O EPA
  crM
            United States
            Environmental Protection
            Agency
            Office of Emergency
            Remedial Response
            Washington, DC 20460
EPA/540/P-91/001
February 1991
            Superfund
Conducting Remedial
Investigations/Feasibility
Studies for CERCLA
Municipal Landfill Sites

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                                            EPA/540/P-91/001
                                    OSWER Directive 9355.3-11
                                               February 1991
Conducting Remedial Investigations/
   Feasibility Studies  for CERCLA
       Municipal Landfill Sites
     Office of Emergency and Remedial Response
       U.S. Environmental Protection Agency
            Washington, D.C. 20460
                                        Printed on Recycled Paper

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                                    NOTICE
Development  of this  document was funded by  the  United  States  Environmental
Protection Agency.   It has  been subjected  to  the  Agency's review  process  and
approved  for publication  as  an EPA  document.

The  policies and  procedures  set  out in this  document  are  intended  solely  for  the
guidance  of response personnel.   They are  not  intended,  nor  can they  be relied
upon, to  create any  rights,  substantive or procedural,  enforceable  by any  party  in
litigation  with  the United  States.  EPA  officials may  decide  to follow  this guidance,
or to act at variance with these policies  and procedures based on  an analysis  of
specific  site circumstances, and  to change  them at any time  without public notice.

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CONTENTS                                                    Page

   GLOSSARY	viii
   ES EXECUTIVE SUMMARY	ES-1
1  INTRODUCTION	1-1
   1.1 Background on Municipal Landfills	1-2
   1.2 Document Organization	1-3

2  SCOPING THE RI/FS FOR MUNICIPAL LANDFILL SITES	2-1
   2.1 Evaluation of Existing Data	2-2
          2.1.1 Sources of Information	2-2
          2.1.2 Types of Data and Data Quality	2-3
          2.1.3 Presentation of Available Data	2-4
   2.2 Existing Data Evaluation Results  and Report	2-4
          2.2.1 Site Description	2-6
          2.2.2 Site History	2-7
          2.2.3Regional and Site Geology and Hydrogeology	2-7
          2.2.4 Hydrology	2-9
                 2.2.4.1 Surface Water	2-9
                 2.2.4.2 Groundwater	2-9
          2.2.5 Waste Characterization	2-9
          2.2.6 Sampling Activities and Results	2-10
   2.3 Site Visit	2-10
   2.4 Limited Field Investigation	2-12
   2.5 Conceptual Site Model	2-15
   2.6 Risk Assessment	2-18
   2.7 Preliminary Remedial Action Objectives and Goals	2-19
   2.8 Preliminary Remedial  Technologies	2-20
          2.8.1 Development of Preliminary Remedial
          Action Alternatives	2-20
          2.8.2 Review of Remedial Technologies in
          CERCLA Landfill  RODs	2-21
   2.9 Objectives of the RI/FS	2-23
   2.10 Development of DQOs	2-31
   2.11 Section 2 Summary	2-39

3  SITE CHARACTERIZATION STRATEGIES	3-1
   3.1 Groundwater	3-2
          3.1.1 Groundwater Investigations	3-2
                3.1.1.1 Phase I Site Characterization	3-2
                3.1.1.2 Phase II Site Characterization	3-4
          3.1.2 Data Requirements	3-4
          3.1.3 Placement of Monitoring Wells	3-5
                 3.1.3.1 Objectives	3-5
                 3.1.3.2 Procedures	3-5
                3.1.3.3 Guidelines	3-7
          3.1.4 Groundwater Summary	3-7

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CONTENTS                                                              Page

       3.2 Leachate	3-7
             3.2.1 Leachate Investigations	3-10
                    3.2.1.1 Objectives	3-10
                    3.2.1.2 Procedures	3-10
                    3.2.1.3 Guidelines	3-12
             3.2.2 Data Requirements	3-12
             3.2.3 Leachate Summary	3-13
       3.3 Landfill Contents/Hot Spots	3-13
             3.3.1 Landfill Contents/Hot Spot Investigations	3-13
                    3.3.1.1 Objectives	3-15
                    3.3.1.2 Procedures	3-17
                    3.3.1.3 Guidelines	3-24
             3.3.2 Data Requirements	3-25
             3.3.3 Landfill Contents/Hot Spots Summary	3-25
       3.4 Landfill Gas	 3-25
             3.4.1 Landfill Gas Investigations	3-25
                    3.4.1.1 Objectives	3-25
                    3.4.1.2 Procedures	3-27
                     3.4.1.3 Guidelines	3-28
             3.4.2 Data Requirements	3-28
             3.4.3 Landfill Gas Summary	3-29
       3.5 Wetlands and Sensitive Environments	3-29
             3.5.1 Wetlands and Sensitive Environment Evaluation	3-29
                    3.5.1.1 Objectives	3-31
                    3.5.1.2 Procedures	3-31
                    3.5.1.3 Guidelines	3-31
             3.5.2 Data Requirements	3-32
             3.5.3 Wetlands Summary	3-32
       3.6 Surface Water	3-34
             3.6.1  Surface Water Investigation	3-34
                    3.6.1.1 Objectives	3-34
                    3.6.1.2 Procedures	3-34
                    3.6.1.3 Guidelines	3-36
             3.6.2 Data Requirements	3-36
             3.6.3 Surface Water Summary	3-36
       3.7 Baseline Risk Assessment	3-37
             3.7.1 Components of the Baseline Risk Assessment	3-37
                    3.7.1.1 Contaminant Identification	3-37
                    3.7.1.2 Exposure Assessment	3-39
                    3.7.1.3 Toxicity/assessment	3-39
                    3.7.1.4 Risk Characterization	3-39
             3.7.2 Using the Baseline Risk Assessment to Streamline
                  Remedial Action Decisions	3-39
       3.8 Section 3 Summary	3-40

4 DETAILED DESCRIPTION OF TECHNOLOGIES 	4-1
       4.1 Remedial Action Objectives	4-1
       4.2 Landfill Contents	4-2
              4.2.1 Access Restrictions	4-2

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CONTENTS                                                                Page
             4.2.2 Containment	4-3
                    4.2.2.1 Surface Controls	4-3
                    4.2.2.2 Cap (Landfill Cover)	   4-6
             4.2.3 Removal/Disposal	4-12
                    4.2.3.1 Excavation (Hot Spots)	4-12
                    4.2.3.2 Consolidation	4-14
                    4.2.3.3 Disposal Offsite (Hot shots)	4-14
             4.2.4 Hot Spots Treatment	4-15
                    4.2.4.1 Thermal Treatment (Onsite)	4-16
                    4.2.4.2 Stabilization	4-17
             4.2.5 Innovative Treatment Technologies	4-18
                    4.2.5.1 Description of Technologies	4-18
       4.2. References	4-19
       4.3 Leachate	4-21
             4.3.1 Collection of Leachate	4-21
                    4.3.1.1 Subsurface Drains	4-21
                    4.3.1.2 Vertical Extraction Wells	4-21
             4.3.2 Treatment of Leachate	4-22
                    4.3.2.1 Onsite Treatment	4-23
                    4.3.2.2 Offsite Treatment	4-25
             4.3.3 References	4-27
       4.4 Landfill Gas	4-28
             4.4.1 Collection of Landfill Gas	4-28
                    4.4.1.1 Passive Systems	4-28
                    4.4.1.2 Active Systems	4-29
             4.4.2 Treatment of Landfill Gas	4-30
                    4.4.2.1 Thermal Treatment (Enclosed Ground Flares)	4-30
             4.4.3 References	4-32
       4.5 Groundwater	4-32
             4.5.1 Collection, Treatment, and Disposal	4-32
             4.5.2 Containment	4-32
                    4.5.2.1 Vertical Barriers (Slurry Walls)	4-32
             4.5.3 References	4-34
       4.6 Wetlands	4-35
             4.6.1 Removal or Management of Wetlands Sediments	4-35
             4.6.2 Mitigating Wetlands Losses	4-35
             4.6.3 References	4-36
       4.7  Surface Water and Sediments	4-36
             4.7.1 Treatment of Surface Water	4-36
             4.7.2 Removal and Management of Sediments	4-36
       4.7.3 References	4-37
       4.8 Section 4 Summary	4-37

5 EVALUATION CRITERIA	 5-1
       5.1  Overall Protection of Human Health and the Environment	5-2
       5.2  Compliance with ARARs	5-6
             5.2.1 Federal Arabs	5-6
                    5.2.1.1 Chemical-Specific ARARs	5-6
                    5.2.1.2 Location-Specific ARARs	5-23
                    5.2.1.3 Action-Specific ARARs	5-24

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CONTENTS                                                                  Page

             5.2.2 State ARARs	5-25
                    5.2.2.1 Chemical-Specific ARARs	5-26
                    5.2.2.2 Location-Specific ARARs	5-26
                    5.2.2.3 Action-Specific ARARs	  5-26
       5.3 Long-Term Effectiveness and Permanence	  5-27
       5.4 Reduction of TMV Through Treatment	5-27
       5.5 Short-Term Effectiveness	  5-27
       5.6 Implementability	5-27
       5.7 Cost	5-28
       5.8 State Acceptance	5-28
       5.9 Community Acceptance	5-28
       5.10 Section 5 Summary	5-28

6 DEVELOPMENT AND EVALUATION OF ALTERNATIVES FOR
  THE EXAMPLE SITE	6-1
       6.1 Example Site ARARs	6-8
             6.1.1 Chemical-Specific ARARs	6-8
                    6.1.1.1 Groundwater	6-8
                    6.1.1.2 Surface Water	6-8
             6.1.2 Location-Specific ARARs	6-8
             6.1.3 Action-Specific ARARs	6-8
                    6.1.3.1 Soils/Landfill  Contents	6-8
       6.2 Development of Alternatives	6-8
             6.2.1 Alternative l~No Action Alternative	6-9
             6.2.2 Alternative 2	6-9
             6.2.3 Alternative 3	6-10
             6.2.4 Alternative 4	6-11
       6.3 Comparative Analysis of Alternatives	6-12
             6.3.1 Overall Protection of Human Health  and the Environment	6-12
             6.3.2 Compliance with ARARs	6-12
             6.3.3 Short-Term Effectiveness	6-12
             6.3.4 Long-Term Effectiveness	6-13
             6.3.5 Reduction of Toxicity, Mobility, and Volume Through Treatment.  . 6-13
             6.3.6 Implementability	6-14
             6.3.7 Costs	6-14
       6.4 Section 6 Summary	6-14

7 BIBLIOGRAPHY

Appendix A Site Characterization Strategy for an Example Site

Appendix B Remedial Technologies Used at  Landfill Sites

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TABLES                                                                            Eag£
2-1    Limited Field Investigation  Options for  Municipal Landfill Sites	 2-13
2-2    Preliminary Identification of Remedial Action Objectives for
       Media of  Concern  at  Municipal  Landfill  Sites	  . 2-20
2-3    Remedial  Actions  Used  at  Landfill   Sites	 • • •. 2-24
2.4    Phase I Remedial Investigation Objectives for Municipal
       Landfill    Sites	 2-32
2-5    Phase II Remedial Investigation Objectives for Municipal
       Landfill    Sites	 2-36

3-1    Conditions  That Determine Monitoring  Well Location and Numbers 	.3-8
3-2    Range of Typical Domestic Refuse Leachate Constituent
       Concentrations	  .  3-11
3-3    Leachate    Sampling   Program	  . 3-13
3-4    Summary of Sampling Requirements for Soil  and Landfill Contents • • •	 3-27
3-5    Landfill   Gas   Sampling  Program	 3-29
3-6    Summary of Sampling  Requirements for Environmental Evaluation 	.3-32
3-7    Sampling and Monitoring Rationale for  Surface Water and
       Sediments   Near  Municipal  Landfill   Sites	 • •. 3-36

5-1    Evaluation of Technologies  Frequently Used at Municipal Landfills	 5-3
5-2    Potential Federal Location-Specific  ARARs for Municipal Landfill  Sites  	.5-7
5-3    Potential Federal Action-Specific ARARs for  Municipal  Landfill Sites	 5-9

6-1    Recommended  Alternatives: Summary of Detailed Analysis (Example Site). — . 6-2
B-l     RODs  Reviewed  for Municipal  Landfill  Study  	 .  ...B-l
B-2     Remedial  Technologies  Used at  Landfill Sites  .	 • B-6
B-3     Breakdown by Region of Remedial Technologies Used at Landfill Sites	 B-36

FIGURES

2-1     Flow  Diagram for Data  Evaluation  and  Preparation	 • •. •. 2-5
2-2     Typical Soil/Geologic Cross Section of Municipal Landfill
        and  Adjacent  kegs		  2-8
2-3     Schematic   of  Conceptual  Landfill  Site	 — .  2-16
2-4     Potential Conceptual  Site Model  for Municipal  Landfills 	.2-17
2-5     Identification  of  Remedial  Technologies	 —  . 2-22

3-1     Logic  Diagram  for  Monitoring  Well and  Screen  Placement  ••..	.3-9
3-2     Logic   Diagram  for  Leachate   Sampling  	 	 3-14
3-3     Logic  Diagram for Soils/Landfill  Contents  Sampling  	.--.3-26
3-4     Logic  Diagram  for  Landfill  Gas  Sampling	 •  . 3-30
3-5     Logic Diagram for Environmental  Assessment Near Municipal Landfills	 3-33
3-6     Logic Diagram for  Surface Water/Sediment Sampling Near Municipal Landfill • • •. 3-38

4-1     Landfill   Cover   Selection   Guide...	 4-7
                                           Vll

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      GLOSSARY  OF ACRONYMS AND ABBREVIATIONS
ARAR      Applicable irrelevant  and appropriate requirement
BOD        Biochemical oxygen demand
BTU        British thermal unit
CAA        Clean Air Act
CERCLA    Comprehensive Environmental Response, Compensation and
            Liability Act
CLP        Contract laboratory program
COD        Chemical oxygen demand
CRP        Community relations plan
CWA       Clean Water  Act
DNAPL     Dense, nonaqueous-phase liquid
DQO       Data quality objective
EMSL      Environmental Monitoring Systems Laboratory
EPA        U.S. Environmental Protection Agency
FIT         Field Investigation Team
FML        Flexible membrane liner
FS          Feasibility study
FSP         Field Sampling Plan
FWQC      Federal Water Quality Criteria
GAC        Granular activated carbon
GC         Gas chromatography
GPR        Ground penetrating radar
HOPE      High density polyethylene
HRS        Hazard ranking system
HSP        Health and safety plan
LDR       Land Disposal Restrictions
LFG        Landfill gas
LFI         Limited field investigation
MCL       Maximum contaminant levels
MCLG      Maximum contaminant level goals
NCC       National Climatic  Center
NCP        National Contingency Plan
NPDES     National Pollutant Discharge Elimination System
NPL        National Priorities List
O&M      Operations and  maintenance
OVA       Organic vapor analyzer
PARCC     Precision, accuracy, representativeness, completeness, comparability
PA/SI      Preliminary  assessment/site  inspection
PCB        Polychlorinated  byphenyl
PIC        Products of incomplete combustion
PID        Photoionization  detector
POTW      Publicly owned  treatment works
                                     Vlll

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ppb          Parts per billion
ppm         Parts per million
PRP         Potentially  responsible  party
PVC         Poly vinyl chloride
QAPP       Quality  assurance project  plan
QA/QC      Quality  assurance/quality  control
RCRA      Resource Conservation and  Recovery  Act
RD/RA      Remedial  design/remedial  action
RI          Remedial  investigation
ROD        Record of  decision
RPM        Remedial  project manager
SAP         Sampling and analysis  plan
SDWA      Safe Drinking  Water Act
SOW        Scope of work
SVE         Soil vapor  extraction
TAL        Target analyte  list
TBC        To  be considered
TCE        Trichloroethene
TCL        Target compound list
TCPL       Toxicity  characteristic  leaching  procedure
TDS         Total  dissolved solids
TMV        Toxicity, mobility, and volume
TOC         Total  organic  carbon
TSDF        Treatment,  storage,  and disposal facility
TSS          Total  suspended  solids
USGS        U.S.  Geological Survey
VC          Vinyl chloride
VOC        Volatile  organic  compound

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                        ACKNOWLEDGEMENTS
This document was developed by EPA's Office of Emergency and Remedial Response
with assistance provided by CH2M HILL in partial fulfillment of Contract No. 68-W8-
0098.  Susan Cange served as EPA project manager. The CH2M HILL project team
was headed by John Rendall and included Amelia Janisz, Sadia Kissoon, Dave Bunte,
Fouad Arbid, Gayle Lytle, and Pat Trate.

In addition to the many EPA Headquarters personnel who assisted in this effort, the
following regional, state, and contractor representatives provided significant  contribu-
tions to the preparation of this document:
   Wayne Robinson

   Edward Als
   Sherrel  Henry
   Caroline Kwan

   Fran Costanzi
   Mindi Snoparsky

   Fred Bartman
   Dion Novak
   Robert Swale

   Steve Veale

   Gwen Hooten

   Brian Ullensvang

   Mary Jane Nearman
   Debbie Yamamoto

   Thomas J. Cozzi


   Peter Kmet


   Celia VanDerloop


   Alan Felser

   Phil Smith

   Bill Swanson
EPA, Region I

EPA Region II



EPA Region, III


EPA Region V



EPA Region VI

EPA, Region VIII

EPA Region IX

EPA Region X


State of New Jersey
Department of Environmental Protection

State of Washington
Department of Ecology

State of Wisconsin
Department of Natural Resources

Ebasco

CH2M HILL

CDM/FPC
                                      XI

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                            EXECUTIVE  SUMMARY
A broad  framework   for  the Remedial
Investigation/Feasibility   Study  (RI/FS)  and
selection of remedy process has been created
through the National Contingency Plan (NCP)
and the U.S. EPA RI/FS Guidance (U.S. EPA
1988d). With this framework now in place, the
Office of Emergency and Remedial Response's
efforts are  being focused on streamlining the
RI/FS and selection  of remedy process  for  spe-
cific classes of sites with similar characteristics.
One such class of sites is the municipal landfills
which compose approximately 20 percent of the
sites on the Superfund Program's National Pri-
orities List (NPL).  Landfill sites currently on
the NPL typically  contain a  combination of
principally municipal  and to  a lesser extent
hazardous waste and range in size from 1 acre
to 640 acres. Potential threats to human health
and the environment resulting from municipal
landfills may include

   •    Leachate generation and groundwater
        contamination

   •    Soil contamination

   •    Landfill  contents

   •    Landfill  gas

   •    Contamination of surface waters, sedi-
        ments, and  adjacent wetlands

Because these sites share similar characteristics,
they lend themselves to remediation by similar
technologies. The NCP contains the  expecta-
tion that containment technologies will general-
ly be appropriate remedies for wastes that pose
a relatively low low-level threat or where treat-
ment is impracticable.   Containment has been
identified as the most likely response  action at
these sites because (1) CERCLA  municipal
landfills are primarily composed of municipal,
and to a lesser extent hazardous wastes; there-
fore, they often  pose a  low-level threat rather
than a principal threat; and (2) the volume and
heterogeneity  of  waste  within CERCLA
municipal  landfills  will often  make treatment
impractical.    The  NCP  also contains  an
expectation that treatment should be  considered
for identifiable  areas of highly  toxic and/or
mobile material  (hot spots) that pose potential
principal threats. Treatment of hot spots within
a  landfill will  therefore be considered  and
evaluated.

With these expectations in mind, a study of
municipal landfills was conducted  with the
intent of developing methodologies and tools to
assist in streamlining the RI/FS and selection of
remedy process. Streamlining may  be viewed as
a  mechanism to enhance the efficiency  and
effectiveness of decision-making at these sites.
The goals of this study to meet this objective
include:  (1) developing tools to assist in scop-
ing  the  RI/FS  for  municipal landfill sites,
(2) defining strategies for characterizing munici-
pal landfill  sites that are on the NPL,  and
(3) identifying practicable remedial action alter-
natives for addressing these types of sites.

Streamlining  Scoping

The primary purpose of scoping an RI/FS is to
divide the broad project goals into manageable
tasks that can be performed within a reasonable
period of time. The broad project goals of any
Superfund site are to provide the information
necessary to  characterize the site, define site
dynamics, define risks, and develop a remedial
program to  mitigate  current  and potential
threats to human health and  the environment.
Scoping  of municipal  landfill  sites can  be
streamlined by focusing the RI/FS tasks on just
the data  required to evaluate alternatives that
are most  practicable for municipal  landfill sites.
Section 2 of this document describes the activi-
ties that must take place to plan an RI/FS and
provides guidelines for establishing a project's
scope. To summarize, scoping of the  RI/FS
tasks can be  streamlined by:

   •   Developing preliminary remedial objec-
       tives  and alternatives  based  on the
       NCP  expectations  and  focusing  on
       alternatives successfully implemented at
       other sites

   •   Using a conceptual site  model (see
        Figure 2-4 for a generic model devel-
                                             ES-I

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        oped for municipal landfill sites based
        on their similarities) to help define site
        conditions  and to scope  future  field
        tasks

   •    Conducting limited field investigations
        to  assist in targeting future fieldwork

   •    Identifying clear, concise RI objectives
        in  the form  of field tasks to ensure
        sufficient  data are collected  to ade-
        quately characterize  the site,  perform
        the necessary risk assessment(s), and
        evaluate the practicable remedial action
        alternatives

   •    Identifying data  quality objectives
        (DQOs) that result in a  well-defined
        sampling and analysis plan, ensure the
        quality of the data collected, and inte-
        grate the information required in the
        RI/FS process

   •    Limiting the scope of the baseline risk
        assessment as discussed below

Streamlining the Baseline Risk  Assessment

The baseline risk  assessment may be  used to
determine whether a site poses risks to human
health and  the environment that are significant
enough to  warrant remedial  action.   Because
options  for remedial action  at municipal landfill
sites are  limited,  it  may  be possible to
streamline  or  limit the scope of  the baseline
risk assessment by (1) using the  conceptual site
model  and Rl-generated  data  to perform  a
qualitative risk assessment that identifies the
contaminants of concern in the  affected media,
their    concentrations,  and their hazardous
properties  that may pose  a  risk  through the
various routes of exposure and  (2) identifying
pathways that are  an obvious threat to human
health or the  environment by  comparing RI-
derived  contaminant concentration levels to
standards that  are potential  chemical-specific
applicable or   relevant   and    appropriate
requirements (ARARs) for the  action.  (When
potential ARARs  do not exist for a  specific
contaminant, risk-based chemical concentrations
should be used.)

Where  established  standards for one or more
contaminants  in a  given medium are  clearly
exceeded, the basis for taking remedial action is
generally warranted (quantitative assessments
that consider all chemicals, their potential addi-
tive effects, or additivity of multiple exposure
pathways are not necessary to initiate remedial
action). In cases where standards are not clear-
ly exceeded, a more thorough risk assessment
may be necessary before  initiating remedial
action.

This streamlined approach may facilitate early
action on the most obvious landfill problems
(groundwater and leachate, landfill gas, and the
landfill contents) while  analysis continues on
other problems such as  affected wetlands and
stream sediments. Dividing a site into operable
units and performing early or interim actions is
often desirable for these types of sites.  This is
because performing certain early actions (e.g.,
capping a landfill) can  reduce the impact to
other parts of a site while the RI/FS continues.
Additionally, early actions must be consistent
with the site's final remedy and therefore help
to speed up the clean-up  process.

Ultimately, it will be necessary to demonstrate
that the final remedy, once implemented, will in
fact address all pathways and contaminants of
concern,  not just those  that triggered  the
remedial action. The  approach outlined above
facilitates rapid implementation of protective
remedial measures for the major problems at a
municipal landfill site.

Streamlining Site Characterization

Site characterization for municipal landfills can
be expedited by focusing field activities on the
information needed to sufficiently assess risks
posed by the site, and to evaluate practicable
remedial actions.   Recommendations to help
streamline site  characterization of media typi-
cally  affected  by landfills are discussed in
Section 3 of this report. A summary of the site
characterization strategies is presented below.

Leachate/Groundwater  Contamination

Characterization of a site's geology and hydro-
geology will affect decisions on capping options
as well  as on extraction and treatment systems
for leachate  and groundwater.  Data gathered
during the hydrogeologic investigation are simi-
lar to those gathered  during investigations at
                                              ES-2

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other types of NPL sites. Groundwater contam-
ination at municipal landfill sites may, however,
vary in composition from that at other types of
sites in  that it often contains  high  levels of
organic matter and metals.

L.eachate generation is of special concern when
characterizing  municipal  landfill  sites.  The
main factors contributing to leachate quantity
are precipitation and  recharge from ground-
water and surface water. Leachate is character-
istically high in organic matter as measured by
chemical oxygen demand (COD) or biochemical
oxygen  demand (BOD).  In many  landfills,
leachate  is perched, within the landfill contents,
above  the water  table.    Placing a limited
number of leachate  wells in the landfill is an
efficient  means of gathering information regard-
ing the depth, thickness, and types of the waste;
the moisture content and degree of decomposi-
tion of the waste;  leachate head levels and the
composition of landfill leachate and the eleva-
tion of the underlying natural soil layer. Addi-
tionally, leachate wells provide good locations
for landfill  gas sampling. It should be noted,
however, that without the proper precautions,
Placing  wells  into  the landfill contents may
create health and safety risks. Also, installation
of wells through the landfill base  may create
conduits  through which leachate can migrate to
lower geologic strata,  and the installation of
wells into landfill contents may make it difficult
to  ensure  the  reliability,  of the sampling
locations.
 Hot Spots

 More  extensive characterization activities and
 development of remedial alternatives (such as
thermal  treatment or  stabilization)  may be
 appropriate for hot spots. Hot spots consist of
 highly toxic  and/or highly mobile  material and
 present  a potential principal threat to human
 health or the environment. Excavation or treat-
 ment of hot spots is generally practicable where
 the waste type or mixture of wastes is in a dis-
 crete,  accessible location of a landfill. A  hot
 spot should  be large enough that its remedia-
 tion would significantly reduce the risk posed by
 the  overall  site, but  small enough that it is
 reasonable to consider removal or treatment. It
 may generally be appropriate to consider exca-
 vation  and/or  treatment of the contents of a
 landfill  where a low to moderate volume of
 toxic/mobile  waste  (for example, 100,000 cubic
 yards or less) poses a principal threat to human
 health and the environment.

 Hot spots should be characterized if documen-
 tation and/or physical evidence exists to indicate
 the  presence and approximate location of the
 hot  spots. Hot spots may be delineated using
 geophysical  techniques or soil gas surveys and
 typically  are  confirmed by excavating test pits or
 drilling exploratory borings. When characteriz-
 ing  hot spots, soil samples  should be collected
 to determine the waste characteristics; treatabil-
 ity or pilot testing may be required to evaluate
 treatment alternatives.
Landfill Contents

Characterization of a landfill's contents is gen-
erally not necessary because containment of the
landfill contents, which is often the most practi-
cable  technology  does  not  require such
information, Certain data, however, are neces-
sary to evaluate  capping alternatives and should
be collected in the field. For instance, certain
landfill properties  such as the  fill thickness,
lateral extent, and age will influence  landfill
settlement and gas generation rates, which will
thereby have an  influence on the  cover type at a
site.    Also,  characterization of a  landfill's
contents may provide valuable information for
PRP determination. A records review can  also
be  valuable  in gathering  data concerning
disposal history, thus reducing the need for field
sampling of contents.
 Landfill Gas

 Several gases typically are generated by decom-
 position of organic materials in a landfill. The
 composition, quantity, and generation rates of
 the  gases depend on  such factors  as refuse
 quantity and composition, placement character-
 istics, landfill depth, refuse moisture content,
 and amount of oxygen present. The principal
 gases generated (by volume) are carbon dioxide,
 methane, trace thiols, and occasionally, hydro-
 gen sulfide. Volatile organic compounds may
 also be present in landfill gases, particularly at
 co-disposal facilities.  Data generated during the
 site characterization  of  landfill  gas should
 include landfill gas characteristics as well  as the
 role of onsite and offsite surface emissions, and
 the geologic and hydrogeologic conditions of
 the site.
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Streamlining the Development of Alternatives

Section 4 of this document describes the reme-
dial technologies that are generally appropriate
to CERCLA  landfill sites. Inclusion  of these
technologies is based on experience at landfill
sites and expectations inherent in the NCP. To
streamline the development of remedial  action
alternatives  for landfill contents, hot  spots,
landfill gas,  contaminated groundwater;  and
leachate,  the  following points  should  be
considered:

   •    The most practicable remedial alterna-
       tive for landfills is containment. Such
       containment may  be  achieved  by
       installing  a cap  to  prevent vertical
       infiltration of surface  water.   Lateral
       infiltration of water or gases into the
       landfill  can  be prevented by a peri-
       meter trench-type barrier.   Caps and
       perimeter barriers sometimes  are used
       in combination. The type of cap would
       likely be either a native  soil  cover,
       single-barrier cap, or composite-barrier
       cap. The appropriate type of cap to be
       considered will be based on remedial
       objectives for the site. For example, a
       soil cover  may be sufficient  if  the
       primary objective is to prevent direct
       contact and minimize erosion.  A single
       barrier  or composite  cap  may  be
       necessary where infiltration is  also a
       significant concern. Similarly, the type
       of  trench  will  be dependent on  the
       nature of the contaminant to be con-
       tained. Impermeable trenches may be
       constructed  to  contain  liquids  while
       permeable trenches may be  used to
       collect gases. Compliance with ARARs
       may also affect the type of containment
       system to be considered.

   •    Treatment of soils and wastes may be
       practicable for  hot  spots.  Consolida-
       tion of hot spot materials under a land-
       fill cap is  a potential  alternative in
       cases when treatment is not practicable
       or  necessary.  Consolidation-related
       differential settlements may  be large
       enough  to  require  placement  of an
       interim  cap  during  the  consolidation
       phase.  Once the rate  of settlement is
        observed to decrease, then a final cap
        can be placed over the waste.

   •     Extraction and treatment of contami-
        nated groundwater and leachate may be
        required to control offsite migration of
        wastes.    Additionally,  extraction and
        treatment of leachate from landfill
        contents may be required.  Collection
        and treatment may be necessary indefi-
        nitely because of continued contami-
        nant loadings  from the landfill.

   •     Constructing an active landfill gas col-
        lection and treatment system should be
        considered  where (1)  existing or
        planned homes or buildings may be
        adversely affected through either explo-
        sion or inhalation hazards, (2) final use
        of the  site includes allowing public
        access, (3) the landfill produces exces-
        sive  odors, or (4) it is necessary to
        comply  with ARARs.  Most landfills
        will  require  at  least  a  passive gas
        collection system (that is, venting) to
        prevent buildup of pressure below the
        cap and to prevent damage to the  vege-
        tative cover.

Conclusions

Evaluation  and selection  of appropriate
remedial  action alternatives  for  CERCLA
municipal  landfill  sites is a  function  of a
number of factors including

   •     Sources and pathways of potential risks
        to human health and the environment

   •     Potential ARARs for the site (Signifi-
        cant  ARARs  might include RCRA
        and/or state closure requirements, and
        federal  or state requirements pertaining
        to landfill gas emissions.)

   •     Waste characteristics

   •     Site characteristics (including surround-
        ing area)

   •     Regional surface water  (including wet-
        lands) and groundwater characteristics
        and potential uses
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Because  these  factors  are  similar for many
CERCLA municipal landfill sites, it is possible
to focus  the  RI/FS and selection of remedy
process. In general, the remedial actions imple-
mented at most CERCLA  municipal landfill
sites include:

   •   Containment of landfill contents (i.e.,
       landfill cap)
   •    Remediation of hot spots

   •    control and treatment of contaminated
       groundwater and leachate

   •    Control and treatment of landfill gas

Other  areas  that  may require remediation
include surface waters, sediments, and adjacent
wetlands.
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                                         Section 1
                                  INTRODUCTION
Approximately 20 percent of the sites on the
National Priorities List (NPL) are landfills
where a combination of principally municipal
and to a lesser extent hazardous wastes have
been co-disposed. Because these sites typically
share similar characteristics, the   Superfund
Program anticipates that their remediation will
involve similar waste management approaches.

EPA has established a number of expectations
pertaining to the remediation of CERCLA sites
and has  listed  them in the National Contin-
gency Plan (NCP). One of these expectations,
which is particularly relevant to municipal land-
fills, states that engineering controls such as
containment will be used for waste   that poses a
relatively low  long-term threat or for sites
where treatment is. impracticable. The  pream-
ble to the NCP identifies municipal landfills as
a type of site where treatment may be impracti-
cable due to the size and heterogeneity of the
contents  of many  landfills.   Because  of this
expectation, the containment alternative should
be developed in the detailed analysis, and will
often be the appropriate  response  action for
CERCLA municipal landfill sites based on the
nine criteria.  However, other alternatives such
as leachate recirculation or "flushing" of landfill
contents  may be appropriate for certain situa-
tions and if determined to be practicable should
not be discounted.

A second NCP expectation slates that principal
threats (e.g., highly mobile and/or highly toxic
waste) will be treated, if practicable. Treatment
of hot spots within a landfill may be considered
practicable when:  (1) wastes are  in discrete,
accessible locations of a landfill and present a
potential principal threat to human health and
the environment arid (2) a hot spot is  large
enough that its remediation will significantly
reduce the risk posed by  the  site, but small
enough that it is reasonable to consider removal
and/or treatment. Characterization of hot spots
to determine if treatment is practicable should
be performed when there is either documenta-
tion  or physical  evidence  (e.g.,   aerial
photographs)  indicating the  approximate
location of hot spots.
Other expectations in the  NCP that may be
relevant to the remediation of municipal land-
fills are summarized below.

  •   A combination of engineering controls
      and treatment will be used as appropri-
      ate  to  achieve protection of human
      health and the environment. An exam-
      ple would include  treatment of hot spots
      in conjunction with containment (cap-
      ping) of the landfill contents.

  •   Institutional controls such as access and
      deed restrictions will be used to supple-
      ment engineering controls as appropri-
      ate, to  prevent exposure to hazardous
      wastes.

  •   Groundwaters will be returned to bene-
      ficial uses whenever practical, within a
      reasonable  time,  given the particular
      circumstances of the site.

  •   Innovative technologies will be consid-
      ered when  such technologies offer the
      potential for superior treatment perfor-
      mance  or lower costs for performance
      similar to   that of demonstrated
      technologies.

The similarity  in landfill characteristics and the
NCP expectations  make it possible to stream-
line the RI/FS process for municipal landfills.
By streamlining the RI/FS process EPA  will
(1) improve the efficiency and effectiveness of
decision making at these sites; (2) provide for
consistency among the  Regions in their
approach to conducting an RI/FS and selecting
remedial  actions,   and  (3)  facilitate  more
effective remedial designs.

In direct response to the need to develop tools
and  methodologies  to  streamline  the  RI/FS
process for different site types (Recommenda-
tion No.  23 in the  Superfund Management
Review Implementation Plan),  the  Office of
Emergency and Remedial Response  has devel-
oped this document which (1) provides informa-
tion and tools to assist in scoping an RI/FS,
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(2) defines    appropriate    strategies   for
characterizing media typically  impacted by
municipal landfills, (3) identifies a strategy for
simplifying the baseline risk assessment (thereby
allowing for early  action at these sites), and
(4) identifies the  most  practicable  remedial
action alternatives for addressing these types of
sites.
  1.1  Background On Municipal
                Landfills

CERCLA municipal landfill sites are unique in
both their size and composition. The  landfills
currently on the NPL range in size from 1 acre
to 640 acres, while most are facilities where a
combination of principally municipal  and to a
lesser extent hazardous wastes have been co-
disposed of. Municipal wastes  disposed of in
these landfills typically  includes a heterogeneous
mixture of materials  primarily composed of
household refuse such  as yard and food wastes
and paper, and commercial waste  such as plas-
tics, inert mineral waste, glass,  and metals.
There are  four ways in which hazardous  wastes
may have been disposed of in municipal land-
fills. First, landfills that  operated  before the
implementation  of RCRA on  November 19,
 1980, typically accepted and co-disposed of both
liquid and solid hazardous waste. Second, small
quantity generators contribute varying quantities
of  hazardous wastes  to  municipal landfills.
Small  quantity generators are those that pro-
duce no more than one kilogram  per month of
designated acute hazardous waste or  no more
than 100 kilograms per month of all other haz-
ardous wastes combined (see 40  CFR 261.5).
Third,  some household wastes such  as batteries
and paints are  hazardous.  And fourth, bio-
degradation of wastes within the landfill can
create new compounds that are hazardous.

The dynamics  within a landfill create  an
unknown  and changing environment. Microbial
degradation of the municipal solid  waste occurs,
in  addition to  various unknown interactions
between hazardous  and municipal solid wastes.
Microbial de-gradation of municipal solid waste
is a dynamic process that occurs for an indefi-
nite period of time after waste has been placed
within a  landfill.   Microorganisms  naturally
occurring in the soil and refuse biodegrade the
wastes in distinct stages; each stage of degrada-
tion creates different byproducts.

Landfills can react with the environment in a
number of ways. One type of interaction occurs
when precipitation and/or liquid wastes dis-
posed of within the landfill percolate through
the  landfilled mass to form a liquid called
leachate.  Leachate may enter the  subsurface
soils and groundwater  or  be discharged to
nearby surface waters and wetlands  from
groundwater or  seeps.  The amount of leachate
formed from a landfill is a function of (1) the
amount of precipitation in the area,  (2) the
types of materials disposed of in the landfill,
(3) the  design, size, age, and initial moisture
content of the landfill,  and (4) the permeability
and porosity of landfilled materials and the soil
used to cover the landfill. The characteristics of
landfill leachate depend upon factors  such as
initial concentrations of compounds, solubilities,
and vapor pressures, rates at which compounds
are transformed  by microbial and chemical pro-
cesses  within the  landfill, and  the physical
characteristics of the landfilled materials. The
transport and fate of leachate in the subsurface
environment is a function of the landfill design
and  the characteristics  of the underlying soil
types.

A second way  in which landfills  can interact
with the environment  is through discharge to
nearby surface  waters and wetlands. As men-
tioned previously, leachate may be discharged
from seeps to  local surface waters and wetlands
or  contaminated groundwaters may recharge
these media.    The most direct contribution
however, is often through stormwater runoff.
Runoff from a landfill may be voluminous but
the contact time with  the landfill materials is
often limited.

A third type of interaction between landfills and
the environment is through airborne emissions
of gases and vapors. Some of the volatile com-
pounds emitted from landfills arc those present
in the landfill as it is being filled, while  others
are generated  by  microorganisms  as  they
degrade the wastes in the landfill. The princi-
pal airborne emissions (by volume)  associated
with landfills are methane and carbon dioxide.
These gases are the result of anaerobic micro-
bial degradation  of municipal solid wastes.
 Other volatile compounds often emitted from
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CERCLA landfills include halogenated hydro-
carbons, simple alkanes, vinyl chloride, benzene
and other aromatic compounds, and mercep-
tons. The principal factors affecting the type of
air emissions include (1) the type of materials
disposed of in the landfill,  (2) the age  of the
landfilled refuse, (3) the  type  of cover over-
laying the landfilled wastes,  (4)  the presence or
absence of a gas extraction  and treatment sys-
tem, (5) subsurface gas migration, and (6) the
presence    of  underground/subsurface   fires.
Barometric pressure and wind speed and direc-
tion also play an important role  in the affects to
potential  receptors.
    1.2  Document Organization

This document is organized into six sections.
The first section is this  introduction,  which
includes the goals and objectives of this project
as well as a summary of municipal landfill char-
acteristics  and their potential  impact on the
environment. Section 2 describes the activities
necessary to adequately scope  an RI/FS for a
landfill site and provides a number of tools to
assist in  scoping.   The third section describes
site characterization strategies  for co-disposal
facilities that either have or do not have sus-
pected hot spots.    Section 4 of  this report
describes the  remedial technologies that are
appropriate for CERCLA  landfills, including
the data requirements to adequately evaluate
them. Section 5 includes an analysis of the nine
criteria used to evaluate practicable technolo-
gies  and  summarizes basic conclusions that can
be made for each technology in light of each of
the  evaluation criteria.     The final  section
describes appropriate remedial alternatives that
have been developed for  an example municipal
landfill site and presents  an evaluation of these
alternatives. The purpose of this section is to
illustrate how technologies might be combined
to form  alternatives  typically developed for
landfill sites and how these are evaluated using
the nine  criteria.

Additionally, scoping activities, and an appro-
priate site characterization strategy, have been
identified for the example site and included as
Appendix A to better illustrate some  of the
concepts presented in this document. Appendix
B of this document contains an historical record
of the  remedial actions selected for CERCLA
municipal landfill sites through FY  1989.
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                                         Section 2
   SCOPING THE RI/FS  FOR MUNICIPAL LANDFILL SITES
Developing  a work  plan  is the first step in
conducting an RI/FS at a municipal landfill site.
The  process  of developing a comprehensive
scope of work to be defined in the work plan is
known as scoping, and has several functions. It
identifies the  preliminary remedial action alter-
natives, summarizes  the RI/FS objectives,  and
outlines the  tasks necessary  to meet these
objectives.     Because the  work plan is  the
foundation of the  RI/FS, the remedial project
manager (RPM) should devote considerable
attention to  preparing  it  and the  individual
tasks. Without  a definition of a proper work
plan, it is unlikely that the RI/FS or the project
objectives will be met because it" is difficult to
achieve  loosely  defined RI/FS or  project objec-
tives that  extend over  a long time. It should
also  be recognized that  adjustments should be
made to the work plan  as work  on the RI/FS
progresses and more  is learned about the site.

A primary purpose of scoping an RI/FS, there-
fore, is  to divide the broad project goals into
manageable tasks that can be performed within
a reasonable  period  of  time. Proper planning
also  provides the RPM  with a mechanism  for
measuring progress and controlling the project.

The  broad  project goals for an  RI/FS at  any
Superfund site  are to provide the information
necessary  to  characterize  the site, define  site
dynamics, define risks; and develop a remedial
program to  mitigate or.  eliminate  potential
adverse  human health and  environmental
impacts. The tasks that should be performed to
achieve these goals include the following:

  •    Evaluate  existing site data (Section 2.1)

  •    Conduct a site visit (Section 2.3)

  •    Conduct a limited site investigation, as
       necessary  (Section  2.4)

  •    Define  the  conceptual site  model
       (Section 2.5)

  •    Scope the risk assessment (Section 2.6)
  •    Identify preliminary applicable or rele-
       vant and appropriate  requirements
       (ARARs)

  •    Develop preliminary  remedial action
       objectives and goals (Section 2.7)

  •    Develop preliminary remedial  technolo-
       gies (Section 2.8)

  •    Develop   objectives   of  the  RI/FS
       (Section 2.9)

  •    Develop data quality objectives (DQOs)
       (Section 2.10)

  •    Prepare  an RI/FS  work plan  and
       sampling and analysis plan

  •    Prepare a health and safety plan

  •    Prepare a community relations plan

  •    Conduct Phase I site investigations

  •    Evaluate Phase I data

  •    Refine  remedial action alternatives

  •    Conduct Phase II  site  investigations, if
       necessary

  •    Evaluate remedial  action alternatives

The scope of work for a municipal landfill site
may be different from the  scopes for other  types
of sites, such as surface impoundments, waste
piles, and tank farms. Because waste in munici-
pal landfills is  a heterogeneous mixture of mate-
rials and may contain liquid and solid hazardous
wastes, the number of remedial action alterna-
tives is limited. Therefore, site-characterization
strategies that  can be used at municipal landfill
sites are  limited.   The specific strategies for
characterizing different types of landfill sites are
presented in  Section 3  of this  report.  This
section focuses on the components of scoping
an RI/FS for municipal landfill sites.
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  2.1  Evaluation  of Existing  Data

 Existing data should be reviewed and evaluated
 before  any other  activities  are  performed, so
 that the site dynamics can be understood and
 the scope of the RI can be adequately prepared.
 Thorough data evaluation is important because
 it affects both the timing and cost of the RI/FS.
 The evaluation also  identifies the needs  and
 objectives of any limited field investigation, the
 selection of preliminary remedial action alter-
 natives, the RI/FS objectives, and the develop-
 ment of the DQOs.

 To begin understanding site dynamics and scop-
 ing the RI, sources of existing data should be
 identified  and the data should be  compiled.
 Information  on the  area's  hydrology and
 geology should be  collected so that contaminant
 pathways can  be identified.  Types and sources
 of hazardous materials in the landfill should be
 determined, where  possible. In addition, regula-
 tory activities should be reviewed, including
 information on any existing  landfill cover.
 Finally, the results  of past sampling and analysis
 efforts should  be evaluated for their usefulness.

 If, after existing data are evaluated, it is deter-
 mined that there is insufficient, information to
 define site dynamics and  to develop the concep-
 tual  site  model, limited field  investigations
 should  be conducted. Limited field  investiga-
 tions  are performed during scoping, and should
 be limited to easily obtainable data  for which
 results  can be received in  a short period of
 time.    The existing data,  together with the
 results of any limited field investigations, should
 then be used  to construct the conceptual  site
 model and to develop the preliminary remedial
 action alternatives and the RI/FS objectives.

 2.1.1  Sources  of Information

 Federal, state, and local agencies may have
 pertinent information for evaluating a  site.
Although some of this  information may be
general, it still can be used to establish a base-
 line.    A an  example,  records of previous
 ownership may indicate that there were manu-
 facturing operations at a site. Exact locations
of buildings may not be available, but  the
materials used  in manufacturing  operations
could  suggest   that additional   analytical
 parameters be tested.   In addition to govern-
 ment sources, other data sources that may be
 particularly useful in  obtaining more specific
 information on a site include:

   •    Preliminary assessment/site inspection
       data

   •    MRS scoring package

   •    Potentially responsible  party  (PRP)
       search report

   •    Aerial photographs

   •    State files, including inspection reports,
       permit applications, and well data bases

   •    Interviews with state  inspectors, local
       government bodies, and local residents

   •    Site history,  ownership,  operation/
       disposal practices  (past  and present,
       from  past owners,   operators,  or
       generators)

   •    Weight tickets/logs

   •    Data from original siting studies  or
       engineering designs

   •    Closure plans

 Information available from other agencies and
 the types  of  information  generally  available
 from other potential data sources are summa-
 rized in Table 2-1  of Guidance for Conducting
Remedial Investigations and Feasibility Studies
 Under CERCLA (U.S.  EPA 1988d). Appendix
 B of this  document provides information on
 technologies most frequently implemented at
 municipal  landfill sites based on a review of
 RODS signed through 1989.

 Existing data should be evaluated and summa-
 rized in formats that  are  easily  reviewed by
 individuals not involved in  the  collection
 process. Reviewing and evaluating the  available
 data will lead to an understanding of the site
 conditions  and  identification  of evident data
 gaps. During this  activity,  the quality (that is,
 accuracy and  precision)  of the data and their
 conformance  with the quality  control  (QC)
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protocols under  which they were  collected
should be assessed. If possible, preliminary data
(e.g., condition of cap) should be confirmed by
onsite observations.

2.1.2 Types of Data and Data Quality

At this early stage, it is important to focus on
compiling as much  information as possible
about the site's characteristics and hydrogeolog-
ical  setting. Although the complete set of
desired information is not always available or of
good quality, it is important to gather all that is
available. This  information includes:
       The  landfill's condition, especially its
       slope stability, the presence of under-
       ground fires, levels of methane gas, and
       amount of cover

       Areas  of  suspected  contamination,
       unusual  surface  patterns,  or unusual
       surface features (for example, mines)

       Boundaries of areas of suspected con-
       tamination

       Depth to groundwater  and  seasonal
       fluctuations

       Existing site conditions,  such as recent
       construction of neighboring  houses

       Site  and property boundaries and land-
       fill depth

       Existing residential,  municipal,  and
       industrial wells, including construction
       and analytical  data

       Details of landfill construction, such as
       drainage channels, clay liners, cap con-
       struction (full or partial), facility base
       grades, present engineering controls (if
       any), and any current landfill gas venting

       Evidence of leachate  seeps,  contami-
       nated surface water runoff,  or other
       spread of contamination

       Nature of the soils  around and  under
       the landfill (for example, permeability,
       composition, clay,  organic content)
  •    Nature and characteristics of material in
       the landfill, particularly chemical com-
       position of hazardous waste

  •    Nature of disposal practices (If wastes
       were  segregated,  locate  potential hot
       spot areas).

As part of this compilation, data quality should
be evaluated to determine the uncertainty asso-
ciated with the conclusions drawn from existing
data and their usability. Uncertainty about the
adequacy of existing data can arise from two
sources: the representativeness or the specific-
ity of the sampling techniques used to collect
the data,  and the validity of the analytical meth-
ods used.  The representativeness of data can be
assessed by reviewing their sources. The ratio-
nale  and  method of sample collection should be
determined. The analytical methods should be
reviewed to determine if the analyses are appro-
priate to the RI/FS objectives. Data validation
identifies  invalid data and  qualifies the usability
of the  remaining data. Formal data validation
procedures are used to identify data that are the
result  of improper  analytical procedures.
QC information, if available, can be reviewed to
assess the validity of the analyses. The usability
of data without QC information can sometimes
be assessed by using statistical techniques or by
using professional judgment. Statistical tech-
niques can be used to judge whether the  data
are consistent by examining their distribution.
Data values that are exceptional may be suspect
and should be verified with additional samples
of known quality.  Additional information on
the statistical evaluation of data can be found in
Statistical  Methods for Evaluating the Attainment
of Superfund Cleanup Standards,  Volume I: Soils
and Solid Media (U.S. EPA, 1989a).

Other  information that is not classed as valid
because of QC restrictions can be used in estab-
lishing a hypothesis about contaminant behavior
over time. These data generally should not be
used in making final decisions about the need
for cleanup, but they can help in developing an
understanding of site  dynamics, sampling
strategies for the RI, and preliminary remedial
action  alternatives.    Factors  that must be
considered in  evaluating the  data  for  their
usefulness are:
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  •     The age and comparability of the data
       sets.  Standard methods of sample col-
       lection and analysis may. change over
       time; thus, sample results may not be
       directly comparable.

  •     The existence  of replicate sample data
       for estimating precision.

  •     The sampling design used to collect the
       samples (for example, were both upgrad-
       ient and downgradient wells located at
       the  landfill for  the  collection of the
       groundwater samples?).

  •     The methods used to  collect, preserve,
       handle, and transport the samples.

  •     The analytical  methods used to estimate
       pollutant concentrations  (for example,
       does the  analytical  method provide
       results that can be used for risk assess-
       ment, or is its usefulness  limited to site
       characterization?).

  •     The length of time samples were held
       before  analysis  (for example, volatile
       organic analysis has a 14-day allowable
       holding time or a 7-day holding time
       when not preserved with acid).

  •     The published sensitivity or detection
       limit of  the  analytical  methods (for
       example,  is the detection limit higher or
       lower  than   the  chemical-specific
       ARAR?). The detection limit should be
       lower than both the chemical-specific
       ARARs  and  appropriate  risk-based
       concentrations.

  •     The quality control measures used  by
       field and  laboratory teams (for example,
       were blank samples used to determine if
       samples  were   contaminated  during
       collection or analysis?).

The assessment of data reliability should also
extend to the entire site investigation process.
The rationale  for  selecting the sampling loca
tions and for determining the completeness of
the sampling should be  evaluated.    The
sampling plans and methods, if available,  should
be reviewed for aspects of the site useful for
determining the RI/FS objectives,
An important part of reviewing and evaluating
the available data is assessing their reliability,
that is, the extent to which the data represent
site conditions. The dates of maps, drawings,
and plans should be checked. Sampling loca-
tions should be evaluated for representativeness.
Analytical data should be checked against inter-
nal laboratory and source  QC criteria (blanks,
duplicates, spike/recovery), and the methods of
sample collection, preservation, handling, and
sampler decontamination should be examined
for potential irregularities.  If more than one
laboratory tested samples from the same area
on the site, the results should be assessed for
consistency,  and variations in methodology
should be identified.

The level of effort to review the  data quality
may be significant if large amounts of potential-
ly high quality data are available. More typical,
however, is the case where some  analytical data
are low or unknown quality and will be used
only in the development of the initial site conc-
eptual model  and  initial  sampling planning
activities. In this case, data quality review may
not require a significant  level of effort.

2.1.3 Presentation of Available Data

Whenever possible, the available data should be
summarized in graphs, tables, or matrices. Data
can also be presented as isoconcentration maps
for parameters that depict the degree and extent
of  contamination for  the various media  or
hydrogeologic  units.  These compact formats
allow for efficient presentation, comparison, and
use of large  amounts  of  data.    A  written
summary is also valuable for conveying data
trends and general conditions. All summaries,
whether  graphic, tabular,  or written,  should
identify both what is known (conditions at the
site) and  what  is  not known (evident data gaps).
   2.2  Existing  Data Evaluation
          Results  and  Report

The evaluation of existing data should result in
the preparation  of a  preliminary  base map,
geologic cross sections, a hydrology summary,
preliminary  waste characterizations,  and a
summary of sampling activities and  results.
Figure 2-1 presents a flow diagram for gathering
                                              2-4

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Obtain Available Data
• Background Data
- Facility Description
- Past Operaton and
DisposalPractices
- Regulatory History
- Physiography/
Topography
- Soils / Geology
- Climate / Weather
- Surface Water
- Groundwater
- Ecology / Land Use
- Sensitive Receptors
• Agency Data
- HRS
- PA/SI
- Chronology of
Agency Involvement
- Existing Permits
- Closure Plans
- Abatement Orders


Review and Evaluate Available Data
^ Prepare Site Description, Site History
^^ Summary Maps, lables, Malrices ^*
Data Quality Evaluation
Figure 2-1
FLOW DIAGRAM FOR
T^ATA T7WA T TTA TT<~»XT A XTT\ DT3T7D A T> A TT<~»XT
1 	 ^-






Prepare Preliminary Base Map
• Underground / Overhead Utilities
• Availability of Water and Electrical Hookups
. Nearby Structures and Residences
. Areas and Locations of Known or
Suspected Hot Spots
. Limits of Waste, if Known
. Location of Known Potential Hazards
. Property Lines/ Boundaries
. Access / Security
. Topography / Vegetation
Drainage Features
. Landfill Location / Size
. Buildings / Structures / Piping
Existing Wells and Sampling Locations

Prepare Preliminary Geologic Cross Sections
. Ground Surface Features
. Soil Horizons
. Major Geologic Units
. Location of Existing Borings, Wells, and Test Pits
. Sample Locations/ Analytical Results
. GrounwaterTable
Prepare Hydrology Summary
Location of Surface Water Bodies
Seasonal Surface Water Fluctuations
Surface Water Level Measurements
. Depth to Groundwater
. Visable Leachate Seepage
. Groundwater Flow Directions and Gradients
Recharge and Discharge Areas
. Identification of Class I and II Aquifers
. Well Survey

Prepare Waste Characterization Summary
Sources, Types and Qanlities of Waste Disposed
Disposal Periods

Prepare Sampling Activities Results Summary
. Data of Study
. Firm Responsible for Study
. Name and Address of Laboratory
. Media Samples
. Analytes Tested and Analytical Method
. Evaluate Useability of Data

-------
evaluating, and preparing data for an RI/FS at a
municipal landfill site.

Inadequate data review during this stage of the
RI/FS can result in a misdirected focus of the
study, which may cause the collection of unnec-
essary samples, an escalation of field investiga-
tion costs, and/or project delays. As an exam-
ple, inadequate data review  during scoping to
determine the need for treatability  studies for
leachate/groundwater or landfill hot spots may
result in project delays and increased costs.

2.2.1 Site Description

The site description should  provide accurate,
detailed, and current information on the site, A
physical description of the  site and.  its  sur-
roundings and a preliminary base map should
be prepared, Data in the hazard ranking system
(HRS)  scaring  package  and the  preliminary
assessment/site  inspection (PA/SI)  should
provide some of the  basic  information.  The
base map should include:

  •     Surface water drainage patterns and site
        discharge locations

  •     Locations of existing residential, munici-
        pal, and industrial wells, and surface
        water intakes

  •     Presence of wetlands/floodplains, wild-
        life habitats, scenic rivers, and historical
        archeological resources

  •     Onsite and offsite buildings, structures,
        and piping, including existing landfill gas
        extraction equipment

  •     Area and site topography and vegetation

  •     Underground and overhead utilities in
        the vicinity of the site (All utilities that
        could possibly  impact geophysical sur-
        veys   should  be  identified  during
        scoping.)

  •     Availability of water,  sewer,  phone, and
        electrical hookups for the site

  •     Nearby structures, residences, and other
        land uses
  •    Previous sample locations

  •    Known or suspected hot spots

  •    Locations  of  potential  hazards  (for
       example, hazards due to falls, heavy-
       equipment operation  areas,  electrical
       power lines)

  •    Areas of active landfilling operations

  •    Property lines, facility and refuse bound-
       aries

  •    Access and security (for example, roads,
       fences, gates)

The site map should differentiate between the
site boundary (the area of the landfill) and the
property boundaries (total area of the property
may not necessarily be used as a landfill). The
preliminary base map can be developed from
existing site maps, aerial  photographs, or a
topographic  survey.    EPA's Environmental
Photographic Interpretation  Center (EPIC)  in
Warrenton, Virginia, can provide a wide range
of information on a site, such as:

  *    Aerial photographs  and analysis for a
       single date

  •    Aerial photographs  and  analysis over
       time  either for the  site itself or for a
    .   wider area  (historical analysis)

  •    Topographic  mapping at 1-foot to 5-foot
       contour intervals

  •    Orthographic mapping, which  is a recti-
       fied photoimage  with a  superimpose
       topographic map"

Existing figures, photographs, and maps may  be
useful sources of historical information but
should  not be relied  on for  information on
current site conditions.  A  fly-over of the site
may  be necessary  to obtain current  aerial
photos and/or to conduct a topographic survey.
If a subcontractor must  be procured for this
activity, it may have to be delayed until the RI
fieldwork is conducted.
                                               2-6

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As mentioned above, the site description should
include the areas, if any, of active landfilling
operations; locations  selecled for sampling or
well installation should consider the impact on
the site's normal  operation and  maintenance.
Meteorologic data should also be collected and
considered during the  development of the work
plan. Meteorologic data can be used to deter-
mine appropriate times for site visits, to direct
sampling efforts,  and to evaluate remedial
action alternatives, such as incineration,  cap-
ping, or grading. Barometric pressure data are
also useful for interpreting landfill gas volume
collection data.

2.2.2 Site History

The  site history section  should detail,  in
chronological order,  the history of previous
regulatory actions, disposal activities, types and
quantities  of  wastes,  previous owners  or
operators,  site  uses,  and  site  engineering
studies. Significant effort should be expended
in detailing the specifies of disposal activities
and  of types and quantities of wastes.   Site
records and interviews with nearby residents
and former site operators are valuable sources
of this information.

The history of previous disposal  activities at a
municipal landfill often directly affects the RI
objectives,  specifically the need to determine
whether hot spots may  be present  and worthy of
investigation.   In addition  to  investigating  a
potential principal threat, the contents of hot
spots are important for associating PRPs  with
the site, Identifying the chemical components
may aid in identifying the sources of the waste
in the hot spots.

A brief history of operations  at adjoining or
nearby facilities  and  other relevant environ-
mental contamination at or near the site should
also  be included.     These potential  offsite
sources of contamination should be considered
during the development of the work plan. They
may affect the choice  of sampling and monitor-
ing well locations  and may contribute contami-
nation to various media.  Multiple sources of
contaminants in the vicinity can make it diffi-
cult to identify all PRPs.
2.2.3     Regional  and  Site Geology and
Hydrogeology

In addition to the preliminary site base map,
preliminary geologic cross  sections should be
developed,  if possible, to  provide  a  three-
dimensional overview of soils and geology and
the possible extent of soil and groundwater con-
tamination  at the site.   The purpose  of this
effort is to identify any  changes or correlations
in the type and movement of contamination and
soil types and structure. This information will
be used to:

  •    Estimate the  depth of the landfill

  •    Estimate the  depth to groundwater

  •   Identify  the   limits  of subsurface
       sampling programs

  •    Select appropriate  soil  sampling  and
      drilling methods

The preliminary  soil/geologic cross-section can
be developed from existing  site maps, soil and
geologic publications, reports on soil borings
and monitoring well  installation, and analytical
results  of  soil  sampling  and  groundwater
sampling, if available.   A  suggested type of
cross-section is shown  in Figure  2-2. Features
shown on  a cross section of this type  should
include:

  •    Ground surface  features (for  example,
       buildings, above-ground tanks, roads)

  •    Soil horizons (for example, clay  lenses
       or other soil  layers with differing char-
       acteristics)

  •    Major geologic units

  •    Locations  of domestic  and/or  public
       supply wells

  •    Locations of  existing borings, wells, and
       test pits

  •    Existing sample  locations, including the
       location of offsite sampling locations to
                                              2-7

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                      Note: Vertical scale is exaggerated
60
                                                                                                                           Truck
                                                                                                                           Storage
                                                                                                                        /^ Building
                                                                                                                        f               Office
                                                                                                                        \	
                                                             0&O&&OOOOOOO&O
40
20
                           -100
                           Legend:
                                                                                                                                                -   -20
                                                                                                                                                _  -40
                                                                                                                                                    -60
                                                                                                                                                    -80
                                                                                                                                                   -100
                                    Loam, organic materiat with silt and clayey layers locally
                                    Gray-green silt with trace fine sand
                                    Fine-to-coarse sand
                                    Glacial till
                                    Bedrock
                             Note:  Numbers listed at different depths for each represent total organic vapor content
                             in ppm as measured by OVA headspace analysis; WD means none detected.
                                                                                                                                                     Figure 2-2
                                                                                                                    TYPICAL SO1UGEOLOGIC CROSS SECTION
                                                                                                               OF MUNICIPAL LANDFILL AMD ADJACENT AREAS

-------
       determine whether offsite contamination
       is a problem in the area

  •    Depth to groundwater

If no soil borings, test pits, or  monitoring wells
have been installed at the site, it may not be
possible to construct  a  detailed preliminary
cross section. However, geologic and soil publi-
cations—such  as United States Geological
Survey (USGS) reports, Soil  Conservation
Service data, state geological survey reports,
state well databases, logs of public supply com-
panies, and  information  from local well
drillers-should be available to give an estimate
of the  thickness of  unconsolidated material, the
depth  to the  groundwater table, and  current
aquifer uses (e.g., agricultural,  drinking water).

If sufficient information from these sources is
available, this section should  also identify the
origin, texture,  and distribution of unconsoli.
dated materials; the origin, texture, nature,  and
distribution of bedrock units;  and the  texture
and classification of surficial soils. In addition,
if available,  this section  should  identify rock
type, porosity (primary and secondary), areal
extent  of geologic units, and structural geology.
This information can  help identify complex
hydrogeological units and define recharge  and
discharge zones and flow systems.  The regional
and site-specific geology are described in  this
section to help identify contaminant pathways
and develop a conceptual  site model.

2.2.4 Hydrology

Collection and  evaluation of hydrologic data
should include both surface water and ground-
water components.

2.2.4.1 Surface Water

Surface water bodies near the site  should be
identified to (1) evaluate the  potential impact
of the  landfill on the body of water, (2) under-
stand  the  relationship,  if any,  between  the
surface water and groundwater flow at the site,
and  (3) determine their  potential to be  dis-
charge locations for treated leachate and surface
runoff from the capped landfill.

Groundwater flow may be affected by seasonal
surface water fluctuations  and may either
discharge to surface water or be recharged by
surface water at different times of the year.
This information may be identified by compar-
ing concurrent groundwater and surface water
level measurements taken seasonally. Prelimi-
nary  information  for groundwater  can  be
obtained  from USGS hydrogeologic atlases,
state aquifer maps or water resource overlays,
the local board of health, water control board,
planning commission, or the local Department
of Public Works.

2.2.4.2 Groundwater

A groundwater assessment should be performed
at and near  the site  to  determine depth to
groundwater,  local  and regional groundwater
flow directions, gradients, recharge areas,  dis-
charge areas,  and to identify  aquifers used by
private and public water supply wells in the
area. This information may be determined' by
evaluating the data gathered for the section on
regional  and  site-specific  geology  (Section
2.2.3).    If no  monitoring wells  have been
installed at the site, it may not be possible to
assess  specific groundwater levels or local flow
directions at the site. However, geologic publi-
cations, as mentioned  in Section 2.2.3,  should
be able to give an estimate for the region of the
depth to the groundwater table.

If possible, a well survey should also be initiated
during scoping. This survey can serve a number
of purposes, including evaluating the "usability"
of existing wells for future field activities  and
accounting for pumping influences when select-
ing additional  sampling locations for monitoring
wells.   This  survey would also be useful  for
identifying potentially contaminated wells being
used as  domestic, municipal,  or industrial
supplies.  Well installation logs, if available,
may  be  useful in  preparing geologic cross
sections.

2.2.5 Waste Characterization

The types and quantities of wastes within the
landfill are estimated during waste characteriza-
tion. This information can be developed from
landfill disposal records; county, state, and EPA
records;   interviews   with   current/previous
employees of the landfill;  aerial photographs;
results of sampling landfill contents; and inter-
views with state inspectors.   If available, the
                                               2-9

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periods of disposal should also be estimated to
help identify the likelihood that contaminants
will be in the landfill (for example, volatile
organics sometimes migrate quickly and may
not be present) and to establish PRP responsi-
bility. Although interviews and records searches
are time-consuming, the information gathered is
very useful in directing the RI/FS process and
the selection of remedial action  alternatives.

2.2.6 Sampling Activities and Results

A summary  of the chemical  analytical data
collected at or near the site may provide exten-
sive information about the potential effects of
the site on the  surrounding media and about
future data needs.  This section addresses  the
affected media  at the site, not the  sources,
which are addressed under "Waste Characteriza-
tion"  (Section 2.2.5). The summary of sampling
activities and results should include the date of
the study, the name of the firm  responsible for
the study, the name and address of the labora-
tory that  performed  the  analysis,  the  media
sampled, the analytes, and the analytical meth-
ods used.

The usability  of the data should be evaluated as
discussed in Section 2.1.2, bearing in mind that
there are several data uses (for example, site
characterization,  evaluation of alternatives, PRP
determination) that  require different qualities of
data.  The existing  chemical analysis informa-
tion (including  QC  information)  should  be
included in an appendix of the work plan.
             2.3  Site  Visit

A site visit by  the RPM and other appropriate
personnel (e.g., state and Federal agency repre-
sentatives) is  necessary  during  the  scoping
process to:

  •    Verify existing data (for example, condi-
       tion of cap, amount of soil cover, extent
       of slope erosion)

  •    Identify  existing  site  remediation systems
       (for example, landfill gas or  leachate
       collection  systems)
  •    Identify critical areas (for example, pos-
       sible equipment-staging  areas,  access
       roadways, residential areas)

  •    Visually characterize wastes (for exam-
       ple,  leachate seeps,  exposed  drums,
       stained soils)

  •    Gather  additional  data to  support
       further  site  evaluation  (for example,
       wetlands, floodplains, biota)

  »    Evaluate the practicability of geophysi-
       cal surveys

Detailed  examination of a  municipal  landfill
during  a site  visit is  important for  several
reasons.   Observation  of slope instability or
explosive levels of gas may indicate  the need to
mitigate an immediate  hazard.  Details  of cap
construction  may  affect  the  feasibility  of
remedial  technologies.  Remedial technologies
that use heavy equipment can also be removed
from  consideration by soft ground  surfaces or
other  conditions limiting access to the landfill.

Characterization of waste materials by visual
observation  is also important. Visual identifica-
tion of hot spots or the physical characteristics
of the wastes (sludge-like or solid) is necessary
for sampling preparation and for ensuring the
representativeness of sampling.  The physical
and chemical characteristics of the waste are
key variables in defining alternative technolo-
gies for remedial actions and in identifying the
most  cost-effective  actions.  Special  wastes
(radioactive, laboratory packs, etc.) not normal-
ly associated with municipal landfills may also
be  at the site and should be noted  during the
site visit.  However, the certainty of information
gathered by visual observation during the site
visit is limited. Ideally,  a site should be visited
when  vegetation is minimal.  Potential sampling
locations should be identified carefully, because
later plant growth may cover them.  It is some-
times useful to visit a site after a heavy rainfall,
if possible, to observe runoff and  leachate seep-
ages that may not be visible at other times. A
follow-up visit during a dry period may be use-
ful in  evaluating the  potential for  dust
generation.
                                              2-10

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The time needed to complete a site visit will
depend on the size and complexity of the site
and whether interviews will be conducted. On
average, a site visit may take,  between 1 to
2 days (not including interviews).

The following activities may be performed
during the site visit:

  •    Identification of unusual  features,
       including

            Spill areas and stained soils

            Evidence of environmental stress
            to  flora  or fauna  and  adjacent
            wetlands

            Presence of waste requiring special
            handling  or  precautions

            Presence  of  surface  impoundments
            and aboveground tanks

            Presence of underground storage
            tanks,  aboveground  vents, or fill
            pipes

  •    Examination of  landfills,  including

            Evidence  of slope  instability,
            leachate seeps, soil erosion

            Details of cap construction, stabili-
            ty, areas of cover cracking, erosion,
            or  subsidence

            Evidence of gas release  through
            cap

            Approximate  perimeter  of  the
            landfill

            Evidence of partially buried drums
            or other hazardous materials

            Localized areas  of stressed vegeta-
            tion or detection on explosimeter

            Factors affecting the  accessibility
            of the landfill to heavy equipment,
            such as moisture  content of the
            soil, width of benches/access roads
     Identification of site features that
     may interfere with  the  perform-
     ance of geophysical surveys

Field  characterization of wastes,
including

     General  nature of  the  wastes-
     residential, industrial, sludges, or a
     mixture

     Physical  state of the wastes~dty,
     wet, very compressible, firm, free
     liquids

     Physical  properties of exposed
     wastes-odor, gas generation, state
     of decomposition

     Preliminary measurements in hot
     areas  with  an  organic  vapor
     analyzer  (OVA)

Identification of:

     Site utilities, facilities, and struc-
     tures

     Unusual  wastes (laboratory packs,
     cylinders)

     Drainage patterns

     Possible  offsite  sources of
     contamination

     Recent  construction,    including
     housing developments

Division of site into grids to facilitate
identification  of target areas and future
remedial activities  (a Cartesian grid is
effective)

Identification of access, egress, staging,
and security points

Interviews with local residents (opportu-
nity to  confirm well survey  and  also
necessary for  preparation of community
relations plan  [CRP])
                                              2-11

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   •    Identification and confirmation of fea-
       tures on the preliminary base map and
       soil/geologic  cross-section

   •    Preparation  of  photographs of site
       features

   •    Performance of air. quality monitoring
       for high levels of volatiles or methane

 A health and safety plan (HSP) should be pre-
 pared for the initial site visit unless an HSP was
 developed for previous site work, in which case
 this plan may be adequate. If no plan exists, a
 limited HSP should be developed on the basis
 of existing data.  The RPM should coordinate
 with the Regional Health and Safety Officer on
 the  need  for the HSP  and contents. Require-
 ments for an HSP can be found in Occupational
 Safety and Health Guidance Manual for Super-
fund Activities (National Institute of Occupa-
 tional Safety and Health,  1984), Guidance  on
 Remedial Investigations Under CERCLA  (U.S.
 EPA 1985e), and Standard Operating  Safety
 Guides (U.S. EP4  1984).
  2.4 Limited  Field Investigation

 After existing data have been evaluated and a
 site visit has been conducted, a preliminary
 conceptual  site model depicting  the site's
 dynamics should be developed. If the informa-
 tion required to develop this model is incom-
 plete, a limited field investigation (LFI) should
 be conducted. (See Section 2.5 for information
 on the conceptual site model.) The LFI should
 be restricted to  the collection of easily obtain-
 able  data, which can be gathered quickly. Its
 purpose is to  define the scope of work  as
 precisely as possible, given the available infor-
 mation.  The LFI typically involves field mea-
 surements but may include chemical analysis of
 groundwater from existing  wells  or samples
 from other easily accessible sample locations.
 The  limited field  investigation is  normally
 performed during the preparation of the  work
 plan and before extensive sampling begins for
 the RI.

 Table 2-1 is a list of the possible activities that
 could be performed during an LFI at a munici-
 pal landfill site. This table should not be inter-
preted to mean that all of these objectives (and
actions to meet the objectives)  should be met to
adequately scope  an  RI/FS for a municipal
landfill  site. Rather, the  data requirements for
adequately scoping the project should be deter-
mined on a site-by-site basis.  Data needs will
differ for each site and will depend on factors
such as  the results of the existing-data evalua-
tion, the number and type of potential contami-
nant  pathways  and receptors, and  the RI
objectives.

RI reports for municipal landfills were reviewed
to determine  the  usual  activities  performed
during limited field investigations at landfills.
These activities are shown in Table 2-1  and can
include:

  '•    Property surveys

  •    Topographic surveys

  •    Surveys of  location, elevation, accessibil-
       ity of monitoring wells

  •    Well surveys for all residential wells
       within  the current or potentially affectd
       area

  •    Collection and analysis of samples from
       existing monitoring and residential wells

  •    Surface and volatile emissions survey

  •    Water  level measurements taken  from
       existing monitoring wells

  •    Survey of gas levels in nearby residences
       to determine if they  are near the explo-
       sive range  (also in onsite buildings and
       confined  spaces)

Most of this information requires field measure-
ments, which would not be gathered during the
site visit.   General investigation Table 2-1
continued activities that  could be done during
the site visit are described in. Section 2.3 and
not repeated here.

Well installation and other  activities requiring
subcontracting should be  avoided during the
LFI. Sampling is also typically not performed;
however, sampling of existing  and residential
                                              2-12

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Table 2-1
LIMITED FIELD INVESTIGATION OPTIONS FOR
MUNICIPAL LANDFILL SITES
Page 1 of 2
Activity
General Investigation
Geotechnical Investigation
Objectives
Identify previous site owner/
operators and delineate site
boundaries. Estimate
uncertainties in boundaries.
Locate existing monitoring
wells.
Evaluate site drainage patterns.
Evaluate site-cover conditions
and surface water drainage.
Evaluate gas migration,
potential, if applicable.
Locate sampling locations.
Determine landfill subsidence,
if survey is otherwise required.
Describe geologic features,
classify soil.
Action
Conduct property survey or
perform a title search or identify
property ownership from tax
records, or plat maps.
Perform location and elevation
survey of existing monitoring
wells.
Review topographic maps and
perform hydrologic survey.
Perform visual surface inspection
with topographic maps. Conduct
surface emissions survey.
Measure explosive gas levels in
nearby residence, or onsite
buildings, if present. Also
measure in water meter boxes
and utility corridors, if landfill
gas poses a threat.
Survey a grid for the site and
cross-reference to sample
locations.
Measure elevations along crown
of fill or install benchmarks in
areas of potential subsidence
(requires repeat visits by
surveyor).
Conduct visual observation of
mechanical erosion, slope
instability, differential
settlement, and pending caused
by subsidences and cracking.
2-13

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Table 2-1
LIMITED FIELD INVESTIGATION OPTIONS FOR
MUNICIPAL LANDFILL SITES
Page 2 of 2
Activity
Hydrogeologic Investigation
Objectives
Evaluate usefulness of existing
monitoring well network.
Review preliminary locations
for new monitoring wells.
Determine location of
residential wells and their
construction.
Determine direction of
groundwater flow and estimate
gradients.
Determine rate of groundwater
flow in strata and bedrock
fractures.
Confirm previous sampling.
results for both existing
monitoring and residential
wells and collect additional
data as necessary. Identify
areas of groundwater
contamination and types of
contaminants.
Determine if residential wells
adjacent to, and downgradient
from, the landfill are
contaminated.
Action
Conduct a well survey for all
wells (residential, commercial,
industrial). Determine local uses
of groundwater and accessibility
of existing wells. Obtain
permission for use.
Determine if existing wells are
obstructed (e.g., by sounding to
the bottom of the well).
Perform fracture-trace analysis in
areas with fractured bedrock
(can be done through EPIC
study).
Perform well survey for all
residential wells adjacent to, and
downgradient from, the landfill.
Obtain well logs from federal,
state, local utilities, or municipal
agencies.
Record water level measure-
ments from existing wells (at
least quarterly, to determine
seasonal variations).
Perform hydraulic conductivity
tests on existing wells.
Collect and analyze* samples
from monitoring and residential
wells. Record quality parameters
for the samples analyzed.
Compare new results with values
from previous studies.
Collect and analyze* tap water
samples before any filtration unit
and conduct preliminary risk
assessment.
* Sample collection and analysis is not usually performed as a part of an LFI but is an option that
could provide valuable information for scoping future fieldwork.
2-14

-------
wells has been included in this table because
this information, if obtainable, will greatly assist
in scoping the RI/FS.

The tasks required to perform a limited field
investigation may be  included in the statement
of  work for an EPA contractor if the  site is
designated as a fund-lead site, or they may be
attached to  the consent order for a PRP-lead
RI/FS. Performing an LFI during the develop-
ment of the, work plan often saves both time
and money. This is because it takes less time
and is less costly to scope the RI/FS correctly
the first time than to rescope certain aspects of
the project at a later date.
     2.5  Conceptual Site Model

The conceptual site model is developed so that
an understanding of the site dynamics can be
obtained.  Its purpose is to describe the site and
its environs  and to present hypotheses regarding
the suspected sources and types of contaminants
present, contaminant release  and  transport
mechanisms, rate of contaminant release and
transport  (where  possible),  affected  media,
known  and  potential routes of  migration, and
known and potential human and environmental
receptors. In general, quantitative data should
be incorporated wherever possible. Hypotheses
presented by the model are tested, refined, and
modified throughout the RI.

Generally, a conceptual site model is based on
the existing data evaluation and is developed
before any field activities, including those per-
formed  as part of an LFI. If insufficient infor-
mation is available to develop a conceptual site
model, the LFI provides  the information needed
to develop a sufficient model for scoping fur-
ther  investigations.

The  conceptual  site model is  a tool that can
assist the site manager in determining the scope
of the project,  identifying data needs, and estab-
lishing preliminary remedial action objectives.
For example, if residential areas are upwind of
the site  and existing data indicate no volatile
emissions of concern, then air may be consid-
ered  an unaffected medium in the model and no
further data should be collected during the RI.
On the other hand, if residential wells near the
 landfill are contaminated and existing ground-
 water data are limited, then the site model will
 indicate that groundwater is an affected medium
 and the collection and analysis of samples from
 this medium should be included in the RI.

 A generic conceptual site model for municipal
 landfills was  developed so that a basis  for
 project scoping could be established.  The con-
 ceptual site model was developed for municipal
 landfill sites with data collected from review of
 71 municipal  landfill RODS.    Figure 2-3
 presents a schematic diagram of this model, and
 Figure 2.4 depicts  the  information as a flow
 diagram. This generic model may be utilized to
 develop a site-specific model. After evaluating
 the data and completing a site visit,"  the RPM
 should determine which contaminant release
 and transport mechanisms  are  appropriate for
 the municipal landfill site in question.   For
 example, if hospital wastes  or radionuclides are
 in the landfill, then they should be added as a
 contaminant source,  and the release mechanism,
 affected media, exposure pathways, and recep-
 tors should be  identified. Likewise,  contami-
 nant  release and transport mechanisms  and
 media that are  not affected by  the landfill
 should be deleted from Figure 2-4. For exam-
 ple, if the  landfill is  in  a depressed  area and
 surface runoff flows into the landfill  area and
 not away  from  it, then the two associated
 release mechanisms, runoff and erosion, can be
 eliminated  from the model. However, if there
 is uncertainty about the existence  of specific
 contaminant release and transport mechanisms,
 it should be retained.

 The key element in  the development of the
 conceptual  site model  is to  identify those
 aspects of the model that require more informa-
 tion to make a decision about remediation. For
 example, if it is not possible to decide whether
 removal or containment of a known hot spot is
 the most cost-effective alternative  because  of
 uncertainty about volume, early field efforts
 should include measures to estimate the volume
 of the material within the  hot spot.  Or, sup-
 pose that existing data show that only volatile
 organics are of concern in the residential wells.
 For streamlining the analytical program, chemi-
 cal analysis of groundwater samples should then
be  focused on the  target compound  list
                                             2-15

-------
   lng*itton,
Darmal Contact,
Bloconcvntration
Ingettlon,
 Dcimal
Contact,
Inhalation
                                                               Duit.
                                                            \tokrtllliatlon.
                                                            Landfill Goi
         LEGEND
        V Grouidwatw KM*
          Landfill Conlmti
          Expoiur* (taut*
                                                                                                                                   Figure 2-3
                                                                                              SCHEMATIC OF  CONCEPTUAL  LANDFILL SITE

-------
 CONTAMINANT
   SOURCE
 MUNICIPAL,

 INDUSTRIAL,

COMMERCIAL,

 HAZARDOUS

  WASTES
   CONTAMINANT
RELEASE/TRANSPORT
AFFECTED
  MEDIA
EXPOSURE
  POINT
EXPOSURE
  ROUTE
 PRIMARY
RECEPTOR
SECONDARY
 RECEPTOR



_
Ingestion
Dermal
Contact


Ingestion



_
                                                                                                            Trespassers
                                                                                                          Future Site Users
                                                                                                           Site Workers
                                                                                                         Terrestrial Wildlife
                                                                                                            People Who
                                                                                                          Consume Wildlife
Residents
Area Workers
Trespassers

Site Workers
Future Site Users

Wed and Ecosystem

Aquatic Wildlife
People Swimming


	

People Who
Consume Wildlife

People Who
Consume Fish
                                                                                       Tress passers
                                                                                    Future Site Workers
                                                                                                           Trespassers
                                                                                                           Site Workers
                                                                                                            Terrestrial
                                                                                                             Wildlife
                                                                                                            People with
                                                                                                          Residential and
                                                                                                          Commercial Wells
                                                                                                            People Who
                                                                                                          Consume Wildlife
                                                                                                            Residents
                                                                                                           Area Workers
                                                                                                           Site Workers
                                                                                                          Future Site Users
                                                                                                                                          Figure 2-4
                                                                            POTENTIAL CONCEPTUAL SITE MODEL FOR MUNICIPAL LANDFILLS

-------
 parameters (U.S.  EPA  1988a), with  some
 analysis of the target analytes list parameters
 (U.S. EPA 1987g) to confirm their absence.

 The site model will also indicate the potential
 human  and  environmental receptors affected  by
 the  site. If quantitative information is devel-
 oped as part of the conceptual model, it may  be
 possible to develop a preliminary evaluation of
 potential risks to  receptors.  Experience and
 judgment can be used to focus on the contami-
 nation that causes the greatest risk or, if, stan-
 dards are available  [such as maximum contami-
 nant levels (MCLs)], they can be used to iden-
 tify potentially affected receptors and the need
 to initiate remedial  action (see Section 2.6).

 The site model can also help identify prelimi-
 nary remedial action alternatives. For example,
 if contaminated groundwater from the landfill is
 being used for residential water supply, then
 preliminary remedial action alternatives could
 include any of the following, depending on the
 site  conditions:   alternative water supply, on-
 line water treatments systems for each  house-
 hold, capping to prevent downward percolation
 of precipitation and associated transport of the
 contaminants  from  the landfill to the
 groundwater, and a slurry wall to prevent addi-
 tional horizontal movement of the contami-
 nated groundwater.
         2.6  Risk Assessment

 The risk assessment is initiated to help to deter-
 mine whether the contaminants of concern at
 the  site pose a current  or potential risk to
 human health or the environment and to help
 determine whether remedial action is warranted.
 The assessments are site-specific and may vary
 in the exent to which qualitative and quantita-
 tive analyses are utilized,  depending  on the
 complexity and particulars of the site, as  well as
 the availability of pertinent ARARs, and other
 criteria and guidance.

 The Risk Assessment Guidance for Superfund:
 Human Health Evaluation Manual (U.S. EPA,
 1989k) describes a preliminary  identification of
potential human exposure that is included in the
 development of the work plan and the Sampling
 and  Analysis Plan. This assessment is based on
existing data and information  and  on the
conceptual  site model  and  is  designed to
identify  data  gaps,  provide a focus  for the
RI/FS, and provide support for remediation to
proceed,  if appropriate.

The baseline risk assessment is a quantitative,
chemical-oriented  evaluation  of  the potential
threats to human health and the  environment
that would be  posed by a site in the absence of
any remedial  action,  i.e., the no-action  alter-
native. The baseline risk assessment is usually
quantitative, although qualitative  analysis may
be  appropriate and sufficient. A  baseline risk
assessment  identifies  and characterizes the
toxicity of contaminants of concern, potential
exposure pathways, potential human and envi-
ronmental receptors, and the extent of expected
impact or threat under the conditions  defined
for the site. The baseline risk assessment can
be used as a tool to streamline remedial action
decisions by identifying areas where remediation
should proceed immediately (see  Section 3.7).
The risk assessment for comparion of remedial
alternatives is designed to identify potential
threats to human  health  or the  environment
that may  arise from the execution of  various
types of remediation activities.   Section 6.3
presents a comparative analysis of alternatives
for an example municipal landfill site.

The preliminary identification of exposures is
conducted during the scoping of the RI/FS and
is based on information from the PA/SI and
possibly other previous  investigations. This
exercise uses this existing information  to iden-
tify the potential area of contamination, chemi-
cals of concarn,   routes  of  contaminant
transport, and potential exposure pathways to
identify  data  needs and to focus the RI/FS.
Because options for remedial action at  munici-
pal landfill sites are limited, it may be possible
to use this preliminary information, with the
addition  of toxicity information or ARARs to
initiate remedial action, if appropriate.  Specifi-
cally, early action may  be warranted when
human health or environmental standards for
one or more contaminants in a given media are
clearly exceeded.   However, because  there is
often not a lot of data available at this stage, or
because data is of questionable quality, it may
not be possible to justify an early or  interim
remedial action at this stage. However, if the
                                              2-18

-------
need for an interim or early action is suspected
(e.g., temporary  landfill  cover, groundwater
remediation, respectively) but insufficient data
are available,  these data needs  should be
identified and the corresponding data should be
collected early  in the RI  process.   This may
allow for decisions on potential early or interim
remedial actions to be made during the baseline
risk assessment  (Section 3.7).     Detailed
information can  be  found on scoping risk
assessments in the documents Risk Assessment
Guidance  for  Super fund—Human  Health
Evaluation Manual (U.S. EPA  1989J), and Risk
Assessment   Guidance  for Superfund—
Environmental Evaluation Manual (U.S. EPA,
 1989c).
     2.7 Preliminary  Remedial
    Action Objectives and  Goals

 Preliminary remedial action objectives and goals
 are developed during the scoping of the RI/FS
 to assist in identifying preliminary remedial
 action alternatives  and RI data requirements.
 Remedial action objectives are general descrip-
 tions of what the remedial action is expected to
 accomplish. The preliminary  remedial  action
 objectives are based on the existing data for the
 site  and the conceptual site model. Remedial
 action  objectives are aimed at protecting human
 health  and the environment and should specify:

  •    The  contaminant(s) of concern

  •    The exposure rate(s) and receptor(s)

  •    An acceptable  contaminant level or
       range of contaminant levels for each
       exposure route

 Examples of general remedial  action objectives
 for media of concern at municipal landfill sites
 are presented in Table 2-2.

 Remedial action goals are  a subset of the reme-
 dial action objective; the remedial  action goals
 consist  of  chemical  concentrations  that are
 protective and serve as specific numeric goals
 for the remedial action.   Preliminary  remedial
 action goals should be developed with the pre-
 liminary ARARs and exposure assessment. An
 example of a preliminary remedial action goal
would be to prevent ingestion of groundwater
containing TCE above 5 micrograms per liter.
In this example, the preliminary remedial action
goal is based on the MCL for TCE.

It is necessary that both the  preliminary risk
assessment and preliminary ARARs be used in
developing  the  preliminary  remedial  action
goals.  A description of the  preliminary risk
assessment is presented in Section 2.6.

As part of identifying remedial action goals,
ARARs that typically apply to municipal land-
fill sites are  divided into three types:
       Chemical-specific
       MCLGs, etc.)
ARARs  (MCLs,
  •    Location-specific ARARs (floodplains,
       wetlands)

  •    Action-specific  ARARs  (performan&
       design standards)

Potential federal ARARs that may affect muni-
cipal landfill sites are discussed in Section 5 of
this report.

To assist in developing preliminary remedial
action goals, an ARARs table should be devel-
oped and should include identifiable contami-
nants  of  concern, affected  media,  regulatory
agencies  concerned  with the  media (federal,
state, or local), potential remedial action alter-
natives (see Section  2.8), and regulatory agen-
cies concerned with that action.   A more
detailed list of chemical concentrations will be
generated during development of the DQOs.

Promulgated state ARARs that are more strin-
gent than federal requirements and have been
identified in  a timely  manner  must  also be
included  (although they may later be waived if
they have not been consistently applied). In
particular, the state  ARARs  for landfill cap
design, extracting and monitoring landfill gas, or
discharging contaminated groundwater should
be incorporated.   It is  important that  care be
used in identifying  and eliminating potential
ARARs at this stage of the scoping  process. In
developing remedial  action goals, "to-be-consid-
ered"  (TBC) material such as  proposed MCLs
should also be  evaluated.    TBC  material
                                             2-19

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Table 2-2
PRELIMINARY IDENTIFICATION OF REMEDIAL ACTION OBJECTIVES
FOR MEDIA OF CONCERN AT MUNICIPAL LANDFILL SITES
Environmental Media
Soils/Landfill Contents
(Primarily from hot spots)
Air/Dust
Landfill gas
Surface water
Sediment
Groundwater
Leachate Seeps
Remedial Action Objective
Prevent direct and dermal contact with, and ingestion of,
contaminated soil/landfill contents
Prevent inhalation
Prevent inhalation and explosion
Prevent ingestion, adsorption, and bioconcentration
Prevent ingestion, adsorption, and bioconcentration
Prevent ingestion and dermal adsorption
Prevent migration to surface waters
Prevent onsite inhalation and dermal adsorption
Prevent migration to surface waters
includes nonpromulgated advisories and guid-
ante issued by the federal or state government,
and often reflects the latest scientific informa-
tion on health effects, detection limits,  and
technical feasibility.

     2.8  Preliminary   Remedial
              Technologies

2.8.1 Development  of Preliminary Remedial
Action Alternatives

Preliminary identification of remedial  action
alternatives for each medium of interest should
begin after the identification of the preliminary
remedial action  objectives.    Developing  the
preliminary remedial action alternatives at this
time and before  determining the RI scope has
several  advantages:

  •    Defining the degree of detail necessary
       in delineating the extent of groundwater
       or soil contamination

  •    Identifying data needed for evaluating
       remedial  action technologies
  •    Identifying action-specific ARARs that
       may influence the scope of RI activities

The number of  practicable  remedial actions
available for municipal landfills is limited. They
are based on previous experience, engineering
judgment, and the NCP expectations. As stated
in  the NCP,  EPA  expects  that containment
technologies will generally be appropriate for
waste  that poses a relatively low long-term
threat or where treatment is impracticable  (40
CFR Sec. 300.430 (a)(iii)(A)). In addition, U.S.
EPA expects  treatment  to be considered  for
identifiable areas of highly toxic and/or mobile
material that constitute the principal threat(s)
posed  by the site (40 CFR  Sec.  300.430(A)
(iii)(C)).    Remedial actions  which are most
practicable for municipal landfill sites are dis-
cussed in more detail in Section 4.

The remedial  action  alternatives developed at
this time will be refined throughout the RI/FS.
Although these alternatives will direct the  site
characterization  activities  and will form  the
basis for the FS, they  do not necessarily have to
limit the alternatives considered later in the  FS.
However, if alternatives that  are not identified
here are later considered in the FS, it may be
necessary to collect  additional site data in a
                                             2-20

-------
second  phase of the RI. This approach  may
contradict the goal of streamlining the RI/FS
for municipal landfill sites, and it is therefore
important that potentially viable alternatives are
not eliminated too early in the process. On the
other hand, alternatives should be ruled out at
this stage if they are clearly unsuited for the site
(that is, technically infeasible or inappropriate
for the site and waste characteristics) or if the
costs  are grossly excessive. An example of. an
impracticable alternative might be excavation
and incineration of the contents of a landfill
that contains more than 100,000 cubic yards of
waste.

As  stated previously, remedial action objectives
are developed as a first step in identifying reme-
dial action  alternatives.    General  response
actions (for example, treatment or containment)
are then  identified to satisfy the remedial action
objectives for each medium of concern. Tech-
nology types (for example, chemical  treatment)
necessary for achieving each remedial action
objective are  identified, followed by the identifi-
cation and evaluation of  technology process
options  for  each technology.   Uncertainties
about existing site  conditions that  preclude
choosing a remedial action alternative should be
highlighted to focus  sample design, collection,
and analytical methods.

The site  characterization proposed  at municipal
landfill   sites  (see Section 3  of  this report)
reflects  the number  of remedial  alternatives
available. Several  technologies or alternatives
are unlikely to survive screening in the FS for
effectiveness, implementability,  or cost reasons.
These alternatives should be eliminated in the
preliminary  screening  stage or  as potential
alternatives are being developed. As an exam-
ple, complete excavation of a large  landfill with
subsequent treatment or disposal is not general-
ly feasible because the costs would be grossly
excessive for the  effectiveness they provide.
Additionally,  excavation of a  landfill may cause
greater risks than it  prevents. Likewise, treat-
ment  or  offsite disposal is not typically consid-
ered for landfill contents because  most of the
waste within landfills is  a heterogeneous mix-
ture of materials.

Remedial action alternatives for landfill  sites
are practically limited to source control by cap-
ping and possibly removal or treatment of hot
spots,  groundwater  extraction and treatment,
and landfill-gas control. Onsite surface water,
sediments, and wetlands are typically addressed
by either source control or groundwater treat-
ment.  These alternatives are often combined
with institutional  controls,  alternative  water
supply, or  fencing  for  a complete  remedial
action.    As  with  all  Superfund sites,  the
no-action alternative  must also be evaluated for
all media.  This alternative involves  no addi-
tional  activities by  EPA thereby providing a
baseline for evaluating other  alternatives.

Figure 2-5  portrays a conceptual model for
identifying technologies that will  lead  to
achievement of specific remedial action objec-
tives at municipal landfill sites.

2.8.2.  Review  of  Remedial Technologies  in
CERCIA Landfill RODS

To identify  the most viable remedial technolo-
gies for use at municipal landfill sites on the
NPL, CERCLA landfill RODS through  1989
were reviewed.  Table B-l, in  Appendix B of
this document, lists RODS that were reviewed.
A source control ROD has not yet been com-
pleted  for some of the sites, and a footnote in
Table  B-l  indicates those sites where partial
remedies have been implemented to  date (for
example, remedies for groundwater contamina-
tion). The information presented in this section
is based on the NCP expectations and the reme-
dies outlined in the ROD documents. Since the
ROD precedes the remedial design and remedi-
al action (RD/RA) phase, some of the remedies
indicated may not have been implemented yet.
However, the information is still valuable for
remedy  selection  purposes.      Additional
information on the status of specific  remedial
actions can  be gathered by contacting the EPA
Regional office in which a specific ROD was
written.

A comprehensive list of the technologies used
at specific sites in each of the EPA Regions is
also presented in Appendix B  (Table B-2).
When  conducting  a  feasibility study  for  a
specific site, an EPA RPM could use this list to
identify sites within  his or her region for which
the same technologies were considered. Addi-
tional  information could  then  be gathered  on
those sites  to help  in  the  FS process.  Table
B-3, also  included in Appendix B, presents a
                                              2-21

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REMEDIAL ACTION
OBJECTIVE REMEDIAL TECHNOLOGY TECHNO

Prevent Direct Contact J-

Prevent Direct
Contact;
minimize erosion
Prevent Direct
Contact, Minimize
Erosions, Reduce
Infiltration
Control Surface
Water & Erosion

Remediate
Soils, Hot
Spots and
Sediments

Control
Contaminated
Groundwater &
Leachate

Treat
Contaminated
Groundwater
& Leachate

Control Landfill
Gas




_[
-| — | Access R


Li Cap*


	 Cap3

— | Surface C








.nntrnk 	 E'



H Excavation & Disposal 	

	 1 Therma

Treatment — 	


"• | Physical Treatment


LOGY OBJECTIVE





osion Control , • '-
PROCESS OPTION
Deed Restriction

Fence

Native Soil Cover
Single Barrierb

Composit Barrier6

Vegetation

non/Runoff Control 	 1 Grading




1 	 1 Vertical Barrier [—{Containment |



Treat Landfill
Gas



— Leacnate ujnecnon 	 • — Collectio
— — | Groundw
	 1 Chemica






3

	 [ Physical









-| — | Passive Systems [ Confeinrr


L_| Active Systems | Containr
	 Thermal Treatment 	 Destnjct



n/Enhanced Containment | 1
L
<
L


E
L
lent " |
Consolidation (Under Cap)

Incineration (Onsite)

Solidification/Fixation

Slurry Wall

Vertical Extraction Wells
Subsurface Drains
Metals Precipitation

pH Adjustment

Aerobic

Anaerobic
Adsorption

Air Stripping

Sedimentation

Sand Filtration

POTW

RCRATSDF

Pipe Vents
1 	 1 Trench Vents

on 	
Extraction Wells
Flaring


a Landfill caps will likely be implemented in conjunction with access restrictions, surface water controls, and erosion controls
b Examples of sites where a composite barrier cap may be selected instead of a single barrier cap include sites where infiltration is the primary concern.
Figure 2-5
IDENTIFICATION OF REMEDIAL TECHNOLOGIES
2-22

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summary by EPA Region of the frequency with
which specific technologies were implemented
at the CERCLA municipal landfill sites.  This
information was used to determine which tech-
nologies appear  to be most practicable for
CERCLA municipal landfill sites based on past
experience.

Table 2-3 presents brief descriptions of remedial
technologies that could be applied to various
environmental media at municipal landfill sites.
These technologies were identified on the basis
of the ROD review mentioned above.   Also
included in this table are  comments that can
assist the RPM  during  development of remedial
action alternatives. The evaluation comments
identify situations where a technology may be
practicable, and therefore,  worthy of consider-
ation.    A  detailed description  of the most
practicable  technologies,  including  the  data
requirements to evaluate these technologies, can
be found in Section 4 of this report.

The need  for treatability  testing to evaluate
remedial  technologies should  be  identified
during project scoping. During scoping, a liter-
ature survey should  be  conducted  to gather
information on a technology's applicability, per-
formance, implementability, relative  costs, and
operation and  maintenance requirements.  If
practicad candidate technologies have not been
sufficiently demonstrated  or cannot be  ade-
quately evaluated  on the  basis of available
information (e.g.,  characterization of a waste
alone is insufficient to  predict treatment perfor-
mance or the size and cost of treatment units),
then treatability testing should be performed.
The  treatability testing  program should be
designed and implemented during the RI, while
other field activities are underway. Additional
information on treatability studies can be found
in the documents titled, Guide for Conducting
Treatability Studies under CERCLA (U.S. EPA,
1989i) and Summary of Treatment Technology
Effectiveness for Contaminated Soil (U.S. EPA,
1989k).

    2.9 Objectives of the RI/FS

The overall objectives of the RI/FS are to:

  •    Complete a field program for collecting
       data of known and acceptable quality to
       evaluate the type, extent, and magnitude
       of contamination in the surface and
       subsurface soils, landfill gas, ground-
       water,  surface water, and sediment of
       ponds and wetlands

  •    Determine the present and future risks
       to human health and the environment
       from existing contamination

  •    Develop and evaluate remedial action
       alternatives where unacceptable risks are
       identified

If a risk to human health or to the environment
exists  and remedial action is necessary,  the
objective of the  RI/FS is to  select  a cost-
effective  remedial action that minimizes  or
eliminates exposure to  contaminants from the
landfill.   Achieving this objective requires a
series of decisions involving several  interrelated
activities. These activities are based on  the
work plan,  which specifies  the information
necessary for developing a cost-effective data-
collection program and for supporting subse-
quent decisions.

During scoping, decisions are made to identify
the remedial action alternatives that could  be
implemented if certain site conditions were met.
Information about a site is gathered to deter-
mine whether the site meets the conditions that
would allow a particular alternative to be imple-
mented. The objectives of the RI are therefore
to characterize the site to assess  if risks  to
human health or to the environment are pre-
sent and to provide sufficient information to
develop and evaluate remedial action  alterna-
tives. Physical information about  the  site is
necessary to differentiate among the technolo-
gies available for each remedial action  alterna-
tive. This information  is obtained  during  the
RI. In addition to specific field tasks,  the  RI
objectives  should  address  the  broad  project
goals.  If this information has not been previ-
ously collected during the initial site scoping, it
must be collected during the RI. This informa-
tion includes characterizing the landfill for the
environmental setting, the proximity  and size of
human population,  the nature  of the  prob-
lem^), the treatability testing for contaminated
groundwater and leachate (and possibly for hot
spots), and the potential remedial actions.
                                              9.9"

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Table 2-3
REMEDIAL ACTIONS USED AT LANDFILL SITES
Pagel of?
Environmental Media
Soils/Landfill Contents
General Response
Actions
No Action
Access Restriction
Containment
Remedial Technologies

Deed Restrictions
Groundwater Restrictions
Fencing
Surface Controls
cap
Process Options


Permits

Grading
Revegelation
Native Soil
Single barrier
Double barrier
Description
No action.
All deeds for properly within potentially
contaminated areas would include restric-
tions on use of property.
All deeds for property within potentially
contaminated areas would include restric-
tions on development and domestic use of
groundwaler.
Security fences installed around potentially
contaminated areas to limit access.
Reshaping of topography to manage infil-
tration and run-off to control erosion.
Seeding, fertilizing, and watering until a
strand of vegetation has established itself.
Uncontaminated native soil placed over
landfill.
FML finer or compacted clay over site.
Usually protected with additional fill,
above, and topsoil. Clay cap is normally
2 feet thick.
Compacted clay covered with a synthetic
membrane (20 millimeter minimum)
followed by 1 foot of and and 1.5 feet of
fill and 6 inches of topsoil to provide
erosion and moisture control and freeze-
thaw protection.
Evaluation Comments
Required by NCP to be carried through
detailed analysis of alternatives
Potentially viable.
Potentially viable.
Potentially viable,
Potentially viable.
Potentially viable.
Viable in cases where direct contact/
erosion are prime threats, Also may be
viable in cases where majority of source is
below water table and leaching is not a
significant release mechanism. Unless
engineered to do so, will not result in
reduction in infiltration.
Potentially viable in situations where it is
not necessary to comply with RCRA
Subtitle C.
Potentially viable. Provides maximum pro-
tection from exposure due to direct con-
tact. Also this is the most effective
capping option for reducing infiltration in
campliancc with RCRA guidance.

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Table 2-3
REMEDIAL ACTIONS USED AT LANDFILL SITES
Page 2 of 7
Environmental Media
Soils/Hot Spots
General Response
Actions
Removal
Soil Treatment
Remedial Technology
Excavation
Disposal Onsite
Disposal Offsite
Thermal Treatment
Process Options
Mechanical
Excavation
Drum Removal
Consolidation
RCRA Type
Landfill
RCRA Landfill
Onsite Incineration
Low Temperature
Thermal Volatiliza-
tion
Description
Use of mechanical escavation equipment
to remove and load landfill wastes for
disposal.
Excavation of subsurface drums applies to
hot spot areas. A drum grappler, a drum
cradle, or a sling attached to a backhoe or
crane, or a front-end loader can be used
for drum removal.
Refers to consolidation under a landfill
cap of excavated material from hoi spot
areas.
Permanent storage facility onsite, double
lined with clay and a synthetic membrane
liner and containing a leschate collection/
detection system.
Transport of excavated soil to a RCRA
permitted landfill.
Landfill wastes are thermally destroyed in
a controlled oxygen sufficient
environment.
VOCs removed from soil in a drying unit.
Evaluation Comments
Potentially viable for hot spot areas. May
release VOCs to the atmosphere posing a
threat to nearby residents. Alhough VOC
releases are usually controllable, potential
for fires and explosions from methane gas
present.
Potentially viable for hot spot areas.
Potential for fires and explosions from
flammable material.
Potentially viable for hot spot areas.
RCRA landfills are usually not constructed
onsite because of typically poor site char-
acteristics and great expense.
Potentially viable for hoi spot areas.
RCRA Land Disposal Regulations may
require treatment of waste prior to
disposal.
Potentially viable for hot spot areas. High
concentration of inorganics would inhibit
efficiency. May require pretreatment for
debris.
Potentially viable for VOC hot spot areas.
However, it is rarely effective by itself
because of mixed nature of waste material
including inorganic and nonvolatile
fraction of organics, and may require
pretreatment of debris.

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to
Table 2-3
REMEDIAL ACTIONS USED AT LANDFILL SITES
Page 3 of 7
Environmental Media
Soil/Hot Spots
(Continued)
Air/Dust
Groundwater and
Leachate
General Response
Actions
In Situ Treatment
Containment
No Action
Institutional
Controls
Containment
Collection
Remedial Technologies
Biological Treatment
Physical Treatment
Offsite Treatment
Dust Controls

Alternate Water Supply
Vertical Barriers
Horizontal Barriers
Extraction
Process Options
Biodegradation
Vapor Extraction
Solidification/
Stabilization
RCRA Incinerator
Cover/Cap

Public Water Supply
Slurry Wall
Bottom Sealing
Extraction Wells
Description
Soils seeded with microorganisms and
nutrients to allow biological degradation.
Volatile organics stripped from soil and
recovered in vapor form through extrac-
lion wells.
Soil mixed with an pozzolanic/cement
material which can solidify and reduce
mobility of contaminants.
Incineration of contaminated soils at a
RCRA-permitted facility.
Uncontaminated native soil placed over
landfill.
No Action.
Residents will be connected to public
waler supply.
Trench around site or hot spot is
excavated while filled with a bentonite
slurry. Trench is backfilled with a soil- (or
cement) bentonite mixture.
Controlled injection of slurry in notched
injection holes to produce horizontal
barrier beneath site.
Series of wells to extract contaminated
groundwater.
Evaluation Comments
Potentially viable for hot spot areas. Pilot
testing is required to design the
biodegradation process. Effectiveness is
uncertain since results have not been
demonstrated with diverse mixed wastes
typically present at municipal landfill sites.
Potentially viable— applicable for removal
of VOCs; inorganic and semivolatile
contamination would remain.
Potentially viable for hot spot areas.
Effective for soils contaminated with
inorganic and low concentrations of
organics.
Rarely viable due to unavailability and
expense.
Potentially viable for dust control.
Required by NCP to be carried through
detailed analysis of alternatives.
Potentially viable.
Potentially viable-effectiveness depends on
site characteristics. Slurry wall should be
keyed into aquitard or bedrock.
Potentially viable-however, very rarely
used because of ineffectiveness in
achieving an adequate seal.
Potentially viable. May include perimeter
wells to collect leachale as well as
downgradient wells to capture offsite
migration of contaminated groundwater.

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Kl
-J
Table 2-3
REMEDIAL ACTIONS USED AT LANDFILL SITES
Page 4 of 17
Environmental Media
Groundwater and
Leachale (continued)
General Response
Actions
Treatment
(may also apply to
surface water)

Remedial Technologies
Leachate Collection
Biological Treatment
Chemical Treatment
Physical Treatment
Process Options
Leachate Drains/
Collection Trench
Aerobic
Anaerobic
Ion Exchange
Oxidation
Metals Precipitation
pH Adjustment
Granular Activated
Carbon (GAC)
Adsorption
Air Stripping
Sedimentation
Description
System of perforated pipe laid in trenches
onsite to collect contaminated ground-
water and lower water table.
The use of aerobic microbes to biodegrade
organic wastes.
The use of anaerobic microbes to bio-
degrade organic wastes.
Contaminated water passed through a bed
or resin material where exchange of ions
occurs between the bed and water.
Oxidizing agents added to waste for oxida-
tion of heavy metals, unsaturated organics,
sulfides, phenolics and aromatic hydro-
carbons to less toxic oxidation states.
Inorganic constituents altered to reduce
the solubility of heavy metals through the
addition of a substance that reacts wilh
the metals or changes the pH.
Neutralizing agents (such as lime) added
to adjust the pH. This may be done to
neutralize a waste stream or to reduce the
volubility of inorganic constituents as part
of the metals precipitation process.
Passage of contaminated water through a
bed of adsorbent so contaminants adsorb
on the surface.
Mixing of large volumes of air with water
in a packed column or through diffused
aeration to promote transfer of VOCs
from liquid to air.
Suspended particles are settled out as a
pretreatment or primary treatment step.
Evaluation Comments
Potentially viable.
Potentially viable for organics. Sludge
produced.
Potentially viable for organics. Sludge
produced.
Potentially viable.
Potentially viable.
Potentially viable.
Potentially viable.
Potentially viable.
Potentially viable.
Potentially viable.

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NJ

NJ
oo
Table 2-3
REMEDIAL ACTIONS USED AT LANDFILL SITES
Page 5 of 7
Environmental Media
Groundwater and
Leachate (continued)
Landfill Gas (LFG)
General Response
Actions
Treatment
(continued)
Disposal
Collection
Remedial Technologies
Physical Treatment
(continued)
Onsite Discharge
Offsite Discharge
Groundwater Monitoring
Passive Vents
Process Options
Sand Filtration
Aquifer Reinjection
POT W

Pipe Vents
Trench Vents
Interceptor
Trenches
Description
Used to filter out suspended particles.
May be preceded by a coagulation/
flocculation step to increase the effec-
tiveness of sand filtration.
Extracted, treated groundwater is
reinjected into the aquifer to accelerate
the cleanup.
Extracted groundwater discharged to local
POTW for further treatment.
Groundwater monitoring of existing or
new wells to detect changes in ground-
water movement or contamination.
Atmospheric vents are used for venting
LFG at points where it is collecting and
building up pressure. Vents are often
used in conjunction with flares.
Constructed by excavating a deep narrow
trench surrounding the waste site or span-
ning a section of the area perimeter. The
trench is backfilled with gravel, forming a
path of least resistance through which
gases migrate upward to the atmosphere.
Trenches are most successfully used where
the depth of LFG migration is limited by
groundwater or an impervious formation.
Used when a landfill contains saturated
refuse near the surface. Constructed by
excavating a deep, narrow trench
surrounding the waste site or along a
section of the perimeter. Backfilled with
gravel to form a path of least resistance.
Evaluation Comments
Potentially viable.
May not be viable due to state ARARs.
Potentially viable. Requires extensive
negotiations wiht POTW.
Potentially viable.
Potentially viable.
Potentially viable.
Potentially viable.

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txJ
to
Table 2-3
REMEDIAL ACTIONS USED AT LANDFILL SITES
Page 6 of 7
Environmental Media
Landfill Gas (LFG)
(Continued)
Surface Water and
Wellands Sediments
General Response
Actions
Collection
(Continued)
Treatment
Monitoring
Removal
Disposal
Treatment
Remedial Technologies
Active Systems
Thermal Destruction
Monitoring Welts
Excavation
Dewatering
Offsite Disposal/
Discharge
Physical
Process Options
Extraction Wells
Air Injection System
Enclosed Ground
Flares

Mechanical
Excavation
Wells or Trenches
RCRA Landfill
Stabilization
Thermal Treatment
Description
Applied extraction vacuum will serve to
withdraw LFG in both the horizontal and
vertical directions. Wells are connected
by a collection header which leads to a
blower/burner facility. Vacuum blowers
serve to extract the LFG from the wells
and push the collected gas through a free
vent or waste gas burner.
Wells are constructed in the natural soil
between the landfill and threatened struc-
tures. A blower pumps air into the wells,
creating a pressurized zone which both
retards LFG flow and dilutes subsurface
methane concentrations.
Enclosed ground flare systems consist of a
refactory-lined flame enclosure. Waste is
sometimes mixed with a supplemental fuel
and fed through a vertical, open-ended
pipe. Pilot burners next to the end of the
pipe ignite the waste.

Use of mechanical excavation equipment
to remove and load contaminated
sediments for disposal.
Temporary lowering of water table.
Usually done in conjunction with sediment
removal.
Transport of exccavated sediment to a
RCRA permitted landfill.
Soil mixed with stablizing reagents
(e.g., lime, fly ash) which can stabilize
contaminants.
Contaminated sediments are thermally
destroyed in a controlled oxygen-sufficient
environment.
Evaluation Comments
Potentially viable.
Potentiality viable. Application of this
technology is site specific. Injection wells
must be located a sufficient distance from
the landfill to prevent forcing air into the
refuse. Spacing and depth of wells are
also important.
Potentially viable— however, could produce
secondary air pollutants from the process,
Potentially viable.
Potentially viable. Potential for secondary
migration of contaminants via surface
water during excavation.
Potentially viable way to reduce the risk of
secondary migration of contaminants
during excavation.
Potentially viable. Treatment may be
based on land disposal restrictions.
Potentially viable for sediments contam-
inated with inorganics and low
concentrations of organics.
Potentially viable. Ash may require
additional treatment for inorganic.

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Table 2-3
REMEDIAL ACTIONS USED AT IANDFILL SITES
Page7of7
Environmental Media
Surface Water
General Response
Actions
Detention and
Sedimentation
Collection
Treatment
Monitoring
Remedial Technologies
Stormwater Controls
Surface Controls
Physical, Chemical, and
Biological Treatment
Gaging Stations
Process Options
Grading
Revegegation
Pumping, Diversion,
or Collection
See Grondwater and
Leachate Process
Options

Description
Reshaping of topography to manage
infiltration and run-off to control erosion.
Collection of surface waler for removal,
rerouting, or treatment.
Treatment of surface water using
biological, chemical, or physical treatment
to remove organic or inorganic'"
contaminants. See descriptions of process
options under groundwater and leachate
treatment.
Surface water monitoring to measure flow
and containment concentration.
Evaluation Comments
Potentialiy viable. Usually implemented
with the construction of a cap.
Potentially viable.
Potentially viable for small ponds or
lagoons. Will usually be done in
conjunction with treatment of groundwater
or leachate.
Potentially viable.
U)
o

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Tables 2-4 and 2-5 present more specific RI
objectives for both Phase I and Phase II field-
work.  A phase is defined as a time  period
where additional  sample  collection may be
rtecessaty  to   characterize   a   site   more
completely.  Activities  such as recontracting for
services or remobilizing onto a site would be
considered a  separate  "phase" of fieldwork.
Ideally, site  characterization  of both sources
(landfill  and  hot  spots) and other affected
media should be  conducted  in one phase.  In
some cases,  however, because of  the  site's
complexity, Phase  II sampling  may be required.
Phase I and Phase II  sampling are  often, but
not necessarily, sequential. These investigations
can take place on slightly different  schedules or
take place simultaneously, depending on the
analytical   turnaround   time   and    field
observations.

If sufficient information is not collected in  a
single phase to characterize a site adequately,  it
may be necessary to conduct a Phase II investi-
gation. Phase II  investigations are  more fre-
quently  required  for  potential or existing
groundwater contamination or at landfill sites
with  nearby  wetlands  and/or surface  water.
Phase I  groundwater  investigations typically
estimate the plume location and may be suffi-
cient to  initiate  remedial actions  for  plume
containment.   Phase II groundwater investiga-
tions typically  further  refine the  extent  of
groundwater  contamination and are typically
used to aid in  the design and implementation of
the final response actions. Similarly, Phase I
wetland  and/or surface water investigations
determine if the wetlands or surface  waters are
affected, while Phase II wet lands and/or surface
water investigations determine the magnitude
and  extent of the impact.  Phase II  investiga-
tions for landfill contents and landfill gas are
not typically done, because adequate informa-
tion for characterizing these media is usually
obtained  from the  Phase I investigation.

    2.10 Development  of DQOs

DQOs are qualitative  and quantitative  state-
ments specifying the required quality of the data
for each specific use.  DQOs are based on the
concept that  different data uses often require
data of varying quality. An example of different
data uses for the RI/FS include site characteri-
 zation,   risk  assessment,   and alternatives
 evaluation.

 DQO development is begun during generation
 of the conceptual site model and further refined
 during definition of the preliminary remediation
 goals. DQOs, however, are not made final  or
 documented until after the RI objectives have
 been established. There are three objectives  in
 developing DQOs.   One is to obtain  a well-
 defined  sampling and analysis plan (SAP). The
 SAP consists of a field sampling plan (FSP) and
 a quality assurance  project plan (QAPP). The
 SAP identifies the number and types of samples
 to be collected,  the appropriate method of anal-
 ysis, and the reason  the information from these
 samples  is necessary  to make necessary remedial
 decisions. The second objective in developing
 DQOs is to identify  the required QA/QC proce-
 dures to ensure the  quality of the  data being
 collected. The third objective is to integrate the
 information required by the decision makers,
 data users, and technical specialists associated
 with the  RI/FS  process.     This  integrated
 approach  allows  for a cost-effective  RI/FS
 implementation  program.

 The  DQO  process  includes  three  stages for
 identifying the data quality needed to character-
ize a site adequately. The stages are:

   •    Stage 1.  Identify decision types

            Identify  and   involve decision
            makers, technical specialists, and
            other data users

            Evaluate available information for
            uncertainty  or    adequacy   for
            making   decisions

             Specify the RI/FS objectives and
            the critical decisions that  would
            affect potential remedial actions

   •    Stage 2. Identify data uses and needs

            Identify data uses and types

            Identify data  quality and quantity
            needs

            Evaluate sampling  and  analysis
            options
                                              2-31

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                                                 Table 2-4
                          PHASE I REMEDIAL INVESTIGATION OBJECTIVES FOR
                                      MUNICIPAL IANDFILL SITES*
                                                                                                 Page 1 of 4
            Activity
                                                               Phase I Objectives
                                           (Activities Generally Performed After Work Plan is Approved)
               Objectives
             Action
Site Mapping/Site Dynamics
 Map site and determine topography
 determine site boundaries, drainage
 patterns, and other geophysical features.
Use photogrammetric methods
from aerial photography; conduct
fly-over, if necessary.
Geophysical  Investigation
 Investigate presence of buried
 ferromagnetic materials (drums) where
 documentation and/or physical evidence
 indicates their presence.

 Determine waste  fill  locations and
determine geologic strata.
Conduct magnetometer and/or
ground-penetrating radar survey.

Conduct electromagnetic
conductivity survey.
Geotechnical Investigation
 Evaluate the physical properties of
 geologic unit governing transport of
 cantaminants.

 Collect data on soil characteristics to
 determine if onsite soil can be used as
 fill material and to determine placement
of a potential cap or

 Identify offsite borrow-source for cap
 construction.

 Evaluate existing cap to determine
 physical properties.
Collect data on permeability,
porosity, hydraulic head, percent
organic carbon, etc.

Measure  soil characteristics such
as plasticity index, moisture
content, porosity, and
permeability.

Survey local areas for appropriate
material.

1) Collect data on permeability,
prmosity, and measure thickness.

2) Determine Atterberg limits.

3) Determine extent of vegetation
cover, any vegetative stress, and
erosion.

4) Monitor landfill settlement
(e.g.,  topographic  survey and
benchmark installation and
Survey).
Hydrogeologic  Investigation
 Determine depth of wells and screen
 intervals for existing shallow and deep
 wells.

 Identify and characterize hydrogeologic
 units.
Obtain soil classification or
     nc data.
                                                                            1) Drill brings around landfill for
                                                                            development of boring logs to
                                                                            better define the aquifers and con-
                                                                            fining layers; drilling through
                                                                            landfill contents may be conducted
                                                                            after evaluating health, safety, and
                                                                            other risks.

                                                                           2) Perform down-hole geophysical
                                                                            surveys.
                                                      2-32

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                                                 Table 2-4
                          PHASE I REMEDIAL INVESTIGATION OBJECTIVES FOR
                                      MUNICIPAL LANDFILL SITES*
                                                                                                 Page2 of 4
            Activity
                                                               Phase I Objectives
                                           (Activities Generally Performed After Work Plan is Approved)
              Objectives
                                                      Action
Hydrogeologic  Investigation
(Continued)
Determine direction of groundwater flow
and estimate vertical and horizontal
gradients.
                                   Determine rate of groundwater flow and
                                   evaluate the feasibility of groundwater
                                   extraction.
1) Install monitoring wells and
take water level measurements
from new and existing wells.

2) Investigate yield of private and
public wells.

Install monitoring wells and
perform hydraulic conductivity
tests on new and existing well;
check water levels at a maximum
of once  a month during the RI.
Meteorologiral Investigation
Determine prevailing wind direction and
air speed to evaluate remedial actions.
Collect and analyze wind speed
and direction data.
Chemical Investigation

  Groundwater
                                   Identify extent and type of groundwater
                                   contamination to perform an assessment
                                   of human health risks.
                                   Identify upgradient water quality for
                                   each geologic unit.
                                   Determine upgradient concentration.
                                   Determine source of groundwater
                                   contamination.
                                   Determine whether seasonal fluctuations
                                   occur in contaminant concentrations in
                                   the groundwater and in hydraulic
                                   characteristics.

                                   Evaluate feasibility of groundwater
                                   treatment systems.
                                         Install monitoring well in aquifers
                                         of concern; design monitoring well
                                         network to determine the extent of
                                         the plume (wells should also be
                                         located in "clean" area to confirm
                                         that the end of the plume is
                                         located both vertically and
                                         horizontally); collect and analyze
                                         samples.

                                         Install upgradient monitoring wells
                                         in aquifers of concern.

                                         Install monitoring wells upgradient
                                         of the landfill and collect and
                                         analyze samples.

                                         Collect and analyze groundwater
                                         samples and compare results to
                                         the landfill waste characteristics
                                         and background levels,

                                         Sample and analyze groundwater
                                         during different seasons.
                                         Obtain COD, BOD, metals, and
                                         other conventional water quality
                                         data.
                                                      2-33

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                                               Table 2-4
                       PHASE I  REMEDIAL INVESTIGATION OBJECTIVES FOR
                                    MUNICIPAL LANDFILL SITES*
                                                                                              Page 3 of 4
           Activity
                                                            Phase I Objectives
                                        (Activities Generally Performed After Work Plan is Approved)
                                               Objectives
                                                     Action
Leachate
Identify intent and o of leachate to
evaluate feasibility of groundwater
treatment system.

Estimate amount of leachate production
from landfill.
Collect and analyze leachate data.
                                                                         Install leachate wells in or around
                                                                         landfill and measure leachate
                                                                         head.

                                                                         Perform water balance calculations
                                                                         on landfill.
Surface Water and Sediment
                                 Determine viability of treatment
                                 technologies.

                                 Determine groundwater and surface
                                 water interactions during several periods
                                 during the RI,
                                 Determine background concentration of
                                 surface water and sediment.
                                 Determine surface runoff impact on
                                 surface water quality; determine the type
                                 and extent of contamination in nearby
                                 surface waters and sediments.
                                 Determine the absence or presence of
                                 contamination in onsite ponds,
                                         Collect field measurements on
                                         Redox  and  DO.

                                         Install staff gauges onsite, survey
                                        gauges, measure surface water
                                         levels and groundwater levels
                                         concurrently.

                                         Collect and analyze upstream
                                         water and sediment samples.

                                         Collect and compare up- and
                                         downgradient surface water to
                                         downgradient groundwater
                                         samples; also collect up- and
                                         downgradient sediment samples.

                                         1) Collect and analyze samples
                                         from nearest leachate seeps and
                                         compare to stream water quality.

                                         2) Collect and analyze surface
                                         water and sediment samples at
                                         increasing distances away from the
                                         landfill and compare results to
                                         landfill waste and background
                                         levels.

                                         1) Collect and analyze surface
                                         water and sediment samples for
                                         onsite ponds.

                                         2) Conduct toxicity testing
                                         (bioassay).
                                                    2-34

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Table 2-4
PHASE I REMEDIAL INVESTIGATION OBJECTIVES FOR
MUNICIPAL LANDFILL SITES*
Page 4 of 4
A c t i v i t y
Landfill Gas/ Air

Landfill Gas/Groundwater
Hot Spots
Environmental Evaluation
Phase I Objectives
(Activities Generally Performed After Work Plan is Approved)
Objectives
Identify areas within the landfill
containing high concentrations of
explosive or toxic landfill gas to perform
an assessment of human health risks due
to air toxics and explosive hazards, to
evaluate the feasibility of gas collection
and treatment, to evaluate need for
immediate action, and to evaluate other
remedial actions.
Estimate concentrations of selected
VOCs being emitted to the atmosphere.
Identify areas within the landfill
containing high concentrations of
explosives or toxic landfill gas to
determine if VOCs act or may act as a
source of groundwater contamination.
Investigate areal extent, depth, and
concentration of contaminants at hot
spots in the landfill's contents.
Delineate wetlands.
Determine impact of landfill on nearby
wetlands.
Describe aquatic and terrestrial
community in vicinity of site and aquatic
community downstream of site.
Determine impact of remedial action on
wetlands/flood plains.
Action
1 ) Obtain flow-related data from
existing and newly installed gas
vents, estimate emission rates, and
perform air modeling.
2) Obtain samples of landfill gas
from within the landfill using the
leachate headwell.
Collect and analyze ambient air
samples.
Obtain flow-related data from
existing and newly installed gas
vents, estimate emission rates, and
perform air madeling.
Collect and analyze samples from
potential hot spot areas
(documentation and/or physical
evidence must exist to qualify hot
spot as "potential"), with more
extensive sampling within
cnfirmed hot spot areas.
Conduct wetlands delineation
survey.
Collect and analyze surface water
and sediment from nearby
wetlands.
Collect or observe aquatic or
terrestrial organisms in the vicinity
of the site; conduct sensitive
receptor survey.
Delineate wetlands/flood plain
areas in vicinity of site.
*Refer to Section 2, Site Characterization Strategies, for an explanation of when these activities are appropriate.
2-35

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                                                     Table 2-5
                            PHASE H REMEDIAL INVESTIGATION  OBJECTIVES FOR
                                         MUNICIPAL LANDFILL SITES*
                                                                                                        Pagel of 2
           Activity
                                                                 Phase n Objectives
                                             (Activities Generally Performed After Work Plan is Approved)
                                                 Objectives
                                                            Action
Geophysical  Investigation
Further investigate probable presence of
buried ferromagnetic materials (drums).
 Excavate probable drum burial area.
Geotechnical Inestigation
Further evaluate the physical properties
governing transport of contaminants through
identified pathways.
 Collect additional data on perme-
 ability, porosity, hydraulic head,
 percent organic carbon, etc.; model
 pathways.
Hydrogeologic Investigation
Determine depth of wells and screen
intervals for existing shallow and deep wells.


Further identify and characterize hydro-
geologic  units.
                                 Further determine direction of groundwater
                                 flow and estimate gradients.


                                 Determine rate of groundwater flow and
                                 evaluate the feasibility of groundwater
                                 extraction.
 Obtain additional soil classification or
geologic data review Phase I RI
 results.

 1) Drill additional borings throughout
 site for development of boring logs to
 better define the aquifers and con-"
 figuring layers (health, safety, and
 long-term risk associated with drilling
 into the landfill should be weighed
 against the potential usefulness of the
 data for evaluating alternatives).

 2) Perform down-hole geophysical
 surveys, as appropriate.

 Install additional monitoring wells and
 take water level measurements from
 new and misting wells.

 Install monitoring wells and perform
 hydraulic conductivity and pumping
 tests on new and existing wells; check
 water levels at a maximum of once a
 month during the RI.
Chemical  Investigation

  Groundwater
                                 Identify extent and type of groundwater
                                 contamination to delineate plume.


                                 Redetermine upgradient concentration if
                                 Phase I results inconclusive.
                                 Further determine whether seasonal
                                 fluctuations occur in contaminant
                                 concentrations in the groundwater and in
                                 hydraulic characteristics.

                                 Further evaluate feasibility of groundwater
                                 treatment systems.
                                              Install additional monitoring wells in
                                              aquifers of concern; collect and
                                              analyze samples.

                                              Install additional monitoring wells
                                              upgradient of the landfill and collect
                                              and analyze samples.
                                             Sample and analyze groundwater with
                                             additional rounds of sampling from the
                                             same location(s).
                                             Obtain additional COD, BOD, and
                                             other conventional water quality data;
                                             initiate treatability studies, as
                                             necessary.
                                                       2-36

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                   Table  2-5
PHASE II REMEDIAL INVESTIGATION OBJECTIVES FOR
          MUNICIPAL LANDFILL SITES*
                                                          Page 2 of 2
Activity
Surface Water and Sediment
Landfill Gas/ Air
Landfill Gas/Groundwater
Environmental Evaluation
Phase II Objectives
(Activities Generally Performed After Work Plan Is Approved)
Objectives
Further determine effect of groundwater on
surface water.
Campare additional stream and water levels
during several periods during the RI.
If initial results are inconclusive, identify
additional areas within the landtill containing
high concentrations of explosive or toxic
landfill gas to perform an assessment of
human health risks due to air toxics and
explosive hazards, to evaluate the feasibility
of gas collection and treatment, and to
evaluate other remedial actions.
If initial results are inconclusive, identify
additional areas within the landfill containing
high concentrations of explosives or toxic
landfill gas to determine if VOCs act or may
act as a source of groundwater
contamination.
Describe aquatic and terrestrial community
in vicinity of site and aquatic community
downstream of site on a seasonal basis.
Action
Collect and compare additional up-
and downgradient surface water and
sediment samples to downgradient
groundwater samples.
Install additional staff gauges onsite,
survey gauges, measure surface water
levels and groundwater levels
concurrently.
Obtain additional flow-related data
from existing and newly installed gas
vents, intimate emission rates, and
perform air modeling.
Obtain additional flow-related data
from existing and newly installed gas
vents, estimate emission rates, and
perform air modeling.
Collect or observe aquatic or
terrestrial organisms in the vicinity of
the site on a seasonal basis.
*Refer to Section 2, Site Characterization Strategies, for an explanation of when these activities are appropriate.
                     2-37

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            Review  precision,  accuracy,
            representativeness, completeness,
            and   comparability (PARCC)
            parameters

  •    Stage 3. Design data collection program

            Assemble data
            Design program

Although the  elements of Stage  1 can  be
thought' of as distinct steps, they are continuous,
incorporating  additional  information as  it
becomes available. DQOs should be under-
taken in an interactive  and iterative  manner;
DQO elements are continually reviewed and
evaluated as data are compiled

The  output  of the DQO process is a well-
defined SAP, with summary information pro-
vided in the  project work plan. Documentation
is  supplied, detailing  the types of  samples
believed to  be necessary for  each matrix to
obtain sufficient representation of site condi-
tions. The  desired PARCC of the  chemical
analyses are also  documented.

Before the DQOs are developed, a detailed list
of potential ARARs specifying the  required
chemical concentrations should be prepared. In
addition, a preliminary risk assessment may be
conducted and chemical concentrations relating
to a 10"4to  10"6risk  range should  be deter-
mined. The  purpose of the ARARs  and risk
assessment  information  is to  determine  the
contaminants of concern and the required ana-
lytical detection limits.  These ARARs should
include both federal and state  requirements,
because some  states may have their own more
stringent standards. The detection limits noted
during the assembly of the ARARs should be
incorporated in the DQOs.

A  combination of laboratory services may be
used to achieve the DQOs so that time and
money are used efficiently. There are five levels
of data methodologies and associated quality
control that can be used during an RI:

  •    Level I is the lowest quality  data but
       provides the fastest  results.    Field
       screening or analysis provides Level I
       data. It can  be used  for health and
       safety   monitoring   and  preliminary
       screening of samples to identify those
       requiring confirmation sampling (Level
       IV).  The generated data can  indicate
       the presence or absence of certain con-
       stituents  and  is generally qualitative
      rather than  quantitative.  It is the least
      costly of the analytical options.

  •    Level II data are  generated by field
       laboratory  analysis  using more-sophisti-
       cated portable analytical instruments or
       a mobile laboratory onsite.  This pro-
       vides fast results and better-quality data
       than in  Level I. The  analyses can be
       used to  direct, a removal action in an
       area, reevaluate sampling locations, or
       direct installation of a monitoring well
       network.

  •    Level III data may be obtained by  a
       commercial laboratory with or without
       CLP procedures. (The laboratory may
       or may not participate  in the  CLP.)
       The  analyses  do not usually  use the
       validation or documentation procedures
       required of CLP Level IV analysis. The
       analyzed parameters are relevant to the
       design of the remedial action.

  •    Level IV data are used for risk assess-
       ment, engineering  design,  and  cost-
       recovery  documentation.   All  analyses
       are performed in a CLP analytical labo-
       ratory  and follow CLP  procedures.
       Level IV is characterized by rigorous
       QC  protocols,  documentation, and
       validation.

  •    Level V data are those obtained by
       nonstandard   analytical  procedures.
       Method development or modification
       may  be required for specific constituents
       or detection limits.

  •    Other.    This category  includes data
       obtained from analyses of the physical
       properties  of  soil,  such  as  Atterberg
       limits and soil moisture.

Tables 6-1  through 6-3 in Appendix A of this
report present an example  of a DQO summary
for an  example landfill site. The  analytical
levels are mixed to provide an optimal analyti-
cal program.   For example, in  the  case  of
                                             2-38

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groundwater, Level I data can consist of screen-
ing for volatile organic compounds  (VOCs)
using a photoionization detector, and Level III
can be obtained from analyzing for parameters
needed for treatment such as iron and manga-
nese.  Level II data can consist of analysis of
the groundwater by an onsite mobile laboratory.
placement of the monitoring wells can then be
readjusted in the field, if necessary.  Level IV
data would provide the results of site character-
ization and risk assessment.   Level V data
would be obtained for chemicals such as vinyl
chloride (for vinyl chloride, the detection limit
required  for risk  assessment, based on a 10"6
cancer risk, is  lower  than  the detection  limit
established in CLP methodology).

The first phase of DQO  development is com-
plete once the field program has been defined.
The RI tasks necessary to  achieve the DQOs
must be specified in the work plan and may be
altered or redefined, depending on the results
of fieldwork. Additional information on DQOs
can be found in  the  documents titled Data
Quality Objectives for Remedial Response Activi-
ties, Volumes I and II (U.S. EPA, 1987b and
U.S. EPA, 1987c).
      2.11  Section 2 Summary

This section illustrates the key components of
scoping an RI/FS for a  CERCLA municipal
landfill site. The primary purpose of scoping an
RI/FS is to divide the broad project goals into
manageable tasks that can be performed within
a reasonable period of time.  The broad project
goals for an RI/FS at any Superfund site are to
provide the information necessary to character-
ize the site, define site dynamics, define risks,
and  develop  a remedial  program to  mitigate
potential adverse public  health and  environ-
mental impacts.  To obtain the necassary data
to achieve these goals, Section 3 presents vari-
ous site-characterization strategies and the asso-
ciated field tasks for municipal  landfill  sites.
                                             2-39

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                                         Section 3
               SITE CHARACTERIZATION STRATEGIES
Once a work  plan has  been developed, field
activities are undertaken to further characterize
the site. The purpose of site characterization is
to assess  the  risks to human health and the
environment posed by the site and to develop a
remediation strategy to  mitigate these current
and potential threats.

As described in Section 2, site characterization
begins with art evaluation of previous data and
analytical  results. This information is combined
with field  investigations to fill in data  gaps and
to test hypotheses about the site developed
during scoping. In this section, characterization
activities  are described by the different media
that might be contaminated by a municipal
landfill site, and different site characterization
strategies  for  two  types of municipal landfill
sites are discussed.

Most municipal landfill  sites on the NPL are
co-disposal facilities that may or may not have
known or suspected  hot spots. Hot spots con-
sist of highly toxic and/or highly mobile material
and  present  a potential principal  threat to
human health  or the environment (see 40 CFR
Sec. 300.430 (a)(l) (iii)(C)). Excavation or treat-
ment of hot spots is generally practicable where
the waste  type or mixture of wastes is in a dis-
crete,  accessible location of a  landfill. A hot
spot should be large enough that its remedia-
tion will significantly reduce the risk posed by
the overall site, but small enough that it is rea-
sonable to consider removal  and/or treatment.

The two principal types of municipal landfills
are as follows:

   .Landfill   Type  I.   This is a co-disposal
       facility where records or some other form
       of  evidence  indicate that hazardous
      wastes were disposed of with municipal
       solid wastes.  There are  no known or
       suspected hot spot areas, and historical
       records  and physical  evidence,  such as
       aerial photographs and the site visit, do
       not document  any discrete subsurface
       disposal areas.
  .Landfill Type II.  This is a  co-disposal
      facility where approximate locations of
      hot spots are known or suspected, either
      through  documentation, physical  evi-
      dence, or consistent employee/resident
      interviews.    Small-  to moderate-sized
      landfills (for example, less than 100,000
      cubic yards) that pose a principal threat
      to human health and the environment
      are included in this group because it may
      be appropriate to consider excavating
      and/or treatment of the contents of these
      landfills.

Placing municipal landfill sites into these two
categories allows more  efficient characterization
through avoidance of extensive and unnecessary
sampling, and streamlines the RI/FS process. It
should be  noted that the distinction between
these landfill types will not always be clear.
Therefore,  the  application  of the approaches
described below should be flexible  and  adapted
to the specific site characteristics.

In general, categorizing landfills into different
types allows the site characterization to focus
on detecting and then characterizing hot spots.
Because there are no known or suspected hot
spots, the feasibility study for Landfill Type  I
can focus on capping alternatives as part of an
operable unit.   This focused feasibility study
could precede  or be conducted  concurrently
with the groundwater investigation, particularly
at sites where  leachate is  not a problem. At
Landfill Type II, more effort can be expended
on characterizing and remediating the hot spots.
At these sites, the feasibility studies can focus
on the operable units and remedial action alter-
natives for  these units.

Site characterization strategies for the  landfill
types are described  below by medium.   The
focus of the descriptions is primarily on those
media most often  requiring remediation  at
municipal landfill sites (e.g., groundwater, leach-
ate, landfill contents/hot spots, and landfill  gas).
Other areas such as wetlands, surface water, and
sediments are also discussed, but in less detail,
since the nature of contamination is not unique
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to municipal landfill sites and information is
readily  available  from other sources.    The
descriptions were prepared as if the site investi-
gations  were done in only one medium.  How-
ever,  at most sites, this will not be the case.
The user should read all descriptions applicable
to the site, arid coordinate sampling and investi-
gation  efforts  as  described in  Section 2.10,
Development of DQOs. Sample requirements
should be reviewed in all media of concern to
determine  the  most  efficient  and  concise
method  of obtaining data.

Site  characterization efforts may  generate  a
large  amount of data. Organization of the data
is essential to proper interpretation.  During
planning of surveys or well installations, consid-
eration  should be given to data organization-
mapping, geologic cross sections, grid points,
etc.-as  well  as to organization of results from
field instrument analyses.
           3.1  Groundwater

Characterizing a site's geology and hydrogeology
as well as  developing an understanding of the
regional geology and hydrogeology is paramount
to the site characterization process. Data gath-
ered for site characterization of geology  and
hydrogeology significantly affect the selection of
an  appropriate remedial action strategy.  The
type of cap selected, the location of the ground-
water extraction system and amount of ground-
water extracted, and the necessity for collecting
and treating landfill gas are all affected by the
geology and hydrogeology of the site. General
procedures  for Phase I and Phase II site charac-
terizations of regional  and site-specific geology
and hydrogeology  are described below. More
specific information on placement of monitor-
ing  wells  by  landfill  type  is  given  in
Section 3.1.3.

All Phase I and Phase  II characterization activi-
ties can be done at both types of landfill sites.
Depending on the type and quality of data gath-
ered both before and during development of the
RI/FS work plan, some of these acclivities  may
have been performed. Further information on
characterizing site  hydrogeology is available in
Guidance on Remedial Actions for Contaminated
Groundwater at Superfund Sites (U.S. EPA,
1988e).

3.1.1 Groundwater Investigations

The characterization   of the groundwater
beneath and near a site is often completed in
two phases.   The initial  site characterization
study is based on a review of existing literature
describing the regional and local geology and
site history.    This literature  includes  local
government  records  and aerial photographs.
The second  phase is based  on the review of
existing  literature  and is used to  design  a
sampling  and monitoring program  to  answer
questions  developed during the first phase.

The initial characterization of the hydrogeology
and the groundwater conditions (done before or
during the limited field investigation) depends
on  an understanding of the relationship of the
site geology and groundwater flow characteris-
tics. At a minimum, a description of the site
geology should include the lithology of geologic
units underlying the site that are contaminated
or used as Class I or II aquifers, and the rela-
tionship among the units.

3.1.1.1 Phase I Site Characterization

In Phase  I,  geological information about the
area, gathered during the limited field investiga-
tion, and intrusive activities such as drilling and
geophysical surveys (described in further detail
in Section 3.2) is reviewed. The data gathered
for the Phase I site characterization should be
sufficient  to provide a general understanding of
the hydrogeological regime of the region and its
relationship  to the  landfill.  The information
should give a general picture of the local stra-
tigraphy,   depositional environments  of the
strata, the tectonic history  as it relates to tilting,
folding,  or  fracturing of the  strata present,
groundwater  depth and flow direction, the units
that are contaminated or  used as Class I or II
aquifers, and local groundwater uses, including
the effects of pumping (withdrawal). After this
information has been gathered and reviewed, a
regional conceptual model of the hydrogeology
should be developed (see Section 2.5). Future
field investigations are based  on this model and
are developed to fill in the  data gaps and to
answer hypotheses  presented by the  model.

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This conceptual model is revised as new infor-
mation is developed from the field investigation.

A limited number of boreholes with wells and
piezometers monitoring discrete water-bearing
zones should be installed during the Phase I site
characterization. For characterization purposes,
it may  be useful if at least one  borehole is
drilled into the  first confining layer beneath the
uppermost aquifer (water table  or unconfmed
aquifer).    Boreholes  and  monitoring wells
should be  drilled at the site in numbers and
locations sufficient to characterize  the geology,
water levels, and  groundwater flow beneath the
site. Sufficient borings and wells should  be
installed to permit the construction  of meaning-
ful  geologic cross sections. The density of data
points   should describe   the relationships
between geologic and hydrologic conditions.
For example, if groundwater flow  is controlled
by fractures in tilted strata, a sufficient number
of wells should intersect or cross the fractured
strata.

Information derived from the borings should be
sufficient to:

  • Correlate  stratigraphic units

  • Identify zones of possible high hydraulic
      conductivity

  • Identify confining layers

  * Identify any unusual or unexpected geo-
      logical features such as faults, fractures,
      facies changes, solution channels, etc.

In some cases, samples should be collected to
test for geotechnical and geochemical parame-
ters.    Tests could include cation exchange
capacity if metals contamination  is expected,
bulk density and moisture  content for treatment
characteristics, permeability and  porosity for
containment or extraction  effectiveness, and
analytical parameters (e.g.,  TAL metals, TCL
organics) for contaminant  fate and transport.

Each boring should be  documented with  a
boring log that  describes:

  • Soil classifications or rock types
   •  Structural features such as fractures and
      discontinuities

   •  Depth to water

   • Depth  of  boring   and  reason  for
      termination

   •   Development of soil zones and vertical
      extent

   • Any evidence  of contamination

   •  Geotechnical  information such as blow
      counts, color, grain-size distributions, and
      plasticity

   •  Well construction details (if boring is
      finished as a  monitoring well)

At least the first borehole should be sampled
continuously  to determine if the  subsurface
materials  are  variable.   Samples should  be
collected  from every  significant stratigraphic
contact and formation, especially the confining
layers. Subsequent borings may be sampled at
predetermined intervals that are justified based
on the subsurface characteristics. All boreholes
in which piezometers  or monitoring wells are
not installed must be properly abandoned. Soil
samples should be described  by a  qualified
geologist,  geotechnical  engineer,  or  soil
scientist.

Groundwater  quality samples that identify the
extent and type of contamination should  be
collected in the aquifer of concern. The aquifer
of concern is  the unit where contamination is
known or  suspected or one that is  used as a
Class I or II aquifer. Upgradient water quality
for the aquifers of concern should also be estab-
lished.  Seasonal fluctuations in contaminant
concentrations should be  determined.   Well
pairs may be required to determine the vertical
direction of flow between the water table and a
lower  aquifer. The deep well of the pair can
also  determine if the contamination has entered
a lower aquifer. Wells penetrating lower aqui-
fers must be constructed with  care so that they
do not become  conduits for contamination. If
such wells are intended only to determine the
hydraulic  relationship between two aquifers,
they should not  be  placed downgradient from a
potential contaminant source. They should only
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be placed downgradient from a source if the
hydraulic relationships of that area may be
different than at other locations or if contami-
nation is suspected or documented.

The  Phase  I  site characterization should be
flexible to accommodate revisions to the scope
as information becomes available.  For example,
groundwater sampling results may be obtained
with, a fast turnaround time during the Phase I
field activities. This would allow refining the
investigation program in the field to delineate
contamination and possibly  limit the need or
extent of a Phase II investigation.

3.1.1.2 Phase H Site Characterization

Phase II site characterization is warranted if the
data  obtained in  Phase I are insufficient to
assess risks to human health and the environ-
ment, and to develop  and evaluate remedial
action alternatives. If the information obtained
in Phase I cannot answer  questions on the
direction and rate of groundwater flow, effec-
tiveness  of an observed or presumed aquiclude,
extent of observed contamination,  or location of
known or presumed contamination, a Phase II
site characterization is necessary. For instance,
descriptions from the boring logs may indicate
that a confining layer is possibly continuous
across the site,  but aquifer tests or analytical
data indicate that the confining layer is discon-
tinuous. In this case, additional borings, wells,
and  aquifer tests may be necessary to resolve
the conflicting data.

Phase II site characterizations are also necessary
if previously unknown hot spots are detected
during the Phase I site activities and additional
borings or wells are beyond the capability of the
driller.    Data should be  obtained  during
Phase II site characterization activities to place
the hydrogeology of known and newly discov-
ered hot spots in context with the geology of
the site and region.

During  this phase, the compatibility  of the
naturally occurring clay minerals and other rock
and  soil-forming materials  with any  known
chemicals in the landfill should be examined.
Soil  and rocks with a high  carbonate content
will be attacked by acids, increasing their per-
meability.   Clays similar to bentonite  can be
ineffective  barriers to the migration of some
organic compounds. Laboratory determination
(X-ray diffraction) of the clay  types may be
necessary.

Data gathered during Phase II  site characteriza-
tion activities should primarily be directed
towards identifying potential targets and opti-
mizing  the analytical program.   Additional
monitoring wells  should be installed,  and
groundwater and leachate samples  should be
collected from areas where Phase  I activities
indicate that  contamination has spread or is
spreading.  Sampling in "clean" areas should be
minimized unless  Phase I activities did  not
adequately  define these areas. Monitoring wells
are needed to identify the limits of the plume,
and as such, would be at the end of the plume
in areas considered "clean." Additional piezo-
meters  can be  installed if groundwater and
leachate rate and flow  direction need to be
clarified for modeling and descriptive purposes.

If the necessary  characterization  is largely done
during Phase I activities, then fewer boreholes
and less additional indirect investigation will be
necessary during Phase II activities. Placement
of boreholes, piezometers, and  monitoring wells
should be  carefully reviewed  so that essential
information  on  leachate and groundwater is
collected. Drilling an excessive number of bore-
holes will not necessarily provide useful infor-
mation on the site's hydrogeology. Additional
information on placement of monitoring wells is
provided in Section 3.1.3.

3.1.2 Data Requirements

A detailed description of groundwater remedial
action alternatives for municipal landfill sites
can be found in Section 4.5: To evaluate the
various remedial action alternatives, data gath-
ered before or during the site characterization
of groundwater should include:

   • The   regional  geologic  regime  and
      regional groundwater flow direction

   •  A hydrogeologic investigation to charac-
      terize the groundwater aquifer including
      the depth to water, flow  direction, flow
      rate, the extent and nature of confining
      layers, fractures, and any potential path-
      ways for contaminant  migration at the
      site
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   • Location of site-specific items of interest
      such as outcrops, springs, seeps, leachate
      outbreaks, and surface drainage features

   •  The compatibility of the suspected con-
      taminants with naturally occurring mate-
      rials at the site

   •  Identification of actual  or potentially
      useable aquifers (e.g., Class  I and Class II
      aquifers) and water-bearing units  and
      their physical properties (including link-
      age between aquifers)

   •   Climatic  and topographic conditions
      affecting groundwater recharge and dis-
      charge,  erosion, flooding,  and  surface
      water conditions of interest

   •  Identification  of potential pathways  for
      contaminant migration

   •   Geologic  conditions,  hazards,  or con-
      straints that could  contribute  to offsite
      contaminant  migration  or that  might
      preclude certain remedial alternatives

   •  Site-specific analysis such  as BOD and
      COD (see Section 4.5)

3.1.3 Placement of Monitoring Wells

3.1.3.1 Objectives

The objective of installing monitoring wells is
to determine if the landfill  has  affected  the
groundwater system. Monitoring wells are used
to:

   • Determine subsurface conditions, includ-
      ing confining layers and zones of high
      permeability

   •   Determine    background  (upgradient)
      water quality

   •   Locate contaminant plumes

   •  Characterize groundwater contaminants

   •  Characterize hot spots
Because there  are many uses for  monitoring
wells at municipal landfill sites, there are no
simple procedures for determining  appropriate
placement.  Simple geology  characterized by
horizontal,  thick, homogeneous,  unfractured
strata tends to  reduce the number of soil bor-
ings and monitoring wells. More complicated
geology, including fractured, tilted, folded, thin,
or heterogeneous  geologic  strata tends  to
increase the number of soil borings and moni-
toring wells necessary to adequately characterize
a site. Landfill conditions that lead to more
detailed investigations include known locations
of the disposal  of hazardous wastes and loss of
containment (liner or slurry wall) integrity.

3.1.3.2 Procedures

Landfill  Type I.  This  is a municipal  landfill
where co-disposal of  hazardous and municipal
wastes occurred, but the disposal in a  discrete,
accessible location of highly toxic and/or highly
mobile material that presents a potential princi-
pal threat to human health or the environment,
is not known.   The presence of hazardous con-
stituents in the  groundwater is a concern at this
type of landfill.  The number of wells should be
determined on  a site-specific basis.

Upgradient Monitoring Wells. The number of
wells increases with the complexity  of site
geology and landfill design or history.  Upgrad-
ient  monitoring wells should be in a "clean"
area so that they may  provide representative
background groundwater quality in the aquifer
of concern. They should be  screened in the
same strata as the downgradient  monitoring
wells unless the bedrock dips  steeply or rock
types change rapidly across the site. Location
of the monitoring wells should also consider
groundwater and contaminant velocity at the
site.  Groundwater that moves slowly and where
the  contaminants are widely dispersed will
require  careful  location of upgradient wells to
avoid" the plume.  The location of upgradient
monitoring wells  should  consider surface water
or agricultural and industrial activities that may
be affecting the groundwater quality upgradient
of the landfill.  A preliminary estimate of con-
taminant travel distances should be  determined
so initial well  installation approaches can  be
determined.
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Downgradient Monitoring Wells. Downgradient
monitoring wells should be  near the  landfill
boundary and  in the  saturated  zone.  If the
landfill lies above the saturated zone, the leach-
ate migration  pathway  to the  groundwater
should be considered before monitoring well
placement is  determined. In cases where com-
plex interbedding,  especially of alluvial deposits,
underlie the landfill, additional monitoring wells
may be  required.  It should also be recognized
that glacial  stratigraphy  can also be very
complex.

Downgradient monitoring wells should be
located  along any zone that may offer prefer-
ential groundwater  movement. Geologic  fea-
tures such  as solution  channels, faults, or
permeable  linear sand lenses should  also be
considered in downgradient  monitoring well
placement,  since these  features can  act as
groundwater  conduits.    Other features  that
affect the placement of downgradient moni-
toring wells include fill areas, buried pipes and
utility trenches, areas with high hydraulic gradi-
ents,  and  areas  with  high  groundwater
velocities.   Placement of downgradient moni-
toring   wells  should  also  consider low-
permeability zones associated with such  features
as clay  lenses, dense bedrock, and glacial till
that can differentially retard groundwater flow.

The use of field data or rapid turnaround  data
from a  nearby laboratory  can provide useful
information  in the placement of monitoring
wells. For example, an onsite laboratory could
be used during well installation to provide  ana-
lytical results that would be used to reevaluate
the  proposed   monitoring   well  network.
Groundwater samples could be  analyzed for
selected VOCs and inorganic anions to aid in
determining  the  extent  of the  groundwater
plume.  Inorganic anions such as chloride and
sulfate are persistent chemicals that can  be used
as indicators of contaminant transport. There-
fore, mapping elevated levels  of these indicator
chemicals relative to upgradient concentrations
can give a more accurate picture of the extent
of the groundwater plume than just VOC analy-
sis. Because of volatization,  adsorption,  and
degradation, VOCs may diminish in concentra-
tions more rapidly than the inorganic ions.
Other Monitoring Wells. Additional monitor-
ing wells need to be installed and sampled to
determine the integrity of any confining layers
and to determine whether the  confining layer is
continuous or breached.   Where a confirming
layer exists, monitoring wells should be installed
in the area in order to assess vertical flow
between  the upper and lower aquifer,  and the
groundwater flow in the lower aquifer. In gen-
eral, numerous boreholes or wells through con-
fining layers should be avoided when the  site
conceptual model indicates  a very low potential
for contamination of the underlying aquifer.

Monitoring  Well Screen Placement. Monitor-
ing wells should be completed in the first aqui-
fer encountered beneath the landfill and other
discrete  zones beneath.   That aquifer will
usually be unconfined at the landfill location.
The nature of the  suspected  contaminants
should be used to determine the ideal screen
location  in  the  aquifer. Most typical  landfill
contaminants are soluble enough to be detected
by laboratory instruments, so screening in the
upper portion of the aquifer should detect  any
contamination present.

If a highly variable geology  exists at the site,
each  screen should be open  only  to one stra-
tum.  If  a screen  is open to more than  one
stratum, contaminants  may  move to uncontami-
nated zones, and the actual zone of contamina-
tion will be  impossible to determine. A typical
screen length is 5 feet, but longer screen lengths
are required in zones of very low permeability
or where water  levels are known to change over
great  intervals.  Generally, screens should be no
longer than 20 feet.

If the contaminant is  a dense, non-aqueous
phase liquid (DNAPL), the screens must moni-
tor the bottom of the first aquifer. If this dis-
tance is excessive, several monitoring wells with
overlapping  screens  are  typically  installed.
DNAPL migration  is generally controlled by the
top surface  of the  confining layer, and is little
affected  by  the hydraulic gradient. Additional
monitoring wells and boreholes may be required
to define this  surface.  A  DNAPL  will enter
deeper aquifers if breaches  in the  confining
layer are encountered.  DNAPLs may  move
through  clays  at  order-of-magnitude greater
velocities than water.  Monitoring wells should
                                              3-6

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be placed in the lower aquifer to determine the
hydraulic gradient between the two aquifers,
and to determine if contamination has reached
the lower aquifer. DNAPLs can migrate to the
bottom of the lower aquifer, but often this dis-
tance is great and the nature and topography of
the underlying aquitard are  difficult to define.

The viscosity and dispersivity of the contami-
nant should also be considered during monitor-
ing well screen placement.   A highly viscous
liquid will migrate very  slowly in the subsurface.
Its movement may be affected more by capillary
attraction than by normal  factors of gradient
and hydraulic conductivity.  A highly  dispersive
compound,  on the other  hand,  can migrate
quickly by  dispersion and extend  downgradient
much  faster than  the  gradient and  hydraulic
conductivity  indicate.

Organic contaminants that are less dense than
water may be detected with screens that extend
from at least 5 feet above the saturated zone to
about  15 feet into the  saturated zone.    This
detects any floating, non-aqueous phase con-
taminants. Screen openings should be confined
to a single stratum.

Landfill Type II. The principal concern at this
type of landfill is the known or suspected hot
spots.  Monitoring well and screen placement
described for Landfill Type I can be employed,
but  additional monitoring wells  should  be
placed downgradient of all confirmed hot spots.
(The presence of hot spots is confirmed using
the geophysical survey procedures described in
Section 3.2.)

Hot spots  should be treated as  unique sites
within the landfill.    The hot spot may  be
isolated with up-  and  downgradient monitoring
wells within the  landfill. Test pits should be
installed in such areas to investigate the subsur-
face materials.  This will restrict remediation to
a smaller area.  Care must be exercised because
drilling through the landfill to install the moni-
toring wells could compromise the integrity of
any liners, puncture isolated drums, or pene-
trate a gas pocket,  causing an explosion hazard.
Also, because of the nature of landfill material,
the integrity (or quality) of sampling locations
within the landfill is unknown.
3.1.3.3 Guidelines

The summary documents presenting the data
should contain concise, narrative descriptions of
the data but must rely on clear, detailed figures
to present the spatial relationships of ground-
water, geology, and the landfill. Geologic cross
sections based on the boring logs must depict
all  significant soil and rock units, geological
structures, zones of high permeability and con-
fining  layers present, and the  depth to  water
and the unconfined and confined water levels.
The locations of all borings should be displayed
on  an appropriate map. The lines of the cross
sections should be shown, and surface features
should be located on the cross sections.

A map showing the monitoring well locations
should also be prepared. The map can display
water levels and  develop water level contours
and show groundwater flow direction, ground-
water divides, recharge, and discharge areas. In
cases where more than one aquifer exists, the
map can also be used to show the direction of
vertical groundwater flow.

3.1.4 Groundwater Summary

Table 3-1 summarizes the conditions that deter-
mine monitoring well locations and numbers.
A flowchart summarizing the decisions neces-
sary to  determine sampling  and monitoring
locations is presented in Figure 3-1. The deci-
sion points illustrated across The top  of the
figure  must be considered separately in  deter-
mining  monitoring well  placement.     For
instance, a determination  of where  to  place
upgradient  monitoring wells does not eliminate
decisions on where to place wells to character-
ize zones of permeability.

The Phase  I and Phase II site characterizations
apply to both landfill types as well as other
NPL sites. Placement and number of monitor-
ing wells vary according to the size of the site,
the geology of the area, and the type of landfill.
              3.2  Leachate

The main factor contributing to leachate quan-
tity is  infiltration. However,  other factors—
                                              3-7

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Table 3-1
CONDITIONS THAT DETERMINE MONITORING WELL LOCATION AND NUMBERS
Conditions
Landfill in saturated zone
Landfill above saturated zone
Landfill in vadose zone
Interlayered confining layers
Breached or continuous
confining layer
No upgradient contaminant
source
Upgradient contaminant
sources
Monitoring Well Location
Downgradient near landfill boundary but
along zones of high hydraulic conductivity,
including hot spots.
OR
If no zones of high permeability, near
downgradient boundary of landfill or near
confirmed hot spot.
Possibly at some distance from downgradient
landfill boundary or hot spot-depends on
subsurface features controlling fluid
movement in vadose or saturated zone.
OR
If homogeneous geology, downgradient in
uniform array.
Intercept leachate downgradient.
Top of each confining layer downgradient.
Top of confining layer and in next lower
aquifer downgradient.
Upgradient of landfill boundary -distance
depends on groundwater velocity and
contaminant dispersivity~in same strata as
monitoring wells on downgradient side of
landfill or as required by geology.
Near potential source and upgradient of
landfill and downgradient of source~in same
strata as monitoring wells on downgradient
side of landfill or as required by geology.
Number of Monitoring
Wells
High.
Moderate.
High.
Moderate to high.
Moderate.
At least one per confining
layer.
At least two.
Relatively few~at least one,
probably more.
One per source and per
strata.
3-8

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'DMAPL • Dfraar tun wain. noo-aqjMus phase iqud
                                                                                                Figure 3-1
                                                                                                LOGIC DIAGRAM FOR MONITORING
                                                                                                WELL AND SCREEN PLACEMENT

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including groundwater  and surface  water
recharge and the water  generated  as  part of
refuse decomposition—all  contribute  to the
quantity  of leachate generated. Leachate pro-
duction  generally  follows a cyclic pattern
depending on local rainfall, runoff, and evapo-
transpiration rates.  Leachate typically carries
many suspended and dissolved materials; the
specific nature and concentration depend on the
landfill history as well as its degradation stage.
Typical  leachate  concentration ranges are
presented in Table  3-2.    The large ranges
presented may be due in part to analysis of
leachate  diluted  by groundwater. Additional
information on leachate composition and con-
taminant  concentrations in  leachate  can  be
found in Characterization ofMWC Ashes and
Leachates from MSW Landfills, Monofills and
Co-Disposal Sites (U.S. EPA, 1987fj.

Leaching is a contaminant release mechanism,
potentially transporting contamination to onsite
and offsite groundwater  through  groundwater
movement, or  to onsite surface  water, sedi-
ments, and nearby wetlands by recharging due
to leachate seeps. Leaching is usually the con-
taminant release method  of greatest concern at
landfill sites.

3.2.1  Leachate Investigations

3.2.1.1 Objectives

The objectives of leachate investigations are  to:

   .Determine  location of leachate seeps

   •   Determine  chemical characteristics of
      leachate

   .Locate potential  source areas  (in situa-
      tions where there are no known or sus-
      pected hot spots, the entire landfill may
      be  considered  a  source)

   .Determine   leachate   impact  on
      groundwater

Leachate samples may be analyzed to confirm
or complement data obtained from  analysis of
groundwater and soil samples.
3.2.1.2 Procedures

Landfill Type 1. Type I landfills include those
landfills where a combination of municipal and
hazardous wastes  have been co-disposed. At
these types of landfills, discrete hot spot loca-
tions are  neither  known  nor  suspected.  At
these sites, a water balance identifying water
sources and discharges should be performed for
the entire site to estimate annual leachate pro-
duction. Leachate  collection locations should,
be identified for sampling.  The  location where
leachate discharges ultimately depends on the
site's physical and  geological characteristics. In
most cases, at least part of the leachate  that
discharges  from the landfill migrates into  the
underlying groundwater system. In this case,
leachate acts as groundwater recharge and its
detection and collection can become very diffi-
cult. The actual zone depends  on the perme-
abilities of the materials involved  and in their
specific gravities, mixing (turbulent versus lami-
nar flow),  and diffusion.    Where underlying
refuse, soil, or rock strata are impervious, leach-
ate will discharge  or the surface either at the
landfill toe  or somewhere on the slopes.

At both landfill types, it may be necessary to
sample the surface waters.  Leachate can move
laterally below ground toward  a  creek or
stream,  affecting the water quality.   Samples
should be collected both upstream and down-
stream of  the  site to  monitor this  situation
properly. At other sites in  which the  refuse is
deposited on impervious clays  and in areas of
high precipitation, the leachate  cart outcrop at
the top and sides of the fill and flow with the
surface runoff directly to a receiving water body.
Samples should be  collected at the  leachate
seep and upstream of the seep.

When a number of seeps are  present in  the
same area,  compositing of samples from these
seeps may be appropriate in some limited cases.
The advantage of compositing is that  the costs
of analysis, data validation,  and  database activi-
ties are lowered while not eliminating  sampling
of any of the seeps. The disadvantage is that
information on the  individual seeps  is not avail-
able. Compositing would not be appropriate if
significant differences in leachate composition
are expected.
                                             3-10

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Table 3-2*
RANGE OF TYPICAL DOMESTIC REFUSE
LEACHATE CONSTITUENT CONCENTRATIONS
Constituent
Iron
Zinc
Arsenic
Lead
Phosphate
Sulfate
Chloride
Sodium
Nitrogen (Kjeldahl)
Hardness (as CaCOs
COD
BOD
TOC
IDS
TSS
Total Residue
Nickel
Copper
pH
Concentration Range Per Liter
(mg)
200-1.700
1-135
0-70
0- 14
5- 130
25-500
100-2,400
100-3,800
20-500
200-5,250
0-750,000
9-55,000
5-30,000
0-51,000
2-140,000
1,000-45,000
0,01 -0.8
0.10 -9.0
4.00 -8.5
*From Characterization of MWC Ashes and Leachates from MSW
Landfills, Monofills, and co-Disposal Sites (EPA, 1987f)
3-11

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When, collecting samples, field observations can
be used to determine if samples from adjacent
locations can be composite, into one  repre-
sentative sample.  Samples from leachate seeps
that are near each  other can be  composite if
they 1) are  similarly colored, 2)  have similar
liquid  phases,  and 3) appear similar when
scanned with field instruments., Samples from.
opposite sides  of the  landfill  should not be
composite.   Further  information on leachate
sampling methods is available in Volumes I and
II of EPA's A Compendium of Superfund Field
Operations Methods  (EPA, 1987h).

If available, samples should also be collected
from leachate collection drains and/or extrac-
tion wells using pumping or bailing, except for
VOCs which must be collected using a bailer.
Samples  should  be  analyzed  for  priority
pollutant  organics  and  metals and  cyanide.
Other  parameters,  such  as  BOD, COD, pH,
IDS, TSS,  oil and grease, TOC, chlorides,
nitrite, nitrate, ammonia, total phosphorus, and
sulfides should be analyzed to provide data for
design of a leachate treatment system.

In many landfills, leachate is perched within the
landfill contents, above the water table. In the
absence of leachate  collection systems at Land-
fill Types I  and II, leachate wells  installed into
the landfill, as part of the site characterization,
may provide good hydrologic.  information on
the  site. That is, placing a  limited number of
leachate wells in the  landfill, is an efficient
means, of gathering information regarding the
depth, thickness, and  types of the waste;  the
moisture content and degree of decomposition
of the waste; leachate head levels "and the com-
position of  landfill leachate; and  the elevation
of the underlying natural soil layer. Additional-
ly, leachate wells provide good  locations for
landfill gas  sampling. Leachate wells should not
be  placed where there  are  existing leachate
collection systems, to prevent possible damage
to  these structures. In addition,  it should be
noted that, without  the proper precautions,
placing wells  into the landfill contents may
create health and safety risks. Also, installation
of wells through the landfill base may create
conduits through which leachate can migrate to
lower geologic  strata.   And finally, the installa-
tion of wells into landfill contents may make it
difficult to ensure the reliability of the  sampling
locations.

The number of leachate wells will vary for each
landfill.  In  cases where  the  refuse  is  fairly
thick, clusters  or nested wells may be appropri-
ate to determine if leachate composition varies
with depth. Samples should be analyzed  for
parameters previously described.

Landfill Type IL Type II landfills differ from
Type I landfills in that there" is evidence of hot
spot areas.  In these cases, treatment of  hot
spots may be a way of reducing the amount and
concentration  of leachate generated.  As with
Landfill Type I, a Water balance for the entire
site should be performed to estimate annual
leachate production.

At landfills that are suspected or known to
contain hot spots; leachate wells should not be
used  as a substitute for test pits  and actual
waste sampling.  However, chemical  analyses of
the leachate may demonstrate a principal threat
to the groundwater or surface water systems not
observed from  analysis   of  environmental
samples showing lower concentrations.

For any sample  collection method" 'used, more
than one round of sampling is recommended to
characterize the leachate properly. A minimum
of two sampling events, one  during a dry period
and the second  during  or immediately after
precipitation; should  be performed to determine
variability in leachate composition.

3.2.1.3 Guidelines

Field screening techniques described in Section
3.3.1.3  may be  useful  in determining which
samples are amenable to compositing or  for-
warding to the  analytical laboratory.   Visual
observations, site topography, and surface drain-
age patterns are also important in determining
the appropriate leachate sampling locations.

3.2.2 Data Requirements

A  detailed description  of leachate  remedial
action alternatives can be found in Section  4.3.
To evaluate the  various remedial action alterna-
tives, data gathered before or during character-
ization  of leachate should include:
                                              3-12

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  .A contour map  to  define  surface  water
      drainage pattern

  .Soil characteristics  including  permeabil-
      ity, grain size distribution, and moisture
      content to determine the physical proper-
      ties  governing  contaminant transport

  .Climatological  characteristics  including
      temperature and  precipitation  to help
      determine approximate leachate  volumes
      for the site

  .Waste  characteristics,  including  BOD,
      COD, pH,  IDS,  TSS, oil and grease,
      chlorides, nitrite, nitrate, ammonia, total
      phosphorus,  sulfides, and  metals, to
      determine,  a suitable leachate treatment
      system

  .Depth  to  groundwater  and ground-water
      flow direction and velocity  to  evaluate
      the feasibility of leachate or groundwater
      extraction and treatment

3.2.3 Leachate Summary

Leachate  sampling  at  seeps and streams  is
recommended for both landfill types. Leachate
can move laterally below ground toward a creek
or stream, affecting the water quality. Sampling
streams and leachate seeps can provide informa-
tion on  actual  or  potential  water quality
impacts. Installation of  leachate wells at land-
fill  Types  I and II can provide information such
as depth, thickness, and types of waste; leachate
head  levels and  the composition of landfill
leachate; and  the elevation of the underlying
natural soil layer.    Table 3-3 summarizes the
recommended  leachate sampling locations.
Figure .3-2 presents a logic flow diagram for
leachate sampling.
 3.3  Landfill Contents/Hot  Spots

Containment has generally been identified as
the most practicable remedial technology for
municipal landfills because  the volume and
heterogeneity of landfill contents often makes
treatment impracticable.  Characterization of
municipal landfill contents therefore is generally
not necessary because containment of the land-
fill contents  do  not require  such information.
More extensive  characterization activities and
development of remedial alternatives (such as
thermal  treatment  or  stabilization)  may be
appropriate for hot spots. The following sub-
sections discuss site characterization strategies
for landfill Types I and II for surficial soils, caps
and liners, and landfill contents  (including hot
spots).

3.3,1 Landfill Contents/Hot Spot Investigations

Typically, investigations at municipal landfills
are separated into four areas:

   . Surficial  soils
   .Caps
   .Liners
   .Landfill  contents

Surficial investigations  are undertaken if there
is either physical evidence or data that suggest
the presence of substantially contaminated surfi-
cial  soil in  the general area of the  landfill.
Surficial  sampling  investigations  should be
limited if surface  soils are planned  to be
Table 3-3
LEACHATE SAMPLING PROGRAM
Location
Collection drain
Surface
locations-stream, seeps
Minimum Sampling Events
Two—collect one during dryer and one
wetter period of the year.
during
Same as above.
                                              3-13

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                    Has
                 leachate
               been sampled
                    and
              .characterized ?>
                      No
Yes
Perform water balance for site
Identify existing leachate collection locations
Sample at leachate collection locations
Identify leachate seeps
Sample surface waters upstream and downstream
Collect leachate from seeps at toe or on slopes of landfill
                     Is
                  disposal
                of hazardous
                waste known
                     or
            Characterize as
          Solid Waste Landfill,
             as Necessary
      Install leachate wells if no leachate
      collection system exists (optional;
      decision should be based on benefit/cost
      analysis)
      Collect leachate samples from wells
               CHARACTERIZE
           LANDFILL TYPES I AND II


                              3-14
    Figure 3-2
    LOGIC DIAGRAM FOR LEACHATE SAMPLING

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covered with a cap.   Cap and liner investiga-
tions are undertaken when previous engineering
studies or field observations  indicate  their pres-
ence at a site, while landfill content investiga-
tions are undertaken to characterize known or
suspected  hazardous  waste  disposal  areas
(potential hot spots).  Small to moderate-sized
landfills (e.g., less than 100,000 cubic yards) may
also undergo  subsurface  investigations if the
landfill poses either  an existing or potential
threat to human health or the environment and
if it is appropriate to consider remediation of
the entire contents, of these landfills through
excavation, treatment,  or disposal.

It should be noted that investigations into land-
fill contents are rarely implemented  at munici-
pal landfills. This is due primarily to problems
in excavating  through refuse and the heteroge-
neous nature of the refuse, which makes charac-
terization difficult. Sampling of landfill contents
may, however,   be  useful  for enforcement
purposes (e.g., identifying  PRPs).    Drilling
through the base of the landfill is not recom-
mended due to the potential for migration of
leachate to lower geologic strata. However, in
general, drilling  into  refuse  for installation of
various extraction systems (for example, leach-
ate and landfill gas) is commonly implemented
(see Sections 4.2 and 4.4).

3.3.1.1   Objectives

The general purpose of characterizing soils  and
hot spots is to define the risks posed by these
media/contaminants and select the appropriate
remedial action alternatives for further evalua-
tion.    However, the specific objectives,  and
therefore,  the  sampling procedures, vary for
each type of investigation.   The objectives of
each type of soils investigation are described
below:

Topographic  Surveys.    The  objectives of
performing topographic surveys at  municipal
landfill sites are to:

   .Establish  a  basis for  determining  the
      total  and differential  settlement of the
      existing cap

   .Document  erosion gullies and  other rele-
      vant  topographic   features  that might
      affect the remediation scheme or point to
      anomalies that require further investiga-
      tion

Surficial Soil Investigation.     Surficial  soil
investigations are performed to:

   .Determine  the distribution  and  concen-
      tration of contamination in surficial soils

   •  Document  erosion  patterns

   .Determine if the surficial  soils,  either in
      whole or  just in  hot spots, should be
      included in the source control actions for
      the landfill.

Investigations of surficial soils should be limited
if there are plans to place a new cover system
over the existing surficial soils. However, "if
surficial soils are significantly contaminated,
particularly in hot spots, then separate source-
control remediation of the contaminated soils
may be considered; an investigation of contami-
nation in the topsoil  is  appropriate; even  if
there are plans to place a final cover over most
of the existing surficial soils.

Surficial soil investigations are normally focused
on anomalies observed at the surface,  such as:

   .Leachate seeps

   .Stains or other discoloration in the surfi-
      cial soils

   .Stressed vegetation

Analysis of surficial soil and sediment samples
may confirm or complement data from analysis
of surface  waters.   While the  presence or
absence of contamination of surficial soils may
have no relationship to groundwater contamina-
tion,  there may be contamination of surficial
soils and no groundwater contamination, or vice
versa.

Cap Investigation.   A cap investigation  is
intended to determine if a new cover system
would  be  required to  reduce infiltration of
water, to collect gas, to minimize erosion, or to
meet ARARs.  Another purpose  is  to define
Total  and  differential  settlement that might
                                              3-15

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occur if a new cover system is placed on the
landfill. If excessive settlement is predicted, the
waste will probably require  stabilization before
final closure with an engineered cover system.

Existing caps may either be engineered or not.
The degree  of sophistication employed in the
investigation of an existing cap will depend to a
great extent on whether it is planned to use all
or part of the existing cap in a new, engineered
cover system. If none of the  existing cap will be
incorporated into the new cover system (e.g., if
the existing cap will be buried beneath a new
cover),  detailed investigations of the existing
cap are  usually not necessary. If an existing cap
was not properly designed  and  constructed, it
will usually not be possible to incorporate the
existing cap within the profile of a new,  engi-
neered,  cover system, although the existing cap
may serve as foundation support for the new
cover system. In many cases, a cursory investi-
gation of the existing cap will verify  that it was
not  constructed to engineering  standards.  In
this situation, more detailed characterization of
the existing  cap is not necessary.

If it is suspected that an existing cap was  engi-
neered,  and information on the design and
construction of the cap is not available, then
preliminary  work should be  performed to verify
that the cap was properly  designed and con-
structed. For example, suppose excavation of
several  test  pits reveals that the  cap consists of
12 inches of topsoil underlain by 2 feet of low-
permeability soil  that appears  to have  been
compacted.  This information suggests that the
existing cap was engineered with the intention
of including a layer of topsoil above a hydraulic
barrier  layer.  If preliminary information  indi-
cates that the cap was engineered, and if it is
desired  to investigate the feasibility of incorpo-
rating all or part of the existing cap in the final
cover  system, then detailed characterization
tests are needed to confirm the properties of
the existing  cap.

The objectives of a cap investigation are to:

   .Determine  the approximate thickness,
      composition, and horizontal extent of the
      existing cap (a greater level of detail is
      needed if the existing cap is engineered
      and will  be incorporated  in  the  final
      cover  system)
   •   Determine if any hot spots of soil con-
      tamination are present in the existing cap
      and characterize these hot spots to the
      extent necessary  to determine whether
      the soils can be covered and left in the
      landfill or whether the hot spots need to
      be excavated and separately remediated
      for source control

   •   Document the  integrity of the existing
      cap (e.g., determine if roots have pene-
      trated  through  the  cap) and determine
      the geotechnical  and other relevant
      properties of the existing cap if the exist-
      ing cap was engineered and will be an
      integral part of  the final cover system

   •   Evaluate potential settlement (total and
      differential) of the landfill and the final
      cover system that will be placed on the
      landfill

   •   Evaluate the stability of any slopes and
      the capacity of the  waste  to support the
      final cover systems and any surficial load-
      ings such as those from surface traffic or
      construction equipment

Liner Investigation.  Liner investigations are
rarely performed, even if there is evidence of a
liner, since the liner could be punctured during
the investigation and  contribute to groundwater
degradation.  If a liner investigation is going to
be performed, then the objectives may include:

   .Confirming the existence of a  liner

   ."Determining  its  permeability

   . Evaluating, if possible,, its susceptibility
      to chemical damage

A liner investigation  could also  be undertaken
to determine the probability that contaminants
will migrate to the groundwater.

Subsurface Soil and Landfill Contents Investi-
gation. The purpose of subsurface sampling  is
to obtain a portion of soil  (disturbed or undis-
turbed)  or landfilled materials for chemical and
geotechnical analysis. This  can  be done  by
drilling and  taking samples  of the  subsurface
soils and landfill contents or by excavating test
                                              3-16

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pits or trenches. As previously described, sub-
surface investigations may only  be used  at
municipal  landfills where documentation  or
physical evidence exists, to indicate the presence
of hot spots.

The objectives of subsurface testing, using test
pits or trenches, are to:

   .  .  Evaluate the integrity of  any buried
      drums

   • Determine the 'degree of contamination
      of  any   unsaturated  soil

Surface geophysical surveys  are performed to
identify areas of buried metal and other areas of
concern. Based on the results, test pit locations
can then be selected to investigate  areas where
drums or  tanks are suspected.  Magnetometer
surveys (total field and vertical gradient), elec-
tromagnetic surveys, and soil gas surveys can be
used to identify test  pit sites.   It should  be
noted, however, that  landfills contain many
products other than metal drums. Therefore,
magnetometers  and. electromagnetic surveys are
used only  when there is. evidence to suggest
large, discrete areas of drum disposal. Trench-
ing, test pitting,  and boring installation are used
to characterize  hot spot areas.  Test pits and
trenches allow  a  larger, more  representative
area to be observed  and permit  selection of
specific samples from relatively shallow subsur-
face materials (biased grab sampling). Test pits
and trenches are typically dug to  confirm the
results of  surface geophysical investigations,
while borings are  typically used to investigate
deeper contamination. Also, soil  gas surveys
can  be used  to  identify  hot spots  if  the
suspected  contaminants,  include, VOCs.   The
soil gas surevey may be able to identify areas of
higher VOC concentrations  that can later  be
investigated with test pits or borings.

3.3.1.2 Procedures

Landfill Type I

A Type I  municipal  landfill is one in which
co-disposal of hazardous and municipal waste
occurred, but the location of highly toxic and/or
highly mobile material, which presents a poten-
tial  principal threat to  human health  or the
environmert (hot spots),  is not known.
Topographic  Surveys.   Topographic data are
often required to document erosional features,
to identify topographic anomalies that might be
related  to  deteriorated  drums  or  other  hot
spots, and to provide a basis for evaluating the
potential total and differential settlement result-
ing from decomposition of waste or compres-
sion of waste from the weight of the final cover
system.   The survey  should be designed to
define  areas with a differential settlement as
small as 6 inches over horizontal  distances of
10 feet.  To  document settlement over time,  a
series of settlement markers should be estab-
lished on  a grid pattern of approximately
100 feet (more in areas with known settlement
problems).

Surficial Soils.  Surficial soils are  investigated
to determine the distribution and concentration
of contamination, to document erosion patterns,
and to  determine if surficial soils  should be
included in  source  control actions. Before the
sampling is initiated, the soils exposed  at the
surface should be examined  visually for evidence
of staining; field personnel  should also look for
signs of vegetation stress. Geophysical tech-
niques  such as  electromagnetic  or ground-
probing radar may be helpful in identifying
anomalies, hot spots, or other zones of surficial
soil that warrant investigation. If it is  antici-
pated that an engineered cover system will be
constructed over the area of concern, sampling
of surficial  soils may  not  be necessary or
sampling efforts may be limited:' If there is an
Engineered  cap on the  landfill,  surficial soil
samples for analysis of contaminant concentra-
tion may not be needed unless surficial soil is
likely to remain as is, and the history of the soil
used for the cap is unknown.

To sample surficial soils, a grid often is super-
imposed on each area suspected of contamina-
tion, e.g., stained areas  or vegetation-stressed
areas.  Soil  samples can be collected at alter-
nate nodes on the grid. The node  samples can
be composite  to  reduce  the  number of
analyses. The analyses from  at least two back-
ground  samples should be available for compar-
ison. Background samples should be obtained
from areas with a similar soil composition on
the  site, but outside the influence of the  site.
Previous activities at any  offsite  locations
should  be  considered before collecting back-
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ground  samples,  since these offsite activities
could introduce contamination.

The depths of the surficial soil sample and the
analytical parameters vary from site to site but,
in general, should be specified as follows:

   .Samples for priority pollutant metals and
      cyanide  analyses should be collected from
      the O-  to 6-inch depth to characterize
      direct exposure risks (i.e., contact and
      ingestion).

   .Samples  for VOC  analyses should be
      collected from the 18- to 24-inch depth
      because  these compounds tend to evapo-
      rate from the soil at shallower depths.

Other  sampling  depths  may be  appropriate
based on site-specific circumstances (e.g., depth
to groundwater, soil structure). While samples
from different nodes may be composite hori-
zontally,  vertical compositing is not recom-
mended, except over short intervals, because
compositing  will  obscure  analytical  results.
Additionally,  compositing samples  for VOC
analysis is not recommended because of losses
during-  mixing of samples. Additional analyses
can be performed, depending on the results of
the site  history and previous waste characteriza-
tion studies.   Additional analytical parameters
could include  RCRA hazardous waste charac-
teristics, total  BTU content, and bulk weight of
the material.

The frequency  of surficial  soil sampling depends
on the characteristics of the soil and waste,  and
requires professional judgment.  For example,
contaminant    migration   from    uniformly
deposited waste in a relatively uniform soil will
be more predictable than migration  from
random placement of wastes in a heterogeneous
environment such as a landfill. Sampling will,
therefore, be  required at a higher frequency
near the landfill area, since contaminants can be
expected to migrate irregularly.

Surficial  soil  samples can be collected using
stainless steel trowels or shovels, hand augers,
or soil  sampling tubes.   Samples containing
volatile compounds must be sealed to prevent
losses.  Special techniques may be required to
preserve soil samples so that levels of contami-
nation do not change between  sampling and
analysis.

Cap  Investigation.   The cap investigation must
be carefully planned to maximize the value of
data collected and to ensure that unnecessary
data are not collected. First,  it must be deter-
mined whether the existing cap is likely to have
been  engineered. In most  cases, the existing
cap will not have been engineered, and since it
is recommended that these  type  cover systems
are not used as part of a new engineered cover
system (except as a  foundation) detailed  assess-
ment of the geotechnical properties of the cap
materials is usually not necessary.   However,
basic information concerning the approximate
thickness and lateral extent of the existing cap,
composition of the  cap, and characteristics of
the soils that make  up the cap will need to  be
developed.   There  are many techniques that
may be used in determining the thickness and
lateral extent of the  cap, including surface geo-
physical techniques  such as ground-penetrating
radar. However,  drilling of holes or excavation
of test pits will generally be needed either alone
or as a means to calibrate surface geophysical
techniques. Sampling at a frequency  of approxi-
mately one exploratory boring or  trench  per
acre is suggested. Samples  should be analyzed
to determine the liquid and plastic limits of the
soils, percentage of fines, percentage of gravel,
moisture content, shear strength, and any other
relevant parameters.

For more  detailed investigations, an appropri-
ately sized  grid can  be superimposed on  several
areas of the  existing  cap.    Samples can  be
collected either  at alternate nodes on the grid
or randomly.    Areas  selected for sampling
should include  both  representative locations
and  those  areas where erosion, cracking,  or
fracturing has occurred.

Shallow test pits can be dug  to expose a cross
section of the cap.    Test pits can be dug  by
hand or with a backhoe. Test pits  are usually
excavated no more than 1 foot below the thick-
ness of the cap.  Exploratory borings, drilled
with a hand auger or truck-mounted equipment,
can also yield information on the materials that
make up the existing cap. Sampling tubes can
be pushed or  driven  into the cap materials if
the characteristics of the in situ material need
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to be identified. Otherwise, disturbed samples
of materials generally are collected for later use
in the laboratory.   Procedures described  in
ASTM  Standard D420, Standard  Guide for
Investigating and Sampling Soil and Rock,  should
be followed.

If undisturbed samples are to  be obtained,  a
thin-walled sampling tube (often called Shelby
tube) should be used. Shelby tubes  are pushed
into the cap using a drill rig, hydraulic ram, or
other device that provides a straight,  steady
push. It is not recommended that the sampling
tube be pushed directly with a backhoe because
that usually tilts the lube.  Also, the sampling
tube should never be driven into the soil if an
undisturbed sample  is  sought.  The sampling
tube usually is not pushed  more than about 18
inches into the soil; a push of 6 inches or less is
recommended for very stiff or hard, cohesive
soils. Once a  sample has been  obtained, it is
classified  in  the field,  extruded  from the
sampling tube, and sealed in a sample-holding
device or sealed directly in the  tube. Samples
then are placed in specially designed boxes that
hold the samples in position and prevent their
disturbance during transport back to the labora-
tory. Collection of undisturbed samples should
be in accordance with ASTM Standard D1587,
Standard Practice for Thin-Walled Tube Sampling
of Soils. Transport  and storage of samples
should  be  in  accord  with  ASTM  Standard
D4220, Standard Practices for Preserving and
Transporting Soil Samples.

Undisturbed samples  are  tested routinely  to
determine the moisture content  and density of
the "soil and are subjected' to relevant tests to
define the  soil property of interest, e.g., shear
strength. Undisturbed  soil samples are some-
times tested for more routine properties, such
as liquid and plastic limit, to "develop a basis for
comparing  the  results  of various  laboratory
tests.

Tests to determine  compaction  characteristics
are usually performed on large, bulk samples of
the materials obtained from soil borings or test
pits. However, unless the existing materials in
the  cap  will be excavated and recompacted,
there is usually no need for compaction tests
other than to verify that the existing materials
are well or poorly compacted. (In most cases,
 the existing cover materials are assumed to be
 poorly compacted.)

 Sometimes the permeability (to air or water) of
 existing cap materials will require evaluation.' If
 the existing cap, or a layer within the existing
 cap, is expected to have a low permeability, a
 combination of laboratory permeability tests on
 undisturbed samples and field (in situ) perme-
 ability tests is recommended. However, field
 tests are time consuming and difficult; they arc
 usually recommended only when the use of the
 existing cap materials  for a low-permeability
 barrier in the final cover system is being consid-
 ered. Laboratory permeability tests usually are
 performed at a frequency of 1 per acre per lift
 on modern, engineered, low-permeability barri-
 ers of compacted  soil.   A  similar frequency
 would be appropriate for evaluation of a  pre-
 existing barrier that is thought to have been
 engineered or otherwise constructed to achieve
 a low permeability. The recommended method
 for laboratory" permeability testing is ASTM
 D5084, Hydraulic Conductivity of Saturated
 Porous Materials Using a Flexible  Wall Perrne-
 ameter.

 In some  circumstances, the  existing cap  may
 have a high permeability, and the material could
 be used as a gas collection layer within the final
 cover system.     Accurate  measurement of
 extremely high gas  permeability is difficult;
 accepted methods of in  situ testing do not exist.
 The permeability to air is probably best evalu-
 ated on the basis of grain size and permeability
 to water, " as measured in the laboratory. With
 an existing material that is suspected of having
 a high permeability, the main issue to be inves-
 tigated is whether the material has sufficiently
 high permeability over the full areal extent of
 the site.  Thus, testing of many samples (at  least
 three tests per acre) to establish  consistent of
 high permeability would be appropriate.

 After the initial stage of geotechnical investiga-
 tion and sampling is completed, the results are
 evaluated to determine whether more field work
 is needed. Additional tests may be necessary to
evaluate various issues.  For example, it may be
 necessary to  construct test  patches of  the
 proposed cover material over the  landfill to
 determine the feasibility of constructing and
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compacting materials for the final cover system
on weak, compressible waste  materials.

Waste Investigation. The physical and biological
properties of the landfill contents have an influ-
ence on the feasibility of placing a final cover
on a site. Some wastes are so compressible or
biologically unstable that technical problems
can  arise in constructing  and maintaining  a
final, engineered cover because of excessive
settlement. In such cases, it. may be necessary
to physically or "biologically stabilize the waste
prior to placement of a final cover. The need
to stabilize the  waste prior to construction of a
final cover may be a critical issue in the feasibil-
ity study of closure of the site.

The  depth of waste must be accurately defined
so that settlement patterns can be calculated.
Surface geophysical techniques, such as seismic
refraction, can  be useful in defining the depth
of waste in some circumstances.   Drilling  soil
borings is the most reliable way, to  determine
the depth of the waste; however, in some cases,
this  may pose'  unacceptable health and safety
risks. Particular attention should be given to
evaluating the  variability of thickness of the
waste because  a variable thickness  can cause
significant and harmful differential settlement of
the final cover.

It may be advantageous to initiate a program to
measure settlement of the landfill. This would
include the installation of one  or more bench-
marks  outside the fill area and periodic survey-
ing of settlement markers placed on the surface
of the existing cap. The measurement of settle-
ment may need to extend through  the RI/FS
and  into the remedial design, in. order to moni-
tor for a sufficient time. Differential settlement
is often more critical to the performance of a
final cover system than is total settlement. The
magnitude of differential  settlement, expressed
as the amount of settlement over a specified
horizontal distance, that exists in a cap can, be a
useful indicator of future problems with differ-
ential  settlement. Sometimes  more extensive
testing may be  needed to quantify differential
settlement and to define the need for stabilizing
the underlying waste. Examples of these types
of studies include:
   .Passage of a heavy  vibratory compactor
      over the  surface of the site and measure.
      ment of the resulting settlement

   .Prototype  deep,  dynamic  compaction
      (which involves dropping a large weight
      on the surface to compact underlying
     materials)

   .Construction of a test fill on the existing
      cap

 The degree of decomposition of the landfill is
 often relevant to issues such  as  potential  for
 future,  settlement and generation  of gas.
 Knowledge of the amount of organic materials,
 volatile solids,  ash  content,  and  moisture
 content usually  helps  in  understanding  the
 condition and stability of the buried waste.

 Geotechnical tests  such as shear  strength and
 consolidation  tests often are  impractical  for
 solid wastes because large fragments of solid
 waste cannot be small laboratory test specimens.
 However, if the waste is homogeneous and free
 of large fragments, such tests are  practical and
 should be performed to  characterize  the
 strength and compressibility of the waste.

 When  laboratory  testing of  samples  from
 municipal landfills is impractical  (as  is usually
 the case), the engineering team  generally will be
 forced to rely  upon published data on the geo-
 technical properties of waste. These properties
 are sensitive to the bulk density  and moisture
 content of the waste. An attempt to quantify
 bulk density (even  if approximate) and moisture
 content of the waste may yield valuable data for
 purposes of estimating other characteristics of
 the waste  material.

 The potential  for  the waste to produce  gases
from volatilization  or decomposition  should be
 evaluated. Analysis of gas from venting wells
 usually is  definitive.

 Liner  Investigations,    Liner  investigations
 should be performed  only if previous engineer-
 ing studies indicate the presence of a liner  and
 the  liner is easily accessible. In general,  soil
 borings should not be  taken through any liner
 because contamination may be spread by  punc-
 turing  the confining  layers.  However, in prac-
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tice, it is impossible to confirm that a liner
exists without drilling to the liner and sampling
it; this will usually require some penetrations.
The penetrations must be carefully sealed using
techniques similar to those for sealing monitori-
ng wells.

If the liner extends to the sides of the municipal
landfill, then samples may be collected at the
edge  of  the liner.  For low-permeability soil
liners, tests to  define permeability, as described
for -caps, should be performed. For geomem-
branes, the liner samples should be collected
where Icachate seeps are evident, if possible,
and exanubed  for deterioration.

Favorable results (e.g., low permeability), from
the tests do not necessarily mean that the unex-
amined portion of the liner is  preventing
groundwater  contamination.  Rips,  tears,  or
uneven distribution of liner  materials could
exist.  Hydrogeological  studies  also should pro-
vide more information on the condition of any
liner,  although these studies may provide incon-
clusive data.

Landfill Type II

Landfill  contents are generally only  sampled
where hot spots  are  suspected  from either
physical  evidence or record searches  or when
the landfill is smaller than 100,000 cubic yards
and it has been determined that (1) the landfill
poses  an actual or potential  risk to human
health or the environment, and (2) it is practi-
cable  to consider excavation and/or treatment of
the contents. Landfill sampling is not normally
performed under other circumstances, since it
can be assumed that landfill contents are heter-
ogeneous.   The horizontal extent of hot spots
should be delineated using magnetometer, elec-
tromagnetic (terrain conductivity), or soil gas
surveys. Electromagnetic  surveys are used prin-
cipally to detect drum clusters buried near the
surface (e.g., approximately one half times the
coil spacing); magnetometer surveys are used to
detect drums buried as deep as 15 feet beneath
the surface; and soil gas surveys are used to
detect leaking drums containing VOCs. Confir-
mation and contaminant quantification in hot
spot areas are done by excavating test pits or
drilling soil borings.
These survey methods develop numerous data
points. Reduction, processing, and presentation
are major concerns in proper interpretation and
analyses of the data. If available, data taken in
the field should be electronically recorded and
downloaded  to a computer system for proces-
sing. Additional  information  on  the  use  of
these methods may be found  in  Quantitative
Magnetic Analysis of Landfills (Bevan, 1983) and
Magnetic Survey Methods Used in the Initial
Assessment of a Waste Disposal Site (Fowler,
date unknown).

Magnetometer Survey. A  magnetometer mea-
sures the total magnetic field of the earth and
its localized  perturbations. A metal mass such
as steel  drums or other ferrous materials
distorts this magnetic field and is  indicated on
the readout. Magnetometer surveys are used at
municipal landfill  sites to  determine the extent,
location,  and relative magnitude of drum
disposal  areas and may provide useful informa-
tion in determining the extent  of the landfill
boundary. A  magnetometer survey  may be con-
ducted rapidly with minimal labor and  field
time.

Before conducting a magnetometer survey, an
appropriate-sized  grid  is laid out  over the
portion of the landfill suspected to contain the
buried drums.   The lines should  be generally
oriented in a north-south fashion, and should
be plotted and  labeled on a site topographic
map. Data intervals (points on the line) should
be greater than  10 feet,  and  space between
traverse lines should  be   at least 25  feet.  In
situations where the size and approximate  mass
of a suspected object is known, the characteris-
tics of the suspected object would dictate the
line intervals and points.  A fixed  point should
be established where base  data can be collected
at various   times   during the  day.  This
information can be  used for  correction
purposes.

During the magnetometer  survey, the field team
should note  any potential interference. These
may include  any steel on the surface, construc-
tion debris that may contain steel rebar, fences,
power' lines, and other buildings. Some of the
local  interferences with the  magnetometer
sensor can  be  minimized by  increasing the
distance between the ground and the sensor.
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Total field and vertical gradient measurements
are collected, using the magnetometer. Vertical
gradient data have higher resolution than the
total field data and minimize potential noise
problems (e.g., interference from miscellaneous
ferrous materials such as wire). The total field
and vertical  gradient data are collected simulta-
neously. At  the completion of the magnetome-
ter survey, data can be corrected for the effects
of the  diurnal changes in the local magnetic
field. Once  this is done, a magnetic contour
map is prepared to interpret magnetic anoma-
lies.

Electromagnetic (Terrain Conductivity) Survey.
An electromagnetic  survey measures the con-
ductivity variations between landfill soils and
suspected drum disposal areas. These surveys
indicate where buried drums may be located.
Depth estimates can  be generalized by incorpo-
rating magnetometer components and both the
horizontal and vertical components of the elec-
tromagnetic survey data. Magnetometer data is
dependent on the amount of ferrous mass and
the depth of which it is buried. A large mass
that is buried very deep will look the same as a
small mass buried near the surface. By combin-
ing the vertical and horizontal electromagnetic
survey data, one can determine  how deeply a
particular  mass  is buried.

The objective of an electromagnetic survey is to
locate buried metallic and/or conductive masses
such as discrete drum disposal areas. However,
conductivity variations in soils or landfill mate-
rials often limit the survey  ability  to  distin-
guish the disposal areas. An electromagnetic
survey, can be used for rapid data  collection
with   minimal   site    preparation.

Before conducting an electromagnetic survey,  an
appropriate-sized grid is laid out over the por-
tion of the  landfill suspected to contain the
subsurface materials. Data are often collected
at 3-meter coil separations but can be extended
to 10, 20, and 40-meter spacings, depending  on
the  depth of investigation required.  If soil
conditions permit (i.e., thin or non-existent clay
layers), ground penetrating radar' can also  be
used. The different coil separations and orien-
tations  (vertical and horizontal) help identify
whether conductivity variations are'  caused by
shallow or deep sources. The data are plotted
and contoured to describe the source disposal
area.  ,

Soil Gas Survey. If a magnetometer or electro-
magnetic survey does not accurately define the
boundaries  of subsurface drum disposal areas
and the  contaminants of concern are VOCs soil
gas surveys can be conducted. Also, if the hot
spot is an area of open dumping of hazardous
substances,  including VOCs a  soil gas survey
may be useful  in. delineating the  area extent.
As part of the soil gas survey, ground probes
are driven to planned depths,  and a  vacuum
pump is used to draw the  samples from the
probe. Soil gas samples are collected in Tedlar
bags or stainless steel bombs, or are adsorbed
onto carbon or  analyzed in the field  with an
OVA.    Initially, vertical profiles of organic
gases in the, soil pore spaces are measured and
plotted  at several locations. Based on these
vertical  profiles and the particular organic gases
present, the sampling depth for more  soil gas
samples  is Selected.

Once  a  constant sampling depth, is established,
soil gas samples are collected on  an appropri-
ate-sized grid laid out over the suspected dis-
posal area.  Once the location is better delin-
eated, additional sampling on a  smaller grid
may.  be conducted to refine the  limits of the
area. If results from the initial vertical profiles
do not provide sufficient data to find a solvent
plume, the -soil gas survey may be discontinued.
'The  sampling  depth may be  limited by the
presence  of buried drums,  and extreme care
should  be exercised when driving probes into
landfills.

Analyses of the  samples can delineate  the
boundaries  of contaminated  subsurface areas.
These surveys, can also be used to minimize the
number of test pits, geotechnical borings or
monitoring  wells that must be drilled  or
installed. Soil gas surveys can save the time and
expense included in drilling additional  geotech-
nical  borings and monitoring wells; however,
they are more  time-consuming and expensive
than  magnetometer   and    electromagnetic
,surveys.

Test  Pits or Trenches.   Depending  on the
results  of the geophysical surveys and soil gas
surveys, test pits or trenches may be excavated.
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OSHA requires that some type of investigative
method such as test pitting be used prior to any
excavation. Test pits or trenches are typically
excavated by backhoes due to the anticipated
hazardous nature of any subsurface materials.
The size of the excavation depends primarily on
the following:

   . Approximate area of the buried materials

   .Space required for efficient  excavation

   .  Economics and  efficiency  of available
      equipment

Test pits normally have a cross section that is 4
to 10 feet square; test trenches are usually 3 to
6 feet wide and may extended for any length to
reveal conditions along a specific line. Further
information on test pits is available in EPA's A
Compendium of Superfund Field Operations
Methods (EPA,  1987h).

Trenches or pits should not be excavated too
closely together. Sufficient space, should be
maintained between excavations to put soils
that will be stockpiled for cover, and to allow
access and free movements by haul vehicles and
operating equipment. Excavated soil should be
stockpiled to one side in one location, If possi-
ble, it should be downwind of the excavation
and away from the edge of the pit to  reduce
pressure on the walls.   Soils should be placed
on a sheet of heavy plastic to prevent additional
contamination of surface  soils.

If the excavation uncovers drums, they should
be carefully examined for identifying markings.
Information stenciled on drums can sometimes
be used to identify PRPs. Any labels  on the
outside of the  drums  should also be used to
specify  additional analytical parameters for soil
testing. Samples arc selected by depth, visual
observations (e.g.,  soil staining),  the concentra-
tion  or types  of  VOCs detected during the
screening process, and stratigraphic  relation-
ships.

The field supervisor selects the depth intervals
after  consultation  with the, project hydrogeo-
logist and chemist.   At least  one sample  is
collected from each wall and the bottom of the
excavation for field screening. If visual observa-
tions and the field screening procedures indicate
that the samples are similar, they may be com-
posite  before laboratory analysis.  If visual
observations, field screening, or stratigraphic
relationships indicate that the  samples  are
different,  then they should be analyzed sepa-
rately by  the laboratory. Samples of possible
waste materials (e.g.,  leaks from buried drums
or tanks) should not be composited.

Test pits excavated into fill are generally more
unstable than pits  dug  into natural in-place
soils. Any required samples should be gathered
without entering the test pit or trench. Samples
of leachate, groundwater,  and. sidewall soils can
be  taken  with telescoping poles,  etc., or if
necessary, from the bucket of the backhoe. If
intact or crushed drums  are encountered, they
should not be, removed. Drummed materials
should  not  be tested unless the  drums  are
degraded and leaking,  as evidenced by the pres-
ence of liquids in the test pits around them.

Dewatering may be  required  to  assure  the
stability of the side walls. This is an important
consideration  for excavations  in landfill
material.   Liquids  removed as  a result of
dewatering  operations  must  be  handled  as
potentially contaminated materials. The water
from any excavated saturated soils and erosion
or sedimentation of these soils should be con-
trolled.   A  temporary detention basin and  a
drainage system should be considered, if neces-
sary,  to prevent contaminated wastes from
spreading.

Following completion of sampling and test pit
logging,   test pits are backfilled to  grade. If
excess material shows evidence of gross  organic
contamination or  photoionization  detector
(PID) readings above background, it should be
drummed. Otherwise, the excavated materials
should be evenly spread over the test pit area
and covered with uncontaminated soil.

The analytical  results are  compared with the
groundwater plume data to identify  groundwater
contaminant  source areas. This  information is
used to identify the potential for  future contam-
inant releases to the groundwater;  to evaluate
containment, treatment,  and disposal alterna-
tives for the hot spots; and to identify PRPs.
                                              3-23

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Soil Borings. In some cases it may be appropri-
ate to drill soil  borings  within the landfill
contents to characterize known hot spots. The
number and depth of borings should be based
on site specific conditions such as the suspected
size and depth of the hot spot,  and potential
variability in contaminant levels within the hot
spot.  Prior to  drilling soil borings into  a hot
spot, a geophysical survey should be completed
as well as a review of any existing information
(such as disposal records)  on the nature of
contamination in the hot spot,

Care must be exercised when sampling landfill
contents because  drilling through the landfill
could compromise the integrity  of any  liners
(particularly  synthetic membrane liners),  or
penetrate a gas pocket causing  an explosion
hazard or release of VOCs Sampling landfill
contents can also be difficult, as garbage bags,
baling wire, etc., cling to the augers. Sampling
should be. extended to the bottom of the landfill
only in situations where the depth of the land-
fill is  known and where it is known that there is
no  liner. Sampling should not  penetrate the
base of the  landfill.

Landfill content samples are usually taken at
intervals approved by the field engineer or
geologist. Samples are typically  taken at each
change  in  material  type  and  are  based on
sampling using field monitoring instruments.
Where sampling is difficult or a larger volume
of material is  needed, a larger-diameter split-
spoon sampler (3-inch),  a  Shelby  tube,  a
pitcher-type sampler, or a piston-type sampler
might be required.

3,3.1.3 Guidelines

Determining the extent of soil contamination
can be very time consuming and costly. It is
important  to  keep the  principal  focus for
conducting any soil sampling in the proper
perspective, that is, defining grossly contam-
inated soil that will be addressed by remedial
action alternatives developed  for the landfill
contents or hot spots. Characterization of land-
fill contents is not necessary when capping is
the only practicable remedial action alternative.

A combination of field instruments and appro-
priate laboratory  samples  can  be used to pre-
liminarily determine the type  and extent of
contamination while minimizing cost and time.
However, field analytical techniques have cer-
tain limitations:

   .OVA  or  PID. If VOCs  are  in  the  soil,
      the  use of an organic  vapor  analyzer
      (OVA) or  photoionization  detector
      (PID)  may indicate  the presence  of
      VOCs However, the head space reading
      from a sample will depend on time delay
      after sampling, temperature, seal of lid
     on  sample  container,  and wind.   The
      results of the head space reading indicate
      VOC contamination, but usually do not
      produce quantitative results. It should be
      noted, when selecting an instrument, that
      an OVA will  detect methane  where  a
      PID will not.

   .Mobile Laboratory Gas Chromatography.
      The use of a field gas chromatography
      requires  the availability of  a  power
      supply or battery  packs with a clean area.
     This allows the analysis of samples for
      many contaminants  depending on  the
      column used, but does not provide total
      contaminant levels.

   •  Metals Analyses.   Field instruments for
      metals  analyses are limited to detection
      of certain indicator compounds, such as
      copper, mercury, and chromium, but do
      not detect levels below 10 ppm.

   .Mobile   Laboratory    PCB Analysis.
      Polychlorinated byphenyls (PCBs)  in the
      soils can be detected in the field using
      the proper extraction,  solvent and  gas
      chromatography (GC). These surveys can
      provide immediate  information  on the
      lateral extent of soil  contamination.
      However, this usually requires the use of
      a field lab set up at the site and generally
      is a large expense for timely turnaround
      (PCBs can be analyzed on a field porta-
      ble GC, with the  right column).

   .Acids  or Bases.   Soil pH can be mea-
      sured by mixing standard volumes of soil
     and deionized water and measuring the
      resulting pH of the slurry  with  a pH
      meter.
                                             3-24

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3.3.2 Data Requirements

To evaluate the various remedial action alterna-
tives for landfill  contents and  hot spots, data
gathered before or during the site characteriza-
tion of  landfill  contents/hot spots  should
include:

   . 1-foot contour maps  on  an  appropriate
      scale (e.g.,  1 inch equals  50 feet) so that
      slope  length and gradients can  be
      assessed for capping alternatives

   .Soil characteristics., including permeabili-
      ty, grain size, Atterberg limits, and ero-
      sion rates, for grading, capping, and ther-
      mal treatment  alternatives

   .Waste characteristics  of hot spot  areas
      including TAL  metals,  TCL organics,
      RCRA waste characteristics (e.g., ignita-
      bility, corrosivity, reactivity), total BTU
      content, bulk weight of the material, and
      results of any pilot testing (if necessary)
      for thermal treatment alternatives

   .Climatic  conditions including the 25-year,
      24-hour storm, frost depth,  and surface
      water runoff velocity for cap design

   .Existing  cap  characteristics

   .Geologic characteristics  and groundwater
      depth for capping and hot spot excava-
      tion alternatives

   .Future uses  of the  site

 3.3.3 Landfill Contents/Hot Spots Summary

 Table 3-4 summarizes the sampling  require-
 ments for soils and landfill contents.  Figure 3-3
 shows a logic diagram for the decisions neces-
 sary to characterize soils and landfill contents
 by landfill type. For Landfill Type I, the follow-
 ing site characterization is necessary:

   .Soils at  leachate  seeps
   .Areas with stressed vegetation
   .Stained  soils
   .Existing caps and liners, if accessible

 Geophysical  surveys  and test  pits  are  not
 required.
For Landfill Type II, the following site charac-
terization steps are necessary:

  .Soils at leachate seeps

  .Areas with stressed vegetation

  .Stained soils

  .Existing caps and liners, if accessible

  .Hot spot areas involving geophysical and
      soil gas surveys, test pits and borings


           3.4  Landfill  Gas

Several gases are typically generated by decom-
position of organic materials in a landfill. The
composition, quantity, and generation rates of
the gases  depend on  such factors  as refuse
quantity and  composition, refuse placement
characteristics, landfill  depth, refuse moisture
content, and amount of oxygen present. The
principal gases generated are carbon dioxide,
methane, nitrogen, and occasionally, hydrogen
sulfide.   Vinyl chloride,  toluene,  benzene,
hydrogen cyanide,  and other toxic contaminants
may also be present.

During a landfill's  early  stages the refuse under-
goes aerobic decomposition, and the principal
gas generated is carbon dioxide. Once all the.
free oxygen is depleted, the refuse decomposi-
tion becomes anaerobic, and the principal gases
become   carbon  dioxide  and methane.
Migration  of landfill gas can pose onsite and
offsite  fire and explosion hazards. In addition,
landfill gas can be an inhalation hazard and can
become soluble in groundwater.

3.4.1 Landfill Gas Investigations

3.4.1.1  Objectives

The goal bf landfill gas characterization is to
identify areas  in the landfill containing high
concentrations of explosive or toxic landfill gas
to:

   .Perform an assessment of human health
       risks due  to  air toxics  and explosive
       hazards
                                              3-25

-------
                                     Li-a« fyjii I n n
                    CHARACTERIZE
                    LANDFILTW
m    }
'"    J^
                     LANOFIL
                      TYPE II
                                           Figure 3-3
                        LOGIC  DIAGRAM  FOR SOILS/
                     LANDFILL CONTENTS  SAMPLING
3-26

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Table 3-4
SUMMARY OF SAMPLING REQUIREMENTS FOR SOIL AND LANDFILL CONTENTS
Medium To Be
Investigated
Surficial soil-stained or
stressed areas, leachate
seeps
Existing cap
Existing liners, if
accessible
Landfill contents
Hot spots
Sample Location
Horizontal composites from
alternate grid nodes or random
locations on the grid.
Representative random areas and
areas where erosion, cracking,
fracturing occurs.
Accessible edges of liner.
Random areas in landfill of less
than 100,000 yds3.*
Grids for surface geophysical
methods, one sample from each
wall and bottom of test pit--
composite or discrete.
Considerations
Metals and cyanide at 0-6 inches.
Volatile organics at 18-24 inches.
Permeability, compaction tests.
Test pits to determine cap depth.
Clay and soil—permeability,
compaction.
Geotextile— suspectibility to
chemical damage.
Stratigraphic changes, analyses for
contaminants indicated by record
search.
Use surface geophysical methods
first, excavate test pits.
* Sampling of landfills of small to moderate volume is dependent on (1) whether the landfill poses a
potential principal threat to human health or the environment, and (2) whether it is practicable to
consider excavation, disposal, or treatment of the landfill contents.
   .Evaluate  the feasibility of gas collection
      and treatment

   .Evaluate  other  remedial actions

The landfill gas investigation can be focused to
collect data specific  to the remedial alternatives
available for landfill gas. These remedial alter-
natives typically include active or passive landfill
gas collection systems which are described in
Section 4.4. The following subsections discuss
the objectives, the procedures,  and general
guidelines for site characterization of landfill
gas.

3.4.1.2 Procedures

Various landfill gas collection methods cart be
used,  depending on the type of landfill, and are
described below.
Landfill Type I. Methane gas as well as other
potential toxic gases are of concern at this type
of landfill where disposal of hazardous wastes
with municipal wastes has occurred, but there
are no  known or suspected  hot  spots.  Grid
sampling for landfill gas at random areas is the
recommended approach for this type of landfill.
Landfill gas samples should be collected from
areas of the landfill where methane production
is suspected, such as for sites where a passive
venting system already exists. Field screening
may be used to identify these areas if they are
not already known. However, note  that any
field screening instrument employing a PID will
not respond to methane due to methane's high
ionization potential.  Flame ionization  detectors
such  as the  OVA can be used to screen for
methane. Methane-specific Draeger tubes can
also  provide a qualitative measure of the
presence of methane in landfill gas.  Analysis
                                              3-27

-------
should include VOC analysis to identify the
presence of toxic organics. If specific contami-
nants of concern have been  identified, contami-
nant-specific Draeger tubes  can be used.  If
specific contaminants  have not been identified,
GC analysis for target compound list (TCL)
VOCs  should  be  performed.

Soil gas probes are commonly used to collect
landfill gas samples due to  the relative ease of
sample collection using this process. An appro-
priately sized grid can be superimposed on a
target  area, and  the nodes  sampled (grid
sampling). A grid size of 100 feet by 100 feet is
often used. Grids can be tightened to address
smaller target areas of known methane produc-
tion. The use of soil gas probes can also be
helpful in evaluating potential offsite migration.

Samples are analyzed using a gas chromato-
graphy. Sampling equipment should be decon-
taminated between sampling points to prevent
any cross-contamination. Using the OVA with
a charcoal pre-filter can help improve the quali-
tative  measure of methane concentration in
landfill gas.  The charcoal filter adsorbs most of
the non-methane gases, which  results in an
OVA reading  closer to the actual methane
concentration in the gas sample.

Samples can be collected from existing gas vents
or from test pits.   A typical test pit can be 1
cubic foot in size (e.g., approx. 1 foot deep). It
is covered with a board with a small opening on
top. Gas samples can be pumped using a small
electric or battery operated pump from this
opening  into a Tedlar bag  (or stainless steel
canister).  The Tedlar bag samples can be  ana-
lyzed using the OVA or by onsite analysis using
a mobile GC, and is typically used for fast-turn-
around results. Samples can be collected using
existing  extraction wells following this  same
procedure. Stainless steel canisters  are state-of-
the-art air/gas collection devices  that can be
shipped for offsite analysis more readily  than
the olher collection devices, but are expensive
and require elaborate decontamination proce-
dures before they  can be reused. Special care
should also be taken with  the field  and trip
blanks for air samples due to possible cross-
contamination or  laboratory problems.
Landfill Type II. Like land-fill Type I, methane
gas as well as other potential toxic gases are of
concern at this type of landfill where disposal of
hazardous  wastes with the municipal wastes
occurred, and there are known or suspected hot
spots.   Grid sampling of random  areas  for
methane sampling is recommended if no known
methane production areas have been identified.
Known hot spots can be sampled for toxic con-
taminants  (such as VOCs suspected  to be
present) on a tighter grid, based on the size of
the hot spot area.   Sample collection proce-
dures described for Landfill  Type  I can be
employed; VOC analysis  should definitely be
performed to identify the  presence  of toxic
organics. If specific contaminants of concern
have been  identified, contaminant specific
Draeger tubes can be used;  followup of Labora-
tory analysis of these specific contaminants
should be conducted. If specific contaminants
have not been identified, GC analysis for TCL
VOCs should be performed.

Further information on landfill gas sampling
methods is available in EPA's A Compendium of
Superfund Field Operations Methods  (EPA
1987h).

3.4.1.3 Guidelines

A gas monitoring program is difficult to estab-
lish because of the difficulty in predicting where
the gas  will migrate. If the  cover material for a
landfill  has  a  high  clay content, is well
compacted, or is wet  or frozen, it is not too
likely that the gas will diffuse uniformly up
Ihrough the cover.   Plots of isoconcentration
lines of gas concentrations determined from
field monitoring may assist in  determining
migration patterns.  Monitoring for landfill gas
around the perimeter of the landfill may also  be
useful in determining lateral migration patterns.

A landfill  gas monitoring program may  also
include some sampling in residential  areas.
This may include sampling for landfill  gas in
nearby  basements of residential or commercial
buildings.

3.4.2 Data Requirements

A detailed description of landfill gas remedial
action alternatives can be found in Section 4.4.
                                             3-28

-------
To evaluate the various remedial action alterna-
tives, data gathered before or during the site
characterization of landfill gas should include:

  .Contour  maps to  determine possible
      migration patterns

  •  Geologic, hydrogeologic, and soil charac-
      teristics  including  permeability, moisture
      content,  geologic strata, pH, and depth to
      bedrock and groundwater to determine
      potential gas migration patterns

  .Landfill  gas  characteristics  including
      composition, moisture content, quantity,
      and heat and methane content to deter-
      mine treatment  alternatives

  •  Types of microorganisms present in waste
      to determine biodegradation stages (for
      estimating  gas production)

3.4.3 Landfill Gas Summary

Table 3-5 summarizes  the  recommended
sampling locations for landfill gas. Figure 3-4
illustrates the decision process  required  to
determine the appropriate sampling approach
to be implemented.

For Landfill Type I, soil gas probes and grids
over a 100- by 100-foot area with sampling for
methane  and  VOCs  is  recommended.   For
Landfill Type II, the same sampling locations
are  recommended, with the exception that a
tighter grid (based on the size of the hot spot)
is used in hot spot areas, and that sampling for
methane,  VOCs,  and  specific  contaminants
associated with the hot spots is recommended.

    3.5  Wetlands and Sensitive
             Environments

Many municipal landfills have been built on or
next to natural wetlands or other sensitive envi-
ronments.   Sensitive  environments next"to
municipal landfills may be contaminated by
inflows of leachate through the surface water or
groundwater pathways. In  addition, contami-
nated sediments in wetlands may adsorb heavy
metals or complex organics in leachate  and
source material  from  municipal  landfills.  The
following subsections broadly discuss the objec-
tives, procedures, and guidelines for characteriz-
ing nearby wetlands and sensitive environments.

3.5.1 Wetlands and   Sensitive  Environment
Evaluation

Data gathered before  or during the environ-
mental evaluation will be used to characterize
the contamination and its extent (e.g., sediment
volume) and to assess  the impact of contamina-
tion on indigenous biota. Wetlands should be
delineated  in  accordance  with  the Federal
Manual for  Identifying  and Delineating
Jurisdictional  Wetlands (U.S. Fish and Wildlife
Service, et al.,  1989).
Table 3-5
LANDFILL GAS SAMPLING PROGRAM
Landfill Type
I
II
Sampling Locations
Soil gas probes at nodes of 100- by
100-foot grid over random areas.
soil gas probes at nodes of 100- by
100-foot grid over random areas and
tighter grid over hot spots (based on
size of hot spot area).
Analysis
Methane
Methane
specific
and VOCs.
, VOCs, and
contaminants.
                                             3-29

-------
          Has
         landfill
      been samcied
          and
      charactenzed ?
          Has
       landfill gas
         been
       adequately
      characterized 7
          Is
        disposal
      ol hazardous
     waste known or
      suspected 7
                                                                                          Is
                                                                                      •gas from
                                                                                       hex spots
                                                                                      adequately
                                                                                     characterized'
Sample lor methano.Usa
• Field analytical technque
•Gnd sampling using sal gas
 probes over random areas
 ol site or perimeter
         I
     CHARACTERIZE
  AS NORMAL MUNICIPAL
 LANDFILL AS NECESSARY
          Is
        disposal
          ol
    hazardous waste
     suspected as a
        res lit ol
         initial
       sampling'
Sarnie for methane and
VOCs  Use
• Field analytical tecflnque
• Gnd sampling using sal gas
 ryobes over random areas
 at site or site perimeter
        T
                                                                               Sample for specific contaminants.
                                                                               methane, and VOC. Use
                                                                               -Field analytical techniques
                                                                               •Tightened grid sampling over hot spots
    CHARACTERIZE
       LANDFILL
        TYPE II
                                               3-30
Figure 3-4
LOGIC  DIAGRAM  FOR
LANDFILL GAS SAMPLING

-------
3.5.1.1 Objectives

The  objectives of the  environmental evaluation
are to:

   .Determine the  impact  of the  site on
      sensitive environments (e.g., habitats,
      wildlife)

   •  Determine the impact of remedial action
      on wetlands  or floodplains

These environmental evaluations are normally
performed, if the municipal landfill is built on
or next to wetlands or other sensitive environ-
ments. The principal focus of these investiga-
tions is the  sediments. However, other media
of concern  may   include  surface water  and
aquatic species. The environmental evaluation
should provide information regarding compli-
ance with other environmental statutes, such as
the Endangered Species Act,  the Coastal Zone
Management Act,  and the Executive Order on
Floodplains and Wetlands.  Additional informa-
tion  on conducting environmental evaluations
can be found in Risk Assessment Guidance for
Superfund, Volume  II—Environmental Evaluation
Manual (U.S. EPA, 1989c).

3.5.1.2 Procedures

Landfill Type 1. The  approach to the environ-
mental  evaluation will  be the same for both
landfill types. A review of the data from the
leachate investigation (Section 3.2.1) and the
landfill  content/hot  spot investigation
(Section 3.3.1) may be useful in determining
contaminants that may affect wetland areas.

If surface water drainage patterns indicate  pos-
sible deposition of contaminated sediment in a
wetlands  area, a minimum of one composite
sediment sample from the major drainage chan-
nel  and  at least  two  background sediment
samples from  the wetlands area  should be
collected. If the composite sample is contami-
nated, then additional grab samples should be
collected  to delineate the areal extent of con-
tamination. The number of additional samples
to be collected should be determined on a case-
by-case basis, depending on the potential extent
of contamination.
In areas where vegetation stress is visible, com-
posite  sediment samples should be  collected
near the affected flora. Two background sam-
ples, if not already  collected for comparison
purposes,  should be collected. These samples
will indicate if contamination from the landfill
is present that may require that biota sampling
be done.

Data from other media investigations  should be
reviwed, because additional pathways could be
identified. For example, where leachate seeps
into groundwater and discharges into a wetlands
area, background samples and samples  of the
potentially contaminated area,  both  sediment
and groundwater, should be. collected  at the
point of groundwater recharge.

A qualified field biologist should survey the
area and note plant and animal  species, if the
area is indicated as  a sensitive environment
during the "records  searches or the  site visit.
Any remedial  action alternatives  considered for
the site should include mitigation procedures
for these sensitive environments.

Landfill Type  II.  The environmental evaluation
will be the same  for Type 11 landfills as for a
Type I landfill. However, the investigation and
remediation of hot spot areas may be a viable
means of reducing or eliminating the source of
wetlands contamination.

3.5.1.3 Guidelines

After data from the environmental evaluation
and other  media  investigations are collected, an
exposure assessment should be performed. The
exposure assessment should particularly review
potential biota targets and the probability that
they will be affected by the site. If contamina-
tion is  present and will harm the  sensitive envi-
ronments,  then  aquatic and  terrestrial  tissue
sampling  or  acute or chronic toxicity testing
should be considered 10  further assess the
impact of the site.   Biota sampling could
include:

   • Sampling of visibly affected plant life

   .Invertebrate  sampling in riverbeds

   • Fish shocking,  if recreational fishing area
                                             3-31

-------
  .Capture and sampling  of native wildlife,
      if it is known to be consumed by humans

Terrestrial and aquatic tissue sampling is labor
intensive and expensive and  should only be
conducted if warranted by the exposure assess-
ment. These types  of studies are very rarely
performed  during an  RI/FS. A more detailed
description of collection of biota sampling is
described in. the documents titled  Guidance for
Conducting Remedial Investigations  and Feasibili-
ty Studies Under CERCLA (U.S. EPA, 1988d),
and EPA's A Compendium  ofSuperfund Field
Operation Methods (EPA, 1987h).

3.5.2 Data  Requirements

A description of remedial action alternatives for
wetlands contamination can  be found in Section
4.6.  To evaluate remedial  action alternatives,
data gathered before or during  the environ-
mental site characterization  should include:

  .Contaminants  and concentrations in the
      sediments and volume of contaminated
      sediments to assess remedial action alter-
      natives

   .Species  of flora  and fauna that may be
      affected by contaminants and remedial
      action alternatives (Fauna should include
      birds, terrestrial  wildlife,  and  aquatic
      wildlife.)

A coordinated approach should be used when
conducting  an    environmental    evaluation,
because groundwater and surface water investi-
gations (Sections 3.1 and 3.6) often  overlap
environmental  evaluations. For example, leach-
ate from  a  municipal landfill can  seep  into
groundwater, which recharges to a wetlands
area.   The  groundwater  investigation would
identify the  contamination pathway and could
provide  additional information  on potential
contamination in the wetlands.    Both media
characterization  efforts, therefore, should be
integrated.

3.5,3 Wetlands Summary

Table 3-6 summarizes the sampling rationale for
an environmental evaluation, while Figure 3-5
Table 3-6
SUMMARY OF SAMPLING REQUIREMENTS
FOR ENVIRONMENTAL EVALUATION
Media to Be
Investigated
Wetlands
Sensitive
Environments
Groundwater
(Section 3.1)
Sample Locations
Collected sediment sample from
affected area and background samples.
Collect additional sediment samples to
confirm extent of contamination.
Observe sample aquatic/terrestrial life
in affected area.
Collect aquatic/terrestrial life for tissue
studies.
Collect sediment sample from stressed
area.
Collect surface water sediment and
groundwater samples.
Minimum Number of Samples
One composite sample per major
drainage channel; two background.
Depends on size of potentially
contaminated area.
Depends upon biota in affected
area.
Depends upon biota in affected area.
One composite sample per area.
(See Section 3.1)
                                             3-32

-------
                             Are wetlands
                              or sensitive
                             environments
                             located near
                              landfill site?
                                    Yes
                                Have
                               surface
                              water and
                              sediment
                             samples been
                              collected
                               before?
                                    Yes
                   No
    Are
  previous
  samples
  adequate
to characterize
  sensitive
environment ?
                                     Yes
Data from leachate,
 surface water, and
  groundwater
  investigations
                                Have
                               aquatic /
                             terrestrial biota
                             been surveyed
                              previously ?
                                     No
                             Yes
                          Sample surface water
                           sediment locations in
                           the sensitive environment.
                          Survey biota.
                            CHARACTERIZE
                        SENSITIVE ENVIRONMENT
                     NEAR MUNICIPAL LANDFILL SITE
                               3-33
                                             LOGIC DIAGRAM FOR ENVIRONMENTAL
                                             ASSESSMENT NEAR MUNICIPAL LANDFILLS

-------
shows a  typical  flow  chart  to determine
sampling locations. The sampling and monitor-
ing locations apply equally to both types of
landfills.
         3.6  Surface Water

Many municipal landfills are  near surface water
bodies, including rivers, intermittent streams,
ponds, and lakes.    Surface  water may  be
contaminated by:

   .Site surface water runoff

   .Surface seepage of leachate

   .Leachate seepage to groundwater, which
      recharges to  a  surface  water body

3.6.1 Surface Water Investigation

The surface water investigation must be coordi-
nated with  the groundwater, leachate, and land-
fill contents/hot spots investigations (Sections
3.1, 3.2, and 3.3, respectively). The rationale for
the location of surface water sampling and mon-
itoring points is often derived from the investi-
gation of other media.

3.6.1.1 Objectives

The objectives of the surface water investigation
are as follows:

   .Determine the  impact of the site  on
      surface water and sediments (e.g., from
      landfill runoff and leachate seeps)

   .Determine  contaminant  concentration  in
      upstream samples

   .Evaluate surface water hydrology, includ-
      ing drainage patterns,  flow, and surface
      water/groundwater   relationships,   as
      necsssary

   •   Determine the waste  characteristics  of
      surface water and sediments

   .  Determine the  extent  of  contamination
      and sediment volumes
   .Determine the tidal or seasonal effects of
      the surface  water on the landfill

   .Determine  impact of flooding  on  cap
      design and  potential erosion

Much of the above information can be  obtained
through record searches, initial site investiga-
tions, and  agencies  such as  the USGS,  Soil
Conservation Service, and other public agencies.
Field investigations of water level measurements
and  sampling should be conducted to supple-
ment this  information  (see  Guidance  for
Conducting  Remedial Investigations and  Feasibil-
ity Studies Under CERCLA (U.S. EPA,  1988d)).

3.6.1.2 Procedures

Landfill Type I.    Contamination of surface
water and sediment is primarily of concern at
Type 11 landfills.   However, since unknown
amounts. .  of hazardous wastes may be com-
mingled with municipal  wastes, migration of
contaminants to surface waters via leachate and
runoff may also be of concern at some Type  I
landfill  sites.  The approach  to both investi-
gating surface water and sediment contamina-
tion  will be similar for both landfill types. The
types of surface  waters that  may need to be
investigated at municipal landfill sites include
rivers, streams, lakes, ponds, or lagoons.

Many municipal landfills arc located near rivers
or streams.    Surface water  and sediment
samples should be collected  upgradient (i.e.,
upstream) of the  site, far enough to avoid any
tidal influences, and downgradient of any known
drainage/leachate seeps.  In areas where tidal
influence is a consideration, samples should be
composited from several locations in  both the
upgradienl  and  downgradient  areas.    Care
should be taken so that cross-contamination of
these samples by  other  industries or other adja-
cent landfills is avoided. Sediment and surface
water samples should be collected upgradient
and  dowmgradient in  each adjacent  river or
stream. Additional sampling locations might be
added depending upon the size of the site, the
number of rivers or  streams near the  landfill,
and  the  location of drainage or leachate seeps
to the river or stream.
                                             3-34

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Typical analytical parameters for surface water
and sediment samples include pH, temperature,
TSS, salinity, and specific contaminant concen-
trations.   These data provide capacity of the
water to carry contaminants and water/sediment
partitioning (Guidance for Conducting Remedial
Investigations and Feasibility  Studies Under
CERCLA (U.S.  EPA,  1988d)).     Specific
sampling  techniques  are  described in EPA's
Compendium of Superfund Field  Operations
Methods (EPA, 1987h).

If contamination  of a river is suspected or docu-
mented, river water  levels and corresponding
flows should be  monitored upgradient from the
site and downgradient from any leachate seeps
or runoff. This  information can  be used to
assess dilution effects and potential seasonal
variations  in contaminant concentrations due to
changing water levels.   Care should be taken
when choosing river  flow monitoring locations
so that impacts from  permitted or nonpermitted
discharges from  industries or adjacent landfills
are avoided. Often,  USGS  and various state
agencies monitor river flow  at various points
along major rivers  or streams. These data bases
can  be used for water  level,  flow  rate,  and
drainage data needs.  The locations may not be
ideal, but  a water balance can provide a reason-
able estimate for  site characterization.  If the
river is not monitored, a minimum of two water
level staff  gauges  should  be installed,  one
upgradient from the site and one downgradient
from the site in  each adjacent river or stream.
Precipitation data  can be acquired from local
weather bureaus or the National Climatic Data
Center in  Asheville, North Carolina.

Water level measurement frequency will depend
upon the data needs of the site.  At a minimum,
measurements should be conducted during the
surface water sampling. More frequent mea-
surements are required  to determine tidal or
seasonal  influences.

Some municipal  landfills are located near inter-
mittent streams. These streams often transport
contamination  from  landfills  as  a result of
surface water runoff during or  after periods of
heavy rainfall. Contamination can also be the
result of an accidental release of contaminants
such as overflow of  a surface impoundment, If
contamination is suspected  as a result of sea-
sonal landfill runoff, surface water and sediment
samples should be collected during or immedi-
ately following periods of heavy rainfall. An
evaluation of the drainage  patterns of the site
should indicate  optimal sampling locations.
One sample should be collected where runoff or
overflow enters  the  stream channel, and one
sample should be collected upgradient of the
site,  if possible.  Additional  surface  water
samples may be  collected to assess the impact
of contamination from the  intermittent stream
on  the water  quality of any  rivers or lakes
downstream.

Intermittent streams  are not usually monitored
by other agencies.   The stream depth, width,
and flow rate during or after periods of heavy
rainfall should be measured. The USGS can be
consulted for estimates of water drainage in a
particular area.   Local weather bureaus should
be contacted for  precipitation data.

Many municipal  landfills are situated near  lakes
and ponds  or  have  small ponds on the  site.
Lakes  and ponds are  often contaminated  by
surface  water runoff and leachate  seeps  from
the landfill. In addition, groundwater contami-
nated from  leachate seeps could  recharge to
nearby lakes and ponds.

Surface water and sediment samples should be
collected near the drainage or leachate seeps
and background  samples  should be  collected
upgradient of leachate  seeps,  care should be
taken  to  prevent   cross-contamination  from
industrial  dischargers and other landfills.
Additional sampling may be required to assess
seasonal/tidal  fluctuations  and multiple  point
discharges.

Larger surface water bodies should be moni-
tored to determine tidal and seasonal fluctua-
tions  that affect the extent of contamination
and groundwater flows. As mentioned above,
the USGS and other agencies may already  mon-
itor water levels and flows to lakes. These data
bases should be used. USGS data can be found
in their WATSTORE files, and U.S. EPA data
can be found in their STORET files. Precipita-
tion data can be obtained  from local weather
bureaus or the National Climatic Data Center
in Asheville, North Carolina.
                                             3-35

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Landfill  Type  II.    For landfills  that  are
suspected or known to have  hot  spot  areas,
investigation and remediation of hot spot areas
may  be a  viable means  of reducing  or
eliminating  the source of  contamination of
surface water and sediment contamination., In
some situations,  hot  spots  may  extend into
surface water sediment. Information on charac-
terizing hot spots can be found in Section 3.3.

3.6.1.3   Guidelines

Data to be collected should include sampling of
potentially  affected surface  waters and sedi-
ments from ponds, lakes, rivers,  and streams
(upgradient and downgradient).

At a  minimum, surface  water and  sediment
samples should be collected near drainage or
leachate seeps.    Background samples should
also be collected upgradient of leachate seeps
and upstream of the landfill site for streams and
rivers.

The determination of analytical parameters for
sediment and surface water samples  should
correlate with leachate analysis and hot spot
analysis. A review of the data generated from
the landfill  contents/hot  spot  investigation
(Section 3.3.1) and the leachate investigation
(Section 3.2.  1) should indicate contaminants of
concern for the surface water investigation.

3.6.2 Data Requirements

Surface waters  are  generally not  treated at
municipal landfill sites. However, removal and
management of contaminated  sediments from
surface water may be required.  A description of
remedial action alternatives for  surface water
and sediments can be found  in Section 4.7.
Data needs  for  evaluating surface  water and
sediment remedial  alternatives  can be  quite
extensive depending on the extent of potentially
contaminated surface water at a specific site.
Since  surface  water data needs  are  largely
dependent on the investigation of other media,
they are discussed  under the  surface water
investigation  (Section  3.6.  1).

3.6.3 Surface Water  Summary

Table  3-7  summarizes  the  recommended
sampling locations for surface waters. A flow-
chart summarizing the decisions necessary to
Table 3-7
SAMPLING AND MONITORING RATIONALE FOR SURFACE WATER
AND SEDIMENTS NEAR MUNICIPAL LANDFILL SITES
Location
Rivers
Intermittent
Streams
Ponds
Lakes
Sampling/Hydrological Monitoring
Location
Upgradient of site, down gradient of
site.
Background samples.
Upgradient and downgradient from
leachate seep/surface water run-
off/seep.
Points of known run-off/seep and
background samples.
Points of known run-off seep and
background samples.
Considerations
Tidal influence, seasonal influence,leachate
seeps, groundwater recharge, number of
rivers/streams bordering the site.
Seasonal influence.
Seasonal influence, groundwater
relationship, other related rivers or streams.
Tidal influence, seasonal influence, leachate
seeps, groundwater relationships, other
related rivers or streams.
                                             3-36

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 determine sampling and monitoring location is
 presented in  Figure  3-6.  The sampling and
 monitoring locations  are equally applicable to
 both types of landfills.
   3.7  Baseline  Risk  Assessment

 Baseline risk assessments evaluate the potential
 threat to human health and the environment in
 the absence of any remedial action. They often
 provide the basis for determining if remedial
 action is necessary and the  justification  for
 performing remedial actions. The baseline risk
 assessment can also be used  to  support a
 finding of imminent and substantial  endanger-
 ment if such a finding is required as  part of an
 enforcement action. It should be noted that the
 risk assessment is performed by EPA regardless
 of whether it is an enforcement-lead site or not.
 Detailed guidance  for conducting risk assess-
 ments is provided in the Risk Assessment
 Guidance  for Superfund,  Volume  I—Human
 Health Evaluation Manual (U.S. EPA 1989J);
 and the Risk Assessment Guidance for Super-
fund—Environmental Evaluation Manual (U.S.
 EPA, 1989c).

 In general, the objectives of a baseline risk
 assessment may be attained by identifying and
 characterizing the following:

   .Toxicity    and  levels   of hazardous
      substances in  relevant  media  (for
      example, air, groundwater, soil, surface
      water,  sediment, and biota)

   .Environmental  fate and transport mecha-
      nisms,  such  as physical, chemical, and
      biological degradation processes  and
      hydrogeological  conditions

   .Potential human and environmental
      receptors

   .Extent of expected impact or threat; and
      the  likelihood  of such impact or threat
      occurring (that  is, risk characterization)

   .Levels of uncertainty associated with  the
      above items
The level of effort required to conduct a base-
line  risk assessment  depends largely on the
complexity of the site.  The goal is to gather
sufficient information to  characterize the poten-
tial risk from a site adequately and accurately,
while at the same time conduct this assessment
as efficiently as possible. Use of the conceptual
site model developed and refined previously will
help focus investigation efforts and, therefore,
streamline this  effort. Factors that may  affect
the level of effort required include:

   •   Number,  concentration,  and types  of
      chemicals present

   •   Extent of contamination

   •   Quality and quantity of available  moni-
      toring data

   «   Number  and  complexity  of exposure
      pathways (including the complexity of
      release sources  and transport media)

   •   Required precision  of sample analyses,
      which in  turn depends on site conditions
      such as the extent of contaminant migra-
      tion and  the proximity, characteristics,
      and size  of potentially exposed popula-
      tion^)

   •   Availability  of appropriate standards
      and/or toxicity data

3.7.1   Components of the Baseline Risk Assess-
ment

The baseline risk assessment processes can be
divided into  four components:

   .Contaminant identification
   .Exposure  assessment
   .Toxicity  assessment
   .Risk  characterization

A brief overview of each component  follows.

3.7.1,1 Contaminant Identification

The objective of contaminant identification is to
screen the information that is  available  on
hazardous substances or wastes present  at the
site and to identify contaminants of concern to
                                             5-57

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                            Have surface
                         water and sediments
                           been previously
                             sampled?
                            Are previous
                          samples adequate
                           to characterize
                           surface water?
                          Have water levels,
                          drainage pathways
                           been previously
                             monitored?
                          Is alternative data
                          base information
                             available?
Yes
                                              Yes
                                    No
                      • Sample surface water
                       and sediment
                      • Perform water level monitoring
   Data from leachate,
environmental assessment,
    and groundwater
     investigations
                           CHARACTERIZE
                         SITE SURFACE WATER
         Are existing
        data adequate
        to characterize
            site?
                                                  Figure 3-6
                                                  LOGIC DIAGRAM FOR SURFACE WATER/
                                            3-38 SEDIMENT SAMPLING NEAR MUNICIPAL LANDFILL

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focus  subsequent efforts in the risk assess-
ment process.  Contaminants of concern may be
selected, because  of their intrinsic toxicological
properties, because they are present in large
quantities, or  because they are presently in or
potentially may  move  into  critical exposure
pathways (for  example, drinking water supply).

3.7.1.2 Exposure  Assessment

The objectives of an exposure assessment are to
indentify actual or potential exposure pathways,
to characterize the potentially exposed popula-
tions, and to determine the extent of the expo-
sure. Detailed guidance  on conducting expo-
sure assessments is provided in the Exposure
Factors Handbook (U.S. EPA 1989dd), and in
the Superfund Exposure Assessment Manual
(U.S. EPA 1988aa).

3.7.1.3  Toxicity Assessment

Toxicity assessment, as part of the Superfund
baseline risk   assessment  process,  considers
(1) the types of adverse health or environmental
effects associated with individual and multiple
chemical   exposures;  (2)  the  relationship
between magnitude of exposures and  adverse
effects;  and (3) related uncertainties such as the
weight of evidence for a chemical's potential
carcinogenicity in humans.

3.7.1.4  Risk Characterization

In the  final component of the risk assessment
process, the potential risks of adverse health or
environmental effects for each of the exposure
scenarios derived in the  exposure assessment,
are characterized  and summarized. Estimates of
risks are obtained by integrating information
developed during the  exposure  and toxicity
assessments to characterize the potential or
actual risk, including carcinogenic risks, noncar-
cinogenic risks, and environmental risks. The
final analysis  should include a summary of the
risks  associated  with  a site including each
projected exposure route for contaminants of
concern and the distribution of risk across vari-
ous sectors of the population. In addition, such
factors as the weight-of-evidence associated with
toxicity information, and any uncertainties asso-
ciated  with exposure assumptions  should be
discussed.
3.7.2 Using the  Baseline Risk  Assessment to
Streamline Remedial Action Decisions

The baseline  risk  assessment often provides
justification for performing remedial action at a
site. Once a potential risk to human health or
the  environment has been demonstrated,  an
evaluation of the appropriate remedial mea-
sures to mitigate the risk must  be performed.
The results of the baseline risk assessment are
used in combination  with chemical-specific
ARARs to determine clean-up levels, which in
turn help to direct  appropriate remedial mea-
sures. Options for remedial action at municipal
landfill  sites, however, are often  limited. There-
fore, in many  cases,  it may be  possible  to
streamline or  limit the scope of the baseline
risk assessment in order to initiate remedial
action on the  most obvious landfill problems
(groundwater/leachate,   landfill  contents, and
landfill gas). Ultimately, it will be necessary to
demonstrate that the final remedy, once imple-
mented, will address all pathways and contami-
nants of concern, not just those that triggered
the need for remedial action.

Rapid implementation of protective measures
for the major problems at a landfill site may be
accomplished  by:

1. Using the  conceptual site model and RI-
   generated data to perform a qualitative risk
   assessment that  identifies  contaminants of
   concern in the affected media, contaminant
   concentrations, and their hazardous proper-
   ties that may pose a risk through the various
   routes of exposure.

2. Identifying pathways that are  an obvious
   threat to human health or the environment
   by comparing Rl-derived contaminant con-
   centration levels to standards  that are poten-
   tial chemical-specific applicable or relevant
   and appropriate requirements (ARARs) for
   the action. These may include:

   .Non-zero  maximum contaminant  level
      goals (MCLGS) and MCIA for ground-
      water and leachate (40 CFR 300.430(e))

   .State air quality standards for landfill gas
                                             3-39

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When  potential ARARs  do not exist for a
specific   contaminant,   risk-based  chemical
concentrations should be used.

Where established standards for one or more
contaminants in a given  medium are clearly
exceeded, remedial action is generally warranted
(quantitative   assessments that consider  all
chemicals,  their potential additive effects, or
additivity of multiple exposure pathways are not
necessary.  In cases where  standards are not
clearly exceeded, a more thorough risk assess-
ment may be advisable before deciding whether
or not to take remedial action.

The benefits of performing early or interim
actions at a landfill site include speeding up  the
clean-up process and reducing the impact on
other affected media  (e.g., wetlands) at a site
while the. RJ/FS continues. The effect of early
action at a  landfill should be factored into any
ongoing risk assessment. For example, if leach-
ate seepage  that  had been contaminating
surface water  and  wetlands is  stopped as a
result of an early action,  then the risk assess-
ment developed  subsequently for the stream
sediments  and  wetlands should  assume  no
further loading. Any early actions also need to
be designed for flexibility so that they will be
consistent  with  subsequent  actions.    For
example,  it may  be necessary  to adjust a
groundwater  pump-and-treat early  action
designed to attain MCLs to achieve even lower
levels, determined to be necessary under a sub-
sequent risk  assessment, in  the interest of
protecting environmental receptors in the wet-
lands into  which the groundwater discharges.

Although  this  process allows for early imple-
mentation of remedial measures, a risk assess-
ment will be required to demonstrate that  the
final remedy at the site is protective of human
health and the  environment.
      3.8  Section  3  Summary

This section provides  information on how to
characterize CERCLA municipal landfill sites
so that site  dynamics and site risks can be
defined.  Also  included  in this  section is a
description of the baseline risk assessment for
municipal landfills. Section 4 describes technol-
ogies   most  practicable  for remediating
CERCLA municipal landfill sites.  The informa-
tion in these two sections can then be used to
assist in these development of appropriate reme-
dial action  alternatives  to mitigate potential
adverse  human health  and  environmental
impacts of municipal landfill sites.
                                              3-40

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                                        Section 4
         DETAILED  DESCRIPTION OF  TECHNOLOGIES
 4.1 Remedial Action  Objectives

Because many CERCLA municipal landfill sites
share similar characteristics, they  lend them-
selves to remediation by similar technologies.
EPA has established a number of expectations
as to the types of remedial alternatives that
should be developed during the detailed analysis
stage; they  are listed in the National Contin-
gency Plan. (40 CFR 300.430(a)(l)). For muni-
cipal landfill sites, iti is expected that:

   •   The  principal threats posed by a site
       will be treated wherever practical,  such
       as in the case of remediation of a hot
       spot.

   •   Engineering controls such  as contain-
       ment will be used for waste  that poses a
       relatively low long-term threat or where
       treatment is impractical.

   •   A combination of methods will be  used
       as appropriate to achieve protection of
       human health and the environment. An
       example  of combined  methods for
       municipal landfill sites would be treat-
       ment of hot spots in conjunction  with
       containment (capping)  of  the landfill
       contents.

   •   Institutional controls  such as   deed
       restrictions will be used to  supplement
       engineering controls, as appropriate, to
       prevent exposure to hazardous wastes.

   •   Innovative technologies will be consid-
       ered when such technologies offer the
       potential for superior treatment perfor-
       mance or lower costs for performance
       similar to that of demonstrated technol-
       ogies.
   •   Groundwatcr will be returned to benefi-
       cial uses whenever practical, within a
       reasonable  time, given the particular
       circumstances of the site.

As  a first step in developing remedial action
alternatives, remedial action objectives need to
be developed. Typically, the primary remedial
action  objectives for  remediating municipal
landfill sites include:

   •   Preventing  direct contact with landfill
       contents

   •   Reducing  contaminant  leaching  to
       groundwater

   •   Controlling  surface water  runoff and
       erosion

   •   Remediating hot spots

   •   Collecting  and treating contaminated
       groundwater and  leachate

   •   Controlling  and treating landfill gas

   •   Remediating   contaminated    surface
       water and sediments

   •   Remediating   contaminated   wetland
       areas

Based on the above remedial action objectives
for CERCLA municipal landfill sites and the
EPA expectations  outlined in the NCP, the
following points should be considered in order
to  streamline  the  development  of remedial
action alternatives:
                                            4-1

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   •    Generally, the most practicable remedi-
       al alternative for landfills  is contain-
       ment (capping).   Depending on  site
       characteristics, containment could range
       from a soil cover to a multi-component
       impermeable cap.

   •    Treatment of soils and wastes may be
       practicable for hot spots.  Consolidation
       of hot spot materials under a landfill
       cap is a  potential alternative in cases
       when  treatment  is not practicable or
       necessary.

   •    Extraction and  treatment of contami-
       nated groundwater and leachate may be
       required to control offsite migration of
       wastes.    Additionally, extraction  and
       treatment of leachate  from landfill con-
       tents may be required. Collection  and
       treatmem may be  necessary indefinitely
       because of continued contaminant load-
       ings from the landfill.

   •    Constructing an active landfill  gas
       collection and treatment system should
       be considered where (1)  existing or
       planned  homes  or  buildings  may be
       adversely affected through either  explo-
       sion or inhalation hazards, (2) final use
       of the site  includes  allowing  public
       access, (3) the landfill produces  exces-
       sive  odors,  or  (4)  it is  necessary to
       comply with ARARs.   Most landfills
       will require at least a passive gas  collec-
       tion system (that is,  venting) to prevent
       buildup of pressure below the cap and
       to prevent damage  to the  vegetative
       cover.

A review of the selected remedies in the records
of decision (RODs) EPA has signed through
FY 1989 for CERCLA municipal landfill sites
indicates that certain technologies are  imple-
mented more often than  others (Appendix B).
Based on this review of technologies used most
frequently at CERCLA municipal landfill sites
and, based on the NCP expectations, a list of
technologies has been developed.  The descrip-
tions  in  this section of  these technologies is
intended to streamline  the  RI/FS  process  by
making available a list of technologies practical
for use at CERCLA municipal landfills.  The
list of technologies  described in  this section is
not intended to alleviate the responsibility of
the feasibility study team to consider other,
possibly appropriate technologies. Design con-
siderations  and  data needs have  also  been
included to help guide the data-gathering tasks
associated with remedial investigations.

The technology discussions have been grouped
by media for organizational reasons. However,
the interactions between media should be con-
sidered when assembling technologies into alter-
natives.   For example, leachate, contaminated
groundwater, and landfill gas  condensate may
all require treatment using  some or all of the
same processes.

While the descriptions focus primarily on tech-
nologies used at  landfill sites, brief descriptions
of surface water and groundwater remediation
are included.   Often,  contamination of these
media must be addressed, although the nature
of the remedial  alternatives is not  necessarily
unique to  landfill sites. Likewise, mitigation of
wetlands  is  addressed  because  a  significant
number of municipal landfill  sites  are located
within or close to wetlands.
        4.2  Landfill  Contents

4.2.1 Access Restrictions

Access restrictions at municipal landfill sites are
intended  to  prevent or  reduce exposure  to
onsite contamination.    They include actions
such as fencing, signage, and restrictive cove-
nants on the property deed to prevent develop-
ment of the site or use of groundwater below
the site.    Access  restrictions may  also  be
imposed to reduce required maintenance and to
protect the integrity of a remedial alternative
such as a landfill  cap. Some of the conditions
at a municipal landfill site  that may warrant
access restrictions  include:

   •    Landfills   where  no cap   has   been
        constructed

   •    Landfills where passive venting of land-
        fill gas is being used  or cases where no
        landfill gas controls  have  been imple-
        mented  and gas  emissions  may  be a
        health hazard
                                              4-2

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   •   Landfills  where erosion of the  cover
       may be of concern (limit  all-terrain
       vehicles, vehicular traffic,  creation of
       foot paths,  etc.)

   •   Landfills where liability concerns may
       warrant limiting access

Situations  where  access  restrictions such as
fencing may not be necessary include:

   •   Rural areas where  heavy use is unlikely
       and where  occasional trespassing, such
       as for hunting, does not present a risk

   •   Urban  areas  in  situations  where the
       landfill is capped  and landfill gas does
       not present a significant risk and where
       the local community may desire that the
       land be used for an appropriate purpose
       such as a  park  area.   In cases where
       fencing is not necessary, it may still be
       prudent to post signs to warn trespass-
       ers of potential risks.

The two types  of access restrictions most used
at municipal landfill sites include deed restric-
tions and fencing.  Conditions in the area of the
site should be evaluated in the 5-year reviews to
assess the continuing or future need for access
restriction.

4.2.1.1 Deed Restrictions

Restrictive covenants on deeds to  the landfill
property are intended to  prevent or limit site
use and  development.   Restrictive  covenants,
written into the landfill  property deed, notify
any potential purchaser of the landfill property
that the  land was  used for waste disposal and
that the land use must be restricted in order to
ensure the integrity of the waste containment
system.  The effectiveness of deed  restrictions
depends on state and  local  laws, continued
enforcement,  and maintenance. Most restric-
tions are subject to changes in  political jurisdic-
tion, legal interpretation,  and level of enforce-
ment.  Some, such as aquifer use restrictions,
are voluntary and  are not enforceable. In addi-
tion, some states do not allow deed restrictions
to be  placed  on  properties  due  to inherent
problems associated with enforcement.
Because deed restrictions arc generally used in
conjunction with  other  remedial actions, the
specific prohibitions outlined in the restrictive
covenant are  based on  the  type of remedial
action implemented at the site  and how the
effectiveness  of that remedial  action can be
improved  through  deed  restrictions.    For
municipal  landfill sites, the  major purpose of
deed  restrictions is to protect the  integrity of
the cap.  The restrictive covenant should limit
subsurface  development (excavation), excessive
vehicular traffic (including off-road vehicles and
dirt bikes), and groundwawr use. Additional
deed restrictions may be required for effective
implementation of other technologies.    The
permissible uses/limitations  for  the  specific
landfill property should be identified based on
the risk the site poses and the remedial actions
likely to be implemented.

4.2.1.2 Fencing

When necessary, fencing is used to physically
limit  access to the landfill site. Signs may be
posted to  make clear to potential trespassers
that there  may  be a health threat associated
with  going  on the site.  Signs typically are
posted at equal intervals along the perimeter of
the site  and along roads leading  to the  site.
The most common type of fence used to limit
access is a chain-link fence about eight feet
high.  Barbed wire on top of the fence may also
be  required to deter trespassing. Gates alone
may be sufficient if only vehicular traffic needs
to  be limited. The primary  data needed for
fence evaluation is a determination of the area
to be fenced. First, however, the location and
potential risks of the landfill site, along with
local land  use restrictions, should be identified
to determine whether fencing  is necessary at all.

4.2.2. Containment

Containment refers to technologies that isolate
the landfill contents  and miligate offsite migra-
tion through the use of engineering controls.
Containment   technologies   include   surface
controls  and capping.

4.2.2.1 Surface Controls

Surface  control technologies are designed to
control and direct site runoff (potentially for
                                               4-3

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treatment) and to prevent offsite surface water
from running onto the site. These technologies
reduce water  infiltration into the  waste and
associated leachate generation, and slow down
the rate  of cap  erosion.   Surface  controls to
divert run-on and  minimize infiltration  at
municipal landfill sites  often are implemented
in conjunction with site closure. Such controls
are almost always employed in concert with
other technologies such  as. installation of a
landfill cap.  Landfill covers, like  any other
disturbed soils, are prone to erosion, which can
result in exposing and eventually  mobilizing
contaminated materials. Therefore, if necessary,
erosion and sediment controls should be consid-
ered, including  space requirements  for  sedi-
mentation basins and erosion control structures.
Surface controls most commonly used at muni-
cipal landfill sites are grading and revegetation.

Grading. Grading modifies topography in order
to promote positive drainage  and  control the
flow of surface  water.    A  properly  graded
surface will  channel uncontaminated surface
water around  the landfill, thereby minimizing
infiltration through the landfill  cap.

Grading is also the general term for techniques
that reshape the surface of landfills in order to
control erosion  and to manage surface water
infiltration,  run-on,  and runoff.    Designing
proper slope lengths and gradients, and creating
berms and swales are common grading tech-
niques used to control and route surface water.
Earth fill, typically from offsite borrow sources,
may be required to change slope gradients and
to construct earthen berms. Regrading existing
fill material is recommended in situations where
there is a significant quantity of fill, if analysis
shows the fill  is acceptable to  reuse.  Significant
cost savings could be made by using existing fill
and thereby  minimizing the cost of transporting
fill material from an offsite source.

Generally, slopes on top of the landfill range
from 3 percent to 8 percent in order to pro-
mote runoff and  control erosion.   Sideslopes
can be as steep as 3H:1V (33 percent) as long
as  benches  (horizontal steps)  are provided to
interrupt the slopes and thus control soil ero-
sion and maintain slope stability.    Steeper
slopes can exist under certain slope  conditions.
However,  the  use of slopes less steep than
3H:1 V is recommended.
3H:1 V is recommended
Municipal solid wastes usually settle during the
life  of a  landfill  due  to decomposition of
organic wastes and  the weight of superimposed
loads of refuse and soil. The settlement may be
significant, especially in the deepest points of
the landfill which typically are located at the
center of the landfill. Settlement cart result in
changing surface slopes and possibly flattening
some of these slopes. A well prepared grading
plan will take settlement into account by recom-
mending slopes that will still be effective after
settlement.  Potential settlement problems can
be identified by placing benchmarks that can be
surveyed at various times throughout  the RI/FS
process.    Continued operations  and mainte-
nance (O&M) will also be required to maintain
adequate surface slopes.

Grading techniques  are  well developed and
commonly  used in landfills  around the U.S.
They are often performed in conjunction with
capping and revegetation and have a consider-
able impact by reducing leachate generated due
to  infiltration.

Some implementation and  O&M considerations
concerning an adequate grading plan  include
the following:

    •    A well  designed grading plan should
        result in runoff  from the  site being
        controlled.    Also, water  that would
        otherwise run  onto the  site will be
        diverted.

    •    A properly graded site, will reduce the
        contact  time of runoff  water on the
        landfill, thus reducing the rate of infil-
        tration of surface water into the landfill.

    •    Erosion  of cover soil can be corm-ollcd
        through grading, and soil retention will
        encourage the growth of beneficial veg-
        etation.

    • '   The cost of earth fill may be high, espe-
        cially when  the  borrow  source  is
        remote. Free fill may be available from
        large  construction  projects.
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   •   There will be need for ongoing main-
       tenance because soil erosion and settle-
       ment of waste  can change  the  slope
       gradient.

   •   Some of the benefits such as reduced
       infiltration rate or  reduced volume of
       leachate can  be hard  to  quantify  in
       landfills where there  is no leachate
       collection  system.

In order to develop an adequate grading plan,
the following data should be gathered:

   •   Likely distance to borrow source

   •   The extent  to which the existing fill
       could be used as part  of  the grading
       plan

   •   Existing topography and boundary of
       project earthworks (area to be graded)

   •   Climatological  data  (for  example,
       precipitation)

   •   Stormwater retention and sedimentation
       boring requirements

   •   Soil data  for the grading soil (for
       example, runoff curve number, perme-
       ability grain size distribution)

   »   Slope  length  and  gradient limits~for
       example,   maximum  and  minimum
       length and gradient. (Top slopes range
       from 3 percent to 8 percent; sideslopes,
       if lined, typically are not steeper than
       3H: IV, with a bench for every 25-foot
       rise in elevation.)

   •   Maximum allowable erosion per acre—
       typically, 2 tons per acre per year (U.S.
       EPA, 1989d).

   •   Maximum stormwater flow velocity and
       type of material available  for ditch
       lining.    Ditch  or  channel  protection
       depends mainly on  the type of  soil
       where the  channel is being  excavated
       (for example, grass, gravel, gabions,
       grouted gabions, concrete, plastic lining,
       etc.). For example, channels excavated
in fine gravel  will require lining when  flow
velocity  exceeds 2.5 feet per second, while
alluvial silts can withstand velocities up to 2.7
feet per second without lining.

Revegetation. Revegetation is a method used to
stabilize the soil surface of a landfill site and
promote  evapotranspiration.     Revegetation
decreases erosion of the soil by wind and water,
reduces  sedimentation in  stormwater runoff,
and  contributes to  the  development  of  a
naturally stable surface.    It  is also used to
improve the aesthetics of the landfill, which, is
especially important when the site is being con-
sidered for use  as recreational land.

Revegetation is used as a temporary measure to
stabilize the soil surface  or  as  a permanent
feature when the closed landfill site is being
reclaimed for other uses. A systematic revege-
tation plan includes selection of a suitable  plant
species,  seedbed preparation, seeding/planting,
mulching and/or chemical stabilization, fertiliza-
tion, and maintenance.

Revegetation is used most in concert with  other
containment technologies  such as caps.  Since
most caps include an impermeable layer, revege-
tation  may require a drainage layer over the
impermeable layer to avoid rotting of the  plant
roots. In dry climates, irrigation may be neces-
sary at times to maintain  strong plants.  Trees
and shrubs with deep roots that might penetrate
the  impermeable  cover layer should be
prevented from growing on landfill covers.

Some  implementation and  O&M considerations
concerning revegetation include the following:

   •   Revegetation will reduce soil erosion by
       wind and water,  improve site aesthetics,
        and increase evapotranspiration due to
       plants.

   •    The requirement for periodic mainte-
       nance  (such as  mowing)  should be
       considered.

   •    The potential need for irrigation, which
        is costly and may  conflict with objec-
        tives of reduced  infiltration, should be
        considered.
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Some plant species commonly used for revege-
tation include Kentucky bluegrass, tall fescue,
meadow fescue,  redtop bentgrass, smooth
bromegrass, field bromegrass,  orchard grass,
annual ryegrass, timothy, and red canary grass.
Revegetation typically  includes grass  and
legume mixtures. Revegetation species can be
selected using  the  state's Soil Conservation
Service guidelines.  Also, the  EPA  Office  of
Research and Development has  developed a
computer model, tilled Veg Cover, which can be
used to provide information on  the selection of
revegetation species. Additionally, the type of
plant species to be used in different climates
and conditions can be found  in  Design  and
Construction of Covers for Solid  Waste Lamdfills
(U.S. EPA, 1979a).

The type of plant species  selected" for revegeta-
tion depends on a number of factors. Primary
data needs for determining an appropriate plant
species  for revegetation are:

   •     Type   of  seeding—temporary  or
        permanent

   •     Time of year when the seeding is to be
        performed

   •     Type of climate at the landfill (annual
        precipitation, low/high  temperatures)

   •     Topographic characteristics (for exam-
        ple, slope steepness,  drainage patterns)

   •     Soil characteristics (for example, nutri-
        ents,  pH,  moisture content,  organic
        content, grain size distribution)

Other  factors that should  be  considered  in
selecting  a plant species include:

   •     Minimizing the  level  of maintenance
        required after seeding

   •     Effects of increased surface soil perme-
        ability due to root system and possible
        increased  infiltration through  the cover

4.2.2.2 Cap (Landfill Cover)

The selection of an  appropriate cap design will
depend not only on the technical objectives but
also on risk factors and the identified ARARs
for the landfill  site.  A discussion and  some
examples of potential ARARs for municipal
landfill sites are presented in Section 5. Addi-
tional guidance for determining requirements to
CERCLA sites can be found in the  CERCLA
Compliance with Other Laws Manual: Part I
(U.S. EPA, 1988c).

A determination should  be made on  which
RCRA  closure requirements are  relevant and
appropriate  for  the  specific site  of concern.
RCRA  Subtitle  D closure requirements  are
generally applicable unless a determination is
made that Subtitle C is applicable or relevant
and  appropriate. In general, RCRA Subtitle C
would be applicable if the waste  is a listed or
characteristic waste under RCRA, and the waste
was disposed of after November 19, 1980 (effec-
tive  date of RCRA) or  the response  action
constitutes treatment, storage, or disposal, as
defined  by  RCRA.      The  decision  about
whether a RCRA requirement is  relevant and
appropriate is based on consideration of a vari-
ety of factors, including the nature of the waste
and its hazardous properties, arid the nature of
the requirement itself.  State closure require-
ments that are more stringent than the Federal
requirements must be used in determining a
final cover  design.  These regulatory require-
ments should be integrated with  the technical
objectives for the site, based on site characteris-
tics, to  determine the best capping alternatives
to be evaluated in detail.

Capping technologies  may be  designed  to
reduce  surface water infiltration,  control emis-
sions of gas and  odors,  reduce  erosion, and
improve aesthetics. Capping technologies also
provide a stable outside surface  that prevents
direct contact with wastes. The different types
of cappinig technologies typically used  at land-
fills  include:

   •    Native soil cover
   •    Single barrier (e.g., clay)
   •    Composite  barrier  (e.g., clay plus  FML)

Figure  4-1  is a simplified decision tree for
determining  an appropriate profile cap based on
site and waste characteristics.
                                              4-6

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  LANDFILL CHARACTERISTICS
REMEDIAL OBJECTIVES
                                                                                  COVER TYPE

I Minimal Hazardous Substances in
 Landfill and Minimal Contamination
 of Ground water
 Significant Percentage of Hazardous
 Substances in Fill Are Below the
 Water Table, And Lowering the
,Water Table Is not Practicable
 Leaching of Hazardous Substances
 to Groundwater Is Expected to
 Contribute to Unacceptable Human
 Health  or Environmental Risks,
 Reliability of Single Barrier Is
 Considered Adequate,0  and
 Potential/Actual Landfill Gas
 Emissions
!Prevent Direct Contact;
Minimize Erosion a
                                    Native Soil Cover
                                                                                                  J
                                              [Prevent Direct Contact;
                                              Minimize Erosion;
                                              Minimize Infiltration;
                                              Control Landfill Gas
                                              Emissions           j
                               C
                                  Single-Barrier Capb
 Significant Contaminant Mass
 in Fill, and Risks of Hazardous
 Substances Leaching to
JSroundwaler Are Great	


 (High Degree of Reliability Needed  i
 in Method of Minimizing Leaching
 of Hazardous Substances to
 Groundwater and Controlling
 Landfill Gas Emissions            /
                                              Prevent Direct Contact;
                                              Minimize Erosion;
                                              Prevent Infiltration;
                                              Control Landfill Gas
                                              Emissions
                                I  Composite-Barrier Cap J
  Primary objective is to prevent direct contact, although the soil cover can be designed to reduce infiltration.

b Single-barrier caps may include additional layers that provide protection to that barrier.

c Examples include situations where infiltration is not the primary concern and may include sites containing a
  small volume of contaminant mass, regions with low annual precipitation, or sites where groundwater is not
  being used as a source of drinking water.
                                                                                                                      Figure 4-1
                                                                                         LANDFILL COVER SELECTION GUIDE

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The primary data needed for designing
system include:
a cap
   •   Depth to ground-water beneath waste
       (caps may be of limited benefit in areas
       of high groundwater if they are the only
       remedial action used)

   •   Availability of cover materials  (caps
       may be  high  in cost if the desirable
       material is not locally  available)

   •   Rate or magnitude of waste settlement
       under the cap  (changes in waste thick-
       ness, degree  of decomposition, and
      potential presence of large, near-surface
       voids should be known)

   •   Steepness of slopes

   •  Cover soil characteristics

           Proctor compaction Properties
           Permeability
           Grain size gradation
           Shear Strength
           Atterberg  limits
           Field moisture capacity

   •   Maximum frost depth at the location of
       the site

   •   Anticipated weather  conditions at the
       site (for example, temperature, precipi-
       tation, wind)

   •   Proximity to residential, commercial, or
       industrial units

   •   Future land use of the site

The efficiency of the covers may be calculated
using EPA's computer model, HELP (hydro-
logic  evaluation  of landfill performance).
HELP is  a  quasi-two-dimensional  hydrologic
model of vertical water movement through the
landfill cap. The model accounts for the effects
of surface water runoff, evapotranspiration, soil
moisture  storage, and lateral flow  through
drainage layers to predict the rate of  water
infiltration through covers. The HELP model
is available from EPA's Risk Reduction and
Engineering Laboratory (RREL) in Cincinnati,
Ohio.
Soil Cover. The use of native soil (nonclays) as
cover for containment of wastes may be appro-
priate in arid climates where surface water infil-
tration (and subsequent leachate generation) is
not a controlling factor. Native  soil caps are
used when the primary objective is to control
erosion and prevent direct contact. However, in
regions having more evapotranspiration poten-
tial than rainfall, native soil covers can be engi-
neered to, also reduce infiltration.   This is
accomplished  by  incorporating  field storage
capacity within the cap sufficient to store the
largest seasonal inflow event.    Such water
balance designs can be performed and verified
using the HELP model. Native soil covers may
also  be appropriate on  stabilized or solidified
wastes, or as temporary caps to prevent direct
contact  with wastes. A temporary cap as  an
interim action may be warranted in situations
where the  settlement rate of the  landfill
contents has not stabilized.

Native soils used to reduce the rate of infiltra-
tion  in arid regions typically have high field
storage  capacities (for  example, 0.3 vol/vol).
Soils with high field storage capacity have a
high percentage of fine material (passing U.S.
No. 200 sieve for example, silts and sandy silts).
Also, native soils can be mixed with additives
and  mechanically compacted  to lower their
permeability and make them more suitable for
reducing infiltration.  The required  field storage
capacity and permeability of soil that is used to
reduce infiltration depends on the following
factors:

   •   Climatological data for the region
       where  the  landfill  is located  (for
       example,  precipitation  for the  design
       storm event,  temperature, and depth of
       evaporative zone)

   •   Characteristics related to the type and
       condition of vegetation that is expected
       to be planted (for example, evapotrans-
       piration)

   •   Physical characteristics of the site {for
       example, slope gradient and thickness of
       native  soil layer)

Unless a water balance analysis  is performed as
part  of the design of a native soil  cover, the

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native soil cover provides only separation, pro-
tection, and/or a vegetative layer.   Generally,
native soils are suitable for vegetation due to
their high organic content. Atypical native soil
cover that provides these limited functions is 18
to 24 inches deep, has a permeability less than
or equal to 1 x 10"5 cm/sec, and  a field storage
capacity less than 0.3vol/vol.

Implementation   and  O&M  considerations
concerning native soil covers include the follow-
ing:

   •    Soil covers are generally low in initial
        cost.

   •    Construction materials generally are
        readily available from local  sources.

   •    Soil covers  usually should be vegetated
        to minimize  erosion;

   •    Unless designed to do  so, soil covers
        are not very effective in reducing infil-
        tration. (If reduced infiltration  is the
        design goal, field  permeability testing
        should be performed prior to construc-
        tion to verify  that the expected low
        permeability can be achieved.)

   •    Erosion can expose waste if cover is not
        adequately  maintained through contin-
        ued O&M.

   •    Native soil may not be naturally useful
        as a barrier  layer in many cases and may
        require processing.

   •    Native soil may not be stable on steep
        slopes (greater than 33 percent); there-
        fore, constructibility may limit the slope
        to less than 25 percent.

 Single Barrier. The main functions of a single
 barrier landfill cap are to  reduce surface infil-
 tration, prevent direct contact,  limit gas emis-
 sions, and control erosion. The two most com-
 monly used barrier  layers are clay soils and
 FMLs. Both serve as low-permeability  barrier
 layers that reduce surface water infiltration into
 the  landfill.     The  barrier  layer is  usually
 overlain by a drainage layer and/or  a vegetative/
 protective layer. A water balance analysis must
be performed if a drainage layer is incorporated
into the cap. The clay materials generally used
are natural clays but also can be processed clay
minerals such  as bentonite mixed with native
soils. The clay  barrier must have a permeability
less than 1 x 10"7to be effective as a barrier. If
bentonite is used, the high shrink-swell poten-
tial needs to be considered.

Clay materials can achieve very low permeabili-
ties (e.g.,  1 x 10"' cm/sec)  if  they are  well
compacted and if their moisture  content is  opti-
mum, as  determined in the laboratory. Upon
surface drying, clayey soils form desiccation
cracks that can allow surface water to infiltrate.
Also, in cold climates, clay may be damaged by
freeze-thaw action unless it is buried below the
frost depth. In order to prevent  surface drying,
a layer of cover soil should be placed over the
clay layer to aid in maintaining the clay's mois-
ture and to provide a base for revegetation.
Also, a soil cover layer can prevent freeze-thaw
damage to  the clay  if the cover layer is  of a
depth equal to or greater  than the local maxi-
mum frost depth.

FMLs, on the other hand, are synthetic materi-
als that, if punctured, can allow surface water to
permeate into the landfill. A cover of soil over
the FML, as well as a bedding  layer under the
FML, is necessary to protect the integrity of the
liner and to allow for revegetation.

Recently, bentonite panels have been marketed
for use as  liners for municipal landfill sites.
Previously, these panels  have been used for
lining impoundments  and  lagoons,  water-
proofing  structures, lining spill containment
areas, and similar uses. The panels consists of a
dry granular sodium bentonite layer approxi-
matly  1/4 inch thick with a woven geotextile on
each side which allows some bentonile, upon
hydration,  to seep through the mesh to facilitate
a seal between  overlapping panels.   When
hydrated, the bentonite is  capable of expanding
up to 15 times its former volume if unconfined.
This characteristic  provides a seal when the
material is confined and provides some  self-
healing at small holes or  penetrations. Several
landfill sites are presently using these panels
with apparent success.   However, use  of  these
panels may require  demonstration to the appro-
priate regulatory agencies  that the preferred
                                                4-9

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liner system will meet the performance objec-
tives of the applicable regulations, even if the
regulations, as written, are not met. Care must
be  used in applications of  bentonite board
barriers on slopes.  As the bentonite hydrates,
its shear strength decreases and slope failures
may result.

Weather conditions must be considered when
constructing a landfill cap. If clay is used, dry,
windy  climates make  moisture control difficult.
Freezing temperatures, rain, and excessive natu-
ral  moisture  make proper placement of clay
difficult. FML installation  is not affected as
much by hot, dry, or wet weather, but wind and
cold temperature can cause  problems.  Caution
must be used in wet  weather, however,  to
ensure the  integrity of FML seams. The FML
must be dry for proper seaming.

Subgrades for both clay and FML barrier layers
must be prepared to  provide  a sound founda-
tion for the  barrier  layer.  This may require
stripping existing vegetation, scarifying and
compacting existing cover soils,  or placing and
compacting a  layer of fill. The integrity of the
foundation layer should be verified  by proof
rolling, when possible.    Visible soft  zones
should be excavated  and recompacted, A
smooth steel roller should be  used to  dress the
surface of the subgrade before placement of an
FML.

A typical cross section of a single-barrier cap
consists of the following layers (from visible top
to top  of waste):

    •    Vegetative    and protective  layer--
        24  inches of native soil

    •    Optional drainage layer- 12  inches of
        sand (permeability > 1 x 10"2cm/sec) or
        a composite drainage net

    •    Barrier layer--.24 inches of clay (perme-
        ability six  10"7cm/sec)  or  a 30-mil
        (minimum) FML

    •    Bedding layer-  12  to  24  inches of
        compacted select native  soil  or sand
        subgrade
Regulations of individual  states or specific
applications   may require  a  different  cross
section; however, the  function of the above-
described system would meet the intent of most
requirements of a single-barrier cap.

Some implementation and O&M considerations
concerning  single-barrier  caps  include  the
following:

       Either a clay or FML cap should result
       in low permeability and reduction of
       infiltration.

   •   There  is a known history of operating
       and placement  experience for both clay
       and synthetic liners.

   •   A single barrier clay cap can be relative-
       ly low in cost if clay  is locally available.
       However, it may be very expensive if the
       borrow source  is remote.

   •   Several choices of materials are used to
       manufacture  FMLs (e.g.,  PVC, HDPE,
       etc.) depending on the specific applica-
       tion.    The  selection of material is
       usually made during design.

   »   An FML cap may be  more difficult to
       repair  than a  clay cap.

   •   A clay cap may be made less  permeable
       by increasing bentonite admixture.

   •   A clay cap and an FML require careful
       placement with slrict QA/QC, especially
       around any gas vents.

   •   Both  FMLs  and  clays may react to
       chemical attack and become  more per-
       meable.

   •   Clay caps require careful design  and
       strict QA/QC.  Field permeability tests
       should be conducted  before  construc-
       tion to verify that the desired low per-
       meability criterion  can  be  achieved
       using  the specified material and equip-
       ment.
                                              4-10

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   •   Clay caps maybe subject to damage by
       weather  elements  (freeze-thaw and
       surface drying).

   •   Problems may rise with clay or FML
       caps and/or drainage layers in cases
       where substantial landfill settlement is
       expected.

   •   In some  cases,  it  may be useful to
       construct a temporary cover until the
       rate  of settlement  subsides and then
       construct a final cap.

Composite Barrier.   A composite-barrier  cap
provides an  additional barrier layer, which
reduces the rate of infiltration more  than a
single-barrier cap does. A composite barrier
consists of a compacted clay layer overlain by a
synthetic liner (FML).  The composite barrier,
in turn, is overlain by an optional drainage layer
and by a top vegetative/protective layer.

   •   The vegetative/protective layer provides
       stability  and erosion control.   It also
       provides  protection for the  synthetic
       liner and for the  drainage layer.

   •   The synthetic or natural drainage layer
       provides drainage  of infiltration water
       in order to maintain a hydraulic head of
       no more  than 1 foot on  top of the syn-
       thetic liner barrier.

   •   The  synthetic and  clay barrier layers
       provide   maximum   infiltration
       protection.

   •   The subgrades under the bottom barrier
       layer and overtop of the waste provide a
       bedding  layer  and can act as a gas
       collection layer, if required.

A composite-barrier cap is to be used when the
landfill contains RCRA listed wastes, waste
sufficiently  similar to RCRA listed waste, or
RCRA  characteristic waste.  The  need for a
composite-barrier cap in cases where  landfills
contain   much    lower    concentrations  of
hazardous  contaminants than that of RCRA
characteristic or listed wastes must be judged on
a site-specific basis and may depend on factors
such as site characteristics  and potential
receptors.    Composite-barrier caps arc  also
required in some states (New York 6NYCRR
Part 360) for closure of municipal solid waste
facilities.

RCRA provides technical guidance (U.S. EPA,
July 1989d) that defines the types of layers EPA
considers to be appropriate  for a cap for  new
RCRA landfill cells. This guidance is a TBC
(to be considered) and is intended to meet the
RCRA regulations requiring a cap of equal or
lower permeability than underlying liners or
native soils. The minimum thicknesses for the
layers in a RCRA cap (from visible top to top
of waste) are as follows:

   •   Vegetative and protective layer--24
       inches of native soil

   •   Drainage layer-  12 inches of sand (per-
       meability > 1 x.lO"2cm/sec) or geonct
       (transmissivity > '. 3 x lO'mYsec)

   •   First  barrier  layer  component~FML
       (20-mil minimum)

   •   Second barrier  layer component-24
       inches  of clay (permeability  1  x 10"7
       cm/sec)

   •   Bedding layer (optional)~12  inches of
       native soil or sand subgrade

The final design profile of a typical composite
cap  will also  include geotextiles as  a filter
between the protective cover and the  drainage
layer and as a protective layer over the  synthetic
barrier if a  layer of natural drainage stone is
used.   A  geosynthetic  must not be placed
between the two barrier layers or the effective-
ness  of the composite will be compromised.
Multilayer caps pose  a stability problem on
slopes.  Laboratory direct shear  tests  must be
performed to  measure the interface  friction
angles between the various layers. To ensure
stability, a slope  stability analysis should be
performed for each interface.

Some implementation and O&M considerations
concerning composite-barrier caps include the
following:
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   •   A composite barrier provides enhanced
       protection against infiltration.

   •   Onsite material potentially can be used
       for some of the layers.

   •   A  composite-barrier cap  will meet
       RCRA requirements for new landfill
       cells.

   •  Construction requires strict QA/QC.

   •   Stability problems may occur on side-
       slopes greater than 10 percent.

   •   Problems  may  arise with clay layers,
       synthetic barriers, and/or drainage layers
       in cases where substantial landfill settle-
       ment is expected.

   •   Lysimeters may be useful to  monitor
       the cover  performance (leak detection)
       where cover stability is uncertain.

       In  some  cases, it may  be useful to
       construct  a temporary  cover until the
       rate of settlement subsides and then
       construct a final composite-barrier cap.

4.2.3  Removal/Disposal

Removal of  contaminated soils at municipal
landfill sites is generally limited to hot  spots or,
when practicable, to landfills with a low to
moderate  volume of  waste (e.g., less than
 100,000 cubic yards). Complete excavation of
the municipal  landfill  contents is often not
considered practicable, because of the large
volume of waste  typically found at CERCLA
municipal landfill  sites.  No.,  examples of
complete excavation were found in the review
of remedial actions outlined in the RODS listed
in Appendix B.

As previously stated, hot spots that are  appro-
priate for  excavation and removal should be
indiscrete, accessible  locations of a  landfill
where a  waste  type  or mixture  of wastes
presents a principal  threat to human health or
the environment.    The  area should  be large
enough so that remediation will significantly
reduce the risk posed by the overall site and
small enough to  be reasonably practicable for
removal  and/or treatment.  Hot spots will not
be investigated and characterized unless some
form of documentation or physical evidence (for
example, aerial photography) exists to support
their existence. In cases where it is not clear
whether a hot spot poses a principal threat and
it is practicable to excavate, at least one alterna-
tive should be developed for removal/treatment
of that area. This alternative will be considered
during detailed  analysis  of remedial action
alternatives.

4.2.3.1 Excavation (Hot Spots)

Excavation of hot spots will be required prior
to consolidation, treatment (except in situ treat-
ment)  or disposal offsite.  Excavation of hot
spots to remove contaminated soils will require
the use of standard construction equipment or
special equipment adapted to minimize distur-
bance  of the deposit or secondary migration.
Also,  any excavations must  be performed in
accordance with OSHA. Typically, mechanical
equipment such as backhoes, bulldozers, and
front-end loaders is used  for excavation. The
use of scrapers and draglines usually makes it
difficult  to adequately control site dispersion.
While the  selection of  specific equipment
normally is based on contractor preference, the
selection also depends on the water table loca-
tion, the water content, and consistency and
strength  of the contaminated soils to be  exca-
vated.  It  is almost always cost-effective to exca-
vate contaminated  soil in thin, 4- to-12-inch
layers  to minimize the volume to be managed.

In many cases, due to landfilling practices and
the weight of overlying material, drums may be
crushed  and empty.   Isolated drums located
throughout the landfill may not be identifiable
nor represent a principal threat. In the  event
that buried,  full drums are  encountered, the
hazards  associated with  the  drums must be
evaluated. Evaluation may be accomplished by
staging, opening, sampling  and analysis followed
by transport and disposal.  Ambient air should
be monitored  continuously during  drum
removal  activities.  A drum  grappler, a drum
cradle or sling attached to a backhoe or crane,
or  a  front-end loader can be  used for drum
removal.    Drums may be  opened by bung
removers or drum cutters. Depending on their
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condition, removed drums may need to be over-
packed into salvage drums prior to transport.

Some implementation and O&M considerations
concerning excavation include the following:

   I   Excavation of hot spots is  a conven-
       tional, demonstrated technology  that
       can be cost-effective, particularly when
       areas  are consolidated with other land-
       fill material prior to capping.

   I   Solid  material above the water table can
       be excavated with very little secondary
       migration and good control of depth of
       cut. By  using  the  proper excavation
       equipment   and sediment control
       devices, the effect of surface runoff can
       be minimized.

   I   Waste disposal may require handling,
       stockpiling, and truck hauling of large
       volumes of material.

   '   Good control  of depth of excavation
       can be difficult under water. In some
       cases, excavation would require  the
       construction of impermeable barriers
       and site dewatering.

   Z   In situations where excavation extends
       below the water table, dewatering is
       likely to be required.  Consideration
       should be given to seasonal fluctuations
       in the groundwater table. Significant
       shoring and dewatering costs may be
       eliminated by excavating at times when
       the water table is low.

   I   Site  accessibility to heavy  equipment
       should be evaluated  to determine
       whether track vehicles may be required.

   I   The   distance  over  which  excavated
       material must be hauled should be eval-
       uated  to  determine whether separate
       moving  equipment (such as  dump
       trucks) is required.

   '   Seasonal (climate) constraints on exca-
       vation activities may  affect the schedule
       for excavation.   Depending on the  size
       of the area, temporary enclosures  and
portable heating  devices  may be  used
excavation occurs during winter months.
                                          if
   t   Enclosure of the excavation area may be
       necessary if volatile" organic compound
       (VOC) emissions are high.

   I   Potential exposure to  workers  and
       nearby communities during excavation
       must be considered. Enclosed cabs  may
       be necessary to minimize  operator expo-
       sure.

The primary data needs for preparing an exca-
vation plan for removal of contaminated materi-
als  include:

   I   Waste characteristics—Excavation is not
       suited for materials with a low solids
       content (dewatering may be required).
       Total suspended  solids  (TSS),  total
       dissolved solids (TDS), volume-weight
       (percentage of moisture) analysis  may
       be  necessary  to determine  the solids
       content if contamination extends below
       the water table.   Other data such as
       particle  size, viscosity, and pH may also
       assist  in material  handling needs.
       Analysis for hazardous waste parame-
       ters (for example, TAL metals, TCL
       organics) and geophysical testing (for
       example, magnatometry  or  ground
       penetrating radar)  may be warranted if
       the  presence  of buried  drums is
       suspected.

   I   Water table levels  (and seasonal fluctu-
       ations,  if data exists)

   '   Volume  of contaminated  material

   t   Geologic characteristics  from geologic
       maps and boring logs to assess difficulty
       of excavation

   '   Climate information  from  National
       Climatic Center (NCC) or local weather
       bureau  to  assess  frequency of rains,
       seasonal variations  in temperature
                                             4-13)

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4.2.3.2   Consolidation.

A common disposal  option  for outlying hot
spots at municipal landfill sites is consolidation
with other landfill material followed by capping.
Consolidation may also be a practicable alterna-
tive, for disposal of wastes in undesirable loca-
tions (for example,  wetlands) or contaminated
sediments. The objective of consolidation is to
relocate contaminated material from  outlying
areas into the landfill  contents to minimize the
required size of a landfill cap.

Since  consolidation  within the area of contami-
nation is  not considered management of the
material,  Land  Disposal Restrictions (LDR)
requirements do not apply. Therefore, material
can be consolidated without being treated first.
In situations where contamination has spread to
eroding sideslopes, contaminated  soil can be
excavated and consolidated within the landfill,
thereby reducing the required area of the cap.
Consolidated material can also be used as fill
under the  cap as called for by the grading plan.

Some implementation  and O&M considerations
concerning consolidation include the following:

   •   Consolidation  is usually implemented in
       conjunction with capping,  and the cap
       design may be influenced by the volume
       and nature of the material being consol-
       i d a t e d .

   •   Consolidation  may require  handling,
       stockpiling, and truck hauling of large
       volumes of  material.

   I   Considerations  and data needs,  listed
       under   excavation   should  also  be
       reviewed.

   Z   Potential exposure to  workers and
       nearby communities during consolida-
       tion activities must be considered.

The primary  data needs to evaluate consolida-
tion are basically covered under the data needs
for preparation of an excavation plan: The
most important information to coordinate with
the selection and design of a landfill cap will
include:
   I   Waste characteristics  of hot spot-deter-
       mined during site characterization

   '   Volume of contaminated  material

4.2.3.3  Disposal Offsite  (Hot Spots)

Offsite land disposal is generally  considered the
least  desirable  alternative  for  remediation.
However, offsite disposal may be employed if
onsite treatment followed by disposal under the
landfill cap is not feasible. Onsite disposal may
not be feasible or practical if the  waste is regu-
lated under RCRA and must be disposed of in
a  RCRA  landfill.

The requirements for offsite disposal of contami-
nated soils will be based largely on the RCRA
LDRs. The LDRs  may be applicable  to the
contaminated soils  if it is determined that the
soils have been contaminated by a restricted
listed RCRA waste or if the contaminatated soils
exhibit a RCRA hazardous waste  characteristic.
As previously stated, LDRs  do not apply if the
hot spots are to be consolidated (only) under
the landfill cap.

If it is determined that  the contaminated soils
are a RCRA waste, the LDRs  may require that
a specific concentration level be  achieved prior
to land disposal in a RCRA landfill  or that a
specified technology be used for treatment prior
to disposal in a RCRA landfill. If a concentra-
tion is specified and the soils are below these
concentrations,  the  soils do  not have  to be
treated  prior to offsite  disposal in  a RCRA
landfill. It is  possible that treated soils, particu-
larly  if  incinerated,  could be  delisted and
disposed of onsite or in a solid waste landfill.

If the  soils  are a  RCRA waste, offsite  land
disposal must be at  a  permitted RCRA
hazardous waste landfill that meets the require-
ments  of RCRA Subtitle C.  The design fea-
tures of a RCRA hazardous waste landfill are
defined in 40 CFR 264 Subpart N. The major
requirements  of such landfills include an imper-
vious cap; a double liner; a leachate detecticm,
collection, and  removal  system; run-on and
runoff control  systems;  and wind  dispersal
controls.
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In the absence of other regulations, solid waste
landfills  will be  regulated  under  RCRA
Subtitle D. In most cases, however, state regu-
lations govern the design, construction, opera-
tion,  and  closure  of solid  waste landfills.
Currently, in many states, the requirements for
new solid waste landfills are approaching the
complexity and restrictiveness of requirements
for disposal of hazardous waste.

CERCLA Section  121(d)(3) and the CERCLA
offsite policy contain another  set of require-
ments  that will impact the offsite disposal of
CERCLA wastes. EPA's current offsite policy
(OSWER  Directive  9834.11, November 13,
1987ff)  describes  procedures  that must be
observed  when  a  CERCLA response action
involves  offsite management  of CERCLA
wastes. The general requirements of the offsite
policy are to be codified and  expanded  in a
proposed rule, which will supersede the current
policy when finalized  (see 53  FR 48218
(November 29,  1988)).  Generally,  this policy
requires  that an offsite facility accepting the
waste have no relevant violations or other envi-
ronmental  conditions that pose a  significant
threat to public health, welfare, or the environ-
ment, or otherwise  affect the satisfactory opera-
tion of the facility. The purpose of this policy
is to direct these wastes only to facilities deter-
mined to be environmentally sound and  thus
avoid  having CERCLA waste contribute to
present or future environmental problems. A
Regional  Offsite Coordinator has information
on the acceptability of commercial facilities in
the region to receive CERCLA wastes.

Some implementation and O&M considerations
concerning  offsite disposal of contaminated  soils
in a RCRA or hazardous waste landfill  include:

   I   Landfilling may be the best  or  only
       disposal   method  for  certain solid
       hazardous wastes.

   *   Based on LDRs, treatment of soils may
       be  required prior  to disposal.

   I   In  addition  to  the  LDRs,  offsite
       disposal    must    comply   with    the
       CERCLA offsite policy.
   I    High volume wastes may be disposed of
       more  economically by landfilling than
       by treatment, although landfilling does
       not reduce toxicity, mobility, or volume
       of wastes.

   •    Waste handling and  landfilling tech-
       nology is well developed.    However,
       offsite disposal in a landfill cannot be
       considered permanent remediation of
       the contaminated material, and future
       risk and liability are  associated with
       landfilling of wastes.

There  are  no specific  desing considerations
associated with offsite  disposal; however,  associ-
ated technologies such as excavation and soils
treatment may be employed prior to  offsite
disposal.

In order to evaluate the offsite disposal options,
the following data should be gathered:

   I    Characteristics of waste  to determine
       suitability for offsite disposal (for exam-
       ple, RCRA characteristic tests, moisture
       content, hazardous  waste parameters).
       The potential landfill(s) that may be
       used  for offsite disposal should be
       contacted to  determine what analysis
       they require.    These  tests should be
       included in the analysis of hot spots.

   t    Volume of waste to be disposed offsite.

4.2.4 Hot Spots Treatment

Based on review of the remedial  actions that
are being conducted  at municipal landfill  sites
on the NPL,  it was found that the most often
selected  soils treatment technology  is onsite
thermal treatment (incineration). Offsite incin-
eration is rarely chosen as an acceptable alter-
niative because of the current lack of available
capacity. Although in-situ treatment is likewise
rarely used,  this type of  response  action
particularly  in-situ  stabilization  and  in-situ
vapor  extraction, may warrant some consider-
ation if the type of soil contamination is treat-
able by this technology. Other technologies for
treatment of hot spots are, at the present time,
rarely  selected. This  is probably because of the
heterogeneous nature of landfill wastes and the
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corresponding complexity  associated with imple-
menting in situ technologies at landfill sites. As
with excavation, soil treatment is considered a
feasible alternative only for hot spots and, when
practicable, for contents of small to moderate
landfills (e.g., less than 100,000 cubic yards).

4.2.4.1 Thermal  Treatment (Onsite)

Thermal,  treatment is an appropriate  method
for the destruction or treatment of combustible
organics in soil.  Onsite thermal treatment can
be  conducted in  a  field-erected facility  or
mobile unit. Low temperature thermal volatil-
ization can also  be used to remove VOCs (or
semivolatiles if  operated at  high  enough
temperatures) in a soil  drying unit.  However,
this  technology is rarely effective by itself
because of the mixed nature of landfill waste
material that includes inorganic and nonvolatile
fraction of organics.

Thermal treatment exposes waste material to a
high temperature for a specific period  of time.
When,  heated in the presence  of  sufficient
oxygen for combustion (incineration), the waste
is chemically transformed into innocuous sub-
stances such as carbon dioxide and water. This
process also produces ash and  a certain amount
of oxides and acid  gases, depending on the com-
position of the waste and the process  conditions
under which it is oxidized. When heated in the
absence  of oxygen (pyrolysis), the waste
decomposes, producing a residue, and a variety
of vapor-phase  compounds that can  then  be
incinerated.

Analysis,   and characterization  of.  the waste
usually determine whether it can. be  treated by
incineration.   The analysis also provides the
physical property data used in  the  design, of
process equipment.

Incineration technologies include rotary kiln,
fluidized  bed, multiple hearth,  radiant heat,
molten salt, liquid injection, and molten glass.
Pyrolysis  technologies  include  conventional
pyrolytic reactors, rotary hearth pyrolyzer, ultra-
high temperature reactors,  and starved-air
combustion. The most commonly used, system
has been  rotary kiln incineration. It is usually
desirable  not to  specify in the feasibility study
which incineration process option will  be used.
Rather a representative option, such as rotary
kiln, can be presented as an example with the
actual  process option  decision  being  made
during design or by  the contractor based on
performance specifications. It should be noted
that the use  of  performance specifications
allows for a variety  of both innovative and
established  incineration technologies  to be
considered.

Some implementation  and O&M considerations
concerning  the use of thermal treatment for
contaminated  hot spot material  include  the
following:

   •   Space requirements typically are modest
       but should be  considered.

   •   Typically, efficiency of destruction is
       high,  emissions can  be effectively
       controlled, and destruction/treatment is
       immediate.

   •   Waste heat recovery may be possible
       and  should be considered.

   •   The weight and volume of combustible
       waste  may be reduced by more than
       90 percent through thermal treatment.
       In  some  cases, incineration of solid
       waste (e.g., soils) may result in little or
       no reduction  in volume;  however, the
       solid feed will be decontaminated.

   •   Residues may  be delistable and disposed
       of onsite  (although exceedance of the
       TCLP characteristics  for metals may
       require solidification prior to onsite
       disposal).

   •   Capital and operating costs are typically
       high and should be considered.

   •   Ash disposal may  have to be  at  a
       RCRA landfill if it  is classified as a
       hazardous  waste.

   •    Supplemental  fuel  is required for
       startup and may be necessary to main-
       tain combustion.

   •    Significant  material handling, prepro-
       cessing, and  post-processing  may  be
                                              4-16

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       required  (for example,   for  rocks,
       drums).

   •   Products  of  incomplete combustion
       (PICs) may be generated that are diffi-
       cult to assess or control.

Data needed for evaluation of thermal treat-
ment technologies and for design  purposes
include the following:

   •   Waste characterization data  (For wastes
       with high concentrations of inorganic,
       thermal treatment may not bei the best
       alternative, or other treatment technol-
       ogies may  be needed in  conjunction
       with incineration. Also, physical char-
       acteristics  such as large percentage of
       rocks and  boulders may indicate that
       waste segregation or pretreatment is
       required.)

   •   Heat content of waste (A BTU analysis
       should be done to evaluate the need for
       auxiliary fuel.)

   •   Pilot testing during either the feasibility
       study  or the predesign phase  (Such
       testing is often required to evaluate the
       treatability  of the contaminated soils by
       thermal means.)

4.2.4.2 Stabilization

Stabilization,  which  is used for treatment of
viscous fluids, solids, and contaminated soil, is a
feasible option for hot spots. To date, stabiliza-
tion (or solidification) has rarely been used at
municipal landfill  sites. However, it appears to
be potentially feasible for soils contaminated by
inorganic. Stabilization has also been used for
treatment   of  low-level-radiaticm-contarrtiriated
soils and for soils contaminated by low concen-
trations of organics, whereby leaching of orga-
nics is reduced but not eliminated.

Stabilization  using an  onsite  batch process
consists of excavation of wastes, onsite mixing
with reagents in a batch plant (for example,  a
cement kiln)  and  finally, replacement  in  the
landfill area. Use of a batch process will trigger
LDRs;  treated waste will either  have to be
disposed of in an offsite RCRA landfill or may
be delisted, and disposed of onsite or in an
off site solid waste landfill. In situ stabilization
refers  to processes where stabilizing reagents
(pozzalanic material) are added in place to
improve physical characteristics of waste by
rendering wastes nonhazardous and nonleach-
able.  Reagents  are  mixed with the contami-
nated waste using standard earth-moving equip-
ment  such as backhoes, drag  lines,  bucket
loaders, or by large-diameter augers.  In situ
stabilization offers the advantage that soils can
be treated in place.   However, greater quality
control, such as assurance of complete mixing
of regents, can be achieved using a balch plant.

Pretreatment such as screening, segregation, and
removal of larger objects such as drums and
debris may be necessary.  In situ stabilization is
typically accomplished in relatively shallow lifts,
commonly about 2 feet deep,  since large quanti-
ties  of materials  are  moved  as  a mass to
accomplish mixing. Depth of contamination is
also  generally  limited to, approximately  12 feet,
although this technology can potentially  be used
for  deeper contamination  by  progressively
removing  solidified wastes  while  increasing
working depth.    For deeper sites, excavation
and  addition  of reagents using a batch plant
may be appropriate.

The  ratio  and composition  of reagents vary
depending on the waste.   A  wide range  of
common pozzolanic stabilizing reagents  can be
selected, depending on what is locally available,
and reagents can be proportioned on the basis
of untreated waste  characteristics.   A typical
formulation of  stabilizing  agents  might be
30 percent fly  ash, 30 percent  kiln dust,
20 percent portland cement, and 20  percent
hydrated lime.    Most  inorgaric  hazardous
sludges can be mixed directly with  pozzolanic
materials to form a hardened soil-like material.
Extraneous materials such as asbestos, sulfides,
and  solid plastics may increase the  strength of
the treated material. Impurities such as organic
materials, silt, clay, lignite, fine dust, sulfates, or
soluble metal salts may retard or inhibit setting
and  curing, may reduce strength, or may cause
swelling and splitting of the solidified mass.
Typically,  wastes  containing  high levels  of
organic (e.g., 10 to 20  percent) constituents
require some form of pretreatment before solid-
ification with pozzolanic  materials.  Treatability
                                               4-17

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studies must be performed to determine if the
contaminated waste/soil is amenable to stabili-
zation.

Because of the nature of stabilization, the final
volume  of treated waste typically is  10 to
30 percent greater than the original volume of
waste.    However, volume increases of 50 to
 100 percent are possible, depending on waste
and site characteristics.

Some implementation and O&M considerations
concerning stabilization include the following:

   •   A wide variety of inexpensive reagents
       is available

   •   The technology is applicable to many
       different waste materials.

   •   Waste remains onsite (this may or may
       not be an advantage,  depending  on site-
       specific  circumstances).

       Use  of a batch  process  will  trigger
       LDRs.

   •   There may be a significant increase in
       volume that should be considered.

   •   Difficulty may arise  in verifying suffi-
       cient mixing  and completion of the
       process.

   •    Stabilization may not be applicable to
       wastes  containing moderate  to  high
        concentrations  of organics.

   •    It  may be difficult  to control odors,
        VOCs or dust during processing..

    •    Wastes containing drums, construction
        debris, etc., may require some pretreat-
        ment.

    •    Long-term monitoring will be necessary
        to verify whether  contaminants  arc
        leaching to the groundwater.

    •    Evaluating the long  term effectiveness
        of stabilization should be  included in
        the 5-year review.
Data that should be  gathered for design  and
implementation of stabilization  include:

   •   Waste characterization (Inorganic  and
       organic hazardous constituents,  and a
       measure of the total organics present
       such  as total  organic carbon [TOC]).
       Treatability  studies  should also  be
       performed during the FS to evaluate if
       the waste is amenable to stabilization,
       particularly when organics are present.
       Treatability tests  will  need  to  be
       conducted during design to optimize the
       formulation of stabilization agents.

   •   Depth of waste to be stabilized  (Depth
       should be less than 12 feet for in situ
       stabilization.)

   •   Total bulk unit weight of material (Soils
       will    typically   be  between  80  to
        110 Ibs/ft3; liquids and sludges typically
       range between 63 to 80 Ibs/ft3.)

4.2.5 Innovative Treatment Technologies

4.2.5.1 Description of Technologies

The focus of this document has been on tradi-
tional, previously used, and proven remedial
technologies.     This  section  is  intended to
address some innovative treatment technologies
that may be appropriate for remedial actions at
municipal landfill sites. It is important that the
evaluation of alternatives  for municipal landfill
sites not be  limited to conventional  technolo-
gies,  particularly in situations where  more
effective or less  costly  treatment can be
achieved by using innovative remedial technolo-
gies.

The following two technologies are presented as
innovative technologies that may be viable for
hot spots  at municipal landfill sites:

    •    Vapor  extraction
    •    In situ bioremediation

Other innovative technologies  may also be
viable and  should be considered if they are
appropriate  to  site characteristics.
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Soil Vapor  Extraction.  Soil vapor extraction
(SVE) is  an in situ process used to remove
VOCs from soil. This technology may be suit-
able for treating hot spots contaminated with
VOCs;  removal  of VOCs can  significantly
reduce the mobility of the other contaminants
present,  such  as  inorganics  or  semivolatile
organics.  SVE  consists  of a network of wells
with perforated well screens.  These wells are
packed with gravel and sealed at the top with
bentonite  to prevent short circuiting.    The
extraction wells are connected to the suction
side of a vacuum extraction  unit through a
surface  collection manifold.    The vacuum
extraction unit induces a flow of air through the
subsurface  into the extraction  wells.    The
vacuum not  only draws vapors  from the unsatu-
rated zone, but it also decreases the pressure in
soil voids, thereby causing the release of addi-
tional volatile organic  compounds  VOCs
The extracted  gas flows  through the surface
collection manifold and is either vented to the
atmosphere,  connected to a vapor-phase carbon
adsorption system, or flaredj depending on the
nature  and extent of  VOC  contamination.
Although  SVE is considered to  be an innovative
technology, many full-scale applications have
already  been  installed  and are currently
operating  or have already achieved performance
objectives.

Standard  procedures  that exist for installing
landfill gas recovery wells  in municipal landfills
should be applied to the installation of SVE
wells. The presence of landfill  gas in municipal
landfills requires that special health and safety
precautions be taken. The presence of landfill
gas may  also require  modified VOC control
systems. SVE can be "shortcircuited" by debris
and noncontinuous lifts  of material.   More
extraction wells  installed closer together are
necessary to ensure sufficient treatment.  One
or more wells in each lift may be necessary.

SVE treatment may be  particularly cost-effec-
tive for municipal landfills that will require
landfill gas  control,   Once SVE treatment is
completed,  the wells can  be used to collect or
vent landfill gas (see Section 4.4)..

In Situ Bioremediation. In situ biodegradation
is the process of enhancing microbial action to
remediate subsurface contaminants that  are
adsorbed to soil particles or dissolved in the
water phase. This technology is designed to
biodegrade  chlorinated  and non-chlorinated
organic contaminants  by employing  aerobic
bacteria  that use  the  contaminants  as their
carbon source.    This technology  could  be
applied to remediate  contaminated soil  and
groundwater without excavating overlying soils.
The technology uses special strains of cultured
bacteria and naturally occurring microorganisms
to achieve biodegradation.  The end result is
carbon dioxide, water, and bacterial biomass.

The most common in  situ biodegradation
method couples the stimulation of the  activity
of native microorganisms through oxygen and
inorganic nutrient  addition with the more con-
ventional   "groundwater pump  and  treat"
approach. This approach is generally the most
demonstrated and most appropriate application
of in situ biodegradation.

Conventional  pump and treat  cleanup is  a
passive approach that largely relies on the parti-
tioning of adsorbed contaminants into the water
phase.    This partitioning will be the rate
limiting step in the removal process, potentially
requiring  an extended  period of  time  to
completely remove the adsorbed contaminant
from  the  soil. In  situ  biodegradation (i.e., by
adding nutrients  to  groundwater) provides a
more  direct attack  on the adsorbed contaminant
phase.    This direct attack may significantly
reduce the  amount of time required  for the
remediation  of the  adsorbed  contaminants.
Simulating  subsurface microbial activity can
also increase the rate at which contaminants are
flushed from the subsurface in a pump and treat
system.

4.2.6  References

Some of the more  common references on reme-
dial technologies for soils/landfill contents are
listed  below.

Containment:

Ghassemi, M. Assessment of Technology for Cons
tructing   and Installing  Cover  and  Bottom
Liner Systems for  Hazardous Waste Facilities:
 Vol. I. Ghassemi  EPA  Contract  No.  68-02-
                                              4-19

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3174. U.S. Environmental Protection Agency.
May 1983.

Kmet, P., K.J. Quinn, and C. Slavik. Analysis of
Design Parameters Afflecting the .Collection Effli-
ciency of Clay Lined Landfills.  University  of
Wisconsin. September 1981.

Lutton, R.J. et al. Design and Construction of
Covers for Solid Wrote Landfill.  600-2-79-165.
U.S. Environmental Protection Agency. August
 1979.

Lutton, R.J. Evaluating Cover Systems for Solid
and Hazardous Waste. S W867.  U.S. Environ-
mental Protection Agency.  1982.

Morrison, W.R. and L. R. Simmons.  Chemical
and Vegelotive Stabilization of Soil: Laboratory
and Field Investigations of New Materials and
Methods for Soil Stabilization and Erosion
Control. Bureau  of Reclamation  Report No.
7613. U.S. Bureau of Reclamation. 1977.

U.S. Environmental Protection Agency. RCRA
Guidance  Document Landfill Design, Liner
Systems and Final Cover. (Draft). July  1982.

U.S. Environmental Protection Agency. Lining
of Waste Impoundment and Disposal Facilities.
SW870. 1983.
Determine Required Liner Thickness. EPA1530-
SW-84-001.

U.S Environmental Protection Agency. Techni-
cal Guidance Document:   Final Covers on
Hazardous   Waste Landfills  and  Surface
Impoundments, EPA/530-S-W-89-047. July 1989.

Warner, R.C, et al. Demonstrotion and Evalua-
tion of the Hydrologic Effectiveness of a Three
Layer Landfill Surface Cover Under Stable and
Subsidence  Conditions.   Phase I, Final Project
Report.     U.S.  Environmental Protection
Agency.

Removal/Disposal:

U.S. Army.   Dewatering and Groundwater
Control for Deep Excavations, Technical Manual
No. 5-818-5. Prepared by the Army Engineers
Waterways  Experiment Station.  1971.

U.S.  Environmental  Protection   Agency.
Handbook, of Remedial Action, of Waste Dispcsal
Sites (Revised). EPA1625/6-85/006.  October
 1985.

U.S. Environmental Protection Agency. Tech-
nology Briefs, Data Requirements for Selecting
Remedial Action Technology. EPA/600/2-87001.
January  1987.
 U.S.  Environmental  Protection   Agency.
 Handbook of Remedial Action of Waste Disposal
 Sites. (Revised).   EPA 1625/6-85/006. October
 1985.

 U.S. Environmental Protection Agency.  A
 Compendium of Technologies Used in the Treat-
 ment of Hazardous Wastes. EPA/625/8-87/014.
 September  1987.

 U.S. Environmental  Protection Agency. Final
 Covers on Hazardous  Waste  Landfills  and
 Surface Impoundments.  EPA/530-SW-89-047.
 July 1989.

 U.S. Environmental Protection Agency. Covers
for  Uncontrolled Hazardous   Waste Sites.
 EPAf540/2085-002.

 U.S. Environmental Protection Agency. Proce-
 dures for Modeling Flow  Through Clay Liners to
Soil Treatment:

U.S.  Environmental  Protection  Agency.
Handbook of Remedial Action of Waste Disposal
Sites  (Revised).   EPA/625/6-85/006. October
 1985.

U.S. Environmental Protection Agency. Systems to
Accelerate  In-Situ  Stabilization  of  Waste
Deposits. EPA/540/2-86/002. September  1986.

U.S. Environmental Protection Agency. Tech-
nology Briefs, Data Requirements for Selecting
Remedial Action Technology. EPA/600/2-87/001.
January  1987.

Innovative Remedial Technologies:

Michaels, P.A., and M.K. Stinson. Technology
Evaluation Report, Vacuum Extaction System.
                                             4-20

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Groveland, Massachusetts.
Engineering Lab., ORD.
EA68-03-3255. 1989.
Risk  Reduction
U.S. Environmental Protection Agency. Hand-
book of Remedial Action at Wrote Disposal Sites
(Revised). EPA/625/6-85/006.  October 1985.

U.S. Environmental Protection Agency.  Tech-
nology Briefs: Data Requirements for Selecting
Remedial Action Technology. EPA/600/2-87/001.
January 1987.

U.S. Environmental Protection Agency.  Tech-
nology Screening  Guide for Treatment of
CERCLA Soils and Sludges. EPA/540/2-88/004.
September 1988.

U.S. Environmental Protection Agency.  Terra
Vac In Situ Vacuum Extraction System, Applica-
tions Analysis Report. EPA/540/A5-89/003. July
1989.

U.S.  Environmental Protection Agency. The
Superfund Innovative  Technology Evaluation
Program:    Technology Profiles.     EPA/540/
5-89/013. November 1989.

U.S.   Environmental  Protection  Agency.
Handbook on In Situ Treatment of Hazardous
Waste-Contaminated Soils.  EPA/540/2-90/002.
January 1990.

U.S. Environmental Protection Agency.  Inter-
national Wrote Technologies/Geo Con In Situ
Stabilization/Solidiflcation,  Applications Analysis
Report. EPA/540/A5-89/004, August 1990.

U.S. Environmental Protection Agency. Ecperi.-
ence in Incineration Applicable to Superfund Site
Remediation.  EPA/625/9-88/008.

U.S. Environmental Protection Agency. High
Temperature Treatment for  CERCLA  Waste:
Evaluation  of Onsite  and  Offsite  Systems.
EPA/540/4-89/006.

U.S.   Environmental  Protection   Agency.
Stabilization/Solidification of CERCLA  and
RCRA  Wastes. EPA/625/6-89/022.
U.S. Environmental Protection Agency. State of
Technology Review:    Soil Vapor  Extraction
Systems  EPA/600/2-89/024.
                                    4.3  Leachate

                       4.3.1 Collection of Leachate

                       Leachate from landfills is a product of natural
                       biodegradation, infiltration,  and groundwater
                       migrating through the waste. Landfill leachate
                       is typically high in biochemical oxygen demand
                       (BOD),  chemical oxygen demand (COD), and
                       heavy metals. The function of a leachate collec-
                       tion system  is  to minimize or eliminate, the
                       migration of leachate away from the solid waste
                       unit. This system is typically  used to control
                       seepage  along the sideslopes of a landfill and to
                       prevent  discharges to surface and groundwater
                       systems. Leachate collection systems commonly
                       used are subsurface drains and vertical extrac-
                       tion wells.

                       4.3.1.1 Subsurface Drains

                       Subsurface  drains  consist of underground,
                       gravel-filled trenches generally equipped with
                       tile or perforated pipe  for greater hydraulic
                       efficiency.    They are used  to intercept and
                       channel leachate to a sump, wet well, or appro-
                       priate surface discharge  before it can infiltrate
                       to the main aquifer system.   Drains, usually
                       installed at the edge of the waste fill, can also
                       be used to collect contaminated groundwater
                       and transport it to a central area for treatment
                       or proper disposal. Typically, subsurface  drains
                       are installed at the perimeter  of the,  landfill,
                       although in landfills where the thickness of fill
                       is less than  approximately 15 feet, it may  be
                       appropriate to consider  installation within the
                       landfill. Depth of waste  as  well  as  hazards
                       associated with excavating landfill material
                       usually prevents installation of drains within the
                       landfill.

                       4.3.1.2 Vertical Extraction Wells

                       Vertical extraction wells  are wells drilled in the
                       waste and screened in a highly  permeable water
                       bearing  zone. This zone  may be perched above
                       the surrounding water table or may be  in the
                       groundwater. The intent is  to collect highly
                                             4-21

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contaminated leachate or leachate/groundwater
mix. The wells, which typically run to the base
of the landfill, are fitted with a pump to extract
leachate and create a negative pressure zone to
promote leachate flow towards  the  wells.  It
should be noted that without the proper pre-
cautions, placing wells into the landfill contents
may create  health and safety risks. Perimeter
wells may  also  be  installed  at the landfill
boundary as a  source  control  measure  to
control  offsite migration of leachate  and con-
taminated groundwater.   Maintenance of the
wells is  essential because the permeable layer  is
prone to fouling due to biological growth or
precipitation of metal hydroxides.

Some implementation and O&M considerations
concerning leachate collection  include the
following:

   •   A properly designed leachate collection
       system should provide a reduction in
       the potential for migration of leachate
       to surface water and groundwater.

   •   Distribution  and  discontinuities  of
       liquids within the landfill will  affect the
       placement  and  number of wells
       required.

   •   Hydraulic head will vary throughout the
       landfill.

   •   Extraction systems will require ongoing
       maintenance to maintain effectiveness.

   •   Drilling conditions must be considered.

   •   Creating a  low-pressure  zone  may
       attract water in the landfill.

   •   Leachate collection is typically  cost-
       effective  compared to  recovering dis-
       persed contaminants (that is, extraction
        and treatment of offsite  contaminated
       groundwater plume).

   •   A leachate collection system may result
        in an increase in landfill settlement as a
       result of leachate extraction.

   •   An effective collection system generally
       will require a thorough characterization
       of the hydrogeology of the site before
       design or installation of the system.

   •   Consideration should be given to possi-
       ble health and safety risks, difficulty in
       drilling and  installation conditions in
       landfill materials,  and resultant high
       costs (drilling within the landfill may
       require at least  Level B health  and
       safety  protection).

The primary data needed for designing a leach-
ate  collection system include:

   •   Topographic characteristics of the site
       (for  example, slopes, drainage divides)

   •   Site  soil characteristics (for example,
       permeability, grain size  distribution)

   •  Climatological  characteristics  (for
       example, precipitation,  temperature)

   •  Hydrogeologic  characteristics  (for
       example, depth to groundwater, ground-
       water flow direction and velocity)

   •   Waste  characteristics  (for  example,
       composition, moisture content,  age)

4.3.2  Treatment of Leachate

Either onsite  or offsite treatment of  leachate
may be feasible options for municipal landfill
sites.  Leachate  from municipal  landfill sites
may have high concentrations of organic  matter
(measured in terms of BOD and COD), and
high  concentrations of  inorganic. Leachate
quality varies from site  to site, and will also
vary over time.  For example, BOD concentra-
tions  may  decrease over time.   Once the
constituents and associated concentrations are
known for the leachate,  appropriate treatment
technologies can be selected.

Typical concentration ranges for some contami-
nants that leach from municipal  landfills are
listed in Table 3-2 of this document. The large
ranges may  be due in part to analysis of leach-
ate that has  been  diluted  by  groundwater.
Additional information on leachate composition
and contaminant concentrations in leachate can
be found in Characterization ofMWC Ashes and
                                              4-22

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Leachates from MSW Landfills, Monofills and
Co-Disposal Sites (EPA,  1987f).

Leachate generally is treated by conventional
means such as biological treatment, physical
treatment, or chemical treatment. The chemical
characteristics of the leachate must be deter-
mined in order to design an onsite treatment
system. This chemical analysis includes:

   •    Quantifying the constituents  in the
        leachate (organies and inorganic), espe-
        cially the compounds to be removed

   •    Determining the variability of leachate
        characteristics

   •    Measuring BOD, COD, and TOC (gross
        indicators of organic, loading for biolog-
        ical treatment  and granular activated
        carbon [GAC])

   »    Measuring  other conventional
        parameters  for leachate such as total
        dissolved    solids    (TDS),   chlorine,
        alkalinity,  nitrate,  nitrite,  ammonia,
        total phosphorous, and sulfide

   •    Measuring pH (effects the efficiency of
        biological    treatment    and   reagent
        requirements of metals precipitation)

   •    Determining influent flow to the treat-
        ment systems (and anticipated variabili-
        ty  in  flow  such  as  from seasonal
        variation in leachate production)

   •    Measuring  total suspended solids (TSS)
        in Ihe leachate (high solids content [for
        example, >50 ppm] may require pre-
        treatment before carbon adsorption)

   •    Measuring oil and grease in the leach-
        ate (high concentrations [for example,
        >10 ppm], may require pretreatment)

   •    Conducting   treatability  during
        predesign,  as required, to optimize the
        treatment system
4.3.2.1 Onsite Treatment

The  degree of treatment depends to a great
extent on  the  strength  of the  leachate  and
whether the effluent is to be discharged directly
to surface water or to a publicly owned treat-
ment works (POTW). The most common tech-
nologies used at municipal landfill sites to treat
leachate  include  biological treatment  for
removal  of biodegradable organies,  physical
treatment such air stripping and carbon adsorp-
tion for VOC removal, and chemical treatment,
such  as  metals precipitation  for  removal of
inorganic.     Treated  leachate  could  be
discharged onsite depending on the extent of
treatment.   Onsite  discharge can be  done by
groundwater aquifer reinjecton or by discharge
to surface water.  Groundwater aquifer reinjec-
tion depends on state groundwater standards in
the area where the site is located. Discharge to
surface water will have to comply to NPDES
Permit requirements.

Chemical Treatment. In chemical treatment,
hazardous constituents are altered by chemical
reactions.  During the  process, hazardous
compounds may  be destroyed or  altered; the
resultant products may  still be hazardous but
transformed  to a more  convenient form for
further processing. The most common  chemical
treatment for landfill leachate is precipitaticm of
heavy metals. Precipitation will remove soluble
heavy metals from leachate by forming  insoluble
metal  hydroxides, sulfides,  or carbonates.
Heavy metals typically removed by precipitation
include arsenic, cadmium, chromium, copper,
lead, mercury, nickel,  and zinc.  Metals are
often removed to either meet NPDES permit
limits  or as pretreatment  to reduce metals
toxicity for biological  treatment.    Chemical
precipitation involves alteration  of the ionic
equilibrium to  convert  soluble metal ions to
insoluble  precipitates.   These precipitates are
then removed by solids separation processes
such as sedimentation and filtration.

Precipitation reactions  for leachate treatment
purposes are usually induced by one or more of
the following steps:
                                             4-23

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   •   Add a substance that reacts  directly
       with the compound in solution to form
       a  less  soluble compound.

   •   Add a substance that shifts the volubil-
       ity equilibrium to a point that no longer
       favors the continued volubility of the
       compound. For instance, pH affects the
       equilibrium   concentration of  ionic
       species. This is particularly true when
       the respective solid phase is  a hydroxide
       or carbonate compound.

   •   Change the temperature of a saturated
       or nearly saturated solution to decrease
       volubility.

Most precipitation reactions are carried out by
adding  appropriate   chemicals  and  mixing.
Common additives include lime, soda  ash, and
caustic. The main liquid stream's pH may need
to be  adjusted  after  removal of the  solid
precipitates.

Biological Treatment.   Biological means are
used in treating leachate contaminated primarily
by biodegradable organic compounds.   Bio-
logical treatment is especially effective in treat-
ing landfill leachate  that typically has high
levels of BOD and COD (e.g., 0.-750,000 mg/1).

In biological treatment, wastewater  is contacted
by a culture  of microorganisms either suspended
in the wastewater  or attached  to  a  solid
medium. The organic compounds in the waste-
water are metabolized by the organisms as a
food  and energy  source. Organics  are  thus
removed from solution and biomass and meta-
bolic waste  gases such as carbon dioxide and
methane  are produced.   Biological treatment
systems  are configured as  fixed   growth,
suspended growth, or a combination  of both.
They can be  designed to treat hundreds of
millions of gallons per day (MOD) or as little
as 1 gallon per minute (0.0014 MOD).

Biologial treatment processes can be classified
as aerobic or  anaerobic.   Aerobic treatment
systems require oxygen, either in air or in pure
form, to meet the metabolic needs of the micro-
organisms. Aerobic treatment systems are the
most frequently  used form  of biological treat-
ment. These systems consist of a reactor, where
the waste stream is brought in contact with a
culture of organisms, and usually a clarifier or
other  solids-separation device where organisms
suspended   in  solution  are  removed by
sedimentation.

Anaerobic  treatment systems are  used  most
often  for treating high-strength wastes. These
systems are often followed by anaerobic treat-
ment  system for additional organics removal.
Compared to aerobic systems, anaerobic treat-
ment  systems produce less biomass per pound
of BOD removed. In addition, anaerobic treat-
ment produces methane of sufficiently high con-
centration to be used in some cases for energy
recovery. Anaerobic digesters are also frequent-
ly used in the treatment of sludge produced in
aerobic treatment. In this process, the sludge is
reduced in volume and methane gas  is produced
as a by-product.

Physical  Treatment.  Two  types of physical
treatment technologies most commonly used to
treat  leachate  are air stripping and granular
activated  carbon (GAC)  for  the removal of
organics.    Other conventional physical treat-
ment  technologies such as sedimentation and
filtration may also have to be incorporated as
part of the overall treatment system.

Activated  carbon  is usually applied  after
conventional treatment as a polishing operation
for removal of trace concentrations of residual
organics and/or heavy metals. It is also used for
the reduction  of COD   and BOD, for the
removal of toxic or refractory organics, and for
the removal and recovery of certain organics
and inorganic from aqueous waste. Applica-
tions  involving organic solutes are  most effec-
tive when  the solutes have  a high molecular
weight, low water volubility, low polarity,  and a
low degree of ionization.     Many organic
compounds such as phenolics, aromatics, and
chlorinated hydrocarbons  are readily adsorbed
on the surface of activated carbon. In addition,
certain heavy metals such as  cadmium, chromi-
um, copper, nickel, lead,  and zinc can be
removed from water with carbon, although this
technology is  not widely  used  for  metals
removal.

Most organic and some inorganic solutes are
absorbed as the leachate stream is  passed
                                             4-24

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through the carbon, usually in packed beds.
When the carbon reaches its maximum capacity
for adsorption, or when effluent concentrations
are unacceptable, the spent carbon is replaced
by fresh carbon.   The carbon may be regener-
ated offsite whereby the adsorbed contaminants
are incinerated, or the carbon may be disposed
of in  a RCRA landfill if regeneration is not
cost-effective.

Contacting methods  for granular carbon include
adsorbers  in  parallel,  adsorbers in  series,
moving-bed,   and  up flow-expanded  beds.
Carbon loadings can approach 1 pound of COD
removal per pound  of carbon. The concentra-
tion of COD in the influent can typically be as
high as 1 to 5 percent. Suspended solids in the
influent should generally be less than 50 ppm to
minimize  backwash requirements.    Actual
carbon usage rates are determined during pilot
testing:

Air stripping is used in municipal landfill appli-
cations for the removal of VOCs from leachate
or groundwater. When leachate containing a
volatile compound  is brought to equilibrium
conditions with air, some portion of the volatile
compound  transfers from the water to the air.
The resulting concentrations  of the volatile
compound  in  the air and  in the water are a
function of the beginning concentration in the
water, the  temperature, the pressure, and the
degree of volatility of the compound. The vola-
tility  of the compound-that is, its tendency to
leave the water and enter the air-is expressed
by Henry's law constant for the particular
compound. The Henry's  law constant  is the
ratio  of the concentration of the compound in
the air to its concentration in water at equilibri-
um conditions.

Leachate   contaminated    with   a  volatile
compound is fed into the top of a tower while a
large air stream is forced into  the bottom. The
lower is usually filled with a packing medium
that provides  a  large surface  area for contact
between the air  and leachate. The air exits the
top of the  tower with the  volatile compound.
The leachate is  collected  at the bottom of the
tower and is either  pumped to another process
area  for further treatment or discharged.  It
should be  noted that leachate may foul the
packing medium and reduce the effectivenss of
air stripping.

If sufficiently low concentrations are involved,
the air can be discharged to the  atmosphere.
Otherwise, air pollution control devices such as
vapor-phase carbon may be needed. State air
pollution regulations must be followed for emis-
sion controls:

Computerized mathematical models arc avail-
able to estimate the  effectiveness of air strip-
ping for removing many organic  compounds.
However, critical operating parameters should
be  determinde experimentally through  pilot
studies.

4.3.2.2 Offsite Treatment

Direct discharge to a POTW may be appropri-
ate for leachate streams containing concentra-
tions  of contaminants that are amenable to
treatment provided by the POTW. More often,
pretreatment may be required before discharge
to the POTW. Major considerations include
the constituents of the  leachate  and  their
concentrations, the type of treatment used by
the POTW, the remaining treatment capacity of
the POTW, the volume of leachate to be dis-
posed of,  and the  expected duration of the
discharge. A high rate of flow for an extended
time  may  require  a capital  expenditure to
increase the capacity of the treatment works.
Early contact with the  POTW during the
feasibility  study process  is  important to
determine the acceptability of the leachate for
treatment at the POTW.

Treatment to reduce  the concentrations of
organics and metals can be expected at most
POTWs. However,  the NPDES permit for the
POTW may have metals limitations that will
preclude the treatment of  leachate.    The
removal efficiency depends  on the type and
concentration of contaminants.   Removal of
organics and metals will be primarily from strip-
ping in aeration basins, adsorption onto biologi-
cal floe, and biological degradation.   Fate  of
Priority Pollutants in Publicly Owned Treatment
 Works (U.S. EPA, 1982c) is a good source for
information on treatability and on the applica-
bility of different treatments for a  particular
waste stream. The need for treatability testing
                                             4-25

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or pretreatment of the waste stream must be
determined on the basis of the probable effect
of the contaminats on the POTW.
CERCLA
4.2.3.3).
                                       waste  to  a POTW  (see  Section
Treatment  processes
POTWs include:
typically employed at
   •   Aerobic processes-Including rotating
       biological contractors, oxidation ditches,
       activated sludge reactors, and tricking
       filters

   •   Anaerobic processes-Including anaero-
       bic contact reactors, anaerobic  filters,
       fluidized bed systems, and various fixed-
       film systems

   •   Physical/chemical  processes-Including
       dissolved-gas flotation, chemical coagu-
       lation,  sedimentation, and filtration

Special considerations for discharge to a POTW
include the proximity  of the  nearest POTW
sanitary sewer sufficient to handle the flow,
pretreatment requirements, and the  potential
health risk to POTW  employees  of treating
wastes from CERCLA  sites. Construction of
gravity main or force  mains to transport the
discharge to the POTW collection system may
be cost effective compared to onsite treatment.
Typically it is cost effective to transport only
low flow  rates (for example, less than 2 gpm)
via  trucks  to  the  PO.TW.

If the leachate is to be trucked offsite for treat-
ment, and it is classified as a RCRA hazardous
waste,  a  RCRA  Part  B  permit would  be
required by the POTW to accept the leachate.
In this situation, another off site option would
be to treat the leachate  at a RCRA treatment,
storage, and disposal facility (TSDF). There are
several RCRA TSDF in various parts of the
country that treat leachate.  If the leachate is
discharged to the sewer system (that is, piped to
the POTW) the POTW is  exempt from RCRA
as outlined in 40 CFR 261A.4(a)(l)(ii)

A-discharge to a POTW is generally considered
on offsite activity,  even if CERCLA waste is
discharged to a sewer located onsite. Therefore,
the offsite policy  and proposed  regulations
would  generaly  apply  to a discharge  of
Some implementation and O&M considerations
concerning   offsite  treatment   include  the
following:

   •   The possible elimination of potentially
       strict limits  for discharging to surface
       water or groundwater

   9   The acceptability at sites with sensitive
       public  relations  issues

   •   The  limited capacity of a POTW to
       handle the leachate  volume  and
       contaminant  loading

   •   The  possible tendency of the POTW
       permitting authority  to  set  stringent
       discharge  standards because there is no
       categorical  standard  for  CERCLA
       operations  and because of public fear or
       mistrust  of   "hazardous  waste"
       (Frequently, discussions on the accept-
       ability of  the discharge and discharge
       standards  will  extend well  into  the
       predesign  and  design phases  of
       Supcrfund sites.)

       The liability of a discharger if the dis-
       charge causes the POTW lo violate its
       NPDES permit,  or if sludge  from the
       POTW fails toxicity  criteria or other
       standards  (Some treatability testing at
       the POTW  may be required  to deter-
       mine whether pass-through of leachate
       contaminants is likely.)

    •   Problems  at sites with leachate of vari-
       able  quality

    •   User fees  usually imposed by POTWS
       receiving  discharge

    •   The partial removal of many organics by
       adsorption on the biomass (Land appli-
       cation of the sludge by the POTW may
       reintroduce  contaminants to the envi-
       ronment  and should  evaluated.

    •   Need to contact the  POTW  to deter-
       mine if overflows or bypasses occur
                                             4-26

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       during wet weather in the sewer to be
       used (If so, then precautions  such as
       temporary storage of leachate during
       wet weather may be necessary.)

   •   Classification as  a  RCRA waste of
       leachate that is trucked offsite (RCRA
       waste will  have  to  be  treated  at a
       RCRA TSDF instead of at a POTW.)

Data on  leachate characteristics, which  may
include parameters such as COD, BOD, pH,
TSS, TOC, IDS, as well as hazardous constitu-
ents such as  inorganic  (metals,  cyanide),
volatile organics, and semivolatile organics will
be required by the POTW to  assess whether it
can accept  the  waste  stream.    Treatability
testing will be necessary to evaluate the effects
of the leachate on the POTW  system as well as
on removal capabilities.

4.3.3 References

Additional references on remedial technologies
for leachate are listed below.

Collection:

U.S. Environmental Protection Agency. RCRA
Guidance Document Landfill Design,  Liner
Systems and Final Cover. (Draft). July 1982.

U.S. Environmental Protection Agency. Lining
of Waste  Impoundment and Disposal Facilities.
SW870. 1983.

U.S. Environmental Protection Agency. Hand-
book of Remedial Action of Waste Dioposal Sites
(Revised). EPA/625/6-85/006. October 1985.

U.S.   Environmental  Protection   Agency.
Leachate Plume Mangement.      EPA/540/
2-85/004. November 1985.

U.S.   Environmental  Protection   Agency.
Technology  Briefs,   Data Requirements for
Selecting  Remedial  Action   Technology.
EPA/600/2-87/001. January 1987.

U.S.   Environmental  Protection   Agency.
Guidance on Remedial Actions for Contaminated
Groundwater at Superfund Sites   EPA/540/6-
88/003. December 1988.
Treatment:

Cheremisinoff, P. N., and Ellerbush, F. Carbon
Adsorption Handbook Ann Arbor Science, Ann
Arbor, MI. 1980.

Clark, Viessman,  and Hammer. Waler Supply
and Pollution Control. lEP-Dun-Donnell. New
York.  1977.

Metcalf & Eddy, Inc., revised by Tchobanoglous.
Wastewater Engineering:    Treatment, Disposal,
Reuse. 2nd Ed. McGraw-Hill. New York, New
York.  1979.

Treybal, R. Moss Transfer Operations.  3rd Ed.
McGraw-Hill.  1983.

U.S. Environmental Protection Agency. Fate of
Priority Pollutants in Publicly Owned Treatment
Works. EPA/440/1-82/303.  1982.

U.S. Environmental Protection Agency. Permit
Guidance Manual on Hazardous  Waste Land
Treatment Demonstrations,  Draft.. EPA 530-SW-
84-015. December  1984.

U.S.   Environmental  Protection   Agency.
Handbook of Remedial Action of Wrote Disposal
Sites  (Revised). EPA/625/6-85/006. October
 1985.

U.S. Environmental Protection Agency. Guide
for Identifying Cleanup Alternatives at Hazardous
 Waste  Sites and  Spills    EPA/600/3-83/063.
December 1985.

U.S.   Environmental   Protection  Agency.
 Technology Briefs,   Data Requirements for
Selecting    Remedial  Action    Technology.
EPA/600/2-87/001. January 1987.

U.S.   Environmental  Protection  Agency.
 Characterizaiton ofMWC Ashes and Leachates
from  MSW Landfills and Co-Disposal Sites.
EPA/530/SW-87/028A.  October  1987.

U.S.  Environmental  Protection Agency.
 Guidance on Remedial Actions for Contaminated
 Groundwater at Superfund Sites.    EPA/540/
 6-88/003. December  1988.
                                            4-27

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U.S.  Environmental Protection Agency.
CERCLA Site Discharges  to POTWs. EPA/540/
6-90/005. August 1990.
           4.4  Landfill  Gas

4.4.1 Collection of Landfill Gas

Landfill gas (LEG) is produced naturally when
organic material from  a landfill decomposes.
LEG  collection should be considered in the
following  situations:

   •   When homes and buildings are (or are
       planned to be) adjacent or close to the
       landfill

   •   When wastes  have  a high  organic
       content

   •   When future use of the site may involve
       allowing access  to  the public (for
       example, as a park)

   •   When emissions pose an unacceptable
       health risk

   •   When the landfill produces excessive
       odors

   •   When gas pressure building under the
       cap can damage it and/or curb vegeta-
       tive growth on the cap

   •   When state ARARs require treatment
       of the LEG

A proper  landfill cover decreases odors and
vertical migration of gas. However, it  increases
lateral gas migration and with it the potential of
entrapping explosive methane gas in nearby
structures. The lateral  movement of LEG can
be intercepted by either permeable or imperme-
able systems. Permeable interception systems
capture gas that is moving laterally  and provide
conduits for the gas to escape to the surface.
These systems typically consist of horizontal
trenches and/or pipes and vertical wells. Imper-
meable interception systems block the flow of
the gas and also provide conduits to the surface,
Typical components of impermeable systems are
barriers made  of clays and synthetic liners.
Most often they arc used in conjunction with
trenches.

Design  considerations  for 'LEG  collection
include:

   •   Volume and type of wastes present

   •   Depth of fill

   •   Subsurface geology of the site

   •   Field  measurements

           Waste constituents
           LEG  concentrations
           Moisture content of waste
           Preferential flow paths
           Soil permeabilities

LEG collection systems  are divided into two
main groups:     passive  systems and  active
systems.

4.4.1.1 Passive  Systems

Passive LEG control  systems  alter subsurface
gas flow paths without using mechanical compo-
nents. Generally, they direct subsurface flow to
points of controlled release through the  use of
high-permeability systems Flow paths to out-
side areas are blocked through the use of low-
permeability   barriers.      High-permeability
systems usually consist  of trenches  or  wells
excavated at the  boundary of the landfill and
backfilled  with   permeable  material  (for
example, gravel, crushed storm, etc.) to create a
preferential  gas flow path.  Low-permeability
barriers typically consist of clay-lined or synthe-
tic-lined (HDPE, PVC, Hypalon, etc.) trenches
or walls.   Passive  systems  are  not used to
recover landfill gas, instead their only use is to
control the  release  of landfill gas to  the
atmosphere. Typical passive  systems are pipe
vents and trench vents.

Pipe  Vents.  Pipe vents are used for venting
LEG at points where  it is  collecting and
building up pressure.  They are often used with
flares that burn the gas at the  point of release.
Pipe vents typically are simple, inexpensive, and
effective at reducing localized LFG pressure.
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However, some considerations concerning pipe
vents include the following:

   •   They potentially will have a small zone
       of  influence   (less  than  5  feet  in
       compacted refuse).

   •   They may result in increased odor prob-
       lems  (due to  LFG  release  to the
       atmosphere).

   •   There  may be  a potential danger  of
       explosion at the point of release, which
       should be considered and evaluated.

Trench Vents. Trench vents usually consist of
gravel trenches  surrounding the  waste site.
They form  a path of least resistance through
which  gases migrate upward to the atmosphere.
A barrier system can be added to the outside of
the  trench  to increase its  effectiveness  in
controlling LFG.

Trench vents typically are more effective than
pipe vents for containment and control. They
require little maintenance, and they are relative-
ly inexpensive.   If there  are houses  nearby,
trench vents, possibly in conjunction with pipe
vents,  should be considered to minimize the
potential for  lateral migration  of LFG. Gas
migrating laterally into basements can  create
toxic or  explosive conditions. Some consider-
ations concerning trench vents  include the
following:

   •   Runoff can  infiltrate and clog  open
       vents.

   •   Gases may migrate under  the trench if
       it is not  constructed to  a  sufficient
       depth  or  keyed  into  an  impervious
       layer.

   •   There is potential for failure  of the
       barrier system below a  15- to 20-foot
       depth.

   •   Odor problems are possible.

The  most important data needed for designing a
passive gas control system are:
   •   Topographic characteristics of the site
       (for example, contour elevation map)

   «   Soil characteristics (for example, perme-
       ability,   grain-size  distribution,  soil
       content)

   •   Geologic characteristics (for example,
       type of subsurface strata, pH, tempera-
       ture, depth of bedrock)

   •   Climatologic    characteristics   (for
       example,  precipitation, temperature).

   •   Hydrogeologic  characteristics  (for
       example, depth to groundwater inside
       and outside the landfill)

   •   Waste characteristics  (for  example,
       composition,   biodegradables  and
       organics  content, moisture  content)

4.4.1.2 Active Systems

Active systems to control LFG restrict subsur-
face migration  of gases.    The systems use
mechanical  means to  alter  pressure gradients
and redirect subsurface gas flow. Major system
components  generally include gas extraction
wells, gas collection headers,  vacuum blowers or
compressors, and gas treatment or use systems.
Active systems  are typically used in landfills
where severe odor problems  exist, they are also
used  to  prevent LFG from  migrating to and
endangering  nearby structures. LFG recovery
and sale or use  as a source  of energy are only
possible with active systems.

Gas extraction wells are drilled to  the seasonal
low groundwater level or to the  base of the
landfill.  Typically, a perforated pipe is set in
the well with permeable material  surrounding
the pipe. At the top of the well, the pipe is
nonperforated  and  the surrounding  area  is
sealed with concrete or clay. A gas collection
header is connected to the top of the pipe and
to  several other  extraction wells spaced  at
regular intervals. Vacuum blowers or compres-
sors,  connected to  the headers,  are  used  to
create, a negative pressure area, which causes
gases to be drawn up from the extraction wells.
Then gases arc  treated and  either released to
                                              4-29

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the atmosphere or recovered and used to gener-
ate energy.

The most common active system is an onsite
extraction well system. It consists of a series of
extraction wells in the landfill, typically 100 to
300 feet apart. The applied extraction vacuum
withdraws  LFG in both  the. horizontal  and
vertical  directions.  Vacuum blowers  extract  the
LFG  from the  wells, and push the collected
LFG through a free vent or waste-gas burner.
Enclosed flares have proven effective in destroy-
ing the combustible components of the  LFG
and thereby eliminating odor problems.

Some implementation and O&M  considerations
concerning active  gas control systems include
the following:

   •   Active gas control systems can provide
       effective LFG control with an area of
       influence larger  than that  of passive
       systems (depending on the design).

   •   Odors and reactive organic gas emis-
       sions are reduced, as compared to pas-
       sive systems.

   •   There is potential for use of LFG.

   •   The expense,  is  greater compared to
       passive systems because of the compli-
       cated design and  mechanial equipment
       required.

    •   Regular  O&M is required for optimal
       results  (depends  on   the design  and
       volume  generated).     For example,
       collection systems may become clogged
       with biological growth or sediments.

    •    Condensate handling is required (possi-
       bly classified as  a RCRA hazardous
       waste).

    •    Modifications after  startup  may be
       necessary because of the variability of
        solid waste, and soils placed at the  site
        (affects gas production).

    •    Landfill settlement may cause collection
        piping to bend.
The typical data needed for designing an active
system include:

   •   Topographic characteristics of the site
       (for example, contour elevations map)

   •   Soil characteristics (for example, perme-
       ability,  moisture  content,  grain  size
       distribution)

   •   Geologic  characteristics (for example,
       type of subsurface strata, pH, tempera-
       ture, depth of bedrock)

   •   Hydrogeologic  characteristics  (for
       example,  depth  to  groundwater)

   •   Waste  characteristics  (for example,
       composition, moisture content, percent
       compaction)

   •   Depth, volume, and approximate settle-
       ment rate of wastes

4.4.2  Treatment of Landfill Gas

4.4.2.1 Thermal Treatment  (Enclosed Ground
Flares)

When treatment of LFG is necessary,  the most
common technology used at CERCLA munici-
pal landfill sites  is thermal  treatment using
enclosed ground  flares.  Treatment of landfill
gas may be necessary in situations where homes
or buildings are close to the landfill, when  final
use of the site includes allowing public access,
when the landfill produces excessive odors, or
when state or federal air standards are  violated.
Flares are a well-established technology and are
being used at many landfills worldwide.

Enclosed  ground  flare systems  consist  of a
refractory-lined flame enclosure (or stack)  with
a burner assembly at its base.  A pilot light is
installed  near the waste-gas burner head.
Combustion  air dampers are  installed at the
base  of the flare to control excess air. In the
operation of an enclosed ground flare system,
landfill gas is mixed with a supplemental fuel, if
required   to support  combustion,  and  fed
through  a vertical, open-ended  pipe.    Pilot
burners (usually at least  three) next to the end
of the pipe ignite the waste.
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Enclosed ground flares are used extensively for
operations involving landfill gas disposal. (They
can also be used to burn gases collected from a
soil vapor extraction operation.) Earlier opera-
tions with landfill gas flaring have consistently
used elevated open flares. Open flares are still
very common at non-CERCLA municipal land-
fill sites.  However, the enclosed flare is increas-
ingly popular and is, in some instances, being
considered   the Best Available  Control
Technology (BACT) for new installations. This
emerging technology is a result of the perceived
improvement  combustion  efficiency and in
control  of enclosed flares over  open flares.
Particularly at CERCLA sites, the presence of a
visible flame on open flares may  cause public
concern or may be considered a nuisance. Use
of open flares is still common in emergencies or
for when  the  quality and quantity of gas
fluctuates widely.

The most important limitation for flare opera-
tion is the quality of the gas. If the LEG is less
than 20 percent methane, then auxiliary fuel is
necessary. Auxiliary fuel is desirable if methane
concentration ranges from 20 to 30 percent. If
high operating  temperatures are desired,  addi-
tional  fuel may be  required in  any  case.
Auxiliary fuel will rapidly drive the operational
costs up, especially if inexpensive fuel is not
available  nearby.

Regulatory  guidance  for  flare  operation is
limited,  so  operating  conditions  are usually
guided by engineering judgment. The assumed
minimum limits for operations are 1,400°F and
1  second of residence time. Data for evaluating
destruction  efficency  are  somewhat limited.
The indications are that destruction efficiencies
should be  greater than  90 percent for  most
trace air-toxic  compounds, with  many flares
probably  realizing greater than  99 percent
destruction  efficiencies.

Caution should be used when predicting treat-
ment performance.  Destruction efficiency can
be highly variable, and predicting performance
for a specific  site may require pilot testing.
Most organic compounds should  be destroyed
effectively with adequate temperature and resi-
dence time; however, test data are limited. In
many cases, demonstrating high destruction
efficiency is difficult because  detection levels
cannot be  measured  precisely using  current
sampling  and  analytical  protocols. In  most
cases,  enclosed  flares consistently  achieve
greater than 98 percent in overall combustion
efficiency.    Operations usually can achieve
smokeless  combustion with no visible flame
outside the stack. Enclosed ground flares can
be built for virtually any flow of LEG from a
landfill site. However,  5,000 standard cubic feet
per minute of LEG  per  flare is  a practical
upper limit,  and lower flows may be  more
appropriate to allow for operational flexibility
and to reduce potential equipment problems.

The EPA Office of Air Quality, Planning, and
Standards is developing new source emission
guidelines and performance  standards  for
collection and treatment of landfill gas. The air
emission standards will apply to new municipal
solid waste landfills as well as to those facilities
that have  accepted waste since November 8,
1987, or that have capacity available for future
use. The proposed rule would require an active
landfill gas collection and control system for
solid waste landfills where emissions exceed
100 megagrams per year of nonmethane organic
compounds (NMOC). Control (i.e., treatment)
would  be achieved using flares.   Since  the
proposed rule is currently under development,
some changes may be made.  Also, judgment
should be used in  determining whether these
guidelines and standards are  relevant and
appropriate to a specific CERCLA municipal
landfill  site.  These standards and  guidelines
were developed for  municipal solid waste land-
fill sites as opposed to CERCLA  sites where
there is typically co-disposal of both municipal
solid waste and hazardous waste.

Some implementation  and  O&M considerations
concerning enclosed ground flares include the
following:

   •   Enclosed ground flares  should eliminate
       odors and air emissions.

   •   Generally, enclosed ground flares  are
       easy to implement and can be used for
       short-term as well  as long-term applica
       tions.

   •   There is no possibility for heat -recovery
                                             4-31

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   «   There is  a potential need for steam to
       control emissions.

   •   There are high noise levels.

   •   Costs of supplemental fuel and its avail-
       ability must be considered.

The data needed  for screening and predesign of
a  flaring  system  include:

   •   The  quantity standard cubic feet per
       minute) of LFG to be treated

   •   The  heat content of waste (Btu/cubic
       foot)

   •   Waste constituents, including methane
       content

Bench or pilot  testing is often  required to
determine destruction and removal efficiencies.

4.4.3 References

Additional references on remedial technologies
for LFG  are listed below:

Argonne National Laboratory. An  Annotated
Bibliography: Environmental Impacts  of Sanitary
Landfills and Associated Gas Recovey Systems.
ANL/CNSV-27.  February 1982,

Emcon  Associates-Ann Arbor  Science.
Methane Generation and Recovery fiom Landfills.
 1980.

Lutton, R.J. et al. Design and Construction of
Covers for Solid Waste Landfills. 600-2-79-165.
U.S. Environmental Protection  Agency.  August
 1979.

Noyes Data Corporation.  Landfill Methane
Recovey.    Energy Technology  Review #80.
 1983.

 Seebold,  James A.    Practical Flare Design.
Chemical Engineering.  December  1984.

U.S. Environmental Protection Agency. RCRA
 Guidance Document Landfill Design, Liner
Systems and Final Cover. (Draft). July 1982.
          4.5  Groundwater

4.5.1 Collection, Treatment, and Disposal

Collection and treatment of groundwater is a
common component of the overall remediation
of municipal landfill sites.  Typically, ground-
water is extracted at the perimeter of the land-
fill to manage offsite migration of leachate and
is extracted  downgradient  to  capture  the
contaminated groundwater  plume.   The two
types of groundwater collection  systems used
most often are extraction wells and subsurface
drains.
Subsurface drains (which are also often used for
leachate  collection)  consist  of underground,
gravel-filled trenches generally equipped with
tile or perforated  pipe for greater hydraulic
efficiency.   The  drains can be used to collect
contaminated groundwater and transport it to a
central area for  treatment or proper disposal.
Drains are typically used in geological units of
low permeability.

Extraction wells are used more frequently then
subsurface drains. Well diameter, flow  rate, and
spacing are determined based on  the desired
groundwater capture  zone  and the hydrogeo-
logic characteristics of the aquifer.

Contaminated groundwater is usually treated
and disposed of  along with leachate (see
Section 4.3.2). The  chemical parameters  that
are typically elevated in samples of contami-
nated groundwater  from municipal landfill sites
include BOD, COD, VOC,  TDS,  chloride,
nitrite,  nitrite, ammonia, total  phosphorous,
sulfides, and metals. As with leachate, treat-
ment of contaminated groundwater  (or pretreat-
ment in cases where discharge is to a POTW)
may involve conventional treatment systems
such as biological treatment (organic removal),
metals precipitation, and air stripping or GAC
for VOC  removal (polishing).

4.5.2 Containment

4.5.2.1 Vertical Barriers  (Slurry Walls)

Vertical barriers  may be a viable technology for
groundwater containment at municipal landfill
sites. Their use warrants some consideration
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since they may improve the overall effectiveness
of a containment system. Extraction wells are
often  used with  slurry walls to increase the
effectiveness of the slurry wall by creating an
inward  groundwater gradient. In some cases,
groundwater extraction wells alone may provide
adequate containment of contaminated ground-
water.

An upgradient barrier may  be used to reduce
the amount of groundwater contacting a con-
taminated area whereas a downgradient barrier
may  be used to restrict  the  migration of
contaminated groundwater away from a contam-
inated area.   These barriers acting alone are
probably not suitable,  for most landfill sites
because of their limited  effects on movement of
groundwater   It is difficult to completely
intercept groundwater using just slurry walls,
therefore, they are usually  implemented with
other containment  technologies such  as  a
groundwater extraction system and landfill cap.

An ideal barrier  will completely encircle the
landfill  area,  will  be  keyed  into  a  lower
acquitard (impervious layer), and will include a
low permeability  cap and a groundwater collec-
tion system  to maintain an inward hydraulic
gradient across the barrier. Such a  barrier, is
generally much more effective  in controlling
movement of groundwater and pollutants than
an upgradient or downgradient barrier or  a
partially-penetrating barrier (that is, one that is
not keyed in to an impervious layer).

The most common type of vertical barrier used
at landfill sites  (as well as other  hazardous-
waste sites) is a soil-bentonite slurry wall. Soil-
bentonitc  slurry   walls  are used  as vertical
barriers to reduce the horizontal permeability of
soil. These walls can be excavated  a limited
distance into rock material (i.e., keyed  into
bedrock) but are not generally installed in rock.

Typically,  the wall  is  constructed  using  a
backhoe or specialty clamshell, which is used to
excavate a trench 2.5 to 4 feet wide in one pass.
The trench is kept open by  the  use  of a
bentonite slurry.    In addition,  this  bentonite
slurry creates a filter cake on the sides  of the
trench as the slurry flows laterally into the soil.
This filter cake consists of a layer of bentonite
with low permeability.
Trenches are generally less than 200 feet deep.
Trenches up to 50 feet deep are  usually
excavated using  special backhoes; deeper
trenches are excavated with clamshells or other
equipment.

The  soil excavated from the trench is usually
used as backfill  material to mix with  the
bentonite slurry. Where sufficient fines are not
present (10 to  30 percent by weight that  can
pass through a No. 200 sieve), additional fines
from adjacent  borrow  areas and/or bentonite
may be  added to decrease the permeability.
The  backfill mixing is generally done adjacent
to the trench and requires an area at least as
wide as the depth of the trench. The backfill
material is then placed into the  trench using a
bulldozer.

The  permeability of the composite trench will
generally be in the order of 1 x 10"7to 1 x 10"6
cm/sec, depending on the type of backfill mate-
rial  used. The  backfill  permeability is somet-
imes affected by the migrating contaminants,
and  compatibility testing  should be performed
to determine this effect. For example, if there
is migration of nonaqueous-phase solvent from
the landfill, the bentonite slurry may not be an
effective barrier.   Other design considerations
include the potential piping  of the bentonite
fines into the trench under pressure in situa-
tions where there is large differential in water
pressure on the barrier.

Some  implementation and O&M considerations
concerning slurry walls include the following:

   •    Slurry walls can  improve,  the overall
        effectiveness of a containment system by
        using the walls  in conjunction with
        extraction wells  and a landfill cap.

   •    A slurry wall is generally a relatively
       low cost, proven technology.

   •    The necessary construction equipment
        is widely  available.

   •    The  use  of slurry walls  is  generally
        limited to relatively flat and unconfined
        sites.
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   •   For a slurry wall to be effective, the
       geologic characteristics of the  site
       should allow it to be keyed into bedrock
       or into an aquitard.

   •   There may be problems with construc-
       tion if the landfill site is located within
       a wetland area.

   •   There may be construction difficulties
       for slurry walls deeper than 50 feet.

   •   The production of large quantities of
       excess  slurry (for deep  trenches) that
       may have  to be disposed of  as  a
       hazardous waste should be considered.

   •   A distance of 50 to 75 feet of open area
       adjacent to the trench is required for
       mixing bentonite with backfill materials.

The primary data needed for designing a slurry
wall include.

   •   Existing topography and boundary  of
       the proposed slurry wall.   (The  con-
       struction of a  slurry wall requires
       relatively flat topography and sufficient
       area to mix the  bentonite  slurry and
       operate  excavation equipment.)

   •   Geologic data such as soils type, soil
       chemistry,  and  types of subsurface
       formations

    •   Depth to acquitard and groundwater as
       well as rate and direction of flow

    «   Chemical characterization of leachate,
       groundwater,   and  landfill  wastes
       (Compatibility testing with slurry wall
       material may also be required.)

4.5.3 References

Additional references on  groundwater remedia-
tion are listed below.

Collection, Treatment and Disposal

Clark, Viessman, and Hammer. Water Supply
and Pollution Control. lEP-Dun-Donnell. New
York.  1977.
Freeze et al. Groundwater. Prentice-Hall, Inc.
Englewood Cliffs, New Jersey. 1979.

Keely.     Optimizing  Pumping Strategies for
Contaminant Studies  and Remedial Actions:
Groundwater Monitoring Review. 1984. p. 63-
14.

Keely and Tsang.   Velocity Plots and Capture
Zones  of Pumping Centers for  Groudwater
Investigations:    Groundwater, Vol. 21, No.  6.
1983. p. 701-14.

Metcalf & Eddy, Inc., revised by Tchobanoglous.
Wastewater Engineering: Treatment, Disposal,
Reuse. 2nd Ed.  McGraw-Hill. New York, New
York. 1979.

Treybal,  R. Mass Transfer Operations. 3rd Ed.
McGraw-Hill.  1983.

U.S.  Environmental  Protection   Agency.
Handbook of Remedial Action of Waste Disposal
Sites. (Revised) EPA/625/6-85/006.  October
1985.

U.S. Environmental Protection Agency. RCRA,
Groundwater Monitoring Technical Enforcement
Guidance Document.      OSWER-9950.1.
September 1986.

U.S.   Environmental  Protection   Agency.
Technology Briefs,   Data Requirements for
Selecting  Remedial Action   Technology.
EPA/600/2-87/001. January 1987.

U.S.   Environmental  Protection   Agency.
Guidance on Remedial Actions for Contaminated
Groundwater at Superfund Sites.   EPA/540/6-
88/003. December 1988.

U.S.   Environmental  Protection   Agency.
Evaluation of Groundwater Extinction Remedies,
 Volume I, Summary Report. EPA/540/2-891054.
September 1989.

U.S.   Environmental  Protection Agency.
Perfromance Evaluations of Pump and Treat
Remediations:      Groundwater  Issue Paper.
EPA/540/4-89/005.  1989.
                                             4-34

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U.S. Environmental Protection Agency. Basics
of Pump and Treat Groundwater Remediation
Technologies. EPA/600/8-90/003. March 1990.

U.S.  Environmental   Protection    Agency.
CERCLA Site Discharges toPOTWS. EPA/540/
6-90/005. August 1990.
Xanthakos, P.    Slurry
McGraw-Hill.  1979.
Wells.    New  York.
             4.6  Wetlands

Many municipal landfill sites may have been
built on or  adjacent to natural wetlands and
remedial  activities may  affect the wetland
habitat. This section briefly reviews the possi-
ble consequences  to wetlands  of a nearby
municipal landfill at an NPL site, and provides
a rationale for mitigating unavoidable damage.
Two topics  are discussed:     removing  or
managing contaminated wetland soil, and miti-
gating the effects on wetlands of site remedia-
tion.   When evaluating damage to environ-
mernally sensitive areas, consideration should
also be  given  to  potential natural resource
damage  claims.

4.6.1  Removal  or Management of Wetlands
Sediments

Wetlands adjacent to municipal landfills may be
contaminated by inflows  of leachate through
surface water and groundwater pathways includ-
ing springs and seeps. Anaerobic sediments in
the wetlands may  concentrate and sequester
heavy metals or complex organics present in the
leachate.  These  compounds may reach levels
that are hazardous to humans or to the biolog-
ical components (flora and fauna) of the wet-
land.  Under these  conditions, remediation of
the wetland areas  may be required. Wetlands
sediments can be physically removed through
dredging  and then disposed of  with  other
hazardous solids.

Because of the potential for dredging to harm
indigenous wetland biota, it should be consid-
ered only as a last resort after a earful environ-
mental risk assessment of the site demonstrates
that a significant risk actually exists.   If the
potential for risk is marginal and is outweighed
by the potential for environmental harm from
sediment removal, then sediment pollutants can
be stabilized and reduced over time by liming,
bioremediation, or other technologies. Adding
lime to  a  wetlands area would  be done to
neutralize acidic groundwater or leachate  that
had migrated into  the wetland. In situ stabiliza-
tion could  potentially  be used to  immobilize
contaminated  sediments,  although this  may
harm wetland biota.  In situ bioremediation
could potentially be  implemented to  reduce
concentration  of  organic contamination  over
time. More information on  these  and other
technologies  can be found in  the document
tit led Handbook of Remedial Action at Waste
Disposal Sites (U.S. EPA, 1985a). This onsite
management  of contaminated sediments may
require monitoring to verify the rate of contam-
inant reduction.

4.6.2 Mitigating Wetlands Losses

When existing natural wetlands  must  be
disturbed through the removal of contaminated
sediments  to  protect  human health  and the
environment,  alternative approaches  may be
used to compensate for the functional loss of
wetlands. To this end,  disturbance to wetlands
will be minimized if the affected area is as small
as possible. The  effects of dredging may be
mitigated by timing dredging activities to avoid
critical biota lifestages (for example, dredging
can be conducted when plant populations are
dormant and migratory wildlife are not present).
Silt screens, hay bales, and other construction
techniques should  be used to minimize the
potential for migration of contaminated  sedi-
ments during  dredging activities. In addition,
compensation for wetland loss may be achieved
by restoring damaged  wetlands or creating new
wetlands. Restoration  may include enhancing
water flows to or natural hydrology of existing
drained wetlands. Restoration provides faster
and more valuable habitat enhancement than
does creation of new wetlands.    However,
creation of new  wetlands may be necessary
when restoration is not possible.

Creating wetlands can also mitigate the wet-
lands damage associated with some remedial
activities at municipal landfill sites.   To the
greatest  extent practical, new wetlands should
provide functional values greater than or equal
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to the values lost from the effected wetland.
These values can be assessed using the Corps of
Engineers  Wetlands  Evaluation Technique.
Additional information can be  found in  the
document titled Wetland Evaluation  Technique
(WET),  Volume II:   Methodology, Corps of
Engineers  (U.S. Army Corps  of Engineers,
1987).      When practical,  created wetlands
should be of the same general habitat type as
the areas that  were  affected  and  should  be
located in the  same  watershed  Since larger,
contiguous wetland areas generally  provide
better  habitat  and  associated  environmental
values than  smaller,  isolated wetlands, new
wetlands should be constructed  as part of larger
wetlands/aquatic systems. A larger, new wetland
area may be created to offset  the loss of a
number of smaller, isolated wetlands affected by
municipal  landfill   remediation.

4.6.3 References

Additional information on evaluation and miti-
gation  of wetlands  can be  found  in  the
following documents:

Adamus, P.  E., et al.    Wetland  Evaluation
Technique (WET):    Volume II-Methodology.
U.S. Army Corps of Engineers.  1987.

Hammer, D.A. Constructed Wetlands-for Waste-
water Treatment. Lewis Publishers,  Chelsea,
Michigan. 1989.

U.S. Army Corps of Engineers. Wetland Evalu-
ation Technique (WET). U.S. Army Engineer
Waterways  Experiment Station.    Wetlands
 Research Program.  1987.

 U.S.  Environmental Protection   Agency.
 Constructed Wetlands and Aquatic Planet Systems
for Municipal Wastewater Treatment. (Design
 Manual) EPA/625/1-88/022. 1988.

 U.S. Fish and Wildlife Service, et al. Federal
Manual, for Identifying Delineating Jurisdic-
 tional  Wetlands. An Interagency Cooperative
 Publication.  1989.
4.7  Surface Water  and  Sediments

4.7.1 Treatment of Surface Water

Generally, surface waters  such as large ponds,
rivers, or streams  are not  treated at municipal
landfill sites. However,  in  situations where
small onsite ponds or lagoons exist, it may be
viable to treat and  dispose  of contaminated
surface water. Management of surface waters in
these instances will likely be done in conjunc-
tion with contaminated groundwater and leach-
ate. Contaminated surface water will likely be
more dilute than leachate  or groundwater  and
may require only minor polishing. Although,
this may not be true for onsite lagoons in situa-
tions where disposal of liquid wastes may have
occurred.    Typically, removal  of VOCs and
semivolatile compounds from  surface water may
be achieved using air stripping and/or GAC.
More  concentrated  waste streams may  also
require neutralization, metals  precipitation, and
biological treatment for removal of COD and
BOD. In situ stabilization is also commonly
used for lagoon closures for wastes containing
primarily inorganic contaminants and 10 to 20
percent  of  organic  constituents.  Additional
discussion regarding viable treatment technolo-
gies can be found in Section  4.3.2. Since treat-
ment of surface waters will likely be for a short
duration compared to groundwater or leachate
treatment, routing surface water to the ground-
water treatment system may be feasible,  or it
 may make sense to use portable  (skid mounted)
 treatment units if additional capacity is needed.

 4.7.2 Removal and Management of Sediments

 In some  cases, it may be necessary to remove
 contaminated sediments from adjacent surface
 waters. Because of the potential  for dredging to
 harm indigenous biota,  dredging should be
 considered only after a careful risk assessment
 demonstrates that a  significant risk  actually
 exists from contaminated sediments.    When
 evaluating the risks  posed by contaminated
 sediments, consideration should also be given to
 the potential  for environmental harm  from
                                              4-36

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sediment removal. However, with this in mind,
a risk assessment for a particular site may result
in the conclusion that  removal of contaminated
sediments is necessary to mitigate unacceptable
risks to human health or the environment.

When excavating sediments below  the water
surface (dredging) the  type of equipment
depends on considerations such as the need to
control secondary migration, the depth of the
contaminated sediment, the consistency of the
contaminated sediment, the size of the  area to
be excavated, and the  depth of excavation. For
small deposits, the  sediment may be reached
from  shore using a  backhoe or  clamshell. For
large  deposits, equipment such as  a  floating
clamshell, backhoe, or a butterhead hydraulic
dredge should be considered. The most feasible
and common alternative for managing excavated
sediments is to consolidate them  with other
landfill material under  the landfill cap, although
sediments may need  to  be  filtered prior to
consolidation to remove excess water.  See the
discussion on ARARs  (Section 5.2) for munici-
pal landfill sites regarding the viability of
consolidation of sediments managed  as  a
hazardous waste. Excavation of contaminated
material will include semi-solids and  sediments.

Semi-solids are composed of saturated earth or
other  materials that have the consistency of wet
concrete.  These  materials  may flow when
disturbed and  are too  soft for excavation with
ordinary  earth-moving equipment such as bull-
dozers or front-end loaders. Tracked equip-
ment  may be used working from firm ground or
barge mounted  equipment can  be  used.
Accurate  control of the depth of excavation of
semi-solids is difficult  with draglines and crane-
suspended clam shells. More accuracy can be
obtained by using a toothless bucket as found
on a  "Gradall" (used  for cleaning ditches and
slopes)  or  as adapted to  a  conventional
backhoe.    Cutterhead dredges can  also  be
operated with reasonable accuracy.

Sediments are fluid-like deposits that do not
hold  their shape and  must be excavated as a
slurry. This requires handling large volumes of
water (frequently 80 to 90 percent). Excavation
equipment may be  either floating or operated
from shore.   Equipment used  for removing
sediments may include hydraulic dredges  (with
or without cutterhead), barge-rnounted pumps,
vacuum  trucks, or a  pneumatic  dredge.  In
pneumatic dredging, compressed air is injected
into a Venturi  pipe, and air, water, and sedi-
ment is lifted and discharged at the  surface.

Secondary migration is often a problem with
sediment  removal below water and thus may
require dewatering of the excavation area, using
sediment control barriers to  minimize migration
of sediments, or conducting  a final sweep of the
area to  remove any  redeposited sediment.
Dewatering  a submerged site is often advanta-
geous because  it minimizes the contaminated
liquid that  is  carried  with the solids. Post-
removal verification sampling can also be diffi-
cult without dewatering. Temporary dewatering
is done by driving sheet metal piling or  shoring
into the ground around the excavation area and
continuously pumping  (that  is baling) water out
of the area until excavation  is complete.

4.7.3 References

Additional references on remedial technologies
for  surface  water and sediments are listed
below:

U.S. Environmental   Protection  Agency.
Handbook of Remedial Action at Waste Disposal
Sites (Revised).    EPA/625/6-85/006.  October
 1985.

U.S.  Environmental Protection  Agency.  The
Superfund Innovative   Technology Evaluation
Program:    Technology Profiles.    EPA/540/5-
89/033.  November 1989.

U.S. Environmental Protection Agency. Systems
to Accelerate In Situ Stabilization  of Waste
Deposits.  EPA/540/2-86/002.  September 1986.

U.S. Steel. Steel Sheet Piling Handbook.  1976.
       4.8  Section  4  Summary

This section provides a description of technolo-
gies  most  practicable  for remediation of
CERCLA municipal landfill sites. This list of
technologies is based on the NCP expectations
and a review of remedial actions selected in
                                             4-37

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RODS for CERCLA municipal landfill sites        evaluate  alternatives at Superfund  sites. The
through FY 1989.                                   objective is to illustrate how each technology
                                                   might affect the alternative evaluation process.
In Section 5, these technologies are analyzed
against each  of the  nine criteria used to
                                             4-38

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                                         Section 5
                            EVALUATION  CRITERIA
Once remedial action alternatives are sufficient-
ly defined, each alternative is assessed against
nine evacuation criteria.   During the detailed
analysis of alternatives, these criteria are consid-
ered individually and are equally weighted for
importance. For the purpose of this section,
the  evaluation criteria have been divided into
three groups based on the function of the crite-
ria during remedy  selection. The three groups
include the threshold  criteria, the balancing
criteria, and the modifying criteria.

The threshold  criteria relate to  statutory
requirements that each alternative must satisfy
in order to be eligible for selection. These are:

       Overall protection of human health and
       the   environment-The   assessment
       against this criterion describes how the
       alternative, as a whole, achieves and
       maintains protection of human health
       and the  environment.

       Compliance with applicable or relevant
       and appropriate  requirements (ARARs),
       unless a waiver is obtained—Under this
       criterion, an  alternative is assessed in
       terms of its compliance with ARARs, or
       if a waiver is required,  how it is justi-
       fied.

The balancing criteria are the technical criteria
that are considered during the detailed analysis.
The technologies identified  as being most prac-
ticable for remediation of CERCLA municipal
landfill sites have,  therefore, been evaluated in
light of the following feasibility  study balancing
criteria:

  •     Long-term  effectiveness  and  perma-
       nence—Under this criterion, an alterna-
       tive is assessed in terms  of its long-term
       effectiveness in maintaining protection
       of human health and the environment
       after response objectives have  been met.
       The  magnitude  of residual  risk and
       adequacy and reliability of controls are
       taken into consideration.
  •     Reduction  of toxicity,  mobility,  or
       volume  (TMV) through treatment—
       Under this  criterion, an  alternative is
       assessed  in  terms of the  anticipated
       performance of the specific treatment
       technologies  it employs. Factors such as
       the volume  of  materials destroyed or
       treated, the degree of expected reduc-
       tions, the degree to which treatment is
       irreversible, and the type and quantity of
       remaining residuals are taken into con-
       sideration.

  •     Short-term   effectiveness-Under  this
       criterion, an alternative  is  assessed in
       terms of its effectiveness in protecting
       human health  and the  environment
       during the  construction and  imple-
       mentation of a remedy before response
       objectives have been met.   The time
       until the response objectives have been
       met is also factored into this criterion.

  •     Implementability—Under this criterion,
       an alternative is assessed in terms of its
       technical and administrative feasibility
       and the  availability of required  goods
       and services. Also considered  is the
       reliability of the technology, the ability
       to monitor  the effectiveness  of the
       remedy,  and the  ease  of undertaking
       additional remedial actions, if necessary.

  •     Cost—Under this  criterion, an alterna-
       tive is assessed, in terms of its present
       worth capital and operation  and mainte-
       nance  (O&M) costs.

Each of the five  balancing criteria represents a
significant element of the evaluation process.
However, in the case  of certain technologies
frequently used at municipal landfills, evalua-
tion under some of the five criteria may require
less analysis, For example, a clay cap does not
reduce TMV through treatment,  so the evalua-
tion of a clay cap under this criterion does not
require any effort, regardless of the site. Even
though these criteria do not require additional
                                              5-1

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analysis to evaluate, the basic conclusion will
still be important during the alternative evalua-
tion. It should be noted that all alternatives
may not need to be evaluated with respect to all
of a criterion's subcriteria. The key is to identi-
fy the subcriteria by which the alternatives vary
significantly  and to focus the evaluation  on
those factors.

Table 5-1 identifies technologies frequently used
at municipal landfill sites and summarizes how
the technology may  affect  the  alternative
evaluation criteria. The  objective  of the table is
to present basic conclusions that can. be made
for each technology in light of each of the
balancing criteria, and to identify for each tech-
nology the level of effort required under each
criterion.  The effort for analysis (i.e., level of
analysis)  is   deemed low, moderate,  or
significant, depending on the technology being
considered  for  inclusion  in  a particular
alternative. For example, using incineration as
part of an alternative may require significant
analysis of potential risks to human health and
the environment due to air emissions from the
incinerator. The two threshold criteria (overall
protectiveness  of  human  health  and  the
environment,  and compliance with ARARs)
have not been included in Table 5-1 because
these criteria are  evaluated only  once the
technologies have been  assembled into complete
alternatives.

The modifying criteria are formally assessed
after the  public  comment period. However,
state or community views are  considered  during
the feasibility study to the  extent they  are
known. The modifying  criteria are as  follows:

  •    State/support agency acceptance
  •    Community  acceptance

Communication with the state/support agency
and community is initiated during scoping and
continues  throughout the  RI/FS. Once  the
preferred alternative has been identified in the
proposed plan, and the proposed plan has been
issued for public comment,  these criteria  are
evaluated.  Based  on the comments received
during  the formal  comment period, the lead
agency may modify aspects of the  preferred
alternative or decide that another alternative is
more appropriate. More information about all
of the criteria,  including a comprehensive list of
subcriteria,  can be found in Chapter  6 of
Guidance for Conducting Remedial Investigations
and Feasibility Studies Under CERCLA (U.S.
EPA, 1988d).  Below,  a summary  is provided
regarding all criteria as they affect municipal
landfill sites.
     5.1  Overall  Protection of
         Human Health  and
           the Environment

When evaluating alternatives in terms of overall
protection of human  health and the environ-
ment,  consideration should be given  to the
manner in which site risks identified  in the
conceptual site model are eliminated, reduced,
or controlled through treatment, engineering
controls (for example, containment), or institu-
tional  controls.  Potential threats  to  human
health and  the  environment resulting from
municipal landfills may include:

  •    Leachate  generation and groundwater
       contamination

  •    Soil  contamination (including hot spots)

  «    The  landfill contents themselves

  •    Landfill gas

  •    Wetlands  contamination

  •    Contamination of surface waters and
       sediments

The overall assessment of protection of human
health and the environment is  based on eval-
uating how each of these potential  threats has
been addressed  in terms of a composite  of
factors assessed under  other evaluation criteria,
especially long-term effectiveness and perma-
nence, short-term effectiveness,  and  compliance
with ARARs.
                                              5-2

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Techno lop
Deed
Hcstncuons
l-eneing
(trading/
Revegcialion
S<«! Cover
Single -Barrier
Cap
Composite-
Barrier Cap
Table 5-1
EVALUATION OK TKCIINOUXHKS FREQUENTLY USED AT
MUNICIPAL LANDFILLS
Evaluation In Terms of I^ong.Term Effectiveness
•nd Permanence
Relics on access. vJo-rloomeni restrictions 10 manage
residual risk Difficulty in enforcement results in tow
reliability of controls. Because of virtually no long -term
effectiveness, almottt no effort 10 evaluate.
Relics on limiting access 10 manage residual risk from direct
contact- Rcliabiiin. of controls is uncertain. Fencing limits
access to the MIC although trespassing is possible. Because
of virtually no km^-term effectiveness, almost no effort lo
evaluate.
Minimal reductioa of residual risk, may reduce risk from
direct contact and reduce teachate formation hy controlling
runoff- May lessen risk from direct contact. Continued
maintenance required 10 achieve long-term reliability.
Because of virtually no long -term effectiveness, almost no
effort to evaluate.
Reduction of re^klual nsk from direct contact. With proper
maintenance is reliable in long term. May use HBLP model
lo evaluate leacrutc reduction. Significant effort to
evaluate.
Reduction of residual rok from direct contact. Lessens
future leactuitc formation and subsequent groundwater con-
tamination by reducing potential for infiltration by 70-
VO percem. Requires kxig-icnri maintenance. May use
HKl.P model and risk assessment lo help evaluate.
Significant cffon to evaluate.
Reduction of residual risk from direct contact. Minimizes
future kachatc formation and groundwatcr contamination
by *inu.tlh cJinunjttnc infiltration (99 percent reduction).
Will lasi for 20 lo 30 \vars before replacement is needed if
propcrh designed and maintained. Greater reliability than
single -barrier rap rxxause of redundancy of harriers.
although a*liabtlii\ with Urge dilTcrcniuit settlements may be
poor May uw: Hhl.P oodel or nsk assessment. Significant
effort to evaluate.
Evaluation In Terms of Reduction of
TMV Through Treatment
Not a treatment technology No effort
lo evaluate.
Not a t real mem technology No cffon
to evaluate.
Not a treatment technology No cffon
to evaluate.
Not a treatment technology. No effort
lo evaluate.
Not a treatment technology No cffon
to evaluate.
Not a treatment technology. No cffon
to evaluate.
Evaluation In Terms of Short -Term
Effectiveness
No health or environmental impacts during implementa-
tion. This criteria is not very important for the
technology and will not vary from site lo silc. Almost
no cffon to evaluate.
With the exception of physical hazards associated with
routine construction activities, minimal health or
environmental impacts during implementation. Almost
no effort 10 evaluate.
Inhalation and direct contact risk if waste is disturbed.
Proper health and safety protection may mitigate risk. If
risk is quantified, moderate cffon to evaluate.
Inhalation and direct contact risk if waste is disturbed.
Community impact through increased dust and noise
from construction and truck traffic if soil is from offsitc.
Need to determine amount of truck traffic and risk from
vehicular and construction accidents. Moderate effort to
evaluate.
Inhalation and direct contact nsk to workers if waste is
disturbed. Community impact through increased dus!
and noise from construction and truck traffic if clay
source is offsitc. Need to determine amount of truck
traffic and risk from vehicular and construction
accidents. Moderate effort to evaluate.
Inhalation and direct contact risk to workers if waste is
disturbed. Community impact through increased truck
traffic if day/soil source is offiite. Need to determine
amount of truck traffic and risk from vehicular and
construction accidents. Moderate effort to evaluate.
Pn*e 1 of 3
Evaluation In Terms of
I m p It mrn Lability
Ability to implement depends on local ordinances
May be difficult if legal requirements are not in
place, especially offsilc. Owner approval needed
for deed restrictions. Important criteria since the
ability to implement will van.' from silc lo site.
Need to contact stale or local authorities.
Significant effon to evaluate.
l-jisy to implement. I:,quipmcni readily available.
Almost no effon to evaluate.
Rasy to implement. Almost no effort to evaluate.
Ilasy to implement Determine presence of soil
nearby. Moderate effon lo evaluate
l;or » clav cap, relatively easy to implement.
Need local source of clay, winch mav be difficult
to find in certain regions. Synthetic liner requires
specialty contractor?, to assure proper installation.
Moderate effort to evaluate.
Synthetic liner requires specialty contractors lo
assure proper installation Need a source of clay,
which may be difficult to obtain in some regions
Determine presence of cl;iy nearby. Moderate
effort to evaluate.
Evaluation In
Terms of Cost
Ixw Significant
effon (difficult)
to cost but is a
minor cost
Uiw. Ijttlc
cffon to cost.
IJDW IJillc
cffon lo cost
Ixvw. M(xJeratc
effort lo cmt.
Medium if land-
fill is large.
Moderate effort
to cost.
Medium-High,
depending on
si/x' of landfill.
Moderate effort
lo cost.

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Table 5-1
EVALUATION OF TECHNOLOGIES FREQUENTLY USED AT
MUNICIPAL LANDFILLS
Page 2 of 3
Technology
Excavation
Consolidation
Excavation of
Hot Spots;
Offsite
Disposal at
landfill.
Excavation of
Hot Spots:
Onsite
Incinerration
Stabilization
Subsurface
Drains
(leachate &
G.W.)
Groundwater
Extraction
Wells (leachate
& G.W.)
Evaluation in Terms of Long-Term Effectiveness
and Permanence
Long-term effectiveness same as cap after consolidation
May use a risk assessment. May need significant effort to
evaluate.
Effectiveness dependent on the type of offsite facility and
whether or not there was a significant reduction in risk due
to excavating the hot spot area. Significant effort to
evaluate if use risk assessment.
Less residual waste onsite to manage. The reduction in risk
will depend on how much of the overall risk posed by the
site has been reduced by excavating the hot spot area.
Incineration very effective in long-term for hot sot waste.
Significant effort to evaluate if risk assessment is conducted
improved long-term effectiveness over cap alone if usec
with cap If u&cO (or ouihine hoi spots without cap will
result in some reduction in risk but will not be as effective
as excavation by reducing mobility and consolidation under
a cap. May not be effective in immobilizing organic
contaminants. All waste remains. Need to determine
permanence and long-term risk. May be significant effort to
evaluate
Some risk from groundwater remains for a long time until
groundwater remediation is complete. If designed as such,
may control further migration.Capture zone analysis may
be required. Significant effort to evaluate.
Some risk from groundwater remains for a long
grounwater remediation is complete. May effecively
control futher migration of contaminated groundwater
migration. Capture zone anlysis may be required.
Significant effort to evalutie.
Evaluation in Terms of Reduction of
TMV Through Treatment
Not a treatment technology. No effort
to evaluate.
Not a treatment technology. No effort
to evaluate.
Treatment to reduce toxicity, mobility,
and volume. The significance of TMV
reduction will depend on the
magnitude of the threat the hot spot
area posed. Moderate effort to
evaluate.
Reduction in mobility of contaminants.
No reduction in toxicity. Potential
increase of waste volume of 10-50
Percent. Stabilization may be
reversible over time. Significant eff
to evaluate.
Not a treatment technology. Evaluate
with treatment.
Not a treatment technology. Evaluate
with treatment.
Evaluation in Terms of Short-Term
Effectiveness
Disturbance of waste is a risk to workers. Proper health
and safety requirements may mitigate risk. Community
impacts through volatization of waste, dust, and
increased truck traffic if cap source is offsite.
Significant effort to evaluate to determine volatization
risk, amount of truck traffic, and risk from vehicular and
construction accident.
Disturbance of waste is risk to workers. Community
impacts through volatization, transport of hazardous
material through community, and increased truck traffic.
Significant effort to evaluate to determine volatility risk,
release of hazardous waste risk, extent of truck traffic,
and risk from vehicular and constructoin accidents.
Possible impacts from disturbance of waste and
improper air emissins. No hazardous waste take
(through commuity. Significant effort to ecaluate by
determining risk from air emissions.
Significant health and environment impacts possible
because waste is completely mixed. Impacts from odor.
dust, and volatiles. Moderate effortto evaluate.
•rt
No significant impacts during Implementator). Drains
arc usually not installed in landfill. Long time needed to
achieve cleanup goals. Significant effort required to
determine time until cleanup goals are met.
Installation of wells in landfill material may result in
impacts to the community and workers from potential
WOC emissions. Also, drilling creates potential
explosion hazards. Significant effort required to
determine time until cleanup goals are met.
Evaluation in terms of
Implementability
Same as cap chosen, if dewatering of excavation
volumes is large, may complicate implementation.
Sampling needed to determine extent of hot spot.
Significant effort to evaluate depending on extent
of Rl data.
Same as cap plus possible added difficulty of
excavating waste in wate
determine extent of hot spins Need to find
hazardous waste landfill with capac
effort to evaluate.
Metals present may still fail TCLP character!!
njtest. It may be difficult to control air emissio
and sufficent space must be available on site.
Significant effort to evaluate.
Materials readily available. May be difficult
achieve sufficent mixing in situ to stabilize waste.
Need treatability studies to determinefeasibility.
Significant effort to evaluate.
Easy to implement if subsurface is consistent and
well-defined. May nedd modeling to determine
deasibility.. Significant effort to evaluate.
Easy to implement if subsurface is consistent and
well known. Wells not reliable in fractured
bedrock. Significant effort to evaluate.
Evaluation in
Terms of Co:
Medium-High,
depending on
area being
considered.
Moderate effort
to cost.
Medium - High
.Moderate effort
to cost.
ty.
ticHigh. Significant
seffort to cost
toMedium-High.
Significant effort
to cost.
Low Medium
Significnat effort
to cost
Low-Medium.
Significant effort
to cost.

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Table S-t
KVAU ATION OF TKCIINOLOGIICS FREQUENTLY USKI) AT
MUNICIPAL LANDFILL
Vmft .1 of 3
Tethnotott
Onsiic Water
Treatment and
j Discharge
1 (k-.ichsic &
(i.W.)
Treatment at
POTW
Slurry Walk
I.K. Passive
Vents,
Active Cias
Collection
U-G Thermal
Treatment
(l-larcs)
Removal,
Onsiie
Consolidation
of Sediments
Compensatory
tt'ct lands
Kvtluation tn Terms of Long-Term Kffectiveness
•nd Permanence
Conventional technologies used lo treat (archaic and GW
(mciJth pn-op. air stripping. GAC, bio treatment) arc
proven and reliable as long us O&M is continued and
proper dtJ-fvisal assumed Significant cffon lo determine
influent and effluent concentrations and reliability.
May not he as reliable as onsitc treatment since the POTWs
typicalh. do not remove all hazardous constituents.
Contaminant may accumulate in sludges, and proper
disposal ma> not be a*&urvd. Potentially less reliable in
rural areas with small systems. DifTicult to determine
reliabiJirv Significant eflon 10 evaluate.
Difficult to maintain and therefore may not provide long-
term reliability. Moderate effort to evaluate because of
difficult to quantify, may be qualitative evaluation.
Not as effective: as an acme system in controlling offsitc
migratitYi tr. the long-term. Primarily protects cap from a
buildup ol pas and collects gas local lo (he passive well or
trench. M<\J \ary over time, requiring tang-term monitoring.
Significant effon to determine reliability and treatment
levels
ixHie-tenn effectiveness affected by cap type used after
consolidation. FTIcctrvrness abo depends on magnitude of
risk reduced through excavation of sediments. Significant
cffon to evaluate.
No mar.ijeoent of residuals. Only a replacement of
d.im.u'i-J »vtlandv hfieci/vtrncsA is not an issue, AJ/nosl no
cffon KA evaluate.
Evaluation In Terms of Reduction of
TMV Through Treatment
Treatment provides a reduction in
loxicity and/or volume depending on
the process option selected. There
may be residuals left in the form of
sludge or carbon. Treatment is not
necessarily irreversible Significant
effort 10 evaluate.
Toxicity and/or volume may be reduced
by PO'I*W. I lowcver. residuals remain.
Significant cffon tn evaluate.
Not a treatment technology. No effort
to evaluate.
Not a treatment technology. No effort
to evaluate.
Not a treatment technology. Uvaluate
with treatment icchnok»gy.
Reduces loxicity and volume
considerably. Treat men I is irreversible.
Moderate cffon to evaluate although
not difficult because of irrcvcrsibility.
Not a treatment technology. No effort
to evaluate.
Not a treatment technology and no
residua K remain. No effort lo
evaluate.
K*«lu*(ton In Term* of Short-Term
Kflecflvene&s
If air stripping is used without gaseous control, may be
some impacts. Ultimate disposal of wjner and residuals
may have an impact. Time until environment*! clean up
goals arc met depends on extraction. Collection system
may have to be operated permanently because there are
continued loadings from the landfill Very difficult to
reliably predict when groundwatcr goals can he met at
landfill perimeter. Significant effort lo evaluate.
Transport of water via pipe has potential for negative
impacts on the environment via spills, pipe rupture,
leaks resulting in infiltration. POTVY bypasses thmuph
overflows, exposure to POTW workers. Significant
effort to evaluate to determine environmental impacts
If waste is disturbed, may be limited risk to workers or
community. Almost no cffon to evaluate.
Protects cap in short-term. Mav impact the environment
and community through gas release. Modeling may be
required. Significant effon to evaluate.
May be an impact to workers by drilling through Undhll.
Moderate cffon to evaluate if waste is disturbed
No significant impact during installation, hven with
proper operation, may be slight risk to the community
depending on the constituents in the gav Significant
effort to evaluate if modeling is conducted.
Disturbance of sediments may further contaminate the
surface water. Dredging may have impact on wctland\
or surface water biota. Sediments are often left in place
to protect aquatic life. Significant eft on lo evaluate il
risk is determined.
The construction of a wetland in a clean area will ruve
positive environmental impacts. No impact to
community or workers il area is clean. Almost no ctl<>rt
to evaluate.
KvaliiNllon in Term* of
Implementeblltl)
Usually easy to implement and equipment is
available. Treatment of Icachale and GW
generally uses conventional, proven technologies.
Unusual processes may be more difficult.
Discharge requires cither NPDIiS permit or
meeting substantive requirements of the permit.
Often, POTWs refuse lo accept water, even if pre-
trcatcd. Reliability is plant specific. PO'IAV
would need additional monitoring to evaluate
effectiveness. Significant effort to determine
feasibility and find capacity.
Technical implement ability depends on site
geologic conditions. Difficult lo monitor
reliability. Significant cffon to evaluate.
Can be installed as part of new cap or in existing
cap. Moderate effort to evaluate
1 -airly easy to implement as part of new cap or
existing cap. Able to monitor effectiveness.
M< H!C™ ic clfon to evaluate.
l-jisy to implement. May be difficult to monitor
effectiveness because of lew detection limits
needed. Significant effon lo evaluate.
Technically difficult to implement due to the
possibility of dispersing contamination during
dredging. Approval for d watering/rerouting of
stream before excavation may be difficult because
of environmental impacts. Sampling during
rcntiAvt) needed. 1-ca.Mbiltiy require* significant
ell ort In evaluate.
Complex to implement successfully. Many
ecological factors need to be. taken into account.
Significant effort to determine implement ability.
Evaluation tn
Term* of Coxt
l^pw- Medium.
Moderate effon
to cost.
I jiw. Significant
effort to Ottt
I>cpends on
informal km
supplied by
POTW.
Medium-High.
Significant cffon
to cost.
Uiw. MtxJeraic
effon lo COM
1 At*;- Medium.
Significant ctlon
In cost
Medium.
Significant effon
to cmt.
l^ow-Mcdium.
.Significant effon
to cost
Medium Hi]: h.
Signitioini el I on
to cost, il
possible.

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  5.2 Compliance With ARARS

Onsite remedial actions at CERCLA municipal
landfill sites must comply with, all ARARs of
other, environmental statutes, unless a waiver
can be justified. These statutes include those
established by U.S. EPAandother federal agen-
ties and those established by the state in which
the  release occurred, if the state's standards are
promulgated, more stringent than the federal
standards, and are identified in a timely manner.

By way of defining "applicable" and "relevant
and appropriate":   applicable requirements are
federal or state requirements that "specifically
address a  hazardous  substance,   pollutant,
contaminant, remedial action, location, or other
circumstance found at a CERCLA site" (NCP
Sec. 300.5). Relevant and appropriate require-
ments are federal or state laws that, while not
applicable to a hazardous substance, pollutant,
contaminant, remedial action, or other circum-
stance at a CERCLA site, "address problems or
situations    sufficiently   similar to   those
encountered at the  CERCLA site that their use
is well suited to the particular site." (NCP  Sec.
300.5).

Another factor in determining which require-
ments must be complied with is whether the
requirement is  substantive  or  administrative.
Onsite CERCLA response actions must comply
with substantive requirements of other environ-
mental laws but not with administrative require-
ments.    Substantive  requirements  include
cleanup standards or  levels  of control; in
general, administrative  requirements prescribe
methods and procedures such as" fees, permit-
ting, inspection, and reporting requirements.

In addition to the legally binding requirements
established as ARARs, many federal and  state
programs have developed criteria, advisories,
guidelines, or proposed standards "to be consid-
ered" (TBC). This TBC material may provide
useful information  or recommend procedures if
(1)  no ARAR addresses a particular situation,
or (2) if existing ARARs (to  not provide protec-
tion. In such situations, TBC criteria or guide-
lines  should be used to set remedial  action
levels. Their use should be explained and justi-
fied in the administrative record for the site.
A more detailed discussion of the general issues
associated with ARARs and TBCs can be found
in the following documents:  the preamble to
the NCP, 55 FR 8741-8766 of March 8, 1990;
and CERCLA  Compliance with  Other Laws
Manual (U.S. EPA, 1988b).

ARARs are divided into three types:

       Chemical-specific ARARs
  •   Location-specific ARARs
  •    Action-specific ARARs

Tables 5-2 and 5-3 list the federal location and
action-specific  ARARs   that typically   arc
pertinent to  CERCLA municipal landfill sites.
ARARs pertinent to air stripping, incineration,
and direct  discharge  to POTWs  are also
included  because    these  technologies   are
frequently  used at  municipal landfill  sites.
Chemical-specific ARARs have been identified
for an example site and are listed in Section 4.1
of Appendix A. A discussion of state ARARs
follows  the information regarding  federal
ARARs.

5.2.1  Federal ARARs

5.2.1.1 Chemical-Specific ARARs

Chemical-specific  requirements   are  usually
technology-  or risk-based numerical limitations
or  methodologies  that, when applied to  site-
specific conditions, result in the establishment
of acceptable concentrations of a chemical lhat
may be found in or discharged to the ambient
environment. Information regarding the use of
chemical-specific ARARs in  risk assessments
can be found in the documents Risk Assessment
Guidance for  Superfund,  Volume I— Human
Health Evaluation Manual (Part A), Interim
Final (U.S. EPA, 1989J),  and  Risk Assessment
Guidance for Superfund,  Volume II—Environ-
mental Evaluation Manual, Interim Final (U.S.
EPA,  1989c).  Examples  of chemical-specific
ARARs and TBCs are listed for the example
silt and can be found in Appendix A of this
report.  The following is  a discussion of the
chemical-specific  ARARs that typically  are
pertinent to landfill sites.
                                             5-6

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T»hl<- 5-2
I'OTKM IAI, KKDKRA1. IXX^ATION-SPKCIKH: AKAKs AT MUNICIPAL LANDFILL SITHS
Page 1 of 2
IxKrallon
1.
2.
3.
4.
5
6.
7.
8.
Wiihm hi meters (200 feel)
of a fault displaced in
1 loloccnc lime
Wilhin 100-year floodplain
Wilhin floodplain
Wilhin sail dome formation,
underground mine, or cave
Critical habitat upon which
endangered species or
threatened species depends
Wetland
Wilderness urea
Wildlife refuge
Ktqiiirrnirnl
New ire.ilmenl, storage, or disposal
of hawrdous waste prohibited.
Facility must be designed, con-
slruclcd, operated, and maintained
to avoid washout.
Action lo avoid adverse effects,
mimmi/e potential harm, restore
and preserve natural and beneficial
values of the flcxxJplain.
Placement ot nonconlaineri/cd or
hulk liquid ha/ardous waste pro-
hibited.
Action to conserve endangered
species or threatened species,
including consultation with Ihe
Department of the Interior.
Aclion lo minimi/e the destruction.
loss, or degradation of wetlands.
Aclion lo prohibit discharge of
dredged or fill material into
wetland without permit.
Area must be administered in such
a manner as will leave it unim-
paired as wilderness and lo pre-
serve Us wilderness character
Only actions allowed under the
provisions ol 16 USC Section 668
dd(c) may be undertaken in areas
that are part of Ihe National
Wildlife Refuge System.
Prrrrquislte(s)
KCRA ha/ardous waste; PCB
treatment, storage, or disposal.
RCRA hawrdous waste; I'd)
treatment, storage, or disposal.
Action (hat will occur in a
floodplain, i.e., lowlands, and
relatively Hal areas adjoining inland
and coastal waters and other flood-
prone areas
RCRA ha/ardous waste; place-
ment.
Determination of endangered
species or threatened species.
Wetland as defined by F.xeculivc
Order 11 WO Section 7.
Federally owned area de-signaled .is
wilderness area
Area designated as part of
National Wildlife Refuge System.
Citation
40 (TK 264.18(a)
40 (TR 264 18(b);
40CFK 761.75
Fjtccutive Order
ll'WK, Protection of
FlcxxJplains, (40 CFK
6, Appendix A)
40 (TK 264.18(c)
Hndangcred Species
Act of l')73 (16 USC
15.11 el seq.); 50
(TRFartlOO, 50
CFR Part 402
1'lxcculivc Order
11 WO, Protection of
Wetlands, (40 (TK
6, Appendix A)
Clean Water Act
Section 404; 40 CTK
Parts 230. 231
Wilderness Act (16
DSC 1 131 et seq.);
50 (TK 35"TeTseq.
16 USC 668 dd et
scq.; 50 CTR Part 27
Comments
Counties considered seismically
active listed in 40 Cl-R 264
Appendix VI.
Applicable if part of the landfill is
in the 100-year fUxxlplain.
Applicable if part of the landfill is
in the 100-year fUxxlplain.
Need lo verify that ihc site does noi
contain any salt dome formations,
underground mines, or caves used
for waste disposal.
Need to identify whether any
endangered species are known lo
exist on the site. May apply in rural
areas.
Applicable if wetlands are present
next to or on the site.
Need to verify that Ihe site is not
within a Federal Wilderness Area
Need to verify that the site is not
within a National Wildlife Reluge.

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ruble 5-2
POTKNTIAI. FKDKRAI. 1XX:ATION-SPKCIKIC ARAKs AT MUNICIPAL IANDFIU. SITUS
Page 2 of 2
lx>callon
9
10
11.
12
13.
14.
Area affecting stream or
river
Within area affecting
national wild, scenic, or
recreational river
Within coaslal zone
Oceans or waters of the
United Stales
Within area where action
may cause irreparable harm,
loss, or destruction of
significant artifacts
I lisloric project owned or
controlled by federal agency
Requirement
Action lo protect fish or wildlife.
Avoid taking or assisting in action
thai will have direct adverse effect
on scenic river.
Conduct activities in manner con-
sistent with approved stale man-
agement programs.
Action lo dispose of dredge and fill
material into ocean waters is
prohibited without a permit
Action to recover and preserve
artifacts
Aclion lo preserve historic
properties; planning of action to
mimmi/e h;irm to National 1 lisloric
landmarks.
!'r
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Table 5-3
POTENTIAL FEDERAL ACTION-SPECIFIC ARAks FOR MUNICIPAL LANDFILL SITES
Cagf 1 ofl 3
Actions
Air Stopping

Dipping
Requirement
Design system lo provide odor-free operation
File an Air Pollution Emission Nonce (APliN) with the State
io include estimation of emission rates for each pollutant
expected.
Include with filed APliN the following:
• Modck-d impact jn^tysis of source emissions
- Provide a Best Available Control Technology (BACT)
review for ihc source operation.
Predict total emissions of volatile organic compounds
(VOCs) io demonstrate emissions do not exceed 450 Ib/hr.
3.000 Ib/dav. 10 gal/day, or allowable emission levels from
similar sources using Reasonably Available Control Tech-
nology (RACT).
Verify ihrough emission estimates and dispersion modeling
concentration greater than or equal to 0.10 ppm.
Venfy thai emissions of mercury, vinyl chloride, and benzene
do not exceed levels expected from sources In compliance
with hazardous air pollution regulations.
Placement of a cap over hazardous waste (e.g , closing a
Landfill, or closing a surface impoundment or waste pile as a
landfill, or similar action) requires a cover designed and
constructed to
• Provide long-term minimization of infiltration of liquids
ihrough (he capped arcj.
• Function with minimum maintenance.
• Promote drainage ,^nd minimise erosion or abrasion of ihe
cover.
• Accommodate scltiinj; and subsidence so that ihe cover's
integrity is maintained.
'X jnv bottom liner svsicm or natural subsoils present
Prerequisites


This additional work and information is
normally applicable lo sources mcelmg the
"major" criteria and/or to sources proposed
for nonattainmcni areas.
Source operation must be in an ozone
nonattainment area.


RCRA waste in landfill.
Significant management (treatment,
storage, or disposal) of hazardous waste
will make requirements applicable; capping
without disturbance will not make
requirements applicable, but technical
requirements mav be relevant and
appropriate.
Citation
CAA Sect ion 101 a
40 CFR 52a
40 CI-'R 52a
40 CFR 52a
40CFK 61 b
40CFR61a
40 CFR 264.228
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                                                                                                                      Table 5-3
                                                                               POTENTIAL FEDERAL ACTION-SPECIFIC AKAk.*. FOR MUNICIPAL LANDFILL SITKS
                                                                                                                                                                                                                                       ?mff 2 of 13
                                                Krqutrrmrnt
                                                                                                      Prerequisite*
                         I.limmaic free liquid*., stabili/.e wastes before capping
                         (surtace impoundments}

                         RCMI-JCI posi-cl<*sure use of property as neccssarv lu prevent
                         damage i*> the cover

                         Prevent run-on and run-off from damaging cover
                         Pro-tec! and  maintain surveyed benchmark^ used in locate
                         wawe cells (landfills, waste piics;

                         Disposal  or decontamination of equipmem, structures and
                                                                                                           40 CI-'K 264.22S
supipon cover
                         Installation of I'm.il cover in proud-,  |. mp-ierrr
                         o! infiltration

                         POK -closure care snd grounowHler nioriitormi;
                                             40CFX 2t>4 22R(n)(


                                             40 CFR 2t*.22£(a)(
                                                  and
                                             40 Cr-K 2o4.25S(h,
                                                                                                                                                                See discussion under Chapping
C'iean C'lo
(Kemoval
Genera!  rx.Tlt>rniancx' standard repuirt> niinim./^iior o: neec
frx- lunhcr niainicnancr and control, mininn/jinon o:
cho.inaim oi rx'M-cltfsurc escape o:  hriz^irdou^ wastt
hi/ardous const it uenis. Icachatc. cont.Hnun.ited runof:.  or
hizardous w;jj,ie dectim posit ion proouct.-
Disiurhance of KCRA ha/^rdous waste
(lisicd or charactensiicl and movcmcni
outside the unit or are^t of contammation

Ma1, apply to surtact impoundmcn! or to
aini^nunait'd soil, including soil from
dredging or soil disturbed in Ihc course of
drilling or excavation and  relumed to land
C"lc«in closure rcmov.i; ol contaminated materials docs noi appc--.r in he fc-isinlc-  lu:
most municiri.il landl'i!; sitci because of Ihc large volume of wastes  llowc%-tr. clear,
closure  icmov^i m;j> N; coriMuercJ for poriions of the siii;. sucli H^  hoi spoi areas   'I
ROvA  cic*ir. closure retjuiremenis would be considered rclcvan'. and appropnalr tn
conianunjico wastes which arc no;  hazardous, but which are similar in ha/^rxJous
                                l or deo~MiLamination o! equipmen:. structures anc!
                                                                                                                                   40 CETv 2inJ I Jispctsa' ReMnciions require trcatmcn! of RCRA waMtrs tn specified
                                                                                                                                                                         f".  wcil" ied  lechnolopirs belure land disposal  If treaiTu'p: to the specifuxi
                                                                                                                                                                         \  ih-.- specified technoiog> i> noi  achieve We or ajipropnat:;. ;>. \anante mu--: t\
                                                                                                                                                                         In mi tlie I'.I'A  If the wastes are deiermmc«1 lo U- HCHA w.isies, these
                                                                                                                                                                        iei)!1. would be applicable

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Table 5-3
POTKNTIAL FEDERAL ACTION -S PET! FIC AKARs FOR MUNICIPAL LANDFILL SITUS
Pajje 3 of 13
Actions
Clean Closure
(Removal) (cont'd.)
Consolidation




Require men!
Removal or decontamination of all waste residues,
contaminated containment system components (e.g., liners,
dikes), contaminated subsoils, and structures and equipment
contaminated with waste and Icachatc, and management of
them as ha/ardous waste.
Meet health-ban"** levels at unit.
Area from which materials are removed should be
remediated.
Consolidation in storage piJes/siorsgc sanks wi!! ingger
siorage requirements
Placement on or in Land outside unit boundary or area nf
contamination will trigger land disposal requirements and
restrictions
Develop fugitive snd odor emission control plan for this
action if exisung site plan is inadequate.
[•'le an Air Pollut»on I- mission Notice (APF-N) with siaic in
include estimation of emission rales for each pollutant
expected.
Include uith ihe Tiled Al'hN the following.
• Mi«Jelcd impaci analysis of source emissions
• A Best A\;nbNe Control Technology ^HACT) rcvio* lor
ihe source operation
Prerequisites
Not applicable 10 undisturbed material.
Dispt»sal of RCRA hazardous waste (listed
•>r characteristic) after disturbance and
movement outside ilie unit or area oC
contamination.
Disposal by disturbance of hazardous waste
(listed or characteristic) and moving tt
outside unit or boundary of contaminated
area.

After November S. 19R5


I his additional work and information is
norm.itly applicable to sources meeting the
"•n.'Hj'ir" criteria and 'or 10 sources proposed
or ni>n,iti.tmmcni ^rcas.
Citation
40CTR :M.2^(a)l)
and
40 CI-R ^>4.258
See Closure
See Container Storage,
Tank Storage, Waste Piles
m this table.
40 CFR IS6 fSubpan D)
CAA Section !0la and
40 CFK 52a
40 Cl-Tl C2d
40CH< 52"
Comment
In the event that the wastes being removed arc determined to be hazardous wastes, the
requirements of this section would be applicable.
If nonliH/ardous wastes arc excavated and moved outside the current area of
contamination, ihcsc requirements will become relevant and appropriate. These
regulations are intended to insure thai when wastes arc consolidated a) a central
location, the satellite areas (former locations of the wastes) arc remediated.
If the wastes which are excavated for consolidation are determined to be hazardous
wastes, this regulation will be applicable.
RCKA reqmrcTnCTiis for siorage in container^, lani^, or piles wiil he relevant and
appropriate lor nonhazardous wastes which are similar to RCRA ha/ardous wastes, or
for hazardous wastes disposed prior to Novemer 1980, which arc excavated from the
site and stored prior to consolidation and/or disposal.
If excavated materials can be classified as ha/^rdous wastes, the requirement will be
applicable
Certain listed ha/ardous wastes are noi eligible for disposal in landfills or other land-
based facilities unless treated to KCRA specified criteria. Hie requirement may be
relevant and appropriate to some nonhazardous wastes at municipal landfill sites which
are contaminated with ha/ardous consiituents at levels simitar to ttuwc in listed wastes,
and are excavated for rcconsolidation and disposal outside the current area of
contamination.
If any of the wastes arc determined to meet the definitions of the restricted ha/ardous
wastes, the requirements will be applicable.
Odor regulations arc intended to limit nuisance conditions from air pollution emissions.
Fugitive emission controls are one feature of (he stale implementation plan used t<>
achicvc/mamiain the ambient air quality standards for paniculate matter
See discussion under Air Stripping.
See discussion under Air Stripping

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Consoiiu.ihon
(con: d )
Containment (Con
Mruction of Nev. Sur
face Impoundment
Onsnc) (Sec Closure
wuli \\astc in Place
and Clean Closure)
Dike Stabih/jtion
Tre.timen: Svstcir
I'tfluent





i'feJici total emisiums of volatile organic compounds
(VOCs) to demonstrate emissions do not exceed 450 Ib/hr,
3.(KX> Ib/day. 10 pal/day, or allowable emission levels from
similar sources using Reasonably Available Control lech
Venf> through emission estimate?, and dispersion modeling
concentration grvaier than or equal to 0.10 ppm
Venfv thai emissions of mercury, vinvl chloride, and hcnzcnc
do not exceed levels expected from sources in compliance
with hj/.ardoub air pollution regulations.
Use two liners below, the waste, a top liner that prevents
waste migration into the liner, and a bottom liner that
presents waste migration through the liner throughout the
post -closure penod
Design and opersie facility lo prevent overtopping due lo
overfilling; wind and wave action; rainfall, run-on;
nut! unctions o( Srve! controller,. sUrnis. or other equipment.
and human error
Applicable fcdcrs! wsscr quaistv colons for the protection of
auu;tlic life must be complied with when environmental
la.'lors are bemj: considered
Applicable (cderalrv approved slate water quality standard4-
must be complied with "l"hcse standards may be in addition
to or more stnnrent than other federal standards under the.
C\VA
ITie discharge must be consistent with the requirement of a
V» jitrr Ouahtv V-inagemcni plan approved bv llf'A under
Section 20S(b) o' the Clean Water Act
i.1**' of N.T.I avails Sk technology (HAT) economically
a t i uu-in u conirt t xn. .t o n n, n cnt na
K'crir.olop (IiC! . is requited to voniroi convention.!;
jvilluianis 'Uvr-vitogv-Kiscd hmiiations m:i\ be delerminet!
'l"he discharge rr.jNl conform to applicable waier gu.thiv
requiremenis wru-n the discharge afiects a Mate oiricr ttiar.
the cen living sie'.c.

Source operation muii bo in an ii/onc
nonanainmcnt area


KCRA hawirdous waste (listed or
characicnstic) currently being placed in a
surface impoundment.
Soil/debris being managed as RCRA
ha/ardous waste
I-jcisting surface impoundment containing
hazardous waste or creation of new surface
Surface discharge of treated cfllucrs!
Surface discharge of treated effluent.

Surface discharge of treated effluent
Surface water discharge affecting waters
outside certifying stale

4(f OK 52a
40 CFR o!"
40 Cl-K 61 a
40 CF-K 264.220
40 CKK 264.221
50 FR 3(1784
(July 2V. 1985)
40 OK 122.44 and state
regulations approved
under 40 CFR 1*3
CVvA Section 20S(b)
40 CFR 122.44(a)
40 C'I'K i2244(d)(J,

Sec iiiiCussir.n under Air Stripping
Sec discussion under Air Stripping
See discussion under Air Stripping
If a new. onsitc surface impoundment is constructed to hold influent and/or effluent
from a treatment process, or to hold groundwatcr, surface water or Icachate thai is noi
operation, and maintenance of the impoundment
'Hiesc requirements would be relevant anJ appropriate id the construction ant!
operation oi a new surface impoundment or the operation and maintenance of an
cxisunp surface impAiunOnicn! onsnc h.i contain gRigndwater, surface water, leach.ttc or
the influent or effluent of a treatment JAM cm ihat is noi a hazardous waste

If state regulations are more stringent than federal water quality standards, the state
standard-, wil! IK applicable to direct discharge 'I "he state has authority under 40 C;"K
131 to impk-mcn: direct discharge requirements within the stale, and should be
contacted on a case-by-case basis when direct discharges are contemplated
Discharge must compiv with substantive bui noi administrative requirements of ihc
manapemen: plan
If trcaieJ elfiiK'ni is discharged lo surface waters, these treaimeni requirements VM' >.•
applifaHlf I'ermntmj: and reporting requirements will he applicable onlv if the elfi^-ni
isc ,.i._t^ i 
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                                                                                                                 T«bk 5-3
                                                                           POTENTIAL FEDERAL ACTION-SPECIFIC ARAK* FOR MUNICIPAL I AN OKI 1.1. SITES
       Actions
                                              Requirement
                                                                                                                                       ClUUon
                                                                                                                                                                                             Comment*
[>ircc( Discharge of
Treatment Sysicm
HfDucni (com'd.)
Discharge limitations must be established for all tonic
pollutants that arc or may be discharged ai levels greater
than I hose that can he achieved by technology-based
standards.
Surface discharge of treated effluent
                                                                                                               122.44(c)
Hxact limitations arc based on review of the proposed trcaimcni system and receiving
water characteristics, and arc usually determined on a casc-bye\elop and implement a Best Management Practices (BMP)
                       program and incorporate in the NPDtiS permit to prevent
                       the release of toxic constituents to surface waters.

                       The BMP program must:

                       •  E-MaMtsh specific procedures for the control of toxic and
                          ha/ardous pollutant  spills.

                       •  Include a prediction of direction, rale of  flow,  and total
                          quamii) o! UAK pdlluiiim& where otiicricnce indicalCA a
                          reasonable potential for equipment failure.

                       •  A«urr proper managemenl of solid and hazardous waste
                          in accordance *nh regulations promulgated under RCRA.
                                                                                   Surface water discharge.
                                                                                                                              40CFR 125.100
                                                                                                       40CFR 125.104
                                                                      These issues arc determined on a case-by-case basis by the NPDI^S permitting auihority
                                                                      for any proposed surface discharge of treated wasiewaicr. Although a CKKCI -A site
                                                                      remediation is not required to obtain an N I'D I-IS permit  for onsitc discharges to surface
                                                                      waters, the substantive requirements of the NPDI-S permit program must be met by the
                                                                      remediation action if possible. The permitting authority  should be consulted on a case-
                                                                      by-case basts to determine BMP requirements.

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                                                                                                                    Table 5-3
                                                                             POTENTIAL  FEDERAL  ACTION-SPECIFIC  ARAR's  FOR MUNICIPAL  LANDFILL SITES
                                                                                                                                                                                                                                     Page 6 of 13
      Action
                                               Requirement
                                                                                                    Prerequisites
                                                                                                                                                                                                  Comments
Direct Discharge of
(Treatment System
(Effluent  (cont'dO
Sample  preservation  procedures.container materials, and
maximum  allowable holding  times are prescribed.
                                                                                      Surface water discharge.
                                                                                                                                  40 CFR 1.36.1 -1.36.4
these requirements are generaly  incorporated into permits,  which are not required for
onsite discharges.  The substantive requirements are applicable, however,  in that
verifiable  evidence must  be offered that standards are being met.  The permitting
authority should be consulted on  a case-by -case basis to determine analytical
requirements.
Discharge to POTW"
                        Pollutants  that pass through   the POTW without treatment,
                        interfere with POTW operation, or contaminate POTW
                        Sludge  are prohibited.
                                                                                                                                  40 CFR 403.5
                                                                                                                                       If any liquid is discharged to a POTW, these  requirements are applicable. In
                                                                                                                                       accordance  with guidance, a discharge permit will be required even for an  onsite
                                                                                                                                       discharge, since permitting is the only substantive control mechanism aval liable to a
                                                                                                                                       POTW
                        Specific  prohibitions preclude the discharge  of pollutants to
                        POTWs  that:

                        . Create a fire or explosion hazard in the  POTW

                        .  Are   corrosive(ph<5.0).

                        • Obstruct flow resulting in interference.

                        . Are  discharged at  a flow rate and/or concentration that
                          will result in interference .

                        . Increase the temperature of wastewater entering the
                          treatment point that would  result  in interference, but in no
                          case raise the POTW influent temperature above 104 F
                          (40 C)

                        Discharge must comply with local POTW  pretreatment
                        program,  including POTW-specific polluatnts,  spill prevention
                        program requirements,,  and   reporting  and monitoring
                        requirements.

                        RCRA permit-by-rule  requirements must  be complied with
                        for discharges  of RCRA hazardous wastes to POTWs  by
                        truck, rail, or  dedicated pipe.
                                                                                                                                      Categorical standards have not been promulgated for CHKCLA silts, so discharge
                                                                                                                                      standards mint be determined on a casc-by-casc basis, depending on the characteristics
                                                                                                                                      of the waste stream and (he receiving PO'I"W.  Some municipalities have published
                                                                                                                                      standards for non-categorical, non-domestic discharges.  Changes in the composition of
                                                                                                                                      the waste stream due to prctrcatmcm process changes or the addition of new waste
                                                                                                                                      streams will require renegotiation of (he permit conditions.
                                                                                                          40 CFR  403.S  and local
                                                                                                          POTW   regulations
                                                                                                                                 40 CFR 264.71
                                                                                                                                     and
                                                                                                                                 40 CFR 264.72

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Table 5-3
POTENTIAL FEDERAL ACTION .SPECIFIC ARARs FOR MUNICIPAL LANDHIU- SITKS
P**r7ofU
Actions
Discharge of Dredge
and 1'fl! Material lo
Navigable Waters
Dredging
HvciVHiion


Requirement
The five condittons thai must be satisfied before dredge and
fill is an ilkwibte alternative arc:
• There must be no practicable alternative.
• Discharge ot dredged or fill material must not cause a
violation of suie water quality standards, violate any
applicable touc effluent standards, jeopardize an
endangered species, or injure a marine sanctuary.
• No discharge shall be permitted that will cause or
contribute to significant degradation of the water
• Appropriate steps to minimize adverse effects must he
taken.
• Determine Jong- and short-term effects on physical,
chemical, and biological components of the aquatic
ecosystem
Removal of all contaminated sediment.
Area from »Jivh materials are excavated may require cleanup
to levels csuSs-hrd by closure requirements.
Movement of excavated materials to a previously
u neon lamina i«l onsilc location, and placement in or on land
may trigger laad disposal restrictions.
All listed aijJ characteristic hazardous wastes or soils and
debris conurusjitcd by a KCRA hazardous waste and
removed frocr. * OKRO ,A site may not be land disposed
until trcaiexi is rvquircd by Ijmd Ban. If alicrn.tiivc
t real men i tectrologicN can achieve treatment similar to that
required K L-uxi Kan, and if this achievement can be
documented. :Scn a variance may not be required.
Prr requisites

Disposal by disturbance of hazardous waste
and moving it outside (he unit or area of
contamination.
Disposal by disturbance of hazardous waste
and moving it outside (he unit or area of
contamination.
Materials containing RCRA hazardous
wastes subject to land disposal restrictions.
Wjistc disposed was RGRA waste.
Citation
40 CMl 230.10
33 CFR 320-330
Sec discussions under
Qcan Closure,
Consolidation, Capping
40 CFR 264 Disposal and
Closure Requirements
40 CFR 268 (Subpari D)
40 CVR 2A8
Comments
This action is not envisioned as part of the site remediation.

If contaminated materials that arc not ha/ardous wastes are excavated from the site
during remediation, the RCRA requirements for disposal and site closure (of the
excavated area) may become relevant and appropriate. See discussions under Capping.
Clean Closure, Closure with Waste In-IMacc, etc
If the excavated materials can be classified as hazardous wastes, the disposal and
closure requirements would be applicable.
The land disposal restrictions restrict disposal of certain hazardous wastes. Some
municipal landfill wastes may be derived from or may be sufficiently similar lo
restricted wastes to make the land disposal restrictions relevant and appropriate.
For wastes that can be classified as restricted hazardous wastes, land disposal is
prohibited unless the)- arc treated lo defined standards. Chemical characlcri/jiiion of
the wastes will be necessary lo determine (he applicability or relevance of this
requirement.
If soil IN a characteristic waste, and if waste disposed prior to November 19X0 is rxwv
designated as a RCRA waste, then soils/sediment and leachalc contamination from
those wastes must be managed as a RCRA waste.

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V1
ON
Table 5-3
POTENTIAL FEDERAL ACTION -SPECIFIC ARARs FOR MUNICIPAL LANDFILL SITES
Pip S of 13
Ac Horn
1-jtCitvalion (cont'd.)
(i:ts Collection

Rrqutremfnl
Develop fugiirve and odor emission control plan for this
action if existing site plan is inadequate.
File an Air Poflunon Hmisston Notice (A!'I:N) with state to
include estimation of emission rales Tor each pollutant
expected
Include with ihc Hied APKN the following
• Modeled impact analysis of source emissions
• A Bat Available Control Technology (IJACT) review for
the source operation.
Predict total emissions of volatile organic compounds
(V(KV) to demonstrate emissions do not exceed 450 Ib/hr.
3.000 Ib/day. 10 eat/day, or allowable emission levels from
similar sources, using Reasonably Available Control Tech
nology (KACT).
Verify through emission estimates and dispersion modeling
that hydrogen &ulfidc emissions do nol create an ambicni
concentration greater (nan or equal to 0.10 ppm
Verify that emissions of mercury, vinyl chloride, and benzene
do not exceed k%els expected from sources in compliance
with hazardous air pollution reputations
ftoposcd standards for control of emissions of volatile
org.inics (CAA requirements to be provided)
Design system to provide odor -free operation.
File an Air Pollution Emission Notice (Ar*I:N) with slate to
include c*timaiKV\ of emission rates (of each pollutant
expccuxi.
Include with the filed APFiN the following.
• Modeled ir.pjct an.il)-sis of source emissions.
• A lies! A\ail3blc Conlrol Tcchnoktp' (HAC1") review for
the source operation.
Prcrequbiites


'i~his additional work and information is
normal Iv applicable to sources meeting the
"major" criteria andAir to sources proposed
for nonattainmem areas.
Source operation must be in an ozone
nonattainmcnt area.


Proposed standard; not yet ARAR.


'J"his additional work and information is
m>nvKillv applicable lo sources meeting the
"major" criteria and/or lo sources proposed
(or nonauainment areas.
Citation
CAA Section 101* and
40 CFR 52*
40 CI-"R 52*
40 Q-K 52s
40 CFR 52*
40 C[-"R 61*
40 CFR 61*
52 FR 3748
(l-cbruary 5. 19S17)
CAA Section 101a
and
40 CFR 52*
40 CFR 52*
40 Cl-K 52"
('.ommrnts
See discussions under Consolidation
See discussions under Consolidation
Sec discussions under Consolidation
Sec discussions under Consolidation
Sec discussions under Consolidation.
See discussions under Consolidation
This is a proposed rule. If the requirement is finali/ed in its proposed form, it may be
applicable or relevant and appropriate to some of the remedial actions at municipal
landfill sites. The proposed standard would impose restrictions on RCRA treatment,
storage, and disposal facilities that would limit the allowable emissions of volatile
organic?, from these facilities. If this requirement is finalized, it will be closejy
examined with respect lo remedial alternatives at municipal land Till sites.
Sec discussions under Consolidation
Sec discussions under Consolidation
See divusMons under Consolidation.

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                                                                                                                   Table SO
                                                                            POTENTIAL FEDERAL ACTION-SPECIFIC AKARs FOR MUNICIPAL LANDFILL SITES
                                                                                                                                                                                                                                  Puft 9 of U
                                                                                                                                                                                                Comments
Gas Collection
(com'd.)
Predict total emissions or volatile organic compounds
(VOC4) 10 demonstrate emissions do no! exceed 450 Ib/hr,
3.000 Ib/day. 10 gal/day, or allowable emission levels from
similar sources UMIW; Reasonably Available Comrol Tech-
nology (KACT)
Source operation must he in an ozone
nommammcm area.
                                                                                                                                40 CM< 52a
                                                                                                                                                            Sec discussions under Consolidation.
                        Vcnfy through emission estimates and dispersion modeling
                        •h:*! hyufr-jicn vuluuc effii.vSiOfis do noi create an ambient
                        concentration greater than or equal in 0.10 ppm.
                                                                                                                                40 CH< 61*
                        Verify ihai efiiiiSiOnS Oi mCfCuFy, viiiyj ChiO~iu€, Slid bCfinC
                        do noi exceed lexels expected from sources in compliance
                        with hazardous atr pollution regulations.
                                                                                                                                40 CITt 61*
                                                                                                                                                            See discussions under Consolidation.
(imundwatcr
Uivcrsion
F-.tcavation of srtl for construction of slurry wall may tnggcr
cleanup or land disposal restrictions.
Disposal by disturbance of hazardous waste
and moving it outside the unit or area of
contamination.
Sec Consolidation.
Excavation in this table.
If waste materials or contaminated soil that arc not hazardous wastes arc excavated or
otherwise disturtxxJ during the construction of a groundwater diversion structure, the
requirements of this section would he relevant and appropriate.

If the excavated wastes or contaminated soil can be classified as ha/ardous wastes, these
requirements would be applicable.
Incineration (Onsite)
                        Analyze the waste fecU-

                        Dtsposc- of all ha/ardous waste and residues, including ash,
                        scrubber water, and scrubber sludge.

                        No further requirements appty to incinerators that only burn
                        wastes lixcd » tu/nrdous so!c!y by virtue of !hc
                        characteristic of Amiability, cormsmty, or both; or the
                        cha ract eristic ol reactivity if the wastes will not be burned
                        when ocncr haunjous wastes arc present in the combustion
                        zone: and if the *astc analysts shows that the wastes contain
                        none of the ha/arUous constituents listed in Appendix VIII
                        which might  reasonably be expected lo be present.

                        Performance standards for incinerators:

                        •  Achieve a destruction and removal efficiency of
                          W.*W percent for each pnncipat organic ha'Mrdous
                          constituent in ihc waste food and 99.9999 percent  for
                          PC^lis and dnTuns

                        •  PariicuUtc cir^sKins muNt be less than 180 mg/dscf (.08
                          prams/dscO oxrwtcd lo 7% ()-,.
                          Keducx- h>drv.xen chloride emissions to l
                          I percent i*( tbc HO in the stack pases before entering
                          any pimuitOn <\«mf(.« ucvwrCS.
                                                                                    RCKA hazardous waste.
                                                                                                        40 CKR 264.341

                                                                                                        40'CFR 264.351


                                                                                                        40 CPU 264.340
                                                                        If incineration is selected as one of the remedial alternatives (or site rcmcdiaUon, ihcic
                                                                        requirements would be relevant and appropriate to the disposal by incineration of
                                                                        potentially nonhazardous site wastev 'Ilic wastes would have to be analysed prior to
                                                                        incineration  to insure that the wastes cannot be classified as ha/jirdous wastes.

                                                                        If wastes to be incinerated can be classified as hazardous wastes, the requirements of 40
                                                                        CM* 264.3-4!, 151, and 340 would he applicable.
                                                                                                        40 GIT* 264.343
                                                                                                        40 O--R 264.342

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Tabk S.3
POTENTIAL FKUKRAL ACTION-SPECIFlC ARARs FOR MUNICIPAL LANDFIU- SITKS
Page 10 of 13
Actions
Incineration (Onsitc)
(cont'd.)

1 .and Treatment










RcquirfRKR'.
Momlonng of various parameters during operation of the
incinerator is required These parameters include:
• Combustion temperature.
. Waste teed rale
* An indicator of combustion gas velocity
• Carbon monoxide
l.nsurc that hazardous constituents are degraded,
transformed, or immobilized within the treatment zone.
Maximum depth of treatment zone must be no more than 1.5
meters (5 feet) from the initial soil surface, and more than
1 meter (3 leel) above the seasonal high water table.
Demonstrate that hazardous constituents for each waste can
be complctcK1 degraded, transformed, or immobilized in the
treatment zone
Minimize rxin-ofl of hazardous constituents
Maintain run-on. "run-off control and management system
Special application conditions if food -chain crops arc grown
in or on treatment ?one
I'nsaturaied zone monitoring.
Special requirements for igniisbic or reactive waMc.
Special requirements for incompatible wastes.
Special requirements for RCRA haTardnus wastes.
Design system to operate odor free
File an Air Pollution Kmivsion Notice (APKN) wuh st.iie to
include osiimaifOn of criiiviiofi rntcs for each po!!u!;j,nl
ot peeled
Include with the filed AIM IN the following
• Modeled imruci analysis of source emissions
- A Best AiaiLihlc Control Tcchnolup (KACT) rou-v. for
the source operation.
prer»,Wl«


KCrKA har^rdous watte.








RCRA waste No's. F020. F021. F022,
TO23, i-X)26, ID27.


'Hiis additional work and information is
normall) applicable to wiurces meeting the
"major" criteria and/or to sources proposed
Cor nonatlainmcnl areas
ClUlion
40 CFR 264.M.1

40 ere 2M.n\
40 CI-K 264.271
40 Cf-K 264.272
40 Cre 264.273
40 CM* 264.273
40 CFR 264.276
40 CR< 2M.27R
40 CFR 264,281
40 Cre 264.282
40 Cre 264.283
CAA Section 1013
and
40 ere 52"
40 ere 52"
40 ere K*
Comment!*


Stx~ discussions under Consolidation.










See discussions under Consolidation
SL-C discussions under Consolidation

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                                                                                                                  Table 5-3
                                                                            POTENTIAL FEDKRAI. ACTION-SPECIFIC ARARx FOR MUNICIPAL lANDKILL SITES
                                                                                                                                                                                                                                Pug* 11 of 13
                                              Requirement
                                                                                                  Prerequisites
I .and Treatment
(cont'd )
Predict lotal emissions of volatile organic compounds
(VOCs) 10 demonstrate emissions do noi exceed 450 Ib/hr,
3,000 Ib/day.  10 gal/day, or allowable emission levels from
simitar sources using Reasonably Available Conlrol Tech-
nology (RACT)

Verify through emission estimates and dispersion modeling
thai hydrogen sulfidc emissions do not create an ambient
concentration  erratcr than or equal to 0.10 ppm.

Verify that emtsAions of mercury, vinyl chlondc. and benzene
do no! exceed levels expected from sources in compliance
with hazardous air pollution regulations.
Source operation must be in an ozone
nonauamment area.
                                                                                                                                40 CFR 52a
                                                                                                                               40 CFR 61a
                                                                                                                               40 CFR 61a
                                                                                                                                                           Sec discussions under Consolidation.
                                                                                                                                                           Sec discussions under Consolidation
                                                                                                                                                           See discussion under Consolidation
Operation and
Maintenance
Post-closure care to ensure that site is maintained and
monitored
                                           40 CFR 264.118
                                           (RCRA, Subpart G)
Post-closure requirements for operation and maintenance of municipal landfill sues are
relevant and appropriate to new disposal units with nonhazardous waste, or existing
units capped in-place.

In cases where municipal  landfill site wastes are determined (o be hazardous wastes,
and new disposal units arc created, the post-closure requirements will be applicable.
Removal
                       General performance standard requires minimization of need
                       for further maintenance and control; minimization or
                       elimination of post-closure escape of hazardous waste,
                       hazardous constituents, Icachate. contaminated runoff,  or
                       hazardous waste decomposition products.
                        Disposal or devAxitamination of equipment, siructures, and
                        soils.

                        Removal or decontamination of all waste residues.
                        contaminated coo tain men t system components (e.g.. liners.
                        dikes), contaminated subsoils, and structures and equipment
                        contaminated with waste and Icachatc, and management of
                        them as hazardous waste.

                        Meet health-Ne
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l-o
O
Tabk 5-3
POTENTIAL FEDERAL ACTION-SPECIFIC ARARs FOR MUNICIPAL LANDFILL S1TKS
P«*r 12 of 13
Actions
Slurry Wall
Surface Water
Control
Treat men 1




Rfqulfvmenl
hxcavaiion of soil [or construction or slurry wall may trigger
cleanup or land disposal restrictions
Prevcni run-on, and control and collect runoff from a
Landfills)
Prevent over-topping of surface impoundment.
Standards for miscellaneous units (long-term retrievable
storage, thermal treatment other than incinerators, open
burning, open detonation, chemical, physical, and biological
treatment units using other than tanks, surface
impoundments, or land treatment units) require new
miscellaneous units to satisfy environmental performance
standards by protection of groundwnlcr. surface water, and
air qu.ilitv. and bv limiting surface and subsurface migration
1 rcatmcnt of wastes subject to ban on land disposal must
attain levels achievable by best demonstrated available
treatment technologies (BDAT) for each ha/Jtrdous
constituent in each listed waste
Prepare fugitive and odor emission control plan for this
action
Hlc an Air Pollution Emission Notice (AI'KN) with stale in
include cstim.mon of emission rates for each pollutant
expected
Include with the filed Al'l:-N Ihc following
• Modeled impact analysis of source emissions
• A llesi Available Control Technology (BACT) review for
the source operation.
Prvfrquklles
Disposal by disturbance of hazardous waste
and moving ii outside the unit or area of
contamination.
l.and-bascd treatment, storage, or disposal


Use of other units for treatment of
hazardous wastes These units do not meet
the definitions for units regulated
elsewhere under RCRA.
Effective dale for CERCLA actions is
November 8, 1988, for P001-P005
ha/ardous wastes, dioxin wastes, and
certain "California List" wastes Other
restricted wastes have different effective
dates as promulgated in 40 CFR 268.


This additional work and information is
normally applicable to sources meeting the
"major" criteria and/or to sources proposed
for non.it lain mem areas
Citation
Sec Consolidation,
Uxcavation in (his table.
40 CFR 264.2Sl(c)(d)
40 CFR 264.27.Xc)(d)
40 CFR 264.301(c)(d)
40 CF-T* 264.221(c)
40 CFR 264
(Subpart X)
40 CFR 268
(Subpan D)
CAA Section 101a
and
40 Cl-lt 52*
40 Cl-TC 52a
40 CFK 52a
Comments
Sec discussions under Consolidation and Excavation.
The requirements for control of run-on and run-off will be relevant and appropriate to
all remediation alternatives that manage nonhazardous waste and include onsitc land-
based treatment, storage, or disposal.
The requirements wilt be applicable to any remediation measures that include land
based treatment, storage, or disposal of hazardous wastes
This requirement will be relevant and appropriate to the construction and operation of
an onsiic surface impoundment, or to operation of an existing onsitc surface
impoundment managing nonhazardous wastes
These requirements would be applicable to the construction or operation of a surface
impoundment for Ihc storage or treatment of hazardous waste.
The requirement will be relevant and appropriate to the construction, operation,
maintenance, and closure of any miscellaneous treatment unit (a treatment unit that is
not elsewhere regulated) constructed on municipal landfill site for treat men i and/or
disposal of nonhazardous wastes
These requirements would be applicable to the construction and operation of a
pow
These regulations are applicable to the disposal of any municipal landfill site waste that
can be defined as restricted wastes.
These requirements arc relevant and appropriate to the treatment prior la land disposal
of any wastes that contain components of restricted wastes in concentrations that make
Ihc site wastes sufficiently similar lo the regulated wastes. The requirements specify
levels of treatment that must be attained prior to land disposal
See discussions under Consolidation.
See di\cnsM<>ns under Consolidation.
Sec discuvsmns under Consolidation.

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Maximum Contaminant Levels (MCLs). MCLs
are  enforceable drinking water standards estab-
lished by U.S. EPA under the Safe Drinking
Water Act. MCLs establish the maximum level
of a contaminant that is allowed in water deliv-
ered to any user of a public water system. An
MCL for a specific contaminant is required by
law to be set as close  as feasible to the maxi-
mum  contaminant level  goal (MCLG) (see
Section 5.2.2.1)  for  the same  contaminant,
taking into consideration the best technology,
treatment techniques, and other factors  (includ-
ing  costs).

MCLs, as the enforceable requirements of the
SDWA,  are potential ARARs  pursuant  to
CERCLA Section 121(d)(2)(A)(i). The  NCP
further states that MCLs generally have the
status of ARARs for groundwater when the
MCLGs are  not an ARAR and the MCLs are
relevant  and appropriate under the  circum-
stances  of the  release. A discussion  of this
issue can be  found on page 8753 of the pream-
ble  to the March 8, 1990, final NCP. Typically,
MCLs are considered relevant and appropriate
to groundwater Class I and II aquifers. Compli-
ance with an ARAR generally would be  mea-
sured at the landfill boundary (not at the
property boundary).

In some cases, a waiver of the MCLs may need
to be  obtained.  As an  example, a landfill with
waste below the water table may continue to
exceed MCLSs in groundwater far into the  future
because of continued leaching of waste. In such
cases,  groundwater collection and  treatment
may not achieve MCLs at the landfill boundary,
and a waiver for technical impracticality would
need to be obtained. A technical impracticality
waiver  for  termination  of  a  groundwater/
leachate collection and treatment system  is
usually available at some extended time  in the
future for municipal landfill sites in the  event
that  MCLs are   not achievable  [SARA
 Maximum Contaminant Level Goals (MCGLs).
 MCGLs are non-enforceable  goals for drinking
 water set by U.S. EPA under the Safe Drinking
 Water Act.  MCGLs represent a contaminant
 level presenting  "no  known or  anticipated
 adverse effects on the  health of persons" and
allowing for an additional adequate margin of
safety beyond that level. MCGLs are listed in
40 CFR 141.50.

Based on the NCP, 40 CFR 300.430(e)(2)(i)(B),
MCGLs above  zero  should be attained by
remedial actions for ground or surface water
that is a current or potential source of drinking
water where the MCGLs are determined to be
relevant and appropriate  under the circum-
stances  of the release. When the MCLG for a
contaminant has been  set  at zero,  the  MCL
promulgated  for that contaminant should be
attained  for  current or potential sources  of
drinking water,  where the MCL is relevant and
appropriate.    In  cases where ARARs (for
example, MCLs, MCGLs)  are not available for
a particular contaminant,  or in cases  where
ARARs  are not sufficiently  protective  (e.g.,
because of multiple contaminants), remediation
goals should be based on a risk assessment
where acceptable exposure levels generally are
concentrations that represent an excess upper
bound lifetime  cancer risk to an individual of
between 10'4and 10'6.

Secondary Maximum Contaminant Levels.
Secondary MCLs are non-enforceable goals for
drinking water  established by EPA  under the
Safe Drinking  Water Act. Secondary  MCLs
pertain  to contaminants  that,  if present  in
excessive quantities, may discourage the utiliza-
tion of a public water supply because they affect
qualities such as taste, color, odor, and corrosiv-
ity. Secondary MCLs are TBCs and are listed
in 40 CFR 143. In many cases, exceedance of
secondary  MCLs  is the  first indication  of a
more serious problem with a drinking  water
source.

Federal Water Quality  Criteria  (FWQC),
FWQCs are non-enforceable guidelines devel-
oped by  EPA  under the  Clean  Water  Act.
However, they are potential  ARARs because
SARA and the  NCP state  that FWQC shall be
attained "where relevant and appropriate under
the circumstances of the  release" (CERCLA
Section    1 2 1 (d) (2)(B);  40   CFR
300.430(e)(2)(i)(E)). Two types of criteria have
been set by  EPA, one for the protection of
human health and another for the protection of
aquatic life. FWQCs set quantitative levels of
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pollutants in water, the levels such that water
quality is adequate for a specified use.  These
levels are based solely on data and scientific
judgments regarding  the relationship between
concentrations  of  a  pollutant  and resulting
effects on environmental  and human  health.
FWQCs  do  not  reflect  consideration  of
economic or technological feasibility. FWQCs
are used by  the states to set their own water
quality standards for surface water. They are
also typically used by state and federal agencies
in setting National Pollution Discharge Elimi-
nation System (NPDES) discharge permit levels.

Whether a water quality criterion is relevant
and appropriate depends on the designated or
potential water  uses,  the environmental media
affected, the purpose for which such  criteria
were  developed, and the latest available  scienti-
fic  information available (see CERCLA  Section
 121(d)(2)(B)(i)). Although a state may  develop
its  own use  classification  scheme, designated
uses  generally  include recreation, protection,
and propagation of fish and aquatic life; agricul-
tural  and industrial uses; public  water  supply
and navigation.

For water designated  as a public water supply,
MCL/MCLGs would  generally be relevant and
appropriate   the criteria  that  reflect fish
consumption may also be relevant and appro-
priate if fishing is included in the state's desig-
nated use. If the state has designated a water
body  for recreation,  a water  quality  criteria
reflecting fish consumption alone may be rele-
vant and appropriate if fishing is included in the
recreational use designation. Generally, water
quality criteria are not relevant and appropriate
for other uses, such as industrial or agricultural,
since  exposure  reflected in  the water  quality
criteria are not  likely to occur. The two types
of FWQC are discussed below:

  •     FWQCs for Human Health Protection:
        One  goal of  the FWQC  is to  protect
        humans  from hazards associated with
        two routes of  exposure, including expo-
        sure from drinking the water and expo-
        sure from consuming aquatic organisms,
        primarily fish.   There are  nonbinding
        guidelines provided that address expo-
        sure from both routes, and from fish
        consumption alone. The criteria identi-
       fy concentrations equating to specified
       levels  of cancer risk (10"5, 10"', and
       10"') for carcinogens or threshold-level
       concentrations for noncarcinogens that
       represent  the  water concentrations  at
       which there  would be no  chronic
       adverse health effects. There are also
       criteria for chemicals with organoleptic
       properties  (that is, affecting, taste  or
       odor but not health). These criteria are
       based on concentrations  at which there
       would be no  taste or odor problems.
       The  FWQC values for human' health
       protection can be found  in the Federal
       Register,  Vol.  45 (No.  231),  FR pg.
       79318,  November  29,   1980-Water
       Quality Criteria.

  •    FWQCs  for Aquatic Life  Protection:
       The  FWQC criteria  for  the protection
       of aquatic life present two sets of values,
       one based on the protection of aquatic
       life from acute exposure and the other
       from chronic exposures. When data are
       not sufficient to  set  a  criterion, the
       lowest reported acute or chronic-effects
       level published in the literature is used.
       A summary of water quality criteria may
       be found in Quality Criteria for Water
       (U.S. EPA, 1986aa), which is commonly
       referred to as the "Gold Book."

Office Of Drinking Water Health Advisories.
The health  advisories  are non-enforceable
guidelines (TBCs) that present the EPA Office
of Water's most recent determination regarding
the  concentration level of  drinking water
contaminants below which adverse effects would
not be anticipated to occur. This level includes
a margin of safety to protect sensitive members
of the population and is subject to change  as
new  health  information becomes  available.
Levels are specified for 1-day,  10-day, longer
term (e.g., 10 percent of one's lifetime, 7 years),
and lifetime exposure  periods.

5.2.1.2 Location-Specific ARARs

Location-specific ARARs are the  restrictions
placed on the concentration of hazardous sub-
stances or  the  conduct  of activities solely
because they occur in special  locations. These
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requirements relate  to the  geographical  or
physical position of municipal  landfill  sites
rather than to the nature of. the  contaminants
or the  proposed remedial  actions.   These
requirements may limit the type of remedial
action that can  be implemented and  may
impose  additional constraints on the cleanup
action. The restrictions caused by flood plains
and  wetlands are among the most common
location-specific potential ARARs for munici-
pal landfill sites.    Federal location-specific
ARARs,  for municipal landfill sites  are
presented in Table  5-2,  at  the  end of this
section. The following is a discussion of the
location-specific ARARs that typically are  most
pertinent to landfill sites.

Wetlands. Remediation of municipal landfill
sites located next to wetland areas will have to
be implemented in a manner which minimizes
the destruction,  loss or degradation of wetlands
(40  CFR 6.302(a)). Additionally,  the Clean
Water Act Section 404 prohibits discharge of
dredged or  fill material  into a wetland  area.
Situations where  wetlands, are filled or  have
been irreparably harmed may  require  the
creation of new wetlands. Information on the
Corps of Engineers methodology for identifying
and evaluating  wetland areas can be found in
the document Wetland Evaluation  Technique
(WET) (U.S. Army Corps of Engineers, 1987).

Floodplains.     Remediation  of  landfill  sites
located within   floodplains  (for  exam-
ple, lowlands, and relatively flat areas adjoining
inland  and  coastal waters)  will have to  be
carried  out to  the  extent possible, to avoid
adverse  effects, and to preserve natural  and
beneficial values of the floodplain (40  CFR
6.302(b)).    For  example,  remedial  actions
should  not be designed and constructed in a
manner that destroys the usefulness of a flood-
plain, thereby potentially causing  adjacent areas
to become flooded.

5.2.1.3 Action-Specific ARARs

Action-specific  ARARs are usually technology-
or activity-based requirements or  limitations on
actions  taken with  respect to hazardous sub-
stances.    These requirements typically define
acceptable  treatment,  storage,  and disposal
procedures for hazardous  substances during the
implementation  of the response action. The
requirements  generally  set  performance  or
design standards for specific activities related to
managing hazardous wastes at municipal landfill
sites.   Action-specific ARARs for municipal
landfill sites are shown in Table 5-3, located at
the end of this section. The following is a dis-
cussion of the  action-specific ARARs that typi-
cally are most  pertinent to landfill sites.

RCRA Closure Requirements. A determination
must be made  on which RCRA closure require-
ments are applicable or relevant and appropri-
ate for the specific  site  of concern.   RCRA
Subtitle D requirements are  generally applicable
unless a determination is made that Subtitle C
is applicable  or  relevant and  appropriate.
RCRA Subtitle C would be  applicable if the
waste is a listed or characteristic waste under
RCRA,  and (1)  if the waste  was disposed of
after  November  19,  1980 (effective date of
RCRA) or (2) the response action constitutes
current treatment, storage, or disposal as certi-
fied by RCRA. The decision about whether a
RCRA requirement is relevant and appropriate
is based on consideration of a variety of factors,
including the nature of the waste  and its
hazardous properties, and  the nature  of the
requirement itself. State  closure requirements
that are an ARAR and that are more stringent
than the federal requirements must be attained
(or waived). Listed hazardous wastes are found
in 40 CFR Part 261, Subpart D. Characteristic
hazardous wastes under RCRA are described in
40 CFR Part 261, Subpart C.

Because  containment of landfill wastes is  a
common element of most remedial actions at
municipal landfill sites,  the  most  significant
closure requirements will likely be the RCRA
requirements concerning landfill covers. RCRA
Subtitle C closure requirements specify that a
landfill cover for a permitted facility  have a
permeability less than or equal to the  perme-
ability of any bottom liner system or natural
subsoils present (40 CFR 264.310). Additional
information on landfill covers can be found in
Section 4 of this document.
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Land Disposal Restrictions. Offsite disposal of
contaminated soils  from hot spots may  be  a
viable component of a remedial action alterna-
tive for a municipal landfill site. In situations
where the material  is regulated as hazardous
under RCRA Subpart C,  land  disposal  of
contaminated soils offsite will be based largely
on the  RCRA  Land  Disposal Restrictions
(LDRs).  The LDRs may be applicable to the
contaminated soils if it is determined that the
soils have been  contaminated by a restricted,
listed RCRA waste or if the contaminated soils
are a RCRA characteristic waste.  The LDRs
may require that a specific concentration  level
be achieved or that a specified technology be
used for treatment prior to land disposal in a
RCRA facility.  Treatment  of hot spots and
subsequent disposal may also trigger LDRs.

If soils  contain  RCRA  waste, offsite  land
disposal  must  be  at  a permitted RCRA
hazardous waste  landfill that meets the require-
ments of RCRA Subtitle C, that is in compli-
ance with CERCLA Section 121(d)(3) and the
Superfund offsite policy. The design features of
a RCRA hazardous waste landfill are defined in
40 CFR  254 Subpart N. If the soils  are not a
RCRA waste or if they  are  delisted, offsite
disposal may be  at a solid waste landfill that is
in compliance with the offsite policy and
CERCLA Sec.  121(d)(3). In the  absence  of
other regulations, solid waste landfills are regu-
lated under RCRA Subtitle D. However,  in
most cases, state regulations  govern the design,
construction, operation, and closure of  solid
waste landfills

Air Emission Treatment Requirements. Several
alternatives for remediation of landfill sites may
include technologies that result in a discharge
of contaminants to the air. Table 5-3 presents a
summary of the federal requirements concerning
air emissions for technologies commonly imple-
mented at municipal landfill sites. The need for
air emission treatment should be  evaluated
based on federal and state requirements and an
evaluation of human health risks. Technologies
that typically result in air emissions include air
stripping, collection and treatment of landfill
gas,  excavation and consolidation of contami-
nated soils, and incineration.
The EPA Office of Air Quality, Planning, and
Standards is currently developing new source
emission guidelines and  performance  standards
for collection and treatment of landfill gas. The
proposed rule (a TBC) would require an active
landfill  gas collection and control system for
solid waste landfills with emissions exceeding
100 megagrams per year of nonmethane organic
compounds. Treatment of landfill gas (e.g., by
enclosed ground flares) would be  required to
demonstrate a destruction removal efficiency of
98 percent or emissions less than or equal to 20
ppm (volume dried) of nonmethane organic
compounds. Since these  emission guidelines
and standards are currently under development,
some changes may be made.

The proposed air emission standards will apply
to new municipal solid waste landfills as well as
to those facilities that have accepted waste  since
November 8, 1987, or that have capacity avail-
able for future use.  For  CERCLA municipal
landfill  remediations,  these requirements would
be potential ARARs for all records of decision
(RODS) signed  after the  rule's  promulgation
date. The standards in this rule,  once promul-
gated, will be applicable  for those municipal
landfill  sites on the NPL that accepted waste on
or after November 8, 1987, or that are  operat-
ing and have capacity for future use. In cases
where these standards are not applicable, such
as landfill sites  that accepted waste prior to
November 8, 1987, they may still be determined
to be relevant and appropriate. The determina-
tion of relevance and appropriateness is made
on a site-specific basis pursuant to NCP Section
300.400(g) (55 Federal Register 8841, March 8,
1990).  Judgment should be used in applying
these guidelines and standards since  they will
apply to  municipal  solid waste landfills as
opposed to CERCLA sites where there is typi-
cally co-disposal of both municipal solid waste
and hazardous waste.

5.2.2 State ARARs

In general, in order for a state requirement to
be considered an ARAR, it must:

  •    Be promulgated (be legally  enforceable
       and of general applicability)
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  •    Be identified to EPA in a timely manner

  •    Not result in an in-state ban  on land
       disposal of hazardous waste

  •    Be more stringent than federal require-
       ments

Even if the  state standard meets these condi-
tions, it may be waived if it is found not to have
been applied  uniformly  and  consistently
throughout the state.

Because  many states may  be revising their
standards in any given year, more stringent state
standards for municipal landfill sites need to be
identified cm a case-by-case basis. The aspects
of state requirements that are likely to be more
stringent are described below.

5.2.2.1 Chemical-Specific ARARs

State Drinking Water  Acts.    Many  states
administer drinking water  acts that contain
chemical-specific standards and criteria that are
often ARARs for groundwater remediation.  A
review of state standards should be conducted
to see if any  standards or criteria  (such as
drinking water action levels)  exist that  are more
stringent than federal standards (for example,
MCLs and MCGLs). For cases where a more
stringent state standard Exists for a particular
compound, the state standard  should  be used,
where relevant and appropriate under the cir-
cumstances of the release (most drinking water
standards are not legally "applicable" to ground-
water). In  addition, states often have  health
advisories that are more stringent than federal
criteria.   These TBCs may be considered as
well.

Clean Water Act. Many states administer the
federal Clean Water Act and its important com-
ponent, the  NPDES program, which  contains
standards and criteria for discharge of treated
waters to nearby surface waters (see Section
5.2.2.3).

5,2.2.2 Location-Specific ARARs

Wetlands.  State requirements for designation
of wetlands should he reviewed to determine if
they  are  more  stringent than  the  Corps  of
Engineers' methodology. Stringent state meth-
odologies for identifying wetlands can expand
the extent of wetlands requiring mitigation.  In
cases where wetlands have been contaminated
or destroyed, mitigation measures may need to
be  included in  the remedial  action.  State
requirements can  differ significantly  from
federal regulations.

Floodplains.  State ARARs  often prohibit the
siting of landfills in floodplains, which in turn
may restrict onsite disposal options.

5.2.2.3 Action-Specific ARARs

NPDES  Program. Pretreatment requirements
for discharge directly to a publicly owned treat-
ment works (POTW) under the  NPDES
program may be dictated by a local or regional
government agency.   A careful review of a
state's NPDES requirements and of the poten-
tial pretreatment requirements  that  would  be
imposed by the POTW is therefore necessary.
Frequently, discussions on the acceptability of a
discharge to  a POTW will extend well into the
predesign and design phases at Superfund sites.
There is also a tendency for POTW permitting
authorities to set stringent discharge standards
because  there is no categorical standard for
CERCLA operations and because of public fear
or mistrust of "hazardous waste."

Direct discharge of treated effluent offsite to a
surface  water body would also require  an
NPDES  discharge permit. In many cases  EPA
has delegated implementation of this program
to the states. Therefore, as with discharge to a
POTW,  a review of a state's NPDES  require-
ments should be  conducted if direct discharge
offsite to  a surface water is being considered.

Closure  Requirements.  State requirements for
cover of hazardous and solid waste landfills
should be reviewed to determine whether more
stringent design criteria exist for the construc-
tion,  operation, and closure of landfills. The
state  may also have erosion and sedimentation
control regulations.   Local requirements (e.g.,
erosion   control regulations) and  closure
requirements such as  minimum standards  for
cover designs may be important TBC material
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although they are generally not ARARs (unless
they represent the state standards).

Air  Emission Treatment Requirements.  As
with the water programs, many states administer
the Clean Air Act (CAA). State air emission
standards should be reviewed for technologies
such as incineration or air stripping to see  if
requirements more stringent than federal CAA
requirements exist. Landfill gas emissions may
also be  regulated under state air regulations.
5.3 Long-Term  Effectiveness and
              Permanence

Some aspects of long-term effectiveness include
the ability of a cap to  maintain its integrity, the
ability of groundwater extraction to meet clean-
up levels, and the long-term maintainability of
leachate or gas treatment systems. Long-term
effectiveness  also includes an evaluation of the
magnitude of residual risk.  Because the tech-
nologies generally considered practicable for
municipal  landfill sites  will  not completely
eliminate the  hazardous substances at a landfill,
long-term management of waste is a critical
issue. Complete evaluation under this criterion
should require  determining  the risk posed by
the remaining waste.  One of the more time-
consuming tasks associated with the evaluation
under this criterion may be the need  to estimate
infiltration through an existing or new landfill
cap. Groundwater and air modeling also may
be  needed.   EPA's  computer model HELP
(hydrologic evaluation of landfill performance),
which is  discussed  in  Section  4.2 (Landfill
Contents), may be useful in evaluating this
criteria.
  5.4 Reduction of TMV Through
               Treatment

 Generally, reduction of TMV at municipal land-
 fill sites occurs through treatment of hot spots.
 However, TMV can also be reduced through
 treatment of groundwater, leachate, or landfill
 gas. When treatment  is  used,  a number of
 factors must be considered.   Naturally, the
 treatment  process  used and  the materials
treated must be evaluated. This evaluation can
be particularly significant for innovative tech-
nologies or conventional technologies  being
applied to a waste that has unusual character-
istics.    The volume of material destroyed or
treated must be evaluated, as well as the degree
of expected reductions.    Also, the degree 10
which treatment is irreversible must be consid-
ered, particularly for technologies like stabiliza-
tion. Technologies such as capping  and fencing
that provide no treatment do not require evalu-
ation under this criterion.
   5.5  Short-Term Effectiveness

A significant issue of short-term effectiveness is
the effect on the community of truck traffic as
large quantities of cap material arc hauled onto
the site. Both  noise and potential increases in
vehicular' accidents must be considered (con-
struction of a typical  40-acre  multilayer cap
requires  about 32,500 truckloads of capping
material). Other issues such as potential VOC
emissions during excavation of hot spots and
during construction  and operation of onsite
treatment systems are  associated with worker
and community  protection  during  remedial
activities.  Also included under this criterion are
the environmental impacts resulting from the
remedial action. To evaluate this  criterion, the
time required to achieve the response objectives
must be  determined, including an estimate  of
time to achieve remediation of  leachate and
groundwater.
        5.6  Implementability

Administrative implementability is the relative
difficulty   of coordinating   and   obtaining
approvals from  other agencies to  perform
certain activities.  The difficulty of meeting this
subcriterion will vary from site to site, and
depends primarily on the location  of the site
and what other agencies are  involved. There
may be significant administrative implement-
ability issues associated with offsite deed restric-
tions  and alternative water  supplies.    The
enforceability  of deed restrictions tends to vary
greatly, depending on local laws and  ordinances.
Likewise, the administrative implementability of
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treating leachate  or  groundwater at a POTW
depends on how receptive local treatment plant
officials  are to accepting contaminated water
from the site.  It is not uncommon for discus-
sions  with POTWs  to extend well  into the
remedial  design phase.

The technical implementability of a technology,
including the ability to construct and/or operate
the technology, and the reliability of the tech-
nology, largely depends on the treatability  of
the contaminated material. For example, tech-
nical difficulties are likely when using incinera-
tion for wastes that are high in metals, or when
using in  situ stabilization for  wastes containing
moderate to high levels of organics. The tech-
nical  implementability of some  technologies
would also depend on availability of sufficient
space for the materials-handling and/or equip-
ment. Also, the ability to monitor the effective-
ness of a remedy  is a consideration, particularly
for a technology  like in situ  stabilization. The
ease of undertaking additional remedial actions,
if necessary, must also be considered.   The
treatment technologies that have been identified
as being  most practicable for  municipal landfill
sites are proven  conventional technologies  (a
few  innovative  technologies have also been
discussed).

The availability of goods and services will also
vary from site to site and will depend primarily
on a  site's location and  accessibility.  As  an
example, the  implementability of bringing  in
truckloads of fill material will depend on the
source of the  material and the accessibility  to
the site.
                5.7  Cost

In Table 5-1, an indication is given of whether
each technology will have a low, medium, or
high impact on total cost if included as part of
an  alternative.  Costs can be difficult to  esti-
mate for groundwater extraction and treatment
and for hot spot excavation and/or treatment
because the volume of contaminated ground-
water and hot spots is difficult to estimate accu-
rately  during the RI/FS.  FS  cost  estimates
should provide an accuracy of +50 percent to
-30 percent using data available from the RI.
        5.8 State Acceptance

Under this criterion, an alternative is evaluated
in terms  of the technical and administrative
issues and  concerns  the state  (or support
agency) may have.   This  is a criterion  that is
addressed in the record of decision (ROD) once
formal comments are  received on the RI/FS
report (to the  extent  they are known, state
concerns are considered earlier in the process as
well). Frequently, state acceptance is closely
related to compliance  with state  ARARs.
    5.9 Community Acceptance

Under this criterion, an alternative is evaluated
in terms of the issues  and concerns the public
may have. As with  state  acceptance, this is a
criterion that is addressed in the ROD once the
comments have been formally received on the
RI/FS report (also,  to  the extent they  are
known,  community concerns  are considered
early  in the process as well).
     5.10  Section 5 Summary

This section presents each of the evaluation
criteria and illustrates how each of the technol-
ogies identified in Section 4 may affect each of
the  alternative  evaluation criteria.   In  the
following section, alternatives typically devel-
oped for a municipal landfill site are presented.
The section describes how the technologies
discussed in this section (Table 5-1) might be
combined  and then evaluated as alternatives
using the nine criteria.
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                                         Section 6
   DEVELOPMENT AND  EVALUATION OF  ALTERNATIVES
                          FOR THE EXAMPLE SITE
Based on the review of practicable technologies
for municipal landfill sites (see Section 4) and
the actual characteristics of the  example site
(see Appendix A), a range of typical alternatives
has been developed.     The purpose is to
illustrate how technologies might be combined
to form  alternatives typically developed for
landfill sites. Some components of these alter-
natives may not be applicable to other sites,
depending  on  their specific  characteristics.
Table 6-1  presents an  evaluation of each
alternative with respect to the threshold criteria,
overall protection of human health and the
environment, and compliance with ARARs and
the five balancing  criteria  described in
Section 5.    The  modifying criteria,  state
acceptance, and community acceptance are not
included in Table 6-1  since  they are not
formally  evaluated during the FS.  These two
criteria are addressed in the Record of Decision
(ROD) and are used as a basis for modifying an
alternative due  to formal comments from the
state or  community cm the FS report  and
proposed plan. Addressing state and commun-
ity concerns  is incorporated  throughout the
RI/FS process;  formal use of the  modifying
criteria once the proposed plan has been issued
is not the  first time  these concerns are
addressed.

The example site, considered a co-disposal facil-
ity with  a known hot  spot, is  described in
Appendix A—Site Characterization Strategy for
an Example Site.  To summarize, the site is
approximately 60  acres  in size  (20 acres of
which is a landfill) and is  in a rural area. In
addition to  municipal  trash,  the landfill
accepted chemical  wastes  such as  solvents,
paint, paint thinners and lacquers, and industri-
al plating sludges. Available records show no
indication of segregation of wastes.  Industrial,
commercial, and municipal wastes are generally
mixed throughout the landfill, except for liquid
industrial solvent wastes. Disposal of this waste
was generally restricted
to the southern portion of the landfill. Exposed
areas in the southern half of the landfill have
been  temporarily covered with a partial cap
consisting of 2  feet of compacted  clay. The
remainder of the landfill has a temporary soil
cover, although there are some areas of exposed
wastes.

The unconsolidated deposits underlying the site
are  approximately 135 feet thick and consist
primarily of sand and gravel of glaciofluvial and
alluvial origin. Bedrock in the vicinity of the
site, encountered at an  approximate depth  of
135 feet, consists of undifferentiated Cambrian
sandstone up to  1,200 feet thick. These sand-
stones are fine to coarse grained and contain a
small amount of  shale.

Some  of the contaminants  of concern are
trichloroethene (TCE) and vinyl chloride (VC)
in the soil and groundwater; lead, arsenic, and
total chromium in the soil; and methane gas.

The  areas  of concern  for the example site
include:

   •    Landfill  contents under the existing soil
        cover

   •    The hot  spot outside  the existing soil
        cover

   •    High-strength (onsite)  groundwater
        (leachate)

   •    Low-strength (offsite) groundwater

   •  Surface water sediments (from a nearby
        unnamed tributaty)

   •    Landfill  gas

The ARARs for the Example Site are discussed
below:
                                             6-1

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Table 6-1
RECOMMENDED ALTERNATIVES SUMMARY OF DETAILED ANALYSIS
EXAMPLE SITE
Page 1 of 6

Alternative 1
No Action
Alternative 2
Single-Barrier Cap
Consolidation of Hot Spot
High-Strength Groundwater (Leachate)
Collection and Onsite Treatment
Low-Strength Groundwater Extraction and
Onsite Treatment
Discharge to Unnamed Tributary
Consolidation of Surface Water Sediments
Institution Controls
Five-Year Review
Alternative 3
Composite-Barrier Cap
Consolidation of Hot spot
High-Strength Groundwater (Leachate)
Collection and Onsite Treatment
Low-Strength Groundwater Extraction and
Onsite Treatment
Discharge to Unnamed Tributary
Consolidation of Surface Water Sediments
Institutional Controls
Five-Year Review
Alternative 4
Single-Barrier Cap
Treatment of Hot Spot (onsite)
High-strength Groundwater (Leachate) Collection 1 id
Onsite Treatment
Low-Strength Groundwater Extraction and Onsite
Treatment
Discharge to Unnamed Tributary
Consolidation of Surface Water Sediments
Institutional Controls
Five-Year Review
Evaluation Criteria
Overall Protection of Human
Health and the Environment
Compliance with ARARs
Long-Term Effectiveness
* Magnitude of Residual
Risk
* Adequacy and Reliability
of Controls
No action taken. Not
considered to be protec-
tive of human health and
the environment
No action taken. Not
expected to be in
compliance with ARARs.
Exisitng infiltration
through cap will continue.
Infiltration allows leaching
of contaminants to
groundwater. Risks from
direct contact will also
remain.
Continued erosion of
existing cap likely to
occur. Wastes could
eventually be exposed with
potenttial for exposure
onsite or transport of con-
taminants in runoff to
wetlands.
Construction of a cap reduces the risk of
exposure to the landfill contents, and
reduces leaching of contaminants to the
groundwater. Institutional controls and
monitoring of groundwater quality will be
required during aquifer restoration to
protect public health and the environment.
Expected to be in compliance with ARARs
Reduction of residual risk from direct
contact. Lessons future potential for
groundwater contamination by reducing
infiltration. The groundwater is collected
and treated; however, the source of
contamination remains, presenting a possible
future risk that contamination will breach
the containment system .
Improved reliability over no action.
Requires long-term maintenance to maintain
the integrity of the cap
A compsite-barrier Cap will be more reliable
than a single-barrier cap in terms of preventing
direct contact with landfill contents and reducing
infiltration. Institutional controls will still be
required during the period of aquifer restoration
for protection of public health and the
environment.
Expected to be in compliance with ARARs.
Potential for infiltration is reduced over single-
barroer cap protection. The groundwater is
collected and treated; however, the source of
contamination remains, presenting a possible
future risk that contamination will breach the
containment system.
Increased reliability over the single-barrier cap.
Synthetic liner provides an additional barrier for
reducing infiltration and leachate generation
resulting from infiltration. Potential for rupture
of synthetic liner from differential setting.
Requires long-term maintenance to maintain the
integrity of the cap.
Treatment of hot spots provides additional protection
to human health and the environment by reducing the
volume of contamination at the site. As with
Alternative 2 and Alternative 3, institutional controls
will still be required during the period of aquifer
restoration to prevent the use of contaminated
groundwater.
Expected to be in compliance with ARARs
Less residual waste onsite to manage since hot spots
will be excavated and incinerated and the groundwater
will be collected and treated. Excavation may reduce
long-term risk. The groundwater is collected and
treated; however, a portion of the source of
contamination remains, presenting a possible future risk
that contamination will breach the containment system.
Provides the greatest long-term effectiveness and
permanence since hot spots will be treated. Continued
maintenance will be required to maintain the integrity
of the cap.

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Table 6-1
RECOMMENDED ALTERNATIVES: SUMMARY OF DETAILED ANALYSIS
EXAMPLE SITE
Page 2 of 6











Alternative 1




No Action





Alternative 2
Single-Barrier Cap
Consolidation or Hot Spot
High-Strength Groundwater (Leachate)
Collection and Onsite Treatment
Low-Strength Groundwater Extraction and
Onsite Treatment
Discharge to Unnamed Tributary
Consolidation of Surface Water Sediments
Institutional Controls
Five-Year Review
Alternative 3
Composite-Barrier Cap
Consolidation or Hot Spot
High-Strength Groundwater (Leachate)
Collection and Onsite Treatment
Low-Strength Groundwater Extraction and
Onsite Treatment
Discharge to Unnamed Tributary
Consolidation of Surface Water Sediments.
Institutional Controls
Five-Year Review
Alternative 4
Single-Barrier Cap
Treatment of Hot Spot (onsite)
High-Strength Groundwater (Leachate) Collection and
Onsite Treatment
Low-Strength Groundwater Extraction and Onsite
Treatment
Discharge to Unnamed Tributary
Consolidated of Surface Water Sediments
Institutional Controls
Five-Year Review
Evaluation Criteria
Reduction of Toxicity,
Mobility, and Volume
* Treatment Process Used
and Materials Treated

* Amount of Hazardous
Materials Destroyed or
Treated






* Expected Reductions in
Toxicity, Mobility, and
Volume
* Irreversibility of the
Treatment

* Type and Quantity of
Treatment Residual



A treatment technology is
not included as part of
this alternative.
A treatment techno Igy is
not included as part of
this alternative.






A treatment technology is
not included as part of
this alternative.
A treatment technology is
not included as part of
this alternative.
A treatment technology is
not included as part of
this alternative.


Conventional treatment of groundwater
including metals precipitation, biological
treatment (activated sludge), GAC.
High-strength groundwater (leachate)
collected from perimeter wells will be
treated, primarily to prevent offsite
migration of contaminated groundwater.
Offsite groundwater will be collected and
treated. The rate of hazardous materials
destroyed will depend on the extraction rate
(that is, whether a high or low flow rate is
selected).
Toxicity or volume of contaminated
groundwater may be reduced by treatment
system .
Groundwater treatment process may not be
irreversible.

Sludge from metals precipitation process
may need to be dispoced of at a RCRA
landfill.


Conventional treatment of groundwater including
metals precipitation, biological treatment
(activated sludge), GAC.
High-strength groundwater (leachate) and low
strength groundwater (offsite) will be collected
and treated. The amount of hazardous materials
destroyed will depend on the extraction rate (that
is, whether a high or low flow rate is selected).




Toxicity or volume of high strength groundwater
may be reduced by treatment system.

Groundwater treatment process may not be
irreversible.

Sludge from metals precipitation process may
need to be disposed of at a RCRA landfill.



Hot spots to be treated onsite via incinerator. Same as
Alternative 2 and 3 for groundwater treatment.

Reduction in the hazardous organic constituents would
be achieved by incineration of hot spots. Same as
Alternative 2 and 3 for groundwater.






TMV would be reduced through the treatment of hot
spot areas. Same as Alternative 2 and 3 for
groundwater.
Incineration is permanent. Same as Alternative 2 and 3
for groundwater.

Ash from incinerator will be placed under cap. Same as
Alternative 2 and 3 for groundwater reciduals.


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Table 6-1
RECOMMENDED ALTERNATIVES: SUMMARY OF DETAILED ANALYSIS
EXAMPLE SITE
Page 3 of 6











Alternative 1




No Action





Alternative 2
Sinle-Barrier Cap
Consolidaation of Hot Spot
High-Strength Groundwater (Leachate)
Collection and Onsite Treatment
Low-Strength Groundwater Extraction and
Onsite Treatment
Discharge to Unnamed Tributary
Consolidation of Surface Water Sediments
Institutional Controls
Five-Year Review
Alternative 3
Composite-Barrier Cap
Consolidation of Hot Spot
High-Strength Groundwater (Leachate)
Collection and Onsite Treatment
Low-Strength Groundwater Extraction and
Onsite Treatment
Discharge to Unnamed Tributary
Consolidation of Surface Water Sediments
Institutional Controls
Five-Year Review
Alternative 4
Single-Barrier Cap
Treatment of Hot Spot (onsite)
High-Strength Groundwater (Leachate) Collection 1 d
Onsite Treatment
Low-Strength Groundwater Extraction and Onsite
Treatment
Discharge to Unnamed Tributary
Consolidation of Surface Water Sediments
Institutional Controls
Five-Year Review
Evaluation Criteria
Short-Term Effectiveness
* Protection of Community
during Remedial Action





* Protection of Workers
during Remedial Action





* Environmental Impacts






No action taken.






None required.






No remedial action.






Possible impacts from consolidation
activities. Community impact through
increased dust and noise from construction
and truck traffic. Truck traffic introduces
risk from vehicular accidents .


Potential risk to workers through inhalation
and direct contact during grading and
excavation of hot spots. Proper dust control
and health and safety proteciton will
mitigate risk.


Potential for exposure to waste or runoff of
contaminants to Polk River during
implementation. Potential negative impact
from possible secondary migration of
contaminated surface water sediments
during removal for consolidation under cap.

Possible impacts from consolidation activities.
Community impact through increased dust and
noise from construction and truck traffic. Truck
traffic introduces risk from vehicular accidents.



Potential risk to workers through inhalation and
direct contact during grading and exavation of
hot spots . Proper dust control and health and
safety protection will mitigate risk.



Potential for exposure to waste or runoff of
contaminants to Polk River during
implementation. Potential negative impact from
possible secondary migration of contaminated
surface water sediments during remowal for
consolidation under cap.

Possible impacts from disturbance of waste and
improper air emissions. Adverse impacts to air quality
from malfunctions of incinerator and poor destruction
efficiency could also be expected. Community impact
through increased dust and noise from construction and
truck traffic. Truck traffic introduces risk from
vehicular accidents .
Greatest potential for safety -related problems because
it involves the excavation of contaminated materials.
Direct exposure and inhalation is the safety risk to
workers. Although detailed planning, design, and
implementation can minimize the potential safety
problems to onsite and offsite personnel, they cannot be
totally eliminated.
Potential negative impact due to air emissions from
incineration. Potential for exposure to waste or runoff
of contaminants to Polk River during implementation.




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Table 6-1
RECOMMENDED ALTERNATIVES: SUMMARY OF DETAILED ANALYSIS
EXAMPLE SITE
Page 4 of 6

Alternative 1
No Action
Alternative 2
Single-Barrier Cap
Consolidation of Hot Spot
High-Strength Groundwater (Leachate)
Collection and Onsite Treatment
Low-Strength Groundwater Extraction and
Onsite Treatment
Discharge to Unnamed Tributary
Consolidation of Surface Water Sediments
Institutional Controls
Five-Year Review
Alternative 3
Composite-Barrier Cap
Consolidation of Hot Spot
High-Strength Groundwater (Leachate)
Collection and Onsite Treatment
Low-Strength Groundwater Extraction and
Onsite Treatment
Discharge to Unnamed Tributary
Consolidation of Surface Water Sediments
Institutional Controls
Five-Year Review
Alternative 4
Single-Barrier Cap
Treatment of Hot Spot (onsite)
High-Strength Groundwater (Leachate) Collection and
Onsite Treatment
Low-Strengh Groundwater Extraction and Omsite
Treatment
Discharge to Unnamed Tributary
Consolidated of Surface Water Sediments
Institutional Controls
Five-Year Review
Evaluation Criteria
Short-Term Effectiveness
(continued)
* Time Until Remedial
Action Obj ectives are
Achieved
No time requirements.
Less than 2 years should be required to
implement components of the remedy. If a
low flow extraction rate (e.g., 200 gpm) is
selected the goal for achieving groundwater
remediation would be 15 years. If a high
flow extraction rate (e.g., 500 gpm) is
selected the goal for achieving groundwater
remediation would be 5 years. This assumes
continued collection of leachate and a
completely effective leachate collection
system controlling offsite migration of
contaminated groundwater.
Less than 2 years should be required to
implement components of remedy. Goal for
achieving remediation is the same as
Alternative 2.
Groundwater remediation will be the same as
Alternative 2. However, incineration of hot spots and
dredging of surface water sediments will require
additional time to implement the source control
components of this remedy. The source control
components should be implemented in less than 4 years.

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Os
Table 6-1
RECOMMENDED ALTERNATIVES SUMMARY OF OF DETAILED ANALYSIS
EXAMPLE SITE
Page 6 of 6











Alternative 1




No Action





Alternative 2
Single-Barrier Cap
Consolidation of Hot Spot
High-Strength Groundwater (Leach ate)
Collection and Onsite Treatment
Low-Strength Groundwater Extraction and
Onsite Treatment
Discharge to Unnamed Tributary
Consolidation of Surface Water Sediments
Institutional Controls
Five-Ymr Review
Alternative 3
Composite-Earner Cap
Consolidation of Hot Spot
High-Strength Groundwater (Leach ate)
Collection and Onsite Treatment
Low- Strength Groundwater Extraction and
Onsite Treatment
Discharge to Unnamed Tributary
Consolidation of Surface Water Sediments
Institutional Controls
Five-Year Review
Alternative 4
Singel-Barrier Cap
Treatment of Hot Spot (on site)
High-Strength Groundwater (Leach ate) Collection and
Onsite Treatment
Low- Strength Groundwater Extraction and Onsite
Treatment
Discharge to Unnamed Tributary
Consolidated of Surface Water Sediments
Institutional Controls
Five-Year Review

evaluation uritena
Implementability
(continued)
• Admnistered Feasibility

Ability to coordinate
and obtain approval
from other agencies




COST


Administrative problems
affecting alternative
feasability are not
expected. However, no
action will likely be
unacceptable since the
remedy is not protective
and there will not be
compliance with ARARs.
None


Discussions with the state for an NPDES
permit for discharge of treated groundwater
to the unnamed tributary to the Polk River
are uncertain and may extend into design.





. Medium


Discussions with the state for an NPDES permit
for discharge of treated groundwater to the
unnamed tributary to the Polk River are
uncertain and may extend into design.





_ Medium-high.


Sufficient space must be available on site to build
incinerator. More difficult to implement than other
alternatives.

Same as Alternative 2 and 3 for discharge of treated
groundwater.



High

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      6.1  Example  Site  ARARs
 6.1.1.2 Surface Water
 In  addition to the potential  federal ARARs
 listed in Section 5, state requirements for the
 example site that are promulgated, more strin-
 gent than federal requirements, and applicable
 or relevant and appropriate are  discussed below.
 It is emphasized that this discussion on specific
 state ARARs applies only to the Example Site.
 The purpose of this discussion is to present
 some typical state requirements that may affect
 the development and  evaluation of  remedial
 alternatives.

 6.1.1 Chemical-Specific ARARs

 6.1.1.1 Groundwater

 Chemical-specific  state standards  for the
 Example  Site  include  state groundwater
 enforcement clean-up standards and preventive
 action limits.    A  list of the specific  state
 groundwater enforcement standards and pre-
 ventative action limits that apply to the example
 site can  be found in Appendix A.  Typically,
 corrective  actions may be more extensive if
 enforcement  standards  are  exceeded.  In
 general, preventive action limits apply wherever
 groundwater is monitored. State  enforcement
 standards apply at the following locations:

   •    Any point of groundwater use

   •    At or beyond the property boundary of
        the facility

   •    Any point within the property bound-
        ary beyond   the  three-dimensional
        design  management  zone,  if one is
        established by the state

 The design management zone  is an imaginary
boundary at some horizontal distance from the
waste boundary that extends downward through
 all saturated geologic  formations.    For land
disposal  facilities with feasibility studies that
were approved by the state after  October 1,
 1985, a horizontal distance of 150 feet is used
for the design management zone.
 Potential state ARARs for the Example Site for
protection of aquatic life include state ambient
water quality criteria for aquatic life protection.
 A list of the specific state ambient water quality
 criteria that apply to the Example Site cart be
 found in Appendix A. Any direct discharge of
 treated  water (including groundwater or leach-
 ate) to the unnamed tributary of the Polk River
would likely have to achieve these standards to
comply  with NPDES requirements.

6.1.2 Location-Specific ARARs

No location-specific state ARARs exist that are
stricter  than the federal ARARs listed in Table
5-2. Most significantly, the  site is not located
within the  100-year floodplain nor have  wet.
lands been impacted by the Example Site.

6.1.3 Action-Specific ARARs

6.1.3.1  Soils/Landfill Contents

The Example Site  has more stringent action-
specific state ARARs than the federal ARARs
for the  construction of a solid waste  landfill
cover.   Portions  of these cover requirements
specify  including  a 2-foot clay layer with a 1.5-
to 2.5-foot cover layer and 0.5 foot of topsoil on
the surface.  The purpose of this requirement is
to assure that adequate freeze-thaw protection
is included in the design of the cap. Otherwise,
expansion and contraction during  freeze-thaw
events could result in the formation of cracks in
the landfill cover.
 6.2  Development  of Alternatives

When developing alternatives, it is important to
reevaluate pathways from the conceptual site
model that  may not represent a  significant
threat to human health  or the environment at
this site. For  example,  landfill gas does not
appear to be  a  significant threat  to  human
health and the  environment at the Example Site
because the area is rural  and  only  a small
                                             6-8

-------
amount of gas is generated. Therefore, future
use of the site may allow some access (such as
for hunting). Because some landfill gas is likely
to be  generated,  it may be  appropriate to
include passive vents in the design of a landfill
cap.

For municipal  landfill  sites with minimal
hazardous  waste and no known hot spots,  it
may not be necessary to consider a composite-
barrier cap or soils treatment and consolidation.
An exception might be sites where erosion has
dispersed some contaminated soils without any
discernible hot spots.  In these instances, some
consolidation of surficial soils may reduce the
area that needs to be capped.

The range of alternatives  developed  for the
Example Site is  composed of the four alterna-
tives described below.

6.2.1 Alternative l~No Action Alternative

Under Alternative  1, no action would be taken.
The no-action alternative is  required as part of
the NCP and provides a baseline against which
other alternatives can be compared.

6.2.2 Alternative 2

Alternative 2 is  composed of the four compo-
nents listed below.

Component 1.  Containment

   •    Construction of a single-barrier cap (to
        cover entire  landfill).    Freeze-thaw
        protection would be included as part of
        the design of the  cap. Passive vents
        would be installed to vent landfill gas.
        Long-term monitoring of  landfill gas
        would also be included as part of the
        remedy.

   •    Surface  controls (as part of cap con-
        struction)

            Grading
            Revegetation
Component 2. Consolidation of the hot spot
               under the clay cap

   •     Since the hot spot is generally within
        the  landfill contents,  consolidation
        would only be required to the extent
        necessary to minimize the size of the
        landfill cap.

Component 3.   Groundwater  extraction and
               treatment

   •     High-strength groundwater (leachate)
        collection  by perimeter  wells, and
        onsite treatment with discharge to the
        unnamed tributary to the Polk River

   •     Low-strength  groundwater (offsite)
        extraction  (by wells) and onsite treat-
        ment with  discharge to the unnamed
        tributary to the Polk River

Component 4. Consolidation of surface water
               sediments under landfill cap

   •     Consolidation of surface  water  sedi-
        ments from  the  unnamed  tributary
        would include dredging the sediments
        and consolidating  them  with other
        material under the landfill cap.

Component 5.   Institutional  controls

   •     Deed restrictions to:

            Limit site access
            Prohibit groundwater use

Component 6. Five-year review

Alternative  2  would  minimize infiltration of
surface  water  and potential  for direct contact
with the landfill contents. Passive vents would
be installed to prevent accumulation of landfill
gas. Perimeter wells would be installed around
the landfill to  capture high-strength ground-
water (leachate) resulting from onsite contami-
nation. Downgradient extraction wells would be
                                              6-9

-------
installed to capture offsite ground-water. The
selection of a groundwater extraction rate for
collection and treatment of offsite groundwater
would be  determined  during design.    It is
estimated that, if a total  offsite groundwater
extraction rate of 500 gpm is selected, it would
require at least 5 years  to achieve MCLs at the
landfill boundary. If a total offsite groundwater
extraction  rate of 200 gpm  is selected, it is
estimated  that at least 15  years  would  be
required  to  achieve   MCLs  at the landfill
boundary.    These estimates  assume that the
onsite perimeter groundwater extraction wells
would be completely effective at controlling
offsite  migration of  leachate.     Extracted
groundwater  would  be  treated onsite and
discharged to the  unnamed tributary to the Polk
River.

High-strength (onsite) groundwater  would
require  removal  of inorganics  using  metals
precipitation, removal of oxygen demand (BOD,
COD) using activated  sludge biological treat-
ment, and removal of VOCs  and semivolatiles
using air  stripping or GAC. Low- strength
(offsite)  groundwater would  only  require
removal of. VOCs and semivolatiles. Because
the site is rural and because  the threat due to
direct contact would be minimized, construction
of a fence has not been included in this  alterna-
tive.   Deed restrictions,  however,  would be
placed,  prohibiting onsite groundwater use or
site development.

Sediment  consolidation (from  the  unnamed
tributary) could reduce the potential  for offsite
migration of contamination in the long term.
However, sediment dredging  could have unac-
ceptable  short-term impacts due to resuspension
of contaminated  sediments. To minimize short-
term impacts, temporary dewatering of the exca-
vation  areas should  be  performed  before
sediment removal.

6.2.3 Alternative  3

Alternative 3 is composed of the six  compo-
nents listed below.
Component  1.  Containment

   •    Composite-barrier  cap

           The layers of the composite-barrier
           cap may include (from the top): a
           vegetative layer, a drainage layer, a
           flexible  membrane liner  (first
           barrier),  a clay  layer (second
           barrier), and a bedding layer. As
           with a clay cap, freeze/thaw protec-
           tion (that is, 3 feet of soil) would
           be   part  of the  design of the
           composite-barrier cap. The design
           would also include the installation
           of passive vents to vent landfill gas.
           Long-term monitoring of landfill
           gas would also be included as part
           of the remedy.

   •    Surface  controls (as  part  of cap
       construction)

           Grading
           Revegetation

Component 2.  Consolidation  of the hot spot
                under the landfill cap

   •    Since the hot spot is generally within
       the  landfill  contents, consolidation
       would be  required only to  the extent
       necessary  to minimize the size of the
       landfill  cap.

Component 3.   Groundwater  extraction and
                treatment

   •    Collection via perimeter wells and
       onsite   treatment   of high-strength
       groundwater (leachate). Effluent would
       be discharged to the unnamed tributary
       to the Polk River.

   •    Offsite extraction (by wells) and onsite
       treatment of low-strength groundwater.
       Effluent would be  discharged to the
       unnamed tributary to the Polk River.
                                              5-10

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Component 4.  Consolidation of surface water
               sediments under  landfill cap

   •    Consolidation  of surface water  sedi-
        ments  from the  unnamed  tributary
        would include  dredging  the sediments
        and  consolidating  them with other
        material under  the landfill cap.

Component 5.  Institutional  controls

   •    Deed restrictions to:

            Limit site access
            Prohibit groundwater use

Component 6. Five-year review

Alternative 3  is similar to Alternative 2 except a
composite-barrier  cap  would be constructed
instead  of a  single-barrier cap.  A composite-
barrier cap would provide maximum protection
against  direct  contact and  would minimize
potential  infiltration.  A composite-barrier cap
would also adhere to the design requirements of
RCRA guidance for new landfill cells. As with
Alternative 2, the  selection of a pumping rate
for extraction of offsite groundwater would be
determined during design.

6.2.4 Alternative 4

Alternative 4 is composed of the six compo-
nents listed below.

Component  1.  Containment

   •    Single-barrier cap

            Includes installation  of passive
            vents for landfill gas and long-term
            monitoring of landfill gas

   •    Surface  controls (as  part  of  cap
        construction)

            Grading
            Revegetation
Component 2. Treatment of the hot spot

   •    Onsite  incineration
   •    Consolidation of ash under landfill cap

Component 3.  Groundwater  extraction and
               treatment

   •    Collection  and onsite  treatment of
        high-strength groundwater  (leachate).
        Effluent would be discharged to the
        unnamed tributary to the Polk River.

            Perimeter wells

   •    Low-strength groundwater  extraction
        and onsite treatment.  Effluent would
        be discharged to the unnamed tributary
        to the Polk River.

            Offsite wells

Component 4.  Consolidation of surface  water
               sediments under  landfill cap

   •    Consolidation of surface water  sedi-
        ments  from  the  unnamed tributary
        would include dredging  the sediments
        and consolidating them with the  other
        material under the landfill cap.

Component 5.  Institutional  controls

   •    Deed restrictions to:

            Limit site access
            Prohibit  groundwater use

Component 6. Five-year review

In  addition to the components  outlined for
Alternative 2, Alternative 4 includes treatment
of material excavated from the hot spot area by
onsite  incineration. Consolidation of the ash
under the landfill cap is anticipated.  By includ-
ing treatment, this alternative would provide
some reduction in toxicity, mobility,  or volume.
Because the hot spot area  would  be treated
rather than  consolidated  under the cap,  a
single-barrier cap is considered adequate.
                                             6-11

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    6.3  Comparative Analysis
            of Alternatives

As part of the feasibility  study, an individual
analysis is conducted where each of the remedi-
ation alternatives is compared to the nine crite-
ria described in Section 5 of this document (see
Table 6-1). A comparative analysis of alterna-
tives  is  conducted  following  the  individual
analysis. The comparative analysis focuses on
the significant differences between the alterna-
tives.  Because  all the alternatives (except no
action)  include  collection  and treatment  of
leachate and offsite contaminated groundwater,
the comparative analysis does not focus on this
aspect of the remedial  action.   A  pump and
treat alternative, is more  effective, protective,
expensive, and  reliable  than  no action,  and
reduces the volume of contaminants. It is also
more  difficult to implement.

A comparative analysis of the alternatives with
respect to the threshold criteria and balancing
criteria follows. As with the individual analysis,
the modifying criteria of  state acceptance and
community acceptance are not included because
they are used to modify an alternative based on
formal state and  community comments once the
proposed plan has  been released.

6.3.1 Overall Protection of Human Health and
the Environment

Alternatives  2  through  4  are protective  of
human health and the environment. Ingestion
of contaminated groundwater is prevented by
groundwater collection and treatment. Direct
contact with waste and release of VOCs from
waste  would be mitigated by either  of  the
proposed caps. The combination of the leach-
ate collection system (perimeter wells), offsite
groundwater extraction wells, and  either  a
single- or composite-barrier cap would mitigate
groundwater  contamination.

The decrease in permeability of the composite-
barrier cap does not increase its protectiveness,
just  its  effectiveness  and reliability.  The
potential increase in infiltration from using a
single-barrier cap instead of a composite-barrier
cap may increase the amount of leachate that is
collected and treated but will  not necessarily
reduce protectiveness.  Incineration of the hot
spot may increase protectiveness by reducing
the contaminant source and subsequent contam-
inant load to groundwater, thereby potentially
reducing  groundwater and leachate  treatment
costs.

The no-action alternative is not considered
protective since risk from the various pathways
is  not controlled.

6.3.2 Compliance  With ARARS

The state in which the Example Site  is located
requires  sanitary  landfills to be closed with a
cap consisting of 2 feet of clay as a  minimum
barrier layer and sufficient cover material to
protect against freeze/thaw damage.  Alterna-
tives 2, 3, and 4 will be designed to meet this
requirement. The incinerator and groundwater
pump and treat system would also be designed
to  meet  all  action-  and  chemical-specific
ARARs.

The objective of Alternatives 2 through 4 would
be to meet  chemical-specific ARARs  for
groundwater (for example,  MCLs,  MCLGs,
state groundwater enforcement standards) at the
landfill boundary.   For these standards to be
maintained (once they are achieved),  the leach-
ate collection system (perimeter wells) and the
landfill cap would have to be maintained.

The no-action alternative  would not  be in
compliance with ARARs.

6.3.3  Short-Term Effectiveness

Effects  on  the community during remedial
actions are related to the degree of truck traffic
needed to import cap materials and the amount
of earth  moved during cap  construction. The
truck traffic of Alternative 3  (composite-barrier
cap) is anticipated to be  slightly greater than
Alternatives 2 and  4, and significantly greater
than the  no-action alternative. The truck traffic
would cause nuisances from noise and dust and
increase  the risk of vehicular  accidents.

Adverse  health effects on the community may
be increased by Alternative 4 (treatment of hot
spot) as  a result of waste disturbance  and the
possibility of improper air  emissions from incin-
erator   malfunctions or   poor  destruction
efficiency. Although  air emission controls and
                                              6-12

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monitoring can limit risk from incinerator air
emissions, it would be more difficult to control
VOC releases as a  result of disturbing the
waste. The rural nature of the site should make
the effects negligible.

Adverse health effects on workers during cap
construction  and  groundwater  remediation
construction are not expected to be significant.
Incineration of soils  in the hot spot (Alterna-
tive 4) may pose  a greater risk to workers than
consolidation of the hot spot under the landfill
cap (Alternatives 2 and 3). Alternatives  2, 3,
and 4 all involve excavation of the hot  spot,
which may pose risks to workers from  potential
VOC emissions. However, since the hot spot is
generally within the landfill, consolidation
(Alternatives 2 and 3) may  involve only a small
amount of excavation to minimize the size of
the landfill cap, whereas excavation and inciner-
ation (Alternative 4) would involve excavation
of the entire hot  spot area and may result in a
greater risk from  VOC emissions. Alternative 4
may also result in greater risk of construction
injuries  from assembly of the materials  handling
and  incinerator  system, and excavation  and
consolidation of surface  water  sediments.
Compared to the  no-action alternative,  all  three
alternatives have a significant increase in risk to
workers.

Environmental impacts for Alternatives  2, 3,
and 4 do not differ  significantly.  There  is a
possibility of waste  or runoff affecting  the Polk
River   during   implementation of  these
alternatives.

The time required for implementation of source
controls is the only  time" variation between
Alternatives 2, 3, and 4. Design and construc-
tion   would   require  from  2   years   for
Alternatives 2 and 3 (consolidate hot spot and
cap) to 4 years for Alternative 4 (incinerate hot
spot  and cap).

6.3.4  Long-Term  Effectiveness

All alternatives leave the landfill in place and
rely  on institutional controls,  such  as  state
prohibition  of construction on  landfills, to
prevent development.  If the landfill is devel-
oped, hazardous  materials could be deposited
on the  surface from  earth-moving activities
(grading or excavation), resulting in exposure to
users of the site or transport of contaminants to
the unnamed, tributary  of the Polk River.
Assuming regular cap maintenance, Alternatives
2, 3, and  4 are  roughly equivalent in,  their
ability to prevent direct contact and erosion.

The amount of residuals is typically gauged by
the contaminant mass that would reach the
groundwater. While this is difficult  to estimate,
the effect of the residuals  is related to the infil-
tration  rate  and the  remaining contaminant
mass. Alternative 4 removes and treats the" hot
spot, thereby removing a  significant portion of
the contaminant mass. Alternative 3  uses  a
composite-barrier cap, which  would  reduce
infiltration  more effectively  than  the  single-
barrier clay cap proposed for Alternatives 2 and
4.  It is estimated that infiltration could be
reduced by as much  as 75  percent by using a
composite-barrier cap instead of a single-barrier
clay cap.   Alternatives 2, 3, and 4 all offer a
significant  effectiveness advantage over the no-
action alternative.

The composite-barrier cap is more reliable than
a clay cap because of the extra barrier. Main-
taining the long-term reliability and effective-
ness of both types of caps would require con-
tinued operations and maintenance.  Incinera-
tion of  the  hot  spot by  Alternative  4  may
reduce  the critical need of  maintaining  cap
reliability by reducing the source of contamina-
tion.

6.3.5  Reduction  of  Toxicity,  Mobility,  and
Volume Through Treatment

All of  the  alternatives, except the no-action
alternative, have groundwater treatment.  The
reduction in toxicity, mobility, or volume from
groundwater treatment would be the same for
Alternatives 2, 3, and 4.  The only significant
difference  concerning treatment is the use of
incineration in Alternative 4.  Compared to the
landfilled  material,  the amount of hazardous
material treated  is not estimated to be large.
Yet,  because the treated  area represents the
most contaminated material, the toxicity of the
remaining  material  would be significantly
reduced.    Incineration is a permanent,  non-
reversible treatment process.
                                              6-13

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6.3.6  Implementability

While Alternatives 2, 3, and 4 have no serious
implementability issues, there  are differences
between the alternatives.   The synthetic  liner
for Alternative 3  requires  special  handling
during  installation to  ensure  integrity.  The
incinerator for Alternative  4 may take some
effort to locate. Trial burns will then be neces-
sary.  Considerable operating attention will be
required because of the heterogeneous nature
of the waste.  In addition, the technical intent
of relevant emission permits will have to be met
and  demonstrated before the incinerator  can
operate.

6.3.7  Costs

The costs of the  alternatives  increase incre-
mentally from no-action to Alternative 4. The
relative  costs  of the alternatives  are  shown in
Table 6-1.
      6.4  Section  6  Summary

This section has been developed to illustrate
how the evaluation process, is applied to a typi-
cal  CERCLA municipal landfill site.  The  previ-
ous sections focused primarily on technologies
that are most practicable for landfill  sites. This
section  demonstrates how these technologies
might be combined into  alternative and
evaluated.
                                               6-14

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                                    Section  7
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 U.S.  Environmental Protection  Agency.  State  of Technology Review:  Soil  Vapor
Extraction  Systems.  EPA/600/2-89/024.  1989h.

 U.S.  Fish and Wildlife  Service et  al. Federal  Manual  for  Identifying  and Delineating
Jurisdictional  Wetlands:  An Interagency  Cooperative  Publication.  1989.

 U.S.  Geological  Survey.  Application of Drilling, Coring,  and Sampling Techniques to
 Test Holes and Wells, Techniques  of Water-Resource Investigations  of the  United States
 Geological Survey.  U.S. Department  of the  Interior.

 U.S.  Geological  Survey.  WATSTORE  files.

 U.S.  Steel  Corporation.   Steel  Sheet Piling  Handbook: Reference Data  on Shapes
Materials, Performance  and Applications.  Pittsburgh:  United  States  Steel.  1976.
                                         7-8

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Viessman  et  al.  Introduction  to  Hydrology. New  York: Harper  and Row.  1977.

Warner, R.C.  et  al.  Demonstration and Evaluation  of the Hydrologic Effectiveness of a
Three-Layer  Landfill Surface Cover  under Stable  and  Subsidence  Conditions: Phase I
Final Project Report. U.S. Environmental  Protection Agency.

Xanthakos, P. Slurry  Walls. New York:  McGraw-Hill.  1979.
                                         7-9

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                Appendix A

Site Characterization Strategy
         for an Example Site

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CONTENTS OF APPENDIX

                                                                     Page

1.     INTRODUCTION	Al-3

2.     EVALUATION OF EXISTING DATA	A2-1

      2.1    Site Description	A2-1
      2.2    Site History	A2-1
      2.3    Regional and Site-Specific Geology	A2-3
            2.3.1 Regional  Geology	A2-3
            2.3.2  Site-Specific  Geology	A2-4
      2.4    Hydrology	A2-4
            2.4.1 Surface Water	A2-4
            2.4.2 Groundwater	A2-4
            2.4.3 Surface Water-Groundwater Relationship	A2-4
      2.5    Hazardous Materials Characterization	A2-6
            2.5.1 Source Description	A2-6
            2.5.2 Waste Description	A2-6
      2.6    Cap Characterization	A2-6
      2.7    Description and Results of Past Sampling and
            Analysis Activities	A2-7

3.     SITE DYNAMICS	A3-1

      3.1    Limited Field Investigation	A3-1
      3.2    Conceptual Site Model	A3-1
      3.3    Preliminary Exposure Assessment	A3-7
            3.3.1 Chemicals Previously Detected at the Site	A3-7
            3.3.2 Contaminant Source	  A3-7
            3.3.3 Release Mechanism	A3-7
            3.3.4 Contaminant Transport	A3-7
            3.3.5 Contaminant Migration	A3-8
            3.3.6 Contaminant Fate	A3-8
            3.3.7 Exposure Pathways	A3-8

4.     PRELIMINARY IDENTIFICATION OF REMEDIAL ACTION
        ALTERNATIVES	A4-1

      4.1    Potential ARARs for the Example Site	A4-1
      4.2    Review of Analytical Results and Comparison to ARARs	A4-2
            4.2.1 Baseline Risk Assessment	A4-2
      4.3    Preliminary Remedial Action Objectives and Goals	A4-8
                                    Al-1

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CONTENTS (cont.)
                                                                     Page

      4.4    Preliminary Remedial  Action Alternatives 	 A4-8
            4.4.1   Landfill  Contents	  A4-9
            4.4.2   Hot   Spots   	  A4-9
            4.4.3    Groundwater   	,	A4-10
            4.4.4   Landfill  Gas  	,	A4-11
            4.4.5   Surface  Water  and  Sediments  	 A4-11

5.     REMEDIAL  INVESTIGATION AND FEASIBILITY
      STUDY  OBJECTIVES	 A5-1

6.     DATA  QUALITY  OBJECTIVES  	 A6-I

7.     RI/FS  TASKS  	  	 A7-1

      7.1    RI/FS   Tasks	  A7-1
            7.1.1   Task  l--Project  Planning  	A7-1
            7.1.2 Task 2~Community Relations Activities  	A7-2
            7.1.3   Task  3~Field Investigation   	A7-2
            7.1.4 Task 4-Sample Analysis and Data  Validation	A7-21
            7.1.5   Task  5--Data  Evaluation  	 A7-25
            7.1.6   Task  6~Risk  Assessment 	 A7-25
            7.1.7  Task  7~Remedial Investigation  Report  	A7-25
            7.1.8 Task S--Remedial Action Alternative Report	A7-25
            7.1.9 Task 9—Alternatives  Evaluation 	 	A7-26
            7.1.10  Task lO-Feasibility  Study Report 	 A7-26
            7.1.11  Task  1 l--Treatability  Studies	 A7-27

8.     COST  AND  KEY  ASSUMPTIONS  	 AS-1

9.     SCHEDULE     .. 	 	 A9-1

10.    PROJECT   MANAGEMENT,    	  A10-1

11.    BIBLIOGRAPHY    	All-1
                                   Al-2

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                                         Section 1
                                  INTRODUCTION
This appendix has been developed to illustrate
how information provided in the body of this
report-specifically, in Sections 2, 3, and 4 of
Conducting Remedial  Investigations/Feasibility
Studies for CERCLA Municipal Landfill Sites—
could be used to develop a scope of work for a
specific landfill site. The example provided in
this appendix should be useful to EPA, states,
potentially responsible parties  (PRPs), and
remedial investigation  contractors.

Specifically, the purpose of this appendix is:

  •   To  present the scope of work to be com-
      pleted at an example site including a site
      description, objectives of the RI/FS, and
      task-by-task breakdowns of the planned
      work

  •   To  illustrate an  example of the level of
      characterization for a CERCLA munici-
      pal landfill site necessary to support
      subsequent decisions (This  level of char-
      acterization is based on previous  experi-
      ence and best engineering judgment.)

  •   To  identify preliminary remedial action
      alternatives that are practicable for the
      example landfill site based on the NCP
      expectations, site conditions, and review
      of remedial alternatives most often used
      at landfill  sites  (see Section 4 of this
      report on Development and Selection of
      Remedial  Action Alternatives.)

This RI/FS characterization strategy  is devel-
oped for a specific municipal landfill site, here.
after referred to as the example site. This docu-
ment will focus on hot spots, seeps, landfill gas,
and groundwater/leachate as the principal  media
of concern. These were selected  because they
are generally the media directly associated with
municipal landfills.  By focusing on these four
media, the example scope of work can be less
complicated and applied to other media. The
omission of other potentially affected media,
such as  wetlands, in this example does not
imply that they should be omitted from
investigation and remediation at sites where
they are  present.

The example site used for preparing this work
plan is described in detail in Section 2 of this
appendix.    In order  to  present technically
supportable conditions for  the example site, the
geology  and hydrology used were taken from
the work plan of an actual municipal  landfill
site located in the State of Wisconsin. Some of
the characteristic, such as  the names of the
river basins, rivers, and distances to hydrologic
features, have been changed.  In  addition,  an
assumption has been made that the RI/FS at
the example site is federally funded.

This appendix begins with a description of the
example site and its history. It then presents
the decisions made from evaluating existing
data, conducting limited field investigations, and
developing data quality objectives. Future tasks
required for conducting the RI/FS are described
next. These tasks  follow the standardized RI/FS
tasks described in Appendix B of the RI/FS
Guidance (U.S. EPA, 1988a).

The example site is a municipal landfill that is
located in a primarily rural area of County X,
Wisconsin. The site was proposed for the NPL
in 1982 after site inspection and HRS scoring
by  an  EPA Field Investigation  Team (FIT).
Investigation by FIT indicated elevated levels of
volatile organic compounds (VOCs) and  metals
in groundwater samples taken  from nearby
residential wells.
                                            Al-3

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The overall goals of the RI/FS for the example             environmental risks  associated with
site are                                               contaminants found at the site

  •   To complete a field program at the site         •   To develop and evaluate remedial alter-
      for collecting data to determine the             natives for the site if there are unaecept-
      nature and extent of contamination  at             able human health or environmental
      the site  and the human health  and             risks
                                           Al-4

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                                        Section 2
                   EVALUATION  OF EXISTING DATA
This section presents a summary of the avail-
able information on the example site. Informa-
tion was obtained from the HRS package, state
files,  interviews with past employees of the
landfill,  records kept by the landfill,  and
available engineers' reports for closure of the
landfill. This section includes the  following
subsections:

  . Site  Description
  .Site  History
  .Regional and Site-Specific  Geology
  .Hydrology
  .Hazardous  Materials  Characterization
  .Cap Characterization
  .Description  and Results of Past Sampling
    and Analysis Activities
         2.1 Site Description

The  example  site,  shown  in Figure 2-1,  is
approximately  60  acres  and is located  in
County X, Wisconsin, an area that is primarily
rural. There are six residences located within
one-half mile of the site and a community  of
300 people is located 5 miles northwest of the
landfill. The primary use of the land near the
site is farming.

Approximately  20 acres of the 60-acre site are
composed of a landfill which accepted both
chemical wastes and municipal trash. Existing
structures on the site include a gate house and
an office. There is  a small tributary running
within 200 feet west of the site which discharges
into  the  Polk  River.   Private drinking water
wells, screened within a sand and gravel aquifer,
are located downgradient of the  site.  The
landfill was closed by the state in 1980 when
contamination was  found  in  these residential
wells.

Industrial, commercial,  and municipal  wastes
are generally mixed throughout  the  fill area,
with the  exception of liquid industrial solvent
wastes which were  generally restricted to the
southeastern half of the landfill. Between 1980
and 1982, exposed areas in the southern half of
the landfill were temporarily covered  with  a
partial cap consisting of 2  feet of compacted
clay.   The remainder of the landfill has  a
temporary soil cover although there are some
areas  of exposed waste. Some of the contami-
nants  of concern are trichloroethene (TCE) and
vinyl chloride (VC) in the soil and groundwater;
lead,  arsenic, and total chromium in the soil
and methane gas.
           2.2 Site History

A summary of  the  landfill's  history  was
formulated after reviewing relevant site records
and correspondence for information regarding
site operations, waste  disposal practices, waste
descriptions, site engineering studies,  historical
aerial photographs, and potentially responsible
party operations.  A condensed version of the
site history follows.

The  landfill, which is privately  owned, was
licensed by  the State  of Wisconsin to operate
from 1969 to 1980, when the state ordered its
closure. State tiles  indicate that  in  1969 the
landfill began operations, receiving residential,
commercial,  and  industrial refuse and liquid
wastes. In 1971, the state required that an area
be designated specifically for the disposal of
liquid  industrial solvents.  Interviews  with site
operators indicated that the solvents were
disposed of in the southeastern portion of the
landfill to  satisfy  the state's requirements;
however, disposal was generally done through-
out the landfill prior  to this  time.   Landfill
operations during the first three years  of opera-
tion were conducted  without an attendant.
Thereafter, operating hours were posted and an
operator was present to record incoming waste
and to measure the nonresidential waste for
record-keeping and billing purposes.

Daily  landfill operation  records indicate that
two major industrial companies began solvent
waste disposal in 1970. The solvent wastes were
                                            A2-1

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                                                    BURIED
                                                    DRUMS
                                                    AREA
                                  GATE  x
                                  HOUSED
                                      _JD
J
                              R-3
LEGEND

    RESIDENTIAL WELLS

    MONITORING WELLS
                                   A2-2
                                                        Figure 2-1
                                                        SITE PLAN
                                                        EXAMPLE SITE

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stored in 55-gallon drums, which were left or
buried at the site  if they were  damaged or
leaking or could not be easily emptied. A large
number of drums were also buried in the  south-
eastern portion of the landfill.

In 1971, the site began receiving paint, paint
thinners,  paint residues, lacquers, plating
sludges, and industrial process sludges. In 1975,
a Consent Order issued by the County Circuit
Court prohibited  the disposal  of  these
materials.

In 1979, the state sampled  nearby  domestic
wells for  compliance  with drinking  water
standards.   The investigations indicated  that
groundwater contamination had occurred and as
a result  the  landfill was ordered to stop its
operation in  1980.   Between 1980 and 1981,
closure  plans were prepared by  a contractor
hired by the owner. Wells, shown by Figure
2-1,  were  drilled  to the base of the landfill
content to provide data for the closure scenar-
ios. In 1981, a partial cap,  consisting of 2 feet
of compacted clay, was placed over the  south-
eastern half of the landfill to cover major areas
of exposed wastes  and  the liquid solvent dis-
posal area. The remaining portion of the land-
fill previously had been covered with soil from
an unknown source.

Investigations by FIT in 1986 indicated elevated
levels of volatile organic compounds (VOCs)
and metals in groundwater samples taken from
nearby residential wells.   Elevated levels of
methane gas were  also found.    To date the
primary contaminants of concern have been 1,1-
dichloroethene   (1,1-DCE),   cis-l,2-dichloro-
ethene (cis-l,2-DCE), tetrachloroethene (PCE),
1,1,1-trichloroethane  (1,1,1-TCA),  trichloro-
ethene (TCE),  vinyl  chloride (VC), toluene,
ethylbenzene,   bis(2-e/h)phthalate,   poly-
chlorinated biphenyls (PBCs), lead, arsenic, and
total chromium.

This appendix outlines the technical approach
and associated activities to complete the RI/FS
for the site. It is based on data gathered by the
state and by FIT. These data were analyzed to
develop  the  conceptual site model, identify
additional data needs, and determine the scope
of the RI/FS activities. The site received a
Hazard Ranking Score of 30.0 which exceeded
the 28.5 scoring and therefore was high enough
to be proposed for the NPL.

Limited field investigations were conducted by
the remedial contractor in 1988 to provide data
needed to fully scope the RI. Detailed discus-
sions of these investigations are in Section 3.
  2.3 Regional and Site-Specific
                 Geology

The following sections describe the regional and
site-specific geology of the area.

2.3.1 Regional Geology

The example site lies within the lower valley of
the James  River Basin, which was  a major
glacial drainage way across the "driftless area" to
the Mississippi River.   Consequently, the site
contains thick deposits  of  unpitted  outwash
comprising of stratified sand and gravel to an
estimated depth of 135  feet.  Bedrock in  the
James River Basin  consists mainly  of  sedi-
mentary rock of Cambrian and Ordovician ages.
Sandstone is predominant, but the Prairie du
Chien Group  and Galena-Platteville units  are
primarily dolomite and limestone, respectively.
The   greatest thickness of  Cambrian  and
Ordovician  rock, approximately  1,700  feet,
occurs in the  southern tip of the basin where
the youngest  bedrock  formations cap  high
ridges.  The Cambrian sandstone has a broad
outcrop area because it is nearly flat lying and
has been exposed by erosion as indicated by
Soil Conservation data for this  county.

Igneous and metamorphic crystalline rocks of
Precambrian age form the basement and are the
bedrock surface  in  the  northern  part of  the
basin.

Erosion of the sandstone and dolomite bedrock
has  occurred in  this  unglaciated  region
throughout geologic time. The erosion has  cut
numerous deep valleys  into what was once a
fairly level plateau forming a dissected upland
with steep relief.  In some parts of the county,
the difference in  elevation between the valley
bottoms and the adjacent ridge tops is as much
as 500 feet.
                                             A2-3

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2.3.2 Site-Specific Geology

The soil underlying the example site belongs to
the Plainfield series, which consists of fine to
loamy fine sand, that are prevalent on alluvial
terraces. This soil exhibits excessive  drainage
and is easily eroded by the wind.

The. unconsolidated  deposits at the site are
approximately 135 feet thick  and consist pri-
marily of sand and gravel of glaciofluvial and
alluvial origin,   The  site is located within an
eroded  bedrock valley that was filled with
outwash transported  by the James and Polk
Rivers near the end  of the Wisconsin Stage
Glaciation.  Atterberg  limit  tests were  per-
formed by the closure contractor on the surface
silt and  clay and results indicate that these
strata are nonplastic. The hydraulic conductiv-
ity of the silt and clay was estimated to range
from  1  x 10"3to 1 x 10"' cm/sec  (Contractor,
1979). The other strata observed  at the site
consists predominantly  of very  fine to  coarse
sand with trace amounts of gravel, silt,  and clay.
The hydraulic conductivity  of this strata was
estimated to range from 1 x 10"2to 1 x 10"3
cm/sec (Contractor, 1979).

Bedrock in the vicinity of the site consists of
undifferentiated Cambrian  sandstone  up to
1,200  feet thick. This  undifferentiated sand-
stone includes  the St.  Lawrence  Formation,
Jordan, Franconia, Galesville, Eau  Claire, and
Mount  Simon Sandstones.  These  Sandstones
are fine to coarse-grained and contain a small
amount of shale.

Bedrock was encountered at a depth of 134 feet
in a residential well south of the  site.
             2.4 Hydrology

The location of the  landfill in relation to  the
Polk River is critical  in understanding  the
surface water-groundwater flow regime at  the
site.

2.4.1 Surface Water

The Polk River flows south-southwesterly to
within  600 feet of the site.   Art unnamed
tributary to the Polk River flows within 200 feet
west of the site (Figure 2-1). As the river flows
past the site, its channel branches  into channels
that are  tributaries to the James River.  The
main  channel of the James River flows south-
east within 2 miles of the site. The James River
is dammed approximately 4 miles south of the
site, forming Lake Ohio (Figure 2-2). A leach-
ate  seep has been identified that flows from the
western position of the toe of the landfill to the
unnamed tributary of the Polk River.

2.4.2 Groundwater

Groundwater flow directions were determined
on the basis of water levels at nearby  residential
wells completed in the unconsolidated deposits
of sand and gravel, and one existing monitoring
well nest completed to the base of the landfill.
These water  levels    have been  measured
quarterly since 1979. Horizontal groundwater
flow is to the south-southwest for the majority
of the year. However, during the  spring runoff
period the flow  is altered, and  groundwater
flows to the south-southeast  away from  the
river.

The horizontal groundwater gradient,  calculated
from  available quarterly data during  the period
1979 to  1986, ranged  from 2.2 x 10'3to 2.2 x
10"4and  averaged 5.3  x 10"4,  remaining rela-
tively flat  throughout the year. This variation
in horizontal groundwater gradients  is a result
of  seasonal variation  associated with spring
runoff.   Vertical groundwater  gradients mea-
sured  during  the investigation  indicate that
there is a slight downward gradient of 1 x 10"2.

2.4.3  Surface Water-Groundwater Relationship

A review of the measurements  of groundwater
level  indicates that the  direction of groundwater
flow displays variation. The groundwater flow
regime at the site is predicated  on the seasonal
surface  water  fluctuations  in the  Polk and
James Rivers. These fluctuations are directly
related to the Polk River and Lake Ohio, which
either recharges the adjacent sand-and-gravel
aquifer or receive groundwater discharge as the
river  and lake levels  fluctuate.   During  the
majority  of the year, groundwater is discharging
to  the river, however, during spring  runoff,
when surface  water levels are high, the river
recharges the sand-and-gravel  aquifer.   This
                                             A2-4

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                                    UNNAMED TRIBUTARY
Scale:
1"=5280ft.=
mile
figure 2.2
SURFAC E WATER FOR
EXAMPL E SITE
                         A2-5

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modifies the direction of groundwater flow, from
the south-southwest  to the  south-southeast,
away from  the  river.
     2.5 Hazardous  Materials
           Characterization

Since landfill operations began, the  20-acre
landfill  had received a variety  of municipal,
commercial, and industrial wastes.    Landfill
records  (gate slips) kept  by the operators
identified the waste haulers, indicated whether
or not the delivery was a municipal or industrial
waste, and listed the approximate quantities
deposited. The gate slips did not provide waste
descriptions nor did they include deliveries that
occurred outside  of the landfill operating hours,
Consequently,  a complete inventory  of  the
wastes disposed of at the landfill is not avail-
able. Other records, however, from the county,
the state, EPA, and past employees of the land-
fill were used to develop  a partial list of the
waste deposited at the landfill. Waste disposed
at the site consisted primarily of solid waste,
including paint  cans, bottles, plastic, paper,
degreasers, and other commercial and municipal
garbage. The wastes of concern generally con-
sisted of chlorinated and nonchlorinated organ-
ics, water-based and oil-based  paints, paint
thinners and lacquers, waste oil, automobile and
household batteries, and industrial   process
sludges.

Available records show no indication of segre-
gation of wastes.   Industrial, commercial and
municipal wastes are generally mixed through-
out the fill area except for liquid industrial
solvent wastes.    In  1971, the state restricted
disposal of the liquid industrial waste to  the
southern portion of the landfill.  The  wastes
were generally buried as soon as it was received
and the  cover material compacted.

2.5.1 Source Description

Records indicate that a  nearby  electroplate
contributed  the  greatest  quantities of liquid
wastes,  consisting primarily of naphtha-based
solvents used in  the metal-cleaning process  and
wastes  from paint  spray  and machine shop
cleaning fluids.   Paint residues and  solvents
were also delivered to the landfill in 55-gallon
drums. These drums were buried intact at the
site if the drums could not be easily emptied or
if they were damaged or leaking. A large  por-
tion of the drums were buried in the southeast
portion  of the  landfill.   There  are no  other
known industrial liquid wastes at the site.

2.5.2 Waste Description

Review of existing records suggests that various
industrial process sludges brought to the facility
may have contained high concentrations of inor-
ganics such as  chromium,  arsenic, and lead.
Review of existing records  also suggests that
waste solvents also were brought to  the  site.
Waste solvents consisted primarily of naptha,
toluene,  ethanol,  and  paint  residues.  The
naphtha-based solvents were primarily mineral
spirits, which are the  least volatile of the
napthas.  Mineral spirits are a watery, colorless
liquid with a gasoline-like odor. Their compo-
nents are slightly  soluble in water.  Records
indicate  that  waste  ethanol (ethyl  alcohol)
brought to the site had previously been used as
a solvent for resins, oils,  hydrocarbons, surface
castings, and cleaning preparations. Ethanol is
a colorless, volatile liquid with a pungent taste.
It has an ethereal,  wine-like odor and is
miscible in water.

The records  also suggest  that the solvent
components of the paint wastes include high-
flash petroleum and toluene.  Toluene  is  a
methylbenzene  (C7H8),  which is  a colorless,
mobile liquid with a distinct aromatic odor and
is immiscible in water.
     2.6 Cap Characterization

In 1980, the state ordered the landfill closed.
The owner then hired a contractor to prepare a
closure plan for the landfill.  In early  1981,
closure investigations indicated that a partial
cap was required over the southern portion of
the landfill where the industrial liquid solvent
wastes were buried and where there were areas
of exposed wastes.   In 1982, the owner sub-
mitted a closure plan to the state indicating that
a cap, consisting of 2 feet of compacted clay
with 6 inches of topsoil, was to be placed over
the  southern  portion  of the  landfill.  The
remaining portion of  the landfill  had  been
                                             A2-6

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previously covered with soil from an unknown
source (Figure 2-3).

As-built or final grading plans for the clay cap
are not known to be available. The existing cap
was visually observed for cracking and erosion
during an inspection that was performed during
the site visit. There  were no major signs of
cracking  or  failure of the existing clay cap,
however,  there  was some minor sideslope
erosion.
  2.7 Description and Results of
         Past Sampling and
          Analysis Activities

Organic  and inorganic data, shown in Table 2-1
(well locations shown in Figure 2-1), are avail-
able for five residential wells near the site and
two onsite monitoring wells installed by the
owner of the landfill for closure investigations
in 1981. All wells are completed in the uncon-
solidated deposits of sand and gravel.  Based on
drillers logs, the five residential wells range in
depth from 45 to 58 feet and are completed as
open-end steel pipes.  Monitoring well GWIS
has an open interval from 36 to 46  feet and
GWID has an open interval from 62 to 72 feet.
Both monitoring wells are PVC with the open
interval being slotted PVC.

The site has a variety of organic contaminants
in the groundwater and soil that appear on the
Target Compound  List (TCL) and the Target
Analyte List (TAL),  including VOCs such as
TCE and VC; semivolatile organic compounds
such as  bis(2-e/h)phthalate  and  phenol,  and
metals such as lead, arsenic, and chromium.
VOC concentrations were highest at the south-
east  corner of the landfill.  Methane gas was
detected  at  concentrations  above  the  lower
explosive limit at the eastern end of the landfill.
Low levels of VOCs were found in all of the
residential wells. These wells are all located to
the south of the site.

Sampling of the seven wells was conducted by
the contractor hired by  the  owner and the
analysis was done by a private laboratory not
participating in  the  Contract Laboratory
Program.    The  QA/QC procedures of the
sampling and analysis are  not readily available.
Sample   analysis   methodologies   were
inappropriate  for some contaminants;  the
detection limit for  VC in groundwater was
above the maximum contaminant level (MCL)
of 2 ppb. Therefore, conclusions with regard to
health risks for this contaminant  cannot be
made because the choice of analytical methods
and  reliability of the  groundwater data are
suspect. For purposes of this work plan, the
above data will be used  only for project
planning  and   to identify  preliminary
remediation goals.

Only limited conclusions can be drawn from the
existing data. The full areal and vertical extent
of groundwater contamination can not be deter-
mined because all of the wells sampled showed
VOC contamination. Well R-5, however, did
not show exceedances of primary MCLs. The
depth  of  contamination, and the extent of
contaminant migration to the south and west of
the site have not been determined. Upgradient
concentrations are also unknown.  These data
gaps need to be filled in the RI.
                                            A2-7

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                                         SOIL COVER
                                                    BURIED
                                                    DRUMS
                                                    AREA
                              R-3
LEGEND
R-41
                                                                     y
                                                                      A
    RESIDENTIAL WELLS
                                   A2-8
                                             Figure 2-3
                                             LOCATION OF EXISTING CAP
                                             EXAMPLE SITE

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Table 2-1
SUMMARY OF GROUNDWATER SAMPLING AND ANALYTICAL RESULTS3
(us/1)
Contaminant
1,1-DCE
cis-l,2-DCE
PCE
1,1,1-TCEA
TCE
V C
Toluene
Ethylbenzene
bis(2-e/h)phthalate
Lead
Arsenic
Total Chromium
Residential Wells
(R-l)
2.0
11.0
2.6
36.0
72.0
<5.0
1,100
700
820
17.3

7.0
(R-2)
2.0
13.0
3.3
36.0
120.0
<5.0
980
850
640
<1.0
2.9
17.0
(R-3)
9.9
17.0
33.5
90.0
100.0
5.1
1,020
920
580
1.3b
<4.0
27.0
(R-4)
3.2
15.0
3.9
5.5
100.0
5.3
640
200
120
<1.9
2.7
<5.0
(R-5)
<5
NA
<5
<5.0
2.3J
<5.0
400
200
45
NA
3.2
<5.0
Onsite Wells
(GWIS)
8.5
16.0
28.9
85.0
110.0
5.5
5,000
10,500
980
16.5
NA
25.1
(GWID)
4.5
10.0
18.6
40.0
75.0
4.2
1,500
500
780
14.0
3.2
18.2
"Samples were collected in January 1981 as part of a closure investigation conducted
by the contractor hired by the owner.
bEstimated value.
A2-9

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                                         Section 3
                                  SITE DYNAMICS
Understanding the dynamics between the site
and its environs including potential receptors, is
essential to  succesfully scoping  the  RI/FS.
This section discusses the limited field activities
conducted  during development of this work
plan to better understand the site dynamics;  the
conceptual  site  model describing the site's
dynamics; and the preliminary remediation goals
that have been developed  as a result of this
information.
  3.1 Limited Field Investigation

Insufficient data were  available to adequately
define the dynamics at the site and, hence, to
develop the conceptual site model and design
the RI program.    Therefore, a limited  field
investigation was performed to collect data to
further determine the  RI scope.  Prior to the
limited  field investigation, a  site visit was
conducted. The general features of the landfill
were observed and documented. The perimeter
of the landfill itself was identified, along with
access and egress to and  from the site. Nearby
residents  were interviewed and  photographs
were taken.   During  the  site  visit,  data  on
VOCs, radioactivity, and explosivity hazards
were obtained using field analytical equipment
(the HNu, radiation  meter, and explosimeter) to
determine appropriate health and safety levels.
Site conditions differing from those reported in
existing reports were also documented.

A summary of the  limited field investigation
objectives, activities, and results are shown by
Table 3-1. The limited field investigation was
conducted for several reasons. The site bound-
aries were not defined and maps of the site
were not available.  Reports indicate that  there
are seven onsite wells.  Two of the existing
wells, GWIS and GWID, were located during
the site visit. The other five wells could either
not be  located  during the site  visit or the
limited field investigation or were unusable.
The viable well nest (GWIS and  GWID)
penetrates through the landfill contents.
In-situ  hydraulic  conductivity tests were
conducted by the RI contractor in May, 1988,
on  three  (RI,  R2,  and  R3)  of  the  five
residential  wells and the one onsite  well  nest
(Figure 2-1).   Based on the results of these
tests, the hydraulic conductivity of this sand-
and-gravel aquifer ranges from 9.8 x 103 cm/sec
to 2.1 x 10"1 cm/sec with a geometric mean of
7.4 x 10"2cm/sec. Table 3-2 summarizes results
of the in-situ hydraulic conductivity testing. In
general, this aquifer is very transmissive. This
information aids in the placement of the  new
monitoring  wells   and  provides  an early
indication of Contaminant migration.

Water level measurements were taken from the
nearby residential and onsite wells.  The water
level at the onsite well was slightly higher than
the other wells,  indicating a  possible local
groundwater mound.
    3.2 Conceptual Site  Model

Figure  3-1  summarizes the  conceptual  site
model for the example site. The  entire landfill
will be considered  as  the source of the con-
taminants; however, disposal records indicate
that high levels of VOCs are present in the
waste disposed of primarily in the southeastern
corner (solvent drums and liquid solvents) of
the landfill.

Table 3-3 shows the preliminary exposure  path-
ways  under  current and future use at the site.
Organics and inorganics are released from the
landfill to the groundwater by leaching caused
by  compression  and/or by percolation. The
contaminated groundwater is used as an offsite
water supply source.  Leachate discharges via
seeps to the small tributary of the Polk River.
Landfill gas present at the landfill can migrate
and pose on-  and offsite fire and explosion
hazards. Landfill gas can also  become soluble
in groundwater.
                                            A3-1

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Table 3-1
LIMITED FIELD INVESTIGATION OBJECTIVES FOR
THE EXAMPLE SITE
Page 1 of 2
Activity
General
Investigation
Objectives
Delineate site boundaries,
estimate uncertainties in
boundaries.
Evaluate present site
conditions.
Locate existing
monitoring wells.
Evaluate site drainage
patterns.
Locate preliminary loca-
tions for new monitoring
wells.
Locate surface waters,
wetlands, sensitive
environments.
Evaluate site-capping
conditions and surface
water drainage.
Initiate measurement of
landfill settlement rate.
Site preliminary locations
for trailer, decon pad, and
secured storage area.
Evaluate site access to
water, utilities, and
telephone.
Action
Conduct property survey or
identify property ownership
from tax records.
Visually inspect site for gas/
fire/explosion damage, run-
off pathways, leachate
seeps, exposed wastes, cover
conditions, access concerns.
Perform a topographic
survey and location and
elevation survey of existing
monitoring wells.
Perform a topographic
survey.
Perform a topographic
survey.
Conduct site visit.
Perform visual surface
inspection with topographic
maps.
Install benchmarks.
Conduct site visit.
Conduct site visit.
Results
Site boundaries defined.
No evidence of gas/fire/
explosion damage was
observed. Several areas of
exposed wastes are present.
Additionally, leachate seepage
from the side of the landfill
was observed. Runoff
pathways to the unnamed
tributary of the Polk River
were located.
Two of the seven existing
onsite wells were located.
Site drainage patterns were
defined.
Preliminary locations of new
monitoring wells were
determined.
An unnamed tributary of the
Polk River flows within 200 ft
of the west side of the landfill.
Capping and drainage appeared
to be in fair condition with
minor sideslope erosion.
Leachate was observed seeping
from the side of landfill.
Benchmarks installed; quarterly
readings will be taken.
Locations were identified.
Water may be available near
the site from an upgradient
well; if not, water will need to
be trucked to the site. Also, a
utility pole arid a telephone
line are needed.
A3-2

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                                                Table 3-1
                         LIMITED FIELD INVESTIGATION OBJECTIVES FOR
                                          THE EXAMPLE SITE
                                                                                             Page 2 of 2
    Activity
        Objectives
          Action
            Results
Geotechnical
Investigation
Describe geologic
features, classify soil.
Conduct visual observation
of mechanical erosion,
slope instability, and
pending caused by
subsidences and cracking.
Minor sideslope erosion of the
 cap was observed.
Hydrogeologic
Investigation
Evaluate usefulness of
existing monitoring well
network.
Determine accessibility  of
existing wells.
                                             Determine, by sounding to
                                             the bottom of the well, if
                                             existing wells are
                                             obstructed.
 Five of the seven wells could
 not be found; however, one
 well nest was located.

 Of the two wells located, both
 were judged suitable for future
 sampling.
                  Review preliminary
                  locations for new
                  monitoring wells.
                            Review topographic map
                            and conduct site survey.
                             Preliminary locations for new
                             monitoring wells were
                             observed.
                  Conduct well inventory:
                  determine  local
                  groundwater uses and
                  construction of wells.
                          Perform well survey for all
                           wells (residential, com-
                           mercial, industrial), adjacent
                           to, and downgradient from,
                           the landfill. Obtain
                           permission for use.
                             The majority of the residential
                             wells are in use and
                             information regarding their
                             construction exists. There were
                             no commercial or industrial
                             wells identified.
                  Confirm direction of
                  groundwater flow and
                  estimate gradients.
                            Record water level
                            measurements from existing
                            wells.
                             A monitoring well located in
                             the landfill showed a slight
                             water-level elevation compared
                             to other wells, indicating the
                             possibility of a local ground-
                             water mound.
                  Determine rate of
                  groundwater flow in strata
                  and bedrock fractures.
                            Perform hydraulic
                            conductivity tests on
                            existing wells.
                             Permeability of hydrogeologic
                             units was estimated; rate of
                             groundwater flow was calcu-
                             lated;  groundwater extraction
                             seems feasible.
                  Estimate interaction
                  between groundwater and
                  surface water.
                            Conduct an investigation of
                            the unnamed tributary on
                            foot to determine if there is
                            groundwater infiltration.
                              It appears that the groundwater
                              is recharging the unnamed
                              tributary.

-------
Table 3-2
RESULTS OF IN-SITU HYDR4ULIC CONDUCTIVITY TESTS
Well Number
Rl
R2
R3
GWIS
GWID
Test Number
1
2
0
1
2
3
1
2
0
1
2
0
1
2
K
2.1 x 10 'cm/sec
1.9 x 10 'cm/sec
1.5 x 10"1 cm/sec
4.8 x 10 2 cm/sec
4.2 x 10 2 cm/sec
5.1 x 10 2 cm/sec
3.0 x 10 2 cm/sec
3.2 x 10 2 cm/sec
2.9 x 10 2 cm/sec
9.5 x 10 2 cm/sec
9.5 x 10 2 cm/sec
1.1 x 10 'cm/sec
1.2 x 10 2 cm/sec
9.8 x 10 3 cm/sec
Geometric Mean
1.8 x 10"1 cm/sec
4.7 x 10 2 cm/sec
3.0 x 10 2 cm/sec
1.0 x 10"1 cm/sec
1.1 x 10"2 cm/sec
Geometric Mean: 7.4 x 10 2 cm/sec
A3-4

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>
                                                                                                                                  lng«tton,
                                                                                                                               Dermal Contact
                                                                                                                                  Inhalation
                                                                                                    Inaeillon.
                                                                                       VWaWteallon,   Inhalation,
                                                                                        Landfill Gat    Dermal
                                                                                                     Contact
                            IngeiHon,
                         Dermal Contact,
                         Bloconcentration
                                                                                                          Municipal
                                                                                                            landfill
                                                      Uachate
                                                      S*«pag*
Water Supply
Wtllt
 Lakes.
Slraami,
Wettands
                                                                                                                         Aluvlum
                                                                                                                       (Sond and Silt)
             : •  : : ::::•:::•:•:•:•: ^n-TTtT^r*?
             ::•:•;•:•:•••:•&::::•••:
                                                                                                                                   (M*dlum to Court*
                                                                                                                                    Sand and Grav«l)
                                   Gfoundwatw loM*
                                   Con1amlml*d M*da
                                                                                                                       Sandstone Bedrock
                                   B«l«ow MKhanlwn
                                                                                                                                                                  Figure 3-1
                                                                                                                                               CONCEPTUAL SITE MODEL
                                                                                                                                                 EXAMPLE LANDFILL SITE

-------
fc
Table 3-3
PRELIMINARY POTENTIAL EXPOSURE PATHWAYS UNDER CURRENT AND
FUTURE USE FOR THE EXAMPLE SITE
Source
Chemicals in
fill and/or in
drums
Release
Mechanism
Erosion
Excavation
Leaching
Leaching
Leaching
Leaching
Leaching
Leaching
Leaching
Transport
Medium
Direct Contact
Direct Contact
Groundwater
Groundwater
Leachate Seep
Leachate Seep
Leachate Seep
Landfill Gas
Landfill Gas
Exposure
Point
Onsite
Onsite
Onsite
Offsite
Stream
Stream
Stream
Onsite
Offsite
Exposure
Route
Ingestion
Dermal Absorption
Ingestion
Dermal Absorption
Inhalation
Ingestion
Dermal Absorption
Inhalation
Ingestion
Dermal Absorption
Inhalation
Bioconcentration
Ingestion
Ingestion offish that
bioncentrated
chemicals
Ingestion
Dermal Absorption
Inhalation
Inhalation
Explosion
Inhalation
Explosion
Potential
Receptors
Site workers
Future site workers
Trespassers
Site workers
Future site users
Groundwater users
Groundwater users
Aquatic organisms
People who
consume fish
Recreational water
users
Site workers
Future site workers
Residents
Area workers
Exposure
Potential
Exposed wastes in southeast section of
landfill.
Landfill not likely to be excavated in
future. Land value is not expected to
be high enough to justify expense of
developing site.
No current use of groundwater onsite.
Potential for future use of onsite
groundwater is minimal because of
landfill.
Use of sand and gravel aquifer. Wells
could be installed in the future.
Depends on degree of attenuation and
dilution.
Depends on degree and frequency of
exposure and amount ingested.
Depends on dilution with surface water
and degree of exposure.
Potential exists for migration into the
groundwater. Potential for exposure
during site investigation.
Potential exists for migration into the
groundwater.
Pathways Retained
Existing
Yes
No
No
Yes
Unknown
Unknown
Unknown
Yes
No
Potential
No, if covered
No, if not
excavated
No
Yes
Yes
Yes
Yes
Yes
Yes

-------
Receptors at the  site include  site  workers,
future site workers, trespassers,  residents, and
area workers. Site workers, future site workers,
and trespassers  can make dermal contact with
the exposed wastes. Residents and area workers
can come into  contact with the groundwater
through ingestion,  inhalation, and/or dermal
contact; and with landfill gas through inhala-
tion. Explosion is also a concern for landfill
gas .
     3.3 Preliminary Exposure
              Assessment

Exposure pathways must be identified in order
to adequately define the preliminary  remedia-
tion goals. Exposure pathways describe how a
chemical  can move  from its  source to a
receptor. Components of an exposure pathway
include  a   contaminant   source,   release
mechanism, and the transport, migration, and
fate of the contaminant.

3.3.1 Chemicals  Previously Detected at the Site

The known types of waste disposed  of at the
landfill  and their  chemical characteristic  are
briefly  discussed in  Section 2.5.2 of this
appendix.  Chemical  analytical data  for these
compounds are,  however,  available only for a
limited  set of contaminants.    The type of
contaminants and levels detected in  the ground-
water are  shown by  Table 2-1. The  contami-
nants detected are:
   1,1-DCE
   PCE
   1,1,1-TCA
   TCE
   cis-l,2-DCE
   VC
lead
arsenic
total chromium
ethylbenzene
toluene
bis(2-e/h)phthalate
3.3.2 Contaminant Source

The contaminant sources at the  site are  the
wastes disposed of in the landfill. They include:

   •   Chemicals  and  drums  containing
       chemicals distributed throughout  the
       landfill
   •    A large number of drums disposed of in
       the southeastern portion of the landfill

   •    The "designated  area" where  liquid
       solvent wastes were also dumped in the
       southeastern section of the landfill

   •    Media now  contaminated  by wastes
       (e.g., groundwater,  possibly  surface
       water, and sediments of the unnamed
       tributary)

3.3.3 Release Mechanism

The mechanisms for contaminant release at the
site  include

   •    Leaching  of contaminants  into  the
       groundwater

   •    Leachate seeps discharging to adjacent
       soils and surface water

   •    Erosion of cover material,  exposing
       landfill contents so they are released by
       runoff

   •    Release  of  landfill  gas  containing
       volatile organics

3.3.4  Contaminant Transport

The primary transport mechanisms are:

   •    Movement with groundwater
   •    Movement of leachate seeps
   •    Movement with surface water runoff
   •    Movement of landfill  gas

Leaching  of contaminants from the landfill
materials  has occurred as  indicated by  the
groundwater contamination  and the possible
presence of a mound under the landfill. This is
the release mechanism of greatest concern at
the site because with no additional action, it has
the potential to  add the greatest amount of
contaminants to the environment and to affect
receptors via drinking water wells. Continued
release, however, may  occur from leaking
drums,  continued low-rate  infiltration  from
contaminated soils, wastes in contact with the
groundwater, or exposure of waste to surface
runoff as  a result of erosion.  Migration of
landfill gas is also of concern at the site because
                                            A3-7

-------
of both explosion potential  by a buildup  of
methane in enclosed  spaces and  air-quality
degradation by volatile (vinyl  chloride)
carcinogens.

3.3.5 Contaminant Migration

After contaminants have  entered the ground-
water, several migration pathways are possible
depending  on their  widely varying  sorption
characteristics.    Shallow groundwater could
migrate  downgradient or to deeper aquifers and
eventually  to  potential receptors  offsite.
Existing data indicate that  the  contaminant
plume has moved offsite  as evidenced by the
contamination in the  nearby residential wells.

Based  on  the  hydraulic conductivities  and
gradients determined during  the limited field
investigations,   and  an  estimated time   of
20 years, groundwater recharge velocities were
calculated.  Most of the  detected  VOCs are
expected to  be found within approximately
 1,000 feet of the site.

Contaminants in the leachate seeps may migrate
offsite to the unnamed tributary to the Polk
River. Potential receptors include aquatic and
terrestrial organisms in the stream  as well  as
human receptors who may consume fish from
the stream or use the stream for recreational
purposes.

Contaminants in the form of landfill gas may
also migrate from the site seeking escape into
the atmosphere.   Microbial decomposition  of
organic  wastes under anaerobic  conditions
produces a gas, which is generally 50 to  55
percent methane and 40 to 45  percent carbon
dioxide.

3.3.6 Contaminant Fate

The following discussion describing the fate of
contaminants  detected in the study area is based
on  a review  of literature and relevant site
conditions.

VOCs were detected in groundwater within the
landfill  and in nearby residential wells. Under
existing  site  conditions, the  VOCs could  be
transported with groundwater,  leachate seeps,
or surface-water  runoff to surface waters.
During transport in  the groundwater, the
contaminants  may be subject to adsorption,
hydrolysis, and biological degradation under
aerobic or anaerobic conditions. Upon trans-
port to surface water the chemicals may be
adsorbed to sediments or taken  up by aquatic
organisms, and with exposure to  aerobic condi-
tions and  sunlight, subjected to  volatilization,
biological    transformation,   hydrolysis, or
photolysis.  The primary mechanisms that affect
the migration  and fate  of the  organic com-
pounds are: adsorption on sediments, volatili-
zation,  degradation,  and uptake by aquatic
organisms.

3.3.7 Exposure Pathways

The  potential  exposure  pathways associated
with the  site are shown  in  Table  3-3.  The
major  potential exposure pathways associated
with the site  are

   •     Release of contaminant to the ground-
        water, contaminant migration through
        the groundwater, and exposure through
        use of the groundwater  as a drinking
        water  source

   •     Release of a contaminant from leachate
        seeps to surface water (stream) and the
        exposure  to  aquatic  and terrestrial
        organisms in the stream

   •     Erosion of cover material and exposure
        of landfill contents leading to exposure
        of nearby residents, site workers, future
        site   workers,   future  site   users,
        trespassers, or terrestrial  wildlife

   •     Landfill gas migration leading  to tire
        and explosion and air quality degrada-
        tion which can  affect residents,  area
        workers, site  workers, and future site
        users

Identifying these exposure pathways aids in the
development of the remedial action objectives
and preliminary remediation goals, which are
presented in Section 4.3 of this appendix.
                                             A3-8

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                                        Section 4
 PRELIMINARY IDENTIFICATION  OF REMEDIAL ACTION
                                 ALTERNATIVES
   4.1 Potential ARARs for the
             Example Site

A description of the federal and state location-
and action-specific ARARs for CERCLA muni-
cipal landfill sites can be found in Sections 5
and 6,  respectively, of the body of this report
(Conducting Remedial Investigation/Feasibility
Studies for CERCLA Municipal Landfill Sites).
Potential federal location-specific ARARs for
the example site are presented in Table 5-2 in
the body of this document; no state location-
specific requirements (Section 6) were identified
that were  more  stringent  than the federal
location-specific ARARs.

The most significant potential location-specific
ARARs  involve  wetlands and floodplains.
Although there are no wetland areas presently
known to exist  near the  site,  if any  are
discovered remediation will have to be imple-
mented in a manner that minimizes  the destruc-
tion, loss or degradation of the wetland areas
(Executive Order  11990, Protection of Wet-
lands~40 CFR 6, Appendix A). Additionally,
the Clean Water Act Section 404 prohibits
discharge of dredged or fill material into  a
wetland  area without a permit.    If it is
determined that the example site is within the
floodplain of the Polk River, then remediation
will have to avoid adverse effects and preserve
natural and beneficial values of the floodplain
(Executive  Order  11988, Protection  of
Floodplains~40 CFR 6, Appendix A).

Potential federal action-specific ARARs are
presented in Table  5-3 in  the body  of  this
document. The most significant action-specific
ARAR will be  in compliance with RCRA clo-
sure requirements.  At a minimum, remedia-
tions will have to comply with RCRA subtitle D
closure requirements.  Compliance  with RCRA
Subtitle C requirements will be necessary if it is
determined to  be applicable or relevant  and
appropriate. Subtitle C will be applicable if the
results of the RI indicate that the waste in the
southeast corner of the landfill contains RCRA
characteristic  or  listed waste  and that  the
response action for those wastes constitutes
treatment, storage, or disposal as defined by
RCRA. A determination of relevance and
appropriateness will depend on a number of
factors, including the nature of the waste, its
hazardous properties,  and the nature of the
requirement itself.  Since it is probable that a
cap will be constructed at the  example site,
compliance with state cover design requirements
will be necessary. The state requires sufficient
freeze-thaw protection with minimum cover
requirement including a 2-foot clay layer with a
 1.5 to 2.5-foot cover  layer and 0.5  foot of
topsoil.

In situations where RCRA  requirements are
potential  ARARs, disposal  of contaminated
soils will be influenced by  the RCRA Land
Disposal Restrictions (LDRs). The LDRs may
be applicable  to  contaminated soils  if it is
determined that the soils have been contami-
nated by a restricted, listed RCRA waste or if
the contaminated  soils  are a RCRA character-
istic hazardous waste. The LDRs may require
that a specific concentration level be achieved
or that a  specified technology  be used for
treatment prior to offsite disposal at  a RCRA
facility.

 Some  of the alternatives for the example site
may include technologies that result in  dis-
charge of contaminants to the  air. Technolo-
gies that typically  result in air emissions include
air stripping, collection and treatment of landfill
gas, excavation and consolidation of contami-
nated soils, and incineration. Table 5-3, in the
body of this document summarizes the require-
ments concerning air emissions for these tech-
nologies,  which  may be implemented at the
 example site.

 State  and federal chemical-specific  ARARs
 (e.g.,  MCLs,  state groundwater enforcement
 standards) will have to be complied with when
                                            A4-1

-------
determining  appropriate cleanup  levels  for
groundwater.   The MCLGs, established under
the Safe Drinking Water Act, that are set at
levels  above zero,  should be  attained  by
remedial actions for ground or surface waters
that are current or potential sources of drinking
water.  Where the  MCLG for a contaminant
has been set at a level of zero, the MCL  for
that  contaminant should be attained.   More
stringent state standards that have been promul-
gated,  are identified  in a timely  manner, and
have been applied consistently by the state, will
have to be  attained unless a waiver is  used.
Tables 4-1 through 4-4 of this appendix present
the potential chemical-specific ARARs for the
example site. Water quality criteria have been
included in the tables along with drinking water
standards since it is likely these criteria would
be   the  basis   for  establishing discharge
requirements for discharges to the unnamed
tributary to the Polk River.
 4.2 Review of Analytical Results
     and Comparison to ARARs

Table 2-1 in this appendix provides a summary
of the  groundwater sampling and analytical
results  for both residential  and  onsite wells.
The sampling data for these seven wells are
described as not being  of CLP  quality, with
QA/QC procedures not available, and with a
detection limit higher than the MCLs for some
chemicals. However,  it is clear  that all wells
show some VOC contamination.

To  show how  the  streamlined  approach
described in Section 3.7.2 of this document may
suggest that a certain remedial action (such as
capping) be initiated, the contaminant concen-
trations actually detected in residential wells are
compared to the ARARs for each contaminant.
Because ingestion of groundwater is a direct
exposure route, any contaminant concentration
above its ARAR (federal non-zero MCLGs or
MCLs) would indicate that remedial action is
warranted. After comparing  Tables 2-1 (con-
taminant levels in residential wells) and  4-1
 (potential chemical-specific ARARs),  it  is
obvious  that several residential  wells have
contaminant  concentrations above  ARARs,
particularly  well  R-3 where 1,1-DCE,  PCE,
TCE, VC, and ethylbenzene concentrations are
all above their federal MCL. Therefore, based
on this review of preliminary groundwater data,
the  following conclusions  can be made  to
expedite remediation:

1.  Initial RI fieldwork should include obtaining
   data that can be utilized to make this com-
   parison and determination.  If validated RI
   data confirms that contaminant levels  in
   residential wells  clearly exceed  ARARs,
   remediation to address  contamination  in
   residential wells as an early action or interim
   action is warranted.

2.  Based  on the volume and heterogeneity of
   waste within the landfill, capping can  be
   identified as the only practicable alternative
   for the  landfill  contents  (discussed  in
   Section 4.4.1). Therefore, in order to reduce
   the continued contaminant  loading  to
   groundwater  capping alternatives  for  the
   example site may be evaluated as an early
   action.

A more thorough  quantitative baseline risk
assessment  is required for other exposure
pathways  since there is not clear exceedance of
ARARs. These areas include risks associated
with hot spot areas, landfill gas, and surface
water and sediments.

4.2.1 Baseline Risk Assessment

The approach described above for the baseline
risk assessment of the example site deals only
with residential groundwater data, ingestion of
groundwater as the route of exposure, and com-
parison to federal MCLs for the toxicity assess-
ment.  The purpose is to expedite remediation
of groundwater  since ARARs appear  to  be
clearly exceeded.   A more  thorough  baseline
risk assessment,  considering all potential
exposure pathways for both human and environ-
mental exposure, will be necessary to show that
the  final  remedies  will protect human health
and the environment. The following documents
provide guidance  regarding  more  thorough
baseline risk assessments:
                                             A4-2

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Table 4-1
POTENTIAL FEDERAL CHEMICAL-SPECIFIC ARARs FOR THE EXAMPLE SITE'
Chemical"
Trichloroethylene
Vinyl Chloride
1 , 1 -Dichloroethylene
cis- 1,2- Dichloroethylene
Benzene
Ethylbenzene
Toluene
Xylenes (total)
Tetrachloroethylene
1,1,1 -Trichloroethane
Bis(2-ethylhexyl)phthlate
Lead
Arsenic
Chromium III
Chromium VI
Copper
Mercury (Inorganic)
Manganese
Iron
MCL
Ug/1
5
final 1987
2°
final 1987
7
final 1985
70'
proposed 1989
5
final 1987
700e
proposed 1989
2,000'
proposed 1989
10,000'
proposed 1989
5'
proposed 1989
200
Final 1987
N/A
50'-'
50s
50''h
final 1986
-508'"
final 1986
1,300
proposed 1988
2'
proposed 1989
N/A
N/A
MCLG
us/l
0
proposed 1985
0'
final 1985
7
final 1985
70'
proposed 1989
0
final 1985
680
proposed 1985
2,000'
proposed 1985
440
proposed 1985
0
proposed 1984
200
Final 1985
N/A
20'
50
proposed 1985
120"
proposed 1985
120"
proposed 1985
1,300
proposed 1988
2'
proposed 1989
N/A
N/A
Secondary
MCL
Pg/1
N/A
N/A
N/A
N/A
N/A
30e
proposed 1989
40'
proposed 1989
20'
proposed 1989
N/A
N/A
N/A
N/A
N/A
N/A
N/A
1,000'
proposed 1989
N/A
50
300
"Source unless otherwise noted - Integrated Risk Information System (IRIS), March 1990
'Some of the ions that may be used for plume mapping at the example site (e.g., chloride, sodium,
sulfate) do not have chemical-specific ARARs associated with them. These parameters are being
analyzed for use as conservative indicators in determining the extent of groundwater contamination.
'Federal Register 45 CFR (141)
'U.S. EPA Health Advisories
'Federal Register 54 CFR (97)
'For water entering the distribution system, not at the tap
Tederal Register 40 CFR (141)
"Proposed 100 jig/1 for total chromium (III and VI), 54 CFR (97)
'Federal Register 53 (160), 8/18/88
N/A = not available
A4-3

-------
Table 4-2
POTENTIAL FEDERAL CHEMICAL-SPECIFIC TBCs FOR THE EXAMPLE SITE'
Page 1 of 2
Chemical'
Trichloroethylene
Vinyl Chloride
1.1-Dichloroethylene
cis-1 ,2-Dichloroethylene
Ethylbenzene
Toluene
Xylenes (total)
Tetrachloroethylene
1,1,1-Trichloroethane
bis(2-ethylexyl)phthlate
Lead
Arsenic
Chromium III
Chromium VI
Benzene
Copper
Amlent Water Quality Criteria
Human Health
Water & Fish
ug/i
2.7
108 cancer risk
2'
10s cancer risk
0.033
106 cancer risk

Fish Only
van
80.7
10° cancer risk
525'
10° cancer risk
1.85
10e cancer risk

1,400 3,280
14,300

0 . 8
10' Cancer Risk
18,400
1.75'
50
0.0022
170,000
50
0.66
106 cancer risk
...
424,000
-.
8.85
10' Cancer Risk
1,030,000
5.88'
N/A
0.0175
3,433,000
N/A
40
10e cancer risk
...
Aquatic Organ sms (Freshwater)
Acute LC
MS/I
45,000
...
11,600

32,000
17,500
N/A
5,280
None
940
82
360
980
16
5,300
6.5'
Chronic LC
MS/I
None

None

None
None
N/A
840
None
3
3.2
190
120
11
None
...
Oral Reference Dose
mg/kg-day
0.00735'

0.009
0.01'
0.1
0.3
(assume 05
absorption factor)
2
0.01
0.09
(assume 0.3
inhalation retention
factor)
0.02
Inappropriate
Pending
1
0.005
Pending

Health Advisory
Longer Term Adult
and Children
ug/i
No suitable data
46'
3,500'
3,500'
3,400
3,460'
27,300'
5,000
125,000'
N/A
N/A
N/A
840
840
Not calculated due
to carcinogenity

Cancer Classification
B2'
A'
C
D
D
D
D
Pending
D
B2
B2
A
N/A
A
by inhalation only
A
D
Oral Potency
(mg/kg-day) '
0.011'
2.3'
06
None
None
None
None
N/A
None
0.014
N/A
1.5'
N/A
N/A
0.029
from inhalation data
None

-------
                                                                                               Table 4-1
                                                             POTENTIAL FEDERAL  CHEMICAL-SPECIFIC TBCs FOR  THE  EXAMPLE SITE'
                                                                                                                                                                                            Page 2 of 2
Chemical'
Mercury
Ambient Water Quality Criteria
Human Health
Water & Fish
ug/l
...
Fish Only
van

Aquatic Organisms (Freshwater)
Acute LC
H9'l
4.857"
Chronic LC
van
1.302"
Oral Reference Dose
mg/kg-day
...
Health Advisory
Longer Term Adult
and Chidren
ug/l

Cancer Classification
D
Oral Potency
(mg/kg-day) '
None
'Source, unless otherwise noted - Integrated Risk Information System (IRIS),  March 1990
bU.S.  EPA Health  Advisories
CEPA  Health Effects Assessment Summary Tables (HEAST) Fourth  Quarter FY 1989
'Federal Register 45(231)
'Interim  Addendum to  DEHP Criteria
'Risk Assessment Forum Document,  1988
'Some of the ions that may  be  used  for plume  mapping at the example site (e.g., chloride, sodium, sulfate) do not have chemical specific ARARs associated with them. These parameters are being analyzed for
 use as conservative  indicators in determining  the extent  of groundwater contamination.
hMercury(ll).  Ambient Water Quality Criteria  for  Mercury - 1984,  EPA
At a hardness  of 50 mg/l, Federal Register, Vol. 50  p. 30784, July 29, 1985
N/A =  not available
LC =  lethal concentration
 — = no  value found

U.S.  EPA  Cancer Classification
 Group  A  Human  carcinogen-sufficient evidence of carcinogenicity  in  humans
 Group  B1 Probable  human carcinogen-limited evidence of carcinogenicity in  humans
 Group  B2 Probable  human carcinogen-sufficient evidence of carcinogenicity  in animals
 Group  C  Possible human carcinogen-limited evidence of carcinogenicity in  in animals
 Group  D  Not classifiable as to human carcinogenicity-there is  no animal evidence, or  human or animal evidence is  inadequate
 Group  E  Evidence of noncarcinogenecity for humans

-------
Table 4-3
STATE GROUNDWATER STANDARDS
FOR THE EXAMPLE SITE
Chemical"
Arsenic
Chromium
1 ,2-Dichloroethylene
(cis)
1,1-Dichloroethene
Ethybenzene
Lead
Manganese
Selenium
Silver
Toluene
Tetrachloroethylene
1,1,1 -Trichloroethane
Trichloroethene
Vinyl chloride
Xylene
Zinc
Enforcement Standard"
(Hi/1)
50
50
100
0.24
1,360
50
50
10
50
343
1.0
200
1.8
0.015
620
5,000
Preventative Action
Limit"
(Hi/1)
5
5
10
0.024
272
5
5
1
5
68.6
0.1
40
0.18
0.0015
124
2,500
"Chemicals are those to which state standards apply. Typically, there will not be
state groundwater standards for all the chemicals detected in the groundwater.
bThe list presented is based on a review of Wisconsin groundwater standards--
NR140.
A4-6

-------
Table 4-4
STATE AMBIENT WATER QUALITY CRITERIA
FOR AQUATIC LIFE PROTECTION
FOR THE EXAMPLE SITE
Chemical
Arsenic d
Benzoic acid
bis-2-Ethylhexylphthalate
Chromium(hexavalent) d
Chromium(trivalent)
1 , 1 -Dichloroethene
1,2-Dichloroethene (cis)
Ethylbenzene
Tetrachloroethylene
1,1,1 -Trichloroethane
Trichloroethene
Vinyl chloride
Xylenes
State Water Quality
Criteria"
Acute* Toxicity
Criteria (ug/1)
363.8
-
-
14.2
3,301.1
-
-
-
-
-
-
-
-
Chronic0 Toxicity
Criteria (ug/1)
153.0
-
-
9.7
95.4
-
-
-
-
-
-
-
-
Notes:
"Based on Wisconsin Water Quality Criteria for Protection of Freshwater Aquatic Life (Warm
Water Sportfish Classification). From Wisconsin Administrative Code NR 105.
'Acute Toxicity Criteria is the maximum daily concentration of a substance which ensures
adequate protection of sensitive aquatic species and may not be exceeded more than once every
3 years.
"Chronic Toxicity Criteria is the maximum 4-day concentration of a substance which ensures
adequate protection of sensitive aquatic species and may not be exceeded more than once every
3 years. CTC are based on acute/chronic toxicity ratios as defined in NR 105.06(5).
'Criterion listed is applicable to the "total recoverable" form. Typically, state water quality criteria
will not exist for all the contaminants found at the site.
A4-7

-------
      U.S. EPA. Risk Assessment Guidance
      for Superjund—Human Health Evaluation
      Manual, Part A. Interim Final. EPA/
      540/1-89/002. December 1989.

      U.S. EPA. Risk Assessment Guidance
      for Superfund.  Volume II. Environ-
      mental Evaluation Manual. EPA/540/
       1-89/001. March 1989.
4.3 Preliminary Remedial  Action
        Objectives and Goals

Preliminary remedial action objectives and goals
have been  developed for the example site to
assist in identifying preliminary remedial action
alternatives and RI  data requirements.    The
remedial action objectives for the example site
are  as follows:

   •   Provide adequate  protection to human
       health and the environment from direct
       contact or ingestion  of the hazardous
       constituents  in wastes or  soil  from
       landfill

   •   Provide adequate  protection to human
       health and the environment from direct
       contact, ingestion, or inhalation of the
       hazardous constituents in groundwater
       beneath the landfill or groundwater that
       has  migrated from the landfill

   •   Provide adequate  protection to human
       health and the environment from direct
       contact or ingestion  of the hazardous
       constituents   in surface water  and
       sediments of the unnamed tributary

   •   Provide adequate  protection to human
       health from  inhalation or explosion  of
       landfill  gases

Preliminary remediation goals were developed
based on the remedial action objectives, existing
data  (Section  2.7),  preliminary  ARARs
(Section 4.1), and the exposure assessment
(Section 3.3). Because of the limited usability
of the data  (see Section 2.7), these goals will be
revised as more  information  on  the site
becomes available.  The preliminary  remedial
action goals are as follows:
4.4
      Prevent ingestion  of contaminated
      groundwater  exceeding  non-zero
      MCLGs or MCLs (where MCLGs are
      set at zero).

      Prevent direct  contact  with landfill
      contents and minimize continued con-
      taminant loading to groundwater.

      Prevent direct contact and ingestion of
      contaminated soils  from hot spot areas.

      Provide adequate protection to human
      health from inhalation or explosion of
      landfill gas.   Potential collection and
      treatment requirements will be estab-
      lished based on an analysis of the data
      to be  collected  in the RI (including a
      risk  assessment).

      Provide adequate protection to human
      health and the environment from direct
      contact or ingestion of contaminated
      surface  waters or  sediments of the
      unnamed tributary.   Specific  remedia-
      tion requirements will be established
      based on risk after  an analysis of the
      data to be collected in the RI.
Preliminary  Remedial Action
        Alternatives
Several technologies  and/or alternatives  are
unlikely  to  survive screening in the FS  for
technical, implementation, or cost reasons. As
an example, the excavation of the landfill with
subsequent  treatment  or  disposal  onsite  or
offsite is not a  feasible  alternative  for  the
example site because of the substantial cost that
would be associated with a landfill of this size
(20  acres,  or approximately 750,000  cubic
yards), the significant health and safety concerns
that would arise during excavation in areas of
solvent disposal,  and  the potential for fire or
explosion of the  landfill gases. Likewise, con-
tainment of groundwater with a cutoff such as a
slurry wall is not considered practicable because
an  aquitard does not  appear to be present at
the site.   The following sections discuss the
practicable remedial actions for the  media of
concern at the site.
                                            A4-8

-------
As required by the NCP, the no-action alterna-
tive  is  included and  involves  no additional
activities by EPA, thereby providing a baseline
for evaluating other alternatives.

4.4.1 Landfill Contents

The most practicable remedial action alternative
for this  medium  is containment with or without
institutional controls. The containment alterna-
tives might include: (1) regrading and  revegeta-
tion  of  existing cap  and implementation of
institutional  controls,  (2) construction of  a
single-barrier cap with or without institutional
controls, or (3)  construction of a composite-
barrier   cap  with  or without institutional
controls. The purpose of the first alternative
would be to provide some protection against
direct contact  and would improve surface water
drainage, thereby  reducing infiltration.  The
second two alternatives would provide superior
protection against further groundwater contami-
nation by minimizing the potential for infiltra-
tion  and would  provide  a barrier to prevent
contaminated  soil from eroding  during precipi-
tation events. Reducing  infiltration  and sub-
sequent leachate generation would also mitigate
leachate seeps. Capping can also provide gas
control, particularly if  implemented in conjunc-
tion  with a gas collection  system. A composite-
barrier cap  will be more effective and reliable in
preventing  infiltration than a single-barrier  cap,
however, both designs  may satisfy applicable or
relevant   and   appropriate    requirements
(ARARs).    All three caps  may be  viable,
depending on the remedial objectives and the
results  of the RI. The factors that may affect
the type of cap to be used are presented in
Figure   4-1   of the  body  of this   report
(Conducting Remedial Investigations/Feasibilip
Studies for CERCLA Municipal  Landfill Sites).
These alternatives could be used in conjunction
with a fence and a restrictive covenant on the
landfill property  to prevent  future  site
development.

If RI data indicate that landfill gas presents a
hazard  to human health and the environment,
then deed restrictions  may also  be imposed on
areas in the vicinity of the site to limit exposure
to the landfill gas. Another measure may be to
vent and treat the landfill gas as described in
Section  4.3.4.
4.4.2 Hot Spots

The practicable alternatives for the  contami-
nated soils in the southern portion of the site
include:  (1) excavation and disposal,  (2) exca-
vation, treatment, and disposal  (onsite  or off-
site) of treated material, or (3) consolidation of
hot spot  areas under a landfill cap.

The first two alternatives would involve excava-
tion, possible treatment,  and disposal of the
soil/waste in the solvent disposal area of the
landfill. Both alternatives would protect against
further contamination  of the groundwater and
surface  water  and  against direct  contact.
Excavation  could be accomplished using con-
ventional construction equipment (e.g., back-
hoe); the risks  to  local  residents  and  site
workers  during  execution activities will be
evaluated during the analysis of remedial action
alternatives.  Treatment of contaminated soil/
waste, if necessary, would likely be done onsite
(offsite treatment of soils from municipal land-
fill sites is rarely done because of availability
and cost).   The  most viable onsite  treatment
options include incineration and solidification/
stabilization. The most common type of incin-
eration process is rotary  kiln, but  often the
decision is  made during design or  by the
remediation  contractor based on performance
criteria.    Solidification/stabilization   involves
adding pozzolanic agents such as lime, cement,
and fly ash to the soil/waste in situ or  in a batch
process.  The selected treatment method  may be
largely dependent on whether  the waste is a
RCRA-restricted  waste or not, and  therefore
whether the land disposal restrictions  apply.

Disposal of excavated soil/waste should occur
onsite and be incorporated under the landfill's
final cover.  All soil/waste  treated onsite would
probably be disposed of in the same place from
which it was removed if the treated wastes are
not considered RCRA  wastes.

The required  level of treatment  of RCRA-
restricted wastes before disposal is dependent
on the RCRA land disposal restrictions  (LDRs)
that apply to the  specific contaminant. In order
to  determine the level of treatment required,
the process generating  the  contaminants
must be identified and the appropriate RCRA
hazardous waste  number determined.
                                              A4-9

-------
In addition to information on the process that
generated the hazardous  waste, information
needed to select  a treatment  and disposal
option includes: the type and concentrations of
contaminants  in the soil, the volume of contam-
inated soil, the moisture content of the soil, and
the soil type. Also, information on the types
and  population  densities  of resident  micro-
organisms suitable for biodegradation of con-
taminants may be needed  if contaminant con-
centrations are sufficiently high.    Potential
exposures from dermal contact, entrainment of
soil  particles  in air,  and  release of volatiles
during remediation would be evaluated and
necessary actions taken.

The  third alternative  for this, area would  be
consolidation of the  hot spots to reduce the
area of the final landfill cap. This alternative is
similar to the first alternative, except that, when
a landfill cap is constructed, the hot spot areas
would be included under the cap, or material
from the hot spot areas would be excavated to
the extent necessary to consolidate these mate-
rials under  the  landfill cap. This  alternative
would prevent direct contact with the contami-
nated soil and prevent contamination of surface
water. Further contamination  of groundwater
would be reduced by preventing  infiltration, of
runoff through the contaminated  soil.

4.4.3 Groundwater/Leachate

The  existing data shows that  four of the five
residential wells tested exceeded primary MCLs,
as presented  in Table 2-1 of this appendix.
Practicable alternatives for groundwater reme-
diation will include extraction, treatment, and
disposal of the contaminated groundwater. The
two  strategies associated with groundwater ex-
traction include placement of perimeter wells to
capture leachate and placement of downgradient
wells to  capture  contaminated groundwater that
has migrated offsite. Leachate extraction wells
in conjunction with a landfill cap may also be
used  to stop  leachate  seeps.  Collection
trenches are also  an  option for groundwater/
leachate extraction; however,  extraction wells
are more likely to be used because of the depth
of groundwater contamination.

Extraction, treatment, and disposal of contami-
nated groundwater would help stabilize the
contaminant plume  and provide for ground-
water  remediation.    Groundwater  samples
should also be  analyzed to characterize the
contaminant types and characteristics and the
conventional parameters-such as hardness and
iron content-needed to  design  a treatment
system.

Extraction wells would be located in areas that
would maximize the yield of contaminated
groundwater. Perimeter wells could be placed
around the  landfill  to  capture  leachate  and
provide a containment" system to minimize off-
site migration of contaminants via groundwater
and leachate seeps.   Placement of wells down-
gradient within the contaminated plume would
be used to remediate contaminated groundwater
that has already migrated offsite. The extracted
groundwater would then be treated before 'dis-
charge, either onsite  or at a POTW. The infor-
mation needed to design a more comprehensive
groundwater extraction  system  includes the
chemical parameters associated with the con-
taminated plume and the hydraulic characteris-
tics of the aquifer.

Either onsite or offsite treatment of contami-
nated  groundwater  will  likely be feasible.
Typically, leachate or high strength contami-
nated groundwater  from municipal landfill  sites
will be high in concentrations of organic matter.
Treatment  is usually by  conventional means
such  as  biological treatment (e.g., activated
sludge), physical treatment (e.g., granular acti-
vated carbon (GAC) or  air stripping), and/or
chemical treatment (e.g., metals precipitation).

Based on known data, onsite treatment might
be  accomplished using air stripping for VOC
removal  and/or GAC for  removal of semi-
volatile contaminants.  Depending on the con-
taminants  and their concentrations, GAC
columns could also  be used without air strip-
ping to remove  VOCs, as well as semivolatile
contaminants.

Average and peak flow rates and contaminant
concentrations and properties would need to be
identified"  to  design the  treatment  system.
Information on the hardness, biochemical oxy-
gen demand (BOD), chemical oxygen demand
(COD), total suspended solids (TSS), iron, and
other conventional pollutant parameters would
be  needed as well in order to determine if other
treatment  processes (such as  biological  or
                                            A4-10

-------
chemical treatments) are necessary in addition
to, or as a replacement for, the  air stripping
and/or GAC  treatment.   At the landfill, the
BOD tests could be prone to interferences from
metals and other  materials present.  COD  is
therefore usually more representative of the
leachate. This  information  could be used to
determine the probability and severity of sealing
and fouling occurring in the bed of an air strip-
per and GAC column. Sand filters or cartridge
filters may be necessary to prevent sealing and
fouling of the GAC columns. Also, if air strip-
ping is  used, vapor-phased GAC may be re-
quired to remove VOCs from the air stripper
emissions.

For onsite remedial actions, the substantiative
requirements of the  ARARs, but not the ad-
ministrative requirements, must be met. Efflu-
ent from an onsite treatment system could be
discharged to  the Polk River; an NPDES permit
could be required for this disposal method and
appropriate ARARs  (such  as MCLs or water
quality criteria)  would be met.

As an  interim action, or  to  supplement a
groundwater  extraction and treatment system,
an alternate water supply could be provided to
affected or potentially affected residents to limit
exposure to contaminated groundwater.   The
water authority could  provide  the alternate
water supply by extending the existing distri-
bution system  or installing a new deep well.
Alternatively, bottled water could be used for
temporary drinking  and cooking. A  compre-
hensive well inventory and subsequent sampling
of nearby residential wells is needed to conduct
a risk assessment to determine  whether pro-
viding an alternate  water supply is warranted.

4.4.4 Landfill Gas

The potential  alternatives  for  this  medium
includes collection and possible treatment  of
landfill  gas.   This alternative involves inter-
cepting the methane gas using passive vents,
which typically consist of free venting struc-
tures; active  vents if air emissions are locally
controlled; or collection of the gas by onsite
extraction wells for treatment.   Passive vent
systems require that a highly permeable mate-
rial be placed in the path of gas flow to inter-
cept the landfill gas and discharge it to the air.
An active vent system  is used to control the
venting of gases into the atmosphere when the
constituents of the gas are of concern from an
air quality standpoint. After collection, if nec-
essary, landfill gas can then be incinerated using
enclosed ground flares.  Enclosed ground-flare
systems consist of a refractory-lined flame en-
closure (or stack) with a burner assembly at its
base. Because of the rural nature of the exam-
ple site, a passive venting system without treat-
ment may be acceptable.

Information needed to determine the need for
gas collection and treatment would be collected
by placement of monitoring gas probes within
the  landfill  as  well  as along the landfill
perimeter and analyzed for methane, TCE, and
vinyl chloride. The potential for pressure build-
up below a landfill cap  and potential for
damage to a vegetative cover will be evaluated
based on the  quality and quantity of landfill gas
estimated to be generated at the site.

4.4.5 Surface Water and Sediments

Contaminated sediments in the nearby unnamed
tributary to the Polk River may require reme-
diation.  The most practicable alternatives for
remediating  contaminated sediments  include
excavation and consolidation under the landfill
cap or leaving sediments in place and relying on
natural attenuation. Sediment removal can be
accomplished with conventional dredging  or
excavation equipment operated from  shore.

The  advantage of relying on natural attenuation
to  remediate  sediments  is  that  dredging
activities can often cause  secondary migration of
contaminants which can potentially have signifi-
cant environmental impacts.   If dredging is
done,  these impacts should be minimized by
dewatering during excavation activities.
                                             A4-11

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                                      Section 5
        REMEDIAL  INVESTIGATION AND FEASIBILITY
                            STUDY OBJECTIVES
The overall goals of the RI/FS are to:

    •    Complete a   field program  for
        collecting data to quantify the extent
        and magnitude  of  contamination in
        the  groundwater,  subsurface  soils,
        surface water/sediments, and landfill
        Determine if unacceptable risk exists
        to human health and the environment

        Develop and evaluate remedial action
        alternatives  if unacceptable risks are
        identified
Table 5-1 shows the objectives of the Phase I
RI for the Example Landfill site. After evalua-
tion of the Phase I data, it may be necessary to
conduct a Phase II. A  Phase II would be con-
ducted if the objectives of the Phase I RI are
not accomplished. For example, if the Phase I
RI groundwater sampling results indicate a con-
taminant plume but not enough data was col-
lected to  determine the extent of the  plume,
then further investigations will  be warranted.

The objectives and actions listed in  Table 5-1
only apply to the example site.  These may vary
for actual sites where  the contaminated media
and site conditions differ from the example site.
                                         A5-1

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                                                  Table 5-1
                          PHASE I REMEDIAL INVESTIGATION OBJECTIVES FOR
                                            THE EXAMPLE SITE
                                                                                                   Page 1 of 3
             Activity
                                                                Phase I Objectives
                                            (Activities Generally Performed After Work Plan Is Approved)
                                                  Objectives
                                                                                          Action
Site Mapping/Site Dynamics
Map site and determine topography;
determine site boundaries, drainage
patterns, and other geophysical features.
Use photogrammetric methods
from aerial photography conduct
fly-over, if necessary.
Geophysical  Investigation
Investigate probable presence of buried
ferromagnetic materials (drums) in
southern portion of the landfill.
Conduct magnetometer and/or
ground penetrating radar survey.
Geotechnical Investigation
Evaluate the physical properties
governing transport of contaminants
through identified pathways.

Collect data on soil characteristics to
determine if onsite soil can be used as
fill material and to determine placement
of a potential cap.

Evaluate existing cap to determine
physical  properties.
                                    Measure current landfill settlement rate.
Collect data on permeability,
porosity, hydraulic head, percent
organic carbon, etc.

Measure  soil characteristics such
as plasticity index, moisture
content, porosity, and
permeability.

1) Collect data on permeability,
porosity, and measure thickness.

2) Determine Atterberg limits.

3) Determine extent of vegetation
cover, any vegetative stress, and
erosion.

Monitor landfill benchmarks.
Hydrogeologic Investigation
Determine selection of screen settings in
both the shallow and deep wells.

Identify and characterize hydrogeologic
units.
Obtain soil classification or
     jic  data.
                                    Determine direction of groundwater flow
                                    and estimate gradients.
1) Place monitoring wells at points
around the landfill to better define
the aquifers and confining layers.

2) Perform down-hole geophysical
survey.

1) Install monitoring wells and
take water level measurements
from new  and existing wells.

2) Investigate yield of private and
public wells.
                                    Determine rate of groundwater flow and
                                    evaluate the feasibility of groundwater
                                    extraction.
                                          Install monitoring wells and
                                          perform hydraulic conductivity
                                          tests on new and existing wells;
                                          check water levels at a maximum
                                          of once a month during the RI.
Meteorological Investigation
Determine prevailing wind direction and
air speed to evaluate remedial
alternatives.
Collect and analyze wind speed
and direction data.
                                                       A5-2

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                                                 Table 5-1
                         PHASE I REMEDIAL INVESTIGATION OBJECTIVES FOR
                                           THE EXAMPLE SITE
                                                                                                Page 2 of 3
            Activity
                                                              Phase I Objectives
                                          (Activities Generally Performed After Work Plan is Approved)
                                                 Objectives
                                                                                        Action
Chemical Investigation

  Groundwater
                                   Identify extent and type of groundwater
                                   contamination to perform an assessment
                                   of human health and environmental risks
                                   to determine if remedial action is
                                   Identify upgradient water quality for
                                   each geologic unit.
                                   Determine source of groundwater
                                   contamination.
                                   Determine whether seasonal fluctuations
                                   occur in contaminant concentrations in
                                   the groundwater and in hydraulic
                                   characteristic

                                  Evaluate feasibility of groundwater
                                   treatment systems.
                                         Install monitoring wells in aquifers
                                         of concern; design monitoring well
                                         network to determine the extent of
                                         the plume (wells should also be
                                         located downgradient in "clean"
                                         area to confirm that the end of
                                         the plume is located); collect and
                                         analyze samples.

                                         Install upgradient monitoring wells
                                         in aquifers of concern and collect
                                         and analyze samples.
                                         Collect and analyze groundwater
                                         samples and compare results to
                                         the landfill waste characteristics
                                         and background levels.

                                         Sample and analyze groundwater
                                         with a minimum of two rounds of
                                         sampling from the  same
                                         location(s).

                                         Obtain COD,  BOD,  and  other
                                         conventional water quality data.
 Leachate
Identify extent and type of leachate seeps
to evaluate feasibility of groundwater
treatment system.

Estimate amount of leachate production
from landfill.
Collect and analyze leachate and
seep data.

Install leachate wells around land-
fill and measure leachate head.

Perform water balance calculation
on landfill.
  Surface Water and Sediment
Determine viability of treatment
technologies.

Determine effect of groundwater on
surface water.
Collect field measurements on DO
and temperature.

Collect and compare up- and
downgradient surface water and
aliment samples to downgradient
groundwater samples.
                                   Compare stream and groundwater levels
                                   during several periods during the RI.
                                         Install staff gauges onsite, survey
                                         gauges, measure surface water
                                         levels and groundwater levels
                                         concurrently.
                                                      A5-3

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                                                Table 5-1
                         PHASE I REMEDIAL INVESTIGATION OBJECTIVES FOR
                                          THE EXAMPLE SITE
                                                                                                Page 3 of 3
            Activity
                                                              Phase I Objectives
                                          (Activities Generally Performed After Work Plan is Approved
                                                Objectives
                                                                                        Action
Surface Water and Sediment
 (Continued)
 Determine background concentration of
 surface water and sediment.
Collect and analyze upstream
water and sediment samples
include toxicity testing.
 Surface Water and Sediment
                                  Determine surface runoff impact on
                                  surface water quality; determine the type
                                  and extent of contamination in nearby
                                  surface waters and sediments.
                                          1) Collect and analyze samples
                                          from nearest leachate seeps and
                                          compare to stream water quality.

                                          2) Collect and analyze surface
                                          water and sediment samples at
                                          increasing distances away from the
                                          landfill and compare results to
                                          landfill waste and background
                                          levels.
 Landfill Gas/Air
                                  Identify areas within the landfill
                                  containing high concentrations of
                                  explosive or toxic landfill gas to perform
                                  an assessment of human health risks due
                                  to air toxics and explosive hazards, to
                                  evaluate the feasibility of gas collection
                                  and treatmemt,  and to evaluate other
                                  remedial actions.

                                  Estimate concentrations of selected
                                  VOCs  being emitted to the  atmosphere.
                                          Obtain flow-related data from
                                          newly installed gas vents, estimate
                                          emission rates, and perform air
                                          modeling.

                                          Collect and analyze landfill gas
                                          samples from onsite  and perimeter
                                          sampling points.

                                          Collect and analyze ambient air
                                          samples.
 Landfill Gas/Groundwater
 identify areas within the landfill
 containing high concentrations of
 explosives or toxic landfill gas to
 determine if VOCs act or may act as a
 source of groundwater contamination
                                                                           Obtain flow-related data from
                                                                           newly installed gas vents, intimate
                                                                           emission rates, and perform air
                                                                           modeling.
 Hot Spots (Soil)
 Investigate areal extent, depth, and
 concentration of contaminants at hot
 spots in the landfill's soil.
Collect and analyze perimeter
samples with more intensive
sampling around known hot spot
 Environmental Evaluation
Determine impact of landfill on nearby
 stream.

 Describe aquatic and terrestrial
 community in vicinity of site and aquatic
 community downstream of site.

 Determine impact of remedial  action on
 stream.
                                                                           Collect and analyze surface water
                                                                           and sediment from nearby stream.

                                                                           Observe aquatic or terrestrial
                                                                           organisms in the vicinity of the
                                                                           site.

                                                                           Collect biota samples from stream
                                                                           adjacent to site.
                                                     A5-4

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                                         Section  6
                       DATA QUALITY OBJECTIVES
The data to be collected during the RI will be
used for site characterization, risk assessment,
and remedial action alternative evaluation. The
objectives of the RI and the necessary actions
to accomplish  the objectives  are shown  in
Table 5-1. The number and types of samples of
soil, groundwater,  leachate, sediments, surface
water,  and landfill gas to be collected for  a
sufficient representation of the conditions at the
site; the chemicals of concern for which the
samples are to be analyzed;  and the precision,
accuracy, representativeness,  completeness,  and
comparability (PARCC) parameters to be used
are summarized in  Tables  6-1 through  6-3.

In order to achieve the established DQOS,  a
combination of laboratory services will be used
for a more efficient use of time and money. All
five levels of data quality will be used  during
the RI as described below

   •   Level  I—Field screening. This level is
       characterized by  the use of portable
       instruments that can provide  real-time
       data to  assist in  the optimization of
       sampling point locations and for health
       and safety  support. Data can be gen-
       erated regarding  the presence or
       absence of certain contaminants (espe-
       cially volatiles) at sampling locations.
       An HNu will be used for Level I analy-
       sis for soil samples and to monitor con-
       centration of VOCS in air for health and
       safety considerations during  drilling.
       Additionally  an  explosimeter will be
       used during  drilling and  soil  probe
       installation; a radiation meter will be
       used initially to determine if harmful
       levels of radioactivity exist at the site.

   •   Level II—Field analysis. This level is
       characterized by  the use of portable
       analytical instruments that can be used
onsite  or in mobile  laboratories  sta-
tioned near  a site (close-support labs).
Depending  on  the  types  of contami-
nants,  sample  matrix,  and personnel
skills,  qualitative and quantitative data
can be obtained.   An onsite  mobile
laboratory  will  be used  during well
installation to provide analytical results
that  will be used  to re-evaluate the
proposed monitoring well  network.
Groundwater samples will be analyzed
for selected VOCs  and inorganic ions
(chloride and  sulfate] to aid in deter-
mining the  extent of the  groundwater
plume.  Soil gas samples  will also be
analyzed for VOCs to determine the
extent  of the solvent disposal area.

Level  Ill-Laboratory analysis  using
methods other  than the CLP Routine
Analytical Services (RAS).  This  level  is
used primarily  in support of engineering
studies using standard EPA  approved
procedures.  Some procedures may be
equivalent  to  CLP RAS,  without the
CLP requirements  for documentation.
Analysis will include COD, BOD, TOC,
and TSS in groundwater and leachate
samples.

Level  IV-CLP RAS.  This level  is
characterized by rigorous QA/QC pro-
tocols  and documentation and provides
qualitative and quantitative  analytical
data. Some regions have obtained simi-
lar support via their own regional labo-
ratories, university laboratories, or other
commercial laboratories. This level will
be used for confirmatory  sampling  of
groundwater, hot spots, surface water,
and sediments. Analyses performed will
include TCL organics  and TAL metals.
                                            A6-1

-------
Level V~Nonstandard methods.  These
 are analyses that may require method
 modification and/or development. CLP
 Special Analytical Services (SAS) are
 considered Level V.  This level will be
 used for vinyl chloride in groundwater
 and leachate where lower  detection
 limits are warranted.
Other—Geoteehniml  testing  to  deter-
  mine soil characteristic and other data,
  such as pH and conductivity, will  be
  conducted  to aid  in  the  enginiring
  design of alternatives.   Geotechnical
  analysis will be done by a commercial
  laboratory. Conductivity and pH  will be
  analyzed in  the  field.
                                       A6-2

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Table 6-1
DATA QUALITY OBJECTIVES SUMMARY FOR GROUNDWATER/LEACHATE
OF THE EXAMPLE LANDFILL SITE
Page 1 of 3
Data Quality
Objective Elements
Objective
Site Characterization
.Identify extent and typs of
contamination
• Determine if contaminants
are present in residential
wells
Risk Assesment
.Assess risks due to
ingestion
Engineering Design
of Alternative
. Evaluate feasibility
of groundwater
treatment system
Data Quality Factors
Prioritized Data Use(s)
Contaminants of Concern
Site characterization
TCE, vinyl chloride, lead,
arsenic, chloride, chromium
Risk assesment
TCE, vinyl chloride-,
lead, arsenic chromium
Engineering design of
alternative
COD, BOD, pH,
conductivity
Lsvel of Concern (ARARs)"
TCE
Vinyl chloride
Lead
Arsenic
Chloride
Sulfate
Chromium
5ppb
2ppb
SOppb
SOppb
N/A
N/A
50 ppb
5 ppb
2 ppb
50 ppb
50 ppb
N/A
N/A
50 ppb
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Reporting Limit"
TCE
Vinyl chloride
Lead
Arsenic
Chloride
Sulfate
Chromium
Appropriate Analytical Levels
Critical samples
5ppb
10 ppb
5 ppb
10 ppb
50 ppb
50 ppb
10 ppb
I, II, Iv
Residential wells
5 ppb
2 ppb
5 ppb
10 ppb
N/A
NIA
10 ppb
IV and V
Residential wells
N/A
N/A
N/A
N/A
N/A
N/A
N/A
III and Other
Monitoring wells
Data Quality Needs
Sampling/Analysis Procedures
• Sample Collection1
.Sample Analysis
Level I— Field Screening'


Use of HNu






N/A~Not appllicable
"These are federal MCLs from the SDWA. While federal ARARs are stated for this example, state ARARs may
preclude the federal ARARs.
'The listed values are the Contract Required Quantitation Limits (CRQLs) taken from the CLP SOWs (Level IV).
Since reporting limits in some cases are at or above levels of concern, special analytical services (SAS) reporting limits
(Level V) maybe required to achieve lower detection limits (e.g., vinyl chloride). This CRQL is matrix dependent and
may not be achievable in every sample.
'Sample collection procedures are outlined in the A Compendium of Supcrfund Field Operatons Methods, August 1987.
'Level I analytical methods are not compound specific, only quantitative for total organics.
A6-3

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                                                    Table 6-1
                   DATA QUALITY OBJECTIVES SUMMARY FOR GROUNDWATER/LEACHATE
                                      OF THE EXAMPLE LANDFILL SITE
                                                                                                     Page 2 of 3
          Data Quality
       Objective Elements
                                     Site Characterization
                                                                   Risk Assessment
                                                                                          Engineering Design
                                                                                             of Alternative
Level II--Field Analysis'
    TCE
    Vinyl chloride
    Lead
    Arsenic
    Chloride
    Sulfate
    Chromium'
                                 GC/ECD/PID
                                 GC/ECD/PID
                                 Atomic  Absorption
                                 Atomic  Absorption
                                 Ion Chromatograph
                                 Ion Chromaograph
                                 Atomic  Absorption
Level III-Non-CLP Lab  Methods8
    COD
    BOD
    TSS
    TOC
                                                                                         EPA 405.1
                                                                                         EPA 410.1
                                                                                         EPA 209
Level IV--CLP RAS
    TCE
    Lead
    Arsenic
    Chromium
                                 CLP  Organic  SOW
                                 CLP  Inorganic SOW
                                 CLP  Inorganic SOW
                                 CLP  Inorganic SOW
CLP Organic SOW
CLP Inorganic SOW
CLP Inorganic SOW
CLP Inorganic SOW
N/A
N/A
N/A
N/A
Level V-CLP SAS"
    Vinyl chloride
                                                               EPA 601
Other
    PH
    Specific Conductance
                                                                                         pH meter
                                                                                         Conductivity  meter
PARCC Parameters
r Precision'
   -   TCE
   - Vinyl  chloride
   -   Lead
   - Arsenic
   - Chromium
                                 +25%
                                 ± 20%
                                 ±20%
                                 ±20%
• Accuracy'
   -   TCE
   - Vinyl chloride
   -   PCB
   -  Lead
   .   Arsenic
   -  Chromium
                                 71-120%
                                 75-125%
                                 N/A
                                 75-125%
                                 75-125%
                                 75-125%
N/A~Not  applicable
 f
Methods  used  by the  onsite mobile labs-story.
Only total chromium will be detected.
 g Level III  analys  is only for parametersnot  on the CLP TLC  and TAL  lists  and  for  where QC  requirements  are
    less stringent than that of the CLP methods. Level III analysis is  not  applcable  for the selected contaminants of
    concern listed except for  COD and BOD  in groundwater  and TCE  and  vinyl chloride  in landfill gas.
 h Level V-CLP  SAS methods may inclide modified versions of CLP RAS methods  to achieve  lower detecton  limits, to
    provide project-specific QC,  to analyze for non-CLP parameters   or to   use   non-CLP   methods but still provide the levels
    and types of QA/QC and deliverables  prevented by CLP  RAS.
 'The  listed values  for  precision  and accuracy in analysis  of water  sample are based on  CLP  RAS  SOW requirements
    and do not necessarily reflect actual method performance.
                                                     A6-4

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                                                  Table 6-1
                  DATA QUALITY OBJECTIVES  SUMMARY FOR GROUNDWATER/LEACHATE
                                     OF THE EXAMPLE LANDFILL SITE
                                                                                                   Page 3 of 3
          Data Quality
       Objective Elements
                                      Site Characterization
                                                                    Risk Assessement
Engineering Desing
   of Alternative
> Representatives1
> Completeness1
1  Comparability'
j Qualitative parametere,  which  consieders  the  project  as  a whole.  No numerical criteria can be set.
  Can be expressed asaquantitative assessment of the percentage of valid data  received.  Also includes a qualitative
  parameter and must be assessed after all data are reviewed.
  A qualitative parameter that can be maximized through the use of standard sampling, analysis, and data review
   techniques.
                                                    A6-5

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Table 6.2
DATA QUALITY OBjECITVES SUMMARY FOR HOT SPOTS, FILL AND CAP INVESTIGATION
OF THE EXAMPLE LANDFILL SITE
Page 1 of 3
Data Quality
Objective Elements
Objective
Hot-Spot Areas
. Identify highly contaminated
areas that may be present
onsite
• Assess risk due to direct
contact
Fill
. Determine if fill can be used
for capping
Caplnvestigations
.Determine existing cap
characteristics
Data Quality Factors
Prioritized Data
use(s)
Contaminants of
Concern
Site characterization, risk
assessment, and engineering
design of alemative
TCE, PCB, lead, arsenic,
chromium, treatability parameters
Engineering design of alternative
Geotechnical parameters
Engineering design of alternative
Permeability, porosity, depth
Lewel of Concern (ARARs)'
TCE
Vinyl chloride
PCB
Lead
Arsenic
Chromium
636 ppb
0.3 ppb
0.091 ppb
105 ppb
3 ppb
(III) 75,000, (VI) 375 ppb


Reporting Limit'
TCE
Vinyl chloride
PCB
Lead
Arsenic
Chromium
Appropriate Analytical
Levels
Critical Samples
Data Quality Needs
Sample/Analysis
Procedure
.Sample Collection1
• Sample Analysis
Level I— Field Screening'
5 ppb
10 ppb
80 ppb
500 ppb
1,000 ppb
1,000 ppb
Site characterization II, III, IV
Risk assessment: iv and V
Clean samples at outer boundary
of contaminated area




Engineering design of alternative,
111
Collect sampes from perimeter
of waste area to determine areal
extent of waste




Engineering design of alternative,
Other




awhile federal ARARS are stated for this example, state ARARs may preclude the federal ARARs. Numbers listed should be updated to
incorporate current guidance. For carcinogens, numbers are based on the 10'cancer risk. For noncarcinogens, numbers are based on the
reference dcse. All numbers are calculated for a 17-kg child ingesting 0.2 gms of soil per day.
'The listed values are the Contract Required Quantitation Limits (CRQLs,) taken from the CLP SOWs (Level IV). TiusCRQL is matrix
dependent and may not be achievable. in every sample. The actual reporting limit will also be affected by moisture content for soil and
sediment samples. Some samples are analyzed as received but reported on a dry-weight basis. Since reporting limits in some cases are at or
above levels of concern, SAS reporting limits (Level V) maybe required to achieve lower detection limits (e.g., vinyl chloride).
'Sample collection procedures are outlined in the^4 Compendium ofSuperfund Field Operations Methods^Mgust 1987.
'Level I analyticlal methods are not compound specific, only quantitative for total organics. Not used for soil investigation.
A6-6

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                                                       Table 6-2
                 DATA QUALITY OBJECTIVES SUMMARY FOR HOT SPOTS, FILL, AND CAP INVESTIGATION
                                           OF THE EXAMPLE LANDFILL SITE
                                                                                                             Page 2 of 3
      Data  Quality
   Objective Elements
         Hot-Spot Areas
Levelll-FieldAnalysis '
  TCE
  Vinyl chloride
  Lead
  Arsenic
  Chromium'
 GC/ECD/PID
 GC/ECD/PID
 X-ray Fluorescent
 X.ray Fluromcerrce
 X-ray Fluroresscence
Level III-Non-CLP Lab
Methods8
Level IV-CLP RAS
  TCE
  Vinyl chloride
  PCB
  Lead
  Arsenics
  Chromium
 CLP Organic SOW
 CLP Organic SOW
 CLP Organic SOW
CLP Inorganic SOW
 CLP Inorganic SOW
 CLP Inorganic SOW
Level V--CLP SAS"
Other
  Moisture Content
  Permeability
  In Sity Density'
  Atterberg Limits
  Grain Size Analysis
  BTU content
  TCLP
                                  ASTM 2216-80
                                  SW 846, Method 9100

                                  ASTM D4318
                                  ASTM D422
N/A
SW 846, Method 9100)
N/A
N/A
N/A
PARCC  Parameters
• Precision1
  -  TCE
     Vinyl chloride
  -  PCB
  -  Lead
  -  Arsenic
  -  Chromium
 <20
 + -25%
 ±25%
 ±20%
 ±20%
 ±20%
• Accuracy"
   -  TCE
   - Vinyl chloride
   -  PCB
   -  Lead
   -  Arsenic
   -  Chromium
 62-137%.
 75-125%
 75-125%
 75-125%
 75-125%
 75-125%
'Levelll methids used by the indite mobilve laboratory and soil gas analysis.
'Only total chromium will be detected.
gLevel III analysis is only for parameters not on the CLP TLC and TAL lists and for where QC requirements are less stringent than
 those of the CLP methods. Level III will not be used for these media.
'Level V—CLP SAS methods may include modified versions of CLP RAS methods to achive lower detection limits, to provide project-
 specific QC, to analyze for non-CLP parameters, or to use non-CLP methods, but they still provide the levels and types of QA/QC and
deliverables prevented by CLP RAS. Level V will not be used for these media.
'Method reported in Methods  for Soil Analysisy, Sectionl3.2.
'The listed values for precision and accureacy in analysis of soil,sediment and water samples are based on CLP RAS SOW requirements and
 do not necessarily reflect actual method performance. Precision and accuracy performance for landfill gas samples are method dependent
 and should be determined on a project-specific basis.
                                                           A6-7

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DATA QUALITY
Data Quality
Objective Elements
• Repersentativeness1
« Completeness
> Comparability"
Table 6-2
OBJECTIVES SUMMARY FOR HOT SPOT, FILL AND CAP INVESTIGATION
OF THE EXAMPLE LANDFILL SITE
Page 3 of 3
Hot-Spot Areas

Fill

Caplnvestigation

'Qualitative parameter, which considers the project as a whole. No numerical criteria can be set.
'Can be expressed as a quantitative assessment of the percentage of valid data received. Also includes a qualitative parameter and must be
assessed after all data are reviewed.
'A qualitative parameter that can be maximized through the use of standard sampling, analysis, and data review techniques.

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Table 6-3
DATA QUALITYOBJECTIVES SUMMARY FOR SURFACE WATER, SEDIMENT
AND LANDFILL GAS OF THE EXAMPLE LANDFILL SITE
Page 1 of 3
Data Quality
Objecitve Elements
Objective
SurfaceWater
Evaluate, impact of surface water
runoff from the site to the
unnamed tributary
Sediment
Evaluate impact of surface water
runoff from the site to the
sediment of the unnamed
tributary
Landfill Gas
Identify areas within the landfill
containing high concentrations of
selected VOCS. Identify landfill
gas contaminant concentration at
perimeter of site to evaluate impact
from offsite migration.
Data Quality Factors
Prioritized Data Use(s)
Contaminants of
Concern
Site characterization, ,.
risk assessment
TCE, PCB, lead, arsenic,
chromium
Site characterization
TCE, PCB, lead, arsenic,
chromium
Site characterization
Methane, TCE, vinyl chloride
Level of Concern (ARARs)'
TCE
Vinyl chloride
PCB
Lead
Arsenic
Chromium
Methane
2.7 ppb
2.0 ppb
0.000079 ppb'
50 ppb
0.0022 ppb
50 ppb
N/A
634 ppb
0.3 ppb
0.091 ppb
105 ppb
0.35 ppb
(III) 75,000, (IV) 375 ppb
N/A
N/A
N/A
N/A
N/A
N/A
N/A
No federal ARARb
Reporting Limit
TCEd
Vinyl chloride'
PCB
Lead
Arsenic
Chromium
Methane'
Appropriate Analytical
Levels
Critical Samples
5 ppb
10 ppb
0.5 ppb
5 ppb
10 ppb
10 ppb
N/A
Site characterization and risk
assessment: IV and V
Samples from the groundwater
and leachate seeps"
5 ppb
10 ppb
80 ppb
500 ppb
1,000 ppb
1,000 ppb
N/A
Site characterization: IV
Samples from the groundwater
and leachate seeps
N/A
N/A
N/A
N/A
Site characterization: 111
Samples from areas of the landfill
where it is suspected that methane
gas is produced
N/A~Not applicable.
"Surface Water— These are based on theFederal Ambient Water Quality- Crireria, a nonenforceable guidance document under the CWA and
are either based on toxicily protection (lead, chromium) or the 10'cancer risk level. The selected criteria are the chronic criteria for
protection of Aquatic life. The level of concern for chromium is for both the total and hexavalent species. While federal ARARs are
stated for this example, state ARARs may preclude federal ARARs if they are more stringent.
'Several states have air toxic emissions regulations. Guidance on air ARARs can be found in the National Air Toxic Information
Clearinghouse Database Report on state,, local, and EPA air toxics.
'The listed values are the Contract Required Quantitation Limits (CRQLs) taken from the CLP SOWs (Level IV). This CRQL is matrix
dependent and may not be achievable in every sample. The actual reporting limit will also be affected by sample moisture content for
sediment sample. Some sample are analyzed as received but reported on a dry-weight basis. Since reporting limits in some cases are at
or above levels of concern,SAS reporting limits (Level V) may be requiredto achieve lower detection limits (e.g vinyl chloride).
d Thereporting limit for TCE, vinyl chloride, and methane is dependent uponnthe volume of gas sampled and should be established for
each sampling event.
A6-9

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                                                        Table  6.3
                       DATA QUALITY OBJECTIVES SUMMARY FOR SURFACE WATER, SEDIMENT
                                AND LANDFILL GAS OF THE EXAMPLE LANDFILL SITE
                                                                                                              Pagc2of3
      Data Qualfty
    Objective Elements
        Surface Water
                                          sediment
                                                                         Landfill Gas
Data Quality Needs
Sample/Analysis
Procedures
• Sample'  Collection'
• Sample  Analysis
LevelII--Field  Screenin0
Level II—Field Analysis5
Level III-Non-CLP Lab
Methods*
  Methane
   TCE
   Vinyl chloride
   TSS
   Alkalinity
   Hardness
   TOC
   Grain Size Analysis
   %.  Moisture
   % Solids
N/A
N/A
N/A
EPA 209
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A

ASTM D422
T014
1014
1014
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Level IV-CLP RAS'
   TCE
 Vinyl chloride
   PCB
   Lead
   Arsenic
   Chromium
CLP Organic SOW
CLP Organic SOW
CLP Organic SOW
CLP Inorganic SOW
CLP Inorganic SOW
CLP Inorganic SOW
CLP Organic SOW
CLPOrganic SOW
CLP Organic SOW
CLP Inorganic SOW
CLP Inorganic SOW
CLP Inorganic SOW
LevelV-CLP SAS1
   Toxicity Tests'1
Other
   Eh
   PH
   Specific Conductance
Eh Meter
pH Meter
Conductivity Meter
EPA 9045
pH Meter
EPA 126.1
N/A
N/A
N/A
N/A—Not applicable.

 'Sample collection procedures are outlined in the A Compendium of SuperfumdField Operations Methods, August 1987.
 'Level I analytical methods are not compound specific, only quantitative for total organics. Level I will not be used for the surface water
    sediment, and landfdl gas media.                             I «
 g Level II will not be used for analysis of the surface water, sediment or landfill gas sample
 'Level III analysis is only for parameters not on the CLP TLC and TAL lists and for cases where QC requirements are less stringent than
    that of the CLP methods. Level III analysis is not applicable for the selected contaminants of concern listed except-for TCE and VC in
    landfill gas.
 'CLP RAS methods are not currently available for landfill gas. These samples will always be analyzed by Level  III methods.
 J Level V-CLP SAS methods may include modified versions of CLP RAS methods to achieve lower detection limits, to provide project-
    specific QC, to analyze for non-CLP parameters, or to use non-CLP methods but still provide the levels and types of QA/QC and
 'deliverables prevented by CLP RAS. Some standard SAS methods are reported for landfill gas.
    Acute and chronic bioassays are done for surface water with invertebrate, vertebrate and plant species. For sediments, EP toxicity tests
    are done.
                                                           A6-10

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Table 6-3
DATA QUALfTY OBJECITVES SUMMARY FOR SURFACE WATER SEDIMENT
AND IANDFILL GAS OF THE EXAMPLE LANDFILL SITE
Page 3 of3
Data Quality
Objective Elements
Surface Water
Sediment
Landfill Gas
PARCC Parameters
• Precision1
- TCE
Vihyl chloride
- PCB
Lead
- Arsenic
Chromium
Methane
• Accuracy"
TCE
- Vinyl chloride
- PCB
Lead
- Arsenic
- Chromium
- Methane
• Representativeness"
• Completeness"
• Comparability0
< 14
+25%
±25%
+ 20%
±20%
±20%
N/A
75-125%
N/A
N/A
N/A
N/A
N/A
N/A

<20
±25%
±25%
+ 20%
±20%
+ 20%
N/A
62-137%
75-125%
75-125%
75-125%
75-25%
75-125%
N/A




N/ A—Not applicable.
'The listed values for precision and accuracy in analysis of water samples are based on CLP RAS SOW requirements and do not
necessarily reflect actual method performance. Precision and accuracy performance for landfill gas sample are method dependent.
"Qualitative parameter, which considers the project as a whole. No numerical criteria can be set.
"Can be repressed as a quantitative assessment of the percentage of valid data received. Also icludes a qualitative parameter and must
be assessed after all data are reviewed.
0 A qualitative parameter that can be maximized through the use of standard sampling, analysis, and data reviewtechniques.
A6-11

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                                        Section 7
                                    RI/FS TASKS
The field investigation is conducted to provide
data that can be used to determine the type and
extent  of contamination at the  site and  to
identify if the site poses risks to human health
and  the environment.    The RI/FS  tasks
described  in this work plan have been devel-
oped to meet these objectives.  This section of
the work plan follows the standard format out-
lined in the RI/FS Guidance (U.S. EPA, 1988a).
Several of these activities  were  conducted
before  developing  this work plan. These activi-
ties include the evaluation of existing data and
the performance of limited field investigations.
The  results  of both  of these activities are
reported in Section 2 and 3, respectively, of this
'appendix.
           7.1  RI/FS Tasks

The following tasks have been identified for the
RI/FS:

  •   Task I—Project Planning

  •   Task 2~Community Relations Activities

  •   Task  3-Field Investigations

           Subtask 3A~Fieldwork Support

           Subtask    SB—Surveying  and
           Mapping

           Subtask   3C--Geophysical
           Investigation

           Subtask 3D~Soil Gas Survey

           Subtask 3E~Cap Investigation

           Subtask 3F~Source Testing, Test
           Pits, Soil Samples (perimeter)

           Subtask  .3 G--Hydrogeologic
           Investigation
           Subtask  3H--Groundwater
           Sampling

           Subtask  31-Residential    Well
           Sampling

           Subtask  3J—Surface  Water and
           Sediment Sampling

           Subtask 3K~Landfill  Gas Emis-
           sions Sampling

           Subtask  3L-RI-Derived  Waste
           Disposal

  •   Task 4~Sample Analysis/Data Validation

  •   Task 5-Data Evaluation

  •   Task 6~Risk Assessment

  •   Task 7~Remedial Investigation Report

  •   Task     8~Remedial     Alternative
      Development

  •   Task 9~Alternatives Evaluation

  •   Task 10-Feasibility Study Report

  •   Task ll~Treatability Studies

7.1.1 Task I—Project Planning

Included in this task  are limited field investi-
gation activities, existing  data  evaluation,
development of the work plan; obtaining appro-
priate approvals for the work plan,  budget, and
schedule;  preparation  of  the  sampling and
analysis plan  (SAP),  which consists  of the
Quality Assurance Project Plan (QAPP)  and the
Field Sampling Plan (FSP); preparation of the
Site Safety Plan (SSP); project management and
agency coordination;  obtaining easements and
permits, if necessary and meetings among EPA,
the State, and the contractor.
                                            A7-1

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Development of the RI/FS work plan includes
formulation of  DQOS,  identification of  the
necessary  RI/FS  tasks,  and  preparation  of
budgets and schedules for implementing  the
proposed RI/FS tasks.   Results of the existing
data evaluation  are presented in Section 2 of
this document and results" of the limited field
investigation activities reported in Section 3
were  utilized to  develop  the scope  of RI
activities.    Potential  ARARs  and remedial
action alternatives for the example site  are
discussed in Section 4 of this document. This
information was also utilized to develop the RI
scope.

A SAP will be prepared in conjunction with the
work plan that will include a QAPP, FSP, and
an SSP for the  proposed field activities. The
QAPP will  specify the analytical  procedures  and
the methods for analytical choices and data
reduction,  validation, and reporting. The FSP
will   indicate  proposed sampling  locations,
collection  procedures,  and the  equipment
necessary  for  sampling  and  testing.    The
procedures  outlined in  the  Compendium  of
Superfund Field Operations Methods (U.S. EPA,
 1987c) and the  Users Guide to the Contract
Laboratoy Program (U.S. EPA, 1988b) will be
used  to  develop the  FSP.   Sample custody
procedures,  including those related to chain-of-
custody, also will be delineated in the FSP and
will conform to the 'procedures detailed in the
National Enforcement  Investigation Center's
Policies and Procedures for Sample Control.
Preparation of the  SSP will also be based  on
historical information, OSHA regulations, and
corporate health  and safety policies.

At critical junctures of the project, it will also
be necessary to conduct meetings between EPA,
the contractor, and other appropriate parties to
discuss project deliverables and the schedule
and to evaluate the need for additional studies.
Table 7-1  summarizes the subject, frequency,
participants, and locations of proposed meetings
for all tasks.

7.1.2  Task 2—Community Relations Activities

A community relations plan will  be prepared
addressing activities that EPA will conduct with
residents and government officials involved with
the site.   The plan will contain the following
sections:

  •    Site description

.  •    History of the site

  •    Community  issues

  •    Objectives of the community relations
       plan

  •    COmmunity relations activities

  •    Schedule of community relations


Information  presented in the  plan will be
developed from previous work conducted at the
site and interviews conducted with federal, state,
and local officials and residents, as appropriate.

Public  meeting contractor  support  can be
provided by  issuing Agency-approved public
notices, supplying court recorders, and prepara-
tion of visual aids. In addition, project updates
will be  developed to provide  information
regarding project  status.  An update  will be
distributed   at  the  beginning  of  the field
investigation,  and  a second once the field
investigation is  complete.   A proposed plan
summarizing the alternative  selection process
and the preferred remedial action alternative
will be prepared for public comments. A final
fact sheet will be prepared after  the ROD is
signed to explain the remedial action alternative
selected for the site.

7.1.3 Task 3~FieId Investigation

All efforts to prepare for onsite work, with the
exclusion of sample analysis, are included in this
task.

7.1.3.1 Subtask 3A—Fieldwork Support

Fieldwork support  includes those  activities that
are necessary before the field activities can be
implemented. The following sections describe
these  activities  and include those associated
with subcontractor and equipment procurement
and site setup.
                                              A7-2

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Table 7-1
PROJECT MEETING SUMMARY FOR THE RI/FS AT THE EXAMPLE SITE
Task
Budgeted No . of Anticipated Point
Under Subject of Meeting Meetings in Schedule
1 Project kickoff meeting 2 Before initiation of project lasks



1 Project progress meetings 6 Quarterly for duration of RI/T3


I Public meetings 2 Before RI/FS initiation and following
EPA issuance of FS report, and public
review period and comment period
2 Community relations 3 Before RI/FS initiation, before issuing
organizational meeting proposed plan, and before issuing final
fact sheet
3 Discuss field activities 2 During field activieties

7 RI Outline Report 1 After RI field data is available
7 Draft RI report 1 After EPA review of draft RI report


8 RA screening 1 During RA screening

10 FS Outline 1 After RA screening
10 Draft FS report 1 After EPA review of draft FS report


Meeting Participants

Contractor EPA Region
Proj ect manager (PM), Remedial proj ect
task leaders manager (RPM),
technical advisors, proj ect
officer
PM, task leaders RPM and technical
advisors (as appropriate)

PM RPM, technical advisors


PM, ccommuniry relations RPM, risk assessment
specialist specialist

PM, semopr hydrogeologist RPM, hydrogeologist


PM, senior hydrogeologist, RPM, technical
risk assessment specialist specialists

PM, process engineer RPM, technical
specialists

PM, process engineer RPM, technical specialist



Anticipated
Other Meeting Location
Slale representative, EPA office and the silt
Nalural Resource
Truslecs, if appmprialc

State representative, 3 in EPA office
Natural Resourece 3 in contractor's office
Trustees, if apropriate
PRP and Stale Site
representatives

State representative EPA office


State representative EPA office or at site, if
necessary

State representative, EPA office
Natural Resource
Trustees, if appropriate
State representative Remedial contractor's office


State representative, EPA office
Natural Resource
Trustees, if appropriate
'Meeting  participants may vary depending  on the EPA  Region.

-------
Subcontractor Procurement.  Several of the
investigative activities that  will  be conducted
during the course of the RI will require services
typically  provided  by  contractors  other  than
those  scoping and  performing the  RI/FS.
Services  expected to be subcontracted are:

  I    Construction  of decontamination  pad

  I    Provision of  trailer for onsite office  and
       mobile  laboratory   and  hookups  of
       electricity  and  telephone

  I    Obtaining sample  bottles

  I    Surveying and  topographic  mapping

  I    Drilling  and installation of  monitoring
       wells

  I    Geophysical  studies

  I    Excavation  of hot spot area test  pits

  '    Fencing  of investigation  waste  storage
       area

  I    Commercial  laboratory  for engineering
       design analysis (BOD, COD,  etc.)

  I    Geotechnical  laboratory  analysis

  I    Removal  of  Rl-derived  waste,  if
       necessary

  I    Treatability  studies, as appropriate

Equipment Procurement  and Site Setup. This
element  involves securing  and  shipping  field
equipment  and health  and  safety  equipment/
materials onsite and  setting  up  an  onsite field
office trailer and  support  area.  A  mobile trailer
will be rented for use  as an onsite  office and for
storing  equipment  and supplies.   This  trailer
will  also house the  onsite  mobile  laboratory.
The  trailer  will be  equipped  with air condi-
tioning  (fieldwork  planned  for  the  summer),
telephone,  water,  and electricity.   A decontami-
nation pad will also be constructed.
7.1.3.2 Subtask 3B—Surveying and Mapping

A preliminary  search  for existing maps  and
aerial  photographs  from  sources such  as the
Department  of  Transportation  and the  U.S.
Geological Survey was  made  during the  evalua-
tion of existing data.   An aerial topographic
survey of the site and  surrounding area  will be
conducted.    This  aerial  survey  will be  field
checked by  a  ground  survey  crew who  will
establish a localized baseline and benchmark for
future  sampling and  to  tie-in new well  locations.
Stream contours will also be established  from
water  depths. The  topographic  site map cover-
ing the 60 acres of the site and  immediate sur-
rounding  area  will  consist of contour lines on
1-foot  intervals  and  use a scale  of 1"  = 75'.  A
topographic map with a  contour interval of
2 feet  and a scale of 1" = 100' will be developed
for a much broader area of 145 acres and will
include the  surface-water  drainage system.  The
locations of surface features  such  as power
lines, fences, and sewers will also be located on
the  site map  to  aid  in  the  geophysical
investigations.

7.1.3.3 Subtask  3C—Geophysical  Investigation

Surface geophysical  surveys will  be performed  in
the  southeast  section of the landfill.  The  pur-
pose of these studies  is  to  confirm suspected
landfill areas that may  contain buried hazardous
waste  drums, to aid in  selecting test pit  sites,
and to delineate the extent of the fill.  The need
for the geophysical  investigation was determined
during  the  scoping  activities  where  indications
of  a buried  drum  area were  identified  through
review of existing  aerial photographs and  inter-
views  with former  employees.  A magnetometer
survey  (total field and  vertical  gradient)  will  be
used to meet these objectives.   It  should  be
noted, however, that   landfills contain many
products other  than drums  that are made  of
metal.  Therefore, this  type of  investigation  is
used only when there is  evidence to  suggest
large  discrete  areas of drum  disposal. While
the survey  cannot specifically distinguish
between  drums  and other metal objects,  they
can delineate  areas of buried  metal masses.
Subsequent  investigations  such  as the  test pits
will  be used to further explore the  specific
nature of the buried  metal  and  to  investigate
                                                A7-4

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subsurface soil conditions below areas of waste
disposal.

Magnetometer Survey. A magnetometer survey
will  be conducted to determine the location,
extent,  and relative magnitude of the drum
disposal area. Before the survey, a 1100-foot by
40-foot grid will be laid out over the south-
eastern portion of the  landfill, which  encom-
passes the  area of  suspected drum  disposal
(Figure 7-1). A magnetometer base station will
also be established to monitor diurnal changes
in the magnetic field (for correction purposes).
Once the  grid  and base  station have been
located, magnetometer readings  will  be  col-
lected at  20-foot centers using an Magneto-
meter/Gradiometer. Any other readings made
from locations not marked by  a grid flag will be
located by positioning a marked tape or rope
along the  appropriate line.

The magnetometer survey will consist of total
field measurements and vertical magnetic gradi-
ent  measurements.  Vertical gradient data are
capable of higher resolution than the total field
data and will minimize  potential  noise prob-
lems. The total field and gradient data will be
collected  simultaneously.

Upon completion of the magnetometer survey,
data will  be corrected for the effects of the
diurnal changes in the  local magnetic field.
Once this has been done, a  magnetic contour
map will be prepared to interpret magnetic
anomalies.

7.1.3.4 Subtask 3D»Soil  Gas Survey

A soil gas survey will be conducted in conjunc-
tion with the magnetometer survey to locate the
boundaries  of the  drum disposal area.  The
magnetometer survey may be  inconclusive if the
number of drums per unit area is low or if the
drums are buried deeply.  A soil gas survey will
be concentrated in the southeast corner of the
landfill. A  soil  gas  survey,  coupled with the
mobile laboratory analysis of the soil gas for a
few selected VOCS, may provide immediate
information on  the lateral extent  of contami-
nation  of the soil  (primarily  in the liquid
solvent disposal  area) and possibly the ground-
water.   This survey may also minimize the
number of geotechnical borings and monitoring
wells that must be drilled or installed.

Soil gas ground probes will be used to save time
and expense. Ground probes will be driven to
the desired depth and a vacuum pump used to
draw a sample from the  probe. The soil  gas
samples will be collected in Tedlar bags.

Sample analyses will be furnished by an onsite
mobile  laboratory.   The laboratory will  use a
gas  chromatography with  a photoionization
detector.   Samples  will be analyzed for 1,1-
DCE, TCE, 1,1,1-TCA, and toluene.

Initially vertical profiles  of organic  gases
present in the soil pore spaces will be measured
and plotted at several locations. A sampling
depth of at least 4 feet will also be selected,
based on the measured vertical profiles.  How-
ever, sampling probe depth within the landfill
may be limited by the presence of buried drums
and extreme care must be exercised. Once this
constant sampling depth is established,  soil  gas
samples will be collected across a grid. Samples
will be collected on a 20-foot by 20-foot grid
laid out over an area measuring 200 feet by  200
feet. Initially, samples will be collected nearest
the suspected disposal location. Once the loca-
tion is identified, sampling on a 10-foot by 10-
foot grid will be done to more accurately identi-
fy  the  limits of the area.  In the event that
results from the initial vertical profiles do not
provide data to sufficiently locate the solvent
plume, the soil gas survey will be discontinued.
A maximum of 80 soil gas samples will be taken
in the initial effort. An additional maximum of
20 soil gas samples will be taken on a 100-foot
by 100-foot grid to identify the extent of the
groundwater contamination  south of the dis-
posal area. Depending  on the location of the
solvent disposal area, this survey may include
additional areas within the landfill.

7.1.3.5 Subtask 3E-Cap Investigation

The cap  covers the southern portion of the
landfill as shown in Figure 2-1. Because the
cap was  engineered and may be used as a
component of the final cover system, further
investigation on its  construction is warranted.
The objectives of the cap investigations are to:
                                              A7-5

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                                        SOIL COVER
                                                                    A
                                                   BURIED
                                                   DRUMS
                                                   AREA
                                              OFFICE

                                                   PARKING
                                                            R-5
LEGEND

    RESIDENTIAL WELLS

 X  TEST PIT LOCATIONS
                                                   R-4
                                   A7-6
Figure 7-1
CAP INVESTIGATION
TEST PIT LOCATION
EXAMPLE SITE

-------
  •    Determine the  permeability  of the
       existing cap

  •    Evaluate the susceptibility  to  damage
       from  freezing, drying, and erosion

  t    Determine thickness of existing cap

Permeability tests  performed on undisturbed
(Shelby tube) samples will be used to determine
the effectiveness of the cap as it currently exists.
Undisturbed and  remolded  sample permeability
and density tests will be compared to explore
the susceptibility of the cap soil to damage from
freezing and drying.    Characterization  and
permeability testing will also be used to support
evaluation of remedial alternatives such as con-
struction of a multilayer cap.  These objectives
can be achieved  as explained in the following
paragraphs.

A maximum of seven test pits (see Figure 7-1)
will be dug at the site to show the  constructed
cross section of  the cap. The visual extent of
cracking, layering, root-penetration and vege-
tation success will be noted when the pits  are
dug. The test pits will be hand dug or dug with
a narrow-bucket backhoe and are  expected to
be  about 2 feet deep. A nuclear density gauge
will be used to determine in situ  density and
moisture content  at various locations across  the
site. The quantity and locations of the nuclear
density tests will  be determined in the field.

Samples from the test pits will be sent to a
geotechnical laboratory for  analysis if it is
determined during the test pit program that the
cap is  a clay cap. A summary of the sampling
and analysis program is presented in Table 7.2.
The samples  will be tested for moisture  content
and will be characterized by grain size analysis,
and Atterberg limits.   One moisture-density
relation  test will be  performed using  a soil
sample taken from a representative test pit. A
flexible-wall permeability test will be performed
on  a remolded sample, compacted to 95  percent
maximum density at the optimum moisture con-
tent. This data will be used  to  determine  the
permeability of the existing cap and whether the
cap has the geotechnical properties  necessary to
be  used as a base if a new cap were constructed
over the existing  material.
Shelby tube samples will be taken at each of the
test pit locations.  The Shelby tubes will be
pushed using the backhoe bucket that is needed
for the hydrogeologic investigation.    If the
characterization tests  performed on the test pit
samples indicate markedly different soil  types,
additional Shelby tube samples may be  neces.
sary. Shelby tube samples will be analyzed for
in-situ  density and moisture.   Flexible-wall
permeability tests  will be performed on samples
taken from the Shelby tubes.

Geotechnical  laboratory  tests  will  require
monitoring  of the procedures and  equipment
being used.  Specifications for each test will be
prepared and included  as  part of the drilling
subcontract. The  drilling subcontractor will be
responsible for retaining a laboratory (with the
remedial contractor's approval) who is capable
of conforming to  the specifications. A  geotech-
nical engineer will visit the laboratory at least
once to review the procedures and  equipment
being used.

Also additional permeability tests on different
locally available  soils or onsite soil-bentonite
clay mixtures will be performed. This is  neces-
sary because it is expected that a cap will be
needed for the currently uncapped northern sec-
tion of the landfill.  And  because  it  may be
necessary to upgrade the existing cap if it has a
high permeability or is geotechnically unstable.,

After the initial stage of geotechnical investi-
gation and sampling  is completed,  the results
will be evaluated to determine whether  or not
more fieldwork  is needed.    Results of the
permeability tests will be reviewed  along with
compaction tests. To fully  evaluate  capping
alternatives, it will be  necessary to construct test
patches of the proposed cover material over the
landfill to determine the feasibility of achieving
the desired relative compaction.  Compaction
over the landfill may be an  issue because of
potential  problems   with  the soft  (refuse)
subgrade.

Landfill settlement will be monitored through-
out the RI by surveying changes in benchmarks
that were  installed during the Limited Field
Investigation.   If substantial settlement  is still
                                              A7-7

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Table 7-2
SUMMARY OF SAMPLING AND ANALYSIS PROGRAM FOR EXISTING CAP AND HOT SPOTS
Medium
Existing
Cap
Hot Spot
Analysis
Moisture Content1'
Permeability Test1*
In Situ Density""
Alterberg Limits""
Grain Size
TCL BNA Extractables
TCL Pesticides/PCBs
TCL Volatile Organics
TAL Inorganic
Cyanide
Mercury
Target
Detection
Limits
—,



.-
CRDL
CRDL
CRDL
CRDL
CRDL
CRDL,
Proposed Ajma;utocal
Method
ASTM 2216-80
SW 842
Method 9100
-.
ASTM D4318
ASTM D422
Organic SOW87
Organic SOW87
Organic SOW87
Inorganic SOW88
Inorganic SOW88
Inorganic SOW88
Source of
Analysis
Geotech Lab
Geotech Lab
Geotech Lab
Geotech Lab
Geotech Lab
CLP-RAS
CLP-RAS
CLP-RAS
CLP-RAS
CLP-RAS
CLP-RAS
No of.
Samples'
7
7
7
7
7
36
36
36
36
36
36
Field and
Rinsate
Blanks



-.
-.
I/day
each
I/day
each
I/day
each
I/day
each
I/day
each
I/day
each
Trip
Blanks"

-
-.
.-
.-


I/day
-

.-
Replicates
.-

-.
-
-
1/20 samples
1/20 samples
1/20 samples
1/20 samples
1/20 samples
1/20 samples
Additional
Volume Needed
for
QA/QC Lots.
.-


.-
.-
Double volume
per 20 samples
Double volume
per 20 samples
Double volume
per 20 samples
Double volume
per 20 samples
Double volume
per 20 samples
Double volume
per 20 samples
CRDL.--Conkact Required Detection Limit
TCL .—Target Compound List
TAL, -Target Analyte List
RAS, — Rouline Analytical Service
CLP, — Cpmtract LaboratoryProgram
SNA-Base Neutral and Acid
"Geotechnical test samples correspond to one sample per cap investigation test pit. Analytical samples for the hot spot aruamw^espond to 12 samples per source (hot spot ) test pit.
'Tripblanks are only necessary for volatile organic samples.
CQC samples arc not collected for geotechnical samples. Sample results are reviewed by an experienced geotechnical engineforfcf conformity with the specified ASTM method.
d The proposed analytical method for in situ density is reported in Mehods of Soil Analysis,Section 13.2.

-------
occurring, then a temporary cap may need to be
designed and installed until the settlement rate
has decreased.

7.1.3.6 Subtask 3F-Source Testing, Test Pits

The objectives of the source testing program
are: (1) to evaluate the intergrity of the buried
drums, (2) determine the extent of contamina-
tion of unsaturated soil in the solvent disposal
area,  and (3)  determine  the  approximate
volume of the hot spot(s). The test pit excava-
tion will  be  done in the one-half acre area
believed to be used for drum disposal. Person-
nel will conduct sampling of the  test pits in
Level B protection.

Test pit depths are limited by the stability of
subsurface materials and the maximum depth of
the backhoe.    Backhoes typically can reach
depths of at least 25  feet  below grade, but
actual test pit depths are expected to be less
because of soil stability limitations. For this
reason, the maximum depth  of test pits is esti-
mated to  be  20  feet below grade.   Specific
excavating equipment cannot be identified until
an excavating contractor has been selected, but
it will probably be a track-mounted backhoe.
Three test pits in the southeastern section of
the landfill will be logged and photographed to
document the subsurface conditions encount-
ered.  No attempt will be  made  to  enter  the
pits, and samples will be collected directly from
the backhoe bucket. Excavated portions of the
existing cap will be kept for replacement of the
cover and the excavated waste will be placed on
plastic sheets in  a separate  area from that of
the cover material to prevent contamination of
surface  soils.

If intact or crushed drums are encountered, the
field  excavation crew will leave them undis-
turbed. Drums will not be removed from test
pits.  Drummed materials will not be  tested
unless drums are degraded and  leaking,  as
visually evidenced by the presence of liquids in
the test pits around the drums; samples will be
obtained from the backhoe.   If a free-floating
liquid layer is found, the pit will be  lined with a
sorbent material and closed  immediately after
samples of the liquid are collected.
Following completion of sampling and test pit
logging, each test pit will be backfilled to grade.
If a strong contaminant profile is observed in
the test pit wall, the field excavation crew will
backfill the test pit to roughly the same condi-
tion it was in before excavation. The most con-
taminated material  based on HNu screening,
will be backfilled into the test pit first with the
least contaminated going in last. Any remain-
ing excavated materials that can not be placed
into  the  test  pit will  be left at the test pit
location and covered  with clean  clay  fill
obtained from an offsite borrow area.

The  qualitative  data obtained from the field
screening will be used in conjunction with visual
and stratigraphic information derived from the
test  pit  logging to select  soil  samples  for
submittal to the  CLP for analyses. The chemi-
cal information obtained from the CLP analysis'
will  be compared to the groundwater  plume
data to  identify  groundwater contaminant
source areas. The  chemical information will
also  characterize the type and concentration of
contaminants in the source areas.   This soil
information  is necessary to characterize  the
potential for  future contaminant releases to the
groundwater and to  evaluate  containment, treat-
ment, and disposal alternatives for the hot spot
in the FS.

The proposed location of the test pits is shown
in Figure 7-2.   A  maximum of 36 test pit
samples will be submitted for TCL and TAL
analyses. This number assumes a maximum of
 12 samples each from the three test pits. The
actual number of samples will depend on field
observations and actual test pit depth. Samples
will  be considered  as having low or medium
concentrations, depending on the HNu readings.
Sampling methods  and protocol will be dis-
cussed in detail in the SAP.  Some or all of the
soil  samples may be depth-interval samples.
Samples will be selected by depth, based on
visual  observations (e.g.,  soil  staining);  the
concentrations  or  types  of VOCs detected
during the soil  gas survey  and stratigraphic
relationships. The  sampling team leader will
decide on the depth interval after consultation
in the field with  the project hydrogeologist and
chemist.   A  summary of the sampling and
analysis  program  is presented in Table 7-2.
                                             A7-9

-------
                                                  BURIED
                                                  DRUMS
                                                  AREA
                                 GATE-^
                                 HOUSE JL
                             R-3
LEGEND

    RESIDENTIAL WELLS

    SOURCE TEST PITS
                                 A7-10
Figure 7-2
SOURCE TEST PITS
LOCATIONS
EXAMPLE SITE

-------
information on health and safety concerns for
test  pit   excavations  can  be  found   in
Compendium  of Superfund Field Operation
Methods(U.S. EPA, 1987c).
7.1.3.7      Subtask
Investigation
3G--Hydro geologic
The purpose of the hydrogeologic investigation
is to accomplish the following:

  «    Refine the  conceptual model of the
       groundwater flow system in relationship
       to underlying hydrostratigraphy

  •    Evaluate the aquifer properties and its
       response to pumping

  •    Locate monitoring wells for the collec-
       tion of analytical data-to define the type
       and extent of contamination

  •    Provide information on pathways for use
       in the risk assessment

Based on thorough review of existing data the
following investigations are,,  intended to  fill in
the data gaps and thereby fulfill the objectives
listed above.

Geotechnical Borings, To refine the conceptual
model and the subsurface stratigraphic relation-
ships, and to aid in delineating the extent  of the
VOC plume in the vicinity of the landfill, eight
soil borings will be drilled and  sampled
(Figure 7-3). The rationale and proposed depth
of each boring is presented in Table 7-3. The
number  and location  of borings may change
depending on the results of the initial borings.
For instance, if soil contamination is found in
borings west or east of the site, based on field
observations and soil gas  probe readings,
additional borings would be installed  upgradient
northwest or northeast of the landfill.  In the
event that the stratigraphy is more  complex or
the  groundwater  contamination more  extensive
than that presented in the evaluation of existing
data,  a  maximum of 16 more geotechnical
borings may be required. The location for these
borings will be based  on  the information
developed from  the initial eight soil borings.
All borings will be advanced using a 6.25-inch
(ID), screened hollow-stem auger. EPA will be
responsible for obtaining easements and permits
at all offsite locations.

Three of the soil borings will be advanced to
bedrock, which is expected to be approximately
135 feet below ground surface. The other five
borings  will be advanced to a depth of about 70'
feet below ground surface to determine the stra-
tigraphy of the fill units beneath  the  south
portion  of the landfill and south of the landfill
in the 'vicinity of the potential groundwater
migration pathways.  Each geotechnical boring
will be sampled at 5-foot intervals using  a
standard split-spoon sampler following ASTM
Standard D-1586 for the Standard Penetration
Resistance Test. Boreholes where monitoring
wells are not installed will be abandoned by
injecting a thick  bentonite slurry  from  the
bottom  of  the  borings to the ground surface
using the tremie method.

Each boring will be logged by an experienced
geologist,  geotechnical  engineer, or  soil
scientist. Samples  will be. described using the
Unified Soil Classification System terminology.
Samples will be collected for grain size analysis
and/or Atterberg limits based on changes in
stratigraphy. The decision to submit a sample
for geotechnical analysis will be made in the
field by the supervising geologist, engineer, or
scientist but in  no case will  exceed  three
samples per boring.

Information  obtained from  the  soil  boring
program will help to  determine the need for
additional monitoring wells and the depths at
which monitoring  wells will be  installed. This

identify potential  migration pathways and to'
evaluate the  fate  and transport  of released
contaminants.

Drill cuttings generated during the soil boring
program will be collected and stockpiled onsite.
These cuttings will be covered with clean clay
fill obtained from an offsite borrow area. The
cuttings will be consolidated with other waste
under the final cap for the landfill.

-------
                                                                      A
          0B-3


LEGEND

    RESIDENTIAL WELLS

    SOIL BORINGS:

 •  BEDROCK DEPTH

 O  70-FOOT DEPTH
R-3
                                                     BURIED
                                                     DRUMS
                                                     AREA
                                                                 B-5
                                                 FFICE

                                                   T PARKING
                                                                   B-8
                                                          .B-7
                                                              R-5
                      a
                    R-4
    A7-12
Figure 7-3
SOIL BORING
LOCATIONS
EXAMPLE SITE

-------
Table 7-3
RATIONALE FOR SOIL BORING LOCATIONS FOR
THE EXAMPLE SITE
Boring Location
B-l
B-2
B-3
B-4
B-5
B-6
B-7
B-8
Proposed Depth
Bedrock
70 feet
70 feet
70 feet
Bedrock
70 feet
70 feet
Bedrock
Rationale
• Stratigraphy in west side of site where data are
scarce, helps determine screen interval for
monitoring wells
• Stratigraphy in SW portion of the site where
data are scarce, helps determine screen interval
for monitoring wells
• Helps determine location of downgradient
monitoring nest
• Helps determine location of downgradient
monitoring nest, stratigraphy in SW corner of
site where data are scarce
• Stratigraphy of potential migration pathways,
helps locate monitoring wells, extent of
contamination
• Stratigraphy of potential migration pathways,
helps locate monitoring wells,, extent of
contamination
• Downgradient stratigraphy, helps locate
monitoring wells, extent of contamination
• Stratigraphy in SE portion of the site, where
data are scarce
A7-13

-------
Monitoring Well Installation. To better define
potentiornetric relationships in the vicinity of
the site and evaluate the extent of groundwater
contamination, 15 new monitoring wells will be
installed and one existing well nest will be used.
An onsite laboratory will be used during well
installation to provide analytical results that will
be used to reevaluate the proposed monitoring
well network. Groundwater samples will be
analyzed  for selected VOC.s  and  inorganic
anions (chloride and  sulfate) to aid in deter-
mining the extent of the groundwater plume.
The inorganic anions are persistent chemicals
which can be used as indicators of leachability
and transport.   Therefore,  mapping elevated
levels of these indicator chemicals relative to
upgradient concentrations  can  give a more
accurate  picture  of the movement of the
groundwater and possible extent of the con-
taminant  plume  than just VOC  analysis.
Because  of volatization,  adsorption   and
degradation,  VOCs may diminish in concentra-
tions  more rapidly than the inorganic ions.

Potential locations for the new wells are shown
in Figure  7-4. The rationale for each location
is presented in  Table  7-4.  This rationale  is
based on the  assumption that subsurface condi-
tions  are  homogeneous. If  subsurface condi-
tions  are heterogeneous, additional wells may
be necessary. Also, based on the conceptual
sire model, it is  possible that the horizontal or
vertical extent of groundwater contamination
may  be  greater  than that estimated from
existing data and the results of the  VOC and
inorganic ion analysis to be  done by  the onsite
mobile  laboratory,  therefore  an additional
number of monitoring wells may be necessary.
For purposes of this work plan, a maximum of
 15 additional wells are estimated. The need for
these wells and their locations will be assessed
in  the  field by  the project manager  in
conjunction with EPA's RPM.

One  two-well  monitoring well nest will be
installed upgradient (background) of the landfill
to determine upgradient groundwater quality.
A second monitoring  well nest  (with  three
wells), in  addition to the existing onsite landfill
well nest,will be installed just off the  southwest
corner of the landfill to evaluate groundwater
quality within the landfill. Because there is an
existing well nest" onsite, and for health and
safety reasons, installing an additional well nest
onsite is not proposed. A third (two-well) and
a  fourth  (three-well)  nest is proposed to
measure downgradient groundwater quality.
Three single wells are proposed to measure the
westward,  eastward and  southerly  extent of
groundwater contamination and to investigate
the possible groundwater mound. One two-well
monitoring well nest is proposed to evaluate the
vertical distribution  of contaminants down-
gradient of the landfill and to determine if a
vertical gradient exists.

At least six of the remaining monitoring  wells
will be  installed in  geotechnical  borings
described earlier. These monitoring wells will
be installed immediately after completion of the
geotechnical  borings  at  each  location.  The
elevations  of each monitoring well measuring
point will be  determined  and  water  levels
recorded.  This  information is needed to
determine  the groundwater flow system. The
information obtained from completion of this
task will be important to the analysis of the fate
and transport of constituents released from the
landfill and to the identification of contaminant
migration pathways.

The boreholes for the monitoring wells will be
advanced using screened hollow-stem augers
(6.25-inch ID).    This size allows  sufficient
annular space between the well and the  auger
wall to introduce' a filter pack and  seal.  If
alternative drilling methods are required, only
methods using clear water, air, or cable tool will
be considered.

Following installation, each monitoring well will
be developed  until substantially free of
sediment,  and until pH and  conductivity  are
stable  to the  satisfaction  of the project
hydrogeologist. Wells will be developed using
the surge-and-bail method. Well development
water will be discharged as described  under
Section 7.1.3.12~RI-Derived Waste Disposal.

During installation  of  the  15  new wells,
groundwater samples will  be collected from
three depths (water table,  mid-depth,  and  above
bedrock)  at each location. These samples will
be analyzed by the onsite mobile laboratory for
                                             A7-14

-------
                                      w
                       MW-1S _
                         MW-1M
   r^/
                     BURIED
                     DRUMS
                     AREA
                /-6M
                  FFICE
                     PARKING
                            _MW-8S

                            MW-8M

                              R-5
                                 £
            MW-3D

LEGEND

    RESIDENTIAL WELLS

    EXISTING ONSITE WELLS

    PROPOSED MONITORING WELLS

    PRODUCTION WELL
                      o
R-3
                    R-4
    MW-7M
    A7-15
Figure 7-4
PROPOSED MONITORING
WELL LOCATION
EXAMPLE SITE

-------
Table 7-4
RATIONALE FOR MONITORING WELL LOCATIONS
Well Number
MW-1S
MW-1M
MW-2S
MW-2M
MW-2D
MW-3S
MW-3D
MW-4S
MW-4M
MW-4D
MW-5M
MW-6M
MW-7M
MW-8S
MW-8M
Proposed Depth
45 feet
90 feet
45 feet
90 feet
135 feet
45 feet
135 feet
45 feet
90 feet
135 feet
70 feet
70 feet
70 feet
45 feet
70 feet
Rationale for Location
Can monitor quality of upgradient groundwater
(background)

Can monitor quality of groundwater migrating from the
landfill (Samples till also be collected from existing
onsite well nest.)


Can monitor quality of downgradient groundwater and
depth of contamination

Can monitor quality of downgradient groundwater


Can monitor westward extent of groundwater
contamination
Can monitor eastward extent of groundwater
contamination
Can monitor southward extent of groundwater
contamination
Can monitor quality of downgradient groundwater and
depth of contamination

Note: Location of monitoring wells are dependent on results front the onsite mobile
laboratory and soil gas analysis if performed.
A7-16

-------
four selected VOCs--l,l-dichloroethene  (1,1-
DCE), trichloroethene  (TCE),  1,1,1-trichloro-
ethane (1,1,  1-TCA),  and toluene,  and two
inorganic ions-chloride and sulfate. The results
will be plotted on site maps and will be used to
evaluate the new monitoring well network.  If
the analytical results  indicate high levels of the
four VOCS and the two inorganic ions from the
downgradient wells, then additional downgradi-
ent wells will be installed.

Water Level Monitoring. All new monitoring
wells will be surveyed to establish horizontal
location and elevation of the measuring points.
Elevation measurements will be taken on the
riser pipe with the measuring point designated
by a chisel  mark.   All  elevations  will  be
referenced to the  benchmark previously estab-
lished at the  site. All  wells will be located
horizontally to within plus or minus 5 feet.
Vertical elevations of measuring points will be
made to the nearest 0.01 foot.

Water levels will  be collected at a maximum of
one a month from new and existing monitoring
wells for the duration of the  RI.   This  is
assumed to  be 5 months.  An electric water-
level indicator graduated in 0. 1-foot increments
will be used.

Aquifer Tests. The purpose of the aquifer tests
is to determine the physical characteristics  of
the underlying aquifer sufficiently  to allow
evaluation of groundwater collection alterna-
tives. Both pumps tests and slug tests will be
conducted.

This pump test is important for understanding
how the aquifer responds to pumping given the
site's proximity to constant-head boundaries.  A
6-inch (minimum) ID, fully penetrating produc-
tion  well  would  be  drilled using mud  rotary
techniques for the purpose  of conducting a 72-
hour pump test. Eight monitoring wells will be
used as  observation  wells for this  test.
Groundwater samples will  be collected during
the pump test for  analysis of CLP routine
analysis of  TCL organic and TAL inorganic
packages. The layout of the pump and  observa-
tion wells that will be used for the test is  shown
by Figure  7-4. The production well will be
located in an area where it could be used later
as a groundwater extraction well.  The final
location and depth of the screened interval will
be selected in consultation with the RPM after
screening results of the groundwater and soil
samples for the mobile laboratory are evaluated.

The pump test may generate up to 1,000 gpm
for 3  days. This volume of water (4.3 million
gallons) is too.  large to store onsite  and will
have  to  be discharged to the  local POTW.
Permission will  have to be obtained from the
POTW.  If permission is  not obtained, the
pump test will not be performed and the slug
test results  will  be  used to characterize the
hydraulic properties of the  aquifer.    The
disadvantage of using only slug tests is that
there  is a higher degree of uncertainty  in the
parameter estimates and the  influence of
constant head boundaries is not determined.

Slug tests will  also  be  performed to measure
in-field hydraulic conductivity. Slug tests will
be completed after  the wells are developed.
Tests will be conducted by either withdrawing a
known volume  of  water  or by  inserting a
cylinder  of known  dimension and recording
changes in water level at the time.

7.1.3.8 Subtask 3H-Groundwater Sampling

Information obtained from the new monitoring
wells will  be   used to study  the  possible
groundwater mound and its effect on contami-
nant migration,  to determine the vertical and
lateral extent of the VOC contamination, and
to evaluate source containment and ground-
water extraction  and treatment alternatives.

After well installation  and recovery, ground-
water samples will be collected from the new
wells and from the existing landfill well nest.
Groundwater sample collection will begin with
the least  contaminated wells and conclude with
the most contaminated  to  prevent"  cross-
contamination of samples. Samples will be col-
lected from within the hollow-stem auger after
purging at least three well volumes to remove
stagnant water or stratified contaminants and
until the  pH and conductivity are stable. Purge
water will be collected or discharged on the
ground as  described  in Section 4.2.3.12-
RI-Derived Waste  Disposal.     Groundwater
elevations will  be measured before purging
wells.    Samples from each well will also be
                                            A7-17

-------
submitted to the CLP for analysis of routine
TCL  organic  and TAL  inorganic packages,
special  analytical service (SAS) for vinyl
chloride as well as for BOD, COD, TOC, and
IDS.  Efforts  will also  be made to identify
Tentatively Identified Compounds (TIC)  if they
are detected in significant concentrations since
they also could pose a human health risk. Field
parameters of pH, temperature, and specific
conductance will  be  measured  at the time  of
sample  collection.    Details  on  sampling
methods, collection of blanks and duplicates,
preservation of samples, and sample handling
and shipping will be presented in the SAP.

A second round of groundwater sampling will
begin 4 months after completion of the  first
round to verify the previous results.  Samples
will be  submitted to the  CLP  for  the same
analyses outlined above for round one. Field
parameters will also  be the same  as above. A
summary of the sampling and analysis program
is presented  in  Table  7-5.

7.1.3.9 Subtask 31-Residential Well Sampling

Residential wells in the vicinity of the landfill
are sampled to verify reported contamination,
to provide additional data as to the extent of
contamination, and to identify wells that may
not be affected by the contaminant plume.

To accomplish these  objectives, a total of nine
residential wells (shown in, Figure 7.5) will be
sampled during the two rounds of groundwater
sampling. Five wells (R1-R5) will be sampled
to provide additional data on  the  extent  of
groundwater contamination; the  four remaining
residential wells (R6-R9) are not anticipated to
be contaminated and will  be sampled only to
verify that contamination has not migrated to
them. Available information' on the 9 wells
including well depths and construction details
was collected during limited field investigations.

Grab  samples will be obtained  from the  cold
water taps, at a point prior to treatment,  after
the wells  have been  adequately purged  to
remove  stagnant water.    Samples will be
submitted  for CLP  analysis  of routine  TCL
organic  and TAL inorganic packages, except for
the vinyl chloride analysis, which will require a
special analytical service (SAS) request. Efforts
will also be made to identify TICS.

Homeowners will be contacted for permission
to sample. Their requests with respect to the
sampling  schedule will be adhered to at all
times. A well inventory form will be completed
for each well sampled.

7.1.3.10 Subtask 3J—Leachate Sampling

There is no existing data on either the observed
leachate seep  or leachate within  the landfill.
The  objectives of the leachate study  are  to
identify the approximate  amount of leachate
production and the  composition of the leachate.
Composition   information will be used  to
characterize the leachate  and to determine
compatibility   of  leachate treatment  with
groundwater  treatment.

The  leachate seep  located on the west side of
the  landfill will  be  sampled twice.    Grab
samples will be taken at the toe of the landfill.
One sample will be taken at the same time as
the surface water  sampling presented below.
The  other sample  will be taken in the spring
after a wet period when the flow from the seep
is higher than normal.  These  two  samples will
indicate   the  range  of composition of  the
leachate seep. Leachate seep samples will  be
analyzed  for  TCL organics,  TAL inorganic,
BOD, COD, pH, TDS, and oil and grease.

Water quality and  wellhead data  from  the
groundwater monitoring wells will be used to
aid in the estimation of leachate composition
and  production.   The  data from  the  shallow
well within the landfill will be a useful source of
this  data.  Sampling of these wells was covered
under Subtask 3H.  A summary of the sampling
and  analysis program is presented in Table 7-5.

7.1.3.11    Subtask  3K-Surface Water and
Sediment  Sampling

No existing data on surface water and sediment
contamination of the unnamed tributary to the
Polk River are  available.   As discussed in
Section 4.3 of this appendix, site contaminants
may have  migrated by way of surface runoff and
groundwater recharge. To determine if this has
                                            A7-18

-------
Table 7-5
SUMMARY OF SAMPLING AND ANALYSIS PROGRAM FOR GROUNDWATER



Medium
Groundwater






















Analysis
TCL BNA Extractables

TCL Pesticides/PCBs

TCL Volatile Organics
(prepurge and purged
samples)
TAL Inorganics
- Metals

- Cyanide

Biochemical Oxygen
Demand (BOD)
Chemical Oxygen
Demand (COD)
Total Dissolved
Solids (TDS)
Total Organic Carbon
(TOC)

Target
Detection
Limits
CRDL

CRDL

0.5 ppb



CRDL

CRDL



-

-

--


Proposed
Analytical
Method
625

625

524.2



200.7

335.2

507

410

209

415.1


Source
of
Analysis
CLP-RAS

CLP-RAS

CLP-SAS



CLP-RAS

CLP-RAS

Non-CLP

Non-CLP

Non-CLP

Non-CLP



No. of
Samples"
52

52

52



52

52

34

34

34

34

Field
and
Rinsate
Blanks
I/day
each
I/day
each
I/day
each


I/day
each
I/day
each
-

-

-

-



Trip
Blanks'


-

I/day


-




-

-

-

-




Replicates
1/20 samples

1/20 samples

1/20 samples



1/20 samples

1/20 samples

1/20 samples

1/20 samples

1/20 samples

1/20 samples

Additionial
Volume
Needed for
QA/QC Lots
Triple volume
per 20 samples
Triple volume
per 20 samples
Triple volume
per 20 samples


Double volume
per 20 samples
Double volume
per 20 samples


-

-

-

CRDL--Contract Required Detection Limit
TCL— Target Compound List
TAL— Target Analyte List
SAS— Special Analytical Service
RAS-Routine Analytical Service
CLP— Contract Laboratory Program
SNA-Base Neutral and Acid
TOC-Total Organic Carbon
'Two rounds of sampling from 26 wells (15 new wells, 2 existing wells, 9 residential wells). Only the 17 monitoring wells (not residential wells) will be analyzed for BOD, COD,
TDS, and TOC.
"Trip blanks are only necessary for the volatile organic samples.

-------
                                                              R-9
                                                   BURIED
                                                   DRUMS
                                                   AREA
                              R-3
LEGEND

    RESIDENTIAL WELLS
                                                  R-4
                                  A7-20
Rgure 7-5
RESIDENTIAL WELL
SAMPLING LOCATION
EXAMPLE SITE

-------
happened,  four  surface water  and sediment
samples will be collected from the stream and
submitted for CLP analysis  of routine TCL
organics and TAL inorganic  and toxicity
testing. One of the sampling locations will be
upgradient of the landfill to  determine back-
ground levels in the river. Two locations will
be along the  banks of the river closest to the
landfill  and  the remaining location will be
downgradient of the landfill. These locations
are shown in Figure  7-6. The  sampling will
occur  in midsummer  during  a period of
relatively    low  stream flow to  determine
maximum groundwater impact on the stream.
A summary  of the  sampling and  analysis
program is  presented in Table  7-6.

7.1.3.12 Subtask 3L-Landfill Gas Emissions
Sampling

Significant  amounts of methane and other gases
such as vinyl  chloride are typically generated by
decomposition of  the  materials  within  the
landfill.  These gases  will be sampled  during
Phase I to  support an evaluation of the extent
of gas migration into  the soil surrounding the
landfill and the rate of contaminant emissions
to  the  ambient air.     To  accomplish this
objective,  eight onsite  gas probes will be
installed within the  landfill,  six offsite  gas
probes will  be  installed  along the southern
border of the site near the residential area, and
three offsite gas probes will be installed along
the northern border. The proposed landfill gas
sampling locations  are shown in Figure 7-7.

The probes will be placed to a depth of at least
5 feet. The collection procedures for methane
gas are the same as those described in Section
7.1.3.4 for soil gas  sampling.
 7.1.3.13
 Disposal
Subtask 3M~RI-Derived Waste
 Wastes derived from the RI  field tasks will
 include:   drill cuttings from monitoring well
 installation; water  produced from  equipment
 decontamination, well  development, ground-
 water sampling,  and aquifer  testing.   Field
 clothes and assorted trash will also be stored,
 but separately from the other waste, for final
 disposal.
Cuttings will be generated as the monitoring
wells are drilled. Some monitoring wells will be
cored for their entire length;  therefore, most
material removed from these holes will be as
core and will be retained for logging and future
reference.  All cuttings will be collected  and
stockpiled  onsite.  These cuttings will need to
be  addressed  when the  final alternative is
implemented.

All  water  generated  during  equipment
decontamination and well development will be
stored onsite. Water from  the pump test will
need  to be discharged  to the  local POTW
because the quantities are too large for  onsite
storage.

Drilling   equipment   decontamination will
typically consist of high-pressure steam  cleaning.
An area will be designated at the  site for this
purpose and berms will be built around the area
for runoff control. The area will be lined with
an  HDPE  liner and the water collected for
storage.

7.1.4    Task 4~Sample Analysis and Data
Validation

7.1.4.1 Subtask 4A~Onsite  Mobile  Laboratory

This subtask includes mobilization, operation,
and demobilization of the mobile laboratory at
the landfill site. The mobile laboratory will be
used for screening groundwater and soil samples
for target VOCS using a  portable  gas
chromatography unit. All analytical data will be
tabulated and organized for agency review in
the field. The screening data will be used to
direct other field operations, including future
drilling on monitoring wells and  test pit
sampling.   Samples will be selected  for CLP
analysis based  on  screening results.

7.1.4.2  Subtask 4B~Data Validation

Upon completion of sample analysis, Sample
Management Office (SMO) receives  the  data
packages   from  the CLP laboratories  and
distributes them  to  the Contract  Project
Management Section (CPMS) of the Regional
Environmental Services Division (BSD). The
                                            A7-21

-------
                                                                  A
                                                 BURIED
                                                 DRUMS
                                                 AREA
                             R-3
LEGEND

    RESIDENTIAL WELLS

    SURFACE WATER
    SAMPLING SITES
                                 A7-22
Figure 7-6
SURFACE WATER
SAMPLING LOCATIONS
EXAMPLE SITE

-------
Table 7-6
SUMMARY OF SAMPLING AND ANALYSIS PROGRAM FOR
SURFACE WATKR, SEDIMENT, AND IANDFU.L CAS
Medium
1 -each ale
(Seep)
Surface Walcr
(Stream)
Sediment
(Stream)


landfill Gas
Analysis
TCL BNA Fjitraclables
TCI, Volatile Organics
TAL inorganics
TCL BNA Cxtraclables
TCL Volalile Organics
TAL Inorganics
TCL BNA I-xlraclables
TCL Volalile Organics
TAL Inorganics
Methane, TCE, VC
Target
Detection
Limits
CRDL
CRDL
cum.
CRDL
CRDL
CRDL
CRDL
CRDL
CRDL
*
Proposed
Analytical
Method
625
624
200.7
625
624
200.7
625
624
200.7
T014
Source
of
Analysis
CLP-RAS
CLP-RAS
CLP-RAS
CLP RAS
CLP-RAS
CLP-RAS
CLP RAS
CLP-RAS
CLP-RAS
non-CI ,P
No. of
Samples
2
2
T
4
4
4
4
4
4
17
Field
and
Rlnsale
Dlanks
t/day
each
i/day
each
I/day
each
I/day
each
I/day
each
I/day
each
I/day
each
I/day
each
I/day
each
-
Trip
Blanks

1/day
-
-
I/day

-
I/day

-
Replicates
1/20 samples
1/20 samples
1/28 samples
1/20 samples
1/20 samples
1/20 samples
1/20 samples
1/20 samples
1/20 samples
1/20 samples
Additional
Volume
Needed for
QA/QC Ixtls
Triple volume
per 20 samples
Triple volume
per 20 samples
! Jon We volume
per 20 samples
Triple volume
per 20 samples
Triple volume
per 20 samples
Double volume
per 20 samples
Triple volume
per 20 samples
Triple volume
per 20 samples
Double volume
per 20 samples
-
CRDL--Conlracl Required Deteclion Limit VC-VinyL Chloride
TCL--Targel Compound List R AS- -Routine Analytical Service
TAL-Targel Analyle List C LI'- Contract laboratory Program
TCE-Trichlorelliylene BNA-Base Neutral and Acid
'The large! detection limit for methane is dependent on Ihe volume
of gas sampled and should be established for each sampling event.

-------
Residential Wells
Landfill Gas Sampling Sites
                              A7-24
                                               Figure 7-7
                                               LANDFILL GAS SAMPLING
                                               LOCATIONS
                                               EXAMPLE SITE

-------
CPMS reviews all data packages resulting from
regional sampling efforts.

After the BSD-reviewed data packages are
received they will be reviewed before inter-
pretation by the project staff. Any data noted
in the review that  should be qualified will be
flagged with the appropriate symbol. Results
for field blanks and field duplicates will also be
reviewed (these may or may not be considered
by the CPMS) and the data further qualified if
necessary. The data set as a whole will also be
examined for consistency, anomalous results,
and whether or not the data are reasonable for
the samples involved.

Any limitations on the use of the analytical data
based on the  data review and the CLP QA/QC
comments will be identified.  Limitations of the
analytical data  will be  presented  in  the RI
report.

7.1.5 Task 5—Data Evaluation

Specific  analyses   and  evaluations to  be
performed under the  Data Evaluation subtask
will  include:

  •    Preparing groundwater contour plots for
       all identified hydrostratigraphic units

  •    Computing   vertical  and horizontal
       hydraulic gradients  and evaluating
       groundwater  flow direction in  each
       stratigraphic unit

  •    Generating figures showing spatial and,
       when applicable, temporal distributions
      of contaminants in soil and groundwater

7.1.6 Task 6—Risk Assessment

The risk assessment will be consistent with EPA
methods as  outlined in the  documents Risk
Assessment Guidance for  Superfund,  Volume I—
Human Health  Evaluation Manual. (Part A)
(U.S. EPA,   1989b)  and Risk  Assessment
Guidance for Superfund, Volume II—Environ-
mental Evaluation Manual (U.S. EPA, 1989c).
The results of the  assessment will be included
as a chapter in the RI Report. Supporting risk,
transport,   and fate  calculations will be
appended, and relevant references will be cited.
Based on the risk assessment, EPA will develop
cleanup levels to guide the selection of remedial
measures  for media where either  ARARs  do
not exist or where the ARARs are not protec-
tive. These proposed criteria will be developed
by EPA with contractor input on the technical
issues.

7.1.7 Task 7~Remedial Investigation Report

A report summarizing RI activities and findings
will be prepared and submitted to the EPA  for
review and comment.   Early chapters of  the
report summarizing the field investigation
activities  and  the  analytical  data  will  be
submitted to U.S. EPA  as early as possible to
aid in identification of ARARs which will be
finalized during the FS.  The RI report will also
be submitted to  the Agency for Toxic Substance
and Disease Registry to assist in  their health
assessment of the site.  The RI report will be
prepared in accordance with the current RI/FS
Guidance  (U.S.  EPA, 1988a).

7.1.8   Task S~Remedial Action Alternative
Development

The purpose of  developing remedial action
alternatives is to produce a reasonable range of
waste management options to be analyzed more
fully  in the detailed analysis of alternatives.
Developing alternatives includes the following
elements:

  •    Establishing remedial action objectives

  •    Developing general response  actions

  •    Identify  and screen technologies and
       process options

  •    Combining medium-specific  technologies
       to  form  alternatives

  •    Screening alternatives, if necessary

Section  4.1  of this appendix presents  the
preliminary identification of remedial actions
alternatives for the example site.  The prelim-
inary remedial action objectives and subsequent
remedial action alternatives  are based on results
of  the limited  site investigation,  preliminary
                                             A7-25

-------
remedial goals, experience at municipal landfill
sites, and engineering judgment.

These preliminary remedial action alternatives
will be refined on the basis of the information
collected during the RI. Additional alternatives
such as direct remediation of surface water and
sediments may need to be developed depending
on the  findings of the risk  assessment. As
required, a no-action  alternative will  also be
retained   through   the  development  and
evaluation of the alternatives process.

Sections 5 and 6 in the body  of this report
(Conducting  Remedial  InvestigationsJFeasibility
Studies for CERCLA Municipal Landfill Sites)
should be referred to for additional information
on the development, evaluation, and selection
of remedial action alternatives for the example
site.

7.1.9 Task 9~Alternatives Evaluation

The  final  alternatives will be  evaluated  to
provide EPA with a framework  with which to
select  a remedy for the site.    The detailed
analysis  of these alternatives will be conducted
in three stages:   further  refinement, individual
analysis,  and  comparative analysis.

Further  refinement  of  the alternatives  will
include developing detailed information such as:

  •    Identifying   design parameters for
       technology components such as landfill
       cap and groundwater treatment  system

  •    Quantifying amounts of contaminated
       soils (and possibly sediments) to be
       handled

  •    Estimating time of implementation for
       construction activities

  •    Estimating   O&M  requirements,
       particularly for a groundwater pump and
       treatment system and  a landfill gas
       treatment system

  •-    Process  sizing

This information will be used to develop a cost
estimate to within +50 percent to -30 percent.
During the individual analysis, each alternative
will be evaluated with respect to the following
nine  evaluation criteria:

  •   Overall protection of human health and
      the environment

  •   Compliance with ARARs

  •   Long-term effectiveness and permanence

  •   Reduction of toxicity,   mobility,  or
      volume through treatment

  •   Short-term effectiveness

  •   Implementability

  •   cost

  •   State acceptance

  •   Community acceptance

Detailed descriptions of each  of the above
criteria  are  reported  in the RI/FS Guidance
(U.S. EPA, 1988a).

Following the individual analysis, a comparative
analysis  will be  performed.  The comparative
analysis  will  lead to the development of a
description of the strengths and weaknesses of
the alternatives relative to one another. Not all
the criteria will be used in this evaluation; just
those that  illustrate significant differences
among the alternatives. As part of this evalua-
tion, there will be an analysis of how  a change
in the uncertainties or assumptions made in the
analysis  may  change the performance of the
alternatives.

7.1.10 Task 10-Feasibility Study  Report

Following, completion of the detailed evaluation
task,  the Contractor will prepare and submit a
draft FS  report for the example site to EPA for
review and comment.  The report will sum-
marize FS activities and RI site characterization
results and will be prepared in accordance with
RI/FS Guidance  (U.S. EPA  1988a).  Informa-
tion  developed during the FS  such as identifica-
tion of ARARs, detailed description of alterna-
tives, and detailed evaluation of alternatives will
                                             A7-26

-------
be provided to EPA for review as these items
are  completed, in order to obtain  input from
the  Agency during the evaluation process.

7.1.11 Task 11-Treatability Studies

Any necessary laboratory, bench, or pilot scale
treatability  studies  required  to evaluate  the
effectiveness  of remedial technologies  and
establish engineering criteria will be identified
as early as possible.  Should laboratory studies
be required, a testing plan for the studies  will
be prepared and presented to EPA for review
and approval. This testing plan will identify the
types and goals of the studies, the level of effort
needed, a schedule for completion, and the  data
management guidelines. Upon EPA approval, a
test  facility  and any necessary  equipment,
vendors, and analytical services will be  pro-
cured.   Upon  completion of the testing, the
results will be evaluated to assess the technolo-
gies with respect to the goals identified in the
test  plan. A report  summarizing  the testing
program and its results will be prepared and
presented in the final FS report.
                                              A7-27

-------

-------
                                Section S
                 COST AND KEY ASSUMPTIONS
The work plan should present a section that contains a cost estimate for conducting the
RI/FS. The key assumptions used in preparing this estimate should also be presented.
This section will follow the same approach used in all RI/FS work plans and is not
discussed here because it is  covered in the  RI/FS  guidance (U.S. EPA,  1988a).
                                   A8-1

-------

-------
                                  Section 9
                                SCHEDULE
The schedule preparation for municipal landfill sites does not differ in approach from
typical RI/FS work plans and is therefore not presented in this example.
                                     A9-1

-------

-------
                                Section 10
                     PROJECT  MANAGEMENT
Project management activities, such as staffing and coordination for municipal landfill
sites, does not differ in approach from other types of sites and is therefore not covered
in this example.
                                   A10-1

-------

-------
                                Section  11
                            BIBLIOGRAPHY
U.S. Environmental Protection Agency, National Enforcement Investigation Center
(NEIC). Policies and Procedures for Sample Control. 1986.

U.S. Environmental Protection Agency. Data Quality Objectives for Remedial Response
Activities. EPA/540/6-87/003. March 1987a.

U.S. Environmental Protection Agency.   Health Advisories for 25 Organics. March
 1987b.

U.S. Environmental Protection Agency.   Compendium of Superfund Field Operations
Methods. EPA/540/P-87/001. December 1987c,

U.S.  Environmental  Protection  Agency.    Guidance for Conducting Remedial
Investigations and Feasibility Studies under CERCLA, Interim Final. EPA/540/G-89/004.
October 1988a.

U.S. Environmental Protection Agency.   User's Guide to the Contract Laboratory
Program. EPA/540/8-89/012.  December 1988b.

U.S. Environmental Protection Agency.   Integrated Risk Information System.  June
 1989a.

U.S. Environmental Protection Agency.  Interim Final, Risk Assessment Guidance for
Superfund, Volume 1, Human Health Evaluation Manual, Part A.  December 1989b.

U.S. Environmental Protection Agency.   Risk Assessment Guidance for Superfund.
 Volume II Environmental Evaluation Manual.  Interim  Final. EPA/540/1-89/001.
March 1989c.
                                    All-1

-------

-------
               Appendix B

Remedial Technologies Used
            at Landfill Sites

-------

-------
Appendix B-l
RODS REVIEWED FOR THE MUNICIPAL LANDFILL STUDY
Page 1 of 5
Region
Region 1
Region II
Site
Auburn Road Landfill, NH
Beacon Heights, CT
Charles George, MA
Davis Liquid, RI
Iron Horse, MA
Kellogg-Deering Well Field, CT
Landfill & Resource Recovery, RI.
Laurel Park, CT
Old Springfield, VTB
Winthrop Landfill, ME
Combe Fill North, NJ
Combe Fill South, NJ
Florence Landfill, NJ
GEMS Landfill, NJ
Helen Kramer, NJ
Kin-But Landfill, NJ
Lipari Landfill, NJ
ROD
Date(s)
9/17/86
9/29/89
9/23/85
12/29/83
7/11/85
9/29/88
9/29/87
9/15/88
9/17/86
9/29/89
9/29/88
6/30/88
9/22/88
11/22/85
9/29/86
9/29/86
6/27/86
9/27/85
9/27/85
9/30/88
8/03/82
9/30/85
7/11/88
"Source control ROD has not yet been completed; only groundwater remedy
 (i.e., management of migration) has been implemented.
                                    B-l

-------
Appendix B-l
RODS REVIEWED FOR THE MUNICIPAL LANDFILL STUDY
Page2of5;
Region
Region II
(Continued)
IRegion III
Site
Lone Pine Landfill, NJ
Ludlow Sand & Gravel, NY
Old Bethpage, NY
Port Washington Landfill, NY
Price Landfill, NJ1
Ringwood Mines, NJ
Sharkey Landfill, NJ
South Brunswick Landfill, NJ
Volney Landfill, NY
Army Creek, DE
Blosenski Landfill, PA
Craig Farm Drum, PA
Delaware Sand & Gravel, DE
Dorney Road Landfill, PA
Henderson Road, PA
Enterprise Avenue, PA
Heleva Landfill, PA
Industrial Lane, PA"
Moyer Landfill, PA
Reeser's Landfill, PA
ROD
Date(s)
9/28/84^
9/30/88!
3/14/88!
9/30/8$>
9/20/831
9/29/86i
9/29/88!
9/29/861
9/27/87'
7/31/87'
9/29/86.
9/29/86
9/29/89
4/29/881
9/29/88
6/01/88
9/29/89
5/10/84
3/22/85
9/29/86
9/30/85
3/20/89
"Source control ROD has not yet been completed; only groundwater remedy
 (i.e., management of migration) has been implemented.
                                    B-2

-------
Appendix B-l
RODS REVIEWED FOR THE MUNICIPAL LANDFILL STUDY
Page 3 of 5
Region
IRegion III
(Continued)
Region IV
Region V
Site
Strasburg Landfill, PA
Tybouts Corner, DE
Wildcat Landfill, DE
Airco, KY
Amnicola Dump, TN
Davie Landfill, FL
Goodrich, KY
Hipps Road Landfill, FL
Kassouf-Kimberling, FL
Lees Lane Landfill, KY
NW 58th Street Landfill, FL
Newport Dumpsite, KY
Powersville Landfill, GA
Belvidere Landfill, IL
Bowers Landfill, OH
Cemetery Dump, MI
Cliff/Dow Dump, MI
Coshocton City Landfill, OH
E.H. Schilling, OH
Forest Waste, MI
ROD
Date(s)
3/30/89
3/06/86.
6/29/881
9/30/881
6/24/88
3/30/89
9/30/85
6/24/88
9/03/86
9/30/89
9/25/86
9/21/87
3/27/87
9/30/87
6/29/88
3/31/89
9/11/85
9/27/87
6/17/88
9/29/89*
2/29/84
3/31/881
"Source control ROD has not yet been completed; only groundwater remedy
 (i.e., management of migration) has been implemented,
                                    B-3

-------
Appendix B-l
RODS REVIEWED FOR THE MUNICIPAL LANDFILL STUDY
Page 4 of 5
Region
Region V
(Continued)
Site
Fort Wayne, IN
Industrial Excess, OH
Ionia City Landfill, MI
Kummer Landfill, MN
Lake Sandy Jo, IN
Liquid Disposal, MI
Marion/Bragg, IN
Mason County, MI
Metamora Landfill, MI
Miami County, OH
Mid-State, WI
New Lyme Landfill, OH
Northside, IN
Oak Grove Landfill, MN
Schmalz Dump, WI
Spiegelberg, MI
Wauconda Sand & Gravel, IL
Windom Dump, MN
ROD
Date(s)
8/26/88
9/30/87
7/17/89
9/29/88
6/12/85
9/30/88
9/26/86
9/30/87
9/30/87
9/28/88
9/30/86
6/30/89
9/30/88
9/27/85
9/25/87
9/30/88
8/13/85
9/30/87
9/30/86
9/30/86
9/29/89
"Source control ROD has not yet been completed; only groundwater remedy
 (i.e., management of migration) has been implemented.
                                    B-4

-------
Appendix B-l
RODS REVIEWED FOR THE MUNICIPAL LANDFILL STUDY
Page 5 of 5
Region
Region VI
Region VII
Region VIII
Region IX
Region X
Site
Bayou Sorrel, LA
Cecil Lindsey, AR
Cleve Reber, LA
Compass Industries, OK
Industrial Waste Control, AR
Arkansas City Dump, KS
Conservation Chemical, MO
Doepke Disposal, KS
Fulbright/Sac River Landfill, MO
Todtz, Lawrence Farm, IA
Marshall Landfill, CO
Jibboom Junkyard, CA
Operating Industries, CA
Ordot Disposal Site, GUAM
Colbert Landfill, WA
Commencement Bay South Tacoma Channel, WA
Northside Landfill, WA
ROD
Date(s)
11/14/86
4/23/86
3/31/87
9/29/87
6/28/88
9/21/89
9/27/87
9/21/89
9/30/88
11/4/88
9/26/86
5/09/85
7/31/87
11/16/87
9/30/88
9/28/88
9/29/87
3/31/88
9/30/89
"Source control ROD has not yet been completed; only groundwater remedy
 (i.e., management of migration) has been implemented.
                                    B-5

-------
                    11/14/90
                    GENERAL  RESPONSE  ACTION/
                    Remedial  Technologies
                      Process  Options
                                                                                     Appendix B2
                                                                   Remedial Technologies  Used at  Landfill  Sites
                              Region I
                               Auburn  Beacon    Charles   Davie   Iron   Kellogg  Landfill &
                                Road   Heights   George    Liquid  Horse  Deering   Res.  Rec.
Laurel
 Park
    Old
Springfield
Winthrop  Region  I
Landfill  Total
                      SOILS/LANDFILL  CONTENTS
CO
NO ACTION
ACCESS  RESTRICTION
Deed Restrictions
Land  Use Restrictions
Fencing
CONTAINMENT
Surface  Controls
  Grading
  Revegetation
Cap
  Clay  Barrier
  Multibarrier
  Soil
  Synthetic  Membrane
REMOVAL/DISPOSAL
Excavation
  Mechanical  Excav.
  Drum  Removal
  consolidation
Disposal  Onsite
  RCRA  Type Landfill
Disposal  Offsite
Soil  Treatment
Biological  Treatment
Physical  Treatment
Thermal  Treatment
  Incineration
Offsite  Treatment
  RCRA  Incinerator
IN-SITU  TREATMENT
  Biodegradation
  Vitrification
Physical  Treatment
  Solidification/fixation
  Vapor  Extraction

-------
                       11/14/90
                                                                                         Appendix B2
                                                                       Remedial  Technologie Used  at  Landfill Sites
W
GENERAL RESPONSE ACTION/ Region I
Remedial Technologies Auburn Beacon
Process Options Road Heights
GROUNDWATER
AND LEACHATE
NO ACTION
Attenuation
Observation
MONITORING X
INSTITUTIONAL CONTROLS X
Alternate Water Supply x X
CONTAINMENT
Vertical Barriers
Slurry Wall
COLLECTION x x
Extraction X x
Extraction Wells
Ext/Inj action Wells
Leachate Collection x X
Collection trench x
Leachate Drain X
Onsite Discharge
Aquifer Reinjection
Surface Discharge
Dewatering
Of f site Discharge
POTW
Land Application
TREATMENT
Biological Treatment
Activated Sludge
Chemical Treatment X
Oxidation
Ion Exchange Treatment
coagulant Addition X
Metals Preciptation X
pH Ad j us tment
Physical Treatment X
Adsorption X
Air stripping X
Sedimentation
Sand filtration
Flocculation
Lime pretreatment
Off site Treatment
POTW
Charles Davis Iron Kellogg Landfill & Laurel
George Liquid Horse Bearing Res. Eec. Park





x x X x
X XX
X X



X X
X X
X X

X

X




X
X

XX X
X

X X
X
X

X

x X x
XX X
X X




X
X
II
Old Winthrop Region I |
Springfield Landfill Total


0
0
0
xx 7
x 5
x 5
0
0
0
1
xx 7
xx 7
2
0
3
1
2
0
0
0
0
1
1
0
x 4
1
0
3
1
1
1
2
0
4
4
3
0 1
0 1
0 1
0 t
1 1
1 1
____«=_»I,M====^_=_____=.»»» 1

-------
                          11/14/90
                                                                                            Appendix B2
                                                                          Remedial  Technologies  Used at  Landfill Sites
CO
OS

GENERAL RESPONSE ACTION/
Remedial Technologies
Process Options
LANDFILL GAS

Collection
Passive Systems
Pipe Vents
Trench Vents
Active Vents
Extraction Wells
Blowers
TREATMENT
Thermal Destruction
F lar ing
Activated carbon
MONITORING

SURFACE WATER
AND SEDIMENTS

Region I
Auburn Beacon Charles Davie Iron Kellogg Landfill & Laurel Old Winthrop Region I
Road Heights George Liquid Horse Deering Res. Rec. Park Springfield Landfill Total


x x 2
x x x x 4
0
0
x 1
x 1
0
x 1
XX 2
x 1
0
xx 2



II
II
II
II
1 1
1!
1!
II
It
II
II
II
II
SI
11
tl
tl
II
II
1 1
1 1
II
11
                         Stormwater  controls
                           Diversion
                         Removal   Disposal   (sediments)
                           Excavation
                         Offsite Disposal  (sediments)
                         Treatment
                           Solidification
                           Dewatering
                           Thermal   treatment

-------
ll/H/90
                                                                                             Appendix B2
                                                                                        Tachnologlaa Oa»d at Landfill Sit..
CEHKMU RESPONSE ACTION/ Region II Clouoeater
lleaait lal Technologlee Combe rill Conbe rill Florence Environ. Helen ICln-Buc Llpaxl Lona Lndlow Old Port
Procaai Option! Korthp south Land Racoo, Hget. (GEMS) Kramer landfill Landfill Pin* Band Bethpage fraahlngton
(OILfl/IJUIDriLL COHTIHTa

IK) ACIION
tease MSTIUCTIOH x x x x x
Deed Rutrlctloni
Land Oi* Restriction*
Fencing X X X X X X
COHTAIHHEin X XX XXXX XX
Surfao* Control* X XX
Grading X X
Rarreget atlon
Cap XXXXXXX XXX
Clay Barrier X X X XXX
Hultibarrler XXX X
loll X
lynthetlo Hanbrane X
REMOVAL/DISPOSAL
Excavation X
Meohanlcal Exca?. X
Dnna fUaroral
Conao lldatlon
Dlipoaal Onalt*
HCRA Type landfill
Olipoaal Offalte
SOIL TREJUMEHT
Biological Treat>ant
Phjalcal Treatment
TbaxBial Tree^Bent X
Inclneratloa
Of flit. Treatment
RCML Incinerator
nr-iim TRXJLTMEHT
llodegradatlon
' Vltrl float Ion
Phyaloal Treatment
Bolldlflcatlon/flxatlon
Vapor Extraction
tl
11
Prloe Klngwod Bharkey faatti Volnej Region 11 1 1
Landfill Mine* Landfill Bronndck Landf 111 Total | |
11
II
0 11
X ( ||
0 II
0 II
X XX )|l
XX X 12 ||
XX X l|l
X X 4 ||
X 1||
X X X 13 It
< It
IX < ||
I 2 ||
1 II
X 1 |t
X 2 |t
1 II
0 II
0 II
, 0 II
0 II
X 1||
D II
0 II
0 II
1 II
0 II
o It
o II
0 II
0 II
0 II
X 1||
X 1||
o 11

-------
              Appandlx B2
Rwtdlal T«hnologlu O*»d at Landfill flit..
CZHERAt, PirTPOWBI ACTIOM/
P«M*t«ant
Phyaloal Traataant
kdaorptlon
Air B tripping
•adl^antatlon
Band filtration
FlooonLatlon
Llna pratraatjwnt
Offalta Tnatmant
term
II
Cnah* rill Comb* rill rloranca CnTlron. Ralan KLn-Bnc Llparl Lona Ludlow Old Port Prloa Rlno^nxxl Bharkay Booth Volnay Raglcn II||
Horth South Land Racon. Hgat . (CD4S} Krnar Landfill Ijutdflll Plna Sand Bathpao^ Waahlngton Landfill Mlna« Landfill Brnnawlck Landfill Total \ \
II
1 1
X 111
X 111
0 1 1
XXX XX X XX XI Xll||
X 1 (I
X X 2 M
X XXXX XXTM
X XXXX XXTH
x xxxx XXTH
o II
X XXXXXXXX X X 11 | |
XX X XXXXXXXX X X13||
X X XXX XX 7 M
x ill
XXXXXX XX||
XXX ||
XX XX||
M
x 11
11
XX I)
XX I)
xx M
11
X XXXX X X X X|1
X X X||
o II
XX XX 4 | |
o II
o II
0 II
X XX 3 ||
X 1(1
XXX XXX X Xl||
X X 2 | |
XX XIX X (||
XX 2|1
0 II
XX III
I I II
XXI I X X III
XXX X I X « ||

-------
                                                                                             .t Landfill BltM
CD41TPAL HEBPCHJTE JU7TTCM/     PL*glon IT
          T*obnolog 1 «>•         C*»*tM rill
         • Option*               Hortb
                               rill    rlor*no«      Environ.     n*l*n   Itln-niio     T.lparl    I^in*  Lndlov
                            South   l»nd Racxm.  Kgnt. (CCHS)   Kr«».r  L»odflil   Landfill   Pin.   Hand
Rlngmod  «h»rl.I
  Kin**
                                                                                                                                                                                 Voln*T
  II
  tl
II|t
  1 1
CHS
COUXCTIOH
Fauin Ifitau X
Pip* V«nt«
Tr«DOh V*nt« X
Aatlv* V*nta
Extraotlon Walla
Blow!
TUJUMEHT
Thers±l Dsstrnctioa
rlarln?
Aoti.Tat«d oacbaa
MDH1T01LD1U
•UFTACX HXTCt
AMD BBDIHBfTD

ItoraMatvr oontrola
DlTmrilon
Tlaannal Dl.«po«al («*dlKant«)
£zcaTfitlc£
Otf.lta Dlapoaal{>a
-------
11/14/90
                                                                                             Appendix B2
                                                                            Remedial Technologies  Head at Landfill Sites

GENERAL  RESPONSE ACTION/     Region III                                                                                                                                           '
^Process ^rns09"3           ^T     B1°SenSki Cra±g  DSlaWare  D°rney  Enterprise   Heleva   Henderson  Industrial   Moyer   Reeser,s  strasburg  Tybouts wildcat  Region IIZ
  Process  Otions
   Process       ns
   Process  Options              Creek     Landfill    Farm    Sand     Road    Avenue   Landfill     Road      Lane     Landfill   Landfill    Landfili   corner   Landfill  Subtotal .

 ~ "SOILS'/LANDFILL" ~ CONTENTS                                                                                                                                                       =1
                                                                                                                                                                                    I
 NO ACTION                                                                                                                                                                          I
 ACCESS  RESTRICTION                                                    x                                                            X                                            1 I
 Deed  Restrictions                                                                                                                                                               ! I
                                                                        A                                                                                                           i
 Land  Use  Restrictions                                                                                                                                                           1 I
 Fencing                                                                                                                                                           x              1 t
 CONTAINMENT                      x         x         x         x       x         x                                                                                               °  '
 Surface  Controls                  x                   x                           x                   X                    X                    *          x        x             12  1
   Grading                         x                                              x                                                                                x              4  I
   Revegetation                                                                   x                                                                                x              3  I
 Cap                                xxxxxxxx                    v                                       X2|
   Clay  Barrier                              x         x                           x                                                                       x        x             11  |
   Multibarrier                    x                            x       x                   x         x                    X                                                      4  '
   Soil                                                                                                                                                   x                       6  I
   Synthetic   Membrane                                                                                                     X                                       x              2  I
 REMOVAL/DISPOSAL                                      x                           x                                                                                               °  '
 Excavation                                  x         x         x                 x                                                                                               ^  ^
   Mechanical   Excav.                                            x                                                                                         x                       5  ]
   Drum  Removal                              x                  x                                                                                         x                       2  |
   Consolidation                                                                                                                                                   x              3  I
Disposal  Onsite                                                                                                                                                                  0  I
   RCRA Type  Landfill                                                                                                                                                            0  I
Disposal  Offsite                                                                                                                                                                 0  I
SOIL TREATMENT                                          x                                                                                                                           1  I
Biological Treatment                                                                                                                                                               2  I
Physical  Treatment                                             x                                                                                                                 0  I
Thermal  Treatment                                              x                                                                                                                 1  I
   Incineration                                                 x                                                                                                                 •*•  I
Offsite  Treatment                                                                                                                                                                1  1
   RCRA   Incinerator                                                                                                                                                                 '
IN- SITU  TREATMENT                                                                                    x                                                                            0  I
  Biodegradation                                                                                                                                                                 1  '
  Vitrification                                                                                                                                                                   °  I
Physical  Treatment                                                                                                                                                               0  I
  Solidification/fixation
                                                                                                                                                                                3
 Vapor  Extraction
                                                                                                                                                                                2

-------
   11/14/90
                                                                                                Appendix  B2
                                                                              Remedial Technologies Used at  Landfill  sites
   GENERAL  RESPONSE  ACTION/
   Remedial   Technologies
     Process   Options
Region  111
   Army  Blosenski
  Creek    Landfill
Craig  Delaware  Dorney Enterprise   Heleva
 Farm     Sand     Road    Avenue    Landfill
Henderson Industrial   Moyer
   Road      Lane   Landfill
Reeser's
Landfill
Strasburg  Tybouts  Wildcat  Region  III
 Landfill   Corner   Landfill   Subtotal
           GROUNDWATER
           AND  LEACHATE

   NO ACTION
     Attenuation
     Observation
   MONITORING
   INSTITUTION  CONTROLS
   Alternate  Water  Supply
   CONTAINMENT
   Vertical   Barriers
     Slurry   Wall
   Horizontal  Barriers
   COLLECTION
   Extraction
     Extraction  Wells
     Ext/Injection  Wells
   Leachate   Collection
g0   Collection  trench
>!_!   Leachate Drain
^* Onsite   Discharge
     Aquifer   Reinjection
     Surface   Discharge
     Dewatering
   Offsite  Discharge
     POTW
     Land  Application
   TREATMENT
   Biological  Treatment
     Activated  Sludge
   Chemical   Treatment
     Oxidation
     Ion  Exchange  Treatment
     coagulant  Addition
     Metals   Preciptation
     pH  Adjustment
   Physical   Treatment
     Adsorption
     Air  Stripping
     Sedimentation
     Sand  filtration
     Flocculation
     Lime  pretreatment
   Offsite  Treatment
     POTW
                                                                                                                                                    1
                                                                                                                                                    0
                                                                                                                                                    0
                                                                                                                                                    6
                                                                                                                                                    1
                                                                                                                                                    4
                                                                                                                                                    0
                                                                                                                                                    0
                                                                                                                                                    0
                                                                                                                                                    0
                                                                                                                                                    4
                                                                                                                                                    4
                                                                                                                                                    3
                                                                                                                                                    1
                                                                                                                                                    4
                                                                                                                                                    4
                                                                                                                                                    3
                                                                                                                                                    0
                                                                                                                                                    0
                                                                                                                                                    0
                                                                                                                                                    0
                                                                                                                                                    0
                                                                                                                                                    0
                                                                                                                                                    1
                                                                                                                                                    3
                                                                                                                                                    1
                                                                                                                                                    1
                                                                                                                                                    0
                                                                                                                                                    0
                                                                                                                                                    0
                                                                                                                                                    0
                                                                                                                                                    0
                                                                                                                                                    0
                                                                                                                                                    3
                                                                                                                                                    2
                                                                                                                                                    2
                                                                                                                                                    1
                                                                                                                                                    0
                                                                                                                                                    0
                                                                                                                                                    1
                                                                                                                                                    1
                                                                                                                                                    1

-------
11/14/90
                                                                                             Appendix  B2
                                                                            Remedial  Technologies Used  at Landfill Sites
GENERAL RESPONSE ACTION/
Remedial Technologies
Process Options
LANDFILL GAS
COLLECTION
Passive Systems
Pipe Vents
Trench Vents
Active Vents
Extraction Wells
Blowers
0 TREATMENT
^ Thermal Destruction
Flaring
Activated carbon
MONITORING
SURFACE WATER
AND SEDIMENTS

Region XII
Army Blosenski Craig Delaware Dorney Enterprise Heleva Henderson Industrial Moyer Reeser's Strasburg Tybouts Wildcat Region III I
Creek Landfill Farm Sand Road Avenue Landfill Road Lane Landfill Landfill Landfill Corner Landfill Subtotal

x x x x 4
x x x 3
0
Xx 2
XX 2
x 1
0
x 1
x 1
0
0
x xx 3


0
  Diversion
Removal   Disposal(sediments
  Excavation
Offsite  Disposal(sediments)
Treatment
  Solidification
  Dewatering
  Thermal  treatment

-------
11/14/90
GENERAL RESPONSE ACTION/
Remodlal Tachnologlos
  Process Options
                                                                Appendix B2
                                                 Remadial Technologies Used at Landfill Sites
Koglon IV
  Alrco  Amnicola  Davie     B . F .    Hipp*  Kassouf -   Lees  NW  5Bth
Landfill   Dump   Landfill Goodrich  Road   Rimerling  Lane  St. LF
                                                                                                  Newport  Powers villa Region  IV |
                                                                                                  Dump ol to   landfill    Total  |
  SOIL 3 /LANDFILL CONTENTS

NO ACTION
ACCESS RESTRICTION
Dead Restrictions
Land Use Restrictions
Fencing
CONTAINMENT
Surface Controls
  Grading
  Ravogetation
Cap
  Clay Barrlar
  Multibarrlar
  Soil
  Synthetic Membrane
REMOVAL/DISPOSAL
Excavation
  Mechanical Eicav.
  Drum Removal
  Consolidation
Disposal Onelte
  RCRA Type Landfill
Disposal Offslte
SOIL TREATMENT
Biological Treatment
Physical Treatment
Thermal Treatment
  Incineration
Offslte Treatment
  RCRA Incinerator
IN-SITTJ TREATMENT
  Vitrification
Phyaicnl Truntmont
  Solidification/fixation
  Vapor Extraction
                                X
                                X
                                X
                                X
                                X
                                X
                                X
                                X
                                X
                                                                         X
                                                                         X
                                                                         X
                                                                         X
                                                                         X
                                                                         X
                                                                                                                                 II
                                                                                                                                 | t
                                                                                                                                 | |
                                                                                                                                 | |
                                                                                                                                 | |
                                                                                                                                 ] |
                                                                                                                                 | I
                                                                                                                              8  | 1
                                                                                                                              5  | |
                                                                                                                              1  | |
                                                                                                   0  t I
                                                                                                   0  | |
                                                                                                   4  j |
                                                                                                   2  \\
                                                                                                   1(1
                                                                                                   1
                                                                                                   2
                                                                                                   1
                                                                                                   0  | |
                                                                                                   O  | |
                                                                                                   0
                                                                                                   0
                                                                                                   0
                                                                                                   0
                                                                                                   0
                                                                                                   0
                                                                                                   0
                                                                                                   0
                                                                                                   0
                                                                                                   3
                                                                                                   2
                                                                                                   2
                                                                                                                                 1 |
                                                                                                                                 ] |
                                                                                                                                 | |
                                                                                                                                 | (
                                                                                                                                 1 |
                                                                                                                                 \ \
                                                                                                                                 \\
                                                                                                                                 I 1
                                                                                                                                 I 1

-------
                        GENERAL  RESPONSE  ACTION/
                        Remedial   Technologies
                          Process  Opt  Ions
                                                                                           Appendix  B2
                                                                           Remedial  Technologies  Used at  Landfill Sites
                              Region  IV
                                Airco   Amnicola  Davie      B. F.
                              Landfill    Dump   Landfill  Goodrich  Road    Kimerling  Lane  st.  LF   Dumpsite    Landfill    Total
                                                                   I I
                                                                   I I
                                                                   I I
Hipps  Kassouf-    Lees  NW  58th  Newport Powersville  Region  IV   | |
                                GROUNDWATER
                                AND  LEACHATE
CO
 NO ACTION
   Attenuation
   Observation
 MONITORING
 INSTITUTIONAL  CONTROLS
 Alternate  Water  Supply
 CONTAINMENT
 Vertical  Barriers
   Slurry wall
 Horizontal  Barriers
 Collection
 Exraction
   Extraction  Wells
   Ext/Inj ection  Wells
 Leachate  Collection
   Collection  trench
   Leachate  Drain
 Onsite  Discharge
   Aquifer  Reinjection
   Surface  Discharge
   Dewatering
 Offsite  Discharge
   POTW
   Land  Application
 TREATMENT
 Biological  Treatment
   Activated   Sludge
 Chemical  Treatment
   Oxidation
   Ion  Exchange Treatment
   Coagulant   Addition
  Metals  Preciptatlon
  pH  Ad j us tment
Physical  Treatment
  Adsorption
  Air  Stripping
   Sedimentation
   Sand  filtration
   Flocculation
  Lime  pretreatment
Offsite  Treatment
   POTW
                                                                                                                        X

                                                                                                                        JC

-------
                            11/14/90
                                                                                               Appendix  B2
                                                                                         Technologies Used  at
                                                                                                               Landfill  Sites
DO
GENERAL RESPONSE ACTION/ Region IV
Remedial Technologies Airco Amnicola Davie B.F. Hipps Kassouf- Lees NW 58th
Process Options Landfill Dump Landfill Goodrich Road Kimerling Lane St. LF
LANDFILL GAS
COLLECTION x x
Passive Systems x x
Pipe vents
Trench Vents x x
Active Vents
Extraction Wells
Blowers
TREATMENT
Thermal Destruction
Flaring
Activated carbon
MONITORING
SURFACE WATER
AND SEDIMENTS

Diversion
Removal Disposal (sediments)
Excavation
Offsite Disposal (sediments)
Treatment x
Solidification x
Dewatoring x
Thermal treatment


Newport Powersville Region IV [
Dumpsite Landfill Total El

2
2
0
2
0
o I
0 1
0 1
0 1
0 1
0 I
x 1 1

1
1
x 1 1
0 1
0 1
o 1!
o 1
1
1
1
0


-------
u/»o
                                                                                                              Appandlx M
                                                                                                  al  Taohnologlaa  Clad it  Landfill  >ltu
EMU. M»am ACT I OH/
Kllal Taohnologlaa
rooaaa Optlona
>lvloaxa    aowar*   C«m*tar
.andflll   Landfill   Dump
Cllrr/Dow  Co. hoc ton   I. H.    roraa
           Landfill  Boh111 lug  Malta
Industrial  lonlj
  Exc«a    City  Landfill
Laka    liquid   Marlon  Mil on  Mataaora   Hlaml  KLd-ttata
    Jo Dlapoaal  Bragg  County  Landfill  County
IIH/UHDrlll COHTENTB
tCIIO*!
'M* HERIUCTIOM
1 Kaatzlotlona
I Qa« Matrlotlona
ilng
xnoonrr
•oa Control*
•ding
T> jatat Ion

ay Barzlar
Itlbarrlar
11


X
X

X
X



X





X

X
X
X
X
X

X
X

X


X 1
X )
X


X

X
X


X ]


I X
C X

X
X
(
X

X
X




X
X


X
X


X

X



X
X

X
X



X


X


X

X X
X X
X X
X


X X

X
X


XX ]
X X

X ]

X
X
I
XXX

X
X


[ X

X
[ X




X
X
X
X


X
X
X
I

X
X

X
X

X





X




X

X

nth.tlo Mambrana
VU./DIIPOUL
TBtloa
ah«nlaal  Kxca-r,
am Jtavorvl
D«olld«tlon
oaal Onftlt*
Hi Typa Landfill
»>al Dffalta
 THUUMDIT
oglcal  TraatBant
Loal Traatmant
ul Traataant
alnaratloa
Lta Tr*at»ant
Ul Inolnarator
[TO TMATHDrr
Ktegrada t loo
:rlfloatIon
Leal Traatxant
Lldlfloatlon/fLutlon
Kir Eatrantlnn

-------
                                                                                                                 Jtppuullx BI
                                                                                               r»n1t«l I*chnolog;l*> D>*d It Landfill lit**
        KMVOH1C ACTION/
       l T*ahnologl*«
  proc*** Option*
 Region V
b«lglc*l
  kotlntwl llndg*
  Oxidation
  Ion Exohang*
  H»tal* Pr.alpt.tlon
  pi IdJnctBut
PbyaluJ. Trut
  JLlx 'tripping
  •and filtration
  rlo
-------
       11/14/90
       omutu, M»OHK  action/
                                                                                                                        Appudlx I!
                                                                                                      K*»«iH«I. Technologic! Ol*d it T^wutu 11  tit««
                 'Option*
                                                Lradllll   Di—p
                                                                   CLlff/Dov  CDihooton   C.  I.     ror**t
                                                                     Dwp     Ludflll  ichlllljuj  «..t«
Fort
H.JI1.
                                                                                                                   IDdu«trial
T.t«jn M
                                                                                                                               City  LuuUlll
         Htrlon  Huoc
         ftr*gg  Coootf
Hid-lt»t*  H*v
 Ludfiii  ia»»
               uuoriij, CM
       COLLECIIOM
       ••••1-n tymtt
         tip* Tut«
       lot IT* V«nt«  .
         tttr.otlon *•!!•
CO
tsJ
o

-------
                                          11/14/90


                                                                                         Appendix B2
                                                                          Remedial Technologies Used at Landfill Sit as


                                        •  GENERAL RESPONSE ACTION/    Region V Continued
                                          Romadlal Technologies        Northslcle   Oak   Schmalz Splegelberg  Wauconda Wlndom Region V
                                            Process Opt lone               IN      Grove   Dump    Landfill      Sand    Dump    Total

                                            SOItS/LANDFILL CONTENTS

                                          NO ACTION                                                              •         .           0
                                          ACCESS RESTRICTION               XX                             X                 17
                                          Deed Restrictions                XX                                               12
                                          Land Use Restrictions                                                                      1
                                          Fencing •                                  X                             X                 15
                                          CONTAINMENT                      XX                             X                 12
                                          Surface Controls                          X                             X       X         13
                                            Grading                                                               XX          9
                                            Ravegetatlon                            X                             X       X          7
                                          Cap                              XXX                    X       X         22
                                            Clay Barrier                                                          XX          6
                                            Multibarrler                   XX                                                8
                                            Soil                                            X                                       9
i                                            Synthetic Membrane                                                                       0
E^                                        REMOVAL/DISPOSAL                                                                           2
                                          Excavation                                        XX                             10
                                            Mechanical Excsv.                               X                                       3
                                            Drum Removal                                                                             3
                                            Consolidation                                                                            ^
                                          Disposal Onslta                                                                            2
                                            RCRA Type Landfill                                                                       0
                                          Disposal Offsita                                  XX                              6
                                          SOIL TREATMENT                                                                             3
                                          Biological Treatment                                                                       1
                                          Physical Treatment                                                                         1
                                          Thermal Treatment                                                                          *
                                            Incineration                                                                             *
                                          Offsite Treatment                                            X                              1
                                            RCRA Incinerator                                           X                              1
                                          IN-SITTJ TREATMENT                                                                          1
                                            Blodogradatlon                                                                           0
                                            Vitrification                                                                            1
                                          Physical Treatment                                                                         2
                                            Solidlllcation/fiiation                                                                  1
                                            Vnpor Extraction                                                                         1

-------
CO
K)
                                        11/14/90


                                                                                       Appandix B2
                                                                        Remedial Technologies Ujjod  at  Landfill Sites


                                        GENERAL RESPONSE ACTION/    Region V Continued
                                        Remedial Technologies        Northsids   Oak   Schmalz Spiegelberg Wauconda Hindom Region V
                                          Procoet Options               IK      Grova   Dump    Landfill      Sand    Dump    Total
GROUNDWATER
AND LHACTATE

NO ACTION
Attenuation
Observation
MONITORING XXX
INSTITUTIONAL CONTROLS
Alternate Hater Supply X
CONTAINMENT
Vertical Darrlerfl
Slurry Wall
Horizontal Barriers
COLLECTION
Extraction
Extraction Halls
Ext /Inject Ion Halls
Leachata Collection X
Collection trench X
Leachate Drain X
Onelte Discharge
Aquifer Reinfection
Surface Discharge
Dewatering
Offnita Discharge
POTW
Land Application
TREATMENT
Biological Treatment X
Activated Sludge X
Chemical Treatment X
Oxidation X
Ion Exchange Treatment
Coagulant Addition
Metals Praciptation X
pH Adjustment
Physical Traatnent X
Adsorption X
Air Stripping
Sadlmenta tlon
Unnd flltrntlon
Floccu 1 at Ion
Lime pre treatment
Off site Treatment
POTH



X 1
0
0
XX 17
6
6
3
3
3
0
X 9
X 10
5
0
X 5
1
X 5
0
0
0
2
0
O
0
5
2
1
3
1
1
0
2
0
7
5
4
1
1
1
0
X 4
X 4
II
1 I
II
•1 1
II
II
II
II
1 1
II
II
II
II
II
It
II
II
II
II
II
II
It
[1
1 1
II
II
II
II
II
11
II
II
M
II
M
II
II
II
II
II
II
II
M
1 1
II
:l 1

-------
                                            11/14/90
                                                                                           Appendix B2
                                                                            Remadlal Technologies Used at Landfill Sites
CO
to
GENERAL RESPONSE ACTION/ Region V Continued
Remedial Techno logics Northslde Oak
Procona Options IN Grove
LANDFILL GAS
COLLECTION
PaEElve Systems
Plpa Vents
Trench Vents
Activa Vents
Extraction Walls
Bloware
TREATMENT
Thermal Destruction
flaring
Activated carbon
MONITORING X
SURFACE WATER
AND SEDIMENTS
Stormwater controls
Diversion X
Removal Disposal (sediments)
Excavation
Offsite Disposal (sediments)
Treatment
Solidification
D avatar ing
Thermal treatment

Schmalz Spiegelberg Wouconda Kindom Region V
Dump landfill Sand Dump Total

3
• 1
0
1
2
2
1
1
x a
X 3
0
X 6


0
1
1
1
0
2
2
0
0

-------
   11/14/90
                                                   Appendix B2
                                Remedial Technologies  Used at Landfill  Sites


  GENERAL  RESPONSE  ACTION/     Region VI
  Remedial  Technologies         uaw/Mi    ^.   • i     „-,
                    a            Bayou    Cecil     cleve  Compass    Industrial  Region VI
    Process   Options             a~-t~t~^    T-j     ~ ^     TJi.-
              *•                  Sorrel    Lindsay  Reber   Industries   waste     Total

    SOILS/LANDFILL   CONTENTS

  NO ACTION
  ACCESS   RESTRICTION               x        x                                          "
  Deed  Restrictions                                                       x              4
  Land  Use   Restriction                                                                °
  Fencing                           x        x                            x              1
  CONTAINMENT                       x                         X           x              4
  Surface  Controls                  x                                                   2
    Grading                          x                                                   1
    Revegetation                                                                        1
 Cap                                x                                                   0
   Clay  Barrier                                                                        3
   Multibarrier                    x                                                   0
   Soil                                                                  x              2
   Sythetic   Membrane                                                                  0
 REMOVAL\DISPOSAL                                                                      0
 Excavation                                                                             0
                                             xx                    x
   Mechanical  Excav.                                                                   3
                                                                         x              i
   Drum  Removal                             x                                           2
   Consolidation                   j                                                    3
 Disposal  Onsite                                                         X              2  I
   RCRA Type  Landfill                                                                  °  I
 Disposal  Offsite                                                                     °  '
 SOIL   TREATMENT                                                         X              1  '
 Biological   Treatment                                                                  °  '
 Physical  Treatment                                                                    °  '
 Thermal  Treatment                                                                     0  I
   Incineration                                     „                                  1  '
 Offsite  Treatment                                                                     !  I
  RCRA  Incinerator                                                                    °  '
 IN-SITU  TREATMENT                                                                     °  '
  Biodegradation                                                                      °  I
  Vitrification                                                                       ° '
Physical   Treatment                                 x                                  ° '
  Solidification/fixation                                              x              2 I
                                                    x                   x              , |
  Vapor  Extraction                                                                    ^ '

-------
                                            11/14/90
                                                                                          Appendl-x B2
                                                                            Remedial Technologies Used at Landfill Sites
                                            GENERAL RESPONSE ACTION/    Region VI
                                            Remedial Technologies        Bayou    Cecil    Clava  Compass   Induetrial  Ragion  VI
                                              Process Options            Sorrel   Lindsay  Rabar Industrlee   Haute      Total
                                                    CROUNDWATER
                                                    AND LEACHATE

                                            HO ACTION                                        X                                1
                                             -Attenuation                                                                     0
                                             .Observation  •                                                                   0
                                            MONITORING                      XXX                  X             4
                                            INSTITUTIONAL CONTROLS                                              XI
                                            Alternate Hater Supply                                                            0
                                            CONTAINMENT                     X                                                 1
                                            Vertical Barriers               X                                   X             2
                                              Slurry Hall                   X                                   X             2
                                            Horizontal Barriers                                                               0
                                            COLLECTION                                               X                        1  J |
                                            Extraction                                               X                        1  )[
                                              Extraction.Wells                                                                0  ( |
                                              Ext/lr,;. ction Hells                                                             0  ||
                                            Laachato Collection                                                 X             1
„                                            Collection trench                                                               O
i                                              Leachate Drain                                                    X             1
NJ
lyi                                          Onslta Discharge                                                                  0
                                              Aquifer ReinJaction                                                             0
                                              Surface Discharge                                                               0
                                              DawatorIng                                                                      0
                                            Offslto Dlicharga                                                                 0
                                              POTW                                                                            0
                                              Land Application                                                                0
                                            TREATMENT                                                XX             2
                                            Biological Treatment                                                              0
                                              Activated Sludge                                                                0
                                            Chemical Treatmant                                                                0
                                              Oxidation                                                                       0
                                              Ion Exchange Treatment                                                          0
                                              Coagulant Addition                                                              0
                                              Metals Freclptatlon                                                             0
                                              pH Adjustment                                                                   0
                                            Physical Treatment                                                                0
                                              Adsorption                                                                      0
                                              Air Stripping                                                                   0
                                              Sedimentation                                                                   0
                                              Sand filtration                                                                 0
                                              Flocculation                                                                    0
                                              Lime pretreatment                                                               0
                                            Offilto Traatmant                                                                 0
                                              POTH                                                                            0

-------
                                             11/14/90
                                                                                            Appandlx B2
                                                                             Roroodlal  Tachnologlaa Uead at Landfill Sita*
CO
K>
GENERAL RESPONSE ACTION/ Rttglon VI
Mwnaillnl • T«nhrml f^jiam nnyon CQOll CJovo Comptimm Industrial
Proc««M Opt: Ion* Oorr*l Linda Ay tUibar Induat:rl«ft Ha«t*
LANDFILL GAS
COLLECTION X
Pacalvo Syctamc X
Plpa Vanti
Tr«nch Vant« X
Actlva Vant*
Extrr.'-tlon Hall*
BlOVfft-L'B
TaEATMEKT
Ihormal Destruction
Flaring
Actlvatad carbon
MONITORING
SOWACE WATER
AND SEDIMENTS

Stormwatar controls X
Dlvarelon
Removal Disposal (sediments)
Excavation
Off Bit a Dlspoeal(£ad±mant»)
Traatmant
Solidification
Dawataring
Th«rmal treatment

Raglon VI
Total

. 1
1
0
1
0
0
0
0
0
0
0
0



1
0
0
0
0
0
0
0
0

-------
                            11/14/90
                                                                                     Appendix B2
                                                                      Remedial Technologies Used at Landfill Sites
00
GENERAL RESPONSE ACTION/
Remedial Technologies
Process Options
SOILS/LANDFILL CONTENTS

HO ACTION
ACCESS RESTRICTION
Deed Re strict ions
land Use Restrictions
Fencing
CONTAINMENT
Surface Controls
Grading
Ravage t at Ion
Cap
Clay Barrier
Multibarrler
Soil
Synthetic Membrane
REMOVAL /DISPOSAL
Excavation
Mechanical Eicav.
Drum Removal
Con s olldat Ion
Disposal On cite
RCRA Type Landfill
Disposal Offalte
SOIL TREATMENT
Biological Treatment
Physical Treatment
Thermal Treatment
Incineration
Off site Treatment
RCRA Incinerator
IN- SITU TREATMENT
Blodegr adat Ion
Vitrification
Physical Treatment
So lldi t 1 cat Ion / f 1 ra t Ion
Vapor Extraction
Region VII
Arkansas Conservation Doepke Fulbrlght/Sac Lawrence Region VII
City Chemical Disposal River Todtz Total

1
X 1 )
X X 2 |
X X 2 |
X 1 j
X 1 |
X 1 I
X X 2 |
X 1 |
X 1 |
XX X 3 |
X 1|
X 1 I
X X 2 |
0 1
X X 2 |
X 1 1
0 1
X 1 I
o 1
X 1 |
0 t
XX 2
0
0
1 o
0
0
0
0
0
0
0
0
0
, 0
Region VIII
Marshall Region VIII
Landfill Total

1
! 0
t X 1
1 0
1 0
1 X 1
t 0
1 X 1
t X 1
[ X 1
1 0
t 0
1 0
1 0
1 0
! o
t 0
1 0 H
1 o II
1 o it
1 0
1 0
0
0
o
0
0
0
0
0
0
0
0
0
0
0

-------
                        11/14/90
                                                                                  Appendix B2

                                                                   Remedial Technologies U*ed at Landfill Site*
CO

l-o
oc
GENERAL RESPONSE ACTION/
Remedial Technologies
Process Opt ion a
CROUNDWATER
AND LEACHATE
NO ACTION
Attenuation.
Obs ervat ion
MONITORING
INSTITUTIONAL CONTROLS
Alternate Watar Supply
CONTAINMENT
Vertical Barrier*
Slurry Wall
Horizontal Barrier ft
COLLECTION
Extraction
Extraction Wells
Ext/ Inject ion Walla
Loachate Collection
Collection trench
Leachate Drain
Onaite Discharge
Aquifer Rein j o ct ion
Surface Discharge
Dewaterlng:
Offelte Discharge
POTH
Land Application
TREATMENT
Biological Treatment
Activated Sludge
Chemical Treatment
Oxidation
Ion Exchange Treatment
Coagulant Addition
Metals Preciptation
pH Adjustment
Physical Treatment
Adsorption
Air Stripping
Sedlmentat ion
Sand filtration
Flocculation
Lime pre treatment
Of/flit-a Tr«ntmont
POTW
Region VII
Arkansas Conservation Doepke Fulbrlght/Sac Lawrence Region VII
City Chemical Dlfipomal River Todta Total


X X 2
0
X 1
X X X X 4
0
X 1
X 1
X 1
X 1
0
X 1
X 1
X 1
0
0
0
0
0
0
0
X 1
0
0
0
X 1
X 1
0
X 1
0
0
0
X 1
0
X 1
X 1
0
0
X 1
0
0
X 1
X 1
Region VIII
Mar* hall Region VIII
Landfill Total


0
0
0
0
0
0
0
0
0
1 . o
• : ' o
0
0
0
X 1
0
X 1
0
0
0
X 1
0
0
0
X 1
0
0
0
0
0
0
0
0
X 1
X 1
X 1
X 1
0
0
0
0
0

-------
                              11/14/90
                                                                                        Appendix B2
                                                                         Ramadial Tachnologiaa Used at Landfill Sitorn
00
GENERAL RESPONSE ACTION/ Region VII
Remedial Technologies Arkansas Conservation Doopka FuJLbright/Sac
Process Options City Chemical Disposal River
LANDFILL GAS
COLLECTION
Passive Systems
Pipe Vent a
Trench Vents
Active Vents
Extraction Hells
Blowers
TREATMENT
Thermal Destruction
Flaring
Activated carbon
MONITORING
SURFACE HATER
AND SEDIMENTS
Storm water contrail
Diversion
Removal Disposal (sediments)
Excavation
Offsita Disposal {sediments}
Treatment
Solidification
Dewaterlng
Thermal treatment


Lawrence Region VII
Todti Total

0
0
0
0
0 1
0 1
0 1
0 1
0 I
0
0
0


0
0
0
0
0
0
0
0
0

Region VIII
Marshall Region VIII
LandTill Total

0
0
0
0
t 0
t o
1 0
1 0
1 0
0
0
0


X 1
0
0
0
0
0
0
0
0


-------
                                                  11/14/90




                                                                                                     Appendix  B2
CO

'jJ
O
GENERAL RESPONSE ACTION/
Romodlal Technologies
Process Options
SOILS/LANDFILL CONTENTS
NO ACTION
ACCESS RESTRICTION
Daed Restrictions
Land Us a ROE tr let lone
fencing
CONTAINMENT
Surface Controls
Grading
Ra vagetat ion
Cap
Clay Barriar
. Multibarrlar
Soil
Synthetic Membrane
REMOVAL/D ISPO S AL
Excavation
Mechanical Excav.
Drum Removal
Consolidation
Disposal Onclte
RCRA Type Landfill
Disposal Off site
SOIL TREATMENT
Biological Treatment
Physical Treatment
Thermal Treatment
Incineration
Off sit a Treatment
RCRA Incinerator
IN- SITU TREATMENT
Biodagr adat ion
Vitrification
Physical Treatment
So lldl f icatio n/ f irat ion
Vapor Extraction
Region IX
Jibboom Operating Ordot Region IX
Junkyard Industries Disposal Total

X 1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
X 1
X 1
0
0
0
0
X 1
0
0
0
0
0
0
0
0
0
0
0
0
0

-------
 11/14/90


                                                 Appendix B2
                                                                    It
GENERAL RESPONSE ACTION/    Ration  IX                              |  |
Remedial Technologies         Jlbboom   Operating    Ordot   Region IX||
  Process Options           Junkyard   Industrias  Disposal   Total  |J
        CROUNDWATER                                                 |
        AND LEACHATE                                                |
                                                                    I
NO ACTION                                                         0 |
  Attenuation                                                     0 |
  Observation                                                     0 |
MONITORING                                                        0 |
INSTITUTIONAL CONTROLS                                            0 |
Altarnata Hatar Supply                                            0 |
CONTAINMENT                                                       0 |
Vertical Barriers                                                 0 |
  Slurry Wall                                                     0 |
Horizontal Barriers   _                                            0 |
COLLECTION                                                        0 |J
Extraction                                                        0 | ]
  Extraction Hells                                                0 |}
  Ext/Injection Hells                                             0 ||
Leachata Collection                                               0
  Collection trench                                               0
  Leachate Drain                                                  0
Onsite Discharge                                                  0
  Aquifer Relnjection                                             0
  Surface Discharge                                               0
  Dewatering,                                                     0
Offsito Discharge                                                 0
  POTW                                                            0
  Land Application                                                0
TREATMENT                                 X                       1
Biological Treatment                                              0
  Activated Sludge                                                0
Chemical Treatment                        X                       1
  Oxidation                                                       0
  Ion Exchange Treatment                                          0
  Coagulant Addition                      X                       1
  Metala Preciptation                                             0
  pH Adjustment                                                   0
Physical Treatment                        X                       1
  Adsorption                              X                       1
  Air Stripping                           X                       1
  Sedimentation                                                   0
  Sand filtration                                                 0
  Flocculation                                                    0
  Lijne pretreatment                                               0
Offiite Treatment                                                 0
  POTW                                                            0

-------
11/14/90
                                                     Appendix B2
GENERAL RESPONSE ACTION/ Region IX
Remedial Technologies Jibboom Operating
Process Options Junkyard Industries
LANDFILL GAS

COLLECTION
Passive Systems
Pipe Vents
Trench Vents
Active Vents x
Extraction Wells x
Blowers
TREATMENT x
Thermal Destruction x
Flaring x
Activated carbon
MONITORING x

SURFACE WATER
AND SEDIMENTS
Stormwater controls
Diversion
Removal Disposal (sediments)
Excavation
Offsite Disposal (sediments)
Treatment
Solidification
Dewatering
Thermal treatment

Ordot Region IX |
Disposal Total
1
1
0 1
0 1
0 1
0 1
1 1
1 1
0 1
1 1
1 1
1 1
0 1
1 1
!]
(

x 1
0
0
0
0
0
0
0
0

-------
                                              11/14/90
                                                                                        Appendix B2
                                                                          Remedial Technologies Us ad at Landfill Site*
00
GENERAL RESPONSE ACTION/ Region X
Remedial Technologies Colbert Commencement Nor the Ida
Process Options Landfill Bay HA
SO I! 3 /LANDFILL CONTENTS
HO ACTION
ACCESS RESTRICTION x
Deed Restrictions X
land Use Restrictions X
Fencing
CONTAINMENT X
Surface Control!
Grading
Reveget at lo n
Cap X X
Clay Barrier
Multibarrier X
Soil
Synthetic Membrane
REMOVAL /D ISPOSAL
Excavation
Mechanical Excav.
Drum Removal
Consolidation
Disposal Onslte
RCRA Type Landfill
Disposal Offsite
SOIL TREATMENT
Biological Treatment
Physical Treatment
Thermal Treatment
Incineration
Off* it • Treatment
RCRA Incinerator
IN-9ITU TREATMENT
Blo
-------
                                         11/14/90
                                                                                  Appendix B2

                                                                    Remedial  Technologies  Used at  Landfill Site*
ro

w
-f-

GENERAL RESPONSE: ACTION/
Remedial Technologies
Procefic Options
GROONDHATER
AMD LEACHATE

NO ACTION
Attenuation
Ob tarnation
MONITOR INC
INSTITUTIONAL CONTROLS
Alternate Hatar Supply
CONTAINMENT
Vertical Barriers
Slurry Hall
Horizontal Barrier*
COLLECTION
Extraction
Extraction Hell*
Ext/ Inject ion Wells
Laachata Collection
Collection trench
Laachata Drain
Onslte Discharge
Aquifer Rain j act ion
Surface Discharge
Dewaterlng
Off cite Discharge
POTH
Land Application
TREATMENT
Biological Traatment
Activated Sludge
Chemical Treatment
Oxidation
Ion Exchange Treatment
Coagulant Addition
Metals Praciptation
pH Adjustment
Physical Treatment
Adsorption
Air Stripping
S edlmant at ion
Sand filtration
riocculatlon
Lime pretraatmant
Offclta Treatment
POTW
1
Region X |
Colbert Commenceaent North* Ida Region X
Landfill Bay HA Total



0
0 1
0 )
X X X 3 |
X X X 3 |
X X X 3 |
0 1
0
0
0
XXX 3
XXX 3
XXX 3
0
X 1
0
X 1
0
0
0
0
0
XXX 3
0
XXX 3
0
0
0
0
0
0
0
0
X 1
0
XXX 3
0
0
0
0
0
0
t
1
GRAND
TOTAL



6
I 1
1 1
I 59
1 21
1 24
1 12
13
13
1
40
43
24
2
27
10
19
0
1
0
6
3
S
1
32
9
2
12
2
2
2
a
i
29
ie
23
S
2
3
2
15
15
••*»-••••*"••
1
1
1
1
-1
!
1
1
1
[









































-------
                                        11/14/90
                                                                                   Appendix B2
                                                                     Remedial Technologle* 0«ed at Landfill Sit«s
CO
GENERAL RESPONSE ACTION/ Region X
Rama dial Technologies Colbert Commencement North* Ida
Pro cose Option* landfill. Bay VIA
LANDFILL GAS
COLLECTIOH
Paejive Syttoms X
Pipo Vant*
Tranch Vents
Active Vente
Extraction Wells X
Blowera
TREATMEHT
Tharmal Destruction
Flaring X
Activated carbon
MONITORING XX X
SURFACE HATER
AND SEDIMENTS
Stormwatar controls
Divareion
Ramoval Diepotal (eedlments )
Excavation
OtfeLta DiBpoeal (Badiments)
Treatment
Solidification
Dana taring
Thermal treatment
Region X
Total

0
1
0
0
0
1
0
0
0
1
0
3


0
0
0
0
0
0
0
0
9 M
CRAND
TOTAL
—


20
17
1
10
11
9
5
8
12
9
3
21
II
II
*M
1 1
1 1
II
11
II
M
M
M
II
II
II
M
II
1 1
10
 5
 5
 5
 2
 4
 4
 4
                                                                                                                              M
                                                                                                                              II
                                                                                                                              ||
                                                                                                                              II
                                                                                                                              M
                                                                                                                              II
                                                                                                                              II
                                                                                                                              II
                                                                                                                              II
                                                                                                                              II
                                                                                                                           .1  II
                                                                                                                            = 11

-------
CO

UJ
ON
Appendix B-3
BREAKDOWN BY REGION OF REMEDIAL TECHNOLOGIES USED AT LANDFILL SITES
Page 1 of 2
Environmental
Media
Soils/Landfill
Contents
Soils/Hot Spots
Groundwater and
Leachate

General Response
Actions
No Action
Access Restriction
Containment
Removal/Disposal
Onsite Treatment
In Situ Treatment
Offsite Treatment
No action
Institutional Controls
Containment

Collection

Remedial
Technologies

Deed Restrictions
Fencing
Land Use Restrictions
Surface Controls
Cap
Excavation
Disposal Onsite
Disposal Offsite
Thermal Treatment
Biological Treatment
Physical Treatment
Thermal Destruction

Alternate Water Supply
Vertical Barriers
Horizontal Barriers
Extraction
Leachate Collection
Region 1
(10 sites)
0
2
3
1
3
6
4
0
1
1
0
1
0
0
5
0
1
7
3
Region 2
(16 sites)
0
0
9
0
6
13
2
0
1
1
0
1
0
1
2
7
0
13
8
Region 3
(14 sites)
1
1
0
1
4
11
5
0
1
1
0
3
0
1
4
0
0
4
4
Region 4
(10 sites)
0
2
3
4
5
8
4
2
0
0
0
3
0
0
3
0
0
4
4
Region 5
(25 sites)
0
12
IS
7
13
22
10
2
6
4
1
2
1
1
6
3
0
10
5
Region 6
(5 sites)
0
0
4
1
1
3
3
0
1
1
0
2
0
1
0
2
0
1
1
Region 7
(5 sites)
1
2
1
1
2
1
1
1
2
0
0
0
0
2
1
1
0
1
0
Region 8
(1 site)
0
0
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
1
Region 9
(3 sites)
1
0
0
0
0
1
1
0
1
0
0
0
0
0
0
0
0
0
0
Region 10
(3 sites)
0
1
0
1
0
2
0
0
0
0
0
0
0
0
3
0
0
3
1
Total
(92 sites)
3
20
36
16
35
68
30
5
13
8
1
12
1
6
24
13
1
43
27

-------
Cd
Appendix B-3
BREAKDOWN BY REGION OF REMEDIAL TECH PiOLOGIES USED AT LANDFILL SITES
Pffe lot I
Knvironmental
Media
Ciroundwatcr and
J^eachatc
(Continued)

l-andfill Gas


Surface Water and
We Hands
Sedintcnt.s


General Response
Actions
Treat men t
[Disposal
Monitoring
Collection
Trcalmenl
Monitoring
Containment
Removal Disposal

Treatment

Remedial
Technologies
Biological Treatment
Chemical Treatment
Physical Treatment
Offsile Treat me nl (at
POTWJ
Onsile Discharge
OtTsilc Discharge
Monitoring welts
Passive Vents
Active Sptems
Thermal l>esiniction
Aclivaled Carbon
Monitoring wells
Slormwater Controls
Rxcavalion
Ortsi'le Disposal
Solid irication
Dewalenng
Thermal Treatment
Region 1
(10 siles)
1
3
4
]
0
1
7
4
1
2
0
2
1
I
0
I
1
0
Region 2
(16 siles)
3
4
6
6
0
2
11
5
5
5
3
5
5
3
I
0
2
1
Region 3
(11 sites)
1
0
3
I
0
0
6
3
2
I
0
3
0
0
1
0
0
0
Region 4
(10 sites)
1
0
3
2
0
0
7
2
0
0
0
1
I
0
0
1
1
0
Region 5
(25 sites)
2
3
7
4
0
0
17
1
2
3
0
6
1
1
0
2
0
0
Region 6
(5 sites)
0
D
0
0
0
0
4
1
0
0
0
0
1
0
0
0
0
0
Region 7
(5 siles)
1
1
1
1
0
0
4
0
0
0
0
0
0
0
0
0
0
0
Region 8
(1 site)
0
0
I
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
Region 9
(.1 siles)
0
1
1
0
0
0
0
0
1
1
0
1
1
0
0
0
0
0
Region 10
P sites)
0
0
1
0
0
0
3
0
0
0
0
3
0
0
0
0
0
0
Total
(92 sites)
9
12
29
15
0
3
59
17
11
12
3
21
10
5
2
4
4
1

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