OSWER DIRECTIVE 9502.00*60
              INTERIM FINAL

RCRA FACILITY INVESTIGATION (RFI) GUIDANCE

             VOLUME I OF IV
    DEVELOPMENT OF AN RFI WORK PLAN
              AND GENERAL
    .CONSIDERATIONS FOR RCRA FACILITY
             INVESTIGATIONS
            EPA 530/SW-89-031
                MAY 1989
         WASTE MANAGEMENT DIVISION
            OFFICE OF SOLID WASTE
     U.S. ENVIRONMENTAL PROTECTION AGENCY

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                                ABSTRACT
     On November 8, 1984, Congress enacted the Hazardous and  Solid Waste
Amendments (HSWA) to RCRA. Among the most significant provisions of HSWA are
§3004(u), which  requires corrective action  for releases of hazardous waste or
constituents from solid waste management units at hazardous waste treatment,
storage and disposal  facilities seeking final RCRA permits;  and §3004(v), which
compels corrective action for releases that have migrated beyond the facility
property boundary.  EPA will be promulgating rules to implement the corrective
action  provisions of HSWA, including requirements for release investigations and
corrective measures.

     This document, which is presented in  four volumes, provides  guidance to
regulatory agency personnel on overseeing owners or operators of hazardous waste
management facilities in  the conduct of the second phase of the RCRA Corrective
Action  Program, the RCRA Facility Investigation (RFI). Guidance is provided for the
development and performance of an investigation by the facility owner or operator
based on determinations made by the regulatory agency as expressed in  the
schedule of a permit  or  in  an enforcement order issued under §3008(h), §7003,
and/or  §3013. The purpose  of the RFI is to obtain information to fully characterize
the nature,  extent and  rate of migration of releases of  hazardous waste  or
constituents and to interpret this information to determine whether interim
corrective measures and/or a Corrective Measures Study may be necessary.

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                               DISCLAIMER
     This document is intended to assist Regional and State personnel in exercising
the discretion conferred by regulation in developing requirements for the conduct
of RCRA Facility Investigations (RFIs) pursuant to 40 CFR 264. Conformance with this
guidance is expected to result in the development of RFIs that meet the regulatory
standard of adequately detecting and  characterizing the nature and extent of
releases.  However, EPA will not necessarily limit acceptable RFIs to  those that
comport with the guidance set forth  herein.  This document is not a regulation (i.e.,
it does not establish a standard of conduct which has the force of law) and should
not be used as such. Regional and State personnel must exercise their discretion in
using this guidance document as well as other relevant information in determining
whether an RFI meets the regulatory  standard.

     Mention of company or product names in  this document should  not be
considered as an endorsement by the U.S. Environmental Protection Agency.

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                          ACKNOWLEDGEMENTS


     This document was developed by the Waste Management Division  of the

Office of Solid Waste (OSW). George Dixon was the EPA Work Assignment Manager

and Art Day was the Section Chief.  Additional assistance was provided by Lauris
Davies and Paul Cassidy.


     Guidance was also provided by the EPA RFI Work Group, including:


         George Furst, Region I             Janette Hansen, OSW
         Andrew Bellina, Region II           Lisa Feldt, OERR
         William Smith, Region II            Stephen Botts, OECM
         Jack Potosnak, Region III           Chris DeRosa, OHEA
         Douglas McCurry, Region IV        James Durham, OAQPS
         Francine Norling, Region V          Mark Gilbertson, OWPE
         Lydia Boada Clista, Region VI        Nancy Hutzel, OGC
         Karen Flournoy, Region VII          Steve Golian, OERR
         Larry Wapensky, Region VIII         Dave Eberly, OSW
         Julia Bussey, Region IX             Jackie Krieger, OSW
         Melanie Field, Region IX            Lisa Lefferts, OSW
         Jim Breitlow, Region IX             Lisa Ratcliff, OSW
         Paul Day, Region X                 Florence Richardson, OSW
         David Adler, OPPE                  Reva Rubenstein, OSW
         Joanne Bahura, OSW              Steve Sisk, NEIC
     NUS Corporation and Alliance Technologies, Inc. assisted OSW in developing

this document, in partial fulfillment of Contract Nos. 68-01-7310 and 68-01-6871,

respectively.  Tetra  Tech, Inc. and Labat Anderson, Inc. also provided assistance.

Prinicipal contributors included:


         Todd Kimmell, NUS                Tom Grieb, Tetra Tech
         Kurt Sichelstiel, NUS               Nick Pangaro, Alliance
         William Murray, NUS               Linda Marler, Alliance
         Ron Stoner, NUS                   Andrea Mysliki, Labat Anderson
         DaveNavecky, NUS
                                   in

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              RCRA FACILITY INVESTSATION (RFI) GUIDANCE
                            VOLUME I
    DEVELOPMENT OF AN RFI WORK PLAN AND GENERAL CONSIDERATIONS
                 FOR RCRA FACILITY INVESTIGATIONS
                       TABLE OF CONTENTS

SECTION                                                    PAGE
ABSTRACT                                                       i
DISCLAIMER                                                     ii
ACKNOWLEDGEMENTS                                            iii
TABLE OF CONTENTS                                              iv
VOLUME II, III AND IV CONTENTS                                    xiv
TABLES                                                        xv
FIGURES                                                      xvi
LIST OF ACRONYMS                                              xvii
SUMMARY                                                    xix
                               IV

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                   VOLUME I CONTENTS (Continued)
SECTION                                                     PAGE
1.0   OVERVIEW OF THE RCRA CORRECTIVE ACTION                     1-1
     PROGRAM
   1.1   INTRODUCTION                                          1-1
   1.2   OVERALL RCRA CORRECTIVE ACTION PROCESS                   1 -4
   1.3   PURPOSE OF THE RCRA FACILITY INVESTIGATION                1-11
       (RFI) GUIDANCE
   1.4   ORGANIZATION OF THIS DOCUMENT                         1-12
   1.5   REFERENCE INFORMATION                                 1-12
   '..6   GUIDANCE CHANGES DESCRIPTION                          1-14
   1.7   CORRECTIVE ACTION REGULATIONS                          1-18

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                     VOLUME I CONTENTS (Continued)
SECTION                                                            PAGE
2.0.  THE RFI WORK PLAN                                              2-1
   2.1   INTRODUCTION                                               2-1
   2.2   PREPARATION OF AN RFI WORK PLAN                            2-1
     2.2.1  Description of Current Conditions                             2-3
           2.2.1.1    Facility Background                                2-3
           2.2.1.2    Nature and Extent of Contamination                  2-5
           2.2.1.3    Implementation of Interim Corrective                 2-9
                    Measures
     2.2.2  Schedule for Specific RFI Activities                            2-9
     2.2.3  Procedures for Characterizing the Contaminant                2-10
            Source and the Environmental Setting
           2.2.3.1    Contaminant Source Characterization                2-10
           2.2.3.2    Environmental Setting Characterization              2-18
     2.2.4  Monitoring and Data Collection Procedures                   2-18
     2.2.5  Assembling Existing Data to Characterize the                  2-20
            Contaminant Release
     2.2.6  Quality Assurance/Quality Control (QA/QC)                   2-21
            Procedures
     2.2.7  Data Management and Reporting Procedures                  2-22
     2.2.8  Identification of Potential Receptors                          2-22
     2.2.9  Health  and Safety Procedures                               2-25
   2.3   IMPLEMENTATION OF THE RFI WORK PLAN                       2-25
   2.4   EVALUATION BY THE REGULATORY AGENCY                     2-26
                                   VI

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                    VOLUME I CONTENTS (Continued)
SECTION                                                         PAGE
3.0   GENERAL STRATGEGY FOR RELEASE INVESTIGATION                 3-1
   3.1   INTRODUCTION                                             3-1
   3.2   PHASED STRATEGY FOR RELEASE INVESTIGATIONS                3-2
   3.3   DATA QUALITY AND USE                                     3-3
   3.4   PROCEDURES FOR CHARACTERIZING THE                        3-4
        CONTAMINANT SOURCE AND THE ENVIRONMENTAL
        SETTING
     3.4.1  Sources of Existing Information                             3-4
     3.4.2  Waste and Unit Characterization                            3-6
     3.4.3  Characterization of the Environmental Setting                 3-7
     3.4.4  Assembling Available Monitoring Data                       3-9
   3.5   USE OF MODELS      .                                       3-9
     3.5.1  General Applications                                      3-9
     3.5.2  Ground-Water Modeling                                  3-12
   3.6   FORMULATING METHODS AND MONITORING                   3-16
        PROCEDURES
     3.6.1  Monitoring Constituents and Indicator                      3-16
           Parameters
     3.6.2  Use of EPA and Other Methods                             3-24
     3.6.3  Sampling Considerations                                  3-27
           3.6.3.1   General Sampling Considerations                   3-28
           3.6.3.2   Sample Locations and Frequency               '    3-29
           3.6.3.3   Judgmental Sampling                             3-30
           3.6.3.4   Systematic or Random Grid Sampling                3-30
           3.6.3.5   Types of Samples                                3-31
     3.6.4  Analytical Methods and Use of Detection Limits               3-34
   3.7   RFI DECISION POINTS                                        3-35
                                 VII

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                    VOLUME I CONTENTS (Continued)
SECTION                                                          PAGE
4.0    QUALITY ASSURANCE/QUALITY CONTROL PROCEDURES              4-1
  4.1   OVERVIEW                                                  4-1
  4.2   QA/QC PROGRAM DESIGN                                     4-2
  4.3   IMPORTANT CONSIDERATIONS FOR A QA/QC                     4-3
        PROGRAM
      4.3.1  Selection of Field Investigation Teams                        4-3
      4.3.2  Laboratory Selection                                       4-5
      4.3.3  Important Factors to Address                               4-6
  4.4   QA/QC OBJECTIVES AND PROCEDURES                           4-9
      4.4.1  Data Quality and  Use                                      4-9
      4.4.2  Sampling Procedures                                      4-14
      4.4.3  Sample Custody                                          4-15
      4.4.4  Calibration Procedures                                    4-16
      4.4.5  Analytical Procedures                                     4-17
      4.4.6  Data Reduction, Validation, and Reporting                    4-18
      4.4.7  Internal Quality Control Checks                             4-18
      4.4.8  Performance and  Systems Audits                            4-20
      4.4.9  Preventive Maintenance                                   4-20
      4.4.10 Corrective Action for QA/QC Problems                       4-21
      4.4.11 Quality Assurance Reports to Management                   4-22
  4.5   REFERENCES                                                4-22
                                  VIII

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                     VOLUME I CONTENTS (Continued)
SECTION                                                            PAGE
5.0   DATA MANAGEMENT AND REPORTING v                             5-1
   5.1   DATA MANAGEMENT                                          5-1
   5.2   DATA PRESENTATION                                          5-1
     5.2.1  Tables                                                    5-2
           5.2.1.1  Listed (Raw) Data                                   5-2
           5.2.1.2  Sorted Summary Tables                              5-7
     5.2.2  Graphic Presentation of Data                                 5-9
           5.2.2.1  Bar Graphs and Line Graphs                          5-9
           5.2.2.2  Area or Plan Views (Maps)                          5-12
           5.2.2.3  IsopachMaps                                     5-14
           5.2.2.4  Vertical Profiles or Cross-Sections      ,              5-14
           5.2.2.5  Three-Dimensional  Data Plots                       5-22
   5.3   DATA REDUCTION                                            b-22
     5.3.1  Treatment of Replicates                    .               5-22
     5.3.2  Reporting of Outliers                                       5-22
     5.3.3  Reporting of Values Below Detection Limits                   5-25
   5.4   REPORTING                                                  5-25
                                   IX

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                  VOLUME I CONTENTS (Continued)
SECTION                                                    PAGE
6.0   HEALTH AND SAFETY                                        6-1
  6.1   OVERVIEW                                              6-1
  6.2   APPLICABLE HEALTH AND SAFETY REGULATIONS                 6-2
       AND GUIDANCE
  6.3   ELEMENTS OF A HEALTH AND SAFETY PLAN                    6-19
  6.4   USE OF WORK ZONES                                    6-20

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                     VOLUME I CONTENTS (Continued)
SECTION                                                           PAGE
7.0   WASTE AND UNIT CHARACTERIZATION                             7-1
   7.1   OBJECTIVES AND PURPOSES OF WASTE AND UNIT                 7-1
        CHARACTERIZATION
   7.2   WASTE CHARACTERIZATION                                   7-3
     7.2.1  Identification of Relevant Information                        7-3
           7.2.1.1  EPA Waste Listing Background                       7-4
                   Document Information
           7.2.1.2  Facility Information                                7-6
           7.2.1.3  Information on Physical/Chemical                    7-7
                   Characteristics
           7.2.1.4  Verification of Existing Information                   7-9
     7.2.2  Waste Sampling                                           7-9
     7.2.3  Physical/Chemical Waste Characterization                     7-10
   7.3   UNIT CHARACTERIZATION                                    7-11
   7.4   APPLICABLE WASTE SAMPLING METHODS                       7-12
     7.4.1  Sampling Approach                                       7-12
     7.4.2  Sampling Solids                                          7-12
     7.4.3  Sampling Sludges                                         7-17
     7.4.4  Sampling Liquids                                         7-19
                                  XI

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                   VOLUME I CONTENTS (Continued)
SECTION                                                       PAGE
8.0   HEALTH AND ENVIRONMENTAL ASSESSMENT                      8-1
  8.1   OVERVIEW                                                8-1
  8.2   HEALTH AND ENVIRONMENTAL ASSESSMENT                    8-2
        PROCESS
  8.3   DETERMINATION OF EXPOSURE ROUTES                        8-4
  8.4   HEALTH AND ENVIRONMENTAL CRITERIA                       8-7
     8.4.1  Derivation of Health and Environmental Criteria               8-7
     8.4.2  Use of Criterion Values                                  8-13
  8.5   EVALUATION OF CHEMICAL MIXTURES                        8-18
  8.6   EVALUATING DEEP SOIL AND SEDIMENT                       8-20
        CONTAMINATION AND USE OF STATISTICAL
        PROCEDURES FOR EVALUATING GROUND-WATER
        CONTAMINATION
     8.6.1  Deep and Surficial Soil Contamination                      8-20
     8.6.2  Sediment Contamination                                8-23
     8.6.3  Use of Statistical Procedures for Evaluating                  8-24
           Ground-Water Contamination
  8.7   QUALITATIVE ASSESSMENT AND CRITERIA                     8-26
  8.8   INTERIM CORRECTIVE MEASURES                            8-27
  8.9   REFERENCES                                             8-32
  8.10  CRITERIA TABLES AND WORKSHEETS                          8-33
     8.10.1   Criteria Tables                                      8-33
     8.10.2   Worksheets                                        8-59
                                XII

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                     VOLUME I CONTENTS (Continued)


SECTION                                                           PAGE

APPENDICES

Appendix A:   Aerial Photography, Mapping, and Surveying                A-1

Appendix B:   Monitoring Constituents and Indicator                     B-1
              Parameters

           List 1:    Indicator Parameters Generally
                   Applicable to Specific Media

           List 2:    40 CFR 264 Appendix IX Constituents
                   Commonly Found in Contaminated
                   Ground Water and Amenable to
                   Analysis by EPA Method 6010-
                   Inductively Coupled Plasma (ICP)
                   Spectroscopy (Metals) and by Method
                   8240 (Volatile Organics)

           List 3:    Monitoring Constituents Potentially
                   Applicable to Specific Media

           List 4:    Industry-Specific Monitoring
                   Constituents

RFI GUIDANCE FEEDBACK FORM
                                  XIII

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                     VOLUME II. ill AND IV CONTENTS
VOLUME II: SOIL, GROUND WATER AND SUBSURFACE GAS RELEASES
    Soil                    -  Sections
    Ground Water           -  Section 10
    Subsurface Gas          -  Section 11
         Appendix C         -  Geophysical Techniques
         Appendix D         -  Subsurface Gas Migration Model
         Appendix E         -  Estimation of Basement Air Contaminant
                             Concentrations Due to Volatile Components in
                             Ground Water Seeped into the Basement
         Appendix F         -  Method 1312: Synthetic Precipitation Leach
                             Test for Soils
VOLUME III: AIR AND SURFACE WATER RELEASES

    Air                    -  Section 12
    Surface Water           -  Section 13
         Appendix G        -  Draft Air Release Screening Assessment
                             Methodology
         Appendix H        -  Soil Loss Calculation
VOLUME IV: CASE STUDY EXAMPLES

     Introduction            -  Section 14
     Case Studies            -  Section 15
                                  XIV

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                            TABLES (Volume I)
NUMBER                                                          PAGE
   2-1      Containment System Evaluation                           2-13
   2-2      Physical, Chemical and Biological Processes Affecting         2-19
           Contaminant Fate and Transport
   2-3      Some Potential Inter-media Contaminant Transfer
           Pathways                                               2-24
   4-1      Essential Elements of a QA Project Plan                     4-4
   5-1      Uses of Tables and Graphics in a RFI                         5-3
   5-2      Useful Data Presentation Methods                         5-5
   5-3      Sorted Data (Concentration of Volatile Organic
           Compounds in Monitoring Well #32)                       5-8
   5-4      Soil Analyses: Sampling Date 4/26/85                       5-10
   5-5      Calculation of Mean Values for Replicates                   5-24
   7-1      Uses and Limitations of EPA Listing Background Documents   7-5
   7-2      Sampling Methods Summary for Waste Characterization      7-13
   8-1      Some Potential Exposure Routes                           8-6
   8-2      Intake Assumptions for Selected Routes of Exposure          8-8
   8-3      Chemicals and Chemical Groups Having EPA Health Effects    8-16
            Assessment (HEA) Documents
   8-4      Examples of Interim Corrective Measures                    8-30
   8-5      Maximum Contaminant Levels (MCLs) Promulgated Under    8-34
            the Safe Drinking Water Act
   8-6      Health-Based Criteria for Carcinogens                      8-35
   8-7      Health-Based Criteria for Systemic Toxicants                 8-38
   8-8      Water Quality Criteria Summary                           8-42
   8-9      Individual Listing  of Constituents Contained Within          8-49
            Chemical Groups Identified in Table 8-8
   8-10     Drinking Water Standards and Health Advisories             8-51
                                   xv

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                            FIGURES (Volume I)
NUMBER                                                          PAGE
   1-1      RCRA Corrective Action Process                           1-5
   2-1      RCRA Facility Investigation (RFI) Process                    2-2
   2-2      Overlapping Plumes from Adjacent Sources that Contain     2-7
           Different Wastes
   2-3      Discrete Versus Continuous Contaminant Sources            2-16
   3-1      Grid Sampling                                          3-32
   3-2      RFI Decision Points                                      3-36
   5-1      Topographic Map Showing Sampling Locations             5-4
   5-2      Comparison of Line and Bar Graphs                        5-11
   5-3      Phenol Concentrations in Surface Soils (ppm = mg/kg)        5-13
   5-4      Isopleth Map of Soil PCB  Concentrations (ug/kg)             5-15
   5-5      Isopleth Map of Diphenylamine Concentrations in the       5-16
             Vicinity of a SWMU
   5-6      Sand Isopach Map Showing Contours (Isopleths)            5-17
   5-7      Cross Section A-A'- Site Subsurface Profile                  5-18
   5-8      Transect Showing Concentration Isopleths (ug/l)             5-19
   5-9      Plan View of Figure 5-7 Showing Offsets in Cross Section     5-20
   5-10    Fence Diagram of Stratigraphy and Lead (Pb)               5-21
             Concentrations (ppm = mg/kg)
   5-11    Three Dimensional Data  Plot of Soil PCB Concentrations     5-23
             (ug/kg)
   8-1      Hypothetical Facility with individual Solid Waste            8-5
             Management Units and a Contaminant Release
             Originating From One of the Units
                                    XVI

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                           LIST OF ACRONYMS
AA
Al
ASCS
ASTM
BCF
BOD
CAG
CPF
CBI
CEC
CERCLA

CFR
CIR
CM
CMI
CMS
COO
COLIWASA
DNPH
DO
DOT
ECD
EM
EP
EPA
FEMA
FID
Foe
FWS
GC
GC/MS
GPR
HEA
HEEP
HPLC
HSWA
HWM
ICP
ID
Kd
Koc
Kow
LEL
MCL
MM5
MS/MS
NFIP
Atomic Absorption
Soil Adsorption Isotherm Test
Agricultural Stabilization and Conservation Service
American Society for Testing and Materials
Bioconcentration Factor
Biological Oxygen Demand
EPA Carcinogen Assessment Group
Carcinogen Potency Factor
Confidential Business Information
Cation Exchange Capacity
Comprehensive Environmental Response, Compensation, and
Lability Act
Code of Federal Regulations
Color Infrared
Corrective Measures
Corrective Measures Implementation
Corrective Measures Study
Chemical Oxygen Demand
Composite Liquid Waste Sampler
Dinitrophenyl Hydrazine
Dissolved Oxygen
Department of Transportation
Electron Capture Detector
Electromagnetic
Extraction Procedure
Environmental Protection Agency
Federal Emergency Management Agency
Flame lonization Detector
Fraction organic carbon in soil
U.S. Fish and Wildlife Service
Gas Chromatography
Gas Chromatography/Mass Spectroscopy
Ground Penetrating Radar
Health and Environmental Assessment
Health and Environmental Effects Profile
High Pressure Liquid Chromatography
Hazardous and Solid Waste Amendments (to RCRA)
Hazardous Waste Management
Inductively Coupled (Argon) Plasma
Infrared Detector
Soil/Water Partition Coefficient
Organic Carbon Absorption Coefficient
Octanol/Water Partition Coefficient
Lower Explosive Limit
Maximum Contaminant Level
Modified Method 5
Mass Spectroscopy/Mass Spectroscopy
National Flood Insurance Program
                                  XVII

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                   LIST OF ACRONYMS (Continued)


NIOSH         -    National Institute for Occupational Safety and Health
NPDES         -    National Pollutant Discharge Elimination System
OSHA         -    Occupational Safety and Health Administration
OVA          -    Organic Vapor Analyzer
PID           -    Photo lonization Detector
pKa           -    Acid Dissociation Constant
ppb           -    parts per billion
ppm          -    parts per million
PDF           -    Polyurethane Foam
PVC           -    Polyvinyl Chloride
QA/QC        -    Quality Assurance/Quality Control
RCRA         -    Resource Conservation and Recovery Act
RFA           -    RCRA Facility Assessment
RfD           -    Reference Dose
RFI           -    RCRA Facility Investigation
RMCL         -    Recommended Maximum Contaminant Level
RSD           -    Risk Specific Dose
SASS          -    Source Assessment Sampling System
SCBA         -    Self Contained Breathing Apparatus
SCS           -    Soil Conservation Service
SOP           -    Standard Operating Procedure
SWMU         -    Solid Waste Management Unit
TCLP          -    Toxicity Characteristic Leaching Procedure
TEGD         -    Technical Enforcement Guidance Document (EPA, 1986)
TOC          -    Total Organic Carbon
TOT           -    Time of travel
TOX          -    Total Organic Halogen
USGS         -    United States Geologic Survey
USLE          -    Universal Soil Loss Equation
UV           -    Ultraviolet
VOST         -    Volatile Organic Sampling Train
VSP           -    Verticle Seismic Profiling
WQC         -    Water Quality Criteria
                                   XVIII

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                                SUMMARY

     The  Hazardous and  Solid Waste Amendments  (HSWA)  to  the Resource
Conservation and Recovery Act (RCRA) were enacted into law on November 8, 1984.
One of the major provisions (Section  3004(u)) of these amendments  requires
corrective action for releases of hazardous waste or constituents from solid waste
management units (SWMUs) at  hazardous waste treatment, storage, or disposal
facilities.  Under this provision, any facility applying for a RCRA hazardous waste
management facility permit will be subject to a RCRA Facility Assessment (RFA).  The
RFA is conducted by the regulatory agency and is designed to identify SWMUs which
are, or are suspected to be, the source of a release to the environment.  If any such
units are identified, the owner or operator of the facility will be directed to perform
a RCRA Facility Investigation (RFI) to obtain information on the nature and extent of
the release  so that  the need for interim  corrective  measures or a Corrective
Measures Study can be determined.  Information collected during the RFI can  also
be  used by the owner or operator to aid in  formulating  and  implementing
appropriate corrective measures. Such corrective measures may range from
stopping the release through the application of a source control technique to a  full-
scale cleanup  of.the affected  area.   In cases wrere releases are  sufficiently
characterized, the regulatory agency may require the owner or operator to collect
specific information needed to implement corrective measures during the RFI.

     This document provides the owner or operator with guidance on conducting a
RCRA  Facility  Investigation.  Based on  release determinations  made by  the
regulatory agency (generally resulting from the RFA), the owner or operator  of a
facility will be notified, through an enforcement order or  permit  conditions, of
those unit(s) and releases (known or suspected) which must be further investigated.

     This guidance  is divided into  fifteen  sections presented  in  four volumes.
Volume I presents recommended procedures to follow in developing a work plan
for conducting the investigation.  It also describes the criteria that the Agency will
use to interpret the data collected during the RFI. This interpretation is an integral
part of the RFI and  is discussed in Section  8, which  describes the  Health  and
Environmental Assessment (HEA) that is conducted by the Agency. The primary
element of the HEA  is a set of  criteria (chemical concentrations),  against  which
concentrations  of   hazardous  constituents   identified   during  the   release
                                    XIX

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characterization are compared. The health and environmental assessment is used in
determining the need for a Corrective Measures Study (CMS) or Interim Corrective
Measures (ICM), and is based primarily on EPA-established chronic-exposure limits.

     Volumes II and III describe specific  methods for characterizing the nature,
extent, and rate of contaminant release to soil, ground  water, subsurface gas, air,
and surface water.  Each medium-specific section contains an example strategy for
characterizing releases, which includes characterizing the source and environmental
setting of the release, and conducting a monitoring program that will characterize
the release.  Also,  each  section  provides a checklist of information  that may  be
needed for. release characterization, formats for data presentation, and  field
methods that may be used in the investigation.  Highlights of the medium-specific
sections are provided below.

     Section 9 (SOIL)

     •   Gives specific emphasis to the potential for inter-media transfer of
         releases from the soil medium to other media;

     •   Explains  the significance of surficial soil and deep  soil contamination;
         and

     •   Highlights the role of leaching tests.

     Section 10 (GROUND WATER)

     •   References the RCRA Ground Water Monitoring Technical  Enforcement
         Guidance Document (TEGD) to characterize site hydrology;

     •   Encourages  the use of  flow nets for  interactive/verifiable site
         characterization; and

     •   Focuses on basement seepage as an important pathway for contaminant
         migration and exposure.
                                    xx

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     Section 11 (SUBSURACE GAS)

     •    Focuses on methane gas from refuse landfills because of its explosive
          properties, as well as volatiies from underground tanks;

     •    Emphasizes the importance of subsurface gas as a pathway  for inter-
          media transport (e.g., transfer of contamination from subsurface gas to
          soil and air); and

     •    Presents a subsurface gas migration model, detailed in in Appendix D.

     Section 12 (AIR)

     •    Addresses monitoring and modeling of unit emissions and dispersion
          modeling for off-site  receptors  at or  beyond  the  facility property
          boundary; and

     •    Provides an air release screening assessment methodology that may  be
          used as a transition between the general quality determinations made in
          the RCRA Facility Assessment (RFA), regarding air emissions that warrant
          the actual performance of an RFI.

     Section 13 (SURFACE WATER)

     •    Emphasizes the importance of understanding the form and frequency of
          releases to surface water and the role of biomonitoring; and

     •    Explains when sampling bottom sediments is important.

     Volume IV presents a number of case studies selected to illustrate various
concepts and procedures presented in Volume I, II and III. Most of the case studies
are based on actual sites. In some cases, existing data have been supplemented with
hypothetical data to illustrate a particular point.
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     Prior to conducting the investigation, the owner or operator will in most cases
be directed, through a permit or enforcement order, to submit a written plan (the
RFI Work Plan) that should propose, in detail, the manner in which the investigation
will be conducted. Specific components of this plan are defined in Volume t of this
guidance.

     In planning the investigation, the owner or operator should consider a logical
progression of tasks that will be followed in investigating the release.  Generally,
these tasks will consist of:

     •   Gathering information on the source of the release to the environment
         (e.g., gathering information on the unit and the waste in the unit);

     •   Gathering physical information on the environment surrounding the unit
         that will affect the migration and fate of the release (e.g., ground-water
         flow direction, average windspeeds, soil types); and

     •   Using  the above information  along  with any existing monitoring or
         modeling information, to develop a conceptual model of the release,
         which will be used to plan and conduct a monitoring program to define
         the nature, rate and extent of the release.

     The owner or operator should use existing sources of information when  these
sources can supply data of the quality and type needed.  Information on waste
constituents,  for instance, may be available from operational records kept at the
facility. In other instances, the owner or operator may propose a waste sampling
and  analysis  effort to characterize  the  waste  in  the unit  of  concern, thereby
producing new data on the waste.   In either case, the owner or operator should
ensure that the data is of the  quality necessary to adequately define the release
because such  data will be used in determining the need for corrective measures.

     Characterizing the release source and the environmental setting of the release
will allow the owner or operator to design a monitoring program which will lead to
adequate characterization of the release.  This effort may be conducted in phases, if
necessary, with each monitoring phase building on the findings and conclusions of
the previous  phase.  For example, in those cases where the regulatory agency has
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identified a suspected release, the first phase of the monitoring program may be
directed  toward release verification.  The level  of effort required  in an  initial
monitoring phase will thus be dictated by the level of knowledge on the release.
The hypothetical examples of this approach given below illustrate that RFIs can vary
widely in complexity and, thus, will not always involve elaborate studies.

     •   A facility contains both active and inactive landfills.  All active landfills at
         the facility are regulated for ground-water releases under 40 CFR Part
         264,  Subpart F;  however,  an  inactive unit was identified by  the
         regulatory agency as being the source of a release to ground water. The
         waste in  the unit was identified by the owner or operator as  being
         supplied solely by a single, well-characterized process.

         Hydrogeologic information, such as identification of the uppermost
         aquifer and ground-water flow direction and rate,  were defined  in the
         RCRA  Part B  permit  application for  the active  units  required   for
         compliance with  Subpart B  of 40  CFR Part  270.   Environmental
         characterization data relevant to the  inactive landfill, such as flow
         direction  and hydraulic gradient, was  readily derived from monitoring
         wells already installed to comply with the monitoring requirements of 40
         CFR Part 264, Subpart F.

         In this case, the owner or operator was able to use  existing information
         to characterize both the environmental setting and  the source of the
         release and conduct a limited sampling program, starting with wells near
         the inactive unit, to define the release.  After installation and sampling
         of these initial wells,  the owner or operator determined the need  for
         further well installation and sampling.  In this case, the level of  effort
         required  to characterize the release,  especially in characterizing  the
         contaminant source and environmental setting, was minimal due  to the
         detailed information already available.

     •   In another case, the owner or operator of a commercial facility with an
         inactive surface impoundment that had  received  waste from several
         generators was directed to conduct an investigation of  a suspected
         release to a nearby stream.  The suspicion of a release was based  on
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     several fishkills noted in the stream during periods of heavy rains and
     reported observations of impoundment overflow during these periods.
     The owner or operator's knowledge of the impoundment's contents was
     limited due to the varying wastes managed, and a survey of drainage
     patterns around  the impoundment  had not been  performed. Also,
     monitoring of the receiving stream itself had not been conducted at the
     time of the notification.

     In this case, a rather extensive level of effort was required to characterize
     the release.  Because the waste could not be  readily characterized by
     direct sampling due  to its varying nature over  time,  the owner or
     operator proposed to forego a direct waste characterization effort and
     conduct  monitoring  of the  receiving stream  for  the  constituents of
     concern. The owner or operator conducted a survey of drainage patterns
     around  the site,  developed  a conceptual model  of the  release, and
     established a network of monitoring stations.   Initial sampling was
     conducted in drains and swales around the unit, with subsequent
     monitoring taking place in drainage ditches and eventually the stream
     itself, with the design of each sampling effort based on knowledge
     gained from the previous effort.  In addition, because contamination of
     the surface water column coincided with periods of   heavy rains,
     sampling of the water column was conducted during such periods. The
     owner  or operator   also  determined, through  analysis of  samples
     collected in the initial phases, that the waste constituents being released
     were highly water soluble and not likely to adhere to bottom sediments.
     In addition, the owner or operator determined that these constituents
     had a low potential to bioaccumulate. Stream sampling, therefore, was
     limited to water column samples; bottom sediment and biota sampling
     were not performed.

•    During  a  visual site inspection conducted by the regulatory agency as
     part of the RCRA Facility Assessment, evidence was found that ten drums,
     placed in  an unrestricted storage area, were releasing their contents to
     soils surrounding the area. Evidence observed  by the investigative team
     included discolored soils and stressed vegetation. The regulatory agency
     issued a  compliance order  requiring the owner  or operator to
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          immediately remove the drums (as an interim corrective measure) and to
          conduct an investigation of the nature and extent of the contamination.
          The owner or operator complied  with the order for removal  and
          conducted sampling to characterize the waste  in the drums.  After
          identifying the  constituents of the  waste,  the owner or operator
          proposed a work  plan to  characterize  the  release,  starting  with a
          screening survey  of the area using an organic  vapor analyzer (OVA),
          followed  by the collection of samples in  the immediate vicinity of the
          drum storage area, then additional  sampling at progressively further
          distances from the area, if necessary. After collection of three rounds of
          sampling, sufficient data had been gathered to adequately define the
          extent of the release.

     The above three examples illustrate general concepts that may vary on a site-
specific basis.

     The owner or operator should understand that the regulatory agency has a
significant oversight responsibility to ensure the protection of human health and
the environment.   Accordingly,  the regulatory agency may often choose to be
present to observe RFI-related operations, especially field and sampling operations.
Regulatory agency oversight of RFI field  work is very important for ensuring a
quality study.  In planning and conducting the RFI, therefore, the owner or operator
is encouraged to interact closely with the regulatory agency to assure that the  data
supplied during the  investigation and, thus, the interpretation of the data, will be
acceptable. The compliance order or permit conditions requiring the investigation
will specify a schedule for conducting the investigation, including the reporting of
data. The  owner or operator should keep the regulatory agency advised of the
progress of the investigation, including any delays, and changes to, or deletions of
specific investigation activities.

     This document presents guidance specific to  the RFI and  the RFI process.
General  subject  areas which are common  to  many  types of  hazardous waste
management  activities (e.g.,  quality assurance and control, sampling, analytical
methods, health and safety procedures), which  are also important to the  RFI, are
addressed in a summary fashion.  More detailed references on these subject areas
are provided.
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     This RFI Guidance is tailored to the structure and goals of the RCRA Corrective
Action Program. The RFI process described in this document parallels the technical
components of the Remedial Investigation (Rl) and removal guidance issued under
the Comprehensive  Environmental Response, Compensation,  and Liability  Act
(CERCLA). The RFI  Guidance has been developed to address releases from operating
as well as inactive and  closing  units.  When such  releases have been  adequately
characterized, the next  step in the RCRA corrective action process can be initiated
(i.e., determination of the need for corrective measures).

     In  order to  assess the  effectiveness  of  this Guidance Document  an  "RFI
Feedback Questionnaire," is provided at the end of Volume I. This feedback will
also help EPA determine the need for additional guidance.
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                                SECTION 1

            OVERVIEW OF THE RCRA CORRECTIVE ACTION PROGRAM

1.1       Introduction

     The primary objective of the RCRA corrective action program is to clean up
releases of hazardous waste or hazardous constituents at treatment,  storage, or
disposal facilities subject to Subtitle C of RCRA.  "Release" means any spilling,
leaking, pouring, emitting, emptying, discharging, injecting, pumping, escaping,
leaching, dumping, or  disposing  of  hazardous wastes (including  hazardous
constituents) into the environment (including the abandonment or discarding of
barrels, containers, and other dosed receptacles containing hazardous wastes or
hazardous constituents).

     The 1984 Hazardous and Solid Waste Amendments (HSWA) provided EPA with
broad and expanded authorities for ensuring corrective action at facilities subject to
RCRA. Authorities that may be used by EPA to ensure corrective action include:

     •   Section 3004(u) - Corrective Action for Continuing Releases

         Section 3004(u) of HSWA requires that permits issued after the date of
         enactment of HSWA (November 8, 1984) require corrective action for
         releases  of hazardous waste  or  constituents from any solid waste
         management unit (SWMU) at any hazardous waste treatment, storage,
         or disposal facility seeking a permit, regardless of the time  at which
         waste was placed in the unit.

     •   Section 3008(h) - Interim Status Corrective Action Orders

         Section  3008(h)  of HSWA authorizes EPA to issue orders  requiring
         corrective action or to take other appropriate response measures to
         protect human health and the environment based on any information
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         that there is  or  has been  a release  of  hazardous waste  into the
         environment from a facility authorized to operate under Section 3005(e).

     •   Section 3004(v) - Corrective Action Beyond the Facility Boundary

         Section 3004(v) authorizes EPA to require that corrective action be taken
         by the facility owner or operator beyond the facility property boundary
         where necessary to protect human health and  the environment, unless
         the owner or operator demonstrates that he was unable  to  obtain
         permission to undertake such action.

     Section 3005(c)(3) of HSWA (commonly known as the "Omnibus"  provision)
gives EPA authority to add to RCRA permits any conditions deemed necessary to
protect human health and the environment.

     In addition, Section 3004(n) of HSWA directs EPA to set standards for the
control and monitoring of air emissions at hazardous waste treatment, storage, and
disposal facilities as necessary to  protect human health and the environment. These
standards are  presently  being  developed and will  form the overall  basis for
regulating air emissions at these facilities. These standards may be used by EPA in
evaluating  corrective  measures  associated with  air releases at solid  waste
management units. However, until these standards are sufficiently developed, EPA
will use this RFI Guidance  to  address air releases that may require  corrective
measures.

     EPA may also apply  RCRA authorities existing prior to the passage of HSWA to
implement the corrective action program. These authorities include RCRA Sections
3013 and 7003. Section 3013 may be used to order an owner or operator to conduct
monitoring, testing, analysis, and reporting at a facility which is or may be releasing
hazardous waste that may present a substantial hazard  to human health or the
environment. Section 7003 can be applied where hazardous waste management
activities may present an  imminent and substantial endangerment to health or the
environment. Under this provision, the EPA Administrator may bring suit against an
owner or operator to cease activities causing such  endangerment or to take other
appropriate action as may be necessary.
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     Section 3004(u) has been codified as 40 CFR §264.101. A companion to EPA's
July 15, 1985 (see 50 FR 28702), codification rule specifies additional information
and data requirements for owners or operators of sol
support the conduct of RCRA Facility Assessments by
d waste management units to
the regulatory agency (see 52
FR 45788 - December 1,  1987). These authorities broaden the scope of the RCRA
corrective action program from detecting and correcting releases to the uppermost
aquifer from regulated  units, to cleaning  up continuing releases  to  any media
resulting from other waste management units and practices at RCRA facilities. Prior
to passage of HSWA,  EPA exercised its authority under  Section 3004 to require
corrective action for releases of hazardous constituents to  ground water from only
certain land-based waste management units; 40 CFR Part 264, Subpart F contains
requirements for  corrective action  at these "regulated units."   Regulated units
include surface impoundments, landfills, waste piles, and land treatment units that
received hazardous waste on or after July 26, 1982. Also, EPA applied Sections 3013
and 7003, as appropriate, toward meeting corrective action program objectives.
HSWA expanded  RCRA  authority  to correct  releases of hazardous waste or
hazardous constituents to all media at RCRA facilities, and encourages the use of
other authorities, as needed  or appropriate, to help achieve  corrective action
objectives at these facilities.

     Section  3004(u)  of the  HSWA  corrective action   provisions  focuses  on
investigating releases from solid waste management units (SWMUs).  A SWMU is
any discernible unit at which solid or hazardous wastes have been placed at any
time, irrespective of whether the unit was intended for the management of solid or
hazardous wastes. Such  units include any area at  a facility at  which hazardous
wastes or hazardous constituents have been routinely and systematically released.
A SWMU does not include an  accidental spill from production  areas and units in
which wastes have not been managed (e.g., product storage areas).

     This  RFI  Guidance  addresses  investigations  of all  releases  from  SWMUs
(hereafter also referred  to  as units) to all media, including  soil, ground water,
subsurface gas, air, and surface water.  Ground-water releases from regulated units
will continue to be regulated under 40 CFR Part 264, Subpart F.
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1.2       Overall RCRA Corrective Action Process

     The RCRA Corrective Action Process consists primarily of the following four
steps: the RCRA Facility Assessment (RFA), the RCRA Facility Investigation (RFI), the
Corrective Measures Study (CMS), and Corrective Measures Implementation (CMI).
A summary of the overall Corrective Action Process for identifying, characterizing,
and correcting releases is presented in Figure 1-1. This process is discussed below.

RCRA Facility Assessment (RFA)

     Release determinations for all environmental media (i.e., soil, ground water,
subsurface gas, air, or surface water)  will be  made by the regulatory agency
primarily through the RFA process. The regulatory agency will perform the RFA for
each facility seeking a RCRA permit to determine if there  are releases of concern.
The major objectives of the RFA are to:

     •    Identify SWMUs   and collect existing  information  on  contaminant
          releases; and

     •    Identify releases or suspected releases needing further investigation.

     The  RFA begins with  a preliminary  but fairly comprehensive review of
pertinent existing information on the facility. If necessary, the review is followed by
a visual site inspection to verify information obtained in the preliminary review and
to gather information  needed to develop  a sampling  plan.  A  sampling visit is
performed subsequently, if necessary, to obtain appropriate samples for making
release determinations.

     The findings of the RFA will result in one or more of the following actions:

     •    No further action under the RCRA corrective action program is required'
          at that time, because no evidence of release(s) or of suspected release(s)
          was identified;
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   REGULATORY AGENCY performs RCRA Facility Assessment (RFA) to:
      •   Identify solid waste management units (SWMUs) and collect existing information
          on contaminant releases.

      •   Identify releases or suspected releases needing further investigation
   REGULATORY AGENCY specifies permit conditions or issues enforcement order to facility
   owner or operator to:

      •  Perform investigations on releases of concern; and/or

      •  Implement interim corrective measures.
   OWNER OR OPERATOR performs RCRA Facility Investigation (RFI) to verify the release(s), if
   necessary, and to characterize the nature, extent and rate of migration for releases of
   concern. Owner or operator reports results and contacts the regulatory agency
   immediately if interim corrective measures seem warranted.
                                        \
   REGULATORY AGENCY conducts health and environmental assessment based on results
   of RFI and determines the need for interim corrective measures, and/or a Corrective
   Measures Study.
                                        I
   OWNER OR OPERATOR conducts Corrective Measures Study (CMS) as directed by
   regulatory agency and proposes appropriate corrective measures when required by
   regulatory agency.
                                        I
   REGULATORY AGENCY evaluates Corrective Measures Study and specifies appropriate
   corrective measures.
   OWNER OR OPERATOR performs the Corrective Measures Implementation (CMI). This
   includes designing, constructing, operating, maintaining and monitoring the corrective
   measures.
Figure 1-1: RCRA Corrective Action Process.   Note  that although  certain aspects of the
          Corrective Action Process are the responsibility of either the regulatory agency  or
          the owner or operator, close coordination  between the regulatory agency and the
          owner or operator is essential throughout the process.
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     •    An  RFI  by the  facility owner or  operator is  required  where the
          information collected indicates a release(s) or suspected release(s) that
          warrant(s) further investigation;

     •    Interim corrective measures by the owner or operator are required where
          the regulatory agency believes that expedited action should be taken to
          protect human health orthe environment; and

     •    In cases where problems associated with permitted releases are  found,
          the regulatory  agency will  refer such  releases  to  the  appropriate
          permitting authorities.

     Guidance for conducting the RFA is presented in the following reference:
   •
     U.S. EPA.  October, 1986.  RCRA Facility Assessment Guidance.  NTIS  PB 87-
     107769. Office of Solid Waste. Washington, D.C. 20460.

RCRA Facility Investigation (RFI)

     If the regulatory agency determines that an RFI is necessary, this investigation
will be required  of the owner or operator either under a permit  schedule of
compliance or under an enforcement order.  The regulatory agency will apply the
appropriate regulatory authority and develop specific conditions in permits or
enforcement orders. These conditions will generally be based on  results of the RFA
and will identify specific units or releases needing further investigation. The  RFI can
range widely from a small specific activity to  a complex multi-media study.  In any
case, through these conditions, the regulatory agency will  direct the owner or
operator to investigate releases of concern. The investigation may initially involve
verification of suspected releases. If confirmed, further characterization of such
releases will be  necessary. This characterization includes identification of the type
and concentration of hazardous waste or hazardous constituents  released, the rate
and direction at which the releases are migrating, and the distance over which
releases have migrated.  Inter-media transfer of  releases (e.g., volatilization of
hazardous constituents from contaminated soils to the  air medium) should also be
addressed during the RFI, as appropriate.
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     The RFI also  includes interpretation by the regulatory agency  of  release
characterization data to established health and environmental criteria to determine
whether a CMS is necessary. This evaluation is crucial to the RCRA Corrective Action
Process.  The regulatory agency will ensure that data and information collected
during the RFI adequately describe the release and can be used with a high degree
of confidence to make decisions regarding the need for a CMS.

     Identifying  and  implementing  interim  corrective  measures may also  be
conducted during the RFI.  If, in the process of conducting the  investigation, a
condition  is identified that  indicates that  adverse  exposure  to  hazardous
constituents is presently occurring or is imminent, interim corrective measures may
be  needed.   Both the owner or operator  and the regulatory  agency have a
continuing responsibility to identify  and respond to  emergency situations  and to
define priority situations that warrant interim corrective  measures. The need  for
consideration of interim corrective measures, if identified by the owner or operator,
should be communicated to the regulatory agency at the earliest possible time.  As
indicated earlier, the need for interacting closely with the  regulatory agency is very
important, not only for situations discussed above, but also to ensure the adequacy
of the data  collected during the RFI and the appropriate interpretation of those
data.

Corrective Measures Study (CMS)

     If the potential need for corrective measures  is identified  during the  RFI
process, the  owner or operator is then responsible for performing a CMS.  During
this step of the Corrective Action Process, the owner or operator will  identify, and
recommend as appropriate, specific measures to correct the release.

     Information generated during the  RFI will be used not only to determine the
potential need for corrective measures,  but also  to aid  in  the selection and
implementation of these  measures.  For releases  that have  been adequately
characterized, the owner or operator may be required to collect such information
(e.g., engineering data such as soil compaction properties or aquifer pumping tests)
during the RFI.  Selection  and implementation of corrective  measures will  be
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addressed in future regulations and in separate guidance to be developed by EPA.
In the interim, guidance for corrective measures selection and implementation is
provided in several references, including the following:

     U.S.  EPA.   September,  1986.   Data  Requirements for Remedial Action
     Technology Selection.  Final Report. NTIS PB87-110813. Office of Emergency
     and  Remedial  Response  and  Office of  Research  and  Development.
     Washington, D.C. 20460.

     U.S. EPA. October, 1985. Handbook of Remedial Action at Waste Disposal
     Sites.   EPA/625-6-85-006.  Office  of  Emergency  and  Remedial Response.
     Washington, D.C. 20460.

     U.S. EPA. June, 1985.  Guidance on Feasibility Studies Under CERCLA.  NTIS
     PB85-238590. Office of Emergency and Remedial Response. Washington, D.C.
     20460.

     U.S. EPA. June, 1987. RCRA Corrective Action Interim Measures. Interim Final.
     OSWER  Directive  No. 9902.4.  Office of  Waste Programs  Enforcement.
     Washington; D.C. 20460.

     U.S. EPA. May, 1985. Guidance Document for Cleanup of Surface Tanks and
     Drum Sites.  OSWER Directive 9380.0-03. Office of Emergency and Remedial
     Response. Washington, D.C. 20460.

     U.S.  EPA.   June,  1986.   Guidance   Document  for Cleanup of Surface
     Impoundment Sites. OSWER Directive No. 9380-0.06. Office of Emergency and
     Remedial Response. Washington, D.C. 20460.

     U.S. EPA. November, 1986. EPA/540/2-85/004. OSWER Directive No. 9380.0-05.

     U.S. EPA. December, 1988. Guidance on Remedial Actions for Contaminated
     Ground Water at Superfund Sites.  OSWER Directive  No. 9283.1-2. Office of
     Emergency and Remedial Response. Washington, D.C. 20460.
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     EPA has developed a draft of a guide for assessing  and remediating
contaminated sites that directs users toward technical support, potential data
requirements and technologies that are applicable to several EPA programs such as
RCRA and CERCLA.  The reference for this guide and a general discussion of its
content are provided below.

     U.S. EPA.  1989.  Draft Practical Guide for  Assessing and  Remediating
     Contaminated Sites.  Office of Solid  Waste and Emergency  Response.
     Washington, D.C 20460.

     This document is intended as a practical guide and reference source for EPA,
state and industry  personnel that are involved with assessing and remediating
contaminated sites. Special emphasis is placed on technical support, potential data
requirements and technologies related to assessing  and remediating point-source
contamination (e.g., problems associated with landfills, surface impoundments, and
underground storage tanks). The guide is designed to address, in a general manner,
releases to ground water, soil, surface water and air.

     The principal objective of the guide is to facilitate  technology  transfer
regarding the assessment and remediation of contaminated sites. It is anticipated
that the guide will be available in two forms:  (1) as a hard copy, i.e., in three-ring
binder form and (2) stored on computer files within  the OSWER Electronic Bulletin
Board System (BBS). (Note: The OSWER Technology Transfer Bulletin Board Users
Guide is available from OSWER headquarters.)  This  dual format will provide
maximum flexibility to users and  allow timely  revision  of existing text or the
inclusion of supplemental material as appropriate.  The  primary function of the
guide is to direct the user toward references and technical support for detailed
information on program requirements, technical methods, data requirements and
technologies.

     The guide is divided into five sections:  (I) Collection and Evaluation of Site
Information, (II) Remedial Technologies, (111) Technical Assistance  Directory,
(IV) Annotated Bibliography, and  (V) Compendium of  Courses,  Symposia,
Conferences, and Workshops.
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     Section  I   is  subdivided  into  Overview,  Preliminary  Site  Assessment,
Characterization of Contaminant Sources(s) and Environmental Setting, Assessment
of Contaminant Fate and Transport,  Selection, Design  and Implementation  of
Remedial Technologies, and Performance Evaluation of Remedial Technologies.
Brief discussions and tables are provided under these and other subdivisions to
clarify how each phase of assessment/remediation  fits into the overall, iterative
process of collecting and evaluating site information.   The tables,  designed  as
screening tools, relate site information with technologies or methods, or vice versa.
Guidance documents, references and other  technical support are listed after the
preliminary discussions and tables.

     Section II  contains descriptions of specific remedial technologies that are
grouped under four categories:  (1) source  control, (2) withdrawal, injection and
flow control,  (3) water treatment,  and  (4) restoration  of  contaminated  water
supplies and utility/sewer lines.  Each  technology description includes a general
description, application/availability, design and construction considerations, costs,
and references.  In addition, an overview of general references precedes the four
categories of remedial technologies.

     Section III is a technical assistance directory of EPA program, regional, and
research staff that may be contacted to answer specific  questions regarding the
assessment and  remediation of contaminated sites.  The directory  includes the
individual's name, organization within  EPA, area of expertise, mailing address, and
phone number. The directory is intended to foster communication among scientists
and engineers within EPA,  other Federal agencies, industry, and state and local
governments.   Improved access to current scientific advances and  data  on the
application and performance of technologies will likely enhance the  effectiveness
and efficiency of assessment and remediation programs.

     Section IV is an annotated bibliography of guidance documents and references
listed under Sections I and II.  Brief summaries of each document are provided to
assist the reader in selecting the appropriate technical guidance.
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     Section V is a compendium of existing courses, symposia, conferences, and
workshops.  Each course, symposium, conference or workshop description includes
the title, content, contact, and cost.

Corrective Measures Implementation (CMI)

     CMI includes designing, constructing, operating, maintaining, and monitoring
selected corrective measures. As indicated above, selection and implementation of
corrective measures will  be addressed  in  future  regulations and  in  separate
guidance to be developed by EPA.

1.3       Purpose of the RCRA Facility Investigation (RFI) Guidance

     This  document provides  guidance to  regulatory  agency personnel  for
overseeing facility owners  or operators who are required  to  conduct  a  RFI to
characterize the  nature, extent,  and rate of migration of contaminant releases to
soils, ground water, subsurface gas, air, and surface water. It also provides guidance
on the interpretation of results  by the regulatory agency to determine if interim
corrective measures and/or a CMS may be necessary.

     This  RFI Guidance is  not  intended to describe all  activities that may be
undertaken during the RFI. For example, consideration of community relations and
development of a community relations plan are addressed in  other EPA guidances.
This and other items that may be undertaken during the RFI are outlined in the
following document:

     U.S. EPA.   November  1986.   RCRA Corrective Action  Plan.  Interim  Final.
     OSWER Directive No. 9902.4 Office  of Solid Waste and Emergency Response.
     Washington, D.C. 20460.

     This document provides as much procedural specificity  as possible to  clearly
define the owner or operator's responsibilities in  the RFI.  Each situation, however,
is likely to be unique. Site-specific conditions, including the amount and quality of
information available at the  start of the RFI process, the existence of or potential for
actual exposure, and the nature and extent of the release call  for a flexible
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approach to the release investigation. This RFI Guidance is written in this context.
However, some situations may be so complicated and unique that further technical
guidance may be necessary. If this is the case, the owner or operator should contact
the responsible regulatory agency for  assistance.   If necessary, the responsible
regulatory agency will contact EPA Headquarters.

1.4       Organization of this Document

     This guidance is organized into four volumes containing 15 sections and 8
appendices. Volume I contains eight sections: Section 2 provides direction for
preparation of the RFI Work Plan  and procedures for submitting this Plan to the
regulatory agency for review. Section 3  provides guidance on the general strategy
to be employed in  performing  release investigations.  Sections 4, 5, and 6 discuss
Quality Assurance/Quality Control (QA/QC), Data Management and Reporting, and
Health and Safety Procedures,  respectively.  Section 7 discusses how information
from  source (waste and unit)  characterization can be  used  in  the  RFI  process.
Section 8 presents guidance on the interpretation of data collected during the RFI
process, using health and environmental criteria. Guidance for situations that may
require the application of interim corrective measures is also provided in Section 8.

     Volumes II and III provide detailed technical guidance on  how to perform
media-specific  investigations.   Volume  II  presents Sections 9, 10 and  11, which
discuss the soil, ground water, and subsurface gas media, respectively.  Volume III
presents  Sections 12 and  13,  which discuss  the  air and  surface-water  media,
respectively.   Representative  case study illustrations  of various  investigative
approaches and  techniques described in  Volumes I through  III are presented in
Sections 14 and 15 of Volume IV.

1.5       Reference Information

     This document provides guidance  on characterizing-known releases and on
verification of  suspected  releases.  Applicable  field  methods  (e.g., sampling
techniques) and equipment  are described  or referenced,  as appropriate.  This
document  uses, to the extent possible, existing guidances  and  information
developed  in various  EPA programs (e.g.,  Office of  Emergency and Remedial
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Response, Office of Waste Programs Enforcement, Office of Air Quality Planning
and Standards, and Office of Water), as well as State material to assist in performing
release characterizations for the various environmental media.  As such,  many
references are provided which refer the owner or operator to more  complete or
detailed information.  Where available, identification or ordering numbers have
been supplied with these citations.  The following describes these identification
numbers and provides information on how these documents may be obtained.

NTIS:      NTIS  stands for the  National Technical Information  Service.   NTIS
          documents may be obtained by calling (703) 487-4650 or by  writing to
          NTIS at the following address:

          NTIS
          U.S. Department of Commerce
          Springfield, VA  22161

EPA:      Environmental Protection Agency (EPA) Reports  are available through
          EPA's Headquarters or Regional libraries, or by writing to EPA at the
          following address:

          U.S. EPA
          Public Information Center
          401 M. Street, S.W.
          Washington, D.C. 20460

          Many EPA  reports are also available through NTIS.  NTIS  should  be
          contacted for availability information.  The indicated EPA office may also
          be contacted for information by writing to the above address.

OSWER:   OSWER stands for EPA's Office of Solid Waste and Emergency Response.
          Availability information on documents identified by an OSWER Directive
          Number can be obtained by calling EPA's RCRA/Superfund Hotline, at
          (800) 424-9346 (toll-free) or (202) 382-3000.
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GPO:     GPO  stands  for  the U.S.  Government Printing  Office.  Documents
         available through GPO may be obtained by calling GPO at (202) 275-
         3648.

1.6      Guidance Changes Description

    The RFl Guidance has undergone a number of revisions since publication of the
initial October 1986 draft.  Draft documents were released to the public in July
1987,  December 1987 (updated Section 8 - Health and Environmental Assessment
only), and  of course the  current  version,  May 1989.  These  revisions  were
necessitated by both the need to remain consistent with evolving EPA policy with
respect to corrective action, and the desire to provide facility owners and operators
with sufficient information and guidance to ensure  that investigations provide
adequate information for confident decisionmaking.  Further revision of the RFl
Guidance is not anticipated. Following is a brief discussion of how the RFl Guidance
has changed since its original release.

     October 1986 Draft - This was the first draft of the RFl Guidance. It contained
basic information on the conduct of RFIs, but did not go into great detail on media
specific investigations, particularly with respect to the air and surface water media.
In addition, this first draft contained little  guidance pertaining to health and
environmental assessment. This draft was circulated mainly to the EPA Regions, in
an attempt to obtain comment before further development of the Guidance was
initiated. As a result of this activity, the need for major revision was identified.

    * July 1987 Draft - This version of the RFl Guidance represented the first  major
revision made to the  Guidance.  Virtually all  sections  were restructured for
consistency and new sections were  added as well.   The major changes were as
follows:

     •   Revision of much of the regulatory and procedural  aspects of the
         Guidance (contained in  Volume I) to reflect the final RCRA Facility
         Assessment (RFA) Guidance.
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•    Introduction of a new,  more efficient  means of selecting hazardous
     constituents and parameters  to monitor  for,  based  on available
     information on the unit(s)  involved, the waste managed, the media
     being investigated and any previous data collected.

•    Addition of guidance relating to the selection of methods for sampling
     and analysis, and incorporation of references to available information
     regarding  acceptable methods already  published by EPA's Superfund
     Program.

•    Addition of new section on health and environmental  assessment
     (Section 8), including tables of action levels for specific constituents in
     specific media.

•    Major editing of all medium specific sections for consistency in structure
     and overall content.

•    Expansion  of all medium specific sections to address the importance of
     inter-media transport of contamination.

•    Expansion  of the Soil Section (Section 9) to emphasize the importance of
     recognizing  soil  as  a   key  medium  for  inter-media  transfer  of
     contamination, both as a source and as a recipient of contamination.

•    Expansion  of the Ground Water Section (Section 10) to provide guidance
     on the use of flow nets and flow cells in defining site hydrogeology and
     contamination migration pathways.

•    Complete  rewrite of the Air Section (Section  12) to reflect the special
     considerations inherent in investigations of releases to air, and evolving
     Agency policy regarding renewed emphasis on monitoring vs modeling.

•    Complete  rewrite of Surface Water Section (Section 13)  to reflect the
     importance of  understanding  the  release  mechanism  (i.e.,  past vs
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          intermittent vs continual  release), and the type of release (i.e., point
          source vs area source).

     •    Addition of new Volume IV - Case Studies.

December 1987 Draft - This revision of the RFI Guidance involved only Section 8 on
Health and Environmental Assessment.  Hence, only Section 8 was reissued. The
major revisions made to Section 8 are summarized as follows:

     •    Clarification of the hierarchy in which the health and environmental
          criteria (i.e., action levels) are applied.

     •    Revision of the criteria tables to reflect new exposure assumptions for
          the soil medium.

     •    Revision of the criteria tables to reflect the latest additions and revisions
          made by EPA to health based exposure levels.

     •    Addition of new guidance pertaining to  evaluation of deep soil and
          sediment contamination.

     •    Update in accordance with new MCLs promulgated for volatile organic
          constituents.

May 1989 Final Draft - The current final draft of  the  RFI Guidance constitutes
significant revision over the previous drafts.  Major changes from previous drafts
include the following:

     •    Incorporation   of  improved   graphics  and  tabular  presentations
          throughout all four volumes of the Guidance.

     •    Incorporation of an RFI Guidance Feedback Form (at the end of Volume
          1) to determine the utility of the Guidance as well as the need for further
          guidance.
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•    General revision, where appropriate, to ensure consistency  with  the
     forthcoming regulations dealing with RCRA corrective action.

•    Revision of the Section 8 criteria  tables to reflect revised  exposure
     assumptions for the soil medium.

•    Revision of the Section 8 criteria tables to reflect the latest additions and
     revisions made by EPA to health based exposure levels.

•    Incorporation of the concept of using leaching tests (Section 9 - Soil) to
     predict when  soil contamination may affect underlying  ground water,
     including a new appendix (Appendix F) presenting  a draft  EPA method
     developed specifically for contaminated soil.

•    Addition of a  new appendix (Appendix E) illustrating the calculation of
     basement air contaminant concentrations due to basement seepage of
     volatile organic contaminants.

•    Addition  of  a new  section  (Section  8.6.3)  pertaining to  r^wly
     promulgated methods for evaluating ground-water contamination in a
     statistical manner,  and  reference  to  additional  guidances and  other
     documents   available  from   EPA   for  conducting   ground-water
     remediation (Section 10.7).

•    Revision of the Air Section of the Guidance (Section 12) to reflect a new
     phased approach, involving  an initial screening assessment, and  the
     incorporation  of  a new  appendix  (Appendix  G) containing  draft
     Guidance on the screening assessment.

•    Revision of the Air Section (Section 12) to reflect a balance between the
     application of modeling and monitoring approaches, depending on site-
     specific circumstances.
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          Incorporation of the concept of using soil loss equations for determining
          contaminated soil loading to surface waters (Section 13), including a new
          appendix (Appendix H) illustrating the soil loss calculation.

          Rearrangement of the Volume IV Case Studies to reflect the order in
          which the specific points illustrated are presented  in Volumes I through
     •    Incorporation of a new Volume IV case study illustrating  the use of
          leaching  tests to  predict the  potential  for contaminated  soil  to
          contaminate underlying ground water.

1.7       Corrective Action Regulations

     EPA  is in the process of  promulgating comprehensive corrective action
regulations pursuant to HSWA Section 3004 (u) and (v). These regulations, which
will appear primarily in Subpart S of 40 CFR Part 264, will establish requirements for
all aspects of RCRA  corrective action. Because the RFI Guidance is being  released
prior to the proposal and promulgation of Subpart S, the potential for differences is
significant.  Therefore, users of this guidance  are  advised to review the  final
Subpart S rule carefully when published. Potential differences are identified below:

     •    Identification of  health and environmental criteria or "action  levels"  -
          The RFI Guidance includes tables of  the  most recent action  levels in
          Section 8, Health and Environmental Assessment. However,  these levels
          are continually being updated by EPA, and the levels presented in the
          Subpart S rule may differ.

     •    Development of  health and environmental criteria - The RFI Guidance
          provides  information on how action levels are developed (e.g., use of
          exposure  assumptions, risk levels for carcinogens). The Subpart S rule
          may propose alternate methods for developing actions levels.
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•    Definition of constituent - The  RFI Guidance  refers to constituents as
     those listed  in  40 CFR  Part  261,  Appendix  VIII.   Use of the  term
     "constituent" in the Subpart S rule is being reviewed.

•    Action levels for surface water - The RFI Guidance identifies action levels
     for surface water to include various Agency-developed criteria (such as
     MCLs),  but  indicates  that State-developed  standards  may  also  be
     considered.  The Subpart S rule may propose a  different scheme for
     establishing action levels for surface water.

•    Action levels for soil - The RFI Guidance attempts to differentiate deep
     from surficial soil contamination, and provide methods (e.g., leaching
     tests) and action levels for determining the  need for corrective action.
     Surficial soil and deep soil contamination may be addressed differently in
     the Subpart S rule.

•    Influence of detection/quantitation limits on action  levels -  The RFI
     Guidance indicates that the detection limit will serve as the action level,
     where action levels are  lower  than detection  limits.   The  issue of
     detection/quantitation limits  is  under  Agency review,  and  may  be
     changed in the Subpart S rule.

•    Evaluation  of chemical  mixtures - The  RFI  Guidance  provides  the
     rationale and equations for computing adjusted action levels, assuming
     additive toxicity, when  more than one  constituent is  present  in  a
     contaminated medium.  The issue of evaluation of chemical mixtures is
     under Agency review and may be addressed  differently in the Subpart S
     rule.

•    Definition of Solid Waste Management Unit (SWMU) - The RFI Guidance
     definition  of SWMU is currently under Agency review and  may be
     changed in the Subpart S rule.

•    Notification and Reporting - The RFI Guidance  identifies specific reports
     that may be required throughout the performance of an RFI, and also
                               1-19

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     identifies specific situations in which the owner or operator is required to
     submit notifications  to  the  regulatory  agency.   Notification  and
     reporting requirements are being reviewed by EPA and may be changed
     in the SubpartS rule.

•    Use of specific language - The specific language used in various sections
     of the RFI Guidance, for  example when  referring  to factors the
     regulatory agency may consider in  determining  the need for  interim
     corrective measures, may be changed in the Subpart S rule.
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                                SECTION 2

                            THE RFI WORK PLAN
2.1        Introduction

     If notified by the regulatory agency that an RFI must be conducted, the owner
or operator should  initiate a series  of activities  aimed at  supplying  specific
information on the identified, suspected,  or known  releases  of concern.  Such
activities can include  release verification and characterization. Conducting the RFI
should follow a logical sequence of actions involving the preparation and submittal
of  an  RFI  Work  Plan,  including  development of  a  monitoring  approach,
performance of investigatory tasks, submission of results, and  interactions with the
regulatory agency on courses of further action. The overall RFI process is shown in
Figure 2-1.

     As indicated previously, ?ach RFI situation  is likely to be unique in various
respects, including the unit or units releasing, the media affected, the extent of the
release, the potential for inter-media impacts, the amount and quality of existing
information, and  other factors. The amount of work that may be involved in the
RFI, and therefore the content of the RFI Work Plan, is also likely to vary.  This
section provides guidance concerning the general content of the RFI Work Plan.

2.2        Preparation of an RFI Work Plan

     The RFI Work Plan is a detailed plan that the facility owner or operator should
develop and follow throughout the RFI  that will lead to characterization of the
nature, extent, and rate of  migration of a release of hazardous waste or hazardous
constituents. This plan consists of a number of components that may be developed
and submitted either concurrently or sequentially in  accordance with the  schedule
specified in  the  permit or compliance order. These  components  are shown  in
the top box  of  Figure 2-1. Development  and, therefore, submittal  of specific
plan  components  (e.g., detailed  monitoring  procedures) may  not be required
                                    2-1

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  Owner or Operator submits RF! Work Plan to regulatory agency for review  Plan snould
  include:

      Description of Current Conditions (see Section 2.2.1)

  -   A Schedule for Specific RFI Activities (see Section 2 2.2)

      RFI Strategy:

      •   Procedures for  Characterizing  the Contaminant Source,  the Environmental
          Setting and Assembling Available Monitoring Data (see Sections 2.2.3 and 2.2.5)
      •   Monitoring and Data Collection Procedures (see Section 2.2.4)

      Quality Assurance/Quality Control Procedures (see Section 2.2.6)

      Data Management and Reporting Procedures (see Section 2.2.7)

      Identification  of Potential Receptors (see Section 2.2.8)

      Health and Safety Procedures (Optional) (see Section 2.2.9)

      Other Information if Specified by the Regulatory Agency
                                            I
 Owner or Operator implements RFI Work Plan by conducting appropriate activities and
 reports  release-specific results to regulatory agency for review.*
 Regulatory Agency evaluates   release-specific   results and makes the  appropriate
 determinations.
  No further
    action
  necessary^
                              i
Begin Corrective
Measures Study
    (CMS)d
   Implement
interim corrective
   measures*
                                                         i
  Further
information
 necessary
a   in some cases, existing information may be adequate to characterize specific releases

b   The owner or operator also has a continuing responsibility to identify and respond to emergency situations and to
    define priority situations that may warrant interim corrective measures.


C   No further action will be necessary where  a suspected release s shown to not be an actual release based on an
    adequate amount of monitoring data or wnere release concentrations are shown to be below levels of concern for a
    sufficient period of time

d   implies release concentrations were observed to be equal to or above health and environmental assessment criteria,
    or that there was a reasonable likelihood of this occurring.


6   interim corrective measures may also be implemented prior to or during the RFI, as necessary.


             FIGURE 2-1. RCRA FACILITY INVESTIGATION (RFI) PROCESS.
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until adequate information on the contaminant source and environmental setting is
gathered and evaluated.  Discussion on RF! reporting and schedules between the
owner or operator and regulatory agency is encouraged.

     The owner or operator should be guided by the information contained in the
RFA  Report and the  conditions specified  in the permit or compliance order in
developing the  RFI Work Plan.  These conditions will usually indicate which units
and releases are to be addressed in the RFI (based on the findings of the regulatory
agency during the RFA), as well as which media are of concern.  In most cases, the
information contained in the  RFA Report and the conditions specified in the order
or permit will enable the owner or operator to develop a sufficiently focused RFI
Work Plan. However, if additional guidance is needed by the owner or operator,
consultation with the regulatory agency is advised.

2.2.1      Description of Current Conditions

     As part  of the RFI  Work  Plan, the owner or operator should  provide
background  information  pertinent to the facility,  contamination, and interim
corrective  measures  as  described below.   Data gathered during  any previous
investigations or inspections  and other relevant data should be included.  The
owner or operator should consult with the regulatory agency to determine if any of
these information items are  irrelevant or have already been submitted in  an
appropriate  format  for  other  purposes (e.g.,  contained  in  a  RCRA  permit
application).

2.2.1.1    Facility Background

     The owner or operator  should  summarize the regional location, pertinent
boundary features, general physiography, hydrogeology, and historical  use of the
facility for the treatment,  storage or  disposal of solid and hazardous waste.  This
information should include the following:

     •    Map(s) depicting:

              General geographic location;
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              Property lines, with the owners of all adjacent  property  clearly
              indicated;

              Topography and surface drainage (with an appropriate  contour
              interval and a scale of 1 inch =  100 feet) depicting all waterways,
              wetlands, floodplains,  water features, drainage patterns,  and
              surface-water containment areas;

              All tanks, buildings, utilities, paved areas, easements, rights-of-way,
              and other features;

              All solid or hazardous waste treatment, storage or disposal areas
              active after November 19,1980;

              All known  past solid or hazardous waste treatment,  storage  or
              disposal areas regardless of whether they were active on November
              19,1980;

              All known past and present product and waste underground tanks
              or piping;

              Surrounding   land  uses  (residential,  commercial,  agricultural,
              recreational);

              The location of all production and ground-water monitoring wells.
              These wells shall be clearly labeled and ground and top of casing
              elevations and construction details included (these elevations and
              details may be included as an attachment); and

              Location of any injection wells onsite or near the facility.

     All maps should be consistent with the requirements set  forth in 40 CFR
§270.14 and be of sufficient detail and accuracy to locate and report all current and
future work performed at the site including
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     •    A history  and  description  of ownership  and  operation,  solid and
          hazardous waste  generation,  and  treatment,  storage  and disposal
          activities at the facility;

     •    Approximate  dates  or  periods  of past  product  and  waste  spills,
          identification  of the materials spilled, the amount spilled, the location
          where spilled, and a description of the response actions conducted (local,
          state,  or Federal  response units or private parties), including any
          inspection  reports or technical reports generated as a  result of the
          response; and

     •    A summary of past permits requested and/or received, any enforcement
          actions and their subsequent  responses, and a list of documents and
          studies prepared for the facility.

2.2.1.2    Nature and Extent of Contamination

     The owner or operator should describe any existing information on the nature
and extent of releases, including

     •    A summary of all possible source areas of contamination.  This, at a
          minimum,  should include all regulated units, solid waste  management
          units, spill areas, and other suspected source  areas of contamination.  For
          each area, the owner or operator should identify the following:

              Location of unit/area (which should be depicted on a facility map);

              Quantities of solid and hazardous wastes;

              Hazardous waste or constituents, to the extent known; and

              Identification of areas where additional information is  or may  be
              necessary.

     •    A description of the degree and extent of  contamination. This should
          include
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              Available monitoring data and qualitative information on locations
              and levels of contamination at the facility;

              All  potential  migration  pathways  including  information  on
              geology, pedology, hydrogeology, physiography, hydrology, water
              quality, meteorology, and air quality; and

              The potential  impact(s)  on  human health and the environment,
              including demography, ground-water and surface-water use, and
              land use.

     The surface configuration of contaminant sources both on and off the site may
impact  assessment and  remediation  by  contributing  to the  complexity  of
contamination.  Technical factors such  as contaminant migration potential, the
ability to withdraw or treat contaminants, and the effectiveness o* treatment trains
can  be significantly  altered by the  interaction  of  releases from  different
contaminant sources.  Well-developed maps showing the number, spacing, and
relative positions of  contaminant sources  are  essential to the planning and
implementation of assessment and remediation activities. In addition to map and
field inspections, remote  sensing, surface geophysical methods, and Geographic
Information Systems are useful site evaluation tools.  Information obtained from
these site screening methods will help direct subsequent, more intensive activities
to the major areas of concern.

     Assessment activities may be subtly affected by the surface configuration of
contaminant sources  at the site.  Figure 2-2 shows  an example of overlapping
ground-water contamination plumes from adjacent sources that contain different
wastes. Organic solvents from Source  A  may facilitate the movement of otherwise
low-mobility constituents from Source B.  Contaminants from Source B, that  are
fairly insoluble in water, dissolve readily when in contact with solvents from Source
A.   This  process is  described  as  co-solvation.   Examples  of other potential
complications in the ground water  medium include heavy metal  transport by
complexation,  particle transport, biotransformation,  clogging  of media  pores or
filtering devices by particulates,  and changes in subsurface adsorptive properties.
These and other factors suggest that an approach that focuses only on individual
                                    2-6

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contaminant sources without considering potential interactions between sources
may lead to improper assessment and remediation. Additional information on this
subject is provided in the following reference:

     Keely, J.F.  January,  1987.  The Use of Models In Managing Ground-Water
     Protection  Programs.   EPA/600/8-87/003.    EPA Office  of Research  and
     Development. Washington, D.C. 20460.

     The extent of contamination at a site  can be viewed in two ways.  First the
extent can be examined from a spatial perspective, i.e., where is the contamination
located  and what are its  approximate dimensions?   Second, the extent of
contamination can be viewed from a toxicity or concentration level perspective, i.e.,
to what degree is the medium (e.g., soil, aquifer) "damaged" or contaminated?
Chemical isopleth maps (discussed in  Section 5)  can  be  used  to represent both
components of  contamination  over a given  area.  Each perspective should be
considered because both can influence ground-water remedy selection, and on a
larger scale, future land use.

     Data  on the extent of contamination are  gathered through a variety of
analytical devices and methods, such as monitoring wells, soil  gas monitoring,
ambient air monitoring, modeling and geophysical techniques. As in all cases, a
more extensive monitoring system allows for better delineation of the contaminant
release. Economic considerations force investigators to obtain a maximum amount
of information from assessment activities.  With this in mind, areal photographs,
color infrared imagery and other more sophisitcated remote sensing imagery may
be useful in defining vegetation stress or other environmental indicators that aid in
delineating the extent of contamination.

     The vertical extent of contamination should  also be  considered in defining a
release. For ground water, the vadose zone, uppermost  aquifer,  and if affected,
other proximal  interconnected aquifers and surface-water. bodies, should be
considered as an integral part of every ground-water decontamination process. The
importance of controlling and cleaning up contamination within the vadose zone is
well documented. Often,  ground-water pollution abatement efforts are  inhibited
by percolating waters that collect leachate or products in a contaminated vadose
zone and advance down to the water table.  At this point, the initial ground-water
                                   2-8

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clean  up attempt must be repeated causing additional problems and  costs.  To
prevent continued loss of ground-water quality,  vadose  zone decontamination
should be initiated and regarded as an important component of the ground-water
remediation process.

     Cross media effects  also play an  important  role in defining  the  extent of
contamination. Air, soil, surface-water, and ground-water quality are all potentially
threatened by any contaminant release within  the environment.  Contaminants
transported inconspicuously from a seemingly confined media to another may harm
ecosystems  or humans simply because the migration  was not anticipated.  Both
natural  pathways between media and those created by anthropogenic features
(e.g.,  improperly constructed  monitoring  wells)  may increase the extent of
contamination. For these reasons the complex interactions between environmental
media should not be overlooked.

2.2.1.3   Implementation of Interim Corrective Measures

     The owner  or operator should document  interim corrective measures that
were or are being undertaken at the facility. This should include

              Objectives of the interim measures, including  how the measure is
              mitigating a potential threatto human health and the environment
              and/or is consistent with and integrated into any long-term solution
              at the facility;

              Design, construction, operation, and maintenance requirements;

              Schedules for design, construction and monitoring; and

              Schedule for progress reports.

2.2.2     Schedule for Specific RFI Activities

     In the RFI Work Plan, the owner or operator should  propose a schedule for
completing the RFI within th« time frame of the order or  permit schedule of
compliance. The schedule should be as specific as possible and should indicate dates
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for submittal of the various components of the RFI Work Plan, dates for starting and
accomplishing specific  tasks associated  with  the RFI, and dates for reporting
information from specific tasks to the regulatory agency.

2.2.3      Procedures  for  Characterizing  the  Contaminant Source and  the
          Environmental Setting

     Prior to  establishing monitoring procedures to provide data on the release,
certain information should be acquired to determine constituents of concern and
appropriate  sampling   locations.    Two  key  areas   should   be  addressed:
characterization of the source (i.e., waste and unit), and characterization of the
environmental setting.  These areas are described in general terms below. They are
also described in detail in each  of the media-specific sections.

2.2.3.1     Contaminant Source Characterization

     Characterization  of the  unit(s) and associated waste may be  necessary  to
identify applicable monitoring constituents or useful indicator parameters for the
release characterization. Design and operational information on the unit, such as
unit  size and  amount of waste managed therein, may be necessary to determine
release rates.

     In some cases, adequate characterization of the waste in the unit can be made
by evaluating existing  waste management records or data  on  the process
generating the waste.  In other  cases,  a  sampling and analysis effort  may  be
necessary. If so, the owner or operator should define the sampling and analysis
effort in regard to:

     •     Constituents, analytical methods, detection limits, and  the rationale for
          their selection;

     •     Sampling methods,  sampling locations, equipment, and schedule; and

     •     Pertinent QA/QC procedures to ensure valid waste characterization.
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     Identification of monitoring constituents and use of indicator parameters are
discussed further in Section 3  and supported  by Appendix  B.  Waste and  unit
characterization methods, including sampling,  are described  in Section 7.  QA/QC
procedures are described in Section 4.

     Unit characterization should include information such  as construction  pro-
cedures and materials, and liner specifications, if applicable. Such information  may
be important in evaluating the probable degree  of contamination from the unit,
and consequently, the probable type and severity of the release.

     Waste characterization will not always provide complete information for use
in identifying monitoring  constituents.  This may be especially true for old units,
where significant degradation of constituents  may have occurred, and for those
units that have received many different types of  waste, where it is difficult to be
sure that all wastes in the unit were sampled and analyzed. The owner or operator
should be aware of these possibilities. Further guidance on appropriate procedures
in these cases is provided in Sections 3 and 7.

     Important data on individual sources also includes the condition of the source,
the spatial distribution of the source,  and waste management practices.   The
condition of a  source  may significantly affect its capacity  to contaminate the
surrounding environment. Evaluating and controlling contaminant sources early on
may significantly reduce the costs of assessment and remediation.

     Waste  treatment,   storage  and* disposal   units  (e.g.,  landfills,   surface
impoundments, and waste piles, etc.) that do not have containment systems are, of
course, more susceptible to the release of contaminants. If there is no cover or liner
present,  the  release of constituents  from  a  unit will  largely depend  on  site
characteristics (e.g., infiltration,  hydrogeology) and  contaminant characteristics
(e.g.,  solubility,  specific gravity),  which are discussed in later sections.  Source
control  technologies such as  cover  installation, waste removal, in  situ waste
treatment,  or subsurface barrier  construction  may be appropriate when no
containment system is present.

     When a containment system is  present,  it is appropriate to evaluate the
condition of the system to determine if modifications could significantly reduce or
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prevent further releases.  Table 2-1 presents an outline <• scribing some of the
important  characteristics  of  waste  treatment,   storage  and   disposal  unit
containment systems that should be evaluated.  The degree of modification to a
source will largely depend on contaminant migration potential, exposure potential,
and the feasibility of implementing remedial measures, which in turn are affected
by .site hydrogeology, land use, waste characteristics, and other factors.

     The three-dimensional distribution  of each source should also be carefully
delineated to focus remedial activities on the site's "hot spots" (i.e., those regions
with the highest concentrations of contaminants). Cleaning up contaminated sites
without identifying, defining  and characterizing  these  hot spots may  lead to
ineffective, inefficient remediation  attempts.   Innovative technologies  such as
specialized coring methods (see Section 9), geophysical methods (see Section 10 and
Appendix C), and soil gas sampling devices (see Section 11) may  provide better
resolution of these hot spots than more  conventional methods and devices (e.g.,
monitoring wells, and split-spoon samplers).

     The manner in which wastes are managed may significantly affect the nature
and extent of contamination by influencing the spatial and temporal variability of
contaminant  releases.    Important factors  to  consider  when  characterizing
contaminant sources include the total quantity of wastes, the location and timing of
waste  management, waste and constituent characteristics,  and  general waste
management practices.

     As indicated previously, the total quantity of contaminants within a source is
an  obvious  yet  important   consideration   when  assessing  or remediating
contamination.  In general, the potential extent of contamination is proportional to
the volume of wastes managed in the source, taking into account other factors such
as hydrogeologic setting, exposure potential, and the condition of the source.

     In addition, the location of waste treatment, storage, and disposal units may
affect the type and degree of remedial measures.  In  addition  to the  surface
configuration of sources, the location of different quantities and types of waste
within a source may affect the potential for release.  For instance, low pH liquid
waste placed near wastes containing heavy metals may promote the migration of
the metal cations by increasing their solubility.
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         TABLE 2-1. CONTAINMENT SYSTEM EVALUATION

I.  Coveri
   A. Characteristics of the soil to be used in the cover
   B. Cover and surrounding land topography
   C. Climate characteristics
   D. Composition of the cover
      1.  Component type
      2.  Component thickness
   E. Cover design and construction practices
   F.  Cover configuration
   G. Cover drainage characteristics
      1.  Material used in drainage system
      2.  Thickness of drainage system
      3.  Slope of the drainage system
   H. Vegetative cover
   I.  Post-closur} maintenance
      1.  Cap system
         a. Adequate vegetative cover
         b. Erosion
         c. Settlement/subsidence
      2.  Run-on and run-off control system
         a. Adequate vegetative cover
         b. Erosion
         c. Flow obstructions
II.  Liner and Leachate Collection/Detection System
   A. The number of liners
  Information in this section was in part obtained from EPA's
  technical resource document, Evaluating Cover Systems for Solid
  and Hazardous Waste. SW-867,1982.
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TABLE 2-1.  CONTAINMENT SYSTEM EVALUATION (Continued)

B.  The type and thickness of the liners
   1.  The compatibility of the liners with the waste type
   2.  The structural strength of the liners
   3.  The liner foundation
C.  The age and installation methods of the liners
D.  Description of leachate collection system
   1.  Thickness of drainage layer
   2.  Material used in the drainage system
   3.  Slope of the collection system
   4.  Method of leachate collection
   5.  Method of leachate withdrawal
E.  Description of leak detection system
   1.  Thickness of detection system
   2.  Material used in the system
   3.  Slope of the detection system
   4.  Method of leak detection
   5.  Ability to withdraw leachate from the system
Other Factors
A. Compatibility of bottom-most liner with the underlying
   geology
B.  Relationship of the ground-water table to the bottom liner
C.  Water content (percent solids and free liquids content)
D. Compatibility of waste with containment system (or underlying
   soil, if no containment system is present)
E.  Waste load on the containment system
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     Transportation of wastes on and off site is an equally important consideration.
For instance, a buried transmission line may rupture and release contaminants to
the subsurface. Vehicles conveying wastes to, from, or within a site may spill or leak
substances  onto  the ground  and  eventually cause subsurface  contamination.
Carefully maintained records of waste transportation or field inspections may reveal
such potential leaks or spills.

     The timing  of  waste  management also is important  in  assessing  and
remediating site contamination.  Two aspects of timing are important to recognize
here: the age of the source and the history of waste management. Both aspects
may affect the timing, nature, and degree of assessment and remediation.

     Due to the generally slow movement of some types  of contamination (e.g.,
ground water plumes), releases covering a large area are more likely  to originate
from older sources (i.e., sources that have managed wastes for long periods or at
previous times). Older sources are generally harder to define and characterize due
the paucity of waste management data and little, if any, containment features.
Newer units, on the other hand, are more likely "3 have accurate management
records and improved design features for containment.  Remediation  for an older
source contaminating  the ground water,  for example, may involve substantial
plume control, aquifer restoration, and capping of large areas of contaminated soil.
On the other hand, a recently detected  leak from a new source may be abated by
minor containment system repair, with  little or no aquifer restoration and  plume
control required.

     The history of waste management  for a specific source affects assessment and
remediation by influencing  the  source's capacity to contaminate  over time. In
addition to the spatial variability of wastes, the temporal  variability of waste
management  should  be considered.  Sources may  form  discrete  or continuous
plumes, depending on the history of waste management.  As shown in Figure 2-3,
the configuration of ground-water contamination may be profoundly affected by
the timing  of releases.  Assessment  and remediation  of  contamination  are
consequently  aided by understanding the  history of  waste  management for
individual sources.
                                   2-15

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t
 o
  I
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     In some cases, altering the timing of waste management may be an effective
source control measure.  For instance, placement of wastes in landfill cells without
covers may be limited to anticipated dry periods.  By doing so, the amount  of
moisture in contact with wastes may be significantly reduced, thus minimizing the
potential for contaminant migration.

     Specific characteristics of waste and constituents affecting the assessment and
remediation of contamination in specific media are discussed in the media specific
sections of this guidance. These characteristics include the compatibility of wastes
with the  unit, the  containment system (if any), the underlying  geology, and
interactions  between   different  wastes  and   constituents.    Assessing  the
characteristics of wastes and constituents in conjunction with data on the condition
of the source  and site  hydrogeology may aid  assessment and remediation  by
identifying problems  related to waste  containment  or complicated  fate and
transport  mechanisms.   If waste/containment  system  compatibility problems are
discovered during a site evaluation, source modification such as liner replacement
may be necessary to reduce or prevent further releases.  In some cases, modifying
waste treatment,  storage, and disposal practices (e.g., restricting certain wastes
from operating landfills) may be the most appropriate source control measure.

     Interactions between wastes and constituents  and underlying geology may
alter  contaminant migration potential  and  complicate  control,  recovery and
treatment operations.   For example, acidic leachate  may cause or exacerbate
solution cavity development in areas underlain by karst geology, thus promoting
the  migration  of contaminants.   In other instances, interactions   between
contaminants and subsurface materials may reduce the effectiveness and efficiency
of  remediation  technologies;  for  example,  by  changing  the  chemistry  of
contaminated ground water  or  by inhibiting fluid  flow to  and from heavily
contaminated areas.

     Predicting  the interactions  between  different wastes and  constituents is
among the  most difficult tasks performed  during  site investigations.    Such
interactions may affect contaminant migration potential and complicate recovery
and treatment operations. One example is the clogging of pore spaces or well
screens by precipitates which form by chemical interactions  between wastes  or
constituents. Other examples include co-solvation,  particle transport and mobile
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transformation products (see Table 2-2).  It should be noted that laboratory testing
of waste,  or  constituent interactions  may  not  accurately depict  subsurface
processes. For this reason, ground-water chemistry and waste treatment, storage,
and disposal  conditions  at the site  should  be considered when  predicting the
behavior of certain combinations of wastes or constituents. In some instances, this
may mean additional sampling, monitoring, and field testing.

     Reviewing waste  management records to  assess the quality of  waste
management practices may aid assessment and remediation activities by providing
insight into the release potential of a source, and consequently, facilitate remedy
selection. For instance, factors such as waste packaging, handling and placement,
freeboard maintenance, and waste characterization may indicate how well a waste
management unit is operated and  maintained.  Improvements  in such  waste
management practices may reduce contaminant migration potential and therefore
should be considered viable source control measures.

2.2.3.2   Environmental Setting Characterization

     Characterization of the environmental setting may be necessary to determine
monitoring locations (i.e., contaminant pathways) and  to  aid in  defining the
boundaries of the contaminated area. Techniques for characterizing the environ-
mental setting are media-specific and are described  in Volumes II  and III of this
Guidance.  Examples of environmental information that may be required  are wind
speed and direction, subsurface stratigraphy, and surface-water body volumes and
flow rates.

2.2.4     Monitoring and Data Collection Procedures

     Specific monitoring procedures  should be identified in the RFI Work Plan to
characterize each release of concern.   These  procedures  should indicate the
proposed approach for conducting the  investigation and should account for the
following:

     •   Historical   information  and/or  information  gathered  during  the
         characterization of the contaminant source and the  environmental
         setting;
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TABLE 2-2.  PHYSICAL, CHEMICAL AND BIOLOGICAL PROCESSES
           AFFECTING CONTAMINANT FATE AND TRANSPORT
           (Keely, 1987)

                     PHYSICAL PROCESSES
                Advection (porous media velocity)
                    Hydrodynamic Dispersion
                      Molecular Diffusion
                     Density Stratification
                     Immiscible Phase Flow
                     Fractured Media Flow

                     CHEMICAL PROCESSES

                 Oxidation-Reduction Reactions
                      Radionuclide Decay
                        Ion-Exchange
                        Complexation
                         Co-Solvation
                  Immiscible Phase Partitioning
                           Sorption

                    BIOLOGICAL PROCESSES

                 Microbial Population Dynamics
                     Substrate Utilization
                      Biotransformation
                          Adaptation
                        Co-metabolism
                            2-19

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     •   An approach for implementation, including the type of information to
         be collected;

     •   Description of the monitoring network; and

     •   Description  of  monitoring activities  (e.g., sampling,  meteorological
         monitoring).

     Monitoring  procedures  may  include  a  phased  approach  for  release
characterization as described  in the media-specific sections of this Guidance.  The
initial phase  may include  a  limited monitoring effort followed  by  subsequent
phases, if necessary. The design of subsequent monitoring phases may be based on
information  gathered during  a prior phase; therefore, revisions to the monitoring
procedures may become necessary as the RFI progresses. A phased approach may be
particularly  useful in  cases where a suspected release  was  identified  by the
regulatory agency as a result of the RFA process. In this case, the first monitoring
phase may be designed to provide for release verification as well as the first step for
release characterizaton. If revisions to a proposed monitoring approach become
necessary, documentation should be submitted to the regulatory agency to support
such changes.

2.2.5     Assembling Existing Data to Characterize the Contaminant Release

     The owner or operator  should assemble and review existing analytical and
monitoring data pertinent to the release(s) and media of concern. This information
can be used to  determine the  need for and to plan the extent of additional
monitoring.   Only data that have been collected  using  reliable methods and
documented QA/QC procedures should be used as the basis for planning additional
efforts.  The amount and  quality  of existing data  will determine the need for
additional monitoring information on the release. Sources of such data include    <

     •   Information supplied by the  regulatory agency with  the permit con-
         ditions or compliance order;

     •   The RFA report;
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     •    Facility records;

     •    The facility's RCRA permit application;

     •    State and local government agency files, and

     •    CERCLA site reports (e.g., Records of Decisions).

2.2.6      Quality Assurance/Quality Control (QA/QC) Procedures

     The use of properly documented  and implemented QA/QC procedures for
monitoring activities (including sampling and analysis) is an essential part of the RFI
Work Plan. It is important to ensure that data generated during the investigation
are valid (i.e., supported by documented procedures) such that they can be used
with confidence to support determinations regarding the need for and design of
subsequent monitoring, the need for interim corrective measures, and the need for
a Corrective Measures Study. These procedures are used to describe and document
data quality and include such activities as

     •    Defining sampling and analytical techniques;

     •    Confirming and documenting correct sample identity;

     •    Establishing precision and accuracy of reported data;

     •    Documenting  all analytical steps in determining  sample identity and
          constituent concentrations;

     •    Establishing detection limits for constituents of concern; and

     •    Establishing any bias arising from field sampling or laboratory analytical
          activities.
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     Another important aspect of QA/QC is to ensure the use of qualified personnel
(e.g., licensed or certified) to conduct or oversee various parts of the investigation.
QA/QC procedures are described in Section 4.

2.2.7      Data Management and Reporting Procedures

     Data management procedures should be included as part of the RFI Work Plan
for organizing and  reporting  investigation  data  and  results.    Satisfactory
presentation  of investigation  results to the  regulatory agency is  essential  in
characterizing and interpreting contaminant releases.   Guidance on these pro-
cedures is presented in Section 5.

2.2.8      Identification of Potential Receptors

     As specified by the regulatory agency in the permit or order, the owner or
operator should provide in  the RFI Work Plan information describing the human
populations and environmental systems that may be susceptible to contaminant
releases from the facility. Such information may include

     •    Existing and  possible future use of ground  water, including type of  use
          (e.g.,  municipal   and/or  residential  drinking  water,   agricultural,
          domestic/non-potable, and industrial);

     •    Location of ground-water users, including wells and discharge areas;

     •    Existing and  possible future uses of surface waters draining the facility,
          including domestic and municipal uses (e.g., potable and lawn/gardening
          watering), recreational (e.g., fishing  and swimming), agricultural, and
          industrial and environmental (e.g., fish and wildlife populations) uses;

     •    Human use of or access to the facility and  adjacent  lands, including
          recreational, hunting, residential, commercial, zoning, and the relation-
          ship between population locations and prevailing wind direction;

     •    A description of  the biota in  surface-water bodies on, adjacent to, or
          which can be potentially affected by the release;
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     •   A description of the ecology on and adjacent to the facility;

     •   A demographic profile of the human population who use or have access
         to the facility and adjacent land, including age, sex, sensitive subgroups
         (e.g., schools, nursing homes), and other factors as appropriate; and

     •   A description of any endangered or threatened species near the facility.

     This information  can  be used to determine whether any interim corrective
measures may be necessary  at the facility.   If  populations are currently being
adversely exposed or such  exposure seems imminent, interim  corrective measures
may be necessary.  Further information  regarding  interim corrective measures is
provided in Section 8 (Health and Environmental Assessment).

     Receptors can be affected by the transfer of a release from one medium to
another.  Apparent or  suspected inter-media  transfers of contamination, as
identified in the permit or order, should  be addressed in the RFI Work Plan. Table
2-3 illustrates  some potential inter-media contaminant transfers and pathways. In
exar «ning the extent of a release, the owner or operator may be directed to collect
sufficient information to allow the identification of potential inter-media transfers.

     Situations where inter-media  contaminant  transfer may be  important  may
arise through  common usage of the contaminated medium.  For example, drinking
of ground  or surface  waters contaminated with volatile constituents poses an
obvious hazard. Less obvious is the inhalation hazard posed by showering with such
contaminated waters.  Situations  such  as this should  also be considered when
determining the need for interim corrective measures.

     The guidance presented in the media-specific sections  (Volumes II and III)
addresses potential areas for inter-media  transfer.  The guidance also identifies
situations in which contamination of more than one media can be characterized, to
some extent,  using common  procedures.  For example, soil-gas analyses, such as
those conducted using  an organic vapor analyzer (OVA), can be used to monitor for
subsurface gas (e.g., methane),  as well as to  indicate the overall extent of certain
types of contaminant releases to ground water.
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TABLE 2-3.  SOME POTENTIAL INTER-MEDIA CONTAMINANT
          TRANSFER PATHWAYS
Release Media
Air
Soil
Ground Water
Surface Water
Subsurface Gas
Potential
Receiving Media
• Soil
• Surface Water
• Ground Water
• Subsurface Gas
• Surf ace Water
• Surf ace Water
• Subsurface Gas
• Ground water
• Air
• Soil
• Air
• Soil
Transfer Pathways
- Deposition of particles
- Atmospheric washout
- Migration through the
unsaturated zone
- Migration through the soil
- Overland runoff
- Ground-water discharge
- Volatilization
- Ground-water recharge
- Volatilization
- Deposition of floodplain
sediments
- Venting through soil
- Migration through soil
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2.2.9      Health and Safety Procedures

     Health and safety procedures may be included as part of the RFI Work Plan.
The owner or operator is advised to  understand, use, and document health and
safety procedures describing efforts that will  be taken to ensure the health  and
safety of the investigative team and others (e.g., the general public) during the RFI.
The owner or operator should  also  be aware that on December 19,  1986, the
Occupational Safety and Health Administration (OSHA) issued an interim final rule
on hazardous waste site operations (29 CFR  1910.120) which specifically requires
certain minimum standards concerning health and safety for anyone performing
activities at CERCLA sites, RCRA sites,  or emergency response operations.  Further
discussion on this topic is provided in Section 6.

2.3        Implementation of the RFI Work Plan

     After review of the RFI Work Plan by the regulatory agency, the owner or
operator should  implement  the  plan as directed.  In some cases,  adequate
information may exist to characterize specific releases, and an extensive monitoring
effort may not be  necessary. The extent of monitoring will depend on the amount
and quality of  existing information  and the nature of the release.   Results of
investigative activities should be submitted to the regulatory agency according to
the RFI Work Plan schedule.  Further guidance on specific  reports that  may be
required is provided in Section  5.

     The owner or operator has a continuing responsibility to identify and respond
to emergency situations and to define priority situations that may warrant interim
corrective measures. Interim corrective measures may be necessary if receptors are
currently being exposed to release constituents or if such exposure seems  imminent.
These situations may become evident at any point in the RFI process. The owner or
operator should contact the regulatory agency immediately if any such situation
becomes apparent. Further information regarding  the evaluation of the results of
release characterization is presented in Section 8.
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2.4       Evaluation by the Regulatory Agency

     The regulatory agency will evaluate reports of release-specific results of the
RFI submitted by the owner or operator to make determinations for further action.
Such determinations may include

     •    No further action is necessary at that time;

     •    Further information on a release is necessary.  The owner or operator will
          be advised to initiate additional monitoring activities;

     •    Interim corrective measures are necessary; or

     •    Adequate information is available to conclude that a CMS is necessary.

     The regulatory agency may elect to be present at the facility to observe any
phase of the release investigation.   As indicated previously, dose coordination
between the owner or operator and  the regulatory agency is essential throughout
the RFI process. Also, as shown in Figure 2-1, interim corrective measures may be
implemented prior to or during the RFI, as necessary.
                                    2-26

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                                SECTION 3

              GENERAL STRATEGY FOR RELEASE INVESTIGATION
3.1        INTRODUCTION

     An investigation  of releases  from solid waste management units requires
various types of information.  This information is specific to the waste managed,
unit type, design, and operation, the environment surrounding the unit or facility,
and the medium to which contamination is being released. Although each medium
will require  specific  data and methodologies to  investigate a release, a general
strategy for this investigation, consisting of two elements, can be described:

     •    Collection and review of data to  be used in developing a conceptual
          model of the release that can be used to plan and develop monitoring
          procedures.    These  data  may include  existing  information on the
          faciIity/unit or related monitoring data, data which can be gathered from
          outside  sources of information on parameters affecting the release, or
         the gathering of new information through  such  mechanisms as  aerial
          photography or waste characterization.

     •    Formulation and implementation of field investigations, sampling and
          analysis, and/or monitoring  procedures  designed to  verify suspected
          releases (if necessary), and to evaluate the nature, extent, and rate of
          migration of verified releases.

     As stated in Section 2, two components of the RFI Work Plan will address these
elements. These are

     •    Procedures to characterize the contaminant source and the environ-
          mental setting; and

     •    Monitoring procedures.
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     Sections 3.4 and 3.5 provide general guidance on these procedures. Section
3.2  outlines the general strategy suggested  for  all  release investigations, and
Section 3.3 briefly discusses concepts concerning data quality that are designed to
ensure that data  collected  during the investigation  will adequately support
decisions that will eventually be made regarding the need for corrective measures.
Section 3.6 provides guidance for formulating methods and monitoring procedures,
and addresses monitoring constituents and  indicator parameters, use of EPA and
other methods, sampling considerations, and analytical methods  and  detection
limits. Section 3.7 provides information concerning various decisions that may be
made based on monitoring data and other information collected  during the RFI
process.

3.2       Phased Strategy for Release Investigations

     At the start of the RFI process,  varying amounts  of information will exist on
specific releases and units.  In some instances, suspected releases may have been
identified based on strong evidence  that releases have occurred, but with little or
no direct data confirming their presence. On the other end of the spectrum, there
may be enough existing data at the  start of the RFI to begin considering whether
some form of corrective measure may be necessary.

     This potentially broad spectrum of situations that may exist at the beginning
of the RFI may call  for a flexible, phased approach for the release investigation,
beginning with an evaluation  of existing data and collecting  additional data, as
necessary to characterize the release source and the environmental setting. From
such data, a conceptual model of the release can be formulated in order to design a
monitoring program capable of release verification and/or characterization.

     The release characterization may be conducted in phases, if appropriate, with
each monitoring phase building on  the  findings and conclusions of the previous
phase.  The  overall level of effort and the number of  phases  for  any given
characterization effort depend on various factors including

     •   The level of data and information available on the site;
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     •   The complexity of the release (e.g., number of units, release pathways,
         affected media); and

     •   The overall extent of the release.

   .  As many situations are likely to be unique with respect to the above factors,
the number and  intensity of each of the phases of the RFI  process leading  to
eventual characterization  and to  assessment against health and environmental
criteria are also likely to  be unique.  Even though  some RFIs may have several
phases, it is important to make sure that the establishment of a phased approach
does not result in undue delay of the RFI process.

     Case Study No. 18 in Volume IV (Case Study Examples) provides an illustration
of a phased characterization.

3.3      Data Quality and Use

     Throughout the RFI process,  it should  be kept in mind that the data will  be
used in  making comparisons to health and environmental criteria to determine
whether a CMS or interim corrective measures may be necessary.  Therefore, the
data collected during the  investigation must be  of  sufficient quality to support
decisions as to the need for corrective measures. The data can also be  used to help
establish the scope and types of corrective measures to be considered in the CMS.

     Qualitative  or quantitative  statements that  outline the decision-making
process and specify the quality and quantity of data required to support decisions
should be made early  in the planning stages of the RFI.  These "data quality
objectives" are then used to design sampling  and analytical plans, and to determine
the appropriate level of quality assurance and control (QA/QC). As this subject is
normally considered a QA/QC function, it is presented in more detail in the QA/QC
Section  (Section  4) of this document.  It is briefly  discussed  here to stress the
importance of defining the objectives of the investigation, and of designing data-
gathering efforts to meet these objectives throughout the investigation.
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3.4      Procedures  for Characterizing  the  Contaminant  Source  and  the
         Environmental Setting

     Before  monitoring   procedures   are  established,  information   on  the
contaminant  source (i.e., waste  and unit)  and environmental  setting may be
required.  The owner or  operator should identify necessary data and formulate
procedures to gather these data.

     Unit-specific data that may be required for release investigation include such
parameters as the physical  size of the unit, the amount of waste in  the unit,
operational schedules, age,  operational lifetime, and release  controls.  Data
concerning the environmental setting that may be necessary are specific to the
medium affected, and may include  such information as climate, hydrogeologic
setting, vegetation, and topography.  These and  other important elements are
described  below,  starting  with  a  discussion  of  the  importance  of existing
information.

     Case Study Numbers 8,  10, 12, 13, 14, and  30 in Volume  IV (Case Study
Examples) provide examples of the techniques discussed below.

3.4.1     Sources of Existing Information

     Useful existing data may be found in the following sources:

     •   The RCRA  Facility  Assessment report.   This report  should provide
         information on the unit(s) known to be causing or suspected of causing a
         release to the environment and the affected media. It may also include
         data supporting the regulatory agency's release determinations.  The
         owner  or operator may  wish to obtain  the  RFA report  from the
         regulatory agency for use in scoping the RFI.

     •   Facility records and files.  Other useful information may be available in
         facility  records and files.  This information may include data from
         required ground-water monitoring activities,  results of required waste
         analyses,  and  other analytical results (e.g., tests run on  wastes to
         determine  such  parameters  as  liner  compatibility  or  free  liquid
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     composition).  The owner or operator may have information on the
     characteristics of the waste in the units of concern from other in-house
     sources, such  as  waste reduction and engineering  studies  on  the
     process(es) feeding the units, or from analyses performed in conjunction
     with other regulatory programs, such as the National Pollutant Discharge
     Elimination  System   (NPDES) permitting process or  Clean Air  Act
     Standards.  Design and construction information may also be contained
     within facility files.  For example, design and construction information
     for advanced wastewater treatment systems may contain information on
     inactive units.

•    RCRA Permit Application. Under current requirements, a RCRA permit
     application should include a description of the waste being managed at
     the facility  (although not  necessarily for all the units of concern),
     descriptions of the units relevant to the permit, descriptions  of the
     general environment within and surrounding the  facility  (including
     descriptions of the subsurface stratigraphy), and  design and operating
     information such  as runon/runoff  controls.    A  companion  rule
     (promulgated December 1, 1987) to the July 15, 1985, codification rule
     for  Section 3004(u)  expands  the information  requirements  under
     §270,14(d) for all  solid waste management units to be located on the
     facility topographic  map, and to contain information on unit type,
     dimensions and design, dates operated, and waste managed,  to the
     extent available.

•    State Construction Permit (e.g., industrial wastewater) files.

•    Environmental or other studies conducted in conjunction with ownership
     changes.

•    Interviews with facility personnel (current or retired).

•    Environmental audit reports.

•    Investigations for environmental insurance policies.
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3.4.2     Waste and Unit Characterization

     In addition to obtaining waste data on general parameters such as pH, density,
and viscosity, which may be needed to characterize a release to specific media (and
which may also be useful in evaluating corrective-measure technologies), the owner
or operator should characterize the unit's waste  to the compound-specific level.
This characterization may serve as a basis for identifying  monitoring constituents
and indicator parameters for the media of concern.  It should be noted that the
owner or operator may be  required to characterize all potential constituents  of
concern for a given medium, unless it can be shown that only certain constituents
could be released from the waste  source.  A detailed  waste characterization,
through the use  of facility records and/or additional waste sampling and analysis,
can be utilized to limit the  number of constituents for which release monitoring
must be performed during the RFI. (See also Section 3.6.1.)

     Waste and unit characterization procedures should address the following:

     •   Existing sources of information on the unit and waste and their utility in
         characterizing the waste source; and
                                            •
     •   Methods for gathering data on the waste and unit that are not presently
         available.

     In some cases the location of disposal areas (units) may not be obvious. Some
of these disposal areas or units may have been  buried, overgrown  by trees,  or
covered by  structures such  as buildings or parking lots.  In such cases,  use  of
geophysical  techniques (e.g., ground-penetrating  radar - see Appendix C) may be
useful in locating former disposal  areas containing materials such as discarded
drums or buried tanks.

     After evaluating existing data, the owner or  operator may propose to collect
additional waste and unit characterization information. In such cases, the owner or
operator should propose procedures in the RFI Work Plan for

     •   Sampling-This should include sampling  locations, schedules, numbers of
         samples to be taken, and methods for collecting and storing samples.
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     •   Analysis-This  should  include  a listing  of analytical  constituents or
         parameters and the rationale for their selection, analytical methods, and
         identification of detection limits.

     •   QA/QC--This should include specific steps to  be taken to ensure the
         viability and validity of data produced during a waste sampling effort.

     •   Data  management-The owner or  operator  should  describe  data
         management procedures, including the format(s) by which data on the
         contaminant source will be presented to the regulatory agency and the
         various reports that will be submitted.

     Further guidance on the types of information and methods to be used in
gathering waste and unit data is given  in Section 7. Case Study Numbers 3,4, 7, 8, 9,
and 10 in Volume IV (Case Study Examples) illustrate some of the activities discussed
above.

3.4.3     Characterization of the Environmental Setting

     Data  on  the environmental  setting  will  generally  be  necessary for
characterizing  the release,  and  may also be  helpful  for  evaluating various
corrective-measure technologies.  The information necessary is specific to the site
and medium receiving the release and is described in the media-specific sections
(Sections 9 through 13). Some examples of the methods and techniques that may be
used are as follows:

     •   Direct media measurements-Direct  media measurements can provide
         important information that can be used to determine the rate and extent
         of  contaminant   release.     For   example,   hydraulic  conductivity
         measurements are essential in determining ground-water flow  rates.
         Wind roses  and  patterns  can  be  used  in determining  how far  air
         contamination may migrate and are essential  input for air dispersion
         models.  Specific  measurements helpful for investigating the rate and
         extent of releases are discussed in the media-specific sections (Sections 9
         through  13) of this Guidance.
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•    Aerial photography-Aerial photography can provide information that
     can be helpful in determining the extent of contamination at a site.
     Interpretation of aerial  photographs can aid in describing past and
     present  contaminant  sources, pathways,  and  effects.   Information
     obtained can include  ecological  impacts (e.g.,  decaying  vegetation),
     topography, drainage patterns, fracture traces, and other erosional
     features. The usefulness of aerial photography  is discussed further in
     Appendix A.

•    Geophysical   techniques-Geophysical   techniques   can   aid   in
     characterizing  subsurface  conditions  fairly  rapidly  with  minimal
     disturbance of the site. Such characterization can provide information
     on physical  (e.g., stratigraphic) and chemical (e.g., contaminant extent)
     conditions and can also be used to locate buried drums, tanks, and other
     wastes.   Geophysical  techniques  include  electromagnetic  induction,
     seismic  refraction,  electrical  resistivity, ground-penetrating   radar,
     magnetic borehole methods, and other methods. These techniques can
     be particularly useful  in determining appropriate sampling locations.
     However, these  geophysical techniques are not  always applicable at a
     particular site and do  not provide detailed contaminant concentration
     data.  Therefore, sampling will generally be necessary to provide data
     needed  for adequately characterizing  the release.  Further details on
     these techniques are available in Section 10 on  Ground Water, and in
     Appendix C (Geophysical Techniques).

•    Surveying and mapping-According to the 40 CFR Part 270 requirements
     for RCRA permit applications, the owner or operator  must provide a
     topographic map and  associated information regarding the site.  If an
     adequate topographic map does not exist, a survey may be necessary to
     measure and plot (and elevations.  Site-specific surveying and mapping
     can provide an effective means of expressing topographic features (e.g.,
     subtle elevation changes and site drainage patterns) of an area useful in
     characterizing releases. Surveying and mapping are discussed in further
     detail in Appendix A.
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     The owner or operator should describe the following in the RFI Work Plan:

     •   Specific techniques to be used in defining the environmental setting for
         the releases of concern at the facility;

     •   A rationale for the use of these techniques;

     •   Specific QA/QC procedures applicable to the proposed techniques;

     •   Procedures for managing and presenting the data; and

     •   Potential uses of the information obtained from this characterization.

3.4.4     Assembling Available Monitoring Data

     The owner or operator should compile and assess available media-specific
monitoring data as a means of determining additional  data needs.  It is conceivable,
in certain instances, that available data will be sufficient to characterize a release
and  provide the basis for making  a  determination  on the need for corrective
measures.   However, this  conclusion  would be valid only if available data are
current, comprehensive, accurate, and supported by  reliable QA/QC  methods.
Otherwise,  the  use of available data should be limited to  planning  additional
monitoring efforts.

3.5       Use of Models

3.5.1     General Applications

     Mathematical and/or computer modeling  may provide information useful to
the owner or operator during the RFI and in the design of corrective measures. The
information may prove useful in refining conceptualizations of the environmental
setting, defining likely contaminant release pathways, and designing corrective
measures (e.g., pumping and treating contaminated ground water).

     Because  a model  is  a  mathematical representation of an often-complex
physical system, simplified assumptions must be made  about the physical system, so

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that it may fit into the more simplistic mathematical framework of the model. Such
assumptions are especially appropriate because  the  model assumes  a  detailed
knowledge of the relevant input parameters (e.g., permeability,  porosity, etc.)
everywhere in the area being modeled.

     Because a model uses assumptions as to both the physical processes involved
and the spatial and temporal variations in field data, the results produced by the
model  may provide only a qualitative assessment of the nature, extent, and rate of
migration of a contaminant release.  Because of the  assumptions  made, a  large
degree of uncertainty may arise from some modeling simulations.  Such modeling
results should not be unduly relied on in selecting precise monitoring locations or in
designing corrective measures.

     Use of predictive models during the RFI may be appropriate for guiding the
general development of monitoring networks.  Each of the media-specific sections
identify where and  how such predictive  models may be  used,  and identify
references containing specific models.  For example, models are identified  in the
Surface Water  Section  (Section  13)  for  use  in determining the extent  of a
monitoring system which may be necessary in a stream.  Modeling  results are
generally not  acceptable for expressing  release concentrations in an  RFI.  An
exception to this is the air medium (Section 12). Atmospheric dispersion  models are
suggested for use (especially  when  downwind  monitoring  is not feasible) in
conjunction  with emission-rate monitoring or  modeling in order  to predict
downwind release concentrations and to define the overall extent of a release.

     Where  a model  is to be used, site-specific measurements should be  collected
and verified. The nature of the parameters required by a model varies from model
to model and is a function of the physical processes being simulated (e.g., ground-
water flow and/or contaminant transport), as well as the complexity of  the model.
In simulating ground-water flow, for example, hydrogeologic parameters that are
usually required include hydraulic conductivity (vertical and horizontal);  hydraulic
gradient; specific yield (unconfined aquifer) or specific storage (confined aquifer);
water levels in wells and nearby surface-water bodies; and estimates of infiltration
or recharge.  In simulating contaminant transport in ground water, physical and
chemical parameters that are usually required  include ground-water  velocity;
dispersivity of the aquifer; adsorptive  characteristics of the aquifer (retardation);
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degradation  characteristics  of  the contaminants;  and  the amount  of each
contaminant entering the aquifer (source definition).

     Model input parameters that can be determined directly should be measured,
with  consideration  given to  selecting  representative samples.   Because the
parameters cannot be measured continuously over the entire region but only at
discrete locations, care should be taken  when extrapolating over regions where
there are no data.  These  considerations  are  especially important where the
parameters vary significantly  in space or time.  The sensitivity of the model output
both to the measured and assumed input parameters should be determined when
evaluating modeling results.  In addition,  the ability of the model to be adequately
calibrated (i.e., the ability of the model to reproduce current conditions), and  to
reproduce past conditions should be carefully evaluated in assessing the reliability
of model predictions. Model  calibration with observed physical conditions is critical
to any successful modeling exercise.

     Many models exist that  may be applicable for use in the RFI.  Because EPA is a
public agency and models used by or for EPA may become part of a judicial action,
EPA approval of  model use should be restricted to those models  that are publicly
available (i.e., those models that are available  to the  public for no charge or for a
small fee). The subset of models that are publicly available is quite  large and should
be sufficient for many applications.  Publicly available  models include those models
developed by or for government agencies (e.g., EPA, U.S.  Geological Survey, U.S.
Department of Energy, U.S.  Nuclear Regulatory  Commission, etc.) and national
laboratories (e.g., Sandia, Oak Ridge, Lawrence Berkeley, etc.), as well as models
made publicly available by private contractors. Any publicly available model chosen
should, however, be widely  used, well-documented,  have its theory published in
peer-reviewed journals, or have  some other characteristics reasonably ensuring  its
credibility.  For situations where publicly available models are not appropriate,
proprietary models (i.e., models not reasonably accessible for use or scrutiny by the
public) should be used only  where the models have been well-documented and
have undergone  substantial peer review. If these minimal requirements have not
been met, the model will not be considered reliable.

     The Graphical Exposure Modeling System (GEMS) may be particularly useful
for various aspects of the RFI. GEMS is an interactive  computer system, developed
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by EPA's Office of Pesticides and Toxic Substances, which provides a simple interface
to environmental modeling, physiochemical property estimation, statistical analysis,
and graphic display capabilities, with data manipulation which supports all these
functions. Fate and transport models are provided for soil, ground water, air, and
surface water, and are supported by various data sets, including demographic,
hydrologic, pedologic,  geologic, climatic,  economic,  amoung  others.   Further
information on GEMS may be obtained  by calling EPA at (202) 382-3397 or (202)
382-3928 or by writing to EPA at the following address:

          U.S. EPA
          Office of Pesticides and Toxic Substances
          Exposure Evaluation Division (TS-798)
          401 M Street, S.W.
          Washington, D.C. 20460

     If the use of a model is proposed to guide the development of a monitoring
network, the owner or operator should describe how the model works, and explain
all assumptions used in  calibrating and applying the model to the site in  question.
In addition, the model and all related documentation should be made available to
the regulatory agency for review.

     Case Study Numbers 20, 24, 25, and 31 in Volume IV (Case Study Examples)
illustrate the use of various models that may be applied during the RFI.

3.5.2      Ground-Water Modeling

     Ground-water  modeling  is often  used for  site  characterization, remedy
selection and  design,  and prediction  of  site-specific  cleanup  levels and  time
requirements.   As with other models, a  ground-water model is a simplified
representation of reality,  usually expressed with mathematics,  that aids in
understanding and predicting subsurface contaminant fate and transport. As such,
models may include flow nets, ground-water flow models, simple analytical solute
transport models, method of characteristics models, or complex multi-phase finite
element models.
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     Perhaps the most important role of ground-water models for assessment and
remediation programs is their application in selecting, collecting and analyzing field
data on subsurface contaminant fate and transport.  Model development and site
characterization should be combined in an iterative process of fate and transport
simulation and data collection.  For instance, after examining several cross-sections
and water level data sets, the investigator may develop several flow nets to better
understand the ground-water flow regime beneath a site.  Following this, a series of
simulations using a simple analytical solute transport model can roughly estimate
the  range  of concentrations  with respect to distance and  time for various
contaminants.  These results could then be compared with actual concentrations of
samples collected  from monitoring wells. Discrepancies between observed and
predicted  concentrations may  suggest  that  additional site  characterization is
required or that the model does  not adequately simulate actual field conditions.

     Ground-water models may be used to some extent in predicting contaminant
migration, selecting and designing remedial systems, evaluating the performance
of technologies, and projecting  cleanup levels. For instance, assuming a pump and
treat alternative is appropriate,  analytical or numerical ground-water flow models
could be used to estimate the placement of recovery wells and plume control wells.
Such  models  could  also be   used in  planning  the timing  of ground-water
withdrawals.  However, these types of applications should only be used in concert
with  actual  data  collection  (e.g., collecting ground-water  samples)  and field
demonstrations (e.g., pilot studies). Exclusive model use for the above applications
without adequate data collection and field demonstration may lead to incorrect
and inefficient remedy selection.

     The following documents provide  information on  the  uses of models and
point out many of their limitations and underlying assumptions:

     Keely, J.F. January 1987.  The Use  of Models  in Managing Ground Water
     Protection Programs.   EPA/600/8-87/003.    EPA Office of  Research and
     Development. Washington, D.C. 20460.

     U.S. EPA.  January 1989. Resolution on Use of Mathematical Models bv EPA for
     Regulatory Assessment and Decision-Making.  Report of the Environmental
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     Engineering. Committee,  Science  Advisory  Board.    EPA-SAB-EEC-89-012.
     Washington, D.C. 20460.

     These documents emphasize the importance of using ground-water models
that are commensurate with the extent and  quality of  collected  field  data.
Matching the model with the type of contamination problem is equally important.
Certain instances may arise where more sophisticated models may be appropriate.
For example, a finite element model simulating multi-phase flow of a hydrocarbon
release in a well-characterized area may contribute to both defining the problem
and selecting the remedy. The key rule to follow is to match the model with the
type of contamination problem and the level and quality of data. In addition, every
modeling exercise should include a sensitivity analysis to determine the relative
impact of different variables on modeling results. The following presents excerpts
from the above identified EPA Science  Advisory Board report on mathematical
models which are particularly  relevant  for regulatory assessment and  decision-
making:

     •   The use of mathematical models for environmental decision-making has
         increased significantly in recent years. The reasons for this are many,
         including   scientific  advances   in  the  understanding   of  certain
         environmental  processes,   the  wide availability  of computational
         resources, the increased number of scientists and engineers trained in
         mathematical  formulation  and  solution  techniques, and a  general
         recognition  of the  power and  potential benefits  of  quantitative
         assessment methods. Within the U.S.  Environmental Protection Agency
         (EPA) environmental models which integrate release, transport,  fate,
         ecological effects  and human  exposure are being used for rule making
         decisions and regulatory impact assessments.

     •   The realistic characterization of an environmental problem requires the
         collection of laboratory and field data - the more complex the problem,
         the more extensive and in-depth are the required studies.  In some cases
         involving more complex  issues, future projections of environmental
         effects, larger  geophysical regimes,  inter-media transfers, or subtle
         ecological effects, mathematical models of the  phenomena provide an
         essential element of the analysis and understanding.  However, the
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     models cannot stand alone; adequate data are required. Indeed, a major
     function of mathematical models is as a tool  to design field studies,
     interpret the data and generalize the results.

•    Mathematical  models should  ideally  be based  on  a fundamental
     representation  of  the  physical,  chemical  and biological  processes
     affecting environmental systems.

•    An improperly  formulated model can  lead  to serious  misjudgements
     concerning  environmental  impacts and the  effectiveness of  proposed
     regulations. In this regard, a bad model can be  worse than no model at
     all.

•    There are a number of steps needed to confirm the accuracy and utility of
     an environmental model. As a preliminary step, the elements of the basic
     equations and the  computational procedures employed to solve them
     should be tested to ensure that the model generates results consistent
     with  its  underlying theory.  The confirmed  model should  then  be
     calibrated with field data and subsequently  validated with additional
     data collected under varying environmental conditions.

•    The stepwise procedure of checking  the numerical consistency of a
     model,  followed  by field  calibration, validation  and  a posteriori
     evaluation should be an established protocol  for environmental quality
     models in all media, recognizing that the particular implementation of
     this may differ for surface water, air and ground water quality models.

•    A number  of  methods have  been developed in  recent years for
     quantifying and interpreting the sensitivity and uncertainty of models.
     These methods  require   careful  application, as experience  with
     uncertainty analysis techniques is somewhat  limited, and there  is a
     significant potential for  misuse of the procedures and misinterpretation
     of the results. Potential problems include the tendency to confuse model
     uncertainty with temporal or spatial variation in environmental systems,
     the tendency  to rely on  model uncertainty  analysis as a  low-cost
     substitute for  actual  scientific  research, and the  tendency to ignore
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          important   uncertainties   in   model   structure  when   evaluating
          uncertainties in model parameters.

     •    Peer review is  an essential element of  all  scientific studies, including
          modeling applications. Peer review is appropriate in varying degrees and
          forms  at different stages  of the model development and application
          process.  The basic scientific representation incorporated in the model
          should be based on formulations which have been presented in the peer
          reviewed scientific literature.  Ideally, the model  itself and initial test
          applications should also be presented in peer-reviewed papers.

3.6       Formulating Methods and Monitoring Procedures

     The RFI Work Plan should describe  monitoring procedures that address the
following items on a release-specific basis:

     •    Monitoring constituents of concern and other monitoring parameters
          (e.g., indicators);

     •    Sampling locations and frequency;

     •    Sampling methods;

     •    Types of samples to be collected;

     •    Analytical methods; and

     •    Detection limits.

     These items are discussed below.

3.6.1      Monitoring Constituents and Indicator Parameters

     Selection and use of reliable and useful monitoring constituents and indicator
parameters is a site-specific process and depends on several factors, including the
following:
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     •    The phase of the release investigation (e.g., verification, characteriza-
          tion);

     •    The medium or media being investigated;

     •    The degree to which verifiable historical information exists on the unit or
          release being investigated;

     •    The degree to which  the waste in the unit(s) has been characterized
          through sampling and analysis;

     •    The extent of the release;

     •    The concentration of constituents within the contaminated media; and

     •    The potential for physical, chemical, or biological transformations (e.g.,
          degradation) of waste or release constituents.

     The general strategy for the selection of specific monitoring constituents starts
with a large universe list of constituents (i.e., 40 CFR Part 261, Appendix VIII).  (It
should be noted that the definition of constituent may also include components of
40 CFR Part 264, Appendix IX that are not  also on Appendix VIII, but are normally
monitored for  during  ground-water  investigations.)   Based  on  site-specific
considerations (e.g., the contaminated media, sampling and analysis of waste from
the  unit, or industry-specific information), this list  may be shortened to  an
appropriate set of monitoring constituents. Constituents initially deleted as a result
of this  process  may have to be analyzed at selected  locations during and/or
following the RFI, especially  if a CMS is found  necessary.  The discussion below
explains the use of the four lists presented in Appendix B for selecting monitoring
constituents and supplemental indicator parameters.

     List 1 in Appendix B identifies indicator parameters recommended for release
verification or characterization for the five environmental media discussed in this
Guidance.  This list was developed  based  on  a review of RCRA  and  CERCLA
guidances, as well  as on information obtained during  RCRA  and CERCLA site
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investigations. These indicator parameters should be used in the RF!  unless the
owner or  operator can show that their use will not be helpful.  For example,
although total organic carbon and total organic halogen are listed as indicator
parameters for ground water,  their use  may  not  be warranted  for releases
consisting  primarily of inorganic (e.g., heavy-metal) contamination, tn addition, as
indicated in the footnote in List 1, although TOC and TOX have historically been
used as indicator parameters for site investigations, the latest data suggests that use
of these parameters may not provide an adequate indication of contamination,
primarily due to precision and accuracy problems.

     At most sites, however, the use of  indicator parameters will be appropriate,
especially for ground-water monitoring.  In general, any constituent not expected
to be contained in or derived from the  waste or the  contaminated area may not
serve as a  reliable or practical indicator  of a release.  Studies have examined the
frequency  of occurrence  of  analytes in ground-water at hazardous waste sites
throughout the country (Garman, Jerry, Tom Freund and Ed Lawless. 1987. Testing
for  Ground-water  Contamination  at  Hazardous  Waste  Sites:    Journal  of
Chromatographic Science, Vol. 25, pp. 328-337). These studies indicate that metals
and  volatile organic compounds (VOCs) are two sets of analytes that generally
provide a  reliable and practical way of detecting and monitoring  a release to
ground water.

     In  addition, investigations by  EPA's  Environmental  Monitoring Systems
Laboratory in Las Vegas, Nevada,  and others  have  shown that  most of the
compounds being released from hazardous waste facilities (as high as 70%) are
volatile organics.  These compounds have a low molecular weight and are fairly
water soluble, which  accounts  for their  high mobility in  ground water.
Furthermore, volatiles are produced in  relatively large quantities in the United
States and wastes containing them are managed in significant quantities at most
permitted  hazardous waste facilities.

     Metals, particularly those that are  amenable to the ICP (Inductively Coupled
Plasma) scan, are the second most common set of contaminants that are released at
hazardous waste  management facilities, and therefore are also expected to be
excellent indicators of releases to ground water, as alluded to earlier.
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     A list  of those 40  CFR 264 Appendix IX constituents commonly found m
contaminated ground water and amenable to analysis by volatile organics and !CP
(metals) methods is provided in Li-st 2.

     List3 in Appendix B is a master list of potential hazardous constituents that
may, at one time or another, have to be monitored during an RFI. It contains the 40
CFR Part 261, Appendix VIII list of hazardous constituents in the left-hand column.
The five environmental  media  columns contain  X's where there is a reasonable
probability, based on physical or chemical characteristics, of a particular constituent
being present in the given medium.  However, constituents not containing an X for
a particular medium may still be present in that  medium, despite a relatively low
probability of their presence.  Therefore,  the regulatory agency may add such
constituents for monitoring when  appropriate.   List 3 was  derived  through
consultation with various EPA program offices and through examination of existing
regulations. The rationale for identifying specific  Appendix VIII constituents for the
various media is explained below:

     •   Reactivity with water. Those constituents that react with or decompose
         in water were not marked with an X in the water-related columns.

     •   Existence  of viable analytical techniques for a constituent in a specific
         medium.  In  many cases, constituents  were not included for a specific
         medium  because  valid analytical methodologies are not currently
         available for that particular constituent/medium combination. In  some
         cases, standard reference materials are not available for the analysis.

[Note that the above two criteria describe the primary rationale used to develop the
40 CFR Part 264, Appendix IX list of ground-water monitoring constituents. Hence,
the ground-water and surface-water columns in  List 3  are based  on the final
Appendix IX constituent list.]

     •   Recommendations from other EPA program offices.  Offices concerned
         with  the  release of hazardous constituents to various  media  were
         consulted for recommendations on the  analytes of  primary concern.
         Appendix VIII hazardous constituents regarded by EPA's Office of Air
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         Quality Planning and Standards (OAQPS) as being of primary concern for
         release to air are identified in the air column in List 3.

     •   Background information.   Analytes recommended for subsurface gas
         releases were chosen due to their predominance in past studies of this
         problem.  The primary sources used for the subsurface gas medium are:

              U.S.  EPA.  Technical Guidance for Corrective Measures -Subsurface
              Gas. Prepared by SCS Engineers for U.S.  EPA, Office of Solid Waste.
              Washington, D.C. 20460.

              South  Coast Air Quality Management  District.   December 1986.
              Hazardous Pollutants in Class II Landfills. U.S. EPA, Region IX. San
              Francisco, CA 94105.

     •   The soil column includes  constituents that may be  present  in both
         saturated and  unsaturated  soil.   The  column generally identifies
         constituents that are also identified for the ground-water and surface-
         water media,  but contains additional constituents that are normally
         analyzed during soil contamination investigations (e.g., hydrogen sulfide
         and other gases), and  certain other compounds that can be highly
         attenuated in soil (e.g., polyaromatic hydrocarbons).

     An  RFI  may  involve  the  investigation  of waste which  is hazardous  by
characteristic, as well as'containing specific hazardous constituents. For example,
methane, which is not an Appendix  VIII hazardous constituent, is shown as an
indicator parameter in List 1 for releases of subsurface gas. Because  methane at
sufficient concentrations possesses explosive or reactive  properties, it  can  be
hazardous based on the reactivity characteristic (40 CFR  261.23).  Hence, subsurface
gas may  be the subject of an RFI  even  if specific hazardous constituents  are not
identified in the release.

     List 4 in Appendix B  is an industry-specific list. This list identifies categories of
constituents, based on the classification presented in the 3rd Edition of EPA's Test
Methods for Evaluating Solid Waste (EPA/SW-846), that may be present if wastes
from a given industry are contained in the releasing unit. The EPA/SW-846 chemical
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classifications for these categories-are reprinted  as a supplement to List 4.  List 4
applies to all media and may be used in conjunction with List 3 to identify industry-
specific constituents that have a reasonable probability of being  present  in a
particular medium.   List 4 was  derived  from  a review of  the Development
Documents  for  Effluent  Guidelines Limitations  prepared for various  industries
under EPA's NPDES program, information received from several EPA Regional Office
Hazardous Waste Programs, and other references, as indicated in Appendix B. It
does  not cover all industries that may be subject to an RFI.  The Development
Documents for Effluent Guidelines Limitations are available  for the 30 industries
identified in List 4, and may be obtained from the National Technical Information
Service (NTIS).

     [Note that the chemical categories upon which List 4 are based are not
mutually exclusive.  If a category is identified as being appropriate for an industry,
all constituents within the category should be monitored regardless of whether the
constituent is contained in other categories.]

     The use of the Appendix B lists in developing and implementing the general
investigation strategy is described below.

     The phase of ».he release investigation is a very important consideration.  For
example, the use of indicator parameters (List  1) along with  specific hazardous
constituents, can be helpful in verifying  the presence of a  suspected release.
However, indicators alone are not adequate in showing the absence of a release,
partially because of their relatively  high detection limits (i.e., generally 1000 ug/l
versus 10 to 20 ug/l for specific  constituent analyses), and  because indicator
parameters do not account for all  classes of constituents that may be present.
Verification  of the absence of a release should therefore always be supported by
specific hazardous constituent analyses.

     For the same reasons, indicator parameters should not form the sole basis for
release  characterization,  especially  at locations in the release  where  indicator
concentrations  are close to  detection limits.   Indicator  parameters may be
particularly  useful in mapping large releases,  but should always  be used in
conjunction with specific monitoring constituents.
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     Specific monitoring constituents and indicator parameters may also need to De
modified as the investigation progresses, because physical, chemical, and biological
degradation may transform constituents as the release ages or advances.  When
chemicals degrade, they usually degrade into less toxic, more stable  species.
However, this is not always the case. For example, one of the degradation products
of trichloroethylene is  vinyl chloride.  Both of these chemicals are carcinogens.
Information on  degradation can  be found in the  environmental  literature.
Particular references include:

          U.S. EPA.  1985.   Atmospheric Reaction Products from Hazardous Air
          Pollutant Degradation. NTIS PB85-185841. Washington, D.C. 20460.

          U.S. EPA. 1984.  Fate of Selected Toxic Compounds Under Controlled
          Redox Potential and pH Conditions in Soil and Sediment Water Systems.
          NTIS PB84-140169. Washington, D.C. 20460.

     This topic is discussed  in more detail later in this section and  in each of the
media-specific sections.

     After a  release is adequately characterized in terms of  concentrations of
hazardous constituents (or hazardous  characteristics), a  comparison of  these
concentrations to EPA health and environmental-based criteria  will be  made (see
Section 8). Although this comparison may involve a shortened list at this stage of
the RFI, all potential monitoring constituents (even  those  deleted earlier in the
process) may need to be analyzed at selected monitoring locations to verify their
presence or absence.

     The  use  of ICP  spectroscopy (for metals)  and gas  chromatography/mass
spectrometry for volatile organic compounds (List 2) can be particularly helpful in
delineating releases where little or no information is available on the source.  These
methods are relatively cost-effective because they address a number of constituents
in a single analysis.

     The medium or media being investigated is also an important consideration in
identifying monitoring constituents.  For example, non-volatile constituents may be
poor candidates for monitoring of an air release, unless wind-blown particulates are
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of concern.  List 3 in Appendix 3  has been  developed  to aid in identifying
constituents most likely to be measurable in each medium of concern.

     Historical information (e.g., records indicating the industry from which wastes
originated) may be useful in selecting monitoring constituents. List 4 in Appendix 8
may be helpful in  identifying classes of constituents that may be of concern if a
particular industry can be identified.

     Waste sampling and analysis (see  Section 7) may be performed  to tailor the
initial list of monitoring constituents. Although complete waste characterization is
recommended in most cases, this may not always be possible or desirable (e.g., for a
large unit in which many different wastes were managed over a long period or in
cases where wastes have undergone physical and/or chemical changes over a long
period).  A complete historical waste characterization in such cases would not be
possible.  Other cases where  waste sampling  and analysis would generally be
inadvisable are those where  the waste is highly toxic (e.g., nerve gas) or explosive
(e.g., disposed munitions). In these cases, it may be more appropriate to sample the
environmental medium  of concern at locations  expected to indicate the highest
release concentrations.  Such sampling activities should  be  performed following
appropriate health and safety procedures (see Section 6).

     The extent of the release may  also dictate, to some degree, the selection of
monitoring constituents.  For  apparently small  releases (e.g., 5 square yards of
contaminated soil), it may be reasonable to base all analyses on specific monitoring
constituents.  For larger releases, the  use of indicator parameters along with specific
monitoring constituents may be  a better  approach.   In this case, an appropriate
balance between indicator parameters and monitoring constituents is advisable.

     In addition, the potential  for physical, chemical, or biological transformations
(e.g., degradation) of constituents should also be considered in identifying monitor-
ing constituents. Biodegradation may be of particular importance for the soil and
surface-water media. For example, trichloroethylene in a waste unit or medium can
degrade over time to vinyl chloride and other products. Such products may be
present at higher concentrations than the parent trichloroethylene and may also be
more toxic. Therefore, the selection of monitoring constituents should consider the
potential for  constituents to  be transformed over time. Each of the media-specific
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sections contains a discussion of physical, chemical, and biological transformation
mechanisms.

     Another approach that may be taken in selecting monitoring constituents for
a particular medium  is to  use physical and  chemical property data, such as the
octanol/water partition coefficient or solubility, to predict which constituents may
be present in a given medium.  Further guidance on the use of this approach,
including tables presenting data on relevant physical and chemical properties of
various constituents, is presented in the following reference:

     U.S. EPA. October,  1986.  Superfund Public Health Evaluation Manual.  EPA
     540/1-86/060.    NTIS  PB87-183125.   Office of Emergency  and  Remedial
     Response. Washington, D.C. 20460.

     Case Study  Numbers  1,  2, 4, 9, and 10 in Volume IV (Case Study Examples)
illustrate application of the concepts discussed above.

3.6.2      Use of EPA and Other Methods

     As described in  the preceding  sections, and in the media-specific sections
(Sections 9 through 13), many different types of methods  may be employed in
conducting the  RFI.   These include methods  for sampling,  QA/QC, and field
operations, as welt as methods for physical, biological, and chemical analyses. These
methods were developed by various organizations, including EPA, other Federal
and State agencies, and by "standard-setting" organizations [e.g., ASTM, (American
Society for Testing and Materials)]. Some of these methods are final, while others
are in draft or proposed status.  As discussed previously, the  RFI Work Plan should
propose methods that best suit the needs of the situation  under investigation.
Guidance in the following sections, and in the media-specific sections, is given on
methods recommended in certain situations, including appropriate references. The
following discussion highlights some general guidelines to follow in the selection of
methods:

     •    Use of EPA  Methods:
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EPA recently published the 3rd Edition of its testing manual for solid
waste (U.S. EPA.   1986.  Test Methods for Evaluating Solid  Waste.
EPA/SW-846, GPO No. 955-001-00000-1),  generally known as SW-846.
This manual provides QA/QC methods, analytical methods, physical and
chemical property test methods, and sampling and monitoring methods.
These methods are acceptable for the RFI and contain guidance  on
unique problems that may be encountered during solid and hazardous
waste investigations. Where possible, it is recommended that SW-846 (or
equivalent) methods be used over other available methods. SW-846,
however, may not provide all methods applicable in certain situations. In
such cases, other EPA methods manuals (including EPA Regional Office
methods  manuals)  may be used.  One such  document that should  be
particularly useful is EPA's Compendium of Field Operations Methods.
developed by the Office of Emergency and Remedial Response (OSWER
Directive  No.  9355.0-14,  EPA 540/P-87/001A,  August 1987).   This
document provides discussions of various methods that can be applied in
field investigations, and includes general  considerations for  project
planning, QA/QC, and  sampling design.  Specific methods presented
include:

    Rapid field screening procedures (e.g.,  soil gas surveys using
    portable field instruments);

    Drilling in soils;

    Test pits and excavation;

    Geological reconnaissance;

    Geophysics;

    Ground-water monitoring;

    Physical and chemical properties;

    Surface hydrology;
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         Meteorology;

         Biology and Ecology/Bioassay and Biomonitoring; and

         Surveying, Photography, and Mapping.

•    Use of Other Federal or State Methods:

     The Occupational Safety and Health Administration (OSHA), the Food
     and Drug Administration (FDA), and several other Federal agencies have
     developed methods and methods manuals for specific applications. In
     addition, State and EPA Regional Offices have also developed methods
     and methods manuals. These methods may also be used during release
     investigations, if appropriate.  The media-specific  sections of this
     Guidance identify where such methods may be particularly applicable.

•    Use of Other Methods:

     Several  "standard-setting"   organizations   are   involved  in  the
     development of  test methods  for  various  applications.   One  such
     organization, the ASTM, publishes test methods and other standards in
     its Annual Book of ASTM Standards, which is updated yearly. Many of
     ASTM's methods may be applicable for use in the  RFI; however, if
     comparable EPA methods exist, they are preferred because they often
     contain important information necessary for regulatory purposes.

Many ASTM and EPA methods are similar and some are identical. The primary
reason for this is that many EPA methods are derived from ASTM methods.
Some of ASTM's methods are adopted by EPA in toto. EPA's Compendium of
Field Operations Methods, for example, contains many ASTM  methods that
can be used during an RFI.

Although ASTM's Committee D-34 on  Waste Disposal has only published
several final methods (ASTM. 1986 Annual Book of ASTM Standards. Volume
11:04), it has many other methods currently in various stages of development.
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     Several methods under development that may be applicable to the RR process
     are expected to be finalized and available soon.

     Other organizations are also involved in the development and standardization
     of test methods. Many industrial and environmental association methods can
     also be used during an RFl. EPA's Compendium of Field Operations Methods
     identifies several of these.

     AH methods proposed for use by the owner or operator should  be clearly
     described and adequately referenced.

3.6.3     Sampling Considerations

     This section discusses several considerations important in designing a sampling
plan, including sample types, and pertains to sampling of the waste source and the
affected environmental media. Section 7 contains additional guidance on waste
source sampling.  A general discussion of sampling equipment and procedures is
presented in EPA's SW-846. Other guidances containing general information that
can be used in designing a sampling plan include the following:

     U.S. EPA. August, 1987. Compendium of Field Operations Methods. Office of
     Emergency and Remedial Response.  OSWER Directive No. 9335.0-U.  EPA
     540/P-87/001A. Washington, D.C. 20460.

     U.S. EPA. 1985.  Practical Guide for Ground-Water Sampling. Robert S. Kerr
     Environmental Research Laboratory. EPA/600/2-85/104. Ada Oklahoma.

     U.S. EPA. 1986. RCRA Ground-Waster Monitoring Technical  Enforcement
     Guidance Document. OSWER Directive No. 9950.1.  Office of Waste Programs
     Enforcement. Washington, D.C. 20460.

     U.S. EPA. July 24, 1981.  RCRA Inspection Manual.  Section V. Office of Solid
    Waste. Washington, D.C. 20460.
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     U'.S. EPA. June,  1985.  Guidance on Remedial Investigations Under CERCLA.
     Office of Emergency and Remedial Response. NT1S P885-238616. Washington,
     D.C. 20460.

     U.S. EPA. May, 1984. Soil Sampling Quality Assurance Users Guide. CR81055Q-
     01. NTISPB84-198621. Washington, O.C. 20460.

3.6.3.1   General Sampling Considerations

     Various methods exist for obtaining acceptable samples of waste and for each
medium described in this document. Each of the media-specific sections (Sections 9
through 13) describes appropriate methods. The RFI Work Plan should propose
methods that best suit the needs of the sampling effort.  The following criteria
should be considered in choosing such methods:

     •   Representativeness-The selected methods  should be capable  of pro-
         viding a true representation of the situation under investigation.

     •   Compatibility with Analytical Considerations-Sample integrity must be
         maintained to the maximum extent possible.  Errors induced by poorly
         selected sampling techniques  or equipment can  result  in poor data
         quality.  Special consideration should be given  to the selection of
         sampling methods and equipment to prevent adverse effects  during
         analysis. Materials of construction, sample or species loss, and chemical
         reactivity are some of the factors that should receive attention.

     •   Practicality-The selected  methods should stress  the  use of simple,
         practical, proven procedures capable of being used in or easily adapted
         to a variety of situations.

     •   Simplicity and Ease of Operation-Because of the nature of the material
         to  be sampled, the physical hazards that may  be encountered during
         sampling, and the wearing of safety equipment, the proposed sampling
         procedures should be relatively easy to follow and equipment simple to
         operate.   Ideally, equipment should be  portable, lightweight,  and
         rugged.
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     •    Safety-The  risk to sampling  personnel and  others,  intrinsic safety of
          instrumentation, and safety  equipment required for  conducting  the
          sampling should be carefully evaluated.

3.6.3.2    Sample Locations and Frequency

     Because conditions in the unit or in the contaminant release will change both
temporally and  spatially, the design  of the  monitoring network should  be
developed accordingly.   Spatially,  sufficient samples should  be collected  to
adequately define the extent of the  contamination.  Temporally, the plan should
address spreading of the release with time and variation of concentrations due to
factors such  as  changes in  background  concentrations, waste  management
practices,  unit operations, the composition of  the waste, and climatic and
environmental factors. For example, sampling and  supplemental measurements
(e.g., wind speed) should  be  conducted when releases are most likely  to  be
observed, when possible.

     Selection of specific sampling locations and times will be site- and release-
dependent.  Three general approaches can be used in selecting specific sampling
locations.  Selection  of a particular approach depends on the level of knowledge
regarding the release.   Judgmental sampling generally  involves selection  of
sampling locations based on existing knowledge of the release configuration (e.g.,
visual evidence or geophysical data). A systematic approach involves taking samples
from locations established by a predetermined scheme, such as a line or grid. Such
samples can help to establish the boundaries of a contaminated area.  Random
sampling involves use of a "randomizing scheme," such as a  random number table,
to select locations within the study area. Random sampling can be useful when
contaminant spatial distribution is expected to be highly variable. Regardless of the
sampling approach taken, it is recommended that a coordinate (grid) system be
established at the site  to describe and record sampling locations accurately. As a
release investigation progresses, and as more information  regarding  a release is
gathered,  the sampling approach may be varied as appropriate. Application of
judgmental, systematic, and random sampling is discussed below.
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3.6.3.3   Judgmental Sampling

     Judgmental sampling is appropriate when specific information exists on the
potential configuration of a  release.  Many releases are likely to  fall into this
category, because site layout or unit  characteristics will  often indicate areas of
potential contamination. Examples of judgmental sampling include:

     •   Taking air samples at areas generally downwind of a unit;

     •   Taking grab  samples of surface soils  from a  drainage  channel that
         receives surface runoff from a known contaminated area; and

     •   Obtaining soil cores downslope from a known waste burial site.

     Judgmental sampling will generally bias the data obtained toward higher
contaminant concentrations.   For example, samples taken only from areas of
suspected contamination would generally be biased toward higher concentrations.
In many cases, this approach will suit the needs of the RFI.

3.6.3.4   Systematic or Random Grid Sampling

     Systematic or random grid sampling allows the  collection of a set of unbiased
samples at  the area of concern.  These  samples can be used for detection of
contamination, for calculation of averages (e.g., for characterizing the contents of a
surface impoundment when  it is expected to be fairly homogeneous), and for
modeling purposes. The size and shape of the grid should consider site-specific
factors.  However, some general recommendations can be made for effective grid
planning. The following steps are recommended in establishing a grid system:

     (1)  Choose the study area  to be included in the grid.  To define the full
         extent of the contaminated area, this area should be larger than the
         suspected extent of contamination.

     (2)  Select the shape and spacing of the grid. The shape may vary (e.g.,
         rectangular, triangular, or radial), depending  on the needs of the in-
         vestigation.  The grid spacing should be  based on consideration of the
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         appropriate density of sampling points. For example, an initial sampling
         effort in an area of widespread, homogeneous contamination may use a
         200-foot grid, whereas a search for "hot spots" in a poorly defined
         contaminated area might require a 50-foot or smaller spacing.

     (3)  Draw (or overlie) the sampling grid on a plan of the site. To  minimize
         sampling bias, a random number table may be used to choose sampling
         cells.

     (4)  Transfer the grid onto the study area by marking grid line intersections
         with wooden stakes.  The exact location of the sample within each grid
         cell may be chosen systematically (e.g., at each node) or randomly (i.e.,
         anywhere within each cell).

     Figure 3-1 a shows a systematic grid with samples taken at each node. Random
grid sampling produces a sampling distribution such as that shown in Figure 3-1 b.  A
possible  limitation of  systematic grid  sampling  is that if contaminants  are
distributed in a regular pattern, the sampling points could all lie within the "clean"
areas (Figure 3-1c).   This possibility should  be considered  when proposing  a
sampling approach.

3.6.3.5   Types of Samples

     The owner or operator should propose the types of samples to be collected
with the monitoring procedures.  In general, there are three basic sample types:
grab, composite, and integrated, as discussed below.

     •   Grab sampling--A grab sample is an individual sample taken at a specific
         location at a specific time. If a contaminant source or release is known to
         be fairly constant in composition over a considerable period of time or
         over substantial distances in all directions, then the sample may serve to
         represent a longer time period or a larger volume (or both) than the
         specific point and time at which it was collected.

         When a contaminant source or release is known to vary with time, grab
         samples collected  at suitable  intervals  and analyzed separately  can
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        a) SYSTEMATIC GRID SAMPLING
         b) RANDOM GRID SAMPLING
            X a BURIED WASTE

c) CASE IN WHICH SYSTEMATIC GRID SAMPLING MISSES
  WASTES BURIED IN A REGULAR PATTERN
         FIGURE 3-1. GRID SAMPLING.
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indicate the magnitude and duration of variations. Sampling intervals
should be chosen on the basis of the frequency with which variations
may be expected. It may not always be desirable to take samples at equal
intervals (e.g.,  subsurface  gas  releases  are sensitive  to  seasonal
influences). If sample composition is likely to show significant variation
with time and  space, grab  samples  from appropriate locations are
recommended.

Composite samples-Composites  are  combinations  of more than one
sample collected at  various sampling locations and/or different times.
Analysis of composites generally yields average values which may not
accurately describe the distribution of release concentrations or identify
hot spots. Compositing does  not reflect actual concentrations and can
reduce some concentrations to below detection limits.  Composites may,
in limited instances, be used  to reduce the number of individual grab
samples (e.g., when calculating an average value is appropriate).  For
example, compositing waste samples from a surface impoundment may
be  performed to determine  an  average value over  several  different
locations. Compositing may  also be  useful in determining the  overall
extent of a contaminated area, but should not be used as a substitute for
characterizing   individual  constituent  concentrations.   Therefore,
compositing should be limited and should always be done in conjunction
with an adequate number of grab samples.

Integrated samples--An integrated sample  is typically  a  continuously
collected single  sample taken to describe a population in which one or
more parameters vary with either time or space. An integrated sampling
technique can account for such variations by collecting one sample over
an extended time period, such that variations can be averaged over that
period.  The most common parameter over which sampling periods are
integrated is time.  Time-integrated samples can provide an average of
varying concentrations over the period sampled.

Integrated sampling may be  appropriate under limited circumstances.
For example, process stream flows often change with variations in. the
process itself or  with environmental conditions, such as  wind speed. A
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         flow-integrated sampling device can collect a sample over a period of
         time as the sampling rate increases or decreases with the rise and fall of
         the stream  flow.  The device  automatically  biases sample  collection
         toward those periods of high flow,  with sampling  rates decreasing
         during low- flow periods.

         Integrated samples can be particularly useful for air and surface-water
         investigations where continuous changes in environmental conditions
         can affect constituent concentrations. See Sections 12 and 13 (air and
         surf ace water, respectively) for more information.

3.6.4     Analytical Methods and Use of Detection Limits

     Analytical methods should be appropriate for the constituents and matrices
being sampled.  As indicated previously, the  EPA publication Test Methods for
Evaluating Solid Waste (EPA/SW-846), should be used as the primary reference for
analytical methods. This document contains analytical methods that can be applied
to solid, liquid, and gaseous matrices, and also presents detection limits generally
associated with these methods. It is important to understand that detection limits
can vary significantly depending on the medium (e.g., air, water, or soil) and other
matrix-specific factors (e.g., presence of multiple contaminants). In addition to SW-
846, the following reference provides detection limit information for water and soil
matrices:

     U.S. EPA.   March, 1987.   Data Quality Objectives for  Remedial Response
     Activities. Volume 1 (Development Process) and Volume 2 (Example Scenario).
     Office of Emergency and Remedial Response and Office of Waste Programs
     Enforcement.    EPA  540/G-78/003a.   OSWER Directive No.  9335.0-7b.
     Washington, D.C. 20460.

Detection limits should be stated along with the proposed analytical methods in the
RFl Work Plan. Analytical values determined to be at or below the detection limit
should be reported numerically (e.g., <0.1 mg/l).
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3.7        RFI Decision Points

     As monitoring data become available, both within and at the conclusion of
discrete investigative phases, they should be reported to the regulatory agency as
directed.  The regulatory agency will compare the monitoring data to applicable
health and environmental criteria to determine the need for (1) interim corrective
measures; and (2)  a CMS.  In addition, the regulatory agency will  evaluate  the
monitoring data with respect to adequacy and completeness to determine the need
for any additional monitoring efforts. The health and environmental criteria and a
general discussion of how the regulatory  agency will apply them are supplied in
Section 8.  A flow diagram illustrating RFI decision points is provided in Figure 3-2.

     Notwithstanding the above process, the owner or operator has a continuing
responsibility to identify and respond to emergency situations and to define priority
situations  that may warrant interim corrective measures. For these situations,  the
owner or operator is directed to follow the RCRA Contingency Plan requirements
under 40 CFR  Part 264, Subpart D.
                                   3-35

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    a
    o
 -
11
= u
                                    3-36

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              FOOTNOTES FOR FIGURE 3-2
  .dtntity a"" '"^ntenm corrective m«,u,~.
  that may warranting                ^ant,fied as "suspected by


•  ssssESsS ass?1:—•" ™ -
  imminent.                        assessment criteria are
              ... L.-,i*h and environmental a5,se5\,aea fritena are
    lied at the unit or waste ma  y                ^ ^^ requ.red
                        3-37

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                                SECTION 4

            QUALITY ASSURANCE/QUALITY CONTROL PROCEDURES
4.1       Overview

     Quality  assurance (QA)  is a management system  for ensuring  that  all
information, data, and decisions resulting from the RFI are technically sound and
properly documented. Quality control (QC) is the functional mechanism  through
which quality assurance achieves its goals. Quality control programs, for example,
define the frequency and methods of checks, audits, and reviews necessary  to
identify problems and dictate corrective action to resolve these problems, thus
ensuring data of high quality.  Thus, a QA/QC program pertains to  all data
collection, evaluation, and review activities that are part of the RFI.

     Data generated during the RFI will provide the basis for decisions on corrective
measures; therefore, the data should present a valid characterization of the
situation.  Utilization of erroneous or poor-quality data in reporting RFI results may
lead to unnecessary repetition of sampling and analysis or, more importantly, to
faulty decisions based on poor results. The  owner or operator should  develop
adequate QA/QC procedures for the RFI.  Implementation of these procedures will
allow the  owner or operator to monitor and document the quality of the data
gathered.

     The next portion of this section (4.2) describes the general design of a QA/QC
program. The following portions of this section (Sections 4.3 and 4.4) outline and
describe important QA/QC considerations that should be accounted for in the
performance of sampling and analysis.

     Section 4 is not intended to constitute a complete guide to constructing QA
project plans or QC programs. EPA has established, through the issuance of various
documents, guidance describing the development and implementation of QA/QC
programs that can be used to design effective QA/QC procedures for the RFI. Th«
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final portion of this section (Section 4.5) presents references that provide additional
guidance in constructing appropriate QA/QC procedures for the RFI.

    When selecting field personnel and analytical services to perform any  RF!
activity, the owner or operator is encouraged to evaluate available QA/QC programs
and procedures in light of the information and references provided in this section.
Participation  in  internal and/or external  (e.g., Federal  or State) laboratory
validation/certification  programs may be  particularly important in selecting
laboratory services.

    Case Study No. 5 in Volume IV (Case Study Examples) provides an example of
an effective QA/QC program.

4.2       QA/QC Program Design

    The initial step for any sampling or analytical work should be to strictly  define
the program goals.  Once these goals have been defined, a program can be
designed to meet them. QA and QC measures are used to monitor the program and
to ensure that all data generated are suitable for their intended uses.  The
responsibility of ensuring that the QA/QC measures are properly employed  should
be assigned to a knowledgeable person (i.e., a QA/QC specialist) who is not directly
involved in the sampling or analysis.

    One approach found to provide a useful  structure for a QA/QC program is
preparing both program and project-specific QA/QC plans. The program plan sets
up basic policies, including QA/QC, and may include standard operating procedures
(SOPs) for specific methods. The program plan serves as an operational charter for
defining  purposes, organizations, and operating principles.  Thus, it is an orderly
assemblage of management policies, objectives, principles, and general procedures
describing a plan for producing data of known and  acceptable quality.  The
elements of a program plan and its preparation are described in the following
reference:

    U.S. EPA. September 20. 1980.  Guidelines and  Specifications for Preparing
    Quality Assurance Program  Plans.  Office of Monitoring Systems and Quality
    Assurance. EPA/QAMS-004/80. NTISPB83-219667. Washington, O.C. 20460.
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     Project-specific QA/QC plans differ from program plans in that specific details
 of a particular sampling/analysis program are addressed. For example, a program
 plan might state that all equipment will be calibrated according to  a specific
 protocol given in written SOPs, while a project plan would state that a particular
 protocol will be  used to calibrate the equipment for a specific set of analyses that
 have been defined in the plan. The project plan draws on the program plan for its
 basic structure and applies this management approach to specific determinations.
 An organization or laboratory would have only one QA program plan, but would
 have a QA project plan for each of its projects. The elements of a project plan and
 its preparation,  presented in Table 4-1, are described in detail in the following
 reference:

     U.S. EPA.   December 29, 1980.  Interim Guidelines and Specifications for
     Preparing Quality Assurance Project Plans. Office of Monitoring Systems and
     Quality Assurance.  EPA/QAMS-005/80.  NTIS PB83-1705U. Washington, D.C
     20460.

 4.3      Important Considerations for a QA/QC Program

     The use of qualified personnel for conducting various portions of the RFI is of
 paramount importance to an effective QA/QC program. This pertains not only to
 qualified QA/QC specialists, but also to specialists in other fields, including
 hydrogeologists, air quality specialists, soil scientists, analytical chemists and  other
 scientific and technical disciplines.  The owner or  operator should ensure that
 qualified specialists, primarily individuals with the proper education, training, and
 experience,  including licensed or  certified professionals,  are  directing and
 performing the various RFI activities. The same general principles apply to selection
of contractors and/or outside laboratories.

4.3.1     Selection of Field Investigation Teams

     The owner or operator should consider  the following factors when selecting
any field investigation team.

     •   Level of expertise and/or training required (e.g., experience, references);

                                    4-3

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                                TABLE
                ESSENTIAL ELEMENTS OF A QA PROJECT PLAN

1.   Title Page

2.   Table of Contents

3.   Project Description

4.   Project Organization and Responsibility

5.   QA Objectives

6.   Sampling Procedures

7.   Sample Custody

8.   Calibration Procedures and Frequency

9.   Analytical Procedures

10. Data Reduction, Validation, and Reporting

11. Internal Quality Control Checks

12. Performance and System Audits

13. Preventive Maintenance

14. Specific Routine Procedures Used to Assess Data Precision. Accuracy, and
    Completeness

15. Corrective Action

16. Quality Assurance Reports to Management
                                    4-4

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     •    Available workforce; and

     •    Time and equipment constraints.

4.3.2      Laboratory Selection

     The owner or operator should consider the following factors when selecting a
laboratory:

     •    Capabilities (facilities, personnel, instrumentation), including:

               Participation in interlaboratory studies (e.g., EPA or other Federal
               or State agency sponsored analytical programs);

               Certifications (e.g., Federal or State);

               References (e.g., other clients); and

               Experience (RCRA and other environmentally related projects).

     •    Service.

               Turnaround time; and

               Technical input (e.g., recommendations on analytical procedures).

     The owner or operator is encouraged to gather pertinent laboratory-selection
information prior to extensively defining analytical requirements under the RFI. A
request may be made to a laboratory to  provide a qualifications package that
should address the points listed above. Once the owner or operator has reviewed
the various laboratory qualifications, further specific discussions with the laboratory
or laboratories should take place. In addition, more than  one laboratory should be
considered.  For large-scale investigations, selection of one laboratory as a primary
candidate and one  or two laboratories as fall-back candidates should be considered.
                                    4-5

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                  4-6

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     •   Selecting the frequency  of sampling and duration of the sampling
         period;

     •   Selecting the types of samples (e.g., composites  and grabs) to be
         collected;

     •   Detailing methods of sample preservation; and

     •   Detailing methods of sample chain-of-custody.

(3)   Documentation of field sampling operations and procedures, including:

     •   Documentation of procedures for preparation of reagents or supplies
         that become an integral part of the sample (e.g., filters and adsorbing
         reagents);

     •   Documentation of procedures and forms for recording the exact location
         and specific considerations associated with sample acquisition;

     •   Documentation of specific sa./iple preservation methods;

     •   Calibration of field devices;

     •   Collection of replicate samples;

     •   Submission of field blanks, where appropriate;

     •   Detailing of potential interferences present at the facility;

     •   Listing of construction  materials and  techniques associated with
         monitoring wells, piezometers, and other monitoring equipment;

     •   Listing of field equipment and sample containers;

     •   Copy of sampling order; and

                                   4-7

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     •   Documentation of decontamination procedures.

(4)   Analytical procedures, including:

     •   Appropriate analytical methods;

     •   Appropriate sample storage;

     •   Appropriate sample preparation methods;

     •   Appropriate calibration  procedures; and

     •   Data management (e.g., review,  reporting, and  recordkeeping)
         procedures.

(5)   Planning for the inclusion of proper and sufficient QA/QC activities, including
     the use of QC samples, throughout the study is necessary to ensure that the
     quality of the sampling and analytical data will meet the objectives of the RFI.

     The factors and considerations described above are important for any
environmental monitoring and  measurement project. If these factors are
adequately addressed (i.e., appropriate procedures are developed, tasks are
assigned to qualified personnel, and sufficient QA/QC steps are employed), the
goals of the RFI should be met. If the QA/QC procedures are sound, problems will be
detected early, enabling the appropriate corrective actions to be taken.

     [Note that the term "corrective action," in the context of a QA/QC program
pertains to actions taken as a result of problems (e.g..  sample contamination)
uncovered by an effective QA/QC program. This should not be confused with the
corrective measures that may be applied as a result of the RFI. Corrective actions as
a result of QA/QC are discussed in Section 4.4.10.]
                                   4-8

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4.4      QA/QC Objectives and Procedures

     The following describes the  general components of QA/QC objectives and
procedures. Specific references regarding recommended procedures are presented
in Section 4.5.

4.4.1     Data Quality and Use

     Throughout the RFI process, it is important that the owner or operator keep m
mind the eventual use to which data will be put;  that is, comparison of data to
health  and environmental criteria to determine whether some form of corrective
measure may be necessary to correct the release. Therefore, data collected during
the investigation needs to be of sufficient quality to support  decisions regarding
whether interim corrective measures and/or a CMS may be necessary.

     Qualitative or quantitative  statements  that outline the decision-making
process and specify the quality and quantity of data required to support decisions
should be made early in the planning stages of the RFI.  These data quality
objectives (DQOs) are then used to design  sampling  and analysis plans and to
determine the appropriate level of QA/QC.

     The following discussion concerning DQOs is summarized from the following
document:

     U.S. EPA.  March, 1987.  Data Quality Objectives for Remedial Response
     Activities. Volume V.  Development  Process.  Volume 2:  Example Scenario.
     EPA 540/G-87/003a.  OSWER Directive No. 9335.0-7B. Office of Emergency and
     Remedial Response and Office of Waste Programs Enforcement. Washington,
     D.C. 20460.

     This document may be reviewed for more detailed information. The Example
Scenario (Volume 2) may  be particularly helpful in understanding the overall DQO
process.

     The first step in  the process of developing DQOs involves defining the
decisions to be made based on the data and the objectives of the investigation. The
                                   4-9

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second step is defining a set of objectives (DQOs) that can be used to design the
sampling and analysis plan and determining the appropriate level of QA/QC..
Ultimately, these DQOs are also used to  determine the adequacy of the data m
terms of whether their quality and quantity are sufficient to enable confident
decision-making. This process of defining the objectives of the investigation and
designing data-gathering efforts to meet these objectives, should be initiated prior
to starting the investigation. Refinements or revisions to these objectives may also
be necessary as the investigation progresses.

     The criteria most commonly used to specify DQOs and to evaluate available
sampling, analytical, and QA/QC options are known  collectively as the Precision,
Accuracy, Representativeness, Completeness, and Comparability  (PARCC)
parameters. A brief description of these follows:

     •    Precision - a measure of the reproducibility of analyses under a given set
          of conditions.

     •    Accuracy - a measure of the bias in a measurement system.

     •    Representativeness - the degree to which sampling data accurately and
          precisely represent selected characteristics.

     •    Completeness - a measure of the amount of valid data obtained from a
          measurement system compared to the amount that could be expected to
          be obtained under "normal" conditions.

     •    Comparability - the degree of confidence with which one data set can be
         compared to another.

     When using these parameters to assess data quality,  only  precision  and
accuracy can be expressed in purely quantitative terms.  The other parameters are
best expressed using a  mixture of quantitative and qualitative terms.  All these
parameters are interrelated in terms of overall data quality and may be difficult to
evaluate separately due to these interrelationships.  The  relative significance of
each parameter depends on the type and  intended use of the data being collected.
Each parameter is addressed in  further detail  below.
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     Precision is a measure of the scatter of a group of measurements made at the
same specified conditions around their average.   Values calculated  should
demonstrate the reproducibility of the measurement process.  Determination of
precision  in  relation to the RFI deals primarily with sampling and analytical
procedures. The sample standard deviation and sample coefficient of variation are
commonly used as indices of precision. The smaller the standard deviation and
coefficient of variation, the better the precision.

     Precision is stated in units of measurement or as a percentage of the
measurement average, as a plus and minus spread around the average measured
value. There are many sources of variation or error within any measurement system.
Depending on the nature of the investigation, variation or error may be introduced
at various stages.  Examples of these are sample collection, handling, shipping,
storage, preparation, and  analysis. When summarizing orecision determinations,
the component or components of the measurement system that are included should
be noted. The stage at which a  replicate is placed within the measurement system,
for example, generally  dictates the components that affect the precision determi-
nation.

     Accuracy is defined as the agreement of a measurement with an accepted
reference  or true value.  This  is normally expressed  as the difference between
measured and reference or true values or the difference as a percentage of the
reference  or true value. It may  also be expressed  as a ratio of the measurement to
the true value. Accuracy is a measurement of system bias.

     The determination of accuracy or bias within the measurement system  is
generally accomplished through the analysis of the neat sample (e.g., distilled water
as opposed to  pond or local water) and the analysis of the sample spiked at a
known concentration utilizing a standard reference material.  As in the case of the
precision determination, the point at which the sample is spiked determines which
components of the measurement system have an effect on the accuracy of the
analysis. The three sample spiking points are sample acquisition (field matrix spike);
preparation (lab matrix spike); and analysis (analysis matrix spike). The field matrix
spike provides a best-case estimate of bias based on recovery. It includes matrix
effects associated with  sample  preservation, shipping, preparation,  and  analysis.
                                   4-11 -

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The lab matrix i>pike provides an estimate of recovery incorporating matrix effects
associated with sample preparation and analysis only. The analysis matrix spike
provides an indication of matrix effects associated with the analysis process only, in
addition to the above sample spiking points, the analysis of a known concentration
of a standard reference  material into the appropriate method solvent (e.g.,
deionized water, methanol, 2 percent nitric acid, etc.) provides an indication of the
accuracy of the analytical system calibration.
            -*

     Completeness is defined as the measure of the amount of valid data obtained
from a measurement system compared to the amount that could be expected to be
obtained under "normal" conditions. The completeness goals should be identified,
to the extent possible, at the beginning of the RFI to  ensure that sufficient valid
data are  collected to  meet the RFI objectives and to provide a measurement
whereby the progress of the RFI may be monitored during data collection.

     QA/QC procedures may benefit through tabular presentations of the precision,
accuracy, and completeness goals for the work performed under the RFI.

     Representativeness expresses the degree  to which data  accurately and
precisely  represent a characteristic of  a population,  parameter variations at a
sampling point,  a process condition,  or an environmental condition.  QA/QC
procedures should address all data gathering with regard to representativeness. All
RFI data compilation should reflect as  precisely and as accurately  as possible the
conditions that existed at  the time of measurement.   Examples of factors that
should be considered include:

     •    Environmental conditions at the time of sampling;

     •   Fit of the modeling or other estimation techniques to the event(s);

     •   Appropriateness of site file information versus release conditions;

     •   Appropriateness of sampling and analytical methodologies;

     •   Number of sampling points;
                                   4-12

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     •    Representativeness of selected media; and

     •    Representativeness of selected analytical parameters.

     Comparability is defined  as an expression of the confidence with which one
data set can be compared to another.  In terms of the RFI, comparability may  be
applied to:

     •    RFI data generated by the owner or operator over a specifictime period;

     •    Data generated by an outside laboratory over a specific time period;

     •    RFI data generated  by an outside laboratory versus data generated  by
          the owner or operator; and

     •    Data generated by more than one outside laboratory.

     The utilization of standard  methodologies for the various data generation
categories (e.g., sampling, analysis, geological, and  meteorological) should ensure
data comparability.  The owner or operator should take the appropriate measures
to ensure the comparability of data compiled under the RFI.

     The PARCC parameters are indicators of data quality.  Ideally, the end use of
the measurement data should define the PARCC parameters necessary to satisfy
that end use. Ideally, numerical precision, accuracy, and completeness goals should
be established to aid in selecting measurement methods to be used. However, RFI
work may not fit this ideal situation.  RFI sites are likely to differ substantially from
one another,  and information on overall measurements (e.g., sampling and
analysis) may be limited such that it may not be practical to initially set meaningful
PARCC goals. In such  cases, the historical precision and accuracy achieved  by
different sampling and analytical techniques should be reviewed to aid in selecting
the most appropriate technique. Only those techniques that have been adequately
evaluated (e.g., precision and accuracy studies),  and which  therefore  have a
documented history of acceptable performance, should be proposed for use.
                                   4-13

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     Precision and accuracy statements and detection limit information  for
analytical methods can be found in the DQO document referenced earlier in this
section, as well as the following reference:

     U.S. EPA.  November, 1986.  Test Methods for Evaluating Solid Wastes.
     EPA/SW-846. GPO No. 955-001-00000-1.  Office of Solid Waste.  Washington,
     D.C. 20460.

     Each of the PARCC parameters should be considered in evaluating sampling
and analysis options. To the extent possible, they should be defined as goals to be
achieved by the data collection program. It should be recognized, however, that
OQOs can be developed for RFI work without strictly defined PARCC goals.

     Whenever measurement data are reviewed, the PARCC parameters should be
included in the review. Precision and accuracy data may be expressed in several
ways and are best evaluated by an analytical chemist or a statistician.  The data
reviewer should keep the action levels (health and environmental criteria) and the
end use of the data in mind when reviewing precision and accuracy information. In
some cases, even data of poor precision and/or  accuracy may be  useful.  For
example, if all the results are far above an action level, the precision and accuracy
are less important. However, dose to the action level, precision and  accuracy are
much more important and should be carefully reviewed. If results have very good
precision but poor accuracy, correcting  the reported results  using  the percent
recovery or percent bias data may be acceptable.

4.4.2     Sampling Procedures

     To ensure that sample collection will provide high quality and representative
data, the owner or operator is advised  to  carefully select appropriate sampling
procedures that will meet the objectives of the investigation. Some factors to
consider in choosing the best sampling methodologies include the following:

     •   Physical and chemical properties of the medium to be sampled;

     •   Relative and absolute concentrations of analytes of concern;
                                   4-14

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     «    Relative importance of various analytes to RFI objectives;

     •    Method performance characteristics;

     •    Potential interferences at the site; and

     •    Time resolution requirements.

     QA/QC procedures relevant to sampling activities should also be formulated
and followed during any site environmental characterization. These procedures
should include a description of the techniques to be utilized in performing tasks
such as well drilling, stratigraphic analysis,  meteorological measurements, and
surface water flow measurements.  More information  can be found in  the
references identified in Section 4.5, and in the media-specific sections (Sections 9
through 13).

4.4.3      Sample Custody

     An essential part of  any program  that requires sampling and analysis is
ensuring sample integrity from collection to data reporting.  This includes the ability
to trace the possession and handling of samples from collection through analysis
and final disposition. The documentation of the history of the sample is referred to
aschain-of-custody.

     Chain-of-custody procedures should identify  the components that will be
utilized for all sampling and analysis under the RFI, including a transfer in custody
and how the chain-of-custody procedures and documents will effectively  record
that transfer. The following sample custody procedures should be addressed:

(1)   Field sampling operations.

     •    Documentation  of procedures for preparation of reagents or supplies
          that become an integral part of the sample (e.g., filters and adsorbing
          reagents);
                                   4-15

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     •   Provision of procedures and forms for recording the exact location and
         specific considerations associated with sample acquisition;

     •   Documentation of specific sample preservation methods;

     •   Provision  of pre-prepared sample labels containing  all information
         necessary for effective sample tracking; and

     •   Establishment of standardized field tracking reporting forms to establish
         sample custody in the field prior to shipment.

(2)   Laboratory operations:

     •   Identification of a  responsible party to act as sample custodian at the
         laboratory facility authorized to sign for incoming field samples, obtain
         documents of  shipment, and verify the data entered onto the sample
         custody records;

     •   Provision  for  a laboratory sample custody  log  consisting of serially
         numbered standard lab-tracking report sheets; and

     •   Specification of laboratory  sample custody procedures for sample
         handling, storage, and dispersement for analysis.

4.4.4     Calibration Procedures

     Another important  consideration in any environmental measurement is the
calibration  of the measurement system. An improperly and/or  infrequently
calibrated system may have a serious negative impact on the precision and accuracy
of the determinations. The result will be erroneous data and the need to repeat the
measurements.  The calibration procedures utilized should  therefore be defined.
Points that should be addressed include:

     •   For each  measurement parameter,  including  all contaminant
         measurement systems, reference the applicable SOP or provide a written
         description of the calibration procedure(s) to be used;
                                   4-16

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     •    List the frequency planned for recalibration and/or the criteria utilized to
          dictate the frequency of recalibration; and

     •    List the calibration standards to be used and their source(s), including
          traceability procedures.

 4.4.5     Analytical Procedures

     The owner or operator should select analytical procedures that will meet the
 objectives of the  RFI.  Factors to consider in  choosing appropriate analytical
 methodologies include:

     •    Scope and application of the procedure;

     •    Sample matrix;

     •    Potential interferences;

     •    Precision and accuracy pf the methodology; and

     •    Method detection limits.

     EPA-approved methodologies, such as those identified in the 3rd edition of
 Test Methods for Evaluating Solid Wastes (EPA/SW-846) or equivalent, should be
 utilized when available.

     For each measurement parameter, including all contaminant  measurement
 systems, the owner or operator should reference the SOP or provide a written
 description of the analytical procedure(s) to be used in support of the RFl.  If any
 method modifications are anticipated due to the nature of the sample(s) being
 investigated, these modifications should be explicitly defined.

     An important factor to consider in any analytical procedure is  holding time.
Samples have a limited shelf life. Analysis should occur within the time specified by
the method.  This is especially important for organic contaminants.  For example,
                                    4-17

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volatile organic compound (VOC) analysis should occur within 2 weeks of sampling.
Acceptable sample holding times for all classes of Appendix VIII constituents are
discussed in Test Methods for Evaluating Solid Waste (EPA/SW-846).

4.4.6      Data Reduction, Validation, and Reporting

     This portion of the QA/QC procedures applies to all measurements performed
in support of the RF1.  The owner or operator should identify  the data reduction
scheme planned for collected data and include all equations and reporting units
used to calculate the concentration or value of the measured parameter.

     Data validation is the process of reviewing data and accepting or rejecting it
on the basis of sound  criteria.  Validation methods may  differ for various
measurements but the chosen validation criteria must be appropriate to each type
of data and the purpose of the  measurement.  Records of all data should be
maintained, even those  judged to be "outlying" or spurious values.  Personnel
assigned the responsibility of data validation should have sufficient knowledge of
the particular measurement system to identify questionable values.

     The owner or operator should identify the principal criteria  that will be
applied to validate data integrity during collection and reporting. In addition, the
methods that will be utilized to identify and treat outliers should be addressed. The
validation process should include mechanisms whereby data reduction is verified. In
the case of computerized data reduction, this may include subjecting a surrogate
data set to reduction by the software to ensure that valid results are produced.

4.4.7      Internal Quality Control Checks

     Quality control checks are performed to ensure  that the data collected  is
representative and valid data. Internal QC refers to all data compilation  and
contaminant measurements.  Quality control checks are the mechanisms whereby
the components of QA objectives are monitored.   Examples of  items to be
considered are as follows:
                                   4-18

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(1)   Field Activities:





     •    Use of standardized checklists and field notebooks;




     •    Verification of checklist information by an independent person;





     •    Strict adherence to chain-of-custody procedures;




     •    Calibration of field devices;




     •    Collection of replicate samples; and




     •    Submission of field blanks, where appropriate.





(2)   Analytical Activities:




     •    Method blank(s);




     •    Laboratory control sample(s);




     •    Calibration check sample(s',,





     •    Replicate sample(s);




     •    Matrix-spiked sample(s);




     •    "Blind" quality control sample(s);




     •    Control charts;




     •    Surrogate samples;




     •    Zero and span gases; and





     •    Reagent quality control checks.
                                    4-19

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     The owner or operator should consider those checks that will meet the QA
objectives of the RFI. In addition, the owner or operator should present, in tabular
format, the frequency with which each control check will be used.

4.4.8     Performance and Systems Audits

     A systems audit is a qualitative evaluation of all  components of the
measurement systems to determine their  proper selection  and use.  This audit
includes a careful review of all data-gathering activities and their attendant QC
procedures. Systems audits are normally performed before or shortly after systems
are operational.  However, such audits should be performed  at sufficiently regular
intervals during the lifetime of the RFI or continuing  operation. Systems audits
should be conducted by an individual who is technically knowledgeable about the
operation(s) under review and who is independent of any other contribution to the
RFI.  The primary objective of the systems audit  is to ensure that the QA/QC
procedures are being adhered to.

     After systems are operational and generating data, performance  audits are
conducted  periodically to determine the accuracy of the total  measurement
system(s) or component parts thereof.  Performance audits are quantitative
evaluations of the measurement system(s).  QA/QC procedures should include a
schedule for conducting performance audits for each measurement parameter
where all measurement systems are included.  Examples of performance auditing
mechanisms for analytical activities would be the inclusion of "blind" samples into
the normal sample flow, an analyst performing the analysis of a sample previously
analyzed by another analyst, and the results of any appropriate interlaboratory
study samples analyzed during the term  of the RFI.  Performance audit checks
relative to data handling operations might be the insertion  of erroneous
parameters into field records.  This should trigger the validation  procedures by
entering unreasonable combinations of responses.

4.4.9     Preventive Maintenance

     Preventive maintenance schedules ensure the maximum amount of active time
for analytical  instrumentation, field devices and instrumentation,  and computer
                                   4-20

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hardware over the course of the RF! program. The following types of preventive
maintenance should be considered:

     •    A schedule of important preventive maintenance tasks that must be
          carried out to minimize downtime of all measurement systems, and

     •    A list of any critical spare parts that should be on hand to minimize
          downtime.

4.4.10    Corrective Action for QA/QC Problems

     Corrective actions are those measures taken to rectify a measurement system
that is out of control.  [Note that the term  "Corrective Action," as used in this
section, is a common QA/QC term applied to  problem-solving activities, it should
not be confused with the RCRA Corrective Action Program.]  Corrective action may
be initiated by any person performing work in support of the RFI at any time. For
example, an analyst should be  familiar with the precision and accuracy of the
analysis that is being performed, if the results of the analysis are not within the
anticipated limits, there are appropriate corrective actions that should be initiated
by the analyst. There are, however, other checks within the measurement system
that only the person assigned QA/QC responsibilities would be in a suitable position
to evaluate and take action upon if required. A "blind" sample inserted  in the
normal sample flow would be an example of such a check.

     The corrective action procedures to  be utilized in the accomplishment of the
RFI objectives should be contained in the QA/QC procedures and should include the
following elements:

    •   The predetermined limits for data acceptability beyond which corrective
         action is required; and

    •   For each measurement system, the identity  of the individual responsible
         for initiating the corrective action and also the individual responsible for
         approving the corrective action, if necessary.
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     In addition to routine corrective actions taken by all personnel contributing to
the RF1, performance and systems audits may result in the necessity of more formal
corrective action.

4.4.11     Quality Assurance Reports to Management

     Another important aspect of the QA/QC program is the  communication
between the QA/QC organization  and the management organization.  Regular
appraisal by management of the quality aspects related to the ongoing  RFI data-
gathering efforts provides the mechanism whereby the established objectives may
be met.

     QA/QC procedures should provide details relating to the schedule, information
to be provided, and the mechanism for reporting to  management.  Reports to
management should include:

     •    Periodic  assessment of  measurement data accuracy, precision, and
          completeness;

     •    Results of performance audits;

     •    Results of system audits;

     •    Significant QA/QC problems and recommended solutions; and

     •    Resolutions of previously stated problems.

     The individual(s)  responsible for preparing the periodic reports should  be
identified. These reports should contain a separate QA/QC section that summarizes
data quality information.

4.5       References

     Following is a list of the major references, including EPA guidances,
recommended for use in designing effective QA/QC programs for RFIs:
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U.S. EPA. September 20, 1980. Guidelines'ard Specifications for Preparing Quality,
     Assurance Program Plans.  Office of Monitoring Systems and Quality
     Assurance. QAMS-004/80. NT1SPB83-219667.  Washington, O.C. 20460.

U.S. EPA. December 29, 1980. Interim Guidelines and Specifications for Preparing
     Quality Assurance  Project Plans.  Office of Monitoring Systems and Quality
     Assurance. QAMS-005/80. NTISPB83-170514.  Washington, D.C. 20460.

U.S. EPA. 1986. Test Methods for Evaluating Solid Wastes. 3rd Edition. Office of
     Solid Waste. EPA/SW-846.  GPO No. 955-001-00000-1. Washington,  D.C.
     20460.

U.S. EPA. August, 1987.  Compendium of Field Operations Methods. OSWER
     Directive No. 9355.0-14.  EPA/540/P-87/001A.  Office of  Emergency  and
     Remedial Response. Washington, D.C. 20460.

U.S. EPA. July, 1981. RCRA Inspection Manual. Office of Solid Waste. Washington.
     D.C. 20460.

U.S. EPA. June, 1985. Guidance on Remedial Investigations Under CERCLA. Office
     of Emergency and Remedial Response. NTIS PB 85-238616.  Washington,  D.C.
     20460.

U.S. EPA. May, 1984.  Soil Sampling Quality Assurance Users Guide. EPA 600/4-84-
     043. NTIS PB84-198621. Washington, D.C. 20460.

U.S. EPA. 1985. Sediment Quality Assurance Users Guide. EPA 600/4-85-048. NTIS
     PB85-233542. Washington, D.C. 20460.

U.S. EPA. March, 1987. Data Quality Objectives for Remedial Response Activities.
     Volume 1:  Development Process. Volume 2:  Example  Scenario.  EPA 540/G-
     87/003a. OSWER Directive No. 9335.0-7B.  Office of Emergency and Remedial
     Response and Office of Waste Programs Enforcement. Washington,  D.C.
     20460.
                                  4-23

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                                SECTION 5

                    DATA MANAGEMENT AND REPORTING

5.1       Data Management

     Release characterization studies  may result in significant amounts of data,
including  results of chemical, physical, or biological analyses.  This may involve
analyses of many constituents,  in different media, at various sampling locations,
and at different times.  Data management  procedures should be established to
effectively process these data such that relevant data descriptions (e.g., sample
numbers, locations, procedures, methods, and analysts) are readily accessible  and
accurately maintained.

     In order to ensure effective data management, the owner or operator should
develop and implement  a data management  plan  to document and track
investigation data and results. This plan should address data and report processing
procedures, project file requirements and all project-related  progress reporting
procedures and documents. The plan should also provide the format(s) to be used
to present the data, including data reduction.

     Data presentation, reduction and reporting are discussed in Sections 5.2, 5.3,
and 5.4, respectively.

5.2       Data Presentation

     RFI data should be arranged and presented in a  clear and logical format.
Tabular, graphical, and other visual displays (e.g., contaminant isopleth maps) are
essential for organizing and evaluating such data.  Tables and graphs are not only
useful for expressing results, but are also necessary for decision-making during the
investigation. For example, a display of analytical results for each sampling location
superimposed on a map of the site is helpful in identifying data gaps and  in
selecting future sampling locations. Graphs of concentrations  of individual
constituents plotted against the distance from the source can help to identify
patterns, which can be used to design further monitoring efforts.
                                    5-1

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     Various tabular and graphic methods are available for data presentation, as
illustrated in Table 5-1. Particular methods most applicable to the RFI may vary with
the type of unit, the type of data, the medium under consideration, and  other
factors. The owner or operator should propose methods in the RFI Work Plan that
best illustrate the patterns in the data.

     Often, certain types of data,  such as stratigraphy  and sampling  location
coordinates, are more effectively displayed in graphic form.  Such data may be
presented in  tabular  form  but should also be transformed  into  graphic
presentations.  For example, stratigraphy might be effectively illustrated on a two-
dimensional  (or possibly three-dimensional) cross-sectional map.  Three-
dimensional data presentation is  particularly relevant to the RFI, as three-
dimensional characterization is generally required to adequately characterize the
nature, extent, and rate of release migration.

     Sampling locations may be effectively illustrated on a topographic map, as
shown in Figure 5-1. Topographic maps and the regulatory requirements for their
preparation (40 CFR Part  270.14(b)) are also discussed in Appendix A.  Table 5-2
provides some useful data presentation methods.  In addition, many of the Case
Studies presented in Volume IV illustrate  effective data presentation techniques.
Case Study No. 6 is of particular relevance to data presentation techniques. Specific
data presentation techniques are discussed below.

5.2.1      Tables

     Tabular presentations of both  raw and sorted data are useful means of data
presentation. These are discussed below.

5.2.1.1        Listed (Raw) Data

     Simple lists of data alone are  not adequate  to illustrate  trends or patterns
resulting from  a contaminant release. However, such lists serve as a good starting
point for other presentation formats.  These  lists are also valuable for sample
validation and auditing. Therefore, such lists are highly recommended for reporting
results during the RFI. Each data record should provide the following information:
                                    5-2

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                                TABLE 5-1

                  USES OF TABLES AND GRAPHICS IN AN RFI
                             Tabular Displays


1.    Display site information and measurements
              Water table elevations
              Sampling location coordinates
              Precipitation and temperature data
              Lists of site fauna and flora

2.    Display analytical data
              List of constituents of concern and other monitoring parameters
              with associated analytical measurements
              Display sorted results (e.g., by medium, sampling date, soil type)
              Compare study and background area data
              Report input data, boundary conditions, and output values from
              mathematical modeling

                             Graphic Displays

1.    Display site features
              Layout and topography (equivalent to the required RCRA permit
              application map)
              Sampling locations and sampling grids
              Boundaries of sampling area
              Stratigraphy and water table elevations (profile, transect, or fence
              diagram)
              Potentiometric contour map of ground water
              Ground-water flow net
              Population plot and/or local residential map
              Features affecting inter-media transport

2.    Illustrate the extent of contamination
              Geographical (areal) extent of contamination
              Vertical distribution of contaminant(s)
              Contamination values, averages, or maxima at sampling locations

3.    Demonstrate patterns and trends in the data
              Change in concentration with distance from the source
              Change in concentration with time
              Display estimates of future  contaminant transport derived from
              modeling
                                   5-3

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                            Table 5-2
                 Useful Data Presentation Methods
Tables

     Unsorted (raw) data

     Sorted tables

Graphic Formats and Other Visual Displays

     Bar graphs

     Line graphs

     Area or plan Maps

     Isopleth (contour) plots

     Ground-water flow nets

     Cross-sectional plots, transects, or fence diagrams

     Three-dimensional graphs
                               5-5'

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    •    Unique sample code;

    •    Sampling location and sample type;

    •    Sampling date;

    •    Laboratory analysis identification number;

    •    Property or component measured;

    •    Result of analysis (e.g., concentration);

    •    Detection limits; and

    •    Reporting units.

    Analytical data will generally be  reduced at the laboratory before they are
reported (i.e., the owner or operator does not have to report instrument readings or
intermediate calculations,  although  this  information  should  be maintained for
ready access.if needed).  The owner or  operator should report all data to the
regulatory agency,  including suspected outliers or samples  contaminated due to
improper collection, preservation, or storage procedures.  The rejected data should
be marked as such in the data tables, and explanations of rejected data should be
presented in footnotes.

    In addition to analytical data, the  owner or operator may be  required to
provide sampling logs for all samples obtained during the investigation.  Sampling
logs are records of procedures used in  taking environmental samples,  and of
conditions prevailing at the site during sampling.  Information in the log should
include:

    •    Name and address of sampler;

    •    Purpose of sampling;

    •    Date and  time of sampling;
                                   5-6

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     •   Sample type (e.g., soil) and suspected contaminants;

     •   Sampling location, description, and grid coordinates (including photos);

     •   Sampling method, sample containers, and preservation (if any);

     •   Sample weight or volume;

     •   Number of samples taken;

     •   Sample identification number(s);

     •   Amount purged (for ground water);

     •   Field observations;

     •   Field measurements made (e.g., pH, temperature);

     •   Weather conditions; and

     •   Name and signature of person responsible for observation.

     The owner or operator  should  also describe any unusual  conditions
encountered during sampling (e.g., difficulties with the sampling equipment, post-
sampling contamination, or loss of samples).

5.2.1.2        Sorted Summary Tables

     Presentation of results grouped according to data categories is one of the
simplest formats used to display trends or patterns in data. Examples of categories
of data include medium tested, sampling date, sampling location, and constituent
or property measured.  Table 5-3  shows an example of a sorted table; data are
sorted by medium (ground water), sampling date, and constituent measured.
                                   5-7

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                             TABLE 5-3
                           SORTED DATA
h/3/82
12/12/82
                                     Concentration
       T  Sample    I Methylene
  Date    Identification   chloride
       I   Number   i       _
/IW-32-1/3A
/»W-32-2/12A
 ^ * — _
 4/24/82 JMW-32-4/24A

 NA- Not analyzed.
                         Acetone
                                   Trichloroethylene
                                                              Benzene
                                        5-8

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     In Table 5-4, the data are sorted by medium, location, depth, and constituent
analyzed.  Inclusion of the sample identification number allows the reader to cross-
reference the data and look up any information not listed in the table.

     Preparation of data summary tables can be simplified by use of a computer
spreadsheet program. These programs can perform sorting operations, perform
simple calculations with the data, and display results in a number of tabular and
graphical formats.

5.2.2      Graphic Presentation of Data

     The graphic methods of data presentation will often illustrate trends and
patterns better than tables.  Some graphic formats useful for environmental data
include bar graphs, line graphs, areal  maps, and isopleth-plots.  These graphic
methods of data presentation are discussed below.

5.2.2.1        Bar Graphs and Line Graphs

     Bar graphs and line graphs may be used to display  changes in contaminant
concentrations with time, distance from a source, or other variables.  For example,
Figure 5-2 compares two methods of displaying changes in concentrations over
distance.  Bar graphs are generally preferable to line graphs in instances where
there is not enough information to assume continuity between data points.
However, line graphs generally can display more information in a single graph.

     Attention to the following principles of graphing should provide clear and
effective line and bar graphs:

     •    Do not crowd data onto a graph. Plots with more than three or four lines
          or bar subdivisions become confusing.  Different symbols or textures
          should be used to distinguish each line or bar;

    •    Choose the scale of the x and y axes so that data are spread out over the
         full range of the graph.  If one or two data points are far outside the
          range of the rest of the data, a broken line or bar may be used to indicate
                                   5-9

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                             TABLE 5-4
               SOIL ANALYSES: SAMPLING DATE 4/26/85
Sample Identification, Location, and Depth
Sample ID
 Number
  lB-7
   SB-2
   S8-3
   SB-4
   SB-5
   SB-6
 Location

N of lagoon
N of lagoon
N of lagoon
 SE corner
 SEcorner
 SE corner
 Depth

surface
6 inches
18 inches
 surface
6 inches
18 inches
                                 Concentration (mg/kg)
Lead
 240
  40
  15
 360
 170
  22
Arsenic
   "sT
   15
   15
   84
   29
Chromium

   1,200
    220
     36
   5,300
    430
     47
                                  5-10

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               METALS IN RIVER SEDIMENTS:  LINE GRAPH
              i            2            S
               DISTANCE  PROM  SOURCE (MILES)
               METALS IN RIVER SEDIMENTS: BAR GRAPH
200-
 i»0-
                OtSTlNCt ?*OM SOURCE (MILES)
        Figure 5-2. Comparison of line and bar graphs
                             5-11

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         a discontinuous scale.  If  the  data range  exceeds two  orders  of
         magnitude, the owner or operator may choose to plot the logarithms of
         the data;

     •   The x and y axes of the plot should be clearly labeled with the  parameter
         measured and the units of measurement; and

     •   The x axis  generally represents the independent variable and the y axis
         the dependent variable.

5.2.2.2        Area  or Plan Views (Maps)

     The distribution of hazardous constituents at a site may be represented  by
superimposing  contaminant concentrations over a map of the site.  Distributions
may be shown by listing individual measurements, or by contour plots of the
contaminant concentrations. Individual techniques are discussed below:

     Contamination  shown at discrete points-ln this format, no assumptions are
made concerning contamination outside  the immediate sampling area. For
example, in Figure 5-3, soil phenol concentrations are shown  by the height of the
vertical bar at each sampling site.  Soil samples indicated on this map were taken
from approximately the same depths. Note that one bar is discontinuous so as to
bring the lower values to a height that can be seen on the graph.  Other possible
representations of the same information could use symbols  of different  shapes,
sizes, or colors to represent ranges of concentration.  For example, a triangle might
represent 0 to 10 ppm; a circle 10 to 100 ppm, etc.

     Display of average concentrations-Shadinqs or textures can be used  to
represent average contamination concentrations within smaller areas at a site.
Shading represents estimated areas of similar concentration only and should not be
interpreted as implying concentration gradients between adjacent points.

     Contaminant isopleth maps-Lines of equal concentration are called isopleths.
Construction of a contaminant  isopleth map generally requires a relatively large
number of sampling  locations spaced regularly across the study area. An isopleth
map is prepared by marking the site map with the concentrations detected  at each
                                   5-12

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sampling  location.  Lines are drawn  to  connect data  points of the same
concentration, similar to contours of elevation, as shown in  Figure 5-4. Figure 5-5
demonstrates the use of an isopleth plot to show the distribution of an air release.

5.2.2.3        Isopach Maps

     A technique that is useful for displaying certain types of geological data is the
isopach map. Isopachs are contour maps in which each line represents a unit of
thickness of a geologic material (e.g., the soil layer) as shown in Figure 5-6.  This
format would be useful if, for example, oil is known to be contained within a highly
permeable sand layer of varying thickness, confined between low-permeability clay
layers. The isopach map displays thickness only  and does  not provide information
on absolute depth or slope.

5.2.2.4        Vertical Profiles or Cross-Sections

     Vertical profiles are especially useful for displaying  the  distribution  of  a
contaminant release in all media. For soil and ground water, the usual approach  is
to select several soil cores (or monitoring wells) that lie in  approximately a straight
line through the center of the contaminant release. This cross-section represents  a
transect of the site.  A diagram of the soil (or ground water)  profile should be
prepared along the length of the transect, displaying subsurface stratigraphy,
location of the waste source, and the location and depth of boreholes, as shown  in
Figure 5-7. Concentrations may  also be indicated  on  the  plot as discrete
measurements or isopleths and may be drawn as in Figure 5-8. Figure 5-9 presents a
plan view of Figure 5-7, showing the offset in cross-section.  If the sampling points
do not fall in a straight line, an alternate display called a fence diagram can be used.
Figure 5-10 shows a fence diagram of subsurface stratigraphy, which also includes
analytical data.

     To characterize  the three-dimensional  distribution  of a subsurface
contaminant release, the owner or operator will generally need  to prepare several
transects crossing the plume in different directions.
                                    5-14

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                                seal*, mtters
Figure 5-4. Isopleth
MapofSoilPCB Concentrations^)
                          5-15

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              I8OPLITH3 Aftf IN MICROQRAM3 PER CUBIC METER
Figure 5*5.   Isopleth Map of Oiphenylamine Concentrations in Ambient Air in the
            vicinity of a SWMU.
                                 5-16

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5.2.2.5        Three-Oimensiona! Data Plots

     Computer graphics packages are available from several commercial suppliers
to produce three-dimensional data  plots.  A common  use of this technique  is to
represent contaminant concentrations across the study area as a three-dimensional
surface, as shown in Figure 5-11. The information provided by this approach does
not differ greatly from that of Figure 5-4.  The primary difference  is that the
smoothing of the concentration dissimilarities between adjacent sampling locations
in Figure 5-11 makes patterns in the data easier to visualize. Precise concentrations,
however, cannot be displayed in this format because the apparent heights of the
contours change as the figure is rotated.

5.3      Data Reduction

     Data should be reported according to accepted  practices of QA and  data
validation.  All data should be  reported.  Considerations, however, include
treatment of replicate measurements, identification of outlier values, and reporting
of results determined to be below detection limits.

5.3.1     Treatment of Replicates

     Replicate measurements of  a  single sample should be averaged prior to
further data reduction. For example, Table 5-5 shows how to calculate an overall
mean when replicate analyses for a single sample have been performed. The three
"8" values are averaged before the mean is calculated.  This removes bias from the
overall mean. The number of analyses is indicated by "n".

5.3.2     Reporting of Outliers

     Any program of environmental measurement can produce numbers that lie
outside the "expected" range of values.  Because field variability of environmental
measurements can  be great, deciding whether an extreme (outlier) value  is
representative of actual contaminant levels may be difficult. Outlier values may be
the result of:

     •   A catastrophic unnatural (but real) occurrence such as a spill;
                                   5-22

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         JL-1000
Figure M
                        sional Data Plot of Soil PCB Co
ncentrations(ug/*9>
                                  5-23

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                TABLE 5-5
CALCULATION OP MEAN VALUES FOR REPLICATED
                         Data Summary
                    Sample     Concentrat.on
Sample  Concentration
                       5-24

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     •    Inconsistent sampling or analytical chemistry methodology;

     •    Errors in the transcription of data values or decimal points; and

     •    True but extreme concentration measurements.

     The owner or operator should attempt to correct outlying values if the cause
of the problem can be documented. The data should be corrected, for example, if
outliers are caused by incorrect transcription and the correct values can be obtained
and documented from valid records. Also, if a catastrophic event or a problem in
methodology occurred that can be documented, data values should be reported
with clear reference. Documentation and validation of the cause of outliers must
accompany any attempt to correct or delete data values, because true but extreme
values must not be altered.  Statistical methods for identifying outliers require that
the analytical  laboratory have an ongoing  program of QA, and that sufficient
replicate samples be analyzed to account for field variability.

     Outlier values  should  not be  omitted  from the raw data reported to the
regulatory agency; however, these values should be identified within the summary
tables.

5.3.3      Reporting of Values Below Detection Limits

     Analytical values determined to be at or below the detection limit should be
reported numerically (e.g.,  <0.1 mg/l).  The data presentation  procedures should
cite analytical methods used including appropriate detection limits.

5.4       Reporting

     As indicated in Section 3.7,  the  owner  or  operator should  respond to
emergency situations and identify to the regulatory agency priority situations that
may require interim corrective measures.  Such reporting should be done
immediately.  In addition, results of various activities conducted during the RFI
should be reported to the regulatory agency, as required in the compliance order or
by the permit conditions.
                                   5-25

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     Various reports may be required. These may include interim, draft, and final
reports.  In addition, periodic progress reports (e.g., bimonthly) may also be
required. Progress reports should generally include the following information:

     •    A description and estimate of the percentage of the RFI completed;

     •    Summaries of all findings;

     •    Summaries and  rationale for all changes made in the RFI Work Plan
          during the reporting period;

     •    Summaries of all contacts with representatives of the local community,
          public  interest  groups, or government representatives during  the
          reporting period;

     •    Summaries of all problems or potential problems encountered during the
          reporting period;

     •    Actions being taken to rectify problems;

     •    Changes in personnel during the reporting period;

     •    Projected work for the next reporting period; and

     •    Copies of daily reports, inspection reports, laboratory/monitoring data,
          etc.

     Reports, including interim, progress, draft,  and final reports may also be
required for specific activities that may be performed during an RFI.  Examples of
specific reports or components that may be required include:

     •    RFI Work Plan;

     •    Description of Current Situation;

     •    Geophysical Techniques;
                                   5-26

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     •    Waste and Unit Characterization;

     •    Environmental Setting Characterization;

     •    Selection of Monitoring Constituents/Indicator Parameters;

     •    Results of "Phases" of the Investigation;

     •    QA7QC results;

     •    Interim Corrective Measures; and

     •    Identification of Potential Receptors.

     In  addition, a draft and final RFI report that incorporates the results of all
previous reports will generally be required. This report should be comprehensive
and should be sufficiently detailed to allow decisions to be made by the regulatory
agency regarding the need for interim corrective measures and/or a CMS.  It should
be noted that these decisions may also be made by the regulatory  agency on the
basis of results of progress reports and/or other reports as described above.
                                    5-27

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                                 SECTION 6

                            HEALTH AND SAFETY
6.1       Overview

      Protecting the health and safety of the investigative team, as well as of the
general public, is a major concern during ha2ardous waste RFIs. Hazards to which
investigators may be exposed include known and suspected chemical substances,
heat stress, physical stress, biological agents, equipment-related injuries, fire, and
explosion.  Many of these hazards are encountered in any type of field study, but
exposure to chemical hazards  is a major concern for the  investigative team at
hazardous waste facilities.

      In addition to the protection of team members, the public's health and safety
should also be considered. RFIs may attract the attention and presence of the news
media, public  officials, and the general public.  Not  only  is the safety of these
observers a concern, but their actions should not hind  v the operations and safety
of the investigative team.  Other public  health concerns include  risks  to  the
surrounding community from unanticipated chemical  releases,  and events such as
fires and explosions.

      The facility owner or operator should develop and update as necessary health
and safety plans and procedures to address the needs of the RFI.  The health and
safety plan should, in particular, establish requirements for protecting the health
and safety  of  the investigative team, facility workers, and the general public
throughout the investigation.

     Health and safety plans should be reviewed and approved by qualified  (via
education and work experience) safety and health professionals. While professional
certifications such as Certified Industrial  Hygienists or Certified Safety  Professionals
are highly regarded, such certifications are not required under the OSHA standard
for plan  review/approval, nor do they inherently guarantee proficiency in
hazardous materials operations.  In addition, health  and safety plans should be
                                    6-1

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discussed thoroughly with the investigative team prior to initiating fieid activities.
Other appropriate parties (e.g., local emergency services) should also be involved, as
necessary.

     Compliance with health and safety regulatory requirements is the ultimate
responsibility of the employer, who, for purposes of the RFI, is the facility owner or
operator.  Development and implementation of health and safety procedures is
therefore the responsibility of the owner or operator.  Although these procedures
may be presented as part of the RFI Work Plan and reviewed by the regulatory
agency, ultimate responsibility  and liability rest with the owner or operator.
Section 6.2 presents general health and safety regulations and guidance that should
be reviewed prior to developing  health and safety procedures, Section 6.3 outlines
basic elements of health and safety procedures which should be addressed, and
Section 6.4 reviews application of zones of operation or work zones.

6.2      Applicable Health and  Safety Regulations and Guidance

      On December 19, 1986, the Occupational Safety and Health Administration
(OSHA) issued, in the Federal Register (29 CFR 1910.120), an interim  final rule on
hazardous  waste site operations  and emergency response,  which specifically
requires certain minimum standards concerning health and  safety for anyone
performing activities at CERCLA sites, RCRA sites, emergency response operations,
sites designated for remediation  by a state or local  agency, or any other operation
where employees' operations involve dealing with hazardous waste. The following
discussion provides details on the major requirements of the interim final rule.

Development and implementation of a safety and health program:

     The development and implementation of a formal, written safety and health
program has long been recognized as a foundation for successful occupational risk
minimization.   In recent years, this recognition has been receiving increased
emphasis from the Occupational Safety and Health Administration (OSHA).  For
example, as stated in the July 15,1988 Federal Register (53 FR 26791):

     . .  . OSHA has  become increasingly convinced of the  relationship  between
     superior management of safety and health programs - which address all safety
                                   6-2

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     and health hazards, whether or not covered by OSHA standards - and low
     incidence and severity of employee injuries.

     As a result, OSHA has  intensified its focus on management practices in its
evaluation of workplaces. One primary area of this focus has been on documented
safety and health programs. This increased emphasis is evidenced in several other
OSHA standards that have been promulgated (e.g., Respiratory Protection - 29 CFR
1910.134, Occupational Noise Exposure - 29 CFR 1910.95, Hazard Communication -
29 CFR 1910.1200, and Subpart C of the Construction Industry Standards - 29 CFR
1926).

     In addition to these individual subject area requirements, OSHA has released
for comment and information a proposed rule  on General Safety and  Health
Programs (previously-referenced Federal  Register - 53 FR 26791). In that proposal,
suggested guidelines for establishing and  implementing new safety and  health
programs - or evaluating/modifying existing programs - are provided. The proposed
rule advises  employers to "institute and maintain...a program which provides
policies, procedures and practices that are adequate to recognize and protect their
employees from occupational safety and health hazards."

     Specific elements of the program proposed by OSHA are addressed under four
subject headings.  These headings include management commitment, worksite
analysis, hazard prevention and control, and safety and health training.

     It is of no small consequence that management commitment is the first issue
addressed in this proposed rule.  A strong commitment from top management
representatives is critical to the success of any program.  Additionally, this
commitment needs to be highly visible to  employees.  Clear program goals and
objectives need to be specified,  as well as identification  and assignation of
appropriate  levels of authority, responsibility and accountability. Finally,  at least
annual program reviews and evaluations are necessary to identify the effectiveness
of the program, and incorporate any necessary program modifications.

     The second program area recommended for inclusion is worksite analysis. The
intent of this part of the program is  to identify methods and practices to be utilized
for recognizing potential hazards. Examples of methods that can be used to achieve
                                   6-3

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these objectives include:  periodic, comprehensive worksite surveys; analysis of new
processes, materials and equipment; and  performance of routine  job or  phase
hazard analyses.  Other recommended methods include the conduct of regular site
inspections, and accident (or near-accident) investigations.

     The third program area  addresses hazard prevention and  control.  These
efforts should include identifying appropriate engineering, administrative, and/or
personnel protective equipment and hazard  controls.  Additionally, emergency
preparedness and a medical program should be elements of this portion of the
overall program.

     The final topic identified in the proposed rule addresses safety and health
training.  Employee education and training  needs should be provided so that
employees are fully aware and capable  of  handling  potential hazards in the
performance of their work. Additionally, safety and health training of supervisors
and managers needs to be addressed and performed to ensure that they are aware
of their responsibilities in regard to health and safety.

     To summarize, a written, comprehensive health and safety program, that has
visible top-management support, is  an important element of a safe and healthful
work environment. However, the  written program itself must be effectively
implemented, periodically evaluated -  and modified as necessary, in order to
achieve its objectives.

Performance of site characterization  and  analysis:

     In addition to the general items of worksite analysis identified above, specific
requirements for this type of analysis are presented under OSHA regulation 29 CFR
1910.120. Performance of site characterization and analysis is specifically addressed
in paragraph (c) of this regulation.

     A site characterization and analysis addressing each site task and operation
planned to be performed needs to be conducted. This effort generally proceeds in
three phases.  Initially (prior to any actual site entry),  a data-gathering phase is
performed to collect any relevant information that may identify potential site
hazards.  This activity may include such items as obtaining shipping/disposal
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manifests or other such  records, including newspaper/media reports, and
interviewing persons with potential knowledge of past operations (e.g., previous
employees, nearby residents). This initial phase may also consist of the conduct of
an  offsite reconnaissance  (e.g., around the  perimeter of  the site), and
characterization based on all of the collected data. The second phase of this process
is the conduct of an onsite survey.  Finally, the third phase involves site entry, with a
continuance of monitoring efforts to  provide current information for evaluating
potential site hazards.

     In view of this phased approach, it is clearly intended that site characterization
and analysis is a continuous process.   It is initiated prior to any actual onsite
involvement, and continues throughout the performance of onsite activities.

Development and implementation of a site control program:

     Site control  elements need  to be established to minimize potential for
employee contact with contamination, and the transfer of contaminants into non-
contaminated areas.  These program elements need to be clearly defined in the
employer's site safety  and  health  plan.  As stated in the  preamble of the rule
establishing 29 CFR  1910.120,  (December  19,  1986 Federal Register), the
establishment of a site control  program should be performed  "in the planning
stages of a project and modified based on new information and site assessments
developed during site characterization."  The preamble further states that the
"appropriate sequence for implementing these measures should be determined on
a site-specific basis."

     The primary intent of this requirement is that the site control  program must be
addressed on a site-specific basis.   However, employers should develop a general
program that identifies minimum  performance requirements in order to establish
overall uniformity for all projects.   For each specific project, the OSHA regulations
specify that the site control program include - at a minimum - the following:

     •    A map of the site;

     •    Designation of site work zones;
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     •   The practice of using what the regulation refers to as a "buddy system"
         (defined as a "system of organizing employees into work groups m such
         a manner that each employee of the group is designated to observe the
         activities of at least one other employee in the work group. The purpose
         of the buddy system  is to provide quick assistance to  those other
         employees in the event of an emergency.");

     •   Establishment and maintenance of site communications;

     •   Establishment and implementation of site standard operating
         procedures or safe work practices; and

     •   Identifying the nearest medical facility that would be contacted in the
         event of a site incident resulting in a need for such services.

Compliance with employee training requirements (specified in paragraph (e)_pf the
standard) and the development and implementation of  an  employee training
program:

     An employee training program must be developed and implemented, meeting
(at a minimum) the training  requirements specified  in  paragraph (e) of the
hazardous waste regulation. The program must include provisions for both initial
and refresher training of employees on matters of health and safety. All involved
employees must receive effective training prior to performing any operations that
could result in their exposure to potential safety and health hazards.

     The training  requirements specified in this regulation are categorized into
several subject areas. While the majority of the requirements address CERCLA
(SuperfundVrelated operations, RCRA-related  projects and emergency response
operations, general training requirements are also specified. The intention of this
categorization is to recognize that varying degrees of risk potential exit, thereby
requiring different types of health and safety training.

     Additionally, for CERCLA-type operations, the program must be further
subdivided to address health and safety training program elements for employees
and onsite management and supervisors. All individuals must receive introductory
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 training (40 hours in duration)  prior to  their initial assignment.  This is to  be
 supplemented by 8-hours of annual refresher training, and the conduct  of site-
 specific training for each assignment. Onsite managers and supervisors who will be
 assigned responsibility for direct, onsite supervision, must receive an additional 8-
 hours of specialized training for operations management upon job assignment.

     Employees involved in normal RCRA operations are required to receive a lesser
 amount of initial training  (24-hours) and 8-hours of annual  refresher training.
 These requirements are applicable for employees who will be involved in hazardous
 waste operations involving storage, disposal  and treatment.  However, major
 corrective actions under RCRA would need to be addressed in a manner similar to
 the previously - identified CERCLA training requirements.

     The final category specifying  employee training requirements addresses
 individuals who participate in  (offsite) emergency response operations (e.g.,
 HAZMAP team personnel). Any employees involved in such operations are required
 to receive at least 24 hours of training annually.

     The development and implementation of an employee  training program must
 be initiated by first identifying  which of the requirements are applicable, and
 identifying the employees who  need to  be  included. The overall program also
 needs to address other types of required employee health and safety training
 applicable to the work site(s) and job tasks.  Examples of other types of required
 training may include:

     •    Hazard Communication Training (29 CFR 1910.1200);

     •    Hearing Conservation Training (29 CFR 1910.95);

     •    Respiratory Protection Training (29 CFR 1910.134); and

     •    Others-based on types of equipment, processes, etc.

     After all training needs have been identified and the program has been
developed and implemented,  it  must be periodically reviewed and evaluated to
determine its effectiveness, with appropriate modifications made where necessary.
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Finally, appropriate records of employee training must be maintained to satisfy
applicable recordkeeping requirements.

Development and implementation of a medical surveillance programi

     A comprehensive  medical surveillance program must be established  for
employees engaged in hazardous waste operations. Employees who have been, or
are expected to be, exposed to hazardous substances or health hazards must  be
participants in such a program. Therefore, one of the first  tasks in program
development should be to define how many (and which) employees need to  be
covered.

     A second critical element in the development of the program is the selection
of a physician (or physicians) who will be utilized to perform the examinations. The
selected physician must be licensed, should be knowledgeable in occupational
medicine, and familiar with the nature of the work tasks that the employees that
he/she will be examining will be performing.

     The program needs to provide examinations to employees prior to their first
hazardous materials job assignment, at least once every twelve months following
the initial examination, upon job termination or reassignment, as soon as possible
for any employee demonstrating  symptoms of overexposure to hazardous
substances, and at more frequent times - as determined to  be necessary by the
examining physician.
            *

     The extent of the examination is at the discretion of the examining physician.
However, in order for the physician to appropriately determine the necessary
parameters, protocols, tests, etc., he/she must be made very familiar with the nature
of the patient's job duties. Therefore, the regulation requires that the physician be
provided with a copy of the standard-in its entirety, a description of the employee's
duties relative to  potential  exposures, a description of known  or anticipated
exposure levels that have been - or may  be • encountered  by the employee, a
description of personal protective equipment that the employee has used  or may
use, and the employee's previous medical history.
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     The established medical  program should be developed to address medical
 concerns specified by other regulations as well as hazardous waste operations (e.g.,
 respiratory protection usage, audiometry, asbestos exposures, and other applicable
 regulations).  Therefore, it should have a mechanism incorporated to  provide for
 periodic program review and evaluation to determine effectiveness, and the need
 for modification as deemed necessary. Finally, medical surveillance recordkeeping
 must be performed and maintained in accordance with OSHA 29 CFR 1910.20.

 Incorporation  of engineering controls,  administrative  controls, and the
 development and implementation of a personal protective equipment program:

     To protect employees from potential hazards that may be encountered  in
 hazardous materials operations (e.g., chemical, physical, biological hazards),
 employers are required to implement appropriate control efforts.  In order  of
 preference, such approaches are to employ engineering and administrative controls
 where feasible, and (as a last resort), personal protective equipment.  However,
 these control efforts are not mutually-exclusive.  The regulation provides for the
 employer to utilize appropriate  combinations of these three types of controls in
 protecting his/her employees.  However, where items of  personal  protective
 equipment (PPE) are used, a PPE program must be developed and implemented.

     In the developmental stages of the program, the employer must define the
 types of PPE that will or may be necessary for employee usage.  Examples include
 respiratory protection (with considerations given to the types necessary - e.g., air-
 supplied vs air-purifying, half-face masks, full facemasks, etc.), hearing  protection,
 head protection, foot protection, dermal protection, eye/face protection, etc.  Many
 of these types of PPE are regulated under specific OSHA standards. Therefore, upon
 identification of the types of PPE to be used, the regulations must be consulted in
 developing and implementing the  program to ensure overall compliance and
 program adequacy.

     The program must also provide for proper selection of equipment on the basis
of the  known or suspected hazards to be encountered, proper maintenance,
cleaning, servicing, storage  of equipment, and, proper training of employees in the
correct use and recognition of the limitations of the selected equipment. As with
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other programs, provisions for review and evaluation for  effectiveness must be
incorporated, enabling necessary modifications to be made.

Development and implementation of an air monitoring program:

     The establishment of an air monitoring program is essential.  The purpose of
the program is to gain accurate inforr   :.ion on employee  exposures in order to
implement the correct PPE, engineering controls, and work practices.  Airborne
contaminants can present a significant threat to employee safety and health. Thus,
identification and quantification of these contaminants through air monitoring is
an essential component of a safety and health program.

     The intent of this  requirement is that  the air monitoring program be
addressed on a site-specific basis. After the site characterization and analysis phase
has been completed, personnel should be  cognizant of possible contaminants on
each specific site.  With this information, proper air sampling and analytical
methods can be chosen.

     Reliable measurements of airborne  contaminants are useful in  selecting
proper personal protective  equipment, determining whether engineering controls
can achieve  permissible  exposure limits and which controls to use.  Also, this
information is used in delineating areas where protection is needed and in assessing
potential health effects of exposure. Knowledge of potential health effects will
further aid in determining the need for specific medical monitoring.

     In view of this approach, air monitoring is a continuous process. It should be
initiated prior to any actual onsite involvement, and should continue throughout
the performance of onsite activities.

     The developed program needs to contain elements identifying the types of
monitoring equipment available for employee use, proper selection, maintenance
and calibration procedures, employee training, and provisions for equipment
cleaning and storage.
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Development and implementation of an employee informational program:

     The Occupational Safety and Health Administration is requiring under 29 CFR
1910.120, that employers, as part of their safety and health program, develop and
implement a site-specific health and safety plan (HASP) for each hazardous waste
site operation.

     The site health and safety plan must be developed by the employer, utilizing
the other parts of the organizational plan and the employer's safety and health
program. The HASP must address the anticipated health and safety hazards
associated with each work operation  or task, and the means to eliminate the
hazards or to effectively control them to prevent injury or illness.

     The minimum requirements that a HASP must include is the following:

     •   The names of those responsible for assuring that safe and healthful
         practices and procedures are followed throughout all work operations;

     •   Risk analysis or system* analysis for specific work tasks or operations on
         the site;

     •   Employee training assignments both offsite and on-the-job training
         onsite;

     •   A list of personal protective equipment needed for each work task and
         operation onsite;

     •   The employers medical surveillance program for the site;

     •   The methods for identification and characterization of safety and health
         hazards on the site including the air monitoring procedures that will be
         performed throughout the work onsite;

     •   Site control measures including those for establishing work zones on the
         site;
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     •   The necessary decontamination procedures which are matched to the
         kinds of anticipated contaminants to be cleaned from personnel and
         equipment;

     •   The general safe work practices to be adhered to by personnel onsite;

     •   The  contingency plan for emergencies and confined  space entry
         procedures;

     •   Site-specific training and site inspections and procedures to be followed
         in changing or modifying the plan; and

     •   All emergency numbers of local authorities (e.g., ambulance, police), as
         well as directions to the nearest hospital and a map to the hospital.

     As a separate section, an emergency response plan must also be included. This
plan is discussed in greater detail in a latter section of this subsection of the
guidance document.

Adherence to proper procedures for handling drums and containers:

     The handling of drums and  containers at hazardous waste sites poses one of
the greatest dangers to hazardous waste site employees.   Hazards include
detonation, fire, explosion, vapor generation, and  physical injury resulting from
moving heavy containers by hand and working in the proximity of stacked drums,
heavy  equipment and  deteriorated drums.   The employer must implement
procedures and provide proper work practices in order to minimize the risks to site
personnel.

     The appropriate procedures for  handling drums depend primarily upon the
drum contents. Thus, prior to handling, drums should be visually inspected to gain
as much information as possible about their contents.  The inspection crew should
look for symbols, words, or other marks on the drum indicating that its contents are
hazardous, e.g., radioactive, explosive, corrosive, toxic and/or flammable. The crew
should also look for signs of deterioration (such as rust, corrosion, and leaks), and
whether the drum is under pressure.
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     Conditions in  the immediate vicinity  of the drums may  also  provide
information about drum contents and their associated hazards.  Monitoring should
be conducted in the area around the drums using instruments such as a radiation
survey meter, organic vapor monitors, and combustible gas indicators.

     As a precautionary measure,  personnel should assume that unlabeled drums
contain hazardous materials until their  contents are characterized.  Also, they
should bear in mind that drums are frequently  mislabeled - particularly drums that
are reused.

     Employers must ensure that any personnel involved with handling drums are
aware of all pertinent regulations. OSHA regulations (29 CFR Parts 1910 and 1926)
include general requirements and  standards for storing, containing, and handling
chemicals and containers, and for maintaining equipment used for handling drums
and containers.  EPA regulations (40 CFR  Part 265) stipulate requirements for types
of containers, maintenance of containers, and design and maintenance of storage
areas. DOT regulations (49 CFR Parts 171  through 178) also stipulate requirements
for containers and procedures for shipment of hazardous wastes.

Development and implementation of a decontamination procedure:

     Decontamination procedures must be developed on a site- and/or task-specific
basis, and be implemented prior to performing any site entrance activities.  These
methods must be specifically matched to  the hazardous substance(s) of concern at
the site in order to be effective.  Procedures for both personnel and equipment
decontamination must be developed and implemented in order to minimize
potential for:

     •   Employee exposure to substances of concern;

     •   Transferring contaminants offsite or to previously non-contaminated
         areas; and

     •   Exposing the environment and/or offsite receptors to hazard potential.
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     The standard requires that upon implementation of these procedures, the site
safety and health officer must conduct.monitoring for effectiveness on a continuous
basis.

     Decontamination procedures must be supplemented by incorporation of and
adherence to standard operating  procedures that  are developed to minimize
potential for personnel and equipment to come into contact with  contaminated
substances and surfaces. Additionally, the developed decontamination procedures
must incorporate provisions for controlling, collecting, and disposing generated
wastes in a proper manner. These materials will typically include items of personal
protective equipment, decontamination (wash  and rinse) fluids, as well as materials
generated during site activities (e.g., drill cuttings, pumped monitoring well fluids,
etc.).

Development and implementation of an Emergency Response Plani

     Prior to any onsite work, the employer must develop and implement an
emergency response plan that is site-specific, and all involved employees must be
made aware of the provisions of this plan. This is to be incorporated as a separate
section of the  site safety and health plan, and it  must include provisions for:
recognition of emergency situations;  methods for  alerting onsite personnel of
emergency situations; site  evacuation procedures; provisions for emergency
medical treatment; lines of authority in emergency situations; emergency
decontamination procedures; and methods for evaluating the effectiveness of the
emergency response plan.

     The regulations require that the role of individual employee's in emergency
situations be reflected in the plan.  Two categories of employee activities are also
discussed.  One is from the standpoint of onsite emergency response,  while the
other addresses offsite response activities. In  addition, the greater the roles and
responsibilities of the employee in a response situation, and the greater the risk
potential that  may be presented, the more  detailed  and comprehensive the
emergency response plan will need to be.  It is also common that both on- and
offsite response efforts may be necessary, depending on the nature and extent of
the specific situation. Therefore, the  emergency response  plan needs to address
both onsite and offsite activities.
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    The emergency response  plan  must include provisions for the  following
elements, at a minimum:

    •   Pre-emergency planning;

    •   Personnel roles, lines of authority, training, and communication;

    •   Emergency recognition and prevention;

    •   Safe distances and places of refuge;

    •   Site security and control;

    •   Evacuation routes and procedures;

    •   Decontamination;

    •   Emergency medical treatment and first aid;

    •   Emergency alerting and response procedures;

    •   Critique of response and follow-up;

    •   Personal protective equipment and emergency equipment;

    •   Establishment of an Incident Command System;

    •   Procedures for incident reporting to appropriate local,  state, and/or
         Federal agencies;

    •   Regular rehearsal and employee training of the elements of the plan;
         and

    •   Periodic   plan   review,  with   necessary  modifications,   for  plan
         effectiveness.

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Compliance  with  the requirements for both  illumination,  and  sanitation  at
temporary workplaces:

     Minimum requirements for illumination and  sanitation  (potable and  non-
potable water  supplies  and  toilet  facilities)  are  specified  in the  regulation,
incorporating the requirements of Subpart C of the Construction Industry standards
(29 CFR Part 1926).

     Illumination requirements are specified by site areas or operations. Generally,
lower levels of  illumination are necessary in areas where employee presence is
incidental or nonfrequent, and where activities involve low risk potential. Greater
amounts of illumination are required in general site  areas, indoor site facilities, and
in personnel facilities. The highest illumination intensity requirements are specified
for areas including first aid stations, infirmaries, and offices.

     Sanitation  requirements address procedures for providing, identifying, and
dispensing  potable water and nonpotable water.   Additionally, if appropriate,
provisions must be made  for toilet facilities,  food handling, sleeping quarters, and
washing facilities.

Compliance with the requirements specified under  paragraph  (o) of the standard
for  certain  operations  conducted  under RCRA.  including developing  and
implementing a hazard  communication program (meeting the requirements of
OSHA29CFR 1910.1200):

     The OSHA  regulation contains less extensive requirements for normal  (e.g.,
non-corrective action type) RCRA operations (vs CERCLA operations)  in recognition
that, by comparison, hazards should  be "better  controlled and more routine and
stable" (51 FR 45661,  December 9,  1986).  Employers conducting operations on
RCRA facilities  must  develop and implement the following  programs and
procedures:

     •    Hazard Communication Program in conformance with the requirements
         of OSHA 29 CFR 1910.120;
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     •    A medical surveillance program;

     •    A health and safety program;

     •    Decontamination procedures; and

     •    An employee training program.

     Following is a list  of other regulations that should be considered when
developing health and safety programs and procedures:
              Citation

              29 CFR 1910.134

              29 CFR 1910.95
              29 CFR 1903
              29 CFR 1904

              29 CFR 1926

              29 CFR 1960
              29 CFR 1975

              29 CFR 1977
                   Title
Respiratory Protection

Hearing Conservation
Inspections, Citations, and Proposed Penalties
Recording and Reporting  of Occupational
Injuries and Illnesses
Safety    and   Health   Regulations   for
Construction
Federal Employee Safety and Health Programs
Coverage   of   Employers   Under   the
Occupational Safety and Health Act
Regulations   on  Discrimination  Against
Employees  Exercising   Rights   Under  the
Occupational Safety and Health Act
      Other Federal and State regulations may also address the health and safety of
the investigative  team and the public.  Department of Transportation (DOT)
regulations (49 CFR 171-178),  for  example, specify containers,  labeling,  and
transportation restrictions for hazardous materials. These regulations cover the
transport of compressed-air cylinders, certain instruments, solvents, and samples.
RCRA regulations (40 CFR 260-265) may apply to the storage, treatment, and
disposal of investigation-derived materials, including disposable clothing,  used
respirator cartridges and canisters, and spent decontamination solutions.
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      Individual states may have occupational safety and health regulations more
stringent than OSHA's. These should be consulted to determine their applicability
and to ensure compliance. In addition, several guidance manuals exist that may be
helpful in establishing health and safety procedures. These are listed below:

     •   Ford, P. J. and Turina, P. T.  1985. Characterization of Hazardous Waste
         Sites-A Methods Manual:   Volume l--Site Investigations.  EPA- 600/4-
         84/075. NTISPB 85-215960. Washington, D.C. 20460.

     •   U.S. EPA. 1984. Standard Operating Safety Guides. Office  of Emergency
         and Remedial Response. Washington, D.C.  20460.

     •   U.S.  EPA.    1985.   Basic  Field  Activities  Safety Training.   Office of
         Emergency and Remedial Response.  Washington, D.C. 20460.

     •   NIOSH/OSHA/USCG/EPA.    1985.   Occupational  Safety  and  Health
         Guidance  Manual for Hazardous Waste Site Activities. NIOSH 85-115.
         GPO No.017-003-00419-6.

     •   Levine, S.P. and W.F. Martin. 1985. Protecting  Personnel  at Hazardous
         Waste Sites. Butterworth Publishers.

     •   U.S.  EPA.  1985. Guidance  on  Remedial  Investigations Under CERCLA.
         Office of  Emergency and  Remedial  Response.  NTIS PB  85-238616.
         Washington, D.C. 20460.

     •   U.S. EPA. 1986. Occupational Health and Safety Manual. EPA 1440.

     •   U.S.  EPA. Order 1440.2 - Health and Safety Requirements for Employees
         Engaged in Field Activities.

     •   U.S. EPA. Order 1440.3-Respiratory Protection.

       Professional recommendations and standards have also been offered by
organizations  such  as the  American Conference of Governmental Industrial
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Hygienists, the ASTM, the American National Standards Institute, and the National
Fire Protection Association.

6.3       Elements of a Health and Safety Plan

     RFI health and safety plans should address the following:

     •    Names of key personnel and alternates responsible for site safety and
         health, and the appointment of a site safety officer;

     •    A safety and health risk analysis for each site task and operation;

     •    Employee training assignments;

     •    Personal protective equipment (PPE) to be used by employees for each of
         the site tasks and operations being conducted;

     •    Medical surveillance requirements;

     •    Frequency  and types of air monitoring, personnel  monitoring, and
         environmental sampling techniques and instrumentation to be used -
         also,  methods of  maintenance and calibration  of monitoring and
         sampling equipment to be used;

     •    Site control measures;

     •    Decontamination procedures;

     •    Site standard operating procedures;

     •    Confined space entry  procedures; and

     •    A Contingency Plan addressing site emergency action procedures.
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6.4      Use of Work Zones

       Although this  section of the RFI Guidance is intended to be only an
introduction to the health and safety aspects of hazardous waste site investigations,
the establishment of zones of operation or work zones deserves some attention. It
should be recognized, however, that the health and safety aspects described below
may not apply to all sites.

      Hazardous waste sites should be controlled to reduce the possibility of (1)
exposure to any contaminants present, and (2) transport of contaminants offsite by
personnel and equipment.  One recommended method to prevent or reduce the
possibility of the transfer of contaminants offsite, and  to maintain control at the
site, is to establish work zones, or areas on the site  where prescribed operations
occur.  It is also important to control access points (i.e., entrances or exists) for each
designated work zone. The use of a three zone system might include:

    •   Zonel:   Exclusion Zone

    •   Zone 2:   Contamination Reduction Zone

    •   Zone 3:   SupportZone

        Zone  1, the  Exclusion Zone, would  include  all areas onsite  where
contamination is known or  suspected to be  present.  The  boundaries can be
established  based on results of previous investigations,  visual observations, facility
records,  or  similar information.   Appropriate  levels  of personal  protective
equipment  (PPE) in this zone are based  on  the types and concentrations of
contaminants known or suspected to be  present, and  other hazards that may be
present. In addition, only specifically authorized personnel should be allowed into
this zone. Once the boundaries of Zone 1 have been determined, they should be
physically secured and defined by barriers such as fences or barricades.

      Zone 2, the Contamination  Reduction Zone, would  be  set up to provide a
buffer to separate  contaminated areas from non-contaminated areas, and  may
actually surround Zone 1.  Decontamination stations  would generally be set up
between Zone 1 and Zone 2, or within Zone 2.  These stations would serve as areas
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for decontamination of both personnel and equipment. Some level of PPE may also
be required in this zone, as some level of contamination or other hazard may be
present. Access into Zone 2 from the Support Zone (Zone 3), is also controlled; only
authorized personnel should be allowed access. Any worker entering Zone 2 should
also be wearing the appropriate PPE.

      The Support Zone, Zone 3, would  be located  in a clean or uncontaminated
area, and would be directly outside of Zone 2. The support zone may have several
functions, including use as a command post and first aid station, and would serve to
house equipment sheds or trailers, mobile laboratory facilities, training and briefing
areas, etc.
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                                 SECTION 7

                    WASTE AND UNIT CHARACTERIZATION


7.1       Objectives and Purposes of Waste and Unit Characterization

     Because the waste managed or contained in a unit provides the source for a
contaminant release, detailed knowledge of the source characteristics is valuable in
identifying monitoring constituents and indicator parameters, possible release
pathways, a conceptual model of the release, monitoring procedures, and also in
linking releases to particular units. Waste and unit characteristics will also provide
information for determining release rates  and other  release characteristics (e.g.,
continuous as opposed to intermittent).  Waste and  unit information is also
important for determining the nature and scope of any corrective measures which
may be applied.

     Without adequate  waste characterization,  it is difficult to ensure that all
constituents of concern will be monitored during the release investigation, unless
all  possible constituents are monitored.   The extent of adequate waste
characterization, however, will vary depending upon the nature of the facility and
types of units studied. For example, waste characterization for a unit dedicated to a
single steady-state process will be much less extensive than for a unit at an offsite
facility that manages a variety of wastes that vary over time.

      As indicated above, waste characterization may also be helpful in identifying
constituents to discriminate among releases from different units. In some situations
(e.g., more than one unit in a waste management area), it  may be important to
identify which unit is responsible for the release of concern. Accurate identification
of the unit from which the  release is occurring may hinge on  the ability to link the
released contaminants to the waste managed in a particular unit (or, in some cases,
to "decouple" the contamination from a particular unit).

      Sufficient characterization of the waste for the purpose of the  RFI may not be
possible due to the diversity of wastes managed in the unit over time or the relative
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inaccessibility of the waste in the unit. Waste characterization may be of limited
utility where:

     •  The waste managed in the unit varies over time such that adequate
         determination of the waste constituents cannot be made.  An example of
         this is  an offsite commercial  facility receiving different wastes from
         different generators.

     •  The unit of concern is no longer active and the waste cannot be sampled
         through a reasonable effort. This situation may occur at closed landfills
         where sampling of buried drums  may not  be  practical due to their
         inaccessibility.

     In certain situations, waste  characterization may also not be advisable.  For
example, the waste in question may be extremely toxic (e.g., nerve gas), or highly
reactive  or explosive (e.g.,  disposed munitions).   In such  cases, release
characterization may be based on constituents (or parameters) identified in the
affected medium  (e.g., leachate)  at the point where the medium becomes (or is
suspected of becoming) contaminated.  If it becomes necessary to conduct waste
characterizations in these situations, or to remove the  waste in question, a  high
level of health and safety protection (See Section 6) should be instituted.

     Waste  characterization  should also  be designed  to provide sufficient
information to support the implementation of interim measures and/or corrective
measures. For example, if buried drums are identified during the RFI, the nature of
the waste within  these drums  (e.g.,  ignitability, corosivity, reactivity, constituent
concentrations), if accessible, should be ascertained to determine if they should be
removed from the site and how they should be subsequently managed as well  as to
support the investigation of media-specific releases under the RFI.

     Design and operational characteristics of the unit are factors that will affect
the rate of release and location within the unit from which the contamination is
being or has been released. Such factors as unit size, type, operational schedule,
and treatment, storage, or disposal practices should be helpful.
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      Although 40 CFR Section  264.13 of the RCRA regulations (General Waste
Analysis) contains waste analysis requirements, the information required may not
always be sufficient for purposes of the RFI.  Waste characterization to determine
specific hazardous constituents, for instance, is not always required.  In addition,
little or no data on inactive units may be available.  The RFI Work Plan should be
                                              /
consistent, as appropriate, with the items identified in the requirements of 40 CFR
Section 264.13. Further guidance is given below.

7.2      Waste Characterization

      In cases where a waste characterization is to  be performed, the  following
approach is recommended:

      •  Identify data needs through review of existing information;

      •  Sample the waste; and

      •  Characterize the physical and chemical properties of the waste and waste
         constituents.

      If the  unit has a leachate collection system, the leachate should  also be
sampled and analyzed, as it may  also provide useful information, particularly with
respect to the teachable portions of wastes contained in the unit.

7.2.1     Identification of Relevant Information

      In general, a  waste characterization should produce the following types of
information:

      •  Identification of specific hazardous constituents and parameters which
         can be used in release verification or characterization (See Section 3.6);

      •  Physical  and/or  chemical  characteristics of the waste useful  for
         identifying possible migration pathways through the  environmental
         media of concern; and
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      •  Physical and/or chemical characteristics of the waste, which may be
         necessary to evaluate treatment and/or management options.

      Identifying specific constituents of the waste through a sampling and analysis
program may require an extensive level of effort. The owner or operator is advised
to use various informational sources on the specific waste in question in order to
focus the analytical effort required. Such sources are described below.

7.2.1.1        EPA Waste Listing Background Document Information

      The RCRA Hazardous Waste Listing Background Documents developed for
the identification and listing of hazardous wastes under  40 CFR  Part 261 contain
information on waste-specific constituents  and their  physical and chemical
characteristics.  These documents contain  information on the generation,
composition, and management of listed waste streams from generic and industry-
specific sources. In addition to identifying hazardous constituents in the wastes, the
documents may also provide data on potential decomposition products. In some
background documents, migratory potential  is discussed  and exposure pathways
identified.

      Appendix B of the Listing Documents provides detailed information on the
fate and transport of  hazardous constituents.   Major  physical and chemical
properties of selected constituents are listed, including molecular weights, vapor
pressures and solubilities, octanol-water partition coefficients,  hydrolysis rates,
biodegradation rates, volatilization rates, and air chemistry (e.g., reaction)  rates.
Another section of  this appendix estimates the  migratory  potential  and
environmental persistence of selected constituents based on a conceptual model of
disposal in an unconfined landfill or lagoon.

      The appropriate uses and limitations of the Listing Documents are outlined in
Table 7-1.  In addition, Case Study No. 1  in  Volume IV (Case Study Examples)
illustrates the use of the Listing Documents.

      A list of the available listing background documents may be obtained by
reviewing 40  CFR Parts 261.31 and  261.32.  These background documents are
available in EPA's RCRA docket at the following location:
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                     Table 7-1
Uses and Limitations of EPA Listing Background Documents
      Uses
                                           Limitations
fe  Identifies  the  hazardous •
   constituents for which a waste
   was listed.

•  In  some   cases,  provides
   information  on additional
   hazardous constituents that may
   be present in a listed waste.

   In  some  cases,  identifies
   decomposition products  of
   hazardous constituents.

   Provides overview of industry;
   gives perspective on range of
   waste generated (both quantity
   and general characteristics).

   May  provide waste-specific
   characteristic  data such  as •
   density, pH, and teachability.

   May provide useful information
   on the migratory  potential,
   mobility, and environmental
   persistence of certain hazardous
   constituents.

•  May list physical and chemical
   properties   of   selected
   constituents.
                          Applicable only for listed hazardous
                          wastes.

                          Industry coverage may be limited in
                          scope.  For example,  the Wood
                          Preserving Industry Listing Document
                          only covers organic preservatives.
                          Inorganics such as inorganic arsenic
                          salts, account  for approximately  15
                          percent of the wood  preserving
                          industry.

                          Data may not be comprehensive. For
                          example,  not  all  potentially
                          hazardous constituents may be
                          identified.  Generally, only the most
                          toxic constituents common to the
                          industry as a whole are identified.

                          Data  may  not  be  specific.
                          Constituents and waste characteristics
                          data often represent  an industry
                          average which encompasses many
                          different types  of production
                          processes and  waste  treatment
                          operations.

                          Some  Listing  Documents  were
                          developed  from  limited data/reports
                          available to  EPA at the time  of
                          promulgation, resulting in varying
                          levels of detail  for different
                          documents.

                          Listing Documents for  certain
                          industries (e.g., the  Pesticides
                          Industry) may be subject  to CBI
                          (confidential business information)
                          censorship. In such cases, constituent
                          information may be expurgated from
                          the document.
                        7-5

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      EPA RCRA Docket
      U.S. Environmental Protection Agency (WH-562)
      RoomS-212
      401MSt.,S.W.
      Washington, D.C. 20460

7.2.1:.2         Facility Information

      Identification of the constituents of a waste stream may be made through
examination of records already existing in the facility. Engineering data on process
raw materials or analytical data on the process effluents will also provide a good
starting point  for waste characterization.  In  some cases, generally where waste
characteristics  are well-defined, data on process raw materials or effluents will
provide sufficient information for  performing the RFI.  More specifically, these
sources may be:

      •   Hazardous waste  characterization  data used  for a RCRA Permit
          Application;

      •   Waste Analysis Plan (as required by 40 CFR Part 264.13);

      •   State or local permit applications;

      •   Initial batch treatment results from  an offsite hazardous waste disposal
          facility;

      •   Hazardous waste compatibility results for bulk shipments;

      •   Purchase orders and packing lists;

      •   Analyses conducted to provide data for shipping manifests;

      •   Facility records of past waste analyses;

      •   Process operational data;

      •   Product quality control analyses;
                                    7-6

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      •  Data from past releases of hazardous waste into the environment;

      •  Compatibility results for containment liner studies;

      •  Past Federal, State, or local compliance and inspection results;

      •  OSHA industrial hygiene monitoring results;

      •  Facility health and safety monitoring data;

      •  Engineering design data from construction of plant processes;

      •  Performance specifications for process equipment;

      •  Related emissions data such as NPDES discharge results; and

      •  Information from past or present employees.

7.2.1.3        Information on Physical/Chemical Characteristics

      Information on physical or chemical characteristics  of the waste or waste
constituents that may be useful in  predicting movement of the contamination
through the media of concern or in evaluating waste treatment or management
options may be found in the following references:

      Callahan, et aJL 1979.  Water-Related  Environmental Fate of 129 Priority
      Pollutants. Volumes I and II. Office of Water Planning and Standards. NTIS PB
      297606. Washington, D.C.  20460.

      Dawson, et aL 1980.  Physical/Chemical Properties  of Hazardous Waste
      Constituents. Prepared by Southeast Environmental  Research Laboratory for
      U.S. EPA. EPA RCRA Docket. Washington, D.C. 20460.

      U.S. EPA. 1985. Health Effects Assessment for [Specific Chemical]. [Note: 58
      individual documents available  for specific chemicals or chemical groups].
                                   7-7

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Environmental Criteria and Assessment Office. Cincinnati, Ohio 45268.  [See
Section 8.4 for a list of these documents]

Jaber, et a[. 1984. Data Acquisition for Environmental Transport and  Fate
Screening. Office of Health and Environmental Assessment, U.S. EPA.  EPA
600/6-84-009.  NTIS PB 84-140102. Washington, D.C. 20460.

Lyman, et a[.  1982.  Handbook of Chemical Property Estimation Methods.
McGraw-Hill, New York.

Mabev. et al. 1982. Aquatic Fate Process Data for c   anic Priority Pollutants.
Prepared by SRI International, EPA Contract Nos. 68-01-3867 and 68-03-2981.
Prepared for Office of Water Regulations and Standards. Washington, D.C.
20460.

U.S. EPA. 1980. Treatabilitv Manual. Volume I.  EPA 600/2-82-001 a. Office of
Research and Development. NTIS PB 80-223050. Washington, D.C. 20460.

U.S. EPA. 1984.   Characterization of  Constituents from Selected Waste
Streams Listed in 40 CFR Section 261. Office of Solid Waste. Washington, D.C.
20460.

U.S. EPA. 1984. Exposure Profiles for RCRA Risk-Cost Analysis Model. Office
of Solid Waste. Washington, D.C. 20460.

U.S. EPA. 1986. Ambient Water Quality Criteria. Office of Water Regulations
and Standards. Washington, D.C. 20460.

Perry  and Chilton. 1973.  Chemical  Engineers' Handbook.  McGraw-Hill.
5th Ed. New York.

Verschueren.  1983. Handbook of Environmental Data for Organic Chemicals.
Van Nostrand Reinhold Co. New York. 2nd ed.

Weastetal. 1979. CRC Handbook of Chemistry and Physics. CRC Press.
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      Windholtz,etal. 1983. The Merck Index. Merck & Co. Rahway, NJ.

      U.S. EPA.  1986.  Test Methods for Evaluating Solid Wastes. 3rd Edition.
      Office of Solid Waste.  EPA/SW-846. GPO No. 955-001-00000-1. Washington,
      D.C 20460.

      U.S. EPA.  1984.  Characterization of Hazardous Waste Sites--A Methods
      Manual. Volume III. Available Analytical methods. EPA 600/4-84-038. NTIS
      PB 84-191048. Washington, D.C. 20460.

      Some commercially available computer information systems that contain
chemical properties data and/or estimation methods may also be used. An example
would be the Chemical Information System (CIS) (7215 York Road,  Baltimore, MO
21212).  Another example is the Graphical Exposure Modeling System (GEMS) data
base discussed in Section 3.5. The owner or operator  should  consult with the
regulatory agency prior to use of such systems.

7.2.1.4        Verification of Existing Information

      If existing  information is current and sufficient to completely identify the
type, amount, and location of waste, then available information may be considered
adequate. If existing information is used, constituents present should be verified by
recent waste analysis or  by dated analysis that is substantiated by recent  facility
records showing that no changes in process, manufacturing, or other practices that
could alter waste composition have  occurred. If existing information does not
provide adequate waste characterization, or if the waste  characteristics have
changed, sampling may be required.

7.2.2     Waste Sampling

      All sampling should  be conducted in  a manner that maintains sample
integrity and encompasses adequate QA7AC The characterization of waste in any
unit must be representative.  As wastes are often generated in  bulk quantities from
a large variety of processes,  adequate determination of  the waste profile requires
that  cyclical or random variations in  waste  composition be considered.  The
characterization should account for variation in waste content by collecting samples
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that are representative of all potential waste variations. If a wide variation in waste
composition is expected, it is preferable to document the range of this variation
through the analysis of numerous samples.  If little variation is anticipated, a lesser
amount of sampling may be appropriate. If composite sampling is proposed, it must
not mask unexpected or unanticipated compositional variations, and should alwavs
be complemented with an appropriate number of grab (non-composited) same
Generally, compositing should not be used when evaluating variation in waste
composition. Collection of representative samples will involve different procedures
for different waste and  unit types. This is discussed  further in Section 7.4.  Case
Studies No. 3, 4, and 17 in Volume IV (Case Study Examples) provide illustrations of
waste sampling uses, considerations, and techniques.

7.2.3      Physical/Chemical Waste Characterization

      Compound-specific waste characterization should consider the  constituents
listed in 40 CFR  Part 261, Appendix VIII, as the universe of overall constituents.
Except for especially complex waste, many of the compounds on this list may be
eliminated using the guidance presented previously  in this section and in
Section 3.6. As indicated  in Section 3.6

      •   The owner or operator should provide a sound justification  or analytical
          results of waste analyses as substantiation for the elimination of
          constituents from further consideration;

      •   The analysis of waste samples to determine their characteristics should be
          performed using standard methods, such as those described in the 3rd
          edition of EPA/SW-846  (Test  Methods for  Evaluating Solid Waste), or
          equivalent methods; and

      •   A detailed QA/QC Plan should  clearly define the sample  preparation
          techniques, analytical methodology, required analytical sensitivities and
          detection limits, and collection of blanks and duplicates.

      In addition, for  units that contain a  mixture of solid, sludge, and/or liquid
waste material, each phase should be analyzed and volume proportions measured.
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7.3       Unit Characterization

      Information  on unit characteristics may affect  release properties and
pathways. The owner or operator should obtain relevant information on the unit
for use in developing the RFI strategy. Such information may include

      •   Unit dimensions (including depth below grade);

      •   Unit type;

      •   Unit purpose (e.g., biodegradation);

      •   Structural description, including materials and  methods of construction,
         and any available drawings;

      •   Amounts of waste managed;

      •   Previous uses of area occupied by unit;

      •   Unit location;

      •   Description of liner or cap materials;

      •   Holding/retention time;

      •   Key operating parameters, such as waste management schedule;

      •   Waste treatment/application or loading rate;

      •   Biological activity present;

      •   Vent numbers and sizes; and

      •   Drainage areas.
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7.4      Applicable Waste Sampling Methods

7.4.1     Sampling Approach

   .   References for waste sampling methods discussed in this section are listed in
Section 3.6.3. A summary of available waste sampling methods for various waste
matrices is provided in Table 7-2.

      Collection of waste samples requires methodology suited to the type of waste
and unit sampled. In addition, waste sampling requires specialized equipment and
protocols that may be designed especially for waste analysis or adapted from other
sampling methods.  Several important points to consider  when developing  a
sampling approach are as follows:

      •  Compatibility of sampling methods and materials with the constituents
         being sampled.

      •  Ensuring the safety of personnel.  Careful attention should be given to
         the level of protection and safe practices required for sampling activities.
         If the sampler is wearing protective gear that limits vision and mobility,
         or is fatiguing to wear, the collection procedures should be as simple as
         possible.

      •  Waste samples are generally not preserved and are considered hazardous
         for shipping purposes.

7.4.2     Sampling Solids

      Sampling of solid materials  should utilize readily available techniques.  In
general, the primary concern for  the sampling of  solid  materials is effectively
representing a large amount of possibly heterogeneous material in small samples.
In order to address this concern, discrete samples should be collected from sufficient
locations to characterize the waste with respect to location and time. Sampling
methods vary depending on whether samples are to be collected at the surface, or
                                   7-12

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below the surface.  For a unit currently in operation, variation in waste stream
composition over time should be considered in determining when samples should
betaken.

     For large amounts of solid materials, sample locations may be determined by
applying a three-dimensional  grid  in combination with  random sampling
techniques as discussed in Section 3.  In certain circumstances, compositing samples
may be acceptable to minimize the  number of sample analyses, as long as waste
composition remains fairly constant over the sampling period.  When composition
waste is expected to vary (e.g., in complex wastes), grab samples should be taken.
Compositing should  be employed only when the representativeness of the waste
characterization is uncompromised,  and should  always  be accompanied  by
confirmational grab samples.

     Bulk solid materials are generally homogeneous. They are likely to be found
in waste piles, drums, bags, trucks or  hoppers, or on conveyor  belts.  Bulk solid
materials can be sampled using various methods.  Surface soil or soil-like materials
found at land treatment units, in landfills, and at waste transfer (e.g., loading and
unloading) areas can also be sampled  using the same basic methods.  Deeper soil
sampling will require other methods as described in Section 9 on soil.

     Five basic solid sampling methods are discussed below:

     •   SCOOPS  and shovels are useful  for sampling dry  or moist granular,
         powdered, or otherwise unconsolidated solids from  piles as well as from
         other containers of solid material (e.g., bags, drums, hoppers, trucks, or
         shallow containers). Waste material transported to the unit by conveyor
         belt can be sampled using  a scoop to collect samples  from the belt.
         Scoops are applicable to solid waste materials that are within easy reach
         of sampling personnel. Scoops made of stainless  steel or Teflon are
         preferable due to the inertness of these materials to most waste types.
         This sampling method is limited in utility to collection of samples near or
         on the surface of the waste. For collection of samples at greater depth,
         other methods are necessary.  Shovels are used in the same manner as
         scoops when larger quantities  of sample are  needed or  when  an
         extended reach is required.  Shovels are available in inert materials like
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Teflon or stainless steel. Scoops and shovels will enable collection of land
treatment unit samples from depths up to about 16 inches. Because most
land treatment units manage organic waste streams, extreme care must
be taken to retain the volatile organic components of the sample
through  rapid handling of the exposed sample during the collection
process.  Containers that have septum  caps or air-tight lids should be
used  in conjunction with the  scoop and shovel sampling method.
Collection of soil samples from depths lower than the  normal depths of
tilling are described in Sections.  Contaminated surface soils at waste
transfer areas are also easily sampled using scoops and shovels.

Triers are used to withdraw a core of sample material.  The trier is similar
to a scoop in that it is inserted by hand into the material to be sampled;
however, the design allows for the collection of a core of material. Triers
are most useful for sampling waste piles, bags, hoppers, or other sources
of loose solid waste material. Cores are most readily obtained with triers
when the material  being sampled  is moist or sticky so that the core,
which is  cut by rotating the trier,  stays together while the sample is
removed from the waste material source. These samplers are useful only
when they can be inserted horizontally into the material being sampled.
Triers are readily available in lengths from 61 to 100 cm and are usually
made of stainless steel with wooden handles.

Thiefs are essentially long hollow tubes with evenly  spaced openings
along their lengths. An inner tube with similar openings is oriented so
that the  openings are not aligned and the entire dual-tube thief is
inserted into the solid  waste material. After insertion, the inner tube is
rotated to align the openings, thus allowing the solid material to flow
into the inner tube. The inner tube is then rotated back to the closed
position, sealing the openings prior to withdrawal of the sampler. Thiefs
can be inserted horizontally, vertically, or at various angles into the
sample as long as the material will flow (by gravity) into the slots of the
sampling tubes.  This  method  is best suited for sampling of dry free-
running solids.  Thiefs are available  in a range  of sizes to allow for
collection of materials of varying particle size, but are not generally
useful for particles in excess of 0.6 cm.  Thiefs, like triers, are available in a
                          7-15

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variety of materials, usually brass or stainless steel, and are appropriate
for sampling waste piles, drums, or hoppers.

Augers can be used to sample solid material at varying depths.  The use
of augers is generally exclusive to the collection of soil samples at depth
such as at landfills.  However, for large waste piles which cannot be
sampled in any other manner, it may be necessary to obtain samples from
the inside portions of the pile in order to assess the overall characteristics
of the material in the pile.  Generally, augers are used in conjunction
with a thin-wall tube sampler that is inserted into the borehole to collect
an undisturbed sample from the depth at which the auger was stopped.
The nature of the solid material and the physical size and accessibility of
the unit will determine the applicability of  augering and the most
suitable type of auger. Augers are designed  for general types of soil
conditions and "disturb" samples to varying degrees.  If possible,
sampling of waste material should be conducted prior to or during waste
placement because sampling by augers and thin-wall tubes can  be
difficult and time consuming. Backhoes may be required to gain access to
the interior portions of the unit (e.g., a waste pile).

Core samplers such as previously described in conjunction with augers are
frequently used for soil sampling. Section 9 addresses soil sampling in
greater detail.  Core samplers can also be used to collect cores of land
treatment unit samples and provide excellent samples for spanning the
depth of treated soil. Thin-wall tube core samplers can be used to collect
vertical  cores at most desired locations. Sampling  of top soil layers that
contain the  applied waste material can usually be accomplished using
conventional hand coring techniques.  As with the scoop and shovel
method, extra consideration should be given to  preventing  losses of
volatile organic components from the sample; the use of air-tight sample
containers is recommended.  Another technique is to utilize a core
sampler which can itself  be used as an air-tight sampling container.
Recent designs include a  coring device with Teflon-gasketed end caps
that can be used to both collect and contain land treatment samples for
soil and soil-gas analyses.
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7.4.3      Sampling Sludges

      Sludges are "semi-dry"  materials ranging from dewatered solids to  high-
viscosity liquids. Due to their liquid content, sludge materials are not usually stored
or handled as solids, and often require containment in  drums, tanks, or
impoundments, to prevent runoff of the liquid portion of the sludge.  Sludges also
include sediments with high liquid content under a liquid layer. Sampling must
frequently include  extended-reach equipment to gain access  to the submerged
sludge layer.  For those cases where sludges are piled and have a sufficiently high
solids content, methods previously discussed under "Solids" may be adequate. The
equipment used in  some of the solid material sampling methods is available with
modifications to contain samples with a high liquid content.

      Sediments can accumulate at  the  bottom of drums due to settling of
suspended solids in liquid and sludge wastes.  These sediments can be readily
sampled  using  the previously discussed  methodology.  Glass-tube  samplers,
particularly those of larger bore, can be pressed into bottom sediments of drums to
obtain samples. For bottom sediments or sludges that are too thick or resistive for
glass tubes, corers with or without core catchers can be inserted into the drum for
collection of sediments.

      Basic methods for sampling sludges are discussed below:

      •   Scoops and shovels are useful for collecting sludge samples from the
         surface of a sludge pile, or at shallow depths in drums, tanks, or surface
          impoundments.  Shovels will allow for the collection  of larger volume
         samples.  Extra care  may be required to collect "representative" samples
         if the liquid fraction of the sludge tends to separate  from the sample
         while being collected.  The liquid fraction should be considered part of
         the sludge material and must be retained for adequate characterization.
         Long-sleeve gloves may be required for personnel protection.

      •   Triers may be useful for collection of cores of material from sludge piles.
         The nature of the waste will determine the utility of this method.  Triers
         are not generally used  for sludges; however, on a trial-and-error basis,
         their applicability may be determined.
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Core samplers modified to retain sludge material can be used to collect
sludge from waste piles where samples are required from various depths.
Core catchers, such as thin-wall tube samplers that prevent washout of
the wet sludge during recovery of the sampler from the sludge source,
are available for attachment to the tip of coring devices. Because sludges
are most often formed through deposition of solids from a liquid
mixture, the composition of the sludge may vary significantly with time
and location. The use of a core sampler equipped with a core catcher can
provide for collection  of a sample  profile. These types of corers are
available with  extension sections that allow for collection of samples
from depths well below the surface of the waste. Corers are generally
equipped with a cutting edge  on the tip that greatly facilitates
penetration of a thick bottom layer  and can also be outfitted with core
catchers to assist in retaining looser sediment materials that might be
more readily lost from the bottom of a glass tube. The amount of sludge
present can be  easily estimated by measuring the depth to the apparent
bottom and comparing it to the known interior depth.

Glass tubes or  a Composite Liquid Waste Sampler (CO U WAS A) can be
used to collect bottom sediments from drums or shallow tanks when they
are gradually inserted into the solid layer at the bottom.  Due to the
fragility of glass and the danger of cuts, this technique is applicable only
for materials easily penetrated by the tube. High-liquid-content bottom
sediments may exhibit washout characteristics similar to liquid samples.
In many cases, the only way to determine if sample losses from the
bottom of the tube will occur is to carefully test it to see what happens.

Petite Ponar Grab Samplers  are clamshell-type scoops activated by a
counter-lever system.  The shell is opened and latched in place, then
lowered to the bottom. When tension on the sample line is released, the
shell halves are unlatched. The lifting action of the cable on the lever
system closes the clamshell.  These  dredges are capable of collecting
most types of sludges or sediments from silts to granular materials up to
a few centimeters in diameter.  As agitation of the  liquid above the
sludge occurs during sampling, it is advisable to collect sediment samples
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         after all liquid sampling is complete. This method is particularly useful
         for tanks and surface impoundments.

7.4.4     Sampling Liquids

   -   Liquid wastes require distinctly different sampling methods than do solids
and sludges, with the exception of some techniques for sampling submerged
sediments, and should also  account for parameters of interest  (e.g., for volatile
contaminants,  it  is important  to prevent volatilization).  Common  liquid  waste
sources are drum handling  units, tanks, and surface impoundments.  A general
safety concern associated with drums and tanks is the structural integrity. Safe-
access procedures for sampling these units should be established prior to sample
acquisition.

      Liquid wastes handled in drums can be sampled before being loaded into the
drum or, if necessary, after placement.  For facilities that receive wastes in drums,
sampling should be conducted prior to the removal of the waste material from the
drum. For waste streams that can be sampled directly prior to drum loading, grab
sampling techniques are appropriate.  As always,  sufficient samples should  be
collected to account for waste variation over time. Sampling of drums can be done
using several different methods, including grab sampling with a dipper from the
open drum, routine full-depth drum sampling using a  disposable  glass tube or
COLIWASA, or with a sampling pump with tubing that is lowered into the drum for
sampling.

      Tanks are containment structures larger than drums that can hold more than
a million gallons. Tanks include tanker trucks, above-ground tanks, and partially or
fully underground tanks. Tanks usually have limited access due to small hatchway
openings, or ladders or walkways that often extend across open-top tanks. Due to
the greater depth of tanks versus drums, methods with extended-reach capabilities
are necessary.  Waste  materials  in tanks generally include liquids and bottom
sludges.  When  retention time of liquid wastes  in tanks is  long, layering or
stratification including settling out of sediments is likely to occur.  Great care should
be taken to minimize the disturbance of liquid layers while collecting samples.  The
surface should  be broken gently and samplers lowered gradually. Liquid sampling
utilizes either  pump and tubing methods  or discrete  depth  samplers, such as
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Kemmerer Bottles or Bacon  Bomb samplers. Bottom sediments that cannot be
drawn up with a pump will require the use of small dredges, such as the Petite Ponar
Grab sampler.

     Surface impoundments can range from several hundred to several million
gallons in capacity. Due to their large size, they are usually open to the atmosphere
rather than covered. Sampling of an impoundment may be difficult, except near its
edges or from walkways that extend over the impoundment. "Off-shore" sampling,
when necessary, should be considered a serious, potentially dangerous operation
and should be  performed according to strict health and safety procedures.
Common means of sampling off-shore locations are boats, floating platforms,
cranes  with  suspended enclosed platforms, and mobile  boom vehicles with
platforms.

     Whenever possible, the waste should be characterized prior to its transfer
into the impoundment. For example, waste pipelines can be sampled from valves,
and tanker trucks discharging waste into impoundments can be sampled prior to
discharging.  However, taking samples from the units is desirable, because changes
in the concentrations reported for samples taken during transfer may have large
impacts on the estimates of the amounts of hazardous waste or constituents in the
impoundment.

     Liquid sampling techniques for impoundments include Dippers (particularly
in the pond sampler configuration with a telescoping handle),  pump and tubing,
Kemmerer Bottles, and Bacon Bomb samplers. The dipper or pond sampler method
is the easiest to use; however, it is not capable of reaching off-shore locations or of
collecting samples at varying depths below the surface.

     Liquid sampling methods are described below:

     •  Dippers can be used to collect samples from the surface liquid layer of
         open drums, tanks, or impoundments. (Other techniques are required to
         collect samples from drums where the only access is through the bung
         hole in the lid).  This method is appropriate only for wastes that are
         homogeneous  and likely to be represented by a grab sample from the
         top layer.  In most cases, a full-depth composite  liquid sample is more
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    representative. The dipper technique involves the use of an intermediate
    vessel that is submerged in the waste liquid. The sample is then poured
    into the designated sample container. Handles are attached to the vessel
    to make sampling easier and reduce direct contact  of  the sampling
    technician with the waste material. In one configuration, the dipper is
    attached to  a telescoping pole for an extended reach; this configuration
    is called a pond sampler. The dipper sampling device is also useful for
    sampling from piping system valves.

•   Glass tube samplers can collect a full-depth  liquid sample from a drum
    and can be used through the bung hole on the drum lid such that the lid
    need not  be removed.  Conventionally, the glass tubes are 122cm long
    and 6 to 16 mm in inside diameter. Larger diameter tubes can be used if
    the liquid to be sampled is more viscous. The major limitation of this
    method is spillage (i.e., liquid  loss from the bottom of the tube is
    unavoidable). Smaller diameter tubes have fewer problems with sample
    loss than do large-bore tubes. This method is perhaps the most common
    drum sampling technique due to its relative ease of use and the minimal
    equipment decontamination required.

•   CO LI WAS A samplers are a more formalized version of the glass-tube
    samplers.  The COLIWASA (composite liquid waste sampler) utilizes an
    inner rod attached to a stopper at the bottom of the sampling tube. The
    sampler is slowly inserted into the drum with the bottom  stopper open.
    When the sampler reaches the bottom, the inner rod is pulled up, sealing
    the sampling tube for removal of the sample. A COLIWASA can be made
    of many materials; however, inert materials (e.g., Teflon or glass) are the
    materials of choice.

•   Pump and tubing (e.g., bladder pumps) systems are readily available and
    are useful for withdrawing liquid samples from up to 28-foot depth.
    Peristaltic pumps are available  in many sizes and flow  rates to
    accommodate many sampling situations.  Full-depth composite samples
    can be collected by gradually lowering the tubing into the material being
    sampled. One limitation of this system is that the pump applies a vacuum
    to the sample that can  alter the chemical equilibrium in the sample,
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resulting in the loss of volatile organic components. A modification to
this basic system can be made by placing a sample vessel in-line between
the tubing and the pump to prevent sample material from contacting the
pump parts.'  In this configuration, collection of numerous samples is
facilitated because pump  tubing  need not be cleaned or replaced
between sampling events.

High flow  rates are not advisable because rapid overflowing of sample
bottles may occur.  A lower flow rate will assist in minimizing the
disturbance of liquid layers in the tank and will cause less agitation of the
sample as it enters the sample bottle. The peristaltic pump and tubing
system can be utilized in two configurations - one with the tubing
connected directly to the  pump and a second with an intermediary
sample vessel in-line between the pump and tubing.  The  second
configuration also eliminates pump decontamination between samples.
When  sufficient waste characterization data are available, small
submersible  pumps can also be used; however, these pumps are not
generally made of chemically resistant or relatively inert materials.  The
utility of these small submersibles depends on their ability to provide
samples from greater depths.  Peristaltic pumps have an upper  limit of
approximately 8 meters, whereas submersibles can be used for most
depths of concern.

Kemmerer Bottles are discrete-depth liquid samplers that are  usually
appropriate for tank or impoundment sampling.  The Kemmerer Bottle is
a spring-loaded device that is lowered into the  liquid in the open
position, allowing the liquid sample to flow through it while it is
descending.  At the desired depth, a messenger is dropped down the
sample line, releasing the spring-loaded closing device to  obtain the
sample. Limitations of Kemmerer Bottles include the poor availability of
devices constructed  of relatively inert  materials,  the difficulty in
decontamination between sampling, and the inability of this sampler to
collect purely depth-discrete samples (because the sampler's surfaces are
exposed to materials in the liquid layers as the sampler passes through
them to arrive at the designated depth).
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Bacon Bomb samplers are lowered on a sample line.  A second line
attached to an opening rod, which runs down the center of the bomb,
will open the sampler when pulled. The sample can be collected with a
minimal amount of agitation since the rod can open the top and bottom
of the bomb, allowing the sample to enter the bottom and air to exit
through the top. Bacon Bomb samplers are readily available  from
laboratory supply houses and are frequently  constructed of  chrome-
plated brass.  Relatively inert construction  materials, such as Teflon or
stainless steel,  are preferable. Careful  maintenance  and regular
inspection of samplers is advised. Samplers with plating materials flaking
off should be removed from use.  If waste characteristics are known,
sample changes caused by the sampler can be avoided by using materials
compatible with the type of waste being sampled. An advantage of the
Bacon Bomb sampler is its ability to be lowered to the desired depth in
the closed position before collecting a sample. This technique minimizes
cross-contamination from liquid layers above.
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                                 SECTIONS

                 HEALTH AND ENVIRONMENTAL ASSESSMENT

8.1        Overview

     This section describes the Health and Environmental Assessment (HEA) that
will be conducted by the regulatory agency as part of the RFI. The primary element
of this assessment is  a set  of  health  and  environmental  criteria (chemical
concentrations) to which measured and in some cases predicted (e.g., for the air
medium) concentrations of hazardous constituents developed during the release
characterization will be  compared.  When these criteria  ("action levels")  are
exceeded or there is a reasonable likelihood of this occurring, a Corrective Measures
Study (CMS) will generally be required,  although the owner or operator may,
because of site specific factors,  present data and  information  to support  a
determination that no further action is necessary.  This section describes the HEA
process (Section 8.2), the determination  of potential exposure routes for each
environmental medium of concern (Section 8.3), and the development and use of
the health and environmental criteria (Section 8.4), leading to an evaluation of the
need for appropriate interim corrective measures and/or a CMS. The evaluation of
chemical mixtures is discussed in Section 8.5. Special considerations involved in the
evaluation of soil and sediment contamination are discussed in Section 8.6. Section
8.6 also provides a review of statistical procedures that may be used to evaluate
ground-water monitoring data. Section 8.7 discusses qualitative and other factors
which  may  be used by  the regulatory  agency  in conducting the health and
environmental assessment. Interim corrective measures are discussed in Section 8.8.
References used in developing this section are listed in Section 8.9. Finally, Section
8.10  presents  the  health  and  environmental   criteria  and provides several
worksheets which may be used to conduct the HEA.

     The health and environmental criteria used in determining the need for a CMS
are based  primarily on EPA-established chronic-exposure limits. These values and
their use are described herein. Subchronic exposure limits and qualitative criteria
are also discussed.  It should be emphasized that the health  and environmental
criteria provided in this section do not necessarily represent clean-up target levels
that must be achieved through the implementation of corrective measures. Rather,
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they establish presumptive  levels that indicate that  a  closer examination  is
necessary. This closer analysis would generally take place as part of a CMS.

     The guidance  provided in this  section presents a general framework for
conducting a HEA.  It is intended  to provide a flexible approach for interpreting
release characterization data, as case-specific factors may enter into consideration.
For example, State-established criteria and  consideration  of  past environmental
problems (e.g., fish-kills) may also be considered.

     The regulatory agency  may require both interim corrective measures and a
CMS as a result of the HEA.  One difference between interim  corrective measures
and  definitive  corrective  measures  may  be timing.  The development  and
implementation of  a comprehensive corrective  action  program can be a time-
consuming process.  Between the time of  the  identification of  a  contaminant
release and the implementation and completion  of definitive corrective measures,
existing conditions or further contaminant migration could endanger human health
and the environment  Under these conditions, interim corrective measures, which
may be temporary  or short-term measures (e.g., providing bottled water or
removing leaking drums) designed to prevent or minimize adverse exposure, can be
applied.   Case Study No.  11 in  Volume IV (Case  Study  Examples) provides an
illustration of the HEA process.

     The HEA procedures described in this section apply to releases from all units
except releases to ground water from "regulated units" as defined under 40 CFR
Part 264.90(a)(2).  Releases  to ground  water from "regulated units"  must be
addressed according to the requirements of 40 CFR §264.91 through §264.100 for
purposes of detection, characterization, and appropriate response.

8.2       Health and Environmental Assessment Process

     The HEA is a continuous process that begins with the initiation of the RFI. As
investigation data  (from  monitoring and/or modeling) become available, both
within and at the conclusion of discrete phases, they should be reported to the
regulatory agency as required. The regulatory agency will compare these data to
applicable  health   and environmental criteria,  including  evaluation  against
qualitative criteria,  to determine the need for (1) interim corrective measures;
and/or (2) a  CMS.   Notwithstanding this process, the owner or operator has a
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continuing responsibility to identify and respond to emergency situations and to
define priority situations that may warrant interim corrective measures. For these
situations,  the  owner  or  operator should follow the RCRA Contingency  Plan
required under 40 CFR Part 264, Subpart D and Part 265, Subpart D.

     The results of the media-specific investigations described in Volumes  II and III
of this Guidance will be used to identify the constituents of concern, constituent
concentrations  within the release, general release characteristics (e.g.,  organic,
inorganic), the affected environmental  media, exposed  or potentially  exposed
human or environmental receptors, the rate of migration of the release,  and the
extent of  the release.  The objective of the HEA  is to integrate  these results to
determine whether interim corrective measures and/or a CMS may be necessary. In
general, this objective is achieved in a two-step process.

     First, potential human and environmental  exposure routes are determined.
Section 8.3 provides guidance for determining potential exposure routes for the
media of concern.  For ground water,  surface water, soil, and air, methods are
described  for making exposure route-specific comparisons with the  health and
environmental criteria.  Subsurface gas migration and inter-media  transport of
contamination from other media to air (e.g., ground-water contamination resulting
in seepage of volatile constituents to basements) are addressed as air problems to
the extent that they contribute hazardous constituents to ambient air, whether
indoors or outdoors.  Evaluation of the migration of methane gas in the subsurface
is also addressed  in this section (Section 8.8) as part of the guidance on interim
corrective measures, due to the immediate explosion potential of methane.

     Second, the  measured (or in  some cases, such as releases to air, predicted)
constituent concentrations  in  the  release  are  compared  to  EPA-established
exposure-limit  criteria.    At  any  time  during  the  RFI  when  contaminant
concentrations in  the release are found to exceed the health and environmental
criteria,  a CMS will generally be required by the regulatory agency, although the
owner or  operator  may,  because  of  site-specific factors, present data and
information to  support a  determination that no  further action is necessary.  In
addition, when health and environmental criteria  are  exceeded, the need for
appropriate interim corrective  measures will also  be  determined.  This process
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involves an evaluation of exposed or potentially exposed human and environmental
populations. This process is discussed in more detail in Section 8.8.

     The determination of whether a CMS may be necessary will be made by the
regulatory agency, by  comparing  constituent concentrations determined  at
locations within the release to the health and environmental criteria discussed in
Section 8.4. These criteria serve as "action levels" for determining whether a CMS
will be necessary.  Figure 8-1 depicts a  hypothetical facility with individual solid
waste management units and a  contaminant release originating from one of the
units. For ground water, surface water, soil, and subsurface gas, the comparison of
constituent concentrations with the criteria will be made for all measurements
within the release at and beyond the limit of the waste management area.

     The evaluation procedure for releases to air differs from the other media in
that comparison of constituent concentrations with the health and environmental
criteria will  be made at the facility property boundary.   However, onsite  air
comparisons may be necessary in cases where people reside at the facility or when
worker safety regulations are deemed inadequate to protect human health and the
environment, although onsite air contamination normally would fall under the
jurisdiction of OSHA.   As  indicated  in  the Air Section  (Section 12), the values
compared can be either measured values derived  from  monitoring or  predicted
values derived from modeling.

8.3       Determination of Exposure Routes

     Some  of the  more  significant  potential  exposure  routes  for  each
environmental medium are presented in Table 8-1. This table should be used to
determine the appropriate  health and  environmental criteria to be used in the
comparison with measured  or predicted constituent release concentrations.  For
example, when releases to ground water have been identified, a primary exposure
route of concern is drinking water. For each constituent identified in the ground-
water release, the  measured concentrations are compared with the appropriate
criterion values discussed for drinking water in Section 8.4.

     Suspected or known inter-media transfers of contamination should have been
characterized (i.e., nature, extent and rate) during the  RFI process. For example, if
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         FACILITY BOUNDARY
LEGEND:
       SAMPLING LOCATIONS
     FIGURE 8-1. HYPOTHETICAL FACILITY WITH INDIVIDUAL SOLID WASTE
               MANAGEMENT UNITS AND A CONTAMINANT RELEASE
               ORIGINATING FROM ONE OF THE UNITS.
                               8-5

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                             TABLE 8-1

                    Some Potential Exposure Routes
Contaminated Medium
SoiM
Ground Water
Subsurface Gas?
Air
Surface Water1
Exposure Route
Soil Ingestion (surficial soil), Dermal
Contact
Ingestion of Drinking Water
Inhalation
Inhalation
Ingestion of Drinking Water
Consumption of Contaminated Biota
(e.g., fish)
1  Exposure routes  for deep contaminated  soils  and bottom sediments
   underlying surface water bodies are addressed separately in Section 8.6.

2  Migration of methane gas in the subsurface presents a problem due to the
   explosive properties of methane. This is treated  as an immediate hazard
   and is discussed under interim corrective measures (Section 8.8).

[Note:   Other important exposure pathways can include inhalation of
        volatile constituents released during domestic use of contaminated
          ground water or when such ground water seeps into residential
          asements.   Similarly, various exposure  pathways can lead to
        adverse effects  on environmental  receptors (i.e.,  animals  and
        plants).]
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the initial contaminant release was to the soil medium and eroded soils have been
transported to surface water, both soil and surface water contamination should
have been adequately characterized during the RFI.  In this example, the regulatory
agency will consider exposure in both media. In cases where subsurface gas, soil, or
ground-water  releases have caused contaminant  seepage to basements, inter-
media  transfer to the  air may  pose  an  inhalation  hazard.  In  such  cases,
contamination of. basement areas should  have been  adequately  characterized
during the RFI process.

8.4      Health and Environmental Criteria

     The preliminary set of health and environmental criteria are presented in
Tables 8-5 through 8-10 in Section 8.10.  The constituents shown in  Tables 8-5
through 8-10 are a subset of the hazardous constituents listed in Appendix VIII of 40
CFR Part 261. It should be noted that the definition of constituent may also include
components of 40 CFR Part 264, Appendix IX that are not also on Appendix VIII, but
are normally monitored for during ground-water investigations. Tables 8-5 through
8-10 identify such constituents, where criteria for these constituents are available.

     The concentrations shown  for each  constituent  are derived. from  EPA-
established chronic (and  in some cases acute) toxicity criteria for ingestion (soil and
drinking water) or inhalation exposure routes, and were calculated  using a set of
intake assumptions for the various media, as shown in Table 8-2. As indicated in the
footnotes accompanying Tables 8-5 through 8-10, the criteria presented are subject
to change. Therefore, these numbers should be confirmed by the regulatory agency
prior to use.

8.4.1     Derivation of Health and Environmental Criteria

     Maximum Contaminant Levels (MCLs)  -- Table 8-5  provides the  maximum
contaminant levels (MCLs) for drinking water promulgated under the Safe Drinking
Water Act. In developing these values, total environmental exposure to a particular
contaminant from  various sources (e.g.,  air, food,  water) and gastrointestinal
absorption were considered.
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                        TABLE 8-2

     Intake Assumptions for Selected Routes of Exposure
 Surficial Soils (Inaestion):
   0.1 g/day for 70 kg person/70 year exposure period for
   carcinogens

   0.2 g/day for a 16 kg child/5-year exposure period for
   systemic toxicants*'
 Surface and Ground Water (Inoestion):
   2 liters/day for 70 kg adult/70-year exposure period
 Air (Inhalation):
   20 m3 air/day for 70 kg adult/70-year exposure period
*  Corresponds to the period of 1 to 6 years of age.
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     The MCL, when available for a constituent released to ground water or surface
water, should be used  as  the  evaluation criterion for human drinking water
consumption  for that constituent.  If an MCL does not yet exist for a particular
constituent, criteria in the other tables presented in Section 8.10 should be used,
where available. If air, surficial soil, or sediment (See Section 8.6) are the media of
concern,  or when evaluating aquatic life exposure or human consumption  of
aquatic organisms, the MCL is not used.  In such cases, the criteria in the other tables
should be used, as described below. [Note:  EPA is in the process of developing a
number of new MCLs to be issued over the next several years.]

     Carcinogens --  Table  8-6  presents  the human  health-based criteria  for
carcinogens.  These criteria, calculated from Risk-Specific Doses  (RSDs), were
developed according to EPA Guidelines for Carcinogen Risk Assessment (U.S. EPA,
1986). The RSO is  an upper bound  estimate of the average daily dose of a
carcinogenic substance that corresponds to a specified excess cancer risk for lifetime
exposure. The values presented in Table 8-6 are environmental concentrations that,
under the intake assumptions shown in Table 8-2,  correspond  to excess lifetime
cancer risks of 10-6 for Class A and  B carcinogens, or 10-5 for Class C carcinogens.
Table 8-6 presents the class (A, B or C) of the carcinogen (See U.S. EPA, 1986, for a
description of carcinogen classification).

     The criteria presented in Table 8-6 were calculated from RSDs in the following
manner:

          Q    «   (R/qi*)x(W/l)                              (Equation 8-1)

where

          Q    *   the criterion concentration for the constituent of interest;
          R    =   the specified risk level (e.g., 10-6);

          q,«   =   the carcinogen slope factor (CSF) in (mg/kg/day)-i developed
                   by the Carcinogen Assessment Group (CAG) of the EPA, Office
                   of Health and Environmental  Assessment, or  the  Agency's
                   Carcinogen Risk Assessment Verification  Endeavor (CRAVE)
                   Workgroup;
                                    8-9

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       (R/q,0   =   theRSD;

          W    a:   the assumed weight of the exposed individual; and

          I     =   the intake amount for a given time period.

     For example, the health-based criterion (C,) for aldrin, a Class A carcinogen,
was calculated for water in the following manner:

          Ci    «   (R/qr)x(W/l)

               s   (10-6/1.7E + 01 (mg/kg/day)-i) x (70 kg/2 liters/day)

               s   2.1 x 10-6 mg/!iter
               s   2.1 x 10-3 yg/liter

     Calculation of the criteria for soil ingestion  and air inhalation shown in Table
8-6 takes essentially the same form.  However, the  values for the. assumed intake
rate (!) differ. The assumed intake rate for soil that is used in the calculations for
carcinogens is 0.1 g/day for a  70-kg person. The current conservative, linear models
that  the  Agency uses  in cancer  risk assessments consider the  expression  of
carcinogenic effects to be a function of cumulative  dose, and thus assume that, in
general, elevated exposures during early childhood alone are not that significant in
determining lifetime cancer risk.  Therefore, the  soil intake value of 0.1 g/day is an
upper-range estimate of soil ingestion  for adults.  The intake rate  (I) for air
inhalation is 20 m3/day for a 70-kg person.

     Many of the  health-based  criteria  for carcinogens shown  in Table 8-6 are
below current  analytical detection  limits (See  Section 3.6 for a discussion  of
detection  limits). For example, the concentration for dieldrin in Table 8-6 is 2.2 x
10-3 ug/l for the drinking water exposure route, while the corresponding current
limit of detection for this constituent is approximately 5 x 10-2 ug/l. In those cases
where the HEA criterion is less than the limit of detection, the detection limit will be
used as a  default value when making comparisons to investigation  data,  unless
acceptably determined  modeling  values  can  be  applied  (i.e., values from air
dispersion models).
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     The criteria provided in Table 8-6 address the surficial soil (ingestion), water
(ingestion), and air (inhalation) routes of exposure. For human health assessment,
the carcinogen criteria for water should be used when ground water or surface
water is the medium of concern, unless MCLs exist or there are lower values for the
constituents of concern in Table 8-7. The carcinogen criteria  for surficial  soil
(ingestion) and air (inhalation) should be used if surficial soil  or air, respectively, is
the medium of concern, unless a lower value appears in Table 8-7. If a  particular
constituent is not identified in Table 8-6, the criteria in Table 8-7 (systemic toxicants)
should be used, if available. As alluded to above, constituents that are both known
carcinogens and systemic toxicants (e.g., chloroform) will have values in both Tables
8-6 and 8-7.  In such cases, the lower of the  two values should  be used as the action
level.  Both values are presented  in the  tables  if  needed  for determining  the
additive toxicity of mixtures (see Section 8.5).

     Systemic Toxicants --  Table 8-7 presents the human health-based criteria for
systemic toxicants. These criteria, calculated from Reference Doses (RfDs), are an
estimate of the daily exposure an individual (including sensitive' individuals)  can
experience without appreciable risk of health effects during a lifetime.  For water
ingestion, the systemic criteria are calculated for a 70-kg aduit for a chronic lifetime
exposure period (i.e., 70 years).  For soil ingestion, the assumed intake rate of 0.2
g/day is based  on a  5-year exposure period for  a  16-kg  child.  These exposure
assumptions for soil are reflective of an average scenario in  which children ages 1-6
(who exhibit the greatest tendency to ingest soil) are assumed to ingest an average
amount of soil on a daily basis. The concentrations shown in Table 8-7 were
calculated using the  intake assumptions presented  in Table 8-2  for the selected
exposure routes, as shown in the following equation:

          Q    a   (Rf D) x (W/l)                                (Equation 8-2)

     For example, the concentration (Cj) for surface water and ground water for
pentachlorobenzene shown in Table 8-7 was calculated in the following manner:

          Cj    s   Criterion concentration for constituent of interest

          RfD  «   Reference Dose for pentachlorobenzene
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               a   8 x 10-4 mg/kg/day

          I     »   ingestion rate (from Table 8-2)

               =   2 liters
                      day

          W   s   adult body weight (from Table 8-2)

               =   70 kg

          Q    «   (8x1 
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systemically toxic (e.g., chloroform) and, thus appear in both Tables 8-6 and 8-7. In
such cases, the  lower of the two values  should be used  for human health
assessment.

     Water Quality Criteria -- A summary of the EPA Water Quality Criteria (WQC)
appears in Tables 8-8 and 8-9. These criteria exist to protect both marine and fresh-
water aquatic life and address both acute and chronic toxicity. WQC also exist for
protection of human health through water  and fish  consumption (incorporating
both routes of exposure), and for fish consumption only. If human consumption of
both the surface water and contaminated aquatic organisms is a factor, the set of
criterion values based on ingestion of contaminated aquatic organisms and drinking
water should  be used. The values based on  consumption of fish alone should be
used only when human consumption of the surface water is not of concern. WQC
should be  used only when surface water is the medium of concern.  If aquatic life
exposure and human exposure are both of concern,  the more stringent  criterion
should be  used. Aquatic life criteria may be applied even if human exposure is not
of concern.   [Note:   In  states which  have adopted numerical Water Quality
Standards, or where numerical standards can  be calculated from non-numeric state
standards,  such standards may be used in lieu of EPA WQC or other available levels
on a constituent-specific basis.]

     Acute and  Subchronic Criteria --  These criteria address impacts on both
children and  adults,  and  are  presented in  Table 8-10.   These  criteria  are most
commonly applied for the  determination  of the  need for interim corrective
measures.  Their use is described in Section 8.8.

8.4.2      Use of Criterion Values

     As indicated previously, the criteria presented in Tables 8-5  through 8-10 are
subject to  change.  These  tables do not present action levels for all  of the 40  CFR
Part 261, Appendix VIII constituents. In addition, action levels for components of 40
CFR Part 264, Appendix IX that are not also on Appendix VIII,  but are normally
monitored for during  ground-water investigations, may also be applied. As existing
health  effects data are reviewed and more  information becomes available from
laboratory and epidemiological studies, these tables may  be expanded to include
additional  hazardous constituents, including those from Appendix IX.
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     Current  information on the health and environmental  effects  of  various
toxicants, including  information on RSOs and RfDs, and supporting toxicological
studies, may be obtained from review of the following document:

     U.S. EPA. Integrated Risk Information System (IRIS) Chemical Files. Office of
     Health and Environmental Assessment, Office of Research  and  Development.
     Washington, D.C. 20460.

     The Integrated Risk  Information System (IRIS), is a computerized library of
current information that is up-dated on a continuous basis.  It contains health risk
assessment  information on chemicals which have undergone a  detailed review of
toxicity data  by work groups composed of EPA.scientists from several  Agency
program offices, and represent EPA consensus.  IRIS may be accessed by the EPA
Regions, and  State and local governments through the EPA electronic mail system
(Dialcom) or through the Public Health Network of the Public Health Foundation
(contact the Network at (202) 898-5600 for details). IRIS is  also available to the
general public through the EPA electronic mail system (Dialcom-(202) 488-0550). In
addition, IRIS is also available on floppy diskettes in ASCII  format through the
National Technical Information Service (NTIS-(703) 487-4763).

     If EPA has not yet developed criteria for constituents which may be pertinent
to a particular release, there are various options  which  may be exercised by the
regulatory agency.  A literature  search may be  performed to locate any health
effects data which can be used to develop an interim criterion value or, at  least,
information such as type of health effect (e.g., carcinogenicity) which can be used to
make judgments.  The regulatory agency, for example, may obtain and review EPA
summaries  of health and   environmental effects  produced  for a  particular
constituent. These summaries include Health and Environmental Effects Profiles
(HEEPs), Health  Effects Assessment  (HEA) documents, and  other documents
produced by  EPA to summarize  health and environmental  effects for particular
constituents. These documents are collectively known as Health and Environmental
Effects Documents (HEEDs),  and  are available for many of the 40 CFR Part 261,
Appendix VIII constituents through EPA's RCRA Docket and library, located at EPA
Headquarters in Washington, D.C. A listing of all the HEEDs currently available is
                                   8-14

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contained in the following document, which is also available through EPA's RCRA
Docket and library:

     U.S. EPA, 1987.  Background Document. Resource Conservation and Recovery
     Act. Subtitle C -- Identification and Listing of Hazardous Waste. Appendix A --
     Health and Environmental  Effects Documents.    Office of Solid  Waste.
     Washington, D.C. 20460.

Additionally,  the HEA documents can be obtained from the National Technical
Information Service (NTIS). Table 8-3 presents a list of all chemicals for which HEAs
are currently available, and also identifies the NTIS ordering number.

     If little or no useful information regarding a particular constituent can  be
located, the initiation of a toxicity bioassay may be considered.  The Technical
Assessment Branch, Health Assessment Section of the Office of Solid Waste, located
in Washington, D.C, may be contacted for toxicological information  [(202)382-
4761)]. This office may also be contacted to determine whether a toxicity bioassay
for a particular constituent is planned or is in progress. Comparison  of background
concentrations (as action levels) to constituent concentrations in the release may be
made by the regulatory agency when health and environmental effects information
are not available.

     Note also that the criteria presented in Tables 8-5 through 8-10 do not address
all routes of exposure or forms of toxicity which may be of concern in particular
circumstances.. For example, dermal toxicity (absorption of toxicants through the
skin) may also be of concern in particular cases. Phytoxicity (toxicity to plants) and
other forms of environmental toxicity, such as terrestrial toxicity (toxicity to animals
and birds) may also be of concern.  Additional information regarding other routes
of exposure and forms of toxicity may be obtained from the following reference:

     U.S. EPA. October, 1986. Superfund Public Health Evaluation Manual. EPA
     540/1-68/060. NTIS PB87-183125.  OSWER  Directive No. 9285.4-1.  Office of
     Emergency and Remedial Response. Washington, D.C. 20460.

     Worksheet 8-1 in Section 8.10 may be used to present release characterization
data and to facilitate the comparison of constituent concentrations to health and
                                    8-15

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                         TABLE 8-3

     CHEMICAL AND CHEMICAL GROUPS HAVING EPA HEALTH
           EFFECTS ASSESSMENT (HEA) DOCUMENTS'
              CHEMICAL
NTIS2PB NUMBER
Acetone
Arsenic and Compounds
Asbestos
Barium and Compounds
Benzene
Benzo (a) pyrene
Cadmium and Compounds
Carbon Tetrachloride
Chlordane
Chlorobenzene
Chloroform
Chromium III and Compounds
Chromium VI and Compounds
Coal Tars
Copper and Compounds
Cresol
Cyanides
DOT
1,1 -Dichloroethane
1,2-Dichloroethane (DCE)
1,1 -Dichioroethylene
1,2-cis-Dichloroethylene
1,2-trans-Dichloroethylene
Dichloromethane
Ethylbtnzene
Glycol Ethers
Hexachlorobenzene
Hexachlorobutadiene
Hexachlorocydopentadiene
gamma-Hexachlorocyclohexane(Lindane)
Iron and Compounds
Lead and Compounds (Inorganic)
  86134277/AS
  86134319/AS
  86134608/AS
  86134327/AS
  86134483/AS
  8613433 5/AS
  86 134491 /AS
  86134509/AS
  86134343/AS
  86134517/AS
  86 134210/AS
  86134467/AS
  86134301/AS
  86 134350/AS
  86134368/AS
  86134616/AS
  86134228/AS
  86 134376/AS
  86134384/AS
  86134137/AS
  86134624/AS
  86134269/AS
  86 13452 5/AS
  86134392/AS
  86134194/AS
  86134632/AS
  86134285/AS
  86134640/AS
  86134129/AS
  86134673/AS
  86134657/AS
  86 134665/AS
                          8-16

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                    TABLE 8-3 (Continued)

      CHEMICAL AND CHEMICAL GROUPS HAVING EPA HEALTH
            EFFECTS ASSESSMENT (HEA) DOCUMENTS'
              CHEMICAL
NTIS2PB NUMBER
 Manganese and Compounds
 Mercury
 Methyl Ethyi Ketone
 Naphthalene
 Nickel and Compounds
 Pentachlorophenol
 Phenanthrene
 Phenol
 Polychlorinated Biphenyls(PCBs)
 Polynuciear Aromatic Hydrocarbons
 Pyrene
 Selenium and Compounds
 Sodium Cyanide
 SulfuricAcid
 2,3,7,8-TCDD (Dioxin)
 1,1,2,2-Tetrachloroethane
 Tetrachloroethylene
 Toluene
 1,1,1 -Trichloroethane
 1,1,2-Trichloroethane
 Trichloroethylene
 2,4,5-Trichlorophenol
 2,4,6-Trichlorophenol
 Vinyl Chloride
 Xylene
 Zinc and Compounds
 Complete Set of 58 HE As
  86 134681/AS
  86134533/AS
  86134145/AS
  86 1342 51/AS
  86134293/AS
  86134541/AS
  86 134400/AS
  86134186/AS
  86134152/AS
  86 134244/AS
  86134418/AS
  86134699/AS
  86134236/AS
  86134426/AS
  86134558/AS
  86134434/AS
  86 134202/AS
  86134442/AS
  86134160/AS
  86134566/AS
  86134574/AS
  86134459/AS
  86134582/AS
  86 134475/AS
  86134178/AS
  86134590/AS
  86134111/AS
i   As of the date of publication for this guidance document.
2   National Technical Information Service.
                            8-17

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environmental criteria.  Additional worksheets are provided for evaluating hazards
posed by mixtures of constituents.  Evaluation of chemical mixtures is discussed in
the following section.

8.5       Evaluation of Chemical Mixtures

     There are several  situations when  the overall potential for adverse effects
posed by  multiple constituents may be assessed.  For example, if no individual
constituent exceeds  its action  level in a given  medium,  but there are many
constituents present  in  the  medium, the overall (additive) health  risk may be
assessed to determine whether a  CMS may be  required.   In other  cases, an
evaluation of the health risk posed by a mixture of constituents may be used in
assessing the need for interim measures, particularly where exposure is actually
occurring. The Guidelines for the Health Risk Assessment of Chemical Mixtures (U.S.
EPA, 1986) describe the recommended  approach to be used in evaluating the
chronic effects of exposure to a chemical mixture.  According to the guidelines, a
mixture is defined as "any concentration of two or more chemicals  regardless of
source or of spatial or temporal proximity/ Under these guidelines, additivity of
effects for carcinogens can be assumed. The guidelines also allow for additivity of
systemically toxic constituents which cause similar systemic effects. Carcinogens and
systemic toxicants must be evaluated separately.  When  evaluating mixtures of
systemic  toxicants,  constituents should be  grouped  by  the same  mode of
toxicological action (i.e., those which induce the same toxicological endpoint, such
as liver toxicity).

     The overall risk posed by a mixture of constituents is evaluated through the
use of a Hazard Index (HI) that is generated for each health endpoint. For systemic
toxicants, the hazard index (Hlj) takes the form:

                   n    EJ
          Hit   »   E    -                                     (Equation 8-3)
                   i»1 ALj
where
          n     a   total number of toxicants;
          E;    »   exposure level of the ith toxicant; and
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          ALj   =   maximum acceptable level for the ith toxicant.

The hazard index for carcinogens (H!c) is similar;
          Hlc   *   n    Ej
                   £    -                                     (Equation 8-4)
                   i s 1 DRj
where
          n    =   total number of carcinogens;
          Ej    s   exposure level to the jth carcinogen; and
          DRj   =   dose at a set level of risk for the jth carcinogen.

     If any calculated hazard  index exceeds unity  (i.e., one), then the need  for
interim corrective measures and/or a CMS may be assessed.

     The use of the hazard index in the evaluation of chemical mixtures is described
below for an example  case in which three carcinogens were measured within a
contaminant release.   Trichloroethylene  and carbon  tetrachloride levels in the
ground water were measured at 2 and 1 ug/l, respectively. A breakdown product of
carbon tetrachloride, chloroform, was also measured at a level of 3 ug/l.  None of
these concentrations exceed the individual criteria presented in Tables 8-5 through
8-10.  (The MCL for both trichloroethylene and carbon tetrachloride is 5.0 yg/l, and
the carcinogenic criteria for chloroform is 5.7 ug/l.) However, the hazard Index (Hlc)
for these three chemicals exceeds unity.  Rewriting  Equation (8-4) in terms of the
measured concentration (Ej) and the criterion concentrations (DRj) shown in Tables
8-5 through 8-10 gives:
          Hlc   »   Ej/DRi + E2/DR2

          Hlc   »   2 uQ/l  +  1 UQ/I  +  3 uQ/l
                   5.0 ug/l  5.0 ug/l    5.7 ug/l
          Hlc   =   0.4 + 0.2 + 0.53
          Hlc   a   1.13

     Thus, in this situation, the need for interim corrective measures and/or a CMS
may be assessed.
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     Contaminant additivity is possible both within a medium and across media.
When appropriate, the regulatory agency may use the hazard index approach for
multiple  contaminants within  a given  medium  to help determine the  need for
interim corrective measures and/or a CMS.  Similarly, contaminant additivity may be
applied across media,  especially when site-specific factors indicate a likelihood of
chronic  exposure to  constituents from  multiple media.   Information on  the
toxicological effects of individual systemic toxicants may be found in the HEEDs, and
the IRIS data base, referenced earlier.

     Worksheet  8-2 (Section 8.10) provides a format that the regulatory agency
may  use to assess the toxic effects of chemical mixtures based on the hazard index.
An example case  worksheet is also presented.

8.6       Evaluating Deep Soil and Sediment Contamination and Use of Statistical
          Procedures for Evaluating Ground-Water Contamination

     As  indicated previously, determining  whether  deep  soil and  sediment
contamination warrants consideration of interim corrective measures and/or a CMS
may  involve the application of specific exposure  assumptions and consideration of
other factors. Guidance regarding these topics is presented in Subsections 8.6.1 and
8.6.2. This guidance may be revised in  future editions of this document as a result of
ongoing  EPA studies.   Subsection  8.6.3  presents  a  discussion  on  statistical
procedures that may be used for evaluating ground-water contamination.

8.6.1      Deep and Surficial Soil Contamination

     As described in  the  Soil Section  of this Guidance (Section 9), releases of
hazardous waste or constituents to  soil  can be  described as surficial  or deep.
Surficial soil is generally described as the top 2 feet of soil; in site-specific conditions,
it  may extend to 12 feet  Land use that involves  housing  developments  is an
example of when the surficial soil depth may extend to 12 feet, because foundation
excavation may result in deep contaminated soils being moved to the surface.

     Because of the potential for inter-media  transport of contamination, the
potential routes for exposure to  surficial soil contaminants are soil, air, surface
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water, and ground water. While air, surface water, and ground-water routes are all
important, the most relevant and major route of exposure is through direct contact
with and/or ingestion of soil.

     Surficial soils may be contaminated with organics, inorganics, organometals,
or a combination of these. At high concentrations, some contaminants will cause at
least irritation at the point of skin  contact. For many contaminants, however,
toxicity  occurs after they pass through certain  barriers (e.g., the wall of the
gastrointestinal tract or the skin itself), and enter blood or lymph, and gain access to
various organs or systems of the body. Generally, because of the chemical forms in
which metals are usually found in soils (e.g., salts, ligand, and chelate complexes),
the concern is with their ingestion rather than with dermal contact.

     Surficial soil contaminated with lead and/or cadmium presents a unique health
risk to children because of the possible ingestion of contaminated soil through their
normal exploratory behavior, coupled in some instances with pica, and because of
the cumulative nature of lead and cadmium poisoning.

     Currently, there is no verified Reference Dose (RfD) or Risk Specific Dose (RSD)
for lead. The Carcinogen Assessment Group (CAG) of ORD is evaluating lead as a
potential human carcinogen via the oral route of exposure and is currently working
on estimating a Carcinogenic Slope Factor (CSF) for lead based on current toxicity
studies.  The  Agency is  also attempting  to develop a RfD for lead based on  new
toxicological  data  on  the  non-carcinogenic,  neuro-behaviora!  effects of  lead
exposure. It is not likely, however, that either the RfD or the RSD will be developed
and approved soon.

     Another metal of concern is cadmium.  Although the Agency has not formally
approved an RfD for cadmium, a value of 0.0005 mg/kg/day will likely be approved
as an RFD. This value would translate to an acceptable soil level of 9 mg/kg.

     Toxicological information on lead and cadmium  are undergoing extensive
Agency  review, and decisions on  relevant health-based standards  are currently
being made. The Integrated Risk Information System (IRIS) chemical files should be
searched periodically for updated material concerning lead and cadmium.
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     The criteria discussed in Section 8.4 that apply to soil (and shown in Tables 8-6
and 8-7 in Section 8.10) pertain to ingestion of surficial soils. Because ingestion of
deep soils may not be a likely exposure scenario, different evaluation methods may
be used for deep soils, as described below.

     In making the determination of whether interim corrective measures and/or a
CMS should be considered for deep contaminated soils, the regulatory agency may
evaluate the  potential for  the contamination within deep soils to contaminate
underlying ground water.   If the potential exists for contaminated deep soils to
release hazardous constituents to ground  water, such that the criteria levels for
ground water discussed in Section 8.4 may be exceeded, interim corrective measures
and/or a CMS will  be considered.  This applies not only to situations where ground
water has not yet  been impacted  by deep soil contamination, but also to situations
where deep contaminated soils are acting as a continuous source of contamination
to already contaminated ground water. In addition, the regulatory agency may
apply this evaluation to surficial soils,  particularly in cases where the soil ingestion
criteria (Section 8.4) are not  exceeded and where the surficial soil may pose a future
or continuing threat to ground water.

     In order to determine whether contaminated soils pose a future or continuing
threat to ground water, leaching tests and/or other evaluation procedures may be
performed on representative samples of contaminated soils following the guidance
presented in  Section  9.4.4.3.  If the concentration  of constituents  of concern
measured in leachate resulting from leaching tests and/or other procedures exceeds
the applicable criteria for ground water discussed in Section 8.4, interim corrective
measures  and/or  a CMS   may  be necessary,  unless  the owner or  operator
demonstrates  (following  the  guidance  presented  in   Section  9.4.4.3)  that
attenuation and other mechanisms will  reduce these concentrations to acceptable
levels prior to entry into the  ground water.

     Case Study  No.  16 in Volume IV  (Case Study  Examples)  illustrates  the
application of leaching tests and the evaluation of other site-specific information to
determine whether contaminated soil poses a threat to ground water.
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8.6.2      Sediment Contamination

     As with deep contaminated soils, direct human exposure to contaminated
sediments underlying surface waters is unlikely.  However, such sediments may pose
risks to both the surface water  ecosystem  and humans due to toxicity and/or
bioaccumulation and biomagnification through the food chain.  The regulatory
agency may therefore assess the potential for contaminated sediments underlying
surface water to act as a continuing or future source of contamination to the water
column, to aquatic life that may be present in the surface water, and consequently
to humans who may ingest the surface water  and/or the aquatic life within  the
surf ace water.

     Section  13,  in addressing  releases to surface water,  recommends that,
whenever metal species or organic constituents having bioaccumulative potential
are known  to be  present  in bottom  sediments (or  in the water  column),
biomonitoring (e.g., sampling and analysis of  aquatic species) be conducted. If
potentially bioaccumulative organic or inorganic contaminants (as discussed in
Section  13) are measured in  the aquatic species of interest,  interim corrective
measures and/or a CMS may be necessary.

     If other hazardous constituents (e.g.,  those  which are not known  to be
potentially bioaccumulative)  are  measured  in  the  sediment  that  can  be
subsequently released  from  the sediment into the surface-water column  at
concentrations above the applicable criteria  discussed in Section  8.4, interim
corrective measures and/or a CMS may also be required by the regulatory agency.

     However, the owner or operator  may attempt to show that constituents
within the sediment have not bioaccumulated or will  not bioaccumulate. The
owner or operator may also attempt to show, through use of static or flow-through
testing (i.e., analysis of water or aquatic species following a period of contact with
the contaminated sediment)  or through the  use  of chemical stability/solubility
information, that sediment contaminants will not be released to the water column
in concentrations that would exceed the applicable criteria discussed in Section 8.4.

     It should also be noted that EPA is working to establish numerical sediment
quality criteria that can  be applied on a site-specific basis, depending primarily on
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the physical/chemical characteristics of the sediment (e.g., sediment organic carbon
content).  The approach being investigated to assessing sediment contamination
examines  the correspondence between  sediment contaminant  concentration,
laboratory  bioassay, and in situ assessments of biomass and  species diversity.
Although these criteria are still in the development/validation process, when issued,
they may be applied in the case of sediment contamination to determine whether
interim corrective measures and/or a CMS may  be necessary.   Contact the  EPA
Criteria and Standards Division for additional information at (202) 475-7301.

8.6.3     Use  of  Statistical   Procedures  For   Evaluating   Ground-Water
         Contamination

     On October 11, 1988, EPA promulgated the final rule for Statistical Methods
for Evaluating Ground-Water Monitoring Data From Hazardous Waste Facilities (53
FR 39720).  This rule, part of 40 CFR Part 264, Subpart F, requires ground-water
monitoring at permitted hazardous waste land disposal facilities to detect ground-
water contamination. This rule amends the requirement  that the  Cochran's
Approximation to the Behrens Fisher Student's t-test (CABF), be applied to ground-
water monitoring data to determine whether there is a statistically  significant
exceedance of background or other allowable concentration levels of specified
chemical parameters. Concerns with the CABF procedure were  brought to EPA's
attention, and after a review of comments on the procedure, EPA promulgated 5
different statistical methods that are more appropriate for the analysis of ground-
water monitoring data.  These 5 methods are 1) Parametric analysis-of-variance,
2) Analysis-of-variance based on ranks, 3) Tolerance intervals, 4) Prediction intervals,
and 5) Control charts.

     Analysis-of-variance models are used to analyze the effects of an independent
variable on a dependent variable. For ground-water monitoring data, a well or
group of wells is the  independent variable, and the aqueous concentration of
certain constituents or of a specified contaminant or contaminants is the dependent
variable.  An analysis-of-variance can determine whether observed variations in
aqueous concentrations between different wells or groups of wells are statistically
significant. Use of analysis-of-variance models is appropriate in situations where
background concentrations for the specific constituent can be determined.
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     Tolerance intervals define, with a specified probability, a range of values that
contain a discrete percentage of the sample  population.  With ground-water
monitoring data, tolerance intervals can be constructed with concentrations from
the background well(s); these intervals are then expressed as an interval centered at
the mean background well concentration.  Possible ground-water contamination is
indicated when concentrations of the specified constituent(s)  at  the compliance
wefl(s) plot outside of the tolerance interval limits.

     Prediction  intervals are intervals in which the user is confident at a specified
percentage that the next observation will lie within the interval, and are based on
the number of previous observations, the number of new measurement to be made,
and the level of confidence that the user wishes to obtain. This method of statistical
analysis can be used in both detection and compliance monitoring programs. It is
useful  in a detection monitoring program when constituent concentrations from
individual compliance wells are compared  to one or more  background wells. The
mean concentration and standard deviation are estimated from the background
well sample.   In a  compliance monitoring  program, prediction  intervals  are
constructed  from compliance well concentrations  beginning  when the fad I it"
entered the compliance monitoring program. Each compliance well observation is
tested to determine if it lies within the prediction interval, and  if it is greater than
the historical prediction limits, quality has deteriorated to such a point that further
action may be warranted.

     Control charts are based on repeated random sampling done over various time
intervals from the population distribution  of a given variable.  Different statistical
measurements,  such as the  mean of replicate values  at a point in time,  are
computed and plotted together with upper and/or lower predetermined limits on a
chart whose  x-axis represents time.  When  a data point plots outside  these
boundaries, the process is "out of control", and when it plots within the boundaries
the process is "in control".   Control charts can be  used to analyze the inherent
statistical variation of ground-water monitoring data and  to note aberrations.
Further investigation of out of control points is necessary before taking any direct
action.  Control charts are also  used to evaluate ground-water monitoring data
when these data are adjusted and/or transformed as necessary.  A control chart can
be constructed for each constituent in each well to monitor the concentration of
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that constituent over time.  New samples can be compared to the historical data
from the well to determine if the well is in or out of control.

     The October 11, 1988 final rule (53 FR 39720) should be reviewed for further
information. In particular, the rule provides a glossary of some of the terminology
commonly used in the field of statistics, which may be particularly helpful. The EPA
Office  of Solid  Waste  Land  Disposal   Branch  may  be  contacted for further
information at (202) 382-4658.

8.7      Qualitative Assessment and Criteria

     Qualitative criteria may also be used to assess the need for interim corrective
measures and/or a CMS.  Qualitative criteria for interim corrective measures are
discussed in Section 8.8. Qualitative criteria for assessing the need for conducting a
CMS are discussed below.

     The regulatory agency may require that a  CMS be performed even though
quantitative criteria (See Section 8.4) have not been exceeded. Circumstances under
which such actions may be appropriate include the following:

     •   Presence of sensitive ecosystems or endangered species;

     •   Data indicating that release concentrations may be increasing over time;

     •   Information  indicating  that  other  contaminant sources  may   be
         contributing to overall adverse exposure;

     •   Information indicating that exposure routes other than those addressed
         by quantitative criteria  (e.g., dermal contact  and phytotoxicity)  are
         important; and

     •   Additional exposure as a result of normal use of a contaminated medium
         (e.g., use of contaminated ground water or surface water for drinking as
         well as for washing, cooking, showering, watering the lawn, etc.).
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     The above list of circumstances is not exhaustive. The regulatory agency may
identify other factors on a case-specific basis.

8.8       Interim Corrective Measures

     If interim  corrective measures are determined  to be  necessary,  population
exposure should be prevented or minimized to the extent necessary and further
release  migration should also be prevented or minimized.   The  process  of
determining whether interim corrective measures  should be  taken,  and the
selection and implementation of such measures, is similar to removal actions that
may be taken under CERCLA  (Superfund).   In many cases, such action may  be
relatively simple (e.g., removal of drums from the land surface with proper storage
or disposal), while in other cases more extensive action may be necessary.

     In  evaluating whether interim corrective measures may be  necessary, the
regulatory agency will review pertinent information about the source and  nature of
the release or potential threat of release. The regulatory agency will apply scientific
judgment in evaluating the potential threat to human health or the environment.
The decision to  apply interim corrective measures will be made in consideration of
the immediacy and magnitude of the potential threat, the  nature of appropriate
corrective action,  and the implications of deferring corrective measures  until the
RFI/CMS is completed. The following factors will be considered in determining the
need for interim corrective measures:

     •    Actual or potential exposure of nearby human populations or animals to
          hazardous wastes or constituents;

     •    Actual or potential contamination of drinking water supplies or sensitive
          ecosystems;

     •    Presence of hazardous wastes or constituents in drums, barrels, tanks, or
          other bulk storage containers that may pose a threat of release;

     •    Presence of high concentrations of hazardous wastes or constituents in
          soils largely at or near the surface that may migrate readily to receptors,
          or to  which the public may be inadvertently or unknowingly exposed;
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     •   Weather conditions that may cause hazardous wastes or constituents to
         migrate or be released;

     •   Threat of fire or explosion; and

     •   Other situations or factors that may pose actual or imminent threats to
         human health orthe environment.

     Exceedance of any of the criteria discussed in Section 8.4 does not necessarily
mean that interim corrective measures will be required.  Although the regulatory
agency should be notified  if health and environmental criteria are exceeded, the
overall circumstances will be considered by the regulatory agency in determining
whether interim corrective measures should be applied.  Notwithstanding this
process, the owner or operator has a continuing responsibility to identify and
respond to emergency situations and to define priority situations that may warrant
interim  corrective measures.  For such situations, the owner  or  operator should
follow the  RCRA  Facility Contingency Plan as required under 40 CFR Part 264,
Subpart D and Part 265, Sub part D.

     It should also be noted that the regulatory agency may apply health criteria
based on acute or subchronic effects, to the determination of the need for interim
corrective measures. For example, the EPA Office of Drinking Water has developed
drinking water health advisories for a number of compounds, which address acute
(1 day) and subchronic (10 day) exposures for both children and adults. A list of the
currently available drinking water health  advisories is provided in Table 8-10.
Health advisory numbers may be periodically revised and can be found in IRIS.  For
further information on health advisory numbers, call the EPA Office of Drinking
Water Hotlint at (202) 382-5533 or 1 -800-426-4791.

     The regulatory agency will base the decision on the need  to apply interim
corrective measures on a determination of the type and magnitude of the potential
hazard and an evaluation of the likelihood and effects of actual or potential human
or environmental exposures.  For example, in  the hypothetical  case depicted in
Figure 8-1,  initial measurements at the indicated sampling  locations identified
constituent  concentrations in  excess  of   health and  environmental criteria.
                                   8-28

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Accordingly, the owner or operator notified the regulatory agency immediately.
The circumstances indicated that human population would be exposed to release
constituents  before  definitive corrective  measures  could   be  selected  and
implemented.  Therefore, immediate steps to address the hazard were required of
the owner  or operator.   Examples of  specific interim corrective measures are
provided in Table 8-4.  For additional information see RCRA Corrective Action
Interim Measures (U.S. EPA, 1987).

     To determine whether an actual or potential threat to human health or the
environment requires interim  corrective  measures, the regulatory  agency will
consider such  factors- as receptor locations,  and  rate  and  extent  of release
migration.  Worksheet No. 3 in Section 8.10.2 presents a list of questions that the
regulatory agency may consider in making a determination.

     The decision to apply interim corrective measures may involve estimates of the
rate of release migration and an assessment of potential human or environmental
receptors.  Estimates of the rate of release migration will generally be based on
simple calculations, analytical models, or well-understood numerical models. For
example, the rate of contaminant migration in ground water is likely to be based on
time of travel (TOT)  calculations  or other simple methods for  estimating  rate.
Additional   information  on  determining  media-specific  migration  and  the
characterization of exposed  populations is provided in the Superfund Public Health
Evaluation  Manual (U.S. EPA, 1986) and the Draft Superfund Exposure Assessment
Manual (U.S. EPA, 1987).  In addition, information describing data  requirements for
exposure related measurements is  expected to be published by the EPA Office of
Research and Development  Exposure Assessment Group in the  Federal Register in
late 1988 or early 1989.

     As discussed above, the determination of the type and  magnitude  of the
potential hazard posed by  most contaminant releases will be accomplished as part
of the  assessment, including the  comparison  of  projected or  actual exposure
concentrations to the health and environmental criteria,  as described in Section 8.4.
However, the evaluation of subsurface releases of methane gas may pose a direct
explosion hazard as a result of a concentration build-up (e.g., in building structures).
Explosions  of methane gas can occur at the Lower Explosive Limit (LEL) in the
presence of a heat source (e.g., a spark).  EPA has promulgated criteria for explosive
                                   8-29

-------
                                    TABLE 8-4
                 EXAMPLES OF INTERIM CORRECTIVE MEASURES
SOILS
•  Sampling/Analysis/Disposal
•  Run-off/Run-on Control (Diversion or
   Collection Devices)
•  Temporary Cap/Cover
CONTAINERS
   Overpack/Re-drum
   Construct Storage Area/Move to Storage
   Area
   Segregation
   Sampling and Analysis
   Treatment, Storage and/or Disposal
   Temporary Cover
GROUND WATER
   Delineation/Verification of Gross
   Contamination
   Sampling and Analysis
   Interceptor Trench/Sump/Subsurface Drain
   Pump and Treat
   In-situ Treatment
   Temporary Cap/Cover
TANKS
•  Overflow/Secondary Containment
e  Leak Detection/Repair/Partial or Complete
   Removal
SURFACE WATER RELEASE (Point and Non-
Point)
   Overflow/Underflow Dams
   Filter Fences
   Run-off/run-on Control (Diversion or
   Collection Devices)
   Regrad i ng/Re vegetati on
   Sample and Analyze Surface Waters and
   Sediments or Point Source Discharges
SURFACE IMPOUNDMENTS
   Reduce Head
   Remove Fret Liquids and or Highly Mobile
   Wastes
   Stabilize/Repair Side Walls, Dikes or Liner(s)
   Provide Temporary Cover
   Run-off/Run-on Control (Diversion of
   Collection Devices)
   Sample and Analysis to Document the.
   Concentration of Constituents Left in Place
   When a Surface Impoundment Handling
   Characteristic Wastes is Clean Closed
   Interim Ground-water Measures (See
   Ground-water Section)
GAS MIGRATION CONTROL
•   Barriers/Collection/Treatment/Monitoring
•   Evacuation (Buildings)
LANDFILL
•   Run-off/Run-on Control (Diversion or
    Collection Devices)
•   Reduce Head on Li ner and/or i n Leachate
    Collection System
•   Inspect Leachate Collection/Removal
    System or French Drain
•   Repair Leachate Collection/Removal System
    or French Drain
•   Temporary Cap
•   Waste Removal (See Soils Section)
•   Interim Ground-water Measures (See
    Ground-water Section)
                                        8-30

-------
                              TABLE 8-4 (continued)

                 EXAMPLES OF INTERIM CORRECTIVE MEASURES
PARTICULATE EMISSIONS
•  Truck Wash (Decontamination Unit)
•  Re-vegetation
   Application of Oust Suppressant
WASTE PILE
•  Run-off/Run-on Control (Diversion to
   Collection Devices)
•  Temporary Cover
•  Waste Removal (See Soils Section)
•  Interim Ground-Water Measures (See
   Ground-water Section)
OTHER TYPES OF ACTIONS
•  Fenci ng to Prevent Di rect Contact
e  Extend Contamination Studies to Off-site
   Areas if Permission is Obtained as Required
   Under Section §3004(v)
e  Alternate Water Supply to Replace
   Contaminated Drinking Water
e  Temporary Relocation of Exposed
   Population
e  Temporary or Permanent Injunction
•  Suspend or Revoke Author!zation to
   Operate Under Interim Status
                                       8-31

-------
gases under the RCRA, Subtitle D program in 40 CFR Part 257.3. These criteria state
that the concentration of explosive gases generated by the facility shall not exceed:
(1) 25 percent of the lower explosive limit (LEL) for the gases in facility structures,
and (2) the lower explosive limit for the gases at the property boundary.  Where
these criteria are being approached or exceeded, interim corrective measures for
gas migration will generally be necessary.

8.9       References

U.S. EPA. 1986.  Super-fund Public Health Evaluation Manual.  EPA/540-1-86-060.
     NTIS PB87-183125. OSWER Directive No. 9285.4-1. Office of Emergency and
     Remedial Response. Washington, D.C. 20460.

U.S. EPA. September 24,1986. Guidelines for Carcinogen Risk Assessment. Federal
     Register51(185):33992-34003.

U.S. EPA. September 24,1986. Guidelines for the Health Risk Assessment of
     Chemical Mixtures. Federal Register 51(185):34014-34025.

U.S. EPA. 1986. Test Methods for Evaluating Solid Wastes. EPA/SW-846.
     GPO No. 955-001-00000.1.  Office of Solid Waste. Washington, D.C. 24060.

U.S. EPA. 1986. Suoerfund Exposure Assessment Manual. Draft. Office of
     Emergency and Remedial Response. Washington, D.C. 20460.

U.S. EPA. 1987.  Data Quality Objectives for Remedial Response Activities: Volume 1
     - Development Process. Volume 2:  Example Scenario.  EPA  540/G-87/003a.
     OSWER Directive No. 9335.0-7B. Office of Emergency and Remedial Response
     and Offict of Waste Programs Enforcement. Washington, D.C. 20460.

U.S. EPA. 1987. Integrated Risk Information System (IRIS) Chemical Files. EPA/600/8-
     86/032b.  Office of Health and Environmental Assessment, Office of Research
     and Development. Washington, D.C. 20460.
                                   8-32

-------
U.S. EPA. 1987. Background Document. Resource Conservation and Recovery Act.
     Subtitle C-ldentification and Listing of Hazardous Waste. Appendix A-Health
     and Environmental Effects Documents.  Office of Solid Waste.  Washington,
     D.C. 20460.

U-.S. EPA. 1987. RCRA Corrective Action Interim Measures.  Officeof Solid Waste.
     Washington, D.C. 20460.

8.10      Criteria Tables and Worksheets

     This section presents both the health and environmental assessment criteria
tables and worksheets that the regulatory agency may use in conducting the health
and environmental assessment.

8.10.1    Criteria Tables

     The following are the  health and  environmental assessment criteria tables
discussed in Section 8.4 and 8.8. Table  8-5 presents the Maximum Contaminant
Levels (MCLs) promulgated under the Safe Drinking Water Act. Table 8-6 presents
human health-based criteria for carcinogens (based on Risk-Specific Doses or RSDs).
       •
Table 8-7 presents human health-based  criteria for systemic toxicants (based on
Reference Doses or RfDs). Table 8-8 presents a summary of the EPA Water Quality
Criteria developed under the  Clean  Water Act.   Table  8-8  identifies individual
constituents as well as groups of constituents (e.g., chlorinated benzenes). Table 8-
9 presents a list of all the individual constituents contained in the chemical groups
identified  in Table 8-8.  Table 8-10 presents drinking  water health advisories
developed by EPA's Office of Drinking Water.
                                   8-33

-------
                         Table 8-5

MAXIMUM CONTAMINANT LEVELS (MCLs) PROMULGATED UNDER THE
                 SAFE DRINKING WATER ACT*
Chemical
Arsenic
Barium
Benzene
Cadmium
Carbon tetrachloride
Chromium (hexavalent)
2,4-Dichlorophenoxy acetic acid
1 ,4-Dichlorobenzene
1,2-Dichloroethane
1 , 1 -Dichloroethylene
Endrin
Fluoride
Lindane
Lead
Mercury
Methoxychlor
Nitrate
Selenium
Silver
Toxaphene
1,1,1 -Trichloroethane
Trichloroethylene
2,4,5-Trichlorophenoxy acetic acid
Vinyl chloride
CAS No.
7440-38-2
7440-39-3
71-343-2
7440-43-9
56-23-5
7440-47-3
94-75-7
T06-46-7
107-06-2
75-35-4
72-20-8
—
58-89-9
7439-92-1
7439-97-6
72-43-5
-
7782-49-2
7440-22-4
8001-35-2
71-55-6
79-01-6
93-76-5
75-01-4
MCL (mg/l)
0.05
1.0
0.005
0.01
0.005
0.05
0.1
0.075
0.005
0.007
0.0002
4
0.004
0.05
0.002
0.1
10
0.01
0.05
0.005
0.2
0.005
0.01
0.002
 These criteria are subject to change and will be confirmed by the
 regulatory agency prior to use.
                           8-34

-------
               Table 8-6.  Health-Based Criteria for Carcinogens1
Constituent
Acrylamide4
Acrylonitnle
Aldnn
Aniline4
Arsenic4
8enz(a)anthracenr*
Benztnt4
Senzidme
Benzo(a)pyrene4
Beryllium4
Bu(2-chloroethyl)
ether
9iS(chloromethyl)
ether (8CME)4
8u(2-ethylhexyl)
phthalate
Cadmium
Carbon tetrachlonde
Chlordane
1-Chloro-2.3-
epoxypropane
(Epichlorohydnn)
Chloroform
Chloromethyl
methyl ether4
(CMME)
Chromium
(hexavalent)
000
OOE
DOT
Oibenz(a.h)
anthracene4
1.2-Dibromo-3-
chloropropane4
(08CP)
CAS
No.
79-06-1
107-13-1
309-00-2
62-S3-3
7440-38-2
56-55-3
71-43-2
92-87-5
50-32-8
7440-41-7
111-44-4
542-88-1
117-81-7
7440-43-9
56-23-5
57-74-9
106-89-8
67-66-3
107-30-2
7440-47-3
72-54-8
72-55-9
50-29-3
53-70-3
96-12-8
Class
(A.8.C)'
8
3
3
C
A
8
A
A
8
a
3
A
8
8
3
a
3
8
A
A
a
a
8
8
3
Oral Exposure Route *SD*
CSF
(mg/kg/day)-'
385E+00
54E-01
1.7E + 01
2.6E-02
-
3.12E + 00
2.9E-02
2.3E+02
1.15E«-01
4.90*00
1 1EfOO
9.45E+00
8.4E-03
--
1 3E-01
1.3E+00
99E-03
6.1E-03
9.45E + 00
—
2.4E-01
3.4E-01
3.4E-01
490E+01
2.21E + 01
Soil
(mg/kg)
1 82E-01
1.30E+00
41E-02
2.76*02
-
2.24E-01
2.46*01
30E-03
6.09E-02
1 43H-01
6.4E-01
7.41E-02
8.3Ef01
~
54E+00
54£^)1
71E*01
1 IE. 02
7.41 E-02
~
2.9E*00
2.1 E* 00
2.1E+00
1.43E-02
3.17E-02
Water
(vg/D
9 09E-03
6 SE-02
2.1E-03
1 3E+01
See MCL
1.12E-02
See MCL
1 SE-04
3.04E-03
7 14E-03
32E-02
3.70E-03
42E+00
Se" MCL
See MCL
27E-02
3.SE.OO
5.7E*00
3.70E-03
See MCL
1 5E-01
10E-01
10E-01
7.14E-04
1.S8E-03
inhalation Exposure ^oute
RSD^
CSP
(mg/kg/day)-'
385E.OO
24E-01
1 7E*01
2.S9E-02
1 51E+01
3.12EfOO
2.9E-02
2.3E+02
1.15E*01
840E*00
1 1E*00
94SE+00
••
7 8E * 00
1 3E-01
1 3E+00
4 8E-03
8 1E-02
945E+00
4.1E*01
-
—
34E-01
490E*01
2.21E*01
Air
(yg/mO
909E-04
1 5E-02
2 1E-04
1 3SE.OO
2 32E-04
1 12E-03
1 2E-01
1 5E-05
3 04E-04
4 17E-04
32E-03
3.70E-04
•*
45E-04
2 -^E-02
2 7E-03
73E-01
4 3E-02
3 70E-04
8SE-05
--
-
1 OE-02
7 14E-05
1 58E-04
Note:  These criteria are subject to change and will be confirmed by the regulatory agency
      prior to use.
                                      8-35

-------
                            Table 8-6.  (continued)i
Constituent
1,2-0'bromoetnane
DibutyimtroJainint
1.2-Oicnioroetriane
1.1-Oicnloroetnyiene
Dichlorometnane
(Methyienecpionde)
1 ,3-Dicnlorooropene
Dieldrin
Oietnyimtrojamme
Oietnyistiibcstroi4
(D6S)
2.4-Oinitrotolu«ne
1,4-DiOxane
1,2-
Diphenyihydrazine
Ethyiene oxide*
Heotacnior
Heptacnior epoxide
Hexacniorooenzene4
Hexachioroouta-
diene
Mexacnioroaibenzo-
p-dioxm
Hexachloroetnane
Hydrazme
Hydrazmesuifate
Undane (gamma -
Hexacnlorocyclo-
hexane)4
3-Metnyl -
cholanthrene*
4.4-Metnyien«-bu-{2-
crtloroaniime)4
Nickel*
Nickel (refinery aust)
CAS
No.
106-93-4
924-: 6-3
107-06-2
75-35-4
75-09-2
542-75-6
60-57-1
55-18-5
56-53-1
121-14-2
'23-91-1
122-66-7
75-21-8
76-44-8
'024-57-3
118-74-1
87-68-3
19408-74-3
67-72-1
302-01-2
10034-93-2
58-89-9
56-49-5
101-14-4
•440-02-0
7440-02-0
n««t>
;A. 9. C}'
3
3
9
C
3
3
8
3
A
3
3
3
3
8
a
9
c
8
C
3
3
C
8
9
A
A
Oral Exposure Route R5Dj
CSF
(mg/kg/day)-'
•-
540E»00
9 16-02
606-01
7 SS-03
1 86-01
1 6E*01
1 5E*02
490E*02
3 08E-01
4 906-03
8.0E-01
3 506-01
45E*00
916*00
1 726*00
736-02
626*03
1 46-02
306*00
306*00
1 36*00
9456*00
1 656-01
-
--
Soil
(mg/kg)
-
i 30E-01
77E*00
1 2E*01
936*01
39E-00
446-02
46£-03
i 436-03
2276*00
1 43E*02
8.86-01
2.006*00
166-01
776-02
4076-01
9.06*01
1 1E-04
5.06*02
236-01
2.36-01
5.46*00
741E-02
4246*00
»»
•-

Water
(ug/D
-
6 48E-03
See MCI
See MCI
47E*00
' 9E-01
2 2E-03
23E-04
7 ?4£-05
1 '46-01
7 146*00
44E-02
1 OOE-01
7 86-03
3 86-03
2.03E-02
45E«00
566-06
2.5E*Oi
1 26-02
i 2E-02
See MCI
3.706-03
2.12E-01
-
--
nnaiation Exoosure Soute
sso^

CSP
(mg/kg/day)-'
76E-01
540E.OO
91E-02
' 2£«00
1 4E-02
•-
• 6E*01
1 5E-02
490£*02
«
i 90E-03
8.0E-01
3 50E-01
456*00
9 t E « 00
' 72E-02
7 8E-02
62E*03
1 46-02
1 02E*01
--
1 36*00
945E*00
: 65E-01
8.40E-01
34E-01

A,r
fUg/mJ)
468-03
6 48E-04
3 8E-02
29E-02
2 SE-01
--
22E-04
23E-05
7 14E-06
le-oi
7 '4E-01
44E-03
' OOE-02
7 SE-04
3 3E-04
203E-01
45E-01
5 6E-07
2 5E-00
3 43E-04
-
2 7E-02
3 70E-04
2.12E-02
4:75-03
42E-03
Note:      Th«s« criteria are subject to change and will be confirmed by the regulatory agency
          prior to use.
                                      8-36

-------
                             Table 8-6.  (continued)i
Constituent
Nickel subsulfide
2-Nitropropane4
N-Nitro$odi-
ethanolamme
N-NitroiOdimethyl -
amme (Dimethyl-
mtrosamine)
N-Nitrosodi-N-
propylamine
N-Nitroso-N-
metnylethylamme
N-Nitroso-N-methyl
urea4
N-Nitroso-
pyrro/idme
PC8's
Pentachloronitro-
benzene4
Perchloroetnylene
(Tetrachloro-
ethylene)
Pronamide(Kerb)4
Reserpme4
Styrene
1,1.2.2-
Tetrachloroethane
Thiourea4
Toxaphene
1,1,2-
Tnchloroethane;
Tnchloroetny!e>nt
2.4,6-
Tnchlorophenol
CAS
NO.
12035-72-2
79-46-9
1 1 1 6-54-7
62-75-9
621-64-7
10595-95-6
684-93-5
930-55-2
1336-36-2
82-68-8
127-18-4
23950-58-5
50-55-5
100-42-5
79-34-5
62-56-6
8001-35-2
79-00-5
79-01-6
88-06-2
Class
(A, 8, C)^
A
a
a
a
a
a
a
a
a
c
c
c
a
a
c
a
8
c
a
a
Oral Exposure Route RSOJ
CSF
(mg/kg/day)-1
-
945E+00
2.8E+00
5.1E*01
7.06*00
2.2E*01
3.01E+02
2.1E4-00
77E*00
2.56E-01
5 1E-02
--
1 05E*01
30E-02
2.00E-01
1 93EfOO
1 IE + 00
5.7E-02
1 1E-02
20E-02
Soil
(mg/kg)
--
741E-02
2.5E-01
1 4E-02
1.0E-01
3.2E-02
2.33E-03
3.3E-01
9.1E-02
2.73E*01
1 .4E + 02
--
6.67E-02
23E+01
3.50E*01
3.63E-01
6.46-0 1
1.2E+02
64E*01
35E*01

Water
(ug/i)
--
3.70E-03
1 3E-02
69E-04
SOE-03
1 66-03
1.16E-04
1 7E-02
45E-03
1 37E+00
6.964-00
-
3.33E-03
1 2E*00
1.756*00
5 18E-02
See MCL
6.1EfOO
See MCL
1 SEi-OO
mnalation Exposure Route
RSD3
CSF
(mg/kg/day)-1
1 7E * 00
945E*00
—
5 1E»01
—
•-
3016*02
2.1E*00
-
2.566-01
2.5E-01
-
1 05E+01
20E-03
2.00E-01
1 93E1-00
1 1E*00
5.7E-02
1 36-02
20E-02
Air
(Ug/m3)
" 2 1 £-03
3 70E-04
—
69E-05
—
—
1 166-05
1 7E-03
-
1 37E-01
1 4E-01
2E»00
3 33E-04
1 8E*00
1 75E-01
5 18E-03
3 2E-03
61E-01
2 7E-01
1 8E-01
^  These criteria are subject to change and will be confirmed by the regulatory agency prior
   to use.
2  The EPA Carcinogen Classification system is discussed in 51 FR 33992-34003 (Guidelines for
   Carcinogen Risk Assessment)
3  See Table 8-2 for the appropriate intake assumptions used to derive these criteria.
4  Indicates criteria undergoing EPA review.
                                        8-37

-------
             Table 8-7.  Health-Based Criteria for Systemic Toxicants'
Constituent
Acetone
Acetonitnle
Acetophenone
Aldicarb
Aldrm
Allyl alcohol
Aluminum phosphide
Antimony
Janum
Urturrt cyanide
9enztdme
Beryllium
Bi$(2-ethylhexyl)
phthalate
Jromodichloromethane
Iromoform
Iromomethane
Calcium cyanide
Carbon dtsulfide
Carbon tetrachlonde
Chiordane
Ihlonne cyanide
Chlorobenzene
l-Chloro-2,3
epoxypropane
Epichlorohydrin)
Ihloroform
Chromium (III)
Chromium (VI)
Copper cyanide
Cresols
Crotonaldenyde
Cyanide
Cyanogen
2.4-0
30T
>i-n-butylphthalate
CAS
No.
67-64-1
75-05-8
98-86-2
116-06-3
309-00-2
10M8-6
20859-73-8
7440-36-0
7440-39-3
542-62-1
92-87-5
7440-41-7
117-81-7
75-27-4
75-25-2
74-83-9
592-01-8
.75-15-0
56-23-5
57-74-9
506-77-4
108-90-7
106-89-8
67-66-3
16065-83-1
7440-47-3
544-92-3
1319-77-3
123-73-9

460-19-5
94-75-7
50-29-3
84-74-2
RfDi
(mg/kg/day)
1E-01
6E-03
1E-01
1E-03
3E-05
5E-03
4E-04
4E-04
5E-02
7E-02
2E-03
5E-03
2E-02
2E-02
2E-02
4E-04
4E-02
1E-01
7E-04
5E-05
SE-02
3E-02
2E-03
1E-02
1E+00
5E-03
5E-03
5E-02
1E-02
2E-02
4E-02
1E-02
5E-04
1E-01
Soil
(mg/kg)
8E+03
5E+02
86*03
8E+01
2£*00
46+02
36+01
36+01
46+03
66+03
26+02
46+02
26+03
2E+03
2E+03
36 + 01
3E+03
8E+03
6E+01
46+00
46+03
26+03
26+02
8E+02
86+04
46 + 02
46+02
4E+03
8E+02
2E+03
3E+03
86+02
46+01
86+03
Water
(yg/D
46 + 03
26+02
46 + 03
46+01
1E + 00
2E+02
1E+01
16+01
See MCI
2E+03
7E+01
2E+02
76+02
7E + 02
7E+02
1E*01
16+03
4E*03
See MCI
26+00
26+03
1E+03
7E+01
46+02
46+04
See MCL
2E+02
2E+03
4E+02
7E+02
1E+03
See MCL
2E+01
4E+0
Air
(ug/m3)
-
-
-
56+00
-
--
-
-
-
-
-
--
-
7E+01
-
-
-
-
•-
-
-
«
"™
-
--
-
-
•-
-
-
-
-
-
-
Note:  These criteria are subject to change and will be confirmed by the regulatory agency prior
      to use.
                                       8-38

-------
                             Table 8-7.  (continued)i
Constituent
Dichiorodifluoro-
methane
1,1-Oichioroethylene
Dichloromethane
(Methylene chloride)
2,4-Oichlorophenol
1 ,3-Oichloropropene
Oitldrm
Oiethyl phthalate
Dimethoate
2.4-Omitrophenol
Dinostb
Diphenylamine
Disulfoton
Endosulfan
Endothal
Endnn
Ethylbenzene
Heptachior
Heptachlor epoxide
Hexachlorobuta-
diene
Hexachlorocyclo-
pentadiene
Hexachloroethane
Hydrogen cyanide
Hydrogen sulfide
isobutyl alcohol
isopHorone
Lmdane (hexa-
chlorocydohexant)
Maleic hydrazid*
Methacrylonitrilc
Methomyl
Methyl ethyl ketone
Methylijobutyl-
ketone
CAS
No.
75-71-8
75-35-4
75-09-2
120-83-2
26952-23-8
60-57-1
84-66-2
60-51-5
51-28-5
88-85-7
127-39-4
298-04-4
115-29-7
145-73-3
72-20-8
100-41-4
76-44-8
1024-57-8
87-68-3
77-47-4
67-72-1
74-90-8
7783-06-4
78-83-1
78-59-1
58-89-9
108-31-6
126-98-7
16752-77-5
78-93-3
108-10-01
RfD2
(mg/kg/day)
2E-01
9E-03
66-02
3E-03
3E-04
5E-05
8E-01
2E-02
2E-03
IE -03
3 £-02
4E-OS
5E-05
2E-02
3E-04
1E-01
5E-04
1E-05
2E-03
7E-03
1E-03
2E-02
3E-03
3E-01
2E-01
3E-04
5E-01
IE -04
3E-02
5E-02
SE-02
Soil
(mg/kg)
2E+04
7E-02
5E*03
2E*02
2E+01
4E*00
6E*04
2E*03
2E*02
SEi-01
2E*03
3E+00
4E*00
2E*03
2E+01
8E*03
46*01
8E-01
2E+02
6E+02
8E*01
2E+03
2E*02
2Ef04
2E+04
2E*01
4E+04
8E+00
2E*03
4E+03
4E*03
Water
(ug/D
7E*03
SeeMCL
2Ef03
1E+02
1E»01
2E*00
3E*Od
7£*02
7£*01
4E*Q1
1E>03
1E*00
2E*00
7E+02
See MCL
4E + 03
2E*01
4E-01
7E*01
2E*02
4E»01
76*02
16*02
16*04
7E*03
See MCL
26*04
46*00
16*03
2E*03
2E*03
Air
(ug/m3)
--
--
-
1E*01
«
--
--
-
76*00
-
-
-
2E-01
-
16*00
•-
--
•-
-
--
--
•-
•-
16*03
--
--
-
~
-
--
-
Note:  These criteria are subject to change and will be confirmed by the regulatory agency prior
      to use.
                                        8-39

-------
                             Table 8-7.  (continued)1
Constituent
Methyl mercury
Methyl parathion
Nickel
Nitric oxide
Nitrooenzene
Nitrogen dioxide
Octamethylpyro-
phosonorainide
Parathion
Pentacnlorobenzene
Pentacnloromtro-
benzene
Pentacnioroonenoi
Percnioroethyiene
(Tetracnioro-
ethylene)
Phenol
Phenyl mercuric
acetate
Phospnme
Potassium cyanide
Potassium silver
cyanide
Pronamtde(Kerb)
Pyndme
SeicniousAcid
Selenourea
Silver
Silver cyanide
Silvex(2.4,5-TP)
Sodium cyanide
Strychnine
Styrene
1.2 AS-
Tetrachlorobeniene
CAS
No.
22967-92-6
298-00-0
7440-02-0
'0102-43-9
98-95-3
10102-44^}
152-16-9
56-38-2
608-93-5
82-68-6
87-86-5
127-18-4
108-95-2
62-38-4
7803-51-2
151-50-6
506-6 1 -6
23950-58-5
110-86-1
7782-49-2
630-10-4
7440-22-4
506-64-9
93-72-1
143-33-9
57.24-9
100-42-5
95-94-3
Rf02
(mg/kg/day)
36-04
3E-04
26-02
16-01
5E-04
IE -00
2E-03
3E-04
86-04
3E-03
36-02
16-02
4E-02
86-05
3E-04
56-02
26-01
86-02
16-03
36-03
SE-03
36-03
16-01
86-03
46-02
36-04
26-01
36-04
Soil
(mg/kg)
26*01
2£*01
2E*03
86*03
46*01
36*04
26*02
26*01
66*01
26*02
26*03
36*02
36*03
6E*00
25*01
46*03
26*04
66*03
86*01
26*02
46*02
26*02
86*03
66*02
36*03
26*01
26*04
26*01
Water
(ug/D
'6*01
1£*01
76*02
46*03
2E*01
ag.04
7E»01
16*01
36*01
16*02
16*03
46*02
1E+03
36*00
16*01
26*03
7E*03
36*03
ag* 01
See MCI
26*02
See MCI
46*03
36*02
16*03
16*01
76*03
16*01
Air
(ug/m3)
-
16*00
-
'
-
•-
-
-
36*00
-
'5*02
"™
-
—
-
--
-
-
-
-
-
-
-
-
-
-
—
16*00
Note:  These criteria are subject to change and will be confirmed by the regulatory agency
       prior to use.
                                       8-40

-------
                             Table 8-7.  (continued)1
Constituent
2.3.4,6-
Tetrachlorophenol
Tetraethyl lead
Thalhc oxide
Thallium acetate
Thallium carbonate
Thallium chloride
Thallium nitrate
Thallium selenite
Thallium sulfatt
Thiram
Toluene
1.2.4-
Tnchlorobenzene
l.l. t-
Tnchloroethane
1,1.2-
Tnchloroethane
Tncrtloromono-
fluoromethane
2.4.5-
Tnchlorophenol
2,4,5-Tnchloro-
phenoxy acetic acid
(2.4.5-T)
1.1.2-
Tnchloroprooane
1,2,3-
Trichloropropane
Vanadium
pentoxide
Warfarin
Xylene (total)
Zinc cyanide
Zmc phosphide
CAS
No.
58-90-2
78-00-2
1314-32-5
563-68-8
6533-73-9
7791-12-0
10102-45-1
12039-52-0
10031-59-1
1 37-26-8
108-88-3
120-82-1
71-55-6
79-00-5
75-69-4
95-95-4
93-76-5
598-77-6
96-18-4
1314-62-1
81-81-2
1330-20-7
557-21-1
1314-84-7
RfD2
(mg/kg/day)
3E-02
1E-07
4E-04
SE-04
4E-04
4E-04
SE-04
5E-04
3E-04
5E-03
3E-01
2E-02
9E-02
2E-01
3E-01
1E-01
3E-03
5E-03
1E-03
2E-02
3E-04
2E+00
SE-02
3E-04
Soil
(mg/kg)
2E*03
8E-03
3E+01
4E»01
3E + 01
3E+01
4E+01
46*01
2E*01
4£*02
2E*04
2E*03
7E*03
2E*04
2E^04
8E»03
2E+02
4E*02
8E*01
2Ef03
2E*01
2E*05
4E+03
2E*01
Water
(ug/D
1E*03
4E-03
1E + 01
2E»01
1E*01
1E*01
2E*01
2E*01
1E + 01
2E*02
1E+04
7E + 02
See MCL
7E*03
IE +04
4E*03
See MCL
2E+02
4E*01
7E+02
IE-t-01
76*04
2E»03
1E*01
Air
(ug/m3)
1E*02
4E-04
•-
-
-
--
~
-
-
-
-
-
-
~
-
4E + 02

-
-
-
-
-
-
-
1  These criteria are subject to change and will be confirmed by the regulatory agency prior to
   use.
2  See Table 8-2 for the appropriate intake assumptions used to derive these criteria.
                                        8-41

-------
                   Table 8-8.  Water Quality Criteria Summary!
Chemical
Acenapthene"
Acroltm
Acrylomtrile
Aldrm
Alkalinity"
Ammonia*-"
Antimony
Arstnic
Arsenic (PENT)
Arsenic (TRI)
Asbestos"
Bacteria*-"
Barium
Benzene
Benzidtne
Beryllium
BHC
Cadmium
Carbon
tetraehionde
Chlordane
Chlormdated
Benzenes
Chlorinated
Naphthalenes
Chlorine"
Chloroalkyl Ethers"
WATER
CONCENTRATIONS IN ug/L
FOR AQUATIC LIFE
Fresh
Acute
Criteria
1,700*
68*
7,550*
3.0


9.000*

850*
360



5300*
2.500*
130*
100*
3.9'
35.200*
2.4
250*
1,600*
19
238.000*
Fresh
Chronic
Criteria
520*
21*
2.600*

20,000

1,600*

48*
190





S3*

i i'

00043
SO*

11

Marine
Acute
Criteria
970*
55*

1 3




2,319*
69



5.100*


0.34*
43
50.000*
0.09
160*
75*
13

Marine
Chronic
Criteria
710*







13*
36



700*



93

0004
129*

75

WATER CONCENTRATIONS IN
UNITS PER LITER
FOR HUMAN EXPOSURE
Water
and
Fish
Ingestion

320 ug
0 058 ug'
0.074ngS


146ug
2.2ng»


30k f/l»

img
0.66ug»
0.12ng»
68ng»

I0yg
0.4ug»
0.46ng»
488U9



Fish
Consumption
Only

780 ug
0.65ug*
0 079ng»


45,000 ug
17 5ng»





40ug»
053ng»
117ng9


6.94ug»
0 48ng>




Date
Reference
'980?R
1980FR
!980FR
1980FR
1976R8
1985PR
'980FR
1980FR
1985FR
1985FR
1960FR
'966rR
•976R3
•980FR
•980FR
1980FR
•980FR
'985FR
1980FR
'980FR
1980FR
1980FR
'985FR
1980FR
Note:  These criteria are subject to change and will be confirmed by the regulatory agency prior to
      use.
                                       8-42

-------
                               Table S-.8. (continued)
Chemical
Chloro«thyl tthtr
(8IS-2),
Chloroform
Chloroisopropyl
«thtr(BIS-2)n
Chloromtthyl «htr
(BIS)
Chloropn«nol 2"
Chlorophcnol 4
Chlorophcnoxy
Htrbicid«(2.4,5-TP)
Chlorophcnoxy
H«rbicid«(2,4,-0)
Chlorpynfos11
Chloro-4 mtthy!-3
phtnol
Chromium (HEX)
Chromium (TRI)
Color*-"
Cooptr"
Cyamdt
DOT
DOT Metaboiitt
(DOE)
DOT Metaoolitt
(TOE)
D«m«ton"
Oibutyi prtthaiatt
Oichiorooenzcnes
Dichiorobenzidint
WATER
CONCENTRATIONS IN ug/L
FOR AQUATIC LIFE
Fresh
Acute
Criteria

28,900*


4,380<



0083
30*
16
1,700'

18'
22
1 1
1,050«
0.06*


1,120«

Fresh
Chronic
Criteria

1,240«


2,000*



0.041

11
210'

12'
5.2
0.001


0.1

763*

Marine
Acute
Criteria




t
29,700*


0.011

1,100
10,300*

29
1
013
14*
38<


1,970*

Marine
Chronic
Criteria








00056

50


29
1
0001


0.1



WATER CONCENTRATIONS iN
UNITS PER LITER
FOR HUMAN EXPOSURE
Water
and
Fish
Ingestion
0.03ug»
O.l9ug»
347ug
000000376
ng»


lOyg
100yg

•
SOug
I70mg


200U9
0.024ng*



35mg
400yg
ooiug9
Fish
Consumption
Only
i 36ug»
157Ug9
436mg
000184ug*







3,433mg



0.024ng»



I54mg
2 6mg
0020ug*
Date
Reference
1980PR
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1976FR
•986FR
1980FR
1985FR
1985FR
1976RB
198SFR
1985FR
1980FR
1980FR
1980FR
1976RB
1980FR
1980FR
'980FR
Note:  These criteria are subject to change and will be confirmed by the regulatory agency prior to
       ust.
                                        8-43

-------
                               Table8-8.  (continued) 1
Chemical
Dichiorotthant 1,2
}ichloro«thyltn*s
Jichlorophtnol 2.4
XWoroprooan*
3tchloroprop«nt
Jitldrm
5i«hyi phthalatt
3im«thyi phtnoi 2.4
>imtthyi phthalatt
3imtrotolu«nt 2,4
>imtroWlu«nt
}mitrotOlutnt
5imtro-oCrtJol2.4
Dioxm (2.3,7,8-TCOO)
3iph«nylhydrazin«
5iphtnylhydrazmt
1.2
Di-2-«thyl htxyl
>hth«l«tt
indosulfan
•ndrm
Ethylb«nztn«n
!luor»nthtnt
Gaits, Total4-"
Unsolved
Guthion11
WATER
CONCENTRATIONS IN ug/L
FOR AQUATIC LIFE
Fresh
Acute
Criteria
118.000*
11,600«
2,020«
23,000*
6,060*
2.5

2,120*



330*

001*

270*

0.22
0.18
32.000*
3,980*


Fresh
Chronic
Criteria
20.000*

365*
5.700*
244*
0.0019





230*

0.00001*



0.056
0.0023



001
Marine
Acute
Criteria
113,000*
224.000*

10,300*
790*
0.71





590*





0.034
0037
430*
40*


Marine
Chronic
Criteria



3,040*

0019





370*




#
00087
0.0023

16*

0.01
WATER CONCENTRATIONS IN
UNITS PER LITER
FOR HUMAN EXPOSURE
Water
and
Fish
Ingestion
0 9«ug»
0.033U9*
3 09mg

87ug
0071ng»
3SOmg

313mg
o.tiug9
70ug

134ug
0.000013
ng«
42ng»

15mg
74ug
lug
1 4m g
42ug


Fish
Consumption
Only
243ug»
1 85ug»


14 img
0.076ng»
1 8g

2.9g
9-1 ug»
U3ug

765ug
0000014ng» »
o 56ug9

SOmg
I59wg

328mg
54ug


Date
Reference
1980F"
1980P»
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
•980FR
1984FR
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1976RB
1976R8
Note:  These criteria are subject to change and will be confirmed by the regulatory agency prior to
       use.
                                         8-44

-------
                              Table 8-8.  (continued)i
Chemical
Haloetherj
Haiometnanes
Heotacnior
Hexachloroetnane
Hexacnlorobenzene
HexacMoro-
butadiene
Hexachlorocyclo-
hexane(Lindane)
Hexacnlorocyclo-
hexane-Alpha"
Hexacnlorocyclo-
hexane-Beta"
Hexacnlorocyclo-
Hexane-Gamma"
Hexachlorocyclo-
hexane-Tecnmcal"
Hexacnlorocycio-
pentadme
Iron11
isopnorone"
Lead
Malathton"
Manganese"
Mercury
Methoxycnlor
Mirex"
Monocnloro-
benzene
Naohthalene
Nickel
Nitrates"
WATER
CONCENTRATIONS IN ugL
FOR AQUATIC LIFE
Fresh
Acute
Criteria
360«
11,000*
052
960*

90*
2.0




7»

117,000*
82'


2.4



2.300*
1 400'

Fresh
Chronic
Criteria
122*

00038
540*

93*
008




52*
1.000

32'
0.1

0.012
003
0.001

620*
160'

Marine
Acute
Criteria

12.000*
OOS3
940*

32*
0.16




7*

12.900*
140


2.1



2.350*
75

Marine
Chronic
Criteria

3.400*
00036











56
0.1

0025
0.03
0001


8.3

WATER CONCENTRATIONS iN
UNITS PER LITER
FOR HUMAN EXPOSURE
Water
and
Fish
Ingestion

0 !9ug9
0 28ng«
I9ug
0.72ncj»
0.45ug}

9.2ng»
16.3ng»
18.6ng»
12.3ng»
206ug
0 3mg
5 2mg
50ug

SOug
144ng
lOOug

488ug

13. «ug
'Omg
Fish
Consumption
Only

15 7ug»
0 29ng»
874ug
0 74ng»
soug»

31ng»
54.7ng»
62.5ng»
41 4ng'


520mg


lOOug
I46ng




lOOug

Date
Reference
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1976R8
1 980FR
198SFR
1976R9
1976RB
1985FR
1976R8
1976R8
1980FR
1980FR
1986FR
1976R3
Note:   These criteria are subject to change and will b« confirmed by the regulatory agency prior to
       use.
                                        8-45

-------
                              Table 8-8.  (continued)
Chemical
Nitrobenzene
Nitropnenols
Nitrosammes
Nitrosodibutyl-
ammeN
Nitrosodittnyl-
amineN
Nitrosodimetnyl-
ammeN
Nitrosodiphenyl-
amineN
Nitrosooyrroddine N
Oil and Grease* "
Oxygen Dissolved* "
Parathion
PCS's
Pentacniormated
Ethanes
Pentachloro-
benrene
Pentacnioroonenoi
pH1'
Ph«nol
PhoJOhorui
Elemental"
PHthaiatt Esters
Polynudear
Aromatic
Hydrocarbons
Selenium
Silver
WATER
CONCENTRATIONS IN ug/L
FOR AQUATIC LIFE
Fresh
Acute
Criteria
27.000*
230»
5,650*







0065
20
7,240*

20'°

10.200*

940*

260
A 1'
Fresh
Chronic
Criteria

150*








0013
0014
1,100*

1310
6.5-9
2.560*

3*

35
0 12
Marine
Acute
Criteria
6,680*
4.850*
3,300.000*








10
390*

13

5.800*

2.944*
300*
410
2.3
Marine
Chronic
Criteria











003
281*

' 79*
6.5-85

0.1
34*

54

WATER CONCENTRATIONS ilM
UNITS PER LITER
FOR HUMAN EXPOSURE
Water
and
Fish
Ingestion
I98mg

08ng'
6.4ng*
0.8ng»
1 4ng>
4,900ng»
16ng»



0 079ng»

74g
1 Olmg

3 Smg


2.8ng»
lOug
SOug
Fish
Consumption
Only


I240ng»
587rtg«
1,240ng»
16,000ng«
I6,100rtg<
91.900ng»



0079ng»

8Sug





31 1ng»


Date
Reference
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1980FR
1976R8
'986FR
1986FR
1 980FR
1980FR
1980FR
1966FR
1976R8
1980FR
1976R8
1980FR
1980FR
1980FR
1980FR
Note:  These criteria are subject to change and will be confirmed by the regulatory agency prior to
       use.
                                        8-46

-------
                              Table 8-8.  (continued)i
Chemical
Solids Dissolved and
Salinity"
Solids Suspended
and Turbidity4."
Sulfiae-Hydrogen
Sulfide
Temperature6-"
Tetrachlonnated
Ethanes
Tetracnioro-
benzere 1.2.4,5
Tetrachloroethane
1.1,2.2
Tetrachloroetnanes
Tetrachloro-
ethylene
Tetrachlorophenol
2.3.5.6
Thallium
Toluene
Toxaphene
Trtchlonnated
Ethanes
Tnchloroethan*
1,1, T
Tnchloroetnane
1,1.2
Tnchioroethyiene)
TnchloropnenoJ
2.4.5
Tnchloropnenol
2.4,6
Vinyl Chloride
Zmc"
WATER
CONCENTRATIONS IN pg/L
FOR AQUATIC LIFE
Fresh
Acute
Criteria




9,320*


9.320*
5,280*

1 400*
17,500*
073
18,000*


45.000*



120'
Fresh
Chronic
Criteria


2



2,400*

840*

40*

00002


9,400*
2 1 ,900*

970*

110'
Marine
Acute
Criteria






9,020*

10,200*

2,130*
6.300*
0.21

31,200*

2.000*



95
Marine
Chronic
Criteria


2





450*
440*

5.000*
00002







86
WATER CONCENTRATIONS IN
UNITS PER LITER
POR HUMAN EXPOSURE
Water
and
Fish
Ingestion
250mg




38U9
0.1 7ug'

oaug*

!3ug
143mg
0.71ng«

18.4mg
0.6ug»
27ug»
2.600ug
1 2ug»
2ug'

Fish
Consumption
Only





48ug
I0.7ug'

885ug'

48ug
4.2 Am q
073ng9

i 03g
41 8wg'
80 7ug»

3.6ug»
525ug»

Date
Reference
1976R8
1976R8
1976R8
1976R8
1980FR
1980FR
1980FR
1980FR
1980FS
'980FR
1980FR
•980"
'986PR
1980FR
1980FR
1980FR
•980FR
1980FR
1980FR
1980FR
'987FR
Note:  These criteria are subject to change and will be confirmed by the regulatory agency prior to
       use.
                                        8-47

-------
Footnotes for Table 8-8:


 1   This table is for general information purposes only; see criteria documents or
    detailed summaries in Quality Criteria for Water 1986 for more information.
    These criteria are subject to change and will be confirmed by the regulatory
    agency prior to use.

 2    Criteria are pH and temperature dependent - See Document (1)

 3    For primary recreation and shellfish uses - See Document (1)

 4    Narrative statement - See Document (1)

 5    Warmwater and coldwater criteria matrix - See Document (1)

 6    Species dependent criteria -See Document (1)

 7    Hardness Dependent Criteria (100 mg/l used)

 8    Insufficient data to develop criteria.  Value presented is lowest observed
     effect level.

 9    Human health criteria for carcinogens reported for three risk levels.  Value
     presented in this table is the 10-6 risk level.

 10   pH dependent criteria - 7.8 pH  used.

 n   Indicates chemical or parameter not on Appendix VIII.  The  regulatory
     agency will exercise discretion  prior  to  requiring  such  chemicals or
     parameters to be monitored during the RFI.

 General     g    a   grams                FR   a    Federal Register
            mg  a   milligrams             RB   a    Quality Criteria for
            wg   »   micrograms                      Water, 1976
                                                     (Redbook)
            ng   a   nanograms
            f     =   fibers
                                  8-48

-------
Table 8-9. Individual Listing of Constituents Contained Within
          Chemical Groups Identified in Table 8-8
Chemical Group
Chlorinated Benzenes
Chlorinated Ethanes
Chloroalkyl Ethers
Chlorinated Naphthalene
Chlorinated Phenols
Oichlorobenzenes
Dichlorobenzidine
Dichloroethylenes
Dichloropropane and
Dichloropropene
Oinitrotoluene
Haloethers
Halomethanes
Individual Constituents
Chlorobenzene
1 ,2,4-Trichlorobenzene
Hexachlorobenzene
1,2-Dichloroethane
1,1,1-Trichloroethane
Hexachloroethane
1,1-Oichloroethane
1 . 1 ,2-Trichloroethane
Chloroethane
Bis(chloromethyl) ether
Bis(2-chloroethyl ether
2-Chloroethyl vinyl ether (mixed)
2-Chloronaphthalene
2,4, 5-Trichl orophenol
Parachlorometa cresol
1 ,2-Oichlorobenzene
1 ,3-Oichlorobenzene
1 ,4-Oichlorobenzene
S.S'-Oichtorobenzidine
1,1-Dichloroethylene
1 ,2-Trans-dichloroethylene
1 ,2-Oichloropropane
1,2-Dichloropropylene(1,3-dichloropropene)
2,4-Oinitrotoluene
2,5-Dinitrotoluene
4-Chlorophenyl phenyl ether
4-Bromophenyl phenyl ether
Bis (2-chloroisopropyl) ether
Bis (2-chloroethoxy) methane
Methylene chloride (dichloromethane)
Methyl chloride (chloromethane)
Methyl bromide (bromomethane)
Bromoform (tri bromomethane)
Oichlorobromomethane
Trichlorofluoromethane
Oichlorodifluoromethane
Chlorodibromomethane
                          8-49

-------
Table 8-9. (Continued)
Chemical Group
Nitrophenols
Nitrosamines
Phthalate Esters
Polynuclear Aromatic Hydrocarbons
Endosulfan and Metabolites
Endrin and Metabolites
Heptachior and Metabolites
Polychlorinated Biphenyls
Individual Constituents
2-Nitrophenol
4-Nitropheno!
2.4-Dinitrophenol
4,6-Dinitro-o-cresol
N-Nitrosodimethylamine
N-Nitro$odiphenylamine
N-Nitrosodi-n-propylamine
Bis (2-ethylhexyl) ph thai ate
Butyl benzyl phthalate
Di-n-butyl phthalate
Oi-n-octyl phthalate
Diethyl phthalate
Dimethyl phthalate
Benzo(a) anthracene (1,2-benzanthracene)
Benzo(a) pyrene
3,4-Benzofl uoranthene
Benzo(k) fl uoranthene (1 1,12-benzof I uoranthene)
Chrysene
Acenaphthylene
Anthracene
Benzo(ghi)Perytene (1 , 1 2-benzoperylene)
Pluorene
Phenanthrene
Dibenzo(a,h)anthracene(1,2,5,6-dibenzanthracene)
Indeno ( 1 ,2,3-cd)pyrene
Pyrene
a-Endosulfan-Alpha
p-Endosulfan-Beta
Endosulfan sulfate
Endrin
Heptachior
Heptachior epoxide
PCB-1 242 (Arochlor 1242)
PCB-1254(Arochlorl254)
PCB-1221 (Ar
-------







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-------
Legend for draft version of prinking Water Standards and Health Advisories table.



Abbreviations column descriptions are:

       NIPDWR  -  National Interim Primary Drinking Water Regulation. Interim enforceable
                    drinking water regulations first established under the Safe Drinking Water
                    Act that are protective of public health to the extent feasible.

       MCLG     -  Maximum Contaminant Level Goal. A non-enforceable concentration of a
                    drinking water contaminant that is protective of adverse human health
                    effects and allows an adequate margin of safety.

       MCL      -  Maximum Contaminant Level. Maximum permissible level of a contaminant
                    in water which is deivered to any user of a public water system.

       RID       •  Reference Dose.  An estimate of a daily exposure to the human population
                    that is likely to be without appreciable risk of deleterious effects over a
                    ifetime.

       DWEL     •  Drinking Water Equivalent Level. A lifetime exposure concentration
                    protective of adverse, non-cancer health effects, that assumes all of the
                    exposure to a contaminant is from a drinking water source.

(•) The codes for the status flea and Status HA columns are as follows:

       F   -   final

       0   -   draft

       L   -   listed for regulation

       P   •   proposed (Phase II draft proposal)

       T   -   tentative (Phase V)

Other codes found in the table include the following:

       NA  -  not applicable

       P S  -  performance standard 0.5 NTU -1.0- NTU

       TT  -  treatment technique

            -  No mom than 5% of the samples may be positive. For systems collecting fewer
              than 40 samples/month, no more than 1% may be positive.

       •••   -  guidance

       t    -  Large discrepancies between Lifetime and Longer term HA values may occur
              because of the Agency's conservative policies, especially with regard to
              carcinogenicity,  relative source contribution, and less than lifetime exposures in
              chronic toxitity testing. These factors can result in a cumulative UF (uncertainty
              factor) of 10 to 1000 when calculating a Lifetime HA.
                                              8-58

-------
8.10.2     Worksheets

     Worksheets 8-1 and 8-2 may be used by the regulatory agency in comparing
constituent concentrations  in the release to  health and environmental criteria.
Example filled  in worksheets are also shown.  These  worksheets address the
following:

     •    8-1: Comparison of individual contaminant concentrations with criteria

     •    8-2: Use of hazard indices for exposure to chemical mixtures.

     A  questionnaire that may  be used in determining  if  interim  corrective
measures are necessary is provided in Worksheet 8-3. Questions are posed to help
focus the determination. These questions will be addressed to the extent possible
based on available information.  The regulatory agency will not necessarily need
answers for all questions in order to make a decision  as to whether interim
corrective measures are necessary.  If release concentration information is available,
Worksheets 8-1 and 8-2 may also be filled out.
                                    8-59

-------
                                   WORKSHEET 8-1

            COMPARISON OF INDIVIDUAL CONSTITUENT CONCENTRATIONS
                    WITH HEALTH AND ENVIRONMENTAL CRITERIA

                                                             Facility Name
                                                             Releasing Unit
                                                       Contaminated Media
                                                           Sample Location
                                                         Sample Number(s)
                                                                     Date
                                                                  Analyst
Exposure
Medium
WATER




SOIL




AIR




Constituent Released















Release
Concentration















Table No.
and Criterion
Type Used















Criterion
Value















Release
Concentrations
Exceed Criterion?















                                     INSTRUCTIONS

1.  List chemicals with human-health and environmental criteria for the appropriate exposure medium.
2.  List chemical concentration for the appropriate exposure medium.
3.  List type of human-health and environmental criteria used and applicable table number.
4.  List appropriate criteria values.
5.  Compare chemical concentration and criteria values and identify whether release concentration
   exceeds criteria.
                                         8-60

-------
                              EXAMPLE WORKSHEET 8-1

            COMPARISON OF INDIVIDUAL CONSTITUENT CONCENTRATIONS
                    WITH HEALTH AND ENVIRONMENTAL CRITERIA
                                                   Site Name

                                                Releasing Unit

                                          Contaminated Media

                                              Sample Location

                                             Sample Number(s)

                                                        Date

                                                      Analyst
SiteX
Impoundment 2
Ground Water/Air/Soil

MW 2/X-7 (see Map)

MW2-1/X-7-1	

9/4/86	

JDP	
Exposure
Medium
WATER




SOIL



AIR




Constituent Released
Trichloroethylene
Carbon tetrachloride
Chloroform


Chlorobenzene
Pentach 1 orobenzene


Trichloroethylene




Release
Concentration
2wg/l
1vig/l
3vg/l


1 0 mg/kg
7 mg/kg


0.1 ug/m3




Table No.
and Criterion
Type Used
MCL
Table 8-7
MCL
Table 8-7
Carcinogen
Table 8-6


Systemic Tox.
Table 8-7
Systemic Tox.
Table 8-7


Carcinogen
Table 8-6




Criterion
Value
5yg/l
5wg/l
5.7 ug/l


2000 mg/kg
60 mg/kg


0.27 yg/m3




Release
Concentrations
Exceed Criterion?
No
No
No


No
No


No




                                     INSTRUCTIONS

1.  List chemicals with human-health and environmental criteria for the appropriate exposure medium.
2.  List chemical concentration for the appropriate exposure medium.
3.  List type of human-health and environmental criteria used and applicable table number.
4.  List appropriate criteria values.
5.  Compare chemical concentration and criteria values and identify whether release concentration
   exceeds criteria.
                                         8-61

-------
                                    WORKSHEET 8-2

                        USE OF HAZARD INDICES FOR EXPOSURE
                               TO CHEMICAL MIXTURES
                                                               Facility Name
                                                              Releasing Unit
                                                        Contaminated Media
                                                            Sample Location
                                                           Sample Number(s)
                                                                      Date
                                                                    Analyst
Exposure
Medium
WATER





SOIL





AIR




Constituent Released

















Ratio of Release
Concentration to
Criterion Value

















HAZARD INDICES
Medium
Total

















Value Exceeds
Unity'

















                                      INSTRUCTIONS
1.  List chemicals in each environmental medium, as shown in Worksheet 8-1.
2.  Compare chemical concentrations and appropriate health criteria values, as shown in Worksheet 8-1.
   Determine ratio of release concentration to the criteria values.
3.  Determine a hazard index for the chemicals in each medium by summing the ratios calculated by
   comparing chemical concentrations and health criteria.
4.  Determine if the hazard index for the chemical mixture found in each individual exposure medium
   exceeds unity.
                                          8-62

-------
                               EXAMPLE WORKSHEET 8-2

                        USE OF HAZARD INDICES FOR EXPOSURE
                               TO CHEMICAL MIXTURES
                                                    Site Name

                                                 Releasing Unit

                                           Contaminated Media

                                               Sample Location

                                             Sample Number(s)

                                                         Date

                                                       Analyst
SiteX
Impoundment 2
Ground Water/Air/Soil

MW 2/X-7 (see Map)

MW2-1/X-7.1	

9/4/86	

JDP	
Exposure
Medium
WATER





SOIL




AIR




Constituent Released
Trichloroethylene
Carbon tetrachloride
Chloroform



Chlorobenzene
Pentachlorobenzene



Trichloroethylene




Ratio of Release
Concentration to
Criterion Value
0.4
0.2
0.53



0.0005
0.12



0.37




HAZARD INDICES
Medium
Total



1.13




0.125


0.37




Value
Exceeds
Unity?



Yes




No


No




                                      INSTRUCTIONS
1.  List chemicals in each environmental medium, as shown in Worksheet 8-1.
2.  Compare chemical concentrations and appropriate health criteria values, as shown in Worksheet 8-1.
   Determine ratio of release concentration to the criteria values.
3.  Determine a hazard index for the chemicals in each medium by summing the ratios calculated by
   comparing chemical concentrations and health criteria.
4.  Determine if the hazard index for the chemical mixture found in each individual exposure medium
   exceeds unity.
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                             WORKSHEET 8-3

QUESTIONS  TO  BE  CONSIDERED  IN  DETERMINING  IF  INTERIM  CORRECTIVE
                      MEASURES MAY BE NECESSARY

     In  considering the actual  or potential threat to human  health  or the
environment posed by a contaminant release, the regulatory agency will consider
factors such as type and extent of the release and site demographics. The following
questions may be used in  evaluating these  factors.  If sufficient information is
available, the worksheets presented on  the-previous pages may also be used in
evaluating the need for interim corrective measures.  For further details, see RCRA
Corrective Action Interim Measures (U.S. EPA, 1987).

A.   Release Characterization

     1.   What  is the source(s) (e.g., nature, number of drums,  area, depth,
         amount, location(s))?

     2.   Regarding hazardous wastes or constituents at the source(s):

         a.   Which hazardous wastes  (listed,  characteristic) and  hazardous
              constituents are present?

         b.   What are their concentrations?

         c.    What  is the background level  of each  hazardous waste or
              constituent?

     3.   What  are the known pathways through  which the contamination is
         migrating or may migrate and the extent of contamination?

         a.   Through which media is the release spreading or likely to spread?
              Direction? Rate?

         b.   How far has the release migrated?  At what concentrations?
                                   8-64

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         c.    How mobile is the constituent?

         d.   What are the estimated quantities and/or volumes released?

     4.   What is the projected fate and transport?

B.    Potential Human Exposure and Effects

     1.   What is  or will  be the exposure pathway(s) (e.g.,  air,  fire/explosion,
         ground water, surface water, direct contact, ingestion)?

     2.   What  are the  location  and  demographics  of   populations  and
         environmental  resources  (potentially) at  risk  from exposure  (e.g.,
         residential areas, schools, drinking water supplies, sole source aquifers
         near vital ecology or protected natural resources)?

     3.   What are the potential effects of human exposure (short-  and long-term
         effects)?

     4.   Has human exposure actually occurred? Or when may human exposure
         occur?

         a.   What is the  exposure route(s) (e.g.,  inhalation, ingestion, skin
              contact)?

         b.   Are there any reports of illness, injury, or death?

         c.    How many people will  be affected?

         d.   What are the characteristics of the exposed populations(s) (e.g.,
              presence of sensitive populations such as infants or nursing  home
              residents)?

     5.   If response is delayed, how will the situation change (e.g., what will be
         the implications to human health)?
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C.   Potential Environmental Exposure and Effects

     1.   What media have been and may be contaminated (e.g., ground water,
         air, surface water)?

     2.   What are the likely short-term and long-term threats and effects on the
         environment of the released waste or constituents?

     3.   What natural resource and environmental effects have occurred or are
         possible (terrestrial, aquatic organisms, aquifers whether or not used for
         drinking water)?

     4.   What are the known or projected ecological effects?

     5.   When is this threat/effect likely to materialize (days, weeks, months)?

     6.   What are the projected long term effects?

     7.   If response is delayed, how will the situation change?
                                   8-66

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               APPENDIX A





AERIAL PHOTOGRAPHY, MAPPING, AND SURVEYING
                   A-1

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                              APPENDIX A

             AERIAL PHOTOGRAPHY, MAPPING, AND SURVEYING
     Aerial photographs,  maps, and  surveys can assist in verifying and
characterizing  contaminant releases and are  particularly helpful sources of
information that can be used during the development of a monitoring plan. They
can also be used, when viewed in historical sense (e.g., over the same location, but
at different points in time), to locate old solid waste management units, stream
beds, and other facility features.  Stereo viewing (using a stereoscope) can further
enhance the interpretation of photographs and maps because vertical as well as
horizontal spatial relationships  can  be observed.  This Appendix discusses the
potential applications of aerial photography, mapping, and surveying in the RFI
process.

     Case Study Numbers 12, 13 and 14 in Volume IV (Case Study Examples)
illustrate the use of several of the techniques presented in this Appendix.

AERIAL PHOTOGRAPHY

Introduction

     Aerial photography may  be  used to gather release verification and
characterization information during the RFI. Although detailed aerial photographic
analysis usually requires a qualified photo-interpreter, the site information that it
can readily provide may warrant its use. Aerial photography can provide valuable
information on. the environmental setting as well as indications of the nature and
extent of contaminant  releases. However, when using aerial  photographic
techniques, important release  information  should be verified through field
observations.

Information Obtained From Aerial Photographs

     The basic recognition elements  commonly  utilized  in  photographic
interpretation are shape, texture, pattern, size, shadow, tone and/or color. Natural
                                  A-2

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color, false color or color infrared, and black and white film are routinely used in
aerial photographic applications. Color imagery may be more readily interpreted
than black and white film, by providing enhanced differentiation of subtle evidence
of such items as surface leachate (e.g., seeps) and surface water quality.  Color
infrared film offers an added  element of information with its near infrared
sensitivity  by enabling  assessment of vegetation type, damage, or stress, and
providing a wide range for detection of moisture conditions in soils.

     Subsurface characteristics  can  be inferred by surface information in  the
photographs.   For example,  vegetative stress may indicate leachate and  gas
migration where the water table is shallow or in discharge areas.  Infrared may be
able to detect vegetative stress not noticeable during a field inspection. Geologic
features (variation  in the distribution of geologic units,  bedrock fractures, fault
zones, etc.) that can affect ground-water flow pathways can also be identified from
aerial photographs. Fractures  at shallow depths in consolidated rocks can serve as
pathways for contaminated ground water and for  rapid infiltration  of  surfac
runoff.  Contamination of surface water bodies can be detected by discoloration or
shading in aerial photography. Land surface elevation determinations and contour
maps can be compiled, and ground-water flow direction in shallow systems can be
estimated using this information.  The time of year is  also an important
consideration when interpreting geologic and hydrologic features.   For example,
the presence of heavy vegetation during the summer months may obscure certain
geologic and hydrologic features.  As another example, drainage patterns and
seasonal, high water tables are more readily observed  after or during winter
snowmelt.

     Other information available from aerial photographs includes:  Natural
topography, drainage  and erosional features, vegetative cover and damage,
indications of leachate, damaged unit containment structures,  etc.  Observable
patterns, colors, and relief can make  it possible to distinguish differences in
geology, soils, soil moisture, vegetation, and land use. Aerial photography can also
indicate important hydrologic  features.  Springs and  marshy  areas represent
ground-water discharge areas.  In  cases of releases to ground water, aerial
photographs can indicate the existence of likely contaminant migration pathways
(e.g., recharge areas, sink holes, karst terrains, subsurface flow patterns, fissures,
and joints).  For releases to surface  water, aerial photographs  can  indicate the
                                   A-3

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location of potential contaminant receiving bodies (e.g., ponds and streams) and
site runoff channels.   Aerial photography can also be used to obtain input
information for designing monitoring plans (e.g., defining boundary  conditions
such as ponds, streams, springs, paved areas, large buildings, irrigation canals).

     Major benefits in using aerial photography as a supplement to other
investigative methods include:

     •   Obtaining information on relatively large areas, including surrounding
         land use and environmental features;

     •   Indicating effects of contamination; and

     •   Providing indirect indications of subsurface conditions.

     The following limitations should be  considered when  using  aerial
     photography:

     •   It does not provide direct information on subsurface characteristics;

     •   There may be variations in photo quality with age, season of flight, film
         type, photo scale, cloud cover, etc.; and

     •   Information obtained from photographs should  not be used alone  in
         evaluating surface/subsurface conditions. They should always be verified
         through field observations.

Use of Existing Aerial Photographs (Historical Analysis)

     Existing aerial photographs may be available that show the site prior to the
existence of some or all hazardous waste management  activities.  Individual
photographs provide an opportunity to identify specific features and activities at a
single point in time.  By identifying conditions at a site at several points in time (i.e.,
historical analysis), the sequence of events leading to the current conditions can be
better understood.  This process may  identify changes  in  surface drainage
conditions through time, locations of landfills, waste treatment  ponds/lagoons and
                                    A-4

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their subsequent burial and abandonment, the burial of waste drums, number of
drums, estimated depth and horizontal extent of burial pits, sources of spillage, and
discharge of liquid wastes, etc.  Historical  photographic analysis can be used to
make maps that reflect conditions that previously existed at a facility if enough
control points are provided (e.g., road intersections, power lines, buildings, railroad
tracks). This information may be very useful in determining appropriate monitoring
locations.  Analysis problems that should  be  considered when  using historical
photos include variations in  placement of the  site  within a given  frame of
photography and variations in scale.

Sources

     Town or county offices may have aerial photographs on file. Also, most of the
United States has been photographed in recent years for various Federal agencies.
A map entitled "Status of Aerial Photography in the United States"  has been
compiled that lists all areas (by county) that have been photographed by or for the
Agricultural Stabilization and Conservation Service, the Soil Conservation Service,
Forest Service,  U.S. Geological Survey,  Army Corps of Engineers, Air Force, and
commercial firms. These maps are available from:
     Map Information Office
     U.S. Department of the Interior
     Geologic Survey
     507 National Center
     Reston, VA  22092
     (703) 860-6045

The names and addresses of agencies holding  negatives for photographs are
printed on the back of the map.

     The U.S. EPA may also have taken aerial photos of certain facilities. The owner
or operator may inquire at specific federal and state regulatory offices for access to
any photos that  may have been taken. Other sources of aerial photographs are
listed below.

     Federal qovernment-The following two U.S. Geological Survey locations can
provide indices of all published maps and include order blanks, prices, and detailed
                                   A-5

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ordering instructions.  They may also provide a list  of addresses of local  map

reference libraries, local map dealers, and Federal map distribution centers.

          Eastern Distribution Branch
          U.S. Geological Survey
          1200 South Eads Street
          Arlington, VA 22202

          Western Distribution Branch
          U.S. Geological Survey
          Box 25286 Denver Federal Center
          Denver, CO 80225
Other Federal Agencies Include:

         Aerial Photography Field Office
         ASCS-U.S. Department of Agriculture (USDA)
         P.O. Box 30010
         Salt Lake City, Utah 84130
         (801)524-5856

         EROS Data Center

         U.S. Geological Survey
         Sioux Falls, SD 57198
         (605) 594-6511 (ext. 151)
         Soil Conservation Service
         USDA-SCS
         P.O. Box6567
         Fort Worth, TX 76117
         (817)334-5292

         National Archives
         841 South Pickett Street
         Alexandria, VA 22304
         (703) 756-6700
(Has all Agricultural
Stabilization and
Conservation Service
photos, Forest Service
photos, etc.)

(Landsat and U-2
photos,
black and white at
1:80,000 scale.
Computer listings of
all available photos
can be accessed)

(Supplies mostly low
altitude, 1:20,000 scale,
photos)
(For historical photos)
     All of the above agencies will require some information identifying the site
location to locate relevant photos. This information may be in the form of a town
engineer's map; Department of Transportation map; description of the township,
range, section; a hand-drawn map of the site in relation to another town; precise
longitude and latitude coordinates of the site area; or a copy of the portion of a U.S.
Geological Survey quadrangle that shows the site.
                                    A-6

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     For facilities near the United States-Canada border, the following agency may
provide aerial photographs:
         The National Air Photo Library
         Surveys and Mapping Branch
         Department of Energy, Mines and Resources
         615 Booth Street
         Ottawa, Ontario K1A OE9

     State government-State agencies may also have aerial photographs on file.
These include:

     •   Pollution control agencies;

     •   Health departments;

     •   Water resources departments;

     •   Forestry or Agricultural departments;

     •   Highway departments; and

     •   Geological survey departments.

     Private companies-Photographs required for the site of concern may be held
by private aerial survey  companies and can often be ordered directly from  these
sources. Local telephone listings and Photogrammetric Engineering, the Journal of
the American Society of Photogrammetry, can provide sources of information.

     Aerial  photographic survevs-lf existing  photographs are not available  or do
not provide enough information, the owner or operator may arrange for an  aerial
photographic survey to be conducted.  When deciding whether an aerial survey is
appropriate, the owner or operator should consider whether the information needs
can be filled with data obtained from  an aerial survey (or from another source or
investigative technique)  and the size of the site (for a small site,  a ground survey
may be more economical). This survey should be conducted by professionals who
                                   A-7

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will plan, schedule, and perform the flight, collect data with appropriate scale
and/or film requirements, analyze results, and compile maps, if necessary.

     Conducting New Aerial Photographic Survevs-A local telephone listing, the
Journal of the American Society of Photogrammetry, or the government agencies
listed in this section may provide names of companies or organizations that conduct
aerial photographic surveys. When requesting that an aerial photographic survey
be conducted, the owner or operator should supply the site location (e.g., marked
on a topographic map).  Property boundaries and waste management areas should
be outlined.  If photographic interpretation is also requested, a brief site
description, type and number of solid waste management units, and types of wastes
handled would also be helpful.

MAPPING

     To assist in adequately characterizing a release, various types of maps may be
useful. Maps can be used to show geology, hydrology, topography, climate, land
use, and vegetative characteristics. Maps can  be generated through compilation of
existing maps, aerial photographs, or through ground surveys. This section discusses
the usefulness of mapping in verifying and characterizing the nature and extent of
a release.   In general,  displaying information from  all types  of  maps can be
presented on the facility's existing topographic map as discussed below.

Topographic Maps

     The owner or operator should use, to the extent possible, the topographic
map and associated information that meets the requirements of 40 CFR Part 270
I4(b)(19) of EPA's Hazardous Waste Permit Program which states:
     "A topographic map showing a distance of 1000 feet around the facility at a
     scale of 2.5 centimeters (1 inch) equal to not more than 61.0 meters (200 feet).
     Contours must be shown on the map. The contour interval must be sufficient
     to clearly show the pattern of surface water flow in the vicinity of and  from
     each operational unit of the facility. For example, contours with an interval of
     1.5 meters (5 feet),  if relief is greater than 6.1 meters (20 feet), or an interval of
     0.6 meters ( 2 feet),  if relief is less than 6.1  meters (20 feet).  Owners and
     operators of HWM facilities located in  mountainous areas  should use large
     contour intervals to adequately show topographic profiles of  facilities. The
     map shall clearly show the following:
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          (i)        Map scale and date.
          (ii)       100-year floodplain area.
          (iii)       Surface waters including intermittent streams.
          (iv)       Surrounding  land  uses (residential, commercial, agricultural,
                   recreational).
          (v)       A wind rose (i.e., prevailing wind-speed and direction).
          (vi)       Orientation of the map (north arrow).
          (vii)      Legal boundaries of the HWM facility site.
          (yiii)      Access control (fences, gates).
          (ix)       Injection and withdrawal wells both onsite and off site.
          (x)       Buildings; treatment; storage, or disposal operations; or other
                   structures (recreation areas, runoff control systems, access and
                   internal roads, storm, sanitary, and process sewerage systems,
                   loading and unloading areas, fire control facilities, etc.).
          (xi)       Barriers for drainage or flood control.
          (xii)      Location of operational units within  the HWM facility site,
                   where hazardous  waste is  (or will be) treated,  stored,  or
                   disposed (include equipment cleanup areas)."


     Additional information that should be noted on the  topographic map is

specified in the requirements of 40 CFR Part 270.14(c)(3), which states:

     "On the topographic map required under paragraph (b)(19) of this section, a
     delineation of the waste management area, the  property boundary, the
     proposed "point of compliance' as defined under §264.95,  the  proposed
     location of ground water monitoring wells as required under §264.97, and, to
     the extent possible, the  information required  in  paragraph (c)(2) of this
     section.", that being . .  .  "(2) Identification of the uppermost aquifer and
     aquifers hydraulically interconnected beneath the facility property, including
     ground water flow direction  and  rate, and the basis for such identification
     (i.e.,  the information  obtained from hydrogeologic investigations of the
     facility area)."


     The use of topographic maps will enable the owner or operator to identify and

display many features useful in characterizing a release, such as potential surface
water receiving bodies, runoff pathways, and engineered structures.


Sources


     Topographic maps of the facility area may be available or obtained from:


     •    U.S.G.S. (generally with 10-foot contour intervals);


     •    Local town offices (e.g., Building  Department, Board of Assessors);
                                    A-9

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     •   Onsite surveying to obtain site specific elevation information; and

     •   Use of an aerial photographic consultant to fly the site and surrounding
         area and develop a map.

     A site-specific topographic map may be constructed by measuring and plotting
land elevations by a stadia survey. This method of surveying determines distances
and  elevations by means of a telescopic instrument having two horizontal lines
through which the marks on a graduated rod are  observed.  A local telephone
directory will usually list companies providing this service.

     Existing topographic maps may also be obtained from:
         Eastern Distribution Branch
         U.S. Geological Survey                    (East of the Mississippi River)
         1200 South Eads Street
         Arlington, VA 22202
         Western Distribution Branch
         U.S. Geological Survey
         Box 25286                            (West of the Mississippi River)
         Denver Federal Center
         Denver, CO 80225

     Before requesting a map, the proper quadrangle must be determined.  Maps
are indexed by geographic location-longitude and latitude.  The quadrangle size is
given in minutes or degrees. 7.5 minute quadrangles provide the best resolution.

     Other sources of topographic information include:

     •   Local colleges or universities that may have index map sets;

     •   Local town officials (town  engineers, planners, etc.) who know which
         quadrangles cover their area;

     •   Nearby institutions or  firms that deal with land  holdings are likely to
         have USGS quadrangles for that area; and

     •   Local USGS offices, map distributors and other suppliers.
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     Although for the most part the  above identified sources will not supply
topographic maps which satisfy the requirements of 40 CFR Part 270, they may still
be useful for pointing out old solid waste mangement units and other facility
features which may be useful in planning the RFI.

Land Use Maps

     Land uses, including residential, commercial, industrial,  agricultural, and
recreational, should also be shown on the site topographic map. This information is
useful for assessing the need for interim  corrective measures, and in evaluating
potential exposure points and the need for a Corrective Measures Study when air is
the medium of contamination.

Sources

     Information may be obtained by contacting local officials, conducting first-
hand observations, and using  a USGS quadrangle.  USGS maps indicate structures,
including dwellings, places of employment, schools, churches, cemeteries, barns,
warehouses, golf courses, and railroad tracks.  Various types of boundary lines
delineate city limits, national and state reservations, small  parks, land grants, etc.
Other land use information may be obtained by contacting local planning boards,
regional planning commissions, and State agencies. Also, the USGS has special land
use maps available for some areas. Inquiries regarding the availability of such maps
may be directed to:
         Geography Program
         Land Information and Analysis Office
         USGS-MS710
         Reston, VA 22092
         (703) 860-6045

Climatoloqical Maps

     Relevant climatological data should be identified. For example, a wind rose
graphically displays wind speed and direction.  Such information may be critical in
the characterization of an air release.  Other climatological  and meteorological
information  (e.g., precipitation and temperature)  are often  important  in
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characterizing releases to the various environmental media. Because many of these
types of meteorological and climatological information  may not be effectively
displayed on the 40 CFR Part 270 topographic map, they should be identified in a
separate map or other document.

Sources
         National Climatic Center
         Department of Commerce
         Federal Building
         Ashville, NC 28801
         (704) 258-2850

     The National Climatic Center may also refer the owner or operator to a data
collection office in the vicinity of the area of concern. In addition, local libraries and
other sources may provide local climatological data for various period storms (e.g.,
the 100-year storm), and other information.

Floodolain Maps

     The 100-year floodplam area, if applicable, should also be included on  the
facility's topographic map.  Special flooding factors (e.g., wave action) or special
flood control features included in the design, construction, operation  or
maintenance of a facility should also be noted.  The topographic map submitted
should include the boundaries of the site property in relation to floodplain areas.

Sources

     The National Flood Insurance Program  (NFIP) has prepared Flood Hazard
Boundary Maps for flood-prone areas. These maps delineate the boundaries of the
100-year floodplain.  Such maps are often included as part of the Flood Insurance
Study for a particular political  jurisdiction along a waterway.  The  U.S. Federal
Emergency Management Administration (FEMA) located in Washington, D.C. ((202)
246-2500) publishes such studies. Hydraulic analyses used to determine flood level,
community description,  and principal flood problems and flood protective measures
(provided in the flood insurance studies)  should also be included.  The USGS,  U.S.
Army Corps of Engineers, U.S. Soil Conversation Service and the Office of Coastal
Zone Management may be contacted for further floodplain information.
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Additional Information

     Other information that should be shown on the topographic map includes:

     •    Access control (fences, gates, etc.);

     •    Buildings, treatment, storage,  disposal operation areas  and  other
          structures nearby or onsite;

     •    Buried pipeline, sewers and electrical conduits;

     •    Barriers for drainage or flood control;

     •    Areas of past spills;

     •    Location  of all existing (active and inactive) solid waste management
          units;

     •    Location and nature of industrial and product process and storage units;
          and

     •    Facility design features such as run-on/runoff control systems and wind
          dispersal control systems.
                                                   «

Sources

     This information can be obtained from aerial photographs, field observations,
operating records, construction and inspection records, etc. The owner or operator
may need to locate additional site-specific information. This information may be
available on existing maps, such as:
     Geomorphology              -    surficial geology maps
                                           historical aerial photographs
                                           topographic maps
     Eolian Erosion and Deposition   -    county soil maps
                                           (historical) aerial photographic
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     Fluvial Erosion and Deposition
     Drainage Patterns
     Geologic Features
     Land Use
     Hydrologic Features
     interpretation topographic maps

floodplain maps
     county soil maps
     (historical) aerial photographic
     interpretation topographic maps

topographic maps
     county soil maps
     hydrologic maps
     aerial photgraphic interpretation

bedrock geology maps
     county soil maps
     topographic maps

zoning maps
     current aerial photos
     local conservation commission
     maps
     county soil
     recent topographic maps

hydrologic maps
     topographic maps
     wetlands maps
     well data
     aerial photographic interpretation
     local conservation commission
     maps
     Some examples of how the above information may be useful to the owner or
operator in characterizing a release are given below:


     •   Knowledge of floodplain  areas, surface water bodies, drainage patterns
         and flood  control  systems identifies potential migration  pathways for
         surface and ground water contamination;


     •   Wind speed and direction may help identify air contaminant dispersion

         areas;


     •   Injection and withdrawal wells may provide locations and information
         (e.g., influences in ground-water flow patterns)  for ground-water

         monitoring;


     •   Structures on or offsite can provide ideal locations for subsurface gas
         monitoring; and
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     •    Potential sources of contamination in close proximity to the facility may
          be revealed by investigating surrounding land use practices.

SURVEYING

     Ground surveying is a direct process for  obtaining topographic and other
terrain features in the field.  A local telephone directory should be consulted for
companies providing surveying services.

     Information that can be obtained from a ground survey includes:

     •    Facility boundary;

     •    Location of engineered structures (e.g., buildings, pipelines);

     •    Natural formations at the site (e.g., bedrock outcrops);

     •    Topographic features;

     •    Drainage patterns and ponding areas;

     •    Elevation benchmarks ("permanent"  elevation reference points that can
          be used in the future);

     •    Location of ground-water monitoring wells (e.g., surface location  and
          elevation); and

     •    Profiles of surface water bodies (e.g.,  depths of lakes/ponds) that are not
          possible by aerial means.

     The above information, obtained during a survey of the facility, may be useful
in characterizing a contaminant release through:

     •    Identification  of engineered structures that may inhibit  or promote
          contaminant migration (e.g., accumulation areas for subsurface gas);
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•    Identification of natural features at the site (e.g., barriers or pathways)
     affecting contaminant migration;

•    Topographic influences (e.g., drainage patterns and ponding areas);

•    Location of ground water or subsurface gas monitoring wells;

•    Ground-water depth  (knowledge of location and elevation of wells,
     enables measurement of ground-water depth); and

•    Depths of surface water bodies that may be useful in predicting surface
     water contamination and in determining ground-water breakout.
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                               REFERENCES


Ritchie.  1977. Mapping for Field Scientists. A. S. Barnes & Co., NY.

Todd, David. 1980.  Ground Water Hydrology, second ed. Wilev & Sons. NY.

U.S. EPA. 1982. Environmental Science and Technology. "Airborne Remote
     Sensing", Vol.  16. No. 6. 1982.

U.S. EPA. 1983. Permit Applicants' Guidance Manual for the General Facility
     Standards of 40 CFR 264. EPA SW-968.  NTIS PB 87-151064. Washington, D.C.
     20460.
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                              APPENDIX B

          MONITORING CONSTITUENTS AND INDICATOR PARAMETERS
LIST 1:    Indicator Parameters Generally Applicable to Specific Media

List 2:     40 CFR 264 Appendix IX Constituents Commonly Found in Contaminated
         Ground  Water  and Amenable  to Analysis by  EPA Method  6010-
         Inductively Coupled Plasma (ICP) Spectroscopy (Metals) and by Method
         8240 (Volatile Organics)

LIST 3:    Monitoring Constituents Potentially Applicable to Specific Media

LIST 4:    Industry Specific Monitoring Constituents
                                  B-1

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                                 LIST1

                         INDICATOR PARAMETERS
                 GENERALLY APPLICABLE TO SPECIFIC MEDIA
SOIL
     INDICATOR PARAMETERS
         Aluminum
         Boron
         Calcium
         Carbonate/bicarbonate
         Chloride
         Cobalt
         Copper
         Fluoride
         Iron
         Magnesium
         Manganese
         Nitrate (as N)
         Phosphorus
Potassium
Silica
Sodium
Soil Eh
Soil pH (Hydrogen Ion)
Strontium
Sulfate
Total Kjeldahl Nitrogen (TKN)
Total Organic Carbon (TOO*
Total Organic Halogen (TOX)*
Total Phenols
Vanadium
Zinc
     Although TOC and TOX have historically been used as indicator parameters for
     site investigations, the latest data suggests that the use of these parameters
     may not provide an adequate indication of contamination.  Both methods
     suffer precision and accuracy problems.  The normal procedure for TOC can
     strip samples of the volatile fraction, and the presence of chlorine/chloride has
     been shown to  interfere  with the TOX determination.   In  addition, the
     sensitivity of these methods (generally in the parts per million level) are often
     too high for constituents of concern.
                                   B-2

-------
                            LIST 1 (Continued)
GROUND WATER (See also 40 CFR 264, Appendix IX)
     INDICATOR PARAMETER
         Aluminum
         Boron
         Calcium
         Carbonate/bicarbonate
         Chloride
         Cobalt
         Copper
         Fluoride
         Iron
         Magnesium
         Manganese
         Nitrate (as N)
pH (Hydrogen Ion)
Potassium
Silica
Sodium
Strontium
Sulfate
Specific Conductance
Total Organic Carbon (TOO*
Total Organic Halogen (TOX)*
Total Phenols
Vanadium
Zinc
     Although TOC and TOX have historically been used as indicator parameters for
     site investigations, the latest data suggests that the  use of these parameters
     may not provide an adequate indication of contamination.  Both methods
     suffer precision and accuracy problems.  The normal procedure for TOC can
     strip samples of the volatile fraction, and the presence of chlorine/chloride has
     been shown to  interfere  with the TOX  determination.  In  addition, the
     sensitivity of these methods (generally in the parts per million level) are often
     too high for constituents of concern.
                                   B-3

-------
                            LIST 1 (Continued)


SUBSURFACE GAS

     INDICATOR PARAMETERS

         Methane
         Carbon dioxide
         Total Hydrocarbons (THC)
         Colorimetric Indicators (e.g., Draeger Tubes)
         Explosivity

AIR

     INDICATOR PARAMETERS

         Total Hydrocarbons (THC)
         Colorimetric Indicators (e.g., Draeger tubes)
                                  B-4

-------
                            LIST 1 (Continued)
SURFACE WATER

     INDICATOR PARAMETERS

         Alkalinity (mg/l as CaCOs)
         Biochemical Oxygen Demand (BOD)
         Calcium
         Chemical Oxygen Demand (COD)
         Chloride
         Dissolved Oxygen (DO)
         Dissolved sol ids
         Magnesium
         Nitrates
         Nitrites
         PH
         Salinity
         Sodium
         Specific Conductance
         Sulfate
         Suspended solids
         Temperature
         Total solids
         Total Organic Carbon (TOO*
         Total Organic Halogen (TOX)*
         Total Phenols
         Turbidity
    Although TOC and TOX have historically been used as indicator parameters for
    site investigations, the latest data suggests that the  use of these parameters
    may not provide an adequate indication of contamination.  Both methods
    suffer precision and accuracy problems.  The normal procedure for TOC can
    strip samples of the volatile fraction, and the presence of chlorine/chloride has
    been shown  to  interfere  with the TOX  determination.  In  addition, the
    sensitivity of these methods (generally in the parts per million level) are often
    too high for constituents of concern.
                                   B-5

-------
                             LIST 2
40 CFR 264 APPENDIX IX CONSTITUENTS COMMONLY FOUND IN CONTAMINATED
    GROUND WATER AND AMENABLE TO ANALYSIS BY EPA METHOD 6010 •
INDUCTIVELY COUPLED PLASMA (ICP) SPECTROSCOPY (METALS) AND BY METHOD
                    8240 (VOLATILE ORGANICS)
Common Name
Acetone
Acrolein
Acrylonitrile
Ally! chloride
Antimony
Arsenic
Barium
Benzene
Beryllium
Bromodichloromethane
Bromoform, Tribromomethane
Cadmium
Carbon disulfide
Carbon tetrachloride
Chlorobenzene
Chloroethane, Ethyl chloride
Chloroform
Chloroprene
Chromium
Cobalt
Copper
Dibromochloromethane,
Chlorodibromomethane
1,2-Dibromo-3-chloropropane, DBCP
1,2-Dibromoethane, Ethylene
dibromide
Chemical
Abstracts
Number
67-64-1
107-02-8
107-13-1
107-05-1
(total)
(total)
(total)
71-43-2
(total)
75-27-4
75-25-2
(total)
75-15-0
56-23-5
108-90-7
75-00-3
67-66-3
126-99-8
(total)
(total)
(total)
124-48-1
96-12-8
106-93-4
Method 1
8240
X
xa
xa
xb



xc

xb
xb

X
xb
xb
xb
xb
xb



xb
xb
xb
Method
6010




X
X
X

X


X






X
X
X



                              B-6

-------
LIST 2 (Continued)
Common Name
trans- 1,4-Dichloro-2-butene
Dichlorodifluoromethane
1,1-Dichloroethane
1,2-Dichloroethane, Ethylene
dichloride
1,1-Dichloroethylene, Vinylidene
chloride
.trans-1 ,2-Dichloroethylene
1,2-Dichloropropane
cis-1,3-Dichloropropene
trans-1, 3-Dichloropropene
Ethylbenzene
Ethyl methacrylate
2-Hexanone
Lead
Methacrylonitrile
Methyl bromide, Bromomethane
Methyl chloride, Chloromethane
Methylene bromide,
Dibromomethane
Methylene chloride,
Dichloromethane
Methyl ethyl ketone, MEK
Methyl Iodide, lodomethane
Methyl methacrylate
4-Methyl-2-pentanone, Methyl
isobutyl ketone
Nickel
Pentachloroethane
Chemical
Abstracts
Number
110-57-6
75-71-8
75-34-3
107-06-2
75-35-4
156-60-5
78-87-5
10061-01-5
10061-02-6
100-41-4
96-63-2
591-78-6
(total)
126-98-7
74-83-9
74-87-3
74-95-3
76-09-2
78-93-3
74-88-4
80-62-6
108-10-1
(total)
76-01-7
Method 1
8240
X
xb
xb
xb
xb
xb
xb
xb
xb
xc
xd
X

xd
xb
xb
xb
xb
xd
xb
xd
xd

X
Method
6010












X









X

       B-7

-------
                            LIST 2 (Continued)
Common Name
2-Picoline
Propionitrile, Ethyl cyanide
Pyridine
Selenium
Silver
Styrene
1,1,1 ,2-Tetrachloroethane
1 , 1 ,2,2-Tetrachloroethane
Tetrachloroethylene,
Perchloroethylene,
Tetrachloroethene
Thallium
Toluene
1,1,1-Trichloroethane, Methyl
chloroform
1 , 1 ,2-Trichloroethane
Trichloroethylene, Trichloroethene
Trichlorofluoromethane
1 ,2,3-Trichloropropane
Vanadium
Vinyl Acetate
Vinyl Chloride
Xylene (total)
Zinc
Chemical
Abstracts
Number
109-06-8
107-12-0
110-86-1
(total)
(total)
100-42-5
630-20-6
79-34-5
127-18-4
(total)
108-88-3
71-55-6
79-00-5
79-01-6
96-18-4
96-18-4
(total)
108-05-4
75-01-4
1330-20-7
(total)
Method 1
8240
X
xd
x«


xc
xb
xb
xb

xc
X
xb
xb
xb
xb

X
xb
xc

Method
6010



X
X




X






X



X
NOTE:   Method 6010 is not recommended for Mercury and Tin.

1  Caution, these are representative methods and may not always be the most
   suitable for a given application.

a  Method 8030 is also suggested.
b  Method 8010 is also suggested.
c  Method 8020 is also suggested.
d  Method 8015 is also suggested.
e  Method 8070 is also suggested.
                                  B-8

-------
                            LIST 3
MONITORING CONSTITUENTS POTENTIALLY APPLICABLE TO SPECIFIC MEDIA
Common Name
Acetonitrile
Acetophenone
2-Acetylaminofluorene
Acetyl chloride
1-Acetyl-2-thiourea
Acrolein
Acrylamide
Acrylonitrile
Aflatoxins
Aldicarb
Aldrln
Ally! alcohol
Ally! chloride
Aluminum phosphide
4-Aminobiphenyl
5-(Aminomethyl)-3-isoxazolol
4-Aminopyridine
Amitrole
Ammonium vanadate
Aniline
Antimony and compounds,
N.O.S.1
Aramite
Arsenic and compounds, N.O.S.1
Arsenic acid
Arsenic pentoxide
Arsenic trioxide
Auramine
Azaserine
Barium and compounds, N.O.S.1
Barium cyanide
Benz(c)acridine
Chemical
Abstracts
No.
75-05-8
98-86-2
53-96-3
75-36-5
591-08-2
107-02-8
79-06-1
107-13-1
1402-68-2
116-06-3
309-00-2
107-18-6
107-05-1
20859-73-8
92-67-1
2763-96-4
504-24-5
61-82-5
7803-55-6
62-53-3
7440-36-0
140-57-8
7440-38-2
7778-39-4
1303-28-2
1327-53-3
492-80-8
115-02-6
7440-39-3
542-62-1
225-51-4
Ground
Water*
X
X
X


X

X


X

X

X




X
X
X
X





X


Surface
Water2
X
X
X


X

X


X

X

X




X
X
X
X





X


Soil3
X
X
X


X

X


X

X .

X




X
X
X
X
X
X
X


X
X

Subsurface
Gas*































Air
X
X



X
X
X

X









X


X








                             B-9

-------
LIST 3 (continued)
Common Name
Benz(a)anthracene
Benzal I chloride
Benzene
Benzenearsomcacid
Benzidine
Benzo(b)fluoranthene
Benzo(j)fluoranthene
Benzo(a)pyrene
p-Benzoquinone
Benzotrichloride
Benzyl chloride
Beryllium and compounds,
N.O.S.1
Bis(2-chloromethoxy)ethane
Bis(2-chloroethyl) ether
Bis(2-chloroisopropyl) ether
Bis(chloromethyl) ether
Bis(2-ethylhexyl)phthalate
Bromoacetone
Bromoform
4-Bromophenyl phenyl ether
Brucine
Butyl benzyl phthalate
Cacodylicacid
Cadmium and compounds,
N.O.S.'
Calcium chromate
Calcium cyanide
Carbon disulfide
Carbon oxyfluoride
Carbon tetrachloride
Chloral
Chemical
Abstracts
No.
56-55-3
98-87-3
71-43-2
98-05-5
92-87-5
205-99-2
205-82-3
50-32-8
106-51-4
98-07-7
100-44-7
7440-41-7
111-91-1
111-44-4
39638-32-9
542-88-1
117-81-7
589-31-2
75-25-2
101-55-3
357-57-3
85-68-7
75-60-5
7440-43-9
13765-19-0
592-01-8
75-15-0
353-50-4
56-23-5
75-87-6
Ground
Water*
X

X


X

X



X
X
X
X

X

X
X

X

X


X

X

Surface
Water2
X

X


X

X



X
X
X
X

X

X
X

X

X


X

X

Soil3
X
X
X

X
X

X
X
X
X
X
X
X
X
X
X

X
X

X

X
X
X
X

X

Subsurface
Gas*


X











X











X

X

Air


X






X
X




X
X

X




X


X
X
X

      B-10

-------
LIST 3 (continued)
Common Name
Chlorambucil
Chlordane, alpha and gamma
isomers
Chlorinated benzenes, N.O.S.1
Chlorinated ethanes, N.O.S.1
Chlorinated fluorocarbons,
N.O.S.1
Chlorinated naphthalene,
N.O.S.1
Chlorinated phenol, N.O.S.1
Chlornaphazine
Chloroacetaldehyde
Chloroalkyl ethers, N.O.S.1
p-Chloroaniline
Chlorobenzene
Chlorobenzilate
p-Chloro-m-cresol
1 -Chloro-2,3-epoxypropane
2-Chloroethyl vinyl ether
Chloroform
Chloromethyl methyl ether
beta-Chloronaphthalene
o-Chlorophenol
Mo-Chlorophenyl) thiourea
Chloroprene
3-Chloropropionitrile
Chromium and compounds,
N.O.S.i
Chrysene
Citrus red No. 2
Coal tars
Copper cyanide
Creosote
Cresols(Cresylicacid)
Crotonaldehyde
Chemical
Abstracts
No.
305-03-3
57-74-9





494-03-1
107-20-0

106-47-8
108-90-7
510-15-6
59-50-7
106-89-8
110-75-8
67-66-3
107-30-2
91-58-7
95-57-8
5344-82-1
126-99-8
542-76-7
7440-47-3
218-01-9
6358-53-8
8005-45-2
544-92-3
8001-58-9
1319-77-3
4170-30-3
Ground
Water*

X
X
X

X




X
X
X
X


X

X
X

X

X
X




X

Surface
Water2

X
X
X

X




X
X
X
X


X

X
X

X

X
X




X

Soil3

X
X
X

X
X



X
X
X
X

X
X

X
X

X
X
X
X

X
X
X
X

Subsurface
Gas*


X
X







X




X














Air

X
X
X
X

X



X
X


X

X


X

X

X



X

X
X
      B-11

-------
LIST 3 (continued)
Common Name
Cyanides (soluble salts and
complexes) N.O.S.1
Cyanogen
Cyanogen bromide
Cyanogen chloride
Cycasin
2-Cyclohexyl-4,6-di nitrophenol
Cyclophosphamide
2,4-0, salts and esters
Daunomycin
000
DDE
DDT
Oiallate
Dibenz(a,h)acridine
Dibenz(a,j)acridine
Dibenz(a,h)anthracene
7H-Oibenzo(c,g)carbazole
Dibenzo(a,e)pyrene
Dibenzo(a,h)pyrene
Dibenzo(a,i)pyrene
1 ,2-Dibromo-3-chloropropane
Di butyl phthalate
o-Dichlorobenzene
m-Dichlorobenzen*
p-Dichlorobenzene
Dichlorobenzene, N.O.S.1
3,3'-Oichlorobenzidine
1 ,4-Dichloro-2-butene
Dichlorodifluoromethane
1,2-Dichloroethylene
Chemical
Abstracts
No.

460-19-5
506-68-3
506-77-4
14901-08-7
131-89-5
50-18-0
94-75-7
20830-81-3
72-54-8
72-55-9
50-29-3
2303-16-4
226-36-8
224-42-0
53-70-3
194-59-2
192-65-4
189-64-0
189-55-9
96-12-8
84-74-2
95-50-1
541-73-1
106-46-7
25821-22-6
91-94-1
764-41-0
75-71-8
156-60-5
Ground
Water*
X






X

X
X
X
X


X




X
X
X
X
X
X
X
X
X
X
Surface
Water2
X






X

X
X
X
X


X




X
X
X
X
X
X
X
X
X
X
Soil3
X






X

X
X
X
X


X

X
X
X
X
X
X
X
X
X
X
X
X
X
Subsurface
Gas*




























X
X
Air
X
X





X














X
X
X
X

X
X

      B-12

-------
LIST 3 (continued)
Common Name
Dichloroethylene, N.O.S.1
1,1-Dichloroethylene
2,4-Dichlorophenol
2,6-Dichlorophenol
Dichlorophenylarsine
Dichloropropane, N.O.S.1
Dichloropropanol, N.O.S.1
Dichloropropene, N.O.S.1
1 ,3-Dichloropropene
Dieldrin
1 ,2,3,4-Diepoxybutane
Diethylarsine
1 ,4-Diethyleneoxide
N.N'-Diethylhydrazine
O,0-Diethyl S-
methyldithiophosphate
Diethyl-p-nitro phenyl
phosphate
Diethylphthalate
0,0-Diethyl 0-pyrazinyl
phosphorothioate
Diethylstilbesterol
Dihydrosafrole
3,4-Dihydroxy-alpha-
(methylamino)methyl benzyl
alcohol
Di isopropyl f I uorophosphate
(DFP)
Dimethoate
3,3'-Dimethoxybenzidine
p- Oi methoxymi noazobenzene
7,12-
Oi methyl benz(a)anthracene
3,3'-Dimethylbenzidine
Dimethylcarbamoyl chloride
1,1-Dimethylhydrazine
1,2-Oimethylhydrazine
Chemical
Abstracts
No.
25323-30-2
75-35-4
120-83-2
87-65-0
696-28-6
26638-19-7
26545-73-3
26952-23-8
542-75-6
60-57-1
1464-53-5
692-42-2
123-91-1
1615-80-1
3288-58-2
311-45-5
84-66-2
297-97-2
56-53-1
94-58-6
329-65-7
55-91-4
60-51-5
119-90-4
60-11-7
57-97-6
119-93-7
79-44-7
57-14-7
540-73-8
Ground
Water*
X
X
X
X

X

X
X
X


X



X
X




X
X
X
X
X



Surface
Water2
X
X
X
X

X

X
X
X


X



X
X




X
X
X
X
X



SoiP
X
X
X
X

X

X
X
X


X


X
X
X




X
X
X
X
X



Subsurface
Gas*






























Air
X
X



X

X
X



X



X











X

      B-13

-------
LIST 3 (continued)
Common Name
alpha, alpha-
Dimethyl phenethyl ami ne
2,4-Di methyl phenol
Dimethylphthalate
Dimethyl sulfate
Dinitrobenzene, N.O.S.1
4,6-Dinitro-o-cresol and salts
2,4-Dinitrophenol
2,4-Dinitrotoluene
2,6-Dinitroioluene
Dinoseb
Di-n-octylphthalate
Diphenylamine
1 ,2-Diphenylhydrazine
Di-n-propylnitrosamine
Disulfoton
Dithioburet
Endosulfan
Endothal
Endrin
Ethyl carbamate (urethane)
Ethyl cyanide
Ethylenebisdithiocarbamic acid,
salts, and esters
Ethylenedi bromide
Ethylene dichloride
Ethylene gfycol monoethyl
ether
Ethyleneimine
Ethylene oxide
Ethylenethiourea
Ethylidene dichloride
Ethyl methacrylate
Chemical
Abstracts
No.
122-09-8
105-67-9
131-11-3
77-78-1
25154-54-5
534-52-1
51-28-5
121-14-2
606-20-2
88-85-7
117-84-0
122-39-4
122-66-7
621-64-7
298-04-4
541-53-7
115-29-7
145-73-3
72-20-8
51-79-6
107-12-0
111-54-6
106-93-4
107-06-2
110-80-5
151-56-4
75-21-8
96-45-7
75-34-3
97-63-2
Ground
Water*
X
X
X

X
X
X
X
X
X
X
X

X
X

X

X










X
Surface
Water2
X
X
X

X
X
X
X
X
X
X
X

X
X

X

X










X
Soil3
X
X
X

X
X
X
X
X
X
X
X
X
X
X

X

X

X








X
Subsurface
Gas*























X




X

Air

X





X




X









X
X

X
X

X

      B-14

-------
LIST 3 (continued)
Common Name
Ethylmethane sulfonate
Famphur
Fluoranthene
Flourine
Fluoroacetamide
Fluoroacetic acid, sodium salt
Formaldehyde
Glycidylaldehyde
Halqmethane, N.O.S.i
Heptachlor
Heptachlor epoxide
Hexachlorobenzene
Hexachlorobutadiene
Hexachlorocvclopentadiene
Hexachlorodibenzo-p-dioxins
Hexachlorodibenzofurans
Hexachloroethane
Hexachlorophene
Hexachloropropene
H exaethy 1 tetra phosphate
Hydrazine
Hydrogen cyanide
Hydrogen fluoride
Hydrogen sulfide
lndeno(1,2,3cd)pyrene
Irondextran
Isobutyl alcohol
Isodrin
Isosafrole
Kepone
Lasiocarpine
Lead and compounds, N.O.S.1
Lead acetate
Chemical
Abstracts
No.
62-50-0
52-85-7
206-44-0
7782-41-4
640-19-7
62-74-8
50-00-0
765-34-4

76-44-8
1024-57-8
118-74-1
87-68-3
77-47-4


67-72-1
70-30-4
1888-71-7
757-58-4
302-01-2
74-90-8
7664-39-3
7783-06-4
193-39-5
9004-66-4
78-83-1
465-73-6
120-58-1
143-50-0
303-34-4
7439-92-1
301-04-2
Ground
Water*
X
X
X





X
X
X
X
X
X
X
X
X
X
X





X

X
X
X
X

X

Surface
Water2
X
X
X





X
X
X
X
X
X
X
X
X
X
X





X

X
X
X
X

X

Soi|3
X
X
X
X




X
X
X
X
X
X
X
X
X
X
X




X
X

X
X
X
X

X
X
Subsurface
Gas*








X














X









Air






X

X
X


X



X



X
X

X


X




• x

      B-15

-------
LIST 3 (continued)
Common Name
Lead phosphate
Lead subacetate
Lindane
Maleic anhydride
Maleic hydrazide
Malonitrile
Melphalan
Mercury fulminate
Mercury and compounds N.O.S.1
Methacrylonitrile
Methapyrilene
Methomyl
Methoxychlor
Methyl bromide
Methyl chloride
Methychlorocarbonate
Methyl chloroform
3-Methylcholanthrene
4,4',Methylenebis(2-
chloroaniline)
Methylene bromide
Methylene chloride
Methyl ethyl ketone (MEK)
Methyl ethyl ketone peroxide
Methyl hydrazine
Methyl iodide
Methyl isocyanate
2-Methyllactonitrile
Methyl methacrylate
Methyl methanesulfonate
Methyl parathion
Chemical
Abstracts
No.
7446-27-7
1335-32-6
58-89-9
108-31-6
123-33-1
109-77-3
148-82-3
628-86-4
7439-97-6
126-98-7
91-80-5
16752-77-5
72-43-5
74-83-9
74-87-3
79-22-1
71-55-6
56-49-5
101-14-4
74-95-3
75-09-2
78-93-3
1338-23-4
60-34-4
74-88-4
624-83-9
75-86-5
80-62-6
66-27-3
298-00-0
Ground
Water*


X





X
X
X

X
X
X

X
X
X
X
X
X


X


X
X
X
Surface
Water2


X





X
X
X

X
X
X

X
X
X
X
X
X


X


X
X
X
Soil3
X

X


X


X
X
X

X
X
X

X
X
X
X
X
X
X
*
X


X
X
X
Subsurface
Gas4
















X



X









Air



X




X
X



X
X

X



X
X
X

X
X
X
X


      B-16

-------
LIST 3 (continued)
Common Name
Methyl thiouracil
MitomycinC
MNNG
Mustard gas
Naphthalene
1,4-Naphthoquinone
alpha-Naphthylamine
Beta-Naphthylamine
alpha-Napththylthiourea
Nickel and compounds, N.O.S.1
Nickel carbonyl
Nickel cyanide
Nicotine and salts
Nitric oxide
p-Nitroaniline
Nitrobenzene
Nitrogen dioxide
Nitrogen mustard and
hydrochloridesalt
Nitrogen mustard N-oxide and
hydrochloridesalt
Nitroglycerin
p-Nitrophenol
2-Nitropropane
4>Nitroquinoline-1-oxide
Nitrosamine, N.O.S.1
N-Nitrosodi-n-butylamine
N-Nitrosodiethanolamine
N-Nitrosodiethylamine
N-Nitrosodimethylamine
N-Niroso-N-ethyl urea
N-Nitrosomethylethylamine
N-Nitroso-N-methylurea
Chemical
Abstracts
No.
56-04-2
50-07-7
70-25-7
505-60-2
91-20-3
130-15-4
134-32-7
91-59-8
86-88-4
7440-02-0
13463-39-3
557-19-7
54-11-5
10102-43-9
100-01-6
98-95-3
10102-44-0
51-75-2
126-85-2
55-63-0
100-02-7
79-46-9
56-57-5
35576-91-1
924-16-3
1116-54-7
55-18-5
62-75-9
759-73-9
10595-95-6
684-93-5
Ground
Water*




X
X
X
X

X




X
X




X

X
X
X

X
X

X

Surface
Water2




X
X
X
X

X




X
X




X

X
X
X

X
X

X

SOJI3




X
X
X
X

X

X

X
X
X
X
X


X

X
X
X

X
X

X

Subsurface
Gas4































Air




X








X

X



X
X










      B-17

-------
LIST 3 (continued)
Common Name
N-Nitroso-N-methylurethane
N-Nitrosomethylvinylamine
N-Nitrosomorpholine
N-Nitrosonornicotine
N-Nitrosopiperidine
Nitrosopyrolidine
N-Nitrososarcosine
5-Nitro-o-toluidine
Octamethyl pryophosphoramide
Osmium tetroxide
Paraldehyde
Parathion
Pentachlorobenzene
Pentachlorodibenzo p dioxins
Pentachlorodibenzofurans
Pentachloroethane
Pentachloronitrobenzene
(PCNB)
Pentachlorophenol
Phenacetin
Phenol
Phenylenediamine
Phenyl mercury acetate
Phenylthiourea
Phosgene
Phosphine
Phorate
Phthalic acid esters, N.O.S.1
Phthalic anhydride
2-Picoline
Polychlorinated biphenyls
N.O.S.1
Potassium cyanide
Potassium silver cyanide
Pronamide
Chemical
Abstracts
No.
615-53-2
4549-40-0
59-89-2
16543-55-8
100-75-4
930-55-2
13256-22-9
99-55-8
152-16-9
20816-12-0
123-63-7
56-38-2
608-93-5


76-01-7
82-68-8
87-86-5
62-44-2
108-95-2
25265-76-3
62-38-4
103-85-5
75-44-5
7803-51-2
298-02-2

85-44-9
109-06-8

151-50-8
506-61-6
23950-58-5
Ground
Water*


X

X
X

X



X
X
X
X
X
X
X
X
X





X


X
X


X
Surface
Water2


X

X
X

X



X
X
X
X
X
X
X
X
X





X


X
X


X
Soi|3


X

X
X

X



X
X
X
X
X
X
X
X
X





X


X
X
X
X
X
Subsurface
Gas*

































Air









X

X
X


X

X

• x



X
X
X

X

X



      B-18

-------
LIST 3 (continued)
Common Name
1,3-Propanesultone
n-Propylamine
Propargyl alcohol
Propylenedichloride
1,2-Propylenimine
Propylthiouracil
Pyridine
Reserpine
Resorcinol
Saccharin and salts
Safrole
Selenium dioxide
Selenium and compounds,
N.O.S.
Selenium sulfide
Selenourea
Silver and compounds, N.O.S.1
Silver cyanide
Silvex(2,4,S-TP)
Sodium cyanide
Streptozotocin
Strontium sulfide
Strychnine and salts
TCDD
1 ,2,4,5- Tetrachlorobcnzene
Tetrachlorodibenzo-p-dioxins
Tetrachlorodibenzofurans
Tetrachloroethane, N.O.S.1
1,1,1 ,2-Tetrachloroethane
1 , 1 ,2,2-Tetrachloroethane
Tetrachloroethylene
Chemical
Abstracts
No.
1120-71-4
107-10-8
107-19-7
78-87-5
75-55-8
51-52-5
110-86-1
50-55-5
108-46-3
81-07-2
94-59-7
7783-00-8
7782-49-2
7446-34-6
630-10-4
7440-22-4
506-64-9
93-72-1
143-33-9
18883-66-4
1314-96-1
57-24-9
1746-01-6
95-94-3


25322-20-7
630-20-6
79-34-5
127-18-4
Ground
Water*






X



X

X


X

X




X
X
X
X
X
X
X
X
Surface
Water2






X



X

X


X

X




X
X
X
X
X
X
X
X
Soi|3






X

X

X

X
X

X
X
X


X

X
X
X
X
X
X
X
X
Subsurface
Gas*


























X

X
X
Air



X


X
X
X











'

X






X
      B-19

-------
LIST 3 (continued)
Common Name
2,3,4,6-Tetrachlorophenol
Tetraethyldithiopyrophosphate
Tetraethyl lead
Tetraethy 1 pyrophosphate
Tetranitromethane
Thallium and compounds,
N.O.S.1
Thallic oxide
Thallium (1) acetate
Thallium (1) carbonate
Thallium (1) chloride
Thallium (1) nitrate
Thallium selenite
Thallium (1)sulfate
Thioacetamide
Thiofanox
Thiomethanol
Thiophenol
Thiosemicarbazide
Thiourea
Thiram
Toluene
Toluenediamine
2,4-Toluenediamin«
2,6-Toluenediamin«
3,4- Toluenediamine
Toluene diisocyanate
p-Toluidine
o-Toluidine hydrochloride
Toxaphene
1 ,2.4-Trichlorobenzene
1 , 1 ,2-Trichloroethane
Chemical
Abstracts
No.
58-90-2
3689-24-5
78-00-2
107-49-3
509-14-8
7440-28-0
1314-32-5
563-68-8
6533-73-9
7791-12-0
10102-45-1
12039-52-0
10031-59-1
62-55-5
39196-18-4
74-93-1
108-98-5
79-19-6
62-56-6
137-26-8
108-88-3
25376-45-8
95-80-7
823-40-5
496-72-0
584-84-9
106-49-0
636-21-5
8001-35-2
120-82-1
79-00-5
Ground
Water*
X
X



X














X







X
X
X
Surface
Water2
X
X



X














X







X
X
X
Soil3
X
X

X
X
X
X
X
X
X
X
X
X



X



X




X


X
X
X
Subsurface
Gas*




















X









X
Air


X










X

X




X

X


X


X
X

      B-20

-------
                                        LISTS (continued)
Common Name
Trichloroethylene
Trichlpromethanethiol
Trichloromonofluoromethane
2,4,5-Trichlorophenol
2,4,6-Trichlorophenol
2,4,5-T
Trichloropropane, N.O.S.1
1 ,2,3-Trichloropropane
0,0,0-Triethylphosphorothioate
sym-Trinitrobenzene
Tris(,1-aziridinyl)phosphine
sulfide
Tris(2,3-
dibromopropyl)phosphate
Trypan blue
Uracil mustard
Vanadium pentoxide
Vinyl chloride
Warfarin
Zinc cyanide
Zinc phosphide
Chemical
Abstracts
No.
79-01-6
75-70-7
75-69-4
95-95-4
88-06-2
93-76-5

96-18-4
126-68-1
99-35-4
52-24-4
126-72-7
72-57-1
66-75-1
1314-62-1
75-01-4
81-81-2
557-21-1
1314-84-7
Ground
Water*
X

X
X
X
X
X
X
X
X





X



Surface
Water2
X

X
X
X
X
X
X
X
X





X



Soil3
X
X
X
X
X
X
X
X
X
X




X
X

X
X
Subsurface
Gas^
X














X



Air
X





X
X






X
X



*  See also 40 CFR 264, Appendix IX.

1  The abbreviation N.O.S. (not otherwise specified) signifies those members of the general class not
   specifically listed by name.

2  Applies to the water column only. Additional constituents may be of concern if sediment and/or biota are
   to be sampled and subjected to analysis (See Section 13).

3  Includes both saturated and unsaturated soils. Some of these are gases at ambient temperature and
   pressure which may be present in wet or saturated soils. Degradation as a result of chemical, biological or
   physical processes, may result in decreasing concentrations of constituents over time, and is dependent on
   moisture content as well as other factors.

4  Compounds indicated are those which may be present within a carrier gas (e.g., methane).
                                               B-21

-------
                             LIST 4

          INDUSTRY SPECIFIC MONITORING CONSTITUENTS


   REFERENCES FOR INDUSTRY SPECIFIC MONITORING CONSTITUENTS

1.    40CFR 122, National Pollutant Discharge Elimination System

2.    U.S. EPA, Development Document for Effluent Limitation Guidelines and
     Standards for the ... Point Source Category.
     (Total of 30 Industries)

3.    U.S. EPA, 1980, Treatability Manual. Volume I. Treatability Data

4.    U.S. EPA Regional Offices for Industry Specific Data.
                              B-22

-------
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                                               B-23

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-------
Corrosive, reactive, or explosive wastes can also damage soil sampling equipment or
cause fires and explosions.  Appropriate precautions to  prevent such incidents
include having an adequate health and safety plan in place, using explosimeters or
organic vapor detectors as early-warning  devices, and  employing geophysical
techniques to  help identify buried objects (e.g., to locate  buried  drums).  All
contaminated soil samples should be handled as if they contain dangerous levels of
hazardous wastes or constituents.

     Identity and composition  of  contaminants-The owner or operator should
identify and provide approximate  concentrations for any constituents  of concern
found in the original waste and, if available, in leachate from any releasing unit.
Identification of other (non-hazardous) waste components that may  affect the
behavior of hazardous constituents or may  be used as indicator parameters is also
recommended.  Such components  may form a  primary leachate causing transport
behavior different from water and may also mobilize hazardous constituents bound
to the soil. Estimations of transport behavior can help to focus the determination of
sampling locations.
     Physical state of contaminants--The physical state (solid, liciuid, or gas) of the
contaminants in the waste and soil should be determined by inspection or from site
operating records.  Sampling can then be  performed at locations  most likely to
contain the contaminant.

     Viscosity-The viscosity of any bulk liquid wastes should be determined to
estimate potential mobility in soils.  A liquid with a lower viscosity will generally
travel faster than one of a higher viscosity.

     pJH-Bulk liquid pH may affect contaminant transport in at least two ways:
(1) it may alter the chemical form of acids and bases, metal salts, and  other metal
complexes, thereby altering their water solubility and soil sorption properties, and
(2) it may alter the soil chemical or physical makeup, leading to changes in sorptive
capacity or permeability. For example, release of acidic (low pH) wastes in a karst
(e.g., limestone) environment can lead to the formation of solution  channels. See
Section 10.3 for more information on karst formations.
                                   9-11

-------
     Dissociation constant (pKa)--For compounds that are appreciably ionized
within the expected range of field pH values, the pKa of the compound should be
determined. Ionized compounds have either a positive or negative charge and are
often highly soluble in water; therefore, they are generally more mobile than in
their neutral forms when dissolved.  Compounds that may ionize include organic
and inorganic acids and bases, phenols, metal salts, and other inorganic complexes.
Estimated  contaminant concentration isopleths  can  be plotted  with this
information and can be used in determining sampling locations.

     Density--The density of major  waste  components should  be determined,
especially for liquid wastes. Components with a density greater than water, such as
carbon  tetrachloride,  may migrate through soil  layers more quickly than
components less dense than water, such as toluene, assuming viscosity  to  be
negligible.  Density differences become more significant when contaminants reach
the saturated zone.  Here they may sink, float, or be dissolved in the ground water.
Some fraction of a "sinker" or "floater" may also be dissolved in the ground water.

     Water solubility-This chemical property influences constituent mobility and
sorption of chemicals to soil particle surfaces. Highly water-soluble compounds are
generally very mobile in  soil and ground water.  Liquid wastes that have low
solubility in water may form a distinct phase in the soil  with flow behavior different
from that of water.  Additional sampling  locations may be needed to characterize
releases of insoluble species.

     Henry's Law constant-This  parameter  indicates  the partitioning  ratio of a
chemical between air and water phases at equilibrium. The larger the  value of a
constituent's Henry's Law Constant, the greater is the tendency of the constituent
to volatilize from water surrounding soil particles into soil pore spaces or into
above-ground air. The Henry's Law Constant should be considered in assessing the
potential for inter-media transport of constituents in soil gas to the air. Therefore,
this topic is also discussed in the Subsurface Gas and Air sections (Sections 11 and
12, respectively).  Information on this parameter can help in determining which
phases to sample in the soil investigation.

     Octanol/Water partition coefficient (K^-The characteristic distribution of a
chemical between an aqueous phase and an organic phase (octanol) can  be used to
                                   9-12

-------
predict the sorption of organic chemicals onto soils. It is frequently expressed as a
logarithm (log Kow).  In transport models, K0w is frequently converted to K0o a
parameter that takes into account the organic content of the soil. The empirical
expression used to calculate K0< is: Koc = 0.63 Kowfoc, where f0c is the fraction by
weight of organic carbon in the soil. The higher the value of Kow (or K0c)  the
greater the tendency of a constituent to adsorb to soils  containing appreciable
organic carbon. Consideration of this parameter will also help in determining which
phases to sample in the soil investigation.

     Biodeqradabilitv-There is a  wide variety of microorganisms that may  be
present in the soil. Generally, soils that have significant amounts of organic matter
will contain a higher microbial  population,  both  in density  and  in diversity.
Microorganisms are responsible for the decay  and/or transformation of organic
materials and thrive mostly in the "A" (uppermost) soil  horizon where carbon
content is generally highest and where aerobic digestion occurs.  Because some
contaminants can serve as organic nutrient sources that soil microorganisms will
digest as food, these contaminants will be profoundly affected within organic soils.
Digestion may lead to complete decomposition, yielding carbon dioxide and water,
but more often results in partial  decomposition and transformation into other
substances. Transformation products will likely have different physical, chemical or
toxicological characteristics than the original contaminants.   These products may
also be hazardous constituents (some with higher toxicities) and should therefore
be considered in  developing monitoring  programs.  The decomposition  or
degradation rate depends on various factors, including:

     •   The molecular  structure of the contaminants.   Certain manmade
         compounds (e.g., PCBs and chlorinated pesticides) are relatively
         nondegradable (or persistent), whereas others (e.g., methyl alcohol) are
         rapidly consumed by bacteria.  The  owner or operator should consult
         published lists of compound degradability, such as Table 9-4, to estimate
         the persistence of waste constituents in soil. This table provides relative
         degradabilities  for some organic  compounds  and can be an aid  to
         identifying appropriate monitoring constituents  and indicator
         parameters.  It may be especially  useful for  older releases where
         degradation may be  a  significant  factor.  For  example, some of the
         parent  compounds that are relatively degradable  (see  Table 9-4) may
                                  9-13

-------
TABLE 9-4. BODs/COD RATIOS FOR VARIOUS ORGANIC COMPOUNDS*
Compound
RELATIVELY UNDEGRADABLE
Butane
Butyl ene
Carbon tetrachlonde
Chloroform
1,4-Dioxane
Ethane
Heptane
Hexane
Isobutane
isobutylene
Liquefied natural gas
Liquefied petroleum gas
Methane
Methyl bromide
Methyl chloride
Monochlorodifluoromethane
Nitrobenzene
Propane
Propylene
Propylene oxide
Tetrach I oroethy I ene
Tetrahydronaphthalene
1 Pentrene
Ethylene dichloride
1 Octene
Morpholine
Ethylenediaminetetracetic acid
Triethanolamine
o-Xylene
m-Xylene
Ethyl benzene
MODERATELY DEGRADABLE
Ethyl ether
Sodium alkylbenzenesulfonates
Monoisopropanolamine
Gas oil (cracked)
Gasolines (various)
Ratio

-0
-0
-0
-0
~0
-0
-0
-0
-0
-0
-0
-0
-0
-0
-0
-0
-0
-0
-0
-0
-0
-0
< 0.002
0.002
>0.003
< 0.004
0.005
< 0.006
< 0.008
< 0.008
< 0.009

0.012
-0.017
<0.02
-0.02
-0.02
Compound
MODERATELY DEGRADABLE
(CONTD)
Mineral spirits
Cyclohexanol
Acrylonitrile
Nonanol
Undecanol
Methyl ethylpyridine
1-Hexene
Methyl isobutyl ketone
Diethanolamine
Formic acid
Styrene
Heptanol
sec-Butyl acetate
n-Butyl acetate
Methyl alcohol
Acetonitrile
Ethylene glycol
Ethylene glycol monoethyl ether
Sodium cyanide
Linear alcohols (12-15 carbons)
Ally! alcohol
Dodecanol
RELATIVELY DEGRADABLE
Valeraldehyde
n-Decyl alcohol
p-Xylene
Urea
Toluene
Potassium cyanide
Isopropyl acetate
Amy) acetate
Chlorobenzene
Jet fuels (various)
Kerosene
Range oil
Glycerine
Adiponitrile
Ratio

-0.02
0.03
0.031
>0.033
<0.04
0.04-0.75
< 0.044
<0.044
< 0.049
0.05
>0.06
<0.07
0.07-0.23
0.07-0.24
0.07-0.73
0.079
0.081
<0.09
<0.09
>0.09
0.091
0.097

<0.10
>0.10
<0.11
0.11
<0.12
0.12
<0.13
0.13-0.34
0.15
-0.15
-0.15
-0.15
<0.16
0.17
                        9-14

-------
                              TABLE 9-4. (Continued)
Compound
RELATIVELY DEGRADABLE
(cowro.)
Furfural
2-Ethyl-3-propyl acrolei n
Methyl ethyl py rid i ne
Vinyl acetate
Diethylene glycol monomethyl
ether
Napthalene (molten)
Dibutyl phthalate
Hexanol
Soybean oil
Paraformaldehyde
n-Propyl alcohol
Methyl methacrylate
Acrylic acid
Sodium alkylsul fates
Triethylene glycol
Acetic acid
Acetic anhydride
Ethylenediamine
Formaldehyde solution
Ethyl acetate
Octanol
Sorbitol
Benzene
n-Butyl alcohol
Propionaldehyde
n-Butyraldehyd«

Ratio

0.17-0.46
<0.19
<0.20
<0.20
<0.20
<0.20
0.20
-0.20
-0.20
0.20
0.20-
0.63 < 0.24
<0.24
0.26
0.30
0.31
0.31-0.37
>0.32
<0.35
0.35
<0.36
0.37
<0.38
<0.39
0.42-0.74
<0.43
<0.43

Compound
RELATIVELY DEGRADABLE
(CONTD.)
Ethyfeneimme
Monoethanolamine
Pyridine
Dimethylformamide
Dextrose solution
Corn syrup
Maleic anhydride
Propionic acid
Acetone
Aniline
Isopropyl alcohol
n-Amyl alcohol
Isoamyl alcohol
Cresols
Crotonaldehyde
Phthalic anhydride
Benzaldehyde
Isobutyl alcohol
2,4-Oichlorophenol
Tallow
Phenol
Benzoic acid
Carbolic acid
Methyl ethyl ketone
Benzoyl chloride
Hydrazine
Oxalic acid
Ratio

0.46
0.46
0.46-0.58
0.48
0.50
-0.50
>0.51
0.52
0.55
0.56
0.56
0.57
0.57
0.57-0.68
<0.58
0.58
0.62
0.63
0.78
-0.80
0.81
0.84
0.84
0.88
0.94
1.0
1.1
*Source:   U.S. EPA 1985. Handbook: Remedial Action at Waste Disposal Sites (Revised).
          EPA/625/6-85/006. NTIS PB82-239054. Office of Emergency and Remedial Response.
          Washington, D.C. 20460.
                                       9-15

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have been reduced to carbon dioxide and water or other decomposition
products prior to sampling. Additional information on degradability can
be found in Elliott and Stevenson, 1977; Sims et al, 1984; and U.S. EPA,
1985. See Section 9.8 for complete citations for these references.

Moisture content. Active biodegradation does not  generally occur in
relatively dry soils or in some types of saturated soils, such as those that
are saturated for long periods of time, as in a bog.

The  presence or absence of oxygen in the soil.   Most degradable
chemicals decompose  more  rapidly  in aerobic (oxygenated) soil.
Although unsaturated surficial  soils are generally aerobic, anaerobic
conditions may exist under landfills or other units.   Soils that are
generally saturated year round are relatively  anaerobic (e.g., as in a bog);
however, most saturated soils contain enough oxygen to support active
biodegradation.  Anaerobic biodegradation, however, can also be
significant in some cases.  For example, DOT degrades more rapidly under
anaerobic conditions than under aerobic conditions.

Microbial adaptation or  acclimation.  Biodegradation depends on the
presence in the soil  of organisms capable of metabolizing the waste
constituents. The large and varied population of microorganisms in soil
is likely to have some potential for favorable  growth  using organic
wastes and constituents as nutrients.  However,  active metabolism
usually requires a period of adaptation or  acclimation that can range
from several  hours  to several  weeks  or months, depending on the
constituent or waste properties and the microorganisms involved.

The availability of contaminants to micro-organisms. Releases that occur
below the upper 6 to 8 inches of soil are less likely to be affected because
fewer rrjicro-organisms exist there. In addition, compounds with greater
aqueous solubilities  are generally more available for degradation.
However,  high  solubility also  correlates directly to the  degree of
mobility. If relatively permeable soil conditions prevail and constituents
migrate rapidly, they are less likely to be retained long enough in the soil
for biodegradation to occur.
                         9-16

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     •    Other factors.  Activity of organisms is also  dependent on favorable
          temperature and pH conditions as well as  the availability of other
          organic and inorganic nutrients for metabolism.

     Rates of Hydrolysis.  Photolysis, and Oxidation-Chemical  and physical
transformation of the waste can also affect the identity, amounts,  and transport
behavior of the waste constituents.  Photolysis is important primarily for chemicals
on the land surface, whereas hydrolysis and oxidation can occur at various depths.
Published literature sources should be consulted to determine whether individual
constituents are likely to degraded by these processes, but it should  be recognized
that most literature values refer to aqueous systems.  Relevant references include
Elliott and Stevenson, 1977; Sims  et al, 1984;  and U.S.  EPA,  1985.  Chemical and
physical degradation will also be affected by soil characteristics such as pH, water
content, and soil type.

9.3.2      Unit Characterization

     Unit-related factors that may be important in characterizing a release include:

     •    Unit design and operating characteristics;

     •    Release type (point-source or nonpoint-source);

     •    Depth of the release;

     •    Magnitude of the release; and

     •    Timing of the release.

9.3.2.1    Unit Design and Operating Characteristics

     Information on design  and operating characteristics of a unit can be helpful in
characterizing a release.  Table 9-5 presents important mechanisms of contaminant
release to soils for various unit types. This.information can be used to identify areas
for initial soil monitoring.
                                   9-17

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                                 TABLE 9-5
       POTENTIAL RELEASE MECHANISMS FOR VARIOUS UNIT TYPES
       Unit Type
               Release Mechanisms
 Surface Impoundment
Loading/unloading areas
Releases from overtopping

Seepage
 Landfill
Migration of releases outside the unit's runoff collection
and containment system

Migration of releases outside the containment area from
loading and unloading operations

Leakage through dikes or unlined portions to surrounding
soils
 Waste Pile
Migration of runoff outside the unit's runoff collection and
containment system

Migration of releases outside the containment area from
loading and unloading operations.

Seepage through underlying soils
 Land Treatment Unit
Migration of runoff outside the containment area

Passage of leachate into the soil horizon
 Container Storage Area
Migration of runoff outside the containment area
Loading/unloading areas
Leaking drums
 Above-ground or
 In-ground Tank
Releases from overflow

Leaks through tank shell

Leakage from coupling/uncoupling operations

Leakage from cracked or corroded tanks
 Incinerator
Routine releases from waste handling/preparation activities

Leakage due to mechanical failure
 Class I and IV Injection
 Wells
Leakage from waste handling operations at the well head
*  Waste transfer stations and waste recycling operations generally have mechanisms of
   release similar to tanks.
                                    9-18

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9.3.2.2    Release Type (Point or Non-Point Source)

     The owner or operator  should establish whether the release involved a
localized (point) source  or a non-point source.  Units that are likely  sources of
localized releases to soil include container handling and storage areas, tanks, waste
piles, and bulk chemical transfer areas (e.g., loading docks, pipelines, and staging
areas).  Non-point sources may include airborne  particulate contamination
originating from a land  treatment unit and widespread leachate seeps from a
landfill.  Land  treatment can also  result in  widespread releases beyond the
treatment zone if such units are not properly designed and operated; refer to EPA's
PermitGuidance Manual on Hazardous Waste Land Treatment Demonstration, July,
1986 (NTIS PB86-229192) for additional information on determining contamination
from land treatment units. This manual also discusses use  of the RITZ model
(Regulatory and Investigation  Treatment Zone Model), which may be particularly
useful for evaluating mobility and degradation within the treatment zone. This
model is discussed in more detail in Section 9.4.4.2.

     The primary characteristic of a localized release is generally a limited area of
relatively high contaminant concentration  surrounded by larger areas of relatively
clean soil. Therefore, the release characterization should  focus on determining the
boundaries of the contaminated area to minimize the analysis of  numerous
uncontaminated samples.  Where appropriate, a survey of the area with an organic
vapor analyzer, portable gas chromatograph, surface geophysical instruments (see
Appendix C), or other rapid screening techniques may aid in narrowing  the area
under investigation.  Stained soil and stressed  vegetation may provide additional
indications of contamination.  However, even if the extent of  contamination
appears to be obvious, it is the responsibility of the owner or operator  to verify
boundaries of the contamination by analysis of samples both inside and outside of
the contaminated area.

     Non-point type releases to soil may also result from deposition of particulates
carried in the air, such as from incinerator "fallout". Such releases generally have a
characteristic distribution  with concentrations often decreasing logarithmically
away from the source and generally having low variability within a small area. The
highest contaminant concentrations tend to follow the prevailing wind directions
(See  also Section 12 on Air).  Non-point releases occurring via other mechanisms
                                   9-19

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(e.g., land treatment) may be distributed more evenly over the affected area.  In
these situations, a large area may need to be investigated in order to determine the
extent of contamination.  However, the relative lack of "hot spots"  may allow the
number of samples per unit area to be smaller than for a point source type release.

9,3.2.3    Depth of the Release

     The owner or operator should consider the original depth of the release to soil
and the depth to which contamination may have migrated since the  release. Often,
releases occur at the soil surface as a result of spillage or  leakage. Releases directly
to the subsurface can occur  from leaking  underground tanks, buried  pipelines,
waste piles, impoundments, landfills, etc.

     Differentiating between deep and shallow  soil  or surficial soil can be
important in sampling and in determining potential impacts of contaminated soil.
Different methods to characterize releases within deep and surficial soils may be
used. For example, sampling of surficial soil may involve the use of shovels or hand-
driven coring equipment, whereas deep-soil contamination usually requires the use
of power-driven equipment (see  Section 9.6 for more information).  In addition,
deep-soil and surficial-soil contamination may be evaluated differently in the health
and environmental  assessment process discussed in Section  8.  Assessment  of
surficial-soil contamination will involve assessing  risk from  potential ingestion  of
the contaminated soil as well as assessing potential impacts to ground water. The
assessment of deep-soil contamination may be limited to determining the potential
for the  soil to act as a continuing source of potential contamination to ground
water.

     For purposes of the RFI, surficial or shallow-zone soils may be defined as those
comprising the upper 2 feet of earth, although specific sites may exhibit surficial soil
extending to depths of up to 12 feet or more.  Considerations for determining the
depth of the shallow-soil zone may include:

     •    Meteorological conditions (e.g., precipitation, erosion due to high winds,
          evaporation of soil-pore gases);
                                   9-20

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     •   Potential for excessive surface runoff, especially if runoff would result in
         gully formation;

     •   Transpiration, particularly from the root zone, and effects on vegetation
         and animals, including livestock, that may feed on the vegetation; and

     •   Land use, including potential for excavation/construction, use of the soil
         for fill material, installation of utilities (e.g., sewer lines  or  electrical
         cables), and farming activities.

     Land use that involves housing  developments is an example of when the
surficial soil depth may extend to 12 feet because foundation excavation may result
in deep contaminated soils being moved to the surface.  Deep-soil zones, for
purposes of the RFI, may be defined as those extending from 2 feet below the land
surface to the ground-water surface. If deep-soil contamination is already affecting
ground water (through inter-media transport) at a specific  site, consideration
should be given  to evaluating the potential for such contamination to act as a
continuing source of ground-water contamination.

     The depth to which a release may migrate depends on many factors, including
volume of waste released, amount of water infiltrating the soil, age of the release,
and chemical and physical properties of the waste and soil (as addressed in the
previous  section). In a  porous, homogeneous soil, contaminants tend to move
primarily downward within the unsaturated zone. Lateral movement  generally
occurs only through dispersion and diffusion. However, changes in soil structure or
composition with depth  (e.g., stratification), and  the presence  of  zones of
seasonally saturated soil, fractures, and other features may cause  contaminants to
spread horizontally for some  distance before migrating downward.  Careful
examination of soil cores and accurate measurement of physical properties and
moisture content of soil are therefore essential  in estimating the potential for
contaminant transport.

     Transport of chemicals in the soil is largely caused by diffusion and mass flow.
Diffusion results from random thermal motion of molecules. Mass flow, also known
as convective flow, is transport by a flowing liquid or by a gaseous phase. Mass flow
is typically downward (due to gravity); however, mass flow could also be upward
                                   9-21

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due to capillary action (e.g., if significant evaporation occurs at the surface).  Mass
flow is a much faster transport mechanism than is diffusion (Morrilletal., 1985).

     Other factors that can promote downward contaminant migration include
turnover of soil by burrowing animals, freeze/thaw cycles, and plowing or other
human activities. All factors that may affect the depth of contamination should be
considered.  The owner or operator should use available information to estimate
the depth of contamination and should then conduct sampling at appropriate
depths to confirm these estimates.

     Approaches to monitoring releases to soil will differ substantially depending
on the depth of contamination. For investigations of both surficial and deep-soil
contamination, a phased approach may be used.  Initial characterization will often
necessitate a judgmental approach in which sampling depths are chosen based on
available information (e.g., topography, soil stratigraphy, and visual indication of a
release). Information derived from this  initial phase can then be used to refine
estimates of contaminant distribution and transport. This information will serve as
a basis for any subsequent monitoring that may be necessary.

     Where the source or precise location of a suspected release has not  been
clearly identified, field screening methods (See Section 9.6)  may be appropriate.
Subsurface contamination can be detected by using geophysical methods or soil gas
surveying equipment (e.g., organic vapor analyzers).  Geophysical methods, for
example, can help in  locating buried drums.  Soil gas surveys can  be useful  in
estimating the lateral and vertical extent of soil contamination. Further delineation
of the vertical extent of contamination may necessitate an additional effort such as
core sampling and] analysis.  Sampling approaches for locating and  delineating
subsurface  contaminant  sources include systematic and random grid sampling.
These approaches are discussed in Section 3.  Geophysical methods are discussed in
Section 10 (Ground Water) and in Appendix C (Geophysical Techniques).

9.3.2.4   Magnitude of the Release

     Information  on the magnitude of the release can be  estimated from site
operating records, unit design features, and other sources.  The quantity (mass) of
waste released to soil and the rate of release can affect the geographical extent and
                                   9-22

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nature of the contamination. Each soil type has a specific sorptive capacity to bind
contaminants.  If the sorptive capacity is exceeded, contaminants tend to  migrate
through the soil toward the ground water. Therefore, a " minor" release may be, at
least temporarily,  immobilized in shallow soils, whereas a "major" release is more
likely to result in ground-water contamination.  The  physical processes  of
volatilization  and  dissolution in water  are  also affected  by  contaminant
concentrations and should, therefore, be considered in assessing the potential for
inter-media transport. Section  9.4.4.3 provides additional guidance on estimating
the mobility of constituents within contaminated soils.

9.3.2.5   Timing of the Release

     Time-related factors that  should be considered in  characterizing a release
include:

     •   Age of the release;

     •   Duration of the release;

     •   Frequency of the release; and
            •
     •   Season (time of year).

     The length of  time that has  passed since  a release occurred can affect the
extent of contamination, the chemical composition of the contaminants present in
soil, and the potential for inter-media transport. Recent releases tend to be more
similar in composition to the parent waste material  and may also be  more
concentrated within the original boundaries of the release.  If a recent release
occurred at the land surface, contaminant volatilization to air or dissolution  in
overland runoff may be important transport mechanisms. Older releases are more
likely to have undergone extensive chemical or biological changes that altered their
original composition and may  have  migrated a  considerable  distance from their
original location.  If the contaminants are relatively mobile in soil,  transport  to
ground water may be a concern; whereas soil-bound contaminants may be more
likely affected by surface transport, such as overland runoff or wind action.  These
                                   9-23

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factors should be considered in the selection of monitoring constituents and
sampling locations.

     The duration and frequency of the release can affect the amounts of waste
released to the soil  and its distribution in the soil.  For example, a release that
consisted of a single episode, such as a ruptured tank, may move as a discrete "slug"
of contamination through the soil. On the other hand, intermittent or continuous
releases may present a situation  in which contaminants exist at different distances
from the source and/or  have undergone  considerable  chemical and biological
decomposition. Therefore, the design of monitoring procedures and estimations of
contaminant fate and transport should consider release duration and frequency.

     The time of year or season may also affect release fate and transport. Volatile
constituents are more likely to be released to the air or to migrate as subsurface gas
during the warmer summer months. During the colder winter months, releases may
be less mobile, especially if freezing occurs.

9.3.3     Characterization of the Environmental Setting

     The nature and extent of contamination  is affected  by environmental
processes such as dispersion and  degradation acting after the release has occurred.
Factors which should be  considered include soil physical and chemical  properties,
subsurface geology and hydrology, and climatic or meteorologic patterns.  These
factors are discussed  below.

     Characteristics of the soil medium which should be considered  in order to
obtain representative samples for chemical  or physical analysis include:

     •   The potentially large spatial variability of  soil properties and
         contaminant distribution;

     •   Spatial and temporal fluctuations in soil moisture content; and

     •   The presence of solid, liquid, and gaseous phases  in the unsaturated
         zone.
                                   9-24

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9.3.3.1    Spatial Variability

     Spatial variability, or heterogeneity, can be defined as horizontal and vertical
differences in soil  properties  occurring  within the scale of the area  under
consideration. Vertical discontinuities are found in most soil profiles as a result of
climatic changes during soil formation, alterations in topography or  vegetative
cover, etc. Soil layers show wide differences in their tendency to sorb contaminants
or to transmit contaminants in a liquid form; therefore, a monitoring program that
fails to consider vertical stratification will likely result in an inaccurate assessment of
contaminant distribution.  Variability in soil  properties may also occur in  the
horizontal plane as a result of factors such as drainage, slope, land  use history, and
plant cover.

     Soil and site maps will aid in designing  sampling procedures by  identifying
drainage patterns, areas of high or low surface permeability, and areas susceptible
to wind erosion and contaminant volatilization. Maps of unconsolidated deposits
may be prepared from existing soil core information, well drilling logs, or from
previous geological studies. Alternately, the information can be obtained from new
soil borings.  Because soil coring can be a resource-intensive activity, it  is generally
more efficient to also obtain samples from these cores for preliminary  chemical
analyses and to conduct such activity concurrent with investigation of releases to
other media (e.g., ground water).

     The number of cores necessary to characterize site soils depends on  the site's
geological complexity and size, the potential area! extent of the release, and the
importance of defining  small-scale discontinuities in  surficial materials.  Another
consideration is the  potential risk of spreading the contamination as a result of the
sampling effort. For example,  an improperly  installed well casing could lead to
leakage of contaminated water through a formerly low permeability clay layer. The
risks of disturbing the subsurface should be considered when determining the need
for obtaining more data.

     Chemical and  physical measurements  should be made for each distinct soil
layer, or boundary  between layers, that may  be  affected  by a release. During
drilling, the investigator should note on the drilling log the depths  of soil horizons,
soil types and textures, and the  presence of joints, channels, and zones containing
                                    9-25

-------
plant roots or animal burrows.  Soil variability, if apparent, should generally be
accounted for by increasing the number of sample points for measurement of soil
chemical and physical  properties. Determination of the range and variability of
values for soil properties and parameters will allow more accurate prediction of the
mobility of contaminants in the soil.

9.3.3.2    Spatial and Temporal Fluctuations in Soil Moisture Content

     As described earlier in this section, there are several mechanisms for transport
of waste constituents in the soil.  Release migration can be increased by the physical
disturbance of the soil during freeze/thaw cycles or by burrowing animals.
Movement can also be influenced by microbial-induced  transformations.  In
addition, movement can occur through diffusion and mass flow of gases and liquids.
Although all of these mechanisms exist, movement  of  hazardous  waste or
constituents through  soil toward  ground water occurs primarily by aqueous
transport of dissolved chemicals in soil pore water. Soil moisture content affects the
hydraulic conductivity of the soil and the transport of dissolved wastes through the
unsaturated zone.  Therefore, characterizing the storage and flow of water in the
unsaturated zone is very important. Moisture in the unsaturated zone is in a
dynamic state and is constantly acted upon by competing physical forces.

     Water applied to the soil surface (primarily through precipitation) infiltrates
downward under the influence of gravity until the soil  moisture content  reaches
equilibrium with capillary forces. A zone of saturation (or wetting front) may occur
beneath  the bottom of a unit (e.g., an unlined lagoon) if the unit is providing a
constant source of moisture.  In a low porosity soil, such a saturation front may
migrate downward through the unsaturated zone to the water table, and create a
ground-water or liquid "mound" (see  Figure 9-1).  In a higher porosity soil, the
saturation front may only extend a small distance below the unit, with liquid below
this distance then moving through  the soil under unsaturated conditions  toward
ground water (see Figure 9-1). In many cases, this area will remain partially
saturated until the capillary fringe area is reached. The capillary  fringe  can be
defined as the zone immediately above the water table  where the pressure is less
than atmospheric and where water and other liquids are  held within the pore
spaces against the force of gravity by interfacial forces (attractive forces between
different molecules).
                                   9-26

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     In certain  cases, soil moisture characterization  can  also be affected  by the
presence of isolated zones of saturation and fluctuations in the depth to ground
water, as illustrated in Figure 9-1. Where there is evidence of migration below the
soil surface, these  factors should be considered in the investigation by careful
characterization of subsurface geology and measurement of hydraulic conductivity
in each layer of soil that could be affected by subsurface contamination.

9.3.3.3    Solid, Liquid, and Gaseous Materials in the Unsaturated Zone

     Soil in the unsaturated zone  generally contains solid, liquid, and gaseous
phases. Depending upon the physical and  chemical properties of the waste or its
constituents, contaminants of concern may be bound to  the soil, dissolved in the
pore water, as a vapor within the soil pores or interstitial  spaces, or as a distinct
liquid phase. The investigation should therefore take into consideration the
predominant form of the contaminant in the soil.  For example, some whole-soil
sampling methods may lead to losses of volatile chemicals, whereas analysis of soil-
pore water may not be able to detect low  solubility compounds such as PCBs that
remain primarily adsorbed in the solid phase.  Release characterization procedures
should consider chemical and physical properties of both the soil and the waste
constituents to assist in determining the nature and extent of contamination.

     Soil classification-The owner or operator should classify each soil layer
potentially affected by the release.  One  or more of the classification systems
discussed below should be used, based on the objectives of the investigation.

     •    USOA Soil Classification  System  (USDA, 1975)--Primarily developed for
          agricultural purposes, the USDA system also provides information  on
          typical soil profiles (e.g., 1-foot fine sandy loam  over gravelly sand, depth
          to  bedrock  12 feet), ranges of permeabilities for each layer, and
          approximate particle size ranges. These values are not generally accurate
          enough  for predictive purposes, however, and should not be used to
          replace information collected on site.  Existing information on regional
          soil types is available but suitable for initial planning purposes only.  U.S.
          Department of Agriculture (USDA) county soil  surveys  may be obtained
          for most areas.
                                    9-28

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     •    Unified Soil Classification Systems (USCS) (Lambe and Whitman, 1979)-- A
          procedure for qualitative field classification of soils according to ASTM
          D2487-69, this system should be used to identify materials in soil boring
          logs. The USCS is based on field determination of the percentages of
          gravel, sand and fines in the soil, and on the plasticity and compressibility
          of fine-grained soils.  Figure 9-2 displays the decision matrix used in
          classifying soils by this system.

     The above classification systems are adequate for descriptive purposes and for
qualitative estimates of the fluid transport properties of soil layers. Quantitative
estimation of fluid transport properties of soil layers requires determination of the
particle size distribution for each soil layer, as described below.

     Particle size distribution-A measurement of particle size distribution should
be  made for each  layer  of  soil  potentially affected by the release.  The
recommended method  for  measurement of particle size distribution is a
sieve/hydrometer analysis according to ASTM D422 (ASTM, 1984).

     The particle size distribution has two major uses in a soils investigation:  (1)
estimation of the hydraulic conductivity of the soil by use of the Hazen (or similar)
formula, and (2) assessment of soil sorptive capacity.

     1.   The hydraulic conduct! vity(K) may  be estimated from the particle size
          distribution using the Hazen formula:
          where dio is equal to the effective grain size, which is that grain-size
          diameter at which 10 percent by weight of the particles are finer and
          90 percent are coarser (Freeze and Cherry, 1979).  The coefficient A is
          equal to 1.0 when K is in units of cm/sec and dio is in mm. Results should
          be verified with in-situ hydraulic conductivity techniques.

     2.    Particle size can affect sorptive capacity and, therefore, the potential for
          retardation of contaminants in the soil. Sandy soils generally have a low
          sorptive capacity whereas clays generally have a high affinity for heavy
                                    9-29

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          metals and some organic contaminants.  This is due in part to the fact
          that small clay particles  have a  larger surface area in relation to their
          volume than do larger sand particles.  This larger surface area can result
          in stronger interactions  with waste molecules.  Clays  may also bind
          contaminants due to the  chemical structure of the clay matrix.

     Porosity-Soil porosity is the percentage of the total soil volume not occupied
by solid particles (i.e., the volume of the voids). In general, the greater the porosity,
the more readily fluids may flow through the soil. An exception is clayey soils that
tightly hold fluids by capillary forces. Porosity is usually measured by oven-drying an
undisturbed sample and weighing  it. It is then saturated with liquid and weighed
again. Finally, the saturated sample is immersed in the same liquid, and the weight
of the displaced liquid is measured. Porosity is the weight of liquid  required to
saturate the sample divided by the weight of liquid displaced, expressed  as a
decimal fraction.

     Hydraulic conductivitv--An essential physical property affecting contaminant
mobility in soil is hydraulic conductivity. This property indicates the ease with which
water at the prevailing viscosity will flow through the soil and is dependent on the
porosity of the soil, grain size, degree of consolidation and cementation, and other
soil factors.

     Measurement of hydraulic conductivity in soil within the saturated  zone is
fairly routine.  Field and laboratory methods to determine saturated conductivity
 are discussed  in  the section on ground-water investigations (Section  10).
Measurement of unsaturated conductivity is usually  more difficult because the
value changes with changing soil moisture content. Therefore, conductivities for a
range of moisture contents may need to be determined for each type of soil at the
facility.

     Techniques for determining saturated hydraulic conductivity are  provided in
Method 9100 (Saturated Hydraulic  Conductivity, Saturated Leachate Conductivity,
and Intrinsic Permeability)  from SW-846, Test Methods for Evaluating Solid Waste,
EPA. 3rd edition. September, 1986. Method 9100 includes techniques for:

     •    Laboratory
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               constant head methods; and
               falling head methods.

     •    Field

               sample collection;
               well construction;
               well development;
               single well tests (slug tests); and
               references for multiple well (pumping tests).

     A detailed discussion of field and laboratory methods for  determining
saturated and unsaturated hydraulic conductivity is also contained in Soil Properties
Classification and Hydraulic Conductivity Testing (U.S. EPA, 1984). In  general, field
tests are  recommended when the soil is heterogeneous, while laboratory tests may
suffice for a soil without significant stratigraphic changes. Estimation of hydraulic
conductivity from the particle size distribution may be used as a rough estimate for
comparison purposes and if precise values are not needed.

     Relative permeabilitv-The hydraulic conductivity of a soil is usually established
using water as the infiltrating  liquid. However, at sites where there is the likelihood
of a highly contaminated leachate or a separate liquid waste phase,  the owner or
operator should also consider determining conductivity with that liquid. The ratio
of the permeability of a soil to a non-aqueous solution and its permeability to water
is known as relative  permeability.

     The importance  of determining this value is due to the potential effects of
leachate  on soil hydraulic properties. Changes in conductivity from infiltration of
leachate  may result from differences in the viscosity or surface tension of the waste,
or the leachate may affect the soil structure so as to alter its permeability.  For
example, studies of waste  migration through landfill  liners  made  of clay have
demonstrated that  certain  wastes may cause shrinking or expansion of the clay
molecular structures, dissolve clays and organic matter, clog soil pores with fine
particles, and cause other changes that affect permeability.
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     Soil sorptive capacity and soil-water partition coefficient (Kd)-The mobility of
contaminants in soil depends not only on properties related to the physical structure
of the soil, but also on the extent to which the soil material will retain, or adsorb,
the hazardous constituents. The extent to which a constituent is adsorbed depends
on chemical properties of the constituent and of the soil. Therefore, the sorptive
capacity must be determined with reference to particular constituent and soil pairs.
The soil-water partition coefficient (Kd) is generally used to quantify soil sorption.
Kd is the ratio of the adsorbed contaminant concentration to the dissolved
concentration, at equilibrium.

     There are two  basic approaches to determining K
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approach are particle size distribution, cation exchange capacity, and soil organic
carbon content.  The waste properties that should be  determined  will vary
depending on the type of waste.  Lyman et al. (1981) discuss several methods for
estimating  K
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hydraulic gradient (i.e., moisture content does not change with depth), the pore-
water velocity can be calculated by the following equation:

                                  V = q/e

where:    V = pore water velocity, cm/day
          q = volumetric flux/unit area, cm/day
          e = volumetric water content, dimensionless

     A simple approximation of volumetric flux (q) can be made by assuming that it
is equal to percolation at the site.  Percolation can be estimated by performing a
water balance as described below.   This approach for calculating  pore-water
velocity is limited by simplifying assumptions; however, the method may be used to
develop an  initial estimate for time of travel of contaminants.  More detailed
methods, which account for unsteady flow and differences in moisture content are
described in the following reference:

     U.S. EPA.  1986.  Criteria for Identifying Areas of Vulnerable Hydroqeoloqy
     Under the Resource Conservation and Recovery Act. NIL PB86-224953. Office
     of Solid Waste. Washington, D.C. 20460.

     Percolation (volumetric flux per unit area)--Movement of contaminants from
unsaturated soil to ground water occurs primarily via dissolution and transport with
percolating soil water. It is important, therefore, to determine the volume of water
passing through  the soil.  The percolation rate, or volumetric flux, must be
determined in order to calculate pore-water velocity through the unsaturated zone.
The rate of percolation can be estimated from the water balance equation:

                              PER = P-ET-DR

where:    PER  =   Percolation/recharge to ground water
          P    =   Precipitation and irrigation
          ET   =   Evapotranspiration
          DR   »   Direct surface runoff
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Annual averages for P, ET and DR should be obtained from existing local sources.
Sources of information to estimate PER include:

     •    State or Regional water agencies;

     •    Federal water agencies (Geological Survey, Forest Service); and

     •    National Weather Service stations.

It is recommended that site-specific ET and DR data be used if possible, because local
conditions can vary significantly from regional estimates. More information  on
percolation and ground-water recharge can be found in standard  ground-water
texts, such as Freeze and Cherry, 1979.  Information on evapotranspiration and
direct surface runoff may be found in the following references:

     U.S. EPA.  1975.  Use of the Water Balance Method for Predicting Leachate
     Generation from Solid Waste Disposal Sites. EPA/530/SW-168. Office of Solid
     Waste.  Washington, D.C. 20460.

     U.S. Geological Survey. 1982.  National Handbook of Recommended Methods
     for Water Data Acquisition.

     Volumetric water content--The volumetric water content is the percent of
total soil volume that is filled with water. It is equal to the amount of water lost
from the soil upon drying to constant weight at 105°C, expressed as the volume of
water/bulk volume of soil.  This parameter affects the unsaturated hydraulic
conductivity and is required for calculation of pore-water velocity.  At saturation,
the volumetric water content is equal to the porosity of the soil.

     Additional soil conditions-Additional soil conditions that may require special
consideration in investigating releases to soil are discussed below.

     •    In certain dense, cohesive  soils, water may move primarily through
          narrow solution channels or fracture zones rather than by permeating
         the bulk of the soil. This condition can sometimes be recognized by dark-
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     colored deposits indicating the fractures or by the tendency of soil cores
     to break apart at the discontinuity.

•    Decomposed rock  (e.g., transitional soils)  may have  a  low primary
     porosity but a high  secondary porosity due to relict joints or fractures or
     solution channels. Therefore, most flow may occur through these cracks
     and channels rather than through the soil pores. As a result, the rate of
     fluid flow is likely to be high, and the low surface area within the joint or
     fracture system generally results in a low sorptive capacity.  Because field
     conditions are highly variable, the characterization of soil structure
     should be sufficiently detailed to identify such joints or fractures that
     may provide contaminant pathways.

•    Certain clay  soils  known as vertisols, or expandable  clays, may fracture
     into large blocks when dry.  These cracks can be  a direct route for
     ground-water contamination.  Soil surveys should be consulted  to
     determine whether these soils are present at the site. They occur in, but
     are not limited to,  eastern Mississippi and central and  southern Texas.
     Other clay soils may also develop desiccation cracks to a lesser degree. In
     these  cases,  it may be advisable to sample during  both  wet and  dry
     seasons.

•    Sampling saturated soils may be accomplished with  the same  drilling
     techniques used for unsaturated soil sampling.  Particular care must be
     taken to prevent contamination  between soil layers.  Methods  of
     telescoping smaller diameter casing downward through larger diameter,
     grouted casing are  useful for minimizing cross-contamination between
     soil layers (See Section  9.6 for additional  information  on telescoping
     methods).

•    Frequently, the choice of sampling technique is dictated by mechanical
     factors. Hard, rocky, or dense soils may prevent the use  of manual tube
     samplers or augers.  Power-driven auger drill rigs equipped with split-
     spoon samplers can penetrate most soils.  Power augers can  penetrate
     most unconsolidated materials, but will not drill through rock, for which
     an air-driven rotary drill is the recommended method. Loose sandy soils
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          will fail to be retained in a tube sampler; therefore a sampler equipped
          with  a  retaining device should be used in such cases.  Core sampling
          should generally be carried out under the supervision of an experienced
          driller, in order to avoid poor results or damaged equipment.

     •    Where  unfavorable soil conditions interfere with a proposed sampling
          location, the sampling point may have to be moved to a nearby location.
          In the event that such conditions are encountered, new locations should
          be chosen that are adequate to characterize the release.

9.3.4      Sources of Existing Information

     Considerable information may already be available to assist in characterizing a
release. Existing information should be reviewed to avoid duplication of previous
efforts and to aid  in scoping the RFI. Any existing information relating to releases
from the unit and to hydrogeological,  meteorological, and environmental factors
that could influence the persistence, transport, or location of contaminants should
be reviewed.  This information may aid in:

     •    Delineating the boundaries of the sampling area;

     •    Choosing sampling and analytical techniques; and

     •    Identifying  information needs for later phases of the investigation,  if
          necessary.

     Information may be obtained from readily available sources of geological and
meteorological data, waste characteristics, and facility operating records.  (See also
Sections 2,3,7 and Appendix A).

9.3.4.1    Geological and Climatological Data

     The Federal government and most state governments compile geological data,
soil surveys, land use records, and climatological information. These sources should
be consulted for  local  geology, soil types, historical precipitation, ground-water
elevation records, and other useful data. Sources which may be consulted for soils
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data include the Soil Conservation Service (SCS), Agricultural Stabilization and
Conservation Service (ASCS), the U.S. Geological Survey (USGS), state soils bureaus
and agricultural extension services, university soil science departments, and private
consultants.  Additional sources of geologic information include geotechnical
boring logs for foundation studies, well logs made during drilling of water supply
wells, and  previous hydrogeologic  investigation monitoring wells.  These logs
should indicate the depth, thickness, and character of geologic materials, and the
depth to the water table.  Climate and weather information can be obtained from:

          National Climatic Center
          Department of Commerce
          Federal Building
          Asheville, North Carolina 28801
          Tel: (704)258-2850

9.3.4.2    Facility Records and Site Investigations

     The owner or operator should plan investigation activities by focusing on the
conditions  specified in the permit or enforcement  order.  Facility records, the
facility's RCRA permit application, and any  previous site reports (e.g., the RFA
report) should also be examined for any other information on unit characteristics,
wastes produced at the facility, and other factors relevant to releases to soil. Facility
operating records should have data on wastes treated, stored, or disposed of at the
facility. Wastes regulated under RCRA are identified by a waste code that may also
aid in identifying constituents of concern (see 40 CFR Part 261). Wastes originating
within the facility may be identified through analysis of  process control records.
Unit releases (e.g., losses from  leaking tanks) can sometimes be estimated  from
storage records.

9.4       Design of a Monitoring Program to Characterize  Releases

9.4.1      Objectives of the Monitoring Program

     Monitoring procedures that specify locations, numbers, depths, and collection
techniques for soil samples should be prepared by the owner or operator prior to
each sampling effort. These procedures should provide the justification  for the
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proposed samples, in terms of their expected contribution to the investigation.
Examples of soil monitoring objectives include:

     •   Describing soil contamination in a drainage channel where a release is
         known to have occurred;

     •   Establishing a random or systematic grid sampling network to determine
         soil contamination concentrations in all zones of a large area affected by
         airborne deposition; and

     •   Filling in data gaps concerning the transport of waste constituents within
         a permeable soil layer.

     In preparing soil monitoring procedures, the owner or operator should take
into consideration those factors discussed in Sections 9.3.1 through 9.3.4 that apply
to the facility.  Also  see Section  9.4.4.3 (Predicting Mobility of Hazardous
Constituents in Soil).

     As discussed previously, the release characterization  may be conducted  in
phases.  The objectives of the initial soil characterization  are generally to verify
suspected releases or to begin characterizing known releases.  This characterization
should use relevant soil physical and  chemical measurements and other information
as described earlier. In developing the approach, the owner or operator should
determine the following:

     •   Constituents and indicator parameters to be monitored;

     •   Role of field screening methods, if any;

     •   Sampling methods;

     •   Approximate study and background areas;

     •   Sampling locations and approach (e.g., judgmental or systematic); and

     •   Number of samples to be collected.
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     The owner or operator may propose the use of field screening methods to aid
in delineating the zone affected  by a contaminant release to soil and/or ground
water.  Such methods may be applied just below the land surface or at greater
depths, as within  soil bore holes. An increasingly used method to detect organic
vapors is generally known as a soil gas survey.  Such a survey can yield qualitative
and relative quantitative data on volatile constituents present in the  soil  gas,
depending on the instrumentation used.  For example, a total  photoionization
detector will provide an integrated value for the volatile organics present; whereas
a portable gas chromatograph can identify and quantitate specific  compounds
present in the soil vapor. Field screening  can also include chemical analyses of soil
samples performed onsite in mobile laboratories.

     When conducting a soil gas survey, it should be realized that any measured soil
vapor concentrations of specific compounds cannot be directly correlated with their
actual concentrations in the soil zone of concern. The concentrations  in soil vapor
resulting from a soil with  given  volatile contaminant concentrations will vary,
depending on several factors, including barometric pressure, relative  humidity in
the soil, weather conditions (e.g., precipitation  events, soil inhomogeneities, and
temperature).  Therefore, the results  of a soil gas survey can  reveal  the relative
abundances of volatile  compounds in the  soil gas, but  not their actual
concentrations in the soil.

     The soil gas survey technique may also be applied when drilling boreholes to
characterize site geology or when  drilling to install ground-water monitoring wells.
Soil samples taken at various depths within the borehole can be placed in  separate
sample bottles with septums.

     A sample of the gas in the headspace can then be withdrawn with a syringe
and  injected into  a portable  gas chromatograph  to identify  the presence  and
relative abundances of specific volatile compounds in the soil gas. Analysis of drill
cuttings in the open air is not as effective as the headspace technique  in detecting
volatile organic compounds; therefore, the headspace method is preferred.

     Additional information on soil gas  monitoring  may be obtained from the
following reference:
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     U.S. EPA. 1987.  Soil Gas Monitoring Techniques Videotape.  National Audio
     Visual Center. Capital Heights, Maryland 20743.

     Screening methods may help to reduce the number of soil  and/or ground-
water samples needed to characterize a release by better delineating the area of
concern in a relatively rapid manner.  However, due to limitations (e.g., relatively
high detection limits and  inability to identify all the  potential hazardous
constituents  of concern), some screening methods may not be adequate to verify
the absence  of a  release.  For such ver :ication,  an appropriate  number  of  soil
samples would need to be analyzed in the laboratory. Additional information on
field screening methods is presented later in this section and in the Compendium of
Field Operations Methods. (EPA, 1987).

     Depending on the outcome of the initial characterization effort, the owner or
operator may be required to obtain additional data to characterize the release.  The
findings of the initial phase will dictate the objectives of any later phases. Such
subsequent phases will generally involve the following:

     •    Expanding the number of sampling locations to a wider area  and/or
          depth, or increasing sampling density where data are sparse;

     •    Institution of a refined grid sampling approach to further assess releases
          identified by judgmental sampling (see Section 3);

     •    Addition or deletion of specific monitoring constituents or indicator
          parameters; and

     •    Sampling in areas of interest based on  previous sampling or  model
          predictions to confirm the suspected extent of the release.

     There is no specified or recommended number of phases to complete a  soil
investigation. The owner or operator should determine through consultation with
the regulatory agency whether the collected data are sufficient to meet  the
objectives of the investigation.
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9.4.2      Monitoring Constituents and Indicator Parameters

     The owner or operator should propose hazardous constituents for monitoring
based on the composition of wastes known or suspected to be present or released
to soils at the site (see Sections 3 and 7 and Appendix B). Additional measurements
may include nonhazardous chemicals that could serve as indicators of the presence
of hazardous constituents or that could mobilize or otherwise affect the fate and
transport of hazardous constituents. Chemical and physical properties of the soil
that can be measured from soil samples should also be included in  the  list of
parameters (see Section 9.3.3.3).

     Justification of monitoring constituent selection may be  provided through
detailed facility records or waste analyses, as explained in Section 3.  If such
justification is  inadequate, it may be necessary to perform a broader  analytical
program (See Section 3 and Appendix B).

     During or after the  selection  of monitoring constituents, the owner or
operator should review guidance on compound-specific requirements for sampling
and sample p sservation.  The laboratory should use  EPA protocols and analytical
procedures when available, and accepted QA/QC practices. Guidance and specific
references in these areas are provided in Sections 2,3,4, and 7.

9.4.3      Monitoring Schedule

     Monitoring frequency and duration determinations should be based primarily
on the type of  release to the soil.  A single episode or intermittent release, as with
any release, would require monitoring until the nature and extent of contamination
has been characterized. This may be accomplished with one or two sample  sets in
some cases. Longer-term releases will usually necessitate a  greater duration of
sampling.  Soil-pore liquid may require more frequent  monitoring than in soil solids
because changes generally occur faster in these fluids.  Frequency  may also be
adjusted, if appropriate, as sampling results become available.  As with  single
episode releases, longer-term releases are monitored until the nature and extent of
contamination  has been adequately characterized.
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9.4.4     Monitoring Locations

9.4.4.1   Determine Study and Background Areas

     Determination  of the area of interest  will depend on the facility layout,
topography, the distribution of surface soils,  soil stratigraphy, and information on
the nature and source of the release. The size and type of unit may affect the area
under consideration. For example, a small landfill may only require monitoring of
the surrounding  soil whereas an inactive land treatment facility may require
sampling over the entire unit surface and beyond.

     High variability in the chemical composition of soils makes determination of
background levels for the constituents of concern  essential. This is particularly
important for quantification of toxic metals,  because such metals commonly occur
naturally in soil.  Background  areas not affected by any facility release should be
selected based on their similarity to the study area in terms of soil type, drainage,
and other physical factors. Background soil  samples should be taken from areas
that are not near a suspected  source of contamination  and from  the same
stratigraphic layer as the study area samples, if possible. Selection and sampling of
appropriate background areas may be important because verification of a release in
a contaminated  area may involve a comparison of  study and background
concentrations.

     The owner or operator may increase efficiency in the initial characterization
effort by using rapid, field-screening methods (e.g., soil gas surveys using HNu, OVA
or portable gas chromatograph) or through indicator parameter measurements to
establish the extent of the study area. Subsurface soil contamination can sometimes
be  identified by  geophysical techniques such as electromagnetic and resistivity
techniques  (See Section 10 and  Appendix C).  Indicator parameters can also be
helpful in establishing the extent of the monitoring  area.  For example, Total
Organic Halogen (TOX) or Total Organic Carbon (TOC) analysis may be useful in
detecting total chlorinated and nonchlorinated organic solvents.  Such parameters
may be used to characterize the nature and extent of a release but should always be
verified by an adequate number of specific constituent analyses.
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     It is generally recommended that a sampling grid be developed for the site,
even for judgmental sampling.  Gridding of the area to be sampled prior to the
sampling effort will  aid in  determining appropriate sampling locations and in
describing these locations.  Refer to  Section 3.6 for additional information on
gridding of a study site.

9.4.4.2   Determine Location and Number of Samples

     The owner or operator should propose monitoring locations and the number
of samples to be collected and analyzed.  Samples should be taken from the vicinity
of all units identified in the conditions of the permit or order as suspected or known
sources of soil contamination.  The total number of samples necessary for the initial
investigation will depend on the extent of prior information, the suspected extent
and severity of the release, and the objectives of the characterization.  However, the
following general guidance should aid the owner or operator to sample efficiently.

     •   Sampling efficiency may be  increased by use of a proportional sampling
         approach, which involves dividing the area of concern into zones, based
         on proximity to the relea' •>  source and/or other factors.  The number of
         samples taken in each zone should be proportional to the area of a zone.

     •   Use  of composite samples may be  able to allow detection of
         contamination over an area of concern with a smaller number of
         analyses. Compositing involves pooling and homogenization of multiple
         soil samples. The composite is then analyzed to give an average value for
         soil contamination in that area. However, as discussed in Sections 3 and
         1, composites should have very limited application during the RFI and
         should always be  accompanied by an appropriate number of individual
         grab samples.  The following additional limitations on  compositing
         should be observed:

              Compositing is most useful when large numbers of soil samples can
              be easily collected (e.g., for surficial contamination).  In order to
              obtain the maximum information from deep soil coring, individual
              grab samples are preferred over composites.
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         Compositing should not be used when analyzing soils for volatile
         organics because the constituents of interest may be lost during
         homogenization and sample handling.

•    The owner or operator should employ appropriate procedures for the
     evaluation and reporting of monitoring data. These procedures can vary
     in a site-specific manner but should result in determinations of the
     nature, extent, and rate of migration of the release. Where the release is
     obvious and/or chemically simple,  it  may be possible to characterize it
     readily from  a descriptive  presentation of concentrations found.
     However, where contamination is less obvious or the release is chemically
     complex, a statistical inference approach may be  proposed. The owner
     or operator  should plan initially to take a descriptive approach to data
     evaluation in order to broadly delineate the extent of contamination.
     Statistical comparisons of monitoring data among monitoring locations
     and over time may be  appropriate if a descriptive approach  does not
     provide a clear characterization of  the release.  Further guidance on use
     of statistical methods in soil investigations is provided in the following
     documents:

         Barth, D.S. and B.J. Mason. 1984. Soil Sampling Quality Assurance
         User's  Guide.  U.S. EPA 600/4-84-043.   NTIS PB84-198621.
         Washington, D.C. 20460.

         Mason, B.J.   1983.  Preparation  of a Soil Sampling  Protocol:
         Techniques and Strategies. NTIS PB83-206979. U.S. EPA  600/4-83-
         020. Washington, D.C. 20460.

•    Characterization of contaminant distribution with depth  necessitates
     sampling of each distinct soil  layer  that might be affected by the release
     and from boundaries between soil layers. If the soil profile contains thick
     layers of homogeneous soil, samples should be taken at regular intervals
     (e.g., every 5 feet). In addition, samples should be taken where borings
     intersect fracture  systems, at  interfaces  of zones of high  and low
     permeability materials, or at other features that  could affect
     contaminant  transport.  The owner or operator should  consider
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          measurement of soil physical and hydraulic properties in each distinct soil
          layer.  The objective of such measurements in the initial release
          characterization effort is to identify properties that vary with depth. This
          approach may  indicate the use of stratified sampling in any future
          sampling phases.  Determination of soil properties will also aid in
          refining conceptual models of contaminant transport and can be input
          for mathematical models of soil transport.

     Modeling-Prediction of contaminant fate and transport can range from a
"conceptual" model of contaminant behavior in the soil to complex computer
programs requiring extensive input of soil and water budget data. The primary uses
of predictive modeling in soil investigations are to locate appropriate  sampling
locations using site-specific input data and to estimate the future rate, extent, and
concentration of contaminant releases.

     Modeling of contaminant transport in the unsaturated zone is often difficult
due to the generally high spatial variability in soil physical and hydraulic properties.
Therefore, modeling should not be used to replace actual measured values (e.g.,
when establishing the limits of waste leaching or diffusion in soil). However, if used
with caution, models can act as useful tools to guide sampling  efforts by directing
sampling towards site areas identified  as preferred soil/water flowpaths (e.g., a
permeable soil layer).  The owner or operator should discuss the use of specific
models with the regulatory agency prior to use.

     Numerous models,  including computer models, have been developed to
calculate water flow and contaminant transport under saturated and unsaturated
soil conditions. In using such models, site-specific data on soils and wastes should be
used. Ground-water (saturated flow) models are discussed in Section 10.  A U.S.
Nuclear Regulatory Commission Report  (Oster,  1982) may  be reviewed  for
information on the applicability of 55 unsaturated flow and transport models.  Use
of the RITZ Model (found in U.S. EPA.  1986.  Permit Guidance Manual on Hazardous
Waste Land  Treatment Demonstration.  NTIS PB86-229192) may be particularly
appropriate in certain situations. The RITZ model describes a soil column, 1 meter
square, with a depth equal to the  land treatment zone (usually 1.5 m). The  soil
column consists of a plow zone and lower treatment zone that are made up of four
phases: soil grains, pore water, pore air, and pore oil. Mobilization of constituents
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within the soil is accounted for by dispersion, advection, and migration between
phases.  The  constituent may also be degraded by biochemical processes
represented in the model. Output from the model includes the concentration (C) of
a constituent at the bottom of the treatment zone, and the time (T) required for a
constituent to travel a distance equal to the treatment zone depth. Although the
RITZ model was developed for evaluating the effectiveness of land treatment units,
the model may be used for other applications, as appropriate (see above referenced
document).

     EPA is in the process of developing a more sophisticated version of the RITZ
model, known as the RITZ-VIP model. The VIP version differs in that it is designed to
provide information for multiple waste loadings in a land treatment situation. The
initial version of the RITZ  model only applies where the waste or material in
question  is applied to the land  once.  The RITZ-VIP version is currently in the
review/verification process.  More information on this model may  be obtained by
writing to EPA at the following address:

     U.S. Environmental Protection Agency
     Roberts. Kerr Environmental Research Laboratory/ORD
     P.O. Box 1198
     Ada, Oklahoma 74820

     Computer models if proposed for use in the RFI should (1) be  well-
documented; (2) have been peer reviewed; and (3) have undergone extensive field
testing.  As Indicated previously, model documentation (e.g.,  model  theory,
structure, use, and testing) should be provided to the regulatory agency for review
prior to use. Access to the relevant data sets should also be available upon request.
The regulatory agency may also recommend that a sensitivity analysis be performed
and that the results of the analysis be submitted with the model results. In selecting
a model, the owner or operator should consider its applicability, limitations, data
requirements, and resource  requirements.

9.4.4.3   Predicting Mobility of Hazardous Constituents in Soil

     Predicting the mobility of hazardous constituents in soil may be necessary in
an RFI. The prediction may then be used to estimate the probable vertical or lateral
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extent of contamination, which  can  be used to identify potential  sampling
locations. Mobility predictions may also be used in determining potential inter-
media transfers from the soil to  ground or surface water.  Finally, mobility
predictions may provide information that can be used  during  the Corrective
Measures Study to differentiate between contaminated soil that should be removed
from the site and that which  may remain at the site without adversely affecting
human health or the environment.  Predicting mobility of soil constituents may be
particularly relevant, as indicated in Section 8, for determining whether deep-soil
contamination, or in some cases surficial-soil contamination, can lead to ground-
water contamination at a level above health and environmental criteria (if such an
impact has not already occurred).

     There is no universally accepted, straightforward method for predicting the
mobility of all  hazardous constituents  within soils  under all possible  sets of
environmental conditions. Nor is there a fully tested method of estimating the
impact of constituents originating  in the unsaturated zone on ground-water
quality.  Therefore, to avoid  unneeded efforts, the first question the owner or
operator should address is whether this task is necessary.  For example, the
characterization of ground-water  quality (conducted  following the guidance in
Section 10) may provide information sufficient to describe the extent of the release
in soils as well, and to determine that a Corrective Measures Study is necessary. This
may be the case in situations where contaminated soils are located solely within the
ground water and when the contaminants are relatively mobile. The most recent
ground-water impact characterization data may not, however, provide information
on the future impact of contaminated soils on ground water (e.g., due to different
leaching rates for different contaminants).

     This section presents various approaches for predicting constituent mobility in
both saturated and unsaturated soils; it also discusses how  to estimate the impact
on ground-water quality of the constituents leached from  unsaturated soils. The
limitations of these methods are also reviewed.

9.4.4.3.1  Constituent Mobility

    There  are several means of investigating mobility, including a descriptive
approach (i.e., consideration of constituent and soil  properties), the use of
                                   9-49

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mathematical models, and the use of laboratory models or leaching tests. Leaching
tests have the advantage of being the only approach that integrates soil and
constituent properties in a single evaluation. They may, in certain cases, provide a
conservative (reasonable worst case) estimate of the concentration within leachate
of waste constituents that may eventually impact ground water. Leaching test
results must be coupled with site-specific factors, (e.g., soil cation  exchange
capacity, ground-water pH, and depth to ground water)  when  used  to design
monitoring programs, determine  potential for inter-media impacts, and evaluate
options for contaminated-soil corrective measures.  When assessing  leach test
results, specific hazardous constituent concentrations in the leachate will  be
compared with the health and environmental criteria  concentrations  for water
described in Section 8.

     The descriptive approach and the use of mathematical models (such as the
RITZ Model, discussed  previously)  may  be appropriate in those cases where
assumptions implicit in the use of leaching tests  may not be applicable.  For
example, leaching tests may be overpredictive of leachate concentrations where
extensive channeling  (e.g., because of root zone  or joints) through  the
contaminated zone is present; in this case, the contact time between the leaching
fluid (e.g., infiltrating precipitation) and the soil, as well as the surface area of the
soil exposed to the fluid, would be less than that simulated by the leaching test.
Leaching tests may also not be applicable where low redox (reduction/oxidation)
conditions are identified. Consideration of redox conditions is particularly relevant
for inorganics.

     The Agency has devised a soils/waste mixture leaching procedure, known as
the Synthetic Precipitation Leach Test (Method 1312) that it generally believes may
be appropriate for evaluating the potential impact of contaminated  soils  on
ground-water quality.   (See Appendix F for a description of this procedure).
Although neither Method  1312 nor any other leaching test (such as the Toxicity
Characteristic Leaching Procedure (Method 1311) have been validated for use on a
wide range of contaminated-soil types, the Agency believes that Method 1312 may
have the broadest applicability.   Method 1312 may be particularly appropriate
when no future waste management or other industrial  activities likely to  produce
an acidic leaching medium are likely to be conducted at the site of the release.
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     However, other leaching tests may be appropriate under certain case-specific
circumstances. For example, a test such as Method 1311  may be appropriate at a
release site that will be used for management of municipal refuse or a similar waste
in the future, because the refuse could produce an acidic leaching medium, which
Method 1311 has been designed  to simulate.  The evaluation of leaching from
cyanide-containing soils should  be performed with neutral water, rather than an
acidic leaching medium, because leaching of cyanide-containing waste under acidic
conditions may result in the formation of toxic hydrogen cyanide gas.  Other
leaching test variations may be necessary if interactive effects on mobility are
caused by non-aqueous solvents,  for example, or if an aqueous phase leaching
medium may underpredict  potential  mobility due to site and waste constituent
characteristics.

9.4.4.3.2   Estimating Impact on Ground-Water Quality

     In evaluating results obtained using the leach test for the evaluation of
contaminants of concern at a specific release site, the Agency will consider relevant
hazardous constituent properties,  the physical and chemical characteristics of the
soil/waste  matrix at the site, and local climatological factors. Factors that will be
considered include the following:

     •     Chemical structure, classification, and bonding (organic vs.  inorganic,
          ionic vs. covalent, etc);

     •     Solubility of the constituents;

     •     Octanol/water or other partitioning coefficients;

     •     Density;

     •    Organic carbon adsorption coefficient;

     •    Volatility (e.g., Henry's Law constant);

     •    Dissociation constants (Pk);
                                   9-51

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     •    Degradation potential (hydrolysis, biodegradation);

     •    Soil/waste matrix characteristics;

     •    Cation exchange capacity;

     •    Soil pH and Eh;

     •    Soil classification (e.g., clay, silt, and sand content);

     •    Particle-size distribution;

     •    Porosity;

     •    Unsaturated hydraulic conductivity;

     •    Climatological characteristics;

     •    Precipitation patterns (volume, frequency, etc.); and

     •    pH of local or regional precipitation.

     The results obtained from a specific leach test must be supported  by an
analysis of the relevant factors, such as those listed above, and considering the likely
future use of the site (industrial, waste management, residential, etc.).

     As an  alternative approach to the  use of a  leach  test  for  evaluating
contaminated soil, the owner or operator may propose to perform an analysis of the
waste, soil, and Climatological conditions, considering such factors as are listed
above, to demonstrate-that the expected concentrations of any constituents that
could leach from any contaminated section of the subsurface soils would not exceed
the action levels for ground-water. This analysis, which would require appropriate
technical justification  and should rely as much as  possible on data (such as the
results of published field studies conducted under environmental conditions similar
to those at the release site), must be based on conservative assumptions related to
                                    9-52

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future changes in environmental conditions and land use (e.g., the use of the site
for future non-hazardous waste management).

     At the present time, studies are being designed to more fully examine various
methods for evaluating leaching  of hazardous  constituents from  contaminated
soils.  Further guidance will be provided by the Agency upon completion of these
studies.  It is recommended that the owner or operator review the procedures and
methods described in Sections 8 and  9 and Appendix J of Petitions to Delist
Hazardous waste. EPA/530-SW-85-003, as well as SW-846, to assist in determining
the appropriateness of  any particular leaching procedures for  evaluating
contaminated soils.   Until more definitive guidance is available,  the owner or
operator may propose what he believes to be the most appropriate leaching
procedure, and provide technical justification to support the proposed procedure
based on site and waste conditions at the time of the investigation.  For additional
assistance on selection of a leaching procedure, the owner or operator may contact
the Technical Assessment Branch of the Office of Solid Waste in Washington, D.C.
(202/382-4764).

     As  indicated above, waste and site-specific factors should  be evaluated,
together with leaching test concentrations, to arrive at predictions of the potential
impacts to ground water.  For example, if the  depth to ground water is great
enough, and the soil cation exchange capacity is high, the owner or operator may
be able to predict that metal species would be adsorbed by the soil  before the soil
leachate reaches the ground water. Particular attention, in this example, would be
needed to ensure that the cation exchange  capacity  of the  soil could  not be
exceeded.  The  characteristics of the  metal ions that are displaced from the
exchange sites should  also be considered.

     As another  example, the soil-water partition coefficient (Kd) is useful for
describing chemical mobility in the subsurface environment, and is widely used in
studies of ground-water contamination. For primarily aqueous  solutions, the
partitioning between  the  aqueous solution and  the solid medium can be  derived
from thermodynamic principles (Freeze and Cherry, 1979).

     More commonly, Kd is determined from batch experiments in which the
contaminated solution and geologic material of interest are brought into contact.
                                   9-53

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After a period of time has elapsed (e.g., 24-hours), the degree of partitioning of the
contaminant between the solution and the geologic material is determined. The
partition coefficient is then calculated using the following equation:

               mass of sorbed chemical/gram of solid
     Kd   =    	
               mass of chemical/ml of solution

     The relative mobility of attenuated constituents in ground water can then be
estimated as follows (after Mills, etal., 1985):
                                   Vs.
                              (1 + Kdb)/ne
where

     v    =    average linear velocity of attenuated constituent along centerline
               of plume, distance/time;
     V$   s    ground-water velocity, distance/time;
     b    =    soil bulk density, mass/volume;
     ne   *    effective porosity, dimensionless; and
     Kd   =    soil-water partition coefficient, volume/mass.
     The relative mobility of selected constituents, based on typical  partition
coefficients, is shown in Table 9-6.  It is important to note  that Kd is a simplified
measure of the relative affinity  of a chemical for the solution and the soil.  Kd is
highly site-specific, varying as a function of pH, redox conditions, soil characteristics,
and the availability of alternate solution phases (organic and inorganic liquids, or
colloidal solids).  The general effect of pH and organic matter content on partition
coefficients for metals is shown in Figure 9-3.

     The Kd value selected for use in estimating chemical mobility should reflect the
predominant chemical species in solution.  One approach to estimating solution
composition is to use thermodynamic stability diagrams, commonly  illustrated as
                                    9-54

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      TABLE 9-6  RELATIVE MOBILITY OF SOLUTES1
Group
Conservative




Slightly Attenuated
Moderately Attenuated
More Strongly
Attenuated
•
Examples
Total Dissolved
Solids
Chloride
Bromide
Nitrate
Sulfate
Boron
Trichloro-
ethylene
Selenium
Arsenic
Benzene
Lead
Mercury
Penta-
chlorophenol
Master Variables2
V
V
V
V, Redox Conditions
V, Redox Conditions
V pH, organic matter
V , organic matter
V, pH, Iron hydroxides,
V, pH, Iron hydroxides,
V , organic matter
V,pH, Sulfate
V, pH, Chloride
V', organic matter
1  Under typical ground-water conditions (i.e., neutral pH and
   oxidizing conditions). Under other conditions mobility may differ
   substantially. For example, acidic conditions can enhance the
   mobility of metals by several orders of magnitude.

2  Variables which strongly influence the fate of the indicated solute
   groups. Based on data from Mills et_ §[., 1985 and Rai and Zachara,
   1984. (V = Average Li near Velocity)
                            9-55

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            too
•Percent
 Adsorption
 by Sell
             50
                         Shift due
                         to presence
                         of soil organic
                         Mtter
                                   Typical adsorption
                                   curve for heavy
                                   metal x, on silica
                                   or aluminum silicate
                                   surface coated with
                                   soil organic matter
Typical
4dsorpt1on
curve for
heavy metal
x, on a clear
silica or
aluminum
silicate
surface
                               pH of the Soil  Solution

 a)  Generalized Heavy Metal Adsorption  Curve for Cationic Species

                           (e.g., CuOH*)
                100  -
 Percent
 Adsorption
 by Soil
50  '

X
\

Typical adsorption
curve for heavy
metal species, x,
on iron hydroxide
m





N%

«
\
\
\ \
\Shift \
x due to \
\ presence \
\ of soil \
x organic \
^ matter \
\ •
                              pH  of the Soil Solution


 b) Generalized Heavy Metal  Adsorption Curve  for Anionic Species

                           (e.g., CroJ")


Figure 9-3.      Hypothetical Adsorption Curves for A) Cations and

                B) Anions Showing Effect of pH  and Organic Matter

                (Mills etal., 1985)
                                    9-56

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Eh-pH diagrams.  These diagrams represent solution composition for specified
chemicals as a function of redox  potential (Eh) and  of pH under  equilibrium
conditions.

     Many  metals of  interest  in ground-water contamination problems are
influenced by redox conditions  that result from changes in the oxidation state of
the metal or from nonmetallic elements with which the metal can form complexes.
Garrels and Christ (1965) present a comprehensive  treatment of the  subject and
provide  numerous  Eh-pH diagrams that can be used for analysis of geological
systems.

     For any  particular point in an Eh-pH diagram, a chemical  reaction  can be
written that describes the equilibrium between the solid and dissolved phases of a
particular constituent.  The following equation represents the general form of the
equilibrium reaction:

                   aA + bB s cC + dD

where:             a, b, c, d =  number of moles of constituent
                   A and B =  reactants
                   Cand D =  products

At equilibrium, the solubility constant (K)  expresses the relation between the
reactants and the products following the law of mass action:

                   K_       IC]c [D]d
                            [A]a [B]b

     The brackets signify an effective concentration, or activity, that is reported as
molality (moles per liter). Solubility constants for  many reactions in water are
reported by Stumm and Morgan (1981). Alternatively, solubility constants can be
calculated from thermodynamic data (Gibbs free energy) for products and
reactants.  Freeze  and  Cherry (1979) describe the use of thermodynamic data to
calculate solubility constants for  several constituents common in ground water.
                                   9-57

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     An example illustrating the use of Eh-pH diagrams and the influence of redox
conditions on solution composition is shown for mercury (Hg) in Figure 9-4. The
stability diagram shown in Figure 9-4 is constructed  for mercury-contaminated
water that contains chloride (Cl) and dissolved sulfur species.  The solid lines in the
diagram represent the Eh-pH values at which the various phases are in equilibrium.
For pH values of less than about 7 and Eh  values greater than 0.5 volts (strong
oxidizing conditions), HgCl2 is the dominant dissolved species.  For pH  values
greater than 7, and at a high redox potential, Hg(OH)2 is the dominant dissolved
species. The main equilibrium reaction in this Eh-pH environment is:

                   HgO + H2O = Hg (OH)2

     From the law of mass action, the solubility relationship for this reaction is
written as follows:

                             [Hg(OH)2]
                             [HgO] [H20]

     At 25«C, the solubility constant (log K) for this reaction is -3.7 (Freeze and
Cherry, 1979). The activity coefficients for a solid (HgO) and H2O are assumed to be
one; therefore, the concentration of Hg(OH)2 in solution is calculated as follows:

[Hg(OH)2] = K = 10-3.7 = 1.995 x 10-4 moles/I = 47 mg/l (mol. wgt. = 235 g/mole)

     The Eh-pH diagram can be used to estimate the concentration  of mercury in
solution at any particular point in the diagram if the solubility constant for the
appropriate equilibrium reaction is known.  For lower redox conditions (pH = 6.0,
Eh = 0.0), the concentration of mercury in solution would be approximately 0.025
mg/l (Callahan et al., 1979).

     Several limitations are associated with the use of Eh-pH diagrams to predict
dissolved chemical species, including the accuracy of thermodynamic data, the
assumption of equilibrium conditions,  and of other chemical processes such  as
adsorption  that can maintain concentrations below those that would exist as a
result of only solubility constraints.  However, the Eh-pH diagrams serve to illustrate
                                   9-58

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1.20
1.00
   0     2     4     6      8      10     12     14
   Figure 9-4.  Fields of Stability for Aqueous Mercury at 25°C
              and Atmospheric Pressure (Callahan et al., 1979)
                            9-59

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that solution composition depends on redox potential and that chemical mobility
within a ground-water system may vary from one zone to another.

9.5       Data Presentation

    The owner or operator will be required to report on the progress of the RFI at
appropriate intervals during the investigation. The data should be reported in a
clear  and concise manner, with interpretations supported  by  the data.   The
following data presentation methods are suggested for soil investigations.  Further
information is provided in Section 5.

9.5.1      Waste and Unit Characterization

    Waste and unit characteristics may be presented as:

    •    Tables of waste constituents and concentrations;

    •    Tables of  relevant physical and  chemical properties of waste and
          constituents;

    •    Narrative description of unit operations; and

    •    Surface map and plan drawings of the facility and waste unit(s).

9.5.2      Environmental Setting Characterization

    Environmental characteristics may be presented as:

    •    A map and narrative description of soil classifications;

    •    Soil boring logs;

    •    Measurements of soil physical or hydrologic characteristics; and

    •    Onsite survey results (e.g., OVA, portable  gas chromatograph,
          geophysical techniques).

                                   9-60

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     Soil and site map(s)-ln addition to the required RCRA permit site topographic
map, the owner or operator should prepare a map(s) displaying the location of
surface soil types (described according to the appropriate classification system),
paved areas, areas of artificially compacted soil, fill or other disturbed soil, and
other features that could affect contaminant distribution. Specific guidance on the
use of maps and  other techniques such as aerial photographs  and geophysical
surveys is provided in Appendices A and C.

     The owner or operator should develop maps of unconsolidated geologic
materials at the site.  These maps should  identify the thicknesses, depths, and
textures of soils, and the presence of saturated regions and other hydrogeological
features. Subsurface soils should be identified according to accepted methods for
description of soils (See Section 9.3.3.3). Figure 9-5 displays a typical soil boring log.

     Graphical  methods commonly used to display soil  boring data are cross-
sections,  fence diagrams, and isopach maps.  Cross-sections are typically derived
from borings taken along a straight line through the site. Plotting the stratigraphy
of surf id a I deposits against horizontal distance  between sampling  points  gives a
vertical profile or transect.  Fence diagrams can depict the same type of information
between points that are not in a straight line.  An  isopach  map resembles a
topographic map, however, the  isopleth lines on  an isopach map represent units of
thickness of a particular soil layer rather than elevations.  For example, a map of clay
isopachs  may be used to show  the thickness in  feet of a low permeability layer
below a  waste  lagoon.  Generally, to verify lateral continuity, more than one
transect through a site will be necessary. When it is important to indicate the areal
extent of a layer (e.g., where a clay lens is suspected to cause lateral transport in the
unsaturated zone) both vertical and horizontal presentations may be necessary.
Graphical methods are discussed in detail  in Section 5 (Data Management and
Presentation).

9.5.3     Characterization of the Release

     Graphical displays of contaminant distributions in soil may include:
                                   9-61

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Figure 9-5. Example of a completed boring log
                9-62

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        9-63

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     •   Area/site maps with concentrations  indicated by numerical values,
         symbols, or isoconcentration lines;

     •   Three-dimensional isopleth plots of concentrations (including stack
         maps), such as are produced by computer graphics; and

     •   Vertical concentration contours (isopleths) plotted along a transect or
         fence diagram.

     All graphical displays should be accompanied  by data tables showing
concentrations for each sampling location.

9.6      Field Methods

     Both soil and soil-pore water sampling may be utilized in the investigation.
Chemical analysis of soil core samples may be used to characterize constituents of
concern that are adsorbed to the solid matrix.  Lysimeters can  be  installed in
boreholes created during core sampling to identify mobile constituents that  may
migrate to ground water. In addition, field screening methods may be used to help
determine the presence  and extent of releases.

     Appropriate sample collection and preservation techniques should be
specified.  When a soil  sample is removed from its surroundings, chemical  and
physical changes can  begin immediately.  These changes include moisture  loss,
oxidation, gas exchange, loss of volatile  components, increased or decreased
biological activity, and potential contamination  of the sample.  Therefore,
appropriate measures must be taken to store and  preserve samples to minimize
their degradation. Sampling techniques should not adversely affect analytical
procedures and hence results.  For example, use of fluids other than water during
drilling can introduce organic  or inorganic  contaminants  that  may make
quantification of the contaminants of concern impossible.  The practice of coating
metal parts of drilling equipment with oils or greases to prevent  rust will have a
similar effect.

     Volatile compounds can sometimes be detected near the soil surface using
rapid, field screening methods (e.g., portable photoionization detector such as  HNu
                                   9-64

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or Photovac or an organic vapor analyzer (OVA)).  Organic vapors caji also  be
detected and measured in shallow boreholes or in ground-water monitoring wells.
Vapor sampling is especially useful for initial characterization because it is a rapid,
semi-quantitative technique.  Benefits of field screening methods include:

     •    The investigator can, in certain cases, quickly determine whether a
          sample is contaminated, thus, aiding  in the identification of areas of
          concern;

     •    Samples that may undergo chemical changes with storage can  be
          evaluated immediately; and

     •    These techniques can be used to  investigate releases to several  media
          simultaneously (e.g., subsurface gas, ground water and soil).

     However, there are limitations in using field screening methods, including:
                                                                          i
     •    They cannot always account for all constituents that may be present in
          the release;

     •    They may not be able to quantify concentrations of specific constituents
          of concern; and

     •    Constituents may be present at levels below detection capability.

Field-screening  methods are described in the Compendium of Field  Operations
Methods (EPA, 1987).

     Soil sampling methods will commonly vary with  the depth of interest.  For
purposes of the RFI, these methods  are  described  as  "surficial" or "subsurface".
Surficial sampling in the upper 20 cm of soil can usually be accomplished with simple
tools, including shovels, spatulas, soil punches, and ring samplers. Contaminants
that have moved further downward  in the soil profile often require tools such as
tube samplers and augers. Manually operated tools are commonly useful to about 1
to 2 meters in depth, depending on the soil type.  Below this depth, hydraulically or
mechanically driven equipment is generally needed (See Everett  et al, 1984  for
                                   9-65

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additional information on soil sampling techniques, as well as Sections 3 and 7 of
this Guidance for discussions of additional sampling methods and references).
                                             •
     Methods to sample  soil-pore water or other fluids are presented in Section
9.6.3.

9.6.1      Surficial Sampling Techniques

     Surficial soils may also contain various materials, including rocks, vegetation,
and man-made items.  The owner or operator should propose how these materials
will be treated (i.e., whether they will be discarded  or analyzed separately). Care
should be taken in choosing sampling equipment that will not adversely affect the
analytical objectives (e.g., painted or  chrome/nickel plated equipment  may
adversely  affect metals analyses).   Some commonly used surficial soil sampling
techniques are discussed below.

9.6.1.1    Soil Punch

     A soil punch is a thin-walled steel tube that is commonly 15 to 20 cm long and
1.3cm to 5.1 cm in diameter.  The tube is driven into the ground with a wooden
mallet and twisted to free the sample. The punch is pulled out and the soil pushed
or shaken from the tube.  This technique is rapid but  is generally not useful in rocky
areas or in loose, granular soils that will not remain  in the punch. Soil punching is
not useful for soil structure descriptions because the method  causes compaction
that destroys natural fractures.

9.6.1.2    Ring Samplers

     A ring sampler consists of a 15 to 30 cm diameter steel ring that is driven into
the ground.  The soil is subsequently removed for analysis. This technique is useful
when results are to be  expressed on a unit area basis, because the soil ring contains
a known area of soil. Ring samplers will generally not be useful in loose, sandy soils
or stiff clays.
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9.6.1.3    Shovels, Spatulas, and Scoops

     Collection of grab samples by shovel, spatula, or scoop is not recommended if
sample area or volume determinations are required (the two previous methods are
more accurate).  The reproducibility of sample size is limited and subject to sample
bias. The principal advantages of grab sampling are the efficiency of collection and
the fact that samples may indicate the range of contaminant concentrations at the
site.

9.6.1.4    Soil Probes (tube samplers)

     Manual soil probes are designed to obtain samples from the upper two meters
of the soil profile. The soil  probe is commonly a stainless-steel or brass tube that is
sharpened and beveled on one end and fitted with a T-handle.  Soil probes are
common agricultural tools and can be obtained in several diameters. The probe is
pushed into the soil in 20 to 30 cm increments.  At the desired depth, the tube is
pulled out and the soil sample extruded.  The sample  may  be  considered
"disturbed" or "undisturbed" depending on whether it can be removed intact. The
samples, however, are generally considered to be disturbed for the  purposes of
engineering or physical measurements. Loose soils will be difficult to sample with
this tool, and the borehole will tend to collapse when the tube is withdrawn to
obtain samples.

9.6.1.5    Hand Augers

    Augers have a spiral cutting blade that transports soil cuttings upwards. Hand-
operated augers are generally used to a depth of approximately 6 feet.  Single flight
augers are pulled from the ground periodically and soil samples are taken from the
threads of the auger. Continuous flight augers transport the loosened soil to the
top of the borehole, where it can be collected.  Augers provide highly disturbed
samples.  Limited information can be obtained on soil structure, bulk density, or
permeability.  Cross-contamination between  soil layers  is likely  and  depth
information on various soil layers is not reliable. Therefore, reliance on augering as
a sole sampling technique is not recommended. Augering may be used, however, in
conjunction with tube sampling that obtains undisturbed samples.
                                   9-67

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9.6.2      Deep Sampling Methods

     The subject of deep drilling is discussed more extensively in the section on
ground-water sampling (see Section 10), because deep cores will generally be taken
in conjunction with drilling for monitoring well emplacement.  There are some
techniques that are of particular importance to soil sampling and, therefore, a brief
discussion is included here. Procedures for sampling with split-spoon and thin-wall
tube corers and other equipment are presented in Section 7.

9.6.2.1    Hollow-Stem Augers

     Hollow-stem augers have a continuous flight-cutting blade around a hollow
metal cylinder.  A stem with a  plug  is ordinarily kept inside the auger barrel to
prevent soil from entering. When core samples are desired, the stem is withdrawn
and a tube sampler may be inserted  to the bottom of the borehole.  This drilling
method may be used for continuous soil sampling.  An additional advantage of
hollow-stem augers is that they do not require drilling fluids.

9.6.2.2    Solid-Stem Augers

     Solid-stem augers, as the name implies, are augers that do not have an inner
barrel. As with the manual variety, single-flight  augers must be withdrawn each
time a sample is desired, or samples may be taken from the cuttings brought to the
surface by augers of the continuous flight type.  Augers may be used in conjunction
with tube samplers by withdrawing  the auger and obtaining a sample from the
bottom of the borehole. This sampling approach is only useful with soils that do not
cave in or crumble after drilling.

9.6.2.3    Core Samplers

     Soil coring devices that may be used with hydraulically or mechanically- driven
drilling rigs include thin-walled Shelby tubes and split-spoon samplers. These are
two of the most common samplers and are discussed below.
                                   9-68

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9.6.2.3.1   Thin-Walled Tube Samplers

     The Shelby tube is a metal cylinder with the end sharpened and beveled for
cutting into the soil. Common sizes used for field investigations are 1 to 3 inches in
diameter. The tube is pushed down into the soil with a smooth even motion by
applying downward pressure from a drilling rig or other apparatus.  Thin-walled
tubes produce high quality undisturbed cores that can be used for engineering and
hydraulics testing but are useful only in cohesive soils as loose soils may fall out of
the tube during removal. The soil must be extruded from the tube in a laboratory or
in a field extruding unit because  core removal  is generally difficult.  For rapid
characterization of the  soil stratigraphy  in the field, split-spoon samplers are
recommended.

9.6.2.3.2   Split-Spoon Samplers

     A split-spoon consists of a hollow steel cylinder split in half and screwed into
an "unsplit" outer tube and tip. This assembly can be connected to drill rods. The
tube is commonly forced into the soil by applying a 140 pound sliding hammer,
dropping 30 inches along the drill rod (ASTM, 1986). The number of hammer blows
required to advance the sampler in six inch increments is recorded.  The total blow
count number  for the second  and third increments is related to a standard
engineering parameter indicating  soil density.  After the tube is pulled from the
soil, the cylinder is removed from the drill rod and opened, exposing the soil core.
Core samples may be used to determine stratigraphy, for chemical and grain-size
analysis, or for pore water extraction.  Split-spoons are the preferred  method for
obtaining unconsolidated  soil samples and may also be used to penetrate some
types of rock.

9.6.2.4    Trenching

     Trenches and test pits  are  useful  where detailed examination of soil
stratigraphy and geology is required. Trenching is generally limited for practicality
to the top eight feet of soil.  Shallow trenches may be dug manually, but in most
instances, a backhoe will be faster and  easier.  Bulk soil samples may be obtained
with this method.
                                   9-69

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9.6.3     Pore Water Sampling

     When contaminants are suspected of migrating readily through the soil with
infiltrating water, monitoring of water or other fluids in the unsaturated zone may
be appropriate.  Sampling soil pore water before it reaches the water table can
provide an early warning of threats to ground water.

     Compounds for which pore water sampling may be useful are those that are
moderately to highly water soluble and thus are not appreciably retained on soil
particles. Examples include poorly adsorbed inorganics such as cyanide or sulfate,
halogenated solvents such as ICE, and organic acids. Due to the mobility of these
compounds, pore water sampling will be most useful for current releases.

     A common pore water  collection technique  uses a suction device called a
pressure vacuum lysimeter, which consists of a porous ceramic cup connected by
tubing to a collection flask and vacuum pump (Figure 9-6). The lysimeter cup may
be permanently installed in a borehole of the appropriate depth, and if the hole is
properly backfilled. Suction from the pump works against soil suction to pull water
out of the  silica flour surrounding the cup. This method will  not work well in
relatively dry soils.

     An advantage of this method is that the installation is " permanent," allowing
multiple samples from one spot to  measure changes in pore water quality with
time.  Limitations include:

     •   Measurements cannot be correlated  accurately with soil concentrations
         because the sample is obtained from an unknown volume of soil;

     •   Lysimeters are subject to plugging and are difficult to install in fractured
         or rocky soils;

     •   Some organic and inorganic constituents may be adsorbed by the
         ceramic cup  (Teflon porous suction lysimeters may overcome this
         problem); and
                                   9-70

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 PRESSURE-VACUUM
  ACCESS TUBE
    BENTONITE
NEOPRENE PLUG
 PLASTIC BODY
 BENTONITE
     POROUS
     CERAMIC
      TIP
                       ACCESS  LINES
                  (1/V POLYETHYLENE
                         TUBING)
                            I
                                     DISCHARGE TUBE
                     AUGERED HOLE
                      V DIAMETER
                                        BACKFILL
                                      POWDERED QUARTZ
                                      BENTONITE
 Figure 9-6. Typical Ceramic Cup Pressure/Vacuum Lysimeter
                          9-71

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     •    Volatile organics will be lost unless a special organic* trap is installed in
          the system.

9.7  Site Remediation

     Although the RFI Guidance is not intended to provide detailed guidance on
site remediation, it should be recognized that certain data collection activities that
may be necessary for a Corrective Measures Study may be collected during the RFI.
EPA has developed a practical guide for assessing and remediating contaminated
sites that directs users toward technical support, potential data requirements and
technologies that may be applicable to EPA programs such as  RCRA and CERCLA.
The reference for this guide is provided below.

     U.S. EPA.  1988.  Practical Guide for Assessing and Remediating Contaminated
     Sites.  Office of Solid  Waste and Emergency Response.  Washington, D.C.
     20460.                                                                t

     The guide is designed to address releases to  ground water as well  as soil,
surface water and air. A short description of the guide is provided in Section 1.2
(Overall RCRA  Corrective  Action Process), under  the discussion of  Corrective
Measures Study.
                                   9-72

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9.8  Checklist
                            RFI CHECKLIST-SOILS
Site Name/Location	

Type of unit	

1.    Does waste characterization include the following information ?      (Y/N)

              Identity and composition of contaminants                	
              Physical state of contaminants                           	
              Viscosity                                              	
              PH                                                   	
              pKa                                                  ~~
              Density                                               	
              Water Solubility
              Henry's Law Constant                                  	
              Kpw                                                  	
              Biodegradability                                       	
              Rates of hydrolysis, photolysis and oxidation              	

2.    Does unit characterization include the following
     information?                                                   (Y/N)

              Age of unit                                           	
              Construction integrity                                  	
              Presence of liner (natural or synthetic)                    	
              Location relative to ground-water table
              or bedrock or other confining barriers                    	
              Unit operation data                                    	
              Presence of cover                                      	
              Presence of on/offsite buildings                         	
              Depth and dimensions of unit                           	
              Inspection records                                     	
              Operation logs                                        	
              Presence of natural or engineered barriers
              near unit                                             	

3.    Does environmental setting information include the following
     information?                                                   (Y/N)
              Site soil characteristics
              Surface soil distribution map
              Soil moisture content
              Predominant soil phase to sample (solid, liquid, gaseous)
              Soil classification
              Particle size distribution
                                    9-73

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              RFI CHECKLIST-SOILS
                  (Continued)
Porosity
Hydraulic conductivity (saturated and unsaturated)
Relative permeability
Soil sorptive capacity
Cation exchange capacity
Organic carbon content
Soil pH
Depth to water table
Pore water velocity
Percolation
Volumetric water content
Have the following data on the initial phase of the release
characterization been collected?

          Geological and climatological data
          Facility records and site-specific investigations
          Area of contamination
          Distribution of contaminants within study area
          Depth of contamination
          Chemistry of contaminants
          Vertical rate of transport
          Lateral rate of transport in each stratum
          Persistence of contaminants in soil
          Potential for release from surface soils to air
          Potential for release from surface soils to
          surface water
          Existing soil/ground-water monitoring data
          Evidence of vegetative stress
          Potential for release to ground water
          Potential receptors

Have the following data on the subsequent phase(s) of the
release characterization been collected?

     •    Further soil stratigraphic and hydrologic
          characterization data
     •    Expanded sampling data
     •    Geophysical data on release location
                                                      (Y/N)
                                                      (Y/N)
                      9-74

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9.9   References

ASTM. 1984. Particle Size Analysis for Soils. Annual Book of ASTM Standards,
     Method D422-63. Vol. 4.08. Philadelphia, PA.

ASTM. 1984. Standard Recommended Practice for Description of Soils. Annual
     Book of ASTM Standards, Method D2488-69. Vol. 4.08.  Philadelphia, PA.

Barth, D. S., and B. J. Mason. 1984. Soil Sampling Quality Assurance User's Guide.
     EPA 600/4-84-043. NTIS PB84-198621. U.S. EPA. Las Vegas, Nevada.

Black, C. A.  1965. Methods of Soil Analysis. Part 2: Chemical  and Microbiological
     Properties. American Society of Agronomy. Madison, Wisconsin.

Callahan.M. A.,etal.  1979. Water-Related Environmental Fate of 129 Priority
     Pollutants.  Vol. 1 and 2, EPA  440/4-79-029a. NTIS PB80-204373.  U.S. EPA,
     Washington, D.C. 20460.

Elliot, L F., and F. J. Stevenson. 1977. Soils for Management of Organic Wastes
     and Waste  Waters.  Soil  Science Society  of America, American  Society of
     Agronomy, Crop Science Society of America. Madison, Wisconsin.

Everett, L G., L. G. Wilson, and E. W. Hoylman. 1984. Vadose Zone Monitoring
     for Hazardous Waste Sites. Noyes Data Corporation.  Park Ridge, New Jersey.

Ford, P. J., etal. 1984. Characterization of Hazardous Waste  Site - A Methods
     Manual. Vol. II. Available Sampling Methods. NTIS PB85-168771.  U.S. EPA.
     EPA 600/4-84-076. Las Vegas, Nevada.

Freeze and Cherry. 1979. Ground Water. Prentice-Hall, Inc.,  Englewood Cliffs,
     N.J.

Garrels, R.M. and  C.L. Christ.  1965. Solutions. Minerals, and Eguilibria. Harper
     and Row, New York.
                                   9-75

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Lambe,T.W. and R.V. Whitman. 1979. Soil Mechanics. SI Version. John Wiley and
     Sons, Inc., New York, New York.

Lyman.W.J. Reehl,W. F. and D. H. Rosenblatt. 1981.  Handbook of Chemical
     Property Estimation Methods. McGraw Hill.

Mason, B.J. 1983. Preparation of a Soil Sampling Protocol: Techniques and
     Strategies. NTIS PB83-206979. U.S. EPA. Las Vegas, Nevada.

Mills, W.B., etal. 1985. Water Quality Assessment: A Screening Procedure for
     Toxic and Coventional Pollutants in Surface and Ground Water.  EPA/600/6-
     85/002a,b, c.   Vol. I, II and III. NTIS PB86-122494,  122504 and  162195.
     Washington, D.C. 20460.

Morrill, L G., L. W. Reed, and K. S. K. Chinn. 1985. Toxic Chemicals in the Soil
     Environment. Volume 2:  Interactions of Some Toxic Chemicals/Chemical
     Warfare Agents and Soils. AD-A158-215. U.S. Army Dugway Proving Ground. *
     Dugway, Utah.

Oster, C. A. 1982. Review of Ground Water Flow and Transport Models in the
     Unsaturated Zone.  PNL-4427.  Battelle  Pacific Northwest  Laboratory.
     Richland,WA.

Rai, D. and J.M.Zachara. 1984. Chemical Attenuation Studies: Data
     Development and Use.   Presented at Second Technology Transfer Seminar:
     Solute Migration in Ground Water  at Utility Waste Disposal Sites.  Held in
     Denver, Colorado. October 24-25,1985. EPRI-EA-3356.

Sims, R. C., et al. 1984. Review of In-Place Treatment Techniques for
     Contaminated Surface Soils. Volume 2: Background Information for In Situ
     Treatment.  EPA-540/2-84-003b. NTIS PB85-124899. U.S.  EPA. Washington,
     D.C. 20460.

Stumm, W, and J.J. Morgan. 1981. Aquatic Chemistry. An Introduction
     Emphasizing Chemical Equilibria in Natural Waters. John Wiley and
     Sons. New York, N.Y.
                                  9-76

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U.S.D.A. (U.S. Department of Agriculture). 1975.  Soil Taxonomy: A Basic System
     of Soil Classification for Making and Interpreting Soil Surveys.  Soil Survey
     Staff, Soil Conservation Service. Washington, D.C.

U.S. EPA. 1975. Use of the Water Balance Method for Predicting Leachate
     Generation from Solid Waste Disposal Sites. EPA/530/SW-168. Office of Solid
     Waste. Washington, D.C. 20460.

U.S. EPA. 1982. Sediment and Soil Adsorption Isotherm. Test Guideline No. CG-
     1710.   In:  Chemical Fate Test Guidelines. EPA  560/6-82-003.  NTIS PB82-
     233008. Office of Pesticide and Toxic Substances. Washington, D.C. 20460.

U.S. EPA. 1982. Sediment and Soil Adsorption Isotherm. Support Document No.
     CS-1710.  in:  Chemical  Fate Test Guidelines. EPA 560/6-82-003.  NTIS PB83-
     257709. Office of Pesticide and Toxic Substances. Washington, D.C. 20460.

U.S. EPA. 1984. Soil Properties. Classification and Hydraulic Conductivity
     Testing. EPA/SW-925. Office of Solid Waste. Washington, D.C. 20460.

U.S. EPA. 1985. Handbook: Remedial Action at Waste Disposal Sites (Revised).
     EPA/625/6-85/006.   NTIS PB82-239054.  Office of Emergency and Remedial
     Response. Washington, D.C. 20460.                        •

U.S. EPA. 1986. Criteria for Identifying Areas of Vulnerable Hydroqeoloqy Under
     the Resource Conservation and Recovery Act.  NTIS PB86-224953. Office of
     Solid Waste. Washington, D.C. 20460.

U.S. EPA. 1986. Petitions to Delist Hazardous Wastes.  EPA/530-SW-85-003. NTISPB
     85-194488. Office of Solid Waste. Washington, D.C. 20460.

U.S. EPA. 1986. Test Methods for Evaluating Solid Waste. EPA/SW-846. GPONo.
     955-001-00000-1. Off ice of Solid Waste. Washington, D.C. 20460.

U.S. EPA. June  13,1986. Federal Register. Volume 51, Pg. 21648. TCLP Proposed
     Rule.
                                   9-77

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U.S. EPA. 1986. Permit Guidance Manual on Hazardous Waste Land Treatment
     Demonstration. NTISPB86-229192. Office of Solid Waste. Washington, D.C.
     20460.

U.S. EPA. 1987. Soil Gas Monitoring Techniques Videotape. National Audio Visual
     Center. Capital Heights, Maryland 20743.

U.S. Geological Survey. 1982. National Handbook of Recommended Methods for
     Water Data Acquisition.
                                  9-78

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                                SECTION 10

                             GROUND WATER

10.1 Overview

     The objective of an investigation  of a release to ground water  is to
characterize the nature, extent, and rate of migration  of a release of hazardous
waste or constituents to that medium. This section provides:

     •   An example strategy for characterizing releases to ground water, which
         includes characterization of the source and the environmental setting of
         the release, and conducting a  monitoring  program  which  will
         characterize the release itself;

     •   Formats for data organization and presentation;     '                 '

     •   Field methods which may be used in the investigation; and

     •   A checklist of information that may be needed for release character-
         ization.

     The exact type and  amount  of information required for sufficient  release
characterization will be site-specific and should be determined through  interactions
between the regulatory agency and the facility owner or operator during  the RFI
process. This guidance does not define the specific data needed in all instances;
however,  it identifies possible  information necessary  to perform  release
characterizations and methods for obtaining  this information. The RFI Checklist,
presented at the end  of this section, provides a tool  for planning and tracking
information for release characterization.  This list is not meant as a list of
requirements for all releases to ground water.  Some  release investigations will
involve the  collection of only a subset of the items listed, while others may  involve
the collection of additional data.
                                   10-1

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10.2 Approach for Characterizing Releases to Ground Water

10.2.1     General Approach

     A conceptual model of the release should be formulated using all available
information on the waste,  unit characteristics, environmental setting, and any
existing monitoring data.  This model (not a computer or numerical  simulation
model) should provide a working hypothesis of the release mechanism, transport
pathway/mechanism, and exposure route (if any).  The model should be
testable/verifiable and flexible enough to  be  modified as new data become
available.

     For ground-water investigations, this model should account for the ability of
the waste to be dissolved or to  appear as a distinct phase (i.e., "sinkers" and
"floaters"), as well as geologic and hydrologic factors which affect the release
pathway.  Both the regional and site-specific ground-water flow regimes should be
considered in determining  the potential magnitude of the release, migration t
pathways  and possible exposure routes.  Exposure  routes of concern  include
ingestion of ground water as drinking water and near-surface flow of contaminated
ground  water into basements of residences or other structures (see Appendix E).
This "basement seepage"  pathway can  pose threats through  direct contact,
inhalation of toxic vapors and through fires and explosions if the contaminants are
flammable. The model should consider the degradability (chemical and biological)
of the waste and its decomposition  products. The conceptual model should also
address  the potential for the transfer of contaminants in  ground water to other
environmental media (e.g., discharge to surface water and volatilization to the
atmosphere).

     Based on the conceptual model, the owner or operator should develop  a
monitoring program to determine  the nature, extent, and  rate of migration of
contaminant releases from  SWMUs* to ground water.   Three-dimensional
characterization  is particularly important.  The initial monitoring phase  should
     Guidance in this section applies to releases from all solid waste management units, except
     releases to ground water from "regulated units" as defined under 40 CFR Part 264.90(a)(2).
     Releases to ground water from "regulated units" must be addressed according to the
     requirements of 40 CFR Parts 264.91 thorugh 264.100 for purposes of detection,
     characterization and appropriate response.
                                    10-2

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include a limited number of monitoring wells, located and screened in such a way
that they are capable of providing background water quality and of intercepting
any release. The regulatory agency will evaluate the adequacy  of an existing
monitoring system, if proposed for use in the initial monitoring phase. The owner
or operator may be required to install new wells if the existing well system is found
to be inadequate.

     Initial ground-water sampling and analysis may be conducted for a limited set
of monitoring  constituents.  This set should include a subset of the hazardous
constituents of concern, and may also include indicator parameters (e.g., TOX).
Guidance regarding the selection of monitoring constituents and indicator para-
meters is provided in Sections 3 and 7 and in Appendix B. Sampling frequency and
duration should also be proposed in the RFI Work Plan.

     Investigation of a suspected release may be terminated based on results from
an initial monitoring phase if these results show that an actual release has not, in
fact, occurred.  If, however, contamination is found, the release must be adequately
characterized through a subsequent monitoring phase(s).

     Subsequent characterization involves determining the detailed chemical
composition and the area! and vertical (i.e., three dimensional)  extent  of the
contaminant release, as well as its rate of migration. This should be accomplished
through direct sampling and analysis and, when appropriate, can be supplemented
by indirect means such  as geophysical methods (See Appendix C)  and modeling
techniques.

    Table 10-1 outlines an example of strategy  for  characterizing  releases  to
ground water.  Table 10-2 lists the specific tasks which may be used in implementing
the strategy, and the corresponding data outputs. The steps delineated in these
tables should generally  be performed in sequential order, although some may  be
accomplished  concurrently.  For example, the site's hydrogeology may  be
investigated at the same  time as waste and  unit characterization; soil  borings
installed during hydrogeologic characterization may be converted into monitoring
wells; and additional wells may be installed to more accurately  characterize a
release while a  sampling and analysis program is in effect at existing wells.
                                   10-3

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                                TABLE 10-1

                  EXAMPLE STRATEGY FOR CHARACTERIZING
                       RELEASES TO GROUND WATER1
                               INITIAL PHASE

1.    Collect and review existing information on:

         Waste
         Unit
         Environmental setting
         Contaminant releases, including inter-media transport

2.    Identify any additional information necessary to fully characterize release:

         Waste
         Unit
         Environmental setting
         Contaminant releases, including inter-media transport

3.    Develop monitoring procedures:
                                                                         i
         Formulate conceptual model of release
         Determine monitoring program objectives
         Plan field screening if appropriate (e.g., geophysical investigations - see
         Appendix C)
         Select monitoring constituents and indicator parameters
         Identify QA/QC and analytical procedures
         Appropriate initial area well locations (background and downgradient)
         Collection of additional hydrogeplogic data (if necessary)
         Proper well screen interval selection
         Borehole testing and use of test pitting
         Sampling frequency and duration of monitoring
         Identification of data presentation and evaluation procedures

4.    Conduct initial monitoring phase:

         Conduct field screening, if appropraite
         Collect samples and perform appropriate field measurements
         Analyze samples for selected parameters and constituents

5.    Collect evaluate and report results:

         Compare monitoring results to  health and environmental criteria and
         identify and respond to emergency situations and identify priority
         situations that warrant interim corrective measures - Notify regulatory
         agency
         Determine completeness and adequacy of collected data
         Summarize and present data in appropriate format
                                   10-4

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                          TABLE 10-1(Continued)

                 EXAMPLE STRATEGY FOR CHARACTERIZING
                       RELEASES TO GROUND WATER 1
                         INITIAL PHASE (Continued)

         Determine if monitoring program objectives were met
         Determine if monitoring locations, constituents and  frequency were
         adequate to characterize release (nature, rate, and extent)

                     SUBSEQUENT PHASES (If Necessary)

1.    Identify additional information necessary to characterize release:

         Perform further hydrogeologic characterization, if necessary
         Add and delete constituents or indicator parameters as appropriate
         Employ geophysical and other methods to estimate extent of release and
         to determine suitable new monitoring locations
         Inter-media transport

2.    Expand monitoring network as necessary:

         Increase density of monitoring locations
         Expand monitoring locations to new areas
         Install new monitoring wells

3.    Conduct subsequent monitoring phases:

         Collect samples and complete field analysis
         Analyze samples for selected parameters and constituents

4.    Collect, evaluate, and report  results/identify additional information necessary
     to characterize release:

         Compare monitoring results  to health  and environmental criteria and
         identify and respond to emergency situations and  identify priority
         situations the warrant  interim  corrective measures - Notify regulatory
         agency
         Summarize and present data in appropriate format
         Determine if monitoring program objectives were met
         Determine if monitoring  locations, constitutents,  and  frequency were
         adequate to characterize release (nature, extent, and rate)
         Identify additional information needs
         Determine need to expand monitoring
         Evaluate potential role of inter-media impact
         Report results to regulatory agency
    The possibility for inter-media  transport of contamination should be
    anticipated throughout the investigation.
                                   10-5

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                                             TABLE 10-2
                   RELEASE CHARACTERIZATION TASKS FOR GROUND WATER
        Investigatory Tasks
  Investigatory Techniques
Data Presentation Formats/Outputs
1.  Waste/Unit Characterization

       Identify waste properties
       (e.g., pH, viscosity)
       Identify constituents of
       concern/possible indicator
       parameters

       Determine physical/chemical
       properties of constituents

       Determine unit dimensions
       and other important design
       features and operational
       conditions

       Investigate possible unit
       release mechanisms to help
       determine flow
       characteristics
Review existing information and
conduct waste sampling if
necessary (See Sections 347)

Review existing information and
conduct waste sampling if
necessary (See Sections 3 & 7)

Review existing information (See
Section 7)

Review existing information and
conduct unit examinations (See
Section 7)
Review existing information and
conduct unit examinations (See
Section 7)
   Tabular presentation (See
   Section 5)
   Tabular presentation (See
   Section 5)
   Tabular presentation (See
   Section 5)

   Tabular presentations, facility
   maps & photographs & narrative
   discussion (See Section 5 and
   Appendix A)

   Facility maps & photographs &
   narrative discussions (See
   Appendix A)
2.   Environmental Setting
    Characterization

       Examine surface features &
       topography for indications
       of subsurface conditions
       Define subsurface conditions
       & materials, including soil
       and subsurface physical
       properties (e.g, porosity,
       cation exchange capacity)
Review existing information,
facility maps, aerial & other
photographs, site history,
conduct surface geological
surveys

Review of existing geologic
information

Soil borings and rock corings

Soil & subsurface material
testing
                                      Geophysical technqiues (See
                                      Appendix C)
   Facility map & photographs/text
   discussion (See Appendix A & C)
   Narrative discussions of geology
   Boring and coring logs

   Subsurface profiles, transects &
   fence diagrams (See Appendix A
   & Section 5)

   Tabular presentations of soil &
   subsurface physical & chemical
   properties

   Geologic cross sections &
   geologic & soil maps (See Section
   5 &9& Appendix A)

   Structure contour maps (plan
   view) of aquifer & aquitards (See
   Section 5 & Appendix A) '
                                                 10-6

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                                         TABLE 10-2
         RELEASE CHARACTERIZATION TASKS FOR GROUND WATER (continued)
     Investigatory Tasks
  Investigatory Techniques
Data Presentation Formats/Outputs
Environmental Setting
Characterization (Continued)

    Identification of regional
    flow cells, ground-water
    flow paths & general
    hydrology, including
    hydraulic conductivities &
    aquifer interconnections
   Identification of potential
   receptors
Review of existing information

Installation of piezometers &
water level measurements at
different depths

Flow cell & flow net analyses
using measured heads

Pumping & slug tests & tracer
studies

Geophysical techniques (See
Appendix C)
Review of existing information,
area maps, etc.
   Narrative descriptions of
   ground-water conditions, flow
   cells, flow nets, flow patterns,
   including flow rates & direction

   Water table or potentiometric
   maps (plan view) with flow lines
   (See Section 5)

   hydrologic cross sectional maps
   (See Section 5)

   Flow nets for vertical  &
   horizontal  flow

   Tabular presentations of raw
   data & interpretive analysis
                          I
   Narrative discussion & area maps
Release Characterization

   Determine background
   levels & determine vertical
   and horizontal extent of
   release, including
   concentrations of
   constituents & determine
   rate & directions of release
   migration
Sampling & analysis of ground-
water samples from monitoring
system
Geophysical methods (See
Appendix Q for detecting &
tracking plume

Modeling to estimate extent of
plume & rate & direction of
plume migration
   Tabular presentations of
   constituent & indicator
   parameter analyses (See Section
   5)

   Iso-concentrations maps of
   contamination (See Section 5)
                                                                     Maps of rates of release
                                                                     migration & direction showing
                                                                     locations of possible receptors
                                                                     (See Section 5)

                                                                     Narrative discussion &
                                                                     interpretations of tabular &
                                                                     graphical presentations
                                             10-7

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     The specific tasks to be conducted for each release will be determined on a
site-specific basis.  It should be noted that some of the characterization tasks may
have been previously accomplished  in conjunction with  the 40 CFR Parts 264
and 265, Subpart F (ground-water monitoring) regulations.

     As monitoring data become available, both within and at the conclusion of
discrete investigation phases, it  should be reported to the regulatory agency as
directed. The regulatory agency will compare the monitoring  data to applicable
health and environmental criteria to determine the need for (1) interim corrective
measures; and/or  (2) a Corrective Measures Study.  In addition, the regulatory
agency will evaluate the monitoring data with respect to adequacy and
completeness to determine the need for any additional monitoring efforts. The
health and environmental criteria and a general discussion of how the regulatory
agency will apply them are supplied in Section 8.  A flow diagram illustrating RFI
decision points is provided in Section 3 (See  Figure 3-2).
                                                                          t
     Notwithstanding the above process, the owner or operator has a continuing
responsibility to identify and respond to emergency situations and to define priority
situations that may warrant interim corrective measures. For these situations, the
owner  or operator is directed to obtain and follow the RCRA Contingency Plan
under 40 CFR Part 264, Subpart D.

     Case Study numbers  10,  18,  19, 20,  21 and 22  in Volume IV (Case Study
Examples) illustrate the conduct of various aspects of ground-water investigations.

10.2.2     Inter-media Transport

     Indirect releases (inter-media transfer) to ground water may occur as a result
of contaminant releases to soil and/or surface water that percolate or discharge to
ground water.  These releases may be recurrent or intermittent in nature,  as in the
case of overland run-off, and can vary considerably in area! extent. Direct releases
to ground water may occur when waste materials are in direct contact with ground
water (e.g., when a landfill rests below the water table).

     Releases of contaminated ground water to other media may also occur, for
example, in those cases where ground  and surface  waters  are hydraulically
                                   1C-8

-------
connected.  Volatilization  of  contaminated  ground  water to the air within
residential and other structures may occur via the basement seepage pathway, as
described previously. It is important for the owner or operator to be aware of the
potential for such occurrences, and to communicate these to the regulatory agency
when discovered.

     This section provides guidance on characterizing ground-water releases from
units, as well as those cases where inter-media transport has contaminated ground
water. The owner or operator should be aware that releases to several media can
often be investigated using concurrent techniques.  For example, soil gas surveys
may help to characterize the extent of soil and subsurface gas releases and, at the
same time, be used to  estimate the extent of a ground-water release.  Further
guidance on the  use of soil gas surveys for investigating releases to soil and ground
water are presented in the Soil Section (Section 9).

10.3 Characterization of the Contaminant Source and the Environmental Setting   (

10.3.1    Waste Characterization

     Knowledge of the waste constituents  (historical and current)  and  their
characteristics at the  units of concern is essential  in  selecting monitoring
constituents and well  locations.   Waste (source) information should include
identifying volumes and concentrations of hazardous waste or constituents present,
and their physical and chemical characteristics.

     Identification of hazardous constituents may be a relatively simple  matter of
reviewing records of unit operations, but generally will require direct sampling and
analysis of the waste in the unit. Hazardous constituents may be grouped by similar
chemical and physical properties to aid in developing a more focused monitoring
program. Knowledge of physical and chemical properties of hazardous constituents
can help to determine their mobility, and their ability to degrade or persist in the
environment.  The mobility  of chemicals in ground water is commonly related to
their solubility, volatility, sorption, partitioning, and density.

     Section 3 provides additional  guidance on monitoring constituent selection
and Section 7 provides additional guidance on waste  characterization. The
                                   10-9

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following discussion describes several waste-related factors and properties which
can aid in developing ground-water monitoring procedures:

     •   The mobility of a waste is highly influenced by its physical form.  Solid
         and gaseous wastes are less likely to come in contact with ground water
         than liquid wastes, except in situations where the ground-water surface
         directly intersects the waste, or where infiltrating liquids are leaching
         through the unsaturated zone.

     •   The concentration of any constituent at the waste source may provide an
         indication of the concentration at which it may appear in the ground
         water.

     •   The chemical class (i.e., organic, inorganic, acid, base, etc.) provides an
         indication of how the waste might be detected in the ground water, and
         how the various components might react with the subsurface geologic(
         materials, the ground water, and each other.

     •   The pH of a waste can provide an indication of the pH at which it would
         be expected to appear in the ground water. A low pH waste could also
         be expected to cause dissolution of some subsurface geologic materials
         (e.g., limestone), causing channelization and differential ground-water
         flow, as in karst areas.

     •   The acid dissociation constant of a chemical  (pKa) is a value which
         indicates its equilibrium potential  in water, and is equal to the pH  at
         which the hydrogen ion is in  equilibrium with its associated base.  If
         direct pH measurements are not feasible, the concentration of a waste in
         combination with its pKa can be used to estimate the likely pH which will
         occur at equilibrium (in ground water), at a  given temperature. Acid
         dissociation values can be found in most standard chemistry handbooks,
         and values for varying temperatures can be calculated  using the Van't
         Hoff equation (Snoeyink and Jenkins, 1980).

     •   Viscosity  is a  measure of a liquid's resistance  to flow at a given
         temperature. The more viscous a fluid is, the more resistant it is to flow.
                                   10-10

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     Highly viscous wastes may travel more slowly than the ground water,
     while low-viscosity wastes may travel more quickly than the ground
     water.

•    Water solubility describes the mass of a compound that dissolves in or is
     miscible with water at a given temperature and  pressure.  Water
     solubility is  important in  assessing the fate and  transport of the
     contaminants in ground water because it indicates the chemical's affinity
     for the aqueous medium. High water solubility permits greater amounts
     of the hazardous constituent to enter the aqueous phase, whereas low
     water solubility indicates that a contaminant can be present in ground
     water as a separate  phase. Therefore, this  parameter can be used to
     establish the potential for a constituent to enter and remain in the
     ground water.

•    The density of a substance (solid or liquid) is its weight per unit volume. (
     The density of a waste will determine whether it sinks or floats when it
     encounters ground water, and will assist in  locating  well screen depths
     when attempting to monitor for specific hazardous constituents released
     to-ground water.

•    The log of the octanol/water partition coefficient (Kow) is a measure of
     the relative affinity of a constituent for the neutral organic and inorganic
     phases represented by n-octanol and water,  respectively.  It is calculated
     from a ratio (P) of the equilibrium concentrations (C) of the constituent
     in each phase:
         P *. Coctano1    and Kow * log P
              Cwater

     The KOW has been correlated to a number of factors for determining
     contaminant fate and transport.  These include adsorption onto soil
     organic matter, bioaccumulation, and biological uptake.  It also bears a
     relationship to aqueous solubility.
                              10-11

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     •    The Henry's Law Constant of a constituent is the relative equilibrium
          ratio of a compound in air and water at a constant temperature.  It can
          be estimated from the  equilibrium vapor pressure divided by  the
          solubility in water and has the units of atm-m3/mole.  The Henry's Law
          Constant expresses the  equilibrium distribution  of  the constituent
          between air and water and indicates the relative ease with  which the
          constituent may be removed from aqueous solution.

     •    Other influences of the waste constituents should also be considered.
          Constituents may react with soils, thereby altering the physical properties
          of the soil, most notably hydraulic conductivity.  Chemical interactions
          among waste constituents should also be considered.  Such interactions
          may affect mobility, reactivity, solubility, or toxicity of the constituents.
          The potential for wastes or reaction  products  to interact with unit
          construction materials (e.g., synthetic liners) should also be considered.
                                                                           i
     The references listed  in Section 7 may be used to obtain information on the
parameters discussed above.  Other waste information may be  found in facility
records, permits, or permit applications.  It should be noted that mixtures of
chemicals may exhibit characteristics different than those of any single chemical.

10.3.2     Unit Characterization

     Unsound unit design and operating practices can allow waste to migrate from
                                                  *
a unit and possibly mix with natural runoff. Examples include surface impound-
ments with insufficient freeboard allowing for periodic overtopping; leaking tanks
or containers; or land based units above shallow, low permeability materials which,
if not properly designed and operated, can fill up with water and spill over.  In
addition, precipitation falling on exposed wastes can dissolve and thereby mobilize
hazardous constituents. For example, at uncapped active or inactive waste piles and
landfills, precipitation and  leachate  are likely to mix at the toe of the active face or
the low point of the trench floor.

     Unit dimensions (e.g., depth  and surface area) and configuration (e.g.,
rectangular, parallel trenches), as well  as volume (e.g., capacity) should also be
                                   10-12

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described, because these factors will have a bearing on predicting the extent of the
release and the development of a suitable monitoring network.

10.3.3     Characterization of the Environmental Setting

     Hydrogeologic conditions at the site to be monitored should be evaluated for
the potential impacts the setting may have on the  development of a monitoring
program and the quality of the resulting data. Several hydrogeologic parameters
should be evaluated, including:

     •    Types and distribution of geologic materials;

     •    Occurrence and movement of ground water through these materials;

     •    Location of the facility with respect to the regional ground-water flow
          system;

     •    Relative permeability of the materials; and

     •    Potential interactions between contaminants and the geochemicai
          parameters within the formation(s) of interest.

These conditions are interrelated and are therefore discussed collectively below.

     There are three basic types of geologic materials through which ground water
normally flows. These are:  (1) porous media;  (2) fractured media; and (3) fractured
porous media. In porous media (e.g., sand  and gravels, silt, loess, clay, till, and
sandstone),  ground water and contaminants  move through  the pore spaces
between individual grains.  In fractured media (e.g., dolomites, some shales,
granites, and crystalline rocks), ground  water and contaminants move
predominantly through cracks or  solution crevices  in  otherwise  relatively
impermeable rock.  In  fractured porous media (e.g.,  fractured tills,  fractured
sandstone, and some fractured shales), ground water and contaminants can move
through both the intergranular pore spaces as well as cracks or crevices in the rock
or soil. The occurrence and movement of ground water through pores and cracks or
solution  crevices depends on the relative effective porosity and degree of
                                  10-13

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channeling occurring in cracks or crevices. Figure 10-1 illustrates the occurrence and
movement of ground  water and contaminants in the three types  of geologic
materials presented above.

     The distribution of these three basic types of geologic materials is seldom
homogeneous or uniform. In most settings, two or more types of materials will be
present.   Even  for one  type of  material at a given site,  large differences in
hydrologic characteristics may be encountered.  The  heterogeneity of the materials
can play  a significant  role in the rate of contaminant transport, as well  as in
developing appropriate monitoring procedures for a site.

     Once the  geologic setting  is  understood,  the site hydrology should be
evaluated. The  location of the site within the regional ground-water  flow system,
or regional  flow net, should  be determined to  evaluate the  potential for
contaminant migration on the regional scale. Potentiometric surface data (water
level information) for  each  applicable geologic formation  at properly selected t
vertical and horizontal  locations is needed to determine the horizontal and vertical
ground-water flow paths (gradients) at the site.  Figure 10-2(a) and (b) illustrate two
geohydrologic  settings commonly encountered  in eastern  regions of the
United States, where ground water recharge exceeds  evapotranspirational  rates.
Figure 10-2(c) illustrates a common  geohydrologic setting for the arid western
regions of the United States. The potential dimensions of a contaminant release
would depend  on a number of  factors  including ground-water recharge and
discharge patterns, net precipitation, topography,  surface water body locations,
and the regional geologic setting.

     Table 10-3 and Figures 10-3  through 10-16 illustrate regional, intermediate,
and local ground water regimes for the major ground-water regions in the United
States.  Ground-water  flow paths, and where possible, generalized flow  nets are
shown  superimposed  on cross-sections of the geological  units.  Much of the
information  presented in the figures and following text descriptions were taken
from Heath et. al., 1 984 (Ground Water Regions of the U.S.. U.S.G.S. Water Supply
                                   10-14

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              LOCAL. AND REGIONAL GROUND WATER
             FLOW SYSTEMS IN HUMIO ENVIRONMENTS
                (b) TEMPORARY REVERSAL Of GROUND-WATER FLOW OUf TO
                             FLOODING OF A RIVER OR STREAM
                    TYPICAL GROUND-WATER FLOW PATHS IN AfllO ENVIRONMENTS
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Figure 10-2.  Ground-water flow paths in some different hydrogeologic settings.
                                     10-16

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                                    10-17

-------
WESTERN MOUNTAIN RANGES
(Mountains with thin soils over fractured rocks,
alternating with narrow alluvial and, in part,
glaciated valleys)
      Potentiometric Surface
      of Lower Aquifer
     Confined
     Bed
Sand

Coane-Grained
Sandstone
Clay Bed

SiltyClay
                                                                                           •;.\'.| Crystalline RocVs

                                                                                           ^^ Joints

                                                                                           ••^ Row Lino

                                                                                           ••—— Equipotential Line
                                 Figure 10-3.  Western Mountain Ranges
                                                      10-18

-------
 Recharge Area
(Mountain Range)
                                                                             Recharge Area
                           Granite

                          Weathered Bedrock
                 '.;•.:•*;•*••;]  Alluvial Deposits
            Figure 10-3.  Western Mountain Ranges (continued)
                                     10-19

-------
ALLUVIAL BASINS
(Thick alluvial deposits in basins and valleys
bordered by mountains)

                                                                                                  Partly drained
                                                                                                  tributary area
             Valley Fin
             Alluvial Deposit
Boundary condition
                                                                                            Metamorphic Bedrock
                                                                                                           Alluvial
                                                                                                           Deposit
                                                                                            Limestone
                                                                           A'
                                   Figure 10-4.  Alluvial Basins
                                                   10-20

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     COLUMBIA LAVA PLATEAU
     (Thick sequence of lavtf flows irregularly interfaedded
     with thin unconsolidated deposits and overlain by thm soils)
        UnoonsoWated
        Sediments
        Basalt

        LaccoJith-Baw*Dfce
"fr-'-nl  and Sediments

:-:'':'-'.-x|  Batement Rocks
                                Figure 10-5.  Columbia Lava Plateau
                                                   10-21

-------
              Schematic Diagram of
              Ground Water Row Regime Through a Saturated Cross Section

              Note: Acaume hydraulic heads increase with depth.
Interbed,
Row Top, •
Row Bottom
Dense Flow
Centerwith -
Vertical Joints

             -High horizontal flow along flow tops

             -Low vertical leakage ttuough basalt interiors
        Figure 10-5.  Columbia Lava Plateau (continued)
                                  10-22

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COLORADO PLATEAU AND
WYOMING BASIN
(Thin soils over consolidated sedimentary
rocks)
                                                            Ridges
                                                                        Dome
         Fault
                            Figure 10-6.  Colorado Plateau

                                         10-23

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HIGH PLAINS
(Thick Alluvial deposits over fractured
sedimentary rocks)
                                                                      1. PaleovaHey Alluvial Aquifers

                                                                      2. High Plains Aquifer System

                                                                      3. Niobrara Sandstone Aquifer

                                                                      4. Pierre Shale Aquitard

                                                                      5. Dakota Sandstone Aquifer

                                                                      6. Undfferentiated Aquifers
                                                                         in Cretaceous Rocks
                                                                      7. Undfferentiated Aquifers
                                                                        in Paleozoic Rocks
                      Generalized local ground water regime for site within the
                      High Plains Region.
                                             Figure 10-7.   High Plains
                                                         10-24

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Ground water flow in
sandstone and clay lenses
B
         Row Line


- — — — Equipotential Line


         Gravel
                                                                    X&  Clay
                                                                        • J  Sandstone
                                 Generalized Regional Flow
                   Withdrawal Wen
                           \
                                     Western Texas
                                     (Recharge cantered at playas)
                           Figure 10-7.  High Plains (continued)
                                             10-25

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NONGLACIATED CENTRAL REGION
(Thm regofitfi over fractured sedimentary rocks)

                                                                                       Solution Cavities
                                                                                       limestone
                                                                                       Shale
                                                                                       Sand,tone
                                                                                Solution Enlarged
                                                                                Faults  and Fractures and
                                                                                Bedding Plane Disolufion
                            Figure 10-8.  Non-glaciated Central
                                             10-26

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GLACIATED CENTRAL REGION
(Glaoal deposits over fractured sedimentary rocks)
                                            Af
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Sand



Till

Outwasned Deposi
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                                  Figure 10-9.  Glaciated Central
                                                 10-28

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PIEDMONT BLUE RIDGE REGION
(Thick regolith over fractured crystalline and
metamorphosed aednwntary rocks)
             Bedrock outcrops
                                                                                             Fractures


                                                                                             Saprolite


                                                                                             Crystalline Bedrock
 Note:  In areas of fractured bedrock, flow through fractures is often greater than flow through the bedrock matrix. Flow through these frac-
 tures may not conform to Darcy's Law. The above flow lines represent generalized flow paths rather than quantitative flow lines used in
 a flow net
                            Figure 10-10.  Piedmont and Blue Ridge
                                                  10-31

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NORTHEAST AND SUPERIOR UPLANDS
(Glacial Deposits Over Fractured
Crystalline rocks)
                                                                    Fractures


                                                                    Glaoo-Fluvial Sand and Gravel


                                                                    Fluvial Valley Train Deposits


                                                                    Delta Deposits


                                                                    Karne Terrace Deposits
                                                              VV&I TIB Deposits
                                                           b^r£r^l Glacio-lacustrine Fine-grained sediments
                                                                    Bedrock
                                                                    Row Line


                                                              — —  EquipotentiaJ Line

                                                              A'
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                                                                            axs of valley, although
                                                                            not shown in this
                                                                            cross-section can often
                                                                            be important.
                  Figure 10-11.  Northeast and Superior Uplands

                                          10-32

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                              Discharge Area
B
                                                                               Water Table
             Generalized local ground water regime witWn the Northeast and
             Superior Upland* Region showing a confining layer of till.
    Figure 10-11. Northeast and Superior Uplands (continued)
                                  10-33

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ATLANTIC AND GULF COASTAL PLAIN
(Complexly mfertedded sand, sift, and day)
                                                                                Clay

                                                                               Sand

                                                                               LJmmtone
                      Figure 10-12.  Atlantic and Gulf c   astal Plain
                                           10-34

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                                           Losing Stream
    :£'*:'•*•! :1 Alluvial Deposits
                                                                    200
                                                                 — Sea Level
                                                                 L- -200
      r-iSg Sandy Shale
   Note: Regional flow based on high recharge in hills which-are
      not shown in this diagram.
Figure 10-12. Atlantic and Gulf Coastal Plain (continued)
                             10-35

-------
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SOUTHEAST COASTAL PLAIN
(Thick layers of sand and day over semiconsoiidated
carbonate rocks)
     r-LIV-S
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Solution Limastone

Crost-Mcaon with highly generalized flow path Knee and equipo»nt>al
lines. Actual condition in Karst terrain may not be definable due to
fractures and solution channel flow.
                                       Recharge Area
              Discharge Area
                                                      Pteistocene/Holocene Sand

                                              Lake    V           /      Limestone Spring
                                                                               n Condition)


                                                                               ;• - *  _^^K^fc 'm
     Formatton
                         Figure 10-13.  Southeast Coastal Plain
                                             10-37

-------
Swamp
teaches and Ban

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     Figure 10-13.  Southeast Coastal Plain (continued)
                           10-38

-------
HAWAIIAN ISLANDS
(Lava flows segmented in part by dikes,
interbedded with ash deposits, and partly
overlain by alluvium)
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ALASKA

(Glacial and Alluvial Deposits. Occupied in
Part by Permafrost, and CVertymg Crystalline,
Metamofphic, and Sedimentary Rocks)
                                      Figure 10-15.  Alaska
                                                10-41

-------
                                                                               EXPLANATION


                                                                              Continuous p»mnfro«


                                                                              Discontinuous psrmsfrost
                                                                         Losing
                                                                         Slrawn
Alluvium
                                                                • v•.•».*•.•• .*.• .•-••/••• • • •• • •'. •
                                                                 .'a* A' •  • •• • ' 9 • • - '•••».••
                                                        -vvv.:y;^;
                                     Figure 10-15.  Alaska (Continued)


                                                     10-42
                                                                                                       Parma
                                                                                                       Fluvial
                                                                                                       Dcpos
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                                                                                                       Alluvii
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ALLUVIAL VALLEYS
(Thick sand and gravel dtpotifc temtih teodptain* and tartans
ofstwms)
                                                           MISSISSIPPI RIVER
                                 Figure 10-16.  Alluvial Valleys
                                              10-43

-------
180
                             Buried drum site
                      Existing Ground Surface
                                                Pre-Excavanon Ground Surface
                       -"^  Primary Barrel Pit "* *»
                          7

            1400    2+00     3+00    4+00    5+00    6+00     7+00    8+00     9+00    10*00
                                       Horizontal Dbtanc
                Legend

                GJadalTiil

                Outwash and Drift
                Bedrock

                Stratified Drift
                     Figure 10-16.  Alluvial Valleys (continued)
                                           10-44

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Paper No. 2242).  Following are descriptions of each of the major ground-water
regions illustrated in the Figures (Figures 10-3 through 10-16).

     Ground-water flow in the Western  Mountain Ranges region is influenced by
melting snow and rainfall at higher altitudes. The thin soils and fractures present in
the underlying bedrock have a limited storage capacity and are filled quickly with
recharging ground water flowing  from  higher elevations (see Figure 10-3). The
remaining surface water runs overland  to streams that eventually may recharge
other areas.  Streams that recharge ground  water are referred to as "losing
streams."  Figure 10-3 also shows local ground-water flow paths influenced by low
permeability bedrock located in intermountain valleys throughout the mountain
ranges.

     The Alluvial Basins region consists of deep, unconsolidated sediments adjacent
to mountain ranges.  Precipitation  often  runs rapidly off the mountains and
infiltrates into  the alluvium at the valley margins.  The water  moves through the
sand and gravel layers toward the centers of the basins (Figure 10-4). The presence*
of disjointed masses of bedrock in this  region is  crucial to the hydrogeological
regime. Low permeability igneous bedrock often isolates the ground-water regime
into individual  basins with minimal  exchange of ground water.  Where the bedrock
is composed of limestone or other highly permeable formations, large regional flow
systems can develop, encompassing many basins. Recharge areas in this region are
located in upland areas; lowland  stream beds only carry water when sufficient
runoff from the adjoining mountains occurs.

     Basaltic bedrock is the major source of ground water within the Columbia Lava
Plateau region. Volcanic bedrock yields water mainly from zones at the contacts of
separate basalt flows. The permeability and hydraulic conductivity are much higher
in these zones at the edges of the flows than in the center of the flows (see Figure
10-5.) This is caused partially by the rapid cooling and consequent fracturing of the
top of each basalt flow.

     The Colorado Plateau and Wyoming Basin region is a large plateau consisting
principally of sandstones, shales, and limestones.  These sedimentary rocks are
generally horizontal but have been modified by basins  and domes in some areas
(see Figure 10-6).  Sandstones have significant primary porosity and are the major
                                   10-45

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water-bearing  units in this region.  Recharge occurs where the sandstones are
exposed.  Intermittent losing streams created by sudden summer storms provide
some recharge, but most recharge is caused by snowmelt.

     Generally, ground water is unconfined in the recharge areas and confined in
trie lower reaches of the aquifers.  The storage coefficients and transmissivities in
the confined portions of the aquifers are small, causing extensive drawdown during
even minor pumping.  Saline ground  water is characteristic of this region and is
caused by the existence of gypsum and  halide in the sedimentary deposits.

    The High  Plains region is underlain by thick alluvial deposits that comprise a
productive and extensively developed aquifer system. The source of recharge to the
aquifer system is precipitation, except in Western Texas where recharge is centered
at playas (see Figure 10-7). In many areas, well discharges far exceed recharge, and
vtfater levels are declining. The dominant features influencing ground-water flow in
this region include the  Ogalalla Aquifer, the Pierre  Shale, and the  complex(
interbedding of sand and clay lenses.  Figure 10-7 provides generalized flow nets,
showing flow patterns through these features.

    Thin regolith over fractured sedimentary rocks typifies the nature of the
geology in the Nonqlaciated Central region (see Figure 10-8). This region extends
from the Rocky Mountains to the Appalachian Mountains.  Water is transmitted
primarily along fractures developed at bedding planes.  Interconnected vertical
fractures also can store a large portion of the ground water. An example of ground-
water flow on a local scale is shown for karst terrain, where ground water moves
rapidly through solution cavities and  fractures in limestone and where  the flow
pathways are closely associated with the configuration of fractures. Ground-water
flow in the karst regime  does  not usually follow Darcy's law because most of the
flow goes through large channels rather than the pores  in the rock.  Thus,
construction of a flow net may not be appropriate in some cases. An additional
example of localized flow in this  region  is  provided, showing a  surface
impoundment site in Pennsylvania. Notice that ground water discharges to surface
water, a phenomenon typical of this region.
                               ^

    The topography of the Glaciated Central region is characterized by rolling hills
and mountains in the eastern  portion of the  region and by flat to gently rolling
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terrain in the western portion of the region.  Glacial deposits vary in thickness
within the region and are underlain by bedrock. Ground water occurs in the glacial
deposits in pores between the grains and in the bedrock primarily along fractures.
Permeability of glacial deposits ranges from extremely transmissive in gravels to low
transmissivity in poorly sorted tills.  The presence of buried valleys, till, deltas,
kames, and other glacial artifacts highly influences the transmission of ground
water within the region.  Two examples of localized flow are presented in Figure 10-
9. The first  example shows a flow regime in an  area where till has the  highest
hydraulic conductivity relative to the other formations.  In the second example, the
till bed has a much lower hydraulic conductivity than the deltaic outwash deposited
above it.

     Thick regolith overlies fractured crystalline and metamorphic bedrock in most
of the Piedmont and Blue Ridge region. The hydraulic conductivities of regolith and
fractured bedrock are similar.  However,  bedrock wells generally have much larger
ground-water yields than regolith wells  because, being deeper, they have a much
larger available drawdown.  Fracture-controlled movement of  ground wateri
through bedrock is illustrated by generalized flow paths rather than quantitative
flow lines used in a flow net in Figure 10-10, as is ground-water movement through
saprolite (weathered bedrock) and river alluvium.

     The Northeast and Superior Uplands region is characterized by folded and
faulted igneous and metamorphic bedrock overlain by glacial deposits. The primary
difference in the ground-water environment between this region and the Piedmont
and Blue Ridge region is the presence of glacial material rather than regolith.  The
different types of glacial material have vastly different  storage  capacities and
hydraulic conductivities.  Examples of ground-water flow through till,  delta, and
kame deposits, as well  as a generalized ground-water regime  with upward
gradients, are illustrated in Figure 10-11.

     The Atlantic and Gulf Coastal Plain region is underlain by unconsolidated
sediments that consist primarily of sand, silt, and clay.  The sediments are often
interbedded as a result of deposition on floodplains or deltas and of subsequent
reworking by ocean currents.  Recharge  to the ground-water system occurs in the
interstream areas; most streams  in this region are gaining streams (see Figure 10-
12). Encroachment of saltwater into well drawdown areas can be a problem in this
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area if high rates of ground-water withdrawal occur. An example of a regional flow
net based on high recharge in hills shows how regional flow may differ from
localized flow based on local topography.  Also shown in Figure 10-12 is a landfill
located in a recharge area nearthe Savannah River in Georgia.

     Ground water in the Southeast Coastal Plain  region lies primarily within
semiconsolidated limestone. Sand, gravel, clay, and shell beds overlie the limestone
beds.  Recharge in this  region occurs by  precipitation infiltrating directly into
exposed  limestone and by seepage through the permeable soils that partially
mantle the limestone (see Figure 10-13). Coastal environments, such as beaches and
bars, and swamp areas have different ground-water regimes, which are  shown in
Figure 10-13.  Flow through solution channels and large fractures in limestone is
often rapid, similar to the situation shown in Figure 10-8.

     The Hawaiian Islands region consists of many distinct and separate lava flows
that repeatedly issued from several eruption centers forming mountainous islands.
Lava extruded  below sea level is relatively  impermeable; lava extruded above sea
level is much more permeable, having interconnected cavities, faults, and joints.
Ground-water flow in this region is similar to that of the Columbia Plateau region,
with the central parts of thick lava  flows being less permeable and the major
portion  of ground-water flow in these thick beds  occurring at the edges and
contacts of the different lava flows.  Alluvium overlies the lava in the valleys and
portions of the coastal plains.

     Ground water in this region can be characterized by'one of three ground-
water flow regimes. The first flow regime consists of ground water impounded in
vertical compartments by dikes in the higher elevations near the eruption centers.
The second flow regime consists of fresh water floating on salt water in the lava
deposits that flank the eruption centers. This ground water is referred to as basal
ground water and makes up the major aquifers in the region.  In some areas of the
coastal plain, basal ground water is confined by overlying alluvium, which may
restrain seaward migration of fresh water.  The third flow regime is where ground
water is perched on soils, ash, or thick  impermeable lava flows above  the basal
ground  water.  Figure  10-14  illustrates examples of ground-water flow in this
region.
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     The Alaska region comprises several distinct flow regimes that can be
categorized by ground-water regions in the lower 48 States. For example, Alaska's
Pacific Mountain System is similar to the Western Mountain Range and Alluvial
Basin regions described previously.  The  major variable causing Alaska to be
classified as a separate region is its climate and the existence of permafrost  over
most of the region.

     Permafrost has a major effect on the hydraulic conductivity of most geologic
deposits. Hydraulic conductivity declines as temperatures drop below 0 °C.  This
effect can be severe, causing a deposit that would be an aquifer in another area to
become a low-permeability aquitard in an area of permafrost.  In Alaska, ground-
water supplies are drawn from deposits that underlie the permafrost or from areas
where the permafrost is not continuous. See Figure 10-15.

     Most recharge in this region occurs in large alluvial deposits, such as alluvial
fans, which streams cross and discharge to.  Although the volume of interstream
surface water is large during periods of snow melt, these interstream areas do not
act as recharge areas because they are usually frozen during the snow melts.

     The Alluvial Valley region consists of valleys underlain by sand and gravel
deposited by streams  carrying sediment-laden melt water from glaciation  that
occurred during the Pleistocene. These valleys  are considered to be a distinct
ground-water terrain.  They occur throughout the United States and  can supply
water to wells at moderate to high rates (see Figure 10-16). These valleys have thick
sand and gravel deposits that are in a clearly defined band and are in  hydraulic
contact with a perennial stream.  The sand and  gravel deposits generally have a
transmissivity of 10 or more times greater than that of the adjacent bedrock.  Silt
and clay commonly are found both above and below the sand and gravel channels
in the Alluvial Valley region as a result of overbank flooding of rivers.  Ground-
water recharge in this region is predominantly by precipitation  on the valleys, by
ground  water moving from the adjacent and underlying aquifers, by overbank
flooding of the streams, and, in some glacial valleys, by  infiltration  from tributary
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streams.  An example of a flow net illustrating local ground-water movement
beneath a waste disposal site in Connecticut also is shown in Figure 10-16.

     In addition to determining the directions of ground-water flow, it is essential
to determine the approximate rates of ground-water movement to properly design
a monitoring program.  Hydraulic conductivity, hydraulic gradient, and effective
porosity data are required to estimate the average linear velocity of ground water
and, therefore, assist in the determination of the rate of contaminant migration.
Hydraulic conductivity data can  be determined using single well (slug) test data.
Several hydraulic conductivity measurements can be made on materials penetrated
by individual wells to provide data on the relative heterogeneity of the materials in
question. Measurements made in several wells also provide a comparison to check
for effects of poor well construction.  Hydraulic conductivity can also be determined
from multiple-well (pumping) tests.  A  multiple-well test provides a hydraulic
conductivity value  for a larger portion of the aquifer.   Hydraulic conductivities
determined in the laboratory have been shown to vary by orders of magnitude from
values determined by field methods and are, therefore, not recommended for use in
the RFI.

     Porosity can  have an important controlling influence on hydraulic con-
ductivity.  Materials with high porosity values generally also have high hydraulic
conductivities.  An exception is clayey geologic materials which, although possessing
high porosities, have low hydraulic conductivity values (resulting in low flow rates)
due to their molecular structure.  All of the pore spaces within geologic materials
are not available for water or solute  flow. Dead-end  pores and the portion of the
total porosity occupied by water held to soil particles by surface tension forces, do
not contribute to  effective porosity. Therefore, to determine  average linear
velocities, the  effective porosity of the materials should be determined.  In  the
absence of measured values, the values provided in Table 10-4 should be used.

     Knowledge of the rates of ground-water flow is essential to determine if the
locations of the monitoring wells are within reasonable flow distances of  the
contaminant sources.  Flow rate data  can also be used  to  calculate reasonable
sampling frequencies. This is particularly important when attempting to  monitor
the potential migration of a intermittent contaminant release.
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           TABLE 10-4.  DEFAULT VALUES FOR EFFECTIVE POROSITY
                 Soil Textural Classes
                                                          Effective
                                                          Porosity of
                                                         Saturation*
 Unified Soil Classification System
    GC, GP, GM, GS
    SW,SP,SM,SC

    ML,MH
    CL, OL, CH, OH, PT
l)SDA Soil Textural Classes
   Clays, silty clays,
   sandy clays
    Silts, silt loams,
    Silty clay loams

    All others
 Rock Units (all)
    Porous media (nonfractured
    rocks such as sandstone and some carbonates)
    Fractured rocks (most carbonates, shales,
    granites, etc.)
                                                            0.20
                                                           (20%)

                                                            0.15
                                                           (15%)

                                                            0.01
                                                             0.01
                                                            0.10
                                                           (10%)

                                                            0.20
                                                           (20%)
                                                            0.15
                                                           (15%)

                                                           0.0001
                                                          (0.01%)
a  These values are estimates. There may be differences between similar units.
b  Assumes de minimus secondary porosity. If fractures or soil structure are
   present, effective porosity should be 0.001 (0.1%).
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     Geochemical and  biological properties of the aquifer matrix should  be
evaluated in terms of their potential  interference with the goals of the monitoring
program.  For example, chemical reactions or biological transformations of the
monitoring constituents of concern may introduce artifacts into the results. Physical
and hydrologic conditions will determine whether or not information on chemical
or biological interactions can be collected.  If the potential for these reactions or
transformations exists, consideration should be  given to monitoring for likely
intermediate transformation or degradation products.

     The monitoring system design is influenced in many ways by a site's
hydrogeologic setting. Determination of the items noted in the stratigraphy and
flow systems discussions will aid in logical monitoring network configurations and
sampling activities. For example:

     •   Background and downgradient  wells should  be screened in the same
         stratigraphic horizon(s) to obtain comparable ground-water  quality
         data.  Hydraulic conductivities should be determined to  evaluate1
         preferential flowpaths (which will require monitoring) and to establish
         sampling frequencies.

     •   The distances between and number of wells (well density) should be a
         function of the spatial heterogeneity  of a site's hydrogeology, as is
         sampling  frequency.  For example, formations of unconsolidated
         deposits with numerous interbedded lenses of varying hydraulic
         conductivity or  consolidated rock with numerous fracture traces will
         generally require a greater number of sampling locations to ensure that
         contaminant pathways are intercepted.

     •   The slope  of the potentiometric surface and the slope of the aquitard
         formation strongly influence the migration rates of light and dense
         immiscible compounds.

     •   The hydrogeology will strongly influence the applicability of  various
         geophysical methods (Appendix C), and should be used to establish
         boundary  conditions for any modeling to be performed for the site.
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Analyses for contaminants of concern in the ground-water monitoring
program can be influenced by the general water quality  present.
Naturally-occurring cations and anions can affect contaminant reactivity,
solubility, and mobility.

Sites with  complex geology will generally require more hydrogeologic
information to provide a reasonable assurance that well placements will
intercept contaminant migration pathways.  For example,  Figure 10-17
illustrates a cross-sectional and plan view of a waste landfill located in a
mature  Karst environment.  This setting is characteristic of carbonate
environments encountered in various parts of the country, but especially
in the southeastern states.  An assessment of the geology of the site
through the use of borings, geophysical surveys, aerial photography,
tracer studies, and other geological investigatory techniques, identified a
mature  Karst geologic formation characterized by sinkholes, solution
channels  and extensive vertical  and  horizontal  fracturing  in  an
interbedded limestone/dolomite.   Using potentiometric data, ground-1
water flow was found to be predominantly in an easterly direction.

Solution channels are formed by the flow of water through the fractures.
The chemical reaction between the  carbonate  rock and the ground-
water flow in the fractures produces solution channels.  Through time,
these solution channels are enlarged to  the point where the weight of
the overlaying rock is too great to support; consequently causing a
"roof" collapse and the formation  of a sinkhole. The location of these
solution channels should guide the placement  of  monitoring   wells.
Note  that in Figure 10-17 the placement of well No. 2 is offset  50 feet
from the perimeter of the landfill. The horizontal placement of well No.
2, although not immediately adjacent to the landfill, is necessary in order
to monitor all potential contaminant pathways.  The discrete nature of
these solution  channels dictate  that each potential pathway  be
monitored.

The height of the solution channels ranges from three to six feet directly
beneath the sinkhole  to one foot under the landfill except for the 40-
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foot deep cavern. This limited vertical extent of the cavities allows for full screening
of the horizontal solution channels. (Note the change in orientation of solution
channels due to the presence of the fossil hash layer).

     Chapter I  of the RCRA Ground Water Monitoring Technical Enforcement
Guidance Document (TEGD) (U.S. EPA, 1986) provides additional guidance in
characterization of site hydrogeology.  Various sections of the document will be
useful to the facility owner or operator in  developing  monitoring plans for RCRA
Facility Investigations.

     In order to further characterize a release to ground water, data should be
collected to assess subsurface stratigraphy and ground-water flow systems.  These
are discussed in the following subsections.

16.3.3.1  Subsurface Geology

     In order to adequately characterize the hydrologic setting of a. site, an analysis
of site geology should first be completed. Geologic site characterization consists of
both  a characterization of stratigraphy, which includes unconsolidated  material
analysis,  bedrock features such as lithology and structure, and depositional
information, which indicates the sequence  of events which resulted  in the present
subsurface configuration.

     Information that may be needed to characterize  a site's subsurface geology
includes:

     •   Grain size distribution and gradation;

     •   Hydraulic conductivity;

     •   Porosity;

     •   Discontinuities in soil strata; and

     •   Degree and orientation of subsurface stratification and bedding.
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Refer to Section 9 (Soil) for further details.

     Grain size distribution and oradation-A measurement of the percentage of
sand, silt, and clay should be made for each distinct layer of the soil.  Particle size can
affect contaminant transport through its impact  on adsorption and hydraulic
conductivity. Sandy soils generally have low sorptive capacity while clays tend to
have a high affinity for heavy metals and some organic contaminants. This is due in
part to the fact that small clay particles have a greater surface area in relation to
their volume than do the larger sand particles.  Greater surface areas allow for
increased  interactions with  contaminant molecules.   Clays  may also bind
contaminants due to the chemical structure of the clay.  Methods for determination
of sand/silt/clay fractions are available from ASTM, Standard Method No. 0422-63
(ASTM, 1984).

     Hydraulic conductivity-This property represents the ease with which fluids can
flow through a formation, and is dependent on porosity, and grain size, as well as
on the viscosity of the fluid. Hydraulic conductivity can be determined by the use of*
field tests, as discussed in Section 10.6.

     Porosity-Soil porosity is the volume percentage of the total volume of the soil
not occupied by solid particles (i.e., the volume of the voids). In general, the greater
the porosity, the more readily fluids may flow through the soil, with the exception
of clays (high porosity), in which fluids are held tightly by capillary forces.

     Discontinuities in geological materials-Folds are layers of rock or soil that have
been naturally bent over geologic time.  The size of a fold may vary from several
inches wide to several miles wide.  In any case, folding  usually results in a complex
structural configuration of layers (Billings, 1972).

     Faults are ruptures in rock or soil formations along which the opposite walls of
the formation have moved past each other. Like folds, faults vary in size. The result
of faulting is the disruption of the continuity of structural layers.

     Folds and faults may act as either barriers to or pathways for ground-water
(and contaminant) flow. Consequently, complex hydrogeologic conditions may be
exhibited. The existence of folds or faults can usually be determined by examining
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geologic maps or surveys.  Aerial  photographs can also be used to identify  the
existence of these features.  Where more detailed  information is needed, field
methods (e.g., borings or geophysical methods) may need to be employed.

     Joints are relatively smooth fractures found in bedrock.  Joints may be as long
as several hundred feet (Billings, 1972). Most joints are tight fractures, but because
of weathering, joints may be enlarged to open fissures. Joints result in a secondary
porosity in the bedrock which may be the major  pathway of ground-water flow
through the formation (Sowers, 1981).

     Interconnected conduits between grains  may form  during  rock  formation
(Sowers, 1981). The  permeability of a bedrock mass is often defined by the degree
of jointing.  Ground water may travel preferentially along joints, which usually
governs the rate of flow through the bedrock. The degree and orientation of joints
and interconnected  voids is needed to determine if there will  be any  vertical or
horizontal leakage through the formation.  In some cases, bedrock  acts  as an
aquitard, limiting the ground-water flow in an aquifer. In other cases, the bedrock1
may be much more productive than overlying alluvial aquifers.

     Geologic maps available from the USGS  (see Section  7)  may be useful in
obtaining information on the  degree and orientation of jointing or interconnected
void formation.  Rock corings may also be used to identify these characteristics.

     Degree and orientation  of subsurface stratification and beddinq-The owner
or operator should  develop  maps of the subsurface structure for the areas of
concern.  These maps should  identify the thickness and depth of formations,  soil
types and  textures, the locations of saturated regions and other hydrogeological
features.  For example, the  existence of an  extensive,  continuous,  relatively
horizontal, shallow strata of low permeability can provide a clue to contaminant
routing. In such cases, the contaminants may migrate at shallow depths, which are
above the regional aquifer. Such contamination could discharge into nearby, low-
lying structures (e.g., seepage into residential basements).  This "basement
seepage" pathway has been demonstrated to be a significant migration  channel in
many cases. This pathway may result from migration of vapors in the vadose zone
or through lateral migration of contaminated ground water. Basement seepage is
more likely to occur in locations with shallow ground  water.  A method  for
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estimating basement air contaminant concentrations due to volatile components in
ground-water seeped into basements appears in Appendix E.

     A variety of direct and indirect methods are available to characterize a site
geologically with respect to the above geologic characteristics.  Direct methods
utilize soil borings and rock core samples and  subsequent lab analysis  to evaluate
grain size, texture, uniformity, mineralogy, soil moisture content, bedrock lithology,
porosity, and structure. Combined, these data provide the basis for delineating the
geologic nature of the site and, in turn, provide the data necessary to evaluate the
hydrologic setting.

     Indirect methods of geologic investigation, such as geophysical techniques
(See Appendix C)  and aerial photography  (See Appendix A) can be used to
supplement data gathered by direct field methods, through extrapolation  and
correlation of data on  surface and  subsurface geologic features.   Borehole
geophysical techniques can be used to extrapolate direct data from soil borings and
bedrock cores.  Surface geophysical methods  can provide indirect information on(
depth,  thickness, lateral  extent, and variation of subsurface features that can be
used to extrapolate information gained from direct methods.  Applicable surface
geophysical methods include seismic refraction,  electrical resistivity, electro-
magnetics, magnetics, and ground penetrating radar.

10.3.3.2  Flow Systems

     In addition to characterizing  the subsurface geology, the owner or operator
should  adequately describe the ground-water flow system.  To adequately describe
the ground-water flow paths, the owner or operator should:

     •    Establish the direction of ground-water flow (including horizontal and
         vertical components of flow);

     •    Establish the seasonal, temporal, and artificially induced (e.g., offsite
         production well pumping, agricultural use) variations in ground-water
         flow; and
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     •    Determine the hydraulic conductivities of the hydrogeologic  units
          underlying the site.

     Hydrologic and hydraulic properties and other relevant information needed to
fully evaluate the ground-water flow system are listed and discussed below:

     •    Hydraulic conductivity;

     •    Hydraulic gradient (vertical and horizontal);

     •    Direction and rate of flow;

     •    Aquifer type/identification of aquifer boundaries;

 *   •    Specific yield (effective porosity)/storage coefficient;

     •    Depth to ground water;                                            '

     •    Identify uppermost aquifer;

     •    Identify recharge and discharge areas;

     •    Use of aquifer; and

     •    Aquitard type and location.

     Hydraulic conduct!vitv-ln addition to defining the direction of ground-water
flow in the vertical and horizontal directions, the owner or operator should identify
the distribution of hydraulic conductivity within each formation. Variations in the
hydraulic conductivity of subsurface  materials can affect flow rates and alter
directions of ground-water flow paths.  Areas of high hydraulic  conductivity
represent areas of  greater ground-water flow and zones of potential migration.
Therefore, information on hydraulic conductivities is needed  to make  decisions
regarding well  placements.  Hydraulic conductivity measurement is  described in
Section 10.6.
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     Hydraulic gradient-The hydraulic gradient is defined as the change in static
head per unit distance in a given direction.  The. hydraulic gradient defines the
direction of flow and may be expressed on maps of water level measurements taken
around the site. Ground-water velocity is directly related to  hydraulic gradient.
Both vertical and horizontal gradients should be characterized.

     Direction and rate of flow-A thorough understanding of how ground water
flows beneath the facility will aid the owner or operator in locating wells to provide
suitable background and/or downgradient samples. Of particular importance is the
direction of ground-water flow and the impact that external factors  (intermittent
well pumping, temporal variations in recharge  patterns, tidal effects, etc.) may have
on ground-water flow patterns.  In order to account for these  factors, monitoring
procedures should  include precise water level measurements in piezometers or
observation wells. These measurements should be made in a sufficient number of
wells and at a frequency sufficient to adequately gauge both seasonal  average flow
directions  and to show any seasonal or temporal fluctuations in flow directions.
Horizontal and vertical components of ground-water flow should  be assessed.
Methods for determining vertical and horizontal components of flow are described
in Subsection  10.5.4.
                                      •
     Identification of aquifer boundaries/aquifer type--Aquifer boundaries define
the flow limits and the degree of confinement of an aquifer. There are two major
types of aquifers:  unconfined and confined.  An  unconfined aquifer has a free
water surface at which the fluid pressure is the same as atmospheric. A confined
aquifer is  enclosed by retarding geologic formations and is, therefore, under
pressure greater than atmospheric. A confining unit consists of consolidated or
unconsolidated earth materials that are substantially less permeable than aquifers.
Confining  units are called aquitards or aquicludes.  Aquifer  boundaries can  be
identified  by  consulting geologic maps and state geologic surveys.  Observation
wells and piezometers can be used to determine the degree of confinement of an
aquifer through analysis of water level data.

    Specific vield/storativitv-Soecific yield and storativity are  both terms used to
characterize the amount of water  an aquifer is capable of yielding.  In  an
unconfined system, the specific yield is the ratio of the drainable volume to the bulk
volume of the aquifer medium (some liquid will  be retained in pore spaces). The
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storativity of a confined aquifer is the volume of water released from a column of
unit area and height per unit decline of pressure head. Specific yield or storativity
values may be necessary to perform complex ground-water modeling.

     Depth to ground water--The depth to ground water is the vertical distance
from the land's surface to the top of the saturated zone.  A release from a unit not
in contact with the water table will first percolate through the unsaturated zone
and may, depending  upon  the nature of the  geologic material,  disperse
horizontally. Thus, a  release of this  nature may reach a deep water table with
limited lateral  spreading. Depth to ground water can influence the selection of
sampling methods as well as geophysical methods.

     A shallow water table  can also facilitate releases to other environments via
volatilization of some compounds into the unsaturated zone, seepage into base-
ments of buildings in  contact with  the  saturated zone,  or the transport of
contaminants into wetlands where the water table reaches the level of the ground
surface. Sufficient mapping of the water table with particular attention to these *
features should provide an indication of where these interactions may exist.

     Identification of uppermost aquifer--As defined in 40 CFR §260.10, "aquifer"
means a geologic formation, group of formations, or part of a formation capable of
yielding a significant amount of ground water to wells or springs.  "Uppermost
aquifer," also defined in 40 CFR §260.10, means the geologic formation nearest the
natural ground surface  that is an  aquifer,  as well as  lower aquifers that  are
hydraulically  interconnected  with  thrs aquifer within  the facilitiy's property
boundary. Chapter one of the Technical Enforcement Guidance Document (TEGD)
(U.S. EPA, 1986) elaborates on the uppermost aquifer definition.  It states that the
identification of the confining layer or lower boundary is an essential facet of the
definition. There should be  very limited interconnection, based on  pumping tests,
between the uppermost and lower aquifers.   If zones of saturation  capable of
yielding significant amounts of water are interconnected, they all comprise  the
uppermost aquifer. Identification of formations capable of "significant yield" must
be made on a case-by-case basis.

     There are saturated zones, such as low permeability  clay, that may not yield a
significant amount of water, yet may act as pathways for contamination that can
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migrate horizontally for some distance  before  reaching  a zone which yields a
significant amount of water.  In other cases, there may be low yielding saturated
zones above the aquifer which can provide a pathway for contaminated ground
water to reach basements.  If there is reason to  believe that a potential exists for
contamination to  escape along such pathways, the  owner or operator should
monitor such zones.

     For further information on  the uppermost aquifer definition, including
examples illustrating the determination of hydraulic interconnection in various
geologic settings, see Chapter One of the TEGD.

     Identification of recharge and discharge areas-Ground-water recharge can be
defined as the entry into the saturated zone of water  made available at the water
table surface, together with the associated flow away from the water table within
the saturated zone.  Ground-water discharge can be defined as the removal of
water from the saturated zone across the water table surface, together with the,
associated flow toward the water table within  the saturated zone (Freeze and
Cherry, 1979). Ground-water recharge and discharge areas also represent areas of
potential inter-media transport.

     Recharge can be derived from the infiltration of precipitation, inter-aquifer
leakage, inflow from streams or lakes, or inadvertently by leakage from lagoons,
sewer lines, landfills, etc. Discharge occurs where  ground water flows to springs,
streams, swamps, or lakes, or is removed by evapotranspiration or pumping wells,
etc. Information on the source and location of aquifer recharge and discharge areas
may be obtained  from state water resource publications, geologic surveys, or
existing site information. Comparison of aquifer water levels with nearby surface
water levels may also provide an indication of the source  and location of aquifer
recharge and discharge areas.

     Flow nets  can also be used  to determine areas of aquifer recharge and
discharge. Section  10.5.2 describes the use of flow nets to determine ground-water
flow patterns.

     Use of aquifer-The proximity and extent  of local ground-water use (e.g.,
pumping)  may dramatically influence the rate and  direction of ground-water flow
                                   10-62

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possibly causing seasonal or episodic variations. These factors should be considered
when  designing  and  implementing  a  ground-water monitoring system.
Information on local aquifer use may be available from the USGS, and state and
local water authorities. Aquifer use for drinking water or other purposes may also
influence the location of ground-water monitoring wells, as it may be appropriate
to monitor at locations pertinent to receptors.

     Aquitard type and location-Aouitard  type  refers to the type  of geologic
formation that serves to bound  ground-water flow for a given aquifer.  Such
boundaries may be rock or may be an unconsolidated  unit such as clay, shale, or
glacial till. The identification of such formations and their  hydraulic characteristics
is essential in determining ground-water flow paths.  Aquitard locations can be
determined  by consulting geologic maps and boring log information.  Although
aquitards  are substantially less permeable than aquifers, they are not totally
impermeable and can allow significant quantities of water to pass through them
overtime. The location of an aquitard should be  used in determining monitoring
well depths.

10.3.4     Sources of Existing Information

     A complete review of relevant existing information on the facility is an
essential part of the release characterization. This review can provide valuable
knowledge and a basis for developing monitoring procedures.  Information that
may be available and useful for the investigation includes both site-specific studies
and regional surveys available from local, state, and Federal agencies.

     Information from the regulatory agency such as the RFA report should be
thoroughly reviewed in developing monitoring procedures, and should serve as a
primary information source.  It may also provide references to other sources of
information.  In addition, the facility's RCRA Permit Application may contain other
relevant information. These reports and all of the facility's RCRA compliance/permit
files will provide an understanding of the current level of knowledge about the
facility, and will assist in identifying data gaps to be filled during the investigation.

     Public information is available from local, state, and Federal governments (see
Section 7) concerning the topics discussed below.
                                   10-63

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10.3.4.1   Geology

     Knowledge of local bedrock types and depths is important to the investigation
of a site. Sources of geologic information include United States Geological Survey
(USGS) reports, maps, and files; State geological survey records; and local well
drilling logs. See also Section 9 (Soils).

10.3.4.2   Climate

     Climate is also an important factor affecting the potential for contaminant
migration from a release source.  Mean values for precipitation, evaporation,
evapotranspiration, and estimated percolation will help determine the potential for
onsite and offsite contaminant transport. The investigator should consult monthly
or seasonal precipitation and evaporation (or temperature) records. Climate and
weather information can be obtained from:
                                                                           i
          National Climatic Center
          Department of Commerce
          Federal Building
          Asheville, North Carolina 28801
          Tel:  (704)258-2850

10.3.4.3   Ground-Water Hydrology

     The owner or operator will need to acquire information on the ground-water
hydrology of a site and its surrounding environment. Ground-water use in the area
of the site should be thoroughly investigated to find the depths of local wells, and
their pumping  rates. Sources of such information include the USGS, state geological
surveys, local well drillers, and State and  local water resources boards. A list of all
state and local cooperating offices is available from the USGS, Water Resources
Division in Reston, Virginia, 22092.   This list  has also been distributed to EPA
Regional Offices. Water quality data, including surface waters, is available through
the USGS via their automated NAWDEX system. For further information, telephone
(703)860-6031.
                                   10-64

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10.3.4.4  Aerial Photographs

     Aerial reconnaissance can be an effective and economical tool for gathering
information on waste management facilities.  For this application,  aerial  recon-
naissance includes aerial  photography and thermal infrared scanning.  See
Appendix A for a more detailed discussion of the usefulness of aerial  photography
in release characterization and availability of aerial photographs.

10.3.4.5  Other Sources

     Other sources of information for  subsurface and  release characterization
include:

     •   U.S. EPA files (e.g., CERCLA-related reports);
     •   U.S. Geological Survey;
     •   U.S. Department of Agriculture Soil Conservation Service;               (
     •   U.S. Department of Agriculture  Agricultural Stabilization  and
         Conservation Service;
     •   U.S. Department of Interior -Bureau of Reclamation;
     •   State Environmental Protection or Public Health Agencies;
     •   State Geological Survey;
     •   Local Planning Boards;
     •   County or City Health Departments;
     •   Local Library;
     •   Local Well Drillers; and
     •   Regional Geologic and Hydrologic Publications.

10.4 Design of a Monitoring Program to  Characterize Releases

     Information on waste, unit and environmental characterization can be used to
develop a conceptual model of the release, which  can  subsequently  be used to
design a monitoring program to fully characterize the release.  The design of a
monitoring program is discussed below.
                                   10-65

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10.4.1     Objectives of the Monitoring Program

     The objective of initial  monitoring  is to  verify or to begin characterizing
known or suspected contaminant releases to ground water. To help accomplish this
objective, the owner or operator should evaluate any existing monitoring wells to
determine if they are capable of providing samples representative of background
and downgradient ground-water quality  for the unit(s) of concern.  Figure 10-18
illustrates three possible cases where existing well systems are evaluated  with
regard to their  horizontal location for use in a ground-water investigation.
Adequacy is not only  a function of well location  but also well  construction.
Guidance on appropriate well construction materials and methods can be found in
the TEGD (EPA, 1986).  If the monitoring network-is found to be inadequate for all
or some of the units of concern, additional monitoring wells should be installed.
Further characterization, utilizing both direct and indirect investigative methods, of
the site's hydrogeology should be completed to identify appropriate locations for
the new monitoring wells.

     If initial monitoring verifies a suspected contaminant release,  the owner or
operator should  extend the  monitoring program to determine the vertical and
horizontal concentratipns (i.e., 3-dimensions) of all hazardous constituents in the
release. The rate of contaminant migration should also be determined. A variety of
investigatory techniques are available for such monitoring programs.

     Monitoring procedures should include direct methods of obtaining ground-
water quality information (e.g.,  sampling and  analysis of ground water  from
monitoring wells).   Indirect methods of investigation may also be used when
appropriate to aid in determining locations for monitoring wells  (i.e., through
geologic and/or geochemical interpretation of  indirect data).  For many cases, the
use of both direct and indirect methods may be the most efficient approach.

     Elements to be addressed in the ground-water monitoring program include:

     •    Monitoring constituents and indicator parameters;

     •    Frequency and duration at which samples will betaken;
                                   10-66

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10-67

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     •   Sampling  and analysis techniques to be used, including appropriate
         QA/QC procedures; and

     •   Monitoring locations.

     [Note:  Permit  application  regulations in 40 CFR §270.14(c)(2) require appli-
     cants to identify  the  uppermost aquifer and hydraulically interconnected
     aquifers beneath the facility property if the facility has any "regulated" units.
     The application must  indicate ground-water flow directions and provide the
     basis for the aquifer identification  (e.g., a report written by a qualified
     hydrogeologist on the hydrogeologic characteristics of the facility property
     supported by at least the well drilling logs  and available professional
     literature).  However, some RCRA  permit applications  did  not  require
     hydrogeologic  characterizations (e.g., storage only facilities)  prior to the
     HSWA Amendments of 1984. Now, such characterizations  may be required
     according to RCRA Section 3004(u) when SWMU releases to ground water are
     suspected or known. The RCRA Ground Water Monitoring Technical Enforce-
     ment Guidance Document (TEGD) (U.S. EPA, 1986), and the Permit Applicant's
     Guidance Manual for Hazardous Waste Land Treatment. Storage, and Disposal
     Facilities (U.S. EPA, 1984) should be consulted for further information on
     regulatory requirements.]

10.4.2    Monitoring Constituents and Indicator Parameters

     Initial  monitoring should be focused on rapid,  effective release character-
ization at the downgradient limit of the waste management area. Monitoring
constituents should include waste-specific subsets of hazardous constituents from
40 CFR Part 261, Appendix VIM (see Section 3 and the lists provided in Appendix B).
Indicator parameters (e.g., TOX, specific conductance) may also be  proposed as
indicated in Section 3. Such indicators alone may not be sufficient to characterize a
release of hazardous constituents, because the natural background  variability of
indicator constituents can be quite high.  Furthermore, indicator concentrations do
not precisely represent hazardous constituent concentrations, and  the detection
limits for indicator  analyses  are significantly higher than  those for  specific
constituents.
                                   10-68

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     In developing an  initial  list of monitoring constituents and indicator para-
meters, the following items should be considered:

     •    The nature of the wastes managed at the facility should be reviewed to
          determine which constituents (and any chemical  reaction products, if
          appropriate) are relatively mobile and persistent;

     •    The effects of the unsaturated zone (if present) beneath the facility on
          the mobility, stability and persistence of the waste constituents; and

     •    The concentrations and related variability of the proposed constituents
          in background ground water.

     In the absence of  detailed  waste  characterization information, the owner or
operator should review the guidance presented in Section 3, which discusses the use
of the monitoring constituent lists in Appendix B.  As discussed in Section 3, the use
of these lists is  contingent  upon  the level of  detail provided  by the waste
characterization.

     The owner  or operator  should consider monitoring for additional inorganic
indicators that characterize the general quality of water at the site (e.g., chloride,
iron, manganese, sodium, sulfate, calcium,  magnesium, potassium, nitrate,
phosphate, silicate, ammonium, alkalinity and pH). Baseline data on such indicators
can be used for subsequent monitoring  phases and for selecting corrective measures
(e.g., in assessing ground-water treatment alternatives).  This is also discussed in
Section 3 and Appendix B. Information on the major anions and cations that make
up the bulk of dissolved solids in water can  be used to determine reactivity and
solubility of hazardous constituents and therefore predict their mobility under
actual site conditions.

10.4.3     Monitoring Schedule

10.4.3.1    Monitoring Frequency

     Monitoring frequency should be based on various factors, including:
                                   10-69

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     •    Ground-water flow rate and flow patterns;

     •    Adequacy of existing monitoring data; and

     •    Climatological characteristics (e.g., precipitation patterns).

     Generally, the greater the rate  of ground-water flow, the greater the
monitoring frequency  needed.  For example, monitoring frequency  in  an
intergranular porosity flow aquifer of low permeability materials would likely be
less than for a fracture or solution porosity flow aquifer with unpredictable and
high flow rates.  In the case of  a fracture or solution porosity flow aquifer, it is
possible that contaminants could migrate past the facility boundary in a matter of
days, weeks, or months; thus requiring frequent monitoring.

     The adequacy of existing monitoring data can be a factor in determining the
monitoring schedule. For example, a facility which has performed adequate
monitoring under RCRA interim status requirements may have a  good data base
which can be helpful in evaluating initial monitoring results.  At the other end of
the spectrum are facilities lacking hydrogeologic data and monitoring systems.
Owners or operators of these facilities will need to design and install an adequate
monitoring system for the units of concern. An accelerated monitoring program is
recommended at such facilities.

10.4.3.2       Duration of Monitoring

     The duration  of the initial monitoring phase will vary with facility-specific
conditions (e.g., hydrogeology, wastes present) and should be determined through
consultation with the regulatory agency. The regulatory agency will evaluate initial
monitoring results  to determine how  long monitoring  should continue and to
determine the  need for adjustments in the monitoring schedule, the list of
monitoring constituents,  and other aspects of the monitoring  effort.   If the
regulatory agency determines that a release to ground water has not occurred, the
investigation process for  that release can be terminated at its discretion.  If
contamination is found  during  initial monitoring, further  monitoring to fully
characterize the release will generally be necessary.
                                   10-70

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10.4.4    Monitoring Locations

     If there is no existing monitoring system or if the system is inadequate to
effectively characterize ground-water contamination, the owner or operator should
design and install a well system capable of intercepting the suspected contaminant
plume(s). The system  should also be  used for obtaining relevant hydrogeologic
data. The monitoring well network configuration should be based on the site's
hydrogeology, the layout of the facility and the units of concern, the location of
receptors, and  should reflect a consideration of any information available on the
nature and source of the release.  It is important to recognize that the potential
pathways of contaminant migration are three dimensional. Consequently, the
design of a monitoring network which intercepts these potential pathways requires
a three dimensional approach.

  *   In many cases, the initial monitoring system will need to be expanded  for
subsequent phases. Additional  downgradient wells will often be needed to
determine the extent of the contaminant plume. A greater number of background
wells may also be needed to account for spatial variability in ground-water quality.

     Prior to the  installation of  additional  downgradient monitoring wells, a
conceptual model  of the release should be made from a review of waste and unit
information and current and past site characterization  information.  Additional
hydrogeologic investigations may also be appropriate.  For example, piezometer
readings surrounding the well(s) showing a release, should be used to determine
the current hydraulic gradient(s). These values should be compared to the
potentiometric surface map developed for the site hydrogeologic characterization
to better describe the direction(s) of release  migration.  Seasonal  (natural or
induced) or regional fluctuations should  be considered during this comparison.  A
re-evaluation of the .facility's subsurface geologic information should be performed
to identify preferential pathways of contaminant migration. In many situations, it
may  be appropriate to develop ground-water flow nets to show vertical and
horizontal components of flow. Guidance on  construction of flow nets is provided
in Section 10.5.2 and in the Ground Water Flow Net/Flow Line Technical Resource
Document.  NTIS  PB86-224979.  (EPA, 1985).  The installation of additional
piezometers may be necessary to verify the accuracy of the flow nets and assist in
                                  10-71

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determining  whether or not the site  hydrogeology has been adequately
characterized.

     At facilities where it is known  or likely that volatile organics have  been
released to the ground water, organic vapor analysis of soil  gas from shallow bore
holes may provide an initial  indication of the area! extent of the  release
(Figure 10-19).  An organic vapor analyzer (OVA) may  be  used  to measure the
volatile organic constituents in shallow hand-augered holes.  Alternatively, a
sample of soil gas may be extracted from a shallow hole and analyzed in the field
using a portable gas chromatograph. These techniques are limited to situations
where volatile organics are  present.  As discussed previously, it is  recommended
that, where possible, concurrent investigations of more than one  contaminated
media be conducted.  Further, the presence of intervening, saturated, low
permeability sediments strongly interferes with the ability to extract a gas sample.
Although  it is not necessarily a limitation, optimal gas chromatography results are
obtained when the analyte is matched with the highest resolution technique, (e.g.,
electron capture for halogenated species).  The effectiveness of  this approach
should be evaluated by initial OVA sampling in the vicinity of any wells known to be
contaminated.

     Other direct methods that may be used to define the extent of a release
include sampling of seeps and springs. Seeps and springs  occur where the local
ground-water surface intersects the land surface  resulting in ground-water
discharge into a stream, lake, or other surface water body. Seeps and springs may
be observed near marshes, at road cuts, or near streams. As discharges from seeps
and springs reflect the height of the  potentiometric surface, they are likely to be
most abundant during a wet season.

     To minimize the installation of new wells, the use of applicable geophysical
and modeling methods may be proposed to describe  geologic conditions and
contaminant release geometry/characteristics. Such methods can also aid in the
placement of new monitoring wells.
                                  10-72

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     A variety of indirect geophysical methods are currently available to aid  in
characterizing geologic conditions and ground-water contamination.  Geophysical
methods do not provide detailed, constituent-specific data; however, they can be
useful in investigating geologic conditions and in estimating the general  areal
extent of a release. This may reduce speculation involved in determining new well
locations.  Details on the use of geophysical methods are presented in Section 10.6
and in Appendix C.

     Mathematical and/or computer modeling results may be used in conjunction
with the results of geophysical investigations to assist in well placement decisions.
The owner or operator should not, however, depend solely on such models  to
determine the placement of new  monitoring wells.  Because models may not
accurately account for the high spatial and temporal variability of conditions
encountered in the field, modeling results should be limited to estimating the aerial
extent of a release, and in determining placement of new monitoring wells.

     In  order to estimate the potential extent of a release in the  direction  of1
ground-water flow, Darcy's law should be applied, if appropriate, to determine the
average linear ground-water velocity (see Section 10.5.3). This velocity should then
be multiplied by the age of the unit of concern (assuming the unit  began releasing
immediately)  to estimate the  potential distance of contaminant migration. This
distance should be used as a  "yardstick"  in determining well locations.  More
complex modeling (e.g., solute  transport), may be proposed  by the owner  or
operator to assist in locating  additional monitoring wells.  However, modeling
results should not be used in lieu of field monitoring data.

     The International Ground Water Modeling Center supported largely by the
U.S. Environmental Protection Agency, operates a clearing-house for ground-water
modeling software, organizes and conducts short courses and seminars, and carries
out a research  program  supporting the Center's technology transfer and
educational activities. Two major functions of the Center are the dissemination of
information regarding ground-water models and the distribution of modeling
software.  The Center maintains computerized data  bases, including updated
computer codes and test files, and descriptions of a large number of ground-water
models. By means of a search and retrieval procedure, this information  is easily
                                   10-74

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accessible and readily available.  The Center can be contacted  at the following
address:

          International Ground Water Modeling Center
          Holcomb Research Institute
          Butler University
          Indianapolis, Indiana 46208
          Telephone: (317)283-9458

The Center will send, upon request and free of charge, a listing  of available
publications, and a copy of its Newsletter.

     In selecting and applying models, it is important to remember that a model is
an artificial representation of a physical system used to characterize a site. A model
cannot replace field data, nor can it be more accurate than the available site data.
In addition, the use  of computer models requires special expertise.  Time and
experience are needed to select the appropriate code and subsequent calibration. If
these resources are not available, modeling should not be attempted. Models are
used in conjunction with scientific and engineering judgment; they are an aid  to,
not a surrogate for, a skilled analyst.

     If a  model is proposed  in the monitoring procedures, the owner or operator
should describe all assumptions used in applying the model to the site in question. A
sensitivity analysis of the model should be run to determine which  input parameters
have the most influence on model results, and the model's results should  be verified
by field sampling. The owner or operator should clear the use of any and all models
through  the  regulatory agency prior to use.   Section 3  provides additional
information on the use of models.

10.4.4.1    Background and Downgradient Wells

     Background wells (preferably upgradient) may be installed to obtain samples
that are not affected by the facility, if the owner or operator believes  that other
sources are contributing to the releases of concern. These wells should be screened
at the same stratigraphic horizon(s) as the downgradient wells. Background wells,
                                   10-75

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if installed,  should be sufficient in number to account for any heterogeneity in
background ground-water quality.

     Downgradient wells should be located and constructed to provide samples of
ground water containing any releases of hazardous constituents from the units of
concern.  Determination  of the appropriate number of wells to be included in an
initial monitoring system  should be based on various factors, including unit size and
the complexity of the hydrogeologic setting (e.g., degree  of fracturing and
variation in hydraulic conductivity).  Oowngradient monitoring wells should be
located at the limit of the waste management area of the units of concern and at
other downgradient  locations, as appropriate.  For example,  "old"  releases may
show higher constituent  concentrations at locations downgradient of the unit.  In
such cases, flow nets  may be useful in determining additional  downgradient well
locations (See Section  10.5.2).

10.4.4.2   Well Spacing

     The horizontal spacing between wells should be a design consideration. Site
specific factors as listed in Table 10-5 should be considered when determining the
horizontal distances between initial monitoring system wells. These factors cover a
variety of  physical and  operational  aspects relating to  the  facility including
hydrogeologic setting,  dispersivity, ground-water  velocity, facility design, and
waste characteristics.  In the less common homogeneous geologic setting where
simple flow patterns  are identified, a more regular well spacing pattern may  be
appropriate. Further guidance on the consideration of site specific conditions to
evaluate well spacing  is described in Chapter Two of theTEGD (U.S. EPA, 1986).

     Subsequent phase monitoring systems should be capable of identifying the
full extent of the contaminant release and establishing the concentration  of
individual constituents throughout the release.  Well installation and monitoring
should concentrate on defining those areas that have been affected by the release.
A well cluster network should be installed in and around the release to define the
horizontal and vertical extent of contamination. Networks of monitoring wells will
vary from site to site,  depending  upon hydrogeological  complexity and
contaminant characteristics.  Surface geophysical techniques and modeling may also
                                   10-76

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TABLE 10-5. FACTORS INFLUENCING THE INTERVALS BETWEEN INDIVIDUAL
         MONITORING WELLS WITHIN A POTENTIAL MIGRATION PATHWAY
Wells Intervals May Be
Closer If the Site:
• Manages or has managed liquid waste
• Is very small (i.e., the downgradient
perimeter of the site is less than 1 50
feet)
• Has waste incompatible with liner
materials
• Has fill material near the waste
management units (where preferential
flow might occur)
• Has buried pipes, utility trenches, etc.,
where a point-source leak might occur
• Has complicated geology
-closely spaced fractures
-faults
-tight folds
-solution channels
-discontinuous structures
• Has heterogenous conditions
-variable hydraulic conductivity
'- variable lithology
• Is located in or near a recharge zone
• Has a high (steep) or variable hydraulic
gradient
• Low dispersivity
• High average linear velocity
Wells Intervals May be
Wider If the Site:





• Has simple geology
-no fractures
-no faults
-no folds
-no solution channels
-continuous structures
• Has homogeneous conditions
-uniform hydraulic conductivity
-uniform lithology
*
• Has a low (flat) and constant hydraulic
gradient
• High dispersivity
• Low average linear velocity
                           10-77

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be used, where appropriate, to help facilitate release definition. The well density or
amount of sampling undertaken to completely identify the extent of migration
should be determined by the variability in subsurface geology present at the site.
Formations such as unconsolidated deposits with numerous interbedded lenses of
varying permeability, or consolidated rock with numerous fracture  traces, will
generally  require  more extensive monitoring to ensure that contamination is
appropriately characterized.

     Monitoring should be performed to characterize the interior portion(s) of a
release. This is important because constituents can migrate at differing rates and
may have been released at different times. Monitoring only at the periphery of the
release may not identify all the constituents in the release, and the concentration of
monitoring  constituents measured at the periphery  of  the  release  may be
significantly  less than in the interior portion(s).  Patterns  in concentrations of
individual constituents can be established throughout the release by sampling
along several lines that perpendicularly transect the release.  The  number of
transects and the spacing between sampling points should be based on the waste
characteristics, the size of the release, and variability in  geology observed  at the
site. Sampling locations should  also be selected so  as to identify those  areas of
maximum contamination within the release. In addition to the expected hazardous
constituents, the release may contain degradation and  reaction products,  which
may also be hazardous.

     Results of geophysical  methods  may be correlated with data from the
monitoring well network.  The  monitoring program should be flexible so that
adjustments can be made to reflect release migration and changes in direction.

     The spacing between initial  downgradient monitoring wells should ensure the
measurement of releases near the umt(s) of concern. However, it is possible that the
initial spacings between wells will only provide for measurements in the peripheral
portion of a release. This might  result in water quality measurements that do not
reflect the maximum concentration of contaminants in  the  release.  Therefore,
additional downgradient wells may be needed adjacent to the units of concern
during subsequent monitoring phases.
                                   10-78

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     A similar  effect may be  observed, even with  a closely spaced initial
downgradient monitoring network, if a narrow, localized release migrates past the
limit of the waste management area. Such a plume may originate from a small leak
in a liner and/or from a leak located close to the downgradient limit of the waste
management area, thereby limiting the amount of dispersion  occurring in  the
release prior to its passing the monitoring wells. Consequently, if relatively wide
spacing exists between wells or there is reason to expect a narrow, localized release,
the installation of additional monitoring wells may be necessary in the immediate
vicinity of those wells in which a  release has been measured. Such an expansion of
the monitoring network is recommended when a release has been measured in only
one or two monitoring wells, indicating a localized plume.

10.4.4.3   Depth and Screened Intervals

     The depth and  screened intervals for initial phase monitoring wells should be
based on: (1) geologic factors influencing the  potential contaminant pathways of
migration to ground water; (2) physical/chemical characteristics of the contaminant
controlling its likely movement  and distribution  in the ground water; and (3)
hydrologic factors likely to have an impact  on contaminant movement.  The
consideration of these factors in evaluating the design of monitoring systems is
described in the TEGD (U.S. EPA, 1986),  including examples of placement in some
common geologic environments. Subsection 10.6 provides guidance on borings and
monitoring well construction.

     In order to  establish vertical concentration gradients of hazardous
constituents in the release during subsequent  monitoring phases, well clusters or
multi-depth monitoring wells should be installed.  The first well in a cluster (or
initial sampling interval in a multi-depth  well) should be screened at the horizon in
which contamination was initially discovered. Additional wells in a cluster should
be screened, where appropriate, above and  below the initial well's sampling
interval until the margins of the release are established.

     Several wells should be placed at the fringes of the release to define its vertical
margins,  and several  wells should be  placed within the  release to identify
constituents and concentrations.  Care  must  be taken  in placing contiguously
screened wells close together because one well's drawdown may influence the next
                                   10-79

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and thus change the horizon from which its samples are drawn. Alternating lower
and higher screens should reduce this effect (see Figure 10-20).

     The specifications of sampling depths should clearly identify the interval over
which each sample will  be taken. It is important that these sampling intervals be
sufficiently discrete to allow vertical profiling of constituent concentrations in
ground water at each sampling location. Sampling will only provide measurements
of the average contaminant concentration over the interval from which that sample
is taken. Samples taken from wells screened over a large vertical interval may be
subject to dilution effects from uncontaminated ground water lying outside the
plume limits.  The proposed screened interval should reflect the expected vertical
concentration gradients within the release.

     At those facilities  where immiscible contaminants have  been  released and
have migrated as a separate phase  (see Figure 10-21), specific techniques will be
necessary to evaluate their migration.  The detection and sampling of immiscible
layers requires  specialized  equipment that  must be  used before the well is
evacuated for conventional sampling.  Chapter 4 of the TEGD  (U.S. EPA, 1986)
contains a discussion of ground-water monitoring techniques that can be used to
sample multi-phased contamination. These sampling techniques vary according to
whether the immiscible phase is lighter than water (i.e., floats) or denser than water
(i.e., sinks), and is also dependent on the thickness of the layer.

     The  formation of separate  phases of immiscible contaminants in  the
subsurface is largely controlled by the rate of infiltration  of the immiscible
contaminant and the solubility of that contaminant in ground water.  Immiscible
contaminants generally have limited solubility in water. Thus, some amount of the
immiscible contaminant released from a unit(s) will dissolve in the ground water
and thus migrate in solution.  However, if the amount of immiscible contaminant
reaching ground water exceeds the ability of ground water to dissolve it (i.e., the
constituent water solubility), the ground water in the upper portion of the water
table aquifer will become saturated and the contaminant will  form a separate
immiscible phase.  Hence, the contaminant will be present in the ground water at a
concentration approaching its water solubility, as well as in a  separate immiscible
phase.  If  cosolvents are present, the concentration of the contaminant  in the
ground  water can  exceed the contaminant's water solubility, whether or not a
separate immiscible phase is present.
                                   10-80

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Vertical Well Cluster Placement
           10-81

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     At this point, the behavior and migration of an immiscible contaminant will be
strongly influenced by its density relative to ground water. If the immiscible is less
dense than ground water, it will  tend  to form a separate immiscible layer  and
migrate on top of the ground water.  If the density of the immiscible contaminant is
similar to that of ground water, it will tend to mix and flow as a separate phase with
the ground water, creating a condition of multiphase flow.

     If the density of the immiscible constituent is greater than ground water, it will
tend to sink in  the aquifer (see Figure  10-21).  As the immiscible layer sinks and
reaches unaffected ground water in  a deeper portion of the aquifer, more of the
immiscible contaminant will tend to enter into solution in ground water and begin
to migrate as a dissolved constituent.  However, if enough of the dense immiscible
contaminants are present, some portion of these contaminants will continue to sink
as a separate immiscible phase until a geologic formation of reduced permeability is
reached.   At this point, these dense contaminants will tend to form a layer  that
migrates along the geologic formation (boundary).

     Immiscible phase  contaminants may migrate at rates different than that of
ground water.  In addition,  immiscible contaminants may not flow in the same
direction  as ground water.   However, it is important to re-emphasize that some
fraction of these contaminants may  dissolve in ground water and migrate away
from the facility as dissolved constituents.

     Light immiscible contaminants  tend to migrate downgradient as a floating
layer above the saturated zone (see Figure 10-21). The hydraulic gradient is a major
factor in  the movement of this light immiscible layer.  Other important factors
involved  in the migration rate of a  light immiscible phase  include the intrinsic
permeability of the medium, and  the density and viscosity of the contaminants.
Oftentimes, an ellipsoidal plume will develop over the saturated zone as depicted in
Figure 10-21. While it may be possible to analyze the behavior of a light immiscible
layer using analytical  or numerical models,  the  most practical approach for
determining the rate and direction of migration of such a layer is to observe its
behavior overtime with appropriately located monitoring wells.
                                   10-82

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     The migration of a layer of dense immiscibles resting on a low permeability
geologic formation may be strongly influenced by gravity. Depending on the slope
of the retarding formation, the immiscible layer may move with or in a different
direction from the flow of the ground water. Consequently, the evaluation of the
rate and direction of migration of a dense  immiscible layer  should include a
determination of the configuration  of the retarding formation  on which  the
immiscible layer is migrating. The direction of migration and estimates of migration
rates of dense immiscibles can then be obtained  by including  the gravitational
forces induced by the slope of the retarding formation in  the  gradients used to
calculate contaminant flow rates.  If a dense immiscible layer(s) is expected or
known, the monitoring plan should include procedures to verify its direction  and
rate of flow.

10.5 Data Presentation

     Section 5 of this guidance describes data presentation methods with examples.
In addition to sorted data tables, the methods described for contaminant isopleth
maps, geologic cross-sections, cross-sectional concentration contours, and  fence
diagrams should be useful for presenting ground-water investigation findings.  The
following presents specific data  presentation methods that may be particularly
useful for presenting ground-water investigation data.

10.5.1    Waste and Unit Characterization

     Waste and unit characteristics should be presented  as:

     •   Tables of waste constituents and concentrations;

     ••   Tables of relevant physical  and chemical  properties  of  waste  and
         constituents;

     •   Narrative description of unit dimensions, operations etc.; and

     •   Topographical  map and plan drawings of facility and surrounding areas.
                                   10-84

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10.5.2     Environmental Setting Characterization

     Environmental characteristics should be presented as follows:

     •    Tabular summaries of annual and monthly or seasonal relevant climatic
          information (e.g., temperature, precipitation);

     •    Narratives and maps of soil and relevant hydrogeological characteristics
          such as porosity, organic matter content and depth to ground water;

     •    Maps showing location of natural or man-made engineering barriers and
          likely migration routes; and

     •    Maps of geologic material at the site identifying the thickness, depth,
          and textures of soils, and  the presence of saturated regions and other
          hydrogeological features.

     Flow nets should be particularly useful for presenting environmental setting
information for the ground-water  medium.  A flow net  provides a graphical
technique for obtaining solutions to steady state ground-water flow. A  properly
constructed flow net can be used to determine the distribution of heads, discharges,
areas of high (or low) velocities, and the general  flow pattern (McWhorter and
Sunada,1977).

     The Ground Water Flow Net/Flow Line Technical Resource Document (TRD).
NTIS PB86-224979.  (U. S. EPA, 1985), provides detailed discussion and guidance in
the construction of flow nets.  Although the focus of this document is on the
construction of vertical flow nets, the same data  requirements and theoretical
assumptions apply to horizontal flow nets. The fundamental difference between
vertical and horizontal flow nets is in their application. A flow net in the horizontal
plane may be used to identify suitable locations for monitoring wells  whereas a
flow net in the vertical plane would  aid in determining the screened interval of a
well.
                                   10-85

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     The following excerpts from the Flow Net Document (U.S. EPA, 1985) explain
data needs for flow.net construction.  Several assumptions must be made to
construct a flow net:

     •   Ground-water flow is steady state, which means flow is  constant with
         time;

     •   The aquifer is completely saturated;

     •   No consolidation or expansion of the soil or water occurs;

     •   The same amount of recharge occurs across the system; and

     •   Flow is laminar and Darcy's law is valid.

     Knowledge  of the hydrologic parameters of the ground-water system is
required to properly construct a flow net. These parameters include:

     •   Head distribution, both horizontally and vertically;

     •   Hydraulic conductivity of the saturated zone;

     •   Saturated zone thickness; and

     •   Boundary conditions.

     The distribution of head can be determined using time equivalent water level
measurements obtained from piezometers and/or wells. Plotting the water level
elevations on a base map and contouring these data will provide a potentiometric
surface. Contour lines  representing equal  head are called lines of equipotential.
Changes in hydraulic head, both horizontally and vertically within an aquifer, must
be known for proper flow-net construction. These changes can be delineated with
piezometers or  monitoring wells installed at varying  depths  and spatially
distributed.  The  data must be time equivalent because water levels change over
time. Ground-water flow directions can be determined  by drawing  lines
                                  10-86

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perpendicular to the equipotential lines. Ground water flows from areas of higher
hydraulic head to areas of lower hydraulic head.

     The hydraulic conductivity of a material depends on the properties of the fluid
and the media.  Clayey materials generally  have low hydraulic conductivities,
whereas sands and gravels have high conductivities (U.S. EPA, 1985).  Where flow
crosses a boundary between different homogeneous media the ground-water
flowlines refract and flow velocity changes due to an abrupt change in hydraulic
conductivity.  The higher permeability formation  serves as a conduit to ground-
water flow.  This is visually apparent in a  properly constructed flow net, because
flow tubes are  narrower in  layers with higher conductivity because less area is
necessary to conduct the same  volume of  ground water.  In  media of lower
conductivity, flow tubes will be wider in order to conduct the same volume of flow
(Cedergren,  1977). Construction of flow nets for  layered geologic settings
(heterogeneous, isotropic systems)  are discussed in  Section 2 of the flow net
document (U.S. EPA, 1985).

     The boundary conditions of an aquifer must also be known  to  properly
construct a flow net.  These boundary conditions will establish the boundaries of the
flow net. The  three types of boundaries  are:   1) impermeable  boundaries;
2) constant head boundaries; and 3) water table boundaries (Freeze and Cherry,
1979).  Ground  water will not flow across an impermeable boundary; it flows
parallel to these boundaries.  A boundary  where the hydraulic head is constant is
termed a constant head boundary. Ground-water flow  at a constant head
boundary is perpendicular to the boundary. Examples of constant head boundaries
are lakes, streams, and ponds. The water table boundary is the upper  boundary of
an unconfined aquifer, and is a line of known and variable head. Flow can be at any
angle in relation to the water table due to recharge and the regional ground-water
gradient. The boundary conditions of an aquifer can be determined after a review
ofthegeohydrologicdataforasite(U.S. EPA, 1985).

     Although a complete  understanding of the  mathematics of ground-water
flow is not necessary for proper flow-net construction  by graphical  methods, a
general understanding of the theory of ground-water flow is required. For a brief
discussion of ground-water flow theory as applied to flow nets, refer to Section 1 of
the flow net document (U.S. EPA, 1985).  Detailed guidance on graphical
                                  10-87

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construction of flow nets is given in Section 2 of that document. Mathematical
techniques can be used to construct flow nets although graphical techniques are the
simplest  and most commonly used.  It is worth noting that flow  nets  are
dimensionless.

     When a flow  net has been constructed for a site, it is advisable to test the
adequacy of the flow net by installing additional piezometers at selected locations.
If the site hydrogeology is adequately characterized by the flow net, the head
values in  the new piezometer(s) will not vary significantly from those  predicted by
the flow net.

     The number of new piezometers needed to check the adequacy of the flow
net would vary depending on a number of factors including  size of the site,
complexity of the site hydrogeology, amount of data used to construct the flow net,
and the level of agreement between the site specific flow net and the regional flow
regime. For example, at a site with predominantly horizontal flow and well defined
stratigraphy, such as illustrated in Figure 10-22, a single new piezometer could test
the flow  net.  For a site with multiple, interconnected aquifers and  a significant
vertical component of flow,  such  as illustrated in Figure 10-23, several nested
piezometers might be necessary to test the flow net.

     In evaluating flow nets and the results of flow net tests, several factors should
be kept in mind. The head measurements in a new piezometer  may not exactly
match the values predicted by the flow net Some variation is inherent in this type
of measurement.  The owner or operator should evaluate whether or not the
difference between measured and predicted values is significant in the context of
flow direction or flow velocity. A new value which  reverses the direction of flow or
redirects flow towards potential receptors would obviously be significant. A change
in  flow velocity as indicated by a revised gradient might be significant  if the
magnitude of the change is substantial or if an increased velocity suggests that the
characterization needs to be extended to a greater distance.

     There are several situations in which extreme caution is needed in evaluating a
flow net test.  In many cases, temporal variations will alter the potentiometric
surface between the time the flow net is constructed and a  test piezometer is
installed. Examples of this situation would include locations with large seasonal
                                   10-88

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                                               IN
DOWNGRADIENT
                                    UPGRADIENT
                                                          HAZARDOUS WASTE
                                                          LAND APPLICATION
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                                           Equipotential Linn
                                           (in Meters)
                                           Flow Linn

                                           Wtlli with Will Numbers
    Figure 10-22.  Potentiometric surface showing flow direction
                               10-89

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variations in ground-water levels. Another situation that would introduce problems
in interpretation would be a site that is adjacent to  tidally influenced surface
waters.

     Construction of flow nets is not appropriate or valid in certain instances. As
discussed in the flow net document (U.S. EPA, 1985), these situations occur when
there is a lack of three-dimensional hydrologic data for a ground-water system, and
when ground- water flow in a system does not conform to the principles expressed
by and assumptions made in Darcy's law. Scaling problems occur when the aquifer
and/or geologic layers associated with a particular ground-water system are thin in
relation to the length of the flow net. If a flow net is constructed for this situation,
the flow net will be made up of squares that are too small to work with  unless the
scale is exaggerated.  For sites where the assumption of steady-state flow is not
valid, the construction of flow nets is very difficult. The flow net must be redrawn
each time the flow field changes to simulate the transient conditions.

     Lack of three-dimensional  hydrologic data or hydrologically equivalent data
for a  ground-water flow system makes proper flow-net construction impossible.
Hydrologic testing at various depths within an aquifer and determination of the
vertical hydraulic conductivity of an  aquifer are essential to provide the necessary
data.  If these data are not available it will be necessary to obtain them before  a
flow net can be constructed.

     There  are three types  of ground-water systems in which the principles
expressed by Darcy's  law do  not apply. The first is a system in which the  flow  is
through materials with low hydraulic conductivities under extremely  low gradients
(Freeze and  Cherry, 1979).  The second is a system in which a large amount of flow
passes through materials with very  high hydraulic conductivities.  The third is  a
system in which the porous media assumption is not valid.  Darcy's  law expresses
linear relationships and requires that flow be laminar (flow in which stream  lines
remain distinct from one another).   In a system with high hydraulic conductivity,
flow is often turbulent.  Turbulent flow is characteristic of karstic limestone and
dolomite,  cavernous volcanics, and  fractured rock systems.  Construction of  flow
nets for areas of turbulent flow would not be valid. The use of Darcy's law also
requires the assumption  of porous media flow. This assumption may not be  valid
for many  fractured bedrock and karst environments where fractured flow  is
dominant or large solution features are present.
                                   10-91

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10.5.3    Characterization of the Release

     The objective of monitoring is to estimate the nature, rate, and extent (3-
dimensional) of the release. Data are, therefore, collected from a set of monitoring
wells that will allow characterization of the dimensions and concentrations  of
constituents in the plume, as well as the rate of flow.

     Subsequent monitoring  phases may include the measurement of additional
constituents in a more extensive well network than initial monitoring.  This will
necessitate careful data management. Sections 6.8 and 6.9 of the TEGD (U.S. EPA,
1986) provide  useful guidance on  organizing,  evaluating,  and  presenting
monitoring data.  Section 4.7 of the TEGD addresses evaluation  of the quality of
ground-water data. Specific data presentation and evaluation procedures are
presented below.

     Migration rates can be determined by using the concentration of monitoring
constituents over a period of time in wells aligned in the direction of flow. If these
wells are located both at the edge of the release and in the interior of the release,
subsequent analysis of the monitoring data can then provide an estimate of the rate
of migration  both of the contaminant front as a whole and  of individual
constituents within the release. This approach does not necessarily provide a
reliable determination of the migration rates that will occur as  the contaminant
release moves further away from the  facility, due to potential changes  in
geohydrologic conditions or degradation of the contaminants. More importantly,
this approach requires the collection of a time series of data of sufficient duration
and frequency to gauge the movement of contaminants.  Such a  delay is normally
inappropriate during  initial characterization of ground-water contamination
because a relatively quick determination of at least an estimate of  migration rates is
needed to deduce the impact of ground-water contamination and to formulate  an
appropriate reaction.

     Rapid  estimates of migration rates should be  made from aquifer properties
obtained during the hydrogeologic investigation. The average linear velocity (v) of
the ground water should be calculated using the following form of Darcy's law:
         -Ki
                                  10-92

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where (K) is hydraulic conductivity, (i) is hydraulic gradient, and (ne) is the effective
porosity. This assumes that contaminants flow at the same rate as ground water.
This equation can be used to roughly estimate the rate of migration, both of the
contaminant front as a whole, and of individual dissolved constituents within the
release.

     Rough estimates of migration rates beyond the facility property boundary can
be  made based on  aquifer properties obtained during  the site hydrogeologic
characterization and knowledge of the physical and chemical properties of
contaminants known to  be present.  By recognizing the various factors which can
affect the  transport of monitoring constituents, the owner  or operator can
determine approximate migration rates. Continued monitoring of the release over
time should be conducted to verify the rate(s) of migration. Information on rate(s)
of  migration should be used  in  determining any additional monitoring well
locations.

     More  refined  estimates of contaminant migration rates should consider
potential differential transport rates among various monitoring constituents.
Differential transport rates are caused by several factors, including:

     •   Dispersion due to diffusion and mechanical mixing;

     •   Retardation due to adsorption and electrostatic interactions; and

     •   Transformation due to physical, chemical, and/or biological processes.

     Dispersion results  in the overall dilution  of the contaminant; however,
chromatographic  separation of the contaminant constituents and  differential
dispersion effects can result in a contaminant arriving at a particular location before
the arrival time computed solely on  the average linear velocity of ground-water
flow. Alternately, retardation  processes can delay the arrival of contaminants
beyond that calculated using average ground-water flow rate(s). Transformation of
waste constituents is a complex process which can be difficult to estimate.  While
some contaminants,  such as radionuclides, decay at a constant rate over time, most
degradabie chemicals are influenced by a variety of factors and  the interactions of
                                   10-93

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these factors can be extremely difficult to predict. Local geologic variations will also
affect constituent migration rates. Relating constituent migration rates to ground-
water flow rates is a reasonable and relatively quick way to estimate contaminant
flow rates. Where possible, contaminant- specific migration  rates should also be
determined.

     Procedures  for the evaluation of monitoring  data vary  in a site-specific
manner, but should all result in determinations of the rate of migration, extent, and
composition of hazardous constituents of the release.  Where the  release is obvious
and/or chemically simple, it may be possible to  characterize it readily from a
descriptive presentation of concentrations found in monitoring wells and through
geophysical measurements.  Where contamination is less obvious or the release is
chemically complex, however, the owner or operator may  employ a statistical
inference approach.  The owner or operator should plan  initially to take a
descriptive approach to data analysis in order to broadly delineate the  extent of
contamination. Statistical comparisons of monitoring data among wells and/or over
time may be  necessary, should the descriptive approach provide  no  clear
determination of the rate of migration, extent, and hazardous constituent
composition of the release.

10.6 Field Methods

10.6.1     Geophysical Techniques

     During the past decade, extensive development of remote sensing geophysical
equipment, portable field instrumentation, field methods, analytical techniques
and related computer processing have resulted in an improvement in the capability
to characterize hydrogeology and contaminant releases.  Some of these geophysical
methods offer a  means of detecting contaminant plumes and flow directions in
both the saturated and unsaturated zones. Others offer a way to obtain detailed
information about subsurface soil and rock characteristics. This capability to rapidly
analyze subsurface conditions without disturbing the site may  provide  a better
overall understanding of complex site conditions, with relatively low risk to the
investigative team.
                                   10-94

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     Various geophysical techniques, including electromagnetic, seismic refraction,
electrical resistivity, ground penetrating radar, magnetic, and several borehole
methods, can be applicable to RCRA Facility Investigations.  Table 10-6 suggests
appropriate applications for the various geophysical methods.  Appendix C provides
additional information.

10.6.2     Soil Boring and Monitoring Well Installation

10.6.2.1       Soil Borings

     Soil borings should be sufficient to characterize the subsurface geology below
the site. Section 1.2 of TEGD (U.S. EPA, 1986) provides criteria for adequate borings.
A summary of these criteria is presented below.

     •    Installation of initial boreholes at a density based on criteria described in
          Table 10-7 and sufficient to provide initial information  upon which to
          determine the  scope  of a more detailed evaluation of geology  and
          potential pathways of contaminant migration.

     •    Initial boreholes should be drilled into the first confining layer beneath
          the uppermost  aquifer. The portion of the borehole extending into the
          confining layer should be plugged properly after a sample is taken.

     •    Additional boreholes should be installed in numbers and locations
          sufficient to characterize the geology beneath the site. The number and
          locations of additional boreholes should  be based on data from initial
          borings and indirect investigation.

     •    Collection of samples of every significant stratigraphic contact  and
          formation, especially the confining layer  should be taken.  Continuous
          cores should be taken initially to ascertain the presence and distribution
          of small  and large  scale permeable layers. Once stratigraphic control is
          established, samples taken at regular intervals (e.g., five foot) could be
          substituted for continuous cores.
                                   10-95

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TABLE 10-7.  FACTORS INFLUENCING DENSITY OF INITIAL BOREHOLES
Factors That May Substantiate
Reduced Density of Boreholes:
• Simple geology (i.e., horizontal, thick,
homogeneous geologic strata that are
continuous across site that are
unfractured and are substantiated by
regional geologic information).
• Use of geophysical data to correlate
well log data.



Factors That May Substantiate
Increased Density of Boreholes:
• Fracture zones encountered during
drilling.
• Suspected pinchout zones (e.g.,
discontinuous areas across the site).
• Geologic formations that are tilted or
folded.
• Suspected zones of high permeability
that would not be defined by drilling
at 300-foot intervals.
• Laterally transitional geologic units
with irregular permeability (e.g.,
sedimentary facies changes).
                         10-97

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     •   Boreholes in which permanent wells are  not constructed should  be
         sealed with materials at least an order of magnitude less permeable than
         the surrounding soil/sediment/rock in order to reduce the number of
         potential contaminant pathways.

     •   Samples should be logged in the field by  a qualified professional
         geologist.

     •   Sufficient  laboratory analysis should  be  performed to  provide
         information concerning petrologic variation, sorting (for unconsolidated
         sedimentary units), cementation (for consolidated sedimentary units),
         moisture content, and hydraulic conductivity of each significant geologic
         unit or soil zone above the confining layer/unit.

     •   Sufficient laboratory  analysis should be  performed to describe the
         mineralogy (X-ray diffraction), degree of compaction, moisture content,
         and other pertinent characteristics of any  clays or other fine- grained
         sediments held  to be  the confining unit/layer.  Coupled  with the
         examination of clay mineralogy and structural characteristics should be a
         preliminary analysis of the reactivity of  the confining layer in the
         presence of the wastes present.

     ASTM or equivalent methods should be used for soil classification, specifically:

     •   ASTM Method D422-63 for the particle size analysis of soils, which
         describes the quantitative  determination of the distribution of particle
         sizes in soils; and

     •   ASTM Methods 02488-69,  for the identification and description of soils
         based on visual examination and simple manual tests.

     An adequate number of geologic cross-sections should be  presented by the
owner or operator. These cross-sections should adequately depict major geologic or
structural trends and reflect geologic/structural  features in relation  to ground-
water flow.  Additionally,  an owner or operator should provide a surface topo-
                                   10-98

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graphic map and aerial photograph of the site. Details regarding specific means for
the presentation of geologic data are presented in Section 5 and in Section 1.2.3 of
the TEGD (U.S. EPA, 1986).

10.6.2.2   Monitoring Well Installation

     The owner or operator is advised to consult Chapter Three of the TEGD (U.S.
EPA, 1986)  for guidance on monitoring well installation. This chapter provides
information on the following topics:

     •   Drilling Methods  for Installing Wells-Section 3.1  (TEGD) discusses a
         variety of well drilling methods and corresponding applicability to the
         installation of RCRA monitoring wells. The selection of the actual drilling
         method that an owner or operator should use at a particular site is a
         function of site-specific geologic conditions.   Of  utmost importance is
         that the drilling method the owner or operator uses will minimize the
         disturbance of subsurface materials and will not cause contamination of
         the ground water.

     •   Monitoring Well Construction Materials-Section 3.2 (TEGD) discusses the
         selection of construction materials for RCRA monitoring wells which are
         durable enough to resist chemical and physical degradation, and do not
         interfere with  the  quality of ground-water samples.   Specific well
         components that are of concern include well casings, well screens, filter
         packs, and annular seals.

     •   Design of Well Intakes-Section 3.3 (TEGD) discusses the design and
         construction of the intake of monitoring wells so as  to:  (1)  allow
         sufficient ground-water flow to the well for sampling; (2) minimize the
         passage of formation materials (turbidity) into the well;  and (3) ensure
         sufficient structural integrity to  prevent the collapse  of the intake
         structure.

     •   Development of Wells-Section 3.4 (TEGD) discusses the requirements for
         proper development  of the monitoring wells to  ensure turbid-free
         ground water samples.
                                   10-99

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•    Documentation of Well Construction Activity-Section 3.5 (TEGD) lists the
     information required for the design and construction of wells as follows:

          date/time of construction;
          drilling method and drilling fluid used;
          well location (±,Q.S ft);
          borehole diameter and well casing diameter;
          well depth (.+.0.1 ft);
          drilling and lithologic logs;
          casing materials;
          screen materials and design;
          casing and screen joint type;
          screen slot size/length;
          filter pack material/size;
          filter pack volume calculations;
          filter pack placement method;
          sealant materials (percent bentonite);
          sealant volume (Ibs/gallon of cement);
          sealant placement method;
          surface seal design/construction;
          well development procedure;
          type of protective well cap;
          ground surface elevation (_+_ 0.01 ft);
          top of casing elevation (.±.0.01 ft); and
          detailed drawing of well (including dimensions).

•    Specialized Well Design-Section 3.6 (TEGD) discusses two cases which
     require special monitoring well design: (1) where dedicated pumps are
     used to draw ground-water samples;  and (2) where light and/or dense
     phase immiscible layers are present

•    Evaluation of Existing Wells-Section 3.7 (TEGD)  discusses how to
     evaluate the ability of existing wells to produce representative ground-
     water samples.
                              10-100

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     Particular attention should be paid to the discussion in Section 3.2.1 regarding
well casing materials (TEGD). It is imperative that well materials are nonreactive to
contaminants that may be present in the ground water. In cases where the facility
has existing monitoring wells which could potentially be used in the RFI, the owner
or operator should evaluate whether these wells are capable of  producing
representative ground-water samples.  A demonstration involving the installation
of new well(s) near existing wells and the analysis and comparison of samples for
the same monitoring constituents from both wells may be necessary if the existing
wells' integrity is in question.

10.6.3     Aquifer Characterization

10.6.3.1   Hydraulic Conductivity Tests

     In addition to defining the direction of ground-water flow in the vertical and
horizontal direction, the owner or operator should identify areas of high and low
hydraulic  conductivity within each formation.   Variations  in the  hydraulic
conductivity of subsurface materials can create irregularities in ground-water flow
paths.  Areas of high  hydraulic conductivity represent areas of greater ground-
water  flow and, if contaminants  are present, zones of potential migration.
Therefore, information on hydraulic conductivities is generally required before the
owner or operator can make reasoned decisions regarding well placements. It may
be beneficial to use analogy or laboratory methods to corroborate results of field
tests; however, only field methods provide direct  information that is adequate to
define the hydraulic conductivity.

     Hydraulic conductivity  can be determined in  the field using single well tests,
more commonly referred to  as slug tests, which are performed by suddenly adding
or removing a slug (known volume) of water from a well or piezometer and
observing the recovery of the water surface to its original level.  Similar results can
be achieved by pressurizing the well casing,  depressing the  water level, and
suddenly releasing the pressure to simulate removal of water from the well. Where
slug tests are not appropriate  (e.g., in fractured  flow aquifers),  hydraulic
conductivity can be determined by multiple well (pumping) tests.
                                  10-101

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     Slug testing  is applied  by hydrogeologists in  many field  situations.
Interpretation  of the results requires some professional judgement.  Slug test
accuracy  is reduced when dealing with  extreme values of hydraulic conductivity.
Very low values (e.g., less than 10-6 cm/sec) are more accurately measured by a
resurg head test after bailing or pumping the well dry. High values (e.g., greater
than 10-2 cm/sec) generally require fast response electronic  measurement
equipment. High value cases in fractured rock or karst terrain may be misleading if
the slug test is measuring the most permeable fractures or solution channels. In
such cases, the test results may be misinterpreted to give an artificially high  value
for the formation as a whole.

     When reviewing information obtained from slug  tests, several  criteria should
be considered. First, slug tests are run on one well  and, as such, the  information
obtained from single well tests is limited in scope  to the geologic area directly
adjacent to the well. Second, the vertical extent of screening will control the part of
the geologic formation that is being tested during the slug test. That part of the
column above or below the screened interval that has not been tested during the
slug test will not have been adequately tested for hydraulic conductivity.  Third, the
methods  used to collect the information obtained  from slug tests should be
adequate to measure accurately parameters such as changing static water (prior to
initiation, during, and following completion of slug test), the amount of water
added to, or removed from the well, and  the elapsed time of recovery.  This is
especially important in highly permeable formations where pressure transducers
and high  speed recording equipment should be used.  Lastly, interpretation of the
slug test  data should be consistent with the existing  geologic information (e.g.,
boring log data). It is, therefore, important that the program of slug testing ensure
that enough tests are run to provide  representative  measures of  hydraulic
conductivity, and to document lateral  and vertical  variation  of  hydraulic
conductivity in the geologic materials below the site.

     It is important that  hydraulic conductivity measurements define hydraulic
conductivity both in a vertical and horizontal manner across  a site.  In assessing
hydraulic conductivity measurements, results from the boring program used to
characterize the  site geology should be considered. Zones of expected high
permeability or fractures identified from drilling logs should generally be included
in  the determination of hydraulic conductivity.  Additionally, information from
                                  10-102

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coring logs can be used to refine the data generated by slug tests (TEGD, Section
1.3.3).

     Techniques for determining hydraulic conductivity are specified in Method
9100, Saturated Hydraulic Conductivity, Saturated Leachate Conductivity, and
Intrinsic Permeability; from SW-846, Test Methods for Evaluating Solid Waste. 3rd
edition. 1986. Method 9100 includes techniques for:

     •    Laboratory

               sample collection;
               constant head methods; and
               falling head methods.

     •    Field

               well construction;
               well development;
               single well tests (slur tests); and
               references for multiple well (pumping) tests.

     Cedergren, 1977 also provides an  excellent discussion on aquifer tests,
including  laboratory  methods (constant  head and falling head), multiple well
(pumping) tests (steady-state and nonsteady-state), and single well tests (open-end,
packer, and others).

10.6.3.2   Water Level Measurements

     Water level measurements are necessary for determining depth to the water
table and  mapping ground-water contours to determine hydraulic gradients and
flow rates. Depths to water are normally  measured with respect to the top of the
casing as in well depth determinations.  Several methods are available, including
the electric sounder and the chalked steel tape.

     The  electric sounder, although  not the  most accurate method, is
recommended for initial site work because of the minimal potential for equipment
                                  10-103

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contamination and simplicity of use. Sounders usually consist of a conductivity cell
at the end of a graduated wire, and  a battery powered buzzer.  When the cell
contacts the water the increased conductivity completes the circuit and allows
current to flow to the alarm buzzer.  The depth to water can then be read from the
graduations on the wire or the wire  can be measured directly. This device may not
be suitable for use if  a potentially flammable or explosive layer (e.g., due to
methane gas) is present in the well, unless it is an intrinsically safe device.

     The chalked steel tape is a more accurate device for measuring static water
levels. The lower 0.5 to 1.0 meters of a steel measuring tape is coated on either side
with either carpenter's chalk or any of the various indicating pastes.  A weight is
attached to the lower end to keep the tape taut and it is lowered into the center of
the well (condensate on the casing wall may  prematurely wet the tape).  A hollow
"plopping" sound occurs when the weight reaches water, then the tape is lowered
very  slowly for at least another 15  cm, preferably to an even  increment on the
measuring tape. Next,  the tape is carefully withdrawn from the well; water depth is
determined by subtracting the wetted  length of tape from the total length of tape
in the well. In small diameter wells, the volume of the weight may cause the water
to rise by displacement. In general,  the use of indicating paste or chalk should be
discouraged although  they may not  present a significant problem if water samples
are not collected. As with all depth measurement devices, the wetted section of the
tape and  the weight  must  be thoroughly cleaned  before reuse  to avoid  cross
contamination.

     The following sections of the TEGD (U.S. EPA, 1986) should be consulted for
water level measurement requirements, and information on data interpretation:

     •     Ground-water level measurement (1.3.1.1);

     •     Interpretation of ground-water level measurements (1.3.1.2);

     •     Establishing vertical components of ground-water flow (1.3.1.3); and

     •     Interpretation of flow direction (1.3.1.4).
                                  10-104

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10.6.3.3   Dye Tracing

     Dye tracing is a field method which can be used to measure the velocity of
ground water for highly permeable strata (such as karst terrain and highly fractured
rock media). When the velocity of flowing water and the hydraulic gradient at a
common point  are known, the permeability can be estimated.  The hydraulic
gradient (i) of an existing water table can be estimated from wells in the area.  If
not, observation welfs must be installed (Cedergren, 1977).

     The procedure used in dye tracing involves the insertion of a dye, such as
fluorescein sodium into a test hole and observation of the time it takes to emerge in
a nearby test pit or on a bank from which seepage is emerging. The average linear
velocity, v, is determined by dividing the distance traveled, L, by the time of travel, t.
The effective porosity, ne, is determined from test data for the in-place soil; if no
tests are available, it is determined using the values in Table 10-4.  The hydraulic
conductivity is calculated from the equation:
          v n«
     It should be noted that the time required for tracers to move even short
distances can be very long unless the formations contain highly permeable strata
(Cedergren, 1977). As a result of the limitations of tracer techniques, this type of
study is applied only in highly specialized locations. Uncertainties associated with
the flow path make interpretation of the results difficult. This technique has been
used effectively in conjunction with modeling  in complex terrain with the tracer
study serving to calibrate the model.

10.6.4    Ground-Water Sample Collection Techniques

     The procedure for collecting a ground water sample involves the following
steps presented in Chapter 4 of TEGD (U.S. EPA, 1986):

     •   Measurement of static water level elevation (4.2.1);
                                   10-105

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     •    Monitoring of immiscible layers (4.2.2);

     •    Well evacuation (4.2.3);

     •    Sample withdrawal (4.2.4);

     •    In situ or field analyses (4.2.5);

     •    Sample preservation and handling (4.3); and

     •    Chain-of-custody procedures (4.4).

     Collection of static water level elevations on a continuing basis is important to
determine if horizontal and vertical flow gradients have changed since initial site
characterization, which  could necessitate modification of the  ground-water
monitoring system.  Steps should be  taken to monitor for the presence and/or
extent of  light and/or dense phase immiscible organic layers before  the well  is
evacuated for conventional sampling if wastes of this type are present at the
facility.

     The water standing in the well prior to sampling may not be representative of
in situ ground-water quality. Therefore, the owner or operator should remove the
standing water in the well so that water which is representative of the formation
can replace the standing water. Purged  water should be collected and screened
with photoionization or organic vapor analyzers, pH, temperature, and conductivity
meters.  If these parameters and facility background data suggest that the water
may be hazardous, it should be drummed and disposed of properly.

     The technique used to withdraw a ground-water sample from a well should be
selected based on a consideration of the parameters which will be analyzed in the
sample. To ensure the ground-water sample is representative of the formation, it is
important to avoid  physically altering or chemically contaminating the  sample
during the withdrawal process.  In  order to minimize the possibility  of  sample
contamination, the owner or operator should:
                                  10-106

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     (1)  Use only polytetrafluoroethylene  (PTFE) or stainless steel  sampling
         devices; and

     (2)  Use dedicated samplers for each well.  (If a dedicated sampler is not
         available for each well, the sampler should  be thoroughly cleaned
         between sampling events, and blanks should be taken and analyzed to
         ensure that cross contamination has not occurred.)

     Section 4.2.4 of TEGD (U.S. EPA, 1986) includes specific factors to take into
consideration regarding sample withdrawal.

     Some parameters are physically or chemically unstable and must  be tested
either in the borehole using a probe (in situ) or immediately after collection using a
field test kit. Examples of several unstable parameters include pH, redox potential,
chlorine, dissolved oxygen, and temperature. Although  specific conductivity
(analogous to electrical resistance) is relatively stable, it is recommended that this
characteristic also be determined in the field.  Most conductivity  instruments
require temperature compensation; therefore, temperatures of the samples should
be measured at the time conductivity is determined.

     Many of the constituents and parameters that are included in ground-water
monitoring programs are not stable and, therefore, sample preservation may be
required. Refer to methods from EPA's Test Methods for  Evaluating Solid Waste  -
Physical/Chemical Methods. 1986 (EPA/SW-846 GPO No. 955-001-00000-1) for
sample preservation procedures and sample container requirements.

     Improper sample handling may lead to sample contamination. Samples should
be transferred into their containers in such a way as to minimize any contamination.
Handling methods are analyte dependent. Special handling considerations for
various analyte types are discussed in Section 4.3.3 of the TEGD (U.S. EPA, 1986).

     An adequate chain-of-custody program will allow for the tracing of possession
and  handling of individual samples from the time of field collection through
laboratory analysis.   An owner  or operator's chain-of-custody  program
requirements are detailed in Section 4 (Quality Assurance and Quality Control).
                                  10-107

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     Chapter Four of the TEGD (U.S. EPA, 1986) may also be consulted for sample
collection techniques as well  as for analytical  procedures, field and laboratory
QA/QC requirements, and suggestions for reporting of ground-water data. Section
4 of this guidance presents a general discussion of QA/QC. In addition, the owner or
operator may also find the following publication useful for sampling information:

     •   U.S. EPA. September, 1987.  Practical Guide for Ground Water Sampling.
         EPA/600/2-85/104. NTIS PB86-137304. Washington, D.C. 20460.

10.7 Site Remediation

     Although the RFI Guidance is not intended to provide detailed guidance  on
site remediation, it should be recognized that certain data collection activities that
may be necessary for a Corrective Measures Study may be collected during the RFI.
EPA  has developed a practical guide for assessing and remediating contaminated
sites that directs users toward technical support, potential data requirements and
technologies that  may be applicable to  EPA programs such as RCRA and CERCLA.
The reference for this guide is provided below.

     U.S. EPA.  1988. Practical Guide for Assessing and Remediating Contaminated
     Sites.  Office of Solid Waste and  Emergency Response.  Washington, D.C.
     20460.

     This guide is designed to address  releases to ground water as well as soil,
surface water and air.  A short description of the guide is provided in Section  1.2
(Overall RCRA  Corrective  Action  Process),  under the discussion of  Corrective
Measures Study.

     In addition to the above described reference, several ground-water computer
modeling programs are available to assist in designing ground-water remediation
systems, such as the one referenced below.  Application of such models should  be
based  on site-specific  considerations, as most  models are not applicable  to  all
situations.

     U.S. EPA.  1987. Zone of Capture for Ground Water Corrective Action. IBM
     Compatible Computer Program and Users Guide.  Federal Computer Products
                                  10-108

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10.8 Checklist

                       RFI CHECKLIST- GROUND WATER
Site Name/Location,
Type of Unit	
1.    Does waste characterization include the following information?      (Y/N)
          •   Constituents of concern/supporting indicator parameters
          •   Concentrations of constituents
          •   Physical form of waste
          •   Chemical properties of waste (organic, inorganic,
               acid, base) and constituents
          •   pH
          •   pKa
          •   Viscosity
          •   Water solubility
          •   Density
          •   KQW
          •   Henry's Law Constant
          •   Physical and chemical degradation (e.g., hydrolysis)

2.    Does unit characterization include the following information?        (Y/N)
          •   Age of unit                                           	
          •   Construction integrity                                  	
          •   Presence of liner (natural or synthetic)                    	
          •   Location relative to ground-water table or bedrock or     	
                other confining barriers
          •   Unit operation data                                    	
          •   Presence of cover
          •   Presence of on/off site buildings
          •   Depth and dimensions of unit
          •   Inspection records
          •   Operation logs
                                   10-110

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                 RFI CHECKLIST- GROUND WATER (Continued)

          •    Past fire, explosion, or other complaint reports
          •    Existing ground-water monitoring data
          •    Presence of natural or engineered barriers near unit

3.    Does environmental setting information include the following information?
                                                                    (Y/N)
     Site Soil Characteristics
          •    Grain size distribution and gradation                    	
          •    Hydraulic Conductivity
          •    Porosity
          •    Discontinuities in soil strata (e.g., faults)
          •    Degree and orientation of subsurface stratification
               and bedding             *
     Ground-Water Flow System Characterization                       (Y/N)
          •    Use of aquifer
          •    Regional flow cells and flow nets
          •    Depth to water table
          •    Direction of flow
          •    Rate of flow
          •    Hydraulic conductivity
          •    Storativity/specific yield (effective porosity)
          •    Aquifer type (confined or unconfined)
          •    Aquifer characteristics (e.g., homogeneous, isotropic,
               leaky)
          •    Hydraulic gradient
          •    Identification of recharge and discharge areas
          •    Identification of aquifer boundaries (i.e., area! extent)
          •    Aquitard characteristics (depth, permeability degree of
               jointing, continuity)
                                   10-111

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                 RFI CHECKLIST- GROUND WATER (Continued)

     Ground-Water Quality Characteristics                            (Y/N)
          •    Presence of minerals and organics                      	
          •    Background water quality
          •    Monitoring constituents and indicator parameters

4.    Have the following data on the initial phase of the release characterization
     been collected?                                                (Y/N)
          •    Extent
          •    Location
          •    Shape
          •    Hydraulic gradient across plume
          •    Depth to plume
          •    Chemistry and concentration
          •    Velocity
          •    Potential receptors
5.    Have the following data on the subsequent phase(s) of the release character-
     ization been collected?                                          (Y/N)
          •   Extent
          •   Location
          •   Shape
          •   Hydraulic gradient across plume
          •   Depth to plume
          •   Chemistry and concentration
          •   Velocity
          •   Potential receptors
                                  10-112

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10.9 References

ASTM. 1984. Annual Bookof ASTM Standards. Volume 4.08: Natural Building
     Stones;  Soil and Rock.   American  Society  for  Testing  and  Materials.
     Philadelphia, PA.

Balch, A. H., and W. W. Lee. 1984. Vertical Seismic Profiling Technique. Applications
     and Case Histories. DE83751260. International Human Resource Development
     Corp.

Billings. 1972. Structural Geology. 3rd Edition. Prentice-Hall, Inc. Englewood
     Cliffs, New Jersey.

Brady. 1974. The Nature and Properties of Soils. 8th Edition. MacMillan
     Publishing Co., Inc. New York, N.Y.

Callahan,etal. 1979. Water-Related Environmental Fate of 129 Priority Pollutants.
     EPA-440/4-79-029. NTIS PB80-204373. Washington, D.C. 20460.

Cedergren.  1977. Seepage. Drainage, and Flow Nets.  2nd  Edition. John Wiley &
     Sons. New York, N.Y.

Freeze and Cherry. 1979. Ground water.  Prentice-Hall, Inc. Englewood Cliffs,
     New Jersey.
                                                              «
Linsley, R.K., M.A. Kohler, and J. Paulhus.  1982. Hydrology for Engineers.  Third
     Edition. McGraw-Hill, Inc. New York, N.Y.

McWhorterandSunada. 1977. Ground Water Hydrology and Hydraulics.  Water
     Resources Publications. Littleton, Colorado.

Oki, D.S. and T.W. Giambelluca, "DBCP, EDB, and TCP Contamination of Ground
     Water in Hawaii," Ground Water. Vol. 25, No. 6, November/December 1987.

Snoeyink and Jenkins. 1980. Water Chemistry. John Wilev & Sons. New York, N.Y.
                                  10-113

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Sowers, G. F. 1981. Rock Permeability or Hydraulic Conductivity-An Overview  in.
     Permeability and Ground Water Transport. T. F. Zimmic and C. 0. Riggs,   Eds.
     ASTM Special Technical Publication 746. Philadelphia, PA.

Sun, R.J.,  Editor.  1986.   Regional  Aquifer-System Analysis Program of the U.S.
     Geological Survey. Summary of Projects. 1978 - 1984.  U.S.G.S. Circular 1002.
     U.S. Geological Survey. Denver, CO.

Technos, Inc. 1982. Geophysical Techniques for Sensing Buried Wastes and Waste
     Migration. Environmental Monitoring Systems Laboratory. NTIS PB84-198449.
     U.S. EPA. Washington, D.C. 20460.

U.S. Department of Agriculture. 1975. Soil Taxonomy: A Basic System of Soil
     Classification for Making  and Interpreting Soil Surveys. Soil  Survey Staff, Soil
     Conservation Service. Washington, D.C.

U.S. Department of the Army.  1979.  Geophysical Explorations. Army Corps of
     Engineers. Engineering Manual 1110-1-1802. May, 1979.

U.S. EPA.  1985.  Characterization of Hazardous Waste Sites - A Methods Manual.
     Volume I - Site Investigations. EPA-600/4-84/075. NTIS PB85-215960. Office of
     Research and Development. Washington, D.C. 20460.

U.S. EPA.  1984.  Characterization of Hazardous Waste Sites - A Methods Manual:
     Volume II: Available Sampling Methods. 2nd Edition.  EPA-600/4-84-076. NTIS
     PB 85-168771. Office of Research and Development. Washington, D.C. 20460.

U.S. EPA.  1986.  Ground Water Flow Net/Flow Line Technical Resource Document
     (TRD).  Final Report. NTIS PB86-224979. Office of Solid Waste. Washington,
     D.C. 20460.

U.S. EPA.  1985.  Guidance on Remedial Investigations Under CERCLA. NTISPB85-
     238616.   Hazardous Waste Engineering Research   Laboratory,  Office  of
     Research and Development. Cincinnati!, OH 45268.
                                  10-114

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U.S. EPA.  1982. Handbook for Remedial Action at Waste Disposal Sites. EPA-625/6-
     82-006.  NTIS  PB82-239054.  Office of Emergency and Remedial Response.
     Washington, D.C. 20460.

U.S. EPA. 1984. Permit Applicant's Guidance Manual for Hazardous Waste - Land
     Treatment.  Storage,  and  Disposal  Facilities.   Office  of  Solid  Waste.
     Washington, D.C. 20460.

U.S. EPA.  1985.  DRASTIC:  A Standardized System for Evaluating Ground-water
     Pollution Potential Using HvdroqeoloqicSettings.  EPA/600/2-88/018. Roberts.
     Kerr Environmental Research Laboratory. Ada, OK.

U.S. EPA.  1986. Guidance Criteria for Identifying Areas of Vulnerable Hydroqeoloqy
     Under  the Resource  Conservation  and  Recovery  Act.  Interim  Final.
     Washington, D.C. 20460

U.S. EPA.  1986. Permit Writers' Guidance Manual for the Location of Hazardous
     Waste Land Storage and Disposal Facilities - Phase II:  Method for Evaluating
     the Vulnerability of Ground V/ater.  NTIS PB86-125580. Office of Solid Waste.
     Washington, D.C. 20460.

U.S. EPA.  1985. Practical Guide for Ground Water Sampling. EPA-600/2-85/104.
     NTIS PB86-137304. Washington, D.C. 20460.

U.S. EPA.  1985. RCRA Ground-Water Monitoring Compliance Order Guidance
     (Final). Office of Solid Waste. Washington, D.C. 20460.

U.S. EPA.  1986. RCRA Ground-Water Monitoring Technical Enforcement Guidance
     Document. Office of Solid Waste. Washington, D.C. 20460.

U.S. EPA.  1987. Zoneof Capture for Ground Water Corrective Action. IBM
     Compatible Computer Program and Users Guide.  Federal Computer Products
     Center, National Technical Information Service. Springfield, VA 22161.
                                  10-115

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U.S. EPA.  1988. Practical Guide for Assessing and Remediating Contaminated
    Ground Water. Office of Emergency and Remedial Response.  Washington,
    D.C 20460.

U.S. Geological Survey.  1984. Ground water Regions of the U.S. Heath et.al.,
    Water Supply Paper No 2242. Washington, D.C.
                                 10-116

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                                SECTION 11

                             SUBSURFACE GAS
11.1 Overview

     This section applies to units with subsurface gas releases, primarily landfills,
leaking underground tanks, and units containing putrescible organic matter, but
may include other units.

     The objective of an investigation of a subsurface gas release is to verify,  if
necessary, that subsurface gas migration has occurred and  to characterize the
nature, extent, and rate  of  migration  of the release of gaseous material or
constituents through the soil.  Methane gas should be monitored because it poses a
hazard due to its explosive properties when it reaches high concentrations, and also
because it can serve as an indicator (i.e., carrier gas) for the migration of hazardous
constituents. Other gases (e.g., carbon dioxide and sulfur dioxide) may also serve as
indicators. This section provides:

     •    An example strategy  for characterizing subsurface gas releases, which
          includes characterization of the source and the environmental setting of
          the release, and conducting monitoring to characterize the release itself;

     •    Formats for data organization and presentation;

     •    Field methods which may be used in the investigation; and

     •    A checklist  of information  that may be needed  for  release
          characterization.

     The exact type and amount of information required for sufficient release
characterization will be site-specific and should be determined through interactions
between the regulatory  agency  and  the facility owner or operator during the RFI
process. This guidance does not define the specific data required in all instances;
                                    11-1

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however, it identifies possible information which may be necessary to perform
release characterizations and methods for obtaining this information.  The RFI
Checklist, presented at the end of this section, provides a tool for planning and
tracking information for subsurface gas release characterizations.  This list is not
meant to serve as a list of requirements for all subsurface gas releases to  soil. Some
releases will involve the collection of only a subset of the items listed.

     As indicated in the following sections, subsurface gas migrates along the path
of least resistance, and can accumulate in structures (primarily basements) on or off
the facility property. If this occurs, it is possible that an immediate hazard may exist
(especially if the structures are used or inhabited by people) and that interim
corrective measures may be appropriate. Where conditions warrant, the owner or
operator should  immediately contact the regulatory agency and consider
immediate measures (e.g., evacuation of a structure),

     Case Study Numbers 23 and  24 in Volume IV (Case Study Examples) provide
examples of subsurface gas investigations.

11.2  Approach for Characterizing Subsurface Gas Releases

11.2.1    General Approach

     The collection and review of existing information for characterization of the
contaminant source and the environmental setting will be the primary basis for
development of a conceptual model of the release and subsequent development of
monitoring procedures  to characterize the release.  A conceptual model of the
release should be formulated  using all available information  on the waste, unit
characteristics, environmental  setting,  and any existing monitoring data.  This
model (not a computer or numerical simulation model) should provide a working
hypothesis of the release mechanism, transport pathway/mechanism, and exposure
route (if any).  The model should  be testable/verifiable and flexible enough to be
modified as new data become available.
                                   11-2

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     The conceptual model for subsurface gas should consider the ability of the
waste to generate gaseous constituents, the conditions which would favor
subsurface migration of the gaseous release, and the likelihood of such a release to
reach and accumulate within structures (e.g., residential basements) at explosive or
toxic concentrations.

     Additional data collection to  characterize the contaminant source  and
environmental setting  may be necessary prior to implementing the monitoring
procedures.  The subsurface pathway data collection effort should be coordinated,
as appropriate, with similar efforts for other media investigations.

     Characterization of subsurface  gas releases can be accomplished through a
phased  monitoring approach.  An example of a strategy  for characterizing
subsurface gas releases is shown in Table 11-1.

     Development  of monitoring procedures should include determining the
specific set of subsurface gas indicators and constituents for monitoring.  Methane,
carbon dioxide, and site-specific volatile organics (e.g., vinyl chloride), can  be used
to identify the presence of subsurface gas during initial monitoring.  Subsequent
monitoring will generally involve these gases, but may also involve various other
constituents.  Development of the monitoring procedures should also  include
selection of the appropriate field and analytical methods.  Selection of these
methods will be dependent on site and unit specific conditions.

     An  initial monitoring phase  should be implemented using  screening
techniques and appropriate monitoring constituent(s). A subsurface gas migration
model can be used, as applicable, as an aid in selection of monitoring locations.
Subsequent monitoring will generally be necessary if subsurface  gas migration is
detected during the initial survey. This additional monitoring may include  a wider
range of constituents.

     Characterization of a subsurface gas release can involve a number of  tasks to
be completed throughout the course of the investigation. These tasks are  listed in
Table 11-2 with associated techniques and data outputs.
                                   11-3

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                               TABLE 11-1

   EXAMPLE STRATEGY FOR CHARACTERIZING RELEASES OF SUBSURFACE GAS1

                               INITIAL PHASE

1.    Collect and review existing information on:

         Waste
         Unit
         Environmental setting
         Contaminant releases, including inter-media transport

2.    Identify any additional information necessary to fully characterize release:

         Waste
         Unit
         Environmental setting
         Contaminant releases, including inter-media transport

3.    Develop monitoring procedures:

         Formulate conceptual model of release
         Determine monitoring program objectives
         Determine monitoring constituents and indicator parameters
         Sampling approach selection
         Sampling schedule
         Monitoring locations
         Analytical methods
         QA/QC procedures

4.    Conduct Initial Monitoring:

         Use subsurface gas migration model to estimate release dimensions (plot
         1.0 and 0.25 lower explosion limit isopleths for methane)
         Monitor ambient air and shallow boreholes around the site  using
         portable survey instruments to detect methane and other  indicator
         parameters
         Use results of above two steps to refine conceptual model and determine
         sampling  locations and  depths; conduct limited well installation
         program.  Monitor well gas and shallow soil boreholes for indicators and
         constituents
         Monitor surrounding structures (e.g., buildings and engineered conduits)
         for other indicator parameters and constituents
                    •
5.    Collect, evaluate and report results:

         Compare methane results with lower explosion limit (LED and 0.25 LEL
         and report results immediately to regulatory agency if these values are
         exceeded
                                   11-4

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                          TABLE 11-1 (Continued)

    EXAMPLE STRATEGY FOR CHARACTERIZING RELEASES OF SUBSURFACE GAS1

         Summarize and present data in appropriate format
         Determine if monitoring program objectives were met
         Determine if data are adequate to describe nature, rate and extent of
         release
         Report results to regulatory agency

                     SUBSEQUENT PHASES (If Necessary)

1.    Identify additional information necessary to characterize release:

         Modify conceptual model and identify additional information needs
         Selection of monitoring constituents for subsequent phase
         Spatial extent of subsurface gas migration
         Concentration levels of methane and other indicators and additional
         monitoring constituents
         Evaluate potential role of inter-media transport

2.    Expand initial monitoring as necessary:

         Expand subsurface gas well monitoring network
         Add or delete constituents and parameters
         Expand number of structures subject to monitoring
         Increase or decrease monitoring frequency

3.    Conduct subsequent monitoring:

         Perform expanded monitoring of area for methane and other indicator
         parameters and specific monitoring constituents
         Further monitoring of surrounding structures if warranted

4.    Collect, evaluate and report results/identify additional information necessary
     to characterize release:

         Compare monitoring results to health and environmental criteria and
         identify/respond to emergency situations and identify priority situations
         that warrant interim corrective measures - notify regulatory  agency
         immediately
         Summarize and present data in appropriate format
         Determine if monitoring program objectives were met
         Determine if data are adequate to describe nature, rate, and extent of
         release
         Identify additional information needs
         Determine need to expand monitoring system
         Evaluate potential role of inter-media transport
         Report results to regulatory agency
    The possibility for inter-media transport of contamination should be

    anticipated throughout the investigation.
                                   11-5

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                                           TABLE 11-2
                 RELEASE CHARACTERIZATION TASKS FOR SUBSURFACE GAS
       Investigatory Tasks
 Investigatory Techniques
Data Presentation Formats/Outputs
1.  Waste/Unit Characterization

       Identification of waste
       constituents of concern

       Identification of unit
       characteristics which
      . promote a subsurface gas
       release
See Sections 3, 7 and Appendix
B

See Section 7
   Listing of potential monitoring
   constituents

   Description of the unit, if
   active, and operational
   conditions concurrent with
   subsurface gas sampling
2.   Environmental Setting
    Characterization

       Definition of climate
       Definition of site-specific
       meteorological conditions
       Definition of soil conditions
       Definition of site-specific
       terrain

       Identification of subsurface
       gas migration pathways
       Identification and location
       of engineered conduits
       Identification and location
       of surrounding structures
Climate summaries for regional
National Weather Service
stations

Meteorological data from
regional National Weather
Service stations

See Section 9 (e.g., porosity,
moisture content,  organic
carbon content, etc.)

See Sections 7,9 and Appendix
A

Review of unit design and
environmental setting

Review of water level
measurements

Examination of maps,
engineering diagrams, etc.

Ground penetrating radar  (See
Appendix C)

Survey of surrounding area
   Tabular summaries for
   parameters of interest
   Tabular listing for parameters
   of interest concurrent with
   subsurface gas sampling

   Soil physical properties
   Topographic map of site area
   Identification of possible
   migration pathways

   Depth to water table
   Description of the examination
                                                                      Results of study
   Map with structures identified
3.   Release Characteriziation

       Model extent of release
       Screening evaluation of
       subsurface gas rdease
       Measurement for specific
       constituents
Gas migration model (See
Appendix 0)
Shallow borehole monitoring
and monitoring in surrounding
buildings for indicators and
specific constituent(s)

Selected gas well installation
and monitoring
                                     Monitoring in surrounding
                                     buildings	
   Estimated methane
   concentration isopleths for LEI
   and 0.25 LEL

   Listing of concentrations levels
   Tables of concentrations

   Detailed assessment of extent
   and magnitude of releases

   Tables of concentrations
                                               11-6

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     As monitoring data become available, both within and at the conclusion of
discrete investigation phases,  it should  be reported to the regulatory agency as
directed. The regulatory agency will compare the monitoring  data to applicable
health and environmental criteria to determine the need for (1) interim corrective
measures; and/or (2) a Corrective Measures Study.  In addition, the  regulatory
agency will evaluate  the monitoring data with respect to  adequacy and
completeness to  determine the need for any additional monitoring efforts. The
health and environmental criteria and a general discussion of how the regulatory
agency will apply them are supplied in Section 8.  A flow diagram illustrating RFI
decision points is provided in Section 3 (See Figure 3-2).

     Notwithstanding the above process, the owner or operator has a  continuing
responsibility to identify and respond to emergency situations and to define priority
situations that may warrant interim corrective measures. For these situations, the
owner or operator is directed to obtain and follow the RCRA Contingency Plan
requirements under 40 CFR Part 264, Subpart D.

11.2.2         Inter-media Transport

     Contaminated ground water and contaminated soil can result in  releases of
gaseous constituents via subsurface migration, primarily due to volatilization of
organic  constituents.  Information collected from ground-water and soil
investigations may provide useful input data for the subsurface gas pathway
characterization.  It may also be more efficient  to jointly conduct monitoring
programs for such related media (e.g., concurrent ground water and subsurface gas
migration monitoring programs).

     Subsurface gas migration also has the potential for inter-media transport (e.g.,
transfer of contamination from subsurface gas to the soil and air media).  Therefore,
information  from the subsurface gas migration investigation will also provide
useful input for assessing soil contamination and potential air emissions.

11.3 Characterization of the Contaminant Source and the Environmental Setting

     The type of waste managed in the unit will determine the conditions under
which the gas can be generated, and the type of unit and characteristics of the
                                   11-7

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surrounding environment (e.g., soil type and organic content) establishes potential
migration pathways.  Units which may be of particular concern for subsurface gas
releases contain putrescible organic material and generally include below grade
landfills,  units closed  as landfills (e.g., surface impoundments), and underground
tanks. These types of  units may have waste deposited or stored at such depths as to
allow for subsurface gas generation by volatilization or decomposition of organic
wastes and subsequent migration (see Figures 11-1 and 11-2).

     The nature and extent of contamination  are  affected by environmental
processes such as dispersion, diffusion, and degradation, that can occur before and
after the release occurred.  Factors that should be considered include soil physical
and chemical  properties, subsurface geology  and hydrology, and in some cases,
climatic or meteorologic patterns.

     The principle components of "landfill gas" are generally methane and carbon
dioxide produced by  the anaerobic decomposition of organic materials in  wastes.
Methane is of  particular concern due to its explosive/flammable  properties,
although other gases of concern  could be present.  The presence of  these other
gases in a unit is  primarily  dependent upon  the types of wastes managed, the
volatilities of the waste  constituents, temperature,  and possible  chemical
interactions within the waste. Previous studies (e.g., Hazardous Pollutants in Class II
Landfills. 1986, South Coast Air Quality Management  District, El Monte, California
and U.S. EPA.  1985. Technical Guidance for Corrective Measures - Subsurface Gas.
Washington, O.C.  20460) have indicated that the predominant components of
landfill gas are methane and carbon dioxide.  Methane is generally of greater
concentration, however, carbon dioxide levels are generally also high, especially
during  the  early stages of the methane generation  process.  Concentrations of
subsurface gas constituents which may accompany methane/carbon dioxide are
generally several  orders of magnitude less than methane. In some cases (e.g.,
associated with acidic refinery wastes) sulfur dioxide may be the primary subsurface
gas.
                                   11-8

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11.3.1         Waste Characterization

11.3.1.1       Decomposition Processes

     Subsurface  gas generation occurs  by biological, chemical, and physical
decomposition of disposed or stored wastes. Waste characteristics usually affect the
rate of decomposition. The owner or operator should  review unit-specific
information (waste receipts, waste composition surveys, and any other records of
wastes managed) to determine waste type, quantities, location, dates of disposal,
waste moisture content, organic content, etc.

     The three decomposition processes known to occur in the  production  of
subsurface gases are  biological decomposition, chemical decomposition, and
physical decomposition. These are discussed below:

11.3.1.1.1      Biological Decomposition

     The extent of biological decomposition and subsequent gas generation from a
given waste is related to the type of unit. Biological decomposition, due primarily
to anaerobic microbial degradation, is significant in most landfills and units closed
as landfills which contain organic wastes.  Generally, the amount of gas generated
in a landfill is directly related to the amount of organic matter present.

     Organic wastes such as food, sewage sludges, and garden wastes decompose
rapidly, resulting in gas generation shortly after burial, with  high initial yields.
Much slower decomposing organic wastes include paper, cardboard, wood, leather,
some textiles and several other organic components. Inorganic and inert materials
such as plastics, man-made textiles, glass, ceramics, metals, ash, and  rock do not
contribute to biological gas production. At units closed as landfills, waste types that
undergo biological decomposition  might include bulk  organic wastes, food
processing sludges, treatment plant sludges, and composting waste.

     Waste characteristics can increase or decrease the rate  of biological
decomposition.  Factors that enhance anaerobic decomposition  include   high
moisture content, adequate buffer capacity and neutral pH, sufficient nutrients
(nitrogen and  phosphorus), and moderate temperatures. Characteristics that
                                  11-11

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generally decrease biological decomposition include the presence of acidic or basic
pH, sulfur, soluble metals and other microbial toxicants.  The owner or operator
should review the waste characteristic information to document if  biological
decomposition and subsequent gas generation may be occurring.

     Under anaerobic  conditions,  organic wastes  are  primarily converted  by
microbial action into carbon dioxide and methane.  Trace amounts of  hydrogen,
ammonia, aromatic hydrocarbons, halogenated organics, and hydrogen sulfide may
also be present. With regard to subsurface migration, the primary gases  of concern
are methane  (because of its explosive properties) and constituents that may  be
present in amounts hazardous to human health or the environment.

11.3.1.1.2      Chemical Decomposition

     Gas production by chemical reaction can result from the disposal or storage of
incompatible  wastes. Reactive or ignitable wastes can produce explosive or heat-
producing reactions, resulting in rapid production of gases, and increased pressures
and temperatures. Under acidic conditions, a strong oxidizing agent can react with
organic wastes to produce carbon dioxide and ammonia which can migrate from
the unit, possibly providing a transport mechanism for other gaseous components.

     Under typical  conditions, gas production from chemical reactions  is not
expected to occur at landfills or units closed as landfills.  However, volatile liquids
stored in underground tanks may have a significant potential to create a release by
chemical  reaction.   Good waste management practices, particularly the proper
design and operation (e.g., pressure-relief valves  and leak detection systems) of
underground tanks can minimize the potential for gas release.

11.3.1.1.3      Physical Decomposition

     Physical  decomposition phenomena include  volatilization and combustion.
Volatilization can result in subsurface gas generation  in underground tanks if there
is a leak or puncture. The greater a compound's vapor pressure, the greater will be
its potential to volatilize. Maintenance of underground tanks (e.g.,  pressure-relief
valves and leak detection systems) can minimize volatilization.
                                   11-12

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     Combustion processes (e.g., underground  fires) sometimes occur at active
landfills and result in subsurface gas release.  Combustion can convert wastes to
byproducts such as carbon dioxide, carbon monoxide, and trace toxic components.
Combustion  processes can also accelerate chemical  reaction rates and biological
decomposition, creating greater potential for future subsurface  gas generation and
subsequent release.  The owner or operator should  review  facility records to
determine if combustion has occurred and when.

11.3.1.2       Presence of Constituents

     Subsurface gas generation and migration of methane is of concern because of
its explosive properties. In addition, methane and other decomposition gases can
facilitate the migration of volatile organic  constituents that may be of concern
because of potential  toxic effects.  Subsurface  gas migration  due to leaks from
subsurface tanks  may also  be associated with  a  variety of volatile organic
constituents.

     In determining the nature of a release, it may be necessary to determine the
specific waste constituents in the unit. Two means of obtaining these data are:

     (1)   Review of facility records.  Review of facility records may not provide
          adequate information (e.g., constituent concentrations) for RFI purposes.
          For example, facility records of waste handled  in  the unit may only
          indicate generic waste information.   Knowledge of individual
          constituents and concentrations is generally needed  for purposes of the
          RFI.

     (2)   Conducting waste sampling and analysis.  When facility records do not
          indicate the specific constituents of the waste which are  likely to  be
          released and may  migrate as subsurface  gas, direct waste
          characterization may be necessary.  This effort, aimed at providing
          compound  specific data on the waste, can be focused in terms of the
          constituents for which analysis should be performed through review of
          the waste types in the unit. In some cases, however, the generic waste
          description (e.g., flammable liquids) will not give an indication of the
                                  11-13

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          specific constituents present, and analysis for all of the constituents of
          concern as gaseous releases (See Appendix B, List 2) may be required.

     Additional guidance on identification of monitoring constituents is presented
in Section 3.6. Section 7 provides guidance on waste characterization.

11.3.1.3       Concentration

     Determination of concentrations of the constituents of concern in the waste
may indicate those constituents which  are of prime concern for  monitoring. The
concentration of a constituent in a waste (in conjunction with its physical/chemical
properties and total quantity) provides an indication of the gross quantity of
material that may be released in the gaseous form.

11.3.1.4       Other Factors

     In addition to the factors described above, determination of the potential for
volatilization of the waste constituents will help determine if they may be released.
The parameters most important when assessing the potential for volatilization of a
constituent include the following:

     •    Water  solubility.   The solubility in water indicates the maximum
          concentration at which a constituent can dissolve in water at  a  given
          temperature.  This value can be used to estimate the distribution of a
          constituent between the dissolved aqueous phase in the unit and the
          undissolved solid or immiscible liquid phase.  Considered in combination
          with the constituent's vapor pressure, it can provide a relative assessment
          of the potential for volatilization.

     •    Vapor  pressure.   Vapor pressure refers  to the  pressure of vapor in
          equilibrium with  a pure liquid.   It is  best used in a relative sense;
          constituents with high vapor pressures are more likely to  be released in
          the gaseous form  than those with low vapor pressues, depending on
          other factors such as relative solubility and concentration (i.e.,  at high
          concentrations releases can occur even though a constituent's vapor
          pressure is relatively low).
                                   11-14

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     •    Octanol/water  partition coefficient.  The  octanol/water partition
          coefficient indicates the tendency of an organic constituent to sorb to
          organic components of the soil or waste matrices of a unit. Constituents
          with high octanol/water partition coefficients will adsorb readily to
          organic  carbon, rather than volatilizing to the atmosphere.  This  is
          particularly important in landfills and  land treatment units, where high
          organic carbon contents in soils or cover material can significantly reduce
          the release potential of vapor phase constituents.

     •    Partial pressure.  For constituents in a mixture, particularly in  a solid
          matrix, the partial pressure of a constituent will be more significant than
          the pure vapor pressure. In general, the greater the partial pressure, the
          greater the potential for release.  Partial pressures will be difficult to
          obtain. However, when waste characterization data is available, partial
          pressures can be  estimated using  methods commonly found in
          engineering and environmental science handbooks.

     •    Henry's Law constant.  Henry's law constant is the ratio of the vapor
          pressure of a constituent and its aqueous solubility (at equilibrium).  It
          can be used to assess the relative ease with which the compound may be
          removed  from the aqueous phase via vaporization. It is accurate only
          when used in evaluating low concentration wastes in aqueous solution.
          Thus it will be most  useful  when  the unit being assessed  is a surface
          impoundment  or tank containing dilute wastewaters.   As the value
          increases, the potential for significant vaporization increases, and when
          it is greater than 0.001, rapid volatilization will generally occur.

     •    Raoult's Law.  Raoult's Law can be used to  predict  releases from
          concentrated aqueous solutions (i.e., solutions  over 10% solute). This
          will be most useful when the unit contains concentrated waste streams.

11.3.2          Unit Characterization

     Unit design (e.g., waste depth, unit configuration, and cover materials) also
affects gas generation.  Generally, the amount of gas  generated  increases with
                                   11-15

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landfill volume and often with landfill depth. Deeper landfills have a proportionally
larger anaerobic zone, greater insulation and compaction, and are more likely to
confine gas production. Deeper landfills, such as trench fills or canyon fills, can trap
gases along confining sidewalls and bottom bedrock  or ground  water.  Daily,
interim, and final cover soils can confine gases within the landfill. This is particularly
true for  low permeability cover  soils (e.g., clays) which impede vertical  gas
migration.  Conversely, mounds  or shallow landfills have large surface areas
through which gases can vent more easily.

     Unit operations, such as methods and procedures  used  to segregate and
isolate inert wastes, to prevent moisture infiltration, to compact and  increase the
density of the waste,  and to minimize or prevent mixing of waste types, can affect
resultant releases of  subsurface gases. Daily covering of the unit  may  inhibit
decomposition and thus gas generation and subsequent migration.

     Certain units have a high potential for allowing the  movement of subsurface
gas. These units are those that receive and/or store large volumes of decomposable
wastes, volatile  organic liquids, or highly reactive materials.  Subsurface  gas
migration may occur especially when major portions of a land-based unit are below
grade. Gas generated by these units can migrate vertically and laterally from the
unit, following the path of  least resistance.

     Some units are operated above grade or in relatively shallow soils (e.g., surface
impoundments, land  treatment units). The potential for subsurface gas migration
from such units is  usually  low.  Gases generated by such units will generally be
vented to the atmosphere unless prevented by a  natural barrier (e.g.,  frozen
ground) or an engineered barrier (e.g., soil cover).

     Information on  unit operations will therefore  be  important in assessing the
potential for subsurface gas migration. Unit operational data may also be required
concurrent with any subsurface gas sampling activities.  It is particularly important
to obtain operational data on any  gas collection system in use at the time of
sampling. These  gas collection systems can significantly  affect subsurface  gas
migration rates, patterns and constituent concentration levels.
                                   11-16

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     Generally, the units that  pose the greatest potential for subsurface gas
migration include landfills, sites closed as landfills, and underground storage tanks.
These are discussed below.

11.3.2.1       Landfills

     Gas generated in landfills can vent vertically to the atmosphere and/or migrate
horizontally through permeable soil, as shown in Figure 11-1. Closure of the landfill
or periodic covering of cells or lifts with impermeable caps may impede the vertical
movement of the gases,  forcing them to migrate laterally  from the unit.  Gas
migration laterally  through the subsurface (e.g., through underground utility line
channels or sand lenses) may accumulate in structures on or off the facility property.

11.3.2.2       Units Closed as Landfills

     Gas generation and subsequent migration is likely to occur at  units closed  as
landfills containing organic wastes, as  previously discussed.  Although surface
impoundments and waste piles may be closed as landfills, they tend to produce less
gas than  landfills because they generally contain  smaller quantities  of
decomposable and  volatile wastes and are generally at shallow depths. Closure  of
such units with an impermeable cover will, however, increase the potential for
lateral gas movement and accumulation in onsite and offsite structures (see Figure
11-2).

11.3.2.3       Underground Tanks

     Subsurface gas release and subsequent  migration  may occur if an
underground tank is leaking. Underground tanks frequently contain  volatile liquids
that could enter the unsaturated zone should a leak occur (see Figure 11-2).

11.3.3         Characterization of the Environmental Setting

11.3.3.1       Natural and Engineered Barriers

     Subsurface conditions at the site should be evaluated to determine likely gas
migration routes. Due to the inherent mobility of gases, special attention must be
                                   11-17

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paid to zones of high permeability created by man-made, biological, and physical
weathering action.  These zones  include backfill around pipes, animal burrows,
solution channels, sand and/or gravel lenses, desiccation cracks, and jointing in
bedrock.  The presence of dead rodents, snakes and other burrowing animals is
usually a good indication of a potential subsurface gas pathway.

     Natural and engineered barriers can also affect gas migration, generally by
inhibiting migration pathways. Natural barriers to gas migration include surface
water, ground water, and geologic formations.  Engineered barriers include walls,
onsite structures, underground structures, caps, liners, and other design features.
On the other hand, preferred pathways for subsurface gas migration may result
from previous  underground construction (e.g., underground utility lines) that can
facilitate gas flow.  Natural and engineered barriers are discussed in more detail
below.

11.3.3.1.1       Natural Barriers

     Surface water, ground water, and saturated soils can slow down or control the
direction of subsurface gas migration. Gases encountering these barriers will follow
the pathway of least resistance, usually through unsaturated porous soil.

     Geologic barriers can also impede or control the  route of subsurface gas
migration. For example, soil type  is an important factor in gas migration.  Gravels
and sands allow gas to migrate readily, particularly sand/gravel lenses, while clayey
gravels and sandy and organic clays tend to impede gas movement. Underground
utility trenches, backfill with granular materials, filled-in mine shafts, and tunnels or
natural caverns can also serve to channel subsurface gas flow.  Climatic conditions
such as precipitation or freezing can reduce the porosity of surface soils, thereby
impeding upward gas movement.  Information regarding characterization of soils is
provided in Section 9 (Soils).

11.3.3.1.2      Engineered Barriers

     Landfills and units closed as landfills may use caps and liners to prevent
moisture  infiltration  and leachate  percolation to ground water.   Caps can
contribute to horizontal gas movement when upward migration to the surface is
                                   11-18

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restricted (as shown in Figure 11-1).  Liners tend to impede lateral migration into
the surrounding unsaturated soils. The owner or operator should evaluate cap/liner
systems (type, age, location, etc.) to determine potential gas migration pathways.
Similar to liners, slurry walls used to border landfill units can retard lateral gas
movement. With respect to underground tanks, caps and liners are not typically
used.  Tanks are often placed into soils  with sand or gravel backfill during
installation, followed by paving on the surface.  Thus, any escaping gases from a
leaking underground tank may migrate laterally along the path of least resistance
adjacent to the units.  The owner or operator should evaluate tank construction,
and age, integrity, and location.

11.3.3.2       Climate and Meteorological Conditions

     The climate of the site should be defined to provide background information
for assessing the potential  for subsurface  gas migration, identifying migration
pathways, and designing the subsurface gas migration monitoring system. Climatic
information, on an annual and monthly or seasonal basis, should be collected for
the following parameters:

     •    Temperature means/extremes and frost  season (which indicates the
          potential for impeding the upward migration of the subsurface gas, thus
          confining the gas within the ground);

     •    Precipitation means and snowfall (which indicates the potential  for
          "trapping" as well as an indication of soil moisture conditions which
          affect subsurface gas migration); and

     •    Atmospheric pressure means (which indicates the potential for gaseous
          releases to ambient air from a unit of concern).

     The primary source of climate information for the Unites States is the National
Climatic Data Center (Asheville, NC). The National Climatic Data Center can provide
climate summaries for the National Weather Service station nearest to the site of
interest. Standard references for climatic information also include the following:
                                   11-19

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     Local  Climatoloqical Data - Annual Summaries with Comparative  Data.
     published annually by the National Climatic Data Center;

     Climates of the States, National Climatic Data Center; and

     Weather Atlas of the United States. National Climatic Data Center.

     Meteorological data for the above parameters should also be obtained
concurrently with subsurface gas sampling activities. As previously discussed, these
meteorological  conditions can influence subsurface gas migration rates, patterns
and concentration levels.  Therefore, these data are necessary to properly interpret
subsurface gas sampling data. Concurrent meteorological data for the sampling
period can be obtained  from the National Climatic Data Center for National
Weather Service stations  representative of the site area.  In some cases, onsite
meteorological data will also be available from an existing monitoring program or
associated with an RFI characterization of the air media (See Section 12).

11.3.3.3        Receptors

     Receptor information needed to assess potential subsurface gas exposures
includes the identification and location of surrounding buildings and potential
sensitive  receptors (e.g., residences,  nursing homes, hospitals, schools, etc.).  This
information should also be considered in developing the monitoring  procedures.
Additional discussion of potential receptors is provided in Section 2.

11.4 Design of a Monitoring Program to Characterize Releases

     Existing data should help to indicate  which units have the potential to
generate methane or other gases or constituents of concern. Such information can
be found in construction or design documents, permit  and inspection reports,
records of waste disposal, unit design and operation records, and documentation of
past releases.

     Units of concern should be identified on the facility's topographic map. The
location and area! extent of these units can be determined from historical records,
aerial photographs,  or field surveys.  The depths and dimensions of underground
                                   11-20

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structures, locations of surrounding buildings, and waste-related  information
should be identified.  Waste management records may provide information on
waste types, quantities  managed, location of waste units, and dates of waste
disposal. Waste receipts, waste composition surveys, and records of waste types
(e.g., municipal refuse, bulk liquids, sludges, contaminated soils, industrial process
wastes or inert materials) should be reviewed. For underground tanks, liquid waste
compositions, quantities, and physical properties should be determined.

     Review of unit design and operation records may  provide background
information on units of concern. These records may include  engineering design
plans, inspection records, operations logs, damage or nuisance litigation, and
routine monitorng data. Also, for landfills and units closed as landfills, data may
include the presence and thickness of  a  liner, ground-water elevations, waste
moisture contents, type and amount of daily cover, records of subsurface fires, and
in-place leachate and/or gas collection  systems.   Historical  information on
underground tank integrity  may be contained  in construction  and monitoring
records. Records of past releases may provide information on  problems, corrective
measures, and controls initiated.

     The owner or operator should review records of  subsurface conditions to
determine potential migration pathways. Aerial photographs or field observations
should identify surface water locations.  Infrared aerial photography or geological
surveys  from the USGS can be used as preliminary aids to  identify subsurface
geologic features and  ground-water  location.  In addition to obtaining and
reviewing  existing information, a field investigation may be necessary to confirm
the location of natural barriers.  The local soil conservation service will often have
information describing soil characteristics (e.g., soil type, permeability, particle size)
or a site specific investigation may need to be conducted.  (Soil information sources
are discussed in  Section 9).  Climatic  summaries  (e.g., temperature, rainfall,
snowfall) can be obtained from th'e National Climatic Data Center for the National
Weather Service  station nearest to the  site  of interest (Specific climatic data
references  are  cited in Section  12).  Historical records of the site  (prior use,
construction, etc.) should also  be reviewed to  identify  any factors affecting  gas
migration  routes.  The monitoring program should also address any engineered
structures affecting the migration pathway.
                                   11-21

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     In addition to the above, the owner or operator should examine the units and
surrounding area for signs of settlement, erosion, cracking of covers, stressed or
dead vegetation, dead  rodents,  snakes and other  burrowing  animals,
contamination of surface waters, odors, elevated temperatures in any existing
monitoring wells, and for venting of smoke or gases. The condition of any existing
gas monitoring systems and containment or collection systems should also be
examined, as well as any structural defects in tanks or liners. Any overflow/alarm
shut off systems, subsurface leak detection  systems, secondary containment
structures (e.g., concrete pads, dikes or curbs)  or other.safety systems for  early
detection of potential gas releases should be checked.

     By reviewing all existing information, the owner or operator should be able to
develop a conceptual model of the release and design a monitoring program to
characterize the release.

11.4.1         Objectives of the Monitoring Program

     Characterization of subsurface gas releases can be accomplished  through a
phased monitoring approach. The objective of initial monitoring should be to verify
suspected releases, if necessary, or to begin  characterizing  known releases.
Monitoring should include methane and other indicators such as carbon  dioxide, as
well as individual constituents if  appropriate.  If initial monitoring  verifies a
suspected release, the owner or operator should  expand the monitoring program to
determine  the vertical and horizontal extent of the  release, as well as the
concentrations of all constituents of concern in the release.
                          *

     The full extent of the release can be  determined through additional shallow
borehole and  gas monitoring well locations.  The  goal of this further
characterization will be to identify the boundary of gas migration, including the
leading edge of the migration.

     A great deal of the effort conducted during any subsequent phase may involve
investigating anomalous areas where subsurface  conditions are non-uniform. In
these situations, the gas migration characteristics may differ from surrounding
areas.  Consequently, non-random  sampling techniques  are  generally  most
appropriate to monitor these areas.  The location of additional gas wells and
                                  11-22

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shallow boreholes at the sites of subsurface anomalies will provide information
regarding the migration pattern around these anomalous areas.  Also, because gas
well installation may be conducted only to a limited  extent  under  the initial
monitoring phase, additional wells may need to be installed.

     The monitoring program should also address the selection of constituents of
concern, sampling frequency and duration, and the monitoring system design.

11.4.2    Monitoring Constituents and Indicator Parameters

     As discussed above, the  number and identity of potential subsurface gas
constituents will vary on a site-specific basis.  Constituents to be included for
monitoring depends primarily on the type of wastes received. For example, if an
underground storage tank contains specific constituents, they should be  considered
during subsurface gas monitoring activities. The guidance provided in Section 3 and
the lists provided in Appendix  B should  be used to determine a select set of
constituents and indicator parameters for subsurface gas monitoring.

     Methane should be used  as the primary indicator of subsurface gas migration
during the initial and any subsequent monitoring phases. Supplemental indicators
(e.g., carbon dioxide and sulfur dioxide) may also be used  as appropriate.  Field
screening equipment should be used to detect the presence of methane  in terms of
the lower explosive limit (LEL).  The LEL for methane is 5 percent by volume, which is
equivalent to 50,000 ppm.  Individual constituents should also be monitored.  In
addition, oxygen  detectors and nitrogen analyses can be  used to confirm the
representativeness of all subsurface gas well samples obtained.  (The presence of
oxygen and nitrogen in well samples indicates the intrusion of ambient air into the
well during monitoring.  Samples containing ambient air would result in  an
underestimate  of methane and other indicators as well as specific monitoring
constituents.)

     Methane concentrations observed during the initial monitoring phase which
exceed the  LEL at the  property boundary or 0.25 the LEL within surrounding
structures, would warrant initiation of subsequent monitoring phases and, possibly,
consideration of interim corrective measures.  Similarly, the presence of individual
constituents would also trigger the need for subsequent monitoring phases.
                                   11-23

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     Regardless of the degree to which monitoring constituents can be limited by
site-specific data, analyses for all constituents identified as applicable in Appendix B
(List 2) will generally be necessary for the subsurface gas medium at selected
monitoring locations.

11.4.3         Monitoring Schedule

     A monitoring schedule should be established and described in the RFI Work
Plan.  This schedule  should describe the sampling frequency, the duration of the
sampling effort, and  the conditions under which sampling should occur.

     During initial monitoring, bar punch probe (See Section 11-6) monitoring for
methane and appropriate constituents should be conducted at least twice over the
course of one week.  Monitoring the wells for methane and constituents should be
conducted at least once a week for one month. (Subsurface gas wells should not be
monitored for at least 24 hours after installation to allow time for equilibration.)
Surrounding buildings should be monitored at least once a week for one month.

     During any subsequent monitoring phases, more extensive sampling may be
needed to adequately characterize the nature and extent of the release. Monitoring
of wells and buildings for methane and constituents should be conducted every
other day for a two  week  period to account for daily fluctuations  in  gas
concentrations.

     Conditions for  sampling should also be defined. Sampling should generally
not be performed if conditions conducive to decreasing gas concentrations are
present (e.g., subsurface gas pressure at less than atmospheric pressure). In these
cases, sampling  should  be  delayed until  such conditions pass.  Subsurface  gas
pressures have  a diurnal cycle and are generally  at  a  maximum during  the
afternoon.
                                  11-24

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11.4.4         Monitoring Locations

11.4.4.1       Shallow Borehole Monitoring

     Areas identified for subsurface gas monitoring as a result of characterization
of the contaminant source and the environmental setting should be investigated for
concentrations of methane and constituents during the initial monitoring phase.
Shallow borehole monitoring using a bar punch probe method or equivalent (See
Section 11.6) is recommended. The bar punch is simply a steel or metal bar which is
hand-driven or hammered to depths of 6 feet. Once this hole is made it is covered
with a stopper or seal to confine the headspace in the hole.  The hole should  be
allowed to equilibrate for up to an hour prior to sampling to provide sufficient time
for subsurface gas to replace the  air in the hole.  The ease of installation of bar
punch holes and the ability to obtain  real-time direct measurements from  field
survey instruments combine to make this task a relatively simple operation.  It
should be recognized, however, that  shallow borehole monitoring  is a rapid
screening method and therefore has its  limitations. Two major limitations are that
negative findings cannot assure the absence of a release at a greater depth and that
air intrusions can dilute the sampling readings. See also Sections 9 (Soil) and  10
(Ground Water) for additional information.

     The number of locations to monitor will vary from site to site. However, due
to the ease of this operation, it is recommended that many locations be surveyed
during the initial monitoring phase. Selection of locations along the perimeter of
the unit of concern and at intervals of approximately 100 feet is an adequate initial
approach. Individual site conditions and anomalies should be considered  to
determine whether the number of sampling locations should be increased  or
decreased. A large  site with homogeneous subsurface conditions could require
fewer sampling locations by increasing  the distance between sampling points.  A
site with many subsurface anomalies, such as engineered barriers or varying soil
strata, would require a greater number of sampling locations. In general, sampling
locations should be established where conditions are conducive to gas migration,
such  as in  sands, gravels and porous soils, and near engineered conduits (e.g.,
underground utility  lines). The appropriate precautions should be taken when
sampling near engineered conduits so as not to damage such property and to assure
the safety of the investigative team and others.
                                  11-25

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     The distance from the unit at which to sample can best be determined through
consideration of site-specific characteristics (e.g., soil conditions), and can be aided
by the use of the gas concentration contour map generated by the predictive model
described in Appendix D. The shallow borehole survey should be fairly extensive,
ranging from sampling locations very near the unit to locations at the property
boundary and beyond.

11.4.4.2        Gas Monitoring Wells

     Gas monitoring wells (See Section 11.6) should be installed to obtain data on
subsurface gas concentrations at depths greater than the depth accessible  with a
bar punch probe. Wells should be installed to a depth equal to that of the unit.
Multiple probe depths may be installed at a single location as illustrated in Figure
11-3.  Where buried material is fairly shallow (e.g., < 10-feet), single depth gas
monitoring probes may  be sufficient.  When buried material exceeds this depth
below ground, multiple depth probes should be installed.

     The location and depth of gas  monitoring  wells should be  based on the
presence of highly permeable zones (e.g., dry sand or gravel), alignment with offsite
structures, proximity of the waste deposit, areas where there is dead or unhealthy
vegetation (that may be due to gas migration), and any engineered channels which
would promote the  migration of a subsurface gas release (e.g., utility lines).  This
information should  be gathered during a review of subsurface conditions, as
discussed previously. At a minimum, a monitoring well should be installed at the
location(s) of expected maximum  concentration(s), as determined or estimated
during the initial monitoring phase.

     Gas monitoring well installation usually requires the use of a drilling rig or
power auger.  Once a borehole has  been drilled to the desired depth, the gas
monitoring  probes  can  be installed as illustrated in Figure  11-3.  Additional
information concerning  the  installation of subsurface gas monitoring wells is
provided in Section  10 (Ground Water) and in Guidance Manual for the
Classification of Solid Waste Disposal Facilities NTIS PB81-218505 (U.S. EPA, 1981).
                                   11-26

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                  •1/2" DIA SCR 40
                   PVC  PIPE
1/8" DIA.
PERFORATIONS
                      FIBERGLASS
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MONITORING PROBE  DETAIL
          MONITORING
          PROBE
                                  1/2" DIA. SCH 40
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                                                            BACKFILL
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                                                        PLUG
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                                  1  PEA GRAVEL
                                                       SOIL BACKFILL


                                                        '- 2' 3ENTON17
                                                       PLUG

                                                       SOIL BACKFILL
                                                       2'  PEA GRAVEL
       Figure 11-3. Schematic of a Deep Subsurface Gas Monitoring Well
                               11-27

-------
     Equilibration times of at least 24 hours should be allowed prior to collection of
subsurface gas samples for analysis after well installation and between subsequent
collection periods.  Individual site characteristics or anomalies which can create
significantly different subsurface conditions will  require an increased number of
wells to sufficiently determine the presence of gas migration.  For example, if the
predominant soil strata along one side of a unit changes from sandy clay to gravel, a
well should be installed in both of these areas. Also, if the amount of gas producing
waste buried at the site varies greatly from one area  to another, gas monitoring
wells should be installed near each area of concern.

     Subsurface gas monitoring may be done concurrently with ground-water
investigations (Section 10), because results of subsurface gas monitoring may
provide useful information for identifying the overall  extent of any ground-water
contamination.

11.4.4.3  Monitoring in Buildings

     Monitoring should also be conducted in surrounding structures near the areas
of concern, since methane and  other subsurface gas constituents migrating through
the soil can accummulate in confined areas. Use of an explosimeter for methane is
the recommended monitoring technique (See Section 11.6).

     Sampling should be conducted at times when the dilution of the indoor air is
minimized and  the concentration of soil  gas is expected to be at its highest
concentration. Optimal sampling conditions would be after the building has been
closed for the weekend or overnight and when the soil surface outside the building
and over the unit of concern has been wet or frozen for several days.  These
conditions will maximize the potential  for lateral migration of gas into buildings
rather than  vtrtically into the ambient air.  Recommended sampling locations
within the building include basements, crawl spaces, and around subsurface utility
lines such as sewer or electrical connections. Access conduits such as manholes or
meter boxes are good sampling locations for water, sewer, or gas main connections.
Methane and, if appropriate, individual constituents should be monitored for.

     The threat of explosion  from accumulation of methane within a building
makes this monitoring activity  important as well as dangerous. The monitoring of
                                  11-28

-------
gas concentrations within buildings is a simple process involving a walk through
inspection of areas with portable field instruments (e.g., explosimiter).  Such
measurements should begin during the initial monitoring phase. The importance of
identifying potential releases to  buildings warrants  a complete inspection of all
suspect areas. The inherent danger during these investigatons warrants adequate
health and safety procedures (See Section 6).

     If significant concentrations of methane or constituents are measured in
surrounding structures during initial monitoring, subsequent monitoring may need
to be expanded to include buildings at greater distances from the unit(s) of concern
and  to include additional constituents of concern.  In addition, interim corrective
measures should be considered.

     Background indoor air quality levels may be  accounted  for  during the
collection and evaluation of the in-building sampling  data. Background levels can
be accounted for by identifying potential indoor air emission sources  (e.g., use of
natural gas as a fuel or wood paneling which has the potential for formaldehyde
emissions). Further guidance on this subject is presented in the following reference:

     U.S. EPA.  1983. Guidelines for Monitoring Indoor Air Quality. EPA- 600/1-4
     83-046.  NTIS  PB83-264465.  Office of Research and Development.
     Washington, D.C. 20460.

11.4.4.4   Use of Predictive Models

     In addition to monitoring  potential gas releases  using  portable survey
instruments, the owner or operator should consider the use of predictive models to
estimate the configuration and concentration of gas releases.  A subsurface gas
predictive model has been developed by EPA to estimate methane gas migration
from sanitary landfills.  This model  is based on site soil conditions, waste-related
data, and other environmental factors.

     As part of the initial monitoring phase, the model provided in Appendix D (or
another appropriate predictive model after consultation with the  regulatory
agency), should be used to estimate the extent of subsurface gas migration. Results
from this model can be used in determining appropriate monitoring locations. The
                                   11-29

-------
methane  gas migration model presented  in  Appendix D yields a  methane
concentration isopleth map of a release. The LEL and 0.25 LEL isopleths for methane
should be mapped for the RFI when appropriate. Because predictive models may
not be sensitive to relevant site conditions, however, model results should be used
cautiously for the monitoring program design and to supplement actual field data.

11.5 Data Presentation

     Subsurface gas data collected during the RFI should be presented in formats
that clearly define the composition and extent of the release. The use of tables and
graphs is highly recommended.  Section  5.2 provides a detailed discussion of data
presentation methods.

11.5.1     Waste and Unit Characterization

     Waste and unit characteristics should be presented as:

     •    Tables of waste constitutents and concentrations;

     •    Tables  of relevant physical  and  chemical  properties of waste and
          potential contaminants;

     •    Narrative description of unit dimensions, operations, etc.; and

     •    Topographical map and plan drawings of facility and surrounding areas.

11.5.2     Environmental Setting Characterization

     Environmental characteristics should be presented as follows:

     •    Tabular summaries of annual and monthly or seasonal  relevant climatic
          information (e.g., temperature, precipitation);

     •    Narratives and maps of soil and relevant hydrogeplogical characteristics
          such as porosity, organic matter content, and depth to ground water;
                                   11-30

-------
     •    Maps showing location of natural or man-made engineering barriers and
          likely migration routes; and

     •    Maps of geologic material  at the site identifying  the thickness, depth,
          and textures of soils, and the presence of saturated regions and other
          hydrogeological features.

11.5.3     Characterization of the Release

     In general, release data should  be initially presented  in tabular form. To
facilitate interpretation, graphs of concentrations of individual constituents plotted
against distance from the unit should  be used to identify migration pathways and
areas of elevated concentrations. Concentration isopleth maps can also be drawn to
identify the direction, depths, and distances of gas migration, and concentrations of
constituents of concern. Specific examples of these and other data presentation
methods are provided in Section 5. Methane concentrations should be presented in
terms of  the  LEL and 0.25  LEL isopleths.  Specific monitoring constituent
concentrations should also be presented.

11.6 Field Methods

     Field methods for subsurface gas investigations involve sample collection and
analysis.  Sample collection  methods  are discussed to summarize  the  monitoring
techniques described above. Because subsurface gas monitoring  is similar to air
monitoring, the available methods for the collection and analysis of subsurface gas
samples are presented here only in tabular format with further discussion in the air
section of this document (Section  12).  Tables 11-3 through 11-5 summarize various
methodologies available to  collect and analyze air samples. These methodologies
range from real-time analyzers (e.g., methane explosimeters) to the collection  of
organic vapors on sorbents or whole air samples with subsequent  laboratory
analysis.

     A portable gas chromatograph with  a flame  ionization detector (calibrated
with reference to methane) can be used to measure methane concentrations in the
field. Methane explosimeters (based on the principle of thermal conductivity) are
                                   11-31

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                                  TABLE 11-3
        SUMMARY OF SELECTED ONSITE ORGANIC SCREENING METHODOLOGIES
   Instrument or
      detector
    Measurable
    parameters
    Low range of
     detection
     Comments
Century Series 100
   or AID Model 500
   (survey mode)
Volatile organic
species
Low ppm
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Detector (FID)
GfG Gas Etechonics
(Methanometer)
Methane explosion
potential
Low ppm
Sensitive to methane
National Mine Service
Company
Methane explosion
potential
Low ppm
Sensitive to methane
Mine Safety
Appliances, Inc.
Methane explosion
potential
Low ppm
Sensitive to methane
                                    11-32

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-------
also available and provide direct readings of LEL levels and/or percent methane
present by volume.

     Table 11-3 provides a  list of organic screening methodologies suited for
detection of methane.  Commercial monitoring equipment (direct reading) suitable
for screening application are also available specifically for carbon dioxide, and
sulfur dioxide. Similar field screening equipment are available for oxygen in  order
to check for the potential for intrusion of ambient air into  the subsurface gas
monitoring well. These screening monitors are available from most major industrial
hygiene equipment vendors. Direct reading gas detection (e.g., draeger) tubes are
also available for methane and  other subsurface gas  indicators for screening
applications.

     It is important that all monitoring procedures be fully documented and
supported  with adequate QA/QC procedures.   Information should include:
locations and depths of sampling points, methods used (including sketches and
photographs),  survey instruments  used,  date and  time, atmospheric/soil
temperature, analytical methods, and laboratory  used, if any.  Also see Section 4
(Quality Assurance and Quality Control).

     The three basic monitoring techniques available for sampling subsurface gas;
above ground air  monitoring, shallow  borehole monitoring, and gas well
monitoring are summarized below.

11.6.1    Above Ground Monitoring

     This technique consists of the collection of samples of the subsurface gas after
it has migrated out of the soil or into engineered  structures (e.g., within buildings
or along under-ground utility  lines.).  Basically, there is no difference in the
apparatus  from that described  for ambient air monitoring (Section  12).  The
locations at which sampling  is conducted, however, are selected to focus on areas
where gases might accumulate.  Sampling methods can utilize various types and
brands of portable direct-reading survey instruments (see  Table 11-5).  However,
because methane gas is frequently the major component of the  soil gas, those
which are most sensitive to methane, such as explosimeters and FID organic vapor
                                  11-37

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analyzers, are the preferred instruments. More selective air sampling methods are
used, however, for constituent analyses (see Section 12 - Air Methods).

11.6.2    Shallow Borehole Monitoring

    Shallow borehole monitoring involves subsurface gas monitoring to depths of
up to  6 feet below the ground surface.  Bar punches  or metal rods which can  be
hand-driven or hammered into the ground are used to make boreholes from which
gas samples are removed.  Table 11-6 provides the basic procedure for shallow and
deep subsurface monitoring techniques.  Sample collection should follow the same
methods employed during above ground monitoring.

    Shallow borehole monitoring, as previously  discussed, is  a  rapid screening
method and, therefore, has its limitations. Two major limitations are that negative
findings cannot assure the absence of a release at a  greater depth  and that  air
intrusion  can dilute the measured concentration levels of the sample.  Misleading
results can also be obtained if the surface soil layer is contaminated (e.g., due to a
spill).

11.6.3    Gas Well Monitoring

    Monitoring gas within wells will involve either the lowering of a sampling
probe (made of a nonsparking material) through a sealed cap on the top of the well
to designated depths, or the use of fixed-depth monitoring probes (see Figure 11 -3
and Table  11-6).   The probe outlet is usually connected  to the  desired gas
monitoring instrument. More information on gas well monitoring is provided in
Sections 9 (Soil) and 10 (Ground Water).

11.7 Site Remediation

    Although the RFI Guidance is not intended to provide detailed guidance  on
sites remediation, it should be recognized that certain data collection activities that
may be necessary for a Corrective Measures Study may be collected during the RFI.
EPA has developed a  practical guide for assessing  and remediating contaminated
site that  directs users toward technical support, potential data  requirements and
                                   11-38

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                               TABLE 11-6
                    SUBSURFACE SAMPLING TECHNIQUES
SHALLOW (Up to 6 ft deep)

     •    Select sampling locations based on soil data and existing monitoring
         data.

     •    Penetrate soil to desired depth. A steel rod 1/2 to 3/4 inch diameter and a
         heavy hammer are sufficient.  A bar punch equipped with  insulated
         handles is better for numerous  holes.  It is a small, hand  operated pile
         driver with a sliding weight on the top. Hand augers may also be used.

     •    Insert inert (e.g., Teflon) tubing to bottom of hole.  Tubing may be
         weighted or attached to  a small diameter stick to assure that it gets to
         the bottom of the hole. Tubing  should be perforated along bottom few
         inches to assure gas flow.

     •    Close top of hole around tubing using a gas impervious seal.

     •    Before sampling record well head pressure.

     •    Readings may be taken immediately after making the barhole.

     •    Attach meter or sampling pump and evacuate hole of air-diluted gases
         before recording gas concentrations or taking samples.

     •    When using a portable meter, begin with the most sensitive range (0-100
         percent by volume of the lower explosive limit (LEL) for methane).  If
         meter is pegged, change to the next least sensitive range to determine
         actual gas concentration.

     •    Tubing shall be marked, sealed, and protected if sampling will be done
         later.
                                  11-39

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                          TABLE 11-6(Continued)
                    SUBSURFACE SAMPLING TECHNIQUES
     •    If results are erratic the hole should  be  plugged and further readings
         taken a few minutes later.

     •    Monitoring should be repeated a day or two after probe installation to
         verify readings.

DEEP (More Than 6 ft deep)

     •    Same general procedures as above.

     •    Use portable power augers or truck-mounted augers.

     •    For permanent monitoring points, use rigid tubing (e.g., Teflon) and the
         general construction techniques shown in  Figure 11-4.

CAUTION

     •    When using hand  powered equipment, stop if any unusually  high
         resistance is met.  This resistance could be from a gas pipe or an electrical
         cable.

     •    Before  using  powered  equipment,  confirm  that  there  are  no
         underground utilities  in the  location(s) selected  (see Appendix C -
         Geophysical Techniques).

     •    Use non-sparking equipment and procedures and monitor for methane
         explosive limits.
                                  11-40

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technologies that may be applicable to  EPA programs such as RCRA and CERCLA.
The reference forthis guide is provided below.

     U.S. EPA.  1988.  Practical Guide for Assessing and Remediating Contaminated
     Sites.  Office of Solid Waste and  Emergency Response.  Washington, D.C.
     20460.

     The guide is designed to  address  releases to ground water as well as soil,
surface water and air. A short  description of the guide is provided in Section 1.2
(Overall RCRA Corrective  Action  Process),  under the  discussion of Corrective
Measures Study.
                                   11-41

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11.8 Checklist

                      RFI CHECKLIST - SUBSURFACE GAS
Site Name/Location  	
Type of Unit        	
1.    Does waste characterization include the following information?      (Y/N)
          •    Physical form of waste                                 	
          •    Chemical composition and concentrations
          •    Presence of biodegradeable waste components
          •    Quantities managed and dates of receipt
          •    Location of wastes in unit
          •    Waste material moisture content and temperature
          •    Chemical and physical properties of constituents
               of concern
2.    Does unit characterization include the following information?       (Y/N)
          •   Age of unit
          •   Construction integrity
          •   Presence of liner (natural or synthetic)
          •   Location relative to ground-water table or bedrock or
              other confining barriers
          •   Unit operation data
          •   Presence of cover or other surface covering to impede
              vertical gas migration
          •   Presence of gas col lection system
          •   Presence of surrounding structures such as buildings
              and utility conduits
          •   Depth and dimensions of unit
          •   Inspection records
          •   Operation logs
          •   Past fire, explosion, odor complaint reports
                                   11-42

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                RFI CHECKLIST - SUBSURFACE GAS (Continued)
         •    Existing gas/ground-water monitoring data
         •    Presence of natural or engineered barriers near unit
         •    Evidence of vegetative stress
3.    Does environmental setting information include the following
     information?                                                   (Y/N)
         •    Definition of regional climate
         •    Definition of site-specific meteorological conditions
         •    Definition of soil conditions
         •    Definition of site specific terrain
         •    Identification of subsurface gas migration routes
         •    Identification and location of engineered conduits
         •    Identification of surrounding structures
4.    Have the following data on the initial phase of the release
     characterization been collected?                                 (Y/N)
          •    Extent and configuration of gas plume                  	
          •    Measured methane and gaseous constituent
              concentration levels in subsurface soil and
              surrounding structures
          •    Sampling locations and schedule

5.    Have the following data on the subsequent phase(s) of the release   (Y/N)
     characterization been collected?
          •    Extent and configuration of gas plume
          •    Measured methane and gaseous constituent
              concentration levels in subsurface soil and surrounding
              structures
          •    Sampling locations and schedule
                                   11-43

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11.9 References

National Climatic Data Center. Local Climatoloqical Data - Annual Summaries
     with Comparative Data. National Oceanic and Atmospheric Administration.
     published annually. Asheville, N.C.

National Climatic Data Center. Climates of the States. National Oceanic
     and Atmospheric Administration. Asheville, N.C.

National Climatic Data Center. Weather Atlas of the United States.
     National Oceanic and Atmospheric Administration. Asheville, N.C.

South Coast Air Quality Management District.  1986.  Hazardous Pollutants in
     Class II Landfills. El Monte, California.

U.S. EPA. October 1986.  RCRA Facility Assessment Guidance.  NTIS PB87-107769.
     Office of Solid Waste. Washington, D.C. 20460.

U.S. EPA.  1983. Guidelines for Monitoring Indoor Air Quality.  EPA-600 14-83-046.
     NITS PB83-264465.  Office of Research and Development.  Washington, D.C.
     20460.

U.S. EPA.  January 1981. Guidance Manual for the Classification of Solid Waste
     Disposal Facilities.  NTIS PB81-218505. Office of Solid Waste. Washington, D.C.
     20460.

U.S. EPA.  1985. Technical Guidance for Corrective Measures - Subsurface Gas.
     Office of Solid Waste. Washington, D.C. 20460.
                                   11-44

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      APPENDIX C





GEOPHYSICAL TECHNIQUES
         C-1

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                               APPENDIX C

                        GEOPHYSICAL TECHNIQUES

     The methods presented in this Appendix have been drawn primarily from two
sources. The first, Geophysical Techniques for Sensing  Buried Wastes and Waste
Migration (Technos, Inc., 1982) was written specifically for application at hazardous
waste sites, and for an audience  with limited technical background.  All of the
surface geophysical methods discussed below can be found in this document. The
second, Geophysical Explorations (U.S.  Army Corps of Engineers, Engineering
Manual 1110-1-1802, 1979) is a more generic application-oriented manual which
contains the borehole methods described in this section.

     Caution should be exercised in the use of geophysical methods involving the
introduction or generation of an electrical current, particularly when contaminants
are known or suspected to be present which have ignitable or explosive properties.
The borehole methods are of particular  concern due to the possible build up of
large amounts of explosive or ignitable gases (e.g., methane).

ELECTROMAGNETIC SURVEYS

     The electromagnetic (EM)*  method provides a means of measuring the
electrical conductivity of subsurface soil, rock, and ground water.   Electrical
conductivity is a function of the type of soil and rock, its porosity, permeability, and
the fluids which fill the  pore space.  In  most cases the conductivity (specific
conductance) of the  pore fluids will dominate the measurement. Accordingly, the
EM method is applicable  both to assessment of natural geohydrologic  conditions
and to mapping of many types  of contaminant  plumes.  Additionally, trench
 *The term "electromagnetic" has been used  in contemporary literature as a
 descriptive term for other geophysical methods, including ground  penetrating
 radar and metal detectors which  are based  on electromagnetic principles.
 However, this document will use electromagnetic (EM) to specifically imply the
 measurement of subsurface conductivities by low frequency  electromagnetic
 induction. This is in keeping with the traditional use of the term in the geophysical
 industry from which the EM methods originated.
                                   C-2

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boundaries, buried wastes and drums, as well as metallic utility lines can be located
with EM techniques.

     Natural variations in subsurface conductivity may be caused by changes in soil
moisutre content, ground-water specific conductance, depth of soil cover over rock,
and thickness of soil and rock layers.  Changes  in basic soil  or rock types, and
structural  features such as fractures or voids  may  also produce changes in
conductivity.  Localized deposits of natural organics, clay, sand, gravel, or salt- rich
zones will also affect subsurface conductivity.

     Many contaminants will produce an increase in free ion concentration when
introduced into the soil or ground water systems. This increase over background
conductivity  enables detection and mapping of contaminated soil and ground
water at hazardous waste sites. Large amounts of organic fluids such as diesel fuel
can displace the normal soil moisture, causing a decrease in conductivity which may
also be mapped, although this is not commonly done. The mapping of a plume will
usually define the local flow  direction of contaminants. Contaminant migration
rates can be estimated by comparing measurements taken at different times.

     The absolute values of conductivity  for geologic materials (and contaminants)
are not necessarily diagnostic in themselves,  but the  variations in conductivity,
laterally and with depth, are significant.  It is these variations which enable the
investigator to rapidly find anomalous conditions (See Figure C-1).

     At hazardous waste sites, applications of EM can provide:

     •    Assessment of natural geohydrologic conditions;

     •    Locating and mapping of burial trenches and pits containing drums
         and/or bulk wastes;

     •    Locating and mapping of plume boundaries;

     •    Determination of flow direction in both unsaturated  and saturated
         zones;
                                   C-3

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                                                            Coil
                 INDUCED
                 CURRENT
                  LOOPS
                                             GROUND  SURFACE
 SECONDARY FIELDS
FROM CURRENT LOOPS
    SENSED BY
   RECEIVER COIL
Figure C-1.  Block diagram showing EM principle of operations.
                           C-4

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     •    Rate  of plume movement by comparing measurements taken  at  dif-
          ferent times; and

     •    Locating and mapping of utility pipes and cables which may affect other
          geophysical measurements, or whose trench may provide a pathway for
          contaminant flow.

     Chapter V of Geophysical Techniques for Sensing Buried Wastes and Waste
Migration (Technos. Inc., 1982) should be consulted for further detail regarding use,
capabilities, and limitations of electromagnetic surveys.

SEISMIC REFRACTION SURVEYS

     Seismic refraction techniques are used to determine the thickness and depth
of geologic layers and the travel time or velocity of seismic waves within the layers.
Seismic refraction methods are often used to map depths to specific horizons such
as bedrock, clay layers, and  the water table,  In  addition to mapping  natural
features, other secondary applications of the seismic method include the locations
and definition of burial pits and trenches.

     Seismic waves transmitted into the subsurface travel at different velocities in
various types of soil and rock, and are refracted (or bent) at the interfaces between
layers.  This  refraction  affects their path of travel.   An  array of  geophones
(transducers that respond to the motion of the ground) on the surface measures the
travel time of the seismic waves from the source to the geophones at a number of
spacings.  The time required for the wave to  complete  this path is measured,
permitting a determination to be made of the number of layers, the thicknesses of
the layers and their depths, as well as the seismic velocity of each  layer. The wave
velocity in each layer is directly related to its material properties such as density and
hardness.  Figure C-2 depicts the seismic refraction technique.

     Seismic refraction can be used to define natural geohydrologic  conditions,
including thickness and depth of soil and rock layers, their composition and physical
properties, and  depth to bedrock or the water table.  It can also be used for the
detection  and location of anomalous features,  such as pits and trenches and for
evaluation of the depth of burial sites or landfills.
                                    C-5

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     Specific details regarding the use of seismic refraction surveys, and the
capabilities  and limitations of this method can  be found  in  Chapter VII of
Geophysical Techniques for Sensing Buried Wastes and Waste Migration (Technos,
Inc., 1982).

RESISTIVITY SURVEYS

     The resistivity method  is used to measure the electrical resistivity of the
geohydrologic section which includes the soil, rock, and ground water. Accordingly,
the method may be used to assess lateral changes and vertical cross- sections of the
natural geohydrologic settings. In addition, it can be used to evaluate contaminant
plumes and locate buried wastes at hazardous waste sites. Figure C-3 is a graphical
representation of the concept of a resistivity survey.

     Applications of the resistivity method at hazardous waste sites include:

     •   Locating and mapping contaminant plumes;

     •   Establishing direction and rate of flow of contaminant plumes;

     •   Defining burial sites by:
         -  locating trenches,
         - defining trench boundaries, and
         - determining the depths of trenches; and

     •   Defining natural geohydrologic conditions such as:
         - depth to water table or to water-bearing horizons;  and
         - depth to bedrock, thickness of soil, etc.

     Chapter VI of Geophysical Techniques for Sensing Buried Wastes and Waste
Migration (Technos.  Inc., 1982), discusses methods, use, capabilities, and  limitations
of the resistivity method.
                                    C-7

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                                     .Current  Meter
              Current  Flow
              Through  Earth
                                         Current
                                         Voltage
                                                         Surface
Figure C-3. Diagram showing basic concept of resistivity measurement.
                             C-8

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GROUND PENETRATING RADAR SURVEYS

     Ground penetrating radar (GPR)* uses high frequency radio waves to acquire
subsurface information.  From a small antenna which is moved slowly across the
surface of the ground, energy is radiated downward into the subsurface, then
reflected back to the receiving antenna, where variations in the return signal are
continuously recorded.  This produces a  continuous cross-sectional  "picture" or
profile of shallow subsurface conditions. These responses are caused by radar wave
reflections from interfaces of materials having different electrical properties. Such
reflections are often associated  with natural  geohydrologic conditions such as
bedding, cementation, moisture  and clay content, voids, fractures, and intrusions,
as well as man-made objects.  The radar method has been used at numerous sites to
evaluate natural soil and rock conditions, as well as to detect buried wastes.  Figure
C-4depictsthe ground penetrating radar method.

     Radar responds to changes in soil and rock conditions.  An interface between
two soil or rock layers having sufficiently different electrical properties will show up
ir the radar profile. Buried pipes and other discrete objects will also be detected.

     Radar has effectively mapped soil layers, depth of bedrock, buried stream
channels, rock fractures, and cavities in natural settings. Radar applications include:

     •   Evaluation of the natural soil and geologic conditions;

     •   Location and delineation  of buried waste materials, including both bulk
         and drummed wastes;
      nas oeen canea oy various names: ground piercing radar, ground probing
 radar, and subsurface impulse radar. It is also known as an electromagnetic
 method (which in fact it is); however, since there are many other methods which
 are also electromagnetic, the term GPR has come into common use today, and is
 used herein.
                                   C-9

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       ANTENNA
CONTROLLER
                 5-300 M«ttr
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                                3
Figure C-4.  Block diagram of ground penetrating radar system.Radar waves are
           relfected from soil/rock interface.
                                 C-10

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     •   Location and delineation of contaminant plume areas; and

     •   Location and mapping of buried utilities (both metallic and nonmetallic).

     In areas where sufficient ground penetration is achieved, the radar method
provides a powerful assessment tool.  Of the geophysical methods discussed in this
document, radar offers the highest resolution. Ground  penetrating  radar methods
are further  detailed in Chapter IV of Geophysical Techniques for Sensing Buried
Wastes and  Waste Migration (Technos, Inc., 1982), as are this method's capabilities
and limitations.

MAGNETOMETER SURVEYS

     Magnetic measurements are commonly used to map regional geologic
structure and to explore for minerals.  They are also used to locate pipes and survey
stakes or to  map archeological sites. In addition, they are commonly used to locate
buried drums and trenches.

     A magnetometer measures the  intensity of the earth's magnetic field.  The
presence of  ferrous metals creates variations in the local strength of that field,
permitting their detection. A magnetometer's response is proportional to the mass
of the ferrous target.  Typically, a single drum can be detected at distances up to 6
meters, while massive piles of drums can be detected at distances up to 20 meters or
more. Figure C-5 shows the use of a magnetometer in detecting a buried drum.

     Magnetometers may be used to:

     •   Locate buried drums;

     •   Define boundaries of trenches filled with ferrous containers;

     •   Locate ferrous  underground utilities, such as iron pipes or tanks, and the
         permeable pathways often  associated with them; and
                                   C-11

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                                  Amplifier*
                                     and
                                   Counter
                                   Circuits
                                                          Chert and
                                                          Moo, TOM
                                                          Racardcrs
                                                  Ground Surface
Figure G5.   Simplified block diagram of a magnetometer.  A magnetometer
             senses change in the earth's magnetic field due to buried iron drum.
                                    C-12

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     •    Aid in  selecting drilling  locations that are clear of buried drums,
          underground utilities, and other obstructions.

     The use, capabilities, and limitations of magnetometer surveys at hazardous
waste sites are provided in Chapter IX of Geophysical Techniques for Sensing Buried
Wastes and Waste Migration (Technos. Inc., 1982).

BOREHOLE GEOPHYSICAL METHODS

     There are several different types of borehole geophysical methods used in the
evaluation of subsurface lithology, stratigraphy, and structure. Much of the  data
collected in boreholes is analyzed in conjunction with  surface geophysical data to
develop a more detailed  description of subsurface features. In  this section, the
major and  most applicable types of borehole geophysical methods are identified
and briefly discussed. They include:
     I.    Electrical Surveys
          a. Spontaneous Potential
          b.  Resistivity
     II.    Nuclear Logging
          a. Natural Gamma
          b.  Gamma Gamma
          c. Neutron
     III.   Seismic Surveys
          a. Up and Down Hole
          b. Crosshole Tests
          c. Vertical Seismic Profiling
     IV.   Sonic Borehole  Surveys
          a. Sonic Borehole Imagery
          b. Sonic Velocity
     V.    Auxiliary Surveys
          a. Temperature
          b. Caliper
          c. Fluid Resistivity

     All of the borehole methods presented in this section are detailed in the Army
Corps of Engineers Geophysical Explorations Manual (Engineering Manual 1110-1-
1802, 1979), with the exception of vertical seismic  profiling.  This method is
relatively new and further information can be found in Balch and Lee, 1984.
                                   C-13

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Electrical Surveys

     The two types of electrical subsurface surveys of geotechnical interest, both of
which involve continuous logging with depth of the electrical characteristics of the
borehole walls, are the spontaneous potential log and the borehole resistivity log.

     The spontaneous potential log (also known as self potential) is a record of the
variation with depth of naturally occurring electrical potentials (voltages) between
an electrode at the depth in a fluid filled borehole and another at *- 
-------

                                           • OREMOLE-FORMATlON
                                           FLUID
                                       
-------
                                                         AND
                                                      KECOKOCK
             INSULATED
         OOWMMOCf
         ELCCTHQOg
Figure C-7.   Single-point resistance log (prepared by the Waterways Experiment
             Station, U.S. Army Corps of Engineers, Vicksburg, Mississippi).
                                    C-16

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     Resistivity logging is a valuable tool in correlating beds from borehole  to
borehole. In addition, they can be used together with knowledge of ground water
and rock matrix resistivities (obtained from samples) to calculate porosities and/or
water saturations.  Also, if porosity is known and a borehole temperature log is
available, contaminant concentrations can  be inferred  by  electrical resistivity
variations.

Nuclear Logging

     Nuclear borehole logging can be used quite effectively for borehole depths
ranging from 10 to more than 1,000 feet.  At considerable depths, as for large
buried structures, nuclear logging is a very effective means of expanding  a small
number of data  points obtained from direct measurements on core  samples  to
continuous records of clay content, bulk density, water content, and/or porosity.
The logs are among the simplest to  perform and interpret, but the  calibrations
required for meaningful  quantitative  interpretations  must be meticulously
complete in attention to detail and consideration of all factors affecting nuclear
radiation in earth materials.  Under favorable conditions, nuclear measurements
approach the precisions of direct density tests on  rock cores. The gamma-gamma
density log and the neutron water content log require the use of isotopic sources of
nuclear radiation.  Potential  radiation hazards mandate thorough training  of
personnel working around these sources. Strict compliance with U.S. NRC Title 10,
Part 20, as well as local safety regulations, is required.   Additional information on
natural gamma, gamma-gamma, and neutron gamma methods is provided below.

     The natural gamma radiation tool is a passive device measuring the amount of
gamma radiation naturally  occurring in the strata being logged.  The  primary
sources of radiation are trace amounts of the potassium isotope K*o and isotopes of
uranium and thorium. K*o is most prevalent, by far, existing as an average of 0.012
percent by weight of all potassium. Because potassium is part of the crystal lattices
of illites, micas, montmorillanites, and other clay materials, the engineering gamma
log is mainly a qualitative indication of the clay content of the strata.

     The natural gamma log is put to its simplest and most frequently used
applications in qualitative lithologic interpretation (specifically identification  of
shale and clay layers) and bed correlations from hole to hole. Since clay fractions
                                   C-17

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frequently reduce the primary porosity and permeability of sediments, inferences as
to those  parameters may sometimes be possible from the natural gamma log.
Environmentally based surveys may utilize the log for tracing radioactive pollutants.
If regulatory restrictions allow the use of radioactive tracers, the natural gamma log
can be used to locate ground water flow paths. The natural gamma radiation level
is also a correction factor to the gamma-gamma density log.

     In the gamma-gamma logging technique, a radioactive source and detector
are used  to determine density variations in the  borehole.  An isotopic source of
gamma radiation can be placed on the gamma radiation tool and shielded so that
direct paths of that radiation from source to detector are  blocked.  The source
radiation then permeates the space and materials near itself.  As the gamma
photons pass through the matter, they are affected by several factors among which
is "Compton scattering."  Part of each photon's energy is lost to orbital electrons in
the scattering material. The amount of scattering is proportional to the number of
electrons present. Therefore, if the portion of radiation able to escape through the
logged earth materials  without being widely scattered and de-energized is
measured, then that is an inverse active measure of electron density. A schematic
representation of the borehole gamma-gamma tool is shown in Figure C-8.

     The neutron water detector logging method is much like the gamma-gamma
technique in that it uses a radioactive source and detector.  The difference is that
the neutron log measures water content  rather than density of  the borehole
material.  A composite isotopic source of neutron radiation can be placed on a
probe together with a neutron detector. A neutron has about the same mass and
diameter as a hydrogen nucleus and is much  lighter and smaller than any other
geochemically common nucleus.  Upon collision with a hydrogen nucleus the
neutron loses about half its kinetic energy to the nucleus and is slowed down as well
as scattered.  Collision with one of the larger nuclei  scatters the   neutron  but
does not slow it. After a number of collisions with hydrogen nuclei, a neutron is
slowed, or it is captured  by a hydrogen atom and produces a secondary neutron
emission  of thermal energy plus a secondary gamma photon.  Detectors can  be
"tuned"  to be sensitive to the epithermal (slowed)  neutron or to the thermal
                                   C-18

-------
                                         FORMATION
                                     BACKSCATTSRSD
                                          PHOTONS
COMPTQN

COLLISIONS
WITH
                     RADIATION
                     SHIELDING
                                                    ELECT KONS
                                     GAMMA
                                     SmiTTKD ?*0*
                                     ISOTOHC SOURCE

Figure C-8.   Schematic of the borehole gamma-gamma density tool (prepared by
            the Waterways Experiment Station, U.S. Army Corps of Engineers,
            Vicksburg, Mississippi).
                                   G19

-------
neutron or to the gamma radiation. One of these detectors plus the neutron source
is then a device capable of measuring the amount of hydrogen in the vicinity of the
tool. In the geologic environment, hydrogen exists most commonly in water (H2O)
and in  hydrocarbons.  If it can be safely assumed that hydrocarbons are not present
in appreciable  amounts, then the neutron-epithermal neutron, the neutron-
thermal neutron,  and the  neutron-gamma logs are measures of the amount of
water present if the tool  is calibrated in terms of its response to saturated rocks of
various porosities.

     The neutron log can  be used for hole to hole stratigraphic correlation.  Its
designed purpose is to measure water quantities in the formation. Therefore, the
gamma-gamma density, the neutron water detector, the natural gamma, and the
caliper logs together form a "suite" of logs that, when taken together, can produce
continuous interpreted values of water content, bulk density, dry density, void ratio,
porosity, and pecent of water saturation.

Seismic Surveys

     The principles involved in subsurface seismic surveys are the same as those
discussed earlier under surface seismic surveys. The travel times for P- and S- waves
between source and detector are measured, and wave velocities are determined on
the basis of theoretical travel paths. These calculated wave velocities can then be
used to complement and supplement other geophysical surveys conducted in the
area of investigation.

     Three common types of borehole seismic surveys are discussed  in this section.
They include Uphole and Downhole surveys, Crosshole Tests, and Vertical Seismic
Surveys. The applications and limitations are discussed for each of these methods.

     In the uphole and downhole seismic survey, a seismic signal travels between a
point in a borehole and a point on the ground near the hole. In an uphole survey
the energy source is in the  borehole, and the detector on the ground surface; in a
downhole survey, their positions are reversed. The raw data obtained are the travel
times for this signal and distances between the seismic source and the geophones.
A plot  of travel time versus depth yields, from the slope of the curve, the average
                                   C-20

-------
wave propagation velocities at various intervals in the borehole. Figure C-9 depicts a
downhole seismic survey technique.

     Uphole and downhole surveys are  usually performed to complement other
seismic tests and provide redundancy  in a geophysical test program.  However,
because these surveys force the seismic signals to traverse all of the strata between
the source and detector, they provide a means of detecting features, such as a low
velocity layer underlying a higher velocity layer of a "blind" or "hidden" zone (a
layer with insufficient thickness and velocity contrast to be detected by surface
refraction).

     Crosshole tests are conducted to determine the P- and S-wave velocity of each
earth material  or layer within the depth of interest through the measurement of
the arrival time of a seismic signal that has traveled from a source in one borehole
to a detector in another. The crosshole test concept is shown in Figure C-10.

     In addition to providing true P- and S-wave velocities as a function of depth,
their companion purpose is to detect seismic anomalies, such as a lower velocity
Tone underlying a  higher velocity zone or a layer with insufficient thickness and
velocity contrast to  be detected by surface refraction seismic tests.

     The vertical seismic profiling technique involves the recording of seismic waves
at regular and closely spaced geophones in the borehole. The surface source can be
stationary or it  can  be moved to evaluate seismic travel times to borehole
geophones, calculate velocities, and determine the nature of subsurface features in
the vicinity of the borehole.

     Vertical seismic profiling surveys are different from downhole surveys in that
they provide data on not only direct path seismic signals, but reflected signals as
well.  By moving the surface source to discrete distances and azimuths from the
borehole, this  method provides a means of characterizing the nature and con-
figuration of subsurface interfaces (bedding, ground water-table, faults), and
anomalous velocity zones around the borehole.
                                   C-21

-------
                                                SYSTEM
                      HAMMER WITH
                      MICROSWITCH
       ORTHOGONAL SIDE-
       WALL CLAMPED.
       VELOCITY DETECTORS
                                     76.2 MILLIMETRES. I.D.
                                     3.0 INCHES. I.D.
Figure C-9.   Downhole survey techniques for P-wave data (prepared by the
            Waterways Experiment Station, U.S. Army Corps  of  Engineers,
            Vicksburg, Mississippi).
                                  C-22

-------
                                  RECOMOE*
                                   (TIMER)
                                                      • ECEIVSP*
Figure C-10.  Basic crosshoie test concept (prepared by the Waterways Experiment
            Station, U.S. Army Corps of Engineers, Vicksburg, Mississippi).
                                    C-23

-------
     The interpretation  of  processed vertical seismic profiling data  is used in
conjunction with surface seismic surveys as well as other geophysical surveys in the
evaluation of subsurface lithology, stratigraphy, and structure.  Vertical  seismic
profiling survey interpretations  also provide a basis for correlation  between
boreholes.

Sonic Borehole Surveys

     In this section, two types of continuous borehole  surveys involving  high
frequency sound wave  propagation are  discussed.  Sound waves are physically
identical to seismic P-waves.  The  term sound wave is usually  employed when the
frequencies include the audible range and the propagating medium is air to water
Ultrasonic waves are also physically the same, except that the frequency range is
above the audible range.

     The Sonic borehole imagery log provides a record of the surface configuration
of the cylindrical wall of the borehole. Pulses of high frequency sound are used in a
way similar to marine sonar to  probe the wall of the  borehole and, through
electronic and photographic means, to  create a visual image representing the
surface configuration of the borehole wall. The physical principle involved is wave
reflection  from a high impedance surface, the same principle used  in  reflection
seismic surveying and acoustic subbottom profiling. The  sonic borehole imagery
logging concept is depicted in Figure C-11.

     The sonic  borehole imagery log can  be used to detect discontinuities in
competent rock lining the borehole.  Varying lithologies, such as shale, sandstone,
and  limestone,  can sometimes be distinguished  on high quality records by ex-
perienced personnel.

     Another method of sonic borehole  logging is referred to as the continuous
sonic velocity logging technique.  The continuous sonic velocity logging device is
used to measure and record the transit time of seismic waves along the borehole
wall between two transducers as it is moved up or down the hole. A diagram of the
continuous sonic velocity logging device is provided in Figure C-12.
                                   C-24

-------
                                                     SUPPLY
                                                IMAGING DEVICE
                                                o   o   o
    COMPASS OK
    DIRECTION
    SENSOR
    ULTRASONIC
    ACOUSTIC
    SEAM
ROTATING
PIEZOELECTRIC
TRANSDUCER
                                            AZIMUTHAU OIKICTIONS
                                            ABOVE "UNWHAPPEO"
                                            •OMCHOue IMAGE
                                            WITH IMAGES O*
                                            TWO
Figure C-11.  Sonic imagery  logger (prepared by the Waterways Experiment
             Station, U.S. Army Corp of Engineers, Vicksburg, Mississippi).
                                    C-25

-------
             ACOUSTIC  ISOIATO*
                 UCIIVCR
              MlIIIK null
                                           &
                                          HF
Figure C-12.  Diagram of three-dimensional velocity tool (courtesy of Seismograph
            Service Corporation, Birdweil Division).
                                   C-26

-------
     This subsurface logging method  provides data on fractures and  abrupt
lithology changes along the borehole wall that can be effective in characterizing
the nature of surrounding material as well as borehole correlation in lithology and
structure.

Auxiliary Surveys

     An auxiliary survey is the direct measurement of  some  parameter of the
borehole or its contained fluid to provide information that will either permit the
efficient evaluation  of the lithology  penetrated by the  boring  or  aid in the
interpretation or reduction of the data from other borehole logging operations. In
most instances, auxiliary logs are made where the property recorded is essential to
the quantitative evaluation of other geophysical logs. In some instances, however,
the auxiliary results can be interpreted and used directly to infer the existence of
certain lithologic or hydrologicconditions.

     Discussed here are three different auxiliary logs; fluid temperature,  caliper,
and fluid resistivity, that are especially applicable to the logging me  hods discussed
in this text  A description of each auxiliary log is presented below.

     Temperature logs are the continuous records of the temperature encountered
at successive elevations in a borehole. The two basic types of temperature logs are
standard (gradient) and differential. Both types of  logs rely  upon a downhole
probe, containing one  or more temperature sensors (thermistors) and  surface
electronics to monitor and  record the  temperature changes  encountered in a
borehole.  The standard temperature  log  is the result of a single  thermistor
continuously sensing the thermal gradient of the fluid in the borehole as the sonde
is raised or lowered in  the  hole.  The differential temperature  log  depicts the
difference  in temperature  over a  fixed  interval  of depth in the borehole by
employing two thermistors spaced from one to several feet apart or through use of
a single thermistor and  an electronic memory to compare the temperature at one
depth with that of a selected previous depth.
                                   C-27

-------
     Temperature logs provide  useful information in  both cased and  uncased
borings and are necessary for correct interpretation of other geophysical logs
(particularly resistivity logs). Temperature logs can also be used directly to indicate
the source and movement of water into a borehole, to identify aquifers, to locate
zones of potential recharge, to determine areas containing wastes discharged into
the ground, and to detect sources of thermal pollution. The thermal conductivity
and permeability of rock formations can be inferred from temperature logs as can
be the location of grout behind casing by the presence of anomalous zones of heat
buildup due to the hydration of the setting cement.

     The caliper log is a record of the changes in borehole casing or cavity size as
determined by a highly sensitive borehole measuring device.  The record may be
presented in the form of a continuous vertical profile of the borehole or casing wall,
which  is obtained with normal or  standard  caliper logging systems, or as a
horizontal cross section  at selected depths, used  for measuring  voids  or large
subsurface openings.  There are two basic methods of obtaining caliper logs. One
technique utilizes mechanically activated measuring arms or bown springs, and the
other employs piezoelectric transducers  for sending  and  receiving a  focused
acoustic signal.  The acoustic method requires that the hole be filled with  water or
mud, but the mechanical method operates equally well in water, mud,  or air.
Reliable mechanically derived caliper logs can be obtained in small (2 in.) diameter
exploratory borings as well as large (36 in.) inspection or access calyx-type borings.

     Caliper or borehole diameter logs represent one of  the most useful and
possibly the simplest of all  techniques employed in borehole geophysics.  They
provide a means for determining inhole conditions and should be  obtained in all
borings in which other geophysical logs are contemplated. Borehole diameter logs
provide information on subsurface lithology and  rock quality.  Borehole diameter
varies with the hardness, fracture frequency, and cementation of the various beds
penetrated.  Borehole diameter logs can be used to accurately identify  zones of
enlargement (washouts) or construction (swelling), or to  aid in the structural
evaluation of an area by the accurate location of fractures  or solution openings,
particularly in borings where core loss has presented a problem.  Caliper  logs also
are a means of identifying the  more porous zones in  a boring by locating the
intervals in which excessive mud filter cake has  built up  on the walls of the
borehole. One of the major uses of standard or borehole caliper logs is to provide
                                   C-28

-------
information by which other geophysically derived raw data logs can be corrected
for borehole diameter effects.  This is particularly true for such nonfocused logs as
those obtained in radiation logging or the quantitative evaluation of flowmeter
logs or tracer and water quality work where inhole diameters must be considered.
Caliper logs also can be useful to evaluate inhole conditions for placement of water
well screens or for the selection of locations of packers for permeability testing.

     The fluid resistivity log is a continuous graphical record of the resistivity of the
fluid within a borehole.  Such records are  made by measuring the voltage drop
between two closely spaced electrodes enclosed within a downhole probe through
which a representative sample of the borehole fluid is channeled. Some systems,
rather than recording in units  of resistivity, are designed to provide a log of fluid
conductivity.  As conductivity is merely the reciprocal of resistivity, either system  can
be  used  to collect the information on inhole fluid required  for the  correct
interpretation of other downhole logs.

     The primary use of fluid resistivity or  conductivity  logs is to provide
information for the correct interpretation of other borehole logs. The evaluation of
nuclear and most electrical logs requires corrections for salinity of the inhole fluids,
particularly when quantitative parameters  are desired for determining porosity
from formation resistivity logs.
                                    C-29

-------
             APPENDIX 0

   SUBSURFACE GAS MIGRATION MODEL
            ADAPTED FROM
GUIDANCE MANUAL FOR THE CLASSIFICATION
   OF SOLID WASTE DISPOSAL FACILITIES
             U.S. EPA, 1981
                 D-1

-------
                               APPENDIX D

                   SUBSURFACE GAS MIGRATION MODEL

METHANE MIGRATION DISTANCE PREDICTION CHARTS

     Migration distance charts have been developed to estimate methane distances
and to plan the monitoring program.  The basic methane migration  distance
prediction chart and appropriate corrective factor charts were produced by
imposing a set of simplifying assumptions on  a general  methane migration
computer model.  These charts are based on a number of assumptions that were
made to produce them. Case Study Number 24 (Volume IV) illustrates the use of the
Subsurface Gas Migration Model.

     To illustrate the use of the charts, an example landfill is shown in Figure D-1
along with two cross-sections. Conditions along each side of the waste deposit are
typical conditions that could be encountered.  A similar sketch or plan  of a facility
being evaluated should be prepared. The land use within 1/4-mile of the solid waste
limits, including offsite and facility structures, should be on the map. The property
boundaries and solid waste deposit limits should also be plotted, as has been done
in Figure D-1.

     Additional data needs are:

     1.   The age of the site from the initial deposit of organic waste in years;

     2.   The average elevation of the bottom of the solid waste;

     3.   Natural boundaries and topography around the site; and

     4.   The  average elevation below the solid waste of  a gas impervious
         boundary such as unfractured  rock.
                                   D-2

-------
                                          Houses
                  Mudhole Creek

                                     /
            Agricultural  '
                               Agricultural Area
                                     400'
                           Landfill
                                  Waste Limits
   Gatehouse *
          m
                                       Equipment
                                            Shed '
                                         Wooded Lowland
                                                o
                                                                       Houses
                                                                El
  West


Agricultural    /+   Sand—»"
'\f-
                        Solid Waste
>
                                                                          East
                                                      M.
                                                                             House
                                                                .Sand	

                                                        Ground-Water Level
                                 Section A-A
                                                                         North
         South
                                                        Ground-Water Level
                                 Section B-B
   Note: Not to Scale
                        FIGURE D-1.  EXAMPLE LANDFILL
                                    D-3

-------
     Two calculations of migration distance from the waste boundary are needed
for each side of the landfill:

     1.   The 5 percent  (Lower Explosion  Limit or LEL) distance  for property
         boundaries.

     2.   The 1.25 percent (1/4 of the LEL) distance for onsite facility structures.

     After preparation  of the sketch and cross-sections, the determination of the
estimated migration distances begins with the use of Figure D-2 for the 5 percent
methane (LEL) migration distance and for the  1.25 percent (1/4 LEL) distance These
distances are then modified, if necessary, with the corrective factors for each depth
and surrounding soil surface permeability (Figures D-3 and D-4). The final distances
of migration for each side of the landfill can then be plotted on the landfill sketch
for comparison to property boundary and structures locations.

UNCORRECTED MIGRATION DISTANCES

     The use of Figure D-2 requires the age of the  site and the type of soil
extending out from each side of the solid waste deposit. The graph is entered with
the site age, moving  up to the appropriate soil type and methane concentration
(1.25 or 5 percent).  Interpolations between the sand and clay lines on the graph can
be made for other soils,  using the following general guidance:
Soil Name                         USCS Classification             Chart Use
Clean (no fines)                    GW, GP, SW, SP                Sand
gravels and sands
Silty gravels and sands,              GM, SM,  ML, OL, MH           Interpolate
silt, silty and sandy
loam, organic si Its
Clayey gravels and                  GC, SC, CL, CH, OH             Clay
sands, lean, fat, and
organic clays
                                    D-4

-------
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     The uncorrected  migration distance from the solid waste limit can then be
read on the left for the appropriate site age and soil type.

     If the soil along a given boundary is stratified and the variability extends from
the waste deposit to the property boundary, the most permeable unsaturated
thickness should be used in entering the charts.  For example, if dry, clean sand
underliessurficial silty clays, the uncorrected migration distance should be obtained
using the sand line of the chart. If there are questions as to the extent of particular
soils along  a boundary,  helpful  information  might be obtained  from Soil
Conservation Services (SCS)  Soil Survey Maps or the landfill operator.  Field
inspection,  SCS maps,  and permit boring information are sufficient.  Additional
borings are not necessary as this is only a ranking procedure.  Where there is doubt,
use the most permeable soil group present.

     For the  example  landfill in Figure D-1, the uncorrected  5 percent methane
migration distances for a  10-year old landfill would be (Figure C-2):

     Section A-A:    East side, 10 years, sand = 165'
                    West side, 10 years, sand =  165'

     Section B-B:    South side, 10 years, sand =  165'
                    North side, 10 years, clay =  130'

     The corresponding uncorrected distances for  the 1.25  percent methane
migration would be:

     Section A-A:    East side, 10 years, sand = 225'
                    West side, 10 years, sand =  135'

     Section B-B:    South side, 10 years, sand =  255'
                    North side, 10 years, clay =  200'

     The depth to corrective mulitpliers for the example sites would be:

     Section A-A:    East side, 10 years, 20'deep  » 1.0
                    West side, 10 years, 20'deep = 1.0
                                    D-8

-------
     Section B-B:    South side, 10 years, 10' deep = 0.95
                    North side, 10 years, 50'deep = 1.4

VENTING CONDITIONS CORRECTION

     The corrective factors for the surrounding soil venting conditions are obtained
using the  chart in  Figure D-4.   This chart is based on the assumption that the
surrounding surficial soil is impervious 100 percent of the time.  Thus, the value read
from the chart must be adjusted, based on the percentage of time the surrounding
surficial soil is saturated or frozen and the percentage of land along the path of gas
migration  from which gas venting to the atmosphere is blocked all year (asphalt or
concrete roads or parking  lots, shallow perched ground water, surface water bodies
not interconnected to ground water). The totally impervious corrective factor is
only used when the landfill is entirely surrounded at all times by these conditions.
Both time and area adjustments are necessary,  and the percentages are additive.
Estimates to the nearest 20 percent are sufficient. An adjusted corrective factor is
obtained by entering the  chart with site age and obtaining the totally impervious
corrective  factor for the appropriate depth and soil type and then entering this
value in the following equation :

     Adjusted corrected factor = [(Impervious corrective factor)-1)]
                                  x [5 of impervious time or area] +  1

     When free venting conditions are prevalent most of the year, simply use 1.0
(no correction). For depths less than 25 feet deep, use the 25 foot value.  For the
example site, the adjusted corrective factors for frozen or wet soil  conditions 50
percent of the year are:

     Section A-A:    East side (ignore narrow   = (2.1-1)(0.50) + 1 a 1.55
                    road, sand 20'deep,
                    10 years old)

                    West side (sand 20'deep,  = (2.1-1)(0.50) + 1 = 1.55
                    10 years old)
                                    D-9

-------
     Section B-B:    South side (sand, 10 deep, = (2.1-1)(0.50) + 1 = 1.55
                     10 years old)

                     North side (clay, 50'deep, = (1.4-1)(0.50) + 1 = 1.2
                     10 years old)

     Once the surface venting factors  have been tabulated as in Table D-1, the
corrective distance can be obtained by multiplying across the chart for each side of
the landfill. These values can then be plotted on the scale plan to describe contours
of the 5 percent and 1.25  percent methane concentrations or simply compared to
the distance from  the waste deposit to structures of concern (Figure D-5).
                                    D-10

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                   cs
                            Houses
                     1.25%
NOTE: NOT TO SCALE
  FIGURE D-5. EXAMPLE LANDFILL METHANE CONDITIONS
                      D-12

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                       APPENDIX E

ESTIMATION OF BASEMENT AIR CONTAMINANT CONCENTRATIONS DUE TO
VOLATILE COMPONENTS IN GROUND WATER SEEPED INTO THE BASEMENT
                          E-1

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                              APPENDIX E

    ESTIMATION OF BASEMENT AIR CONTAMINANT CONCENTRATIONS DUE TO
    VOLATILE COMPONENTS IN GROUND WATER SEEPED INTO THE BASEMENT
     Ground water can  reach the basement and the walls of a house in several
ways. If ground water is contaminated by volatile components, there are several
possibilities that the indoor ambient air can be affected by these constituents.
There are several methods which can be applied to estimating the ambient air
concentrations in the basement into which the contaminants are volatilized from
ground water. The manner in which and the extent to which  the ground water
reaches the basement or the walls will dictate the choice of a method.

     Two cases are considered as example scenarios:   Case 1)  Ground water is
seeped inside the basement completely wetting the basement, with a visual
indication of water on the floor.  Case 2) The basement is partially wetted without
a visual indication of liquid on the floor. This latter case can be subdivided into two
subcases:  Subcase 1)  involving a damp floor evident on the surface; Subcase 2)
involving a floor without observable dampness on the floor surface but with ground
water underneath the concrete floor.

     The way  the emission rates are estimated will be different for the three cases.
If the emission flux rate per unit square area of the exposed surface is denoted by E
(g/m2 day), then in all cases the air concentration, C (ug/m3), in the basement can be
estimated from:
                  C(ug/m3) = E

where         A  a basement floor and wall area exposed to ground water, m2

              VB = volume of the basement, m3, and

              te  - air exchange time for the basement, days.
                                  E-2

-------
     The air exchange time should be determined on a site-specific or situation-
specific basis. The tight room will have a longer time per air exchange in the room,
and the room with an exhaust fan will have a shorter time per air exchange.  The
default value for a typical house could bete = 0.05 days.

     The emission rates in  Eq. (1) can be estimated for the various case scenarios
illustrated above.

     Case 1.   Wet basement with visible liquid.

     The volatilization is a mass transfer phenomenon from the liquid phase of
ground water on the floor to the basement air.  Emission flux rate can be estimated
from:

                             E = KOL(CL-CL*)                            (2)

where KQL = overall mass transfer coefficient in the liquid phase unit, m/day, C|_ =
concentration of contaminant in water, g/m3, and  CL* = liquid phase concentration
in equilibrium concentration with the basement air, g/m3.  The equilibrium
concentration C* could be assumed to be approaching a small value compared to
the ground water contaminant concentration when the air exchange rate is high, or
when the time per air exchange is small. But this assumption would not be valid at a
low air exchange rate or at a longer time for a room air exchange. In this case, the
emission flux rate should be estimated by a trial and error method using Equation
(2) in combination with Equation (1), and Henry's Law constant.

     It is a well-established scientific principle to  use the two-resistance theory to
obtain the overall mass transfer coefficient, KQL, as follows:
                                         Hck
                                                                       (3)
where kj. and kg = individual mass transfer coefficients in liquid and gas phases,
respectively, m/day, and HC = dimensionless Henry's Law  constant obtained from
                                    E-3

-------
concentration units for gas and liquid phase concentrations. The numerical value
for HC can  be calculated  from Henry's Law constant given in atm/g-mol.m3 by
multiplying by 41.  Default values for the individual mass transfer coefficients can be
estimated from:
44 >
MW
i!i
i »
I 100
M
cm
          kL = 3      cm    I  44  \ «  /  24       M      hr
                      hr    I  MW  |    \  100      cm      day
       1
       t2
MW J    I  100      cm      day |      (5)
                      cm    /  18  \ 2  /  24       M       hr
where MW = molecular weight of the contaminant.

     Case 2.  Basement partially wetted with no visual indication of liquid.

     (a) Subcase  1.  Dampness evident on  the  floor  or  wall  surface.  The
volatilization process can  be treated as a diffusional process from the air at the
water-air interface through the air pores in the basement floor material and into
the basement air.  The diffusional process can be solved using the approach
described in the EPA report Development of Advisory Levels for Polychlorinated
Biphenvls (PCBs) Cleanup (PB86-232774). The final result needed for emission flux
estimation would be:
                                2e Dej       u
                                             H
                                   E-4

-------
where e = porosity of the floor material, Dej = effective diffusivity in the air pores
( = Dj e 1/3), m2/day, Dj = molecular diffusivity, m2/day, T = averaging time, days,
and a = Dei e/(e  + (1-e))/Hc. If steady state conditions are achieved as a result of a
continuous supply of contaminated water to the floor surface, it may be more
appropriate to treat the emission rate problem using Eq. (2) rather than Eq. (6).

     (b) Subcase  2. No dampness evident on the floor or wall surface but ground
water underneath the basement or wall material. Diffusion through the air space
of the floor or wall material will result in a slow release of volatile contaminants
from ground water to the basement air. The steady state flux rate can be estimated
from:
                            = D, ,4/3
where h = thickness of the barrier between the surface of ground water and the
air-basement floor interface, m.  When the basement air concentration is small
compared to the HcCt term in Eq. (7), the C term can be ignored in estimating e from
Eq. (7). Otherwise Eq.  (7) should be solved along with Eq. (1) requiring a trial and
error solution.
                                    E-5

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            APPENDIX F

METHOD 1312: SYNTHETIC PRECIPITATION
        LEACH TEST FOR SOILS

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                        METHOD 1312

        SYNTHETIC PRECIPITATION LEACH TEST FOR SOILS

1.0  SCOPE AND APPLICATION

     1.1  Method 1312 is designed to determine the mobility of
both organic and inorganic contaminants present in soils.

     1.2  If a total analysis of the soil demonstrates that in-
dividual contaminants are not present in the soil, or that they
are present but at such low concentrations that the appropriate
regulatory thresholds could not possibly be exceeded, Method
1312 need not be run.

2.0  SUMMARY OF METHOD

     2.1  The particle size of  the soil is reduced (if necessary)
and is extracted with an amount of extraction fluid egual  to 20
times the weight of the soil.  The extraction fluid employed is
a function of the region of the country where the soil site is
located.  A special extractor vessel is used when testing  for
volatiles.  Following extraction, the liguid extract is separated
from the soil by 0.6-0.8 urn glass fiber filter.

3.0  INTERFERENCES

     3.1  Potential interferences that may be encountered  during
analysis are discussed in the individual analytical methods.

4.0  APPARATUS AND MATERIALS

     4.1  Agitation apparatus - an acceptable agitation apparatus
is one which is capable of rotating the extraction vessel  in an
end-over-end fashion at 30 + 2 rpm (see Figure 1).  Suitable
devices known to EPA are identified in Table 2.

     4.2  Extraction vessel - acceptable extraction vessels are
those that are listed below:

         4.2.1 Zero Headspace Extraction Vessel (ZHE) - This
     device is for use only when the soil is being tested  for the
     mobility of volatile constituents (see Table 1).  The ZHE is an
     extraction vessel that allows for liguid/solid separation within
     the device and which effectively precludes headspace  (as depicted
     in Figure 3).  This type of vessel allows for initial liguid/soli
     separation, extraction, and final extract filtration  without
     having to open the vessel (see Step 4.3.1).  These vessels shall
     have an internal volume of 500 to 600 mL and be eguipped to
     accommodate a 90-mm filter.  Suitable ZHE devices known to EPA
     are identified in Table 3.  These devices contain viton 0-rings
     which should be replaced frequently.  For the ZHE to  be acceptabl
     for use, the piston within the ZHE should be able to  be moved

                             1312-1                   Revision 0
                                                      December 1988

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     with approximately 15 psi or less.  If it takes more pressure
     to move the piston, the 0-rinqs in the device should be replaced.
     If this does not solve the problem, the ZHE is unacceptable for
     1312 analyses and the manufacturer should be contacted.  The ZHE
     should be checked after every extraction.  If the device con-
     tains a built-in pressure gauge, pressurize the device to
     50 psi, allow it to stand unattended for 1 hour, and recheck
     the pressure.  If the device does not have a built-in pressure
     gauge, pressurize the device to 50 psi, submerge it in water
     and check for the presence of air bubbles escaping from any
     of the fittings.  If pressure is lost, check all fittings and
     inspect and replace 0-rings, if necessary.  Retest the device.
     If leakage problems cannot be solved, the manufacturer should
     be contacted.

         4.2.2  When the soil is being evaluated for other than
     volatile contaminants, an extraction vessel that does not pre-
     clude headspace (e.g. a 2-liter bottle) is used.  Suitable
     extraction vessels include bottles made from various materials,
     depending on the contaminants to be analyzed and the nature of the
     waste  (see Step 4.3.3).  It is recommended that borosilicate
     glass bottles be used over other types of glass, especially
     when inorganics are of concern.   Plastic bottles may be used
     only if inorganics are to be investigated.  Bottles are available
     from a number of laboratory suppliers.  When this type of ex-
     traction vessel is used, the filtration device discussed in
     Step 4.3.2 is used for initial liguid/solid separation and final
     extract filtration.

         4.2.3  Some ZHEs use gas pressure to actuate the ZHE piston,
     while others use mechanical pressure (see Table 3).   Whereas
     the volatiles procedure (see Step 7.4) refers to pounds-per-
     sguare inch (psi), for the mechanically actuated piston, the
     pressure applied is measured in torque-inch-pounds.   Refer to
     the manufacturer's instuctions as to the proper conversion.

     4.3  Filtration devices - It is recommended that all filtrations
be performed in a hood.

         4.3.1  Zero-Headspace Extractor Vessel (see Figure 3) -
     When the waste is being evaluated for volatiles, the zero-
     headspace extraction vessel is used for filtration.   The device
     shall be capable of supporting and keeping in place the fiber
     filter, and be able to withstand the pressure needed to accomplish
     separation (.50 psi).

         NOTE; When is it suspected that the glass fiber filter
               has been ruptured, an in-line glass fiber filter may be
               used to filter the material within the ZHE.

          4.3.2  Filter holder - when the soil is being evaluated
     for other than volatile compounds, a filter holder capable of


                             1312-2                   Revision 0
                                                      December 1988

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     supporting a glass fiber filter and able to withstand 50 psi
     or more of pressure shall be used.   These devices shall have a
     minimum internal volume of 300 mL and be equipped to accomodate
     a minimum filter size of 47 mm (filter holders having an
     internal capacity of 1.5 liters or greater are recommended).

         4.3.3  Materials of construction - filtration devices shall
     be made of inert materials which will not leach or absorb soil
     components. Glass, polytetrafluoroethylene (PTFE) or type 316
     stainless steel equipment may be used when evaluating the mcbilit
     of both organic and inorganic components.  Devices made of nigh
     density polyethylene (HOPE), polypropylene, or polyvinyl chloride
     may be used only when evaluating the mobility of metals.  Boro-
     silicate glass bottles are recommended for use over other types
     of glass bottles, especially when inorganics are constituents
     of concern.

     4.4  Filters - filters shall be made of borosilicate glass
fiber, shall have an effective pore size of 0.6 - 0.8 urn and
shall contain no binder materials.  Filters known to EPA to meet
these requirements are identified in Table 5. When evaluating the
mobility of metals, filters should be acid-washed prior to use
by rinsing with 1.ON nitric acid followed by three consecutive rinses
with deionized distilled water (a minimum of 1-liter per rinse is
recommended).  Glass fiber filters are fragile and should be handled
with care.

     4.5  pH meters - any of the commmonly available pH meters are
acceptable.

     4.6  ZHE extract collection devices - TEDLAR bags, glass, stain-
less steel or PTFE gas tight syringes are used to collect the volatili
extract.

     4.7  Laboratory balance - any laboratory balance accurate to
within + 0.01 g may be used (all weight measurements are to be within
+_ 0.1 g).

     4.8  ZHE extraction fluid transfer devices - any device capable
of transferring the extraction fluid into the ZHE without changing
the nature of the extraction fluid is recommended.

5.0  REAGENTS

     5.1 Reagent water-- reagent water is defined as water in
which an interferent is not observed at or above the method
detection limit of the analyte(s) of interest.  For non-volatile
extractions, ASTM Type II water, or equivalent meets the definition
of reagent water.  For volatile extractions, it is recommended
that reagent water be generated by any of the following methods.
Reagent water should be monitored periodically for impurities.
                             1312-3               .    Revision 0
                                                      December 1988

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         5.1.1  Reagent water for volatile extractions may be
     generated by passinq tap water through a carbon filter bed
     containing about 500 g of activated carbon (Calgon Corp.,
     Filtrasorb 300 or equivalent).

         5.1.2  A water purification system (Millipore Super-Q or
     equivalent) may also be used to generate reagent water for
     volatile extractions.

         5.1.3  Reagent water for volatile extractions may also
     be prepared by boiling water for 15 minutes.   Subsequently,
     while maintaining the water temperature at 90 + 5°C,  bubble
     a contaminant-free inert gas (e.g.  nitrogen)  through  the
     water for 1 hour.  While still hot, transfer the water to a
     narrow-mouth screw-cap bottle under zero headspace and seal
     with a Teflon lined septum and cap.

     5.2  Sulfuric acid/nitric acid (60/40 weight percent  mixture)
H2S04/HN03.  Cautiously mix 60 g of concentrated sulfuric  acid with
40 g of concentrated nitric acid.

     5.3  Extraction fluids:

         5.3.1  Extraction fluid #1 - this fluid is made by adding
     the 60/40 weight percent mixture of sulfuric and nitric acids
     to reagent water until the pH is 4.20 + 0.05.

         5.3.2  Extraction fluid #2 - this fluid is made by adding
     the 60/40 weight percent mixture of sulfuric and nitric acids
     to reagent water until the pH is 5.00 + 0.05.

         5.3.3  Extraction fluid #3 - this fluid is reagent water
     (ASTM Type II water, or equivalent) used to determine cyanide
     leachability.

     Note;  It is suggested that these extxraction fluids  be moni-
            tored frequently for impurities.   The pH should be
            checked prior to use to ensure that these fluids are
            made up accurately.

     5.4  Analytical standards shall be  prepared according to the
appropriate analytical method.

6.0  SAMPLE COLLECTION, PRESERVATION, AND HANDLING

     6.1  All samples shall be collected using an appropriate
sampling plan.

     6.2  At least two separate representative samples of  a soil
should be collected.  The first sample is used to determine if the
soil requires particle-size reduction and, if desired, the percent
solids of the soil.  The second sample is used for extraction
of volatiles and non-volatiles.


                              1312-4                  Revision 0
                                                      December 1988

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     6.3  Preservatives shall not be added to samples.

     6.4  Samples shall be refrigerated to minimize loss of volatile
organics and to retard biological activity.

     6.5  When the soil is to be evaluated for volatile contaminants,
care should be taken to minimize the loss of volatiles.  Samples
shall be taken and stored in a manner to prevent the loss of
volatile contaminants.  If possible, it is recommended  that any
necessary particle-size reduction be conducted as the sample is
being taken.

     6.6. 1312 extracts should be prepared for analysis and
analyzed as soon as possible following extraction.   If  they need
to be stored, even for a short period of time, storage  shall be at
4°C, and samples for volatiles analysis shall not be allowed to
come into contact with the atmosphere (i.e. no headspace). See
Section 8.0 (Quality Control) for acceptable sample and extract
holding times.

7.0  PROCEDURE

     7.1 The preliminary 1312 evaluations are performed on a mini-
mum 100 g representative sample of soil that will not actually under-
go 1312 extraction (designated as the first sample in Step 6.2).

         7.1.1  Determine whether the soil requires particle-size
     reduction.  If the soil passes through a 9.5 mm (0.375-inch)
     standard sieve, particle-size reduction is not required
     (proceed to Step 7.2).  If portions of the sample  do not
     pass through the sieve, then the oversize portion  of the
     soil will have to be prepared for extraction by crushing
     the soil to pass the 9.5 mm sieve.

         7.1.2  Determine the percent solids if desired.

     7.2  Procedure when volatiles are not involved -  Enough
solids should be generated for extraction such that the volume
of 1312 extract will be sufficient to support all of the analyses
required.  However, a minimum  sample size of 100 grams shall
be used.  If the amount of extract generated by a single 1312
extract will not be sufficient to perform all of the analyses,
it is recommended that more than one extraction be performed and
the extracts be combined and then aliquoted for analysis.

         7.2.1  Weigh out a representative subsample of the soil and
     transfer to the filter holder extractor vessel.
                                                                     «
         7.2.2  Determine the appropriate extraction fluid to use.
     If the soil is from a site that is east of the Mississippi
     River, extraction fluid #1 should be used.  If the soil is
     from a site that is west of the Mississippi River, extraction
     fluid #2 should be used.  If the soil is to be tested for
     cyanide leachability, extraction fluid #3 should  be used.

                             1312-5                   Revision  0
                                                       December  1988

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Note:  Extraction fluid #3 (reagent water) must be used
when evaluating cyanide-containing soils because leaching
of cyanide-containing soils under acidic conditions may
result in the formation of hydrogen cyanide gas.

    7.2.3  Determine the amount of extraction fluid to add
based on the following formula:

    amount of extraction fluid (mL) = 20 x weight of soil (g)

Slowly add the amount of appropriate extraction fluid to the
extractor vessel.  Close the extractor bottle tightly (it
is recommended that Teflon tape be used to ensure a tight
seal), secure in rotary extractor device, and rotate at 30
+_ 2 rpm for 18 ^+ 2 hours.   Ambient temperature  (i.e. temper-
ature of room in which extraction is to take place) shall
be maintained at 22 _+ 3°C during the extraction period.

Note;  As agitation continues, pressure may build up within the
       extractor bottle for some types of soil  (e.g. limed or
       calcium carbonate containing soil may evolve gases such as
       carbon dioxide).  To relieve excess pressure, the extractor
       bottle may be periodically opened (e.g. after 15 minutes,
       30 minutes, and 1 hour) and vented into a hood.

    7.2.4  Following the 18 _+ 2 hour extraction, the material in
the extractor vessel is separated into its component liquid and
solid phases by filtering through a glass fiber filter.

    7.2.5  Following collection of the 1312 extract it is re-
commended that the pH of the extract be recorded.  The extract
should be immediately aliquoted for analysis and properly
preserved (metals aliquots must be acidified with nitric
acid to pH < 2; all other aliquots must be stored under
refrigeration (4°C) until analyzed).  The 1312 extract
shall be prepared and analyzed according to appropriate
analytical methods.  1312 extracts to be analyzed for metals,
other than mercury, shall be acid digested.

    7.2.6  The contaminant concentrations in the 1312 extract are
compared to thresholds in the clean closure guidance manual.
Refer to Section 8.0 for Quality Control requirements.

7.3 Procedure when volatiles are involved:

    7.3.1 The ZHE device is used to obtain 1312 extracts for
volatile analysis only.  Extract resulting from the use of the
ZHE shall not be used to evaluate the mobility of non-volatile
analytes (e.g. metals, pesticides, etc.).  The ZHE device
has approximately a 500 mL internal capacity.  Although a minimum
sample size of 100 g was required in the Step 7.2 procedure, the
ZHE can only accommodate a maximum of 25 g of solid , due to the
need to add an amount of extraction fluid equal to 20 times the

                        1312-6                   Revision 0
                                                 December 1988

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weight of the soil.  The ZHE is charged with sample only once and
the device is not opened until the final extract has been col-
lected.  Although the following procedure allows for particle-
size reduction during the conduct of the procedure, this could
result in the loss of volatile compounds.  If possible particle-
size reduction (see Step 7.1.1) should be conducted on the
sample as it is being taken (e.g./ particle-size may be reduced
by crumbling).  If necessary particle-size reduction may be
conducted during the procedure.  In carrying out the following
steps, do not allow the soil to be exposed to the atmosphere for
any more time than is absolutely necessary.  Any manipulation of
these materials should be done when cold (4°C) to minimize the
loss of volatiles.  Pre-weigh the evaculated container which
will receive the filtrate (see Step 4.6), and set aside.  If
using a TEDLAR® bag, all air must be expressed from the device.

    7.3.2  Place the ZHE  piston within the body of the ZHE (it
may be helpful first to moisten the piston 0-rings slightly with
extraction fluid).  Adjust the piston within the ZHE body to a
height that will minimize the distance the piston will have to
move once it is charged with sample.  Secure the gas inlet/outlet
flange (bottom flange) onto the ZHE body in accordance with the
manufacturer's instructions.  Secure the glass fiber filter
between the support screens and set aside.  Set liquid inlet/out-
let flange (top flange) aside.

    7.3.3  Quantitatively transfer 25 g of soil to the ZHE.
Secure the filter and support screens into the top flange of the
device and secure the top flange to the ZHE body in accordance
with the manufacturer's instructions.  Tighten all ZHE fittings
and place the device in the vertical position (gas inlet/outlet
flange on the bottom).  Do not attach the extraction collection
device to the top plate.  Attach a gas line to the gas inlet/out-
let valve (bottom flange) and, with the liquid inlet/outlet
valve (top flange) open, begin applying gentle pressure of 1-10
psi to a maximum of 50 psi to force most of the headspace out of
the device.

    7.3.4  With the ZHE in the vertical position, attach a
line from the extraction fluid reservoir to the liquid inlet/
outlet valve.  The line used shall contain fresh extraction
fluid and should be preflushed with fluid to eliminate any air
pockets in the line.  Release qas pressure on the ZHE piston
(from the gas inlet/outlet valve), open the liquid inlet/
outlet valve, and begin transferring extraction fluid  (by
pumping or similar means) into the ZHE.  Continue pumping
extraction fluid into the ZHE until the appropriate amount of
fluid has been introduced into the device.

    7.3.5  After the extraction fluid has been added,  immediate!;
close the inlet/outlet valve and disconnect the extraction fluid
line.  Check the ZHE to ensure that all valves are in  their clos<
positions.  Physically rotate the device in an end-over-end fash


                       1312-7                    Revision 0
                                                 December 1988

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     2 or 3 times.   Reposition the ZHE in the vertical position with
     the liquid inlet/outlet valve on top.   Put 5-10 psi  behind the
     piston (if nesessary) and slowly open  the liquid inlet/outlet
     valve to bleed out any headspace (into a hood)  that  may have
     been introduced due to the addition of extraction fluid.
     This bleedinq  shall be done quickly and shall be stopped  at the
     first appearance of liquid from the valve.  Re-pressurize the
     ZHE with 5-10  psi and check all ZHE fittings to ensure that
     they are closed.

         7.3.6- Place the ZHE in the rotary extractor apparatus (if
     it is not already there) and rotate the ZHE at  30 +  2 rpm for
     18 4^ 2 hours.   Ambient temperature (i.e. temperature of the room
     in which extraction is to occur) shall be maintained at 22 +_ 3°C
     during agitation.

         7.3.7  Following the 18+2 hour agitation  period, check
     the pressure behind the ZHE piston by  quickly opening and closing
     the gas inlet/outlet valve and noting  the escape of  gas.   If the
     pressure has not been maintained (i.e. no gas release observed),
     the device is  leaking.  Check the ZHE  for leaking and redo the
     extraction with a new sample of soil.   If the pressure within
     the device has been maintained, the material in the  extractor
     vessel is separated into its component liquid and solid phases.

         7.3.8  Attach the evacuated pre-weighed filtrate collection
     container to the liquid inlet/outlet valve and  open  the valve.
     Begin applying gentle pressure of 1-10 psi to force  the liquid
     phase into the filtrate collection container.  If no additional
     liquid has passed through the filter in any 2 minute interval,
     slowly increase the pressure in 10-psi increments to a maximum of
     50 psi.  After each incremental increase of 10  psi,  if no additional
     liquid has passed through the filter in any 2 minute interval,
     proceed to the next 10 psi increment.   When liquid flow has
     ceased such that continued pressure filtration  at 50 psi  does
     not result in  any additional filtrate  within any 2 minute period,
     filtration is  stopped.  Close the inlet/outlet  valve, discontinue
     pressure to the piston, and disconnect the filtration collection
     container.

         NOTE; Instantaneous application of high pressure can
               degrade the glass fiber filter and may cause
               premature plugging.
         7.3.9  Following collection of the 1312 extract,  the extract
     should be immediately aliquoted for analysis and stored with
     minimal headspace at 4°C until analyzed.   The 1312 extract will be
     prepared and analyzed according to the appropriate analytical
     ma t-hr>Hc .
8.0  QUALITY CONTROL

     8.1  All data,  including quality assurance data,  should be
                             1312-8                   Revision 0
                                                      December 1988

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maintained and available for reference or inspection.

     8.2  A minimum of one blank (extraction fluid # 1) for every
10 extractions that have been conducted in an extraction vessel
shall be employed as a check to determine if any memory effects
from the extraction equipment are occurring.

     8.3  For each analytical batch (up to twenty samples), it is
recommended that a matrix spike be performed.  Addition of matrix
spikes should occur once the 1312 extract has been generated
(i.e. should not occur prior to performance of the 1312 procedure).
The purpose of the matrix spike is to monitor the adequacy of the
analytical methods used on the 1312 extract and for determining
if matrix interferences exist in analyte detection.

     8.4  All quality control measures described in the appropriate
analytical methods shall be followed.

     8.5  The method of standard addition shall be employed for
each analyte if:  1) recovery of the compound from the 1312
extract is not between 50 and 150%, or 2) if the concentration of
the constituent measured in the extract is within 20% of the
appropriate regulatory threshold.  If more than one extraction is
being run on samples of the same waste (up to twenty samples),
the method of standard addition need be applied only once and the
percent recoveries applied on the remainder of the extractions.

     8.6  Samples must undergo 1312 extraction within the following
time period after sample receipt:  Volatiles, 14 days; Semi-
Volatiles, 40 days; Mercury, 28 days; and other Metals, 180 days.
1312 extracts shall be analyzed after generation and preservation
within the following periods:  Volatiles, 14 days; Semi-Volatiles,
40 days; Mercury, 28 days; and other Metals, 180 days.

9.0  METHOD PERFORMANCE

     9.1 None available.

10.0  REFERENCES

     10. 1  None available.
                             1312-9                   Revision 0
                                                      December 1988

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TABLE 1. — VOiJ^TILE  CONTAMINANTS
Compounds












Ethyl ether. 	 	 	

















CAS No.
67-64-1
107-13-1
71-43-2
71-36-6
75-15-0
56-23-5
108-90-7
67-66-3
107-06-2
75-35-4
141-78-6
100-41-4
60-29-7
78-83-1
67-56-1
75-09-2
78-93-3
108-10-1
630-20-6
79-34-5
127-18-4
108-88-3
71-55-6
79-00-5
79-01-6
75-69-4
76-13-1
75-01-7
1330-20-7

             1312-10
Revision
December
0
1988

-------
             TABLE 2. — SUITABLE ROTARY AGITATION APPARATUS
                                                            1
    Company
Location
Model
Analytical Testing and
  Consulting Services, Inc,

Associated Design and
  Manufacturing Company

Environmental Machine
  and Design, Inc.

IRA Machine Shop and
  Laboratory

Lars Lande Manufacturing
Millipore Corp.
REXNORD
Warrington, PA
  (215) 343-4490

Alexandria, VA
  (703) 549-5999

Lynchburg, VA
  (804) 845-6424

Santurce,  PR
  (809) 752-4004

Whitmore Lake, MI
  (313) 449-4116

Bedford, MA
  (800) 225-3384
Milwaukee, WI
  (414) 643-2850
 4-vessel device
 4-vessel device,
 6-vessel device

 4-vessel device,
 6-vessel device

16-vessel device
10-vessel device
 5-vessel device

 4-vessel ZHE devic
 or 4-one litter
 bottle extractor
 device

 6-vessel device
*Any device that rotates the extraction vessel in an end-over-end
 fashion at 30 + 2 rpm is acceptable.
      TABLE 3. — SUITABLE ZERO-HEADSPACE EXTRACTOR VESSELS
       Company
    Location
   Model No.
Analytical Testing & Con-
 sulting Services, Inc.

Associated Design & Manu-
 facturing Co.

Lars Lande Mfg.
Millipore Corp.
Warrington, PA,
 (215)~343-4490

Alexandria, VA
 (703) 549-5999

Whitmore Lake, MI
 (313) 449-4116

Bedford, MA,
 (800) 225-3384
   C102, Mechanical
    Pressure Devio

   3740-ZHB, Gas
    Pressure Devici

   Gas Pressure
    Device

   SD1 P581 C5, Ga
    Pressure Devic
                             1312-11
                         Revision 0
                         December 1988

-------
             TABLE 4. — SUITABLE ZHE FILTER HOLDERS1
Company
Micro Filtration Systems
Millipore Corp.
Nucleopore Corp.
Location
Dublin, CA
(415) 828-6010
Bedford, MA
(800) 225-3384
Pleasanton, CA
(800) 882-7711
Model
302400
YT30142HW
XX1004700
425910
410400
Size
142 mm
142 mm
47 mm
142 mm
47 mm
     device capable of separating the liquid from the solid phase of
 the soil is suitable, providing that it is chemically compatible with
 the soil and the constitutents to be analyzed.   Plastic devices (not
 listed above) may be used when only inorganic contaminants are of con-
 cern.   The 142 mm size filter holder is recommended.
                TABLE 5.  — SUITABLE FILTER MEDIA
Company
Millipore Corp.
Nucleopore Corp.
Whatman Laboratory
Products, Inc.
Location
Bedford, MA
(800) 225-3384
Pleasanton, CA
(415) 463-2530
Clifton, NJ
(201) 773-5800
Model
AP40
211625
GFF
Sizei
0.7
0.7
0.7
^•Nominal pore size
                             1312-12
Revision 0
December 1988

-------
Figure 1.   Rotary Agi tati
                                   on
   Motor     ,  \
            |L
(30 *  2 rpra),

    "       V
             Extraction Vessel Holder
         1312-13
                                             Revision 0
                                             December 1988

-------
Figure 2.  Zero-Headspace Extraction Vessel
        liquid inlet/outlet valve
                  t
        *	filter
                                        top flange
            waste and
             extraction
              fluid
          I
piston
                                      -V body
                                        VI TON 0-rings
                                     >• bottom flange
   pressurizing gas inlet/outlet valve
                1312-14
                            Revision 0
                            December 1986

-------
                  METHOD  1312
SYNTHETIC ACID PRECIPITATION LEACH TEST FOR SOILS
                  T.J-T.I Hrftn
                "tract!** »f ittl
                 for It k.iri; ».
                   •rfimlct
                7-*
                ••HMtl.t t>
                ai (f«r ..Utll.)
                •': 3) ftltMd..'
                                                      Revi sion
                                                      December
0
1988

-------
                            OSWER DIRECTIVE 9502.00-6D
              INTERIM FINAL
RCRA FACILITY INVESTIGATION (RFI) GUIDANCE
             VOLUME III OF IV
                                             t
     AIR AND SURFACE WATER RELEASES        »
            EPA 530/SW-89-031
                 MAY 1989
         WASTE MANAGEMENT DIVISION
            OFFICE OF SOLID WASTE
     U.S. ENVIRONMENTAL PROTECTION AGENCY

-------
                                ABSTRACT
     On November 8, 1984, Congress enacted the Hazardous and Solid Waste
Amendments (HSWA) to RCRA. Among the most significant provisions of HSWA are
§3004(u), which requires corrective action for releases  of hazardous  waste or
constituents from  solid waste management units at hazardous waste treatment,
storage and disposal  facilities seeking final RCRA permits; and §3004(v), which
compels corrective action for releases that have migrated beyond the facility
property boundary.  EPA will be promulgating rules to implement the corrective
action  provisions of HSWA, including requirements for release investigations and
corrective measures.
\.                                                                        t
     This document,  which is presented in four volumes, provides guidance tp
regulatory agency  personnel on overseeing owners or operators of hazardous wastp
management facilities in the conduct of the second phase of the RCRA Corrective
Action  Program, the RCRA Facility Investigation (RFI). Guidance is provided for the
development and performance of an investigation by the facility owner or operator
based on determinations made by the regulatory agency as expressed in the
schedule of a permit or  in an enforcement order issued under §3008(h), §7003,
and/or  §3013. The purpose of the RFI is to obtain information to fully characterize
the nature,  extent and rate of migration of releases of hazardous  waste or
constituents and  to  interpret this information to determine  whether interim
corrective measures and/or a Corrective Measures Study may be necessary.

-------
                               DISCLAIMER
     This document is intended to assist Regional and State personnel in exercising
the discretion conferred by regulation in developing requirements for the conduct
of RCRA Facility Investigations (RFIs) pursuant to 40 CFR 264. Conformance with this
guidance is expected to result in the development of RFIs that meet the regulatory
standard of adequately detecting and  characterizing the nature and extent of
releases.  However, EPA will not necessarily limit acceptable RFIs to those that
comport with the guidance set forth  herein.  This document is not a regulation (i.e.,
it does not establish a standard of conduct which has the force of law) and should
not be used as such. Regional and State personnel must exercise their discretion in
using this guidance document as well as other relevant information in determining
whether an RFI meets the regulatory standard.                                t
                                                                         ?
     Mention of company or product names in  this document should not be
considered as an endorsement by the U.S. Environmental Protection Agency.

-------
              RCRA FACILITY INVESTIATION (RFI) GUIDANCE
                            VOLUME III
                  AIR AND SURFACE WATER RELEASES
                        TABLE OF CONTENTS

SECTION                                                     PAGE
ABSTRACT                                                        i
DISCLAIMER                                                       ii
TABLE OF CONTENTS                                               iii
TABLES                                                         xi
FIGURES                                                       xiii
LIST OF ACRONYMS                                               xiy
                               in

-------
                     VOLUME III CONTENTS (Continued)
SECTION                                                            PAGE
12.0  AIR                                                            12-1
   12.1   OVERVIEW                                                   12-1
   12.2   APPROACH FOR CHARACTERIZING RELEASES TO AIR               12-2
      12.2.1   General Approach                                       12-2
         12.2.1.1  Initial Phase                                         12-13
           12.2.1.1.1   Collect and Review Preliminary                  12-13
                      Information
           12.2.1.1.2   Conduct Screening Assessment                  12-14
         12.2.1.2  Subsequent Phases                                   12-15
*          12.2.1.2.1   Conduct Emission Monitoring                    12-16
           12.2.1.2.2   Confirmatory Air Monitoring                    12-17 ^
   12.3   CHARACTERIZATION OF THE CONTAMINANT                    12-20
         SOURCE AND THE ENVIRONMENTAL SETTING
      12.3.1   Waste Characterization                                 12-21
         12.3.1.1  Presence of Constituents                             12-21
         12.3.1.2  Physical/Chemical Properties                          12-21
      12.3.2   Unit Characterization                                   12-27
         12.3.2.1  Type of Unit                                         12-27
         12.3.2.2  Size of Unit                                         12-33
         12.3.2.3  Control Devices                                      12-34
         12.3.2.4  Operational Schedules                               12-35
         12.3.2.5  Temperature of Operation                            12-35
                K-
      12.3.3   Characterization of the Environmental Setting             12-36
         12.3.3.1  Climate                                             12-36
         12.3.3.2  Soil Conditions                                      12-38
         12.3.3.3  Terrain                                             12-38
         12.3.3.4  Receptors                                           12-39
      12.3.4   Review of Existing Information                           12-39
                                   IV

-------
                     VOLUME III CONTENTS (Continued)
SECTION                                                            PAGE
      12.3.5   Determination of Reasonable Worst Case"                12-41
              Exposure Period
   12.4  AIR EMISSION MODELING                                      12-43
      12.4.1   Modeling Applications                                  12-43
      12.4.2   Model Selection                                        12-44
        12.4.2.1  Organic Emissions                                   12-44
        12.4.2.2  Paniculate Emissions                                 12-46
      12.4.3   General Modeling Considerations                        12-47
   12.5  DISPERSION MODELING                                       12-48
      12.5.1   Modeling Applications                                  12-48
      12.5.2   Model Selection                                        12-50 ?
        12.5.2.1  Suitability of Models                                 12-51
        12.5.2.2  Classes of Models                                    12-52
        12.5.2.3  Levels of Sophistication of Models                     12-53
        12.5.2.4  Preferred Models                                    12-54
      12.5.3   General Modeling Considerations                        12-56
   12.6  DESIGN OF A MONITORING PROGRAM TO                       12-58
        CHARACTERIZE RELEASES
      12.6.1   Objectives of the Monitoring Program                     12-58
      12.6.2   Monitoring Constituents and Sampling                    12-59
              Considerations
      12.6.3   Meteorological Monitoring       «                      12-60
        12.6.3.1 ^Meteorological Monitoring Parameters                 12-60
        12.6.3.2 "Meteorological Monitor Siting                        12-62
      12.6.4   Monitoring Schedule                                   12-64
        12.6.4.1  Screening Sampling                                  12-64
        12.6.4.2  Emission Monitoring                                 12-65
        12.6.4.3  Air Monitoring                                      12-68
        12.6.4.4  Subsequent Monitoring                              12-69

-------
                     VOLUME III CONTENTS (Continued)
SECTION                                                            PAGE
      12.6.5   Monitoring Approach                                   12-69
         12.6.5.1  Source Emissions Monitoring                          12-71
         12.6.5.2  Air Monitoring                                      12-72
      12.6.6   Monitoring Locations                                   12-73
         12.6.6.1  Upwind/Downwind Monitoring Location               12-73
         12.6.6.2  Stack/Vent Emission Monitoring                       12-77
         12.6.6.3  Isolation Flux Chambers                              12-77
   12.7   DATA PRESENTATION                                        12-78
      12.7.1   Waste and Unit Characterization                         12-78.
 i
      12.7.2   Environmental Setting Characterization                   12-79t
      12.7.3   Characterization of the Release                          12-80*
   12.8   FIELD METHODS                                             12-85
      12.8.1   Meteorological Monitoring                              12-86
      12.8.2   Air Monitoring                                         12-86
         12.8.2.1  Screening Methods                                  12-89
         12.8.2.2  Quantitative Methods                                12-93
            12.8.2.2.1   Monitoring Organic Compounds in               12-93
                       Air
              12.8.2.2.1.1 Vapor-Phase Organics                       12-94
              12.8.2.2.1.2 Particulate Organics                        12-111
            12.8.2.2.2   Monitoring Inorganic Compounds in            12-113
                       Air
                SL
              12,8.2.2.2.1 Particulate Metals                          12-113
              12.8.2.2.2.2 Vapor-Phase Metals                        12-114
              12.8.2.2.2.3 Monitoring Acids and Other                 12-120
                         Compounds in Air
      12.8.3   Stack/Vent Emission Sampling                          12-121
         12.8.3.1  Vapor Phase and Particulate Associated               12-122
                 Organics
                                   VI

-------
                   VOLUME III CONTENTS (Continued)
SECTION                                                        PAGE
        12.8.3.2  Metals                                         12-127
   12.9  SITE REMEDIATION                                       12-129
   12.10 CHECKLIST                                             12-131
   12.11 REFERENCES                                            12-133
                                 vti

-------
                    VOLUME III CONTENTS (Continued)
SECTION                                                           PAGE
13.0   SURFACE WATER                                               13-1
   13.1  OVERVIEW                                                 13-1
   13.2  APPROACH FOR CHARACTERIZING RELEASES TO                  13-2
        SURFACE WATER
      13.2.1    General Approach                                      13-2
      13.2.2    Inter-media Transport                                  13-8
   13.3  CHARACTERIZATION OF THE CONTAMINANT                    13-8
        SOURCE AND THE ENVIRONMENTAL SETTING
      13.3.1    Waste Characterization                                 13-8
      13.3.2    Unit Characterization                                  13-17 '
        13.3.2.1 Unit Characteristics                                 13-17 *
        13.3.2.2 Frequency of Release                               13-18
        13.3.2.3 Form of Release                                    13-19
      13.3.3    Characterization of the Environmental Setting             13-19
        13.3.3.1 Characterization of Surface Waters                    13-20
           13.3.3.1.1   Streams and Rivers                            13-20
           13.3.3.1.2   Lakes and Impoundments                      13-22
           13.3.3.1.3   Wetlands                                    13-24
           13.3.3.1.4   Marine Environments                          13-25
        13.3.3.2 Climatic and Geographic Conditions                   13-26
      13.3.4    Sources of Existing Information                          13-27
   13.4  DESIGN QF A MONITORING PROGRAM TO                      13-28
        CHARACTERIZE RELEASES
      13.4.1    Objectives of the Monitoring Program                    13-29
        13.4.1.1 Phased Characterization                             13-30
        13.4.1.2 Development of Conceptual Model                    13-31
        13.4.1.3 Contaminant Concentration vs                       13-31
                Contaminant Loading
        13.4.1.4 Contaminant Dispersion Concepts                     13-33
                                  VIII

-------
                    VOLUME III CONTENTS (Continued)
SECTION                                                             PAGE
         13.4.1.5  Conservative vs Non-Conservative Species               13-36
      13.4.2   Monitoring Constituents and Indicator                    13-36
              Parameters
         13.4.2.1  Hazardous Constituents                              13-36
         13.4.2.2  Indicator Parameters                                 13-37
      13.4.3   Selection of Monitoring Locations                        13-42
      13.4.4   Monitoring Schedule                                    13-44
      13.4.5   Hydrologic Monitoring                                  13-46
      13.4.6   The Role of Biomonitoring                               13-46
         13.4.6.1  Community Ecology Studies                           13-47{
         13.4.6.2  Evaluation of Food Chain/Sensitive Species              13-48;
                 Impacts
         13.4.6.3  Bioassay                                            13-49
   13.5   DVTA MANAGEMENT AND PRESENTATION                      13-50
      13.5.1   Waste and Unit Characterization                         13-50
      13.5.2   Environmental Setting Characterization                   13-51
      13.5.3   Characterization of the Release                           13-51
   13.6   FIELD AND OTHER METHODS                                  13-53
      13.6.1   Surface Water Hydrology                                13-53
      13.6.2   Sampling of Surface Water, Runoff, Sediment              13-55
              and Biota
         13.6.2.r Surface Water                                       13-55
           13.6.2M.1   Streams and Rivers                             13-55
           13.6.2.1.2   Lakes and Impoundments                       13-56
           13.6.2.1.3   Additional Information                         13-57
         13.6.2.2  Runoff Sampling                                     13-58
         13.6.2.3  Sediment                                           13-59
         13.6.2.4  Biota                                               13-62
                                   IX

-------
                    VOLUME III CONTENTS (Continued)
SECTION                                                          PAGE
      13.6.3    Characterization of the Condition of the                  13-63
              Aquatic Community
      13.6.4    Bioassay Methods                                    13-66
   13.7  SITE REMEDIATION                                         13-67
   13.8  CHECKLIST                                                13-68
   13.9  REFERENCES                                              13-71

APPENDICES
Appendix G:    Draft Air Release Screening Assessment
              Methodology
Appendix H:    Soil Loss Calculation

-------
                            TABLES (Volume ill)
NUMBER                                                          PAGE
   12-1     Example Strategy for Characterizing Releases to Air          12-3
   12-2     Release Characterization Tasks for Air                      12-5
   12-3     Parameters and Measures for Use in Evaluating Potential      12-22
           Releases of Hazardous Waste Constituents to Air
   12-4     Physical Parameters of Volatile Hazardous Constituents       12-25
   12-5     Physical Parameters of PCB Mixtures                        12-26
   12-6     Summary of Typical Unit Source Type and Air Release Type    12-28
   12-7     Typical Pathways for Area Emission Sources                  12-49
   12-8     Preferred Models for Selected Applications in Simple         12-55
           Terrain
 r»-
   12-9     Recommended Siting Criteria to Avoid Terrain Effects        12-63
   12-10   Applicable Air Sampling Strategies by Source Type           12-70
   12-11    Typical Commercially Available Screening Techniques        12-90
           forOrganicsin Air
   12-12   Summary of Selected Onsite Organic Screening              12-92
           Methodologies
   12-13A  Summary of Candidate Methodologies for Quantification of  12-95
           Vapor Phase Organics
   12-13B  List of Compound Classes Referenced in Table 12-15A        12-97
   12-14   Sampling and Analysis Techniques Applicable to Vapor       12-98
           Phase Organics
   12-15   Compounds Monitored Using EMSL-RTPTenax Sampling      12-102
           Protocols
   12-16   Summary Listing of Organic Compounds Suggested for       12-106
           Collection With a Low Volume Polyurethane Foam Sampler
           and Subsequent Analysis With an Electron Capture Detector
           (GC/ECD)
                                    XI

-------
                      TABLES (Volume III • Continued)

NUMBER                                                         PAGE
   12-17    Summary Listing of Additional Organic Compounds          12-107
           Suggested for Collection With a Low Volume Polyurethane
           Foam Sampler

   12-18    Sampling and Analysis Methods for Volatile Mercury          12-115

   12-19    Sampling and Analysis of Vapor State Trace Metals           12-118
           (Except Mercury)

   12-20    Sampling Methods for Toxic and Hazardous Organic          12-123
           Materials From Point Sources

   12-21    RCRA Appendix VIII Hazardous Metals and Metal             12-128
           Compounds

   13-1     Example Strategy for Characterizing Releases to             13-3
           Surf ace Water

   13-2     Release Characterization Tasks for Surface Water             13-7

   13-3     Important Waste and Constituent Properties Affecting        1 3-9
           Fate and Transport in a Surface Water Environment

   13-4     General Significance of Properties and Environmental        13-16
           Processes for Classes of Organic Chemicals Under
           Environmental Conditions
                                   XII

-------
                           FIGURES (Volume III)
NUMBER                                                          PAGE
   12-1     Release Characterization Strategy for Air-Overview         12-6
   12-2     Conduct Screening Assessments-Overview                 12-7
   12-3     Conduct Emission Monitoring-Overview                   12-8
   12-4     Conduct Confirmatory Air Monitoring                      12-9
   12-5     Evaluation of Modeling/Monitoring Results                 12-10
   12-6     Example Air Monitoring Network                         12-74
   12-7     Example of Downwind Exposures at Air Monitoring Stations  12-84
   13-1     Qualitative Relationship Between Various Partitioning       13-11
           Parameters
   13-2     Typical Lake Cross Section                                13-23    t
                                                                         f
                                   xiii

-------
                           LIST OF ACRONYMS
AA
Al
ASCS
ASTM
BCF
BOD
CAG
CPF
CBI
CEC
CERCLA

CFR
CIR
CM
CMI
CMS
COD
COLIWASA
DNPH
DO
DOT
ECD
EM
EP
EPA
FEMA
FID
Foe
FWS
GC
GC/MS
GPR
HEA
HEEP
HPLC
HSWA
HWM
ICP
ID
Kd
Koc
Kow
LEL
MCL
MM5
MS/MS
NFIP
NIOSH
NPDES
OSHA
Atomic Absorption
Soil Adsorption Isotherm Test
Agricultural Stabilization and Conservation Service
American Society for Testing and Materials
Bioconcentration Factor
Biological Oxygen Demand
EPA Carcinogen Assessment Group
Carcinogen Potency Factor
Confidential Business Information
Cation Exchange Capacity
Comprehensive Environmental Response, Compensation, and
Lability Act
Code of Federal Regulations
Color Infrared
Corrective Measures
Corrective Measures Implementation
Corrective Measures Study
Chemical Oxygen Demand
Composite Liquid Waste Sampler
Dinitrophenyl Hydrazine                                (
Dissolved Oxygen                                      ?
Department of Transportation
Electron Capture Detector
Electromagnetic
Extraction Procedure
Environmental Protection Agency
Federal Emergency Management Agency
Flame lonization Detector
Fraction organic carbon in soil
U.S. Fish and Wildlife Service
Gas Chromatography
Gas Chromatography/Mass Spectroscopy
Ground Penetrating Radar
Health and Environmental Assessment
Health and Environmental Effects Profile
High Pressure Liquid Chromatography
Hazardous and Solid Waste Amendments (to RCRA)
Hazardous Waste Management
Inductively Coupled (Argon) Plasma
Infrared Detector
Soil/Water Partition Coefficient
Organic Carbon Absorption Coefficient
Octanol/Water Partition Coefficient
Lower Explosive Limit
Maximum Contaminant Level
Modified Method 5
Mass Spectroscopy/Mass Spectroscopy
National Flood Insurance Program
National Institute for Occupational Safety and Health
National Pollutant Discharge Elimination  System
Occupational Safety and Health Administration
                                  XIV

-------
                      LIST OF ACRONYMS (Continued)
OVA
PID
pKa
ppb
ppm
PUF
PVC
QA/QC
RCRA
RFA
RfD
RFI
RMCL
RSD
SASS
SCBA
SCS
SOP
SWMU
TCLP
TEGD
TOC
TOT
TOX
uses
USLE
UV
VOST
VSP
WQC
Organic Vapor Analyzer
Photo lonization Detector
Acid Dissociation Constant
parts per billion
parts per mi 11 ion
Polyurethane Foam
Polyyinyl Chloride
Quality Assurance/Quality Control
Resource Conservation and Recovery Act
RCRA Facility Assessment
Reference Dose
RCRA Facility Investigation
Recommended Maximum Contaminant Level
Risk Specific Dose
Source Assessment Sampling System
Self Contained Breathing Apparatus
Soil Conservation Service
Standard Operating Procedure
Solid Waste Management Unit
Toxicity Characteristic Leaching Procedure
Technical Enforcement Guidance Document (EPA, 1986)
Total Organic Carbon
Time of travel
Total Organic Halogen
United States Geologic Survey
Universal Soil Loss Equation
Ultraviolet
Volatile Organic Sampling Train
Vertide Seismic Profiling
Water Quality Criteria
                                   xv

-------

-------
                                 SECTION 12

                                    AIR

12.1      Overview

     The objective  of an  investigation of a release to air is to characterize the
nature, extent, and rate of migration of the  release of  hazardous waste or
constituents to that  medium.   This is done by  characterizing  long-term  air
concentrations (commensurate with the long-term exposures which are the basis for
the health and environmental criteria presented in Section 8) associated with unit
releases of hazardous wastes or constituents to air. This section provides:

     •    An example strategy for characterizing  releases to air, which includes'
          characterization  of the source and the environmental setting  of the*
          release, and conducting a monitoring and/or modeling, program which
          will characterize the release itself;

     •    Formats for data organization and presentation;

     •    Modeling and field methods which may be used in the investigation; and

     •    A  checklist  of  information  that may  be   needed   for  release
          characterization.

     The exact type and amount of information  required  for sufficient release
characterization will be site-specific and should be determined through interactions
between the regulatory agency and the facility owner or operator during the RFI
process. This guidance does not define the specific data needed in all Instances; it
identifies possible information necessary to perform release characterizations and
methods for obtaining this information.  The RFI Checklist, presented at the end of
this section, provides a tool  for  planning and tracking information for release
characterization.  This list is not a list of requirements for all  releases to air.  Some
release investigations will involve the collection of only a subset of the items listed,
while other releases may involve-the collection of additional data.
                                    12-1

-------
     Case studies 25 and 26 in Volume IV (Case Study Examples) illustrate several of
the air investigation concepts discussed in this section.

12.2     Approach for Characterizing Releases to Air

12.2.1    General Approach

     The intent of the air release investigation is to determine actual or potential
effects at the facility property boundary.   This differs from the other media
discussed in this Guidance.   During the health and  environmental assessment
process  for the air medium  (see Section  8), the decision as to whether interim
corrective measures or a Corrective Measures  Study will be necessary is  based on
actual or potential effects at the facility property boundary.
 "-                                                                        »
     Characterization of releases from waste management units to air may  be.
approached in  a tiered or phased fashion as described in Section 3.  The key
elements to this approach are shown in Table 12-1. Tasks for implementing the
release characterization strategy for releases to air are summarized in Table  12-2.
An overview of the release characterization  strategy for air is illustrated in Figures
12-1 through 12-5.

Two major elements can be derived from this strategy:

     •   Collection  and review of data  to be used for characterization of the
         source of the air release and the  environmental setting for this source.
         Source characterization will include obtaining information on the unit
         operating conditions and configuration, and may entail a sampling and
         analytical effort to characterize the waste material in the unit or the
         incoming waste streams.  This effort will lead to development of a
         conceptual model of the release that provides a working hypothesis of
         the release mechanism, transport  pathway/mechanism,  and  exposure
         route (if any), which can be used to guide the investigation.

     •   Development and implementation of  modeling  and/or monitoring
         procedures to be used for  characterization of the release (e.g., from a
                                    12-2

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                               TABLE 12-1

        EXAMPLE STRATEGY FOR CHARACTERIZING RELEASES TO AIR*
                             INITIAL PHASE

1.    Collect and review existing information on:
2.
         Waste
         Unit
         Environmental setting (e.g., climate, topography)
         Contaminant releases, including inter-media transport
         Receptors at and beyond the facility property boundary

     Identify additional information necessary to fully characterize release:

         Waste
         Unit
         Environmental setting (e.g., climate, topography)
         Contaminant releases, including inter-media transport
         Receptors at and beyond the facility property boundary

3.    Conduct screening assessments:

         Formulate conceptual model of release
         Determine monitoring/modeling program objectives
         Obtain source characterization data needed for modeling input
         Select release constituent surrogates
         Calculate emission estimates based on emission rate screening
         modeling results
         Calculate concentration estimates based on dispersion screening
         modeling results
         Compare results to health based criteria
         Conduct screening monitoring at source (as warranted)
         Perform sensitivity analysis of modeling input/output
         Obtain additional waste/unit data as needed for refined modeling
         Consider conduct of more refined emission/dispersion modeling

4.    Collect, evaluate and report results:

         Account for unit/waste temporal and spatial variability and modeling
         input/output uncertainties
         Determine completeness and adequacy of screening assessment
         results
         Evaluat^ potential for inter-media contaminant transfer
         Summar4ze and present results in appropriate format
         Determine if monitoring program objectives were met
         Compare screening results to "health and environmental criteria and
         identify and respond to emergency situations and identify priority
         situations that may warrant interim corrective measures - Notify
         regulatory agency
         Determine whether the conduct of subsequent release charaterization
         phases are necessary to obtain more refined concentration estimates
                                  12-3

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                         TABLE 12-1 (continued)

        EXAMPLE STRATEGY FOR CHARACTERIZING RELEASES TO AIR*


                    SUBSEQUENT PHASES (if necessary)

.1.    Conduct emission monitoring and dispersion modeling if necessary:

         Conduct onsite meteorological monitoring if representative data are
         not available for dispersion modeling input
         Conduct emission rate monitoring
         Conduct dispersion modeling using emission rate monitoring data as
         input
         Evaluate results and determine need for confirmatory air monitoring

2.    Conduct confirmatory air monitoring if necessary:

         Develop monitoring procedures
         Conduct initial monitoring
         Conduct additional monitoring if additional information is necessary
         to characterize the release

3.    Collect, evaluate and report results:

         Account for  source and meteorological  data  variability  during
         modeling and monitoring program
         Evaluate long-term representativeness of air monitoring data
         Apply dispersion models as appropriate to aid in data evaluation and
         to provide concentration estimates at the facility property boundary
         Compare monitoring results to health and environmental criteria and
         identify and respond to  emergency situations and identify  priority
         situations that may  warrant interim  corrective  measures - Notify
         regulatory agency
         Determine completeness and adequacy of collected data
         Summarize and present data in appropriate format
     - .   Determine  if  modeling and  monitoring locations, constituents, and
         frequency were adequate to characterize release (nature, extent, and
         rate)
         Determine if monitoring/modeling program objectives were met
         Identify additional information needs, if necessary
         Determine need to expand modeling and monitoring program
         Evaluate, potential role of  inter-media transport
     The  potential  for  inter-media  transport of contamination  should be
     evaluated continually throughout the investigation.
                                  12-4

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                                        TABLE 12-2
                      RELEASE CHARACTERIZATION TASKS FOR AIR
   Investigatory Tasks
Investigatory Techniques
   Data Presentation
    Formats/Outputs
Waste/Unit Characterization

    Identification of waste
    constituents and properties
   •Prioritization of air emission
    constituents

    Identification of unit
    characteristics which may
    promote an air release	
See Section 3, 7 and Volume I,
Appendix B List 2; Section 12.3,
Section 12.4, Appendix F

Waste sampling and
characterization

See Section 7, Section 12.3,
Section 12.4, Appendix F
Listing of potential release
constituents
Listing of target air emission
constituents for monitoring

Description of the unit
Environmental Setting
Characterization

    Definition of climate
    Definition of site-specific
    meteorological conditions
    Definition of soil conditions
    to characterize emission
    potential for paniculate
    emissions and for certain
    units (e.g., landfills and land
    treatment) for gaseous
    emissions

    Definition of site-specific
    terrain
    Identification of potential
    air-pathway receptors
Climate summaries for regional
National Weather Service
stations (may require onsite
meteorological monitoring
survey)

Onsite meteorological
monitoring concurrent with air
monitoring

See Section 9
See Section 7. 9 and Appendix A
(Volume 1) of RFI and recent
aerial photographs and U.S.
Geoigoical Survey maps

Census data, area surveys, recent
aerial photographs and U.S.
Geological Survey topographic
maps	'	
Wind roses and statistical
tabulations for parameters of
interest
Wind roses and tabulations for
parameters of interest


Soil physical properties (e.gJ,
porosity, organic matter
content)                "
Topographic map of site area
Map with  identification of
nearby populations and
buildings
Release Characterization

    Emission rate modeling


    Dispersion modeling
    Emission rate monitoring
   Air monitoring
Air emission models as discussed
in Section 12.4

Atmospheric dispersion models
as discussed in Section 12.5
Direct emission source tests for
point sources, isolation flux
chamber for area sources or
onsite air monitoring (Section
12.8)

Upwind/downwind air
monitoring for "release
mapping"
Unit-specific and constituent-
specific emission rates

Air concentration estimates at
facility property boundary
(tabular summaries or graphical
presentations which may include
release concentration isopleths)

Listing of emission rate
monitoring results
Air concentration estimates at
facility property boundary
(tabular summaries or graphical
presentations which may include
release concentration isopleths)
                                            12-5

-------
                      FIGURE 12-1
RELEASE CHARACTERIZATION STRATEGY FOR AIR-OVERVIEW
Collect and Review
Preliminary Information
Waste/Unit
Characteristics
Historical
Air Monitoring/Modeling
Data
Environmental
Characteristics
          Develop Conceptual Model of Release
                        Evalute
                     Hazard Index/
                      RFI Decision
                        Points
                                                                INITIAL
                                                                PHASE
             Conduct Screening Assessments
             (Emphasis on Emission Modeling)
                         Evalute
                      Hazard Index/
                       RFI Decision
                         Points
              Conduct Emission Monitoring
                         Evalute
                      Hazard Index/
                       RFI Decision
                         Points
              Confirmatory Air Monitoring
                         Evalute
                      Hazard Index/
                       RFI Decision
                         Points
                 1
  Information Sufficient
    to Characterize Air
  Release as Significant
      Information Sufficient
        to Characterize Air
      Release as Insignificant
                                     SUBSEQl


                                        PHAS
   Corrective Measures
 Study/Interim Corrective
         Measure
12-6
No Further Action
    Required

-------
                                         FIGURE 12-2
                     CONDUCT SCREENING ASSESSMENTS - OVERVIEW

                                        Collect and Review
                                     Preliminary Information
     Consider Refined
    Emission/Dispersion
        Modeling
       Conduct Screening Modeling

Obtain source characterization data
Select release constituent surrogates
Calculate emission estimates based on emission
modeling results
Calculate concentration estimates based on
dispersion modeling results
Compare results to health based criteria
      Obtain Additional
      Waste/Unit Data
                                                                       Conduct Preliminary
                                                                       Monitoring at Source
                                                                         (discretionary)
                                 Conduct Model Sensitivity Analysis, Evaluate Input
                                 Data and Model Accuracy to Determine Uncertainty
                                                   Factor (U?)
                                      No
                    (Optional steps)
              Screening
             Assessment
               Results
               dequate
                                                   Evaluate
                                                Hazard Index/
                                                 RFI Decision
                                                   Points
orrective Measure Study/
:enm Corrective Measures
     Conduct Emission Monitoring
           (See Figure 12-3)
   No Further
Action Required
                                             12-7

-------
                                          FIGURE 12-3
                       CONDUCT EMISSION MONITORING - OVERVIEW

                                     Screening Assessments
                                        Representative
                                        Meteorological
                                        Data Available
                      No
                                                ves
                                                                           Conduct
                                                                        Meteorological
                                                                          Monitoring
                                       Conduct Emissions
                                       Rate Monitoring
                  Direct Emissions
                  Source Testing
                  for Point Sources
    Isolation Flux
     Chamber
  for Area Sources
                        t
  Onsite
    Air
Monitoring
                                           Conduct
                                     Dispersion Modeling
Corrective Measures Study/
Interim Corrective Measures
                                          Evaluate
                                        Hazard Index/
                                         RFI Decision
                                           Points
Conduct Confirmatory
   Air Monitoring
  (See Figure 12-4)
              No Further
           Action Required
                                              12-8

-------
                                       FIGURE 12-4
                      CONDUCT CONFIRMATORY AIR MONITORING

                                Emission Monitoring Results
Screening Develop Monitoring
Air Samples Procedures
*
Select Monitoring
Approach/Procedures
t
Monitor _,
Placement*
*
Conduct Initial Monitoring
*
1 I
Air Meteorological
Monitoring Monitoring
1 |
*
Ca
>
-*-
-^~
ndidate Air Emission
Constituents (see
Appendix B, List 2)

Site
Meteorological
Characterization

Dispersion
Modeling

*e As close to source as
possible to increase
potential for release
detection and
quantification
e At actual receptors' at or
beyond the facility*
property boundaivto
support health ana
environmental
assessment (if oracticaO
                                Collect and Evaluate Results
                                           i

t
Waste/Unit
Characterization
Data Summaries
Summarize Data/
Perform Dispersion
Modeling**
t
t
Air/Meteorological
Monitoring Data
Summaries
1
conce
recep
beyor
prop*
neces
t
Modeling Data
Summaries
i.
                              ** To Estimate
                                 concentrations at actual
                                 receptor locations at or
                                 beyond the facility
                                 property boundary (as
                             Additional Monitoring (if necessary)
          f
rective Measures Study/Interim
   Corrective Measures
  Evaluate
Hazard Index/
 RFI Decision
   Points
                               No Further Action
                                   Required
                                           12-9

-------
                              FIGURE 12-5
             EVALUATION OF MODELING/MONITORING RESULTS

                      Modeling/Monitoring Results
                                  i
                               Compute
                             Hazard Index
                                  (HI)
                                 I
                              Determine
                         Modeling/Monitoring
                          Uncertainty Factors
                                (±UF)*
                               Evaluate
                                Hazard
                               Index/RFI
                               Decision
                                Poin
        I  HI.>UF**  I    |UF>HI.>1/UF*** I     |HK1/UF****|
        •••^•^•^•^••••J    ^^,^^^^^,^^^l^^m^mlm^     ^^^^m*mi^mmm^l
        Information is
         sufficient to
         characterize
          release as
          significant
  Information is
  not sufficient
       to
  characterize
   the release
                                  7
Information is
 sufficient to
 characterize
the release as
 insignificant
                           7
      Corrective Measures
         Study/Interim
      Corrective Measures
Additional Release
 Characterization
   Assessments
    Necessary
      No
    Further
    Action
   Required
*      UnctrtairTty Factor assumed to be J> 1.0

**     Hl>1 Generally used for evaulation of confirmatory air monitoring
       results.

***    This alternative is generally not used to evaluate confirmatory air
       monitoring results. However, additional air monitoring may be
       warranted if monitoring objectives were not acheived. Confirmatory air
       monitoring will generally be conducted during worst-case long-term
       emission/dispersion conditions. Therefore, this facilitates the use of
       more rigorous evaluation criteria for this final air release
       characterization step prior to RFI decisionmaking.

****   HK1 Criterion generally used for evaluation of confirmatory air
       monitoring results.
                                 12-10

-------
          unit or contaminated soil).  Utilizing a phased approach, the air release is
          characterized in  terms of  the types  and  amounts  of hazardous
          constituents  being emitted,  leading to  a  determination of actual  or
          potential exposure at the facility property boundary. This may involve
          emission  modeling (to  estimate   unit-specific  emission  rates),  air
          monitoring  (to  determine  concentrations  at the  facility property
          boundary), emission monitoring (monitoring at the source to determine
          emission rates), and dispersion modeling  (to estimate  concentrations at
          the  facility property boundary).  A phased  approach  utilizing both
          modeling  and monitoring  may not always  be  necessary to  achieve
          adequate release charterization.

     As indicated in  Section 1 of this Guidance (See Volume I), standards for the
control and monitoring of air emissions at hazardous waste treatment, storage and
disposal (ISO)  facilities are being developed  by the Agency  pursuant to HSWA'
Section  3004(n).   These  standards will address specific  methodologies  and
regulatory requirements for the identification and control of air  releases at TSD
facilities.   The  Guidance  provided  herein  is intended to provide  interim
methodologies and procedures for the identification and delineation of significant
air releases. In particular, the Guidance addresses those releases which may pose an
existing and significant hazard to human health  and the environment, and thus,
should be addressed without delay, i.e., prior to the  issuance of the Section 3004(n)
regulations.

     The RFI release characterization strategy for air includes several decision points
during  the  characterization process to  evaluate the  adequacy of available
information and to determine an appropriate course of action from the following
alternatives (as illustrated in Figures 12-1 through 12-5).
                  SL
•    Information is sufficient to characterize  the air release as significant and a
     Corrective Measures Study/Interim Corrective Measures is warranted.

•    Information is  sufficient to  characterize the air release  as insignificant,
     therefore, no further air assessments are required.
                                   12-11

-------
•    Information is not sufficient to characterize the air release, therefore further
     release characterization is warranted.

     Criteria for decisionmaking  involves consideration  of the  uncertainty
associated with release  characterization results (modeling/monitoring), which is
facilitated by use of a Hazard Index as illustrated in Figure 12-5. The Hazard Index is
defined as the ratio of exposure concentration levels or estimates, to specific health
criteria  for an individual  constituent or a mixture of constituents with  similar
potential health impacts. Further guidance on the computation and application of
the Hazard Index is provided in Section 8.

     The uncertainty associated with concentration estimates based on air pathway
modeling and monitoring results is factored into the decision making effort
through use of uncertainty analyses.  A primary  component of the uncertainty
analysis is the accuracy of the modeling and/or monitoring approach utilized for the
release characterization. Model-specific and monitoring method-specific accuracies
should be used as available for the uncertainty analysis.  The quality of the input
data to models is another important component of the uncertainty analysis that
should be accounted for.  Generally, conduct of a model sensitivity analysis (i.e.,
varying the values of input parameters based on their uncertainty range to evaluate
the effect on model output), will provide a quantitative basis to characterize input
data quality. This step is particularly important for some unit-specific models.  For
example, the spatial variability of wastes at a landfill and the uncertainty of other
input parameters (e.g., soil porosity) can significantly affect the overall uncertainty
associated with emission modeling results.

     As concentration measurements or estimates at the facility property boundary
become  available, both within and at the conclusion  of discrete investigation
phases, they shoujd be reported to the regulatory agency as  directed.   The
regulatory agency will compare the concentrations with  applicable health  and
environmental criteria to determine the need for (1) interim corrective  measures;
and/or (2) a Corrective Measures  Study.  In  addition, the  regulatory agency  will
evaluate the data with  respect  to adequacy and completeness to determine the
need for any additional characterization efforts.  The health and environmental
criteria and a general discussion of how the regulatory agency will apply them are
                                   12-12

-------
provided in Section 8.  A flow diagram illustrating RFI Decision Points is provided in
Section 3 (See Figure 3-2).

     Notwithstanding the above process, the owner or operator has a continuing
responsibility to identify and respond to emergency situations and to define priority
situations that may warrant interim corrective measures.  For these situations, the
owner or operator is advised to follow the RCRA Contingency Plan requirements
under 40 CFR Part 264, Subpart D and Part 265, Subpart D.

     The strategy for characterizing releases to air consists of an initial phase and, if
necessary, subsequent phases, as illustrated  in Table  12-1  and Figure  12-1.
Additional   phases  may  not  be  needed   depending   on  the  site-specific
modeling/monitoring data available, and the nature and magnitude of the release.
A summary discussion  of the initial phase is presented in Section  12.2.1.1 and the
subsequent phases in Section  12.2.1.2.
12.2.1.1   Initial Phase
     The initial phase of the release characterization strategy for air  involves the
collection and review of preliminary information and the conduct of a screening
assessment.

12.2.1.1.1 Collectand Review Preliminary Information

     The  first step  is to collect, review and evaluate available  waste,  unit,
environmental setting and release (monitoring and  modeling) data.   The air
pathway data collection effort should be coordinated, as appropriate, with similar
efforts for other media investigations.
                 c_
     Evaluation of these data may, at this point, clearly indicate that a Corrective
Measures Study and/or interim corrective measures are necessary or that no further
action is required.  For example, the source may involve a  large, active storage
surface  impoundment containing  volatile  constituents located  adjacent  to
residential  housing.   Therefore, action instead  of  further studies  may be
appropriate.  Another case may involve a unit in an isolated location, where an
acceptable modeling/monitoring  data  base  may be available which  definitively
                                   12-13

-------
indicates that the air release can be considered insignificant and therefore further
studies are not warranted. In most cases, however, further release characterization
will be necessary.

     A conceptual model (as discussed in Volume I - Summary Section and Section
3.2) of the release should then be developed based on available information. This
model (not a computer or numerical simulation model) should provide a  working
hypothesis of the release mechanism, transport pathway/mechanism, and exposure
route (if any). The model should be testable/verifiable and flexible enough to be
modified as new data become  available.  For example, transport pathway and
exposure modes for a  contaminated surface area may involve air emissions due to
volatilization, wind  erosion and mechanical disturbances.  These air emissions are
expected to result in  inhalation exposure  for offsite receptors.  In addition, the
deposition of air emissions on soil, water  bodies and crops, and  infiltration and
runoff from the onsite source, may contribute to overall exposures.

12.2.1.1.2 Conduct Screening Assessment

     Following review of existing information  and development of the conceptual
model, a screening assessment should be conducted to characterize the air release
(see Figure 12-2).  The  initial screening should be based on conservative (i.e., worst-
case  assumptions).  A screening assessment based on more realistic assumptions
should be conducted if initial air concentration predictions exceed health criteria.

     The Draft Final Air Release Screening  Assessment Methodology, presented in
Appendix G, describes the screening assessment in detail. It consists of emission rate
and dispersion models and involves the following steps:

     •    Obtain source characterization input data
     •    Select release (target) constituents which  may be present in the waste
          and have health criteria for the air pathway (see Section 8.0)
     •    Calculate emission estimates
     •    Calculate concentration estimates at facility property boundary
     •    Compare results to health based criteria
                                   12-14

-------
     In order to assure adequate source characterization input data, it  may be
necessary to collect additional waste/unit data. This may involve field sampling of
the waste to identify waste constituents and determine concentration levels. At this
early RFI stage, it may be more effective and conclusive to sample the wastes (with
relatively  higher  concentration  levels)  instead  of the release.   In general, if
obtaining  source-specific data is not practical, conservative source assumptions
should be used.

     Preliminary monitoring at the source may also be conducted to aid in the
evaluation of the screening/modeling results.  Preliminary monitoring may involve
the use of screening or quantitative methods, and is discussed in Section 12.6. The
preliminary monitoring period will generally be limited to a few days.  Although
preliminary  monitoring results may identify  release  constituents that  were  not
expected  based  on  modeling, or vice  versa, the limitations of modeling and
monitoring should be  considered when comparing these data and determining
appropriate followup activities.                                               .

     A sensitivity analysis should also be conducted to evaluate model input data
quality.  The results  of the sensitivity analysis as well as consideration of model
accuracy should be used to compute  the UF for the screening assessment.  The
results of the screening assessment should then  be compared  to the health and
environmental  assessment  criteria   (as  previously  discussed)  to  determine
appropriate followup actions.  Collection of  additional waste/unit data  and/or
considering  the application  of more refined emission/dispersion models are also
possible options if initial results from the screening assessment are inconclusive.

12.2.1.2   Subsequent Phases
                 £_
     Subsequent phases of  the  release  characterization  strategy for air  may be
necessary if screening assessment results are not conclusive to characterize the air
release,  and should involve the conduct of emission monitoring and confirmatory
air monitoring as indicated in Figure 12-1. These are discussed below.
                                    12-15

-------
12.2.1.2.1  Conduct Emission Monitoring

     Source monitoring should be used in conjunction with dispersion modeling to
further  characterize  the  release, as indicated in Figure 12.3.   Direct emission
sampling should be used for point sources such as vents and stacks.  An isolation
ffux chamber may be used for area source emission measurements.  Onsite air
monitoring (particularly near the emission source) is an alternative approach for
characterizing area source emissions if direct emission monitoring is not practical
(e.g., considering equipment availability). Guidance for the conduct of these field
programs is presented in Section 12.6 and 12.8.

     The development of emission monitoring procedures should address selection
of target air emission constituents.  One acceptable approach is to monitor for all
potential Appendix VIII air emission constituents (see Appendix B, List 3) applicable
to the unit or release of concern. An alternative approach is to use unit and waste-(
specific  information to identify constituents that are expected to be present,  thus^
reducing  the  number of target  constituents  (see  Section  3.6).   The  target
constituents selected  should be limited to those which may be present in the waste
and have health criteria for the air pathway (see Section 8).

     Representative  meteorological data as well  as  emission monitoring  results
should be available as input data for  dispersion modeling.  Therefore, it may be
necessary  to  conduct  an  onsite meteorological  monitoring  survey.    The
meteorological  monitoring survey should be conducted, at a minimum, for a period
sufficient  to  identify and define  wind and stability  patterns  for the  season
associated  with worst-case,  long-term  source  emission/dispersion  conditions.
However, it may ajso be desirable to obtain sufficient data to characterize annual
dispersion conditions at the site.  The season associated with the highest long-term
air concentration Js determined   by evaluating seasonal  emission/dispersion
modeling results based on available meteorological data (e.g., National Weather
Service data).  This modeling application accounts for the complex relationships
between  meteorological  conditions  and  emissions potential  and  dispersion
potential.  For  example,  high average wind speeds  may increase the long-term
emission potential of organics at a surface impoundment, but worst case long-term
dispersion conditions would be associated with low average wind speed conditions.
Seasonal  temperature conditions  would  also  affect  the  emission potential.
                                   12-16

-------
Therefore, it would  be necessary to compare seasonal air concentration results to
identify the season  with worst case long term exposure conditions.  This season
would be the candidate period to collect several months of onsite meteorological
data to support more refined modeling analyses (e.g., dispersion modeling using
emission rate monitoring data as input).  Guidance on selection of the emission
monitoring period within this worst case season is  presented in Section 12.6.4.2.
Guidance on the conduct of a meteorological monitoring program is provided in
Sections 12.6.3 and 12.8.1.

     Dispersion models are  used  to estimate constituent concentrations based on
source and  meteorological monitoring input data.  Guidance on the selection and
application of dispersion models is presented in Section 12.5 and in Guidance on Air
Quality Models (U.S. EPA, July 1986) and  Procedures for Conducting Air Pathway
Analyses for Superfund Applications (U.S. EPA, December 1988).  The results of the
dispersion  modeling assessment should then  be  compared  to the health and'
environmental  assessment   criteria  (as  previously   discussed)  to  determine
appropriate followup actions.

12.2.1.2.2 Confirmatory Air Monitoring

     Confirmatory air monitoring (as outlined  in Figure 12-4), may  also be
appropriate to  provide  additional release  characterization information for RFI
decisionmaking.  Air monitoring data will  provide a basis for release mapping and
for evaluation and  confirmation of modeling  estimates.  The conduct of an air
monitoring program should include the following components:

     •   Develop monitoring procedures
     •   Condudfinitial monitoring
     •   Collect and evaluate results
     •   Conduct additional air monitoring (if necessary)

     The development of monitoring procedures should address selection of target
air emission constituents.  One acceptable approach is to monitor for all potential
Appendix VIII air emission constituents (See Appendix B, List 3) applicable to the
unit or release of concern. An alternative approach is to use unit and waste-specific
information to identify constituents that are expected to be present, thus reducing
                                   12-17

-------
the number  of  target monitoring  constituents  (See  Section 3.6).  The target
constituents selected should be limited to those which may be present in the waste
and have health criteria for the air pathway (see Section 8.0).

     The development of monitoring procedures should also include selection of
appropriate field  and analytical  methods for conducting the  air monitoring
program.  Candidate methods and criteria for monitoring program design (e.g.,
relevant  to sampling schedule and  monitor placement)  should  be limited  to
standard published protocols (such as those available from EPA, NIOSH, and ASTM).
The selection of appropriate methods will be dependent on site and unit-specific
conditions, and is discussed further in Section 12.8.

     A  limited  screening-type  sampling  program may  be  appropriate  for
determining the design of the air monitoring  program.  The  objective of this
screening sampling will be to verify  a  suspected release, if appropriate, and to
further  assist  in identifying  and quantifying release  constituents  of concern.
Screening sampling at each unit for a multiple-unit facility, for example, can be used
to prioritize release sources.  The emphasis during this screening will generally be
on obtaining air samples near the source,  or collecting a limited number of source
emission samples. The availability of air  monitoring data on units with a limited set
of air emission constituents may preclude the need for screening sampling during
the investigation.

     An  initial air monitoring program  should  be  conducted, as necessary,  to
characterize the magnitude and distribution  of  air  concentration levels for  the
target constituents selected.  Initial monitoring should  be conducted for a period
sufficient  to characterize air concentrations at the facility  property boundary, as
input to the health and environmental assessment (e.g., a 90-day  period may  be
appropriate for a flat terrain site with minimal variability of dispersion and source
conditions).

     The basic approach for the initial  air monitoring will consist of collection of
ambient air samples for four target zones:  the first zone located  upwind of the
source to  define  background  concentration  levels;  the  second zone  located
downwind at the unit boundary; the third zone located downwind at the facility
property boundary for input into the health and environmental assessment; and a
                                   12-18

-------
fourth zone offsite,  as  practical, to determine the need for  interim corrective
measures. Multiple monitoring stations will generally be required for each of the
four target zones. It should be noted that offsite air monitoring may not always be
practical  due  to  various  problems  (e.g.,  vandalism,  public  tampering  with
equipment, public relations and legal access problems). Dispersion modeling can be
used to estimate offsite concentrations if monitoring data are not available for the
actual receptor locations of interest.

     The location of air monitors within each zone should be based on site-specific
diurnal and  seasonal wind patterns appropriate for the monitoring period.  An
onsite meteorological monitoring survey (as previously discussed) may be necessary
to characterize local wind patterns.  The objective of the air monitoring network
should be to provide adequate coverage for primary air flowpaths for each of the
zones enumerated above.
  *
     The conduct  of the  initial  air monitoring program generally includes the
collection of meteorological data concurrent with air quality measurements. The
meteorological data are needed during the air monitoring program to characterize
emission  potential and atmospheric dispersion conditions.  This information is also
used to evaluate source/receptor relationships and to interpret and extrapolate the
air monitoring data.

     Additional  air monitoring  may be warranted  if initial monitoring program
objectives are not met (e.g., data recovery goals were not adequate) or results are
not adequate to characterize  the release (e.g., additional  monitoring stations are
needed).

     The air monitoring program data should be evaluated, and a dispersion model
used, as  needed, to estimate concentrations at the facility property boundary.
These results should then be compared to the health  and environmental assessment
criteria (as previously discussed).  Subsequent monitoring  may also be conducted
during or after the implementation of corrective measures to characterize changes
in downwind release concentrations attributed to mitigation efforts.
                                   12-19

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12.3 Characterization of the Contaminant Source and the Environmental Setting

     Release investigations can  be conducted  in an efficient,  effective  and
representative manner if certain information is obtained prior to implementation
of the effort.  This information consists of both  waste/unit characterization and
characterization of the environmental setting.  Review of information from existing
sources can be used to identify data gaps and to initiate data collection activities to
fill  these  data  gaps.  Waste/unit characterization  and characterization  of the
environmental setting are discussed below:

          Waste and unit specific information:  Data on the specific constituents
          present in the unit that are likely to  be released to the air can be used to
          design  sampling efforts  and  identify candidate constituents  to be
          monitored. This information can be  obtained from either a review of the
          existing  information on the waste or from new sampling and analysis.{
  6        The manner in which the wastes are treated, stored or disposed may have.
          a bearing on the magnitude of air emissions from a unit.  In many cases,
          this information may be obtained from facility records, contact with the
          manufacturer of any control devices, or, in some cases, from the facility's
          RCRA permit application.

          Environmental setting information:  Environmental setting information,
          particularly climatological data, is essential in characterizing  an air
          release.  Climatological parameters such as wind speed and temperature
          will have  a significant  impact on the  distribution of a release and  in
          determining  whether  a  particular  constituent  will  be  released.
          Climatological and meteorological information for the area in which the
          facility is located can be obtained either through an onsite monitoring
          effort or from the  National Climatic Data Center (Asheville, NC).  The
          climatological data should be evaluated considering site topography and
          other local influences that can affect the data representatives.

     Information pertaining to the waste,  unit, and environmental setting can be
found in  many  readily  available  sources.   General  information  concerning
waste/unit characterization is discussed  in Section  7.  Air specific  information is
provided in the following discussions.
                                    12-20

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12.3.1          Waste Characterization

     Several  waste  characteristics contribute to  the  potential  for  a  waste
constituent to be released via the air pathway.  These characteristics, in conjunction
with the type of unit and its operation, will determine whether a release will be via
volatilization of the constituent or as particulate entrainment.   Major factors
include  the types  and  number  of  hazardous   constituents  present,  the
concentrations of these constituents in the waste(s), and the chemical and physical
characteristics of the waste  and its constituents.   All of these  factors should be
considered in the context of the specific unit operation involved.  It is important to
recognize that  the constituents  of concern in a  particulate  release may involve
constituents that are either sorbed onto the particulate, or constituents which
actually comprise the particulate.
 %
                                                                            i
12.3.1.1        Presence of Constituents                      .                ,

     The composition of the wastes managed in the unit of concern will influence
the nature of a release to air.  Previous studies may indicate that the constituents
are present in  the unit  or that there is a potential for the presence of these
constituents.  In determining the nature  of  a release, it may be necessary to
determine the specific waste constituents in the unit  if this has not already been
done.  Guidance on selecting monitoring constituents is presented in Section 3 (and
Appendix B); waste characterization guidance is presented in Section 7.

12.3.1.2        Physical/Chemical Properties

     The  physical  and chemical  properties of the waste constituents will affect
whether they will be released, and  if released, what form the release will take (i.e.,
vapor, particulate, or paniculate-associated).  These parameters are identified in
Table  12-3 as a function of emission  and  waste  type.  Important parameters to
consider when assessing the volatilization  of a constituent include the following:

     •    Water  solubility.   The solubility  in  water indicates the maximum
          concentration  at which  a constituent can dissolve in water at a given
          temperature.    This  value  can help  the investigator  estimate  the
                                    12-21

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                                      TABLE 12-3
           PARAMETERS AND MEASURES FOR USE IN EVALUATING POTENTIAL
                RELEASES OF HAZARDOUS WASTE CONSTITUENTS TO AIR
   Emission and Waste Type
 A. Vapor Phase Emissions

    •   Dilute Aqueous
       Solution^

    -   Cone. Aqueous
       Solution^
    -   Immiscible Liquid


    -* Solid




 B.  Particulate Emissions

    -   Solid
     Units of Concern!/
Surface Impoundments,
Tanks, Containers

Tanks, Containers, Surface
Impoundments
Containers, Tanks
Landfills, Waste Piles, Land
Treatment
     Useful Parameters
       and Measures
Solubility, Vapor Pressure,
Partial Pressure3/

Solubility, Vapor Pressure,
Partial Pressure, Raoults
Law

Vapor Pressure, Partial
Pressure

Vapor Pressure, Partial    t
Pressure, Octanol/Water
Partition Coefficient,     f
Porosity
Landfills, Waste Piles, Land   Particle Size Distribution,
Treatment                  Unit Operations,
                            Management Methods
1/  Incinerators are not specifically listed on this table because of the unique issues concerning air emissions
   from these units. Although incinerators can burn many forms of waste, the potential for release from
   these units is primarily a function of incinerator operating conditions and emission controls, rather than
   waste characteristics.

2>  Although the octanol/water partition coefficient of a constituent is usually not an important
   characteristic in these waste streams, there are conditions where it can be critical. Specifically, in waste
   containing high concentrations of organic particulates, constituents with high octanol/water partition
   coefficients will adsorb te the particulates. They will become part of the sludge or sediment matrix,
   rather than volatilizing from the unit.

3/  Applicable to mixtures of volatile components.
                                         12-22

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     distribution of a constituent between the dissolved aqueous phase in the
     unit and the undissolved solid or immiscible liquid phase.  Considered in
     combination with the constituent's vapor pressure, solubility can provide
     a relative assessment of the potential for volatilization of a constituent
     from an aqueous environment.

•    Vapor pressure.  This property is a measure of the pressure of vapor in
     equilibrium  with a pure  liquid.   It is best used  in a  relative sense;
     constituents with high vapor pressures are more likely  to be released
     than those with low vapor pressures, depending on other factors such as
     relative solubility and concentration (e.g., at high concentrations releases
     can occur even though a constituent's vapor pressure is relatively low).

•    Octanol/water  partition   coefficient.   The  octanol/water  partition
     coefficient indicates the tendency of an organic constituent to sorb to"
     organic components of soil or waste matrices.  Constituents with high
     octanol/water partition coefficients tend to adsorb readily to organic
     carbon, rather than volatilizing to the atmosphere. This is particularly
     important in landfills  and land treatment units, where high organic
     carbon content in soils or cover  material can significantly reduce the
     release potential of volatile constituents.

•    Partial  pressure.  For constituents in a mixture, particularly in  a solid
     matrix, the partial pressure of a constituent will be more significant than
     pure vapor pressure.   A partial pressure measures the pressure which
     each component of a mixture of liquid or solid substances will exert in
     order to enter the gaseous phase. The rate of volatilization of an organic
     chemical when either dissolved in water or present in a solid mixture is
     characterized by the partial pressure of that chemical.  In general, the
     greater the partial pressure, the greater the potential for release. Partial
     pressure values  are unique for any given  chemical in any given mixture
     and may  be difficult to obtain.  However when waste characterization
     data are  available, partial pressure can  be estimated  using methods
     commonly found in engineering and environmental science handbooks.
                               12-23

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     •    Henry's Law constant.  Henry's law constant is the ratio of the vapor
          pressure of a constituent to its aqueous solubility (at equilibrium).  This
          constant  can be  used to  assess the  relative  ease with which the
          compound  may vaporize from the aqueous phase. It is applicable only
          for low concentration  (i.e., less  than 10  percent) wastes in  aqueous
          solution and will be most useful when the unit being assessed is a surface
          impoundment or tank containing dilute wastewaters. The potential for
          significant vaporization increases is the value for Henry's Law  Constant
          increases; when it is greater than 10E-3, rapid volatilization will generally
          occur.

     •    Raoult's Law.  Raoult's Law accurately predicts the behavior of most
          concentrated mixtures of water and organic solvents (i.e., solutions over
          10% solute). According to Raoult's Law, the rate of volatilization of each
 3        chemical in a mixture is proportional to the product of its concentration
          in the mixture and its vapor pressure. Therefore, Raoult's Law can be
          used to characterize volatilization potential. This will be especially useful
          when  the unit  of concern  entails container storage, tank storage, or
          treatment of concentrated waste streams.

     A summary of some of these factors for several constituents is given  in Tables
12-4 and 12-5. The following document contains a compilation of chemical-physical
properties for several  hundred constituents. Additional references for these data
are provided in Section 7.

     U.S. EPA. December 1987.  Hazardous Waste Treatment Storage and Disposal
     Facilities fTSDF) - Air Emission Models. EPA-450/3-87-026. Office of Air Quality
     Planning and Standards. Research Triangle Park, N.C. 27711

     For airborne particulates, the particle size distribution plays an important role
in both dispersion and actual inhalation exposure. Large particles tend to settle out
of the air more rapidly than small particles.  Very small particles (i.e., those that are
less than 2.5 to 10 microns in diameter) are considered to be respirable  and thus
present a greater health hazard than the larger particles. Therefore, the  source of
the release should be examined to obtain information on particle  size. Process
information may be sufficient to grossly characterize the-potential for particulate
                                    12-24

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                     TABLE 12-4
PHYSICAL PARAMETERS OF VOLATILE HAZARDOUS CONSTITUENTS
Hazardous constituent
Acetaldehyde
Acrolein
Acrylonitrile
Allylchloride
Benzene
Benzyl chloride
Carbon tetrachloride
Chlorobenzene
Chloroform
Chloroprene
Cresols
Cumene (isopropyl benzene)
1,4-dichlorobenzene
1,2-dichloroethane
Oichloromethane
Dioxin
Epichlorohydrin
Ethylbenzene
Ethylene oxide
Formaldehyde
Hexachlorobutadiene
Hydrogen cyanide
Hydrogen flouride
Hydrogen sulfide
Hexachlorocyclopentadiene
Maleic anhydride
Methyl acetate
N-Dimethylnitrosamine
Naphthlene
Nitrobenzene
Nitrosomorpholine -
Phenol
Phosgene
Phthalic anhydride
Propylene oxide
1 , 1 ,2,2-tetrachloroethane
Tetrach I oroethy I ene
Toluene
1,1,1-trichloroethane
Trichloroethylene
Vinylchloride
Vinylidenechlonde
Xyienes
Molecular
weight
44
56
53
76.5
78
126.6
154
112
119
88.5
108
120
147
99
85
178
92.5
106
44
30
261
27
20
34
273
98
74
81
123


94
98
148

168
166
92
133
131
62.5
97
106
Vapor pressure
at25°C(mmHg)
915
244
114
340
95
1.21
109
12
192
215
0.4
4.6
1.4
62
360
7.6E-7
13
10
1,095
3,500
0.15
726
900
15,200
0.03
0.3
170
3.4
0.23
0.3
5.3
0.34
1,300
0.03
400
9
15
30
123
90
2,600
500
8.5
Solubility
at25°C(mg/l)
1.00E + 06
4.00E + 05
7.90E + 04

1.78E + 03
1.00
8.00E * 02
5.00E + 02
8.00E + 03

2.00E + 04
50.0
49.00
8.69E + 03
2.00E + 04
3.17E-04
6.00E + 04
152
1.35E + 05
3.00E + 05





1.63E + 05
3.19E + 05


1.90E + 03

9.30E + 04

6.17E + 03

2.90E + 03
200
534
720
1.10E + 03
6.00E + 03

1.00
Henry's Law
constant
(atm"3/mol)
9.50E-05
4.07E-05
8.80E-05
340E-01
5.50E-03

2.00E-02
2.00E-03
3 OOE-03

4.60E-07
2.00E-04

1.00E-04
2.00E-03
1.20E-03
3.08E-05 r
7.00E-03








1.00E-04


1.30E-05

1.02E-05

9.00E-07

2.00E-04

5.00E-03
2.15E-02
8.92E-03
1.90E-01

4 04E-04 .
                       12-25

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                    TABLE 12-5
      PHYSICAL PARAMETERS OF PCB MIXTURES*
Arochlor
(PCB)
1242
1248
1254
1260
Vapor pressure
at 25°C (atm)
2.19E-07
1.02E-07
1.85E-08
5.17E-09
Solubility
at25°C(mg/l)
2400
520
120
30
Henry's Law
constant
(atm-m3/mol)
238E-08
1.02E-08
1.40E-08
6.46E-08
All values estimated based on calculations.
                       12-26

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formation. For example, the presence of ash materials and similar wastes would be
a case in which paniculate emissions would be of concern.

12.3.2         Unit Characterization

     Different types of units may have differing release potentials. The particular
type of unit, its configuration, and its operating conditions will have a great effect
on the nature, extent, and rate of the release. These practices or parameters should
be determined and reasonable worst-case operating practices or conditions should
also be identified priorto initial sampling.

12.3.2.1       Type of Unit

     The type of unit will  affect its release potential and the types of releases
eapected.  For the purpose of this guidance, units have been divided  into three{
general types with regard to investigating releases to air. Theseare:              I

     •    Area sources having  solid surfaces,  including land treatment facilities,
          surfaces of landfills, and waste piles;

     •    Point sources,  including vents,  (e.g., breathing  vents from tanks)  and
          ventilation outlets from enclosed units (e.g., container handling facilities
          or stacks); and

     •    Area sources having liquid surfaces, including surface impoundments and
          open-top tanks.

     The following discussion provides examples for each of these unit types and
illustrates the kind of data that should be collected  prior to establishing  a sampling
plan. Table 12-6 indicates types of releases most likely to be observed from each of
these example unit types. It should also be recognized that releases to air can be
continuous or intermittent in nature.

     Waste piles-Waste  piles  are primary sources of particulate releases due to
entrainment into the air of solid particles from the pile. Waste piles are generally
comprised  of dry materials which  may  be  released into  the  air by  wind or
                                    12-27

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                             TABLE 12-6
      SUMMARY OF TYPICAL UNIT SOURCE TYPE AND AIR RELEASE TYPE
Typical
Unit Type
Waste Piles
Land Treatment
Units
Landfills
Drum Handling
Facilities
Tanks
Surface
Impoundments
Incinerators*
Source Type
Area Sources
with Liquid
Surface




X
X

Area Sources
with Solid
Surface
X
X
X




Point Sources


X
X
X

X
Potential Phase
of Release
Vapor
X
X
X
X
X
X
X
Paniculate
X
X
X
X


X
*  Includes units (e.g., garbage incinerators) not covered by 40 CFR Part 264,
   SubpartO which pertains to hazardous waste incinerators.
                                12-28

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operational activities.  The major air contaminants of concern from waste piles will
be those compounds that are part of or have been adsorbed onto the particulates.
Additionally, volatilization of some constituents may occur. Important unit factors
include the waste pile dimensions (e.g., length, width, height, diameter and shape),
and the waste management practices (e.g., the frequency and manner in which the
wastes are applied to the pile and whether any dust suppression procedures are
employed).  The pile  dimensions determine the surface area available for wind
erosion. Disturbances to the pile can break down the surface crust and thus increase
the potential for particulate emissions.  Dust suppression activities, however, can
help to reduce particulate emissions.

     Land treatment units-Liquid or sludge wastes may be applied to tracts of soil
in various ways such as surface spreading of sludges, liquid spraying on the surface,
and subsurface liquid injection.   These methods may also involve cultivation or
tilling of the soil. Vapor phase and particulate contaminant releases are influenced'
by the various application techniques.  Particulate or volatile emission releases are
most likely to occur during initial application or during tilling, because tilling keeps
the soil unconsolidated and loose, and increases the air to waste surface area.

     Important unit factors in assessing an air release from a land treatment unit
include:

     •    Waste application method  - Liquid  spraying applications tend  to
          minimize particulate releases while increasing potential volatile releases.
          Subsurface  applications generally reduce the potential for particulate
          and volatile releases.

     •    Moisture content of the waste - Wastes with high moisture content will
          be less Ifkely to be released as particulates; however, a potential vapor
          phase refease may become more likely.

     •    Soil characteristics - Certain  constituents, such as hydrophobic organics,
          will be more likely to be bound to highly organic soils than non-organic
          soils. Therefore, releases of these types of constituents are most likely to
          be associated with particulate emissions.
                                    12-29

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     Landfills-Landfills can result in  participate and  vapor phase releases.  This
process generally involves placement of waste in  subsurface disposal  cells and
subsequent covering of the waste with uncontaminated soil. Landfill characteristics
that can affect contaminant release include:

     •    Porosity and moisture content of the soil  or clay covering can  influence
          the rate at which vapor phase releases move through the soil towards the
          surface. Finer soils with lower porosities will generally slow movement of
          vapors through the unit.  The frequency of applying soil cover to the
          open  working face  of a landfill  will also affect the  time  of  waste
          exposure to the air.

     •    Co-disposal of  hazardous and municipal  wastes will often increase the
          potential for vapor phase releases, because biodegradation of  municipal
 &        wastes results in the formation of methane gas as well as other volatile*
          organics.  Methane gas may act as a driving force for release of other
          volatile hazardous components that may  be in the unit (See Section 11 -
          Subsurface Gas.)

     •    Landfill gas vents, if present, can act as sources of vapor phase emissions
          of contaminated landfill gases.

     •    Leachate  collection  systems can  be sites of  increased vapor  phase
          emissions due  to the  concentrated  nature of the leachate  collected.
          Open trenches are more likely to be emission sources than underground
          collection sumps due to the increased exposure to the atmosphere.

     •    Waste mixing or consolidation areas where bulk wastes are mixed with
          soil or "other  materials (e.g., fly  ash)  prior to landfilling can  be
          contributors to both particulate and vapor phase air releases.  Practices
          such as spreading materials on the ground to  release moisture prior to
          landfilling will also increase exposure to the  atmosphere.

     Drum handling facilities-Emissions from drum or  container handling areas can
result from  several types of basic operations.   Frequently, emissions from these
operations are vented to the air through ducts or ventilation systems. Air sampling
                                   12-30

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to assess emissions from  these operations may include sampling of the control
device outlets, the workplace atmosphere at each operation, or the ambient air
downwind of the unit. Factors which effect emissions include:

     •    Filling operations can be a major source of either vapor or particulate
          emissions due to agitation of the materials during the filling process.
          Spillage which  occurs during loading may  also contribute to emissions.
          Organic waste components with high volatility will readily vaporize into
          the air. Similarly, particulate matter can be atmospherically entrained by
          agitation and wind action.  The emission potential of filling-operations
          will be affected by exposure to ambient air. Generally, fugitive emissions
          from an enclosed  building will be less than emissions created during
          loading in an open structure.

 ,*   •    Cleaning operations can have a  high potential for  emissions. These'
 ,        emissions may  be  enhanced by the use of solvents or steam cleaning
          equipment.  The waste collection systems at these operations usually
          provide for surface runoff to open or below ground  sumps, which can
          also contribute to air emissions.

     •    Volatilization of waste components can also occur at storage units. Since
          it is common practice to segregate incompatible wastes during storage,
          the potential for air releases may differ within a storage unit depending
          on the nature  of the wastes stored  in any  particular area.  The most
          common source of air emission releases from drum storage areas is spills
          from drums ruptured during shipping and handling.

     •    For offsite facilities, storage areas frequently are located  where drums
          are sampled  during the waste testing/acceptance process.  This process
          involves drum opening for sampling  and could also include  spillage of
          waste materials on the ground  or floor.

     Important release information includes emission rates, and data  to estimate
release rise (e.g., vent height and diameter  as well as  vent exit temperature and
velocity). Information pertaining to building dimension/orientation of the unit and
nearby structures is needed to assess the potential for aerodynamic behavior of the
                                   12-31

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stack/vent release.  These input data would  be needed if atmospheric dispersion
modeling was necessary.

     Tanks-Tanks can emit volatile waste components under various circumstances.
A major determinant of any air emission will be the type of tank being studied.
Closed or fixed roof storage tanks will most likely exhibit less potential for air
emissions than open topped tanks. Some tanks are equipped with vapor recovery
systems that are designed to reduce emissions.  Important process variables for
understanding air emissions  from tanks can be classified as  descriptive and
operational variables:

     •    Descriptive variables include type, age, location, and configuration of the
          tank.

 ,   •    Operational variables include  aeration, agitation, filling  techniques/
 r        surface area, throughput, operating pressure and temperature, sludge
          removal technique and frequency, cleaning technique.and frequency,
          waste retention and vent pipe dimensions and flow rate.

     Important release information includes emission rates, and data to estimate
plume rise (e.g.,  height  and diameter as well as exit temperature  and velocity).
Information pertaining to building dimensions/orientation of the unit and nearby
structures is needed to assess the potential  for aerodynamic behavior of the
stack/vent release.  These input data would  be needed if atmospheric dispersion
modeling was necessary.

     Surface impoundments-Surface impoundments are similar in many ways to
tanks in the manner in which air emissions may be created. Surface impoundments
are generally larger, at least in terms of exposed surface areas, and are generally
open to the atmosphere. The process variables  important for the  evaluation of
releases to air from surface impoundments can also be classified as descriptive and
operational.

     •    Descriptive parameters include dimensions, including length, width, and
          depth,  berm design, construction and liner materials used,  and the
          location of the unit on the site.
                                   12-32

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     •    Operational  parameters  include freeboard,  filling  techniques  (in
          particular, splash versus submerged inlet), depth of liquid and sludge
          layers, presence of multiple liquid layers, operating temperature, sludge
          removal techniques and frequency, cleaning technique and frequency,
          presence  of  aerators  or  mixers,  biological  activity  factors   for
          biotreatment, and the presence of baffles, oil  layers, or other control
          measures on the liquid surface. (These factors are relevant to some tanks
          as well.)

     Some surface impoundments are equipped with leak collection systems that
collect leaking liquids, usually into a sump.  Air emissions can also occur from these
sumps.  Sump operational characteristics and dimensions  should be documented
and,  if  leaks occur, the  volume of  material entering  the sump should  be
documented. (These factors are relevant to some tanks as well.)
                                                                           I
     Incinerators  - Stack emissions from  incinerators  (i.e.,  incinerator  units not
addressed by RCRA in Part 264, Subpart 0, e.g., municipal  refuse incinerators) can
contain  both particulates and volatile constituents.  The high temperatures  of the
incineration process can also cause volatilization of low vapor pressure organics and
metals.  Additional volatile releases can occur from malfunctioning valves during
incinerator charging. The potential for air emissions from these units is primarily a
function of incinerator operating conditions and emission controls.  Important unit
release information includes emission rates, and data to estimate plume rise (e.g.,
height and diameter as well as exit temperature and velocity), as well as building
dimensions/orientation  of the  unit and nearby structures.  This  information is
needed  to assess the aerodynamic behavior of the stack/vent release and for input
to atmospheric dispersion models.
                 *L
12.3.2.2        Size'ofUnit

     The size of  the unit(s) of concern will have an important  impact on the
potential magnitude of a release to air. The release of hazardous constituents to
the air from an area source is often directly proportional to the surface area of the
unit, whether this surface area is a liquid (e.g., in a tank) or a solid surface (e.g., a
land treatment unit). The scope of the air investigation may be a function  of the
                                   12-33

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size of the unit.  Generally, more sampling locations will  be required as the unit
increases in size, due primarily to increased surface area. Also, as the total amount
of waste material present in a particular unit increases, it will  represent a larger
potential reservoir or source of constituents which may be released.

     Scaling factors, such as surface area to volume ratios should also be evaluated.
One large waste pile, for instance, can exhibit a lower ratio of surface area to total
volume than the sum of two smaller piles in which the total volume equals that of
the larger pile. Other units such as tanks may exhibit a similar economy of surface
area, based on the compact geometry of the unit.

     Because releases to air generally occur at the waste/atmosphere interface,
surface area  is generally a more  important  factor than  total  waste volume.
Consequently, operations  that increase the atmosphere/waste interface', such as
agitation or aeration, splash filling,  dumping or filling operations, and spreading*
operations will tend to increase the emission rate. Total emissions, however, will be
a function of the total mass of the  waste constituent(s) and the.duration of the
release.

     For point sources, the process or waste throughput rate  will  be the most
important unit information needed to evaluate the potential for air emissions (i.e.,
stack/vent releases).

12.3.2.3       Control Devices

     The  presence of air  pollution control devices on units can have a major
influence on the nature and extent of releases.  Control devices can include wet or
dry scrubbers,  electrostatic  precipitators, baghouses,  filter  systems,  wetting
practices for solid materials, oil layers on surface impoundments, charcoal or resin
absorption systems, vapor flares, and  vapor recovery systems.   Many of  these
controls systems can be installed on many of the unit types discussed in this section.
Due to the variety of types of devices  and the range of operational differences, an in
depth  discussion of individual  control devices is not presented  here.  Additional
information on control technologies for hazardous air pollutants is available in the
following references:
                                   12-34

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     U.S.  EPA.   1986.   Handbook -  Control  Technologies for  Hazardous  Air
     Pollutants. EPA/625/6-86/014. Office of Research and Development. Research
     Triangle Park, N.C. 27711.

     U.S.  EPA.   1986.   Evaluation of Control Technologies for  Hazardous  Air
     Pollutants:  Volume 1  - Technical Report.  EPA/600/7-86/009a.  NTIS PB  86-
     167020. Volume 2 - Appendices.  EPA/600/7-86/009b.   NTIS  PB 86-167038.
     Off ice of Research and Development. Research Triangle Park, N.C. 27711.

     If  a  control device is present  on the  unit of concern, descriptive and
operational characteristics  of  the unit/control  device  combination should  be
reviewed and documented.  In many cases, performance testing of these devices has
been conducted after their installation on the unit(s). Information from this testing
may help to quantify releases to air from the unit(s); however, this testing may  not
have been performed under a  "reasonable worst-case" situation.  The conditions'
under which the testing was  performed should be documented.

12.3.2.4       Operational  Schedules

     Another characteristic which can affect the magnitude of a release to air from
a unit is the unit's operational schedule. If the unit is operational on a part time or
batch  basis,  the  emission  or  release rate should  be  measured  during  both
operational and non-operational periods. In contrast to batch operations, emission
or release rates from continuous waste management operations may be  measured
at any time.

12.3.2.5       Temperature of Operation

     Phase changes~bf liquids and solids to gases is directly related to temperature.
Therefore, vapor phase  releases to air are  directly  proportional to  process
temperature. Thus, it  is important to document operational  temperature (i.e.,
waste temperature)  and fluctuations to enhance the understanding of releases to
air from units. Particular attention should be paid to this parameter in the review of
existing data or information  regarding the operation of the unit.
                                   12-35

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     The  release  rate  of volatile components  also  generally  increases  with
temperature.  Frequently, the same effect is observed for particulates, because
entrainment is enhanced as materials are dried. Thus, the evaporation of any water
from solids, which generally increases as temperature increases, will likely increase
the emissions of many particulates in the waste streams.  Evaporation of water may
also serve to concentrate wastes, leading to conditions more conducive to vapor
phase releases to air.  It should  also be noted that the destruction efficiency of
incinerators  is  also  a  function  of temperature  (i.e.,  higher temperatures are
generally associated with greater destruction efficiency).

12.3.3          Characterization of the Environmental Setting

     Environmental factors can influence not only the rate of a release to air but
also the potential for exposure. Significant environmental factors include climate,
s«il conditions, terrain and location of receptors. These factors are discussed below.'

12.3.3.1        Climate
     Wind, atmospheric stability and temperature conditions affect emission rates
from area sources as well as atmospheric dispersion conditions for both area and
point sources. Historical summaries of climatic factors can provide a basis to assess
the long-term potential for air emissions and to characterize long-term ambient
concentration patterns for the areNa.  Short-term  measurements of these conditions
during air monitoring will provide the meteorological data needed to interpret the
concurrent air quality data. Meteorological monitoring procedures are discussed in
Section 12.8.  Available climatic information, on an annual and monthly or seasonal
basis, should be collected for the following parameters:

     •    Wind direction and roses  (which affects atmospheric transport, and can
          be used to determine the direction and dispersion of release migration);

     •    Mean wind speeds (which affects the potential for dilution of releases to
          air);

     •    Atmospheric stability distributions (which affects dispersion conditions);
                                    12-36

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     •   Temperature  means  and extremes  (which affects the  potential for
         volatilization, release rise and wind erosion);

     •   Precipitation means (which  affects  the potential for  wind erosion of
         particulates);

     •   Atmospheric  pressure  means  (which  affects  the potential for  air
         emissions from landfills); and

     •   Humidity means (which can  affect the air collection efficiencies of some
         adsorbents - see Section 12.8).

     The primary source of climate information for the United States is the National
Climatic Data Center (Asheville, NC). The National Climatic Data Center can provide
climate summaries for the  National Weather Service station nearest to the site of
interest. Standard references for climatic information include the following:

     National Climatic Data Center. Local Climatoloqical Data - Annual Summaries
     with Comparative Data, published annually. Asheville, NC 28801.

     National Climatic Data Center. Climates  of the States.  1973.  Asheville, NC
     28801.

     National Climatic Data Center. Weather Atlas of the United  States.  1968.
     Asheville, NC  28801.

     The climatological data should  be evaluated  considering the  effects of
topography and other local influences that can affect data representativeness.
                 t
     A meteorological monitoring survey may  be conducted  prior to ambient air
monitoring to establish the local wind  flow  patterns and for  determining the
number and locations of sampling stations.  The survey  results will be used to
characterize  local  prevailing winds and diurnal wind flow patterns  (e.g., daytime
upslope winds, nighttime downslope winds, sea breeze conditions) at the site.  The
survey should  be  conducted  for a one-month period  and  possibly  longer to
adequately characterize anticipated  wind  patterns  during  the air monitoring
                                   12-37

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program.    Inland,  flat  terrain  conditions  may  not  necessitate an  onsite
meteorological monitoring survey if representative data are available from previous
onsite studies or from National Weather Service stations.

     The meteorological monitoring data collected during the initial monitoring
phase can serve  as a basis for the  placement of air sampling stations during any
subsequent monitoring phases.

12.3.3.2       Soil Conditions

     Soil conditions (e.g., soil porosity) can affect air emissions from landfills and
the  particulate  wind  erosion  potential  for  contaminated  surface soils.   Soil
conditions pertinent to characterizing the potential for air emissions include the
following:
                                                                            t
 *                                                                          t
     •    Soil porosity (which affects the rate of potential gaseous emissions);

     •    Particle  size distribution (which  affects the  potential  for particulate
          emissions from contaminated soils); and

     •    Contaminant concentrations in soil (i.e., potential to act as air emission
          sources).

     Soil characterization information is presented in Section 9.

12.3.3.3       Terrain

     Terrain features can significantly influence the atmospheric transport of air
emissions.  Terrain heights relative to  release heights will  affect groundlevel
concentration. Terrain obstacles such as hills  and mountains can  divert regional
winds. Likewise, valleys can channel wind flows and also limit horizontal dispersion.
In addition, complex terrain can result in the  development  of local  diurnal wind
circulations and affect wind speed, atmospheric turbulence and stability conditions.
Topographic maps of the facility and adjacent areas are needed to assess local and
regional terrain. Guidance on the appropriate format and sources of topographic
and other maps is presented in Section 7 and Appendix A.
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12.3.3.4       Receptors

     Information concerning the locations of nearby buildings and the population
distribution in the vicinity of the site are needed to identify potential air-pathway
receptors. This receptor information provides a basis for determining the need for
interim corrective measures.  Both environmental and human receptor information
is needed to assess potential air-pathway exposures. Such information may include:

     •    A site boundary map;

     •    Location of nearest buildings and residences for each of the sixteen 22.5
          degree sectors which corresponds to major compass points (e.g., north,
          north-northwest);

     •    Location of buildings and residences that correspond to the area or
          maximum  offsite groundlevel  concentrations based. on  preliminary
          modeling estimates (these locations may not necessarily be near the site
          boundary for elevated releases); and

     •    Identification of  nearby  sensitive  receptors  (e.g.,  nursing  homes,
          hospitals, schools, critical habitat of endangered or threatened species).

     The  above information should be  considered  in  the  planning of an air
monitoring program. Additional guidance on receptor information is  provided in
Section 2.

12.3.4         Review of Existing Information
                 s_
     The review of existing air modeling/monitoring data entails both summarizing
the reported  air contaminant concentrations as well as evaluating the quality of
these data.  Air data can be of many varieties and of varying utility to the RFI
process. Modeling data should be evaluated based on the applicability of the model
used, model accuracy, as well as the quality and representativeness of the input
data.
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     One of the most basic parameters to review in any type of air monitoring data
should be the validity of the sampling locations used during the collection of the
monitoring data.  The results of previous investigations should be assessed with
respect  to the  upwind-downwind pattern around the unit  to determine the
likelihood that the sampling devices would have measured releases from the unit of
concern.  For relatively simple sites  (e.g., flat terrain,  constant wind speed and
direction),  this  determination should be  fairly  straight-forward; however,  for
complex sites (e.g., complex terrain, variable winds, multiple sources, etc.), assessing
the appropriateness  of past sampling locations should consider such  factors  as
potential interferences that may not have been addressed by the sampling scheme.

     The most useful monitoring data are compound-specific results which can  be
associated with the unit being investigated, or, for point sources (such as vent stacks
or ventilation system outlets), direct measurements of the exhaust prior to  its
release  into the atmosphere.  Because the hazardous properties and health andj
environmental criteria are compound-specific, general compound category or classj
data (e.g., hydrocarbon results) are less  meaningful. Any existing air data should
also be described and documented as to the sampling and analysis methods utilized,
the associated detection limits, precision and accuracy, and the results of QA/QC
analyses conducted. Results reported as non-detected (i.e., not providing numerical
detection limits) are likely to be of no value.

     In  addition, available upwind and downwind air data should be evaluated to
determine if the contamination is due to releases from the unit.  If background data
are available for the unit of concern, the data will be of much greater use in the
planning of additional air monitoring  tasks. Upwind data (to characterize ambient
air background levels) are important for evaluating if downwind contamination can
be attributed to the unit of concern.  If background data are not available, the
existing downwind air concentration data will be of less value in characterizing a
release; however, the lack of background data does not negate the utility of the
available monitoring data.

     Data may also be available from air monitoring  studies  that did  not focus
directly on releases from a unit of concern. Many facilities conduct onsite health
and safety programs, including routine  monitoring of  air quality for purposes of
evaluating worker exposure.  This type of data  may include  personnel hygiene
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monitoring results from personal  sampling  systems worn by employees as they
perform  their jobs,  general  area monitoring  of zones  at  which  hazardous
operations are conducted, or actual unit-emission monitoring. The detection limits
of these  methods (generally in parts per million) are frequently higher than are
needed for RFI purposes. However, this type of industrial hygiene monitoring is
frequently compound-specific, and can be useful in qualitatively evaluating the air
emissions from particular sources.

     Indoor air monitoring, generally only applicable to units that are enclosed in a
building (e.g., drum handling areas or tanks), often includes flow monitoring of the
ventilation system.  Monitoring of hoods and ductwork  systems may  have been
conducted  to determine exchange time and air circulation rates.  These  flow
determinations  could prove  to  be useful in the evaluation of  air emission
measurements during the RFI.

     Another important aspect of the existing data review is to  document  any
changes in composition of the waste managed in the unit of concern since the air
data were collected. Also, changes in operating conditions or system configuration
for waste generation and/or unit functions could have major effects on  the nature
or extent of releases to air.  If such operational or waste changes have occurred,
they should be summarized and reviewed to determine their role in the  evaluation
of existing data.  This summary and review will not negate the need to take new
samples to characterize releases from the unit. However, such information can be
useful in the planning of the new air monitoring activities.

12.3.5         Determination of "Reasonable Worst-Case" Exposure Period

     A "reasonable worst-case" exposure period over a 90 day  period should be
identified if an airmonitoring program is to be conducted.  Determination of
reasonable worst-case exposure conditions will aid in planning the air monitoring
program  and is dependent on seasonal variations in emission rates and dispersion
conditions.

     The selection of the "reasonable worst-case" 90-day exposure period for the
conduct of air monitoring should account for the following factors:
                                  •12-41

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     •    For vapor  phase releases,  wind speed  and temperature  are  the  key
          factors  affecting releases from the unit.   In general, the higher the
          temperature and windspeed, the greater the rate of volatilization of
          constituents  of  concern from the waste.   This process is  tempered,
          however, by the fact that at higher windspeeds, dispersion of the release
          is generally  greater,  resulting  in lower downwind  concentrations at
          potential exposure points.

     •    For paniculate releases, wind speed is the key meteorological factor.  The
          amount of local precipitation contributing to the degree of moisture of
          the waste may also be important. In general, the higher the windspeed,
          and the drier the waste, the greater will be the potential for  particulate
          release. As with vapor phase releases, higher wind speeds may also lead
          to  greater dispersion of the release,  resulting  in  lower  downwind
  v        concentrations.
                                                                           !
     •    For  point  source  releases, increased  wind  speeds  and  unstable
          atmospheric  conditions (e.g., during cloudless days) enhance dispersion
          but also tend to reduce plume height and can lead to relatively high
          groundlevel concentrations.

     •    Constituent concentrations at any downwind sector will also be directly
          affected by the wind direction and frequency.

     Air emission release rate models and atmospheric dispersion models can be
used to identify reasonable worst-case exposure conditions (i.e., to quantitatively
account for the above  factors).  For this application, it is recommended  that the
modeling  effort be limited to a  screening/sensitivity exercise with the objective of
obtaining  "relative".results for a variety of source and meteorological scenarios. By
comparing results in a relative fashion, only those input meteorological parameters
of greatest significance (e.g., temperature, wind speed and stability) need to be
considered.

     In general, the summer season will be the "reasonable worst-case" exposure
period at  most sites because of relatively high temperatures and low windspeeds.
Spring and fall are also candidate monitoring seasons that should be evaluated on a
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site-specific basis. Winter is generally not a prime season for air monitoring due to
lower temperatures and higher wind speeds.

12.4      Air Emission Modeling

12.4.1          Modeling Applications

     Air emission models can be used to estimate constituent-specific emission rates
abased on waste/unit input data for many types of waste management units.  (An
emission rate is defined as the source release rate for the air pathway in terms of
mass per unit of time.)

     An  important  application  of  emission   models   in  the  RFI  release
characterization strategy for air is the conduct of screening assessments. For this
application, available waste/unit input data for  emission models, in conjunction
with dispersion modeling results, are used to estimate concentrations at locations of
interest. These results can then be evaluated to determine if adequate information
is available for RFI decisionmaking or if monitorinc is needed to further reduce the
uncertainty associated with characterizing the release. Depending on the degree of
uncertainty in the estimated concentrations relative to the differences between the
estimated concentrations and the health based  levels, modeling  results may be
sufficient  to characterize  the release  as  significant (i.e.,  implementation  of
corrective action would be appropriate) or as insignificant (i.e., no further action is
warranted).

     Emission rate models can also be used to identify potential major air emission
sources at a facility (especially multiple-unit  facilities). For this type of application,
modeling  results are used to compare routine long-term emissions from various
units to prioritize the need  for release characterization at each unit.  For example,
modeling  results may indicate that 90 percent of the volatile organic  compound
emissions at a facility are attributable to surface  impoundment units and only 10
percent to other sources. Therefore, emphasis should be on characterizing releases
from the surface impoundments.

     Emission modeling is not available for  all air-related phenomenon associated
with waste management.  For example, anaerobic biological activity  in surface
                                    12-43

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impoundments may, in certain instances, contribute to air pollution by emitting
constituents not contained in the waste placed in the impoundment and which
available models do not adequately address.  In such instances, source testing or
monitoring may be necessary; based on such monitoring, emission rates can  be
developed.

12.4.2          Model Selection

     The information gathered during the initial stage of the  air investigation
should be used to select  appropriate models and to estimate  unit-specific and
constituent-specific emission rates.  A thorough  understanding  of the available
models is needed before selecting a model for an atypical emission source. When
gathering information on any emission source, it would be  useful to obtain a
perspective of  the potential  variability of the waste and  unit  input data.  A
sensitivity analysis of this variability relevant to emission rate estimates would help
determine the level of confidence associated with the emission modeling results.

     Air emission models can be classified into two categories; models which can be
used to estimate volatile organic releases,  and  models which  can be used to
estimate particulate emissions. These are discussed below.

12.4.2.1         Organic Emissions

     Comprehensive guidance on the application of air emission models for volatile
organic releases from various units is presented in the following  references:

     U.S. EPA. December 1987. Hazardous Waste Treatment. Storage, and Disposal
     Facilities rTSDF) - Air Emission Models. EPA-450/3-87-026. Office of Air Quality
     Planning and*Standards. Research Triangle Park, NC 27711.

     U.S. EPA.  December 1988  Draft.  Procedures  for Conducting Air Pathway
     Analyses for Superfund  Applications.  Office of Air Quality Planning and
     Standards. Research Triangle Park, NC 27711.
                                   12-44

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     These references provide modeling guidance for the following units:

     •    Surface impoundments
              Storage impoundments
              Disposal impoundments
              Mechanically aerated impoundments
              Diffused air systems
              Oil film surfaces

     •    Land treatment
              Waste application
              Oil film surfaces
              Tilling

 .   •    Landfills
                                                                          t
              Closed landfills
              Fixation pits
              Open landfills

     •    Waste piles

     •    Transfer, storage and handling operations
              Container loading
              Container storage
              Containercleaning
              Stationary tank loading
              Stationary tank storage
              Spills
              Fugitive emissions
              Vacuum truck loading

Emission factors for various evaporation loss sources (e.g., storage and handling of
organic liquids) are provided in the following reference:
                                   12-45

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     U.S. EPA.  1985.  (Fourth edition and subsequent supplements) Compilation of
     Air Pollutant Emission Factors. EPA AP-42. NTIS PB 86-124906. Office of Air
     Quality Planning and Standards. Research Triangle Park, NC 27711.

     An emission factor is generally defined as an average value which relates the
quantity of a pollutant released to the atmosphere with the activity associated with
the release of the pollutant.  However, for estimation  of organic releases from
storage tanks,  the emission factors are  presented in terms of empirical formulae
which can relate emissions to such variables as tank diameter, liquid temperature,
etc.

     Selection  of  an  appropriate air emission model will be based primarily on
selection of a  model  which is appropriate for the  unit of concern, has technical
credibility and is practical to use.  Some of the models  presented in Hazardous
Waste Treatment.  Storage and Disposal Facilities (TSDF) - Air Emission Models (U.S.'
EPA, December 1987), are available on  a diskette for use  on a microcomputer.
Computer-compatible air emission models (referred  to as CHEMDAT6 models) are
available for the following sources.

     •    Nonaerated impoundments
     •    Open tanks
     •    Aerated impoundments
     •    Land treatment
     •    Landfills

These models are prime candidates for RFI air release characterization applications.

12.4.2.2       Paniculate Emissions
                 s^
     Guidance  on "the  selection  and  application  of air  emission  models  for
particulate releases is  presented in the following references:

     U.S.  EPA.  February  1985.   Rapid Assessment of  Exposure to Particulate
     Emissions from  Surface Contamination Sites.  EPA/600-18-85/002.  Office of
     Health and Environmental Research. Washington, D.C. 20460.
                                   12-46

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     U.S. EPA. 1985.  (Fourth edition and subsequent supplements) Compilation of
     Air Pollutant Emission Factors. EPA, AP-42. Office of Air Quality Planning and
     Standards. Research Triangle Park, NC 27711.

     U.S. EPA. 1978.  Fugitive Emissions from Integrated Iron and Steel Plants.  EPA
     600/2-78-050. Washington, D.C. 20460.

     U.S. EPA.  December 1988  Draft. Procedures for Conducting  Air Pathway
     Analysis for Superfund  Applications.  Office of Air Quality Planning  and
     Standards. Research Triangle Park, NC 27711.

     These references provide modeling  guidance for  the following particulate
sources and associated operations and activities (e.g..vehicular traffic):

     •    Wastepiles
     •    Flat, open surfaces

     The air emission models for both types of sources should account for both
wind erosion potential as well as releases due to mechanical disturbances.

     The  U.S. EPA-Office  of Air Quality  Planning  and  Standards  is  currently
developing  guidance regarding  particulate  emissions from  hazardous  waste
transfer, storage and disposal facilities.

12.4.3         General Modeling Considerations

     Organics in surface impoundments, land treatment facilities, landfills,  and
wastepiles, can depart through  a variety of pathways, including volatilization,
biological decomposition, adsorption, photochemical  reaction, and hydrolysis. To
allow reasonable estimates of organic disappearance, it is necessary to determine
which  pathways predominate for a  given chemical, type of  unit, and  set of
meteorological conditions.

     Source variability will significantly influence the relative importance  of the
pathways. For highly variable sources it may be possible to exclude insignificantly
small pathways from consideration. The relative magnitude of these pathways then
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can be computed by applying the methodology to a model facility to determine
relative differences among various compounds. A summary of typical pathways for
air emission sources is presented in Table 12-7.

     It is also necessary to consider the variation of waste composition as a function
of time as well as other potential variations in source conditions.  These variable
conditions may necessitate multiple modeling scenarios to adequately characterize
representative waste/unit conditions.

12.5      Dispersion Modeling

12.5.1          Modeling Applications

     Atmospheric dispersion models  can be used to estimate constituent-specific
concentrations at  locations  of  interest  based  on input  emission  rate  and
meteorological input data.  The major RFI dispersion modeling  applications for
characterizing releases to air can be summarized as follows:

     •    Screening assessments:  Dispersion models can be used to estimate
          concentrations at locations of interest using input emission  rate data
          based on  air emission modeling.

     •    Emission  monitoring:  Dispersion models can be  used to estimate
          concentrations at locations of interest using input emission  rate data
          based on  emission rate monitoring.

     •    Confirmatory air monitoring: Dispersion modeling can  be used to assist
          in designing an air monitoring program (i.e., to determine appropriate
                 SI
          monitoring locations and monitoring period) as well as for interpretation
          and extrapolation of monitoring  results.

     Atmospheric dispersion models  can be used for monitoring  program design
applications to identify areas of high  concentration relative to the facility property
boundary or actual receptor locations. High concentration areas which correspond
to actual receptors are priority locations for  air monitoring stations.
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                             TABLE 12-7

           TYPICAL PATHWAYS FOR AREA EMISSION SOURCESa
Pathway
Volatilization
Biodegradation
Photodecomposition
Hydrolysis
Oxidation/reduction
Adsorption
Hydroxyl radical reaction
Migrationb
Runoff b
Surface
Impoundments
I
I
S
s
N
N
N
N
N
Land
Treatment
I
I
N
N
N
N
N
N
N
Landfill
I
S
N
N
N
N
N
N
N
I   =  Important
S  =  Secondary
N  «  Negligible or not applicable

a  Individual chemicals in a given site type may have dominant pathways
   different from the ones shown here.

b  Water migration and runoff are considered to have negligible effects on
   ground and surface water in a properly sited, operated, and maintained
   RCRA-permitted hazardous waste treatment, storage, and disposal facility.
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     Dispersion models (with input emission rates based on emission models) can
also be used to provide seasonal air concentration  "patterns" based on available
representative historical meteorological data (either onsite or offsite). Comparison
of seasonal air concentration patterns can be used to identify the "reasonable worst
case" period for monitoring. Air concentration patterns based on modeling results
can similarly be used to evaluate the representativeness of the actual data collection
period.   Representativeness is determined by comparing the air  concentration
patterns  for  the actual  air  monitoring  period with  historic seasonal  air
concentration  patterns.

    The objective  of the modeling  applications  discussed above involves the
estimation  of  long-term  (i.e., several months to years) concentration patterns.
These long-term patterns do not have the variability associated  with  short-term
(i.e., hours to days, such as a 24-hour event) emission rate and dispersion conditions,*
and are more conducive to data extrapolation applications.  For example, neart
source and fenceline air monitoring  results can be used to  back calculate an?
emission rate for the source. This estimated emission rate can be used as dispersion
modeling input to estimate offsite air concentrations for the same downwind sector
and exposure period as for the air monitoring period.

12.5.2         Model Selection

     Guidance on the selection and application of dispersion models is provided in
the following references:

     U.S. EPA. July 1986. Guidelines on Air Quality Models (Revised). EPA-450/12-
     78-027R.  NTtS PB86-245248.  Office of Air Quality Planning and Standards.
     Research Triangle Part, NC 27711.

     U.S. EPA.  December 1988 Draft.  Procedures for Conducting Air  Pathway
     Analyses  for Superfund Applications.  Office of  Air Quality Planning and
     Standards.  Research Triangle Park, NC 27711.

     The following  information is based primarily on guidance provided in these
references.
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12.5.2.1  Suitability of Models

     The extent to which a specific air quality model is suitable for the evaluation of
source impact depends upon several factors. These include: (1) the meteorological
and topographic complexities of the area;  (2) the level of  detail  and accuracy
needed for the analysis;  (3) the technical competence of those undertaking such
simulation modeling; (4) the resources available; and (5) the detail and accuracy of
the data  base, i.e., emissions inventory, meteorological data, and air quality data.
Appropriate data should  be available before any attempt is made to apply a model.
A model  that requires detailed, precise, input data should not be used when such
data are  unavailable.  However, assuming the data are adequate, the  greater the
detail with which a model considers the spatial and temporal variations in emissions
and meteorological conditions, the greater the ability to evaluate the source impact
                                                                          e
afid to distinguish the effects of various control strategies.
 '                                                                         ?
     Air  quality models  have  been applied with the  most accuracy or the least
degree of uncertainty to simulations of long term averages in  areas with relatively
simr'e topography.  Areas subject to major topographic influences experience
meteorological  complexities that are extremely difficult to  simulate.  Although
models are available for such  circumstances, they are  frequently site-specific and
resource  intensive.   In  the  absence of a model capable  of simulating  such
complexities, only a preliminary approximation  may be feasible until such time as
better models and data bases become available.

     Models are highly specialized tools.  Competent  and experienced personnel
are an essential prerequisite to the successful application of simulation models. The
need  for specialists is critical when the more sophisticated models are  used or the
                e_
area being investigated has complicated meteorological or topographic features. A
model applied improperly, or with inappropriately chosen data, can lead to serious
misjudgments  regarding the  source impact or the  effectiveness  of a control
strategy.

     The resource demands generated by use  of air  quality models  vary widely
depending  on the  specific application.  The resources required  depend on the
nature of the model and  its complexity, the detail of the data base, the difficulty of
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the application, and the amount and level of expertise required.  The costs of
manpower and computational  facilities may also  be important factors  in the
selection and  use  of a model  for a  specific analysis.   However,  it should be
recognized  that  under  some  sets  of  physical  circumstances and  accuracy
requirements, no present model  may be appropriate. Thus, consideration of these
factors should not lead to selection of an inappropriate model.

12.5.2.2       Classes of Models

     Dispersion models can be  categorized into four generic classes:  Gaussian,
numerical, statistical  or empirical, and physical.  Within these classes, especially
Gaussian and  numerical models, a large number of individual "computational
algorithms"  may exist, each with its own specific applications. While each of the
algorithms may have the same generic basis, e.g., Gaussian, it is accepted practice to
refer to them individually  as models.  In many cases  the  only real difference'
between models within the different  classes is the degree of detail considered in
                                                                           {
the input or output data.

     Gaussian  models are the  most widely used techniques for estimating the
impact of nonreactive pollutants. Numerical models may be more appropriate than
Gaussian models for area source urban applications that involve reactive pollutants,
but they require much more extensive input data bases and resources and therefore
are not as widely applied. Statistical or  empirical techniques are frequently
employed in situations where incomplete  scientific understanding of the physical
and chemical processes or  lack of the required  data bases make the  use of a
Gaussian or numerical model impractical.

     Physical modeling, the fourth generic type, involves  the use of wind tunnel or
other fluid modeling facilities. This class of modeling is a complex process requiring
a high level of technical expertise, as well as access to the necessary  facilities.
Nevertheless, physical modeling  may be useful for complex flow situations, such as
building, terrain or stack down-wash conditions, plume impact on elevated terrain,
diffusion in an urban environment, or diffusion in complex terrain. It is particularly
applicable to such situations for  a source or group of sources in a geographic area
limited to a few square kilometers. The publication "Guideline for Fluid Modeling
                                   12-52

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of Atmospheric Diffusion" provides information on fluid modeling applications and
the limitations of that method (U.S. EPA, 1981).

12.5.2.3       Levels of Sophistication of Models

     In  addition  to the  various classes  of models, there  are two  levels  of
sophistication.  The first level  consists  of general, relatively simple  estimation
techniques that provide conservative estimates of the air quality impact of a specific
source, or source category.   These are screening techniques or screening models.
The purpose of such techniques is to eliminate the need for further more detailed
modeling for those sources that clearly can be characterized and evaluated based
on simple screening assessments.

     The second level consists of those  analytical techniques that provide  more
detailed treatment  of physical and chemical atmospheric processes, require  more
detailed  and  precise input  data, and  provide  more specialized  concentration*
estimates. As a result they provide a more refined and, at least theoretically, a more
accurate  estimate of source impact and the effectiveness of control strategies.
These are referred to as refined models.

     The use  of screening techniques followed by a more refined analysis is always
desirable, however, there  are  situations where the screening techniques are
practically and technically the only viable option for estimating source impact.  In
such cases, an attempt should be made to acquire or improve the necessary data
bases and to develop appropriate analytical techniques.

12.5.2.4       Preferred Models

     Guidance ontPA preferred models for screening and refined applications is
provided in the following references:

     U.S. EPA. July 1986. Guidelines on Air Quality Models (Revised). EPA-450/2-78-
     027R.   NTIS PB86-245248.  Office  of Air  Quality Planning and  Standards.
     Research Triangle Park, N.C.  27711.
                                   12-53

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     U.S. EPA. October 1977. Guidelines for Air Quality Maintenance Planning and
     Analysis. Vol. 10 (Revised):  Procedures for Evaluating Air Quality Impact of
     New Stationary  Sources.  EPA-450/4-77-001.  NTIS PB274-087.  Office of Air
     Quality Planning and Standards. Research Triangle Park, N.C. 27711.

     U.S. EPA.  December 1988 Draft.  Procedures for Conducting Air Pathway
     Analyses for Superfund Applications.  Office of Air Quality Planning and
     Standards.  Research Triangle Park, NC 27711.

     Appropriate dispersion models commensurate with the above guidance and
sutiable for mainframe computer use are included in the UNAMAP series available
from NTIS.  Versions of the UNAMAP models suitable for use on a microcomputer
are also available from commercial sources.

     Alternative screening approaches based on hand calculations are available for
point sources located in flat terrain based on the following guidance:              l
                                                                          t
     Turner, D.B. 1969.  Workbook of Atmospheric Dispersion Estimates. Public
     Health Service. Cincinnati, OH.

     U.S. EPA.   March 1988 Draft.  A Workbook of Screening Techniques for
     Assessing Impacts of Toxic Air Pollutants.  Office of Air Quality Planning and
     Standards.  Research Triangle Park, NC 27711.

     Preferred models for selected applications in simple terrain are identified in
Table  12-8.  Appropriate dispersion  models for complex terrain  applications
generally need to be determined on a case-by-case basis.  Acceptable models may
not be available for many complex terrain applications.
                 t
     The use of the Industrial Source Complex (ISC) Model is recommended as a
prime candidate for RFI atmospheric dispersion modeling applications. Applicable
ISC source types include stack area and volume sources. Concentration estimates
can be based on times of as short as one hour and as long  as one year. The model
can be used for both  flat and rolling terrain.  The ISC model can also account for
atmospheric deposition (i.e., inter-media transport to soil).  The ISC Model (See EPA
                                   12-54

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                                   TABLE 12-8

      PREFERRED MODELS FOR SELECTED APPLICATIONS IN SIMPLE TERRAIN
Short Term (1-24 hours)
Single Source
Multiple Source
Complicated Sources**
Buoyant Industrial Line Sources
Long Term (monthly, seasonal or annual)
Single Source
Multiple Source
Complicated Sources**
Buoyant Industrial Line Sources
Land Use
Rural
Urban
Rural
Urban
Rural/Urban
Rural

Rural
Urban
Rural
Urban
Rural/Urban
Rural
Model*
CRSTER
RAM
MPTER
RAM
ISC*
BLP

CRSTER
RAM
MPTER
COM 2.0 or RAM***
ISC* .
BLP
*  The long-term version of ISC (i.e., ISCLT) is recommended as the preferred dispersion model for
   RFI applications.

** Complicated sources are sources with special problems such as aerodynamic downwash,
   particle deposition, volume and area sources, etc.

***lf only a few sources in an urban area are to be modeled, RAM should be used.
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450/4-86-005a and b) is included in the UNAMAP series available through the NTIS
(U.S. EPA, June 1986).

     Additional guidance on dispersion model selection and application is available
from EPA Regional Office and State modeling representatives as well as from the
EPA Model Clearinghouse.

     If other than preferred models are selected for use, early discussions with the
regulatory  agency is  encouraged.   Agreement on the data base to  be  used,
modeling techniques to be applied and the overall technical approach, prior to the
actual analyses, helps avoid misunderstandings concerning the final results and may
reduce the  later need for additional analyses. The  preparation (and submittal  to
the appropriate regulatory agency) of a written modeling protocol is recommended
for all RFI atmospheric dispersion modeling applications.

12.5.3         General Modeling Considerations

     Dispersion  modeling  results  are  limited  by the  amount, quality and
representativeness of the input data.  In addition to meteorological and source data
modeling input, the following are also important modeling factors:

     •   Location of facility property boundary
     •   Dispersion coefficients
     •   Sta b i I ity categories
     •   Plume rise
     •   Chemical transformation
     •   Gravitational settling and deposition
     •   Urban/rural classification
                 ai

     In designing a computational network for modeling, the emphasis should  be
placed on location with respect to the facility property boundary. The selection of
sites should  be a  case-by-case determination  taking  into  consideration the
topography, the climatology, monitor sites, and should be based on the results of
the initial screening procedure. Additional  locations may be needed in the high
concentration location if greater resolution is indicated by terrain or source factors.
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     Gaussian  models  used  in  most  applications should  employ dispersion
coefficients consistent with those contained in the preferred  models available in
UNAMAP. Factors such as averaging time, urban/rural  surroundings, and type of
source (point vs. line) may dictate the selection of specific coefficients.

     The Pasquill approach  to classifying stability is  generally  required in all
preferred models. The Pasquill method, as modified by Turner, was developed for
use with commonly observed  meteorological  data from the National  Weather
Service (NWS) and is based on cloud cover, insolation and wind speed.

     Procedures  to determine  Pasquill stability categories from other than NWS
data are presented in Guidelines on Air Quality Models  (Revised) (U.S. EPA, July
1986).  Any other method to determine Pasquill stability categories should be
justified on a case-by-case basis.
                                                                          t
     The plume rise methods incorporated  in the EPA preferred models  arer
recommended for use in all modeling applications. No provisions,in these models*
are made for fumigation or multi-stack plume rise enhancement or the handling of
such special plumes as flares; these problems should be considered on a c se-by-case
basis.

     Where  aerodynamic downwash occurs due to the adverse influence of nearby
structures, the algorithms included in the ISC model should  be used.

     Use of models incorporating complex  chemical  mechanisms should  be
considered only on a case-by-case basis with proper demonstration of applicability.
These are generally regional models not designed for the evaluation of individual
sources but used primarily for region-wide evaluations.
                 s_
     An  "infinite ftalf-life* should be used  for  estimates of total suspended
particulate  concentrations when Gaussian models containing  only exponential
decay terms for treating settling and deposition are used. Gravitational settling and
deposition may be directly included in a model if either is a significant factor.  At
least one preferred model (ISC) contains settling and deposition algorithms and is
recommended  for use  when  particulate  matter sources can be  quantified and
settling and deposition are problems.
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     The selection of either rural  or  urban dispersion coefficients in a specific
application should follow one of the  procedures presented in Guidelines on Air
Quality Models  (Revised)  (U.S.  EPA,  July  1986).   These  include a land  use
classification procedure or a population based procedure to determine whether the
character of an area is primarily urban or rural.

12.6      Design of a Monitoring Program to Characterize Releases

     Monitoring procedures should  be developed based  on the information
previously described, including determination of reasonable worst-case scenarios as
discussed above.  This section discusses the recommended monitoring approaches.

     Primary elements in designing a monitoring system include:
 i
     •    Establishing monitoring objectives;                                 *
                                                                          I
     •    Determining monitoring constituents of concern;

     •    Monitoring schedule;

     •    Monitoring approach; and

     •    Monitoring locations.
           *
     Each of  these elements should be addressed to meet the objectives of the
initial monitoring phase, and any subsequent monitoring that may be necessary.
These elements are described in detail below.
                s_
12.6.1         Objectives of the Monitoring Program

     The primary goal  of the air investigation is to determine concentrations at the
facility property  boundary as input to the health and environmental  assessment
process. As discussed previously, the monitoring program may be conducted in a
phased  approach,  using the  results  of  initial monitoring  and/or modeling to
determine the need for and scope of subsequent monitoring.
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     Principal components of both the initial and subsequent monitoring phases
are:

     •    Identification or verification of constituents;

     •    Characterization of long-term air constituent concentrations (based on a
          "reasonable worst case" exposure period) at:
              the unit boundary to maximize the potential for release detection
              the facility property boundary
              actual offsite receptor  locations (for determining  the  need for
              interim corrective measures)
              areas upwind of the release source  (to characterize background
              concentrations); and

     •    Collection of meteorological data during the monitoring period to aid in
          evaluating the air monitoring data.

     Atmospheric   dispersion  modeling   may   also  be  used  to   estimate
concentrations, if monitoring is not practical, as discussed previously.

     Subsequent monitoring may be necessary if initial monitoring  and  modeling
data  were not sufficient  to  characterize  long-term   ambient  constituent
concentrations.

12.6.2         Monitoring Constituents and Sampling Considerations

     Sampling and  analysis  may be conducted for all appropriate Appendix VIII
constituents that have an air pathway potential (See Section 3 and Appendix B).  An
alternative approach  is to  use unit and waste-specific information to  identify
constituents that are not expected to be present and thus, reduce the list of target
monitoring constituents.  For example, the industry specific monitoring constituent
lists  presented  in Appendix B,  List 4 can be used to identify appropriate  air
monitoring constituents for many applications (especially for units that serve only a
limited number of industrial categories). The target constituents selected should be
                                    12-59

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limited to those which may be present in the waste and have health criteria for the
air pathway (see Section 8).

     Results from screening assessment,  emission  monitoring, and/or  screening
sampling phase (as defined later in Section 12.6.4.1) may also be used as a basis for
selection  of monitoring  constituents.   These   results  may  confirm/identify
appropriate monitoring constituents for the unit of concern.

12.6.3          Meteorological Monitoring

     Monitoring of onsite meteorological conditions should be  performed  in
concert with other emission rate and  air monitoring activities.  Meteorological
monitoring results can serve as input for dispersion models, can be used to assure
that the air monitoring effort is conducted during the appropriate meteorological
conditions (e.g., "reasonable worst case" period for initial monitoring), and to aid
in the interpretation of air monitoring data.

12.6.3.1        Meteorological Monitoring Parameters

     The following  meteorological parameters should  be routinely  monitored
while collecting ambient air samples:

     •    Horizontal wind speed and direction;

     •    Ambient temperature;

     •    Atmospheric stability (e.g., based on the standard deviation of horizontal
          wind direction or alternative standard methodologies);
                 SL

     •    Precipitation measurements if representative National Weather Service
          data are not available; and

     •    Atmospheric pressure (e.g., for landfill sites or contaminated  soils) if
          representative National Weather Service data are not available.
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     It is recommended that horizontal  wind  speed and direction,  and  air
temperature  be  determined  onsite  with  continuous recording  equipment.
Estimates from offsite monitors are not likely to  be representative for all of the
conditions at the site.   Input parameters for dispersion models, if appropriate,
should be reviewed prior to conducting the meteorological data collection phase to
ensure that all necessary parameters are included.

     Field  equipment   used  to  collect  meteorological  data  can range  in
sophistication from small, portable, battery-operated units  with wind speed and
direction sensors, to large, permanently mounted, multiple sensor units at varying
heights.  Individual sensors can collect data on horizontal wind speed and direction,
three-dimensional wind speed, air temperature, humidity, dew point, and mixing
height. From such data, variables for dispersion models such as wind variability and
atmospheric stability can be determined. Additional guidance on meteorological
measurements can be obtained from:

     U.S.  EPA.   June  1987.   On-Site  Meteorological  Program  Guidance  for
     Regulatory Modeling  Applications.  EPA-450/4-87-013.  Office of Air Quality
     Planning and Standards. Research Triangle Park, N.C. 27711.

     U.S. EPA.  February 1983.  Quality Assurance handbook  for- Air Pollution
     Measurements Systems:  Volume IV.  Meteorological  Measurements.  EPA-
     600/4-82-060. Office of Research and  Development. Research Triangle Park,
     N.C. 27711.

     U.S. EPA. July 1986. Guidelines on Air Quality Models (Revised). EPA-405/2-78-
     027R.  NTIS  PB 86-245248.  Office  of Air Quality Planning and Standards.
     Research Triangle Park, N.C. 27711.

Appropriate performance specifications for monitoring equipment are given in  the
following document:

     U.S. EPA.  November 1980. Ambient Monitoring Guidelines for Prevention of
     Significant Deterioration  (PSD). EPA-450/4-80/012. NTIS PB  81-153231.  Office
     of Air Quality Planning and Standards.  Research Triangle Park, N.C. 27711.
                                   12-61

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12.6.3.2       Meteorological Monitor Siting

     Careful placement of meteorological monitoring equipment (e.g., sensors) is
important in gathering  relevant data.  The objective  of  monitoring tower
placement is to position  sensors to  obtain  measurements representative of the
conditions that  determine atmospheric dispersion in the  area of interest.  The
convention for placement of meteorological monitoring equipment is:

     •   At or above a height of 10 meters above ground; and

     •   At a horizontal distance of 10 times the obstruction  height from any
         upwind obstructions.

In addition, the recommendations given  in Table 12-9 should be followed to avoid
effects of terrain on meteorological monitors.

     Depending on the complexity of the terrain  in the area of interest  and the
parameters being measured, more than one  tower location may be necessary.
Complex terrain can greatly influence the transport and diffusion of a contaminant
release to air so that one tower may not able to account for these influences. The
monitoring station height may also vary depending on source characteristics and
logistics.  Heights should be selected to minimize near-ground effects that are not
representative of conditions in  the atmospheric layer into which  a constituent of
concern is being released.

     A tower designed specifically to mount meteorological instruments should be
used. Instruments should  be mounted on booms projecting horizontally out from
the tower at a minimum distance of twice the tower diameter. Sound engineering
practice should  be used to  assure tower integrity  during  all  meteorologic
conditions.

     Further guidance on  siting meteorological  instruments   and  stations is
available in the following publications:
                                   12-62

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                    TABLE 12-9
RECOMMENDED SITING CRITERIA TO AVOID TERRAIN EFFECTS
Distance from Tower
(meters)
0 -15
15-30
30-100
100-300
Maximum Acceptable Construction
or Vegetation Height
(meters)
0.3
0.5-1.0
3
10
                       12-63

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     U.S. EPA. November 1980.  Ambient Monitoring Guidelines for Prevention of
     Significant Deterioration (PSD). EPA-450/4-80-012. NTIS PB 81-153231. Office
     of AirQuality Planning and Standards.  Research Triangle Park, N.C. 27711.

     U.S.  EPA.   June 1987.   On-Site  Meteorological  Program  Guidance  for
     Regulatory  Modeling Applications.  EPA-450/4-87-013.  Office of Air Quality
     Planning and Standards.  Research Triangle Park, N.C. 27711.

     U.S. EPA.   February  1983.  Quality Assurance Handbook for Air Pollution
     Measurement Systems:   Volume IV.  Meteorological  Measurements.  EPA-
     600/4-82-060. Office  of Research and  Development. Research Triangle Park,
     N.C. 27711.

12.6.4         Monitoring Schedule
                                                                          t
     Establishment of a monitoring schedule is an important  consideration in
developing a monitoring plan. When appropriate, air monitoring'should coincide
with monitoring  of other media (e.g., subsurface gas, soils, and surface water) that
have the potential for ai.  emissions.  As with all other aspects of the monitoring
program, the objectives of monitoring should  be considered in  establishing  a
schedule.   As indicated previously, monitoring generally consists of screening
sampling, emission monitoring, and air monitoring.   The  monitoring schedule
during each of these phases is discussed below.

12.6.4.1       Screening Sampling

     A limited screening sampling effort may be necessary to focus the design of
additional  monitoring phases.  Therefore, screening samples may be warranted
during the screening assessment or prior to  initiating emission monitoring or air
monitoring studies. This screening phase can also be used to supplement modeling
and emission monitoring results as available, to verify the existence of a release to
air, and to prioritize the major release sources at the facility.

     Screening sampling should be used to characterize air emissions (e.g., by using
total hydrocarbon measurements as an indicator), and to confirm/identify  the
presence of candidate constituents.  Screening samples should generally consist of
                                   12-64

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source emissions measurements or ambient air samples collected, at or in  close
proximity to the  source.  This approach will  provide  the  best opportunity for
detection of air emission constituents. (A discussion of available screening methods
is presented in Section 12.8.) An alternative screening approach involves collection
of a limited number of air samples to facilitate the analysis of a wide range of
constituents (e.g., collection via Tenax adsorption tubes or whole air sampling with
analysis by GGMS - see Section 12.8).

     The screening study should generally involve collection of a limited number of
grab or time-integrated samples (several minutes to 24 hours) for a limited time
period  (e.g.,  one  to  five .days).    Sampling  should  be  conducted  during
emission/dispersion  conditions  that  are expected  to  result  in relatively  high
concentrations, as discussed previously.  Screening results should be interpreted
considering the representativeness of the waste and unit operations during the
sampling, and the detection capabilities of the screening methodology used.
                                                                           I
12.6.4.2       Emission Monitoring

     Emission rate  monitoring may  be necessary  to  characterize a  release  if
screening assessment results are not conclusive. This approach involves stack or vent
emission monitoring for point sources.  Point source monitoring is not dependent
on meteorological conditions. However, emission rate monitoring for both point
and area sources should be conducted during typical or "reasonable worst case"
emission rate conditions.  Therefore,  emission monitoring  should  be  conducted
when source conditions (e.g., unit operations and waste concentrations) as well as
meteorological conditions are conducive to  "reasonable worst case" emission rate
conditions.  Emission rate monitoring for area sources should  not  be  conducted
during or immediately following precipitation or if hourly average wind speeds are
                 s^
greater than 15 miles per hour. It should also be noted that soil or cover material (if
present) should be  allowed to dry prior to  continuing monitoring operations, as
volatilization decreases under saturated soil  conditions.   In  these  cases, the
monitoring  should  be interrupted  and  resumed  as soon  as  possible after the
unfavorable  conditions pass.  Similarly, operational  interruptions  such  as  unit
shutdown should also be factored into the source sampling schedule.
                                    12-65

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     Point  source emission sampling  generally requires  only  a  few hours  of
sampling and occurs during a more limited time (e.g., one to three days). Guidance
on point-source sampling schedules is presented in the following:

     U.S. EPA.  November 1985.  Practical Guide - Trial Burns for Hazardous Waste
     Incinerators.   NTIS PB 86-190246.  Office of  Research  and Development.
     Cincinnati, OH 45268.

     U.S. EPA.  Code of Federal  Regulations.  40 CFR Part 60:   Appendix  A:
     Reference Methods. Off ice of the Federal Register. Washington, D.C.

     U.S. EPA.  1978.  Stack Sampling Technical  Information. A  Collection  of
     Monographs and Papers. Volumes Nil.  EPA-450/2-78-042a,b,c.  NTIS PB 80-
     161672, 80-161680, 80-161698. Office of Air Quality Planning and Standards.
     Research Triangle Park, NC 27711.

     U.S. EPA.  February 1985.  Modified Method 5 Train and'Source Assessment
     Sampling  System Operators Manual.  EPA-600/8-85-003.  NTIS PB 85-169878.
     Off ice of Research and Development. Research Triangle Park, NC 27711.

     U.S. EPA.  March 1984. Protocol for the Collection and  Analysis of Volatile
     POHCs Using  VOST. EPA-600/8-84-007.  NTIS PB 84-170042. Office of Research
     and Development. Research Triangle Park, NC 27711.

     U.S. EPA.  February 1984.  Sampling  and Analysis Methods for Hazardous
     Waste Combustion. EPA-600/8-84-002. NTIS PB 84-155845. Washington, D.C.
     20460.

     U.S. EPA.  198\  Source Sampling and Analysis of Gaseous Pollutants.  EPA-
     APTI Course  Manual 468.  Air Pollution Control Institute. Research Triangle
     Park, NC 27711.

     U.S. EPA.  1979.  Source Sampling for Paniculate Pollutants.  EPA-APTI Course
     Manual 450.  NTIS PB 80-188840, 80-182439, 80-174360. Air Pollution Control
     Institute.  Research Triangle Park,  NC 27711.
                                   12-66

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     U.S. EPA. 1986.  Test Methods for Evaluating Solid Waste. 3rd Edition. Office
     of Solid Waste.  EPA/SW-846.  GPO No. 955-001-00000-1. Washington, D.C
     20460.

     Emission rate monitoring should be conducted during a 1 to 3 day period
representative of  "reasonable worst case" source emission conditions.  The worst
case short-term emission rate conditions should be determined by  parametric
analyses  (i.e., by  modeling a wide range of source operational  conditions and
associated  waste  concentrations  as well  as meteorological   conditions  for
parameters such as wind speed and temperature).  Historical meteorological data
representative of the site should be reviewed to determine the season and time of
day associated with worst case emission conditions. These results should be used to
select and schedule (along with meteorological forecasts for local conditions and
expected source operational and waste concentration)  the emission monitoring
period.                                                                    t
                                                                          I
     Emission rate monitoring results based on measurements during worst-case
conditions should be initially used  as dispersion modeling input.  If these initial
results exceed health  criteria then the emission monitoring  results should be scaled
to represent long term (i.e., annual) conditions.  The scaling factor should be based
on the ratio of emission  rate modeling results (using meteorological conditions
during the monitoring period as input)  compared to modeling results based on
typical (annual) meteorological conditions.

     Guidance on area  source  emission  rate monitoring  is  provided in  the
following:

     U.S. EPA. 19^6. Measurement of Gaseous Emission Rates from Land Surfaces
     Using an Emission Isolation Flux Chamber: User's Guide. EPA/600/8-86/008.
     NTISPB86-223161. Environmental Monitoring Systems Laboratory. Las Vegas,
     NV  89114.

     U.S. EPA.  December 1988 Draft.   Procedures for Conducting Air  Pathway
     Analyses for Superfund Applications.  Office  of  Air Quality Planning and
     Standards. Research Triangle Park, NC 27711.
                                   12-67

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12.6.4.3       Air Monitoring

     The primary objective of confirmatory monitoring is to characterize long-term
exposures that may be associated with air emissions from the unit under reasonable
worst-case  conditions.  A schedule  should  be proposed that  will provide an
adequate degree of confidence that those compounds that may be released will be
detected (i.e., by sampling  during the season associated with the highest air
concentrations as determined  based on modeling).  Laboratory analytical  costs
typically range from $200 to over $1,000 per air monitoring station for one 24-hour
integrated  sample (the  actual cost depends on the number and type of target
constituents).  Recent advances in applied technology have facilitated the use of
field gas chromatographs (GCs) to automatically obtain analytical results for many
organics  (i.e., offsite laboratory  analyses may not be  necessary  for some air
monitoring programs). The cost for this equipment typically range from $20,000 to
over $50,000 and one GC can generally service multiple sampling stations.

     An  example  sampling  schedule (e.g., for flat terrain  sites with  minimal
variability of  dispersion and source conditions) for meeting this objective is given
below:

     •   Meteorological monitoring - 90 days continuous monitoring.

     •   Initial air monitoring (Alternative 1) -90 days:
              Analysis of 24-hour time integrated samples for target constituents
              every day during the 90-day period (total of 90 samples)

     •   Additional monitoring - as necessary to supplement initial air monitoring
         results in order to adequately characterize the release.
                 Si

     The 90-day monitoring program will facilitate collecting samples over a wide
range of emission and dispersion conditions.  The 90-day period should be selected,
as previously  discussed, to coincide with the expected season of highest  ambient
concentrations. Meteorological monitoring should  be continuous and concurrent
with this 90-day period to adequately characterize dispersion conditions at the site
and  to provide meteorological data to  support interpretation of the  air-quality
monitoring data.
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     The collection of a time-integrated sample based on continuous monitoring
for several days can result in technical difficulties (e.g., poor collection efficiencies
for volatile constituents or large  sample volumes).  The application of five-day
composite samples at each station, or intermittent sampling during the five days,
results in continuous  monitoring coverage during the 90-day period and facilitates
the characterization of long-term exposure levels.

     Although there are some limitations associated with composite/intermittent
sampling (e.g.,  the  potential  for  sample degradation), the 24-hour samples
collected every sixth day will provide a second data set for characterizing ambient
concentrations.  Although the results of the two data sets should not be directly
combined  (because   of  the  different  sampling   periods)  they  provide  a
comprehensive technical basis by which to evaluate long-term exposure conditions.

12.6.4.4       Subsequent Monitoring

     Subsequent monitoring may  be necessary if initial monitoring data were not
sufficient to estimate "reasonable  worst case" long-term concentrations (e.g., data
recovery was not sufficient or additional monitoring stations are needed).

     The same schedule specified for the initial monitoring phase is also applicable
to subsequent monitoring. However, when evaluating the results of subsequent
monitoring and comparing them to previously collected data, potential differences
in emission/dispersion conditions and other data representativeness factors should
be accounted for.

12.6.5        Monitoring Approach
                 EL

     The RFI air release characterization  strategy may involve  source  emission
monitoring and/or air  monitoring.  The strategy which defines the process for
selection and application of these  alternative monitoring approaches has been
discussed previously.  A summary of applicable air monitoring strategies related to
source type is presented in Table 12-10.
                                   12-69

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                            TABLE 12-10
     APPLICABLE AIR RELEASE SAMPLING STRATEGIES BY SOURCE TYPE
     Unit Type/Expected Emission
                                       Air Release Sampling Strategy
                                       Air
                                    Monitoring
                                                Emissions Monitoring
        Vent/Stack
        Sampling
        Isolation
          Flux
       Chambers
AREA SOURCES WITH LIQUID SURFACES
   Surface Impoundments
     Vapor Phase
     Particulates
   Open Roof Storage/Treatment
   Tanks
     Vapor Phase
X
X
AREA SOURCES WITH SOLID SURFACES
   Waste Piles
     Vapor Phase
     Particulates
   Landfill Surface
     Vapor Phase
     Particulates
   Land Treatment
     Vapor Phase
     Particulates
X
X

X
X

X
X
POINT SOURCES
   Vents from container Handling
   Units
     Vapor Phase
   Landfill Vents
     Vapor Phase
   Storage/Treatment Tank Vents
     Vapor Phase
   Incinerators ,
     Vapor Phase
     Particulates
X

X

X

X
X
X

X

X

X
X
                                12-70

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12.6.5.1       Source Emissions Monitoring

     Monitoring at the source to measure a rate of emission for the constituents of
concern may,  in many cases,  offer a practical  approach  to  characterizing air
emissions. Using this technique, the emission rate is then input into a mathematical
dispersion  model  for  estimation of  downwind  concentrations.   Monitoring
interferences from  sources close to the unit are eliminated  because the source  is
isolated from the ambient atmosphere for monitoring purposes.  Source monitoring
techniques are also  advantageous  because  they  do  not  require the  level  of
sensitivity required  by air monitors. Concentrations of airborne constituents at the
source are generally  higher than  at  downwind  locations due to the lack of
dispersion of the constituent over a wide area.  The  concentrations expected in the
air (generally part-per-billion levels) may be at or near the limit of detectability of
the methods used. Methods for source emissions monitoring for various constituent
classes are discussed in Section 12.8.                                           t
                                                                          !
     Area  sources   (such as  landfills,   land treatment  units,  and  surface
impoundments) can be monitored using the isolation flux chamber approach. This
method involves isolating  a small area of contamination  under a flux chamber, and
passing a known amount  of a zero hydrocarbon carrier  gas through the chamber,
thereby picking up any organic emissions in the effluent gas stream from the flux
chamber. Samples of this effluent stream are collected in inert sampling containers,
usually stainless steel canisters under vacuum,  and  removed to  the laboratory for
subsequent  analysis.   The analytical results  of  the identified analytes can  be
converted through  a series of calculations to direct  emission  rates from the source.
These  emission rates can be  used to evaluate  downwind  concentrations  by
application of dispersion models. Multiple emission tests should be conducted to
account for temporal  and spatial variability of source conditions. More information
on use of the isolation flux chamber and test design is  provided in the following
references:

     U.S. EPA.  1986.  Measurement of Gaseous Emission Rates from Land Surfaces
     Using an  Emission Isolation  Flux Chamber:  User's  Guide.  EPA/600/8-86/008.
     NTISPB 86-223161. Washington, D.C. 20460.
                                   12-71

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     U.S. EPA.  December 1988 Draft.  Procedures for Conducting Air Pathway
     Analyses for Suoerfund Applications.  Office of Air Quality Planning and
     Standards. Research Triangle Park, NC 27711.

     Some  area source  units  may not  be amenable to the source sampling
approach, however.  A unit in which the source  cannot be isolated  and viable
measurements taken of the parameters of concern is one example.  This includes
active areas of landfills and  land-treatment areas, as well as aerated surface
impoundments.  Also, area sources in which particulate emissions are of concern
cannot be measured using an isolation flux chamber due to technical limitations in
the technique.   For these applications,  only an  upwind/downwind  monitoring
approach should be used.

12.6.5.2       Air Monitoring
                                                                         *
 t
     Use of an upwind/downwind network of monitors or sample collection devices
is the primary air monitoring approach recommended to determine release and
background concentrations of the constituents of concern.  Upwind/downwind air
monitoring networks provide concentrations of the constituents of concern at the
point of monitoring, whether at the unit boundary,  facility property boundary, or at
a receptor  point.  The upwind/downwind approach involves the placement  of
monitors or sample collection devices at various points around the unit of concern.
Each air sample collected is classified as upwind or downwind based on the wind
conditions for the sampling period.  Downwind concentrations are compared  to
those measured at upwind points to determine the  relative contribution of the unit
to air concentrations  of  toxic compounds.  This is  generally accomplished  by
subtracting the upwind concentration (which represents background  conditions)
from the concurrent downwind concentrations. Applicable field methods for air
                t
monitoring are discussed in Section 12.8 as well as in Procedures for Conducting Air
Pathway Analyses for Superfund  Applications  (U.S.  EPA, December  1988).
Downwind air concentrations at the facility can be extrapolated to other locations
by using dispersion modeling results.  This is accomplished by obtaining initial
modeling results based on meteorological conditions for the monitoring period and
an arbitrary emission rate.  These initial dispersion modeling results  along with
monitoring results at the site perimeter are used to back calculate an emission rate
such that modeling results can be adjusted to be equivalent to monitoring results at
                                   12-72

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the onsite  monitoring station.   This  estimated  emission  rate is then used as
dispersion modeling input to predict offsite concentrations.

12.6.6         Monitoring Locations

     As with other factors associated with air monitoring, siting of the monitors
should reflect the primary objective of characterizing concentrations at the facility
property boundary.    This  section  discusses monitoring  locations  for  both
upwind/downwind approaches and source monitoring techniques.

12.6.6.1       Upwind/Downwind Monitoring Locations

     The air monitoring  network design  should provide  adequate coverage to
characterize both upwind (background) and downwind concentrations. Therefore,
four air monitoring zones are generally necessary for initial monitoring.  Multiple^
monitoring stations per zone will frequently be required to adequately characterize^
the release. An  upwind zone is used to define background concentration levels.
Downwind  zones at the unit boundary,  at the  facility property boundary and
beyond the facility property boundary, if appropriate, are used to define potential
offsite exposure.

     The location of air monitoring stations should be based on local wind patterns.
Air monitoring stations should be placed at strategic locations, as illustrated in the
following example (see Figure 12-6).

     •   Upwind (based on  the expected prevailing wind flow during the 90-day
         monitorjng period) of the unit and near the facility property boundary to
         characterize background air concentration levels. There should be no air
         emission_source between the upwind monitoring station and the unit
         boundary.

     •   Downwind (based  on the expected prevailing wind flow during the 90-
         day monitoring period) at the unit boundary plus stations at adjacent
         sectors also  at the unit boundary (the separation distance  of air
         monitoring stations at  the unit boundary should be 30° or 50  feet,
         whichever is greater).
                                   12-73

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                                        12-74

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     •    Downwind (based on the expected prevailing wind flow during the 90-
          day monitoring period) at the facility property boundary (this station
          may not be required if the site perimeter is within 100 meters of the unit
          boundary).

     •    Downwind  (at the area expected  to have the  highest average
          concentration levels during the 90-day monitoring period) at the facility
          property boundary, if appropriate.

     •    Downwind at actual offsite receptor locations (if appropriate).

     •    Additional locations at complex terrain and  coastal sites associated with
          pronounced secondary air flow paths (e.g.,  downwind of the unit near
          the facility property boundary for both primary daytime and nighttime
          flow paths).                                                      .

     The above locations should be selected prior to initial monitoring based on the
onsite meteorological survey and on evaluation of available  representative offsite
meteorological data. This analysis should provide an estimate  of expected wind
conditions during the 90-day initial monitoring period. If sufficient representative
data are  available, dispersion modeling can be  used to  identify the  area of
maximum long term concentration levels at the facility property boundary and, if
appropriate, at actual offsite receptors. If not, the facility property boundary sector
nearest to the unit of concern should be selected for initial monitoring.

     The network design defined above will  provide an adequate basis to define
long-term concentrations based on continuous monitoring during the 90-day initial
monitoring period.. The monitoring stations at the unit boundary should increase
the potential for release detection.  The facility property boundary air monitoring
stations should provide data (with the aid of dispersion modeling, if appropriate) to
perform  health and environmental  assessment, and  if appropriate, characterize
offsite concentrations.

     Air  monitoring at  offsite receptors (if deemed  to be  appropriate) may be
impractical in many cases, because analytical  detection  limits may not be  low
                                   12-75

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enought at offsite receptor locations to measure the release. Also, a 90-day offsite
monitoring program can be problematic.  Factors such as vandalism, erroneous
readings due to public tampering with the equipment, public relations problems in
setting up the equipment, and legal access problems may preclude the use of offsite
air  monitoring stations.   For these cases, dispersion  models  may  be used  to
extrapolate monitoring data collected at the facility to  actual offsite receptor
locations.   This is accomplished  by obtaining initial modeling results based on
meteorological conditions for the monitoring period and an arbitrary emission rate.
These initial dispersion modeling results along with monitoring results at the site
perimeter are used to back calculate an emission rate such that modeling results can
be adjusted to be equivalent to monitoring results at the onsite monitoring station.
This estimated emission rate is then used as dispersion modeling input to predict
offsite concentrations for the same downwind sector and exposure period as for this
monitoring period.

     If  additional monitoring  is required, a  similar  network design  to that
illustrated  in  Figure  12-6 will  generally  be appropriate.   Evaluation of the
meteorological monitoring data collected during the initial phase should provide an
improved  basis to identify  local prevailing and diurnal wind flow paths. Also, the
site meteorological data will provide dispersion modeling input. These modeling
results should  provide  dilution patterns that  can  be used to identify areas with
expected  relatively  high  concentration  levels.   However, these results should
account for seasonal meteorological differences  between initial  and additional
monitoring periods.

     Wind-directionally controlled air monitoring stations can also be used at sites
with highly variable wind directions. These wind-directionally controlled stations
should be collocated with  the fixed monitoring stations. This approach facilitates
determination of the unit source contribution to total constituent levels in the local
area.  These automated stations will only sample for a user-defined range of wind
directions (e.g., downwind stations would only sample if winds were blowing from
the source towards the station).  Interpretation of results from wind-directionally
controlled air monitoring stations should  account for the lower sampling volumes
(and therefore, the possibility that not enough  sample would be  collected for
analysis) generally associated with this approach.
                                   12-76

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     The inlet exposure height of the air monitors should be 2 to 15 meters to be
representative .of potential inhalation exposure but not unduly biased by road dust
and natural wind erosion phenomena. Further guidance on air monitoring network
design and  station exposure criteria  (e.g., sampling  height and  proximity to
structures and air emission sources) is provided in the following reference:

     U.S. EPA.  September 1984. Network Design and Site  Exposure Criteria for
     Selected Non-criteria Air Pollutants. EPA-450/4-84-022.  Office of Air Quality
     Planning and Standards. Research Triangle Park, N.C.

     The above referenced document recommends the use of dispersion  models to
identify potential relatively high concentration areas as a basis for network design.
This topic is also discussed in the following document:

     U.S. EPA. July 1986. Guidelines on Air Quality Models (Revised). EPA-450/2-78-
     027R.   NTIS PB  86-245248.  Office of Air Quality Planning  and Standards.
     Research Triangle Park, NC 27711.

     Uniformity among  the sampling sites should  be achieved to the greatest
degree  possible.  Descriptions should be prepared for all  sampling sites.  The
description  should include the type of ground surface, and the direction, distance,
and approximate height with respect to  the source of the release. Location should
also be described on a facility map.

12.6.6.2        Stack/Vent Emission Monitoring

     Point source measurements should be taken  in the vent. Both the  VOST and
Modified Method 5 methodologies describe the exact placement in the stack for the
sampler inlet. (See Section 12.8.3). If warranted, an upwind/downwind monitoring
network can be used to supplement the release rate data.

12.6.6.3        Isolation Flux Chambers

     Monitor placement using flux chambers (discussed  earlier)  is similar to
conducting a characterization of any area source.  Section 3 of this guidance
discusses establishment of a grid network for sampling. Such a grid should be
                                   12-77

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established for an area source, with sampling points established within the grids, as
appropriate.  It is suggested  that a minimum of six points  be chosen for each
monitoring effort. Once these areas are sampled, the results can be temporally and
spatially averaged to provide an overall  compound specific emission rate for the
plot.  Additional guidance on monitoring locations for isolation flux chambers  is
presented in Section 3.6 and in the following references:

     U.S. EPA. 1986.  Measurement of Gaseous Emission Rates from Land Surfaces
     Using an Emission Isolation Flux Chamber:  User's Guide.  EPA/600/8-86/008.
     NTIS PB86-223161. Environmental Monitoring Systems Laboratory.  Las Vegas,
     NV89114.

     U.S.  EPA.  December 1988  Draft.   Procedures for Conducting Air Pathway
     Analyses for Superfund  Applications.  Office  of Air Quality  Planning and
     Standards. Research Triangle Park, NC 27711.

12.7 Data Presentation

     As discussed in Section 5, progress reports will  be required by the  regulatory
agency at periodic  intervals during  the investigation.  The following  data
presentation formats are suggested for the various phases of the air investigation in
order to adequately characterize concentrations at actual offsite receptors.

12.7.1         Waste and Unit Characterization

     Waste and unit characteristics should be presented as:

     •    Tables of waste constituents and concentrations;

     •    Tables of relevant physical/chemical properties for potential air emission
          constituents;

     •    Tables and narratives describing unit dimensions and special operating
          conditions  and operating schedules concurrent with the  air monitoring
          program;
                                   12-78

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     •   Narrative description of unit operations; and

     •   Identification  of "reasonable worst  case"  emission  conditions  that
         occurred during the monitoring period.

12.7.2         Environmental Setting Characterization

     Environmental characteristics should be presented as follows:

     •   Climate (historical summaries from available onsite and offsite sources):

              Annual and monthly or seasonal wind roses;

              Annual and monthly or seasonal tabular summaries of mean wind
              speeds and atmospheric stability distributions; and

              Annual and monthly or seasonal tabular summaries of temperature
              and precipitation.

     •   Meteorological survey results:

              Hourly listing of all  meteorological  parameters for the entire
              monitoring period;

              Daytime wind rose (at coastal or complex terrain sites);

              Nighttime wind rose (at coastal or complex terrain sites);

              Summary wind rose for all hours;

              Summary of dispersion conditions for the  monitoring period (joint
              frequency  distributions  of wind  direction  versus wind speed
              category and stability class frequencies); and

              Tabular summaries of means and extremes for temperature and
              other meteorological parameters.
                                   12-79

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     •    Definition of soil conditions (if appropriate):

               Narrative of soil characteristics  (e.g., temperature,  porosity and
               organic matter content); and

               Characterization  of soil contamination conditions (e.g.,  in  land
               treatment units, etc.).

     •    Definition of site-specific terrain and nearby receptors:

               Topographic map of the site  area with identification of the units,
               meteorological and air monitoring stations, and facility property
               boundary;

               Topographic map of 10-kilometer radius from site (U.S. Geological
               Survey 7.5 minute quadrangle sheets are acceptable); and

               Maps which indicate  location  of nearest  residenc: for each  of
               sixteen 22.5 degree sectors which correspond  to major compass
               points (e.g.,  north, north-northwest, etc.), nearest population
               centers and sensitive receptors (e.g., schools, hospitals and nursing
               homes).

     •    Maps showing the topography of the area,  location of the unit(s)  of
          concern, and the location of  meteorological monitoring equipment.

     •    A narrative description of the meteorological conditions during  the air
          sampling periods, including qualitative descriptions  of weather events
          and precipitation which are needed for data interpretation.

12.7.3          Characterization of the Release

     Characteristics of the release should be presented as follows:

     •    Screening sampling:
                                   12-80

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          Identification of sampling and analytical methodology;

          Map which identifies sampling locations;

          Listing  of measured  concentrations indicating  collection time
          period and locations;

          Prioritization of  units  as  air  release  sources  which  warrant
          monitoring based on screening results;

          Discussion of QA/QC results; and

          Listing and discussion of meteorological data during the sampling
          period.

•    Initial and additional monitoring results:

          Identification of monitoring constituents;

          Discussion of sampling  and analytical  methodology as  well  as
          equipment and specifications;

          Identification of monitoring zones as defined in Section 12.6.6.1;
                               *

          Map which identifies monitoring locations relative to units;

          Discussion of QA/QC results;

          Listing  of concentrations  measured  by station  and monitoring
          period  indicating  concentrations of all  constituents for which
          monitoring was conducted. Listings should indicate detection limits
          if a constituent is not detected;

          Summary tables of concentration measured indicating maximum
          and mean concentration values for each monitoring station;
                               12-81

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Discussion of  meteorological station  locations selection, sensor
height,   local   terrain,   nearby  obstructions  and   equipment
specifications;

Listing of all meteorological  parameters  concurrent with the air
sampling periods;

Daytime wind rose (only for coastal or complex terrain areas);

Nighttime wind rose (only for coastal or complex terrain areas);

Summary wind rose based on all wind direction observations for the
sampling period;

Summary of dispersion conditions for the sampling period (joint
frequency distributions  of wind  direction versus wind speed
category  and  stability  class  frequencies based  on guidance
presented in Guidelines on Air Quality Models (Revised). (U.S. EPA,
July 1986));

Tabular summaries of means  and extremes for temperature and
other meteorological parameters;

A  narrative  discussion of sampling results, indicating problems
encountered, relationship of the sampling  activity to unit operating
conditions and meteorological  conditions, sampling  periods and
times, background levels and identification of other air emission
sources   and   interferences   which  may   complicate   data
interpretation;

Presentation and discussion of models used (if any), modeling input
data and modeling output data (e.g., dilution or dispersion patterns
based on modeling results); and
                     12-82

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              Concentrations based on monitoring and/or modeling for actual
              offsite receptor locations.

     Interpretation of air monitoring results should also  account for additional
factors such as complex terrain, variable winds, multiple contaminant sources and
intermittent or irregular releases.  The key to data interpretation for these cases is
to evaluate monitoring results as a function of wind direction.

     Terrain  factors can  alter wind  flow trajectories especially during stable
nighttime conditions.  Therefore, straightline wind trajectories  may not  occur
during these conditions if there is intervening terrain between the source and the
air monitoring station.  For these cases wind  flows will be directed around large
obstacles (such as  hills) or channeled (for flows within valleys).  Therefore, it is
necessary to determine the representativeness of the data from the meteorological
stations as a function of wind  direction, wind speed and stability conditions. Based
on  this assessment, and  results  from the meteorological survey, upwind and
downwind sectors (i.e., a range of wind direction as measured at the meteorological
station) should  be  defined  for each  air monitoring station  to aid  in  data
interpretation. Figure 12-7 illustrates an example which classifies a range of wind
directions during which the air monitoring stations will be downwind  of an air
emission source.  Therefore, concentrations measured during upwind conditions can
be  used to characterize  background  conditions and concentrations  measured
during downwind  conditions  can  be used to evaluate the air-quality impact of the
release.

     Complex terrain  sites and coastal sites frequently  have  very pronounced
diurnal wind patterns.  Therefore, as  previously  discussed,  the air monitoring
network at these sites may involve coverage for multiple wind direction sectors and
use of wind-directionally controlled air samplers.  This monitoring  approach is also
appropriate for sites with highly variable wind conditions.  Comparing results from
two collocated air monitoring stations (i.e., one station which samples continuously
and a second station at the same location which is wind-directionally controlled on
an automated basis), facilitates determination of source contributions to ambient
air concentrations.
                                    12-83

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                      FIGURE 12-7
EXAMPLE OF DOWNWIND EXPOSURES AT AIR MONITORING STATIONS
    MONITORING STATIONS
    DOWNWIND SECTOR
                                       UNIT SOURCE
                        12-84

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     Comparison of results from collocated (continuous versus wind-directionally
controlled) air monitoring stations can also be used to assist in data interpretation
at sites with multiple air emission sources  or with intermittent/irregular releases.
For some situations, the consistent appearance of certain air emission constituents
can be used to "fingerprint" the source.  Therefore, the air monitoring results can
be classified based on  these "fingerprint" patterns.   These results can then  be
summarized as two separate  data sets  to assess  background  versus  source
contributions to ambient concentrations.

     The  use  of  collocated (continuous and wind-directionally controlled)  air
monitoring stations is a preferred approach to data interpretation  for complex
terrain, variable wind, multiple source and intermittent release sites. An alternative
data interpretation approach involves reviewing the hourly meteorological data for
each air sampling period.   Based  on this review, the results from  each  sampling
period (generally a 24-hour period) for each station are classified in  terms of
downwind frequency. The downwind frequency is defined as the number of hours
winds were blowing from the source towards the air monitoring station divided by
the total number of hours in the sampling period. These data can then be processed
(by plotting scattergrams) to determine the relationship of downwind frequency to
measured concentrations.

     Data interpretation should also take into account the potential for deposition,
degradation and transformation of the monitoring constituents. These mechanisms
can affect ambient concentrations as well as air sample chemistry (during storage).
Therefore, standard technical references on chemical.properties,  as well as the
monitoring  guidance previously  cited,  should  be consulted  to determine the
importance of degradation and  transformation for the monitoring constituents of
concern.

12.8      Field Methods

     This  section  describes  field  methods which can be  used  during  initial or
subsequent monitoring phases. Methods are classified according to source type and
area.  Guidance on meteorological monitoring methods is also provided in this
section.
                                   12-85

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12.8.1         Meteorological Monitoring

     Meteorological  monitoring generally should  employ  a 10-meter  tower
equipped with wind direction, wind speed, temperature and atmospheric stability
instrumentation. Wind direction and wind speed monitors should exhibit a starting
threshold of less than 0.5 meters per second (m/s).  Wind speed monitors should be
accurate above the starting threshold to within 0.25 m/s at speeds less than or equal
to 5 m/s. At higher speeds the error should not exceed 5 percent of the wind  speed.
Wind direction monitor errors should not exceed 5 degrees.  Errors in temperature
should not exceed 0.5°Cduring normal operating conditions.

     The meteorological station  should  be  installed  at  a  location which  is
representative of overall site terrain and wind conditions. Multiple meteorological
station locations may be required at coastal and complex terrain sites.

     Additional  guidance on  equipment  performance  specifications,  station
location, sensor exposure criteria, and field methods for meteorological monitoring
are provided in the following references:

     U.S. EPA.  February 1983.  Quality Assurance  Handbook for  Air Pollution
     Measurement Systems: Volume IV. Meteorological Measurement.  EPA-600-4-
     82-060.  Office of Research and  Development.  Research Triangle Park,  NC
     27711.

     U.S. EPA. November 1980.  Ambient Monitoring Guidelines for Prevention of
     Significant Deterioration  (PSD). EPA-450/4-80-012.  NTIS PB 81-153231.  Office
     of Air Quality Planning and Standards.  Research Triangle Park, NC 27711.

     U.S. EPA. July 1986.  Guidelines on Air Quality Models (Revised). EP-450/2-78-
     027R.   NTIS  PB  86-245248.  Office  of Air Quality Planning  and Standards.
     Research Triangle Park, NC 27711.

12.8.2         Air Monitoring

     Selection of methods for  monitoring air contaminants  should  consider a
number of factors, including the compounds to be detected, the purpose  of the
                                   12-86

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method (e.g., screening or quantification), the detection limits, and sampling rates
and duration required for the investigation.

     Organic and  inorganic constituents require different  analytical methods.
Within these two groups, different methods may also be required depending on the
constituent and its physical/chemical properties.  Another condition that affects the
choice of monitoring technique is whetherthe compound is primarily in the gaseous
phase or is found adsorbed to solid particles or aerosols.

     Screening  for  the presence of  air constituents  involves  techniques  and
equipment that are rapid, portable, and can provide "real-time" monitoring data.
Air contamination screening will generally be used to confirm the presence of a
release, or to establish the extent of contamination during the screening phase of
the investigation.  Quantification of  individual components  is not as  important
during screening as  during  initial  and additional  air monitoring,  however the
technique must have sufficient specificity to differentiate hazardous constituents of
concern from potential interferences, even when the  latter are present in higher
concentrations. Detection limits for screening  devices are often higher than for
quantitative methods.

     Laboratory analytical techniques  must  provide positive identification of the
components,  and accurate and precise  measurement  of  concentrations.  This
generally means that  preconcentration and/or storage of air  samples will  be
required.  Therefore, methods chosen for quantification usually  involve a longer
analytical time-period,  more sophisticated equipment, and  more rigorous  quality
assurance procedures.

     The  following  list  of references  provides  guidance  on  air monitoring
methodologies:

     U.S.  EPA.   June 1983.  Technical Assistance  Document for  Sampling and
     Analysis of Toxic Organic Compounds in Ambient Air. EPA-600/4-83-027.  NTIS
     PB 83-239020.  Office of Research and Development. Research Triangle Park,
     NC 27711.
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U.S. EPA. April 1984. Compendium of Methods for the Determination of Toxic
Organic Compounds in  Ambient Air.  EPA-600/4-84-041.  Office of Research
and Development. Research Triangle Park, NC 27711.

NIOSH.  February 1984.  NIOSH Manual of Analytical Methods.  NTIS PB 85-
179018. National Institute for Occupational Safety and Health. Cincinnati, OH.

U.S. EPA.  September 1983.  Characterizaiton  of Hazardous Waste Sites - A
Methods Manual: Volume II. Available Sampling Methods. EPA-60G74-83-040.
NTIS PB 84-126929. Office of Solid Waste. Washington, D.C. 20460.

U.S. EPA.  September 1983.  Characterization  of Hazardous Waste Sites - A
Methods Manual: Volume III, Available Laboratory Analytical Methods. EPA-
600/4-83-040.  NTIS PB 84-126929.  Office of Solid Waste.  Washington, D.C.
20460.

U.S. EPA.  1986. Test Methods for Evaluating Solid Waste. 3rd Edition. EPA
SW-846.  GPO No 955-001-00000-1. Office of Solid Waste.  Washington, D.C.
20460.

ASTM.   1982.   Toxic  Materials  in  the Atmosphere.   ASTM,  STP 786.
Philadelphia, PA.

ASTM.  1980.  Sampling and Analysis of Toxic Orqanics in the Atmosphere.
ASTM, STP 721. Philadelphia, PA.

ASTM.  1974.  Instrumentation for Monitoring Air Quality. ASTM, STP 555.
Philadelphia, PA.

APHA. 1977. Methods of Air Sampling and Analysis. American Public Health
Association.  Cincinnati, OH.

ACGIH.   1983.  Air Sampling  Instruments for  Evaluation of Atmospheric
Contaminants. American Conference of Governmental Industrial Hygienists.
Washington, D.C.
                              12-i

-------
     U.S. EPA.  December 1988 Draft.  Procedures for Conducting Air Pathway
     Analyses for Superfund  Applications.  Office  of Air Quality  Planning  and
     Standards. Research Triangle Park, NC 27711.

12.8.2.1       Screening Methods

     Screening  techniques for vapor-phase  constituents fall  into  two  main
categories.   (1) organic and  non-organic compound-specific indicators, and (2)
general organic detectors.  Table 12-11 presents a summary  of  commercially
available screening methods for these compounds.

     Indicator tubes and other colorimetric methods-Indicator tubes, also known
as gas detector or Draeger tubes, are small glass tubes filled with a reagent-coated
material which changes color when exposed to a particular chemical.  Air is pulled
through the tube with a low-volume pump. Tubes are available for 40 organic
gases, and for 8 hour or 15 minute exposure periods.  Indicator tubes were designed
for use in occupational settings, where high levels of relatively pure gases are likely
to occur. Therefore, they have only limited usefulness for ambient air sampling,
where  part-per-billion levels are often  of concern.  However,  because they  are
covenient to use and available for a wide range of compounds, detector tubes may
be useful in some screening/sampling situations.

     Other colorimetric methods,  such  as  continuous  flow and  tape  monitor
techniques,  were developed to provide real-time monitoring capability with
indicator methods.  The disadvantages of these  systems are similar to those of
indicator tubes.

     Instrument detection screening methods-More commonly used for  volatile
organic surveys, portable instrument detection methods include flame ionization
detectors (FID), photoionization detectors (PID), electron capture detectors (BCD),
and  infrared detectors (ID).   Also  in use are detectors that respond to  specific
chemical classes  such  as  sulfur-  and  nitrogen-containing  organics.    These
instruments are used to indicate levels of total organic vapors and for identification
of "  hot zones" downwind of the release source(s).  They can be used as real-time
non-specific  monitors  or,  by adding  a   gas  chromatograph,   can  provide
concentration estimates and tentative identification of pollutants.
                                   12-89

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     Of the available detectors, those that are the most applicable to an RFI are the
FID and PID.  Table  12-12 summarizes four instruments (two FID and  two PID
versions) which are adequate for the purposes of the screening phase.

     Flame lonization Detectors-The Century OVA 100 series and AID Model 550
utilize a FID to  determine the  presence of vapor phase organics.  The  detector
responds to the total of all organics present in the air at any given moment. Flame
ionization detectors  will  respond  to  most organics, but are most  sensitive to
hydrocarbons (i.e., those chemicals which  contain  only carbon  and hydrogen
molecules such as benzene and propane).  FIDs are somewhat less sensitive to
compounds containing chlorine, nitrogen,  oxygen, and sulfur molecules.  The
response is calibrated against a reference gas, usually methane. FID response is
often termed "total hydrocarbons"; however, this is misleading because particulate
hydrocarbons are not detected.  FID detection without gas chromatography is not
useful for quantification of individual compounds, but provides a useful tool  for
general assessment purposes.  Detection limits using a FID detector alone are about
1 ppm.  Addition of a gas chromatograph (GC) lowers the detection  limit to ppb
levels, but increases the analysis time significantly.

     Photoionization Detectors-Portable photoionization detectors  such  as the
HNU Model PI-101 and  the  Photovac 10A10 operate  by applying  UV  ionizing
radiation to the contaminant molecules.  Some selectivity over the types of organic
compounds detected  can be obtained  by varying energy of the ionizing beam.  In
the screening mode this feature can be used to distinguish between aliphatic and
aromatic hydrocarbons and to  exclude background gases from the  instrument's
response.  The HNU and Photovac can be used either in the survey mode (PID only),
or with GC. Sensitivity with PID alone is about 1 ppm, but can go down to  as low as
0.1 ppb when a GC is used.

     PI and Fl detectors used in the GC mode can be used for semiquantitative
analysis of compounds  in ambient air.  However,  in areas where numerous
contaminants are present, identification of peaks  in a complex matrix  may be
tentative at best.
                                  12-91

-------
                                 TABLE 12-12

       SUMMARY OF SELECTED ONSITE ORGANIC SCREENING METHODOLOGIES
Instrument
or detector
Measurable
parameters
Low range
of detection
Comments
Century Series 100 or
AID Model 550 (survey
mode)
Volatile organic
species
Low ppm     Uses Flame lonization
             Detector (FID)
HNU Model PI-101
Volatile organic
species
Low ppm     Photo-ionization (PI)
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             molecular weight
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             (i.e., benzene, toluene)
Century Systems        Volatile organic
OVA-128(GCmode)     species
                     Low ppm
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Photo Vac 10A10
Volatile organic
species
Low ppm     Uses PI detector.
             Especially sensitive to
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             identification if
             interferences are not
             present
                                    12-92

-------
     Another method which  can  be used  as a survey technique is mobile  mass
spectrometry. Ambient air is drawn through a probe directly into the instrument,
which is usually mounted in a  van. Particularly in the MS/MS configuration this is a
powerful technique which can provide positive identification and semiquantitative
measurement of an extrememly wide range of organic and inorganic gaseous
contaminants.

12.8.2.2       Quantitative Methods

     Laboratory analysis of hazardous constituents in air includes the following
standard steps:

     •   Preconcentration of organics (as necessary to achieve detection  limit
         goals);

     •   Transfer  to  a gas chromatograph  or HPLC (High  Pressure  Liquid
         Chromatography); and

     •   Quantification and/or identification with a detector.

     Broad-spectrum methods applicable to most  common air contaminants are
discussed below.

12.8.2.2.1 Monitoring OrganicCompoundsin Air

     Due to the large number of organic compounds that may be present in air, and
their  wide range  in chemical and  physical  properties,  no single  monitoring
technique is applicable to all organic air contaminants. Numerous techniques have
been developed, and continue to be developed, to monitor for specific compound
classes, individual chemicals, or to address a wide range of hazardous contaminants.
This last approach may be the  most efficient approach to monitoring at units where
a wide range of chemicals are likely to be present. Therefore, methods that apply to
a broad range of compounds are recommended. In cases where specific compounds
of concern are not adequately measured by broad-spectrum methods, compound-
specific techniques are described or referenced.
                                  12-93

-------
12.8.2.2.1.1    Vapor-Phase Organics

     The majority of hazardous constituents of concern can be classified as gaseous
or (vapor-phase)  organics.   These constituents include  most petroleum-related
hydrocarbons, organic solvents, and many pesticides, and other semivolatile organic
compounds.  Methods to monitor these  compounds generally  include on-site
analysis (making  use of  onsite concentration techniques, where necessary),  or
require storage in a tightly sealed non-reactive container.

     Techniques for volatile and semivolatile organics measurement include:

     •    Adsorption of the sample on a solid sorbent with subsequent desorption
          (thermal or chemical), followed by gas chromatographic analysis using a
          variety of detectors.

     •    Collection of whole air (grab) samples in an evacuated flask or in Tedlar
          or Teflon bags, with direct injection of the sample into a GC using high
          sensitivity and/or constituent-specific detectors.  This analysis may or may
          not be preceded by a preconcentration step.

     •    Cryogenic trapping of samples in the field with subsequent instrumental
          analysis.

     •    Bubbling ambient air through a liquid-filled  impinger,  containing  a
          chemical that will absorb or react with specific compounds to form more
          stable products for GC analysis.

     •    Direct introduction of the air into a MS/MS or other detector.

     Tables 12-13 (A and  B), 12-14, and 12-15 summarize sampling and analytical
techniques that are applicable to a wide range of vapor phase organics, have been
widely tested and validated in the literature, and make use of equipment that is
readily available. A discussion of general types of techniques is given below.
                                   12-94

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-------
TABLE 12-13B. LIST OF COMPOUND CLASSES REFERENCED IN TABLE 12-13A
    Category
                Types of Compound
                 Volatile, nonpolar organics (e.g., aromatic
                 hydrocarbons, chlorinated hydrocarbons) having boiling
                 points in the range of 80 to 200°C.
                 Highly volatile, nonpolar organics (e.g., vinyl chloride,
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                 points in the range of -15 to  +120°C
       III
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pesticides and PCBs).
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                               12-97

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-------
                      TABLE 12-15
        COMPOUNDS MONITORED USING EMSL-RTP
              TENAX SAMPLING PROTOCOLS
2-Chloropropane
1,1-Dichloroethene
Bromoethane
1-Chloropropane
Bromochloromethane
Chloroform
Tetrahydrofuran
1,2-Dichloroethane
1,1,1-Trichloroethane
Benzene
Carbon tetrachloride
Dibromomethane
1,2-Dichloropropane
Trichloroethene
1,1,2-Trichloroethane
2,3-Dichlorobutane
Bromotrichloromethane
Toluene
1,3-Dichloropropane
1,2-Dibromomethane
Tetrachloroethene
Chlorobenzene
1,2-Dibromopropane
Nitrobenzene
Acetophenone
Benzonitrite
Isopropylbenzene
p-lsopropyltoluene
1-Bromo-3-chloropropane
Ethylbenzene
Bromoform
Ethenylbenzene
o-Xylene
1,1,2,2-Tetrachloroethane
Bromobenzene
Benzaldehyde
Pentachloroethane
4-Chlorostyrene
3-Chloro-1-propene
1,4-Dichlorobutane
1,2,3-Trichloropropane
1,1-Dichloroethane
2-Chlorobutane
2-Chloroethyl vinyl ether
1,1,1,2-Tetrachloroethane
p-Dioxane
Epichlorobutane
1,3-Dichlorobutane
p-Dichlorobenzene
cis-1,4-Dichloro-2-butene
n-Butyl benzene
3,4-Dichloro-1-butene
1,3,5-Trimethyl benzene
                        12-102

-------
     Sprbent techniques--A very common technique used to sample vapor-phase
organics involves sorption onto a solid medium.  Methods of this type usually
employ a low- or high-volume pump to pull air through a glass tube containing the
sorbent  material.   Organic compounds are  trapped  (removed from the air) by
chemical attraction to the surface of the adsorbent material. After a predetermined
volume of air has been pulled through the trap, the tube is capped and returned to
the laboratory for analysis. Adsorbed organics are then  thermally  or chemically
desorbed from the trap prior to GC or GC/MS analysis.

     Thermal desorption is accomplished by rapidly heating the sorbent tube while
a stream of inert gas flushes desorbed organics directly onto  the GC column.
Generally a secondary trap (either another sorbent or a cryogenically cooled loop) is
used to hold the organics until injection into the GC column, but this step precludes
multiple analyses of the sample.

     Chemical  desorption  involves  flushing  the sorbent tube with an  organic
solvent, and  analysis of the desorbed organics by GC or GC/MS. Since only a portion
of the solvent is injected into  the GC, sensitivity  is lower than  with thermal
adsorption.   However, reanalysis of samples  is  possible.   The most  common
application of  chemical desorption is for analysis of workplace air samples, where
relatively high concentrations of organics are expected.

     The primary advantages of sorbent techniques are their ease of use and ability
to sample  large volumes of air.  Sorbent cartridges are commercially available for
many applications,  and can easily be adapted to portable monitoring pumps or
personal samplers.  A wide variety of sorbent materials are available, and sorbent
traps can be used singly or in series for maximum retention of airborne pollutants.
Sorbent methods are especially  applicable to  integrated  or long-term sampling,
because large  volumes of air  can be passed  through the sampling tube  before
breakthrough occurs.

     In choosing a sorbent method, the advantages and limitations of specific
methods should be considered along with general limitations of  sorbents.  Some
important considerations are discussed below.
                                  12-103

-------
•    Sorbents can be easily contaminated during manufacturing, shipping or
     storage.  Extensive preparation  (cleaning)  procedures are  generally
     needed to insure that the sorbent is free from  interfering compounds
     prior to sampling.   Tenax,  for example, is often  contaminated with
     benzene  and  toluene from  the  manufacturing   process,  requiring
     extensive solvent extraction  and thermal conditioning before it is used.
     Once   prepared,   sampling   cartridges  must   be  protected  from
     contamination before and after sampling.

•    No single adsorbent exists that will retain all vapor phase organics. The
     efficiency of retention of a compound on  a sorbent depends on  the
     chemical properties of both compound and sorbent.  Generally, a sorbent
     that works  well for nonpolar organics such  as benzene will perform
     poorly  with  polar organics  such as methanol, and  vice versa.   Highly
     volatile compounds such as vinyl chloride will not be retained on weakly
     adsorbing materials such as Tenax, while less volatile compounds will be
     irreversibly retained on strong  adsorbents such as charcoal. The  optimal
     approach involves  use of a sorbent that will retain a  wide range of
     compounds  with  good  efficiency, supplemented   by  techniques
     specifically directed towards "problem" compounds.

•    Tenax-GC is a synthetic  polymeric resin which  is highly effective  for
     volatile nonpolar organics such as aliphatic and aromatic hydrocarbons,
     and chlorinated organic solvents. Table 12-15  lists compounds that have
                                                     *
     been successfully monitored  using a Tenax sorption protocol. Tenax  has
     the important advantage that it does not retain water. Large amounts of
     water vapor condensing on  a sorbent reduces collection efficiency and
     interferes with  GC and  GC/MS analysis.  Another  advantage of this
     material is the ease of thermal or chemical desorption.

     The major limitation  of Tenax is that certain highly volatile or polar
     compounds  are poorly  retained  (e.g.,  vinyl  chloride,  methanol).
     Formation  of artifacts  (i.e.,   degradation  products  from  the  air
     contaminant sample collected due to hydrolysis, oxidation, photolysis or
     other processes) on Tenax has  also been noted, especially the oxidation
                              12-104

-------
of amines to form nitrosamines, yielding false  positive results for the
latter compounds.

Carbon sorbents include activated carbon, carbon molecular sieves, and
carbonaceous polymeric resins. The major advantage of these materials
is their strong affinity for volatile organics,  making them useful for
highly volatile compounds such as  vinyl chloride. The strength of their
sorptive properties is also the major disadvantage of carbon  sorbents
because some organic compounds may become irreversibly adsorbed on
the carbon. Thermal desorption of compounds with boiling points above
approximately 80°C is not feasible due to the high temperature (400°C)
required. Carbon adsorbents will retain some water, and therefore may
not be useful in high humidity conditions.

In addition to the Tenax and carbon tube sampling methods shown
above, passive sorption devices for ambient  monitoring can  be  used.
These passive samplers consist of  a portion of Tenax or carbon  held
within a stainless steel mesh holder. Organics diffuse into the sampler
and  are  retained on the sorbent material.   The sampling device is
designed  to fit  within  a  specially constructed  oven  for  thermal
desorption.   Results from these  passive  samplers were reported to
compare favorably with pump-based sorbent techniques. Because of the
difficulty of determining the volume of air sampled via passive sampling,
these devices would appear to  be mainly  applicable for screening
purposes.

Polyurethane foam (PUF)  has been used extensively and effectively for
collection of semivolatile organics  from  ambient air.   Semivolatiles
include PCBs and pesticides.  Such compounds  are often of concern even
at verly low concentrations.  A significant advantage of  PUF is its ability
to perform at high flow rates, typically in excess of 500 liters per minute
(l/m). This minimizes sampling times.

PUF  has been shown to be  effective for collection of a wide  range of
semivolatile  compounds.  Tables 12-16 and 12-17 list compounds that
have been successfully quantified in ambient air with PUF.  Compounds

                        12-105

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          that have shown poor retention or storage behavior with PDF include
          hexachlorocyclohexane, dimethyl  and diethylphthalates,  mono-  and
          dichlorophenols, and trichloro-  and  tetrachlorobenzenes.    These
          compounds have higher vapor pressures,  and may  be collected  more
          effectively with Tenax or with resin sorbents such as XAD-2.

          PDF is easy to handle, pre-treat, and extract.  Blanks with very low
          contaminant concentrations can be obtained, as long as precautions are
          taken  against contamination after pretreatment.  Samples have been
          shown to remain stable on PUF during holding times of up to 30 days.
          PUF concentration methods have shown excellent collection efficiency
          and recovery of sorbed compounds from the material.

          Most PUF methods specify the use of a filter ahead of the PUF cartridge,
          to retain  particulates.  The filter prevents plugging of the PUF which
          would reduce air flow through the sorbent. Some  methods reo -nmend
          extracting the filter separately to obtain a value for particulate organics.
          However, because most semivolatile compounds have sufficient vapor
          pressure  to  volatilize from the  filter during the  collection  period,
          particulate measurements may not be representative of true particulate
          concentrations.    Therefore,  results from   the  PUF  analyses  may
          overestimate gaseous concentrations of semi-volatile compounds due to
          volatilization of semi-volatiles originally collected  on the sampler  inlet
          filter and subsequently collected by the PUF cartridge.

     •    Cryogenic methods for capturing and collecting volatile organics involve
          pulling air through a stainless steel or nickle  U-tube  immersed in liquid
          oxygen or liquid argon. After sampling, the tube is sealed, stored in a
          coolant,  and  returned to  the laboratory for anlaysis.   The trap  is
          connected to a GC, rapidly heated, and flushed into a GC or GCMS for
          analysis.

     The major advantage of cryogenic concentration is that all vapor phase
organics, except the most volatile, are concentrated. This is a  distinct advantage
over sorbent  concentration,  which is especially selective for particular  chemical
                                  12-108

-------
classes.  Contamination problems are minimal with cryogenic methods because a
collection media is not required.

     Several disadvantages limit the current usefulness of cryogenic  methods,
including:

     •   Samplers rapidly become plugged with ice in high humidity conditions.
         This limits the volume of air that can be sampled.

     •   The entire sample is analyzed at once, enhancing sensitivity but making
         multiple analyses of a sample impossible.

     •   The necessity of handling and transporting cryogenic liquids makes this
         method cumbersome for many sampling applications.

     •   There is a possibility of chemical reactions between compounds in the
         cryogenic trap.

     Whole air sampling-Air may be collected without preconcentration for later
use in direct GC analysis or for other treatment. Samples may be collected in glass or
stainless steel containers, or in inert flexible containers such  as Tedler bags. Rigid
containers are  generally  used  for  collection  of  grab samples, while flexible
containers or rigid containers may be used to obtain integrated samples. Using a
flexible container to collect whole air samples requires the use of a sampling pump
with flow rate controls.  Sampling with rigid containers is performed  either by
evacuating the container and allowing ambient air to enter, or by having both inlet
and  outlet valves remain  open while  pumping air through the container until
equilibrium is achieved.

     Whole air sampling  is generally simple and efficient.  Multiple analyses are
possible on samples, allowing for good quality control. This method also has the
ability to be used for widely differing analyses on a single sample.  The method has
been widely used, and a substantial data base has been developed.

     Problems may occur using this method due to decomposition of compounds
during storage and loss of some organics  by adsorption to the  container walls.
                                  12-109

-------
Sample stability is generally much greater in stainless steel containers than in glass
or plastic. Whole-air sampling is limited to relatively small volumes of air (generally
up to 20  liters due to the  impracticality of  handling  larger sample collection
containers), and has higher detection limits than some sorbent techniques.

     Impinqer collection-lmpinqer collection  involves  passing  the air stream
through an organic solvent. Organics in the air are dissolved in the solvent, which
can then be analyzed by GC/MS. Large volumes of air sampled  cause the collection
solvent to evaporate. In addition, collection efficiency is dependent on flow rate of
the gas, and on the gas-liquid partition  coefficients of the individual compounds.
However, there are certain specialized applications of impinger sampling that have
been found to be preferable to alternate collection techniques (e.g., sampling for
aldehydes and ketones).

     Certain  compounds  of interest  are  highly  unstable  or  reactive,  and  will
decompose during  collection  or  storage.   To  concentrate  and analyze these
compounds, they must be chemically altered (derivatized) to  more stable forms.
Another common reason for derivatization is to improve the chromatographic
behavior of  certain  classes  of compounds  (e.g., phenols).   Addition  of the
derivatization reagent to  impinger solvent is a convenient way to accomplish the
necessary reaction.

     A widely used method for analysis  of  aldehydes  and  ketones is  a DNPH
(dinitrophenylhydrazine)  impinger technique.   Easily oxidized  aldehydes  and
ketones react with DNPH to form more stable hydrazone derivatives, which are
analyzed by high performance  liquid chromatography (HPLC) with a UV detector.
This method is applicable to formaldehyde as well as less volatile aldehydes and
ketones.

     Direct analvsis--A method not requiring preconcentration  or separation of air
components is highly desirable, because it avoids component  degradation or loss
during storage.  Air is drawn through  an  inert tube or probe directly  into the
instrument detector. Several portable instruments exist that can provide direct air
analysis, including infrared  spectrophotometers, mobile MS instruments,  and
portable FID detectors.  Some of these instruments  have been discussed in the
section on screening methods.
                                  12-110

-------
     Mobile mass spectrometry has been used to compare upwind and downwind
concentrations of  organic pollutants at hazardous waste management facilities.
The advantage of the multiple mass spectrometer configuration  (MS/MS or triple
MS) over a single  MS system is that multiple systems can identify compounds in
complex  mixtures  without  pre-separation  by  gas chromatography.    Major
limitations of MS/MS methods are low sensitivity and high instrument cost.

     In summary,  of the methods described in this subsection, the majority of
vapor-phase organics can be monitored by use of the following sampling methods:

     •   Concentration on Tenax or carbon adsorbents, followed by chemical or
         thermal desorption onto GC or GGMS.

     •   Sorption on polyurethane foam (PDF) cartridges, followed by solvent
         extraction.

     •   Cryogenic trapping in the field.

     •   Whole-airsampling.

12.8.2.2.1.2    Paniculate Organics

     Certain hazardous organic compounds of concern in ambient air are primarily
associated with airborne particles, rather than in the vapor phase.  Such compounds
include  dioxins, organochlorine  pesticides,  and   polyaromatic  hydrocarbons.
Therefore, to measure  these compounds accurately, it is  necessary to monitor
participate emissions from units of concern.

     Measurement of particulate organics is complicated because even relatively
nonvolatile organics exhibit some vapor pressure, and will  volatilize to a certain
extent during sampling.  The partitioning of a compound  between solid  and
gaseous phases is highly dependent on the sampling conditions (e.g., sampling flow
rate, temperature).  Particulate sampling methods generally include a gas phase
collection device after the particulate collector to trap those organics that become
desorbed during sampling.
                                  12-111

-------
     The most common methods used for collection of particles from ambient air
are:

     •    Filtration

              Cellulose Fiber
              Glass or Quartz Fiber
              Teflon Coated Glass Fiber
              Membranes

     •    Centrifugal Collection (e.g., cyclones)

     •    Impaction

     •    Electrostatic Preciptation

     The standard sampling method for particulates is filtration.  Teflon-coated
glass  membranec generally give the  best retention without  problems with
separating the particulates sampled  from the filter.  Problems, however, may be
caused by desorption  of organics from  the filter, by chemical transformation of
organics collected on the filter, and with chemical transformation of organics due
to reaction with  atmospheric gases such as oxides of nitrogen and ozone. These
problems are magnified by the large volumes of air that must be sampled to obtain
sufficient particulate material to meet  analytical requirements.  For example, to
obtain 50 milligrams of particulates from a typical air sample, 1000 cubic meters of
air must be sampled, involving about 20 hours of sampling time with a high-volume
sampling pump.

     Despite the drawbacks mentioned above, filtration is currently the simplest
and most thoroughly tested method  of collecting particulates for organic analysis.
Other methods, such as electrostatic precipitation, make use of electrical charge or
mechanical  acceleration of the  particles.   The effect of these procedures on
compound stability is poorly understood.
                                  12-112

-------
12.8.2.2.2  Monitoring Inorganic Compounds in Ambient Air

12.8.2.2.2.1    Participate Metals

     Metals in ambient air can occur as participates or can be adsorbed on other
paniculate material.  Metals associated with particulate releases are effectively
collected by use of filter media allowing for the collection of adequate samples for
analysis of a number of particulate contaminants.

     Collection on filter media-Sampling methods  for particulate metals  are
generally based on capture  of the particulate on filter media.  For the most part,
glass fiber filters are used; however, organic and membrane filters such as cellulose
ester and Teflon can also be used. These membrane filters demonstrate greater
uniformity  of pore size and, in  many cases,  lower contamination levels of trace
metals than are found in glass fiber filters.  Analytical  procedures described in  the
following reference can be utilized to analyze particulate samples.

     U.S. EPA. 1986.  Test Methods for Evaluating Solid  Waste.  3rd Edition. EPA
     SW-846. GPO No. 955-001-00000-1.  Office of Solid  Waste. Washington, D.C.
     20460.

     Hi-Vol collection devices--The basic ambient air sampler is the high volume
sampler which can collect a 2000 cubic meter sample over a 24-hour period and
capture particulates on an 8 x 10 inch filter (glass fiber) as described in 40 CFR Part
50.  It  has a nominal cut  point of  100um for  the maximum diameter particle size
captured.  A recent modification involves  the addition of a cyclone ahead of the
filter to separate respirable  and  non-respirable particulate matter.  Health  criteria
for particulate air contaminants are based on respirable particulate matter.

     Personnel samplers-Another particulate  sampling method involves the use of
personnel  samplers according to  NIOSH  methods (NIOSH, 1984).  The  NIOSH
methods are intended to measure worker  exposure to  particulate metals  for
comparison to OSHA standards. A 500-liter air volume is sampled at approximately
2 liters per minute.  This method is most efficient when  less than 2 mg total
particuiate weight are captured. Capture  of  more than  2 mg may lead to  sample
                                  12-113

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losses during handling of the sample. The preferred filter medium is cellulose ester
(47 mm diameter) which will dissolve during the standard acid digestion.

     The NIOSH  method, however, is not recommended for the  RFI for several
reasons. The NIOSH analytical methods (and good QA/QC practices) require several
aliquots of the sample to be prepared for best analytical results. The 47 mm filter is
too small for aliquoting; therefore, use of the NIOSH  method would require the
simultaneous operation of several sampling systems.   More importantly, the 500
liter sample volume generally does not provide sufficient particulate matter for the
analytical methods to detect trace ambient levels of metals.  The  method is best
suited for industrial hygiene applications.

     Dichotomous Samplers-Dichotomous samplers (virtual impactors) have been
developed for particle sizing with various limit cutpoints for use in  EPA ambient
monitoring programs. These samplers collect two particulate fractions on separate
37 mm diameter filters from a total air volume  of about 20 cubic  meters.  The
standard sampling period is 24 hours. Teflon filters are  generally  recommended by
sampler manufacturers because they  exhibit negligible  particle penetration and
result in a low pressure drop during the sampling period. However, glass fiber and
cellulose filters are also acceptable.

     The need for multiple extractions would require multiple sampling trains.  If
the two filters are combined to form one aliquot and extracted together, they will
provide sufficient sensitivity for some but not all analytical procedures and defeat
the purpose of fractioning the sample.  The use of the dichotomous sampler  is,
therefore, limited.

12.8.2.2.2.2    Vapor Phase Metals

     Most metallic elements and  compounds have very low volatilites at ambient
temperatures.  Those that  are relatively  volatile, however, require a different
sampling method than used  for collection of particulate forms, although analytical
techniques may be similar.  For the purpose of ambient monitoring, vapor-phase
metals are defined as all elements or compounds that are not effectively captured
by standard filter sampling procedures. Available methods for the measurement of
vapor phase metals are presented in Tables 12-18 and 12-19.  These available
                                  12-114

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methods are generally developed for industrial hygiene applications by NIOSH.

     The methods for measuring vapor-phase metals presented in Tables 12-18 and
12-19 have undergone  limited  testing for precision and accuracy and have had
matrix interferences documented.  Therefore, they should be used in lieu of any
methods which have no supporting data.

     Several methods are suitable  for quantification of vapor-phase mercury.  If
elemental  mercury  is to be measured, the silver amalgamation technique with
thermal desorption  and flameless AA (atomic absorption) analysis is recommended.
This technique is presented in American Public Health Association (APHA) Method
317, which can achieve nanogram per cubic meter detection limits. If organic and/or
particulate mercury are also to be determined, NIOSH methods (NIOSH, 1984) are
recommended. These methods can  measure all three airborne mercury species, but
require a complex two stage thermal desorption apparatus.

12.8.2.2.2.3    Monitoring Acidsand Other Compounds in Air

     Monitoring for acids  and  other  inorganic/non-metal  compounds (e.g.,
hydrogen sulfide) in the ambient air will generally require application of industrial
hygiene technologies.  Applicable methods have been compiled in the following
references:

     NIOSH. February 1984.  NIOSH Manual of Analytical Methods. NTIS PB 85-
     179108. National Institute for Occupational Safety and Health. Cincinnati, OH.

     ASTM.   1981.  Toxic Materials  in  the Atmosphere.  ASTM, STP 786.
     Philadelphia, PA.

     APHA. 1977. Methods of Air Sampling and Analysis. American Public Health
     Association.

     ACGIH.  1983.  Air Sampling Instruments for Evaluation  of Atmospheric
     Contamination.  American  Conference of Governmental Industrial  Hygienists.
     Cincinnati, OH.
                                  12-120

-------
12.8.3    Stack/Vent Emission Sampling

     EPA methods for source-sampling  and  analysis  are  documented in the
following reference:

     Code of Federal  Regulations.  40 CFR Part  60, Appendix A:  Reference
     Methods. Office of the Federal Register, Washington, D.C.

     Additional guidance is available in the following references:

     U.S. EPA.  1978.  Stack Sampling Technical  Information, A Collection of
     Monographs and  Papers, Volumes Nil.  EPA-450/2-78-042 a, b, c. NTIS PB 80-
     161672,80-1616680,80-161698.  Office of Air Quality Planning and Standards
     Research Triangle Park, NC  27711.

     U.S. EPA. February 1985.  Modified Method 5 Train  and Source Assessment
     Sampling System  Operators Manual. EPA-600/8-85-003. NTIS PB 85-169878.
     Office of Research and Development. Research Triangle Park, NC 27711.

     U.S. EPA  March  1984.  Protocol for the Collection and Analysis of Volatile
     POHC's Using VOST. EPA-600/8-84-007.  NTIS PB 84-177799.  Office of Research
     and Development. Research Triangle Park, NC 27711.

     U.S. EPA.  February  1984.  Sampling and Analysis Methods  for Hazardous
     Waste Combustion. EPA-600/8-84-002.  NTIS  PB 84-155845. Washington, D.C.
     20460.

     U.S. EPA. November 1985.  Practical Guide - Trial Burns for Hazardous Waste
     Incinerators.   NTIS PB 86-190246.  Office  of Research and Development.
     Cincinnati, OH 45268.

     U.S. EPA. 1981.  Source Sampling and Analysis of Gaseous Pollutants.  EPA-
     APTI Course Manual 468.  Air Pollution Control Institute.  Research Triangle
     Park.NC 27711.
                                  12-121

-------
     U.S. EPA. 1979.  Source Sampling for Participate Pollutants. EPA-APTI Course
     Manual 450. NTIS PB 80-188840, 80-174360, 80-182439. Air Pollution Control
     Institute. Research Triangle Park, NC 27711.

     U.S. EPA.   1986.  Test Methods for Evaluating  Solid Waste.  3rd Edition.
     EPA/SW-846. GPO No. 955-001-00000-1.  Office of Solid Waste.  Washington,
     D.C. 20460.

12.8.3.1  Vapor-Phase and Particulate Associated Organics

     Generally, point source vapor-phase samples are obtained from the  process
vents and effluent streams either by a grab sample technique or by an integrated
sampling train.  Careful planning is necessary to insure that sampling and analytical
techniques provide accurate quantitative and qualitative data for measurement of
vapor-phase organics. Considerations such as need for real-time (continuous) versus
instantaneous or short-term data, compatibility with other compounds/parameters
to be measured, and the need for onsite versus offsite analysis may all be important
in the selection process.

     Monitoring for  complex  organic  compounds  generally  requires detailed
methods and  procedures for  the collection,  recovery,  identification,  and
quantification of these compounds. The selection  of appropriate sampling  and
analytical methods depends on a number of  important  considerations, including
source type and the compounds/parameters of interest.  Table 12-20 lists several
sampling methods for various applications  and compound classess (applicable to
combustion sources).  The first  three  methods listed  are fixed-volume, grab-
sampling methods. Grab sampling is generally the simplest technique to obtain
organic emission samples.

     Sample collection by the bag and canister sampling methods  can  be used to
collect time-integrated samples.  These methods also allow for a choice of sample
volumes due to a range of available bag sized (6, 12, and 20 liter capacities are
typical).  Bags of various materials are  available, including relatively inert  and
noncontaminating materials such as Teflon, Tedlar, and Mylar. All sample collection
bag  types may have  some sample loss due to adsorption of the contaminants
collected to container walls. The bag sample is collected by inserting the bag  into
                                  12-122

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an airtight, rigid container (lung) and evacuating the container.  The sample is
drawn into the bag because reduced pressure in the container provides adequate
suction to fill the bag.  This procedure is presented in detail in 40 CFR Part 60,
Appendix A (Method 3).

     Evacuated canisters are conventionally constructed  of  high grade polished
stainless steel.  There are many versions available ranging from units with torque
limiting needle valves, purge free assemblies, internal electropolished surfaces and
versions utilizing stainless  steel  beakers with custom designed tops and fittings.
Also,  different container  materials  may react differently  with  the sample.
Therefore, sample storage  time  or sample recovery studies to determine or verify
inertness of the sampling canister should be considered.

     Canisters  are generally used to collect samples by slowly opening  the sample
valve, allowing the vacuum to draw in the sample gas. In less than a minute, the
container should equilibrate with the ambient atmospheric pressure. At that time,
the sample valve is closed to retain the sample.  To collect composite samples over
longer intervals, small calibrated orifices can be inserted  before the inlet valve to
extend the time required  for equilibration of pressure once the sample valve is
opened.

     The sample collection  procedure for EPA Method 5 (U.S. EPA, 1981) is similar in
principle  to that for the evacuated canister. The train consists of a polished stainless
steel canister with a cold  condensate trap in series and prior to the canister to collect
a higher  boiling  point organic fraction. This two fraction apparatus provides for
separate  collection  of two concentration ranges of volatile  organic compounds
based on boiling point.

     The following four sampling methods utilize sample concentration techniques
using one or more sorbent  traps.  The advantages of these methods is an enhanced
limit of  detection  for  many  toxic and  hazardous organic  compounds.  These
techniques are preferred due to their lower detection limit. The Modified Method 5
(MM5) sampling train (U.S.  EPA, 1981) is used to sample gaseous effluents for vapor-
phase organic compounds that  exhibit vapor pressures of less than 2  mm Hg (at
20°C). This system  is a modification of the conventional EPA Method 5 paniculate
sampling train. The modified system consists of a probe,  a high efficiency glass or
                                   12-125

-------
quartz fiber filter, a sorbent module, impingers, and related control hardware. The
sample gas is passed through a single sorbent trap, containing XAD-2. The M1V15
train is limited due to the single sorbent trap design that does not provide a backup
for breakthrough.  This is especially important when large volumes of sample are
collected.

     To minimize the potential for breakthrough, the MM5 train can be modified
to provide a backup trap.  However, this dual trap  modification  increases the
pressure drop across the train, reducing the range of flow rates possible for sample
collection. To overcome this pressure drop and maintain the desired flow rate, the
high-volume MM5 train utilizes a much larger capacity pump.

     The Source Assessment Sampling System (SASS) train is another comprehensive
sampling train, consisting of a probe that connects to three cyclones and a filter in a
heated oven module, a gas treatment section, and a series of impingers to provide
large collection capacities for paniculate  matter, semivolatiles, and  other  lower
volatility organics.  The materials of construction are all stainless steel making the
system very heavy and cumbersome.  The stainless steel construction is also very
susceptible to corrosion.  This system can, however, be used to  collect and
concentrate  large sample volumes, providing for a much lower detection limit.
Because of the sorbents used (generally XAD-2), its use is limited to the same class of
lower volatility organics and metals as the MM5 train.

     The Volatile Organic Sampling Train  (VOST) has proven  to be a reliable and
accurate method for collection of the broad range of organic compounds.  By using
a dual sorbent and dual in-series trap design, the VOST train can supplement either
the  MM5 or SASS  methods allowing  for  collection of  more volatile species.
However,  VOST has several limitations, including a maximum sample flow rate of
1.0 liter/minute, and a total sample volume  of 20 liters per trap pair. Therefore,
frequent changes of the trap pairs are required for test periods that exceed 20
minutes.  The frequent change  of traps makes the samples more susceptible to
contamination.

     Any  of  the point source  monitoring  techniques described above can  be
adapted for use with the isolation flux chamber techniques described previously.
For point sources where paniculate emissions are of concern, the Modified Method
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5 or SASS train (originally designed to measure particle emissions from combustion
effluents) are also applicable and proven technologies.

     Analytical methodologies for the techniques discussed above will vary with the
technique used.  While certain techniques will offer advantages over others in the
measurement  of specific  contaminants, the  investigator  is advised to  utilize
standard methodologies whenever possible in performing the RFI.  For example, use
of the VOST and/or the MM5 train, and their associated analytical methodologies is
recommended for  point  source  monitoring of  the  applicable compounds.
Descriptions for  both  of these  methods are included in the 3rd  Edition of "Test
Methods for Evaluating Solid Waste" (EPA SW-846), 1986 (GPO No. 955-001-00000-
1).   Although these  methods are designed  for  the  evaluation  of  incinerator
efficiencies, they are essentially point-source monitoring methods which can be
adapted to most  point sources.

12.8.3.2   Metals

     Although the emission of metallic contaminants is primarily associated with
particulate emission from area sources caused by the transfer of material to and
from different locations, wind erosion, or general maintenance and traffic activities
at the unit, point source emission of particulate or vapor-phase  metals can exist.
Metallic constituents may exist in  the atmosphere as solid  particulate matter, as
dissolved or suspended constituents of liquid droplets (mists), and as vapors.

     Metals specified as hazardous constituents in 40 CFR Part 261, Appendix VIII
are generally  noted as the element  and  compounds "not otherwise  specified
(NOS)", as shown in Table 12-21, indicating that measurement of the total content
of that element in the sample is required.

     Vapor phase metals-Forthe purpose of point-source monitoring, vapor-phase
metals will  be  defined as all  elements or compounds thereof, that are not
quantitatively  captured  by standard filter sampling procedures.  These include
volatile forms of  metals such as elemental and alkyl mercury,  arsine, antimony, alkyl
lead compounds, and nickel carybonyl.
                                   12-127

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               Table 12-21.
  RCRA APPENDIX VIII HAZARDOUS METALS AND
            METAL COMPOUNDS
      Antimony and compounds
      Arsenic and compounds NOSb
      Barium and compounds NOSb
      Beryllium and compounds NOS
      Cadmium and compounds NOS
      Chromium and compounds NOS
      Lead and compounds NOS
      Mercury and compounds NOSb
      Nickel and compounds NOSb
      Selenium and compounds NOSb
      Silver and compounds NOSb
      Thallium and compounds NOSb
a NOS = not otherwise specified.
b Additional specific compound(s) listed for this
 element.
                 12-128

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     The sampling of point sources for vapor phase metals has not been a common
or frequent  activity for the  investigation  of air releases from solid  waste
management units.  If a point source of vapor-phase  metals  is identified, the
sampling approach should identify the  best available  monitoring  techniques,
considering that many  have been developed which are specific to single species
rather  than multiple species  of many different metal  elements.   The primary
references  for  identifying  available techniques  include National Institute of
Occupational Safety and Health (NIOSH, 1984) methods, EPA methods such as those
presented in  SW-846 and  in the Federal  Register under the National Emissions
Standards for Hazardous Air Pollutants (NESHAPs), and  American Public Health
Association (APHA, 1977)  methods.   The basic  monitoring techniques  include
collection on sorbents and in impinger solutions. The particular sorbent or impinger
solution  utilized should be selected based on the specific  metal  species under
investigation.

     Particulate Metals-Point-source releases to air could also require investigation
of particulate metals. Source sampling particulate procedures such as the Modified
Method 5 or SASS  methods previously discussed are appropriate for this activity.
EPA Modified Method 5 is the recommended  approach.  Modification of this basic
technique  involving  the  collection of particulate material  on  a  filter with
subsequent analysis of the collected particulate materal on a filter for the metals of
concern, could include  higher or lower flow rates and the use of alternate filter
media. Such modificaitons may be proposed when standard techniques prove to be
inadequate. Several important particulate  metal sampling methods are available in
the NIOSH methods manuals (NIOSH, 1984); however, these methods were designed
for ambient or indoor applications and may require modification if used on point
sources.

12.9  Site Remediation

     Although the RFI Guidance is not intended to provide detailed guidance on
site remediation, it should be recognized that certain data collection activities that
may  be necessary for a Corrective Measures Study may be collected during the RFI.
EPA  has developed a practical guide for assessing and remediating contaminated
sites  that directs users toward technical support, potential data requirements and
                                   12-129

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technologies that may be applicable to EPA programs such as RCRA and CERCLA.
The reference forthis guide is provided below.

     U.S. EPA. 1988.  Practical Guide for Assessing and Remediating Contaminated
     Sites.  Office of Solid Waste and Emergency Response.  Washington,  D.C.
     20460.

     The guide is designed to address releases  to ground water as well as soil,
surface water and air. A short description of the guide is  provided in Section 1.2
(Overall  RCRA  Corrective  Action Process),  under the  discussion of Corrective
Measures Study.
                                  12-130

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12.10     Checklist

                             RFI CHECKLIST-AIR
Site Name/Location
Type of Unit
1.    Does waste characterization include the following information?   (Y/N)

          •    Physical form of the waste                         	
          •    Identification of waste components                	
          •    Concentrations of constituents of concern          	
          •    Chemical and physical properties of constituents
               of concern
2.    Does unit characterization include the following information?     (Y/N)

          •   Type of unit                                     	
          •   Types and efficiencies of control devices            	
          •   Operational schedules                            	
          •   Operating logs                                  	
          •   Dimensions of the unit                            	
          •   Quantities of waste managed                     	
          •   Locations and spatial distribution/
              variation of waste in the unit                      	
          •   Past odor complaints from neighbors               	
          •   Existing air monitoring data                       	
          •   Flow rates from vents
3.   Does environmental setting characterization include
          the following information?                                (Y/N)

          •    Definition of regional climate                      	
          •    Definiation of site-specific meteorological conditions	
          •    Definition of soil conditions
                                   12-131

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          •    Definition of site-specific terrain                    	
          •    Identification of potential release receptors         	

4.    Have the following data on the initial phase of the release
          characterization been collected?                           (Y/N)

          •    Conceptual model of release developed             	
          •    Concentrations of released constituent at unit,
               facility property boundary and, if appropriate,
               at nearby offsite receptors (based on
               screening assessment or available
               modeling/monitoring data)                        	
          •    Screening monitoring data (as warranted)           	
          •    Additional waste/unit data (as warranted)           	

5.    Have the following data on the subsequent phase(s) of the
          release characterization been collected?                    (Y/N)

          •    Identification of "reasonable worst case"
               conditions                                       	
          •    Meteorological conditions during monitoring       	
          •    Release source conditions during monitoring        	
          •    Basis for selection of monitoring constituents        	
          •    Concentrations of released constituents at unit,
               facility property boundary and, if appropriate,
               at nearby offsite receptors (based on
               monitoring or modeling and representative
               of reasonable "worst case" conditions)
                                   12-132

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12.11     References

ACGIH. 1983. Air Sampling Instruments for Evaluation of Atmospheric
    Contamination.  American Conference of Governmental Industrial Hygienists.
    Washington, D.C.

APHA.  1977. Methods of Air Sampling and Analysis. American Public Health
    Association. Cincinnati, OH.

ASTM.  1982. Toxic Materials in the Atmosphere. ASTM, STP 786. Philadelphia, PA.

ASTM.  1981. Toxic Materials in the Atmosphere. ASTM, STP 786. Philadelphia, PA.

ASTM.  1980. Sampling and Analysis of Toxic Orqanics in the Atmosphere. ASTM,
    STP 721. Philadelphia, PA.

ASTM.  1974. Instrumentation for Monitoring Air Quality. ASTM, STP 555.
    Philadelphia, PA.

National Climatic Data Center. Climates of the United States.  Asheville, NC 28801.

National Climatic Data Center. Local Climatoloqical Data - Annual Summaries with
    Comparative Data, published annually.  Asheville, NC 28801.

National Climatic Data Center. Weather Atlas of the United States. Asheville,
     NC 28801.

National Institute for Occupational Safety and Health (NIOSH). 1985. NIOSH
    Manual of Analytical Methods. NTISPB85-179018.

Turner, D.B.  1969. Workbook of Atmospheric Dispersion Estimates. Public Health
    Service. Cincinnati, OH.

U.S. EPA.  December 1988 Draft. Procedures for Conducting Air Pathway Analyses
    for Superfund Applications. Office of Air Quality Planning and Standards.
    Research Triangle Park, NC 27711.
                                  12-133

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U.S. EPA. March 1988 Draft. A Workbook of Screening Techniques for Assessing
     Impacts of Toxic Air Pollutants. Office of Air Quality Planning and Standards.
     Research Triangle Park, NC 27711.

U.S. EPA. June 1987. On-Site Meteorological Program Guidance for Regulatory
     Modeling Applications. EPA-450/4-87-013. Office of Air Quality Planning and
     Standards. Research Triangle Park, NC 27711.
                                                        >
U.S. EPA. December 1987. Hazardous Waste Treatment Storage and Disposal
     Facilities (TSDF) Air Emission Models.  EPA-450/3-87-026.  Office of Air Quality
     Planning and Standards.  Research Triangle Park, NC 27711.

U.S. EPA. 1986. Evaluation of Control Technologies for Hazardous Air Pollutants:
     Volume 1-Technical Report. EPA/60077-86/009a. NTIS PB 86-167020. Volume
     2 - Appendices. EPA/600/7-86/009b. NTIS PB 86-167038. Office of Research and
     Development. Research Triangle Park, NC 27711.

U.S. EPA. September 1986. Handbook-Control Technologies for Hazardous Air
     Pollutants. EPA/625/6-86/014. Office of Research and Development.  Research
     Triangle Park, NC  27711.

U.S. EPA. February 1986.  Measurement of Gaseous Emission Rates from Land
     Surfaces Using an Emission  Isolation Flux Chamber:   User's  Guide.  1986.
     EPA/600/8-86/008.  NTIS PB 86-223161.  Environmental  Monitoring Systems
     Laboratory. Las Vegas, NV 89114.

U.S. EPA. 1986. Test Methods for Evaluating Solid Waste. 3rd Edition. EPA SW-846.
     GPO No. 955-001-00000-1. Washington, D.C  20460.

U.S. EPA. July 1986. Guideline on Air Quality Models (Revised). EPA-450/2-78-027R.
     NTIS PB 86-245248.  Office of Air Quality Planning and Standards.  Research
     Triangle Park, NC  27711.

U.S. EPA. June 1986. Industrial  Source Complex (ISC) Model User's Guide-Second
                                  12-134

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     Edition.   EPA-450/4-86-005a  and b.  Office  of  Air Quality Planning and
     Standards. Research Triangle Park, NC 27711.

U.S. EPA. November 1985. Practical Guide - Trial Burns for Hazardous Waste
     Incinerators. NTIS PB 86-190246. Office of Air Quality Planning and Standards.
     Research Triangle Park, NC 27711.

U.S. EPA. February 1985. Rapid Assessment of Exposure to Paniculate Emissions
     from Surface  Contamination Sites.  EPA/600/8-85/002.  NTIS PB 85-192219.
     Office of Health and Environmental Assessment. Washington, D.C. 20460.

U.S. EPA. February 1985 (Fourth Edition and subsequent supplements). Modified
     Method  5 Train and Source Assessment Sampling System Operators Manual.
     EPA/600/8-85/003.  NTIS PB 85-169878.  Office of Research and Development.
     Research Triangle Park, NC 27711.

U.S. EPA. 1985. Compilation of Air Pollutant Emission Factors. EPAAP-42.  NTIS PB
     86-124906. Office of Air Quality Planning and Standards.  Research Triangle
     Park.NC 27711.

U.S. EPA. 1984. Evaluation and Selection of Models for Estimating Air Emissons
     from Hazardous Waste Treatment. Storage, and Disposal Facilities. EPA-450/3-
     84-020.  NTIS  PB  85-156115.  Office of Air Quality Planning  and Standards.
     Research Triangle Park, NC 27711.

U.S. EPA. September 1984.  Network Design and Site Exposure Criteria for Selected
     Noncriteria Air Pollutants. EPA-450/4-84-022.  Office of Air Quality Planning
     and Standards. Research Triangle Park, NC 27711.

U.S. EPA. June 1984. Evaluation of Air Emissions from Hazardous Waste
     Treatment. Storage and Disposal  Facilities.  EPA  600/2-85/057.   NTIS PB 85-
     203792. Office of Research and Development. Cincinnati, OH 45268.

U.S. EPA. April 1984. Compendium of Methods for the Determination of Toxic
     Organic  Compounds in Ambient Air.  EPA-600/4-84-041.  Office of Research
     and Development. Research Triangle Park, NC 27711.
                                  12-135

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U.S. EPA.  March 1984. Protocol for the Collection and Analysis of Volatile POHCs
     Using VQST.  EPA-600/8-84-007.  NTIS PB 84-170042. Office of Research  and
     Development. Research Triangle Park, NC 27711.

U.S. EPA.  February 1984. Sampling and Analysis Methods for Hazardous Waste
     Combustion.  EPA-600/8-84-002. NTIS PB 84-155845. Washington, D.C. 20460.

U.S. EPA.  September 1983. Characterization of Hazardous Waste Sites - A Methods
     Manual: Volume II. Available Sampling Methods.  EPA-600/4-83-040. NTIS PB
     83-014799. Off ice of Sol id Waste. Washington, D.C. 20460.

U.S. EPA.  July 1983. Guidance Manual for Hazardous Waste Incinerator Permits.
     NTIS PB 84-100577. Office of Solid Waste.  Washington, D.C.  20460.

U.S. EPA.  June 1983. Technical Assistance Document for Sampling and Analysis of
     Toxic Organic Compounds in Ambient Air.  EPA-600/4-83-027. NTIS PB 83-
     239020.  Office of Research  and  Development.  Research Triangle Park, NC
     27711.

U.S. EPA.  February 1983. Quality Assurance Handbook for Air Pollution
     Measurement Systems:  Volume IV. Meteorological Measurement.  February
     1983.  EPA-600-4-82-060.  Office of Research and Development.  Research
     Triangle Park, NC 27711.

U.S. EPA.  November 1980. Ambient Monitoring Guidelines for Prevention of
     Significant Deterioration (PSD).  EPA-450/4-80-012.  NTIS PB 81-153231.  Office
     of Air Quality Planning and Standards. Research Triangle Park, NC 27711.

U.S. EPA.  1978. Stack Sampling Technical Information. A  Collection of Monographs
     and  Papers. Volumes  Nil.  EPA-450/2-78-042a,b,c.  NTIS PB 80-161672, 80-
     161680,80-161698.

U.S. EPA.  October 1977. Guidelines for Air Quality Maintenance Planning and
                                  12-136

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     Analysis. Volume 10 (Revised): Procedures for Evaluating Air Quality Impact of
     New Stationary Sources. EPA-450/4-77-001. NTIS PB 274087/661. Office of Air
     Quality Planning and Standards. Research Triangle Park, NC 27711.

U.S. EPA. Code of Federal Regulations. 40CFRPart60: Appendix A: Reference
     Methods. Office of Federal Register. Washington, D.C.

U.S. EPA. November 1981. Source Sampling and Analysis of Gaseous Pollutants.
     EPA-APTI Course  Manual 468.  Air Pollution Control Institute.  Research
     Triangle Park, NC 27711.

U.S. EPA. 1979. Source Sampling for Particulate Pollutants.  EPA-APTI Course
     Manual 450. NTIS PB 80-182439, 80-174360.  Air Pollution Control Institute.
     Research Triangle Park, NC 27711.
                                  12-137

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                               SECTION 13

                             SURFACE WATER

13.1 Overview

     The objective of an invest.gation  of a  release to surface water  is to
characterize the nature, extent, and rate of migration of the release to this medium.
This section provides the following:

     •   An example strategy for characterizing releases to the surface water
         system (e.g., water column, bottom sediments, and biota), which includes
         characterization of the source and the environmental setting of the
         release, and conducting a monitoring program that will characterize the
         release;

     •   A discussion of waste and  unit source characteristics and operative
         release mechanisms;

     •   A strategy  for the design  and conduct of monitoring  programs
         considering specific requirements of different wastes,  release
         characteristics, and receiving water bodies;

     •   Formats for data organization and presentation;

     •   Appropriate field and other methods  that  may  be  used  in the
         investigation; and

     •   A checklist of information  that  may be  needed for  release
         characterization.

     The exact type and amount of information required for sufficient release
characterization will be facility and site-specific and should be determined through
interactions between the regulatory agency and the facility owner or operator
during the RFI process.  This guidance does not define the specific data needed in all
                                   13-1

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instances;  however, it identifies the information that is likely  to  be needed  to
perform release characterizations  and identifies  methods for obtaining this
information. The RFI Checklist, presented at the end of this section,  provides a tool
for planning and tracking information collection for release characterization. This
list is not a list of requirements for all releases to surface water. Some releases will
involve the collection of only a subset of the items listed, while others will involve
the collection of additional data.

     Case  Study Numbers 27, 28, 29, 30 and  31 in Volume IV (Case Study Examples)
illustrate various aspects of surface water investigations which are described below.

13.2  Approach for Characterizing Releases to Surface Water

13.2.1         General Approach

     A conceptual model of the release should  be formulated using all available
information  on the waste,  unit characteristics,  environmental setting, and any
existing monitoring data.  This model (not a computer  or  numerical simulation
model) should  provide a working hypothesis of the release  mechanism, transport
pathway/mechanism, and  exposure route  (if any).   The model  should  be
testable/verifiable  and flexible enough to be modified as new data become
available.  For surface water investigations, this model  should account for the
release mechanism (e.g., overtopping of an impoundment), the nature of the source
area (e.g.,  point or non-point), waste type and degradability, climatic factors (e.g.,
history of  floods), hydrologic factors (e.g., stream flow conditions), and fate and
transport factors (e.g., ability for a contaminant to accumulate in  stream bottom
sediments). The conceptual model should also address the potential  for the transfer
of contaminants in surface water  to  other environmental  media  (e.g., soil
contamination as a  result of flooding of a contaminated  creek  on  the  facility
property).

     An example strategy for characterization of  releases to surface  waters is
summarized in Table 13-1. These steps outline a phased approach, beginning with
evaluation of existing data  and proceeding to  design and  implementation of a
monitoring program, revised over time, as necessary, based on findings of the
previous phase.  Each of these steps is discussed briefly below.
                                   13-2

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                                TABLE 13-1

   EXAMPLE STRATEGY FOR CHARACTERIZING RELEASES TO SURFACE WATER*


                              INITIAL PHASE

1.    Collect and review existing information on:

         Waste
         Unit
         Environmental setting
         Contaminant releases, including inter-media transport

2.    Identify any additional information necessary to fully characterize release:

         Waste
         Unit
         Environmental setting
         Contaminant releases, including inter-media transport

3.    Develop monitoring procedures:

         Formulate conceptual model of release
         Determine monitoring program objectives
         Select monitoring constituents and indicator parameters
         Select monitoring locations
         Determine monitoring frequency
         Incorporate hydrologic monitoring as necessary
         Determine role of biomonitoring and  sediment monitoring

4.    Conduct initial monitoring:

         Collect samples under initial monitoring phase procedures and complete
         field analyses
         Analyze samples for selected parameters and constituents

5.    Collect, evaluate, and report results:

         Compare analytical and  other monitoring procedure results to  health
         and  environmental criteria and identify and respond  to emergency
         situations and identify  priority situations that may warrant interim
         corrective measures - Notify regulatory agency
         Summarize and present data in appropriate format
         Determine if monitoring program objectives were met
         Determine if monitoring locations, constituents and frequency were
         adequate to characterize release (nature, extent, and rate)
         Report results to regulatory agency
                                   13-3

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                          TABLE 13-1 (continued)

   EXAMPLE STRATEGY FOR CHARACTERIZING RELEASES TO SURFACE WATER*



                     SUBSEQUENT PHASES (If necessary)

1.    Identify additional information necessary to characterize release:

          Identify additional information needs
          Determine need to include  or expand hydrologic, and sediment and bio-
          monitoring
          Evaluate potential role of inter-media transport

2.    Expand initial monitoring as necessary:

          Relocate, decrease, or increase number of monitoring locations
          Add or delete constituents and parameters of concern
          Increase or decrease  monitoring frequency
          Delete, expand, or include hydrologic, sediment or bio-monitoring

3.    Conduct subsequent monitoring  phases:

          Collect samples under revised monitoring procedures and complete field
          analyses
          Analyze samples for selected parameters and constituents

4.    Collect, evaluate and report results/identify additional information necessary
     to characterize release:

          Compare analytical  and other  monitoring procedure results to health
          and  environmental  criteria and identify and respond  to emergency
          situations and identify  priority situations that may warrant interim
          corrective measures - Notify regulatory agency
          Determine if monitoring program objectives were met
          Determine if monitoring locations, constituents, and  frequency were
          adequate to characterize release (nature, extent, and rate)
          Identify additional information needs
          Determine need  to  include or expand hydrologic, sediment, or bio-
          monitoring
          Evaluate potential role of inter-media transport
          Report results to regulatory agency
     Surface water system is subject to inter-media transport. Monitoring program
     should incorporate the necessary procedures to characterize the relationship,
     if any, with ground water, sediment deposition, fugitive dust and  other
     potential release migration pathways.
                                   13-4

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     The first step in the general approach is the collection and review of available
 information on the contaminant source and the environmental  setting. Some
 information on the contaminant source will be available from several reports and
 other documents. The RCRA permit, compliance order, or RFA report will provide a
 summary of information regarding  actual or suspected releases from the various
 units. The facility owner or operator should be familiar with this information as a
 basis  for further characterization of the release(s) in the  RFI.   In addition, a
 thorough understanding of the environmental setting  is essential to an adequate
 determination of the nature and extent of releases to surface waters. Monitoring
 data should also be  reviewed focusing on the quality of the data. If the quality
 is determined to  36  acceptable, then the data  may  be  used in  the  design  of
 the monitoring program.  Guidance  on  obtaining and evaluating the necessary
 information on the contaminant source and the environmental setting is given in
 Section 13.3.

     During the initial investigation particular attention  should be given  to
 sampling run-off from contaminated areas, leachate seeps and other similar sources
 of surface water contamination, as these are the primary overland release pathways
 for surface water. Releases to surface water via ground-water discharge should be
 addressed as part of the ground-water investigation, which should be coordinated
 with surface water investigations, for greater efficiency.

     Based  on the collection and review of existing information, the design of the
 monitoring  program is the next major  step in the general approach.  The
 monitoring program should include clear objectives, monitoring  constituents and
 indicator parameters,  monitoring  locations,  frequency  of monitoring,  and
 provisions for hydrologic monitoring. In addition to conventional water quality and
 hydrologic monitoring,  sediment monitoring  and biomonitoring may also have a
 role in the surface water evaluation for a given RFI. Guidance on the design of the
 monitoring program is given in Section 13.4.

     Implementation of the monitoring program is the next major step in the
general strategy for characterizing releases to surface water.  The program may  be
implemented in a phased manner that allows for modifications to the program in
subsequent phases.  For example, initial  monitoring  results may indicate  that
                                   13-5

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downstream monitoring locations have been placed either too close to or too far
from the contaminant source to accurately define the complete extent of
downstream contamination.  In this case, the program should be modified to
relocate monitoring stations for subsequent monitoring  phases. Similarly, initial
monitoring may indicate that biomonitoring of aquatic organisms is needed in the
next phase.  Guidance on methods that can be used in the implementation of the
program is given in Section 13.6.

    Finally, the results of the characterization of releases to surface waters must be
evaluated and presented in conformance with the requirements of the  RFI. Section
13.5 provides guidance on  data presentation. Table  13-2 summarizes techniques
and data-presentation methods for the key characterization tasks.

    As monitoring data become available, both within and at the conclusion of
discrete investigation phases, they should be reported to the regulatory agency as
directed.  The regulatory agency will compare the monitoring data to applicable
health  and environmental criteria to determine the need for (1) interim corrective
measures;  and/or  (2) a Corrective Measures Study.  In addition, the regulatory
agency will evaluate the  monitoring  data with respect to adequacy  and
completeness to determine the need for any additional  monitoring efforts.  The
health  and environmental criteria and a general discussion of how the regulatory
agency will apply them are supplied in Section 8.  A flow diagram illustrating RFI
decision points is provided in Section 3 (See Figure 3-2).

    Notwithstanding the above process, the owner or operator has a continuing
responsibility to identify and respond to emergency situations and to define priority
situations that may warrant interim corrective measures.  For these situations, the
owner  or operator is directed to follow the RCRA Contingency Plan requirements
under 40 CFR Part 264, Subpart D and Part 265, Sub part D.
                                   13-6

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                                     TABLE 13-2
                RELEASE CHARACTERIZATION TASKS FOR SURFACE WATER
     Investigatory Tasks
Investigatory Techniques
   Data Presentation
   Formats/Outputs
1.  Waste/Unit
   Characterization

   -   Waste Composition and
      Analysis

   -   Unit or Facility
      Operations
      Release Mechanisms
See Section 13.3.1
Review waste handling and
disposal practices and
schedules

Review environmental
control strategies

See Section 13.3.1, Review
operational information
Data Tables
Schematic diagrams of flow
paths, narrative
Site-specific diagrams,
maps, narrative
2.  Environmental Setting
   Characterization

   -   Geographic Description
      Classification of Surface
      Water and Receptors

      Define Hydrologic
      Factors
Review topographic, soil
and geologic setting
information

See Section 13.3.3.1
See Section 13.3.3.1
Maps, Tables, Narrative
Maps, Cross Sections,
Narrative
Tables, Graphs, Map
3.  Release Characterization

   -   Delineate Areal Extent
      of Contamination
      Define Distribution
      Between Sediment,
      Biota and Water
      Column

      Determine Rate of
      Migration

      Describe Seasonal
      Effects
Sampling and Analysis
Sampling and Analysis
Flow Monitoring
Repetitive Monitoring
Tables of Results, Contour
Maps, Maps of Sampling
Locations

Graphs and Tables
Graphs and Tables
Graphs and Tables
                                        13-7

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13.2.2         Inter-media Transport

     Surface waters are subject to inter-media transport, both as a receptor of
contamination and as a  migration pathway.   For example, surface waters are
generally engaged in a continual dynamic relationship with ground water. Ground
water may discharge to a surface water body that may, in turn, recharge an aquifer.
Hence, contamination may be transported from ground water to surface water and
from surface water to ground water.  Release  of contaminants from a receiving
water body to soil can also occur through deposition  of  the contaminants in
floodplain sediments.  These sediments may  be exposed to wind  erosion  and
become distributed through fugitive dust. Sediments may be exposed to air during
periods of low flow of  water in  streams and lakes and  when sediments are
deposited by overland flow during rainfall-runoff events. Contaminants may also
enter the air from surface water through volatilization.

13.3      Characterization of the Contaminant Source and Environmental Setting

     The initial step in developing an effective monitoring program for a release to
surface waters is to investigate the  unit(s) that is the subject of the RFI, the waste
within the unit(s), the constituents within the waste, the operative release
mechanisms and migration pathways to surface water bodies, and the surface water
receptors. From this information, a  conceptual  model of the release can be
developed for use in designing a monitoring program to characterize the release.

13.3.1         Waste Characterization

     Knowledge of the  general  types of wastes involved is an important
consideration in the development of an  effective  monitoring program.  The
chemical and physical properties of a waste and the waste constituents  are major
factors in determining the likelihood that a substance will be released. These waste
properties may also be important initially in selecting monitoring  constituents and
indicator parameters. Furthermore, once the wastes are released,  these properties
play a major  role  in controlling the constituent's migration through the
environment and its fate.  Table 13-3 lists some of the significant properties in
evaluating environmental fate and transport in a surface water system. Without
data on the wastes, the  investigator may have to implement a sampling program
                                   13-8

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                                 TABLE13-3

              IMPORTANT WASTE AND CONSTITUENT PROPERTIES
     AFFECTING FATE AND TRANSPORT IN A SURFACE WATER ENVIRONMENT

Bulk waste properties affecting mobility*
     •    Physical state (solid, liquid, gas) of waste
     •    Chemical nature (e.g., aqueous vs non-aqueous) of waste
     •    Density (liquid)
     •    Viscosity (liquid)
     •    Interfacial tension (with water and minerals) (liquid)

Properties to assess mobility of constituents^
          Solubility
          Vapor pressure
          Henry's law constant (or vapor pressure and water solubility)
          Bioconcentration factor
          Soil adsorption coefficient
          Diffusion coefficient (in air and water)
          Acid dissociation constant
          Octanol-water partition coefficient
          Activity coefficient
          Mass transfer coefficients (and/or rate constants) for intermedia transfer
          Boiling point
          Melting point

Properties to assess persistence^
     •    Rate of biodegradation (aerobic and anaerobic)
     •    Rate of hydrolysis
     •    Rate of oxidation or reduction
     •    Rate of photolysis
a    These waste properties will be important when it is known or suspected that
     the waste itself has migrated into the environment (e.g., due to a spill).
b    These properties are important in assessing the  mobility  of constituents
     present in low concentrations in the environment.
c    For these properties, it is generally important to know (1) the effects of key
     parameters on the rate constants (e.g., temperature, concentration,  pH) and
     (2) the identity of the reaction products.

Sources of values for these and other parameters include Mabey, Smith, and Podall,
(1982), and Callahan, et al. (1979).  Parameter estimation methods are described by
Lyman, Riehl, and Rosenblatt, (1982), and Neely and Blau (1985).
                                    13-9

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involving many constituents to ensure that all potential constituents have been
addressed.  General guidance on defining physical and chemical properties and
identifying  possible monitoring constituents and indicator parameters is provided
in Sections 3 and 7.

     Below are brief synopses of several of the  key  release, mobility,  and fate
parameters summarized in Table 13-3.  Figure 13-1 shows the qualitative
relationship between various environmental partitioning parameters. Neely and
Blau (1985) provide a description of  environmental partitioning effects  of
constituents and application of partition coefficients.

     •   Physical State:
         Solid wastes would appear to be less susceptible to release and migration
         than liquids. However, processes such as dissolution (i.e., as a result of
         leaching  or runoff), and physical transport of waste particulates can act
         as significant release mechanisms.

     •   Water Solubility:
         Solubility is an important factor affecting  a constituent's release and
         subsequent migration and fate in the surface water environment. Highly
         soluble contaminants (e.g., methanol at 4.4 x 106 mg/L at 77oF) are easily
         and quickly distributed within the hydrologic cycle. These contaminants
         tend to  have relatively low adsorption coefficients for soils and
         sediments and relatively low bioconcentration factors in aquatic life. An
         example  of a less soluble constituent is tetrachloroethylene at 100 mg/L
         at 77oF.

     •   Henry's Law Constant:
         Henry's Law Constant indicates the relative tendency of a constituent to
         volatilize from aqueous solution to the atmosphere based on the
         competition  between its vapor  pressure and  water solubility.
         Contaminants with low Henry's Law Constant values (e.g., methanol,
         1.10x10-6 atm-m3/mole at  77oF)will tend  to favor the aqueous phase
                                  13-10

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     and volatilize to the atmosphere mere slowly than constituents with high
     values (e.g., carbon tetrachloride, 2.3 x 10-2 atm-m3/mole at 77°F). This
     parameter is important in determining the potential for inter-media
     transport to the air media.

•    Octanol/Water Partition Coefficient (Kow):
     The octanol/water partition coefficient (Kow) is defined as the ratio of an
     organic constituent's concentration in the octanol phase (organic) to its
     concentration  in  the  aqueous phase  in a two-phase octanol/water
     system.  Values of K0w carry no units.  Kow can be used to predict the
     magnitude of  an organic constituent's tendency to partition between
     the aqueous and organic phases of a two phase system such as surface
     water and aquatic organisms.  The higher the value of K0w, the greater
     the tendency  of an organic  constituent to adsorb to soil or waste
     matrices containing appreciable organic carbon  or  to accumulate in
     biota. Generally, constituents with Kow values greater than or  equal to
     2.3 are considered potentially bioaccumulative (Veith, et al., 1980).

•    Soil-Water Partition Coefficient (K
-------
     bioaccumulation, and therefore to determine whether sampling of the
     biota may be necessary.  Another source of BCFs for constituents  is
     contained in EPA's Ambient Water Quality Criteria  (for  priority
     pollutants). BCFs can also be predicted by structure-activity relationships.
     Constituents exhibiting a BCF  greater than  1.0  are potentially
     bioaccumulative. Generally, constituents exhibiting a  BCF greater than
     100 cause the greatest concern.

•    The Organic Carbon Adsorption Coefficient (K0c):
     The extent to which an organic constituent partitions between the solid
     and solution  phases of a saturated or unsaturated soil, or between runoff
     water and sediment,  is determined  by the  physical and chemical
     properties of both  the constituent and the soil  (or sediment).  The
     tendency of  a constituent to be adsorbed to soil is dependent on  its
     properties and on the organic carbon content of the soil or sediment. Koc
     is the ratio of the amount of constituent adsorbed per unit weight of
     organic carbon  in the soil or sediment to the concentration of the
     constituent in aqueous solution  at equilibrium.   Koc can be  used to
     determine the partitioning of a constituent between the water column
     and the sediment.  When constituents have L high K0c,  they have a
     tendency to  partition to the soil or sediment.  In  such cases, sediment
     sampling would be appropriate.

•    Other Equilibrium Constants:
     Equilibrium constants are important predictors of a compound's chemical
     state in solution.  In general, a constituent which is dissociated (ionized)
     in solution will be more soluble and therefore more likely to be  released
     to the environment and more likely to migrate in a surface water body.
     Many inorganic constituents, such as heavy metals and mineral acids, can
     occur as different ionized species depending on pH. Organic acids, such
     as the phenolic compounds, exhibit similar behavior.  It should also be
     noted that ionic metallic species present in the  release may have a
     tendency  to  bind to particulate matter, if present in a surface water
     body, and settle out to the sediment over time and distance.  Metallic
     species also generally exhibit bioaccumulative properties. When metallic
                              13-13

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     species are present in a release, both sediment and biota sampling would
     be appropriate.

•    Biodegradation:
     Biodegradation  results from the enzyme-catalyzed transformation of
     organic constituents, primarily from microorganisms. The ultimate fate
     of a constituent  introduced into a surface water or other environmental
     system (e.g., soil),  could be a constituent or compound  other than the
     species originally released.  Biodegradation potential should therefore
     be considered in designing  monitoring programs.  Section 9.3 (Soils)
     presents additional information on biodegradation.

•    Photolysis:
     Photodegradation or photolysis of constituents dissolved in aquatic
     systems can also occur. Similar to biodegradation, photolysis may cause
     the  ultimate fate  of a constituent introduced into a surface water or
     other environmental  system (e.g., soil) to be  different from  the
     constituent originally released.  Hence, photodegradation potential
     should also be considered in designing sampling and analysis programs.

•    Chemical Degradation (Hydrolysisand Oxidation/Reduction):
     Similar to photodegradation and biodegradation, chemical degradation,
     primarily through hydrolysis and oxidation/reduction (REDOX) reactions,
     can  also act to change constituent species once they are introduced to
     the environment.  Hydrolysis of organic compounds usually results in the
     introduction of a hydroxyl group  (-OH)  into  a  chemical structure.
     Hydrated metal ions, particularly those with a valence of 3 or more, tend
     to form ions in aqueous solution, thereby enhancing species solubility.
     Mabey and Mill (1978) provide a critical review of the hydrolysis of
     organic compounds in  water under environmental conditions.  Stumm
     and Morgan (1982) discuss the hydrolysis of metals in aqueous systems.
     Oxidation  may  occur as a  result of oxidants being formed  during
     photochemical processes  in  natural  waters.  Similarly, in some surface
     water environments (primarily those with low oxygen levels) reduction
     of constituents may take place.
                              13-14

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     Degradation, whether biological, physical or chemical, is often reported in the
literature as a half-life, which is usually measured in days.  It is usually expressed as
the time it takes for one half of a given quantity of a compound to  be degraded.
Long half-lives (e.g., greater than a month or a year) are characteristic of persistent
constituents.  It should be noted that actual  half-life can vary significantly  over
reported  values based on  site-specific conditions.  For example, the absence of
certain microorganisms at a site, or the number of microorganisms,  can influence
the rate  of biodegradation, and therefore, half-life.   Other conditions (e.g.,
temperature) may also affect degradation and change the half-life.  As such,  half-
life values should be used only as general indications of a chemical's persistence.

     In addition to the above, reactions between constituents present in a  release
may also  occur.   The  owner or  operator  should be aware  of  potential
transformation processes, based on the constituents'  physical, chemical  and
biological properties, and account for such transformations in the  design of
monitoring procedures and in the selection of analytical methods.

     Table 13-4 provides an application of the concepts discussed above in assessing
the behavior  of waste material  with respect to release, migration,  and fate. The
table gives general qualitative descriptors of the significance of some of the me -e
important properties and environmental  processes for the major classes of organic
compounds likely to be encountered.

     Table 13-4 can be used to illustrate several important relationships.
                        *
     •    Generally, water  solubility varies  inversely with  sorption,
         bioconcentration, and to a lesser extent, volatilization.

     •    Oxidation is a significant  fate process for some classes of constituents
         which can volatilize from the aqueous phase.

     •    Variations in properties and environmental processes occur within classes
         as indicated by the pesticides, monocyclic aromatics, polycyclic aromatics,
         and the nitrosamines and other nitrogen-containing compounds.
                                   13-15

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     Characterizing the environmental processes and properties of inorganic waste
constituents takes a similar approach to that shown on Table 13-4 for organics.
However, characterizing the metals on a class-by-class basis is not advisable because
of the complex nature of each metal and the many species in which the metals
generally occur.  The  interaction of each metal species with the surface  water
environment is generally a function of many parameters including pH, REDOX
potential, and ionic strength.  See Stumm and Morgan (1982) for additional
discussions on this subject. Generally, however, when metal species are present in a
release, it is advisable to monitor the sediment and biota, in addition to the water
column.  This is due to likely deposition of metals as particulate matter, and to
potential bioaccumulation.

13.3.2        Unit Characterization

     The relationship between unit characteristics and  migration  pathways
provides the framework in this section for a general  discussion of release
mechanisms from units of concern to surface waters.

13.3.2.1       Unit Characteristics

     Information on design and operating characteristics of a unit can be helpful in
characterizing a release. Unsound unit design and operating practices can allow
waste to migrate from a unit and  possibly  mix  with  runoff.  Examples include
surface impoundments with  insufficient  freeboard, allowing for  periodic
overtopping; leaking tanks or containers; or land-based units above shallow, low-
permeability materials which, if not properly designed and operated, can fill with
water and spill over.  In addition,  precipitation falling on exposed wastes can
dissolve and thereby mobilize hazardous constituents. For example, at uncapped
active or inactive waste piles and landfills, precipitation and leachate are likely to
mix at the toe of the active face or the low point of the trench floor. Runoff may
then flow into surface water through drainage pathways.
                                   13-17

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13.3.2.2       Frequency of Release

     Releases to  surface waters may be  intermittent, continuous, or a  past
occurrence.  It is important to consider the anticipated frequency of a release to
establish an effective monitoring program.

     Most direct releases to surface waters are intermittent. Intermittent discharges
may be periodic, but may occur more often in a non-periodic manner, for example,
in response to rainfall runoff. Other common factors affecting intermittent releases
include fluctuations in water levels and flow rates, seasonal conditions (e.g., snow
melt), factors affecting mass stability (e.g., waste  pile mass migration),  basin
configuration, quantity/quality of vegetation, engineering  control practices,
integrity of the unit, and process activities.

     Erosion  of contaminated materials  from a unit (e.g., a landfill) is generally
intermittent,  and is generally associated with rainfall-runoff events.  Similarly,
breaches in a dike are generally short-term occurrences when they are quickly
corrected following discovery.  Leaks, while still  predominantly  intermittent in
nature, may occur over longer spans of  time and are dependent on the rate  of
release and the quantity of material available.

     Direct placement of wastes within surface waters (e.g., due to movement of an
unstable waste pile) has the potential to continuously contribute waste constituents
until the wastes have been removed or the waste constituents exhausted.  Direct
placement is usually easily  documented by  physical presence of wastes within the
surface water body.

     The frequency of sample collection should be considered in the design of the
monitoring program.  For example, intermittent releases  not associated  with
precipitation runoff may  require  more frequent or even continuous sample
collection to obtain representative data on the receiving water body. Continuous
monitoring is generally feasible only for the limited number of constituents and
indicator parameters for which reliable automatic sampling/recording equipment is
available.  Intermittent releases that are  associated with precipitation runoff may
require event sample collection. With event sampling, water level or flow-activated
automatic sampling/recording equipment can be used. For continuous releases, less
                                   13-18

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frequent sample collection is generally adequate to obtain representative data on
the receiving water body.

     Previous intermittent releases may  be identified through  the  analysis  of
bottom sediments, and whole body or tissue analyses of relatively sessile and long-
lived macroinvertebrates (e.g., clams), or other species, such as fish. These analyses
may identify constituents that may have adsorbed onto particulates and settled to
the sediment, as well as bioaccumulative contaminants. In  addition, intermittent
releases may be detected through the use  of in situ bioassays.  Using  these
procedures, the test specie(s) is held  within the  effluent or stream flow and
periodically checked for survival and condition.

13.3.2.3        Form of Release

     Releases to surface waters  may be generally categorized as point sources or
non-point sources.  Point  sources are those that enter the  receiving  water at a
definable location, such  as piped discharges.  Non-point source discharges are all
other discharges, and generally cover large areas.

     In general, most unit releases to surface waters are likely to be of a point
source  nature.  Most spills, leaks, seeps,  overtopping episodes, and breaches occur
within  an area which can be easily defined. Even erosion of contaminated soil and
subsequent deposition to surface water can usually be identified in terms of point
of introduction to the surface water body, through the use  of information on
drainage patterns, for example. However, the potential for both point and non-
point  sources  should be recognized, as  monitoring programs  designed  to
characterize these types of releases can be different.  For example,  the generally
larger  and  sometimes  unknown areal extent of non-point source discharges may
require an  increase  in the number of monitoring locations from that  routinely
required for point source discharges. The number of monitoring locations must be
carefully chosen to ensure representative monitoring results.

13.3.3          Characterization of the Environmental Setting

    The environmental setting includes the surface water bodies and the physical
and biological environment.  This section provides a general classification scheme
for surface waters and discusses collection of hydrologic data that may be important
in  their characterization.  Collection  of specific geographical and climatological
                                   13-19

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data are also discussed.  Characterization of the biotic environment is treated in
Section  13.4.

     Note that individual states have developed water quality standards for surface
waters pursuant to the Clean Water Act. These standards identify the designated
uses (e.g., drinking, recreation, etc.) of a surface water and  a maximum
contaminant level to support the use.  If applicable, the owner or operator should
report such standards.

13.3.3.1        Characterization of Surface Waters

     Surface waters can be classified into one of the following categories. These
are obviously not pure classifications; intergrades are common.

     •    Streams and rivers;

     •    Lakes and impoundments;

     •    Wetlands; and

     •    Marine environments.

13.3.3.1.1       Streams and Rivers

     Streams and rivers are conduits of surface water flow having defined beds and
banks.  The  physical characteristics of streams and rivers greatly influence their
reaction to  contaminant releases and natural purification (i.e.,  assimilative
capacity).  An understanding of the nature of  these influences is important to
effective  planning and execution  of a monitoring program.   Important
characteristics include depth, velocity, turbulence, slope, changes in direction and in
cross sections, and the nature of the bottom.

     The effects of some of these  factors are so interrelated that it is difficult to
assign greater or lesser importance to them.  For example, slope and roughness of
the channel influence depth and velocity of flow,  which together control
turbulence.   Turbulence,  in turn, affects rates of contaminant dispersion,
                                   13-20

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 reaeration, sedimentation, and  rates of natural purification.   The nature of
 contaminant dispersion is especially critical in the location of monitoring stations.
 All these factors may be of greater or lesser importance for specific sites.  It should
 also be noted that these factors may differ at the same site depending on when the
 release occurred. For example, differences between winter and summer flow may
 greatly influence the nature of contaminant dispersion.

     Of further relevance  to  a surface water investigation are the distinctions
 between ephemeral, intermittent, and perennial streams, defined as follows:

     •    Ephemeral streams are those that flow only in response to precipitation
          in the immediate watershed or in response to snow melt. The channel
          bottom of an ephemeral stream is always above the local water table.

     •    Intermittent streams are those that usually drain watersheds of at least
          one square mile and/or receive some  of their flow  from  baseflow
          recharge from ground water during at least part of the year, but do not
          flow continually.

     •    Perennial streams flow throughout the year in response to ground water
          discharge and/or surface water runoff.

     The distinction between  ephemeral, intermittent and perennial streams will
 also influence the selection of monitoring frequency, monitoring locations and
 possibly other monitoring program design factors.  For example, the frequency of
 monitoring for ephemeral streams, and to a lesser extent intermittent streams, will
 depend on rainfall runoff.  For perennial-stream monitoring, the role of rainfall
 runoff in monitoring frequency may be of less importance under similar release
 situations.

    The location of ephemeral and intermittent streams may not be apparent to
the owner or operator during periods of little or no precipitation.  Generally,
 intermittent  and ephemeral streams may be  associated  with topographic
depressions in which surface water runoff is conveyed to receiving waters.  In
addition to topography, a high density of vegetation in such areas may be an
indicator of the presence of ephemeral or intermittent drainage.
                                  13-21

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     Perennial streams and rivers are continually engaged in a dynamic relationship"
with ground water, either receiving ground-water discharge (gaining stream) or
recharging the ground water (losing stream) over any given stream reach.  These
characteristics should be considered in the evaluation of contaminant transport and
fate.

     The Ecology of Running Waters (Hynes 1970) and Introduction to Hydrology
(Viessman et al., 1977) may be reviewed for basic  discussions of surface  water
hydrology.

13.3.3.1.2     Lakes and Impoundments

     Lakes are typically considered natural, while impoundments  may be man-
made.  The source for lakes and  impoundments may be either surface water or
ground water, or both.  Impoundments may be either incised  into the ground
surface or may be created via the placement of a dam or embankment.  As with
streams and rivers, the physical characteristics of lakes and impoundments influence
the transport and fate of contaminant releases and therefore the  design of the
monitoring program. The physical characteristics that should be evaluated include
dimensions (e.g., length, width, shoreline, and depth), temperature distribution,
and flow pathways.

     Especially in the case of larger lakes and impoundments, flow paths are not
clearcut from inlet to  outlet.  Not only is the  horizontal component of flow in
question, but as depth of the water body increases in the open water zone, chemical
and more commonly physical (i.e., temperature)  phenomena  create a vertical
stratification or zonation. Figure 13-2 provides a typical lake cross section, showing
the various zones of a stratified lake.

     Because of stratification, deeper water  bodies can  be considered  to be
comprised of three lakes.  The upper lake, or epilimnion, is characterized by good
light penetration, higher levels of dissolved oxygen, greater overall  mixing due to
wave action, and elevated biological activity. The lower lake, or hypolimnion, is the
opposite  of the epilimnion. Lying between these is what  has  been termed the
                                  13-22

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 (Source Adapted from Col*. 1975).
                           13-23

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middle lake or mesolimnion, characterized by a rapid decrease in temperature with
depth. Were it not for the phenomenon of lake overturn, or mixing, contaminants
with specific gravities greater than water might be confined to the lowermost lake
strata, where they might remain for some time. Due to the potential importance of
lake mixing to contaminant transport, it is discussed below.

     Temperatures within the epilimnion are relatively uniform because of the
mixing that occurs there.  Water is most dense at 4o Centigrade (C); above and
below 4oC its density decreases. In temperate climates, lake mixing is a seasonal
occurrence. As the surface of the epilimnion cools rapidly in the fall, it becomes
denser than the  underlying strata.  At some point, the underlying strata can no
longer support the denser water and an "overturn" occurs, resulting in lake mixing.
A similar phenomenon occurs in the spring as the surface waters warm to 4oc and
once again become denser than the underlying waters.

     Because  of  the influence of stratification  on the transport of contaminants
within a lake or reservoir, the location of monitoring points will largely depend on
temperature stratification.  The monitoring points on water bodies that are not
stratified will be more  strongly influenced  by horizontal flowpaths, shoreline
configuration and other factors. The presence of temperature stratification can be
determined by establishing temperature-depth profiles of the water body.

     More information on lakes and impoundments may be found in the following
references:

     A Treatise on Limnology. Volumes I and II (Hutchinson. 1957,1967) or

     Textbook of Limnology (Cole. 1975)

13.3.3.1.3      Wetlands

     Wetlands are those areas that are inundated or saturated by surface or ground
water at a frequency and duration sufficient to support, and  that under normal
circumstances do support, a prevalence of vegetation typically adapted for life in
saturated soil conditions.  Wetlands include,  but  are not limited  to, swamps,
marshes, bogs, and similar areas.
                                  13-24

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     Wetlands are generally recognized as one of the most productive and sensitive
of biological habitats, often  associated with critical habitat for State or Federally
listed special-status  species  of plants or wildlife.  Wetlands also  may  play  a
significant  role in basin hydrology, moderating peak surface water flows and
providing recharge to the ground water system. The definition of the extent and
sensitivity of wetlands that may be affected by a release is essential to release
characterization.

     High organic content, fine-grained sediments, slow surface water movement
and lush vegetative growth and biological activity contribute to a high potential for
wetlands to concentrate contaminants from releases.  This is  especially true for
bioaccumulative  contaminants,  such  as heavy metals.  The  pH/Eh  conditions
encountered in many wetlands are relatively unique and can  have a  significant
effect on a  contaminant's toxicity, fate, etc. Seasonal die-off of the vegetation and
flooding conditions within the  basin may result in  the  wetlands serving as a
significant  secondary source of contaminants to downstream surface water
receptors.

13.3.3.1.4     Marine Environments

     For the purpose of this guidance,  marine environments are restricted  to
estuaries, intermediate between  freshwater and saline, and ocean environments.
Industrial development near the mouths of rivers and near bays outletting directly
into the ocean is  relatively widespread, and the estuarine environment may be a
common receptor of releases from industrial facilities.
                                                                    t
     Estuaries are influenced by both fresh water and the open ocean.  They have
been functionally defined as tidal habitats that are partially enclosed by land but
have some access to the open sea, if only sporadically, and in which ocean water is
partially diluted by fresh water.  Estuaries may also experience conditions where
salinities are temporarily driven above the ocean levels due to evaporative losses.
Because of  the protection afforded by encircling land areas, estuaries are termed
"low-energy" environments,  indicating that wave energy and  associated  erosive
and mixing  processes are reduced.
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     The physical characteristics of an estuary that will influence the design of a
monitoring program are similar to those considered for lakes and impoundments
(i.e., length, width, shoreline, depth, and flow pathways).  However, the increased
probability for chemical stratification due to  varying salinities may be most
pronounced in areas where freshwater streams and rivers discharge into  the
estuary. The monitoring program design should also consider tidal influences on
stratification and contaminant dispersion.

     In  addition, estuaries, or some portions of estuaries, can be areas of
intergrained sediment deposition.  These sediments  may contain a significant
organic fraction, which enhances the opportunity for metal/organic adsorption, and
subsequent bioaccumulation. Hence, biomonitoring within an estuary may also be
appropriate. The ionic strength of contaminants may also have an important effect
on their toxicity, fate, etc., in the marine environment.

13.3.3.2        Climatic and Geographic Conditions

     A  release to  the surface water  system  will be influenced  by local
climatological/meteorological and geographic conditions.  The release may be
associated only with specific seasonal conditions like spring thaws or meteorological
events such as storms. If the release is intermittent, the environmental conditions at
the time of the release may help identify the cause of and evaluate the extent of the
release. If the release is continuous, seasonal variations should also be evaluated.

     The local climatic conditions should be reviewed to determine:

     •   The annual precipitation distribution (monthly averages);

     •    Monthly temperature variations;

     •   Diurnal temperature range (daytime/nighttime difference);

     •   Storm frequency and  severity;

     •   Wind direction and speed; and
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     •    Snowfall and snow pack ranges (if applicable).

     This  information will be useful in developing a sampling schedule and in
selecting sampling methods. From these data, it should be possible to anticipate
the range of climatic conditions at the site.  These conditions may be far more
complex than simple cold/hot or wet/dry seasons.  Some areas have two or more
"wet seasons", one characterized by prolonged showers, another by brief intense
storms, and perhaps a third as a result of snowmelt.  Cold/hot seasons may overlap
these wet/dry seasons to create several climatologically identifiable seasons.  Each
season  may affect the release differently and may  require a separate
characterization. The unique climatological seasons that influence the site should
be identified. Typical winter, spring, summer and fall seasonal descriptions may not
be appropriate or representative of the factors influencing the release. Sources of
climatological data are given in Section 12 (Air).

     In  addition to the climatological/meteorologica! factors, local  geographic1
conditions will influence the design  of the sampling program.  Topographic1
conditions and soil structure may make some areas prone to flash floods and stream
velocities that are potentially damaging to sampling equipment.   In other areas
(e.g., the coastal dune areas of the southeastern states), virtually no runoff oca rs.
Soil porosity and vegetation are such that all precipitation either enters the ground
water or is lost to evapotranspiration. (See Section 9 (Soil) for more information).

     A description of the geographic setting will  aid in  developing a  sampling
program that is responsive to the  particular conditions  at the facility. When
combined with a  detailed understanding of the  climatological/meteorological
conditions in the area, a workable monitoring framework can be created.

13.3.4     Sources of Existing Information

     Considerable information may already be available to assist in characterizing a
release.  Existing information should be reviewed to avoid duplication of previous
efforts and to aid in focusing the RFI.  Any information relating to releases from the
unit, and to hydrogeological, meteorological, and environmental factors that could
influence  the  persistence,  transport or location of  contaminants should be
reviewed.  This information may aid in:
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     •    Delineating the boundaries of the sampling area;

     •    Choosing sampling and analytical techniques; and

     •    Identifying information needs for later phases of the investigation.

Information may  be obtained  from readily available sources of geological and
meteorological data, waste characteristics, and facility operations records. (See also
Sections 2,3, 7 and Appendix A).

13.4      Design of a Monitoring Program to Characterize Releases

     Following characterization of the contaminant source and environmental
setting, a monitoring  program is developed.  This section outlines and describes
factors that should be considered in design of an effective surface water monitoring '
program. The characterization of contaminant releases may take place in multiple
phases. While the factors discussed in this section should be carefully considered in
program design, each of these generic approaches may  require modification  for
specific situations.

     The primary  considerations in designing a surface water monitoring program
are:

     •    Establishing the objectives of the monitoring program;

     •    Determining the constituents of concern;

     •    Establishing the hydrologic characteristics of the receiving water and
         characteristics of the sediment and biota, if appropriate;

     •   Selecting constituents and/or indicators for monitoring;

     •   Selecting monitoring locations and monitoring frequency; and
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                                        I
     •    Determining the need for sediment monitoring and, hydrologic and
          biomonitoring.

 13.4.1          Objectives of the Monitoring Program

     The principal objectives of a monitoring program are to:

     •    Identify the characteristics of releases (e.g., continuous vs intermittent);

     •    Identify the fate of constituents;

     •    Identify the nature, rate, and extent of the  release and actual  or
          potential effects on water quality and biota; and

     •    Identify the effect of temporal variation on constituent fate and identify
          impacts on water quality and biota.

     Periodic monitoring of the surface water system  is often  the only effective
 means of identifying the occurrence of releases and their specific effects. Releases
 can be continuous or intermittent, point source, or non-point source.  The concept
 of monitoring is the same, regardless of the frequency or form of the release.  A
 series of measurements, taken over time, better approximate the actual release to
 surface waters than a one-time grab sample.

     The functional difference between monitoring the various types of discharges
 is the point of measurement.  Point source discharges may be monitored at and/or
 near the discharge point to surface waters. The fate and potential effects of non-
 point source discharges should be inferred through measurement of the presence of
 constituents of concern or suitable indicators of water quality within the receiving
water body.

     The monitoring program should also establish the background condition
against which to measure variations in a continuous release or the occurrence of an
intermittent release. Such information will enable the facility owner or operator to
compile data that will establish trends in releases from a given unit(s) as well as to
identify releases from other sources.
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     Monitoring programs should characterize contaminant releases as a function
of time. Climatologic factors such as frequency of intense rainfall, added effects of
snowmelt, temperature extremes, and mixing in lakes and estuaries should be
evaluated and quantified as causative agents for intermittent contaminant release.

     Important concepts to consider in  designing  the monitoring program for
surface water to help meet the above-stated objectives are described below.

13.4.1.1       Phased Characterization

     The initial phase  of a surface water release characterization program may be
directed toward verification of the occurrence of a  release identified as suspected
by the regulatory agency.  It may also serve as the  first step for characterizing
surface water systems  and releases to those  systems in cases where a release has
already been verified.

     The initial characterization wilt typically be a short-duration activity, done in
concert with evaluation of other media that may either transport contaminants to
surface waters, or may themselves be affected by discharges from surface  waters
(i.e., inter-media transport).  It may be particularly difficult to define intermittent
discharges in the initial characterization effort, especially if the contaminants from
these releases are transient in the surface water body.

     If the waste characterization is adequate,  the initial characterization  phase
may rely upon monitoring constituents and suitable indicator parameters to aid in
defining the nature, rate, and extent of a release.  Subsequent phases of release
characterization will  normally take  the form  of  an expanded environmental
monitoring program and hydrologic evaluation, sensitive to seasonal variations in
contaminant release and loading to the receiving water bodies, as well as to natural
variation in hydrologic characteristics (e.g., flow velocity and volume, stream cross
section).
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 13.4.1.2       Development of Conceptual Model

     To effectively design  a monitoring program, it is important to develop  a
 conceptual model or understanding of the fate of constituents of the release in the
 receiving water body.  This conceptual understanding will assist in answering the
 following questions.

     •    What portion of the receiving water body will be affected by the release
          and what conditions (e.g., low flow, immediate  stormwater runoff)
          represent reasonable worst case conditions under which sampling should
          occur?

     •    What should the relative concentrations of contaminants be at specific
          receptor points within the water body (e.g., public water supply intakes
          downstream of a site)?
                                                                          i
     •    How does the release of concern relate to background contamination in'
          the receiving water body as a result of other discharges?

     •    How might the monitoring  program be optimized, based on
          contaminant dispersion and relative concentrations within the receiving
          water body?

     The fate of waste constituents entering surface waters is highly dependent on
 the hydrologic characteristics of the  various classifications of water bodies, (i.e.,
 streams and rivers, lakes and impoundments, wetlands, and estuaries, as discussed
 earlier). Because of their complexity, methods for characterization of contaminant
 fate in wetlands and estuaries is not presented in detail in this guidance. The reader
 is referred to Mills (1985) for further detail on characterizing contaminant fate in
wetlands and estuaries.

 13.4.1.3       Contaminant Concentration vs Contaminant Loading

    Concentration and loading are  different  means of expressing  contaminant
levels  in a release or receiving water body. The concept is important in the selection
of constituents for monitoring.  Both  concentration and  loading should be
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evaluated with respect to the release and the receiving  waters.   Basing an
evaluation solely on concentration may obscure the actual events. In addition, it is
essential  to quantify  individual sources of contaminants and the relationships
between  media, as well as the loading found in the receiving water body, to
effectively define the nature and extent of the contaminant release.

     Contaminant concentrations in receiving  waters have specific value in
interpreting the level of health or environmental effects anticipated from the
release. Contaminant loading provides a common denominator for comparison of
contaminant inputs between monitoring points. In addition, especially in the case
of contaminants that are persistent in  sediments (e.g., heavy metals), loadings are a
convenient means of expressing ongoing contributions from a specific discharge.
The distinction between concentration and loading is  best drawn through the
following example.

     A sample collected from a stream just upgradient of a site boundary (Station
A) has a  concentration of 50 micrograms per liter (ug/l) of chromium. A second
sample collected just downstream  of the  site (Station  B)  has a chromium
concentration of 45 ug/l-  From these data it appears that the site is not releasing
additional chromium to the stream.   If, however, the stream flow is increasing
between  these two sampling locations, a different interpretation is apparent.  If the
stream flow at the upstream location is 1,000 gallons per minute (gpm) and the
downstream location is 1,300 gpm, the actual loading of chromium to the stream at
the two locations is as follows:

Station A
Chromium = (50.0 ug/l)(1,000 gal/min)(10-9 kg/ug)(60 min/hr)(3.785 I/gal) - 0.0114
kg/hr

Station B
Chromium =  (45.0 ug/l)(1,300gal/min)(10-9kg/ng)(60 min/hr)(3.785 I/gal) = 0.0133
kg/hr

     It is  now apparent that somewhere between the two sampling stations is  a
source(s)  contributing 0.0019 kg/hr of chromium.  If all of the flow difference (i.e.,
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300 gpm) is from a single  source, then this source would  have a chromium
concentration of 27.9 ug/l:

Chromium = [(0.0019 kg/hr)(1Q9 ug/kg)(1hr/60min)(1 min/300 gal)(1 gal/3.785 I)] =
27.9 ug/l

     If, however, 90 percent of this flow difference (i.e., 270 gpm) was due to
ground-water discharge with a chromium concentration below detectable limits
and the remaining 10 percent (i.e., 30 gpm) was the result of a direct discharge from
the facility, this discharge could have a chromium concentration of 279 ug/l.

13.4.1.4        Contaminant Dispersion Concepts

     Contaminant dispersion concepts and models of constituent fate can be used
to define constituents to be monitored and the location  and frequency of
monitoring.  Dispersion may occur in streams, stratified lakes or reservoirs, and in1
estuaries. Dispersion may be continuous, seasonal, daily, or a combination of these.

     The discussion below  is based on information contained in  the Draft
Superfuno' Exposure Assessment Manual  (EPA, 1987) relative to simplified  models
useful in surface water fate analyses. The reader is directed to that document for a
more in-depth discussion of models. The equations presented  below are based on
the mixing  zone concept originally developed for EPA's National Pollutant
Discharge Elimination  System (NPDES) under the Clean Water Act.   To avoid
confusion over regulatory application of these concepts in the NPDES program,  and
the approach presented below (basically to aid in the development of a monitoring
program), the following discussion refers to use of the "Dispersion Zone".

     The following equation  provides an approximate estimate of  the
concentration  of a substance downstream from  a  point  source release, after
dilution in the water body:

                CuQu + CWQW
     Cr   =     	
                  Qu + Qw
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where:

     Cr    =   downstream  concentration  of substance following complete
              dispersion (mass/volume)
     Cu    =   upstream concentration of substance before effluent release point
              (mass/volume)
     Cw   =   concentration of substance in effluent (mass/volume)
     Qw   =   effluent flow rate (volume/time)
     Ou   -   upstream flow rate before effluent release point (volume/time)

     The following equation may be used to estimate instream concentrations after
dilution  in situations where waste constituents are" introduced via inter-media
transfer or from a non-point source, or where the release rate is known in terms of
mass per unit time, rather than per unit effluent volume:

                Tr + Mu
where:
     Tr    =   inter-media transfer rate (mass/time)
     MU   =   upstream mass discharge rate (mass/time)
     Qt   -   stream flow rate after inter-media transfer or non-point source
              release (volume/time)

     The above two equations assume the following :

     •    Dispersion is instantaneous and complete;

     •    The waste constituent is conserved (i.e., all decay or removal processes
          are disregarded); and

     •    Stream flow and rate of contaminant release to the stream are constant
          (i.e., steady-state conditions).
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     For a certain area downstream of the  point of release, the assumption  of
complete dispersion may not be valid. Under certain situations, the dispersion zone
can extend downstream for a considerable distance, and concentrations can be
considerably higher  within the dispersion  zone than those estimated by the
equation. The length of this zone can be approximated by the following equation:

                0.4
     D2   =
                O.Sdygds

where:

     DZ   =   dispersion zone length (length units)
     w    =   width of the water body (length units)
     u    =   stream velocity (length/time)
     d    =   stream depth (length units)
     s    =   slope (gradient) of the stream channel (length/length)             '
     g    =   acceleration due to gravity (32 ft/sec2)

     Within the dispersion zone, contaminant concentrations will show spatial
variation.  Near the release point the contaminant will be restricted (for a discharge
along one shoreline)  to the nearshore area and (depending on the way  the
discharge  is introduced and its density) can be vertically confined.  As the water
moves downstream, the contaminant will disperse within surrounding ambient
water and the plume will widen  and deepen.  Concentrations will generally
decrease along the plume centerline  and the concentration gradients away from
the centerline will decrease. Eventually, as described above, the contaminant  will
become fully  dispersed within the  stream;  downstream from this point
concentration will be constant throughout the stream cross-section, assuming that
the stream flow rate remains constant.

     It is  important to understand  this concentration  variability within  the
dispersion  zone if measurements are to be made near the release.   Relatively
straightforward analytical expressions (See Neely, 1982) are available to calculate
the spatial variation of concentration as a function of such parameters as stream
width, depth,  velocity, and dispersion coefficients.  Dispersion coefficients
characterize the dispersion between  the stream  water and contaminated influx;
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they can, in turn, be estimated from stream characteristics such as depth, gradient,
and path (i.e., straight or bends).

     The above considerations are for instream concentrations resulting from the
releases of concern.  If total instream  concentrations  are required, the
concentrations determined from  background water samples should also be
considered.  In addition, if introduction of the contaminant occurs over a fixed
stream reach, as mig : be the case with a non-point discharge, it should be assumed
that the dispersion zone begins at the furthest downstream point within this reach.

13.4.1.5       Conservative vs Non-Conservative Species

     The expressions presented thus far have assumed that the  contaminant(s) of
concern is conservative (i.e., that the mass loading of the contaminant is affected
only by the mechanical  process of dilution).  For contaminants that are non-
conservative, the above equations would provide a conservative estimate  of  '
contaminant loading at the point of interest within the receiving water body.

     In  cases where  the concentration  after dilution of a  non-conservative
substance is still expected to be above a level of concern, it  may be useful  to
estimate the distance downstream where the concentration will  remain above this
level and  at selected points  in  between.  The reader is  referred to  the Draft
Superfund Exposure Assessment Manual (EPA, 1987), for  details regarding this
estimation procedure  and  to specific State Water Quality Standards  for
determination of acceptable instream concentrations.

13.4.2         Monitoring Constituents and Indicator Parameters

13.4.2.1       Hazardous Constituents

     The facility owner or operator should propose a list .of constituents and
indicator  parameters,  if appropriate,  to  be included  in  the Surface Water
investigation.  This list should be based on a site-specific  understanding of the
composition of the release source(s) and the operative release mechanisms, as well
as the physical and  chemical characteristics of the various classes of contaminants.
These factors,  as well as potential release mechanisms and migration  pathways,
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have been discussed in Sections 13.3 and 13.4.1. Also refer to Sections 3 and 7 of this
guidance, and to the lists of constituents provided in Appendix B.

13.4.2.2       Indicator Parameters

     Indicator  parameters (e.g., chemical and biochemical oxygen demand, pH,
total suspended solids, etc.) may also play a useful role in release characterization.
Though  indicators can  provide  useful  data for release verification and
characterization, specific hazardous constituent  concentrations should always be
monitored. Furthermore, many highly toxic constituents may not be detected by
indicators because they do not represent a significant amount of the measurement.

     Following are brief synopses of some common indicator parameters and field
tests that can be used in investigations of surface water contamination.  The use of
biomonitoring  as an indicator of contamination is discussed in Section 13.4.5.
                                                                         i
Biochemical Oxygen  Demand (BOD) and Chemical Oxygen  Demand (CQD)--BOD is
an estimate of the amount of oxygen required for the biochemical degradation of
organic material (carbonaceous demand) and the oxygen used to oxidize inorganic
material such as sulfides and ferrous iron. It may also measure the oxygen used to
oxidize reduced forms of nitrogen (nitrogenous demand! unless their oxidation is
prevented by an inhibitor.  Because the complete stabilization  of a BOD sample may
require an extended period, 5 days has been accepted as the standard  incubation
period.  While BOD measures only biodegradable organics,  non-biodegradable
materials can exert a demand on the available oxygen in an aquatic environment.
COD measures the total oxygen demand produced by biological and chemical
oxidation of waste constituents. Availability of results for the COD in approximately
4 hours, versus 5 days for the BOD, may be an important advantage of its use in
characterizing releases of a transient nature.

    COD values are essentially equivalent to BOD when the oxidizable materials
present consist  exclusively of organic matter. COD values exceed BOD values when
non-biodegradable materials that are susceptible to oxidation are present.  The
reverse is not often the case;  however, refinery wastes provide a notable exception.
There are some organic compounds, such as  pulp and paper mill cellulose, that are
non-biodegradable, yet oxidizable.  Nitrogenous compounds, which may place a
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significant drain on available oxygen in aquatic environments, are not measured in
the COD test.  In addition, chlorides interfere  with  the  COD  test,  leading to
overestimates  of the actual COD.   BOD/COD ratios, as an  indicator of
biodegradability, are discussed in Section 9 (Soil).  BOD and COD  may be useful
indicator parameters if the release is due primarily to degradable organic wastes.

Total Organic Carbon (TOC)--Total organic carbon is valuable as a rapid estimator of
organic contamination in a receiving water. TOC, however, is not specific to a given
contaminant or even to specific classes of organics. In addition, TOC measurements
have little use if the release is primarily due to inorganic wastes.

Dissolved Oxygen (DO)--Measurements of DO may be readily made in the field with
an electronic DO meter, which  has virtually  replaced laboratory titrations.
Especially in lake environments, it is valuable to know the DO profile with depth.
The bottoms of lakes are often associated with  anoxic conditions (absence  of
oxygen) because of the lack of mixing with the surface and reduced or non-existent'
photosynthesis.  Influx of a contaminant load with a  high oxygen demand can
further exacerbate oxygen deficiencies under such conditions. In addition, low DO
levels favor reduction, rather than oxidation  reactions, thus altering products of
chemical degradation of contaminants.  DO levels less than 3 mg/liter (ppm) are
considered stressful to most aquatic vertebrates (e.g., fish and amphibians).

pJH-pH is probably one of the  most common field measurements made of surface
waters.  It is defined as the inverse log of the hydrogen ion concentration of an
aqueous medium.  pH is generally measured in  the field with analog or digital
electronic pH meters.

     As an indicator of water pollution, pH is important for two reasons:

     •   The range within which most aquatic  life forms are tolerant  is usually
         quite narrow.  Thus, this factor has significant implications in terms of
         impact to aquatic communities; and

     •   The pH of a solution may be a determining factor in moderating other
         constituent reactions.
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Temperature-Alonq with pH, temperature is a fundamental parameter that should
always be recorded in the field when a water sample is collected. Temperature is
most often measured by electronic meters that can simultaneously record pH and/or
specific conductance. Temperature is a significant parameter because:

     •    Most aquatic species are sensitive to elevated temperatures;

     •    Elevated temperatures can be an indication of a contaminant plume;

     •    Most chemical reactions are temperature-dependent; and

     •    Temperature defines strata in thermally-stratified lakes.

Alkalinity-Alkalinity  is the capacity  of water to resist a depression in pH.  It is,
therefore, a  measure of the ability of the water to accept hydrogen ions without
resulting in  creation of an acid medium.   Most natural waters have substantial
buffering capacity (a resistance to any alteration in pH, toward either the alkaline
or acid side) through dissolution  of carbonate-bearing minerals, creating a
carbonate/bicarbonate buffer system.

     Alkalinity is usually expressed in calcium carbonate (CaCOa) equivalents and is
the sum of alkalinities provided by the carbonate, bicarbonate, and hydroxide ions
present in solution. Alkalinities in the natural environment usually range from 45 to
200 milligrams per liter  (mg/l). Some  limestone  streams have extremely high
buffering capacities, while other natural streams are very lightly buffered and are
extremely sensitive to acid (or alkaline) loadings.

Hardness-The sum of carbonate and  bicarbonate alkalinities is also termed
carbonate hardness.  Hardness  is generally considered a measure of  the total
concentration of calcium and magnesium ions present in solution, expressed as
CaCO? equivalents.

     Calcium and magnesium  ions  play a role in plant and animal uptake of
contaminants; knowledge of the  hardness of a surface water is necessary for
evaluation of the site-specific bioaccumulative  potential of certain contaminants
(e.g., heavy metals).
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Total Solids-Analytically. the total solids (TS) content of a water is that remaining
after evaporation at 103-115° C or 180oC, depending on the method.  The residue
remaining represents a sum of the suspended, colloidal, and dissolved solids.
Hazardous constituents with high vapor pressures (i.e., volatiles, semi-volatiles) will
not remain after evaporation, and will not contribute to the TS determination.

Suspended Solids-Suspended solids are those materials that will not pass a glass-
fiber filter.  Suspended solids contain both organic and inorganic compounds. For
the purpose of comparison to  water samples, the average domestic wastewater
contains about 200 ppm (mg/l) of suspended solids.

Volatile Suspended Solids-Volatile suspended solids are the volatile organic portion
of the suspended  solids.   Volatile suspended solids are the components of
suspended solids that volatilize at a temperature of 600° C. The residue or ash is
termed fixed suspended solids and is  a measure of the  inorganic fraction (i.e.,1
mineral content).  The only inorganic salt that will degrade below  600<> C is'
magnesium carbonate.

Total Dissolved Solids-Total dissolved  solids context is obtained  by subtracting
suspended solids from total solids. Its significance lies in the fact that it cannot be
removed from a surface water or effluent stream through  physical means or simple
chemical processes, such as coagulation.

Salinity-The major salts contributing to  salinity are sodium chloride (NaCI) and
sulfates of magnesium and calcium (MgSOd, CaSO4). The following represents an
example of classification of saline waters on the basis of salt content.
         Type of Water       Total Dissolved Solids (As Salts)
         brackish             1,000 to 35,000 mg/l
         seawater            35,000 mg/l
         brine               > 35,000 mg/l

Specific Conductances-Conductivity measures the capacity to conduct current.  Its
counterpart is, of course, resistance, measured in ohms. The unit of conductivity has
been defined as the mho. Specific conductance is conductivity/unit length. The most
common units for specific conductance are mho/cm. Specific conductance can be
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 measured instantaneously with electronic conductivity meters to comparatively
 high levels of accuracy and precision in the field and is an excellent real-time
 indicator parameter.

     Conductivity generally rises with increased concentration of dissolved (ionic)
 species. Therefore, waters with high salinities, or high total dissolved solids, can be
 expected to exhibit high conductivities. Variations in specific conductance within a
 stream reach or a portion of an impoundment may indicate the presence of
 contaminant release points.

 Major  Ion Chemistrv-The nature and prevalence of ionic  species may serve as
 indicators of pollution from waste sources containing inorganics.  Ions result from
 the dissociation of metal salts.  The cation (e.g., Na + , Ca + , Mg+ +) is typically a
 metallic species and the anion (e.g., CI-, $04--) a non-metallic species.
                                                                           i
     A common approach to use of ion chemistry as  an indicator of waste
 contamination in surface waters is to analyze for anions. Standard Methods
 (American Public Health Association, 1985), protocol no. 429 includes the following
 common anions as analytes:

          Chloride (CI-)
          Fluoride (F-)
          Bromide (Br-)
          Nitrate (NOs-)
          Nitrite (NO2-)
          Phosphate (PO4—)
          Sulfate (S04-)

     While elevated concentrations of these anions may indicate the presence of
inorganic constituents or other contaminants,  no information will  be provided
regarding the identity of specific constituents or contaminants.  In addition,
elevated levels of anions may  be associated with effluent from  domestic refuse
and/or runoff from fertilized agricultural fields.
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     The nature and concentrations of naturally-occurring ions in surface waters
are a function of the geologic setting of the area, and may be temporarily affected
by stormwater runoff, which may cause resuspension of streambed sediments.

     In  reference to their inertness with  respect to constituent and  biological
degradation, ionic species are termed "conservative." The fact that their mass is not
altered  (i.e., is conserved) in surface waters permits them to  be used in simple
dilution modeling.

13.4.3         Selection of Monitoring Locations

     The selection of monitoring locations should be addressed prior to sample
acquisition  because it may affect the selection of monitoring equipment  and
because monitoring locations will affect the representativeness of samples taken
during the monitoring program.  Samples must be taken at locations representative
of the water body or positions in the water body with specific physical or chemical
characteristics.   As discussed  in Section 13.4.1.2 (Development of Conceptual
Model), one of the most important  preliminary steps in  defining monitoring
locations in a surface water monitoring program is developing a conceptual model
of the manner in which the release is distributed within the  receiving water body.
This is dependent on the physical and chemical characteristics  of the receiving
water, the  point source or non-point source nature of the discharge,  and the
characteristics of the constituents themselves.

     As a practical example, if a release  contains contaminants  whose specific
gravities exceed that of water, it may behave almost as a separate phase within the
receiving water body, traveling along  the  bottom of the water body. As another
example, certain contaminants may be found in comparatively low concentrations
in  sediments or within the water column, yet may accumulate in aquatic biota via
bioaccumulation. In this case monitoring of the biota would be advised.  If the
facility owner or operator is unaware of these phenomena, it would be possible for
the monitoring program to show no evidence of contamination.

     In  general, it will be desirable to locate monitoring stations in three areas
relative to the discharge in question:
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Background monitoring stations:

Background monitoring should be performed in an area known not
to be influenced  by the release of concern (e.g., upstream of a
release).

Monitoring stations at the release point(s) or area:

If the release is a point source or area source, periodic monitoring
should be performed at monitoring stations near the discharge
origin to determine the range of contaminant concentrations.  The
contaminant stream (e.g.,  leachate seep, runoff) should also be
subjected to monitoring.

Monitoring of the receiving water  body within  the area of
influence:                                                   '
                                                            i
One means of evaluating the water quality effects of a discharge is
to monitor the discharge point and model its dispersion (e.g., using
dispersion zone concepts discussed previously) within the receiving
water body. The results of this modeling may be used to determine
appropriate sampling locations.  Actual sampling  of the area
thought to be influenced by the release is required.  The "area of
influence" may be defined as that portion of the receiving water
within which the  discharge would show a measurable effect.  As
described previously, the area to be sampled is generally defined in
a phased fashion, based on a growing base of monitoring data. It is
usually prudent to start with a conservatively large area  and
continually refine its boundaries.  This is particularly true  where
sensitive receptors (e.g., public water supply  intakes, sensitive
wetlands,  recreation areas)  lie downstream of the release.  In
addition, in order to determine the full extent of the release (and
its effects),  samples  should be taken at locations  beyond the
perceived area of influence.
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     The majority of the effort of the monitoring program will take place within
the area of influence, as defined  above.  Many factors are involved in selecting
monitoring stations within this area, the most critical being:

     •    The homogeneity of the water body in terms  of temperature, flow,
          salinity, and other physical and chemical characteristics;

     •    The representativeness of the monitoring point,  in terms of both
          contaminant characteristics and use factors;

     •    The presence of areas of pronounced water quality degradation;  and

     •    Defensible monitoring design, including the choice of the monitoring
          scheme (random, stratified random, systematic,  etc.), the experimental
          design, and adequate sample size determination.
                                                                           i

     Estuarine areas are  particularly difficult in terms of selecting monitoring
locations  that will  allow an adequate evaluation of  constituent distribution,
because detailed knowledge of the hydrologic characteristics of  the  estuary  is
required to accurately locate representative monitoring points.  Freshwater- salt
water stratification  is  a  particularly important consideration. If stratification  is
known to  occur or is suspected, sampling should be conducted at a range of depths
within the estuary as well as at surface locations.

     The selection of sampling locations is described in much greater detail in EPA
(1973,1982).

13.4.4         Monitoring Schedule

     The monitoring schedule or frequency should be a function  of the type of
release (i.e., intermittent vs continuous), variability in water quality of the receiving
water body (possibly as a result of other sources), stream flow conditions, and other
factors causing the release (e.g., meteorological or  process  design factors).
Therefore, frequency of monitoring should be determined  by the facility owner or
operator  on  a site-specific  basis.  Sampling points  with common monitoring
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objectives should be sampled as close to simultaneously as possible, regardless of
the monitoring frequency established.

     Factors important  in determining the required frequency of monitoring
include:

     •        The homogeneity of the receiving water in terms of factors that
              may affect the fate of constituents. The most important of these
              are flow and seasonal or diurnal stratification.

     •        The characteristics of the releases.  Releases may be continuous or
              event-associated.

     As an example, continuous, point source releases of low variability subject to
few, if any, additional releases may require relatively infrequent monitoring.  On
the other hand, releases known to be related to recurrent causes, such as rainfall'
and runoff, may require monitoring associated with the event. Such monitoring is
termed "event" sampling. To evaluate the threshold event required  to trigger
samplinn, as well as the required duration of the monitoring following the event, it
is necessary that the role of the event in creating a release from the unit be well
understood. In what is probably a very common example, if stormwater runoff is
the event of concern, a hydrograph for various storm return intervals and durations
should be estimated  for the point or  area of interest and the magnitude and
duration of its effects evaluated.

     Continuous monitoring can be accomplished through in situ probes that
provide frequent input to  field data storage  units.  However, continuous
monitoring is feasible only for the limited number of constituents and indicator
parameters for which reliable automatic sampling/recording equipment is available.

     In estuaries, samples are generally required through a tidal cycle. Two sets of
samples are taken from an area on a given day, one at ebb or flood slack water and
another at three hours earlier or later at half tide interval. Sampling is scheduled
such that the mid-sampling time of  each  run coincides  with  the calculated
occurrence of the tidal condition.
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     Where investigating discharges of contaminated ground water to streams or
rivers, it is important to sample during low flow conditions (e.g., using State critical
low flow designations) to  better assess the  possible  effects of the release(s)  of
concern.

13.4.5         Hydrologic Monitoring

     The monitoring  program should  also include provisions  for hydrologic
monitoring. Specifically, the program should provide  for collection of data on the
hydrologic condition of the surface water body at the time of sampling.

     For example, some indication of the stage and discharge of a stream being
monitored  needs to be recorded at the time and location each water sample is
collected.  Similarly, for sampling that occurs during storms, a record of rainfall
intensity over the duration of the  storm  needs to be obtained.  Without this
complementary hydroiogic data,  misinterpretation of the water  quality data in1
terms of contaminant sources and the extent of contamination is possible.

     The techniques for hydrologic  monitoring that could be  included in a
monitoring program range in complexity from use of simple qualitative descriptions
of streamflow to permanent installation of continuously-recording stream gages.
The techniques appropriate in a given case will depend on the characteristics of the
unit and of the surface waters  being investigated.  Guidance  on hydrologic
monitoring techniques can be found in the references cited in Section 13.6.1.

13.4.6         The Role of Biomonitoring

     The effects of contaminants may  be reflected  in  the population  density,
species composition and diversity, physiological condition, and metabolic rates of
aquatic organisms and communities.  Biomonitoring techniques  can provide an
effective complement to detailed  chemical analyses for identifying chemical
contamination of water bodies. They may be especially useful in those cases where
releases involve constituents with a high propensity to  bioaccumulate. This includes
most metal species and organicswith a high bioconcentration factor (e.g., > 10) or a
high octanol/water partition coefficient (e.g.,  .>2.3). These  properties  were
discussed in Section 13.3.
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     Biomonitoring techniques may include:

     •        Community ecology studies;
     •        Evaluation of food chain/sensitive species impacts; and
     •        Bioassays.

     These techniques are discussed below.

 13.4.6.1       Community Ecology Studies

     Indicator species are useful for evaluating  the well-being of an aquatic
 community that may be stressed by the release of contaminants. For example, the
 condition of the benthic macroinvertebrate community is commonly used as an
 indicator of the presence of contaminants. The objective of studying the naturally-
 occurring biological community is to determine community structure that would be'
 expected, in an undisturbed habitat. If significant changes occur, perturbations in1
 the community ecology may be linked to the disturbance associated with release of
 contaminants to the water bodv.

     EPA is engaged in research to develop rapid bioassessment techniques using
 benthic macroinvertebrates.  Although protocols are being considered, in general
 these techniques suffer from lack of data on undisturbed aquatic communities and
 associated water quality information.  For some areas (e.g., fisheries), however,
 indices to community health  based on benthic invertebrate communities are
 available (Hilsenhoff 1982, Cummins and Wilgbach, 1985).

     Because species diversity is a commonly-used indicator of the overall health of
 a community, depressed community diversity may  be considered an indicator of
 contamination.  For example, if a release to  surface waters has a high chemical
 oxygen  demand  (COD) and,  therefore, depresses oxygen  levels in the receiving
water body, the  number  of different species of organisms that can colonize the
water body may be reduced.  In this case the oxygen-sensitive species (e.g., the
mayfly), is lost from the community and is replaced by more tolerant species.  The
number of tolerant species is small, but the  number of individuals within these
species that can colonize the oxygen-deficient waters may be quite large. Therefore,
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the overall species diversity could be low, even though the numbers of organisms
may be high.

     Evaluations of community ecology should however, be sensitive to the role
that habitat variability may play in altering community structure.  Diversity  of
habitat  may be altered by natural physical conditions (e.g., a rapid  increase  in
stream gradient), substrate characteristics (e.g.,silty versus rocky substrate), and  so
forth. It  may also be difficult to directly link contaminant levels with the presence or
absence of aquatic organisms, unless there  is a secondary impact that is more self-
evident, such as high oxygen demand, turbidity, or salinity.

13.4.6.2        Evaluation of Food Chain Sensitive/Species Impacts

     At  this level of biomonitoring, the emphasis is actually on the threat to specific
fish or wildlife species, or man, as a result of bioaccumulation of constituents from
the release being carried through the food web. Bioaccumulative contaminants are'
not rapidly eliminated by biological processes and accumulate in certain organs or
body  tissues.   Their effect may not be felt by individual organisms that initially
consume the contaminated substrate or take up the contaminants from the water.
However, organisms at higher trophic levels consume the organisms of the lower
trophic  levels.  Consequently, contaminants may become bioaccumulated  in
organisms and biomagnified through the food web.

     Examination of the potential for bioaccumulation and biomagnification of
contaminants requires  at least a cursory characterization of the  community to
define its trophic structure, that is, which organisms occupy which relative positions
within the community.  Based on this definition, organisms  representative of the
various trophic levels may be collected, sacrificed, and analyzed to determine the
levels of the contaminants of interest present.

     If a specific trophic level is  of concern, it may be possible to short-cut the
process  by selectively collecting and analyzing organisms from that level for the
contaminants of concern.  This may be the case, for instance, if certain organisms
are taken by  man  either commercially or through recreational fishing, for
consumption.  It may also be necessary to focus on the prey of special-status fish or
wildlife  (e.g., eagles and other  birds of  prey) to establish their potential for
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 exposure.  This type of biomonitoring may be especially useful  if constituents
 released have a  relatively high  potential to bioaccumulate.  A discussion of
 indicators that are generally  predictive of constituents which have a significant
 potential for bioaccumulation was presented in Section 13.3.

     In addition, in the selection of organisms it is important to consider the ability
 of a given organism to accumulate a class of contaminants and  the residential vs
 migratory nature of the  organisms. For example, bullfrogs  are superior  for
 accumulating metals but poor  for organics; spawning (thus migratory)  salmon
 would be much less useful for  characterizing a release from a  local  facility than
 would resident fish.

 13.4.6.3       Bioassay

     Bioassay may be defined  as the study of specially selected  representative
 species to determine their response to the release  of concern, or to  specific*
 constituents of the release. The organisms are "monitored"  for a period  of timef
 established by the bioassay method. The objective of bioassay testing is to establish
 a concentration-response relationship between the contaminants  of concern and
 representative biota that can  be used  to evaluate the effects  of  the  release.
 Bioassay testing may involve the use  of indigenous organisms (U.S. EPA, 1973) or
 organisms available commercially for this purpose.  Bioassays have an advantage
 over strict constituent analyses of surface waters and effluents in that they measure
 the total effect of all constituents within the release on aquatic  organisms (within
 the limits of the test).  Such  results,  therefore, are  not as tightly constrained by
 assumptions of contaminant interactions.  Discussions of bioassay procedures are
 provided by Peltier and Weber (1985) and Horning and Weber (1985).

     The criterion commonly used to establish the endpoint  for a bioassay is
 mortality of the test organisms, although other factors such as depressed growth
 rate, reproductive success,  behavior  alteration, and flesh tainting  (in fish  and
shellfish) can be used.  Results are commonly reported as the LC50 (i.e., the lethal
concentration that resulted in  50 percent mortality of the test organisms within the
time frame of the test) or the EC50 (i.e., the effective concentration that resulted in
50 percent of the test organisms having an effect other than death  within the time
frame of the test).
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     One  potential  use of bioassays during the RFI  is to predict the effect  of a
release on sensitive species residing in the affected surface water(s).  Bioassay may
be especially useful if the release is intermittent.  In this case, samples of the waste
may be taken from  the unit of concern  and used to conduct bioassay tests. The
bioassay may be conducted using the waste at 100 percent strength, and in diluted
form, to obtain a concentration response relationship. The results of this testing
may then be used to predict the effects of a release on  the surface water biota.

     Bioassays can serve as important complements to the  overall monitoring
program.  In considering the role and design of bioassays in a monitoring program,
the facility owner or operator should be aware of the advantages and limitations of
toxicity testing. The study design must account for factors such as species sensitivity
and frequency of monitoring which may  be different from the considerations that
feed into chemical monitoring programs.  Toxicity testing techniques are an integral
part of the Clean Water Act program to control the discharge of toxic substances.
Many issues associated with toxicity testing have been addressed in this context in
the Technical Support Document for Water Quality-Based Toxics Control (Brandes et
al, 1985).

13.5 Data Management and Presentation

     The owner or operator will be required to report on the progress of the RFI at
appropriate intervals during  the investigation. The data should be reported in a
clear and concise manner, and interpretations should be supported by the data. The
following data presentation methods are suggested  for  the various phases of the
surface water investigation. Further information on the various procedures is given
in  Section 5.  Section 5 also  provides guidance  on various reports that may  be
required.

13.5.1         Waste and Unit Characterization

     Waste and unit characteristics should be presented as:

     •        Tables of  waste constituents, concentrations, effluent flow and
              mass loadings;
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     •         Tables of relevant physical  and chemical properties of potential
               contaminants (e.g., solubility);

     •         Narrative description of unit operations;

     •         Surface map and plan drawings of facility, unit(s), and surface
               waters; and

     •         Identification of "reasonable worst case" contaminant release to
               surface waters.

13.5.2          Environmental Setting Characterization

     The environment of the waste unit(s) and surface waters should be described
in terms of physical and biological environments in the vicinity. This description
should include:

     •         A map  of the area portraying the location of tr.e waste unit in
               relation to potential receiving waters;

     •         A map  or narrative classification of surface waters (e.g., type of
               surface water, uses of the surface water, and State classification, if
               any);
                              *
     •         A description of the  climatological setting as it may  affect the
               surface hydrology or release of contaminants; and

     •         A narrative  description of the hydrologic conditions during
               sampling periods.

13.5.3          Characterization of the Release

     The complex nature of the data involving  multiple monitoring events,
monitoring locations, matrices (water, sediment, biota), and analytes lends itself to
graphic presentation.  The most basic  presentation is a site map or series of maps
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that locate the monitoring stations for each monitoring event.  These maps may
also be adapted to include isopleths for specific analytes; however,  since the
isopleths imply a continuity within their borders, they may not be appropriate
unless they are based on an adequate number  of  monitoring  points and
representative data. The contours should be based on  unit intervals whose accuracy
ranges do not overlap.  In most situations, two separate  reporting formats are
appropriate.  First, the data should be included as tables.  These  tables should
generally be used to present the analytical results for a given sample.  Each table
could include samples from several locations for a given matrix, or could include
samples from each location for all sample matrices. Data from these tables can then
be summarized for comparison purposes using graphs.

     Graphs are most useful for displaying spatial and temporal  variations. Spatial
variability for a given analyte can be displayed using bar graphs where the vertical
axis represents concentration and the horizontal axis represents downstream
distance from the discharge. The results from each monitoring station can then be1
presented as a concentration bar. Stacked bar graphs can be used to display these
data from each matrix at a given location or for more than one analyte from each
sample.

     Similarly, these types of graphs can  be  used to demonstrate  temporal
variability if the  horizontal axis represents time rather than  distance.  In this
configuration, each graph will present the  results of one analyte  from a single
monitoring location. Stacked  bars can then display multiple analytes or locations.
Line graphs, like isopleths, should be used cautiously because  the line implies  a
continuity, either spatial or temporal, that may not be accurately supported by the
data.

     Scatter plots are useful for displaying correlations between variables. They can
be used to  support the validity of indicator parameters  by plotting the indicator
results against the results for a specific constituent.

     Graphs are used to display trends and correlations. They should not be used to
replace data tables, but rather to enhance the meaning of the data.
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13.6 Field and Other Methods

     The purpose of this section is to provide an overview of methods that can be
used to characterize the nature, rate, and extent of contaminant releases to surface
water. Detailed descriptions of specific methods can be found in the indicated
references.

     The methods presented in this section relate to four specific areas, as follows:

     •        Surface Water Hydrology;

     •        Sampling and Constituent  Analysis  of Surface Water,  Sediments,
              and Biota;

     •        Characterization of the Condition of the Aquatic Community; and
                                                                          I
     •        Bioassay Methods.

13.6.1         Surface Water Hydrology

     The physical attributes of the potentially affected water  body should be
characterized to effectively develop a monitoring program and to interpret results.
Depending on the characteristics of the release and the environmental setting, any
or all of the following hydrologic measurements may need to be undertaken.

     •   Overland flow:
              Hydraulic measurement;
              Rainfall/runoff measurement;
              Infiltration measurement; and
              Drainage basin  characterization (including  topographic
              characteristics,  soils and geology, and land use).

     •   Open channel flow:
              Measurement of stage (gaging activities);
              Measurement of width, depth, and cross-sectional area;
              Measurement of velocity;
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              Measurement of channel discharge;
              Measurement of channel discharge at controls (e.g., dams and
              weirs); and
              Definition of flow pathways - solute dispersion studies.

     •   Closed conduit flow:
              Measurement of discharge.

     •   Lakes and impoundments:
              Morphometric mapping;
              Bathymetric mapping;
              Temperature distributions; and
              Flow pathways.

     The following references provide descriptions of the measurements described
above.

     National Oceanic and Atmospheric Administration. Rainfall Atlas of the U.S.

     Viessman.etal., 1977. Introduction to Hydrology.

     USGS. 1977. National Handbook of Recommended Methods for Water-Data
     Acquisition Chapter 1 (Surface Water) and Chapter 7 (Physical  Basin
     Characteristics for Hydrologic Analyses).

     U.S Department of Interior.  1981. Water Measurement Manual. Bureau of
     Reclamation.  GPO No. 024-003-00158-9.  Washington, D.C.

     Chow. 1964.  Open Channel Hydraulics. McGraw-Hill. New York, N.Y.

     In addition, the following monographs in the Techniques of Water Resources
Investigations series of the  USGS (USGS-WSP-1822, 1982)  give the  reader more
detailed  information  on  techniques for measuring discharge and other
characteristics of various water bodies and hydrologic conditions:
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     Benson and Dalrymple. 1967. General Field and Office Procedures for Indirect
     Discharge Measurement.

     Bodhaine, 1968.  Measurement of Peak Discharge at Culverts  by  Indirect
     Methods. USGS-TWI-03-AS.

     Buchanan and Somers.  1968. Stage Measurements at Gaging Stations.

     Carter and Davidian.  1968. General Procedure for Gaging Streams. USGS-TWI-
     03-AL

13.6.2         Sampling of Surface Water, Runoff, Sediment, and Biota

13.6.2.1       Surface Water

     The means of collecting water samples is a function of the classification of the
water body, as discussed in Section 13.3.3.1. The following discussion treats lakes
and  impoundments separately  from streams and rivers although, as indicated
below, the actual sampling methods are similar in some cases.  Wetlands are
considered an tntergrade between these waters. Stormwater and snowmelt runoff
is also treated as a separate category (Section 13.6.2.2).  Although estuaries also
represent somewhat of an intergrade, estuary sampling methods are similar to
those for large rivers and lakes.

13.6.2.1.1      Streams and Rivers

     These  waters  represent a continuum from ephemeral  to  intermittent to
perennial. Streams and rivers may exhibit some of the same characteristics as lakes
and impoundments. The degree to which they are similar is normally a function of
channel configuration (e.g., depth, cross sectional area and discharge rate). Larger
rivers are probably more similar to most lakes and impoundments, with respect to
sampling methods, than to free-flowing headwater streams. In general, however,
streams and rivers exhibit a greater degree  of mixing due to their free-flowing
characteristics than can be achieved in lakes and impoundments.  Mixing and
dilution of inflow can be slow to fast, depending on the point of discharge to the
stream or river and the flow conditions.
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     Stream and river sampling methods do not differ appreciably from those
outlined in  the following section (Lakes and Impoundments).  However,  the
selection of monitoring stations  must consider additional factors created by
differential flow velocities within  the stream cross section. Strong currents and
turbulence as a result of channel configuration may affect the amount of mixing
and the distribution of contaminants in the stream. The reader may wish to refer to
the references provided in Section 13.3.1 for a discussion of the manner in which
differential velocities are handled in stream gaging studies to obtain representative
discharge measurements.

13.6.2.1.2      Lakes and Impoundments

     These waters are, by definition, areas where flow velocity is reduced, limiting
the circulation of waters from sources such as discharging streams or ground water.
They often include a shoreline wetland where water circulation is slow, dilution of1
inflowing contaminants is minimal, and sediments and plant life.become significant
factors in sampling strategies.  The deeper zones of open water may be vertically
stratified and subject to periodic turnover, especially in temperate  climates.
Sampling programs should be designed to obtain depth-specific information as well
as to characterize seasonal variations.

     Access to necessary monitoring stations may be impeded by both water depth
and lush emergent or floating aquatic vegetation, requiring the use of a floating
sampling platform or other means to appropriately place the sampling apparatus. It
is common to employ rigid extensions of monitoring equipment to collect surface
samples at distances of up to 30 or 40 feet from the shoreline.  However, a boat is
usually the preferred alternative for distances over about six feet.  A peristaltic
pump may also be used to withdraw water samples, and has the added advantage
of being able to extract samples to a depth of 20 to 30 feet below the surface.

     Many sampling devices are available in several materials.  Samples for trace
metals should not be collected in metal bottles, and samples for organics should not
be collected in plastic bottles.  Teflon or Teflon-coated sampling equipment,
including bottles, is generally acceptable for both types of constituents.  EPA (1982)
and EPA (1986) provide an analysis of the advantages and disadvantages of many
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sampling bottles for specific sampling situations. Detailed descriptions of the use of
dippers/transfer devices, pond samplers, peristaltic pumps, and  Kemmerer bottles
are provided by EPA (1984).

     Depth-specific samples in lake  environments are usually  collected with
equipment such as Kemmerer bottles (commonly constructed of brass), Van Dorn
samplers (typically of polyvinyl chloride or PVC construction), or Nansen tubes. The
depth-specific sample closure mechanism on these devices is tripped by dropping a
weight (messenger) down the line. Kemmerer bottles and Nansen tubes  may also
be outfitted with a thermometer that records the temperature of the water at the
time of collection.

13.6.2.1.3      Additional Information

     Additional information regarding specific surface water sampling  methods
may be found in the following general references:

     U.S. EPA. 1986. Methods for Evaluating Solid Wastes. EPA/SW-846.  GPO No.
     955-001-00000-1. Off ice cf Solid Waste.  Washington, D.C 20460.

     U.S. EPA.  1984. Characterization of Hazardous Waste Sites -- A  Methods
     Manual:  Volume II.  Available Sampling Methods. EPA-600/4-84-076. NTIS PB-
     168771. Washington, D.C. 20460.

     U.S. EPA.  1986. Handbook of Stream  Sampling  for Wasteload Allocation
     Applications. EPA/625/6-83/013.

     U.S. EPA. 1982. Handbook for Sampling and Sample Preservation of Water and
    Wastewater. NTIS PB 83-124503.

     USGS. 1977. National Handbook of Recommended Methods for Water-Data
    Acquisition.
I
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13.6.2.2        Runoff Sampling

     Runoff resulting from  precipitation  or  snowmelt creates an intermittent
release situation that requires special treatment for effective sampling.  The
contaminant release mechanism  in runoff situations may be overflow of ponds
containing contaminants or erosion of contaminated soils.  Based on an evaluation
of the waste characteristics and the environmental setting, the facility owner or
operator can determine whether waste constituents will be susceptible to this
release mechanism and migration pathway.

     Once it has been determined that erosion of contaminated soils is of concern,
the quantity of soil transported to any point of interest, such as the receiving water
body, can be determined through application of an  appropriate modification of the
Universal  Soil Loss Equation  (USLE).  The USLE was initially developed by the U.S.
Department of Agriculture,  Agricultural Stabilization and Conservation Service
(ASCS) to assist in the prediction  of soil loss from agricultural  areas. The initial'
formula is reproduced below:

                                A  = RKLSCP

where:

     A   =    Estimated annual average soil loss (tons/acre)
     R    =    Rainfall intensity factor
     K   =    Soil credibility factor
     L    =    Slope-length factor
     S    =    Slope-gradient factor
     C    =    Cropping management factor*
     P    =    Erosion control practice factor*

     *C and P factors can be assumed to equal unity in the equation if no specific
crop or erosion management practices are currently being employed. Otherwise,
these factors can be significantly less than unity,  depending on  crop or erosion
control practices.
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     Section 2.6 (Soil Contamination) of the Draft Super-fund Exposure Assessment
Manual (EPA, 1987) provides a discussion of the application of a modified USLE to
characterization of releases through soil erosion. This discussion is summarized in
Appendix H (Soil Loss Calculation).

     If the potential for a significant contaminant release exists, based on analysis
of the hydrologic situation and waste site characteristics, event samples should be
taken during high  runoff periods. In situations where high runoff is predictable,
such as spring runoff or the summer thundershower season,  automatic samplers
may be set to sample during these periods.  Perhaps the most effective way to
ensure sampling during significant events is to have personnel available to collect
samples at intervals throughout and following the storm.  Flow data should be
collected coincident with sample collection to permit calculation of contaminant
loading in the runoff at various flows during the period.  Automated sampling
equipment is available  that will  collect individual samples and composite them
either over time or with  flow amount, with the latter  being preferred.  Flow-1
proportional samplers are usually installed with a flow-measuring device, such as a
weir with a  continuous head recorder. Such devices are readily  available  from
commercial manufacturers and can be rented or leased.  Many facilities with an
NPDES discharge permit routinely use this equipment in compliance monitoring.

     Automated samplers are discussed in Section 8 of Handbook for Sampling and
Sample Preservation of Water and Wastewater (EPA. 1982) (NTIS PB 83-124503); this
publication also includes other references to automated samplers and a table of
devices available from various manufacturers.

13.6.2.3       Sediment

     Sediment is traditionally defined as the deposited material underlying a body
of water. Sediment is formed as waterborne solids (particulates) settle out of the
water column and build up as bottom deposits.

     Sedimentation is greatest in areas where the stream velocity decreases, such as
behind dams and flow control structures, and at the inner edge of bends in stream
channels. Sediments also build up where smaller, fast-flowing streams and runoff
discharge into larger streams and lakes. These areas can be important investigative
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areas. Some sections of a streambed may be virtually without sediments.  In some
streams or some areas of streams, water velocity may be too fast for sediments to
deposit and actually may scour the bottom, transporting material and depositing it
further downstream.  The stream bed in such an area will be primarily rocks and
debris.

     In some situations, such  as low-flow conditions, the overlying water
temporarily recedes, exposing sediments to the air.  Runoff channels, small lakes,
and small streams and  rivers may on occasion dry completely.  In  these cases,
samples can be collected using the same procedures described in the Soils section
(Section 9) of this document.

     For this discussion, the definition of sediment will be expanded to include any
material that may be overlain by water at any time during the year. This definition
then includes what may otherwise be considered submerged soils and  sludges.
Submerged soils are found in wetlands and marshes.  They may be located on the'
margins of lakes, ponds, and streams, or may be isolated features resulting from
collected  runoff, or may appear in areas where the ground-water table exists at or
very near the land surface. In any instance they are important investigative areas.

     Sludges are included for discussion here because many RCRA facilities use
impoundments for treatment or storage and these impoundments generally have a
sludge layer on the bottom.  Sampling these  sludges involves much the same
equipment and techniques as would be used for sediments.

     There are essentially two ways to collect sediment samples, either by coring or
with grab/dredges.  Corers are metal tubes with sharpened lower edges. The corer
is forced vertically into the sediment. Sediments are held in the core tube by friction
as the corer is carefully withdrawn; they can then  be transferred  to a sample
container. There are many types and modifications of corers available. Some units
are designed to be forced into the sediments by hand or hydraulic pressure; others
are outfitted with weights and fins and are designed to free fall through the water
column and are driven into the sediment by their fall-force.

     Corers sample a greater thickness of sediments than do grab/dredges and can
provide a profile of the sediment layers. However, they sample a relatively small
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surface area. Most corers are less than four inches in diameter and are more
commonly two inches in diameter.

     Grab/dredges are basically clamshell-type scoops that sample a larger surface
area but offer less depth of penetration. Typical grab/dredge designs are the Ponar,
Eckman,  and Peterson versions;  each has a somewhat different operating
mechanism and  slightly different advantages.  Some use spring force to close the
jaws while others are counter-levered like ice tongs.

     In sediment sampling, vertical profiling is not normally  required because
deposition of hazardous material is often a recent activity in terms of sedimentary
processes.  Grab/dredges that sample a  greater  surface area may be  more
appropriate than corers.  Similarly, shallow sludge layers contained in surface
impoundments should be sampled with grab/dredges because corer penetration
could damage the impoundment liner, if present. Thicker sludge layers which may
be present in surface impoundments, may be sampled using coring equipment if it is
important to obtain vertical profile information.

     Submerged soils are generally easier to sample with a corer, than with a
grab/dredge because vegetation and  roots can  prevent the grab/dredges from
sealing completely. Under these conditions, most of the sample may wash out of
the device as it is recovered. Corers can often be forced through the vegetation and
roots to provide a sample. In shallow  water, which may overlie submerged soils,
sampling personnel can wade through the water (using proper equipment and
precautions) and choose sample locations in  the small,  clear areas between
vegetative stems and roots.

     A wide variety of sampling devices are  available for  collection of sediment
samples. Each has advantages and disadvantages in a given situation, and a variety
of manufacturers produce different versions of the same device. As with  water
sampling, it is important to remember that metal samplers should not be used when
collecting samples  for trace metal analysis,  and sampling devices with  plastic
components should not be used when collecting samples for analysis of organics.

     The following references describe the availability and field use of sediment
samplers:
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     U.S. EPA.  1982.  Handbook for Sampling and Sample Preservation of Water
     and Wastewater.  Environmental  Monitoring and Support Laboratory,
     EPA-600/4-82-029. NTIS PB 83-124503.

     U.S. EPA. 1985. Methods Manual for Bottom Sediment Sample Collection. NTIS
     PB 86-107414.

     USGS. 1977, update June 1983. National Handbook of Recommended Methods
     for Water-Data Acquisition.

     U.S. EPA.  1984. Characterization of  Hazardous Waste  Sites - A Methods
     Manual: Volume II. Available Sampling Methods.  EPA-600/4-84-076.  NTIS PB
     85-168771.

13.6.2.4        Biota                                                        '

     Collection  of biota for constituent  analysis (whole body or tissue) may be
necessary to evaluate  exposure of aquatic  organisms or man  to  bioaccumulative
contaminants. For the most part, collection should be restricted to  representative
fish species and sessile macroinvertebrates, such  as mollusks.  Mollusks are filter-
feeders; bioaccumulative contaminants in the water column will be extracted and
concentrated in their tissues. Fish species  may be selected on the basis of their
commercial or recreational value, and their resultant probability of being consumed
by man or by special status-species of fish or wildlife.

     The literature on sampling  aquatic organisms is extensive.  Most sampling
methods include capture techniques that be collected using sampling bottles (as for
water samples) or nets of appropriate mesh sizes. Periphyton may  be most easily
collected by scraping off the substrate to  which the organisms are attached. Other
techniques using  artificial substrates are available if a quantitative  approach is
required.  Aquatic macroinvertebrates may be collected using a wide variety of
methods, depending on the area being sampled; collection by hand or using forceps
may be efficient. Grab sampling, sieving devices, artificial substrates and drift nets
may also be used effectively. EPA (1973) provides a discussion of these techniques,
as well as a method comparison and description of data analysis techniques.
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     Fish collection techniques may be characterized generally as follows (USGS,
 1977):

     •             Entangling gear:
                        Gill nets and trammel nets.
     •             Entrapping gear:
                        Hoop nets, basket traps, trap  nets,  and fyke and  wing
                        nets.
     •             Encircling gear:
                        Haul seine, purse seine, bay seine, and Danish seine.
     •             Electroshocking gear:
                        Boat shockers, backpack shockers, and electric seines.

Selection of sampling equipment is dependent on the characteristics of the water
body, such as size and conditions, the size of the fish to be collected, and the overall '
objectives of the study.  Fisheries Techniques (Nielsen and Johnson, 1983) and
Guidelines for Sampling  Fish in  Inland Waters (Backiel and Welcomme, 1980)
provide basic descriptions of sampling methods and data interpretation  from
fisheries studies.

13.6.3         Characterization of the Condition of the Aquatic Community

     Evaluation of the condition of aquatic communities may proceed from two
directions. The first consists of examining the structure of the lower trophic levels as
an indication of the overall health of the aquatic ecosystem.  With respect to RFI
studies, a healthy water body would be one whose trophic structure indicates that it
is not impacted by contaminants.  The second approach focuses on a particular
group or species, possibly because of its commercial or recreational importance or
because a substantial historic data base already exists.

     The first approach emphasizes the base  of the aquatic food chain, and may
involve studies of plankton (microscopic flora and fauna), periphyton (including
bacteria, yeast, molds, algae, and protozoa), macrophyton (aquatic  plants), and
benthic macroinvertebrates  (e.g., insects, annelid worms, mollusks, flatworms,
roundworms, and crustaceans). These lower levels of the aquatic community are
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studied to determine whether they exhibit any evidence of stress. If the community
appears to have been disturbed, the objective is to characterize the source(s) of the
stress and, specifically, to focus on the degree to which the release of waste
constituents has caused the disturbance or possibly exacerbated  an existing
problem. An example of the latter would be the further depletion of already low
dissolved oxygen levels in the hypolimnion of a lake or impoundment through the
introduction of waste with a high COD and specific gravity.

     The sampling methods referenced in Section 13.6.2.4 may be adapted (by
using them in  a quantitative sampling scheme) to collect the data necessary to
characterize aquatic communities. Hynes (1970) and Hutchinson (1967) provide an
overview of the ecological structure of aquatic communities.

     Benthic macroinvertebrates  are commonly used  in  studies of aquatic
communities. These organisms usually occupy a position near the base of the food
chain. Just as importantly, however, their range within the aquatic environment is
restricted, so that their community structure  may be referenced to a particular
stream reach or portion of lake substrate.  By comparison, fish are generally mobile
within the aquatic environment, and evidence of stress or contaminant load  may
not be amenable to interpretation with reference to specific releases.

     The presence or absence of particular benthic  macroinvertebrate species,
sometimes referred to as "indicator species," may provide evidence of a response to
environmental stress. Several references are available in this regard.  For more
information, the reader may consult Selected Bibliography on the Toxicology of the
Benthic Invertebrates and Periphyton (EPA. 1984).

     A "species diversity index" provides a quantitative measure of the degree of
stress within the aquatic community, and is an example  of a common basis for
interpretation of the results of studies of aquatic biological communities.  The
following equation (the Sannon-Wiener Index) demonstrates the concept of the
diversity index:
            s
     H  =  I  (PiMlogjPi)
                                   13-64

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where:

     H    ss   species diversity index
     s    =   number of species
     Pi    =   proportion of total sample belonging to the [th species

Measures of species diversity are most useful for comparison of streams with similar
hydrologic characteristics or for the analysis of trends over time within a  single
stream.  Additional  detail regarding  the application  of other measures of
community structure may be found in the following references:

     U.S. EPA. 1973.  Biological Field and Laboratory Methods for Measuring the
     Quality of Surface Water and Effluents.

     USGS. 1977, Update May,  1983.  National  Handbook  of Recommended
     Methods of Water-Data Acquisition.

     Curns, J. Jr., and K.L Dickson, eds.  1973. ASTMSTP528:  Biological Methods
     for the Assessment of Water  Quality.  American Society for Testing  and
     Materials. STP528.  Philadelphia, PA.

     The second approach to evaluating the condition of an aquatic community is
through selective sampling  of specific organisms, most commonly  fish,  and
evaluation of standard  "condition factors" (e.g., length, weight, girth).  In many
cases, receiving water bodies are recreational  fisheries,  monitored by state or
federal agencies. In such cases, it is common to find some historical record  of the
condition of the fish  population, and it may be possible to correlate operational
records at the waste management facility with alterations in the status of the fish
population.

     Sampling of fish populations to evaluate condition factors employs the same
methodologies referenced in Section 13.6.2.4. Because of the intensity of the effort
usually associated with obtaining a representative sample of fish, it is common to
coordinate tissue sampling for constituent analysis with fishery surveys.
                                   13-65

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13.6.4          Bioassay Methods

     The purpose of a bioassay, as discussed is more detail in Section 13.4.6.3, is to
predict the response of aquatic organisms  to  specific changes within the
environment.  In the RFI context, a bioassay may be used to predict the potential
adverse environmental effects of releases to surface water. Thus, bioassay  is not
generally considered to be an environmental characterization or monitoring
technique. As indicated below, bioassay may be required for Federal water quality
programs or state programs, especially where stream classification (e.g., warm-
water fishery, cold-water fishery) is involved.

     Bioassays may be conducted on  any aquatic  organism  including algae,
periphyton, macroinvertebrates, or fish.  Bioassay  includes two main techniques,
acute toxicity tests and chronic toxicity tests.  Each of these may be done in a
laboratory setting or using a mobile field laboratory. Following is a brief discussion
of acute and chronic bioassay tests.                                            .

Acute Toxicitv Tests-Acute toxicity tests are used in the NPDES permit program to
identify effluents containing toxic wastes discharged in toxic amounts. The data are
used to predict potential acute and chronic toxicity in the receiving water, based on
the LC50 and appropriate dilution, and application of persistence factors. Two types
of tests are used; static and flow-through. The selection of the test type will depend
on the objectives of the test, the available resources, the requirements of the test
organisms, and effluent characteristics.  Special environmental  requirements of
some organisms may preclude static testing.

     It should be noted that a negative result from  an acute toxicity test with a
given effluent sample does not preclude the presence of chronic toxicity, nor does it
negate the possibility  that the effluent may be acutely  toxic under different
conditions, such as variations in temperature or contaminant loadings.

     There are many sources of information relative to the performance of acute
bioassays. Methods for Measuring the Acute Toxicitv of Effluents to Freshwater and
Marine Organisms (Peltier and Weber, 1985) provides a comprehensive treatment
of the subject.
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Chronic Toxicitv Tests-Chronic toxicity tests may include measurement of effluent
effects on growth and reproductive success. These tests usually require long periods
of time, depending on the life cycles of the test organisms. Chronic bioassays are
generally relatively sophisticated procedures and are more intensive  in terms of
manpower, time and expense than are acute toxicity tests. The inherent complexity
of these tests dictate careful planning with the regulatory agency prior to initiation
of the work. Methods for Measuring the Chronic Toxicitv of Effluents to Aquatic
Organisms (Horning and Weber,  1985) is a  companion volume to the methods
document noted above, and contains method  references for chronic toxicity tests. A
discussion of bioassay procedures is also provided in Protocol for Bioassessment of
Hazardous Waste Sites, NTIS PB 83-241737. (Tetra Tech, 1983).

     Chronic toxicity tests are also used in the  NPDES permit program to identify
and control effluents containing toxic wastes in toxic amounts.
                                                                           i
13.7  Site Remediation                                                       I

     Although the RFI Guidance is not intended to provide detailed guidance on
site remediation, it should be recognized that certain data  collection activities that
may  be necessary for a Corrective Measures Study may be collected during the RFI.
EPA  has developed a practical guide for assessing and remediating contaminated
sites that directs users toward technical support, potential data requirements  and
technologies that may be applicable to EPA programs such as  RCRA and CERCLA.
The reference for this guide is provided below.

     U.S. EPA.  1988.  Practical Guide for Assessing and Remediating Contaminated
     Sites.   Office of Solid Waste and Emergency Response.  Washington, D.C.
     20460.

     The guide is designed to address releases to ground water as well  as soil,
surface water and air. A short description of the guide is provided in Section 1.2
(Overall  RCRA  Corrective Action Process),   under the discussion of Corrective
Measures Study.
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13.8 Checklist

                       RFI CHECKLIST - SURFACE WATER
Site Name/Location
Type of Unit
1.    Does waste characterization include the following information?      (Y/N)
     •    Constituents of concern                                    	
     •    Concentrations of constituents                             	
     •    Mass of the constituent                                    	
     •    Physical state of waste (e.g. .solid, liquid, gas)                	
     •    Water solubility                                          	
     •    Henry's Law Constant                                     	
     •    Octanol/Water Partition Coefficient (Kow)                    	
     •    Bioconcentration Factor (BCF)                              	
     •    Adsorption Coefficient (Koc)                               	
     •    Physical, biological, and chemical degradation               	

2.    Does unit characterization include the following information?        (Y/N)
     •    Age of unit                                              	
     •    Type of unit                                              	
     •    Operating practices                                       	
     •    Quantities of waste managed                              	
     •    Presence of cover                                         	
     •    Dimensions of unit                                        	
     •    Presence of natural or engineered barriers                   	
     •    Release frequency                                        	
     •    Release volume and rate                                  	
     •    Non-point or point source release                           	
     •    Intermittent or continuous release
                                   13-68

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                 RFI CHECKLIST - SURFACE WATER (Continued)
3.    Does environmental setting information include the following?      (Y/N)

     •   Areal extent of drainage basin                             	
     •   Location and interconnection of all streams, lakes            	
         and other surface water features
     •   Flow identification as ephemeral, intermittent or perennial    	
     •   Channel alignment, gradient and discharge rate             	
     •   Flood and channel.control structures                       	
     •   Source of lake and impoundment water                    	
     •   Lake and impoundment depths and surface area             	
     •   Vertical temperature stratification of lakes and impoundments	
     •   Wetland presence and role in basin hydrology               	
     •   NPDES and other discharges                               	
     •   USGS gaging stations or other existing flow monitoring systems	
     •   Surface water quality characteristics                        	
     •   Average monthly and annual precipitation values            	
     •   Average monthly temperature                             	
     •   Average monthly evaporation potential estimates            	
     •   Storm frequency and severity                             	
     •   Snowfall and snow pack ranges                           	
4.    Have the following data on the initial phase of the release
     characterization been collected?                                 (Y/N)
     •   Monitoring locations                                    	
     •   Monitoring constituents and indicator parameters           	
     •   Monitoring frequency                                   	
     •   Monitoring equipment and procedures                     	._
     •   Concentrations of constituents and locations                	
         at which they were detected
     •   Background monitoring results                            	
                                  13-69

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                 RFI CHECKLIST-SURFACE WATER (Continued)
                                                                  (Y/N)
     •    Hydrologic and biomonitoring results                       	
     •    Inter-media transfer data                                  	
     •    Analyses of rate and extent of contamination   .             	
5.    Have the following data on the subsequent phase(s) of the release
     characterization been collected?                                 (Y/N)
     •   New or relocated monitoring locations                      	
     •   Constituents and indicators added or deleted for monitoring   	
     •   Modifications to monitoring frequency, equipment           	
         or procedures
     •   Concentrations of constituents and locations at which         	
         they were detected
     •   Background monitoring results                            	
     •   Hydrologic and biomonitoring results                      	
     •   Inter-media transfer data                                  	
     •   Analyses of rate and extent of contamination                	
                                   13-70

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13.9 References

American Public  Health Association, (APHA).  1985.  Standard Methods for the
     Examination of Water and Wastewater.  16th Edition. American Public Health
     Association, Washington, D.C.

Backiel,T.,and R. Welcomme. 1980. Guidelines for Sampling Fish in Inland Waters.
     EIFAC  Technical  Paper No. 33.  Food and Agriculture Organization of the
     United Nations, Rome, Italy.

Benson, M.A., and T. Dalrymple.  1967.  General Field and Office Procedures for
     Indirect   Discharge  Measurement.    Techniques  of  Water  Resources
     Investigations series.  U.S. Geological Survey, Reston, VA.

Bodhaine, G. L  1968.  Measurement of Peak Discharge at  Culverts by Indirect.
     Methods. Techniques of Water Resources Investigations Series. U.S. Geological i
     Survey, Reston, VA.

Brandes, R., B. Newton, M. Owens, and E. Southerland.  1985. The Technical Support
     Document for Water Quality-Based Toxics Control.  EPA-440/4-85-032. Office
     of Water Enforcement and Permits. Washington, D.C. 20460.

Buchanan, T. J., and W. P. Somers. 1968. Stage Measurement at Gaging Stations.
     Techniques  of Water Resources  Investigations Series. U.S. Geological Survey,
     Reston, VA.

Cairns, J. Jr., and K. L. Dickson, eds.  1973. Biological Methods for the Assessment of
     Water Quality (STP 528).   American  Society for Testing and  Materials,
     Philadelphia, PA.

Callahan, M., M. Slimak, N. Gabel, I. May, etal. 1979. Water-Related Environmental
     Fate of 129 Priority Pollutants.  Volumes  I  & II.   EPA  440/4-79-029a/b.
     Monitoring  and Data Support  Division. NTIS 029A/80-204373  and 029B/80-
     204381.Washington, D.C. 20460.
                                  13-71

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Carter, R. W., and J. Davidian.  1968. General  Procedure for Gaging Streams.
     Techniques of Water Resources Investigations Series.  U.S. Geological Survey,
     Reston, VA.

Chow, V.T.  1964. Open-Channel Hydraulics. McGraw-Hill. New York, NY.

Cole, G. A. 1975. Textbook of Limnology. The C. V. Mosbv Company. St. Louis. MO.

Cowardin, L M., V. Carter, F. C.  Golet, and E. T. Laftoe.   1979.  Classification of
     Wetlands and Deepwater Habitats of the United States. U.S. Fish  & Wildlife
     Service. NTIS PB 80-168784. Washington, D.C.

Cummins, K. W. and N. A. Wilgbach.  1985.  Field Procedures for Analysis of
     Functional Feeding GroUPS of Stream Macroinvertebrates. Contribution 1611.
     Appalachian Environmental Laboratory, University of Maryland.
                                                                        i
Hilsenhoff, W. L 1982.  Using a Biotic Index to Evaluate Water Quality in Streams.1
     Technical Bulletin No. 132. Department of Natural Resources. Madison, Wl.

Horning, W., and C. I. Weber. 1985. Methods for Measuring the Chronic Toxicitv of
     Effluents to Aquatic Organisms.   U.S.  EPA, Office of Research  and
     Development. Cincinnati, OH.

Hutchinson, G. E.  1957. A Treatise on Limnology: Volume I. Geography. Physics,
     and Chemistry. John Wiley & Sons, Inc. New York, NY.

Hutchinson, G. E.  1967.  A Treatise on Limnology: Volume  II. Introduction to Lake
     Biology and Limnoplankton. John Wiley & Sons, Inc. New York, NY.

Hynes, H.  B. N. 1970. The Ecology of Running Waters. University of Toronto Press.
     Toronto, Ontario.

Lyman, W. J., W. F. Riehl, and D. H. Rosenbaltt. 1982.  Handbook of Chemical
     Property Estimation Methods. McGraw-Hill.  New York, NY.
                                  13-72

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Mabey, W.( and T. Mill. 1978.  "Critical Review of Hydrolysis of Organic Compounds
     in Water Under  Environmental Conditions."  Journal of Environmental
     Chemistry. Vol. 7, No. 2.

Mabey, W. R., J. H. Smith, R. T. Podall, et al. 1982.  Aquatic Fate Process Data for
     Organic Priority Pollutants. EPA 440/4-81-014. Washington, D.C. 20460.

Mills, W. B.,  1985. Water Quality Assessment: A Screening Procedure for Toxic and
     Conventional  Pollutants in  Surface and Ground Water:  Parts  land 2.  EPA
     600/6-85-002, a, b. NTIS PB 83-153122 and NTIS PB 83-153130. U.S. EPA, Office
     of Research and Development. Athens, GA.

National Oceanic and Atmospheric Administration. Rainfall Atlas of the U.S.

Neely,  W.  B.  1982. "The Definition and Use of Mixing Zones".  Environmental
     Science and Technology 16(9): 520A-521 A.                                i
                                                                         t
Neely, W. G., and G. E. Blau, eds.  1985.  Environmental  Exposure from Chemicals.
     Volume I. CRC Press. B jca Raton, FL

Nielsen, L A., and D. L Johnson, eds.  1983.  Fisheries Techniques.  The American
     Fisheries Society. Blacksburg, VA, 468 pp.

Peltier, W. H., and C. I. Weber.  1985.  Methods for Measuring the Acute Toxicitv of
     Effluents to Freshwater and Marine Organisms.  EPA 600/4-85/013. NTIS PB 85-
     205383. U.S.EPA, Environmental Monitoring and Support Laboratory, Office
     of Research and Development. Cincinnati, OH.

Stumm, W. and J. J. Morgan.  1982.  Aquatic Chemistry.  2nd Edition.  Wiley
     Interscience. New York, NY.

TetraTech. 1983.  Protocol for Bioassessment of Hazardous Waste Sites.  U.S.  EPA.
     NTIS PB 83-241737. Washington, D.C. 20460.

U.S. Department Of Interior.   1981.  Water Measurement Manual.   Bureau of
     Reclamation. GPO No. 024-003-00158-9. Washington, D.C.
                                  13-73

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U.S. EPA.  1973. Biological Field and Laboratory Methods for Measuring the Quality
     of Surface Water and Effluents.  EPA-67014-73-001.  Office of Research and
     Development. Washington, D.C. 20460.

U.S. EPA.  1982. Handbook for Sampling and Sample Preservation of Water and
     Wastewater. Environmental Monitoring and Support Laboratory. EPA-600/4-
  .   82-029. NTIS PB 83-124503. Washington, D.C.

U.S. EPA.  1984. Characterization of Hazardous Waste Sites - A Wetlands Manual-
     Volume II - Available Sampling Methods.   EPA-600/4-84-076.  NTIS PB 85-
     168771. Washington, D.C. 20460.

U.S.  EPA.   1984.  Selected Bibliography on the Toxicology of the Benthic
     Invertebrates and Periphyton.  Environmental  Monitoring and Support
     Laboratory. NTIS PB 84-130459.                                        '
                                                                       I
U.S. EPA.  1985.  Methods Manual for Bottom Sediment Sample Collection. NTIS
     PB86-107414. Washington, D.C. 20460.

U.S.  EPA.   1987. Draft Superfund Exposure Assessment Manual.  Office of
     Emergency and Remedial Response. Washington, D.C. 20460.

U.S. EPA.  1986.  Test Methods for Evaluating Solid Waste.  EPA/SW-846.  GPO
     No.9 55-001-00000-1. Officeof Solid Waste. Washington, D.C. 20460.

U.S.  EPA.   1986. Handbook of Stream  Sampling for Wasteload Allocation
     Applications. EPA/625/6-83/013.

USGS.  1977.  National Handbook  of Recommended  Methods for Water-Data
     Acquisition. U.S. Geological Survey. Office of Water Data Coordination. U.S.
     Government Printing Office. Washington, D.C.

Veith, G., Macey, Petrocelli and  Carroll.   1980.  An  Evaluation of Using
     Partition.Coefficients and  Water Solubility  to  Estimate Biological
                                 13-74

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     Concentration Factors for Organic Chemicals in Fish. Proceedings, ASTM 3rd
     Symposium on Aquatic Toxicity. ASTM STP 707.

Viessman, W., Jr., W. Knapp. G. L Lewis, and T. E. Harbaugh. 1977. Introduction to
     Hydrology. 2nd Edition. Harper and Row, Publishers, New York, NY.
                                  13-75

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                APPENDIX G





AIR RELEASE SCREENING ASSESSMENT METHODOLOGY

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        DRAFT FINAL
        (Revised)
     AIR RELEASE
SCREENING ASSESSMENT
    METHODOLOGY
        MAY 1989

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                          TABLE OF CONTENTS
   Section                          Title
     1.0      Introduction                                           1-1
     2.0      Screening Methodology                                 2-1
              2.1 Overview                                        2-2
              2.2 Step 1 -SourceCharacterization Information         2-5
              2.3 Step 2 - Release Constituent Surrogates              2-7
              2.4 Step 3 - Emission Estimates                         2-9
              2.5 Step4-Concentration Estimates                    2-14
              2.6 Step 5 - Health Criteria Comparisons                 2-17
     3.0      Example Applications                                   3-1
              3.1 Case Study A                                     3-1
              3.2 Case Study B                                     3-6
     4.0      References                                            4-1
                                                                       l

Appendix A   Background Information
Appendix B   Release Constituent Surrogate Data
Appendix C   Emission Rate Estimates - Disposal Impoundments
Appendix D   Emission Rate Estimates - Storage Impoundments
Appendix E   Emission Rate Estimates - Oil Films on Storage
             Impoundments
Appendix F   Emission Rate Estimates - Mechanically Aerated
             Impoundments
Appendix G   Emission Rate Estimates - Diffused Air Systems
Appendix H   Emission Rate Estimates - Land Treatment (after tilling)
Appendix I    Emission Rate Estimates - Oil Film Surfaces on Land
             Treatment Units
Appendix J    Emission Rate Estimates - Closed Landfills
Appendix K   Emission Rate Estimates - Open Landfills
Appendix L   Emission Rate Estimates - Wastepiles
Appendix M   Emission Rate Estimates - Fixed Roof Tanks
Appendix N   Emission Rate Estimates- Floating Roof Tanks

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                     TABLE OF CONTENTS (Continued)
  Section                          Title
Appendix O   Emission Rate Estimates - Variable Vapor Space Tanks
Appendix P   Emission Rate Estimates - Particles from Storage Piles
Appendix Q   Emission Rate Estimates - Particles from Exposed, Flat,
             Contaminated Areas
Appendix R   Dispersion Estimates
Appendix S   Emission Rate Estimation Worksheets
                                   HI

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                           LIST OF FIGURES
Number                                                         Page
  2-1     Screening Methodology Overview                        2-3
  2-2     Step 1 - Obtain Source Characterization Information         2-6
  2-3     Step 2-Select Release Constituents and Surrogates          2-8
  2-4     Step 3 - Calculate Emission Estimates                      2-10
  2-5     Step 3 - Calculate Emission Estimates (Alternative          2-11
          Approach)
  2-6     Step4-CalculateConcentration Estimates                2-15
  2-7     Step 4 - Calculate Concentration Estimates (Alternative     2-16
          Approach)
  2-8     Step 5-Compare Results to Health-Based Criteria          2-18
                           LIST OF EXHIBITS
Number
  2-1     Ratio of Scaling Estimates to CHEMDAT6 Emission Rate
          Modeling Results
  3-1     Table S-2 Emission Rate Estimation Worksheet - Storage
          Impoundment
  3-2     Table R-1 Concentration Estimation Worksheet - Unit
          Category: Storage Impoundment
  3-3     Table S-8 Emission Rate Estimation Worksheet - Closed
          Landfills
  3-4     Table S-8 Emission Rate Estimation Worksheet - Closed
          Landfill
  3-5     Table R-1 Concentration Estimation Worksheet - Unit
          Category: Closed Landfill
  3-6     Table R-1 Concentration Estimation Worksheet - Unit
          Category: Closed Landfill
2-20

 3-2

 3-5

 3-8

 3-9

3-10

3-11
                                 IV

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1.0       INTRODUCTION

A screening method has been developed for evaluating which waste management
units have air releases warranting  further investigation under a RCRA  Facility
Investigation (RFI). This method can be used as an intermediate step between the
general qualitative determination of the RCRA Facility Assessment (RFA) regarding
identification of air emissions that warrant an RFI, and the actual performance of a
complicated and costly RFI.  Specifically, this screening methodology provides a basis
for identifying air releases with the potential to have resulted in off-site exposures
that meet or exceed health-based criteria in the RFI Guidance.

This screening methodology has been developed as a technical aid for routine use
by EPA Regional and State staff who  may not  be familiar with  air  release
assessments.  However, it should also be considered a resource available to prioritize
waste management units which may warrant the  conduct of an RFI for  the  air
media.   Alternative  resources (e.g.,  available  air monitoring  data, more
sophisticated modeling analyses, judgmental factors) may also provide important
input to the RFI decision-making process.

The screening methodology itself is explained in Section 2 and example applications
of it are  presented  in Section  3. A discussion  of  background information that
addresses the technical basis for the air release screening methodology is presented
in Appendix A.
                                    1-1

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2.0       SCREENING METHODOLOGY

This  section presents the air  release screening  assessment methodology.   This
methodology can  be used  as a transition between the  general  qualitative
determination made in the RFA regarding air emissions that warrant an RFI, and the
actual performance of an RFI.

The  primary  (recommended)  screening approach  involves  the application of
available emission rate models and dispersion models.  An alternative approach
involves the use of technical aids based on scaling  modeling results for a limited set
of source scenarios.

The  screening  methodology  for  releases  of organics  is based  on  using the
CHEMDAT6 air emission models, available from EPA's Office of Air Quality Planning
and Standards (OAQPS), (U.S. EPA, December 1987).  Specifically, the following unit
categories are directly addressed in this section:

     •    Disposal impoundments
     •    Storage impoundments
     •    Oil Films on Storage Impoundments
     •    Mechanically Aerated Impoundments
     •    Diffused Air Systems
     •    Land treatment (emissions after tilling)
     •    Oil Film Surfaces on Land Treatment Units
     •    Closed landfills
     •    Open landfills
     •    Wastepiles

The alternative approach presented in this section  involves scaling the emission rate
results from numerous source scenarios that have been modeled using CHEMDAT6.
These scaling computations can become tedious if numerous  source scenarios are
evaluated.  In addition,  the direct use of CHEMDAT6 models will provide more
representative   unit-specific  emission  estimates.    Therefore,  it  is   strongly
recommended that EPA Regional and State agency staff develop a capability to use
CHEMDAT6  directly  to model  unit-specific  and  facility-specific  scenarios.
                                   2-1

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CHEMDAT6 has  been developed for use on  a  microcomputer using  LOTUS
spreadsheet software; therefore, these models can easily be used by staff familiar
with LOTUS applications.  However, the basic strategy described in this section to
estimate ambient concentrations can still  be successfully used even without using
LOTUS.

The screening methodology for organic emissions from storage tanks is based  on
emission factors in  EPA's AP-42, "Compilation of Air Pollutant Emission Factors"
(U.S. EPA, September 1985). The following categories of tanks are addressed:

     •    Fixed roof tanks
     •    Floating roof tanks
     •    Variable vapor space tanks.

Open tanks should be  assessed using the methodology for storage impoundments.
                                                                        i

The screening methodology for particulate matter releases from wind  erosion of
storage piles and batch dumping and loader activity on the pile is based on emission
factors in EPA's AP-42 (U.S. EPA, September 1985). The screening methodology for
particulate matter releases from wind erosion of flat,  exposed,  contaminated
surface  areas is based  on emission factors in  EPA's "Fugitive Emissions from
Integrated  Iron and Steel Plants" (U.S. EPA, March  1978).  The  EPA-OAQPS is
currently developing  guidance  regarding particulate emissions for treatment,
storage, and disposal facilities.

2.1        Overview

The air release screening assessment methodology involves applying emission rate
and dispersion results to estimate long-term ambient concentrations at receptor
locations for comparison to health-based criteria. The methodology consists of five
steps as follows (see Figure 2-1):

     •    Step 1  - Obtain Source Characterization Information: This information
          (e.g., unit size, operational schedule) is needed to define the emission
          potential of the specific unit.
                                   2-2

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             FIGURE 2-1
SCREENING METHODOLOGY OVERVIEW


               RFA
               1
               Stem

           Obtain Source
          Characterization
            Information
              Step 2

           Select Release
          Constituents and
            Surrogates
            Calculate
        Emission Estimates
              Step 4
      Calculate Concentration
            Estimates
              StepS

        Compare Results to
       Health-Based Criteria
               1
             Input to
        Decision on Need for
           RFI-Air Media
                2-3

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     •    Step  2-  Select  Release  Constituents and Surrogates:   The primary
          approach involves using the actual physical/chemical properties  for all
          unit-specific  constituents  for emission  modeling  purposes.    The
          alternative (scaling) screening approach uses a limited set of constituents
          or surrogates to represent a wide range of potential release constituents.
          This surrogate approach significantly simplifies the screening assessment
          process.

     •    Step 3 - Calculate Emission Estimates: The primary approach involves the
          use of emission rate  models based on  unit-specific source conditions.
          Modeling results of emission rates for a wide range of source conditions
          are also presented in  Appendices C through Q.  As an alternative
          approach, these  modeling results can be interpolated to estimate an
          emission rate specific to the unit.
                                                                          i
     •    Step 4 - Calculate Concentration Estimates:  Emission rates from  Step 3
          are used to calculate concentration estimates at receptor locations  of
          interest.  The primary approach involves the application of dispersion
          models  based  on site-specific  meteorological  conditions.    As an
          alternative approach, dispersion conditions are accounted for by use  of
          modeling  results  available   in  Appendix  R  for   typical  annual
          meteorological conditions.

     •    Step  5 - Compare Concentration Results to  Health-Based  Criteria:
          Concentration  results from Step 4 can  be compared to constituent-
          specific health-based criteria provided in the RFI Guidance.

For some applications, Step 4 (Calculate Concentration Estimates) will not warrant
the use of emission models because it can be assumed that all the volatile  wastes
handled  will eventually  be emitted  to  the air.   This assumption is generally
appropriate for highly volatile organic compounds placed in a disposal unit like a
surface impoundment.  In these cases, the air emission rate can be assumed to be
equivalent to the disposal rate, so that an emission rate model may not be required.
This assumption  is valid because of the long-term  residence time  of wastes in the
disposal units. In open units like surface impoundments, a substantial portion  of
the volatile constituents will frequently be released to the  atmosphere  within
                                    2-4

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several days.  However, for  more complex situations (e.g., storage or treatment
units where total volatilization of the constituents is not expected), air emission
models can be used to obtain a more refined long-term release rate.

Results from  the air release screening  assessment, using the above steps, will
provide input to decisions on the need for an RFI for the air media.  They can also be
used to prioritize air emission sources at a facility (i.e., by identification of the major
onsite air emission sources)  as well as to prioritize the total release potential  at
candidate facilities.

2.2       Step  1 • Source Characterization Information

Implementation of the air  release  screening  assessment  methodology involves
collecting  source  characterization  information,  as  illustrated  in  Figure  2-2.
Specifically, this involves completion of Column  2 of  unit-specific  Emission Rate
Estimation Worksheets (included  in  Appendix  S) as specified  in  Figure  2-2.
Parameters in Column  2 of the worksheet represent standard input used by the
CHEMDAT6 air emission models or input to the AP-42 emission equations. Source
characterization information should be available  from the RFA but it may be
necessary to request additional information from the facility owner or operator on
an ad hoc basis.

Additional worksheets should be completed for each unit to be evaluated. Similar
units can be grouped together and considered as one area source to simplify the
assessment process. For example, several contiguous landfills of similar design could
be evaluated efficiently as one (combined) source.

Completeness and quality of the source  characterization  information are very
important and,  as previously stated, directly affect the  usefulness of the screening
assessment results.   Certain source characterization parameters are considered
critical  inputs to the screening assessment.  These critical  input parameters are
needed to define the total mass of constituents in the waste input to the unit being
evaluated or the potential for release of particles less than 10 microns.  These
parameters have been identified in the unit-specific worksheet (Tables S-1 through
S-13 for VO sources and Tables S-14 and 15 for participate sources).
                                    2-5

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                              FIGURE 2-2
        STEP 1 - OBTAIN SOURCE CHARACTERIZATION INFORMATION
                                 RFA
Complete Column 2 of Unit-Specific Emission Rate Estimation Worksheet:
•  Disposal impoundment - Table S-1
•  Storage impoundment/open tank-
   Table S-2
•  Oil film on storage impoundment -
   Table S-3
•  Mechanically aerated impoundment
   Table S-4
•  Diffused air system - Table S-5
•  Land treatment (emissions after
•  tilling)- Table S-6
•  Oil film surface on land treatment
   unit-Table S-7
Closed landfill-TableS-8
Open landfill-TableS-9
Wastepile- Table S-10
Fixed roof tank - Table S-11
Floating roof tank-Table S-12
Variable vapor space tank -
Table S-13
Storage pile (participates) -
Table S-14
Exposed, flat, contaminated area
(particulates)TableS-15
   Complete Column 2 of additional worksheets for each unit to be evaluated
              (similar units can be grouped as one area source).
Select typical and/or reasonable worst-case values specified in Appendices C-M if
values for input parameters are not available.
   Disposal impoundment - Table C-1
   Storage impoundment/open tank-
   Table D-1
   Oil film on storage impoundment -
   Table E-1
   Mechanically aerated impoundment -
   Table F-1
   Diffused air system - Table G-1
   Land treatment (emissions after
   tilling)-Table H-1
   Oil film surface on land treatment
   unit-Table 1-1
Closed landfill-Table J-1
Open landfill-Table K-1
Wastepile-Table L-1
Fixed roof tank-Table M-1
Floating roof tank -Table N-1
Variable vapor space tank -
   Table p-1
Storage pile (particulates)-
Table P-1
Exposed, flat, contaminated area
(particulates)- Table Q-1
                                   T
                                 Step 2-

                      Select Release Constituents and
                               Surrogates
                                  2-6

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Unit-specific values for some of the source characterization  parameters may be
difficult to determine.  For example, air porosity values of the fixed waste are
needed for  evaluating  emissions from  open  landfills,  closed  landfills,  and
wastepiles, and total  porosity values of the fixed waste are  needed to evaluate
emissions  from open  landfills and wastepiles.  However,  unit-specific data are
typically  not available for these  parameters.   If unit-specific values for input
parameters are not available, typical and/or reasonable worst-case values should be
selected from the range of values specified in Appendices C through Q.

Selection of source scenario input  data should be based on realistic physical and
chemical limitations. For example, the waste concentration value for a constituent
should not exceed the constituent-specific solubility in water.

2.3       Step 2 • Release Constituent Surrogates

The primary approach involves using the actual physical/chemical properties for all
unit-specific  constituents for emission  modeling purposes.   The  alternative
screening approach (scaling) uses a limited set of constituents or surrogates.

A limited set of surrogates is used to represent the constituents of concern in this
alternative screening  method to  represent a wide range  of potential  release
constituents. This significantly simplifies the screening assessment process since the
list of potential air release constituents included in the RFI Guidance is extensive.
Selection of  appropriate  source release constituent surrogates is illustrated in
Figure 2-3.  Table B-3 presents the appropriate surrogate to  be used for each
constituent of concern. This step is not used in screening for particle emissions from
storage piles and exposed areas.

Table B-3 of Appendix B, presents  the appropriate surrogate  to be used for each
constituent of concern. Two subsets of surrogates are presented in Appendix B. The
first subset is applicable to emissions that can be estimated  based on Henry's Law
Constant (i.e., applicable for low concentrations,  less than 10 percent, of wastes in
aqueous solution). Surrogates based on  Henry's Law Constant are appropriate for
units like storage and disposal impoundments. Henry's Law Constant surrogates are
presented in Table B-1.
                                    2-7

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                            FIGURE 2-3
      STEP 2 - SELECT RELEASE CONSTITUENTS AND SURROGATES

                 Source Characterization Information
         Impoundments
        (Organic Releases)
                            Select
                          appropriate'
                          surrogate
                            subset.
   Other Units
(Organic Releases)
Surrogate subset
based on Henry's
Law Constant (see
   Table B-1)
                      Paniculate Releases
                                                 Surrogate subset
                                                 based on Raoult's
                                                Law (see Table B-2)
                               Select
                             appropriate
                           constituents to
                              represent
                               release.
                                           Alternative Approach
Primary Approach
 Use all constituents to
    evaluate unit.
                                          Limit evaluations to release
                                         constituent(s) that represent
                                            reasonable worst-case
                                                 conditions.
                                              Identify surrogates which
                                               correspond to release
                                                   constituents
                                                    (Table B-3).
                               Step 3-

                              Calculate
                          Emission Estimates
                                2-8

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The second subset is applicable to emissions that can be estimated based on Raoult's
Law.  Raoult's Law predicts the behavior of most concentrated mixtures of water
and organic solvents (i.e., solution with over 10 percent solute).  Surrogates based
on Raoult's Law are appropriate for units like landfills, wastepiles, land treatment
units and storage tanks. Raoult's Law surrogates are listed in Table B-2.

It is also necessary to select surrogates from the appropriate subset (i.e., from the
Henry's Law Constant or  Raoult's  Law  subset  selected) to represent  release
constituents  of interest. The  primary approach is to use all  surrogates from the
appropriate  subset  to  evaluate the  unit.   This  approach  will  provide  a
comprehensive data base for the screening assessment.  An alternative approach is
to select release constituent(s)/surrogate(s) that represent reasonable worst-case
conditions.  Release constituents having the most restrictive health-based criteria
and those having high volatility are frequently associated with these reasonable
worst-case (long-term) release conditions.
                                                                          i
2.4       Step 3 • Emission Estimates

Two approaches for calculating emission estimates are identified in Figure 2-4. The
primary approach involves the calculation of unit-specific emission rates based  on
available models (e.g.,  CHEMDAT6, et cetera).  This approach is recommended for
most applications.

The alternative approach involves the calculation  of emissions by applying scaling
factors to emission modeling results presented in Appendices C  through Q for a
limited  set of  source  scenarios.   This  approach is appropriate when a rapid
preliminary estimate is needed and modeling resources are not available.  However,
the primary  approach  will  provide more representative unit-specific emission
estimates.

Specific instructions for implementing the alternative emission estimation approach
are presented in Figure  2-5.

Emission rate modeling results for a wide range of source scenario conditions are
presented in  Appendices C through   Q  to  facilitate implementation  of  the
alternative emission estimation approach. These available modeling results can be
                                     2-9

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                             FIGURE 2-4
               STEP 3 • CALCULATE EMISSION ESTIMATES
         Source Characterization Information/Constituent Surrogates
    Primary approach -
  calculate emissions by
  using models available
   from the following:

•  CHEMDAT6

•  Hazardous Waste
   Treatment Storage and
   Disposal Facilities
   (TSDF)- Air Emission
   Models

•  AP-42

•  Other standard EPA
   technical documents
  Alternative approach -
  calculate emissions by
applying scaling factors to
emission modeling results
available for limited set of •
  so u rce see n a r i os (see  .
       Figure 2-5).      '
                                Step 4-

                               Calculate
                        Concentration Estimates
                                2-10

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                               FIGURE 2-5
     STEP 3 - CALCULATE EMISSION ESTIMATES (ALTERNATIVE APPROACH)

        Source Characterization Information/Constituent Surrogates
 Obtain Emission Rate Estimation Worksheets (as selected in Step 1):
 •  Disposal impoundment-Table S-1
 •  Storage impoundment/open tank -
    Tablel-2
 •  Oil film on storage impoundment-
    Table S-3
 •  Mechanically aerated impoundment -
    Table S-4
 •  Diffused air system - Table S-5
 •  Land treatment - Table S-6
 •  Oil film surface on land treatment
    unit-Table S-7
                                        Closed landfill-Table S-8
                                        Open landfill-TableS-9
                                        Wastepile-Table S-10
                                        Fixed roof tank-Table S-11
                                        Floating roof tank - Table S-12
                                        Variable vapor space tank -
                                        Table S-13
                                        Storage pile (particulates)-
                                        Table3-l4
                                        Exposed, flat, contaminated area
                                        (particulates) - Table S-15	
                                 I
 Select the source scenario for each modeling parameter (identified in Col. 1 of
 worksheets) that best represents unit-specific conditions from available cases
 (appropriate alternative case numbers are identified in Col. 3 of the worksheet
 and case specifications are presented in Appendices C-Q):
 • Disposal impoundment-Table C-1
 • Storage impoundment/open tank-
   TableD-1
 • Oil film on storage impoundment -
   Table E-1
 • Mechanically aerated impoundment-
   Table F-1
 • Diffused air system - Table G-1
 • Land treatment - Table H-1
 • Oil film surface on land treatment
   unit-Table I-2
                                        Closed landfill-TableJ-1
                                        Open landfill-Table K-1
                                        Wastepile-Table L-1
                                        Fixed roof tank-Table M-1
                                        Floating roof tank-Table N-1
                                        Variable vapor space tank -
                                           Table 0-1
                                        Storage pile (particulates) -
                                        Table p-i
                                        Exposed, flat, contamianted
                                        area (particular
                      f^l I VW I I I I M I I VW W

                      es) Table Q-1
Compute parameter-specific scaling, factors by completing Cols. 4-11 (12 for
Raoult's Law surrogates) of the worksheet or Co|. 4 for particulate worksheets
based on modeling results presented in Appendices C-Q (computational
                 ;ented with each v
instructions are presentee
worksheet):
•  Disposal impoundment - Table C-2
•  Storage impoundment/open tank-
   TableT>-2
•  Oil film on storage impoundment -
   Table E-2       s
•  Mechanically aerated impoundment -
   Table F-2
•  Diffused air system - Table G-2
•  Land treatment - Table H-2
•  Oil film surface on land treatment
   unit -Table I-2
                                       Closed landfill-Table J-2
                                       Open landfill-Table K-2
                                       Wastepile - Table L-2
                                       Fixed roof tank -Table M-2
                                       Floating roof tank - Table N-2
                                       Variable vapor space tank -
                                       Table O-2
                                       Storage pile (particulates) -
                                       Table"P-2
                                       Exposed, flat, contaminated area
                                       (particluates) Table Q-2
       Complete unit-specific emission rate, which accounts for unit-
       specific scaling factors (last line item on each worksheet based
       on instructions presented with each worksheet).	
                                Step 4-

                   Calculate Concentration Estimates
                                  2-11

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interpolated to estimate a unit-specific emission rate. The process for calculating
emission rate estimates  for application  to a  specific  unit  (i.e./unit-specific
application) is summarized in Figure 2-5.

Calculating emission rate estimates is accomplished by completing an Emission Rate
Estimation Worksheet, included in Appendix S. A separate worksheet is provided in
Appendix S for each unit category. Column 2 (unit-specific values for each modeling
parameter) of the worksheet should already have been completed during Step 1.

The alternative emission estimation approach presented in Figure 2-5 also involves
scaling the  emission rate modeling results available in Appendices C through Q to
represent unit-specific conditions.   This  is accomplished  by first computing
individual parameter-specific factors  and then combining the results to calculate a
unit-specific emission rate for each surrogate  of interest. Therefore, it is necessary
to select the appropriate  source  scenario that  best represents unit-specific
conditions for each modeling parameter (identified in Column 1  of the worksheet).
Column 3 of the worksheet identifies the appropriate candidate scenario cases for
each parameter.  The source scenario  case specifications (i.e., values of the modeling
parameters for each case) are presented in Table C -1  (disposal impoundment), D-1
(storage impoundment), E-1 (oil film on storage impoundment), F-1 (mechanically
aerated impoundment), G-1 (diffused air system), H-1 (land treatment), 1-1 (oil film
surface  on  land treatment unit), J-1 (closed landfill),  K-1 (open  landfill),  L-1
(wastepile), M-1 (fixed roof tank), N-1 (floating roof tank), O-1 (variable vapor space
tank), P-1 (storage piles), and Q-1 (exposed, flat, contaminated areas).

It is also recommended that a second scenario case be selected for each parameter
in order to bracket source conditions.   The selection of a second scenario is
appropriate if unit-specific source conditions are different than those presented in
the source scenario case specifications (Appendices C-Q).

Parameter-specific scaling factors are computed by following instructions in each
worksheet and by completing Columns 4-11 (12). (Column 12 is needed for RaouIt's
Law surrogates.) Information needed to complete Columns 4-11 (12) is available in
Appendices C through Q.  Information  needed  to complete  worksheets  for
particulate  emissions  are available  in  Appendices  P and Q.   Instructions  for
                                    2-12

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computing unit-specific emission rates based  on applying  scaling  factors are
included in each worksheet.

The  last set of three source scenario  cases for unit-category  modeling  results
presented in Appendices C through Q represents the following:

     •    Reasonable best-case emission rate for unit category (for a typical source
          surface area or tank size)

     •    Typical emission rate for unit category (for a typical source surface area
          or tank size)

     •    Reasonable worst-case emission  rate for unit category  (for a  typical
          source surface area or tank size)

Frequently these cases can be used to rapidly estimate typical and extreme emission
rates. However, they should not be considered as absolute values. These scenarios
generally  represent the range of source conditions identified in the  Hazardous
Waste Treatment. Storage and Disposal Facilities (TSDF) Air Emission Models (U.S.
EPA,  December  1987).  But frequently  this information was  incomplete,  and
subjective estimates were  postulated instead.  Therefore, the emission rates for
best, typical  and worst case source scenarios should only be used as a preliminary
basis to compare and prioritize sources.

At times one of the source scenario cases presented in the Appendices  may be
representative of the modeling parameters for the unit scenario being evaluated.
For these situations, it is not necessary to implement all of the intermediate
computational steps otherwise needed  to complete the worksheet.  Instead, the
modeling  results presented in Appendices C through Q can  be used  to  directly
represent  unit-specific emission rates. However, it may be necessary to scale these
results to account for the  unit-specific surface  area and waste  constituent
concentrations. (Scaling can be  accomplished  by the approach  specified  in each
worksheet).
                                    2-13

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2.5       Step 4 - Concentration Estimates

Emission rate  values from Step 3  are  used  as  input  to  calculate  concentration
estimates at receptor locations of interest. Dispersion conditions are accounted for
by use of available modeling results for typical annual meteorological conditions. A
summary of this process is included in Figure 2-6. Dispersion models can be applied
to directly estimate concentration.  This primary approach is recommended for most
applications.   The  EPA-lndustrial  Source  Complex  (ISC)  model is  generally
appropriate for a wide range of sources in flat or rolling terrain. Alternative models
are identified in the Guideline On Air Quality Models (Revised) (U.S. EPA, July 1988).

An alternative approach to obtain concentration  estimates (for flat terrain sites)
involves  the application of  dispersion factors  presented in Appendix R.   A
Concentration  Estimation  Worksheet  (Table  R-1)  is  used as  the  basis  for
concentration calculations. This approach is appropriate when a rapid preliminary
estimate is needed and modeling resources are not available. However, the primary
approach will provide more representative site-specific concentration estimates.

Specific instructions  for implementing  the alternative concentration  estimation
approach are presented in Figure 2-7.

Concentrations should  be estimated at locations corresponding to receptors of
concern (pursuant to RFI  Guidance).  Receptor information may also be available
from the RFA. Column 2 of the worksheet should be completed to define distances
to receptors as a function of direction.

Ambient concentrations are  influenced by atmospheric dispersion conditions in
addition to emission rates. Atmospheric dispersion conditions for ground-level non-
buoyant releases (as  is the case for surface impoundment, landfill, land  treatment
unit,  and wastepile applications)  can be accounted for by the  use of  dispersion
factors.  Appropriate dispersion factors based on Figure  R-1 should be  used to
complete Column 3 of the worksheet The dispersion factors presented in Figure R-1
include individual plots for a range of unit-surface-area sizes. Instruction regarding
the use of these plots to determine unit- and receptor-specific dispersion factors is
included with Figure R-1.
                                    2-14

-------
                             FIGURE 2-6
            STEP 4 - CALCULATE CONCENTRATION ESTIMATES
                           Emission Estimates
    Primary approach -
calculate concentrations by
 using dispersion models:

•  ISC

•  Other models identified
   in Guideline on Air
   Quality Models
   (Revised)
  Alternative approach -
calculate concentrations by
applying dispersion factors
     (see Figure 2-7).
                                Step 5-

                          Compare Results to
                          Health-Based Criteria
                                2-15

-------
                         FIGURE 2-7
        STEP 4 - CALCULATE CONCENTRATION ESTIMATES
                  (ALTERNATIVE APPROACH)
                           Emission Estimates
RFA Receptor
Information
                          Obtain Concentration
                          Estimation Worksheet
                               (Table R-1).
Define receptor locations of interest
(complete Col. 2 of worksheet to
define distances of receptors as a
function of direction).
                    Determine dispersion factor (Chi/Q)
                    values for appropriate source area
                    and receptor downwind distance
                    based on Figure R-1 (complete Col. 3
                    of worksheet).
                    Assume annual downwind frequency
                    of 100% for each receptor (complete
                    Col. 4 of worksheet).
                    Calculate long-term ambient
                    concentrations based on Equation 1
                    of worksheet (complete Cols. 5-13).
                                 Step 5-

                            Compare Results to
                           Health-Based Criteria
                            2-16

-------
The dispersion factors presented in Figure R-1 are based on the assumption that
winds are flowing in one direction (i.e..toward the receptor of interest) 100 percent
of the time on an annual basis.  This conservative assumption of a wind direction
frequency of 100%  for each receptor of interest should be used if Figure R-1 is used
as the basis to estimate dispersion conditions for Column 4 of the worksheets.

The information entered into Column 3 and 4 of the worksheet, plus the emission
rate  results calculated during Step 3,  provides the required input to calculate
ambient concentrations. Specifically, Equation 1 presented in the worksheet should
be used to obtain ambient concentrations for each surrogate and receptor location.
Equation  1 of Table R-1 includes  a safety factor of  10 which is applied to all
concentration estimates based on the scaling approach. This factor accounts for the
inherent uncertainty involved in the scaling approach.  This  safety factor is
applicable to all concentration estimates based on emission rates obtained via the
scaling approach. These results should be entered into Columns 5 through  13 of the
worksheet.
                                                                         I
2.6       Step 5 • Health Criteria Comparisons

Concentration results from Step  4 can  be compared to  constituent-specific
health-based criteria provided in the RFI Guidance (see Figure 2-8). To facilitate this
comparison,  it is  recommended that the  appropriate reference  toxic  and
carcinogenic  criteria be entered  in the space allocated in the Concentration
Estimation Worksheet.

Interpretation of the ambient concentration estimates should also account for the
uncertainties associated with the following components of the assessment:

     •    Inaccuracies in input source characterization  data will directly affect
          concentration results.

     •     Emission rate models  have not been  extensively verified.  However,
          OAQPS states, "In general, considering the uncertainty of field emission
          measurements, agreement between measured and predicted emissions
          generally agree within an order of magnitude." (U.S. EPA, April 1987).
         These verifications have been for short-term emission conditions. Model
                                   2-17

-------
                       FIGURE 2-8
   STEP 5 - COMPARE RESULTS TO HEALTH-BASED CRITERIA
RFI Guidance
Health Criteria
                          Concentration Estimates
                                     l	
Compare annual concentrations
to health criteria:

   •  Toxic criteria
   •  Carcinogenic criteria
                       Consider modeling/screening
                       methodology uncertainties and
                       background concentrations.
                       Consider variations in emission
                       rates/concentrations for various
                       exposure periods
                         Input to Decision on Need for
                                RFI-Air Media
                          2-18

-------
          performance  is expected  to be  better  for  long-term emission rate
          estimation (as used for this screening assessment).

     •    Inaccuracies associated with  use of the alternative emission estimation
          approach presented in Figure 2-5.

               Source conditions for the unit of interest may not be the same as
               those  for the source  scenarios presented  in  Appendices C-Q.
               Therefore, scenarios should be selected to bracket the unit-specific
               conditions in order to obtain a range of emission rate estimates.

               The use of scaling factors for each source parameter may yield
               somewhat different emission rate values compared to those based
               on direct use of a model with unit-specific inputs. These differences
               are attributed to the interrelationships of source parameters which
               may not be linear.  A comparison of direct modeling results versus
               scaling estimates is presented in Exhibit 2-1.

     •    Atmospheric dispersion models for long-term applications (as used for
          this screening assessment) typically are accurate within a factor of ± 2 to
          3 for flat terrain (inaccuracy can be a factor of ± 10 in complex terrain.

Therefore, "safety factors"  commensurate  with  these uncertainties should  be
applied to concentration estimates for health criteria comparisons.

The calculations of emission rate and concentration estimates obtained have been
for a 1-year period. Some units, such as closed landfills, will have different average
emission rates for longer exposure periods for certain constituents. The air pathway
health-based criteria included in the RFI Guidance are based on a 70-year exposure
period. Appendices C through Q each contain a set of scenario cases for 1-, 5-, 10-,
and 70-year exposures for information  purposes. However, only inactive units are
expected to have an average 70-year emission rate that is significantly different
from the 1-year rate.  All of the emission results presented in Appendices C through
Q are assumed to be active with the exception  of closed  landfills (Appendix J). Air
concentrations  for each one-year period within the reference  70 year exposure
period should be less than those associated with constituent-specific health criteria.
                                    2-19

-------
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3.0   EXAMPLE APPLICATIONS

Two case studies have been selected to demonstrate the  application of the
alternative (scaling) air assessment screening methodology based on the technical
aids presented in Appendices B through S. The first example involves a  storage
impoundment and the second a closed landfill.

3.1   Case Study A

Case Study A involves a storage impoundment located close to a small community.
The closest resident lives 0.2 mile south of the unit. The impoundment has a surface
area of 1 acre, a depth of 0.9 meter, and a typical storage  time cycle of 1.2 days.
Wind  data from the nearest National Weather Service station indicate that
northerly winds occur 10 percent of the time annually. Waste records for the un^t
indicate the frequent appearance of carbon tetrachloride.  Limited waste analyses
indicate that a 1,000-ppm concentration of this constituent in the impoundment is a
reasonable assumption.  The object of this example screening assessment is to
estimate the ambient concentrations at the nearest residence.  Following is a
summary of this example application.

Step 1 -Obtain Source Characterization Information

The appropriate Emission Rate Estimation Worksheet for this case study is Table S-2
for storage impoundment units. The unit information provided above is sufficient
to complete Column 2 for Lines 1-4 of the worksheet (see Exhibit 3-1) pursuant to
Instruction A of the Worksheet (Table S-2).
                                  i
Step 2 - Select  Release Constituent Surrogates

Based  on Figure 2-3,  it is apparent that the  Henry's Law Constant surrogate subset
(Table B-1) is appropriate for a storage impoundment unit. Evaluation of Table B-3
indicates that the following surrogate is applicable to Case Study A:
                                   3-1

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          Constituent
     •    Carbon tetrachloride
Surrogate No.
Surrogate Code

     HHLB
Step 3 - Calculate Emission Estimates

This step involves implementing  Instructions B-D of the  Worksheet (Table S-2).
Instruction B involves selection of representative cases from Table D-1 which best
match actual unit values in Column 2. A review of Table D-1 indicates that Case 1
(based on a depth of 0.9 meter) best estimates the depth of the example case (also a
depth of 0.9 meters has been specified for Case Study A).  Table D-1 also indicates
that Case 5 (based on a retention cycle of 1 day) best represents the example case (a
retention cycle of 1.2 days has been specified for Case Study A).

Implementation of Instruction C involves determination  of surrogate-specific
                                                                         i
scaling factors.  For this example this involved completion of Column 5 for lines 2
and 3 of the Worksheet (Table S-2).  Emission rates for Cases 1 and 5, and a typical
emission rate (Case  18) were obtained from Table D-2 as follows:
Case
Casel
CaseS
Case 18
Emission Rate (1Q6g/yr)
Carbon Tetrachloride
22.5
161.5
39.2
Column 5 of the worksheet (for carbon  tetrachloride) was completed  via the
following computations (Case 18 represents a typical emission rate for the source
category of storage impoundment):
     *Line2:
    Case 1 Emission Rate (from Table D-2)
    Case 18 Emission Rate (from Line 7 of the Worksheet)
                                   0.57
                                    3-3

-------
     *Line3:
    Case 5 Emission Rate (from Table D-2)                       161.5
    Case 18 Emission Rate (from Line 7 of the Worksheet)        39.2
                                                                  = 4.1
Implementation of Instruction D of the Worksheet (Table S-2) involves completion
of Lines 5-6 and 8 as follows:
     *Line5:
    Unit-Specific Area (from Column 2 of the Worksheet)         1.0
    Case 18 Area (this value is identified in the Worksheet        0.4
    instructions for Line 5)
     *Line6:
    Unit-Specific Concentration                               1,000
                                                                  = 2.5
                                                                  = 1.0
    Case 18 Concentration                                    1fOOO


     *Line8:
     Emission Rate  =  Line 2 x Line 3 x Line 5 x Line6x Line?
                   =  0.57x4.1x2.5x1.0x39.2
                   =  229.0 x106g/yr
                   -  229.0 Mg/y

 Step 4 - Calculate Concentration Estimates

This step involves use of the Concentration  Estimation Worksheet (Table R-1).
Application of the Worksheet involves implementation of Instructions A-D included
in Table R-1. The example Concentration Estimation Worksheet for Case Study A is
presented in Exhibit 3-2. Implementation  of Instruction A involves input of the
distance of the receptor from the downwind unit boundary for sectors of interest.
Notice that the receptor distance of 0.2 mile (Column 2) corresponds with the south
(downwind) sector. This is because the frequency of northerly winds obtained from
the National Weather Service (as stated at the beginning of 3.1) represents the
                                    3-4

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direction "from which the wind is flowing."  This is standard meteorological
terminology. Therefore, northerly winds affect receptors south of the unit.

Implementation of Instruction B involves determination  of  the  appropriate
dispersion  factor for the downwind  distance selected.  The dispersion  factor
obtained from Figure R-1 for this example is 6.4 x 10-5 sec/m3 (entered in Column 3
of the Concentration Estimation Worksheet). This value is applicable  to a receptor
0.2 mile downwind from a 1-acre area source.

Implementation of Instruction C involves entering the downwind frequency for the
sector of interest  in Column 4 of the  Worksheet.  The downwind frequency
(conservatively assumed to be 100 percent if Table R-1  dispersion factors are used)
fora receptor located south of the unit is entered in Column 4 of the Worksheet.
Implementation of Instruction D involves computation of air concentrations based
on Equation 1 of the Worksheet (Table R-1). The concentration estimate for carbon
tetrachloride was calculated using Equation 1 of the Worksheet as follows:

   •  Worksheet estimate:

     Concentration (pg/m3) = Col. 3 x Col. 4 x Emission Rate x (unit conversion =
                             3.17 x 102) x (Safety factor « 10)
                          = (6.4 x 10 -5) x (100) x (229.0) x (3.17 x 102) x (10)
                          = 4600 vig/m 3

Step 5 - Compare Results to Health Criteria

Available health-based criteria from the RFI Guidance were entered into the
Concentration Estimation Worksheet (see Exhibit 3-2).  These results indicate that
carbon tetrachloride concentrations at the nearest receptor  significantly exceed the
carcinogenic health-based  criteria.  Based on the expected carbon tetrachloride
concentrations, this unit is a prime candidate for unit-specific emission rate and
dispersion modeling to confirm the need for an RFI for the air media.
                                    3-6

-------
3.2   Case Study B

Case Study B involves a closed landfill of 7 acres with a waste-bed thickness of 25
feet and a cap thickness of 6 feet. Benzene is believed to be a primary constituent
of the waste (approximately 10 percent). The closest resident lives 1 mile east of the
unit. The prevailing winds (which occur 20 percent of the time annually, based on
available facility data) are from the west (i.e., these winds will affect the downwind
sector east of the unit). Following is a summary of the screening assessment for
Case Study B.

Step 1 -Obtain Source Characterization Information

The appropriate Emission Rate Estimation Worksheet for Case Study B is Table S-8
for closed landfill units: The unit information provided is sufficient to complete
Column 2 of the worksheet, with one exception (see Exhibit 3-3): the air porosity of
the fixed waste is not  known. Therefore, typical conditions [i.e., 25 percent a^
represented by Cases 14 and 22 (see Table J-1) will be assumed for this assessment].

Step 2 - Select Release Constituent Surrogates
                                          •
Based on Figure 2-3, it is apparent that the Raoult's Law surrogate subset (Table B-2)
is appropriate for a closed landfill unit.  Evaluation of Table B-3 indicates that the
following surrogate is applied to Case Study B:

   Constituent         Surrogate No.           Surrogate Code
   Benzene                  1                    HVHB

Step 3 - Calculate Emission Estimates

The calculational inputs for the Emission  Rate  Estimations  Worksheets for Case
Study B are presented  in Exhibit 3-3  and  3-4.  Scenario Case 1 (Exhibit 3-3) and
Scenario Case 2 (Exhibit 3-4) were selected to bracket the actual waste-bed thickness
for the example unit. Scenario Case 1 is associated with a waste-bed thickness of 15-
feet and Case 2 with  a 30-foot bed thickness. The actual waste-bed thickness is 25
feet. The resulting benzene emission rate estimates range from 46.4 x 106g/yr to
83.4x106g/yr.
                                     3-7

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-------
Step 4 - Calculate Concentration Estimates

The example Concentration Estimation Worksheets for Case Study B are presented
in Exhibits 3-5 (Scenario Case 1) and 3-6 (Scenario Case 2). The resulting benzene
concentration  at the nearest receptor is estimated to range from 69 ug/m3 to 124
ug/m3.

Step 5 - Compare Results to Health Criteria

A review of results presented in Exhibits 3-5 and 3-6 indicates that the estimated
benzene concentrations of 69 wg/m3 to 124 ug/m3 are approximately 1000 times the
carcinogenic criterion of 0.1  ug/m3.  A toxic criterion is not available for benzene.
Based on the results presented in Exhibits 3-5 and 3-6, this unit is a prime candidate
for an air release RFI.
                                    3-10

-------




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4.0  REFERENCES

U.S. EPA, September 1985 (and subsequent supplements). Compilation of Air
Pollutant Emission Factors, Vol. I. Washington, DC 20460.

U.S. EPA, June 1974. Development of Emission Factors for Fugitive Dust Sources,
Research Triangle Park, NC, 27711.

U.S. EPA, March 1978. Fugitive Emissions from Integrated Iron and Steel Plants. EPA
600/2-78-050, Washington, D.C.

U.S. EPA, July 1988. Guidelines on Air Quality Models (Revised). EPA-450/2-78-027R,
Office of Air Quality Planning and Standards, Research Triangle Park, NC 27711.

U.S. EPA. December 1987. Hazardous Waste Treatment Storage and Disposal
Facilities (TSDF) Air EmissiorTModels. Office of Air Quality Planning and Standards.
Research Triangle Park, NC 27711 (CHEMDAT6).

U.S. EPA, 1989. RCRA Facility Investigation (RFI) Guidance. Office of Solid Waste,
Washington, D.C. 20460.

Turner. D.B. 1969. Workbook of Atmospheric Dispersion Estimates. Public Health
Service, Cincinnati, OH.                                                     ,

                                                                         I
                                    4-1

-------
     Appendix A
Background Information

-------
A.O      BACKGROUND INFORMATION

The air release screening assessment methodology has been developed based on
use of available air emissions models applicable to facilities for treatment, storage,
and disposal  of hazardous waste, and on results of atmospheric dispersion
modeling. The emission models were used to  calculate emission rates for a wide
range of source scenarios. (An emission rate is defined as the source release rate for
the air pathway in terms of mass per unit of time.)  These modeling results have
been summarized in this document so that they can be easily used by Environmental
Protection Agency (EPA) Regional and State Agency staff to estimate emission rates
for facility-specific and unit-specific applications.  These source-specific emission
rates can be used in conjunction with dispersion modeling results, representative of
typical annual conditions, to estimate long-term  ambient concentrations at
locations of interest.  (Ambient concentrations are defined as the concentrations of
the released constituent downwind from the source.)   The emission rate and
atmospheric dispersion modeling  approaches used to develop the screening
methodology are discussed in the subsections that follow.

A.1      Emission Rate Models

The air release screening assessment  methodology has been based primarily on
application of air emission models (available on a  diskette for use  on a
microcomputer) developed  by EPA's Office of Air Quality  Planning and Standards
(OAQPS) to estimate  organic releases for hazardous waste treatment, storage, and
disposal facilities (TSDFs) (U.S. EPA, December 1987).  Computer-compatible air
emission models (referred to as CHEMDAT6 models) are available for the following
sources:

    •   Surface impoundments, which for modeling purposes include quiescent
         impoundments, aerated impoundments, and open-top tanks
              Disposal impoundments
              Storage impoundments
              Oil films on storage impoundments
              Aerated impoundments
                                  A-1

-------
     •    Land treatment
              Soil emissions subsequent to waste tilling
              Oil film surfaces
     •    Closed landfills
     •    Open landfills
     •    Wastepiles

Since the  results presented in this document are based on the  December 1987
version of CHEMDAT6, subsequent modifications to any of these models may
require revisions to this screening methodology

The available models for CKEMDAT6  provide a basis to estimate emissions for
numerous unit categories (e.g., surface impoundments, landfills) as previously
listed. Therefore, the CHEMDAT6  models will be applicable to a wide range of air
release screening assessments.  CHEMDAT6  (December 1987 versions) does not,
however, include models for the following sources:                            '
                                                                        I
     •    Land treatment-waste application
     •    Fixation pits
     •    Containerloading
     •    Container storage
     •    Containercleaning
     •    Stationary tank loading
     •    Stationary tank storage
     •    Fugitive emissions
     •    Vacuum truck loading

However, guidance for estimating  organic emissions from these sources is available
from OAQPS (U.S. EPA, December 1987).

In addition to the CHEMDAT6 model, emission equations from EPA's AP-42,
"Compilation  of  Air Pollutant Emission Factors" and "Fugitive Emissions from
Integrated Iron and Steel Plants" have  been  used for estimating organic emissions
from storage tanks and paniculate matter emissions that are less than 10 microns in
diameter from storage piles and exposed areas which result from wind erosion and
activities on storage piles.
                                   A-2

-------
A.2       Source Scenarios

A wide range of source scenarios were evaluated as a basis for developing the air
release assessment methodology.  This involved identification of a limited set of
surrogates to represent the numerous individual potential air release constituents
of concern. This also involved evaluating of the sensitivity of the input parameters
used by the CHEMDAT6 air emission models and the AP-42 emission equation input
parameters.

A.2.1      Release Constituent Surrogates

A  limited  set of surrogates was required to simplify the  air release assessment
methodology since the list of potential air release constituents included in the RFI
Guidance  (U.S.  EPA, 1988) is extensive.  The set of surrogates selected  for this
application was the same list developed by OAQPS for  assessment of  organic
emissions from TSDFs (see Appendix B).

Two subsets  of suhogates are presented  in Appendix B.  The first subset is
applicable to air emission modeling applications based on the use of the Henry's
Law Constant (Table B-1) and the second subset is  based on  use of Raoult's Law
(Table B-2).  Raoult's Law accurately predicts the behavior of most  concentrated
mixtures of water and organic solvents  (i.e., solutions over  10  percent  solute).
According to Raoult's Law, the rate of volatilization of each chemical in a mixture is
proportional to the product of its concentration  in the  mixture and its vapor
pressure.  Therefore,  Raoult's Law can be used to characterize potential  for
volatilization. This is especially useful when the unit of concern entails container
storage, tank storage, or treatment of concentrated waste streams.

The Henry's Law Constant is the ratio of the vapor pressure of a constituent to its
aqueous solubility (at equilibrium).  This constant can be used to assess the relative
ease with which the compound may vaporize from the aqueous solution and will be
most useful when the unit being  assessed is  a surface impoundment  or tank
containing dilute wastewaters. The potential for significant vaporization increases
as the value for the Henry's Law Constant increases;  when it is greater than 10E-3,
rapid volatilization will generally occur.
                                    A-3

-------
The surrogates presented in Appendix B span the range from very high volatility to
low volatility (frequently classified as semi-volatiles).  Biodegradation potential has
also  been accounted for  in the surrogate specifications.  Therefore,  a  cross-
reference of constituents has also been provided in  Appendix B (Table B-3). This
listing provides the  basis for the identification of the appropriate surrogate for
individual  air release constituents of interest.  Instructions for use of Appendix B
data are provided in Section 2.

A.2.2     Sensitivity Analyses

Sensitivity  analyses of the input parameters used by the CHEMDAT6 air  emission
models emission rate relative to output were evaluated to determine the feasibility
of developing a  source characterization index.   The  object  of the source
characterization index was to define  a simple relationship between the primary
source description  parameters and the emission rate of the release.  This evaluation
was  accomplished by modeling a series  of source  scenario cases for each unit
category (i.e., categories such as surface impoundments and landfills). Each of these
source scenario cases represents long-term (i.e., annual) emission conditions. A base
case  representative of typical source conditions was defined for each unit category.
These typical conditions were specified based on  TSDF survey  results and  on
guidance  presented  in the OAQPS air  emissions  modeling  report  (U.S. EPA,
December 1987). This base case provided a standard for comparison to results of
parametric analyses. The parametric analyses consisted of varying  (one at a time)
the input values  for the  most sensitive modeling parameters. These input
parameter values  were varied  over a range of expected  source  conditions.  In
addition to the parametric analyses and  the typical  (base-case) scenario, a
reasonable best-case (minimum emission rate) and a  reasonable worst-case
(maximum emission  rate) source scenario were also  modeled.  The most  sensitive
modeling  parameters and  their associated  range of values were  determined by
considering model sensitivity results and TSDF source  survey information presented
in the OAQPS air emission  modeling report (U.S.EPA, December 1987), as well as
other judgmental factors. A similar sensitivity analysis was performed for the three
tank types.
                                   A-4

-------
A summary of the air emissions modeling parameters, input values, and modeling
results (emission rates) is presented in Appendices C through Q.  Evaluation of these
results indicates that emission rates are highly dependent on  numerous sensitive
source parameters.  Therefore, these complex relationships are not conducive to
development of a source characterization index (i.e., defining a simple relationship
between the primary source description parameters and the emission rate of the
release).  However, the modeling results  presented  in Appendices  C through Q
provide data which can be interpolated to estimate unit-specific emission rates with
minimal guidance.  The methodology for application of these  data is discussed in
Section 2.

A.3      Atmospheric Dispersion Conditions

Atmospheric dispersion conditions affect the downwind dilution of emissions from
a source. Available EPA dispersion models can be used to account for site specific
meteorological and source  conditions.  For this screening assessment, modeling
results are presented which represent typical dispersion conditions (neutral stability
and 10-mph winds) in the United States.

Dispersion modeling results  to be used for the screening assessment (assuming flat
terrain) are presented in Appendix R (Figure R-1) and are applicable to ground-level
sources with non-buoyant releases (this  assumption  is  valid  for  surface
impoundments, land treatment units, landfills, waste piles, tanks,  and exposed
areas). These results are presented in terms of dispersion factors. Dispersion factors
can be considered as the ratio of the ambient concentration to the source emission
rate.   Therefore,  dispersion  factors facilitate  the calculation of  ambient
concentrations if emission rate estimates are available.

The dispersion  factors presented in Figure R-1 were  developed  from similar
dispersion graphs presented in a standard technical reference (Turner, 1969).  These
dispersion factors are applicable to long-term (e.g., annual) conditions. It has been
assumed that dispersion factors (and, thus also ambient concentrations) decrease as
a function of downwind distance but are uniform in the crosswind direction within
a 22.5 degree sector (22.5 degree sectors correspond with major compass directions
such as N, NNW, NW, etc.).  The dispersion  factors presented in Figure R-1 also
account for the initial  plume size, which  corresponds to the surface area of the
                                    A-5

-------
source (Turner, 1969).  Results presented in Figure R-1 are expected to be similar to
results from the EPA-approved Industrial Source Complex dispersion model.
                                   A-6

-------
    Appendix B
Release Constituent
  Surrogate Data                             ,

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-------
                TABLE B-3
LISTING OF CONSTITUENT-SPECIFIC SURROGATES
Constituent
Acrylamide
Acrylonitrile
Aldicarb
Aldrin
Aniline
Arsenic
Benz(a)anthracene
Benzene
Benzo(a)pyrene
Beryllium
Bis(2-chloroethyl)ether
Bromodichloromethane
Cadmium
Carbon tetrachloride
Chlordane
1-Chloro-2,3-
epoxypropane
(Epichlorohydrin)
Chloroform
Chromium (hexavalent)
DOT
Dibenz(a.h) anthracene
1,2-D«bromo-3-
Chloropropane (OBCP)
1,2-Dibromoethane
1,2-Oichloroethane
1,1-Dichloroethylene
Dichloromethane
(Methyl ene chloride)
CAS
No.
79-06-1
107-13-1
116-06-3
309-00-2
62-53-3
7440-38-2
56-55-3
71-43-2
50-32-8
7440-41-7
1.11-44-4
75-27-4
7440-43-9
56-23-5
57-74-9
106-89-8
67-66-3
7440-47-3
50-29-3
53-70-3
96-12-8
106-93-4
107-06-2
75-35-4
75-09-2
Henry's Law
Constant
Surrogate Code
7
4
8
3
8
0
9
1
9
0
5
3
0
3
6
6
3
0
3
9
6
3
3
3
I
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Surrogate Code
4
1
9
7
5
0
7
1
8
0
5
7
0
3
7
3
3
0
7
7
6
3
3
3
1
                  B-3

-------
                     TABLE B-3
LISTING OF CONSTITUENT-SPECIFIC SURROGATES (Continued)
Constituent
2,4-Dichlorophenol
2,4-Dinitrophenol
2,4-Dinitrotoluene
1,4-Dioxane
1 ,2-Diphenylhydrazine
Endosulfan
Ehtylene oxide
Heptachlor
Hexachlorobenzene
Hexachlorobutadiene
Hexachloroethane
Hydrazine
Isobutyl alcohol
Lindane (gamma-
Hexachlorocyclohexane)
3-Methyl-cholanthrene
4,4-Methylene-bis-{2-
chloroaniline)
Methyl parathion
Nickel
Nickel (refmtry dust)
Nickel subsuifidt
2-Nitropropan*
N-Nitroso-N-methyl urea
N-Nitroso-pyrrolidine
Pentachlorobenzene
Pentachlorophenol
CAS
No.
1 20-83-2
51-28-5
121-14-2
123-91-1
122-66-7
115-29-7
75-21-8
76-44-8
118-74-1
87-68-3
67-72-1
302-01-2
78-83-1
58-89-9
56-49-5
101-14-4
298-00-0
1440-02-0
7440-02-0
12035-72-2
79-46-9
684-93-5
930-55-2
608-93-5
87-86-5
Henry's Law
Constant
Surrogate Code
8
9
9
6
9
9
4
3
6
3
9
q
7
9
6
3
6
0
0
0
6
5
2
3
9
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Surrogate Code
5
3
6
3
7
7
10
7
7
6
6
3
4
7
7
6
6
0
0
0
3
9
2
6
7
                       B-4

-------
                     TABLE B-3
LISTING OF CONSTITUENT-SPECIFIC SURROGATES (Continued)
Constituent
Perchloroethylene
(Tetrachloroethylene)
Styrene
1,2,4,5-
Tetrachlorobenzene
1 , 1 ,2,2-Tetrachloroethane
2,3,4,6-Tetrachlorophenol
Tetraethyl lead
Thiourea
Toxaphene
1 , 1 ,2-Trichloroethane
Trichloroethylene
2,4,5-Trichlorophenol
2,4,6-Trichlorophenol
CAS
No.
127-18-4
100-42-5
95-94-3
79-34-5
58-90-2
78-00-2
62-56-6
8001-35-2
79-00-5
79-01-6
95-95-4
88-06-2
Henry's Law
Constant
Surrogate Code
3
3
3
6
9
3
6
3
6
3
6
6
Raoult's Law
Surrogate Code
3
6
6
6
6
6
3
6
3
3
6
6
                       B-5

-------
     Appendix C


Emission Rate Estimates
Disposal Impoundments
  (Quiescent Surfaces)

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                           TABLE N-3
                     TANK RIM SEAL CLASSES
DESCRIPTION
External Floating Roof Tank:
Metallic shoe seal
- primary seal only
- with shoe mounted secondary seal
- with rim mounted secondary seal
Liquid mounted resilient seal
- primary seal only
- with weather shield
- with rim mounted secondary seal
Vapor mounted resilient seal
- primary seal only
- with weather shield
with rim mounted secondary seal
Internal Floating Roof Tank:
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- primary seal only
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Vapor mounted resilient seal
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CLASS
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                           TABLE N-4
                     TANK SHELL CONDITIONS
CLASS
A
B
C
DESCRIPTION
Light rust
i
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Gunite lined
                              N-5

-------
       Appendix 0

  Emission Rate Estimates
Variable Vapor Space Tanks

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-------
       Appendix P
 Emission Rate Estimates
Particles from Storage Piles

-------
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-------
Table P-2. Emission Rate Estimates (106 g/yr) - Particles from Storage Piles*
Case
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
Wind Erosion**
8.1E-07
2.0E-06
4.0E-06
8.1E-06
3.1E-06
6.2E-06
9.0E-06
1.5E-05
6.9E-06
6.2E-06
5.2E-06
5.0E-06
6.2E-06
6.2E-06
6.2E-06
6.2E-06
6.2E-06
6.2E-06
6.2E-06
6.2E-06
6.2E-06
6.2E-06
6.2E-06
6.2E-06
6.2E-06
6.2E-06
8.8E-07
6.2E-06
2.3E-05
Batch Dump***
1.1E-06
2.8E-06
5.6E-06
1.1E-05
8.7E-06
8.7E-06
8.7E-06
8.7E-06
8.7E-06
8.7E-06 '
8.7E-06
8.7E-06
5.1E-06
8.7E-06
1.2E-05
8.7E-06
2.1E-06
2.3E-07
5.9E-08
8.7E-06
8.7E-06
8.7E-06
8.7E-06
8.7E-06
8.7E-06
8JE-06
4.2E-07
8.7E-06
1.6E-05
Vehicle
Activity****
1.4E-07
3.6E-07
7.1E-07
1.4E-06
1.1E-06
1.1E-06
1.1E-06
1.1E-06
1.2E-06
1.1E-06
9.3E-07
8.6E-07
1.1E-06
1.1E-06
1.1E-06
1.1E-06
1.1E-06
1.1E-06
1.1E-06
6.5E-07
1.1E-06
2.1E-06
1.1E-06
1.1E-06
1.1E-06
1.1E-06
3.1E-07
1.1E-06
1.7E-06
                                 P-2

-------
                             Table P-2(Cont'd)

'Particle size of 10 microns assumed (emission rate particle multiplier of 0.5 used,
based on pg. 4-7 of Control of Open Fugitive Dust Sources. U.S. EPA, September
1988). Constituent concentration of 1ppm assumed.
**
  Emission rate estimates for wind erosion based on Equation 3, p. 11.2.3-5 of
Compilation of Air Pollutant Emission Factors. Vol.I. (U.S. EPA, September 1985).

***Emission rate estimates for batch dump operations were calculated using
Equation l.p. 11.2.3-3 of Compilation of Air Pollutant Emission Factors. Vol. I. (U.S.
EPA, September 1985).  Drop height of 21.9 feet and dumping device capacity of
6.375 yd3 assumed.

****Emission rate estimates for vehicle activity were calculated using Equation 1, p.
11.2.1-1 of Compilation of  Air Pollutant Emission Factors.  Vol. I. (U.S. EPA,
September, 1985) assuming one vehicle in continuous operation for 2,080 hours per
year at speed of 3 mph (this low speed assumed to account for loading/unloading in
immediate vicinity of the waste pile.)  Minor adjustments in emission rates should
be implemented  if unit-specific vehicle speeds and/or total vehicle miles traveled
per year are higher than these assumptions.
                                    P-3

-------
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-------
                Appendix Q

           Emission Rate Estimates
Particles from Exposed, Flat, Contaminated Areas

-------
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-------
                             TABLE Q-2
 EMISSION RATE ESTIMATES (106 g/yr) PARTICLES FROM EXPOSED AREAS*
Case
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Estimated Emission Rates**
(106 g/yr)
4.8E-08
1.2E-07
2.4E-07
4.8E-07
2.9E-07
4.3E-07
6.7E-05
1.0E-06
1.7E-06
9.1E-06
1.0E-06
3.6E-07
9.1E-06
4.0E-08
1.8E-07
3.6E-07
5.5E-07
9.1E-07
3.6E-07
3.6E-07
3.6E-07
3.6E-07
3.4E-08
3.6E-07
1 .46-04
*  Particle size of 10 microns assumed (emission rate particle multiplier of 0.5
   used, based on p. 6-9 of Control of Open Fugitive Dust Sources. U.S. EPA,
   September 1988). Constituent concentration of 1 ppm assumed.
** Emission rate estimates for particles from exposed areas were calculated
   using Equation 8, p. 4-2 of Fugitive Emissions from Integrated Iron and
   Steef Plants (U.S. EPA, March 1978).
                                Q-2

-------
                     TABLE Q-3
SOIL ERODIBILITY FOR VARIOUS SOIL TEXTURAL CLASSES*
Predominant Soil
Textural Class
Sand
Loamy sand
Sandy loam
Clay
Silty clay
Loam
Sandy clay loam
Sandy clay
Silt loam
Clay loam
Silty clay loam
Silt
Erodibiiity,
tons/acre/year
220
134
86
86
86
56
56
56
47
47
38
38
* U.S. Department of Agriculture July 1964. Guide for
Wind Erosion Control on Cropland in the Great Plains
States, Soil Conservation Service.
                       Q-3

-------
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Q-4

-------
    Appendix R
Dispersion Estimates

-------





























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      Appendix S

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                                            TABLES-14
         EMISSION RATE ESTIMATION WORKSHEET- PARTICLES FROM STORAGE PILES
               Col 1
                                      Col 2
                           Col 3
                                                       Col 4
Line
         Modeling Parameters
Instruction A:
 Input Unit -
   Specific
   Values
       Instruction B:
Select a Representative Case
from Appendix P - Table P-1
  (underline selected case)
 Instruction C

   Determine
Scaling Factor
 1   Area
 2   Silt content*
 3   Silt content*
 4   Silt content*
 5   % of ti me wi nd speed
     exceeds 12 mph*
 6   Days precipitation
     (> .01 inch/day)
 7   Mean wind speed*
 8   Moisture content*
 9   Vehicle weight*
 10   Vehicle wheels*
 11   Throughput*
 12   Mass fraction of
     contaminant
                                         acres
                                                   1,2, 3 or 4
                                                   5, 6, 7 or 8
                               wind erosion
                               batch dump
                               vehicle activity
                               wind erosion
                                         days

                                         mph

                                         tons

                                         tons/yr
                                         ppm
                9, 10, 11 or 12   wind erosion
                               vehicle activity
                13, 14or15     batchdump
                16, 17, 18oM9  batchdump
                20, 21 or 22     vehicle activity
     INSTRUCTION D: Complete Lines 13-15 and 19-22

13   Account for Area
     [unit-specific area/(Case 28 area = 5 acres)]
14   Account for Vehicle Wheels
     [square root (vehicle wheels)/square root (Case 28 wheels = V4)]
15   Account for Throughput
     [unit throughput/(Case 28 throughput  =  50,000 tons/yr)]
16   Typical case emission rate • wind erosion
     (Case 28), 106 g/yr
17   Typical case emission rate - batch dump
     (Case 28), 106 g/yr
18   Typical case emission rate - vehicle activity
     (Case 28), 10* g/yr
19   Calculate Unit-Specific Emission Rate-Wind Erosion, 106 g/yr
     (multiply lines #2 x #5 x #6 x #13 x # 16)
20   Calculate Unit-Specific Emission Rate - Batch Dump, 106 g/yr
     (multiply lines #3 x #7 x #8 x # 15 x # 17)
21   Calculate Unit-Specific Emission Rate - Vehicle Activity, 106 g/yr
     (multiply lines #4 x #7 x #9 x #14 x #18)
22   Calculate Total Emission Rate, 106 g/yr
     (add lines #19 f #20 •*• #21)
                                                                       SURROGATE-SPECIFIC VALUES
                                                                                     6.2 x 10'6

                                                                                     8.7x10-6

                                                                                     1.1 x 10'6
  Critical input value
  Scaling factor determined for Lines 2-12 from Appendix P
  m Case 28 (see lines 16.17, and 18).
                                            Emission Rate Estimate from Table P-2 divided by Typical Emission Rate defm

                                                S-14

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-------
                 APPENDIX H

            SOIL LOSS CALCULATION

               EXCERPTED FROM

U.S. EPA. Final Draft Superfund Exposure Assessment
 Manual. September, 1987. Office of Emergency and
    Remedial Response, Washington, D.C.  20460
                     H-1

-------
                                APPENDIX H

                          SOIL LOSS CALCULATION
           •
Introduction

     Many of the  organic substances  of concern found at Superfund sites are
relatively nonpolar, hydrophobic substances (Delos et al., 1984).  Such substances
can be expected to sorb to site soils and migrate from the site more slowly than will
polar compounds.  As discussed in Haith (1980) and Mills et al. (1982), estimates of
the amount of hydrophobic compounds released in site runoff can  be calculated
using the  Modified Universal Soil Loss Equation (MUSLE) and sorption partition
coefficients derived from the compound's octanol-water partition coefficient. The
MUSLE allows estimation of the amount of surface soil eroded in  a storm event of
given intensity, while sorption coefficients allow the projection of the amounts of
contaminant carried along with the soil, and the amount carried in  dissolved form.

Soil Loss Calculation

     Equation 2-20 is the basic equation for estimating soil loss.  Equations 2-21
through 2-24 are used to  calculate certain  input parameters  required to apply
Equation 2-20.  The modified universal  soil loss equation (Williams 1975),  as
presented in Mills et al. (1982), is:

         Y(S)E = a(Vrqp)0.56KLSCP                                     (2-20)

where

     Y(S)E       a   sediment yield (tons per event, metric tons per event).
        a      a   conversion constant, (95 English, 11.8 metric).*
        Vr     =   volume of runoff, (acre-feet, m3).
        qp     =   peak flow rate, (cubic feet per second, m3/sec).
     Metric conversions presented in the following runoff contamination equations
     are from Mills etal. (1982).
                                    H-2

-------
         K     =    the soil  credibility factor, (commonly expressed in tons per
                    acre per dimensionless rainfall erodibility unit).  K  can be
                    obtained from the local Soil Conservation Service office.
         L     «.   the slope-length factor, (dimensionless ratio).
         S     =    the slope-steepness factor, (dimensionless ratio).
         C     =    the cover factor, (dimensionless ratio:  1.0 for bare soil); see
                    the following discussion for vegetated site "C" values).
         P     a    the erosion control practice factor, (dimensionless ratio:  1.0
                    for uncontrolled hazardous waste sites).

     Soil erodibility  factors are indicators of the erosion  potential of given soils
types.  As such, they are highly site-specific. K values for sites under study can be
obtained from the local Soil Conservation Service office. The slope length factor, L,
and  the  slope steepness factor, S, are generally entered into the MUSLE as a
combined factor, LS, which is obtained from Figures 2-4 through  2-6. The  cover
management factor, C, is determined by the amount and type of vegetative cover
present at the site. Its value is " 1" (one) for bare soils. Consult Tables 2-4 through 2-
5 to  obtain C values for sites with vegetative covers.  The factor, P, refers to any
erosion control practices used on-site. Because these generally describe the type of
agricultural plowing or planting practices, and because it is unlikely that any
erosion control would  be practiced at an abandoned hazardous waste site,  use a
worst-case (conservative) P value of 1 (one) for uncontrolled sites.

     Storm runoff volume, Vr, is calculated as follows (Mills et al. 1982):

                          Vr » aAQr                                  (2-21)

where

     a     »   conversion constant, (0.083 English, 100 metric).
     A    a   contaminated area, (acres, ha).
     Qr   ~   depth of runoff, (in, cm).

     Depth of runoff, Qr, is determined by (Mockus 1972):

                    Qr = (Rt - 0.2Sw)*/(Rt + 0.85*,)                       (2-22)
                                     H-3

-------
                               Slope  Length,  Meters
                    20   30 40  60 80 100 150200 300 4OO 600 800
               40.0 •
                    70 100    200    4OO 600  IOOO    2000
                               Slept  Length,  Fett
Figure 2-4.     Slope Effect chart Applicable to Areas A-1 in Washington, Oregon,
              and Idaho, and All of A-3:  See Figure 3-5 (USDA 1974 as Presented
              in Mills etal. 1982).

NOTE:    Dashed  lines are extension of LS formulae  beyond values  tested in
         studies.
                                     H-4

-------
Figure 2-5.     Soil Moisture-Soil Temperature Regimes of the Western United
              States (USDA 1974).
                                     H-5

-------
       20
            3.S    6.0    10
Slope Length, Meters
 20      40  60    100
200    4OO  60O
           10      20      40  6O    IOO     200     400  600  1000    2000
                                Slope  Length, Feet'
Figure 2-6.     Slope Effect Chart for Areas Where Figure 3-5 Is Not Applicable
              (USDA 1974).

NOTE:   The dashed lines  represent estimates for slope dimensions beyond the
         range of lengths and steepnesses for which data are available.
                                     H-6

-------
                                           TABLE 2-4

                             C" VALUES FOR PERMANENT PASTURE,
                                 RANGELAND, AND (OLE LAND
Vegetal canopy
Type and height
of raised canopy*"
No appreciable canopy
Canopy of tall weeds or
short brush
(0.5m fall height)
Appreciable brush or
brushes
(2 m fall height)
Trees but no appreciable
low brush
(4m fall height)
Canopy
covert
(%)

25
50
75
25
50
75
25
50
75
Cover that contacts the surface/Percent groundcover
Typed
G
W
G
W
G
W
G
W
G
W
G
W
G
W
G
W
G
W
G
W
0
0.45
0.45
0.36
0.36
0.26
0.26
0.17
0.17
0.40
0.40
0.34
0.34
0.28
0.28
0.41
0.42
0.39
0.39
0.36
0.36
20
0.20
0.24
017
0.20
0.13
0.16
0.10
0.12
0.18
0.22
0.16
0.19
0.14
0.17
0.19
0.23
0.18
0.21
0.17
0.20
40
0.10
0.15
0.09
0.13
0.07
0.11
0.06
0.09
0.09
0.14
0.085
0.13
0.08
0.12
0.10
0.14
0.09
0.14
0.09
0.13
60
0.042
0.090
0.038
0.082
0.035
0.075
0.031
0.067
0.040
0.085
0.038
0.081
0.036
0.077
0.041
0.087
0.040
0.085
0.039
0.083
80
0.013
0.043
0.012
0.041
0.012
0.039
0.011
0.038
0.013
0.042
0.012
0.041
0.012
0.040
O.U13
0.042
0.013
0.042
0.012
0.041
95-100
0.003
0.011
0.003
0.011
0.003
0.011
0.003
0.011
0.003
0.011
0.003
0.011
0.003
0.011
0.003
0.011
0.003
0.011
0.003
0.011
Source: Wischemier 1972.

a All values shown assume: (1) random distribution of mulch or vegetation and (2) mulch of appreciable depth
  where it exists.
b Average fall height of waterdrops from canopy to soil surface: m = meters.
c Portion of total-area surface that would be hidden from view by canopy in a vertical projection (a bird's-eye
  view).
<* G:  Cover at surface is grass, grass! ike plants, decaying compacted duff, or litter at least 5 cm (2 in.) deep.
  W:  Cover at surfact is mostly broadleaf herbaceous plants (as weeds) with little laterial-root network near the
      surface and/orundecayed residue.
                                              H-7

-------
                                     TABLE 2-5

                           'C VALUES FOR WOODLAND
Stand condition
Well stocked
Medium stocked
Poorly stocked
Tree canopy
percent of area'
100-75
70-40
35-20
Forest litter
percent of area*>
100-90
85-75
70-40
Undergrowth^
Managed0
Unmanagedd
Managed
Unmanaged
Managed
Unmanaged
"C" factor
0.001
0.003-0.011
0.002-0.004
0.01-0.04
0.003-0.009
0.02-0.09*
Source: Wischemier 1972.

a  When tree canopy is less than 20 percent, the area will be considered as grass land or cropland
   for estimating soil loss.
b  Forest litter is assumed to be at least 2 in. deep over the percent ground surface area covered.
c  Undergrowth is defined as shrubs, weeds, grasses, vines, etc., on the surface area not
   protected by forest litter. Usually found under canopy openings.
<*  Managed - grazing and fires are controlled.
   Unmanaged - stands that are overgrazed or subjected to repeated burning.
«  For unmanaged woodland with litter cover of less than 75 percent, C values should be derived
   by taking 0.7 of the appropriate values in Table 3-4. The factor of 0.7 adjusts for much higher
   soil organic matter on permanent woodland.
                                         H-8

-------
where
     Rt   s   the total storm rainfall, (in, cm).
     Sw   -   water retention factor, (in, cm).

     The value of Sw, the water retention factor, is obtained as follows (Mockus
1972):
                                  -10 a                               (2-23)
where

     Sw   »   water retention factor, (in, cm).
     CN   a   the SCS Runoff Curve Number, (dimensionless, see Table 2-6).
     a    a   conversion constant (1.0 English, 2.54 metric).

     The CN factor is determined by the type of soil at the site, its condition, and
other parameters that establish a value indicative of the tendency of the soil to
absorb and hold  precipitation or to allow precipitation to run off the surface. The
analyst can obtain CN values of uncontrolled hazardous waste sites from Table 2-6.

     The peak runoff rate, qp, is determined as follows (Haith 1980):

                                   aARtQr                             (2.24)
                                Tr(Rt - 0.2Sw)
where
     qp   »   the peak runoff rate, (ft3/sec, m3/sec).
     a    a   conversion constant, (1.01 English, 0.028 metric).
     A    a   contaminated area, (acres, ha).
     Rt   a   the total storm rainfall, (in, cm).
     Or   a   the depth of runoff from the watershed area, (in, cm).
     Tr   a   storm duration, (hr).
                                    H-9

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                                  TABLE 2-6

                          RUNOFF CURVE NUMBERS
Soil Group
A
B
C
D
Description
Lowest runoff potential: Includes deep
sands with very little silt and clay, also
deep, rapidly permeable loess
(infiltration rate = 8-12 mm/h).
Moderately low runoff potential : Mostly
sandy soils less deep than A, and loess less
deep or less aggregated than A, but the
group as a whole has above-average
infiltration after thorough wetting
(infiltration rate = 4-8 mm/h).
Moderately high runoff potential:
Comprises shallow soils and soils
containing considerable clay and colloids,
though less than those of group 0. The
group has below-average infiltration
after presaturation (infiltration rate = 1-
4 mm/h).
Highest runoff potential: Includes mostly
clays of high swelling percent, but the
group also includes some shallow soils
with nearly impermeable subhorizons
near the surface (infiltration rate = 0-1
mm/h).
Site Type
Overall
site*
59
74
82
86
Road/right
of way
74
84
90
92
Meadow
30
58
71
78
Woods
45
66
77
83
Source: Adapted from Schwab et al. 1966.

* Values taken from farmstead category, which is a composite including buildings, farmyard,
  road, etc.
                                    H-10

-------
     Sw   =   water retention factor, (in, cm).

Dissolved/Sorbed Contaminant Release

     As discussed in  Mills et  al.  (1985), the analyst can  predict the degree  of
soil/water partitioning expected for given compounds once the storm event soil loss
has been calculated with the following equations.  First, the amounts of absorbed
and dissolved substances are determined, using the equations presented below as
adapted from Haith (1980):

                        Ss = [1/0 + ec/Kd8)](Cj)(A)                     (2-25)
                                   and
                        Ds = [1/0  + Kd8/ec)](Ci)(A)                    (2-26)

where

     S«    s   sorbed substance quantity, (kg, Ib).
     8C   =   available water capacity of the top cm of soil (difference between
              wilting point and field capacity), (dimensionless).
     K
-------
can be estimated according to procedures described in Lyman etal. (1982).  Initially,
the octanol-water partition coefficient can be estimated based on the substance's
molecular structure. If necessary, this value can be used, in turn, to estimate either
solubility in water or bioconcentration factor.

     After calculating the amount of sorbed and dissolved contaminant, the total
loading to the receiving waterbody is calculated as follows (adapted from Haith
1980):

                           PXj =: [Y(S)E/100B]S$                        (2-27)
                                    and
                              PQi = [Qr/RtJ Ds                          (2-28)
where
     PXJ   =   sorbed substance loss per event, (kg, Ib).
     Y($)E >   sediment yield, (tons per event, metric tons).
     6    3   soil bulk density, (g/cm3).
     Ss    =   sorbed substance quantity, (kg, Ib).
     PQi  «   dissolved substance loss per event, (kg, Ib).
     Qr   *   total storm runoff depth, (in, cm).
     Rt    =   total storm rainfall, (in, cm).
     Ds   ~   dissolved substance quantity, (kg, Ib).

     PXJ and PQi can be converted to mass per volume terms for use in estimating
     contaminant concentration  in the  receiving waterbody by dividing by the site
     storm runoff volume (Vr, see Equation 2-21).
                                    H-12

-------
                                REFERENCES

 Delos C. G., Richardson, W.L, DePinto J. V., et al. 1984. Technical guidance manual
 for performing wasteload allocations, book II:   streams and  rivers.  U.S.
 Environmental Protection Agency.  Office of Water Regulations  and Standards.
.Water Quality Analysis Branch. Washington, D.C. (Draft Final.)

 Haith D. A.,  1980. A mathematical model for estimating pesticide  losses in  runoff.
 Journal of Environmental Quality. 9(3):428-433.

 Lyman, W. J., Reehl W. F., Rosenblatt D. H., 1982. Handbook of chemical property
 estimation methods. New York. McGraw-Hill.

 Mills W. B.,  Dean J. D., Porcella D. B., et al. 1982. Water quality assessment:  a
 screening  procedure  for toxic and conventional pollutants:  parts 1, 2,  and 3.
 Athens, GA:  U.S. Environmental Protection Agency.  Environmental  Research
 Laboratory.  Office of Research and Development. EPA/600/6-85/002 a, b, c.

 Schwab G. 0., Frevert R. K., Edminster T. W., Barnes  K. K.,  1966.  Soil and water
 conservation engineering. 2ndedn. New York: John Wiley and Sons.

 USDA.  1974. Department of Agriculture.  Universal soil loss equation. Agronomy
 technical note no.  32.  Portland, Oregon.  U.S. Soil Conservation Service.  West
 Technical Service Center.

 Williams J. R., 1975.  Sediment-yield prediction with the universal equation using
 runoff energy factor.  In present and prospective  technology  for predicting
 sediment yields and sources. U.S. Department of Agriculture.  ARS-S-40.

 Wischmeier W.  H.,  1972.  Estimating the cover and management factor on
 undisturbed areas.  U.S. Department of Agriculture.  Oxford, MS:  Proceedings of
 the USDA Sediment Yield Workshop.
                                   H-13

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                           OSWER DIRECTIVE 9502.00-60
              INTERIM FINAL

RCRA FACILITY INVESTIGATION (RFI) GUIDANCE

             VOLUME IV OF IV
          CASE STUDY EXAMPLES
            EPA 530/SW-89-031
                 MAY 1989
         WASTE MANAGEMENT DIVISION
            OFFICE OF SOLID WASTE
     U.S. ENVIRONMENTAL PROTECTION AGENCY

-------
                                ABSTRACT
     On November 8,  1984, Congress enacted the Hazardous and Solid Waste
Amendments (HSWA) to RCRA. Among the most significant provisions of HSWA are
§3004(u), which requires corrective action  for releases of hazardous waste or
constituents  from solid waste management units at hazardous waste treatment,
storage and  disposal facilities seeking final RCRA permits;  and §3004(v), which
compels corrective action for  releases that have migrated beyond the facility
property boundary.  EPA will be promulgating rules to implement the corrective
action provisions of HSWA, including requirements for release investigations  and
corrective measures.

     This document, which is presented in  four volumes, provides guidance to
regulatory agency personnel on overseeing owners or operators of hazardous waste
management facilities in the conduct of the second phase of the RCRA Corrective
Ac+ion Program, the RCRA Facility Investigation (RFI). Guidance is provided for the
development and performance of an investigation by the facility owner or operator
based on determinations made by the regulatory agency as expressed in  the
schedule of a permit or in  an enforcement order issued under §3008(h), §7003,
and/or §3013. The purpose  of the RFI is to obtain information to fully characterize
the nature,  extent and  ratt of migration of releases of hazardous waste or
constituents and to interpret this information to determine whether interim
corrective measures and/or a Corrective Measures Study may be necessary.

-------
                               DISCLAIMER
     This document is intended to assist Regional and State personnel in exercising
the discretion conferred by regulation in developing requirements for the conduct
of RCRA Facility Investigations (RFIs) pursuant to 40 CFR 264. Conformance with this
guidance is expected to result in the development of RFIs that meet the regulatory
standard of adequately detecting and characterizing the nature and extent of
releases.  However, EPA will not necessarily limit acceptable RFIs to those that
comport with the guidance set forth herein.  This document is not a regulation (i.e.,
it does not establish a standard of conduct which has the force of law) and should
not be used as such. Regional and State personnel must exercise their discretion in
using this guidance document as well as other relevant information in determining
whether an RFI meets the regulatory standard.

     Mention of company or product names in  this document should not be
considered as an endorsement by the U.S. Environmental Protection Agency.
                                    ii

-------
              RCRA FACILITY INVEST1ATION (RFI) GUIDANCE
                            VOLUME IV
                       CASE STUDY EXAMPLES
                        TABLE OF CONTENTS
SECTION                                                     PAGE
ABSTRACT                                                        i
DISCLAIMER                                                      ii
TABLE OF CONTENTS                                               iii
TABLES                                                        vii
FIGURES                                                         ix
LIST OF ACRONYMS                                               xii
                              in

-------
                VOLUME IV CONTENTS (Continued)
SECTION

14.0

  14.1

  14.2

15.0
INTRODUCTION

   USE OF CASE STUDIES

   ORGANIZATION OF VOLUME IV

CASE STUDIES
  CASESTUDY1.
  CASE STUDY 2.
  CASE STUDY 3.
  CASE STUDY 4.
  CASE STUDY 5.
  CASE STUDY 6.
  CASE STUDY 7.
  CASE STUDY 8.
  CASE STUDY 9.
  CASE STUDY 10.
  CASE STUDY 11.
          USE OF THE 40 CFR 261 LISTING BACKGROUND
          DOCUMENTS FOR SELECTING MONITORING
          CONSTITUENTS

          ESTIMATION OF DEGRADATION POTENTIAL OF
          CONTAMINANTS IN SOIL

          SELECTION AND EVALUATION OF A SOIL
          SAMPLING SCHEME

          SAMPLING OF LEACHATE FROM A DRUM
          DISPOSAL AREA WHEN EXCAVATION AND
          SAMPLING OF DRUMS IS NOT PRACTICAL

          USE OF QUALITY ASSURANCE/QUALITY
          CONTROL (QA/QC) AND DATA VALIDATION
          PROCEDURES

          PRESENTATION OF DATA COLLECTED DURING
          FACILITY INVESTIGATIONS

          CORRELATION OF CONTAMINANT RELEASES
          WITH A SPECIFIC WASTE MANAGEMENT UNIT
          USING GROUND-WATER DATA

          WASTE SOURCE CHARACTERIZATION FROM
          TOPOGRAPHIC INFORMATION

          SELECTION OF GROUND-WATER MONITORING
          CONSTITUENTS AND INDICATOR PARAMETERS
          BASED ON FACILITY WASTE STREAM
          INFORMATION

          USING WASTE REACTION PRODUCTS TO
          DETERMINE AN APPROPRIATE MONITORING
          SCHEME

          CORRECTIVE MEASURES STUDY AND THE
          IMPLEMENTATION OF INTERIM MEASURES
PAGE

14-1

14-1

14-1

15-1

15-1



15-6


15-10


15-14



15-19



15-29


15-43



15-47


15-50




15-54



15-58
                             IV

-------
                VOLUME IV CONTENTS (Continued)
SECTION

  CASE STUDY 12.



  CASE STUDY 13.



  CASE STUDY 14.




  CASE STUDY 15.


  CASE STUDY 16.



  CASE STUDY 17.




  CASE STUDY 18.

  CASE STUDY 19.

  CASE STUDY 20.



  CASE STUDY 21.



  CASE STUDY 22.


  CASE STUDY 23.


  CASE STUDY 24.
                                     PAGE

USE OF AERIAL PHOTOGRAPHY TO IDENTIFY   15-63
CHANGES IN TOPOGRAPHY INDICATING
WASTE MIGRATION ROUTES

IDENTIFICATION OF A GROUND-WATER       15-68
CONTAMINANT PLUME USING INFRARED
AERIAL PHOTOGRAPHY

USE OF HISTORICAL AERIAL PHOTOGRAPHS    15-74
AND FACILITY MAPS TO IDENTIFY OLD WASTE
DISPOSAL AREAS AND GROUND-WATER FLOW
PATHS

USING SOIL CHARACTERISTICS TO ESTIMATE    15-78
MOBILITY OF CONTAMINANTS

USE OF LEACHING TESTS TO PREDICT         15-87
POTENTIAL IMPACTS OF CONTAMINATED SOIL
ON GROUND WATER

USE OF SPLIT-SPOON SAMPLING AND ON-SITE   15-97
VAPOR ANALYSIS TO SELECT SOIL SAMPLES
AND SCREENED INTERVALS FOR MONITORING
WELLS

CONDUCTING A PHASED SITE INVESTIGATION   15-105

MONITORING BASEMENT SEEPAGE           15-110

USE OF PREDICTIVE MODELS TO SELECT       15-114
LOCATIONS FOR GROUND-WATER
MONITORING WELLS

MONITORING AND CHARACTERIZING         15-119
GROUND-WATER CONTAMINATION WHEN
TWO LIQUID PHASES ARE PRESENT

METHODOLOGY FOR CONSTRUCTION OF      15-124
VERTICAL FLOW NETS

PERFORMING A SUBSURFACE GAS           15-137
INVESTIGATION

USE OF A SUBSURFACE GAS MODEL IN         15-144
ESTIMATING GAS MIGRATION AND
DEVELOPING MONITORING PROGRAMS

-------
                VOLUME IV CONTENTS (Continued)
SECTION

  CASE STUDY 25.
  CASE STUDY 26.


  CASE STUDY 27.


  CASE STUDY 28.




  CASE STUDY 29.


  CASE STUDY 30.



  CASE STUDY 31.
USE OF METEOROLOGICAL/EMISSION
MONITORING DATA AND DISPERSION
MODELING TO DETERMINE CONTAMINANT
CONCENTRATIONS DOWNWIND OF A LAND
DISPOSAL FACILITY

USE OF METEOROLOGICAL DATA TO DESIGN
AN AIR MONITORING NETWORK

DESIGN OF A SURFACE WATER MONITORING
PROGRAM

USE OF BIOASSAYS AND BIOACCUMULATION
TO ASSESS POTENTIAL BIOLOGICAL EFFECTS
OF HAZARDOUS WASTE ON AQUATIC
ECOSYSTEMS

SAMPLING OF SEDIMENTS ASSOCIATED WITH
SURFACE RUNOFF

SAMPLING PROGRAM DESIGN FOR
CHARACTERIZATION OF A WASTEWATER
HOLDING IMPOUNDMENT

USE OF DISPERSION ZONE CONCEPTS IN THE
DESIGN OF A SURFACE WATER MONITORING
PROGRAM
PAGE

15-153
15-158


15-165


15-174




15-185


15-188



15-194
                             VI

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                            TABLES (Volume IV)
NUMBER                                                          PAGE
   14-1     Summary of Points Illustrated                             14-2
   15-1     Uses and Limitations of the Listing Background Documents   15-2
   15-2     Results of Original Surface Soil and Tap Water Analyses      15-23
   15-3     Laboratory QC Results                                   15-25
   15-4     Field QC Results                                         15-26
   15-5     Summary of Data Collected                               15-33
   15-6     Typical Methods for Graphically Presenting Data Collected    15-42
           During Facility Investigations
   15-7     Indicator Parameters                                    15-52
   15-8     Results of Monitoring Well Sampling                       15-55
   15-9     Average Values of Parameters in Ground Water and Stream   15-73
           Samples
   15*10   Relative Mobility of Solutes                               15-82
   15-11    HEA Criteria, Constituent Concentrations and Relevant      15-91
           Physical/Chemical Property Data For Constituents
           Observed At Site
   15-12   Leaching Test Results (mg/l)                               15-93
   15-13   Ground-Water Elevation Summary Table Phase II            15-127
   15-14   Model Results                                          15-149
   15-15   Summary of Onsite Meteorological Survey Results           15-156
   15-16   Relationship of Dissolved and Sorbed Phase Pollutant        15-169
           Concentrations to Partition Coefficient and Sediment
           Concentration
   15-17   Parameters Selected for Surface Water Monitoring Program   15-170
   15-18   Selected Surface Water Monitoring Stations and Rationale    15-171
                                    VII

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                      TABLES (Volume IV - Continued)
NUMBER                                                         PAGE
   15-19   Mean Concentrations (jig/0 of Organic Substances and       15-178
           Trace Metals in Leachate and Surface Waters
   15-20   Mean Sediment Concentrations (pg/kg Dry Wt) of Organic    15-179
           Substances and Trace Metals
   15-21    Mean Liver Tissue Concentrations (iig/kg Wet Wt) of         15-180
           Organic Substances and Trace Metals
   15-22   Mean LCso and ECso Values (Percent Dilution) for           15-181
           Surface-Water Bioassays
   15-23   Relative Toxicity of Surface-Water Samples                 15-182
   15-24   Arsenic and Lead Concentrations (ppm) in Runoff           15-187
           Sediment Samples
   15-25   Summary of Sampling and Analysis Program for             15-191
           Wastewater Impoundment
   15-26   Relationship of Dissolved and Sorbed Phase                 15-198
           Contaminant Concentrations to Partition
           Coefficient and Sediment Concentration
   15-27   Parameters Selected For Surface Water                     15-199
           Monitoring Program
   15-28   Selected Surface Water Monitoring Stations and             15-200
           Selection Rationale
                                   VIII

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FIGURES (Volume IV)
NUMBER
15-1
15-2
15-3
15-4
15-5
15-6
15-7
15-8
15-9
15-10
15-11
15-12
15-13
15-14
15-15
15-16
15-17
15-18
15-19
15-20

Results of Laboratory Bench Tests for Pesticide
Degradation
Isoconcentration Map of the Lead Concentrations in ppm
Around the Smelter
Schematic Diagram of Gas Control System Utilized at Pit
Schematic Drawing of Wireline Drill Bit and Reaming Shoe
Map of the Smelter Site and Associated Tailings Ponds
Locations of Copper Leach Plant and Waste Storage Ponds
Schematic of Surface Water System
Ground-Water Flowlines Based on Measured Water Levels
Selected Surface Water Quality Parameters at Key Stations
Changes in Suifate Over Time at Selected Wells Located
Within the Site
Field Sketch of Tailings Trench T-3
Depth vs. Concentration Profiles for Selected Variables
for Borehole 88A
Location of Ground-Water Monitoring Wells
Site Map Showing Waste Disposal Areas
Site Map and Monitoring Well Locations
Ground-Water Elevations and Flow Directions in
Upper Limestone Aquifer
October 1983 Aerial Photograph of Land Disposal Facility
Aerial Photograph Interpretation Code
February 1984 Aerial Photograph of Land Disposal Facility
Facility Plan View
PAGE
15-8
15-13
15-16
15-17
15-30
15-31
15-35
15-36
15-37
15-38
15-40
15-41
15-44
15-48
15-56
15-60
15-65
15-66
15-67
15-69
       IX

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                      FIGURES (Volume IV - Continued)
NUMBER                                                         PAGE
   15-21    Generalized Geologic Cross-Section                       15.71
   15-22    Infrared Aerial Photograph of the Site                     15-72
   15-23    Site Layout: LWDA-2, SDWA-2 and Stream Channel         15-76
           Identified Through Use of Aerial Photograph Analysis
   15-24    Schematic Cross-Section of Waste Disposal Site              15-80
   15-25    Hypothetical Adsorption Curves for a) Cations and          15-83
           b) Anions Showing Effect of pH and Organic Matter
   15-26    Schematic Diagram Showing Plumes of Total Dissolved       15-86
           Solids (TDS>, Total Organic Halogens (TOX) and Heavy
           Metals Downgradient of Waste Disposal Site
   15-27    Facility Map Showing Soil Boring and Well Installation       15-88
   15-28    Facility Map Showing Ground-Water Contours              15-90
   15-29    Site Plan Showing  Disposal Areas and Phase I Well           15-98
           Locations
   15-30    Geologic Cross-Section Beneath Portion of Site              15-100
   15-31    Ground-Water Elevations in November 1984               15-101
   15-32    Example of Borehole Data Including HNU and              15-102
           OVA/GC Screening
   15-33    Proposed Phase II Soil Borings                            15-107
   15-34    Proposed Phase II Monitoring Wells                       15-108
   15-35    Geologic Cross-Section Beneath Sitt                       15-111
   15-36    Estimated Areal Extent of Hypothetical Plumes              15-116
           from Four Wells
   15-37    Consideration of Solute Migration Rates in Siting           15-118
           Sampling Wells
   15-38    Well Locations and Plant Configuration                    15-121
   15-39    Behavior of Immiscible Liquids of Different Densities        15-123
           in a Complex Ground-Water Flow Regime

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                      FIGURES (Volume IV • Continued)
NUMBER                                                         PAGE
   15-40   Top of Lowest Till Contour Map and Location of            15-125
           Vertical Flow Net
   15-41    Recharge/Discharge Areas and Flow Directions              15-130
   15-42   Vertical Flow Net T-T'                                    15-132
   15-43   Site Plan                                               15-138
   15-44   Gas Monitoring Well                                    15-140
   15-45   Facility Map                                            15-145
   15-46   Uncorrected Migration Distances for 5 and 1.25%           15-147
           Methane Concentrations
   15-47   Correction Factors for Landfill Depth Below Grade           15-148
   15-48   Impervious Correction Factors (ICF) for Soil Surface           15-150
           Venting Condition Around Landfill
   15-49   Landfill Perimeter Gas Collection System Wells              15-152
   15-50   Site Map Showing Location of Meteorological Sites A and B   15-154
   15-51    Site Plan and Locations of Meteorological Stations           15-159
   15-52   Sampling Station Locations for Surface Water Monitoring    15-167
   15-53   Site Plan and Water Sampling Locations                   15-176
   15-54   Bioassay Responses to Surface Water Samples              15-183
   15-55   Surface Water and Sediment Sample Locations              15-186
   15-56   Schematic of Wastewater Holding Impoundment           15-190
           Showing Sampling Locations
   15-57   Sampling Station Locations for Surface Water              15-196
           Monitoring
                                   XI

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                           LIST OF ACRONYMS
AA
Al
ASCS
ASTM
BCF
BOO
CAG
CPF
CBI
CEC
CERCLA

CFR
OR
CM
CMI
CMS
COD
COLIWASA
DNPH
DO
DOT
ECD
EM
EP
EPA
FEMA
FID
Foe
FWS
GC
GC/MS
GPR
HEA
HEEP
HPLC
HSWA
HWM
ICP
ID
Kd
Koc
Kow
LEL
MCL
MM5
MS/MS
NFIP
NIOSH
Atomic Absorption
Soil Adsorption Isotherm Test
Agricultural Stabilization and Conservation Service
American Society for Testing and Materials
Bioconcentration Factor
Biological Oxygen Demand
EPA Carcinogen Assessment Group
Carcinogen Potency Factor
Confidential Business Information
Cation Exchange Capacity
Comprehensive Environmental Response, Compensation, and
Lability Act
Code of Federal Regulations
Color Infrared
Corrective Measures
Corrective Measures Implementation
Corrective Measures Study
Chemical Oxygen Demand
Composite Liquid Waste Sampler
Dmitrophenyl Hydrazine
Dissolved Oxygen
Department of Transportation
Electron Capture Detector
Electromagnetic
Extraction Procedure
Environmental Protection  Agency
Federal Emergency Management Agency
Flame lonization Detector
Fraction  organic carbon in soil
U.S. Fish  and Wildlife Service
Gas Chromatography
Gas Chromatography/Mass Spectroscopy
Ground Penetrating Radar
Health and Environmental Assessment
Health and Environmental Effects Profile
High Pressure Liquid Chromatography
Hazardous and Solid Waste Amendments (to RCRA)
Hazardous Waste Management
Inductively Coupled (Argon) Plasma
Infrared  Detector
Soil/Water Partition Coefficient
Organic Carbon Absorption Coefficient
Octanol/Water Partition Coefficient
Lower Explosive Limit
Maximum Contaminant Level
Modified Method 5
Mass Spectroscopy/Mass Spectroscopy
National Flood Insurance Program
National Institute for Occupational Safety and Health
                                   XII

-------
                      LIST OF ACRONYMS (Continued)
NPDES
OSHA
OVA
PID
pKa
ppb
ppm
PUF
PVC
QA/QC
RCRA
RFA
RfD
RFI
RMCL
RSO
SASS
SCBA
SCS
SOP
SWMU
TCLP
TEGD
TOC
TOT
TOX
uses
USLE
UV
VOST
VSP
WQC
National Pollutant Discharge Elimination System
Occupational Safety and Health Administration
Organic Vapor Analyzer
Photo lonization Detector
Acid Dissociation Constant
parts per billion
parts per mi 11 ion
Polyurethane Foam
Polyyinyl Chloride
Quality Assurance/Quality Control
Resource Conservation and Recovery Act
RCRA Facility Assessment
Reference Dose
RCRA Facility Investigation
Recommended Maximum Contaminant Level
Risk Specific Dose
Source Assessment Sampling System
Self Contained Breathing Apparatus
Soil Conservation Service
Standard Operating Procedure
Solid Waste Management Unit
Toxicity Characteristic Leaching Procedure
Technical Enforcement Guidance Document (EPA, 1986)
Total Organic Carbon
Time of travel
Total Organic Halogen
United States Geologic Survey
Universal Soil Loss Equation
Ultraviolet
Volatile Organic Sampling Train
Verticle Seismic Profiling
Water Quality Criteria
                                   XIII

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14.0 INTRODUCTION

14.1 Use of Case Studies

     This document, Volume IV of the RCRA Facility Investigation (RFI) Guidance,
contains case  studies selected to illustrate various concepts and procedures
presented in Volumes I, II, and III.  These case studies are  provided to  explain,
through example, how various tasks can be conducted during RFIs. The case studies
also identify some of the potential problems that can occur if the RFI sampling and
analytical programs are not carefully designed and executed.   The case studies,
however, should not be used as the primary source of guidance for RFI program
design and conduct. Instead, Volumes I, II and III should be consulted. The studies
do  not necessarily address details specific to individual  facilities, and omission of
certain RFI tasks should not be interpreted as an indication that such tasks are
unnecessary or of less significance. Most of the case studies are based on actual
sites.  In some cases, existing data have been supplemented with hypothetical data
to illustrate a particular point.

14.2 Organization of Volume IV

     The case  studies are organized primarily  by the order in  which the subject
matter was presented in Volumes I, II and III.  In some cases, individual case studies
present materials relevant to more than one topic or media. Table 14-1 lists the
points illustrated and identifies the case studies which provide information relevant
to these points.

     The following general format was used as appropriate for each case study:

     •   Tit*
     •   Identification of points illustrated
     •   Introduction/Background
     •   Facility description
     •   Program design/Data collection
     •   Program results/Data analysis
     •   Case discussion.
                                    14-1

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                                    TABLE 14-1

                         SUMMARY OF POINTS ILLUSTRATED
                       POINTS ILLUSTRATED
CASE STUDY
  NUMBER
SELECTION OF MONITORING CONSTITUENTS
   •   Us* of 40 CFR Part 261 Listing Background Documents in selecting
       monitoring constituents
   e   Consideration of degradation as a factor in identifying monitoring
       constituents
SAMPLING SCHEMES
   e   Selection of a sampling scheme that appropriately characterizes soil
       contamination
   e   Evaluation of the effectiveness of a sampling scheme using
       statistical analyses
   e   Us* of release monitoring/leachate collection to characterize wastes
       when the actual waste stream is inaccessible, as in the case of buried
       drums
     3

     3

     4
QUAUTY ASSURANCE AND CONTROL
   •   Use of quality assurance and control and data validation procedures
DATA PRESENTATION
   *   Techniques for presenting data for facility investigations involving
       multimedia contamination
WASTE CHARACTERIZATION
   *  Correlation of a contaminant release with a specific waste
      management unit using ground-water data
   *  Use of site topographic information to s*l*ct test boring and
      monitoring well locations at facilities where large volumes of waste
      have been disposed
   *  Use of waste stream information to select indicator parameters and
      monitoring constituents in a ground-water monitoring program to
      minimize the number of constituents that must be monitored
   •  Us* of information on possible wast* reaction products in designing
      a ground-water monitoring program	
     7

     8
    10
CORRECTIVE MEASURES INCLUDING INTERIM MEASURES
   •   Us* of biodegradation and removal for interim corrective measures
   •   Corrective action and th* implementation of interim corrective
       measures
     2
    11
AERIAL PHOTQgU PHY
   •   Us« of Mhal photographs to identify actual and potential wast*
       migration routes and areas requiring comtctiv* action
   •   identification of a ground-wat*r contaminant plum* using infrared
       aerial photography
   •   Us* of historical a*rial photographs and facility maps to identify old
       wast* disposal areas and ground-water flow paths	
    12

    13

    14
                                      14-2

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                                    TABLE 14-1

                    SUMMARY OF POINTS ILLUSTRATED (continued)
                        POINTS ILLUSTRATED
CASE STUDY
  NUMBER
SOIL
   •   Use of soil characteristics to estimate mobility of contaminants in
       soil
   •   Effects of degradation in determining the fate of a contaminant in
       soil
   •   Use of leaching tests to predict potential impacts of contaminated
       soils on ground water	
    15

     2

    16
GROUND WATER
   •   Use of split-spoon sampling and organic vapor monitoring to select
       screened intervals for ground-water monitoring
   •   Development of a two-phase boring program to investigate
       ground-water contamination
   e   Use of basement monitoring to estimate contaminant migration
   e   Use of mathematical models to determine locations of ground-
       water monitoring wells
   •   Monitoring and characterization of ground-water contamination
       when two liquid phases are present
   e   Methodology for construction of vertical flow nets  	
    17

    18

    19
    20

    21

    22
SUBSURFACE GAS
   e   Design of a phased monitoring program to adequately characterize
       subsurface gas migration
   e   Use of predictive models to estimate extent of subsurface gas
       migration	
    23

    24
AIR
       Use of dispersion modeling and meteorological/emissions
       monitoring data to estimate downwind contaminant
       concentrations
       Design of an upwind/downwind monitoring program when
       multiple sources are involved	
    25

    26
SURFACE WATER
   e   Use of existing site-specific data to design a surface water
       monitoring program
   •   Use of bioassays and bioaccumulation studies to assess potential
       biologkal effects of off-site contaminant migration
   e   Use of sediment sampling to indicate off-site contaminant
       migration via surface runoff
   e   Design of a sampling program to account for three-dimensional
       variations in contaminant distribution
   e   Use of dispersion zone concepts in the design of a surface water
       monitoring program                         	
    27

    28

    29

    30

    31
                                       14-3

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15.0  CASE STUDIES

CASE STUDY 1: USE OF THE 40 CFR 261 LISTING BACKGROUND DOCUMENTS FOR
              SELECTING MONITORING CONSTITUENTS

Point Illustrated

     •   The 40 CFR 261 Listing Background Documents can be of direct help in
         selecting monitoring constituents.

Introduction

     The RCRA Hazardous Waste Listing Background Documents developed for the
identification and listing of hazardous wastes under 40 CFR Part 261 represent one
source of potential information on waste-specific constituents and their physical
and chemical characteristics.  The documents contain  information on the
generation, composition, and management of listed waste streams from generic
and industry-specific sources. In addition to identifying hazardous constituents that
are present in the wastes, the documents may  also provide data on  potential
decomposition products.  In some background documents, migratory potentials are
discussed and exposure pathways are identified.

     Appendix B of the Listing Document provides more detailed information on
the fate and transport of hazardous constituents.  Major physical and chemical
properties of selected constituents are listed, including molecular weights,  vapor
pressures and solubilities, octanol-water partition coefficients, hydrolysis  rates,
biodegradation rates, and volatilization rates.  Another section of the appendix
estimates tht migratory potential and environmental persistence of selected
constituents based on a conceptual model of disposal in an  unconfined landfill or
lagoon.

     The appropriate uses and limitations of the Listing Documents are outlined in
Table 15-1.  A case study on how the Documents may be used in investigating a
release follows.
                                   15-1

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                                      TABLE 15-1

            USES AND LIMITATIONS OF THE LISTING BACKGROUND DOCUMENTS
                   Uses
                Limitations
•  identifies the hazardous constituents for
   which a waste was listed
•  Applicable only for listed hazardous wastes
e  in some cases, provides information on
   additional hazardous constituents which
   may be present in a listed waste
    Industry coverage may be limited in scope
    (e.g., the wood preserving industry). Listing
    Documents only cover organic
    preservatives, not inorganics (15 percent of
    the industry), such as inorganic arsenic salts
   In some cases, identifies decomposition
   products of hazardous constituents
    Data may not be comprehensive (i.e., not all
    potentially hazardous constituents may be
    identified). Generally, limited to the most
    toxic constituents common to the industry
    as a whole
   Provides overview of industry; gives
   perspective on range of waste generated
   (both quantity and general characteristics)
    Data may not be specific. Constituents and
    waste characteristic data often represent an
    industry average which encompases many
    different types of production processes and
    waste treatment operations
   May provide waste-specific characteristics
   data such as density, pH, and teachability
    Listing Documents were developed from
    data/reports available to EPA at the time,
    resulting in varying levels of detail for
    different documents
   May provide useful information on the
   migratory potential, mobility, and
   environmental persistence of certain
   hazardous constituents
    Hazardous waste listings are periodically
    updated and revised, yet this may not be
    reflected in the Listing Documents
   May list physical and chemical properties of
   selected constituents
    Listing Documents for certain industries
    (e.g., the pesticides industry) may be subject
    to CBI censorship due to the presence of
    confidential business information. In such
    cases, constituent data may be unavailable
    (i.e., expurgated from the document)
                                         15-2

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Facility Description

     The facility is a wood preserving plant located in the southeast.  The facility
uses a steaming process to treat southern pine and timber.   Contaminated vapors
from the wood treating  process are condensed and  transported to an  oil/water
separator to reclaim free oils and preserving chemicals.  The bottom sediment
sludge from this  and subsequent waste water treatment units  is a RCRA listed
hazardous waste: K001.

Use of Listing Background Documents

     Due to the presence of small, but detectable, levels of phenolic compounds in
the ground water of an adjacent property, a RCRA Facility Assessment (RFA) was
conducted and it was determined that a release from the facility had occurred. The
owner was instructed to conduct a RCRA Facility Investigation (RFI).  Before
embarking  on an extensive waste sampling and  analysis  program,  the owner
decided to explore existing sources of information in order to  better focus analytical
efforts.

     The owner obtained  a  copy of the Wood Preserving  Industry  Listing
Background Document from the RCRA Docket at EPA Headquarters.  He also had
available a copy of 40CFR Part 261, Appendix VII, which identifies the hazardous
constituents for which his waste was listed.  For K001, he  found the following
hazardous constituents listed: pentachlorophenol, phenol, 2-chlorophenol,  p-
chloro-m-cresol,  2,4-dimethylphenyl, 2,4-dinitrophenol, trichlorophenols,
tetrachlorophenols, 2,4-dichlorophenol, creosote, chrysene,  naphthalene,
fluoranthenc, benz(b)fluoranthene,  benz(a)pyrene, ideno(1,2,3-cd)pyrene,
benz(a)anthractne,dibenz(a)anthracene, and acenaphthaiene.

     From the Summary of Basis for Listing section in the Listing Document, the
owner found that phenolic compounds are associated with waste generated from
the use of pentachlorophenol-based wood preservatives, and that polynuciear
aromatic hydrocarbons (PAHs) (i.e., chrysene through acenaphthaiene in Appendix
VII) are associated with  wastes from  the use of creosote-based preservatives.
Examining the facility records, he determined that pentachlorophenol had been the
                                  15-3

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sole preservative used; moreover, it had come from a single manufacturer.  Based
on a demonstrable absence of creosote use, the owner felt confident in excluding
creosote and PAHs.

    To help focus on which phenolics might be present in his waste, the owner
turned to the Composition section of the Listing Document.  In Table 4, he found
typical compositions of commercial grade pentachlorophenol.  The sample from his
manufacturer contained 84.6 percent pentachlorophenol, 3 percent
tetrachlorophenol, and ppm levels of polychlorinated dibenzo-p-dioxins and
dibenzo-furans.  The owner was surprised by the absence of the other phenolics
mentioned in Appendix VII, and he was concerned by the presence of dioxins and
furans. Reading the text carefully, he discovered that the majority of the phenolic
compounds listed as hazardous  constituents  of  the waste are actually
decomposition products of penta- and  tetrachlorophenol. He also learned that
while the Agency had ruled out the presence of tetrachlorodibenzo(p)dioxin (TCOO)
in the listed waste (except where incinerated), it  had not ruled out the possibility
that other chlorinated dioxins might be present: "... chlorinated dioxins have been
found in commercial pentachlorophenol and could therefore be expected to be
present in very small amounts in some wastes." Due to their extreme toxicity and
because his facility had historically used the commercial pentachlorophenol with
the highest concentration of dioxins and furans, the owner thought it prudent to
include a scan for dioxins in his waste analysis plan.

    The owner found no  further data in the Composition section to help him
narrow the list of phenolics; however, Table 6 gave a breakdown  of organic
compounds found in  different  wood  preserving plants (i.e., steam  process vs.
Boneton conditioning), but only two phenolics were listed.  A  note  in the text
highlights on* of the  limitations of using the Listing Document: "The absence in
this table (TaMt 6) of certain components... probably indicates that an analysis for
their  presence was not performed rather than an actual absence of the
component." It should be kept in mind that the waste analyses in  the Listing
Background Documents are not comprehensive  and that they are  based, as the
Agency acknowledges, on data available  at the time.  In the absence of more
detailed waste-specific data, the owner decided to include pentachlorophenol,
tetrachlorophenol, unsubstituted phenol, and the six listed decomposition-product
phenolic compounds in his waste analysis plan.
                                  15-4

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     In reading the Listing  Documents, the owner found useful information for
other phases of the RFI.  In the Migratory Potential Exposure Pathways section, he
learned that pentachlorophenol is highly bioaccumulative, with an octanol/water
partition coefficient of 102,000.  Tetrachlorophenol, tri-chlorophenol, and
dichlorophenol are likewise bioaccumulative, with octanol/water coefficients of
12,589,4,169, and 1,380, respectively.  He also learned that the biodegradability of
pentachlorophenol is concentration limited.

     In Appendix B of the Listing  Background Documents;  Fate and Transport of
Hazardous Constituents, the owner found  data sheets for six out of nine phenolic
compounds, also some for dioxins and furans. Information on water chemistry, soil
attenuation, environmental persistence, and bioaccumulation potential were listed
along with chemical and physical properties such as solubility and density.

Case Discussion

     Although the Listing Background Document did not provide the owner with
enough specific data to fully characterize his waste, it did help him refine the list of
monitoring constituents, alert him to the potential presence of dioxins,  and gave
him physical and  chemical waste  characteristic data which could  be  useful in
predicting contaminant mobility.
                                   15-5

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CASE STUDY 2: ESTIMATION OF DEGRADATION POTENTIAL OF CONTAMINANTS
              IN SOIL

Point Illustrated

     •   Degradation, either chemical or biological, can be an important factor in
         determining the fate of a contaminant in soil, and can also be a factor in
         identifying constituents to monitor.  The degradation rate can also be
         accelerated as a means of conducting interim or definitive corrective
         measures.

Introduction

     Degradation of contaminants in the environment can occur through several
mechanisms, and can be a factor in identifying monitoring constituents.   Under
natural conditions, these processes are often very slow, but studies have shown that
chemical and biological degradation can be accelerated in the soil by modifying soil
conditions.  Parameters such as soil moisture content and redox condition can be
altered to encourage contaminant degradation in soils.

Site Description

     The site is situated in an arid region that was used during the 1970s by aerial
applicators  of  organochlorine and organophosphate pesticides. The applicators
abandoned the site in 1980 and homes were built in the vicinity. The site can be
divided into three areas based on past use. The most contaminated area, the "hot
zone", is a 125 feet by 50 feet area at the north end of the site that was used for
mixing, loading, and unloading the pesticides.  Soil samples from this  area
contained toaaphtnt, ethyl parathion, and methyl parathion at concentrations up
to 15,000 mg/kg.  The present residential area was used as a taxiway and an area to
rinse tanks  and clean planes.  Soils from this zone were low in parathions but
toxaphene concentrations ranging from 20 to 700 mg/kg were found.  This area is
approximately 1.7 acres in size and located immediately south and west of the hot
zone.  The  runway  itself was approximately  10  acres in size and  south  of the
residential zone.  Soil sample results from the runway area had low concentrations
of all three pesticides.
                                   15-6

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     A number of factors influence degradation of organic compounds in soils.
These include:

     •    chemical nature of the compound
     •    organic matter content of the soil
     •    soil pH
     •    oxidation/reduction environment of the soil
     •    concentrations of the compound.

     At the subject site, the soils were low in moisture content, were oxidizing, and
exhibited  soil pH values of 6.8 to 8.0.  Under such conditions, parathion can be
degraded  slowly by alkali catalyzed hydrolysis reactions. The rate of these reactions
increases with increasing soil pH. Parathion can also be biodegraded to 0,O-Oiethyl
phosphoric acid.  At a nearby site, it  was shown  that toxaphene will degrade
anaerobically if reducing conditions can  be achieved in the soil.  It has also been
observed that the  loss of toxaphene by volatilization is enhanced by  high soil
moisture content.   Other data indicated  that toxaphene will degrade in the
presence of strong alkali, by dechlorination reactions. This information can be used
in identifying monitoring constituents and in performing interim and definitive
corrective  measures.

     To test the feasibility of chemically degrading the contaminated soil, m, situ.
laboratory bench-scale tests were performed.  Two treatments were evaluated,
application of calcium oxide (quicklime) and sodium hydroxide (lye). Figure 15-1
shows that the pesticides were degraded by both of these strong alkalis.

     Those responsible for the remedial  measures felt that the hot zone was too
contaminated for in situ treatment to  be effective over reasonable time periods.
The upper 2 feet of soil  from this area was excavated and  transported to an
approved landfill for disposal. However, the 1.7-acre residential area was treated in
situ.  To promote degradation, approximately 200  g/ft* of sodium hydroxide was
applied using a tractor with a fertilizer-spreading attachment. A plow and disc
were used to mix the sodium hydroxide into the soil to a depth of 1.5 feet.  At 70
days after  the application, concentrations of ethyl parathion had decreased by 76
percent, methyl  parathion by 98 percent, and toxaphene by 45 percent.
                                    15-7

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   1000
    800 •
    600
  I
    400 •
    200
        25
        20
                                                         15
                                                         10
                                                                              • NaOH

                                                                              o  CaO
   Laboratory Banch Tatt, Ethyl ParMhion Degradation
                   2468
                         DAYS

      Laboratory Banch Tact, Methyl Parathion Degradation
                           17,500




                           15,000



                           12.500



                           10,000



                            7,500




                            5,000



                            2,500
• NaOH
eCaO
                                        2468
                                              DAYS

                            Laboratory Bench Tatt, Toxapbana Degradation


  Figure 15-1.    Results of Laboratory Bench Test for Pesticide Degradation
Swim: (from Kinf et d.. IMS).
                                             15-8

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Case Discussion

     Knowledge of the properties of a contaminant as well as its environment are
important in assessing the potential for degradation, and this information can be
used to identify monitoring  constituents and conduct  interim or definitive
corrective  measures.   It may  be  possible to alter the site's physical or chemical
characterisitcs to enhance degradation of contaminants.  Under appropriate
conditions, m situ treatment of contaminated soils can  be  an effective corrective
measures method.

Reference

King, J., T. Tinto, and M. Ridosh. 1985. In Situ Treatment of Pesticide Contaminated
Soils.  Proceedings of the National  Conference of Management of Uncontrolled
Hazardous Waste Sites. Washington, O.C
                                   15-9

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CASE STUDY 3: SELECTION AND EVALUATION OF A SOIL SAMPLING SCHEME
Points Illustrated

     •   Sampling methodologies must be  properly selected  to most
         appropriately characterize soil contamination.

     •   Statistical analyses can be used to evaluate the effectiveness of a chosen
         sampling scheme.

Introduction

     Selection of a sampling scheme appropriate for a soil contamination problem
is dependent on the objectives of the sampling program. A grab sampling  scheme
may be employed; however, grab sampling can produce a biased representation of
contaminant concentrations because areas of gross contamination are most often
chosen for sampling.  Random sampling can provide an estimate of average
contaminant concentrations across a site, but does not take into account differences
due to the proximity to waste sources and soil or subsurface heterogeneities.  A
stratified random sampling scheme allows these factors to be considered and, thus,
can be appropriate for sampling. Depending on the site, additional sampling using
a grid system may be needed to further define the areas of contamination.

Facility Description

     The example facility operated as a secondary lead smelter from World War II
until 1984. Principal operations at the smelter involved recovery of lead from scrap
batteries.  Air emissions were not controlled  until 1968, resulting in gross
contamination of local soils by lead particulates.

     Land use  around  the smelter is primarily  residential  mixed  with
commercial/industrial. A  major housing development is located to the  northeast
and a 400-acre complex of single family homes is located to the northwest. Elevated
blood lead levels have been documented in children living in the area.
                                  15-10

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Program Design/Data Collection

     Initial soil sampling was conducted at the lead smelter and in the surrounding
area to document suspected contamination. Sample locations were selected based
on suspected areas  of deposition of airborne  lead and in areas where waste
dumping was known to have occurred. High lead concentrations were documented
in samples collected  from these sources. Because data obtained in the exploratory
sampling program (grab sampling) were not adequate to delineate the area) extent
of contamination, a stratified random sampling scheme was developed.

     Based on wind  rose data and the behavior of airborne participate matter, a
sampling area was selected encompassing  a 2-mile radius from the smelter. Specific
sampling sites were selected using a stratified random sampling scheme. The study
area was divided into sectors each 22.5 degrees wide and aligned so that prevailing
winds bisected the sectors. Each sector was further divided into approximately one-
tenth mile sections.  A random  number  generator was used to select first the
direction and then the section. Random  numbers generated were subject to the
following restrictions:  two-thirds  of the sites selected had to fall  in the major
downwind direction; both residential and non-residential sites had to exist in the
sector; sampling sections were eligible for repeat selection  only  if they were
geographically within  1/2 mile of  the smelter or if the  section  contained both
residential and non-residential sites.   Sites that were  biased towards lead
contamination from other than the lead smelter were not sampled  (e.g., gas
stations and next to roads). A total of 20 soil sampling locations were selected, 10 at
residences and 10 at non-residential  sites such as schools, parks, playgrounds and
daycare centers.

     Sample cores were collected  using a 3/4-inch inner diameter stainless steel
corer. Total sample depth was 3 inches. A minimum of four and maximum of six
samples were collected at  each sampling location within a 2 ft  radius. Cores were
divided into 1 inch increments and the corresponding increments were composited
from each depth to  make up one  sample. This approach provided data on lead
stratification in the top 3 inches of soil. All  samples were analyzed for total lead.
                                  15-11

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     The results of the stratified random sampling indicated several acres with over
2,000 ppm lead in the soil. To further define the extent of these areas, a grid
sampling plan was designed.  Seven hundred and fifty foot increments were used.
The grid was oriented along the  axis of the release.  Both residential and  non-
residential areas were sampled.  At each grid point, four 3-inch cores were collected
30 m from the grid  point in each major  compass direction.  The cores were
composited by depth as discussed above.

Program Results/Data Anavsis

     Analytical results from the soil sampling  program indicated significant lead
contamination within the study area. Maximum concentrations observed were
2,000 ppm lead with a background level of 300  ppm. Kriegmg of the data from the
grid sampling plan was used to develop a contour map as shown in Figure  15-2.
Lead concentrations were highest northwest and southwest of the smelter.

Case Discussion

     Because of the large area potentially affected by lead emissions, development
of a sequential sampling plan was necessary to determine the maximum soil lead
concentrations surrounding  the smelter  and the areas  having elevated
concentrations.  A grab sampling scheme was first used to confirm that soil
contamination existed.  A stratified random sampling scheme was developed to
provide representative data throughout the study area.  This type  of sampling
allowed consideration of prevailing wind directions and the need to sample both
residential and non-residential areas. To further define areas of contamination, a
grid sampling plan was developed. From these data, lead isoconcentrations maps
were prepared d*lineating areas with elevated concentrations.
                                  15-12

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    -i	r
Lead isovaives


• SMELTER
I     I 	1	1	1	1	1	1	1	I	1	P

  ESTIMATED LEAD CONCENTRATIONS 
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CASE STUDY 4: SAMPLING OF LEACHATE FROM A DRUM DISPOSAL AREA WHEN
              EXCAVATION AND SAMPLING OF DRUMS IS NOT PRACTICAL
Points Illustrated

     •   It is not always possible to perform waste characterization prior to
         establishing the RFI monitoring scheme because the waste may not be
         directly accessible, as in the case of buried drums.

     •   When direct waste characterization is not practical, release monitoring
         should be performed for the constituents listed in Appendix B of Volume
         I of the RFI Guidance.

Introduction

     Insufficient waste characterization data existed for a former drum disposal
facility that was suspected  of releasing contaminants into the subsurface
environment.  Leachate within the disposal pit was sampled and analyzed for all
constituents listed in Appendix B of Volume I of the RFI Guidance.  The resulting
information was used to determine the major waste constituents to be monitored
during the RFI.

Facility Description

     The unit of concern was a pit containing an estimated 15,000 drums. Due to
poor recordkeeping by the facility operator, adequate information regarding the
contents of the drums was not available.  It was also not known if the drums were
leaking and releasing contaminants to the environment  Because insufficient data
existed regarding the drum contents, it was not known what constituents should be
monitored in nearby ground and surface waters. Due to the risk to workers and the
potential for causing  a multi-media environmental  release, excavation and
sampling of the drums to determine their contents was not considered practical.
Instead, it was decided that leachate around the perimeter of the drum disposal pit
would be sampled to identify constituents which may be of concern.
                                  15-14

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Program Design/Data Collection

     To determine the physical extent of the buried drums, a geophysical survey
was conducted using a magnetometer.  Borings were located at positions having
lower magnetometer readings than surrounding areas in order to minimize the
potential for drilling into drums.

     Soil borings were drilled around the perimeter of the drum disposal pit, as
defined by the magnetometer survey.  Drilling was accomplished using a hydraulic
rotary drill rig with a continuous cavity pump.  Water was used as the drifting fluid.
To  prevent surface runoff from  entering the borehole and to control gaseous
releases from the  borehole, primary and secondary surface collars were installed.
These consisted of 5-foot sections of 4-inch steel pipe set in concrete. A device to
control liquid and gaseous releases from the borehole was threaded onto the collars
to form a closed system (Figure 15-3).

     Drilling was  performed using a wireline operated tri-ccm roller bit with a
diamond tipped casing advancer (Figure 15-4).  Water was pumped down inside the
casing and out the drill bit, returning up the borehole  or entering the formation.
The use  of water to aid in drilling also helped reduce the escape of gases from the
borehole. Air monitoring showed no releases. Split-spoon samples were collected
at 5-foot intervals  during the drilling and a leachate monitoring well was installed
at each boring location.

     The soil and leachate samples were  analyzed for the compounds contained in
Appendix B of Volume I of the RFI Guidance.

Program ResuKs/Data Analysis

     The leachate samples were found to contain high levels of volatile organic
compounds including 2-butanone, 4-methyl-2-pentanone, and  toluene.
Concentrations were higher on the downgradient side of the pit
                                  15-15

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          r8MJ.-VM.VC OPCRATCD
          SAMSUNG POUT
                                          KCLLY /too
                                          •KCU.Y SWVCL

                                            •KCLLT HOSi
     CNCLOSO
      TANK (200 GM.)
                                                         S7QL
Figure 15-3.     Schematic Diagram of Gas Control System Utilized at Pit
                                15-16

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                                     WIRELINE CA8L£
                                     OVERSHOT LATCHING
                                     DEVICE
                                        CASING
                                     RETRACTABLE 2 15/16'
                                     TRI-CONE ROLLER 3IT
                                     W/ LOCKING INNER SU3
                                     DIAMOND TIPPED CASING
                                     ADVANCER (REAMING SHOE)
Figure 15-4.   Schematic Drawing of Wireline Drill Bit and Reaming Shoe
                             15-17

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Case Discussion

     Leachate sampling can be useful in determining whether buried drums are
leaking and to identify materials that are being released. This methodology can be
safer than excavation and sampling of individual drums.  It can also identify the
more soil-mobile constituents of the leachate.

     The data gathered  in this case study were used in designing a monitoring
program, and the contaminants found were used as indicator compounds to link
downgradient ground-water contamination to this waste disposal unit.
                                   15-18

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CASE STUDY 5: USE OF QUALITY ASSURANCE/QUALITY CONTROL (QA/QC) AND
              DATA VALIDATION PROCEDURES
Points Illustrated

     •   A comprehensive field and laboratory QA/QC program is necessary for
         assessing the quality of data collected during an RFI.

     •   Timely validation of laboratory data can uncover problems correctable by
         reanalysis or by resampling, thus preventing data gaps.

Introduction

     A company in the mining and smelting  industry sampled domestic wells and
surface soils in the vicinity of a tailings pile to monitor possible leaching of metals
into the aquifer and possible soil contamination due to wind-blown dust.  Because
the data would be used to assess corrective measures alternatives and to conduct a
health and  environmental assessment  the company  chose to conduct  both  its
sampling and analysis efforts under a formal QA/QC Project Plan and to subject all
laboratory data to rigorous data validation procedures.

Facility Description

     At this facility, a tailings pond had received smelter waste for many years.
Local  water supply wells were potentially at risk due  to percolation of water
through the pile and possible leaching of heavy metals.  Local surface soils in nearby
residential  areas  (e.g., yards,  public playgrounds) were also  subject  to
contamination from wind-blown dust originating from the pile during dry windy
weather.

Sampling Program

     Before sampling began, a set of documents were drafted following  U.S. EPA
guidelines (U.S. EPA 1978,1980a, 1980b, 1981,1982,1985a, 1985b) that specified in
detail sampling  sites and parameters to be measured, field and laboratory
                                  15-19

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procedures, analytical laboratory protocols, and all field and laboratory QC checks
including frequencies, and corrective actions.  The  important  elements  of each
document are described below.

Standard Operating Procedures (SOPs)--

     This document contained step-by-step procedures for the following items:

     •   Calibration, operation, and maintenance of all instruments used in the
         field and laboratory.

     •   Equipmentdecontamination.

     •   Ground water and soil sampling, including compositing.

     •   Use of field notebooks and document control.

     •   Sample packaging, shipping, and chain-of-custody.

Field Operations Plan (FOP)--

     This document included the following:

     •   Rationale  for choice of sampling locations, sampling frequency,  and
         analytes to be measured

     •   List of sampling equipment and SOPs to be used for each sampling event.

     •   List of field QC checks to be used and their frequency for each sampling
         event

     •   Health and safety issues and protective measures for field personnel.

     •   Sampling schedule.
                                  15-20

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Laboratory Analytical Protocol (LAP)--

     This document included the following:

     •    Sample size, preservation, and analysis protocol for each analyte.

     •    List of laboratory QC checks, QC statistics to be calculated and their
          control limits, and corrective actions for QC checks outside control limits.

     •    Detailed list of deliverable documents and their formats.

     •    Procedures for sample custody, independent audits, and  general
          laboratory practices.

QA/QC Project Plan (QAPP)--

     This document gathered  into one place the overall data quality objectives for
the sampling and detailed QC procedures needed to attain those objectives.
Included were:

     •    Quality assurance objectives in  terms of  precision,  accuracy,
          completeness, comparability, and representativeness.

     •    Procedures for the screening of existing data.

     •    Data management reduction, validation, and reporting.

     •    Overview of both field and laboratory QC checks and their frequencies,
          control limits, and corrective actions.

     •    Data assessment procedures.

Results

     Five surface soil  samples were taken in high traffic areas  of two playgrounds
and three residential yards. Five tap water samples were collected at two public
                                   15-21

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drinking fountains at the playgrounds and at the three private residences. The
analysis results, as received from the laboratory, are shown in Table 15-2. The data
indicated that a soil hot spot existed for cadmium, that elevated lead occurred at all
five soil stations, and that all of the domestic wells showed elevated levels of
mercury.

     The laboratory data package was subjected to a thorough data validation, as
detailed in the QA Project Plan. The following information and QC results were
checked by examination of original documents or photocopies of the documents.

Sampling, Sample Shipping, Chain-of-Custody-

     Copies of field and field laboratory notebook pages were examined to insure
that ail SOPs were correctly followed, that there were no notations of anomalous
circumstances (such as sample spillage) that may have affected analysis results, and
that the samples were correctly preserved, packaged, and shipped. Copies of all
chain-of-custody forms, bills-of-lading, and sample analysis request forms were
examined to insure that chain-of-custody was not broken and that samples arrived
intact at the laboratory.

Laboratory Raw Oata-

     The QAPP had specified that one of the deliverables from the laboratory was
copies of all instrument readouts and laboratory notebook pages. The digestion
raw data were checked to insure that no holding time violations had occurred. This
is important for mercury because the holding time is only 28  days for aqueous
samples.

     All raw calibration data  were recalculated and tested against instrument-
calculated sample results.  Recoveries of calibration verification standards and
continuing calibration standards were checked to insure that all instruments were
correctly  calibrated, were not drifting out of calibration, and  were correctly
calculating raw analysis results.
                                   15-22

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                        TABLE 15-2

 RESULTS OF ORIGINAL SURFACE SOIL AND TAP WATER ANALYSES
Sample*
SOIL-1
SOIL-2
SOIL-3
SOIL-4
SOIL-5

WATER- 1
WATER-2
WATER 3
WATER-4
WATER-5
Cd
14
7
<20e
19
1200

<50
<50
<50
<50
<50
Cu
5200
2400
720
680
1080

NA
NA
NA
NA
NA
Pb
800
400
4530
350
460

<30
<30
<30
<30
<30
Hg
NA°
NA
NA
NA
NA

1.5
1.3
1.0
1.4
1.2
Zn
1200
190
70
350
420

NA
NA
NA
NA
NA
a  Soils in units of mg/kg, water in ug/L
t>  Not analyzed.
c  Undetected at detection limit shown.
                          15-23

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     Final analysis results were recalculated from raw data using  dilution and
digestion factors, as summarized in the lab notebooks, and compared to the data
summary sheets. No transcription errors were found. However, the cadmium result
for SOIL-5 contained a calculation  error, and the correct final result was 12 mg/kg
instead of the 1200 mg/kg reported.

Laboratory QC Checks-

     The QAPP had specified that the  laboratory had to analyze p re-digestion
duplicates and spikes, U.S. EPA laboratory control samples, and reagent blanks. The
laboratory QC results are summarized in  Table  15-3 and  indicated accuracy and
precision well within U.S. EPA guidelines.  The mercury preparation blank also
indicated that the tap water results were not due to laboratory digestion reagents
or procedures.

Field QC Checks--

     As specified  in the QAPP and  FOP,  the following field QC samples were
included with each of the soils and tap water samplings: bottle blank, field blank,
standard reference material (SRM), triplicate, and an interlaboratory split to  a
"reference" lab. The results are summarized in Table 15-4.

     Although  no U.S. EPA control limits or corrective  actions exist for field-
generated QC checks, the results of their analysis can aid in the overall assessment
of data quality. The triplicate, SRM, and interlaboratory  split analyses indicated
good overall analysis and  sampling precision and accuracy.  The field blanks
indicated tht possibility of  mercury contamination from one of the four possible
sources: thcprt-deaned bottles, the preservation reagent, the distilled water used
in the field, or an external  contamination source such as dust.  The high positive
mercury result in the water  bottle  blank eliminated all of these sources except the
first because the bottle blanks remained sealed throughout the sampling effort.

     The laboratory was  immediately called and, upon personal inspection, the
laboratory manager discussed the  remnants of a broken thermometer bulb in the
plastic tub used to acid-soak the bottles. An unused bottle from the same lot and
                                   15-24

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                                  TABLE 15-3

                          LABORATORY QC RESULTS
Analyte
Cd
Cu
Pb
Hg
Zn
Duplicate RPD'(%)
SOIL-2
18
S
14
NA
7
WATER-4
NC*
NA"
NC
NC
NA
Spike Recovery "(%)
SOIL-2
100
93
110
NA
85
WATER-4
98
NA
92
103
NA
LCS<
(%)
101
97
106
NA
99
Soil
Preparation
Blank*
<509
<100
<200
NA
<150
Water
Preparation
Blank*
<50
NA
<3Q
<0.20
NA
a  RPO s relative percent difference * (difference/mean) x 100. Controllimits 3 135% for
   solids and ± 20% for aqueous samples.
b  Spike Recovery » (spike + sample result) • (sample result) x 100. Control limit.» 75-125%.
                                 (spike added)
c  LCS = laboratory control sample. Control limit -90-110%.
d  mg/kg.
   ug/i.
   NC = not calculated due to one or both concentrations below detection limit.
   Undetected at detection limit shown.
   NA = not analyzed.
                                     15-25

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                                       TABLE 15-4

                                    FIELD QC RESULTS
Analytt
Cd
Cu
Pb
Hg
Zn
Triplicate
CV'(%)
SOIL-1
22
3
7
NA
1
WATER- 1
NC
NA'
NC
18
NA
SRM
Recovery** (%)
BCSS-T
83
94
97
NA
110
U.S. EPA*
105
NA
101
103
NA
interlab.
RPDf(%)
SOIL-1
-12
0
14
NA
24
WATER- 1
NC
NA
NC
19
NA
Field
Blanks'
SOIL-1
   Recovery « (certified value/result) X100.
c   National Research Council of Canada marine sediment

-------
still at the laboratory as well as two bottles washed in previous lots were analyzed.
The bottles previously washed contained no detectable mercury, and the bottle
from the same lot as used in  the sampling effort contained 0.75 ug.  The water
mercury data were rejected, and a second sampling  effort using new bottles was
conducted. All of the new samples contained no detectable mercury.

Discussion

     This case study demonstrates the need for the establishment of a formal
QA/QC program  that not only specifies field QC protocols but also incorporates
thorough data package validation. In this instance, a potential hot spot was found
to be due to a calculation error, and potential mercury contamination of domestic
well water was found to be a  result of using contaminated sample containers.  In
the latter case, timely QA/QC review allowed for a speedy resampling effort which
could be done at this site. In situations where resampling is not possible, adequate
QA is crucial.

References
U.S. EPA.  1978 (revised 1983). NEIC Policies and Procedures. EPA-33079-78-001-R.
U.S. EPA, National Enforcement Investigations Center, Denver, CO.
1978 (revised  1983).  NEIC Policies and Procedures. EPA-330/9-78-001-R. U.S. EPA,
National Enforcement Investigations Center, Denver, CO.
U.S. EPA.  1980a. Interim guidelines and specifications for preparing  quality
assurance project plans. QAMS-005/80.  U.S.  EPA. Office of Monitoring Systems and
Quality Assurance, Washington, DC. 18pp.
U.S. EPA. 1980b.  Samplers and sampling procedures for hazardous waste streams.
EPA-600/2-80-018"U.S. EPA, Municipal Environmental Research Laboratory,
Cincinnati, OH.
U.S. EPA.  t9i1.   Manual of  qrqundwater quality sampling  procedures.
EPA-600/2-8t-T«0. Roberts. Kerr Environmental Research Laboratory, Ada, OK. 105
PP-
U.S. EPA. 1986. Test  methods for evaluating solid waste.  SW-846.  3rded. U.S. EPA,
Office of Solid Waste and Emergency Response, Washington, DC.
                                  15-27

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U.S. EPA.  1985a.  Contract laboratory prot
analysis, multi-media, multi-concentration.
                       Qf
                                  U.J
	,-..,, ........ ..,^w,q.. muiu-iuriteniranon.  iUW No   785  Ju u  idi
Environmental Monitoring Support Laboratory, Las Vegas, NV


:UJ:.E?A:'. ly.Sb.^LatioratorY data validation  Funrtional guidelines for evaluating

                                                                     jmedial
inorganic analysis' October, 1985.
Response, Washington, DC.
U-S-
            .ee o
                             aneme
15-28

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CASESTUDY6: PRESENTATION  OF  DATA  COLLECTED  DURING  FACILITY
              INVESTIGATIONS

Point Illustrated

     •   Techniques for presentation of data for facility investigations involving
         multimedia contamination.

Introduction

     Data acquisition and interpretation are integral parts of facility investigations.
Depending on the  size, complexity, and  hazards  posed at a particular site,
significant  quantities  of meteorologic, hydrologic, and chemical  data can be
collected. To make the best use of these data, they should be presented in an easily
understood and meaningful fashion. This case study focuses on widely used and
easily implemented graphical techniques for data presentation.

Site Description

     The site is a former copper smelter that ceased operation in the early 1980s.
During the operation of the smelter, large quantities of mine tailings were slurried
to tailings ponds that remain today (Figure  15-5). The tailings contain high solid
phase  concentrations  of inorganic contaminants such as copper, zinc, lead,
cadmium, and arsenic.  In the Smelter Hill area, flue dust and  stack emission
deposition have contaminated surficial soils. Numerous other units were operated
at the  complex including an  experimental plant  designed to leach  copper using
ammonia. The copper leach plant is shown in Figure 15-6. Three disposal ponds (I,
II, and III) received wastes slurried from the plant.

     As a result of smelting and waste disposal practices, multimedia contamination
of ground water, surface water,  and soils  has occurred.  Also, episodes of air
contamination have been documented due to entrainment of tailings during windy
periods.
                                  15-29

-------

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15-31

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Field Sampling and Data Collection

     Data collection activities at this site were comprehensive. Over 100,000 pieces
of data were collected in the categories shown in Table 15-5.

Oata Presentation

     This section illustrates a number of graphical techniques that can be used to
present data from facility investigations. Graphical presentations are useful for the
following general purposes:

     •    Site feature identification, source identification, and mapping;

     •    Hydroiogic characterization; and

     •    Water quality characterization.

For large sites, aerial photography is often very useful for defining the locations and
boundaries of waste deposits, and  for  establishing time variability  of site
characteristics. Figure 15-6, for example, was developed from aerial photographs at
a 1:7800 scale. Types of information obtained by comparing this photograph to one
taken 10 years earlier include:

     •    Pond III was originally constructed earlier than Ponds I and II, and was not
          lined. Ponds I and II wtrt lined.

     •    Tht red sands (a slag deposit) shown in Figure 15-6 are present only north
          of tht railroad tracks. Earlier photographs showed that  the red sands
          exfcwrfed to the highway, but were leveled and covered  with alluvium
          during construction of the copper leach plant.

This type of photographic* information is valuable for locating  waste  deposits,
estimating quantities of wastes, and determining waste proximity to sensitive areas.
                                   15-32

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                        TABLE 15-5
               SUMMARY OF DATA COLLECTED
Category
Ground Water

Surface Water and
Sediment
Alluvium'
Soil*
Tailings*
Slag and Flue Oust*
Miscellaneous
Parameters
Water level elevations, potentiometric heads
Concentration of Al, Sb, As, Ba, Be, Bo, Cd, Ca, Cr,
Co, Cu, Fe, Pb, Mg, Mn, Hg, Mo, Ni, K, Se, Ag, Na,
Sn, V, Zn, P, Cl, F, S04, pH, 0?, EC, Eh, Alkalinity,
TDS
Flow rates, bed particle size distributions,
suspended solids concentrations, dissolved
concentrations of same inorganic parameters as
ground water
Moisture content, soil, pH, EC, Sb, As, Cd, Cu, Fe,
Pb, Mn, Se, Ag, Zn, particle-size distribution
Cd, Cu, Fe, Pb, Mn, Ni, Zn, Sb, As, Cd, Cr, Hg, Se,
Ag, Zn, particle-size distribution, Eh, S, TOC
Sb, Ar, Be, Cd, Cu, Fe, Pb, Mn, Ag, Se, Zn, particle
size, moisture, pH, EC, sulfur, carbonate
Sb, As, Cd, Cu, Fe, Pb, Mn, Se, Ag, Zn, S04, EC, pH,
alkalinity
Meteorology, aerial photographs and other
photographic documentation, well log data,
surface topography, volumetric surveys of waste
piles
Element data are solid phase.
                           15-33

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     For sites with complex hydrologic interaction, it is often helpful to graphically
represent the flow system. Figure 15-7 illustrates the surface water system at the
site.  The diagram is useful because it shows the hydrologic interconnections of the
drainage system.

     For the ground-water system, flow direction and velocities provide
information needed for contaminant transport predictions.  This information  is
generated by plotting water levels on a site map, and then drawing contours
through points of equal elevation. An example is shown in Figure 15-8. Because the
contours form a  relatively simple pattern in this case, they were  drawn by hand.
However, computer-based contour packages exist that could be used to plot more
complicated contour patterns.

     Inferred flow directions are also shown in Figure 15-8.  From a knowledge of
the hydraulic gradient, hydraulic conductivity and effective porosity, the average
linear velocity can be calculated, as shown in the upper left hand corner of the
figure. A velocity of  79 m/yr  is calculated, for example, which means that
approximately 126 years would be required for conservative solutes to move across
the site (approximately 10,000 meters).

     Water quality data can be presented as shown in  Figure 15-9.  This  figure
shows the spatial distribution of calcium, sulfate, and IDS at  key surface  water
stations.  This data presentation method  provides a broad area! view of these
parameters.

     Time series plots art useful for showing temporal variations in water quality.
For example, time trends of SO4 at three ground-water  monitoring locations are
shown in Figure  15-10.  Well 19 is slightly downgradient from the source, and the
high S04I eve* reflect that the well is receiving solutes generated within the source.
Wells 26 and 24 are further upgradient, and reflect better water quality conditions.
The plot indicates that variability between stations generally is  more  significant
than time variability at a given location.  One exception is at well 24 where a
temporary increase in sulfate levels was noted in 1975-76.
                                   15-34

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UNCAGED
DIVERSIONS
    NCW  i
    LIMI  ;
    DITCH!
 RANGUS
 CREEK
HILL
CREEK
               SOUTH
               DITCH
               OLD
               UM€
               DITCH
                                                 SEWAGE
                                                 DITCHES
BYPASS
r'  /"
GOLDEN
CREEK
                                 PONOS
                                                     DRAIN
                                                     DITCH
                                                            COLD
                                                            CREEK
                                                           GARDINER
                                                           OITCM
                                         UNCAGED
                                         DIVERSIONS
                                          GREEN
                                          RIVER
          Figure 15-7.    Schematic of Surface Water System
                                15-35

-------
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                                        15-37

-------
   2000-
=  1600-

S
cT
W  1200-
    800-
    400-
                                                       • Well 19
                                                       a Well 24
                                                       • Wen 26
         1974   1975   1976  1977  1978   1979  I960  1981   1982  1983  1984  1985
                                         Y«ar
        Figure 15-10.   Changes inSulfate Over Time at Selected Wells
                       Located Within the Site
                                   15-38

-------
     To identify leachate and soil interactions beneath a waste site, trenches may
be dug. The trench walls are then logged and photographed. Detailed sampling
may be done at  closely  spaced intervals to confirm that reactions such  as
precipitation have occurred. Figure 15-11 shows a cross-section of a tailings deposit
that was developed based on a trench excavated through the tailings  into the
underlying alluvium. The plot shows the demarcation between wastes and natural
alluvium.

     Figure 15-12  shows the details of the chemical composition of one borehole
through the tailings and into the underlying alluvium.  The chemical composition is
shown to varv significantly with depth. These types of plots  contain a wealth of
chemical information that can help to explain the geochemical processes operative
in the tailings.  Figure 15-12 also shows the marked contrast between the
composition of the tailings (in the top 16 feet) and the underlying alluvium.

Summary

     The graphical presentations illustrated in this case study are a few of the many
techniques available.  With the proliferation  of graphical packages available on
microcomputers, scientists and engineers have a wide range of tools available for
data presentation. Some of these tools are summarized in Table 15-6.
                                  15-39

-------
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                        15-41

-------
                       TABLE 15-6
TYPICAL METHODS FOR GRAPHICALLY PRESENTING DATA COLLECTED
              DURING FACILITY INVESTIGATIONS
Data
METEOROLOGIC DATA
Wind speed and direction
Air temperature
Precipitation
Evaporation
SURFACE WATER DATA
Flow rates
Water quality
GEOHYDROLOGIC DATA

GROUND-WATER DATA

MISCELLANEOUS

Graphical Presentation Methods

e Wind rose showing speed, direction and percent of
observations for each 10° increment
e Bar chart, by month
e Bar chart, by month
e Bar chart, by month

e Hydrographs; distance profiles, cumulative frequency
distributions, flood frequency plots
Hydrologic network depiction and water budgets
Tri linear diagram
Stiff diagrams
Contour showing vertical concentration or temperature
variability in two deep water bodies
Time history plots showing daily/annual variability
Bar charts of major cations/anions or contaminants at
multiple locations shown on a single map

Geologic map of site and vicinity
Stratigraphic cross-sections of site in direction of and
perpendicular to ground water flow
Well logs
Cross-sections near waste deposits
Solid phase chemical analyses by depth at borings near
waste deposits and into alluvium

Water level contours
Flow directions and velocities
Time history of water table at important locations
Stiff diagrams
Tri linear diagrams
Contaminant plumes, showing isopleths

• Figures with important site features, including waste
sources, storage ponds, disposal areas, buildings,
sampling locations, well locations
• Operational aspects for special sampling equi pment
(e.g., lysimeters)
                         15-42

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CASE STUDY 7: CORRELATION OF CONTAMINANT RELEASES WITH A SPECIFIC
              WASTE MANAGEMENT UNIT USING GROUND-WATER DATA

Point Illustrated
                                        i
     •    Development of an effective ground-water monitoring program can tie
          releases of contaminants to specific waste mangement units.

Introduction

     Documentation of a release from a specific waste  management unit may
require the development of a comprehensive  ground-water monitoring program
coupled with an extensive hydrogeologic investigation. Determination of ground-
water flow direction and horizontal and vertical gradients are necessary to assess
the direction of potential contaminant migration.  Historical data  on wastes
disposed in specific units can provide information on contaminants likely to be
detected downgradient.

Facility Description

     Chemicals were manufactured at a 1000-acre facility for over 30 years.  The
facility produced plastics including cellulose nitrate, polyvinyl acetate, poly vinyl
chloride and polystyrenes, and other chemicals such as phenols and formaldehyde.
Wastes produced in the manufacturing processes were  disposed on  site in an
unlined  liquid waste impoundment and in two solid waste disposal areas.  Readily
combustible materials were incinerated in four burning pits. Ground-water
contamination has been documented at the site. Figure  15-13 shows the facility
plan and locations of ground-water monitoring wells.

     The site is located in a glacial valley and is adjacent to a major river. A minor
tributary runs through the southwestern portion of the facility and drains into the
river. Approximately 200 dwellings are located downgradient of the site.
                                  15-43

-------
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                15-44

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Data Collection

     Initial studies to assess the extent of ground-water contamination began m
1981. Studies focused on ground water in the vicinity of various waste disposal
units. A limited number of monitoring wells were installed in 1983.  These wells
provided general data on the direction of ground-water flow and chemical
constituents that had entered the ground water. In 1984, a two-phased approach
was developed to define the areal and vertical extent of contamination and to
identify contaminant releases from specific waste management units. The first
phase involved the characterization of  facility geologic and hydrogeologic
conditions  using historical data, determination of the chemical nature of
contaminants  in the ground  water using existing monitoring  wells, and
development of a contaminant contour map delineating the horizontal boundaries
of contamination. Based on this data, 33 soil borings were drilled in Phase 2. The
goals of the second phase were to: 1) detail subsurface  geologic characteristics,
vertical and horizontal water flow patterns, contaminant migration, and site-
specific chemical contaminants; and 2) install wells that would be used to monitor
contaminants being released from all units of concern at the facility.

     Continuous split spoon samples were collected in each boring and headspace
analyses for volatile organic compounds (VOC)  were conducted on each sample.
Chemical constituents were identified using  a field gas  chromatograph.
Confirmational analysis by GC/MS were conducted  on selected samples.
Geotechnical analyses were also conducted on the split spoon samples.

     Chemical and hydrogeologic data (direction of flow, gradients) obtained from
the borings were used to select appropriate  ground-water  monitoring  well
locations and screen depths.  Fifty-two (52) nested monitoring wells were installed
at 25 locations upgradient and downgradient of each waste management unit, and
near the river and its tributary.  Screen depths were determined by the depth of
maximum VOC contamination observed in the borings and the permeability of soil
layers.
                                  15-45

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Data Analysis

     Ground-water contamination data from new wells coupled with historical
waste disposal data allowed releases from three specific waste management areas
to be defined. Sample analyses showed organic solvents in nearly all locations.
However, more unusual constituents associated with specific  manufacturing
processes were detected in some samples, allowing them to  be  correlated with
releases from specific waste management units. The two situations below illustrate
how these correlations were accomplished:

1)   PCBs detected in some samples were correlated with Solid Waste Disposal Area
     #1. This area received construction debris, resins, plastics, metals, drums, and
     PCB containing transformers.  Records indicated  that this unit was the only
     location where transformers were disposed onsite.   PCBs could not be
     associated with any of the other waste management units.

2)   The solvent dimethylformamide (DMF)  detected  in some  samples was
     correlated with Burning Pit B. It was discovered that the building that housed
     this unit had been used to tint windshields and that DMF is a component of
     the dye used in this process. DMF could not be tied to any of the other waste
     management units. A leachfieid in which waste dyes had been disposed was
     discovered under the building and the contamination was traced back to that
     source.

Case Discussion

     An exttmivt hydrogeologic investigation of the facility was completed and, in
conjunction wWt historical data, was used to develop a comprehensive ground-
water monitoring program. Placement of the monitoring wells and screens was
essential in providing data that unequivocally linked contaminant  releases to
specific waste management units and manufacturing processes.
                                  15-46

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CASESTUDY8: WASTE SOURCE CHARACTERIZATION FROM  TOPOGRAPHIC
              INFORMATION

Points Illustrated

     •   Mapping of changes in site topography can  support the selection of
         locations for test borings and monitoring wells.

     •   This technique is especially useful at sites where large volumes of waste
         have been disposed of over several years.

Introduction

     Topographic surveys conducted prior to and at different times during the
operation of a waste management  facility can be used to help  characterize the
vertical and horizontal extent of waste disposal areas. Because the resolution of
this technique is limited, it is most useful when large volumes of waste are involved.

Facility Description

     This facility is the same as discussed in Case Study 7 above.

Topographic Survey

     In 1984, a topographic survey measuring elevations in feet relative to mean
sea level was conducted for the areas shown in Figure 15-14. These elevations were
plotted on a map of appropriate horizontal scale and contoured in 2-foot intervals.
This topography  was transferred to an existing site plan (horizontal scale  1" to
200'). Topographic maps from 1935 (showing the natural topography before waste
deposition)  to 1960 (showing the topography in  the earlier .stages of the facility
operation)  were compared to the 1984 map.  By examining the changes in
elevations which occurred  over time, contours were  developed showing the
estimated changes in vertical and horizontal units of the liquid  waste and solid
waste disposal areas.
                                       i
                                  15-47

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Results

     From the analysis, it was apparent that the deepest portion of Solid Waste
Disposal Area (SWDA) No. 1  (Figure 15-14) was approximately 48 feet, and the
Liquid Waste Disposal Area (LWDA) was approximately 30 feet deep.  The
horizontal limits of the disposal areas were also defined in part by this review, but
other field surveys  provided more accurate information  on  the horizontal
boundaries of the waste disposal areas.

Case Discussion

     Topographic surveys can provide useful information  for characterizing
disposal areas.  The results of these studies can facilitate the selection of
appropriate test boring locations, and may reduce the number of borings necessary
to describe the subsurface extent of contamination.  It should be noted that
techniques such as infrared aerial photography and topographic surveying are
approximate in their findings. They are useful methods in the early phases of an
investigation, but do not replace the comprehensive characterization  of the
environmental setting needed for the full investigation.
                                  15-49

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CASE STUDY 9:  SELECTION OF GROUND-WATER MONITORING CONSTITUENTS AND
              INDICATOR PARAMETERS BASED ON FACILITY WASTE STREAM
              INFORMATION

Points Illustrated

     •   Waste stream information can  be used  to identify potential
         contaminants, and thus to select appropriate ground-water monitoring
         constituents and indicator parameters.

     •   The  number of initial monitoring  constituents analyzed may be
         significantly reduced from the 40 CFR Part 261 Appendix VIII list when
         detailed waste stream information is available.

Introduction

     Hazardous waste treatment, storage, and disposal facilities subject to RCRA
are required to identify all waste streams managed the facility, waste volumes,
concentrations  of waste constituents,  and the waste management unit in which
each waste type is disposed.  Ground-water monitoring programs should be
developed  to  adequately  monitor  contaminant migration from each  unit.
Constituents to be analyzed  in the ground-water monitoring program should be
established prior to sample collection.  When waste stream data are not available,
the full set of Appendix VIII monitoring constituents may be  required to
characterize ground-water contamination.   Knowledge of the waste streams
managed by a  facility  simplifies the  selection  of monitoring constituents and
indicator parameters because potential contaminants and their likely  reaction and
degradation products can be more easily identified.

Facility Description

     The 600-acre facility is a permitted waste disposal site operated since  1980.
Solid waste management units occupy  20 acres of the site and include four surface
impoundments and one container storage area subject to RCRA.  Until 1985, three
units (two surface impoundments and one solids disposal  unit) not subject to RCRA
were used for geothermal waste disposal. However, the two surface impoundments
                                 15-50

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were replaced by a RCRA regulated landfill.  RCRA wastes managed by the facility
include metals,  petroleum refining  wastes, spent  non-halogenated solvents,
electroplating wastewater treatment sludge, spent pickle liquor from steel finishing
operations, and ignitable, corrosive, and reactive wastes. Ground-water monitoring
wells have been installed downgradient of each waste mangement unit.

Program Design

     Prior to disposal, each  load  of waste received  is  analyzed in an on-site
laboratory to provide a complete characterization of waste constituents.  Periodic
sampling of the waste management units  is also conducted to identify waste
reaction products and hazardous mixtures. Even though the incoming wastes have
been characterized, the facility owner also analyzed  initial ground-water samples
from each monitoring well for all Appendix VIII constituents.  The resulting data
were used to establish existing concentrations for each  constituent and to select a
set of monitoring constituents and indicator parameters to identify migration of
waste to the ground-water system.  Table  15-7 includes a list of the indicator
parameters analyzed at the facility.  Rationale for indicator parameter selection are
included in this table. A separate list of hazardous constituents to be monitored
was also developed based on the waste analysis.

     Because the facility accepts only a limited number of 40 CFR Part 261 Appendix
VIII constituents and initial monitoring verified the absence of many constituents,
the facility  owner or operator was able to minimize the total number of
constituents monitored in ground water. The process of constituent elimination is
dependent on the actual wastes received by the facility and the physical and
chemical properties of these constituents that influence their migration potential
(e.g., octanol/water partition  coefficients, solubility, adsorptivity, susceptiblity to
biodegradation).

     Non-halogenated  solvents  have relatively  low  partition coefficients
(Kow: benzene « 100; toluene = 500)  and are  not readily  retained  by soils.
Conversely, polycyclic aromatic hydrocarbons, constituents of petrochemical wastes,
have very  high partition coefficients  (e.g., chrysene a 4x10s) and are generally
immobile in soils.  Migration  rates of metals are also influenced by the exchange
                                   15-51

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      TABLE 15-7
INDICATOR PARAMETERS
Parameter
Total Organic Carbon (TOO
Total Petroleum Hydrocarbons
Total Organic Halogen (TOX)
Nitrates
Chloride
Sulfides
PH
Total phenols
Criteria for Selection
Collective measure of organic substances present
Indication of petroleum waste products
Halogenated organic compounds are generally
toxic, refractory, and mobile
Mobile contaminant, degradation product of
nitrogen compounds
Plating solution constituent, highly mobile in
ground water. Early indicator of plume arrival
Toxic, biodegradation by product, strong
reducing agent, may immobilize heavy metals
Good indicator of strongly acidic or alkaline waste
leachates close to sources
Collective measure of compounds likely to be in
waste. Even small concentrations can cause
olfactory problems following water treatment by
chlorination
        15-52

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capacity of the soil.  Different metal species are sorbed to different extents.
Following an assessment of the migration potential of each waste constituent, the
need for analysis of that constituent can be prioritized.
Case Discussion
     Waste stream information was used to determine appropriate monitoring
constituents and indicator parameters. The use of the existing initial ground-water
quality data and  the  incoming  waste analyses allowed for prediction  of
contaminants of concern in ground water and reduced the number of constituents
requiring analysis.
                                   15-53

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CASE STUDY 10:     USING WASTE REACTION PRODUCTS  TO DETERMINE AN
                   APPROPRIATE MONITORING SCHEME

Point Illustrated

    •   It is important to consider  possible waste reaction  products when
         developing monitoring procedures.

Introduction

    Volatile organic priority pollutants have been detected in ground  water at
various areas across the country.  These compounds, widely  used as solvents, are
generally considered environmentally mobile and persistent.  Increasing evidence,
however, indicates that chlorinated solvents can be degraded under anaerobic
conditions by reductive dehydrochlorination.  The sequential removal of chlorine
atoms from halogenated 1 and 2 carbon aliphatic compounds results in formation
of other volatile priority pollutants which can be detected during investigations of
solvent contamination.

Facility Description

    The facility  is a small municipal landfill  sited on a former sand and gravel
quarry.  In addition to municipal wastes, the landfill accepted trichloroethane and
tetrachloroethene contaminated sludge from a local fabrication plant until 1975. In
1983,  a municipal well located downgradient of the landfill tested positive  for
dichloroethane, dichloroethene isomers, and vinyl chloride. This prompted the city
to investigatt the cause and extent of the problem.

Site Investigation

    According to records kept at the facility, some of the compounds found in the
municipal well were not managed at the facility. This prompted the city to request
that a monitoring program be developed to determine whether another source was
causing well contamination.  A careful search of the city records, however, failed to
indicate a credible alternative source of the compounds.  Suspecting  that the
landfill was the source of the  well contaminants, five monitoring wells were
                                  15-54

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installed (Figure 15-15) and water samples  were analyzed  for halogenated
compounds using EPA Method 601.  The results, given  in Table 15-8, show an
increase in degradation products of trichloroethane and tetrchloroethene with
increasing distance from the landfill. Using these data, supported by hydrogeologic
data from the monitoring wells, the municipal landfill was shown to be the source
of the observed contamination.

                               TABLE 15-8
                  RESULTS OF MONITORING WELL SAMPLING

Chlorinated Ethanes
(l)Trichloroethanes
(2) 1,1-Dichloroethane
1,2-Dichloroethane
Chloroethane
Chlorinated Ethenes
(l)Tetrachloroethene
Trichloroethene
(2) 1,2-Dichloroethenes
1,1-Dichloroethene
Vinyl Chloride
WELL NUMBER (See Figure 15-15 for
well locations)
1

10(3)
71
ND
NO

80
12
ND
ND
ND
2

68
240
12
21

13
100
990
ND
120
3

ND(4)
130
?1
18

ND
62
950
ND
59
4

ND
11 '
ND
160

ND
ND
150
ND
100
5

ND
13
ND
ND

ND
ND
ND
ND
ND
      (1) Parent Compounds
      (2) Degradation Products
(3) All Concentrations In Micrograms/L
(4) ND means < 10 Micrograms/L
Case Discussion

    Based on the compounds found in the municipal well, the city believed that
the municipal landfill could  not  be the source of the contamination.  If this
reasoning had been followed, then a system of monitoring wells might have been
needlessly installed elsewhere in the attempt to find an alternate source of the
                                  15-55

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               .„._?T3perty Line
                    Approxim*c« Scale  L"»!00
                                                              Direction
                                                              Of
                                                              Ground
                                                              •low
                    MOTE: Locations of ntarby industrial
                          facilities noc shown.
Figure 15-15.    Site Map and Monitoring Well Locations
                         15-56

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contamination.  Instead, after carefully researching local industries, it was
determined that the landfill was the most reasonable source of the contamination
and that the observed well contaminants were probably degradation products of
the landfilled solvents. The progressive dehalogenation of chlorinated ethanes and
ethenes, as shown  in Table 15-8, is commonly encountered in  situations where
chlorinated solvents are subjected to anaerobic conditions (Wood, 1981). Different
degradation reactions may occur when pesticides are subjected to acidic or alkaline
conditions or biological degradation.  Therefore, it is important to keep reaction
products in mind  when designing  any monitoring scheme or interpreting
contaminauon data.

Reference
Wood, P.R., R.F. Lang, I.L  Payan.and J. DeMarco. 1981. Anaerobic Transformation.
Transport and  Removal of Volatile Chlorinated  Orqanics in Ground Water  First
International Conference on Ground Water Quality Research, October 7-10, 1981,
Houston, Texas.
                                  15-57

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CASE STUDY 11:      CORRECTIVE MEASURES STUDY AND THE IMPLEMENTATION
                   OF INTERIM MEASURES

Points Illustrated

     •   Interim corrective measures may be necessary to protect human health or
         the environment.

     •   The evaluation of the need for definitive corrective measures.

Introduction

     The development and  implementation  of a  comprehensive Corrective
Measures Study can be a time-consuming  process.  Between  the  time of the
identification  of a contaminant release and the completion of definitive corrective
measures, existing conditions or contaminant  migration can endanger human
health or the environment.  Under such conditions interim -measures may be
necessary.   The case study presented  below illustrates the implementation of
interim measures to  reduce contaminant migration and to remove the imminent
threat to the nearby  population from exposure to contaminants in drinking water,
and also illustrates the decision- making process  as to whether definitive corrective
measures may be necessary.

Facility Description

     The facility in this case  study is  an underground tank farm located at a
pharmaceutical manufacturing plant.  The tank farm  encompasses an area
approximately 140 feet by 260 feet and contains 30 tanks  ranging  in size from
12,000 to 20,OtO gallons. The tanks are used to store both wastes and raw materials
for the various batch manufacturing processes  performed at the plant. Typical
wastes include carbon tetrachloride, acetonitrile and chloroform. At the time of the
release, the tank farm had no cap to prevent the infiltration of rainfall or runoff. It
also did not have berms to provide containment for surface spills. No leak detection
or leachate collection systems were present.
                                  15-58

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Geological and Hydroloqical Setting

     The site is underlain by silty soil overlying limestone. The weathered limestone
beneath the site is very permeable (up to 210 ft/day) due to the solution of rock
along joints and bedding planes in the limestone.  Depth to the limestone varies
from 3 to 80 feet beneath the tanks and from  15 to 190 feet downgradient of the
site.

     The ground-water system beneath the site consists of two aquifers. The upper
one, an unconfined  limestone aquifer, is about 300 feet below the surface.  The
deep aquifer is an artesian aquifer in another limestone formation about 1200 feet
below the land surface.  Ground-water flow in the upper aquifer is controlled by
both  the regional flow system and  local  channelized  flow through  solution
conduits. The upper aquifer discharges to a canal 3 miles north of the site. Figure
15-16 shows the ground-water elevation  contours in the vicinity of  the  site.
Regional average ground-water flow velocity was estimated at 4 ft/day, but ground-
water velocities on the order of 50 ft/day have been measured in some channelized
areas. Channelized flow is also responsible for local deviations in flow direction.

Release Characterization

     A contaminant release from the tank farm was discovered when one of the
tanks used for waste storage was found to be empty. The waste stored in the tank
was predominately carbon tetrachloride (CCU) (a carcinogen with an MCL of 0.005
mg/l, with some acetonitrile (a systemic toxicant with a water-based health criterion
of 200 ug/l) and chloroform (a systemic toxicant with a water-based health criterion
of 400 ug/0 reference dose (RfD) is 0.4 mg/l).  Approximately 15,000 gallons of waste
liquids had  been routed to the tank before the leak was discovered.  Excavation of
the tank revealed ruptures in at least three locations.  Initial ground-water
monitoring after the tank rupture was" discovered identified CCU in a well 2500 feet
downgradient of the site, at concentrations above the MCL for CCU of 0.005 mg/l.

     Contaminants from the leaking tank were found to  have dispersed laterally
within a two-foot-thick sand bed which underlies the tanks. The contaminated area
                                  15-59

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                                                             ®MW22
   SMW20
     313
         Elevation aoove
         Mean Sea Level
        ' Grounowattr
         Flow Lines
         Groundwattf
         Monitoring Well
         (ana El«v m Ft )
         Contour* BiMd
         taken on 9/2/84
         (Contour interval 0 2 Ft )
                                                       -co:
               <§MW1
Water ueveta
Figure 15-16.   Ground-Water Elevations and Flow Directions in Upper Limestone

                 Aquifer
                                         15-60

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was approximately 5600 ft2.  High levels of CCU were found throughout the sand
layer. Concentrations of CCU in the natural soil ranged between undetected and
2200 mg/kg.  Observed concentrations were well above the soil RSD for CCU (2.7
mg/kg). Concentrations generally decreased with depth due to adsorption onto the
clay particles in the soil.  Carbon tetrachloride apparently moved downward with
Httle lateral dispersion until reaching the soil-limestone interface. Upon reaching
the unsaturated limestone, the contaminants then  appeared to have rapidly
dispersed over an area of about 12 acres before entering the aquifer.

Interim Corrective Measures

     Immediate action  to  contain the release  in the aquifer was  taken.  This
involved  pumping the well where CCU had been found continuously at its full
capacity of 450 gpm.

     All drinking water in the vicinity of the release was  obtained from wells
installed in either the shallow or artesian aquifer. Immediately after the detection
of the release, all domestic  and industrial wells north of the facility were tested for
CCU contamination. Test results showed contamination of several shallow water
supply wells.   Based on this information and the inferred ground-water flow
direction to the north-northeast, wells serving two small communities and a nearby
motel were closed.  The facility operator hired all mobile water tanks available and
supplied  water for immediate  needs until a  temporary water supply could be
implemented.  Water from an  unaffected artesian well was then used to supply
water to these communities.

     The design and operation of the tank farm was altered in an attempt to avoid
similar problems in the future.  A fiber-reinforced concrete cap was installed over
the tank farm to prevent the infiltration of rainfall and runoff, thus minimizing
further contaminant migration in the soil. The ruptures were repaired, and a tank
monitoring system was also developed and implemented at the site.

Definitive Corrective Measures:  Saturated and Unsaturated Zones

     A comparison of CCU concentrations within the ground water to the MCL for
CCU (O.OOSmg/l) indicated  that definitive corrective measures may be necessary.
                                   15-61

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Due to the high mobility of CCU within the unsaturated zone, and the potential for
continued inter-media transfer from this zone to the ground  water, definitive
corrective measures for both the saturated (ground water) and unsaturated zones
should be evaluated in a Corrective Measures Study (CMS).

Case Discussion

     The development and implementation of definitive  corrective measures at a
site may take a substantial length of time. Depending on the nature and severity of
the release and the proximity of receptors, interim measures, such as alternative
water supplies, were  required to minimize the effects on human  health and  the
environment.  Comparison of constituent concentrations with  health  and
environmental criteria indicated that definitive corrective measures may be
necessary and that a Corrective Measures Study (CMS) should be initiated.
                                  15-62

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CASE STUDY 12:     USE OF AERIAL PHOTOGRAPHY TO IDENTIFY CHANGES IN
                   TOPOGRAPHY INDICATING WASTE MIGRATION ROUTES

Points Illustrated

     •    Aerial photographs can be used to obtain valuable data on facility-
          related topographic features, including  type of waste management
          activity, distance to residences and surface waters, adjacent land use, and
          drainage characteristics.

     •    Detailed interpretation of aerial photographs can identify actual and
          potential waste migration routes and areas requiring corrective action.

Introduction

     Stereoscopic pairs of historical and current aerial photographs were used to
assist in the analysis of waste management practices at a land disposal facility.
Stereo viewing enhances the interpretation of aerial rvhotographs because vertical
as well  as horizontal spatial relationships can be observed, and  because the
increased vertical resolution aids  in distinguishing various shapes, tones,  textures,
and colors within the study area.  Typical items that should be noted include  pools
of unknown liquid that may have been released from buried materials which could
migrate off site through drainage channels. Soil discoloration, vegetation damage,
or enhanced vegetation growth can also be indicative of contaminant migration.

Facility Description

     The site contains an active land disposal facility which receives bulk hazardous
waste, including sludges and contaminated soil for burial, and liquid wastes for
disposal into solar evaporation surface impoundments.   Operations at the facility
began in 1969.  Historical and current aerial photographs were reviewed  to assess
waste management practices  and to  identify potential  contaminant migration
pathways requiring further investigation and corrective action.
                                   15-63

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Data Collection and Anavsis

     Low altitude color aerial photographs of the facility (scale =  1:8400) were
obtained in October 1983 and Feburary 1984. The photos were interpreted by an
aerial photo analyst at the U.S. EPA Environmental Monitoring  and Support
Laboratory at Las Vegas, Nevada. Figure 15-17showstheanalyzed photograph. The
interpretation code is given  in Figure 15-18.  Analysis of the photograph indicates
several areas of seepage at the base of the surface impoundments.  This seepage
indicates that either the impoundments are not lined or the liners have failed.
Drainage from the western portion of the facility which contains most of the
impoundments flows into a drainage  reservoir formed by a dam across the main
drainage. Drainage from the northeast portion of the facility where seepage was
also observed appears to bypass this reservoir and enter the main drainage which
flows offsite. Besides possible surface contamination, this seepage  also indicates
potential subsurface contamination.

     The aerial photograph  obtained in February 1984 (Figure 15-19) indicates the
continued existence of seepage from the surface impoundments. There is evidence
of possible discharge  from the drainage reservoir to a stream channel, as a pump
and piping were observed. Additional material in the solid waste disposal area has
altered the drainage pattern.  At the south end of this area, seepage is evident in
association with damaged vegetation. Drainage from this area enters a drainage
system and appears to be diverted offsite.

Case Discussion

     Analysis of aerial photographs of the land disposal  facility  enabled
investigators to identify potential contaminant sources and migration  pathways.
This  information was used by investigators to identify areas for surface water,
sediment, soil, and subsurface sampling.
                                   15-64

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                      '
-------
                      INTERPRETATION CODE
                      BOUNOAHI6S AND LIMITS
                      !_•_!..  'iNcn an IOUNOAHV
                      —~  UNMNCID art MUNOAMV
                      I I I I I  »f NC(
                      _-_  MOPtMTV UNI
                      ^ /—  GAri/Accra MINT
                        -|—    SICT10M COHNfH

                      DRAINAGE
                       ••— — -  OMAINACI
                        «    •  'LOW OlNICTION
                      •••-.••• INO(TfH«lMNAT|
                     TBAMSPOHTATIQN/UTlLlTV
                      SXS33  vlHICLf ACCIM
                      art
                       IMHIMttlH OIKK
                              ITANOIMO LIQUID
                         «,    STANDING UOUlO
                               iSMAkU
                              OIXCAVATION. *«T
                               KXTINIIVII
                              MouMon
                              MOUNOIO MATIMIAk
                               (SMAkU
                         Cfi
                         OM   OHUMB
                         HT   MOMnNTAk rA«M
                         »r   MUSUIIf TAM«
                         VT   VINTICAk TADM

                         CA   CUAHfO AIIIA
                         OG   OISTUMIO aHOUNO
                         IM
                         to
                         00   OHM OUM»
                         SO   SLUOGI
                         ST   STAIN
                         SW   1OLIO MAtTt
                         T«   TMINCM
                         «0   NAfTt OIVOSAk A«|A
Figure 15-18.    Aerial Photograph Interpretation Code
                              15-66

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                 EROSION!
                I OF ROAD

                           I AERIAL
                            SURVEY
                            MARKER!
TANK TRUCK]
UNLOADING gDG]


                                                                    r\

              I TANK

             "<.Z^*
I AERIAL
I SURVEY
I MARKER!
 tite
                                   *"***' '
                                                     I DAMAGED
                                                     (VEGETATION!
                                          .UIH l-
                                                  [RESERVOIR"
                         AERIAL
                         SURVEY
                         MARKER!
                                       [DISCHARGE
                                       INTO STREAM|
                                       CHANNEL
             Figure 15-19.   February 1984 Aerial Photograph of Land Disposal Facility
                                        15-67

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CASE STUDY 13:     IDENTIFICATION OF A GROUND-WATER  CONTAMINANT
                   PLUME USING INFRARED AERIAL PHOTOGRAPHY

Point Illustrated

     •    Infrared photography can assist in identifying contaminant plumes and
          in locating monitoring wells by showing areas of stressed vegetation and
          contaminated surface water.

Introduction

     Infrared aerial  photography can assist .1 identifying contaminant plumes at
sites where little or  no monitoring has been conducted.  By identifying areas of
stressed vegetation or contaminated surface water, it may be possible to focus on
contaminant discharge points and roughly  define the extent of a release.
Hydrogeologic investigations and surface water sampling can then be performed to
further characterize the release.  Infrared photography offers  the potential to
increase the efficiency of a sampling program.

Facility Description

     The facility is a municipal solid waste landfill which has served a population of
22,000 for 30 years.  The facility covers an area of 11 acres, holding an estimated
300,000 tons of refuse. The majority of waste in the landfill was  generated by the
textile industry.  Until  July 1978, the facility was operated as an  open dump with
sporadic management. City officials indicated that original  disposal occurred in
open trenches with little soil cover. After July 1978, the facility was converted to a
well-operated sanitary landfill. Figure 15-20 shows the facility.

Geologic Setting-

     The landfill  is located on a sandy to silty till varying in thickness from 23 feet at
the hill crest to 10 feet on the side slope.  A swamp is present at the base of the hill
at about 255 feet above sea  level. There is a dam at the southern drainage outlet
                                   15-68

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              o  BACKGROUND  WELL a
                     METAL
                        BACKGROUND WELL
                                                                             N
TREE
KILL
AND      >
STRESS  (
                                                                SCALE  (APPROXIMATE)

                                                                        0    332'    564'
                                                                   SWAMP

                                                             	TREE LINE

                                                              •    WATER
                                                              O    WELL LOCATION

                                                              Q    VEGETATION SAMPLING

                                                             	 STREAM

                                                              «    STREAM SAMPLING POINT

                                                              •    HOUSING
                       Figure 15-20.  Facility Plan View
                                     15-69

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of the swamp, a distance of 2,500 feet from the landfill.  Ground  water is
approximately 20 feet below the surface at the crest of the hill, while on the slope it
is approximately 6 feet below the surface. The swamp at the foot of the  hill is the
surface expression of the ground water (Figure 15-21).

Aerial Photography and Sampling Program

     Figure  15-22 shows the infrared aerial  image of the site.  The landfill
corresponds to the light area  in the northwest portion of the photograph (Figure
15-21). The dark area to the south of the site is stressed vegetation, and the light
area within it is contaminated swamp water. The 33-acre area of tree kill and stress
is clearly visible in the original photograph. Plants under stress may be detected by
infrared photography because of changes in infrared reflectance.

     Ground-water monitoring wells and vegetation sampling points are  shown in
Figure 15-20.  Data collected from the wells indicated elevated levels of chromium,
manganese,  iron,  and total organic carbon (TOC).  Table 15-9 lists the average
concentrations of the parameters tested.  The vegetation study indicated an
accumulation of heavy metals.

Case Discussion

     The vegetative stress apparent in the infrared photography was confirmed by
the data from the ground water and vegetation sampling.  However, the site
requires further characterization to determine the vertical extent of contamination
and to assess the potential  for impact  beyond the present area of stressed
vegetation.

     It should  be emphasized that infrared  photography is not a substitute for
hydrogeologic characterization. However, it is a useful tool for identifying areas of
stressed vegetation that may be associated with releases from waste disposal sites.
                                  15-70

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                                      15-73

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CASE STUDY 14:     USE OF HISTORICAL AERIAL PHOTOGRAPHS AND FACILITY
                  .MAPS TO IDENTIFY OLD WASTE DISPOSAL  AREAS AND
                   GROUND-WATER FLOW PATHS

Points Illustrated

    •   Aerial photographs taken over many years in the life of a facility can be
         used to locate old solid waste management units (SWMUs).

    •   Historical  aerial  photographs can  be used  to  identify
         geologic/topographic features that may affect ground-water flow paths.

Introduction

    In gathering information pertaining to investigation of a release, historical
aerial  photographs and facility maps can be examined and compared to current
aerial  photographs and facility maps. Aerial photographs  can be viewed as stereo
pairs or individually.  Stereo viewing, however, enhances the interpretation  because
vertical as well as horizontal spatial relationships can be  observed.  The vertical
perspective aids in distinguishing various shapes, tones, textures, and colors within
the study area.

    Aerial photographs and facility maps can be used for the following:

    •   Providing evidence of possible buried drums. Historical photographs can
         show drums disposed of in certain areas where  later photographs show
         no indications of such drums, but may show that the ground has been
         covered with fill material.

    •   Showing  previous areal extent of landfill or waste management area.
         Earlier photographs might show a much larger waste management area
         than later photographs.

    •   Showing areas that were dry but now are wet, or vice versa, indicating a
         possible release from an old waste management  area.
                                  15-74

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     •    Showing changes  in land use patterns (e.g., a landfill  m  an early
          photograph could now be a park or be covered by buildings).

     •    Soil discoloration, vegetation damage, or enhanced vegetative growth
          can sometimes be detected, indicating possible contaminant migration.

     •    Geologic/hydrologic information, such as faults, fracture or joint systems,
          old stream  courses  (channels), and the contact between moraines and
          outwash plains.

 Facility description

     This facility is the same as previously described in Case Studies 7 and 8.

 Data collection and analysis

     Over the past  50 years aerial photographs were taken  of the facility area.
 Interpretation of the photographs produced important information that is shown
 diagramatically in Figure 15-23. Solid Waste Disposal Area 2 (SWDA-2) was lower in
 elevation in 1940 than it is now.  In fact, the area appears to have been leveled and
 is now covered by vegetation, making it difficult to identify as a SWMU at ground
 level. Another area was identified as a possible waste disposal area from a  historical
 review of photos.  Further study of photographs, facility maps and  facility files
 revealed this to be  a  former Liquid Waste Disposal Area (LWDA), designated  as
 LWDA-2 on Figure 15-23.

     The use of these historical photographs also revealed geologic features that
 could affect  the  ground-water flow system  under the facility.  In this case,
 monitoring well data indicated a general northwesterly ground-water flow
 direction, in addition to a complex flow pattern near LWDA-1 and SWDA-1 (Figure
 15-23). Recent photographs were analyzed, but because of construction and other
 nearby activities (e.g., cut and fill, sand and gravel mining), conclusions could not be
drawn. A review and analysis of old photographs revealed the existence of a buried
stream channel of the river  (Figure 15-23).  This buried stream channel was
identified as a preferential path  for ground water and consequently contaminant
                                   15-75

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migration. Additional monitoring data and further analysis of subsurface geologic
data is needed to determine the full impact of the  buried stream channel on the
ground-water flow regime.

Case Discussion

     Analysis and interpretation of a series of historical aerial photographs  and
facility maps spanning a period of over 50 years enabled facility investigators to
identify the following:

     (1)   Location of waste disposal areas (e.g., old SWMUs);

     (2)   Changes in topography (related to earlier disposal activities); and

     (3)   Possible preferential pathways (e.g., old stream channel) for migration of
          ground water and contaminants.

     This information was used to  identify areas for more detailed sampling  and
analysis.

     Analysis of  historical  facility maps and historical aerial  photographic
interpretation can be a very  powerful  tool in  a RCRA  Facility Investigation,  but
should be used  in combination  with other investigative techniques to result  in a
thorough characterization of  the nature,  extent, and  rate  of contaminant
migration.
                                   15-77

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CASE STUDY 15:   USING  SOIL CHARACTERISTICS TO ESTIMATE  MOBILITY OF
                 CONTAMINANTS

Point Illustrated

    •    Information on soil characteristics can be used to estimate the relative
          mobility of contaminants in the subsurface environment.

Introduction

    The  relative mobility of contaminants  can be  estimated  using soil
characteristics and aquifer hydraulic characteristics. Although metals do precipitate
at higher concentrations,  at the levels encountered in most subsurface
environments, sorption is the dominant attenuation process. The degree to which a
metal sorbs onto soil particles depends on the soil pH, the percent clay, the percent
soil organic matter, the presence of particular coatings (e.g., iron, manganese, and
aluminum oxide/hydroxides) and, to a lesser extent, the type of clay present.  For
organic contaminants, there  are several processes which may be important in
predicting their fate in soils.  These include sorption, biodegradation, hydrolysis
and, to a lesser extent, volatilization.  The sorption of a given organic compound
can be predicted  based on its octanol-water partition coefficient, the  percent
organic carbon in the soil, and the grain-size distribution of the soil.

    Determining the relative mobility of contaminants can be helpful  in selecting
appropriate  sampling locations. For example, if wastes containing metals were
present in an impoundment, samples to determine the extent of any downgradient
metal contamination would normally  be collected within  a short distance of the
impoundment.  On the other hand, for fairly mobile waste  constituents such as
trichloroethylene (TCE), samples could  be taken over a much larger downgradient
distance.  The case study presented below illustrates how contaminant mobility can
be estimated.

Facility Description

    A 17-acre toxic waste dump was operated in a mountain canyon for 16 years.
The facility received over 32  million gallons of spent acids and caustics in  liquid
                                  15-78

-------
form. These wastes were placed in evaporation ponds.  Other wastes sent to the
facility included solvents and wastes from electroplating operations containing
chromium, lead, mercury and zinc.  Pesticides including DDT had been disposed of in
one corner of the site.

Site Description

     The site was underlain by alluvium and granitic bedrock (Figure 15-24).  The
bedrock, as it was later discovered, was fractured to depths of between 50 and 100
feet  Ground water occurred in the alluvial deposits at depths of 10 to 30 feet.
Several springs existed in the upgradient portion of the site.  A barrier dam was
built across part of the canyon at the downgradient edge of the site in an effort to
control leakage.  Because of the  extensive fracture system, this barrier was not
effective.  Instead, it appears to have brought the ground-water table up into the
wastes and, at the same time, pressurized the underlying fracture system, thereby
creating seepage of contaminated water under the dam.

Estimation of Contaminant Mobility

     Because of the variety of constituents accepted at this site, an estimate of their
relative mobility was needed prior to designing the remedial investigation. The first
step was to estimate the average linear velocity using the following equation :
           Ki
     V  s  	
           He
where
     v    =   horizontal seepage velocity, ft/day
     K    =   hydraulic conductivity, ft/day
     i     =   ground-water gradient
     He    =   effective porosity, decimal fraction.

     The hydrogeologic data needed were obtained from existing site assessment
reports.  The alluvium underlying the site had an average hydraulic conductivity of
0.8 ft/day and an estimated effective porosity of 11 percent.  The average ground-
                                   15-79

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water gradient below the site was 0.06.  Using the above equation, the average
linear velocity was estimated to be 160 ft/yr. This represents the average velocity at
which a conservative constituent would migrate downgradient along the centerline
of the plume.   Examples of such constituents include chloride  and bromide.  As
shown in Table 15-10, nitrate and sulfate also behave conservatively in many cases.
Due to the absence of highly weathered,  sesquioxide soils, sulfate  behaved
conservatively at this site. Using the above average linear velocity, an estimate was
made of the distance a conservative solute would travel in a given time (T) using
d = vT.  Limited water quality  data were available for 1980.  Wastes were first
disposed  at this site in  1956.  The average extent of plume migration along the
centerline was thus estimated to be 3800 feet.

     With respect to metals, additional data were  needed to estimate their fate
including soil pH, presence of carbonates, organic ligands, and percent soil organic
matter and clay. At this site, the soil pH varied from less than  3.0 within 400 feet of
the acid  ponds to 7.2  at a distance 2000 feet downgradient. As shown in Figure
15-25, the partition coefficients for metals are dependent on pH and organic matter
content.  For example, below a pH of 5.6, for the types of soil encountered at the
site, the partition coefficient (Kp) for cadmium is about 10 ml/g. At a pH of 7.2, Kp is
about 6500 ml/g (Rai and Zachara,  1985).  The relative mobility of attentuated
constituents can be estimated as follows (Mills eta[., 1985):

     VA  =  v/Rd
where
     VA   =    average velocity of attentuated consitutent along centerline
                   of plume, ft/day
     v    =    average linear velocity as defined above, ft/day
     Rd   =    retardation factor (unitless)

and

     Rd   =    1 +
                                   15-81

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                          TABLE 15-10

                 RELATIVE MOBILITY OF SOLUTES
Group
Conservative




Slightly Attenuated

Moderately Attenuated
More Strongly
Attenuated
Examples
TDS
CL"
BR-
NO;
SO42-
B
TCE
Se
As
Benzene
Pb
Hg
Penta-
chlorophenol
Exceptions



Reducing conditions
Reducing conditions
and in highly
weathered soils coated
with sesquioxides
Strongly acidic systems
Anaerobic conditions


Master Variables*
V




v, pH, organic matter
v, organic matter
v ,pH,.Fe hydroxides
V , pH, Fe hydroxides
v, organic matter
v , pH, SCV
v.pH.CI
v , organic matter
Variables which strongly influence the fate of the indicated solute groups.
Based on data from Mills etal., 1985 and Roi and Zachara, 1984.
                             15-82

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                   100
    Percent
    Adsorbtion
    by Soil
                   50
                             Shift due
                             to presence
                             of soil organic
                             matter
Typical
adsorbtion
curve for
heavy metal
x, on a clean
silica or
aluminum
silicate
surface
                                             Typical adsorbtion
                                             curve for heavy
                                             metal x, on silica
                                             or aluminum silicate
                                             surface coated with
                                             soil organic matter
                                             pH of the Soil Solution

                       a) Generalized Heavy Metal Adsorbtion Curve for Cationic Species (e.g., CuOH*)
                      100
       Percent
       Adsorbtion
       by Soil
50
                                         Typical adsorbtion   \
                                         curve for heavy      \
                                         metal species, x,      \
                                         on iron hydroxide      \

                                                  \
                                                   \
                                               Shift    \
                                               due to   \
                                          \     pretence  t
                                           \    of soil    \
                                            \     organic   \
                                            \    matter
                                             \

                                              V      .      v
                                             pH of the Soil Solution
                                                                                         2-,
                        b) Generalized Heavy Metal Adsorbtion Curve for Aniotic Species (e.g., CrOj")
Source:  (Milh M •!.. 19881.
    Figure 15-25.    Hypothetical Adsorption Curves for a) Cations and b) Anions
                       Showing  Effect of pH and Organic Matter
                                             15-83

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where

     Kp   =    soil-water partition coefficient for solute of concern, ml/g
     PB   =    soil bulk density, g/ml
     ne   =    effective soil porosity (decimal fraction).

For example, the relative mobility of cadmium at a pH of 7.2 was estimated for this
site as shown below:

     Rd = 1  + 6500(1.7) = 100,456
                0.11
     VA = 160/100,000 * 0.002 ft/yr.

This  estimate was consistent with the field data which indicated that the metals
migrated only until the pH of the contaminant plume was neutralized, a distance of
about 2000 feet. Cadmium concentrations decreased from 1.3 mg/l at a distance of
1400 feet from the ponds to below detection (<0.1 ug/l) at a distance of 2000 feet.

     Estimates of mobility for organic contaminants which sorb onto soil particles
can be made in an analogous  manner.  The partition coefficient for  organic
constitutents can be calculated using the following equation (MillsetaL, 1985):

     Kp = K0c[0.2(1-f)X'oc + fXfoc]

where
     Kp   =    soil-water partition coefficient, ml/g
     KOC  =    organic carbon partition coefficient, ml/g
     and
     Koc  s    0.63 Kow
     KQW  s    octanol-water partition coefficient
     f    =     mass of silt and clav (0< f< 1)
               mass of silt, day and sand
     X'oc  a    organic fraction of sand (X$oc<. 0.01)
     Xfoc  s    organic fraction of silt-clay (0 <. Xfoc.< 0.1).
                                   15-84

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For example, the solvent trichloroethylene (TCE) has a Kow value of 200. Using the
above equation and site data (f = 0.1, X50c  = 0.001, Xfoc  = 0.01), the partition
coefficient Kp was estimated to be 0.2 ml/g. The relative mobility of TCE at the site
was then estimated to be approximately 40 ft/yr (Rd  = 4 and VA  = 40 ft/yr).
Methods for considering additional processes influencing the fate of organics (e.g.,
hydrolysis and biodegradation) are presented in the manual  entitled Water Quality
Assessment:  A Screening  Procedure for Toxic and Conventional Pollutants in
Surface and Ground Water (Mills et al.. 1985).

Case Discussion

    As shown in Figure  15-26, contaminants downgradient  of a waste disposal site
may migrate at different speeds. Using the methods illustrated above, estimates of
the relative mobility of constituents can be made. Such estimates can then be  used
to locate downgradient monitoring wells and to assist in the interpretation of field
data.
References
Mills, W.B., D.I. Porcella, M.J. Ungs, S.A. Gherini, K.V. Summers, L Mok, G.L. Rupp,
and G.L Bowie. 1985.  Water Quality Assessment:  A Screening Procedure for Toxic
and Conventional Pollutants in Surface and Ground Water. EPA/600/6-85/002a. Vol.
I, II and III.
Rai, D. and J.M. Zachara. 1984. Chemical Attenuation Studies: Data Development
and Use. Presented at Second Technology Transfer Seminar:  Solute Migration in
Ground Water at Utility Waste disposal Sites. Held in Denver, Colorado, October 24-
25,1985. 63pp.
                                   15-85

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                             \
              TDS
                                                         FEET
                                                      I
                                                      0
                                                  I
                                                 800
Figure 15-26.
Schematic Diagram Showing Plumes of Total Dissolved Solids (TDS),
Total Organic Halogens (TOX) and Heavy Metals Downgradient of
Waste Disposal Site
                                 15-86

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CASE STUDY 16:     USE OF LEACHING TESTS TO PREDICT POTENTIAL IMPACTS OF
                   CONTAMINATED SOIL ON GROUND WATER

Point Illustrated

     o    Soil leaching tests can be used in conjunction with waste and site-specific
          factors to predict potential impacts on ground water.

Introduction

     Contaminated soil, whether deep, or surficial in nature, has the potential to
impact  ground  water, primarily through leaching.   In many  cases,   soil
contamination has already lead to contamination of the  ground  water  and
decisions can be  made regarding clean-up of the contaminated soil and ground
water based on the constituent concentrations observed in these media.  However,
in cases where contaminated  soil has  not yet resulted in  contaminated ground
water, but has some potential to  do so, decisions need to be made regarding the
contaminated soil and whether it should be removed or some other action should
be taken because of the soil's potential to contaninate ground water above levels
of concern. This evaluation may be especially critical in those cases where only deep
soils are contaminated, or where constituent concentrations within surficial soils do
not exceed soil ingestion criteria.  Both theoretical (mathematical) and physical
(leaching test) models can  be used in this evaluation, as well as or in conjunction
with a qualitative evaluation of release and site-specific factors. This case illustrates
the use  of leaching tests and  consideration of release and site-specific factors to
determine whether contaminated soil  has the potential to contaminate ground
water above levels of concern.

Facility Description

     The facility is an industrial chemical and solvent facility located on a leased 2.5
acre site within the corporate limits of a  major city in the north-central  United
States (see Figure 15-27). Periodic overtopping of the surface impoundment, which
is now empty, and suspected contamination of the  soil  with  organic solvents
from the surface impoundment, resulted in an RFI in which the facility was directed
to characterize the nature, extent and rate of release migration.
                                   15-87

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     Release characterization revealed that the soil surrounding the surface
impoundment, which was  mostly  fine sand  and  silt  with some clay, was
contaminated with tetrachloroethylene and 1,1,1-trichloroethane at concentrations
ranging from 0.05 to 0.10 and 2 to 20 mg/kg, respectively. This contamination was
observed at depths of up to  5 feet, which was approximately 20 feet above the
water table (i.e., the water table was approximately 25 feet below the land surface).
The soil beneath the site was relatively permeable, with a hydraulic conductivity of
approximately 9x10-4 cm/sec.

     Ground-water monitoring  conducted  during the RFI showed no current
contamination of the  ground water,  which flows in a northerly direction and
eventually intersects the river (Figure  15-28).  The river is  used for irrigation and
drinking at downstream locations.  Grab samples taken from the river and river
sediments showed no contamination.

     The soil in the immediate vicinity of the railroad spur also  showed isolated
pockets of mercury contamination, ranging in concentration from 1 to 2 mg/kg, and
to a depth  of 1  foot below the land surface. The source  of the  mercury
contamination could not be determined.

Contamination Evaluation

     The relevant health and environmental (HEA) criteria, the constituent
concentrations observed at the site, and selected physical/chemical properties for
the three constituents are shown  in Table 15-11. Although comparison of the HEA
criteria for  ingestion  with the consituent concentrations observed at the  site
showed no  exceedances, the regulatory agency overseeing the RFI was concerned
that leaching of the contaminated soil could lead to eventual contamination of the
underlying  ground water.  This  concern was  based on  the  relatively high
permeability of the soils beneath the site and the relatively high mobility of the two
organic constituents detected.  The  facility obtained the  regulatory agency's
approval to  conduct a leaching evaluation using EPA's Method 1312 (Synthetic Acid
Precipitation Leach Test for Soils).
                                  15-89

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                              TABLE 15-11

       HEA CRITERIA, CONSTITUENT CONCENTRATIONS AND RELEVANT
  PHYSICAL/CHEMICAL PROPERTY DATA FOR CONSTITUENTS OBSERVED AT SITE
Chemical
Tetrachloroethylene
1,1,1-Trichloroethane
Mercury
CAS No.
127-18-4
71-55-6
7439-97-6
HEA
Criteria
(Ingestion)
(mg/kg)
69 '
2,000
-
H20
Sol
(mg/l)
150
1500
~
HEA
Criteria
(Water)
(mg/l)
0.0069
0.2
0.002
Constit.
Cone.
(mg/kg)
0.10
20
2
Koc
(mg/l)
364
152
Low
Log
Kow
2.6
25
-
Det.
Limit*
(mg/l)
0.01
0.01
0.0004
*  Detection limits presented are those for water. Detection limits for soil vary greatly, but may
   be assumed to be approximately 1 mg/kg.
                                 15-91

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Leaching Evaluation.

     Prior to collecting samples and applying the leaching test, the facility first
decided to determine if the contaminated soils could possibly result in leaching test
(extract) concentrations that exceed the relevant HEA criteria (See Table 15-11). To
do this, the  facility calculated the maximum theoretical extract concentration by
assuming that 100 percent of the constituents would leach  from the soil.  The
following equation was used:

     Maximum Theoretical                 Concentration of Toxicant
                                  s
     Extract Concentration (mg/l)              in Soil (mq/kq)
                                                  20

where 20 refers to the liquid to solid ratio applied in EPA Method 1312.

     Using this simple equation, the facility determined that the maximum leachate
concentration for tetrachloroethylene was, in fact, below the HEA criteria for water
(see Table 15-11), and that the level could not possibly be exceeded even if 100
percent of the contaminant leached from the waste. For 1,1,1-trichloroethane and
mercury, however, it was determined that the HEA criteria level could be reached if
only a portion of the contaminant present leached from  the soil, and that
application of the  leaching test would  be necessary.  Using  this screening-type
evaluation, the facility was able to reduce the number of constituents that would
need to be analyzed when applying the leaching test, from three to two.

     Samples of the  contaminated soil  were then collected at selected  locations
(i.e., those expected  to  produce the more  heavily contaminated samples) and
Method 1312 applied. Total constituent analyses were also conducted in order to
ensure that the samples represented the  more heavily contaminated areas of the
site.  Analyses of the soils and  leaching test extract were conducted for  1,1,1-
trichloroethane and mercury. The results are shown in Table 15-12.

     The leaching test results for 1,1,1-trichloroethane and mercury showed extract
concentrations above   the  respective  HEA criteria   (action levels) for  these
                                   15-92

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                            TABLE 15-12

                   LEACHING TEST RESULTS (mg/l)*
Constituent
1,1,1-Trichloroethane
Mercury
D-C
0.3
0.002
C-C
0.2
0.002
C-B'
0.5
0.003
*  Resampled at locations close to original sampling point. Samples analyzed
   are result of composite of three grab-samples. All samples were taken from
   the top 0-1 ft of the soil surface.
                               15-93

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constituents, indicating that there might  be a basis to  require some sort of
corrective action. The facility, however, presented arguments to show that mercury
would be attenuated  in the soil column as the leachate percolates towards the
water table, and that 1,1,1-trichloroethane would be degraded to below the level
of concern in the ground water. Below is a synopsis of the two arguments.

     Mercury: The facility first examined theoretical Eh-pH fields of stability for the
various aqueous mercury species; determined that the predominant mercury species
would be elemental mercury, and further predicted (using Eh-pH diagrams) that the
maximum equilibrium concentration of elemental mercury in water would be 0.025
mg/l.  The facility interpreted the substantially lower leaching test concentration to
indicate that attenuation processes such as sorption play a major role in restricting
the mobility of elemental mercury. The facility cited high  soil/water partition
coefficients (i.e., Kd values), and several scientific studies to further support their
contention that mercury  would  strongly  sorb to both  organic and inorganic
components of the soil before any leachate reached the ground water.

     1.1.1-Trichloroethane: The facility recognized that due to its high solubility
(1500 mg/l) and low Kd (0.011 ml/g), 1,1,1-trichloroethane would not be attenuated
appreciably as the leachate percolates towards the water table. The facility argued,
however, that abiotic hydrolysis would significantly degrade 1,1,1-trichloroethane
during leaching. Several environmental half-life studies were cited which indicated
                                      /
that the half life for 1,1,1-trichloroethane ranged between 0.5 and 2.5 years. Based
on  these studies, the  facility predicted that 1,1,1-trichloroethane  would  be
degraded to below levels of concern within one to three years. Usin'g additional site
information  and simple time of travel calculations,  the facility predicted that
concentration  levels for 1,1,1-trichloroethane  would be  decreased  to  below the
level of concern well before reaching any potential receptors.

     The regulatory agency's evaluation of the facility's arguments is presented
below:

     Mercury: The facility's argument with respect to mercury is essentially correct
if it can be assumed or proven that the mercury originally present at the site is
inorganic in nature. If, however, the mercury present is organic in  nature (e.g.,
                                   15-94

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methyl mercury), the  potential for  migration  of the mercury is  substantially
increased.  Organic mercury compounds generally have  higher volatility,  higher
solubility, and much lower Kd values than inorganic mercury compounds.  It should
also be noted that even  if the original  release was of inorganic mercury,
biotransformation (i.e., biomethylation) of elemental mercury may occur.  The
facility should be required to determine the actual form(s) of mercury present at the
site.

     1.1,1-Trichloroethane:   The facility's  argument  with  respect to 1,1,1-
trichloroethane raises  many technical questions. For example, the facility  uses
published data on the  half life of  1,1,1-trichloroethane, which may not be
applicable to the facility's soil and ground-water environment. As another example,
the half-life degradation rate argument may only be applicable for ground-water
transport. The facility does not address degradation  in soil or effects on surface
water (assuming that contaminated ground-water will eventually migrate to the
river).  Most important, however, is the fact that the facility did not address the
degradation  products of  1,1,1-trichloroethane,  one  of which  is  1,1-
dichloroethylene, which is also a hazardous constituent. 1,1,1-trichloroethane
should be assumed to pose a threat to  ground water.

Conclusions

     The next step in the RFI process would be to determine if interim corrective
measures or a Corrective Measure Study was warranted for the release.  Although
none of the soil ingestion HEA criteria were exceeded at the site, application of the
leaching  evaluation indicated that 1,1,1-trichloroethane could leach to  ground
water and result in exceedance  of the HEA  criterion for water.  On this basis, the
facility should be directed to perform a Corrective Measures Study.

     To prevent further contaminant migration, the  application of  interim
corrective measures may also be considered. Construction of a temporary cap over
the contaminated area is one option.  Perhaps a more  appropriate measure would
be to remove the contaminated  soil. Such an action, taken as an interim corrective
measure, may negate the need for a formal Corrective Measures Study.
                                  15-95

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Case Discussion

     Leaching tests and  similar evaluations (e.g., application of  validated
mathematical leaching models) can be used to identify potential problems due to
leaching of contaminated soils.  In this case, application of a leaching evaluation
was instrumental in identifying a  potential threat to ground water as a result of
leaching of contaminated  soil.  This finding was particularly significant as HEA
ingestion criteria were not exceeded.

     It should be noted, however, that in some cases leaching  tests  may provide
results that are difficult to interpret.  For example, consider what  would  have
happened if the soil underlying the facility  was predominantly  clay  with a
permeability on the order of 10-8 cm/sec.  In this case, demonstrating that leaching
will most likely occur within the forseeable future  may be difficult. As  another
example, if the soil underlying the facility were predominantly sand, leaching would
be probable. In both these cases, application of a leaching test may not provide any
more useful information than is already available. Careful consideration of release
and site-specific information is always warranted prior to  application of leaching
tests.
                                   15-96

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CASESTUDY17:     USE OF SPLIT-SPOON SAMPLING  AND ON-SITE VAPOR
                   ANALYSIS TO SELECT SOIL  SAMPLES AND  SCREENED
                   INTERVALS FOR MONITORING WELLS

Point Illustrated

     •   HNU  and OVA/GC screening can provide a relative  measure of
         contamination by volatile organics.  It can be used to select soil sample
         locations  and can assist in the selection  of screened intervals for
         monitoring wells.

Introduction

     On-site vapor screening of soil samples during drilling can provide indications
of organic contamination. This information can then be used to identify apparent
hot spots and to select soil samples for detailed chemical analyses.  In this manner,
the use of higher powered laboratory methods can be focused in an effective way
on the analysis of samples from critical locations and depths. The vapor analyses o,.
site can also be helpful in selecting screened intervals for monitoring wells.

Facility Description and History

     Manufacturing  of plastics and numerous other chemicals has occurred at the
site over the past 30  years. Some of the major products included cellulose nitrate,
polyvinyl acetate, phenol, formaldehyde, and  polyvinyl chloride.  The entire site
covers 1,000 acres. The location of the buildings and waste disposal areas are shown
in Figure 15-29. This is the same facility as used in Case Studies 7, Sand 14.

     Three disposal methods are known to have been employed at the site. Readily
combustible materials  were incinerated  in four burning  pits, while  non-
combustibles were either disposed of in landfills or in a liquid disposal area. All on-
site disposal operations were terminated in  1970, and monitoring  programs have
been implemented to identify contaminants, define and monitor ground-water
contaminant plumes, and assess the resulting environmental impacts.
                                  15-97

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Geologic and Hydroloqic Setting

     The site is located in a well-defined glacial valley, adjacent to a river. Three
major units underlie  the site, consisting primarily of sand and gravel  outwash
deposits; fine-grained lacustrine sands;  and till. The middle sand  unit contains
lenses of silt, clay and till. Only the deep till formation  appears to be continuous
across the site.  A geologic cross-section beneath two of the disposal areas is shown
in Figure 15-30.

     The ground-water flow direction at the site is to the northwest. However,
there appears to be a buried stream channel running across the site which strongly
influences the local ground-water flow regime (see Figure 15-31).  Ground water
from the site is thought to discharge to the river. The depth to ground water varies
from 10 to 40 feet.

Sampling Program

     As part of the remedial investigation at this site, 33  borings were drilled using
a hollow-stem auger rig.  Continuous soil samples were collected using split-spoon
samplers.  Samples for laboratory chemical analysis were selected based on  the
volatile organic concentrations detected by  initial vapor screening of the  soil
samples in the field.

     This field screening was achieved by placing a portion of each sample core in a
40 ml glass headspace vial.  An aliquot of gas was extracted from the vial and
injected  directly  into a  portable OVA gas chromatograph (OVA/GC).  The
chromatograph was  equipped with a  flame  ionization detector to identify
hydrocarbons.  Each  sample  was also screened using an HNU photoionization
detector because of its sensitivity to aromatic  hydrocarbons, particularly benzene,
toluene and the xylenes. Following completion of drilling, gamma logs were run on
all boreholes.

     An-example of the vapor screening  results (HNU and OVA/GC) and geological
and gamma logs for one of the boreholes are shown in  Figure 15-32. The data
shown demonstrate the differential sensitivity of the HNU and OVA/GC detectors.
Because the OVA/GC  is more sensitive to the organics of  interest  (aliphatics),
                                  15-99

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15-103

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these results were  used to select samples for detailed chemical analysis in  the
laboratory. As shown in Figure 15-32, samples in zones with OVA/GC readings of
365 ppm (45 feet deep), 407 ppm (65 feet deep), and 96 ppm (85 feet deep) were
selected. In the laboratory, samples were first analyzed  for total organic carbon
(TOC).  The ten samples with the  highest TOC levels were then  analyzed for
purgeable organics using EPA Method 50-30 and  extractable organics  using EPA
Method 82-50 (U.S. EPA, 1982 - Test Methods for Evaluating Solid Waste, SW 846).

     The OVA/GC results were also used to select well screen intervals. Examination
of the data in  Figure 15-32 shows that the highest levels of volatile organics (by
OVA/GC) were  found at a depth of 65 feet. In addition, the gamma and geologic
logs indicated  that the permeable medium at that depth was coarse sand which
would be a suitable location for the placement of a well screen.  Thus,  a 5-foot
stainless steel screen was set over the depth interval of 62 to 67 feet.

Case Discussion

     This sampling program incorporated field techniques that detect the presence
of volatile organics and allow on-site, rapid identification of likely contaminant
"hot spots" for detailed laboratory anaysis and to select depths for monitoring well
screens.
                                  15-104

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CASE STUDY 18:     CONDUCTING A PHASED SITE INVESTIGATION
                                           ;
Points Illustrated

     •   When ground-water contamination is known or suspected at a site, a set
         of initial borings is typically  made  to determine site hydrogeologic
         characteristics and  to identify areas of soil  and  ground-water
         contamination (Phase I).

     •   These findings are then used to select well locations to fully delineate the
         extent of contamination (Phase II).

Introduction

     To identify the extent of ground-water contamination in an efficient manner,
information is  needed on the ground-water flow regime.  Phase I investigations
typically focus on determining site geologic characteristics and ground-water flow
directions and velocities.  Waste sources are also identified. The Phase I results are
then used  in planning the Phase II investigation to determine the extent of
contamination  and to refine estimated rates of contaminant migration.

Facility and  Site Description

     Descriptions of the facility and site geologic characteristics were included in
Case Studies 7,8,14 and 17.

Sampling Program

     The Phase I sampling program included geophysical  surveys,  water level
monitoring, soil sampling, and ground-water quality sampling.  Three seismic
refraction lines were run to estimate the depth to the top of the deep till. The top
of the till was found to occur at a depth of 70 to 120 feet over most of the site.

     Available  historical  data indicated that the general  ground-water flow
direction was to the northwest across the site.  The ground water was thought to
discharge to the river. This information and historical drawings and maps of known
                                  15-105

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disposal areas were  used to locate the Phase I borings (see Figure 15-29 in  Case
Study 17).  One well (MW4) was located on the suspected upgradient side of the
site. The other wells were located near waste sources to determine which sources
appeared to be contributing contaminants to the ground water. For example, two
wells (MW6 and 7) were immediately downgradient of solid waste disposal area #2.
To determine the presence of vertical gradients, three two-well clusters were
drilled-each with one well screened just below the water table and a second well
screened considerably below that at the base of the till.

    The results of the Phase I investigation indicated that all the wells contained
solvents. Thus, investigations of the waste sources and contaminant plumes were
continued  in Phase  II.  The highest solvent  concentrations were  found in wells
located near the liquid waste disposal area where downward vertical gradients
were present.  The contaminants had  migrated down to depths of 75 feet in this
portion of the site.  The Phase I data confirmed the general  northwest ground-
water flow direction but showed a complex flow pattern near the buried  stream
channel. A second concern was whether observed lenses of fine-grained till under
the site were producing localized saturated zones which could be contaminated.

    Based on  the Phase I results, a Phase II monitoring program was designed to
determine the extent of contamination around the major disposal sites. Typically,
two soil borings were made - one up- and one downgradient of the waste  source.
Because of the high  solvent concentrations observed  in the wells downgradient of
the liquid  disposal area, a more intensive field investigation of this area was
included in Phase II.  Instead of two borings per waste source at the liquid disposal
area, 11 soil borings and five new monitoring wells were drilled.  This represented
one-third of the  total effort for the entire 1,000 acre site.  The total number of
Phase II soil borings was 33 (Figure 15-33) and the total number of Phase II wells was
15 (Figure 15-34).   The Phase II  data indicated that most of the solvent
contamination originated from the liquid disposal area and not from solid waste
disposal area #1 which is upgradient of the liquid disposal area. The Phase II data
did identify PCBs from solid waste disposal area #1 but not from any of the other
sources. This was consistent with site records indicating that transformers had  been
disposed at this area.
                                  15-106

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Case Discussion

     Investigation of a large complex site is commonly conducted sequentially.
Basic information is needed on site geologic characteristics and  ground-water
velocities and directions to appropriately locate wells for determining the extent of
contamination.  Thus, the initial installation of a limited  number  of exploratory
borings and wells can provide the data needed to design a complete and effective
investigation. Results from the latter investigation can then be used to determine
the need for remedial action and to evaluate alternative remediation methods.
                                  15-109

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CASE STUDY 19:     MONITORING BASEMENT SEEPAGE

Point Illustrated

    •    Basement monitoring can be used to estimate the extent of contaminant
          migration.

Introduction

    Leachate produced in a landfill can be transported downgradient in ground
water by advection and dispersion.  Shallow ground water may surface and seep
into basements.

Site Description

    A channel, originally constructed as part of a hydroelectric power generation
system, was used as a disposal site for a variety  of chemical wastes from the 1920s
through the 1950s. More than 21,000 tons of waste were dumped in and around
the site before its closure in 1952.  After closure,  homes and a school were
constructed on and around the site. In the 1960s, residents began complaining of
odors and residues. During the 1970s, the local water table rose, and contaminated
ground water seeped into nearby basements.

Geologic and Hydroloqic Setting

    Figure 15-35 shows a cross-section of the site. The site has both a shallow and
a deep aquifer. The shallow aquifer consists of approximately 5 feet of interbedded
layers of silt and fine sands overlying beds of clay and glacial till. The deeper aquifer
is a fractured dolomite bedrock overlying a relatively impermeable shale.  Travel
times from the shallow to the deeper aquifer are relatively long. Contamination has
occurred in the shallow aquifer because of the "bathtub effect". The impermeable
channel filled because of infiltration, and leachate spilled over the channel sides.
The leachate contaminated the shallow ground water and was transported laterally
in this system.
                                  15-110

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Sampling Program

     The houses surrounding the channel were  grouped into three sets
(upgradient, downgradient, and on-site) based on  preliminary data on the
underlying strata and ground-water flow directions. Four houses from each group
were selected  for sampling for a total of 12 houses.  Samples of water and
sediments were collected from the sump  pump wells  in each basement.   Water
samples were collected when the sump pumps were running and 24 hours after
pumping had ceased. Water and sediment samples were analyzed for purgeable
and  extractable organics.  Benzene, carbon tetrachloride, chloroform, and
trichloroethylene (TCE) were found in the water samples.  Water samples taken
while the sump pumps were running had higher concentrations of volatile organics.
Sediment samples contained  PCBs and  dioxin,  possibly due to  cosolvation.
Relatively immobile organics can become dissolved in another more mobile solvent.
The mobile solvent containing traces of other organics can be adverted along with
the water. This process (cosolvation) is one facet of enhanced transport which has
recently been proposed as a possible mechanism for the  observed mobility of
otherwise immobile organics. Samples of water and sediments from storm drains
were also collected and analyzed to determine if discharges from the sumps to the
storm drains were a significant source of organics in the storm runoff.

     In addition to determining water quality, indoor and outdoor air quality was
measured in  the basements at each house. Tenax and polyurethane foam tubes
were placed  in air monitoring systems in each  basement to  measure 12-hour
average concentrations of volatile organics (e.g., carbon tetrachloride, benzene,
and TCE) and semi-volatile organics (e.g., pesticides). Volatile organics were present
in the indoor air samples but semi-volatile organics were not detected. The highest
volatile organic concentrations were observed when the  sump pumps were
operating.

Case Discussion

     At sites where hydrogeologic factors favor shallow lateral ground-water flow,
initial site characterization may involve sampling of basements.  Results from such
an initial site characterization can provide information on contaminant migration
                                 15-112

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which can be used in the design and implementation of detailed soil and ground
water monitoring programs.

     The results of the sampling program described above led to the evacuation
and destruction of a number of homes.  A system of monitoring wells has been
installed to replace the basement sump sampling sites. The shallow aquifer is being
pumped and treated to arrest contaminant migration.
                                 15-113

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CASE STUDY 20:     USE OF PREDICTIVE MODELS TO SELECT LOCATIONS FOR
                   GROUND-WATER MONITORING WELLS

Point Illustrated

    •   Simple mathematical models can be used to estimate the longitudinal
         and  transverse spread of a  contaminant plume.  Wells can then be
         located in areas expected to have elevated contaminant concentrations
         and in areas thought to be both up-anddowngradientofthe plume.

Introduction

    The use of mathematical  models to estimate the migration of contaminants
can be helpful for several reasons, including: 1) fewer wells may be needed  to
delineate a contaminant plume, and 2) wells can be rationally located in an attempt
to determine the maximum concentrations in a plume, its furthest extent, and
locations where concentrations should be at background levels.

Facility Description

    The site was an electronics manufacturing plant that had been in operation for
20 years. Four  large diameter,  rock-filled "dry wells" had been used to dispose of
solvents and process wastes. These disposal  units were between 35 and 60 feet
deep.  Depth  to ground water was over 460 feet.  Disposal Units 1 and  2 had
received paint wastes and solvents, including trichloroethylene (TCE) and
tetrachloroethylene, between 1964 and 1979.  Disposal Units 3 and 4 had been used
to dispose of plating solutions and spent acids between 1971 and  1977.  These
solutions contained copper, chromium, nickel, lead and tin. All the disposal units
were dosed in 1982. Exact quantities of wastes disposed are not known.

Geologic and Hvdroloqic Setting

    The site is located in a large alluvial basin in an arid region. The basin alluvium
is over 1,000 feet thick and consists of an upper sand and gravel unit, a middle silty-
clay unit, and  a lower sand and gravel unit.  Granitic bedrock underlies the
unconsolidated formations. Prior to large withdrawals of ground water, the upper
                                  15-114

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unit had been saturated. At present, the silty-clay unit acts as an aquitard so that
water beneath it is under confined conditions. The potentiometric surface is now
350 feet below the land surface.  In addition to a drop in water level elevations, the
ground-water flow direction has changed over the years from east to north in
response to changing pumping regimes. Estimated horizontal flow velocities have
varied from 10 to 40 feet/year.

Site Investigation

     In  1982, city water officials discovered TCE in water samples from wells within
3 miles  of the site.  On its own initiative, the site owner began  a pre-remedial
investigation, and then later a remedial investigation, to determine whether his site
could be a source of the TCE. The pre-remedial investigation provides an example
of how  simple models can  be  used to determine well locations. The pre-remedial
investigation included sampling  nearby wells and drilling a single deep sampling
well (over 500 feet deep).

     Original plans called for locating the deep monitoring well between the waste
disposal units in an attempt to determine whether solutes had contaminated the
underlying ground water. However, site constraints, including an overhead power
transmission line, underground power lines and major manufacturing  buildings,
necessitated  that the monitoring well site be moved.  The next step  was to
determine an appropriate location for this well.  Because of the changing ground-
water flow direction at this site, it was decided to use a simple mathematical model
to predict the areal extent of contamination from the disposal units.  The results
would then be used in selecting a new location for the deep monitoring well. Data
were collected to determine historical hydraulic gradients, pumping histories, and
aquifer  hydraulic characteristics (e.g., conductivity, porosity).  Following data
collection, a vector analysis model "the method of Mido" (1981) was used to predict
plume evolution.  The results showed that the major plume migration was to the
north (Figure 15-36). Thus, the well was located north of the disposal  units at a
distance of 60 feet from Unit 4.
                                  15-115

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   I
   0
            Final Site of Deep
             Monitoring Well
            DISPOSAL UNIT #4
            DISPOSAL UNIT #3.

            Original Planned
            Deep Monitoring
             Well Location
            DISPOSAL UNIT #2-
            DISPOSALUNITtV
      Scale
100
       Feet
                                                BUILDING 2000
                                                BUILDING 1000
Figure 15-36.  Estimated Areal Extent of Hypothetical Plumes from Four Wells

                                 15-116

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Case Discussion

     Use of a model to predict potential plume migration at this site provided a
means of evaluating the long-term consequences of changing ground-water flow
directions and velocities.  Thus, the pre-remedial investigation deep monitoring
well could be sited in the direction of net plume displacement, rather  than at a
location which might have had a low probability of intercepting contaminated
ground water.  A concentration below  the detection  limits from a well  located
beyond the expected plume boundaries would have been inconclusive (for example,
see Figure 15-37).  However, the deep monitoring well was located  close to the
disposal units and in the direction of plume migration.  Additional wells are now
being planned forthe full-scale remedial investigation.

Reference
Mido, K.W. 1981. An economical approach to determining extent of ground water
contamination and formulating a contaminant removal plan. Ground Water,
Vol. 19, No. 1, pp. 41-47.
                                  15-117

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                                             WASTE SOURCE
         SAMPLING WELL
                   YEARLY INCREMENTS OF WATER AND
                   CONSERVATIVE SOLUTE MOVEMENT
Figure 15-37.   Consideration of Solute Migration Rates in Siting Sampling Wells.

          If a monitoring well is sited farther downgradient than solutes could
          have traveled in the time since disposal, low concentrations in the well
          would certainly not prove that ground-water contamination had not or
          was not occurring.  Prior to locating a well,  average linear velocities
          should  be estimated  (v =  Ki/rie where  v = average linear velocity for
          conservative solutes, K  = hydraulic conductivity, i  =  ground-water
          gradient, and Tie 3 effective porosity).  Using these estimates, and the
          age of the disposal unit,!, an approximate migration distance, D, can be
          computed (D « T/v) for conservative solutes associated with the waste.
          For soil interactive solutes, migration distances will be  less.  Methods for
          estimating these distances are given by Mills et at.  (1985).
                                 15-118

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CASE STUDY 21:     MONITORING AND CHARACTERIZING GROUND-WATER
                   CONTAMINATION WHEN TWO LIQUID PHASES ARE PRESENT

Point Illustrated

     •    Monitoring and characterizing ground-water contamination when two
          or more liquid phases are present requires knowledge of the physical and
          chemical properties of each phase.

Introduction

     Ground-water supplies are susceptible to contamination by immiscible organic
liquids.  Organic liquids such as PCB-contaminated transformer oils, petrochemical
solvents, and motor fuels, because of their nature, often form a second liquid phase.
This separate liquid, in either the vadose or saturated zone, represents a problem in
multiphase flow. It is necessary to understand how these separate phases behave
when designing monitoring and sampling programs for sites contaminated with
such liquids. Techniques commonly used for single-phase flow systems may not be
appropriate.
                         »
Site Description

     The facility is a transformer manufacturing plant which experienced a major
discharge of polychlorinated biphenyls (PCBs) and trichlorinated benzenes (TCBs).
The discharge resulted from a break in a buried pipeline, but surface spillage may
have also occurred during production. The volume and duration of the subsurface
discharge is not known; neither is the quantity released by above ground spillage.

Geological and Hvdroloqic Setting

     The site is comprised of 10 feet of fill over lacustrine clay which  varies in
thickness from 20 to 30 feet. Fractures with openings of approximately  0.1 cm have
been observed in the clay. Below the clay lies a thin silt layer. Below that  is a 40- to
60-foot-thick layer of glacial till composed of fine sand near the top,  and gravel,
sand, and silt below.
                                  15-119

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     Perched water about 3 feet deep flows laterally in the fill.  The permanent
water table, located in the till, is partially confined. Potentiometric levels in this
latter system are between 25 and 30 feet below the land surface.

Sampling Program

     Over 1000 soil samples were taken as part of the site investigation. A mobile
atmospheric pressure chemical ionization mass spectrophotometer (APCI/MS) was
employed for rapid, on-site characterization of soil samples.  This instrument can
detect PCBs down to a minimum concentration of 100 mg/kg.  About 20 percent of
the PCB analyses were replicated by conventional gas chromatography.

     Granular dry  materials  were sampled from an  auger with care taken  in
cleaning sampling equipment to avoid cross-contamination.  In taking samples from
the clay, special effort was made to sample the surfaces of obvious fractures. This
was done to maximize the changes of detection of PCBs in largely uncontaminated
soil.  Due to dilution, large bulk samples can prevent the detection of contaminant
migration through fractures in low permeability soils.

     Vertically, the soil sampling program showed PCBs to be distributed in a non-
homogeneous pattern within the clay zone. Concentrations of PCBs greater than
500 mg/kg PCBs were detected.  The  lateral spreading of PCBs throughout the fill
was much more extensive than the vertical movement. This could be due to the
nature of the discharge/spillage, pressure from the broken pipe, or the fact that the
fill is more permeable than the clay. The PCBs appear to have formed a layer along
the fill/clay interface. Movement of PCBs more than 300 feet laterally from the
original spill site has been confirmed.

     Based on the soil sampling results, 12 well locations (Figure 15-38) were chosen
to further characterize the site.  Four boreholes were drilled  into the till  aquifer.
One  well, 686-B, was placed  upgradient of the spill site with  a screened interval
between depths of 45 and 50 feet. The three downgradient wells in the till aquifer
were screened over different intervals to increase  the possibility of detecting  a
separate organic liquid layer.  The screened intervals used were at depths  45 to  50
feet  (well 686-A), 50 to 55 feet (well 686-C), and  55 to 60 feet  (well 686-D).  Eight
                                  15-120

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   03
               06
                        • • 6S6.D
                       686-A  Oj
                                               PARKING LOT
 pipeline
31
                    MANUFACTURING
                                            • 686-B
                                                       direction of
                                                       ground water
                                                       flow
                                                                            t
                                                                           N
• deep well locations
o shallow well locations
             Figure 15-38. Well Locations and Plant Configuration
                                     15-121

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shallow wells were also placed in the fill to monitor the perched water.  The fill is
approximately 10 feet deep and a  layer of PCBs was suspected at the fill/clay
interface. The depth of the perched water fluctuates between 7 and 8 feet.  Six of
the eight wells in the fill, 1, 3,4, 6, 7, and 8, are screened from 7 to 10 feet. Samples
from wells 1, 6, 4, and 7 showed PCB levels much higher than the solubility  limits.
The sampling results suggest that two separate liquid layers exist at these locations
and that the liquids are being mixed during sampling. Wells 2 and 5 were screened
from 5 to 8 feet to determine if a floating liquid layer was present. Again, samples
having concentrations far in excess of solubility limits indicated the existence of a
layer of organic liquid.

Case Discussion

     Ground-water systems contaminated with immiscible liquids require special
attention.  Well screen  intervals  should be  placed  to intercept flow  along
boundaries between soil layers of differing hydraulic conductivities and at water
table surfaces.  Sampling results must also be  interpreted properly.   Samples
showing contaminant concentrations far in excess of solubility limits may indicate
that two layers of different liquids are being pumped and mixed.

     Finally, Figure 15-39 is offered as an illustration of the types of complexity
which can be encountered with immiscible liquids having densities both greater
than and less than water.
                                   15-122

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                                ' 'i GflOUNO WATER FLOW
Figure 15-39.   Behavior of Immiscible Liquids of Different Densities in a Complex
              Ground-Water Flow Regime
                                  15-123

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CASE STUDY 22:     METHODOLOGY FOR  CONSTRUCTION OF VERTICAL FLOW
                  . NETS

Point Illustrated

     •    Construction of a vertical ground-water flow net can be a valuable tool
          for evaluating ground-water (and contaminant)  pathways  and for
          determining additional actions that may be necessary  to accurately
          delineate the ground-water flow regime at a facility.

Introduction

     Constructing a vertical flow net at a facility provides a systematic process for
analyzing the accuracy of ground-water elevation and flow data, and can therefore
foster a better understanding of the ground-water flow regime at the site.

Facility Description and History

     The site contains a large chemical manufacturing facility of approximatley 300
acres located beside a major river in the northeastern United States.  The site has
been used for chemical manufacturing by different companies since 1904 and has a
long history of on-site waste management.  Several solid waste management units
have been  identified at the facility. This is the same facility as discussed in Case
Studies 7, 8,14,17 and 18.

     Geologic and Hydrologic Setting:  At depths of 150 to  200 feet the site is
underlain by bedrock identified as arkosic sandstone. Above this bedrock are glacial
deposits consisting of a thick bed of hard till, overlain by lacustrine sediments and
deltaic and outwash deposits. Discontinuous lenses of till were identified within the
deltaic deposits. A trough cut into the thick-bedded till and trending approximately
southeast to northwest has been identified. See Figure 15-40.

     The river beside the facility flows westward and discharges into the main stem
of a larger river approximately 4 miles west of the facility. A small tributary (brook)
borders the facility to the southwest and west.  Swamp-like areas are present near
                                  15-124

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15-125

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the tributary.  It is suspected  that the  arkosic sandstone outcrops  in the  river
adjacent to the  facility.  Whether this visible rock is a large glacial erratic or an
outcrop of the arkosic sandstone bedrock is an issue identified during previous
investigations  and may be important in characterizing the ground-water  flow
regime at the facility.

Program Design

     The site was investigated in two phases.  Phase I (1981-1984) included the
installation and  monitoring of wells MW-1 through MW-12, while Phase II (1984-
1985) consisted of 34 soil borings, installation of wells MW-13 through MW-57, and
monitoring and sampling of all wells. This two-phased approach allowed the use of
the initial monitoring well data and soil boring data to determine the placement of
the Phase II monitoring wells.  Further discussion of this two-phased approach is
provided in Case Studies 7 and 18.

Data Analysis

     Evaluation  of the data was conducted based on information provided by the
owner or operator, including the water-level elevation data presented in Table
15-13. Well locations and water-level elevations in the wells were mapped  and
compared to elevations of the midpoint of the well screens  to  show relative
hydraulic head differences from well to well.  Vertical gradients are a  reflection of
different head values at different elevations.  For each well,  the head can be
determined at the elevation of the midpoint of the well screen  by measuring the
water-level elevation in the well. Different head values corresponding to different
screen elevations were used to evaluate  vertical gradients. During the plotting of
this map, anomalous data were identified and marked for further investigation.

     The geology of the site and the  depositional processes forming the aquifer
were  studied to determine what sorts of hydrogeologic phenomena might be
expected.  Glacial outwash deposits exhibit trends in  sediment size  and sorting.
Sediment size  decreases and  sorting  increases from the marginal to the  distal
portions of the deltaic/lacustrine deposits. 1 It is expected that this tendency  will be
'Mary P Anderson, "Geologic Faces Models: What Can They Tell Us About Heterogeneity," presented to the American
Geophysical Union. Baltimore. May 18.1987
                                   15-126

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                           TABLE 15-13

        GROUND-WATER ELEVATION SUMMARY TABLE PHASE II
, Well
Number
MW-1
MW-2
, MW-3
MW-4
MW-5
MW-6
MW-7
MW-8
|MW-9
MW-10
MW-11
MW-12
MW-1 3
MW-1 4
MW-1 5
MW-1 6
MW-1 7
MW-1 8
MW-1 9
MW-20
MW-21
MW-22
MW-23
MW-24
MW-25
MW-26
MW-27*
MW-28
MW-29
MW-30
MW-31
MW-32
MW-33
Ground
Elevation
(ft)
162.80
162.50
174.20
201.90
186.30
144.30
144.60
155.10
160.50
160.40
154.70
159.50
162.20
162.10
162.00
162.00
162.00
161.90
137.10
137.20
141.40
141.60
204.30
143.90
143.80
143.80

142.70
142.80
172.00
172.20
203.10
174.20
Well
Depth
(ft)'
76.50
22.50
31.00
5400
47.50
39.50
19.50
24.00
61.00
30.00
27.00
26.50
29.00
29.00
29.00
29.00
71.00
72.00
24.00
17.00
26.50
15.10
225.50
70.00
39.00
24.00

46.00
23.00
85.50
24.85
61.00
94.00
Midpoint of
Well Screen
Elevation1


145.7
150.4
141.3
107.3
127.6
133.6
135.0
132.9
130.2
135.5
139.2
139.1
139.1
135.5
104.5
103.4
116.6
123.7
118.4
13.0
-10.2
76.4
107.3
123.2

100.2
123.3
90.0
150.8
145.6
83.7
Screen
Length
(ft)
3
3
3
3
3
3
3
3
3
3
3
3
10
10
10
3
25
25
5
5
5
5
20
5
5
5

5
5
5
5
5
5 .
Water
Level Elevation
9/1/82


150.54
156.85
149.95
135.78
135.94
149.04
141.53
144.62
140.57
141.05
141.22
140.66
140.67
140.87
140.52
140.53
127.83
127.82
135.39
135.35
184.98
136.47
130.20
130.17

12786
127.88
152.70
151.68
154.78
150.49
•Not installed.
1 Assumes screens are installed one foot above the bottom of the well.
                             15-127

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                        TABLE 15-13 (continued)
Well
Number
MW-34
MW-35
MW-36
MW-37
MW-38
MW-39
MW-40
MW-41
MW-42
MW-43
MW-44
MW-45
MW-46
MW-47
MW-48
MW-49
MW-50
MW-51
MW-52
MW-53
MW-54
MW-55
MW-56
MW-S7
Screen
Reference
Points
SRP-1
SRP-2
SRP-3
SRP-4
SRP-5
SRP-6
SRP-7
SRP-8
Ground
Elevation
(ft)
186.20
203.20
189.40
189.50
189.30
154.90
173.80
173.70
134.20
139.50
139.50
144.32
144.15
141.50
141.60
143.00
143.00
157.00
157.00
159.30
145.80
145.90
133.60
141.90











Well
Depth
(ft)
75.80
106.25
101.20
48.00
135.30
68.00
47.50
75.30
64.00
32.10
28.00
35.00
25.00
34.00
17.00
72.20
30.20
70.30
34.00
77.90
52.00
35.00
20.30












Midpoint of
Well Screen
Elevation1
113.9
100.4
91.7
145.0
57.5
90.5
129.8
101.9
73.7
80.9
115.0
112.8
122.6
111.0
128.1
74.3
116.3
90.2
126.5
84.9
97.3
114.4
116.8












Screen
Length
(ft)
5
S
5
S
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5




114.41
114.92
116.05
1 1 5.86
NA
128.81
137.28
134.11
Water
Level Elevation
9/1/82
U9.72
144.31
143.22
150.51
145.04
142.45
146.59
141.95
117.62
117.24
119.62
128.97
126.48
131.91
131.74
123.22
123.85
149.58
139.48
141.09
120.18
121.63
119.84












*Not installed.
1 Assume screens are installed one foot above the bottom of the well.
                                 15-128

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reflected in hydraulic conductivities throughout the outwash deposits at the facility.
There is some suggestion of such a trend in the head data from the site.

     The map of hydraulic head  values and screen midpoint elevations were
evaluated  considering both the possible hydrogeologic phenomena expected for
the geology of the area and the depositional processes creating the aquifer. Several
working hypotheses were developed to explain  the  apparent ground-water flow
patterns and the identified vertical gradients.

     •    Hypothesis  1: Vertical gradients  can be explained by classifying areas
          where the  vertical gradients were reflective of discharge and recharge
          areas. (See  Figure 15-41.)

     •    Hypothesis  2: The top surface of the till forms a trough with a saddle.
          (See Figure 15-40.)  The vertical  gradients showing  higher head with
          depth reflect the movement of water as it flows upward over the saddle.

     •    Hypothesis  3: The  vertical  gradient may correlate  with  locations of
          buildings and parking lots at the  site.  Recharge occurs primarily where
         the ground is not paved. The downward gradient near the river may be
          caused by runoff flowing downhill and recharging the ground water at
         the edge of the pavement.

     •    Hypothesis 4: Most of the ground-water flow is horizontal. The vertical
          gradients reflect phenomena whose scale is smaller than the resolution
          of available data,  and  an  accurate interpretation  cannot be made.
          Geologic systems exhibit heterogeneity on different scales, causing
         fluctuations in head on  different scales.  The small-scale  fluctuations
         detected at the site are due to undefined causes and may represent:

          1.    details of stratigraphy (such as till beds  in  parts of the outwash
              deposit),
         2.    artificial recharge and discharge (such as leaky sewer pipes), or
         3.    errors  in the data.
                                  15-129

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15-130

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     To characterize  flow  at the site and to support the design of corrective
measures (if needed), a working (conceptual) model of flow at the site should be
developed. This model, in this case a vertical flow net, can be used to identify data
gaps  and to prioritize gathering, of the  necessary additional  information.
Considering the hypotheses developed, an area for characterizing the vertical flow
regime was selected.  Determination of this area, where a geologic cross-section
and flow net will be constructed, was based on:

     •    Assumptions and requirements necessary to construct flow  nets,  as
          identified in the Criteria for Identifying Areas of  Vulnerable
          Hydroqeoloqy.  Appendix  B:   Ground-Water  Flow  Net/Flow  Line
          Construction and Analysis (Vulnerable Hydrogeology, Appendix B). For
          example, ground-water flow should be roughly parallel to the direction
          of the cross-section and vertical flow net.

     •    Flow being representative of the hydrogeology of the facility.

     •    Flow  representing the major paths of ground-water movement. For
          example, the aquifer is shaped like a trough and  a major portion of the
          ground-water flow occurs in the middle of this trough; therefore, a cross-
          section and flow net should be constructed along the axis of the trough.

     A geologic cross-section was constructed for the area of interest and is
identified  as T-T in Figure  15-40.  A flow net was then constructed following the
methodology described in Vulnerable Hvdroqeoloqy. Appendix B; see Figure 15-42.
Construction of a vertical flow  net requires a graphical solution  of  Darcy's  Law.
Data that  do not fit the solution become evident in Figure  15-42 as shown, for
example, by the head value for MW 52.

     Construction of a vertical flow net allowed for a systematic evaluation of the
various hypotheses. Hypothesis 1, where vertical gradients are labeled recharge and
discharge, is rejected  because the gradients vary significantly in  a very irregular
pattern (compare well clusters MW 14-18 and MW 12 and 53); there is no apparent
reason that natural recharge would  vary so  irregularly.  Hypothesis 2  seemed
reasonable initially but, after  closer inspection,  is  rejected because  upward
                                  15-131

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                            rsi







                             91
15-132

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gradients are not consistently found near the saddle. Hypothesis 3 is feasible and
deserves further study. Aerial photographs were examined to identify paved and
unpaved areas, but the available ground-water data are insufficient for detailed
correlation to these distinct areas. Additional data are needed to construct a more-
detailed flow net to further evaluate this hypothesis. Hypothesis 4, which asserts
that most of the flow is horizontal, addresses the area of the site where the major
portion of ground-water flow occurs. Although it  relies on undefined causes to
explain fluctuations, it reflects the most logical explanation of the data.

Results

     During construction of the flow net and testing of the hypotheses several
issues were identified. One of the most important gaps in the study to date is how
localized flow at the site fits into the regional ground-water flow regime. Regional
flow issues would need to be resolved prior to determining the extent and type of
corrective  measures, if necessary.  The following regional flow issues  were
identified:

     •    Geologic information beyond the facility property boundary is necessary
         to explain the suspected bedrock in the middle of the river directly beside
         the site  to characterize the  regional  ground-water flow (i.e., to
         determine the possibility for contamination of regional ground water).
         The difference in elevation of the top of the bedrock in the river and the
         top of the bedrock throughout the facility is approximately 120 feet.
         How can this be explained? Is the bedrock surface irregular or is this rock
         a glacially-transported  boulder exposed  in the river? How does this
         affect regional ground-water flow?

     •    Data consistently show a downward gradient (i.e., recharge conditions)
         near the river.  This is difficult to explain because rivers in this region are
         not expected to  be losing streams (Heath, 1984).   The expected flow
         direction near a  ground-water discharge area, in  this case a gaining
         stream, is upward.  Data points showing downward flow near the river
         are not included in flow net T-T. (Further investigation  of vertical
         gradients near the river is recommended). If this downward  gradient
         near the river is confirmed, near-water-table contamination could  move
                                  15-133

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         downward and contaminate deeper ground water.  If deeper, regional
         contamination must be addressed, corrective measures may  be
         significantly more difficult and extensive.

Other issues deal with localized flow patterns that may affect design of corrective
measures.  Resolution of these issues will probably not change the overall scope of
corrective measures, but would need to be considered in the detailed design.

These localized flow pattern  issues are as follows:

     •   The hydraulic head in the brook is higher than the head in the closest
         wells in the aquifer, but the water slopes toward the stream.  This is
         inconsistent.  If ground water from the site is not discharging into this
         stream, fewer interceptor wells may be needed.

     •   Anisotropy must be taken into account in determining the region of flow
         captured by interceptor wells, drains, etc.

     •   Till identified as lenses in outwash deposits may actually be continuous
         with  upgradient  till, causing the aquifer to flow under confined
         conditions. Are the till beds isolated lenses or are they continuous? If the
         till beds in the outwash aquifer are continuous  and isolate adjacent
         zones within the aquifer, they will have the potential of blocking flow to
         interceptor wells that may be included in the corrective measures plan.

     •   Vertical gradients of 0.25 and  0.002 in  the same geologic unit are
         presented. Are these gradients accurate and how can they be explained?
         There could be artificial discharge (pumping) or recharge (possibly from a
         leaking sewer) near the wells showing a high vertical gradient. The areas
         labeled discharge  areas show no signs of surface water or other surficial
         evidence of discharge. Artificial recharge and discharge may create areas
         of relatively constant head, such  as where ground water contacts leaky
         sewers; these areas could limit the growth of cones of influence of any
         interceptor wells or drains.  Also, any contaminated water that may be
         discharging from pipes should be identified and corrected.
                                  15-134

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Case Discussion

     Further investigation is necessary to resolve the above issues.  Regional flow
issues should be resolved  first.  This  information would  be used to  better
understand localized flow patterns which would affect the design of corrective
measures. The following options for further investigation are suggested:

     1.    Study the regional geology and hydrogeology. Techniques that could be
          employed using existing data include review of geologic maps, analysis
          of well logs, and interpretation of existing surface geophysical data (e.g.,
          gravity and magnetic surveys). Measurement of water level elevations in
          wells outside the site would also be useful.

     2.    Conduct a detailed study of the depositional environment of the glacial
          deposits on the site. This should provide a better  understanding of flow
          patterns.

     3.    Collect a full-year series of head data at existing wells to differentiate
          transient from steady-state (e.g., artificial from natural) effects in the
          measured heads.

     4.    Conduct multiple-well  pumping tests  to determine the degree of
          connectivity of geologic formations using wells at different depths and
          locations. [Note:  this should be done with careful attention to details of
          well construction  so that it is understood exactly what  is being
          measured.]

     5.    Collect detailed chemical data (including major ions and  contaminants)
          at the  existing wells and interpret them to aid  in characterizing the flow
          regime.

     6.    Drill one or more  wells into the bedrock  near the  river to  determine the
          vertical component of ground-water flow at this location.

     Options 1 through 5 above are recommended prior to drilling additional wells
in the outwash deposits, unless more wells are needed to  delineate the release.
                                  15-135

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Further single-well hydraulic conductivity tests in the glacial deposits are not
recommended at this time. The large-scale flow in the outwash aquifer should be
determined by the location and relative degree of continuity of the till versus the
sand because the permeability contrasts between the till and sand  is so much
greater than the variability among the different sands. (See paper by Graham Fogg
.in Water Resources  Research, 22, 679.)  Single-well tests would be useful for
determing  localized hydraulic conductivities of the sand  bodies, not their
connectivity.

     Gathering existing data and constructing an  initial vertical flow  net proved
useful in  identifying data gaps in defining  ground-water flow, and identified
problems due to differing interpretations of the existing data. Determining options
for gathering additional data necessary to resolve these  issues was based on a
qualitative understanding  of the ground-water flow  regime gleaned from
construction of the vertical flow net.

References
Fogg, Graham. Water Resources Research. 22, 679.
Heath.  1984. Ground Water Regions of the U.S.  USGS Water Supply Paper No.
2242.
U.S.  EPA.   1986.  Criteria for  Identifying  Areas of  Vulnerable Hydroqeoloqy,
 Vppendix B: Ground-Water Flow Net/FIc
of Solid Waste. Washington, D.C. 20460.
Appendix B: Ground-Water Flow Net/Flow Line Construction and Analysis. Office
                                  15-136

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CASE STUDY 23:   PERFORMING A SUBSURFACE GAS INVESTIGATION

Points Illustrated

     •    Design of a phased monitoring program to adequately characterize the
          extent and nature of a subsurface gas release.

     •    The use of ambient  air and basement  monitoring  to  supplement
          monitoring well data.

     •    The importance of subsurface  characterization prior to design of a
          monitoring network.

Introduction

     Gases produced in  a landfill will migrate via the path of least  resistance.
Subsurface, lateral migration of landfill gas can occur due to natural and man-made
barriers to vertical gas migration, such as impermeable overlying soil layers, frozen
soil, or surf ace water. Installation of a gas-monitoring well network, in con,jnction
with sampling in buildings in the area, can be used to determine the need for
corrective measures.

Facility Description

     The unit in question is a  landfill covering approximately  140 acres and
bordered by a river on one side and a flood wall on the other. Beyond the floodwall
lies a residential area (Figure 15-43).  Several factors contribute to the subsurface
gas migration problem at this landfill. The  site reportedly received large quantities
of organic wastes which, when decomposed in the absence of air, produce methane
and carbon dioxide gases. The presence of "tight", low permeability soils at the
ground surface (12 feet  of clayey silt at the surface grading to coarse sand  and
gravel at a depth of 55 feet) in the residential area, combined with a  rapidly rising
water table below the landfill due to increased infiltration, restrict the vertical area
available for gas migration and encourage lateral movement.
                                  15-137

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                                   L
                                           c
                                           _2
                                           Q.
                                           LO
                                            3
                                            CT>
15-138

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     Investigation pf the gas migration began when foul odors and explosive levels
of methane (5 to 15 percent by volume in air) were discovered in the basement of a
home approximately 200 feet from the landfill.  Residents in the area were
evacuated, a sampling network was installed, and monitoring was conducted.

Sampling Program

     The sampling was conducted in four phases, an initial screening phase and a
more detailed three-phase sampling  program.  The monitoring network  for the
initial screening  phase consisted  of four  wells (W1 through W4) aligned
perpendicular to the long axis of the landfill, in the  direction of (and extending
beyond) the house where the gas was initially detected (Figure 15-43). The  wells
were drilled to an approximate depth of 30 feet below the land surface with the
farthest well located about 1000 feet from the landfill boundary. These wells were
sampled twice a day for a  month.  Samples were analyzed for methane and
combustible hydrocarbons. The results of this initial monitoring showed average
methane levels to be highest at the monitoring  well closest to  the  landfill (30
percent by volume), and roughly grading to below the detection  limit at the well
farthest from the landfill.

     Grab and composite ambient air samples were also taken at the  landfill and
around houses in  the neighborhood where gas was detected during the initial
monitoring phase.   These samples  were analyzed for  methane  and other
combustible hydrocarbons.  No gases were detected above normal background
levels in any of these above ground samples.

     The next phase of monitoring (Phase I of the detailed sampling) involved the
installation  of 14 new gas monitoring wells (1-1 through 1-14 in Figure 15-43).  Most
of these were placed in a line 250 feet from and  parallel to the longitudinal axis of
the landfill. Seven of these wells were drilled to an average depth of 55  feet, at
least 5 feet below the water table so that ground-water levels could be monitored.
The other seven wells averaged 30 feet and did not intercept ground water.  As
shown in Figure 15-44, each well consists of three separate gas monitoring probes at
evenly spaced depth intervals.   Each probe was packed in gravel to allow gas to
collect in its vicinity. Clay plugs were installed  between each probe interval and
                                  15-139

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CAST IRON COVER SET IN CONCRETE

  GROUND SURFACE
 VALVE
 PROBE A

 1/4" DIAMETER
 POLYETHYLENE
 TUBING
 PROBE B
    LEGEND

    NATIVE SOIL
    BACKFILL

    BENTONITE PLUG

    PEA GRAVEL
VALVE
PROBE A
                                         PROBE B
                                       2" OIAMETER
                                       PVC PIPE
                                         PROBE C
                                    2" DIAMETER
                                    WELL SCREEN
 PROBE C
 Figure 15-44.  Gas Monitoring Well
             15-140

-------
between the top probe and the surface to minimize vertical movement of gas in the
well. After two months of monitoring the well headspace twice monthly, concern
over the high levels of methane that were being measured prompted an expansion
of the monitoring well system.

     The Phase II monitoring network involved another 14 wells (11-1 through 11-14)
installed to a depth of 6 feet along three radial lines from the landfill. These wells
were monitored twice monthly with the Phase I wells.  Methane was not detected at
these wells because they were not deep enough to penetrate the clayey silt layer
which in this area extended to  a depth of  12 feet. Had adequate boring logs been
compiled prior to the placement of these wells, the  time and  money involved  in
their installation and sampling could have been saved.

     Detailed soil boring logs were compiled during the installation of the Phase III
wells (111-1 through III-8 in Figure 15-43). These wells were drilled to ground water,
averaging  55 feet in depth, were located  in the vicinity of the Phase II wells, and
were constructed in the same  manner as the Phase I wells, with three gas  probes
placed in each well. The Phase  III wells were located from 510 to 900  feet from the
lane.'ill.  These wells were monitored twice a month  for two months concurrently
with the Phase I wells.  Methane levels at all but two Phase III wells (which are
located along the same radial line) exhibited explosive concentrations, ranging up
to 67 percent by volume in air.  These high concentrations of gas prompted another
round of sampling  of homes  in the vicinity of wells  exhibiting high methane
concentrations.

     Methane and combustible hydrocarbons were measured in basements, crawl
spaces, and living areas of 28 homes adjacent to the landfill.  All proved to be well
below the lower explosive limit of methane.

    Wells were then selected based  upon proximity to houses exhibiting the
highest levels of combustible gases, and sampled to determine gas composition and
concentration.  The proportion of constituents in the collected gas was similar in all
samples analyzed, and concentrations decreased with increasing distance from the
landfill.
                                  15-141

-------
     Ambient air sampling for organic gases at the landfill and in the residential
area was also performed at this time and showed low levels  of several organic
compounds. Air samples collected in houses near the landfill showed the presence
of two of the gas components measured in the test wells (methane and ethane).

     The gas migration hazard had been sufficiently characterized so that a plan for
corrective measures could be developed.  This involved the installation of 31 gas
extraction wells which were  located along a line  between the landfill and the
residential areas, and a blower system to "pump" the gas out of these extraction
wells.

Results

     The monitoring program implemented for this case was,  for the most part,
effective in characterizing the extent and concentrations of subsurface gas
contamination.  The four initial monitoring wells verified that the landfill was the
source of contamination.  Phase I monitoring confirmed that  the  high levels of
methane were present at all depths monitored and along the entire length of the
landfill.  The horizontal  location of the Phase II wells, in lines radiating from the
landfill, was appropriate, although the lack of subsurface characterization rendered
them useless.  Phase III  sampling established the vertical and  lateral extent of
subsurface contamination into the residential area.

     Throughout the study, ambient air sampling as well as monitoring of homes in
the area of concern provided adequate safety control, as well as  an additional
indication of potential migration of landfill-generated gases.

Case Discussion

     Subsurface gas migration can occur when atmospheric ventilation of  gases
generated in a landfill is insufficient. The gas produced migrates along the paths of
least resistance.  Conditions restricting release to the atmosphere, such as saturated
or tight surficial soils, may force  the gas to move laterally  over considerable
distances.
                                  15-142

-------
     This case was selected as an illustration of a phased approach to monitoring a
subsurface gas release. The results of one phase of monitoring were incorporated
into the design of the next phase throughout the study. Monitoring was performed
at discrete vertical levels below the surface and  at distances from the landfill that
were adequate to confirm the extent of the contaminant plume.

     The study  also illustrates the importance of characterizing subsurface
conditions prior to installing monitoring wells.  Fourteen unusable wells were
installed and then monitored for  two months because of insufficient preliminary
soil  (stratigraphic) characterization.

     The use of ambient and basement  monitoring for gas to supplement
monitoring well data is also noted in this case study. The location of new wells can
be based in part on readings from these sources.
                                  15-143

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CASE STUDY 24:     USE OF A SUBSURFACE GAS MODEL IN ESTIMATING GAS
                 .  MIGRATION AND DEVELOPING MONITORING PROGRAMS

Point Illustrated

    •   Predictive models can be used to estimate the extent of gas  migration
         from a suspected subsurface source. This information can be used to
         estimate human exposure  and to determine appropriate locations for
         monitoring wells and gas collection systems.

Introduction

    Methane is a common landfill gas and is often used as an indicator of landfill
gas migration. The subsurface methane predictive model, described in Volume II,
Appendix D of this document, will yield a methane concentration contour map and
predict the distance that methane  will migrate. The model consists of a series of
charts developed by imposing a  set of simplifying assumptions on a general
methane migration computer model.

    A methane migration distance prediction chart is used to find a preliminary
migration distance based on the age  of the site and the soil type. The remaining
charts are used to find correction  factors  which  are in turn  used to adjust the
migration distance. These factors are  based upon site characteristics (e.g., depth of
the waste).

Facility Description

    The unit is located on a 583-acre  site in a suburb of a major metropolitan area.
Figure 15-45 shows the site layout. The landfill  itself occupies 290 acres. 140 acres of
the landfill were  used  for the disposal of hazardous wastes.  Both hazardous and
nonhazardous wastes were disposed at the site from 1968 to 1984. Hazardous waste
disposal ended in 1984. The disposal of sewage treatment sludges and municipal
refuse continues.  As seen in Figure 15-45, residential development has taken place
with houses now bordering the facility to the south.  A population of 30,000 to
40,000 people reside within a mile radius of the landfill center.
                                  15-144

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                   Scale Houi«
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                   Figure 15-45.  Facility Map
                             15-145

-------
     The unit is a V-shaped fill overlying sediment and bedrock. The rock type is a
poorly consolidated, fractured sandy silt offering no lithologic barrier to gas
migration. The shape of the water table has not been established. Also unknown
are the possible effects of local, permeable formations such as sand lenses, faults,
etc.

     The warm climate at the site encourages rapid degradation of organic wastes
and therefore rapid gas production.  Site characteristics suggest  that vertical gas
migration is not hindered. However, the compaction of the fill cover by truck traffic
combined with the rapid production of gas has forced lateral migration through the
fractured sandy silt.

Applying the Subsurface Methane Predictive Model

     The subsurface methane predictive model allows the development  of a
subsurface methane concentration contour map. The model predicts the distance
methane will  migrate from a unit  based on its age, depth, soil  type,  and
environmental factors. A contour map for two different methane concentrations, 5
and 1.25 percent, is predicted. The likelihood of human exposure can be estimated
from the location of the contours with  respect to on-site and off-site structures.

     Application of the model involves three steps. The first step is the prediction
of gas migration distances, based  on the age of the landfill and the local soil type.
The unit  of interest is 18 years old and has sandy soils.  Figure  15-46 shows the
unconnected methane migration distances for various soils over  time.  From
Figure 15-46, the unconnected migration distances for the subject site are 165 feet
and 255 feet for 5 and 1.25 percent methane concentrations, respectively.

     The second step in applying the model involves the application of a correction
factor to the migration distances based on waste depth. The deeper the waste, the
greater the opportunity for subsurface migration.  Figure 15-47 is used to find the
correction factors for depth. For the subject waste unit the depth is 25 feet, which
corresponds to a correction factor  of 1.0 for both concentrations.
                                  15-146

-------










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15-147

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                   15-148

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     The final step in applying the model is the correction of migration distances
based on surface venting conditions.  The following equation is used to calculate
the adjusted correction factor, ACF:

     ACF a [(ICF-1)(fraction of site which is impermeable)] + 1

The impervious correction factor, ICF,  is obtained from Figure 15-48. In the above
equation, ICF is adjusted to account for the fraction of time the solid is saturated or
frozen and the fraction of the land area that is impermeable due to natural or man-
made barriers. If corrections for both  time and area are required, the fractions are
additive. From Figure 15-48, the ICF for a unit 18 years old and 25 feet deep is 2.4.
Site charcteristics together with  weather conditions indicate a value of  0.4 for the
fraction of impermeable area.  Substituting these values into the above equation
yields an adjusted correction factor of:
     ACF = [(2.4-1X0.4)] + 1 = 1.56.
Results
     Table 15-14 summarizes the results from steps one through three of the model
application.  The  predicted  migration distances for methane  are  found  by
multiplying the unconnected distance from step one by the correction factors from
steps two and three. The predicted distances of travel for methane are 255 feet and
395 feet for 5 and 1.25 percent concentrations, respectively.

                                TABLE 15-14
                              MODEL RESULTS
 Methane
 Concentration
 (percent)
     5
     1.25
Uncorrected
Distance
   (ft)
    165
    255
Correction
for Depth
    1.0
    1.0
Correction
for Venting
    1.56
    1.56
Corrected
Distance
   (ft)
    255
    395
                                  15-149

-------










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         15-150

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Case Discussion

     Figure 15-49 is a  methane concentration contour map developed from the
predicted  travel distances.  The map indicates that the  possibility  of  human
exposure to landfill gas is high.  Landfill gas is known to be present and well drilling
operations at the landfill have caused minor explosions. The monitoring wells along
the facility perimeter and testing in nearby homes indicate  that gas has migrated
off site. Both the 5 percent and 1.25 percent methane  contours enclose homes
evacuated because of gas accumulation. Measures have been taken to mitigate the
immediate  problems and the landfill operators have installed additional gas
collection wells and extended the monitoring system.
                                  15-151

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                                       15-152

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CASE STUDY 25:     USE OF  METEOROLOGICAL/EMISSION  MONITORING DATA
                  . AND DISPERSION MODELING TO DETERMINE CONTAMINANT
                   CONCENTRATIONS  DOWNWIND OF  A LAND  DISPOSAL
                   FACILITY

Point Illustrated

    •   How to use meteorological/emission monitoring  data and dispersion
         modeling to estimate contaminant concentrations.

Introduction

    Concern over possible vinyl chloride transport into residential areas adjacent
to a land disposal facility prompted  initiation of this study.  As a followup to a
screening assessment (involving emission  modeling) a survey and emission
monitoring  program with the application of an air dispersion model  were used to
assess potential health hazards.

Facility Description

    The facility is a landfill which has been in operation since 1963. The facility
occupies an area of 583 acres, of which 228 acres contain hazardous and municipal
waste.  The facility and surrounding terrain is hilly with elevations ranging from 600
to 1150 feet above mean sea level.   Residential areas are located  immediately
                *
adjacent to the south and southeast facility boundaries, as shown in Figure 15-50.

    The facility previously received waste solutions from the synthesis of polyvinyl
chloride which included the vinyl chloride monomer.  Gas is generated by municipal
waste decomposition and chemical waste volatilization.  The primary air release
from the particular unit  is  vinyl chloride.  A gas collection system  has not been
installed for this unit.
                                  15-153

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15-154

-------
Program Design/Data Collection

     A  screening assessment (based on  emission/dispersion  modeling) was
conducted to evaluate vinyl chloride emissions from the landfill.  Evaluation of
these results indicated  that emission monitoring should  be conducted to more
accurately quantify the release.  An isolation flux chamber was used to measure
vinyl chloride emissions during a three-day period in August. This sampling period
was selected based on the  screening assessment results to represent worst case
emission and dispersion conditions.

     An on-site meteorological survey program was also conducted to characterize
wind flows at this complex terrain site. Two meteorological stations were deployed
to evaluate wind flows, as influenced by complex terrain, which may impact the two
adjacent residential areas (see Figure 15-50.) A one-month data collection period
during August was conducted to characterize  on-site wind and stability patterns
during worst-case, long-term emission/dispersion conditions. Although the facilty is
located in complex terrain,  the  diurnal wind pattern  during  the meteorological
survey was  very  consistent from  day  to day.   Therefore,  the one-month
meteorological monitoring period was adequate for this RFI application.

Program Results/Data Analysis

     The emission monitoring and meteorological monitoring data were used as
input for dispersion modeling. The wind patterns were different for each of the on-
site meteorological stations (see Table 15-15). Therefore, two sets of modeling runs
were conducted (meteorological  station  A data  were  used to estimate
concentrations at residential  area A and meteorological station  B data were used to
estimate concentrations at residential area B).

     The dispersion  modeling results indicated that estimated concentrations at
both residential areas were  significantly below the RFI health  criteria. Therefore,
followup air release characterizations were not necessary and  information was
sufficient for RFI decision making.
                                  15-155

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                  TABLE 15-15
SUMMARY OF ON-SITE METEOROLOGICAL SURVEY RESULTS
I
i
j Prevailing daytime
; wind direction
I Prevailing nighttime
i wind direction
Station A
S
NNE
Station B
SW
ENE
                     15-156

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Case Discussion

     Emission sampling was appropriate for this application because of the
uncertainties associated with  emission rate modeling for landfills (including
uncertainties in emission modeling inputs such as the waste composition and spatial
distribution).  The isolation flux chamber technique  provided a basis for direct
measurement of vinyl chloride emission rates for dispersion modeling input.

    The conduct of an on-site meteorological monitoring survey provided the
required wind and stability input for dispersion modeling.  The use of multiple
meteorological towers for this application was necessary to characterize wind flow
patterns in complex terrain and to account for off-site exposure at two residential
areas subject to different wind conditions.   The combination  of emission
monitoring, meteorological monitoring  and dispersion modeling  provided an
effective air release characterization strategy for this RFI application.

References

B 'ker, L.W. and  K.P. MacKay.  1985.  Screening Models for Estimating Toxic Air
Pollution Near a Hazardous Waste  Landfill.  Journal of Air Pollution Control
Assocation, 35:11.
                                  15-157

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CASESTUDY26:     USE OF METEOROLOGICAL DATA  TO DESIGN  AN  AIR
                   MONITORING NETWORK

Points Illustrated

     •   How to design an air monitoring program

     •   How to conduct an upwind/downwind  monitoring  program when
         multiple sources are involved.

Introduction

     A screening  assessment  (based  on emission/dispersion  modeling)
commensurate with  RFI guidance was conducted to characterize hazardous air
constituents being released from a wood treatment facility.  Evaluation of these
screening results indicated that it was necessary to conduct a monitoring program
to more accurately quantify air emissions from units at the facility. Meteorological
data were first collected to determine the wind  patterns in the area.  The wind
direction data with the locations of the potential  emission sources were then used
to select upwind/downwind air sampling locations.

Facility Description

     The site is a 12-acre wood treatment facility located in a flat inland area of the
southeast. Creosote and pentachlorophenol are used as wood preservatives; heavy
metal salts  have been used in the past. Creosote  and pentachlorophenol are
currently disposed  in an  aerated  surface impoundment.  Past waste disposal
practices included treatment and disposal  of the metal salts in a surface
impoundment, and disposal of contaminated wood  shavings in waste piles.  The
constituents of concern in  the facility's waste stream include phenols, cresols, and
poiycyclic aromatic hydrocarbons  (PAH)  in the creosote; dibenzodioxins and
dibenzofurans as contaminants in pentchlorophenol;  and particulate heavy metals.
The potential emission sources (Figure 15-51) include the container storage facility
for creosote and pentachlorophenol, the wood  treatment and  product storage
areas, the aerated surface  impoundment for the  creosote and pentachlorophenol
wastes, and the contaminated soil area which previously contained both the surface
                                 15-158

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PREVAILING
WIND
DIRECTION
                        INACTIVE SURFACE
                        IMPOUNDMENT AND
                        CONTAMINATED
                        WOOD SHAVINGS
                        STORAGE AREA
                      AERATED
                      SURFACE
                      IMPOUNDMENT
                                           STATION 2 (V)
                         OFFICE
     STATION 4 (V)«
TREATMENT
AND PRODUCT
STORAGE AREAS
                                                I
                   STATION 1 (PVM)
                              CONTAINER
                              STORAGE
                              FACILITY
                                                        STATION 3 (PV)
                                   GATE
                         KEY

                      *  AIR MONITORING STATIONS
                      P  PARTICULATE MONITORING
                      V  VOLATILE CONSTITUENT MONfTORl
                      M  METEOROLOGICAL MONITORING
                                                                    N
                 Figure 15-51. Site Plan and Locations of Air Monitoring Stations
                                          15-159

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impoundment for treating the metal salts and the wood shavings storage area.
Seepage from these .waste management units has resulted in documented ground-
water and surface water contamination.

     The area surrounding the facility has experienced substantial development
over the years. A shopping center is now adjacent to the eastern site perimeter. This
development has significantly increased the  number of potential receptors of air
releases of hazardous constituents.

Program Design/Data Collection

Preliminary Screening Survey-

     A limited-on-site air screening survey was first conducted to document air
releases of potentially hazardous consituents, to prioritize air emission sources, and
to verify screening assessment modeling results and the need  to  conduct a
monitoring program.  Total hydrocarbon (THC) levels were measured with a
portable THC analyzer downwind of the aerated surface impoundment, wood
treatment area, and product storage area. Measurements were also made upwind
of all units to provide  background concentrations.  Because THC levels detected
downwind were significantly higher than background levels, a comprehensive
monitoring program to characterize  releases to  the air was designed  and
implemented.

Waste Characterization-

     To develop an adequate monitoring program, the composition  of wastes
handled in each waste management unit was first determined to identify which
constituents were likely to be present in the air releases. Existing water quality data
indicated contamination  of ground water with cresols, phenol, and PAHs and of
surface water with phenols,  benzene, chlorobenzene, and ethylbenzene. A field
sampling program was developed to characterize further the facility's waste stream.
Wastewater samples were collected from the aerated surface  impoundment and
soil samples were  collected from the heavy metal salt waste  treatment/disposal
area.  Analytical data from this sampling effort confirmed the presence of the
constituents  previously identified.  Additional constituents  detected included
toluene and xylenes in  surface  impoundment wastes, and arsenic, copper,
chromium, and zinc in the treatment/disposal area.
                                 15-160

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     Based on their individual emission potentials and potentials for presenting
health and environmental hazards, the following constituents were selected  for
measurement in the air monitoring program:
     Volatile/semi-volatile constituents:   toluene, benzene, total phenols, penta-
                                      chlorophenol, PAHs, cresols
     Particulate constituents:            aresenic, copper, chromium, zinc.

Meteorological Data Collection--

     Meteorological information is critical for designing an air monitoring program
because stations must be located both upwind and downwind of the contaminant
sources. Therefore, a one-month meteorological monitoring survey was conducted
at this flat terrain site. The survey was conducted under conditions considered to be
representative of the summer months during which air samples would be collected.
Summer represented worst-case conditions of  light  steady winds and  warm
temperatures.  The collected meteorological data showed that the local  wind
direction was from the southeast.  No well-defined secondary wind flows  were
identified.

Initial Monitoring--

     Alternative  methods were considered  for monitoring emissions from  the
aerated surface impoundment and  contaminated storage  area.  Direct emission
measurements (such  as use of  isolation flux chambers)  would  not be practical  for
aerated  ponds or for monitoring particulate emissions from area sources.
Therefore, an air monitoring program with samplers located  in proximity to  the
other units of concern was selected for this application.

     The on-site meteorological survey data were used with the EPA atmospheric
dispersion model, ISC (Industrial Source Complex Model), to  estimate  worst-case air
emission concentrations and to help determine the locations for the air sampling
stations. The ISC model was used because it is capable of simulating  conditions of
point and non-point source air emissions. Using the established southeast wind
direction, maximum  downwind  concentrations were predicted for different
                                  15-161

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meteorological conditions (e.g., wind speed).  Upwind background stations and
downwind monitoring stations were selected based on the predicted dispersion
pathways. Because the releases from the individual  waste management  areas
overlapped, the model also provided a means for separating the incremental
contamination due to each source.

     Figure 15-51 shows the locations of the selected sampling stations.  Station 1 is
the upwind  background  station.   Here background volatile  concentrations,
particulate concentrations, and meteorological  conditions were  monitored.
Stations 2 and 4 were located to identify volatile emissions from the aerated surface
impoundment and wood treatment/product storage areas, respectively. Station 3
was located  downwind of the  inactive surface  impoundment/wood shavings
disposal area.  This station was sited to document releases from these waste
management  units and to document worst-case concentrations of volatiles and
particulates at the facility property boundary. For this application the locations of
Stations 2,3 and 4 were adequate to characterize air concentrations at both the unit
boundary as well as the facility property boundary (due to the proximity of these
two boundaries in the area downwind, based on the prevailing wind direction, of
the units of concern).  A trailer-mounted air  monitoring station was used to
supplement the permanent stations and to account for any variability in  wind
direction.

Sample Collection-

     The air quality monitoring was conducted over a three-month period during
the summer.  Meteorological variables were  measured  continuously on site
throughout the study. Air samples were taken over a 24-hour period approximately
every six days. The sampling dates were flexible to insure that worst-case conditions
were documented.

     Volatile and semi-volatile constituents were sampled by drawing ambient air
through a sampling cartridge containing sorbent media.  A modified high volume
sampler consisting of a glass fiber filter with a polyurethane foam backup sorbent
(EPA Method TO4) was used to sample for total phenols, pentachlorophenol, and
PAHs.  Benzene and toluene were collected  on Tenax sampling  cartridges (EPA
                                 15-162

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Method T01) and cresol was collected on silica'gel cartridges (NIOSH Method Z001).
Participates were collected on filter cassettes using high-volume samplers.

     In addition to the constituents previously discussed, Appendix VIII metals were
analyzed on the first few sets of samples. These analyses were conducted to identify
air releases of constituents other than  those  known  to be present.   The results
indicated that no additional constituents were present in significant concentrations,
so the additional analyses were dropped for the remainder of the study.

Program Results/Data Analysis

     Standard sampling/analytical methods  were available for all  the target
monitoring constitutents.  Analytical detection limits  were below specific health
and environmental criteria for all constituents except cresol.  The high analytical
detection limit for cresol which exceeded reference health criteria complicated data
analysis. This difficulty was handled by the routine collection and analysis of waste
water samples during the air monitoring program.   These  data were  used to
estimate cresol levels in the air by comparing its emission potential to the other air
monitoring constituents which have relativeJy low detection levels.

     Analytical results obtained during this sampling  program established that
fugitive air emissions significantly exceeded  reference health criteria.  Source
control  measures were implemented to reduce emission concentrations below
health criteria levels. Subsequent air monitoring was conducted at the same stations
                                                           •
used previously  on a weekly  basis immediately  after implementation of the
remedial measures, and on a quarterly basis thereafter.

Case Discussion

     This case illustrates a sequence of tasks which were taken to design  an air
monitoring program at a site with multiple air emission sources. An initial field
survey was conducted to identify 'local  prevailing  wind patterns and to identify
potential downwind receptors of fugitive air emissions. The meteorological survey
results were used to design an effective monitoring network. Monitoring station
locations were selected to obtain background conditions and to document air
releases downwind of each emission source. Also, the monitoring strategy included
                                   15-163

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use of a portable sampling station to provide flexibility in sampling locations to
account for variation in wind direction. Spatial variability in air concentration was
assessed with the aid of an air dispersion model to assist in data interpretation.

     Air emissions data showed an  air release of hazardous  constituents
significantly above health crtiteria levels.  Remedial measures were implemented,
and periodic subsequent monitoring was conducted to insure compliance with the
health criteria.
References
Methods T01 and T04, Compendium of Methods for Determination of Toxic Organic
Compounds in Ambient Air. 1984, EPA-600/4-84-041.
Method 2001, NISOH Manual  of Analytical Methods. 1984, National  Institute of
Occupational Safety and Health.
                                  15-164

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CASE STUDY 27:     DESIGN OF A SURFACE WATER MONITORING PROGRAM

Point Illustrated

     •    When designing a surface  water monitoring program, site-specific
          sediment and suspended solids information should be considered.

Introduction

     Designing a surface water  monitoring  program to determine the extent of
contamination involves identifying the potential waste sources, the contaminants
likely to  be present in  each  waste stream, and the flow paths  by  which the
contaminants could reach surface waters. The fate of the contaminants once they
reach the surface water must also be considered when selecting sampling stations
and parameters to be measured.  The example described here illustrates the design
of a monitoring program for a river system.

Facility Description

     A facility which processed zinc, copper and precious metals from ores operated
along a river for five years. The plant was closed after being cited for repeated fish
kills which were reportedly due to failures of a tailings pond dike. At present, the
site is  covered with tailings containing high concentrations of  copper,  zinc,
cadmium, arsenic and lead. There is no longer a tailings pond.

Site Setting

     The site is located  on coarse colluvium  (hill-slope deposits of weathered
bedrock)  and fine-grained alluvium.  These deposits are typically 50 feet thick.
Metamorphic rock (phyllite) underlies the unconsolidated materials.  Ground water
moves  laterally in the gravel formations from  the steep valley walls towards the
river.

     The site is about 400 feet from the river. Two drainage ditches cross the lower
portion of the site and  merge prior to leaving the site.  The ditch carries the
                                  15-165

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combined flow and discharges directly into the river  (Figure 15-52).  No other
tributaries enter the river within two miles of this location.

Sampling Program

     A surface water monitoring program was designed as part of the Phase I
remedial investigation to determine the extent of contamination in the  river.
Existing data from a reconnaissance visit had shown high concentrations of metals
in the drainage ditch sediments (e.g., 5,170 mg/kg Cu and 11,500 mg/kg Zn). Ground
water data from the plant's well showed  concentrations of Cu (7 ug/l) and Zn (54
ug/l). The contribution of metals to the river by ground-water discharge at the site
was considered to be relatively small.

     Based on a review of the plant history and the available water quality and
sediment data, a monitoring program was designed. The potential pathways by
which metals could reach  the river appeared to be direct discharge from  the
drainage ditch, seepage of contaminated ground water, and storm water runoff.
Plant records indicated that typical flows in the drainage ditch at its confluence with
the river varied from 1 to 3 cubic feet per second (cfs) in the spring.  During extreme
flood conditions, the flow in the ditch exceeded 20 cfs.  In the summer, flows in the
drainage  ditches  at all locations were less than 0.5 cfs.   Resuspension  of
contaminated sediments in the ditches during storm runoff appeared to be  the
most likely pathway for metals to reach the river. The specific metals of concern
were identified as As, Cd, Cu, Pb and Zn based on the processes used at the plant
and  the composition of the ores which contained some arsenopyrites (As, Cu),
galena (Pb), and sphalerite (Zn, Cd).

     The available  soil and water quality  data from the reconnaissance visit were
reviewed to determine the likely fate of the metals.   Soils in the area were
circumneutral (pH  s 6.5) and contained about 0.5 percent organic  matter by
weight. Thus the metals, particularly Pb, would be expected to adsorb onto the soil
particles. In the on-site tailings piles, the  pH of core samples ranged between 3.3
and 4.9. Low soil pH values had been measured  in sediments in the drainage ditch
just  downgradient of the tailings  pile.  The pH  of the river  during  the
reconnaissance was 6.9. The suspended solids concentration was 10 mg/l.
                                  15-166

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• S6
                                                               To S8
          Area of
          Former
          Tailings
          Pond
   Site Operation*

   Drainage Ditch

   Sampling Station
                 N
                                                                    t
     Scale
I               I
0             160 feet
Figure 15-52.  Sampling Station Locations for Surface Water Monitoring
                                 15-167

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     Estimates of the distribution of metals between the dissolved and adsorbed
phases for a range of partition coefficients (Kp) are shown in Table 15-16.  For
example, if Kp =  104 and the suspended solids concentration was 10 mg/l, 90
percent of the metal present would be in the dissolved phase.  This information
indicated that even though a metal (e.g., lead), was known to sorb strongly, a
significant amount could be transported in the dissolved phase.  Thus, both water
and suspended solids should be  analyzed  for metals.  The  complete list of
parameters selected for measurement in the Phase I investigation and the rationale
for their selection are outlined in Table 15-17.

    The sampling stations were selected to determine river quality up- and
downstream of the site and to determine whether particulates with sorbed metals
were deposited on the river banks or streambed.  The sampling stations and the
rationale for their selection are  listed in Table  15-18. The station locations are
shown in Figure 15-52.   Because floods were considered to  be one cause of
contamination incidents, samples were to be collected under both high and low
flow conditions.

    Selected results of the surface water quality sampling program for spring
conditions are given below:
Station
S5 (mouth of ditch)
S7 (upstream)
S8 (downstream)
Dissolved Copper
Concentration, ug/1
1110
2.7
4.0
                                  15-168

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                          TABLE 15-16

    RELATIONSHIP OF DISSOLVED AND SORBED PHASE POLLUTANT
    CONCENTRATIONS TO PARTITION COEFFICIENT AND SEDIMENT
                        CONCENTRATION
Kp
100




101




102




103




104




SS
(ppm)
1
10
100
1000
10,000
1
10
100
1000
10,000
1
10
100
1000
10000
1
10
100
1000
10000
1
10
100
1000
10,000
Cw/
-------
                  TABLE 15-17
PARAMETERS SELECTED FOR SURFACE WATER MONITORING
                   PROGRAM
Parameters
Metals - As, Cd, Cu,Pb, Zn
pH
Dissolved Oxygen, Sulfide,
Fe(ll), Fe(lll)
Alkalinity
Total Dissolved Solids
Major Cations (Ca2 * , Mg2 * ,
Na*,KMMH%)
Major Anions (C1-,SO42-,NO3")
Suspended Solids
Streamflow
Rationale
Determine extent of contamination
Predict sorption behavior, metal
solubility, and speciation
Determine redox conditions which
influence behavior of metals,
particularly the leaching of tailings
A measure of how well buffered a
water is; allows consideration of the
likelihood of pH change
Used as a water quality indicator and
for QA/QC checks
May identify other waste sources;
can influence fate of trace metals
Predict the fraction of metal in water
which is sorbed
Compute mass balances and assist in
identifying sources of observed
contamination
                    15-170

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                      TABLE 15-18
SELECTED SURFACE WATER MONITORING STATIONS AND RATIONALE
Station
Drainage ditch west of site
(SI)
Drainage ditches on site (S2
and S3)
Downstream of confluence of
2 ditches (54)
Mouth of drainage ditch (55)
River (56, S7, and 59)
River (S8)
Media
Water and sediments
Water and sediments
Water and sediments
Water, suspended
sediment, bedload
Water, suspended
sediment, bedload
Water, suspended
sediment, bedload
Rationale
Determine whether off-site drainage is
significant source of contamination
Identify on-site sources
Provide information for checking mass
balances from the two drainage ditches
Determine upstream water quality
Determine upstream water quality
Determine quality downstream of site
and provide data for mass balance
                        15-171

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A mass balance was computed to determine how much of the apparent decrease
from the ditch (S5) to the downstream river sampling point (58) was due to dilution
and how much could be attributed to other processes (e.g., sorption, precipitation).
The concentration in the river considering dilution alone  was predicted using the
following mass balance equation:

         CUQU + CWQW
     CR =	
          Qu + Qw
where
     CR « downstream concentration of pollutant in river following mixing with
                   ditch waters (58), ug/l
     Cw = concentration in ditch water (55), ug/l
     Cu = concentration in river above ditch (57), ug/l
     Qw = discharge rate of ditch, ft3/sec
     Qu s flow rate of river above ditch, ft3/sec.

At the time of sampling, the flow in the ditch at station 55 was 1 cfs and the river
flow at station  57 was 155 cfs.   Using the above equation, the predicted river
concentration for Cu was approximately 10 ug/l. (The observed concentration was 4
ug/l.)  The  observed decrease in  concentration  was primarily due to dilution,
although other attenuation processes (e.g., sorption) were probably occurring. The
expected sorbed concentration was estimated as follows:

     X = KPC

where
         X    a   sorbed concentration, ug/kg
         Kp   =   partition coefficient, I/kg
         C    *   concentration of dissolved phase, ug/l.

Here, the sorbed concentration of Cu was estimated as 8 x 105 ug/kg (800 mg/kg).
                                  15-172

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Case Discussion

     This case illustrates the use of site-specific data and the use of information on
the environmental fate of contaminants in the design of a surface water monitoring
program. Site data are needed to locate waste sources and to determine the likely
flow paths by which contaminants reach rivers.  An understanding of the general
behavior of the contaminants of interest and of the factors which influence their
fate is helpful  in determining where samples should be  collected and  what
parameters, particularly master variables, should be measured. Collecting data on
such parameters (e.g., pH, suspended solids) ensures that the necessary information
is available to interpret the data.
                                  15-173

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CASE STUDY 28:     USE OF  BIOASSAYS AND BIOACCUMULATION TO  ASSESS
                 -  POTENTIAL BIOLOGICAL EFFECTS OF HAZARDOUS WASTE ON
                   AQUATIC ECOSYSTEMS

Point Illustrated

•    Measurements of toxicity (i.e., bioassays) and bioaccumulation can be used to
     assess the nature and extent of potential biological impacts in off-site areas.

Introduction

     A study was conducted to determine whether leachate discharged into surface
waters had adversely affected biota in a stream adjacent to a waste site and in a
nearby lake.  The components of the study included chemical analyses of the
leachate, surface waters, sediments, and tissue samples;  toxicity testing of the
surface waters; and  surveys of the structure and composition  of the biological
communities.   Tissue analyses are important for  determining contaminant bio-
accumulation  and assessing  potential human exposure through consumption of
aquatic organisms.  Toxicity testing is important for determining potential lethal
and  sublethal effects of contaminant  exposure on aquatic biota.  Although
ecological analysis of community structure and composition is also an important
component of biomonitoring, it will not  be discussed here since the focus is on the
relationships between the leachate source, the distributions of contaminants near
the waste site, and the toxic effects and bioaccumulation of the contaminants in the
tissues of local fauna.

Site Description

     The 5-acre facility is an industrial waste processing site which accepts wastes
from nearby plastic manufacturing and electroplating industries. Liquid wastes are
dewatered on site prior to removal to an off-site disposal area. The principal wastes
processed at the faclity include several organic compounds and metals.

     The site  contains a wastewater impoundment with numerous seeps and
drainage channels that transport leachate into an adjacent river (Figure 15-53). The
river flows from northeast to southwest,  and is joined by a tributary stream before
                                  15-174

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entering a nearby lake. The RFA indicated an oily sheen associated with a strong
chemical odor on the surface of the stream below the treatment pond, and further
reported numerous violations of the NPDES permit. Subsequent analyses of samples
taken from the drainage channels and seeps flowing into the river showed high
concentrations of organic and trace metal  contaminants, principally bis(2-
ethylhexyl) phthalate, ethylbenzene, phenol, copper, cadmium, and zinc.

Sampling Program

     Six stations were sampled to assess possible toxicity and bioaccumulation of
released substances (Figure 15-53).  Station 6, located upstream of the release, was
selected as a reference location for the stream. Station  17 was selected as a
reference location for the  lake because it is distant from the river mouth and
because prevailing winds from the northwest direct the river discharge along  the
southeast shore of the lake away from the station.  Stations 7, 15, and 18 were
selected to determine the extent of toxic impacts on river and lake biota.

     Water, sediments, and tissues of bottom-dwelling fishes (brown bullhead
catfish. Ictalurus nebulosus) were collected at each station. Concentrations of bis(2-
ethylhexyl) phthalate, ethylbenzene,  phenol, copper, cadmium, and zinc were
measured in each matrix. Analyses were conducted according to U.S. EPA guidelines
for sediments, water,  and  tissues.  Water quality variables (dissolved oxygen,
temperature profiles, and alkalinity), total organic carbon in sediments, and lipid
content of tissues were also  measured.

     Three independent bioassays were conducted on each water sample. The test
species and endpoints  used in the bioassays were those recommended in the U.S.
EPA protocol for bioassessment of hazardous waste sites (Tetra Tech, 1983). Growth
inhibition in the alga Selanastrum capricornutum. and mortality in the crustacean
Daphnia  maana were determined using U.S.  EPA (1985) short-term  methods
for chronic toxicity testing.  Inhibition of enzyme-mediated  luminescence in  the
bacterium Photobacterium phosphoreum (i.e., the Microtox  procedure) was
measured according to the methods established by Bulich et a[. (1981).
                                  15-175

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                                               vrt
                                               C
                                               o
                                               01
                                               C

                                              "5.
                                              •o

                                               fl
                                               C
                                              J2
                                              Q_
                                               nn
                                               in
                                                i
                                               un
15-176

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Results

     Results of the survey indicated that concentrations of organic contaminants m
the surface waters were generally less than U.S. EPA water quality criteria, but that
concentrations of inorganic contaminants generally exceeded water quality criteria
at Stations 7, 15, and 18 (Table 15-19). In comparison with the reference stations,
significant sediment contamination was  evident at Stations 7,  15, and 18 for the
three trace metals (Table 15-20).  Tissue  concentrations of organic substances
exceeded  detection limits for bis(2-ethylhexyl) phthalate at Stations 7 and 15, and
for ethylbenzene at Station 7 (Table 15-21). However, trace metal concentrations in
tissues were highly elevated at Stations 7 and 15, but only slightly elevated  at
Station 18.

     The bioassay data showed a considerable range in sensitivity, with the algal
bioassay being the most sensitive (Table 15-22). Consequently, the bioassay results
were normalized  to the least toxic of the reference stations (i.e., Station 6)  to
compensate for the wide range of sensitivity among the test species (Table 15-23).
Overall, the bioassay results showed a high degree of agreement with contaminant
concentrations in water and sediments  (Figure 15-54, Table  15-19 and 15-20).
Stations 7 and 15 showed highly toxic results, and Station 18 indicated moderate
toxicity. Only the  algal bioassay indicated significant, but low, toxicity at Station  17
(the lake reference station).

     In summary, the results indicated that the organic contaminants were less of a
problem than the trace metals  in terms of bioaccumulation and potential toxicity.
Most of the observed toxicity was attributed to trace metal contamination, which is
consistent with the elevated concentrations of trace metals measured in the water,
sediments, and tissues.

Case Discussion

     This case study provides an example of a biomonitoring program designed  to
characterize the  relationship  between a contaminant  source,  contaminant
concentrations in  sediments and water, bioaccumulation in tissues, and receiving-
water toxicity. It  should  be recognized  that  in many instances, the relationship
                                   15-177

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                              TABLE 15-19

 MEAN CONCENTRATIONS Ug/i) OF ORGANIC SUBSTANCES AND TRACE METALS
                   IN LEACHATE AND SURFACE WATERS3


Chemical Class

Base Neutral

Volatile
Acid Extractable
Metals




Chemical

Bis(2-ethylhexyl)
phthalate
Ethylbenzene
Phenol
Copper
Zinc
Cadmium

Station

Seep
LI
600

100
1500
4300
35,000
4800
River
6
2

1
<1
<1
17
<1
River
7
11

1
18.37
489
4290
146
Lake
15
10

<1.
<1
56
1100
49
Lake
18
1

1
<1
26
37
<1
Lake
17
2

2
<1
2
35
<1
Water Quality
Criteria0

Acute
940

32,000
10,200
18
320
3.9
Chronic
3

NAC
2560
12
47
1.1
'River and lake alkalinity = lOOmgCaCCtyL
"Trace metal criteria adjusted for alkalinity
'Not available for this substance
                                 15-178

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                          TABLE 15-20

      MEAN SEDIMENT CONCENTRATIONS (ug/kg DRY WT) OF ORGANIC
                  SUBSTANCES AND TRACE METALS

Chemical Class


Base Neutral

Volatile
Acid Extractable
Metals



Chemical


8is(2-ethylhexyl)
phthalate
Ethylbenzene
Phenol
Copper
Zinc
Cadmium
Station

Seep
LI
NA1

NA
NA
NA
NA
NA
River
6
216

10
<30
3
11
<0.1
River
7
1188

34
<30
1663
28,314
19
Lake
15
1080

20
<30
190
7260
6
Lake
18
108

14
<30
88
24
<0.1
Lake
17
216

8
<30
7
23
<0.1
aNot applicable (NA).
                             15-179

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                           TABLE 15-21

     MEAN LIVER TISSUE CONCENTRATIONS (ug/kg WET WT) OF ORGANIC
                  SUBSTANCES AND TRACE METALS
Chemical Class
Base Neutral
Volatile
Acid Extractable
Metals
Chemical
Bis(2-ethylhexyl)
phthalate
Ethylbenzene
Phenol
Copper
Zinc
Cadmium
Station
Seep
LI
NA'
NA
NA
NA
NA
NA
River
6
<25
<5
<30
118
983
115
River
7
95
9
<30
1600
28,400
1600
Lake
15
86
<5
<30
750
8500
639
Lake
18
<25
<5
<30
237
2139
190
Lake
17
<25
<5
<30
180
1420
125
aNot applicable (NA).
                             15-180

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                                TABLE 15-22

   MEAN LC50 AND EC50 VALUES (PERCENT DILUTION) FOR SURFACE-WATER
                                BIOASSAYS3

Bioassay
Algae
Daphnia
Microtox

Endpoint
Growth inhibition
(EC50%)'
Mortality (LC5o%)a
Decreased
luminescence
(EC5o%)*
Station

Seep
L1
NA°
NA
NA
River
6
>100C
>100
>100
River
7
0.4
3.3
5.6
Lake
15
10.0
18.5
15.0
Lake
18
24.9
100.0
43.4
Lake
17
75.0
90.0
>100
aPercent dilution required corresponding to a 50 percent response
"Not applicable (NA) because leachate toxicity was not tested
'Response of > 100 indicates that samples were not toxic at all dilutions tested
"Percent dilution corresponding to 50 percent mortality
                                   15-181

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                                TABLE 15-23

             RELATIVE TOXICITY OF SURFACE-WATER SAMPLES8

Bioassay


Algae

Daphnia
Microtox



End point


Growth inhibition
(EC50%)
Mortality (LCso%)
Decreased
luminescence
(EC50%)'
Station

Seep
L1
NA°

NA
NA


River
6
0.0

0.0
0.0


River
7
99.6

96.7
94.4


Lake
15
90.0

81.5
85.0


Lake
18
75.1

0.0
56.6


Lake
17
25.0

10.0
0.0


'Relative toxicity s 100 x [(Reference Station - Impacted Station)/Reference Station]
"Not applicable (NA) because leachate toxicity was not tested
                                   15-182

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i
i
•^f
g
o
§
100

 90 -

 80

 70

 60

 50

 40

 30

 20

 10

 0
                                                         \
                           Rfvw?
                                                      18
                                                                      /\
                  17
                                       Stnoon
      100
      90 -

      80 -

      70

      80

      50
      40

      30

      20

      10 -

       0

             Rfv«r9
            zz

                                                      I
                                                      I
                                       19
                                 Station
                              Dophnio
Lota* 18

  Mleratox
         Figure 15-54. Bioassay Responses to Surface Water Samples
                                   15-183
17

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between contaminant concentrations in the water and toxicity will not be as clear-

cut as described  in this example.  Consideration of the chemical composition in

leachate samples, mass balance calculations, and transport and fate mechanisms
may indicate that sediments are the  primary repository of contaminants. In such
instances, sediment bioassays rather than receiving-water bioassays may  be better
suited for characterization of potential toxic effects on local fauna.


References

Bulich, A.A., M.W. Greene, and D.L Isenberg.  1981.  Reliabiltv  of the bacterial
luminescence  assay for determination  of the toxicitv of pure compounds and
complex effluent,  pp. 338-347. In:  Aquatic toxicology and  hazard assessment.
Proceed ings of the fourth annual symposium. ASTM STP 737.  D.R. Branson and K.L
Dickson (eds). American Society for Testing and Materials, Philadelphia, PA.

TetraTech.  1983.  Protocol for bioassessment of hazardous waste sites.  EPA-600/2-
83-054.  Lafayette, CA.  42 pp.  + appendices.

U.S. Environmental Protection Agency.  1985.  Short-term  methods for estimating
the chronic toxicitv of effluents and receiving"waters to freshwater organisms.
EPA/600/4-85/014.  U.S. EPA,  Environmental Monitoring and  Support Laboratory,
Cincinnati, OH. 162pp.
                                  15-184

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CASESTUDY29:     SAMPLING  OF SEDIMENTS ASSOCIATED WITH SURFACE
                   RUNOFF
Point Illustrated

     •    Contaminated sediments associated with surface runoff pathways
          (rivulets or channels) are indicative of the migration of chemicals via
          overland flow.

Introduction

     This facility is a secondary lead smelting plant which began operation in 1976.
The  plant reclaims lead from materials such as waste automotive batteries,
byproducts of lead weight manufacture, and wastewater sludges. Lead grid plates
from salvaged batteries are temporarily stored on site in an open pile prior to being
re-melted. It is therefore appropriate to conduct some form of runoff sampling to
monitor migration of contaminants from the site via this route.

Facility Description

     The facility covers approximately 2,000 ft? and is situated in an area primarily
used for farming. A creek flows adjacent to the plant and drains into a major river 6
miles west of the site.  Population is sparse with the nearest town 4 miles to the
south.  In the past, there have been four on-site impoundments in operation and
two landfills. In addition, blast furnace slag, lead grid plates, and rubber chips from
the recycled batteries have been stored in two on-site waste piles.

Sediment Sampling

     Four sediment samples (020, 022, 025, and 027) were collected from surface
runoff pathways and a creek  which receives runoff from the site.  Figure 15-55
shows the locations of the runoff pathways relative to the facility and the four
sampling points.  Additional sediment samples were collected from the creek at
various points upstream and downstream of known overland leachate seeps and
surface water runoff routes.  The program design enabled comparison between
                                  15-185

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                                                  . CLOSED
                                                   IMPOUNDMENT 3
                        CLOSED SLAG
                        STORAGE AREA —
                                               CLOSED RUBBER CHIP
                                               STORAGE AREA
                              CLOSED SLAG
                              STORAGE AREA
                              • DRILL HOLES
                                WASTE AREA
                                WELLS
                                  FEET
                                         200
Figure 15-55.  Surface Water and Sediment Sample Locations
                       15-186

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concentrations at different sections  of the creek and  background  locations in
relation to the runoff pathways.

Results

     Table 15-24 presents the concentrations of lead and arsenic measured on the
four surface runoff pathways and at location 029, which represents an upstream
background  concentration (Figure 15-55).  It is clear that highly elevated levels of
lead were detected in all four of the runoff  pathway samples.  The  highest
concentration of lead, 1,900 ppm, was detected in the western-most portion of the
site. Runoff pathway sediment at the northern end of the facility, adjacent to the
slag storage area, recorded 1,600 ppm of lead.  Concentrations of this order
represent a substantial source of sediment contamination.
                               TABLE 15-24
            ARSENIC AND LEAD CONCENTRATIONS (PPM) IN RUNOFF
                            SEDIMENT SAMPLES
                   	Sampling Location
Contaminant
Arsenic
Lead

Case Discussion

    This case illustrates the importance of monitoring surface runoff pathways,
because they can represent a major route of contaminant migration from a site,
particularly for contaminants likely to be sorbed on or exist as fine particles.  This
type of monitoring is especially useful  for units capable of generating overland
flows. Such monitoring can establish the need for corrective.measures (e.g., surface
runon/runoff controls and/or some form  of waste leachate collection system).
#020
11.0
1300
#022
9.6
1900
#025
2.0
1600
#027
8.9
1700
Background
#029
<0.1
11.0
                                  15-187

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CASE STUDY 30:     SAMPLING PROGRAM DESIGN FOR CHARACTERIZATION OF A
                  WASTEWATER HOLDING IMPOUNDMENT

Points Illustrated

     •   Sampling programs should  consider three-dimensional  variation in
         contaminant distribution in an impoundment.

     •   Sampling programs should  encompass active  areas near inflows and
         outflows, and potentially stagnant areas in  the  corner of an
         impoundment.

Introduction

     This study was conducted  to assess whether an active liquid waste
impoundment could be assumed to be of homogenous composition for the purpose
of determining air emissions.  This case shows the  design of an appropriate
sampling grid to establish the three-dimensional composition of the impoundment.

Facility Description

     The unit being investigated in this study is a wastewater impoundment at a
chemical manufacturing plant. The plant primarily produces nitrated aromatics and
aromatic amines. Raw materials include benzene, toluene, nitric acid, and sulphuric
acid.  Wastewater  from  the  chemical processing is discharged  into  the
impoundment prior to being treated for  release into a nearby water body.  The
impoundment has an approximate surface area of 3,750 m2 and a depth of 3 m.

Sampling Program

     For the most part, sampling involved the collection of grab samples using an
extended reach man-lift-vehicle. The program was designed to collect samples at
different locations and depths in the impoundment.
                                15-188

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Sampling Locations and Procedures--

     Samplinq Grid - The wastewater impoundment was divided into 15 segments
of equal area.  Within this grid, eight sampling  locations were  selected which
included all pertinent areas of the impoundment, such as active portions near the
inflows and outflows, potential stagnant areas in the corners, and offshore points
near the center line of the impoundment.

     It was decided to take samples from four depths in the liquid layer and one
from the bottom sediments at each of the eight locations.  Figure 15-56 shows the
impoundment schematic and sampling locations.

     Liquid Sampling - A total of 32 liquid grab samples were taken. These were
analyzed for the following parameters: all identifiable volatile organic compounds
(VOCs) and semivolatile organic compounds (SVOCs) using gas chromatograph/mass
spectroscopy; and selected  VOCs and SVOCs by gas chromatography using a flame
ionization detector.

     Sediment/Sludge Sampling - The bottom layer was sampled using a Ponar grab
sampler. The same analyses were performed on the eight sediment/sludge samples
as on the liquid samples.

     Meteorological Monitoring - The ambient meteorological conditions were
monitored throughout'the  sampling period, including wind speed, wind direction,
and air temperature. A video camera was also used to record the movement of
surface scum on the impoundment.

     Table  15-25 summarizes the sampling locations and analyses, including
locations where QC data were collected.

Results

     From the sampling program, it was discovered that approximately 99 percent
of the organic compounds (by weight) were contained in the bottom sludge layer.
                                 15-189

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                     117'
   343'
               D
              A

             (*
                             H
E 0
      © - PROPOSED SAMPLING  LOCATIONS
O
X

o
Ul
EXISTING
                                                          N
                                                 PLANT SUMP EFFLUENT
                                                 INFLUENT/LAGOON
                                                 EFFLUENT
                                                 BOILER BACK WASH EFFLUENT
                                                 PRIMARY PLANT EFFLUENT
Figure 15-56.   Schematic of Wastewater Holding Impoundment Showing

              Sampling Locations
                                15-190

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                             TABLE 15-25

         SUMMARY OF SAMPLING AND ANALYSIS PROGRAM FOR
                    WASTEWATER IMPOUNDMENT
Location
A-1
A-2
A-3
A-4
A-5
8-1
8-2
8-3
B-4
8-5
C-1
C-2
C-3
C-4
D-1
D-2
D-3
D-4
D-5
DeQth
(Feet)
0-1
2
4
6
Bottom
Sediment
0-1
2
4
6
Bottom
Sediment
0-1
2
4
Bottom
Sediment
0-1
2
4
6
Bottom
Sediment
Sample Analyses
GOFID
VGA
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
GGMS
VGA
X



X
X



X
X


X
X



X
TOC
X



X
X



X
X


X
X



X
POC
X




X




X



X




Onsite
Parameters*
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
GGFID
svoc
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
GC/MS
svoc
X



X
X



X
X


X
X



X
a Includes pH, turbidity, specific conductance, and dissolved oxygen measurements.
X Indicates locations where QC samples were collected.
                                15-191

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                          TABLE 15-25 (continued)
Location
E-1
E-2
E-3
E-4
E-5
F-1
F-2
F-3
F-4
F-5
G-1
G-2
G-3
G-4
G-5
H-1
H-2
H-3
H-4
H-5
Depth
(Feet)
0-1
2
4
6
Bottom
Sediment
0-1
2
4
6
Bottom
Sediment
0-1
2
4
6
Bottom
Sediment
0-1
2
4
6
Bottom
Sediment
Sample Analyses
GC/FID
VOA
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
GC/MS
VOA
X



X
X



X
X



X
X



X
TOC
X



X
X



X
X



X
X



X
POC
X




X




X




X




Onsite
Parameters*
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
GGFID
svoc
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
GC/MS
svoc
X



X
X



X
X



X
X



X
a Includes pH, turbidity, specific conductance, and dissolved oxygen measurements.
X I nd i cates I ocati ons where QC sam pi es were col I ected.
                                   15-192

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Vertical and horizontal variation in the composition of the lagoon was apparent.
The degree of horizontal variation was relatively small, but sample point "A"
showed consideraby higher concentrations of 2,4-dinitrophenol than the other
locations. This could have resulted from a recent discharge from the outflow at the
southern end of the impoundment.  Vertical variation in composition showed a
general trend of increasing concentration with depth, but certain  chemicals tended
to have higher concentrations at mid-depth in the impoundment.

Case Discussion

    This case provides an example of a sampling program at an areal source
designed to yield accurate information for characterizing air emissions from the
unit.   The study  illustrated the importance  of characterizing the  organic
composition of the lagoon in three dimensions and considering variations resulting
from inflow and outflow areas.

    It should be mentioned that this study did  not  consider variation in the
chemical composition of the impoundment with time. To obtain tLs information, it
would be necessary to conduct subsequent sampling programs at different times.
From this study, it is apparent that chemical composition  varies  both horizontally
and vertically, and is likely to change depending on inflows and outflows of wastes.
This sampling  program is therefore limited to effectively characterizing composition
at a single point in time.
                                  15-193

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CASE STUDY 31:     USE OF DISPERSION  ZONE CONCEPTS  IN THE DESIGN OF A
                   SURFACE WATER MONITORING PROGRAM

Point Illustrated

    •    Estimation of the dispersion zone of contaminants downstream of a
          release point can be used to help design a surface water monitoring
          program.

Introduction

    When a contaminant is initially released to a body of water, the concentration
of the contaminant will  vary spatially until fully dispersed.   In streams, the
contaminant will disperse with the surrounding ambient water as the water moves
downstream and will eventually  become fully dispersed within the stream.
Downstream of this point, the contaminant concentration will remain constant
throughout the stream cross-section, assuming that streamflow is constant and that
the contaminant is  conservative (e.g., nondegradable).  The area in which a
contaminant's concentration will vary until fully dispersed, referred to here as the
dispersion zone, should be considered when determining the number and location
of sampling stations downstream of the release point.

Facility Description

    A facility that processed zinc, copper and precious metals from ores operated
along  a stream for five years.  The plant was closed  after being cited for repeated
fish kills, reportedly due to failures of  a tailings pond dike. At present, the site is
covered with tailings containing high concentrations of copper,  zinc,  cadmium,
arsenic, and lead.  There  is no longer a  tailings pond. This is the same facility
described in Case Study 27.

Site Setting

    The  site is located on coarse colluvium (hill-slope deposits of weathered
bedrock)  and fine-grained alluvium.  These deposits are typically 50  feet thick.
Metamorphic rock (phyllite) underlies the unconsolidated materials. Ground water
                                  15-194

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moves laterally in the gravel formations from the steep valley walls toward the
stream.

     The site is located about 400 feet from the stream. Two drainage ditches cross
the lower portion of the site and merge prior to leaving the site. The ditch carries
the combined flow and discharges directly into the stream (Figure 15-57). No other
tributaries enter  the stream within 2 miles of this location.  Downstream of the
release point, stream width and depth remain fairly constant at 45 and  3  feet,
respectively. Mean stream velocity is 0.5 feet per second and channel slope is 0.0005
feet per foot.

Sampling Program

     A surface water  monitoring program was designed as  part of a Phase  I
investigation to determine the extent of contamination in the stream.  Existing data
from previous sampling had shown high concentrations of metals in the drainage
ditch sediments (e.g., 5,170 mg/kg Cu and 11,500 mg/kg Zn). Ground-water data
from the plant's well showed concentrations of Cu (7 ug/0 and Zn (54 ug/i).  The
contribution of metals to the stream by ground-water discharge was considered to
be relatively minor.

     Based  on a  review of the  plant history and the available water quality and
sediment data, a monitoring program was designed.  The potential  pathways by
which metals could reach the stream appeared to be direct discharge from the
drainage ditch, discharge of contaminated ground water, and storm water runoff
over the  general facility area.  Plant records indicated that  typical flows in the
drainage ditch at its confluence with the stream varied from  1 to 3 cubic feet per
second (cfs) in the spring. During extreme flood conditions, the flow in the  ditch
exceeded 20 cfs.  In the summer, flows in the drainage ditches at all locations  were
less than  0.5 cfs.  Resuspension of contaminated sediments in the ditches during
storm runoff appeared to be the most likely  pathway for metals to reach the
stream.  The specific metals of concern were identified as As, Cd, Cu, Pb and Zn,
based on the  processes used at the plant and the composition of the ores which
contained some arsenopyrites (with As, Cu), galena (Pb), and sphalerite (with Zn,
Cd).
                                  15-195

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                ArMof

                Fonw
                Tailings

                Pond
         Site Operation*


         Drainage Ditch


         Sampling Station
                                                                   N
                                                                   t
Scale
        n
        160 tot
     Figure 15-57.  Sampling Station Locations for Surface Water Monitoring
*    Located approximately 1030 feet downstream of the confluence of the ditch

     with the stream.
                                  15-196

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     The available soil and  water quality data from  previous sampling were
reviewed to help determine the likely fate of the metals. The pH of soils in the area
is about 6.5 and they contain about 0.5 percent organic  matter by weight.  Under
such conditions, the metals, particularly Pb, would be expected to adsorb onto the
soil particles.  In the  on-site tailings piles, the pH of core samples ranged between
3.3 and 4.9.  Low soil pH values had been measured  in sediments in the drainage
ditch just downgradient of the tailings pile.  The pH of the stream during the
previous sampling was 6.9. The suspended solids concentration was 10 mg/l.

     Estimates of the distribution of metals between the dissolved  and adsorbed
phases for a range of partition coefficients (Kp)  are shown in  Table  15-26.  For
example, if Kp = 104 and the suspended  solids  concentration was  10  mg/l, 90
percent (0.9) of the metal present would be in the dissolved phase. This information
indicated that even  though a metal (e.g., lead)  was known to strongly sorb, a
significant amount could still be transported in the dissolved phase.  Thus, both
water and suspended solids should be analyzed for metals.  The complete list of
parameters selected for measurement in the Phase I investigation and the rationale
for their selection are outlined in Table 15-27.

     The sampling stations were selected to determine  stream  water quality up-
and downstream of  the site and to determine whether particulates with sorbed
metals were deposited on the stream banks or streambed. The sampling stations
and the rationale for their selection are listed in Table 15-28.  The station locations
are shown in Figure 15-57.  Because floods  were  considered  a cause of
contamination incidents, samples were to be collected under both  high  and low
flow conditions.

     The location of the downstream station (S8) was determined after estimating
the stream length  that may  be required  for complete  dispersion  of the
contaminants. The following equation was used for this estimation:

              0.4 w2u
     DZ   =    	
              O.Sd-^gds
                                  15-197

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                              TABLE 15-26

      RELATIONSHIP OF DISSOLVED AND SORBED PHASE CONTAMINANT
        CONCENTRATIONS TO PARTITION COEFFICIENT AND SEDIMENT
                            CONCENTRATION

                Kp                     SS              Cw/Cia
10o




101




102




103




104




1
10
100
1000
10,000
1
10
100
1000
10,000
1
10
100
1000
10,000
1
10
100
1000
10,000
1
10
100
1000
10,000
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
0.9
1.0
1.0
1.0
0.9
.0.5
1.0
1.0
0.9
0.5
0.1
1.0
0.9
0.5
0.1
0.0
After Mills et §[.,1985.

•The fraction dissolved (Cw/CT) is calculated as follows:
      C         1
      CT     1+KpxSxKH

where Kp  =  partition coefficient, f/kg
      SS  =  suspended solids concentration, mg/l
      Cw  =  Dissolved concentration
      CT  =  Total concentration
                                 15-198

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                            TABLE 15-27

   PARAMETERS SELECTED FOR SURFACE WATER MONITORING PROGRAM
           Parameters
             Rationale
Metals - As, Cd, Cu, Pb, Zn

PH


Dissolved Oxygen, Sulfide, Fe(ll),
Fe(lll)


Alkalinity
Total Dissolved Solids
Major Cations (Ca * 2, Mg * 2, Na *, K *,
NH4*)and
Major An ions (CI-, SO4-2( NO-3)

Suspended Solids
Streamflow
Determine extent of contamination

Predict sorption  behavior,  metal
solubility, and speciation

Determine redox  conditions  which
influence  behavior  of  metals,
particularly the leaching of tailings

A measure of how well buffered a water
is, allows consideration of the likelihood
ofpH change

Used as a water quality indicator and for
QA/QC checks

May identify other waste sources, can
influence fate of trace metals
Predict the fraction of metal in water
which issorbed

Compute mass balances and assist in
identifying  sources  of observed
contamination
                               15-199

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                             TABLE 15-28

SELECTED SURFACE WATER MONITORING STATIONS AND SELECTION RATIONALE
       Station
       Media
          Rationale
Drainage ditch west of
site(S1)
Drainage ditches on site
(S2 and S3)

Downstream of
confluence of two
ditches (54)

Mouth of drainage
ditch (S5)

Stream (S6, S7 and 59)
Stream (S8)
Water and sediments
Determine whether off-site
drainage is significant source of
contamination
Water and sediments Identify on-site sources
Water and sediments
Water, suspended
sediment, bedload

Water, suspended
sediment, bedload

Water, suspended
sediment, bedload
Provide   information   for
checking mass balances from the
two drainage ditches

Determine quality of direct
discharge to stream

Determine upstream  water
quality

Determine quality downstream
of site  following  complete
dispersion and provide data for
mass balance
                               15-200

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•
         where:
              DZ   -   dispersion zone length, ft
              w   =   width of the water body, ft (45 ft)
              u    =   stream velocity, ft/sec (0.5 ft/sec)
              d    =   stream depth, ft (3 ft)
              s    =   slope (gradient) of stream channel, ft/ft (0.0005)
              g    =   accerleration due to gravity (32 ft/sec 2).

              Using the above equation, the estimated stream length required for complete
         contaminant dispersion is  1030 feet.  This can serve as an approximate distance
         downstream of the release  point at which a sampling station should be located.

         Case Discussion

              This case illustrates the use of contaminant dispersion  zones in the design of a
         surface water monitoring program.  In this example, the  data indicate that
         approximately 1030 feet of flow within the described stream d innel is required
         before a contaminant  will  become fully dispersed.  A downstream station  should
         therefore  be located at or below this dispersion zone to fully characterize the
         extent of the release.  An  adequate number of sampling  stations should also be
         located upstream of this point.
                                            15-201

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