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

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                                         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

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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

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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

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                                                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

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                                  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

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     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.