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
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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.
ES-3
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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
ES-4
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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.
ES-5
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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,
1-1
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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.
1-3
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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:
2-3
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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
-------
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
-------
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
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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
-------
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
-------
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
-------
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"
-------
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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to
to
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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to
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.
-------
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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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
3-1
-------
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.
-------
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
3-3
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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
3-4
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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.
3-5
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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
-------
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
-------
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-
3-17
-------
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
3-18
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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
3-19
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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-
3-20
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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.
3-21
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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.
3-22
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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
-------
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
-------
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
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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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
• 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
-------
• 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
-------
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.
4-4
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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.
4-5
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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
-------
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:
4-11
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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
4-12
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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.
4-14
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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
4-15
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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.
4-ls
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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.
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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.
4-28
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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
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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.
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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
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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
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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
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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
-------
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
-------
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.
-------
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.
-------
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.
-------
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
-------
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.
-------
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
-------
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
-------
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.
-------
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
5-22
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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
5-23
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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.
5-24
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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)
5-25
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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
5-26
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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
5-27
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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.
5-28
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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.
-------
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.
-------
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.
-------
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.
-------
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
-------
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
-------
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
-------
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
-------
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
-------
Section 7
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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
-------
-------
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
-------
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
-------
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
-------
BURIED
DRUMS
AREA
GATE x
HOUSED
_JD
J
R-3
LEGEND
RESIDENTIAL WELLS
MONITORING WELLS
A2-2
Figure 2-1
SITE PLAN
EXAMPLE SITE
-------
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
-------
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
-------
UNNAMED TRIBUTARY
Scale:
1"=5280ft.=
mile
figure 2.2
SURFAC E WATER FOR
EXAMPL E SITE
A2-5
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
>
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
-------
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
-------
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
-------
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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.
-------
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
-------
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
-------
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
-------
-------
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
-------
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
-------
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
-------
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
-------
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
-------
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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