RCRA Showcase Pilot
Region I
Ten Most Wanted List
An Approach to Streamline Corrective Action
Overview
The EPA New England Regional Office has recently released a revised Ten Most Wanted List.
The list, which was first issued in 1995 to support the region's voluntary RCRA Corrective
Action initiative, is a compilation of the ten most common comments provided on RCRA
Facility Investigation (RFI) work plans and reports.
In the New England Region of EPA, Corrective Action work on a voluntary basis is
intended to be very performance-based. While the review time of work plans by EPA staff is
often reduced, the quality of the final products are still expected to be as good as or better than
work conducted under a permit or order. The Ten Most Wanted List is intended to be the RFI
work plan comments issued to RCRA facilities in advance of the preparation of the work plan so
that re-work after the submission of the RFI report is minimized or avoided altogether.
Description
•	What makes this project innovative? (Does the project speed achievement of Environmental
Indicators? Why will the pilot project/cleanup work?)
Many project mangers have a sense of the comments they make repeatedly on numerous RFI
work plans and reports. In Region I, we have pooled this experience and distilled it into our
ten most wanted list of the topics we most often make comments on. This innovative
"comment letter in advance" provides a tip sheet which minimizes generic flaws in work plans
and other reports and accelerates the Corrective Action process.
•	What are the benefits of this project (e.g., environmental, community, economic, other)?
The benefits are economic and environmental. Providing facilities a tip sheet on the most
common errors in their submittals to the agency helps them avoid these mistakes. Avoiding
these mistakes shortens our review and their comment response time frames, saving the facility
money and speeding the site more efficiently to meet the Environmental Indicator goals (i.e.,
unacceptable human exposures under control and migration of contaminated groundwater
under control) and to meet the final remedy goals.
•	How have you involved stakeholders in developing this project (for example; owner/operator,
tribe, state/local agencies, local community, redevelopers, other interested parties)? Where
applicable, please indicate the level of support of the owner/operator.
There is no formal participation from outside stakeholders on this pilot; however, in its use and
our interactions with facilities and the public, we continually update the document as we

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encounter ambiguities or other fuzzy points in the document or as new sources of common
error arise (e.g., each new guidance or newly recognized technical need (such as our current
program wide re-examination of how we characterize indoor air) brings new sources of
potential disagreement between EPA and other stakeholders.)
•	Who are the pilot participants and what is their role (for example; states, tribes, local agencies,
other federal agencies, regulated industry, and environmental and community groups)?
Every facility we have initiated work with within the last three years is a participant in that they
have received the ten most wanted list as part of our initial interaction.
•	What is the potential for applying this innovative approach to other sites?
This pilot is in use and has been provided to at least 40-50 facilities over the past several years.
•	What are the proposed project milestones and associated dates?
The Ten Most Wanted list is a tool in use at every site we initiate Corrective Action with. We
continually update it and see no end to its use. Given the nature of this innovation there are no
milestones associated with it.
•	Provide a brief description of the pilot facility, including location and regulatory status if pilot
addresses a specific facility.
As noted above there is no single pilot facility.
•	How and when will pilot progress be measured and reported?
There is no specific measure or measurement point. This tool is one aspect of broader changes
in how we approach and interact with facilities on the start up of Corrective Action. We have
improved the pace at which we initiate and complete Corrective Action in our region and feel
this tool has made a valuable contribution to that improvement.
•	Who will oversee the pilot (State and/or Region)?
Region.
•	Who are the key Regional/State contacts responsible for managing the pilot project (name,
phone, e-mail, affiliation)?
Ernest Waterman
617-918-1369
waterman.ernest@epa.gov
USEPA Region I

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EPA New England Region's 10 Most Wanted List (revised July 6. 2001)
This list contains guidance on several of the most frequent recurring issues encountered when
conducting an RCRA Facility Investigation (RFI) or discovered when reviewing an RFI.
Conceptual Site Model
A Conceptual Site Model is an assimilation of known site history, general theoretical knowledge,
and site specific sampling data into a picture or description of how releases of contaminants have
or are likely to have been released at a site, where contaminants are expected to move, and what
impacts such movements may have. It serves as a primary vehicle for organizing and
communicating information and focusing resources on the contamination issues that represent
the most significant problems at any given point in time. A good CSM is communicated through
a variety of means to assure it serves as a common understanding of the site. It is revisited and
revised as necessary as new data is generated at the site. When well developed the CSM serves
as a tool which screens not only what is known and unknown, but identifies which unknowns
must be resolved and when decisions can be made in the face of remaining uncertainty through
provision of adequate contingency actions or other uncertainty management measures. The CSM
will serve as a robust backdrop for design of study elements throughout the investigation process
and will indicate when we have arrived at a sufficient level of site characterization to support a
remedy decision.
As an example of the first use consider the problem of selecting sample parameters. Sampling
parameters at each sampling site should reflect a consideration of facility processes and
operations throughout the entire history of the site. The parameters selected should encompass
all contaminants whose occurrence at the locale is plausible. An assumption of all plausible
contaminants likely to have been released at any area of the site can also be supported by field
screening (e.g. headspace analyses, soil gas survey, X-Ray Fluorescence (XRF)) and collection of
samples for laboratory screening analyses (e.g. Total Petroleum Hydrocarbons (TPH), Total
Organic Halogens (TOX), Total Organic Carbon (TOC)).
Given the uncertainty in site histories, the parameter assumptions should be confirmed by
analyses for a wide range of hazardous constituents (e.g. Target Analyte List (TAL) and Target
Compound List (TCL) of the Contract Laboratory Program (CLP) protocol or 40 CFR Part 264
Appendix IX) in at least some samples taken from the areas showing the highest degree of
contamination. At some facilities gaps in historical knowledge or length and variety of site use
will recommend greater use of broad spectrum analyses. As our understanding of a site evolves
it may be possible to restrict the range of sample parameters.
In evaluating the completeness of our site characterization we might use the CSM as a guide
through a set of questions similar to the following to evaluate our level of understanding of site
conditions:
• Do I have data to address every known and reasonably expected source area?

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•	Do I have a "best fit" explanation of the data that works far better than any other
interpretation?
•	Do I have data which doesn't fit into this best fit and does it suggests further problems
which require additional characterization (e.g. an unexpected source area)?
•	What other uncertainties do I have? What limits can I place on them?
•	Are these unexplained data and other uncertainties significant (i.e can they change my
picture of what needs to be cleaned up or how it can be cleaned up)?
•	Can I control any significant uncertainties without answering them now (e.g. a modified
remedy option or a contingency plan renders the uncertainty insignificant).
Quality Assurance Project Plans and Data Validation
Every study conducted for EPA in support of RCRA Corrective Action activities requires a
Quality Assurance Project Plan (QAPP) which outlines why data is being collected, what data
quality is necessary to meet the objectives of the data collection, and what quality
assurance/quality control procedures will be instituted to demonstrate the necessary quality has
been achieved.
As stated in the Preface to The Region I, EPA-New England Compendium of Quality Assurance
Project Plan Requirements and Guidance:
"The Region I, EPA-New England Quality Assurance Unit has restructured its Quality
Assurance Project Plan (QAPP) Program in response to the recently reissued EPA Order
5360.1 CHG 1, July 1998. Among other requirements, this "QA Order" requires the
development, review and approval of QAPPs for all environmental data operations
performed by or on behalf of EPA. The term "environmental data operations" refers to
activities involving the collection, generation, compilation, analysis, evaluation and use of
environmental data. In addition, these requirements are incorporated into voluntary,
consentual or unilateral enforcement agreements, decrees and orders. The Region I, EPA-
New England Compendium of Quality Assurance Project Plan Requirements and Guidance
and its attachments implement within EPA-NE the national QAPP requirements specified in
"EPA Requirements for Quality Assurance Project Plans for Environmental Data
Operations", EPA QA/R-5, October 1998, or most recent revision, and the "EPA Quality
Manual for Environmental Programs", 5360, July 1998.
As a Regional implementation document, the Region I, EPA-New England Compendium of
Quality Assurance Project Plan Requirements and Guidance;
-outlines a Regional systematic planning process to ensure project quality objectives are
appropriately identified
-defines a minimum set of project QA/QC activities and procedures to ensure that data
collected for this Region are of known and documented quality and can be used in
environmental decision making

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-specifies project information that must be compiled and included in a QAPP to document
that project activities have been properly planned
-and, assigns roles and responsibilities to project management/personnel and to EPA-NE to
establish accountability."
Data Validation is a review process at the tail end of data collection to verify compliance with the
QAPP and document the quality of the collected data. Because we will make reference to
differing degrees of data validation elsewhere in this document here is a brief overview of EPA-
New England's three tiers of data validation:
•	Tier I: A completeness evidence audit is performed, in accordance with the Region I CSF
Completeness Evidence Audit Program, dated 7/3/91, to ensure that all laboratory data
and documentation are present.
•	Tier II: A Tier I completeness evidence audit is performed, and, in addition, the results of
all Quality control checks and procedures are evaluated and used to assess and qualify
sample results. Tier II data validation is performed in accordance with the Region I
Laboratory Data Validation Functional Guidelines. Tier II validation takes approximately
50% of the time required to perform a Tier III validation.
•	Tier III: A full data validation is performed. Tier III includes Tier I and Tier II
procedures plus an in-depth examination of all raw data to check for technical,
calculation, analyte identification/analyte quantitation, and transcription errors. Tier III
data validation is performed in accordance with the Region I CSF Completeness
Evidence Audit Program and the Region I Laboratory Data Validation Functional
Guidelines.
At a minimum, all laboratory data should be carried through Tiers I or II. For data which will be
used in the risk assessment, a minimum of Tier II data validation should be conducted. As long
as Tiers I or II have been completed, full validation (Tier III) can always be performed at a later
date. All biota should be validated at Tier III and it is highly recommended that sediment
samples receive Tier III. It is preferable to have some Tier III data validation for other media. A
limited number of samples may be acceptable depending upon the quality of the other lab results.
Each new sampling round for each medium should also have performance evaluation samples
included.
Presentation of Data
Typical data presentations and tabulations that facilitate joint understanding of site data and its
significance are presented below. EPA also strongly encourages submission of data in electronic
form as an aid to EPA's review and interpretation of the data and preparation of comments.
Until written procedures and requirements for electronic data submissions are formalized, please
contact the RCRA facility manager for your facility to discuss specifics regarding electronic data
deliverables.

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•	Figures- Site data should be presented graphically to the extent practicable. Graphics
should be legible, consistent, to scale, contain sufficient detail to show the data they are
based on and to clearly show they are supported by the data. Examples of information to
be presented graphically include but are not limited to:
Locus Plan
Site Plan (including abutters)
Site Plan with Areas of Concern (AOC's)\Solid Waste Management Units
(SWMU's)
Site Plan indicating Sampling Locations
Soil Borings
Wells
Surface Water
Geological Cross-Sections
Groundwater Contours
Overburden and Piezometric Head Contours
Flow Lines
Contaminant Plume Contours
Soil, GW and Soil Gas
Graphical presentations of the vertical and horizontal extent of contamination in
each media
Groundwater plume contours
Soil gas plume contours
Maps of contaminant in sediments
•	Tables- Tables should include appropriate units and regulatory media protection criteria
(if appropriate).
Summary of Well Installations:
• ID,
Screen Interval,
Construction Details
Groundwater Results:
Groundwater Level Measurements and Field Sampling Results,
Results of Hydrogeological Characterizations,
Slug Tests, Pump Tests
Sample Analytical Results:
Soil Analyses—Field Headspace and Laboratory
Groundwater Laboratory Analyses
Soil Gas Analyses
Risk Assessment Tables
• References
•	Appendices-
Boring Logs
Standard Operating Procedures
Hydrogeological Data

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Raw Data
Modeling Input Parameters and Assumptions
Modeling Output
Laboratory Analytical Results
Lab Reports
QA/QC Program and Results
Chain of Custody Reports
Risk Assessment (These can be stand alone documents submitted after the RFI)
• Human Health
Ecological
Establishing Ground Water Investigation Programs
Ground water investigation programs are required to assess the nature and extent of
contamination in aquifers, water supply wells, and other receptor areas. Well placement,
installation, design, construction, development, and sampling must be conducted in a manner
which defines the nature and extent of contamination and maximizes representativeness of
groundwater samples. Fully defining the extent of contamination will likely require phased well
placement. Commonly missed points include:
•	Well placement should reflect consideration of the probable transport pathways of
contaminants.
•	Generally, no more than 10 feet of screen length should be used for wells which are
screened across the surface of the water table (with approximately half the screen set
below the average expected water table) and wells below the water table should depend
on the site stratigraphy and have screen lengths no greater than 5-10 feet.
•	All wells must be fully developed (pumped) to assure that sediment is removed and that
the water quality of the well reflects the ambient aquifer and not contaminant artifacts.
•	Particular attention should be made to wells installed in silt or clays as the installation
method/procedure can often result in a decreased permeability bias. For instance, during
installation of wells in clays using hollow-stem augers, the constant scrapping of the
auger against the side of the borehole can cause smearing of the clay. This smearing can
cause a decrease in the effective permeability of the well—this permeability bias may go
undetected and result in erroneous conclusions about the soil unit.
•	Split spoon sampling conducted during installation of the well provides valuable
information as to the soil type, delineation of soil heterogeneity, and contaminant
distribution. Generally, in order to obtain accurate information regarding the continuity
of geologic conditions at a site, continuous split spoon sampling should be performed at a
representative set of wells.
Mud rotary or other drilling methods that introduce foreign materials into the well should

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be avoided.
•	Avoid cross-contamination between aquifers along well bore.
•	Sampling of wells by the low-flow methodology is generally preferred.
Characterization for Non-Aqueous Phase Liquids (NAPLs)
Materials which are insoluble or poorly soluble in water will tend to form separate phases in the
saturated zone of the subsurface. When the materials are lighter than water, the separate phase
will float on top of the water table. These materials are called light non-aqueous phase liquids
(LNAPLs).
When the material is denser than water, the separate phase will sink down through the saturated
zone until a relatively impermeable boundary is encountered. These materials are called dense
non-aqueous phase liquids (DNAPLs). DNAPL can migrate in directions other than that of
groundwater flow. Chlorinated solvents are the DNAPL forming material most commonly
encountered by RCRA Corrective Action. DNAPL can migrate in directions other than that of
groundwater flow (e.g., flow along bedrock topography).
Detection of NAPLs at facilities where materials likely to form plumes may have been released
requires particular planning for well placement and sampling. It also requires examining the well
sampling data obtained at the site for particular clues to NAPL presence. When the likelihood of
NAPL presence has been established, special field screening techniques may also be applicable
for use at the Facility.
Background Sampling
At many facilities some of the Media Protection Standards for remedy selection will be based
upon the background levels of hazardous constituents. This will occur whenever background
levels are above risk based goals or applicable standards. Knowledge of background levels will
always be an issue for heavy metals and other naturally occurring materials. Background levels
of synthetic organic compounds should only be an issue at sites where sources of contamination
outside the facility exist.
Regional values or other background estimates available in the literature may not be relied on in
setting Media Protection Standards. Regional values are too highly variable for use in this
context though they may be useful guides early in the investigation process. Site specific
sampling must be conducted to determine background levels.
Background samples to establish background levels must meet the stringent objective of
representing what site conditions were before facility releases occurred. Knowledge of site
history, geology, hydrology and meteorology must be used to select sample locations that present
environmental setting conditions that are similar to areas of concern but are not impacted by
releases. At many sites this will require off-site samples. Meeting this objective will often end

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up involving more than one round of sample site selection. In some settings (e.g. estuaries) no
true background will exist and background will have to be established using reference stations.
Selection of background sampling locations and review of background sampling results should
be coordinated with EPA.
Receptors and Exposure Assessment in Risk Characterization
A principal element of all risk assessments is the proper identification of the potential receptors
(i.e. the populations of human and animal life that is potentially exposed to hazardous
constituents in the environment). The assessed populations should include an analysis of the
more susceptible groups as well as the general population. Key to this is an understanding of the
potential pathways of hazardous waste through the groundwater/surface water, soils, and air and
the identification of those pathways that pose significant risk. The HERA SOW is the best
reference on this topic. RCRA risk assessments use Superfund guidances whenever possible.
Points to Remember When Looking at Human Receptors:
•	EPA Risk Assessment Guidances and when to use them:
Use EPA guidances listed in the Human Health and Environmental Risk
Assessment(HERA) Statement of Work (SOW),
• Make sure to receive the most current version of the SOW from the EPA RCRA
Facility Manager,
The baselinerisk assessment examines the risks at a site before any remedial action
takes place (Risk Assessment Guidance for Superfund 'RAGS', Part A),
Risk assessment may estimate clean-up goals before remediation(RAGS part B)
and verify the appropriateness of these goals after completion of the baseline risk
assessment.
Risk assessment may qualitatively evaluate how much risk may be reduced by a
given remedial action (RAGS part C). A facility can compare the risks from
remedial alternatives as an addendum to a baseline risk assessment. (Examples of
remedial alternatives are bioremediation, containment, excavation, institutional
controls, and natural attenuation.)
•	Selecting Chemicals of Concern (COC's):
If certain contaminants present on the site are not being considered as Chemicals of
Concern (COC's), explain why.
Shorten the list of COC's using the Region IX Preliminary Remediation Goals
Tables the EPA Soils Screening Levels Guidance or screening levels calculated in a
similar way.
Comparisons between site contaminants and background concentrations cannot be
used to eliminate chemicals as COC's in the risk assessment.
Data and sampling issues:
Data for the risk assessment should be CLP-type or equivalent.
The sampling should include the EPA standard lists of chemicals (TAL/TCL) and

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or Appendix IX and any unusual chemicals that are unique to a given facility.
For air, soils, sediments, and surface water, calculate risk based on the 95% upper
confidence limit of the mean. EPA recommends collecting a minimum of 10-20
samples per exposure area to make this calculation.
For groundwater, calculate the average concentration using wells in the center of
the plume of contamination; if there is no plume use contaminated wells. Use only
unfiltered groundwater for the risk assessment. EPA prefers low-flow sampling for
the metals and long-chain volatiles.
For surface soils, collect samples from a 0 to 1 foot depth for risk assessment. (EPA
will accept 0-3" or 0-6" sampling if the facility shows that the contamination did
not extend as far as one foot.) If an excavation or construction worker scenario is
appropriate for the site, soils should be collected from 0 depth to the depth at which
exposure is reasonable (the default value is 10 feet).
Hot spots may need less sampling than general contamination. If a removal is
planned, hot spots are treated separately in the risk assessment.
• Information on human receptors:
Include information about populations at risk, people living adjacent to the site, and
special populations near the site. Include maps showing schools, day care
facilities, homes, recreational areas, agricultural land, prevailing wind directions,
contaminant plumes, public water supplies, and drinking water wells.
Indicate whether contaminants leave the site and come into contact with these
populations. Indicate whether workers at the facility contact site contaminants.
All potential routes of exposure should be covered adequately (e.g. inhalation of
gases or particulates, incidental ingestion of soils, dermal contact with soils,
ingestion of groundwater).
If people live near the site and could potentially contact site contaminants, a
residential scenario should be used rather than an industrial scenario.
Each risk assessment must include point estimates for risk at central tendency and
high end exposure scenarios. Monte Carlo analysis(optional) should only be used
for describing uncertainty.
Development of Media Protection Standards (MPSslt
MPSs are contaminant concentration levels in the affected media (e.g., soil, water, air) designed
to protect human health and the environment from exposure to the contaminant. MPSs are also
designed to prevent contaminant transfer to another media (through leaching, run-off,
volatilization, etc.) that would result in unsafe levels for human health and the environment.
MPSs guide selection of final remedies. Remedies must be able to prevent exposure to media
containing hazardous constituents in excess of the established MPS.
Draft proposed MPSs are initial cleanup goals that are protective of human health and the
environment. They are developed early in the investigation/remediation process based on readily
available information (such as state remediation goals or other risk-based concentrations) and can
be modified to reflect results of a baseline risk assessment. They usually represent a point of

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departure of 10"6 for cancer risk or a hazard index of 1 for non-cancer risk in humans. These
risks are calculated based on the latest toxicity data, considering assumptions appropriate for
current and future land uses at the RCRA Corrective Action facility. They consider the
cumulative risks to humans from multiple pathways of exposure. Initially, they are based on
considerations of risk alone with limited consideration of practicability or technical feasibility. If
toxicity information is lacking for a particular chemical, draft MPSs are developed after
consultation with EPA.
MPSs designed to protect ecological receptors can be established through risk management
decision-making based on the results of an ecological risk assessment. As part of the ecological
risk assessment, assessment endpoints are identified, in concert with EPA and other stakeholders.
Assessment endpoints are explicit expressions of the actual environmental value that is to be
protected and include both a valued ecological entity and an attribute of that entity that is
important to protect (e.g., aquatic community composition and structure in the portion of a
stream or river downstream from a site, reproduction and population maintenance of bass in an
on-site pond, etc.). Because assessment endpoints generally refer to characteristics of
populations, communities, and ecosystems, changes in these characteristics may be difficult to
measure. Therefore, measures of effect (also known as measurement endpoints), which are
measurable ecological characteristics, may be selected to measure the response of the assessment
endpoint to a stressor (e.g., percent mortality in laboratory toxicity testing of benthic organisms
and percent mortality of caged bass in the on-site pond could be respective measures of effect
selected to evaluate the assessment endpoint examples presented above). MPSs are then
established at a level that prevents adverse effects to the assessment endpoint.
Ecological risk assessment will only proceed to the point of establishing MPSs if the results of
the problem formulation stage and any subsequent ecological assessment suggest that
unacceptable ecological risk is occurring. The problem formulation stage is the stage of the
ecological risk assessment during which assessment endpoints are identified; a conceptual model
of potential exposure pathways, ecological receptors, and ecological effects is developed; and an
analysis plan for evaluating the relationship between contaminant levels and ecological effects is
assembled.
Final proposed MPSs are chemical-specific proposed cleanup levels documented in the
Corrective Measures Study. They may differ from proposed draft MPSs because of
modifications resulting from consideration of various uncertainties, technical and exposure
factors, and considerations of the remedy chosen. For example, the modifications could consider
the naturally occurring background concentration of the substance, established regulatory limits,
or technological limitations (e.g., analytical detection limits). EPA's policy is to select remedies
that can achieve MPSs for the more protective end of the cancer risk range of 10"6 to 10"4 and to
maintain a hazard index below 1. The final proposed MPSs combine considerations of both
human and ecological risks for all appropriate pathways.
Many states, including some in New England, have developed state remediation regulations
which include numerical remediation standards. EPA-New England has not endorsed any one set
of numerical standards for use at all RCRA Corrective Action facilities. Use of such standards

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may be appropriate to use as MPSs for a given facility. However, the pathways, scenarios, and
toxicity information on which the standards are based must be evaluated to ensure that the
standards will adequately protect human health and the environment.
Field Oversight
A significant percentage of site characterization errors originate in the field as sampling errors.
Sampling standard operating procedures (SOPs) are often broadly and ambiguously written and
not reflective of variable conditions which will be encountered in the field. Sampling personnel
are often inexperienced and poorly versed in the procedures they are using and the acceptable
adaptations of these conditions allowable to meet field conditions.
Sampling SOPs should be clear, comprehensive, and up to date. Facilities or their contractors
should maintain logs which record all sampling event data required in the relevant SOPs and
general conditions of all sampling events (e.g. weather conditions). They should conduct internal
audits to verify compliance with sampling SOPs and, at least for major field efforts or over the
course of extended investigations, should arrange some third party oversight of sampling
procedures. Provisions for unscheduled visits by EPA or our state agency counterparts can fulfill
this third party oversight need.
• Indoor Air
The following provides EPA New England Region's RCRA Corrective Action Program's policy
with respect to indoor air risk and the use of OSHA Permissible Exposure Levels (PEL).
•	For purposes of RCRA Corrective Action, indoor air risk may be described as the impact
or potential impact to human health of the inhalation of volatile organic compounds
(VOC) as a result of the physical/chemical migration of VOCs from soils and/or
groundwater into buildings. Two factors make the characterization of indoor air risk by
direct empirical evidence difficult.
First, very low concentrations of some volatile organic constituents (e.g., 1,1-
dichloroethylene, vinyl chloride) have been demonstrated to drive unacceptable
inhalation risk in indoor air; these low concentrations challenge sampling and state-
of-the-art analytical detection methods.
Second, the often severe spatial and temporal variability of air-phase VOC
concentrations within a building - compounded by potential sources of indoor air
bias - makes characterization of accurate and precise average conditions by 'direct'
sampling of indoor air difficult.
•	Accordingly, at any given site, conclusions or recommendations on indoor air risk and
characterization must be technically defensible and based on reasonable and appropriate
assumptions. To meet this standard for purposes of the Environmental Indicators, EPA
New England recommends:
indoor air characterization include an adequate site conceptual model (e.g. nature
and extent of groundwater contamination, geology and hydrology, exposure

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pathways, extent and nature of man-made subsurface preferential pathways),
direct sampling of indoor air by Summaฎ Cannister methods may be appropriately
supplemented - occasionally replaced - by a 'toolbox' of direct and/or 'indirect'
characterization methods (described below),
application of a tool is to be scientifically appropriate under the conditions
suggested by the site conceptual model, and
the results of the application of these tool(s) must tend to corroborate the site
conceptual model and/or one another in support of proposed indoor air conclusions
or recommendations.
• Sampling and analysis tools include, among others: direct indoor air sampling and/or
screening, soil vapor sampling/screening, passive diffusion sampling, surface flux
measurements, soil and/or groundwater sampling and indoor air modeling. For technical
information on:
direct indoor air sampling See the State of Massachusetts' Draft February 1, 2001
Indoor Air Sampling and Evaluation Guide, www, state, ma.us/dep/new.htm:
USEPA, Compendium of Methods for the Determination of Air Pollutants in
Indoor Air, EPA/600/4-90-010; Shigehisa Uchiyama and Shuji Hasegawa,
Investigation of a Long-Term Sampling Periodfor Monitoring Volatile Organic
Compounds in Ambient Air, Environ. Sci. Technol. 34: 4656-4661 (2000) (an
intriguing evaluation of a mass flow-controlled adsorption sampling system for
measuring long-term average VOC concentrations in ambient air).
•	soil vapor sampling See generally, USEPA, Soil Vapor Extraction Technology:
Reference Handbook, EPA/540/2-91/003, February 1991. As a general matter,
anticipated soil vapor concentrations should be calculated to, among other things,
gauge sampling depth, anticipate effects of non-steady state influences (e.g.,
atmospheric pumping, variations in surface cover form and permeability) and to
identify the best sampling and analytical technique(s). Whenever possible,
sampling depth should be at least as deep as building foundations. Three-
dimensional profiling is recommended.
passive diffusion sampling and related technologies See Environmental
Technology Verification Report, Soil Gas Sampling Technology, W.L. Gore &
Associates, Inc., GORE-SORBER Screening Survey, EPA/600/R-98/095;
Environmental Technology Verification Report, Soil Gas Sampling Technology,
EMFLUX Soil Gas System. EPA/600/R-98-096. Guidance for passive diffusion
sampling for dissolved-phase VOCs in groundwater wells has recently been
published in draft form: see USGS, Water-Resources Investigation Report, Parts 1
and 2: User's Guide for Polyethylene-based Passive Diffusion Bag Samplers to
Obtain Volatile Organic Compound Concentrations in Wells. Part 1 (USGS WRI
report 01-4060) is entitled, "Deployment, Recovery, Data Interpretation, and
Quality Control and Assurance." Part 2 (USGS WRI Report 01-4061) is entitled,
"Field Tests." This guidance is anticipated to be available soon at the following
web sites: www.itrcweb.org and www.frtr.gov.
•	surface flux measurements See USEPA, Procedures for Conducting Air Pathway
Analyses for Superfund Activities, Interim Final Documents: Volume 2 - Estimation
of Baseline Air Emissions at Superfund Sites, EPA-450/l-89-002a (NTIS PB90-

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270588), August 1990; USEPA, Measurement of Gaseous Emission Rates from
Land Surfaces Using an Emission Isolation Flux Chamber - User's Guide, EPA
600/8-86-008 (NTIS PB86-223161), February 1986; BartEklund, Practical
Guidance for Flux Chamber Measurements of Fugitive Volatile Organic Emission
Rates, J. Air Waste Manage. Assoc. 42:1583-1591 (Dec 1992).
• indoor air modeling See Paul C. Johnson, Robert A. Ettinger, Heuristic Model for
Predicting the Intrusion Rate of Contaminant Vapors into Buildings, Environ. Sci.
Technol. 25:1445-1452 (1991). The Johnson-Ettinger model is generally accepted
among technical and risk experts as the appropriate model to evaluate vapor
intrusion; it may be used in either abbreviated or more complex forms (as
conditions warrant) to substantiate in whole, or support in part, indoor air findings
and/or recommendations. See EPA's Superfund Risk Assessment webpage
entitled, Subsurface Vapor Intrusion into Buildings at
www.epa.gov/superfund/programs/risk/airmodel/johnson_ettinger.htm (series of
screening level spreadsheets for site-specific application of the Johnson-Ettinger
model (developed by Craig Mann for EPA)).
•	Human health risk may be substantiated by site-specific risk calculations or by
comparison to appropriate numerical criteria. Specific regulatory provisions, risk
assessment procedures or numerical criteria which have been promulgated or are
recommended by other Regions or States may help to guide an environmental indicator
determination. The States of Massachusetts, Connecticut, Michigan and Colorado have
been at the forefront of developing procedures and/or numerical criteria for indoor air.
See generally, Massachusetts Department of Environmental Protection, Background
Documentation for the Development of the MCP Numerical Standards (April 1994);
Connecticut Department of Environmental Protection, Regulations of Connecticut State
Agencies, 22a-133k-l et seq.; Michigan Department of Environmental Quality, Part 201:
Generic Groundwater and Soil Volatilization to Indoor Air Inhalation Criteria Technical
Support Document (hug. 31, 1998).
•	EPA's Indoor Air Workgroup is currently working on developing and consolidating
technical guidance and policy on indoor air. This policy may be updated as new
information becomes available.
•	OSHA PELs—To determine if indoor air is an exposure pathway with unacceptable risk to
human health under current industrial use (i.e., under current ownership which operates
the facility with full, actively maintained knowledge that releases from current and past
operations exist which may contribute to current indoor air concentrations) EPA New
England Region will use the lowest value available within Occupational Safety and
Health Administration (OSHA) regulations (i.e., Permissible Exposure Levels (PEL) and
guidance (i.e., Recommended Exposure Levels set by the National Institute for
Occupation Safety and Health and Threshold Limit Values set by the American
Conference of Governmental Industrial Hygenists)).
To account for the added response time which may be necessary to gain control of an

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environmental source of air contamination (e.g., solvent releases into shock adsorbent
flooring, or sub-floor soils) EPA-New England recommends cutting the OSHA standards
and guidance by a factor of 100, thus using 1% of the OSHA levels as the screening level
to determine achievement of environmental indicators.
•	Remediation of soils cannot be implemented as quickly as repairing a faulty blower or
fume hood and provides no recourse to definitively effective controls (such as controlling
an operational source by shutting down operations until new equipment can be installed).
EPA New England Region anticipates that timely actions triggered at these concentration
levels will prevent any exceedences of OSHA standards and guidance from changes in
indoor air quality. EPA New England Region expects that the use of OSHA standards
and guidance as interim standards will be accompanied by the observance of all OSHA
controls with respect to monitoring, training, employee awareness of hazards, etc.
•	Please note that EPA New England Region will not use OSHA standards and guidance as
a reference point for selecting media cleanup standards for contaminated soils or
groundwater. Long-term remediation must achieve standards reflective of the risk
assessment protocol followed by the EPA New England Region RCRA Corrective Action
Program and which will provide protection of human health and the environment under
current and any reasonably foreseeable future use of the facility.

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APPENDIX
GUIDANCE DOCUMENTS FOR RCRA CORRECTIVE ACTION
The following is an index of several guidance documents to follow when conducting RCRA
Corrective Action. The names of the documents in this appendix are grouped according to the
task for which they are designed to provide assistance. The documents on this list are generally
applicable to most RCRA Corrective Action facilities. However, there are numerous other
guidance documents available for specific technical or policy issues which are not listed below.
Such documents may be found through the EPA website at http://www.epa.gov.
Copies of the national EPA guidance documents listed below may be downloaded from EPA's
website at http://www.epa.gov/rcraonline or requested through the RCRA Hotline at (800) 424-
9346 or (703) 412-9810 or through the National Technical Information Service (NTIS) at
703/487-4650. Some of the EPA risk assessment guidance documents listed below are available
from EPA's website at http://www.epa.gov/ORD. EPA New England Region guidance
documents or non-EPA guidance documents may be requested from your EPA RCRA Facility
Manager. To be placed on the mailing list for EPA New England Region Risk Updates, contact
your RCRA Facility Manager.
GENERAL RCRA CORRECTIVE ACTION:
Corrective Action for Solid Waste Management Units (SWMUs) at Hazardous Waste
Management Facilities (Subpart S Proposed Rule), Federal Register. Volume 55, No. 145,
July 27, 1990, pp. 30798 - 30884. (Note this must be used in light of: Partial Withdrawal of
Rulemaking Proposal, Federal Register. Volume 64, No. 194, October 7, 1999, pp 54604-
54607.)
Corrective Action for Releases from Solid Waste Management Units at Hazardous Waste
Management Facilities (Advanced Notice of Proposed Rulemaking for Subpart S), Federal
Register. Volume 61, Number 85, May 1, 1996, pp. 19432 - 19464, available through
http://www.epa.gov/EPA-WASTE. (Note this must be used in light of: Partial Withdrawal
of Rulemaking Proposal, Federal Register. Volume 64, No. 194, October 7, 1999, pp 54604-
54607.)
U.S. Environmental Protection Agency, 1994, RCRA Corrective Action Plan. OSWER
Directive 9902.3-2A, EPA520-R-94-004, May 1994.
U.S. Environmental Protection Agency, 1999, Documentation of Environmental Indicator
Determination. Interim Final February 5, 1999.
FUTURE LAND USE:
U.S. Environmental Protection Agency, 1995, Land Use in the CERCLA Remedy Selection
Process. OSWER Publication 9355.7-04, May 25, 1995, PB95-963234.

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U.S. Environmental Protection Agency Region I, 1998, Future Land Use Policy for RCRA
Corrective Action Sites, memorandum dated June 29, 1998.
Institutional Controls: A Site Manager's Guide to Identifying. Evaluating and Selecting
Institutional Controls at Superfund and RCRA Corrective Action Cleanups. EPA 540-F-
00-005, OSWER 9355.0-74FS-P, dated September 2000.
PUBLIC INVOLVEMENT:
U.S. Environmental Protection Agency, 1996, RCRA Public Participation Manual.
EPA530-R-96-007, September 1996. available through
http://www.epa.gov/epaoswer/hazwaste/permit/pubpart/manual.htm
RCRA FACILITY INVESTIGATION:
U.S. Environmental Protection Agency, 1989, RCRA Interim Facility Investigation
Guidance. Interim Final: Volume I: Development of RFI Work Plan and General
Considerations for RCRA Facility Investigations: Volume II: Soil. Groundwater, and
Subsurface Gas Releases: Volume III: Air and Surface Water Releases: Volume IV: Case
Study Examples. OSWER Directive 95-02.00D, EPA 530/SW-89-031, May 1989.
U.S. Environmental Protection Agency, 1992, Characterizing Heterogeneous Wastes:
Methods and Recommendations. EPA/600/R-92/033, February 1992.
U.S. Environmental Protection Agency, 1997, Field Analytical and Site Characterization
Technologies. Summary of Applications, EPA542/R-97/001, November 1997.
U.S. Environmental Protection Agency, Test Methods for Evaluating Solid Waste.
Physical/Chemical Methods. EPA SW-846.
Groundwater Investigation:
U.S. Environmental Protection Agency, 1991, Dense Nonaqueous Phase Liquids—A
Workshop Summary, Ground Water Issue Paper. EPA/540/4-91-002.
U.S. Environmental Protection Agency, 1991, Handbook of Suggested Practices for the
Design and Installation of Groundwater Monitoring Wells. EPA/600/4-89/034, March,
1991.
U.S. Environmental Protection Agency, 1992, Dense Nonaqueous Phase Liquids, Ground
Water Issue Paper. EPA/600-R-92/030.
U.S. Environmental Protection Agency, 1992, Estimating the Potential for Occurrence of
DNAPL at Superfund Sites. Memorandum, OSWER Directive 9355.4-07.

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U.S. Environmental Protection Agency, 1992, Handbook of RCRA Ground-Water
Monitoring Constituents: Chemical and Physical Properties. EPA/530/R-92/022,
September 1992.
U.S. Environmental Protection Agency, 1992, RCRA Groundwater Monitoring Draft
Technical Guidance. EPA 530-R-93-001, PB93-139350, November 1992.
U.S. Environmental Protection Agency, 1996, Ground Water Issue: Low-Flow (Minimal
Drawdown) Ground-Water Sampling Procedures, Ground Water Issue Paper.
EPA/540/S-95/504, April 1996.
U.S. Environmental Protection Agency Region I, 1996, Low Stress (Low Flow') Purging
and Sampling Procedure for the Collection of Ground Water Samples from Monitoring
Wells. July 30, 1996.
Quality Assurance:
U.S. Environmental Protection Agency, 1987, OSWER Directive 9335.0-7B, Data
Quality Objectives for Remedial Response Activities. EPA/540/G-87/003 & 004, March
1987.
U.S. Environmental Protection Agency, 1998, EPA Requirements for Quality Assurance
Project Plans for Environmental Data Operations. EPA QA/R-5, External Review Draft
Final, October 1998 as implemented in EPA Region I by the:
Region I. EPA-New England Compendium of Quality Assurance Project Plan Guidance.
and Attachment A: Region I, EPA-New England Quality Assurance Project Plan Manual,
Draft, September 1998.
U.S. Environmental Protection Agency Region I, 1996, Data Validation Functional
Guidelines for Evaluating Environmental Analyses. December 1996.
RISK ASSESSMENT
Both Human Health and Ecological Risk Assessments:
U.S. Environmental Protection Agency Region I, 1995, Health and Environmental Risk
Assessment fHERA) Statement of Work. 'SOW.' for Risk Assessment. August 18, 1995.
U.S. Environmental Protection Agency Region I, Risk Updates (periodic EPA-Region I,
New England bulletins which provide current guidance).
Http://www.epa.gov/superfund/programs/risk

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http://www.epa.gov/NCEA
Human Health Risk Assessments:
U.S. Environmental Protection Agency, 1989, Air/Superfund National Technical
Guidance Study Series. Volumes I, II, III, and IV, EPA 450/1-89-001,002,003,004, July
1989.
U.S. Environmental Protection Agency Region IX Preliminary Remediation Goals at
http://www.epa.gov/region09/waste/sfund/prg/index.htm
U.S. Environmental Protection Agency, 1991, Role of the Baseline Risk Assessment in
Superfund Remedy Decisions. OSWER Directive 9355.0-30, April 22, 1991.
U.S. Environmental Protection Agency, 1991, Human Health Evaluation Manual.
Supplemental Guidance: "Standard Default Exposure Factors." OSWER Directive
9285.6-03, March 25, 1991.
U.S. Environmental Protection Agency, 1992, Calculating the Concentration Term:
Supplemental Guidance to RAGS. EPA Publication 9285.7-081, May 1992.
U.S. Environmental Protection Agency, 1992, Dermal Exposure: Principle and
Applications. EPA/600/8-91/01 IB, January 1992.
U.S. Environmental Protection Agency, 1992, Guidance for Data Useabilitv in Risk
Assessment. Part A. EPA Publication 9285.7-09A, April 1992, PB92-963356.
U.S. Environmental Protection Agency, 1992, Guidelines for Exposure Assessment.
57FR22888 - 57FR22938, May 29, 1992.
U.S. Environmental Protection Agency, 1993, Guidance Manual for the Integrated
Exposure Uptake Biokinetic Model for Lead in Children. OERR, Publication Number
9285. 7-15-1, PB93-963510.
U.S. Environmental Protection Agency, 1993, Integrated Exposure Uptake Biokinetic
Model riEUBKl Version 0.99d. OERR, Publication Number 9285.7-15-2; PB93-963511.
U.S. Environmental Protection Agency, 1995, New Policy on Evaluating Health Risks to
Children, Memorandum from Carol M. Browner, Administrator, and Fred Hanson,
Deputy Administrator, EPA, October 20, 1995.
U.S. Environmental Protection Agency, 1996, PCBs: Cancer Dose-Response Assessment
and Application to Environmental Mixtures. September 1996.

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U.S. Environmental Protection Agency, 1996, Recommendations of the Technical
Review Workgroup for Lead for an Interim Approach to Assessing Risks Associated with
Adult Exposures to Lead in Soil EPA Technical Review Workgroup for Lead, December,
1996.
U.S. Environmental Protection Agency, 1996, Soil Screening Guidance: Technical
Background Document. OSWER Directive 9355.4-17A, EPA 540/R-96/018, PB96-
963502
U.S. Environmental Protection Agency, 1996, Soil Screening Guidance: User's Guide.
OSWER Directive 9355.4-23, PB96-963505.
U.S. Environmental Protection Agency, 1997, Exposure Factors Handbook (Vols. I, II,
and III), EPA/600/P-95/002Fa, August 1997.
U.S. Environmental Protection Agency, Risk Assessment Guidance for Superfund.
Volume I: Human Health Evaluation Manual. (RAGS HHEM).
(Part A) interim final, EPA 540/1-89/002, December 1989.
Development of Risk-Based Preliminary Remediation Goals (Part B) EPA
Publication 9285.7-01B, December 1991, PB92963333.
Risk Evaluation of Remedial Alternatives (Part CI EPA Publication 9285.7-01C,
December 1991, PB92-963334.
Standardized Planning. Reporting, and Review of Superfund Risk Assessments
(Part D1 January 1998, PB9285.7-01D.
Guidelines for:
Carcinogen Risk Assessment (51 FR 33992, September 24, 1986);
Mutagenicity Risk Assessment (51 FR 34006, September 24, 1986);
The Health Risk Assessment of Chemical Mixtures (51 FR 34014, September 24,
1986); and
The Health Assessment of Suspect Developmental Toxicants (51 FR 34028,
September 24, 1986); and Exposure Assessment (57 FR 22887, 1992).
U.S. Environmental Protection Agency, Health Effects Assessment Summary Tables
(HEAST). Environmental Criteria and Assessment Office, Office of Health and
Environmental Assessment: Office of Research and Development, Cincinatti, OH (most

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current version).
U.S. Environmental Protection Agency, Integrated Risk Information System, (most
current version), http://www.epa.gov/iris.
Ecological Risk Assessments:
Calabrese, E.J. andL.A. Baldwin, 1993, Performing Ecological Risk Assessments.
Lewis Publishers, Chelsea, MI. 257 pp.
Code of Federal Regulations (CFR), Title 40, Chapter 1, Subchapter D, Part 131, Water
Quality Standards. As amended through December 22, 1992, FR 60910.
Jaagumagi, R., 1992, Development of the Ontario Provincial Sediment Quality
Guidelines for Arsenic. Cadmium. Chromium. Copper. Iron. Lead. Manganese. Mercury.
Nickel, and Zinc. Water Resources Branch. Ontario Ministry of the Environment.
Jaagumagi, R., 1992, Development of the Ontario Provincial Sediment Quality
Guidelines for PCBs and the Organochlorine Pesticides. Water Resources Branch.
Ontario Ministry of the Environment
Long, Edward R., Donald D. MacDonald, Sherri L. Smith and Fred D. Calder, 1995,
Incidence of Adverse Biological Efects Within Ranges Of Chemical Concentrations In
Marine andEstuarine Sediments. Environmental Management. 19:81-97.
Maughan, J. T., 1993, Ecological Assessment of Hazardous Waste Sites. VanNostrand
Reinhold. New York, New York. 352 pp.
Persaud, D., R. Jaagumagi and A. Hayton, 1992, (Revised 1993) Guidelines For The
Protection and Management Of Aquatic Sediment Quality In Ontario. Water Resources
Branch, Ontario Ministry of the Environment.
Rand, G.M. (editor), 1995, Fundamentals of Aquatic Toxicology: Effects. Environmental
Fate, and Risk Assessment. Second Edition. Taylor and Francis, Washington, DC. 1125
pp.
Suter, G.W., 1993, Ecological Risk Assessment. Lewis Publishers, Chelsea, MI. 538 pp.
U.S. Environmental Protection Agency, 1989. Risk Assessment Guidance for Superfund.
Volume II. Environmental Evaluation Manual. March 1989, (EPA/540/1-89/001).
U.S. Environmental Protection Agency, 1989, Ecological Assessment of Hazardous
Waste Sites. A Field and Laboratory Reference: Environmental Research Laboratory,
Corvallis, Oregon, EPA/600/3-89-013

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U.S. Environmental Protection Agency, 1992, Risk Assessment Forum, February 1992.
Framework for Ecological Risk Assessment (EPA/630/R-92/001).
U.S. Environmental Protection Agency, 1992-, EcoUpdate: Intermittent Bulletins.
supplemental guidance to RAGS, Vol. II, EPA Publication 9345.0-051, Volume 1,
Numbers 1, 2, 3, 4, and 5, 1991-1992; Volume 2, Numbers 1, 2, 3, and 4, 1994; Volume
3, Numbers 1 and 2, 1996.
U.S. Environmental Protection Agency, 1993, Wildlife Exposure Factors Handbook.
EPA/600/R-93/187a, December 1993.
U.S. Environmental Protection Agency, 1994, Ecological Risk Assessment Issue Papers.
Office of Research and Development, EPA/63 0/R-94/009
U.S. Environmental Protection Agency, 1998, Guidelines for Ecological Risk
Assessment. Office of Research and Development, Risk Assessment Forum,
Washington, D.C. EPA/630/R-95/002f. May 1998.
U.S. Environmental Protection Agency, 1997, Ecological Risk Assessment Guidance For
Superfund: Process for Designing and Conducting Ecological Risk Assessments. Interim
Final. Environmental Response Team, Edison New Jersey. June 5, 1997. (EPA540-R-
97-006).
ENVIRONMENTAL INDICATORS/ STABILIZATION
U.S. Environmental Protection Agency, Documentation of Environmental Indicator
Determination, Interim Final, February 5, 1999.
REMEDIAL TECHNOLOGIES
Information on remedial technologies is available on the following EPA website
addresses:
http ://www. epa.gov/ swertio 1
http://www.epa.gov/attic/index.html
MANAGEMENT OF REMEDIATION WASTE
Corrective Action Managment Units and Temporary Units; Corrective Action Provisions
Under Subtitle C; Final Rule, Federal Register. Volume 58, No. 29, February 16, 1993,
pp. 8658 - 8685.
U.S. Environmental Protection Agency, 1996, Memorandum from Shapiro, Luftig, and
Clifford to EPA Regions re: Use of AOC Concept During RCRA Cleanups. (SOC 1996-3
FB 11954) March 13, 1996.

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U.S. Environmental Protection Agency, 1998, Management of Remediation Waste Under
RCRA (EPA 530-F-98-026) October 1998, available at http://www.epa.gov/osw.
Hazardous Remediation Waste Management Requirements (HWIR-Media); Final Rule,
Federal Register. Volume 63, No. 229, February 16, 1993, pp. 65873-65947, also
available at http://www.epa.gov/osw.
POST-REMEDIATION SAMPLING
U.S. Environmental Protection Agency, 1989, Methods for Evaluating Attainment of
Cleanup Standards Volume 1: Soils and Solid Media (EPA 230/02-89-042) February
1989.

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