United States Environmental Protection Agency
Region 5
Waste, Pesticides, and Toxics Division
Risk Management Strategy for Corrective Action Projects
EPA Region 5 RCRA Program
MAY 2005
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NOTICE
The procedures described in this U.S. EPA Region 5 Risk Management Strategy for
Corrective Action Projects are provided as guidance and recommendations primarily
for Project Managers in the RCRA Corrective Action program. It is intended to apply to
RCRA corrective action investigations and remedial decisions on sites/facilities for
which Region 5 is the lead agency.
This Strategy does not create any new regulatory compliance requirements and does
not supersede any applicable Federal or state statutory or regulatory requirements. The
Strategy does not impose legally binding requirements on EPA, the states, or regulated
entities. Region 5 may decide that the Strategy is not applicable at a particular
site/facility or part of a site/facility due to specific circumstances. The Strategy should
be used in conjunction with formal corrective action agreements that apply at a
site/facility, such as a permit, unilateral order, consent order, voluntary agreement, etc.
The Strategy is based in part on several U.S. EPA technical guidance and policy
documents which Region 5 has incorporated into the Strategy. All decisions regarding
corrective action at a particular site/facility will be made based on the applicable statutes
and regulations.
Interested parties are free to raise questions about the appropriateness of any
recommendation or policy in the Strategy with respect to a particular site/facility. After
reviewing such questions, Region 5 will consider whether or not the recommendations
in the Strategy are appropriate to apply.
The Strategy may be revised and updated at any time to reflect the Region's experience
in implementing the Strategy or in response to questions and comments received from
the States, regulated entities, and the public.
CONTENTS
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Acronyms v
Chapter 1: Introduction 1
Section 1: Requirements and challenges of the RCRA Corrective Action program
Section 2: Reforms in the RCRA Corrective Action Program
Section 3: Decision-making Based on Risk Management
Section 4: When are risk management decisions made?
Chapter 2: What is the Purpose of the Region 5 RCRA Risk Management Strategy? 5
Section 1: What are the responsibilities of the RCRA Project Manager?
Section 2: Are there other participants who could contribute to risk management decisions?
Chapter 3: Starting down the road to Risk Management decisions - the Conceptual Site Model... 7
Section 1: Facility Profile
Section 2: Physical Profile
Section 3: Release Profile
Section 4: Land Use and Exposure Profile
Section 5: Ecological Profile
Section 6: Risk Management Profile
Chapter 4: Applying "Priority Factors" for Making Risk Management Decisions 11
Section 1: Phase 1 - Initiate Site Characterization and Risk-Based Ranking 11
1.1: Land Use Decisions
1.2: Groundwater Use and Groundwater Classification
1.3: Data Quality Objectives
1.4: Human Health Risk-Based Screening
1.5: What is Risk Screening?
1.6: Which environmental media, receptors, and land uses are appropriate to consider for
risk-based screening?
1.7: Are there land uses and receptors for which risk screening should not be applied?
1.8: What risk ranking categories should be used?
1.9: When should the risk-based screening be initiated?
1.10: How should the risk-based screening be carried out?
1.11: Ecological Risk-Based Screening
1.12: Which environmental media, receptors, and land uses are appropriate to consider for
ecological risk-based screening?
1.13: Are there land uses and receptors for which ecological risk screening should not be
applied?
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1.14: When should the ecological risk-based screening be initiated?
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Section 2: Phase 2 - Complete the Site Characterization and Risk Evaluation 25
2.1: Address the high risk release locations
2.2: Select and plan Interim Measures
2.3: Site-specific risk assessment
2.4: Ecological risk assessment
2.5: Risk Evaluation Report
Section 3: Phase 3 - Remedy Selection to Achieve Site-wide Risk Management Goals 32
3.1: Human Health Risk Goals
3.2: Ecological Risk Management Goals
3.3: Source Control
3.4: Removal / Reduction
3.5: Engineered Controls
3.6: Monitored Natural Attenuation of Chemical Contaminants
3.7: Institutional Controls
3.8: Risk Management Plan
Chapter 5: Relationship between the Risk Management Strategy and State RCRA
Corrective Action Authority 48
Attachment 1: Criteria for determining compliance with Toxic Substances Control
Act (TSCA) regulations at a RCRA site found to have PCB contamination 50
Attachment 2: Region 5 RCRA program policy on the use of occupational standards
for evaluating concentrations of chemical constituents in indoor air 54
Attachment 3: EPA's Expectations for Final Corrective Action Remedies 55
EXHIBIT 1: Performing risk-based screening of surface soil data 58
EXHIBIT 2: Performing risk-based screening of groundwater and surface water data 60
IV
ACRONYMS
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ANPR - Advanced Notice of Proposed Rulemaking
AOC - Area of Concern
BTSC - Brownfields Technology Support Center (EPA)
CMS - Corrective Measures Study
CSGWPP - Comprehensive State Ground Water Protection Program
CSM - Conceptual Site Mode
CWA- Clean Water Act
DAF - Dilution-Attenuation Factor
DERA- Detailed Ecological Risk Assessment
DQO - Data Quality Objective
El - Environmental Indicator
ESL - Ecological Screening Level
GPRA - Government Performance and Results Act
HI - Hazard Index
HQ - Hazard Quotient
1C - Institutional Control
IEUBK - Integrated Exposure Uptake Biokinetic Model
IM - Interim Measure
J&E - Johnson and Ettinger
MCL - Maximum Contaminant Level
MNA - Monitored Natural Attenuation
MOD - Memorandum of Understanding
NAPL - Non-Aqueous Phase Liquid
NCP - National Oil and Hazardous Substances Pollution Contingency Plan
NHANES - NATIONAL HEALTH AND NUTRITION EVALUATION SURVEY
ORD - Office of Research and Development (EPA)
OSHA - Occupational Safety and Health Administration
OSWER - Office of Solid Waste and Emergency Response (EPA)
PBT - Persistent and Bioaccumulative Toxic
PCB - Polychlorinated Biphenyl
PCOC - Potential Contaminant of Concern
PEL - Permissible Exposure Limit
PERA - Preliminary Ecological Risk Assessment
PM - Project Manager
PRG - Preliminary Remediation Goal
QAPP - Quality Assurance Project Plan
RCRA - Resource Conservation and Recovery Act
RFI - RCRA Facility Investigation
RP - Responsible Party
SERA- Screening Ecological Risk Assessment
SWMU - Solid Waste Management Unit
TEQ - Toxic Equivalence
TSCA - Toxic Substances Control Act
UCL - Upper Confidence Level
WPTD - Waste, Pesticides and Toxics Division
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CHAPTER 1: Introduction
Section 1: Requirements and challenges of the RCRA Corrective Action program
When the Resource Conservation and Recovery Act (RCRA) was enacted in 1976 and regulations went
into effect in 1980, thousands of industrial facilities that handle hazardous waste became subject to new
federal regulations. The RCRA regulatory structure with its emphasis on "cradle to grave" management
of waste has helped ensure that hazardous waste generated from ongoing industrial operations is
properly managed and does not contribute to a future generation of toxic waste sites. Important
regulations were put in place for the proper handling and disposal of hazardous waste and for imposing
permit compliance requirements on facilities that generate, store, treat, and dispose hazardous waste.
In addition to waste handling and permit requirements, the Hazardous and Solid Waste Amendments of
1984 gave EPA the authority to impose corrective action requirements for solid waste management units
(SWMUs) and other areas of concern (AOCs) at facilities where a hazardous waste treatment, storage or
disposal unit was operated after 1980. More than 5000 facilities were estimated to be subject to RCRA
corrective action authority. Many of these facilities had existing soil and groundwater contamination
resulting from historical waste management practices. The degree of investigation and corrective action
necessary to protect human health and the environment varies significantly across these facilities. Some
facilities were recognized as requiring no remediation or only minor action, while many were found to be
as complex and highly contaminated as any Superfund site.
Over the last decade, general consensus was reached among Congress, the EPA, state agencies, facility
owners, and concerned citizens that the pace and progress of RCRA remediation decisions must be
increased and streamlined. In reviewing the program, EPA and other stakeholders identified several
factors that were impeding timely and cost-effective remediation. In some instances, RCRA site
investigations and remedial decisions were perceived as being hampered by an emphasis on process
steps and a lack of clarity in remedial objectives. An additional complication is the actual or perceived
impediments to site remediation created by the application of certain RCRA requirements, such as the
land disposal restrictions, minimum technological requirements, and permit application and review.
Section 2: Reforms in the RCRA Corrective Action Program
In an effort to address the key impediments to timely site investigation and remediation, EPA announced
an initiative called the "RCRA Cleanup Reforms." The purpose of the reforms is to enhance RCRA
program flexibility and spur progress toward faster and more efficient site investigation and remedial
decisions. The key reforms are:
• Foster maximum use of program flexibility and practical approaches through training and outreach,
and by issuing new results-oriented site investigation and remedial guidance containing more clearly
defined objectives.
• Promote the guidance for program flexibility and streamlined remedial approaches that EPA described
in the "Advanced Notice of Proposed Rulemaking" (ANPR) on corrective action at RCRA regulated
facilities.
• Promote and implement Environmental Indicator (El) determinations at RCRA sites. EPA has
established two short-term El goals for the RCRA Corrective Action program. These goals were
developed in response to the Government Performance and Results Act (GPRA) and apply to RCRA
facilities that EPA and the states have identified as high priority sites. The purpose of short-term El
goals is to provide evidence that the current conditions at a RCRA site are not causing significant
human health risks. The goals require that by the end of 2005, EPA and the states will document that
95 percent of approximately 1700 RCRA facilities will have "current human exposures under control,"
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Risk Management Strategy for Corrective Action Projects - May 2005
and 70 percent of these facilities will have "migration of contaminated groundwater under control."
The long-term goal of the program is to achieve final remediation at all RCRA corrective action
facilities.
• Promote "results-based" approaches for RCRA corrective action. EPA will favor and accept results-
based approaches that emphasize outcomes and eliminate reliance on unnecessary process steps.
Results-based approaches should be accepted in order to meet the GPRA goals and to move facilities
toward the ultimate goal of achieving final remediation. Results-based approaches include setting
clearly understood cleanup standards, providing procedural flexibility in how goals are met, inviting
innovative technical approaches, and allowing facility owners to undertake cleanup action with
reduced agency oversight when appropriate. Under such approaches, owners focus on environmental
results and the most technologically efficient means of achieving them while still being held fully
accountable.
• Promote the RCRA Brownfields Initiative (1998). The goal of the Initiative is to encourage the reuse of
potential RCRA Brownfields so that the affected land better serves the needs of the community either
through more productive commercial or residential development or as greenspace /recreational
space. (A potential RCRA Brownfield is a RCRA facility or portion of a RCRA facility that is not
actively managed or not in full use, and where there is redevelopment potential. For most of these
sites, reuse or redevelopment has been slowed due to factors such as: real or perceived concerns
about actual or potential chemical contamination, legal liability for new property owners, and RCRA
cleanup requirements.)
Preparing Brownfield sites for productive reuse through corrective action requires the integration of
many elements - financial issues, community involvement, liability considerations, risk assessment.
The cleanup strategy must integrate the concept of risk management into the overall redevelopment
process. The risk assessment will be affected by the planned reuse of the property. Since cleanup
strategies will vary from site to site, the challenge is to clean up sites in accordance with
redevelopment goals in a way that benefits communities and local economies. Meeting this challenge
for land reuse is Agency policy as articulated in various guidance documents and memos.
EPA's Land Revitalization Initiative is sponsored by OSWER. Region 5 has a Land Revitalization
Team (including a Team Leader, a Superfund Brownfields coordinator, and a RCRA Brownfields
coordinator) which is available to assist with strategies for working with communities on the non-
technical issues, such as how to include local interests in redevelopment/reuse strategies. For
technical information, EPA-ORD maintains a Brownfields Technology Support Center (BTSC). The
BTSC can provide information about specific technologies or types of technologies for use during site
investigation and cleanup activities. Included are field-based measurement techniques, off-site
analytical techniques, and innovative or conventional techniques for cleaning up contaminated soil or
groundwater at a site. The BTSC can identify applicable technologies and provide brief analyses of
their potential advantages and limitations in light of site-specific features and needs.
Key references:
RCRA Cleanup Reforms: Faster, Focused, More Flexible Cleanups (EPA530-F-99-018; July 1999)
http://www.epa.gov/osw
RCRA Cleanup Reforms - Reforms II: Fostering Creative Solutions (EPA 530-F-01-001; Jan. 2001)
http://www.epa.gov/osw
Approaches and Tailored Oversight Guidance for Facilities Subject to Corrective Action Under Subtitle C
of the Resource Conservation and Recovery Act (EPA 530-R-03-012; Sept. 2003)
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Risk Management Strategy for Corrective Action Projects - May 2005
http://www.epa.gov/epaoswer/hazwaste/ca/resource/guidance/gen_ca/reslt-bse.pdf
Advance Notice of Proposed Rulemaking: Corrective Action for Releases from Solid Waste Management
Units at Hazardous Waste Management Facilities (Fed. Reg. 61:19432, May 1, 1996).
http://www.epa.gov/docs/fedrgstr/EPA-WASTE/1996/May/Day-01/pr-547.pdf
Partial Withdrawal of the May 1, 1996 Rulemaking Proposal. (Fed Reg.64, 54604, October 7, 1999).
http://www.epa.gov/fedrgstr/EPA-WASTE/1999/October/Day-07/f26070.htm
Government Performance and Results Act (http://www.epa.gov/ocfo/planning/gpra.htm)
Interim Final Guidance for RCRA Corrective Action Environmental Indicators
(Feb. 1996) http://www.epa.gov/epaoswer/correctiveaction/eis/ei guida.pdf
RCRA Brownfields Overview (http://www.epa.gov/swerosps/rcrabf/overview.htm)
Brownfields Technology Support Center (http://www.brownfieldstsc.org)
Section 3: Decision-making Based on Risk Management
In the previous section, EPA's ANPR for corrective action was mentioned as a major item under the
RCRA reforms initiative. After publishing the ANPR, the Agency later decided not to rely heavily on the
rulemaking process for corrective action, but designated the ANPR as "the primary corrective action
implementation guidance." In the ANPR, EPA outlined a few basic operating principles that it believed
should be implemented to accomplish flexible and results-based corrective action. The principles were
referred to as the "Program Management Philosophy" for implementing corrective action. The major
principles are:
• Corrective action decisions should be based on risks to human health and the environment.
Remedial decisions fora site are now recognized fundamentally as risk management
decisions. EPA, the states, and facility owners will be making decisions to eliminate risks, control
exposure, and reduce potential future risk. The risk management decisions will cover human health
risks and risks and threats to the environment. Risks to the environment will be addressed through
ecological risk assessment which can include analysis and protection of wildlife, natural habitats, and
environmental resources (e.g., watersheds, surface water, and sediments).
• Interim actions and stabilization to reduce or prevent chemical releases are also risk management
decisions. Finding, stabilizing, and controlling existing sources of chemical releases should be the
early focus of a site investigation project.
• The site investigations should focus on how to get meaningful results. The purpose of the program
should be to stabilize releases, cleanup releases, and reduce or eliminate risks in a timely manner.
The program implementers should focus on getting results rather than fulfilling standardized process
steps.
Section 4: When are risk management decisions made?
As a result of the implementation of the ANPR and the RCRA Cleanup Reforms, the major application
points for risk management decisions during the corrective action for a site are:
• El determinations - to meet the Region 5 RCRA program commitments under the GPRA; these
determinations formally apply only to the current site conditions and primarily for human health risks.
Ecological risk evaluation applies if contaminated groundwater is discharging to surface water.
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Decisions to perform interim actions or take stabilization measures - actions to reduce or prevent
significant chemical releases from a source of waste or to prevent significant potential chemical
migration from one environmental media to another. These decisions could be made at any time
during the site investigation process.
Final remedial decisions - the final decisions that apply to an entire site. These are the decisions that
apply to current conditions and also address reasonably foreseeable future conditions. These
decisions address remediation of both human health risk& ecological risk/ecological damage. They
are referred to as final remedial decisions even if implementation of the decisions occurs in multiple
phases.
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Risk Management Strategy for Corrective Action Projects - May 2005
CHAPTER 2: What is the Purpose of the Region 5 RCRA Risk Management Strategy?
EPA's national program goals and the emphasis on promoting program flexibility and results-based
approaches for conducting corrective action projects were outlined above. The concept that all important
site remedial decisions are risk management decisions were also introduced. Based on these ideas, the
Region 5 RCRA program decided to develop a single guidance that would be suitable as an approach for
making risk management decisions at any RCRA corrective action site. Consequently, the objectives of
this Strategy are:
*• To provide a unified guidance and a "coaching tool" that a Project Manager (PM) can follow to design
a site investigation and compile the critical site related information that will allow for timely and
transparent risk management decisions.
*• To assist a PM in collecting and organizing the essential information needed to recommend
appropriate risk management decisions.
*• To recommend a practical sequence or time-line of site investigation activities which will support
efficient risk management decisions;
*• To explain the fundamental risk management policies and preferences that the Region 5 RCRA
program will apply for making risk management decisions.
The primary application of the Strategy is for RCRA corrective action sites. However, it is anticipated that
parts of the Strategy could be useful for other personnel in the Waste, Pesticides and Toxics Division
(WPTD) who make decisions that fall in the category of risk management. This would include project
managers and staff in the Underground Storage Tank program and the Toxics Program.
It should be noted that this Strategy does not provide in-depth technical details for how to perform the site
investigation and data collection and does not eliminate the need to refer to and use the EPA technical
guidance that already exists.
Section 1: What are the responsibilities of the RCRA Project Manager?
For RCRA corrective action projects in Region 5, the site PM takes a lead role in oversight of a project by
reviewing plans and making recommendations to the RCRA Corrective Action Program Manager on
major site decisions, including how the site investigation should be conducted and what site-specific
interim and final remedial decisions should be made. The major PM responsibilities include:
• Defining the scope of the corrective action project needed for a specific site to fulfill the original
enforcement order, permit, or consent agreement;
• Setting up internal "briefing" meeting(s) with other EPA staff to introduce the project and start defining
project information needs; lining up technical support from other Region 5 staff as needed (e.g.,
analytical chemist/QA specialist; risk assessment specialists; hydrogeologist; public affairs specialist)
• Setting up meeting(s) with the facility owner/operator who is the Responsible Party (RP) for the site;
explaining EPA's needs and requirements for making site decisions; leading discussions with the RP
to define project information needs and the time line for proceeding (as a follow-up to the original
order or permit);
• Providing oversight on the RP's site investigation and the technical reports that document the
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progress of the investigation;
• Providing oversight on the RP's conduct of the required public participation activities for the site;
determining the level of public interest in the site and recommending additional voluntary public
participation activities by the RP;
• Responding to citizen questions about RCRA regulations and the site investigation;
• Filling out site El forms or reviewing El forms submitted by an RP.
• Presenting alternatives and recommendations on the following important site activities and decisions:
a) public participation activities that should be undertaken by EPA (e.g., fact sheets, information
meetings; health agency consultations); b) El decisions; c) Interim Measures decisions; and d) final
remedial decisions and the Statement of Basis for a site. The RCRA Corrective Action Program
Manager will evaluate the alternatives, the PM's recommendations and make site decisions, including
how the site investigation should be conducted, what site-specific interim measures are needed and
the basis for the final risk management determination.
• Providing oversight on the RP's implementation of the Interim Measures decisions and the final
remedial decisions for the site.
Section 2: Are there other participants who could contribute to risk management decisions?
EPA guidance and practice recommend that the PM and the Program Managers should accept or seek
input from a number of additional sources as part of the process of risk management decision making.
These sources could be regarded as participants in the risk management decision process but not as the
decision maker for the corrective action. The following groups or entities should be regarded as the most
appropriate participants:
• The RP - in particular, the "on-site" project manager who is the RP's representative; this individual
promotes the interests of the RP in the overall project; provides direct management of the RP's site
investigation; explains the RP's future land use plans and economic interests in the site; explains and
promotes the RP's favored options for remedial decisions at the site;
• The public - in particular citizens living in the vicinity of a site under investigation. Citizens can
influence a site investigation by: providing additional information on site operational history and
possible chemical release locations; providing additional information on local land uses, groundwater
well locations, and potential chemical exposure scenarios; expressing concern over the completeness
or limitations of the RP's investigation.
• Government agencies (state, local, other Federal agencies, other EPA programs) and non-
governmental organizations. These agencies and organizations may provide information that the PM
and RP should consider in planning and implementing the site corrective action. They may have
significant interest or information regarding: a) the current and future use(s) of the land and
groundwater at a specific RCRA site or the areas surrounding the site; b) the nature of releases or
environmental conditions of the site or adjacent sites that may have impacted a RCRA site; c)
regulatory requirements needed to implement remedies - including establishing, monitoring, and
enforcing institutional controls; d) the presence of threatened or endangered species or critical
habitats; and e) remedial options which could be perceived as having an influence that goes beyond
the site boundaries. The typical list of entities includes: the State environmental agencies or health
departments; the EPA Superfund program; the State and Federal fisheries and natural resource
agencies; the U.S. Army Corps of Engineers; local municipalities; regional planning authorities; and
environmental organizations.
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CHAPTER 3:
Starting down the road to Risk Management decisions -the Conceptual Site Model (CSM)
In the ANPR for corrective action, EPA stated that site investigations and remedy decisions are most
successful when based on a "conceptual site model." A CSM is a multi-dimensional picture of site
conditions that conveys what is known about the chemical contaminant sources, contaminant release and
transport mechanisms, chemical fate and transport pathways, chemical exposure pathways and
exposure scenarios; and ultimately, the quantitative estimation of health and ecological risks.
The CSM is based on information available at any time and will evolve as new information becomes
available. It should be used as a starting point for identifying known and potential contaminant source
locations, for deciding where the analytical sampling of media should be performed to test for
contaminant releases, and to make logical deductions on how and where contaminant releases could
migrate. The initial version of the CSM can often be drawn from the traditional RCRA Facility
Assessment and its supporting material. At the beginning stage, the CSM should be used to compile all
relevant site information and to begin identifying the scope of the subsequent site sampling and
characterization investigation. The CSM should be documented by focused written descriptions of site
conditions (e.g., adapted from the RCRA Facility Assessment) and supported by visual documentation
such as maps, diagrams, and data tables.
After the CSM is initiated, the PM and the RP should discuss the relevance and quantity of additional
information to be included as the site investigation proceeds. Six categories of information should be
included as the CSM is developed. It is not necessary for the PM and the RP to regard each
category as requiring a new formal written document. Rather, it is expected that the categories
and the recommended information in each category should serve as placeholders or "check lists"
to cover the information and analysis that the site investigation needs to accomplish.
The recommended categories are:
Section 1: Facility Profile
The facility profile should provide information on potential source areas and identify buildings or process
structures that could affect sampling decisions for the site investigation. The locations of facility
structures and their links to chemical handling processes are important in identifying contaminants of
potential concern that will need to be addressed in the Data Quality Objectives and the risk evaluation.
The location of property boundaries can be important for evaluating land use determinations.
The facility profile should describe all important existing man-made features on the site, including: facility
buildings; chemical process areas; solid waste management units (SWMUs); property boundaries; and
historical features that are no longer present but may have impacted historical releases (e.g., demolished
process buildings, storage tank locations; earth-filled trenches).
Section 2: Physical Profile
The physical profile should concentrate on the important environmental setting information that is
applicable even if detailed data on the chemical releases are not yet available. The physical profile
information will be integrated later with information from the release profile to describe the behavior of
contaminants in the environment. The initial development of the physical profile will begin with some
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preliminary understanding of the environmental setting. Data gaps can than be identified and used to
design future investigations.
The physical profile describes the factors that may affect releases, fate and transport, and receptors,
including:
*• topographical features, such as hills, gradients, surface vegetation or pavement
*• surface geology including soil types and parameters, outcrops, and faulting
*• subsurface geology including stratigraphy, continuity, and connectivity
*• hydrogeologic information identifying the water-bearing zones, hydrologic parameters, and
impermeable strata
*• soil boring and monitoring well logs and locations
*• surface water features such as drainage routes, surface water bodies, wetlands, and
watershed parameters and characteristics
Section 3: Release Profile
A Release Profile will be developed overtime as information is obtained. At the beginning of the CSM,
the release profile may consist only of the potential source locations. As the CSM undergoes
development, the profile should contain site-specific information on release locations and characteristics.
The contaminant migration and fate and transport aspects of the release profile should be integrated with
the geologic and hydrogeologic information developed for the physical profile.
The release profile should describe the nature of the contaminants in the environment, including the
following:
*• identification of potential source locations and source materials;
*• identification of contaminants of potential concern;
*• source locations where a release has been confirmed;
*• soil sampling and groundwater monitoring well locations;
*• delineation of the area of contamination;
*• analytical sampling data on the concentration of contaminants of concern in a release;
*• migration routes and mechanisms;
*• rationale for selecting fate and transport models and results of the modeling;
Section 4: Land Use and Exposure Profile
The PM and the RP should begin by evaluating the types of land use and determining beneficial
resources on and around the facility. In addition, information on potential receptors locations (such as
surface water bodies, water wells, and residences) should be incorporated. For example, the
identification of surface water bodies at locations in the assessment area indicates the potential for
exposure from drinking water, water recreation, and fishing consumption. Receptor information also can
be important in demonstrating potentially complete or incomplete exposure pathways for the risk
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evaluation.
In the risk evaluation, the land use information is reviewed to determine the applicable exposure
scenarios for the facility and surrounding off-site properties. The determination of appropriate exposure
scenarios is also addressed. After this review is completed, the applicable exposure scenarios should be
incorporated into the CSM. If on-site or off-site land use changes, the land use profile and CSM should
reflect those changes.
The land use and exposure profile consists of information used to identify and evaluate the applicable
exposure scenarios and receptor locations, including:
*• land use on-site at the facility and off-site in nearby adjacent properties, emphasizing specific
uses (industrial/production, non-production open land, single-family homes, wood lands, park
lands, agriculture, etc.)
*• beneficial resource determination (groundwater classification, natural resources, wetlands,
etc.)
*• resource use locations (water supply wells, surface water intakes, etc.)
*• significant off-site landmark types and receptor locations (schools, hospitals, daycare
centers)
*• applicable exposure scenarios (residential, industrial, recreational, farming, etc.)
*• applicable exposure pathways identifying the specific sources, release and migration
mechanisms, exposure media, exposure routes, and receptors
Section 5: Ecological Profile
The ecological profile consists of information concerning the physical relationship between the developed
and undeveloped portions of the site, the use and level of disturbance of the undeveloped property, and
the type of ecological receptors present in relation to completed exposure pathways. The information
captured in the ecological profile will be critical in completing the ecological risk-based screening and the
site-specific ecological evaluation.
The following information should be included in the ecological exposure profile (some applicable
information may already be available from other CSM profiles):
*• description of the undeveloped property zones on-site and adjacent to the site, including but
not limited to - sensitive environmental areas (federal/state parks and protected areas) habitat
types (wetland, grass land, forest, pond, stream, etc.), primary ecological uses, degree and
nature of historical disturbances, locations of drainage ditches, creeks, and landfill areas
*• description of site receptors in relation to habitat type, including but not limited to -
endangered or protected species, mammals, migratory and native birds, fish, etc.)
*• description of relationship of releases to potential habitat areas - suspected or known
contaminants of concern, media contaminated, sampling data summary, potential or likely
routes of migration or exposure of potential receptors
Section 6: Risk Management Profile
The risk management profile summarizes and illustrates the ultimate outcomes of the site investigation. It
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will summarize the relationship between the human health and ecological risk evaluations, the EPA risk
management goals, and the selected risk management decisions/remedies. During the development of
the preliminary CSM, this profile will serve as a placeholder. As the facility progresses through the site
investigation, the information contained in the risk management profile will be augmented and refined and
will ultimately explain the specific risk management decisions that were made for the site.
The risk management profile should include the following:
*• summary of the risk evaluations for human health and ecology
*• summary of the chemical release situations that require risk management actions and
remedies
*• summary of the selected remedies and how they accomplish the required risk management
The following references provide guidance and more detailed information that can be consulted for
developing a CSM, including useful data "fill-in" sheets and a case study that illustrates the development
of a CSM.
Key References:
Region 6 Corrective Action Strategy (Nov. 2000)
www.epa.gov/earth 1r6/6pd/rcra_c/pd-o/riskman.htm
So;7 Screening Guidance: User's Guide (U.S. EPA Publication 9355.4-23; April 1996)
http://www.epa.gov/superfund/resources/soil/index.htm#user
Soil Screening Guidance: Technical Background Document (U.S. EPA Publication EPA/540/R-95/128;
May 1996) http://www.epa.gov/superfund/resources/soil/toc.htm
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CHAPTER 4: Applying "Priority Factors" for Making Risk Management Decisions
Chapters described the EPA concept that a CSM should be developed to summarize all of the important
information concerning chemical releases, chemical migration and transport, risk evaluation to receptors,
and risk management remedies. However, the construction of a full CSM could appear to be daunting
and complicated task, and a plan for developing a CSM was not described.
The Region 5 RCRA program believes that the information needed to complete the CSM and for making
risk management decisions can be obtained by applying a reasonable set of "Priority Factors." The
Priority Factors represent the major information sources, evaluation exercises, and policy preferences
that should be applied to a site investigation. The results of applying these factors can be incorporated
directly into the CSM. In addition, the Priority Factors can be utilized by the PM and/or the RP in an
approximate sequence that will benefit accomplishing the site investigation and the risk management
decision-making for any site.
Some of the Priority Factors also contain the risk management policy preferences that the R5 RCRA
program will apply to accomplish certain risk management decisions for a site.
Section 1: Phase 1 - Initiate Site Characterization and Risk-Based Ranking
The Priority Factors designated as Phase 1 should be applied to accomplish the initial or preliminary site
investigation and to identify all of the high risk chemical release situations that need immediate or
expedited attention.
1.1: Land Use Decisions
Both the ANPR and Superfund program guidance have recognized current and future land use as
important early decision points that will affect the ultimate risk management decisions for a site. Land
use decisions are of fundamental importance because they affect the risk evaluation to be performed for
the site and the risk management decisions about the contaminant cleanup goals and the levels of
residual contaminants that can be left in place. Early in the site investigation, the PM should develop a
preliminary land use summary that could be subject to change after further discussion with the RP.
The basic technical information that is needed for making land use determinations was already
summarized above in Chapter 3 under the heading "Land Use and Exposure Profile." In addition to the
technical information needed for the CSM, the following factors about land use should be considered or
reviewed since they could affect the risk evaluation procedures and could entail professional judgment on
the part of the PM.
• The fundamental concept is that the Region 5 RCRA program will recognize that RCRA sites have
been historically industrial and that many sites will remain industrial. For many RCRA sites where the
prevailing evidence is that the current industrial use will be continued by the existing owner/operator,
the decision to accept the RP's claim that future land use will be industrial is relatively straightforward.
• An RP's assertion that land use will remain industrial will likely trigger the need for land use
institutional controls and/or land use covenants that will need to be imposed on the RP's property
through deed notices, State authorized deed restrictions, a Region 5 enforcement order/permit
condition or some combination of these mechanisms.
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• For many historically industrial sites, the future land use situation may change because of economic
conditions and/or property taxation. RPs may want to convert existing facilities into multiple land
parcels for sale to new owners, lease to new users, or donation to a municipality or non-profit
organization for recreational use or ecological habitat. EPA encourages these decisions which result
in redevelopment and revitalization of property as part of the RCRA Cleanup Reforms. In some
cases, the redevelopment of the property may be a driving force for the RP to conduct the site
investigation. For these situations, the claims and assertions about future land use should be carefully
reviewed.
• For many large industrial sites, a single future land use designation may not be warranted. For
example, parts of a facility not historically used for industrial operation (e.g., set back lands) may not
be logical to consider as only for future industrial use. PMs should raise questions about considering
alternate future uses such as residential, commercial, recreational, and ecological habitat. And RPs
should be encouraged to seek the widest range of future uses consistent with EPA's promotion of
redevelopment and revitalization. Therefore, the PM should collect and review a wide range of
information for the site - historical land uses, the RP's economic interest and stated plans for the site,
and local land use plans and trends.
Key Reference:
Land Use in the CERCLA Remedy Selection Process (OSWER Directive 9355.7-04, May 25, 1995)
http://www.epa.gov/swerffrr/documents/land_use_cercla_remedy.htm
1.2: Groundwater Use and Groundwater Classification
The fundamental Agency policy is to maintain and/or restore groundwaterto its highest beneficial uses
wherever practical, within a time frame that is reasonable given the particular circumstances at a RCRA
site. The understanding of groundwater uses and the potential for a groundwater use classification at a
site is another early decision point that can affect the ultimate risk management decisions for a site.
EPA's primary objective is to restore currently used and reasonably expected sources of drinking water,
as well as groundwater closely connected hydraulically to surface waters, whenever such restorations are
practicable and attainable. Determining current and reasonably expected uses of groundwater at a
facility is important for assessing the risks posed by groundwater contamination on-site and off-site,
determining appropriate remedial objectives, and setting appropriate cleanup levels when groundwater
restoration is an objective. Alternatively, a determination that groundwater is not a drinking water source
(currently or in the reasonably expected future) or that restoration is not practical will generally result in
groundwater remedial objectives which address other uses and exposures that could occur (e.g.,
agricultural uses, recharge to usable groundwater, groundwater-surface water interface transfer). EPA
recognizes that groundwater use designations can enhance flexibility for groundwater cleanups while still
protecting human health and the environment.
Groundwater use designation is the determination and identification of the reasonably expected current
and future uses of groundwater at a site and adjacent to a site. The groundwater use designation needs
to define whether the groundwater is a current or potential source of drinking water, or whether it has
value other than drinking water. The following activities are important to consider for establishing the
groundwater use designation for a site. Since they do not require the collection of extensive analytical
data on groundwater contamination or quality, they can be considered early in the site investigation.
• Determine if groundwater is a current or reasonably expected future source of drinking water at the
site based on the current and future land uses for the site; consult the land use decision information if
necessary; determine if a groundwater aquifer(s) capable of supporting a drinking water supply is
located beneath the site or in reasonable proximity to the site.
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• Determine if groundwater migration from the site could be expected to impact local groundwater
currently used as drinking water or reasonably expected to be used as drinking water; to verify local
groundwater use, consider the need to locate current groundwater well users through historical well
logs/records and through actual confirmatory location surveys and local interviews;
• To assist in making designations for off-site groundwater use, confer with the applicable State
environmental agency and/or natural resource agency; Determine if the state has placed a formal
groundwater use designation in the vicinity of the facility - such as a determination that groundwater is
within a designated non-drinking water aquifer; EPA will generally defer to a state groundwater use
designation when it is part of an EPA-endorsed Comprehensive State Groundwater Protection
Program (CSGWPP).
• In the absence of an EPA-endorsed CSGWPP, the PM should determine if the state has an alternate
designation for local groundwater which considers the same factors listed in the CSGWPP guidance
(EPA 1992). If EPA has the lead role in implementing corrective action and a State designation
system is not available or is not adequately protective based on the CSGWPP guidance, then PMs
should consider using EPA's classification. EPA's groundwater classification system for site-specific
groundwater use designations is found in "Guidelines for Groundwater Classification under the EPA
Ground-Water Protection Strategy" (EPA 1986). These guidelines describe three classes of
groundwater that represent resource values to society: Class I is groundwater that is an irreplaceable
source of drinking water and/or ecologically vital; Class II is groundwater currently used or potentially
usable as a source of drinking water; and Class III includes groundwater that is not a current or
potential source of drinking water.
• If a non-drinking water use designation is determined to be valid for the site groundwater, alternative
use designations for the groundwater should still be identified; at a facility-specific level, there may be
uses of groundwater or potential exposures to contaminants from groundwater that might not be
considered in a State-wide groundwater use designation. Alternative uses for groundwater on-site
could include product manufacturing (e.g., cooling water, cleaning water); alternative uses for
groundwater off-site could include crop irrigation and gardening.
Key References:
Handbook of Groundwater Protection and Cleanup Policies for RCRA Corrective Action (EPA/530/R-04-
030; April 2004)
http://www.epa.gov/epaoswer/hazwaste/ca/resource/guidance/gw/gwhandbk/gwhndbk.htm
The Role ofCSGWPPs in EPA Remediation Programs (OSWER Directive 9283.1-09; April 1997)
http://www.epa.gov/superfund/resources/csgwpp/roledesc.htm
Final Comprehensive State Groundwater Protection Program Guidance (EPA/1 OO/R-93/001; 1992)
http://www.epa.gov/correctiveaction/resource/guidance/gw/csgwpp.htm
Guidelines for Ground-Water Classification under the EPA Ground-Water Protection Strategy (EPA
1986). http://www.epa.gov/correctiveaction/resource/guidance/gw/gwclass.htm
1.3: Data Quality Objectives
One of the key objectives of the Release Profile of the CSM is the collection of appropriate and relevant
data on chemical releases that will be evaluated through risk-based screening and through site-specific
risk assessments.
Data Quality Objectives (DQOs) are qualitative and quantitative statements about the types of analytical
data that will need to be collected at the site, the types of decisions to be made with data, and the level of
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sensitivity that must be obtained to use the data (i.e., detection limits, reporting limits). DQOs should be
used to ensure that environmental data are scientifically valid, defensible, and of an appropriate level of
quality given the intended use of the data.
Site investigations can be expedited considerably when DQOs are carefully established during project
planning. For example, if the objective of an initial investigation is to define a geographic area of gross
contamination, a DQO for this investigation may include accepting a relatively high method detection limit
provided by a cost-effective field screening technology for analysis of samples. In contrast, if the
objective is to determine if chemical contamination is present in groundwater used as drinking water, the
DQO should specify a very low method detection limit.
In the Region 5 RCRA program, DQOs should be established in the Quality Assurance Project Plan
(QAPP) for the site investigation. The QAPP is a document for which Region 5 and the RP will both be
signatories, and it may be the only document in the site investigation for which EPA gives formal
signature approval before final risk management and remedial decisions are made for a site. The RCRA
program has issued a formal guidance for how an acceptable QAPP should be written (see reference
below).
The following is a summary of the fundamental needs to be established in the DQO/QAPP process so
that data obtained in the site investigation will be suitable for risk evaluation and risk management
decisions.
• Identify SWMUs and Areas of Concern (AOCs) on which the sampling effort will be focused. This
information is usually drawn from the Preliminary Site Assessment, the RFA, or other documents
assembled by the PM and the RP.
• For most site investigations, sample data will need to be collected for both human health and
ecological risk evaluation. The QAPP should recognize and explain differences in sample locations,
types of media, and sample depths needed to collect site data for both types of applications.
• Identify the chemical constituents to be sampled at each SWMU/AOC and in each environmental
medium (e.g., soil, groundwater, sediment, surface water) suspected to be of concern at the start of
the project. These chemicals are often referred to as the Potential Contaminants of Concern (PCOC)
since they will be chemicals which contribute to human health and ecological risk. The QAPP should
contain a rationale for how the PCOC list was derived based primarily on the knowledge of facility
operations and/or the documented history of chemical releases at the site. If knowledge of the facility
history is minimal or highly uncertain, the QAPP should show that an expanded list of PCOCs was
selected to cover the potential risk concerns.
• Provide DQO statements and/or Decision Rules (e.g., "if-then" statements) to explain how the
collected data will be used to make decisions about the significance of chemical releases and actions
to be taken if the releases are found to be significant. The applicable DQOs should address how the
data on chemical constituent concentrations would be used for risk-based screening.
• Identify the analytical reporting limits that must be achieved so that the data for PCOCs will be
sensitive enough to use for risk-based screening and site-specific risk assessments. For human
health risk evaluation, the Region 5 RCRA program recommends that the Region 9 Preliminary
Remediation Goals (PRGs) and the Maximum Contaminant Levels (MCLs) be used to establish the
appropriately sensitive reporting levels. For ecological evaluation, the Region 5 Ecological Screening
Levels should be employed to establish the appropriately sensitive reporting levels.
• Provide a plan for background sampling if site-specific SWMU/AOCs sample concentration data will
be compared to site-specific background sample concentration data. According to RCRA policy, only
data on naturally-occurring inorganics should be compared to site-specific background data.
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In addition to the fundamental needs described above, specific risk management and/or analytical
concerns exist for the following 3 constituents:
Lead - when lead releases are expected at a site based on historic industrial operations or based on
preliminary/historical analytical data, the DQOs for soil should always call for sampling in the shallow
surface soil (typically the upper 3 inches of surface soil). This is because exposure to shallow surface
soils is expected to be the predominant pathway for lead intake by children in residential land use and by
adults in industrial land use.
Polychlorinated Biphenyls (PCBs) - Almost any industrial site that was in operation prior to 1978 may
have used equipment that contained PCBs, usually in an oil, but possibly also in other forms. PCBs were
mainly used in the following equipment or materials:
*• electrical equipment, particularly transformers, capacitors, and voltage regulators;
*• hydraulic equipment, particularly any hydraulic system used in operations involving die casting,
forging, extruding, a foundry, and a furnace, or other operations involving high temperatures or fire
risks;
*• heat transfer systems; and investment casting waxes.
*• waste oils (i.e., waste oil drums, tanks, or storage areas) and foundry sands, generated or
involving the above uses.
If any of the above equipment or materials were used at a site, the site investigation should include the
possibility of releases or spills of PCBs, and the DQOs should include sampling for PCBs in waste
materials, soils, and sediments. If PCBs are actually detected at a site, see Attachment 1 to view the
criteria for determining if compliance with Toxic Substances Control Act (TSCA) regulations will be
required at the site. TSCA regulations can apply to the site investigation procedures, the waste
handling/disposal procedures, and the remedial cleanup goals for the site. In addition, it should be noted
that the Region 5 RCRA program will confer with the Region 5 TSCA program (Toxics Program Section)
to identify the TSCA requirements that apply at a RCRA site.
Polychlorinated Dibenzodioxins and Polychlorinated Dibenzofurans (Dioxins)
Dioxins would usually be constituents of concern only at sites that have specific current or historical
operations. These are likely to be sites where the following activities occurred: combustion of hazardous
and nonhazardous waste in incinerators and boilers; open burning of waste; wood treatment facilities
using chlorinated phenols; manufacturing of certain chlorinated pesticides (e.g., 2,4-D; 2,4,5-T); paper
and pulp mills. If dioxins are suspected as potential constituents of concern, EPA guidance calls for
application of analytical procedures that will allow for detection and quantitation of the full range of toxic
congeners needed to evaluate the potential risk from the mixture of congeners expected from locations
where dioxin releases might have occurred. The DQOs fordioxin should include sampling for dioxins in
waste materials, soils, and sediments.
Key References:
Regional Policy for Development of Quality Assurance Project Plans (QAPP; EPA-Region 5 Waste,
Pesticides and Toxics Division; May 1998) http://www.epa.gov/reg5rcra/ca/qapp.htm
Data Quality Objectives Process for Hazardous Waste Site Investigations (QA/G-4HW; January 2000)
http://www.epa.gov/quality/qa_docs.html
Guidance for the Data Quality Objectives Process (QA/G-4; August 2000)
http://www.epa.gov/quality/qa_docs.html
Preliminary Remediation Goals (U.S. EPA - Region 9; 2004)
http://www.epa.gov/region09/waste/sfund/prg/index.htm
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Region 5 RCRA Corrective Action: Ecological Screening Levels (EPA-Region 5 Waste, Pesticides and
Toxics Division) http://www.epa.gov/reg5rcra/ca/edql.htm
1.4: Human Health Risk-Based Screening
The RCRA program recognizes that important time savings and sometimes cost savings can be realized
by ranking chemical releases from a site according to their apparent level of risk. Then, additional effort
on site characterization can be focused on the locations and constituents that represent the most
significant potential health risks. This would include both current risks and future risks based on the
expected uses of the site. By converse, locations and constituents that exhibit very low or insignificant
risks can become candidates for elimination from further characterization.
When a suitable QAPP is developed and sensitive analytical sampling is performed at a site, it should be
possible to identify high risk release areas and their associated constituents by conducting risk-based
screening.
1.5: What is Risk Screening ?
Risk screening is an exercise in which measured site-specific concentrations of chemicals are compared
to pre-determined chemical concentrations which correspond to known levels of health risk. A pre-
determined chemical concentration is derived from exposure parameters and chemical toxicity factors
which are combined to "back-calculate" the chemical concentration which corresponds to a known risk
level. The exposure parameters are selected to represent a specific exposure scenario that is plausible
at a site (e.g., residential land use, industrial land use, drinking water consumption). The chemical
toxicity factor is derived from EPA's analysis of the dose-response characteristics of the chemical in an
experimental system or from epidemiological data in humans.
The primary use of risk-based screening levels is to identify the lower bound of the risk spectrum, namely,
chemical concentration levels below which EPA believes there is no concern for further action provided
that the appropriate exposure scenario is applied. In addition, the comparison of site concentrations to
screening levels can also be used to identify the upper end of the risk spectrum, namely, chemical
concentrations which EPA believes would require further study including remedial action. Consequently,
risk-based screening can be used as a tool to expedite the identification of contaminants and exposure
locations/areas of both low and high risk concern.
1.6: Which environmental media, receptors, and land uses are appropriate to consider for
risk- based screening ?
Surface Soil - As described in the So;7 Screening Guidance, surface soil screening evaluation should
reflect the actual nature of surface soil exposure expected at a site. Consequently, the Region 5 RCRA
program makes the following recommendations:
*• Industrial land use - the receptor is a full-time facility worker who contacts surface soil on every work
day at the location in question. The assumed exposure pathways are incidental soil ingestion,
inhalation of volatile chemicals and particulates, and dermal contact. The sampling plan and the depth
for surface soil screening should normally be limited to the top 6 inches of soil. (Note: A trespasser
on industrial property may also be screened under the full-time facility worker scenario only if the
trespasser is assumed to be exposed to contaminants in surface soils from the same SWMUs and
AOCs to which the worker has contact.)
*• Residential land use - the receptor is a full-time resident who contacts surface soil on a daily basis at
the location in question. The assumed exposure pathways are incidental soil ingestion, inhalation of
volatile chemicals and particulates, and dermal contact. The sampling plan and the depth for surface
soil screening should normally be limited to the top 3 inches of soil.
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Subsurface Soil
*• The assumed exposure pathway is migration or leaching of subsurface soil chemical constituents to
underlying groundwater. The exposure scenario is the consumption of groundwater as drinking water
by a resident receptor. Consequently, this screening process is commonly referred to as the
"Migration to Groundwater Pathway" or the "Protection of Groundwater Pathway." As described in the
So;7 Screening Guidance, chemical constituents that can be screened by this pathway are limited to
those expected to have a significant potential for migration in the soil column.
Groundwater
*• The receptor is a full-time resident who consumes groundwater as drinking water. For risk-based
screening, this exposure assumption is applied anywhere that screening is performed (i.e., at any
monitoring well location or any place within a groundwater plume).
Indoor Air
*• The assumed exposure pathway is the migration of volatile chemicals from underlying contaminated
groundwater and/or soil gas into homes and buildings. The migration process is usually referred to as
"vapor intrusion." As described in the OSWER guidance, the process is limited to chemical
constituents that have a significant capacity for upward migration through the soil column (see
reference below).
*• Industrial land use - the receptor is a full-time facility worker who is exposed to contaminants on every
work day by inhalation at an existing building or at a future building located above the groundwater/soil
gas contamination. (NOTE: For vapor intrusion into industrial buildings, the EPA has no applicable
risk-based screening levels; for Environmental Indicator determinations, EPA has made a policy
decision that OSHA indoor air concentration limits can be applied as screening levels for the vapor
intrusion pathway. For a more detailed explanation for how the Region 5 RCRA program will
recognize the use of OSHA compliance limits, see Attachment 2).
*• Residential land use - the receptor is a full-time resident who is exposed to contaminants on a daily
basis by inhalation at an existing residence (or a residential use location) above the contaminated
groundwater/soil gas.
Sediment
*• The assumed exposure pathway is that a worker or resident has occasional (non-daily) contact with
surface sediments. The screening level assumption is that the daily surface soil direct contact
scenario for residential land use (described above) can be used as a suitable surrogate for direct
contact with surface sediments (i.e., incidental ingestion, dermal contact, and vapor/particle
inhalation).
Key References:
Soil Screening Guidance: User's Guide (U.S. EPA Publication 9355.4-23; April 1996)
http://www.epa.gov/superfund/resources/soil/index.htm#userDra/? Guidance for Evaluating the Vapor
Intrusion to Indoor Air Pathway from Groundwater and Soils (Subsurface Vapor Intrusion Guidance)
(OSWER ; November 2002) http://www.epa.gov/epaoswer/hazwaste/ca/eis/vapor.htm
1.7: Are there land uses and receptors for which risk screening should not be applied ?
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Based on historical experience with site investigations and risk assessments, several potential exposure
pathways and exposure scenarios have been identified which the EPA believes are not suitable for
applying risk-based screening. Most of these situations involve cases where standard conservative
exposure factors cannot be assigned or the exposure scenarios are too complicated for the purpose of
back-calculating a suitable screening level. They include the following situations:
*• Agricultural land use where food consumption pathways are actually occurring or are reasonably
possible on contaminated land;
*• Food consumption pathways from recreational use (e.g., fishing and hunting), especially where
indirect exposure to persistent and bioaccumulative toxics could occur through contaminated
sediments, soil, and plants (e.g., harvesting fish from a contaminated water body; harvesting game
animals that have contact with contaminated soil or sediments);
*• Potential "trespasser" exposure to contaminants on industrial property by activities other than surface
soil contact at known SWMUs or AOCs. Such activities would include: contact with on-site
contaminated sediments and surface water; consumption of or contact with contaminated
groundwater; harvesting fish from a contaminated water body; harvesting game animals that have
contact with contaminated soil or sediments;
*• Most "recreational" land use situations because they cannot obviously be accounted for by using
default industrial or residential land use exposure parameters as a surrogate;
*• Future soil excavation/construction situations; these could vary widely in time duration and exposure
frequency and include contact with soil and groundwater.
*• Groundwater concentrations that are estimated using a groundwater transport model; this is because
the modeled concentration is not an actual measurement of contaminant levels.
All of these situations need to be addressed in a site-specific risk assessment where site- specific
exposure factors and parameters are assigned for each scenario.
Key Reference:
Risk Assessment Guidance for Superfund: Volume I - Human Health Evaluation Manual; Part A
(EPA/540/1-89/002; Dec. 1989) http://www.epa.gov/superfund/programs/risk/ragsa/index.htm
1.8: What risk ranking categories should be used ?
In order to characterize health risks, the EPA separates potential risks into those from cancer-causing
chemicals and those from toxic chemicals not known to induce cancer. The risk from toxic chemicals is
normally referred to as a "hazard."
EPA treats cancer induction as a process which has no threshold dose, meaning that some level of
health risk is caused at any dose level. Therefore, cancer risk for a specific chemical is estimated as a
probability derived from:
Cancer Risk = (Intake Dose) x (Cancer Potency)
Cancer risk is expressed as a probability such as 3E-05 (i.e., 3 x 10"5; or "3 chances per 100,000
individuals"). As a policy, EPA generally regards cancer risks at or below 1E-06 (1 in a million) to be
levels that do not require further concern (also called a "de minimus" risk level).
EPA treats the induction of toxicity as a process with a threshold dose, meaning that a specific dose
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would need to be reached before actual adverse toxic effects would be expected. EPA assigns
chemicals a Reference Dose or Reference Concentration below which no adverse health effects would
be expected even on long-term exposure. Therefore, a Hazard Quotient (HQ) for a specific chemical is a
quantity derived from the direct comparison of the intake dose to the Reference Dose:
Hazard Quotient = (Intake Dose) •*• (Reference Dose)
As a policy, EPA generally regards Hazard Quotients at or below 1.0 to be levels that do not require
further concern.
In addition, for the purpose of obtaining a screening level estimate of cancer risk and hazard from
exposure to multiple chemicals by the same individual, EPA estimates cumulative cancer risk and
cumulative hazard quotient (called a "Hazard Index") as the sums of the individual cancer risks and
individual quotients, respectively.
Consequently, for evaluating chemical releases in a site investigation, the categorization of risk
significance should be based on the following rationale:
*• Chemical constituent levels considered to be of "No Further Concern";
Cancer Risk - All individual constituents at concentrations below a cancer risk level of 1E-06 and
cumulative cancer risk not exceeding 1E-06; l
Hazard Index - All individual constituents at a concentration below an HQ of 1.0 and cumulative
Hazard Index for multiple constituents also below 1.0; 2
Response action - no additional sampling or risk evaluation should be necessary when the
sampling was conducted in accordance with the Quality Assurance Plan. The location and
constituents of the sampling may be proposed fora No Further Action determination.
*• Chemical constituent levels that may need further evaluation.
Cancer Risk - One or more individual constituents at a concentration between a cancer risk level
of 1 E-06 to 1E-04 and cumulative cancer risk level between 1 E-06 and 1E-04;
For the purpose of risk screening, the chemical constituent concentrations corresponding to a cancer risk
of 1E-06 will be the Preliminary Remediation Goal (PRG) concentrations for the cancer endpoint developed in the
EPA Region 9 PRG Tables. See Section 1.10 for additional information.
2
For the purpose of risk screening, the chemical constituent concentrations corresponding to a Hazard
Quotient of 1.0 will be the Preliminary Remediation Goal (PRG) concentrations for the non-cancer endpoint developed
in the EPA Region 9 PRG Tables. See Section 1.10 for additional information.
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Hazard Index - One or more individual constituents at a concentration above an HQ of 1.0 with a
cumulative Hazard Index for multiple constituents not exceeding 2;
Response action - require further evaluation through additional sampling for constituent(s) that
exceed an HQ of 1.0; the release location may be associated with a "hot spot" of chemical
contamination; the PM may decide that the release location is not fully characterized and may
need additional sampling in horizontal or vertical directions;
*• Chemical constituent levels that are high risk
Cancer Risk - One or more individual constituents at a concentration above a cancer risk level of
1E-04 or a cumulative cancer risk level above 1E-04;
Hazard Index - One or more individual constituents at a concentration above an HQ of 2.0 or a
cumulative Hazard Index above 4.0
Response action - elevate the location for expedited further evaluation and/or direct remedial
response:
The PM should conclude that the extent of release from the location is not fully characterized
and needs additional sampling in horizontal or vertical directions to more fully characterize the
nature and extent of contamination;
The release location may be associated with a "hot spot" of chemical contamination;
The release location is a candidate for causing significant constituent migration to other
media; the location should be regarded as: a candidate location for source control measures; a
candidate for Interim Measures; a situation which would prevent positive El determinations;
1.9: When should the risk-based screening be initiated ?
Risk screening should usually begin at the completion of the first round or Phase I of the sampling plan
spelled out in the QAPP and other project work plans. Screening may be initiated as data become
available at each release location understudy (SWMU or AOC).
Soil: Based on information found in the Soil Screening Guidance and other Agency guidance, the
Region 5 RCRA program is recommending the following procedures to accomplish the sampling needs
for risk-based screening:
Surface soil
*• A minimum of 8 surface soil sample results that meet QA requirements are needed to begin
risk screening of areas not larger than 0.5 acre under residential or industrial land use;
SWMUs and AOCs suspected of having release areas much larger than a 0.5 acre should be
subdivided into 0.5 acre parcels for which a minimum of 8 samples should be obtained. An
area of 0.5 acre should be regarded as the generic unit area/lot size for risk-based screening
unless reliable site-specific information indicates that a different lot size is appropriate to apply
at a specific site (e.g., existing local residential lot sizes are significantly above or below 0.5
acre).3
These recommendations are based on information from the EPA So;7 Screening Guidance. The sample
size of 8 is a necessary minimum number of random discrete (non-composited) samples needed to conduct a valid
direct comparison of each sample's constituent concentrations to risk-based screening concentrations. This is the
sample size corresponding to only 5% probability that the actual mean constituent concentrations of the samples will
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*• The above recommendation for a minimum of 8 surface soil samples per unit area is a generic
starting point for application to the risk screening exercise. This frequency represents a
balance between the need to reduce uncertainty in risk management decisions (by collecting
additional data) with the objective of early identification and action at high priority areas. The
acceptable sample density could be affected by site-specific factors. For example, unit-
specific characteristics including the variability of waste(s) managed, how chemicals were
managed, and any physical alterations to the unit that would affect contaminant distribution
could dictate a higher, or lower, sampling frequency. Units for which preliminary or historical
information indicates that contamination is relatively homogeneous may require less sampling
than units with potentially highly variable or highly uncertain chemical distributions in soil. An
RP may present rationale for the PM's consideration for an alternate sampling frequency if
supported by site-specific conditions.
*• Because of the relatively small sample sizes normally encountered in risk screening of
multiple SWMUs and AOCs, the maximum detected concentration of each constituent should
be used for the comparison to the screening level concentration during the risk-based ranking
exercise for Phase 1 of the site investigation. It is recommended that statistical analysis of the
data should be deferred to Phase 2 of the site investigation after a larger number of sample
results become available or after the necessary data is obtained to answer concerns about
the extent of contamination. (See Section 2)
Subsurface soil
*• A minimum of 3 soil borings should be obtained from the area of highest known or suspected
contaminant impact within a SWMU or AOC. In each boring, soil samples from appropriate
depth intervals (e.g., 2 feet) should be collected and analyzed until the maximum depth to be
sampled is reached (e.g., depth to water table; depth to bedrock).
*• In each soil boring, the maximum and mean concentration of each constituent within the soil
segments should be found by reviewing the data;
Groundwater: Because of the higher potential for migration of contaminants in groundwater and the
difficulty in linking groundwater contamination with potential source locations, chemical constituent
concentration data from each groundwater well should be compared to the screening level concentration.
Data from multiple wells should not be combined to derive a mean concentration unless a clear rationale
can be offered.
Key Reference:
Soil Screening Guidance: User's Guide (U.S. EPA Publication 9355.4-23; April 1996)
http://www.epa.gov/superfund/resources/soil/index.htm#user
not exceed 2x the risk-based screening concentrations. An area of 0.5 acre was recommended as the default
suburban residential lot size.
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1.10: How should the risk-based screening be carried out ?
Surface Soil
A procedure for performing the risk-based screening of surface soil data is outlined in Exhibit 1. The
procedure utilizes the EPA Region 9 PRG values as risk-based screening concentrations.
For each constituent, the procedure will determine if the measured site concentration exceeds: a 1E-06
risk level, a 1E-04 risk level, and/or an HQ of 1.0.
In addition, the use of the procedure will allow for calculation of a cumulative screening level cancer risk
and a cumulative screening level hazard index for the multiple constituents present at a given location
(i.e.,.SWMUorAOC).
Subsurface soil
A set of generic or default screening levels for the soil-to-groundwater migration pathway can be found in
Appendix A of the So;7 Screening Guidance: Technical Background Document
(http://www.epa.gov/superfund/resources/soil/toc.htm). Table A-1 of Appendix A has a list of
constituents for which EPA determined that adequate physical/chemical data on migration potential was
available to develop a conservative screening level for the soil-to-groundwater migration pathway.
To conduct the screening procedure, locate the maximum subsurface soil concentration for each
detected chemical constituent in each soil boring from the available data for a given SWMU or AOC. If
the chemical constituent is listed in Table A-1, compare the maximum concentration from each soil boring
to the value listed under the column labeled "Generic Migration to Groundwater- 20 DAF". (Note: 20
DAF refers to a Dilution Attenuation Factor of 20. This means that contaminants migrating in soil
leachate are expected to be diluted by a factor of 20 when entering groundwater. EPA determined that
this was a reasonable and conservative dilution factor to apply for a screening level evaluation).
Groundwater and Surface Water
A procedure for performing the risk-based screening of groundwater/surface water data is outlined in
Exhibit 2. The procedure utilizes the EPA Region 9 PRG values and the EPA Maximum Contaminant
Levels (MCLs) as risk-based screening concentrations.
For each constituent, the procedure will determine if the site concentration exceeds: the published MCL
value, a 1E-06 risk level, a 1 E-04 risk level, or an HQ of 1.0.
In addition, the use of the procedure will allow for calculation of a cumulative screening level cancer risk
and a cumulative screening level hazard index for the multiple constituents present at a given
groundwater or surface water location.
It should be noted that the use of surface water as drinking water is the only surface water exposure
pathway that can be evaluated through risk-based screening. It is appropriate to apply MCL values for
risk-based screening of surface water used as drinking water. Other human uses of surface water (e.g.,
consumption offish, recreational use) cannot be addressed through risk-based screening. They need to
be addressed through site-specific risk assessment (Section 2.3).
Indoor Air
• Current Industrial Land Use:
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As explained in Section 1.6, the EPA does not have risk-based screening levels for indoor air in the
industrial use environment. For on-site industrial buildings determined to be subject to OSHA
compliance, Region 5 will recognize the OSHA-Permissible Exposure Limits (PELs) as acceptable indoor
air screening level concentrations for El determinations. The OSHA-PEL values can be downloaded from
the following web site:
The following should be regarded as additional needs and requirements for applying indoor air screening
using OSHA-PEL values:
*• Application of OSHA-PEL values for screening indoor air concentrations for on-site buildings is an
option to be exercised by the RP; the RCRA program may request the RP to provide evidence that the
on-site building(s) is regulated under OSHA for the contaminants of concern.
*• In order to apply OSHA-PEL values, the RP will need to run the Johnson and Ettinger (J&E) Model as
described in current EPA guidance. The J&E Model allows indoor air concentrations to be estimated
starting from chemical constituent concentration data for on-site groundwater or soil gas. The RP
must provide suitable documentation to show that it can make appropriate use of the J&E Model in a
manner that fits the specific site application including the use of appropriate building characteristics.
• Future Industrial Land Use and Residential Land Use:
The EPA guidance for evaluating vapor intrusion to indoor air is found in the document "DRAFT
GUIDANCE FOR EVALUATING THE VAPOR INTRUSION TO INDOOR AIR PATHWAY FROM
GROUNDWATER AND SOILS." (http://www.epa.qov/correctiveaction/eis/vapor/complete.pdf). This is a
guidance which provides a step-wise protocol for determining if vapor intrusion has the potential to be a
"complete" exposure pathway at a site. If application of the protocol shows that vapor intrusion cannot be
a complete pathway, then it may be eliminated from further concern.
The guidance provides risk-based screening levels for evaluating whether migration of constituents from
contaminated groundwater could cause unacceptable long-term indoor air concentrations (Tables 1 - 3;
http://www.epa.gov/epaoswer/hazwaste/ca/eis/vapor.htm). Consequently, the screening levels actually
apply to groundwater concentrations. For each chemical, screening levels are provided for 3 risk levels
(1E-06, 1E-05, and 1E-04) or for a hazard quotient of 1.0 (whichever is lower). Consequently, a user can
determine where a specific chemical fits within the risk ranking categories described in Section 1.8. The
risk screening model uses several conservative assumptions for estimating the migration of chemicals
from groundwater to indoor air. Because of the uncertainties inherent in this modeling, it is not
recommended that the screening levels should be used to estimate cumulative cancer risk levels or
hazard index levels at the present time.
Key References:
Preliminary Remediation Goals (U.S. EPA - Region 9; 2004)
http://www.epa.gov/region09/waste/sfund/prg/index.htm
So;7 Screening Guidance: Technical Background Document; Appendix A (U.S. EPA Publication
EPA/540/R-95/128; May 1996) http://www.epa.gov/superfund/resources/soil/toc.htm
Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils
(Subsurface Vapor Intrusion Guidance; Tables 1-3) (OSWER; November 2002)
http://www.epa.gov/epaoswer/hazwaste/ca/eis/vapor.htm
Safety and Health Topics: Permissible Exposure Limits (PELs) (U.S. Department of Labor; Occupational
Safety & Health Administration; 2003) http://www.osha.gov/SLTC/pel/
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Johnson and Ettinger (1991) Model for Subsurface Vapor Intrusion into Buildings (U.S. EPA; Superfund
Risk Assessment) http://www.epa.gov/superfund/programs/risk/airmodel/johnson_ettinger.htm
Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils
(Subsurface Vapor Intrusion Guidance ) (APPENDIX G: CONSIDERATIONS FOR THE USE OF THE
JOHNSON AND ETTINGER VAPOR INTRUSION MODEL)
(OSWER; November 2002) http://www.epa.gov/epaoswer/hazwaste/ca/eis/vapor.htm
1.11: Ecological Risk-Based Screening
As with human health risk, the RCRA program recognizes that important time savings and sometimes
cost savings can be realized by ranking chemical releases from a site according to their apparent level of
risk. Then, additional effort on site characterization can be focused on the locations and constituents that
represent the most significant potential ecological risks - both current risks and future risks based on the
expected uses of the site. By converse, locations and constituents that exhibit very low or insignificant
risks can become candidates for elimination from further characterization.
When a suitable QAPP and sensitive analytical sampling are performed at a site, it should be possible to
identify high risk release areas and their associated constituents by conducting ecological risk-based
screening.
Ecological risks should initially be evaluated through a screening ecological risk assessment (SERA)
process. A SERA is ideally conducted early in the RCRA site investigation schedule. This process begins
with the identification of goals, such as the environmental values to be protected, and the ecological
endpoints to be measured. Endpoints should define both the valued ecological entity (e.g., specific
species, resource, habitat type) at the site and a characteristic of the entity to protect (e.g., reproductive
success, survival, areal extent). A SERA most often consists of a desktop effort which compares
measured concentrations in environmental media against conservative ecological screening values. If
the comparison to screening level concentrations identifies potential risks, a more detailed study is
conducted. The detailed study would focus only on those specific stressors (e.g. chemicals) and species
identified in the SERA as presenting a risk concern. In some cases, further analysis of risk is necessary
later in the site investigation process. Alternatively, a site-specific assessment may be included in the
Corrective Measures Study or during later stages when final remedial goals are developed. (The site-
specific ecological risk assessment process is described in more detail in Section 2.4)
1.12: Which environmental media, receptors, and land uses are appropriate to consider for
ecological risk-based screening ?
Surface Soil - The EPA's national guidance on ecological soil screening should be followed (Guidance for
Developing Ecological Soil Screening Levels; 2003). This guidance published acceptable soil screening
levels for 9 constituents frequently encountered during hazardous waste site investigations (Aluminum,
Antimony, Barium, Beryllium, Cadmium, Cobalt, Iron, Lead, and Dieldrin). Several additional constituents
will be added to the above guidance in the future and the selected screening levels will become nationally
applicable levels. For constituents not on the above list, the Region 5 RCRA program's Ecological
Screening Levels should be applied. The actual depth for appropriate soil sampling and screening will be
distinct for each site based on the likely receptor species and the naturally occurring soil horizons. The
general expectation is that samples for surface soil screening should not exceed a depth of 2 feet below
ground surface.
Subsurface Soil - The EPA guidance is the same as above for surface soil, except that the appropriate
depth for sampling will depend on site-specific information on the likely receptor species.
Surface Water - The level of protection and the appropriate screening levels need to follow established
beneficial uses as addressed in EPA's Water Quality Criteria (2002). In addition, individual Region 5
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state water quality standards should also be considered as applicable screening levels.
Sediment - the objective is to protect species in aquatic communities with a particular focus on organisms
associated directly with sediments. Consequently, the chemical contaminants of major concern in
sediment will be persistent and bioaccumulative toxics (PBTs). Where the sediment PBTs could be part
of a food web, an evaluation needs to be made for terrestrial species that consume aquatic life. A Region
5 ecologist should be consulted to determine if appropriate chemical-specific screening levels are
available for application to sediments at a specific site.
Ajr - A level of protection has not been established, but some direction is available in EPA guidance (see
references below). Screening levels for a few chemicals in air can be found in the Region 5 Ecological
Screening Levels tables.
1.13: Are there land uses and receptors for which ecological risk screening should not be
applied ?
Based on EPA guidelines, ecological risk concerns and risk screening should apply only to wild plants
and wild animals. Consequently, ecological risk concerns should not be applied to agricultural crops,
domestic pets, and animals raised as livestock. Risk screening should also not be applied to artificially
maintained landscapes that are recognized as being constructed solely for human uses (e.g., recreational
fields, ballparks). An exception arises if the artificial landscape creates an attraction for wildlife.
1.14: When should the ecological risk-based screening be initiated ?
Risk screening should usually begin at the completion of the first round or Phase I of the sampling plan
spelled out in the QAPP and other project work plans. Screening may be initiated as data become
available at each release location understudy (SWMU or AOC).
No required or specific sampling needs for ecological risk-based screening can be identified other than
those available in the EPA ecological risk assessment guidance documents (see references below). For
example, a specific default exposure unit area (e.g., 0.5 acres) for soil sampling cannot be recommended
because the exposure area for a wildlife species depends on the particular "home range" that the species
needs for food consumption and protective cover.
Key references:
Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological
Risk Assessments - Interim Final (EPA540-R-97-006; OSWER 9285.7-25; June 1997)
http://www.epa.gov/superfund/programs/risk/ecorisk/ecorisk.htm
Guidelines for Ecological Risk Assessment (Final; Risk Assessment Forum; EPA/630/R-95/002F; April
1998) http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=12460
Guidance for Developing Ecological Soil Screening Levels (Eco-SSLs) (OSWER Directive 9285.7-55;
Nov. 2003) http://www.epa.gov/superfund/programs/risk/ecorisk/ecossl.htm
FACT SHEET: ECOLOGICAL RISK ASSESSMENT IN THE RCRA PROGRAM (EPA-Region 5 Waste,
Pesticides and Toxics Division; Jan. 2000) http://www.epa.gov/reg5rcra/ca/guidance.htm
Region 5 RCRA Corrective Action: Ecological Screening Levels (EPA-Region 5 Waste, Pesticides and
Toxics Division) http://www.epa.gov/reg5rcra/ca/edql.htm
Section 2: Phase 2 - Complete the Site Characterization and Risk Evaluation
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The Priority Factors designated as Phase 2 should be applied to address site contaminant releases that
need a rapid response, and to complete the contaminant characterization and risk evaluation for the
entire site.
2.1: Address the High Risk Release Locations
By this point in the investigation, after the Phase 1 priority factors have been applied, the release
locations of highest concern should be identified. The high risk release locations identified by the risk-
based screening (Section 1.10) should be elevated for direct and/or expedited remedial responses. The
following are decisions and actions that should be applied to address the high risk release locations (i.e.,
SWMUs and AOCs).
For soil:
*• The concentration levels in the release are a verified problem, but the location likely is not fully
characterized; additional sampling is needed in horizontal and/or vertical directions to more fully
characterize the nature and extent of contamination;
*• analytical results from additional constituent sampling should be compared to human health risk-
based screening levels; continue the sampling effort until new concentration data for all constituents
fall below the high risk screening level.
*• original sample locations with high constituent concentrations may be associated with one or more
"hot spots" of contamination; consider sampling in horizontal and/or vertical directions around the
known hot spots until subsequent sample concentrations are determined to fall below the high risk
screening level.
*• evaluate whether the original source of release (e.g., landfill, lagoon, holding pond, tank) could be a
continuing release point for contaminants to soil; If yes - source control will be needed to eliminate the
source or to place a release barrier around the source (e.g., excavation, capping, capture trench);
*• the possibility that the release location could cause significant migration to other media should be
considered; consider soil-to-groundwater migration and soil runoff/erosion to surface water as prime
migration problems; new or additional groundwater monitoring should be considered at and
downgradient of the release location;
*• the location should be considered as: a candidate location for source control measures; a candidate
for Interim Measures; a situation which would prevent positive El determinations;
For Groundwater:
*• Additional monitoring is needed in horizontal or vertical directions to more fully characterize the nature
and extent of contamination; analytical results of additional sampling should be compared to human
health risk-based screening levels; continue sampling in horizontal and/or vertical directions until
concentrations for all constituents fall below the "high risk" screening level.
*• Need to question whether groundwater contaminant migration is "under control" at the location of
concern; Determine if contaminated groundwater could be located in a "perched zone" or in an upper
aquifer with no significant potential for migration.
*• Additional monitoring may be needed to track migration of contaminated groundwater and to
determine if contaminated groundwater is moving in a plume; consultation with hydrogeologist and
more study of groundwater flow characteristics may be needed for the location.
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*• The migration outcomes of most concern are: migration to a drinking water aquifer; migration of
groundwater off-site to locations not under control of the RP; migration of groundwaterto a surface
water body (i.e., groundwater-to-surface water interface).
*• If significant evidence for contaminant migration under control cannot be obtained in a reasonable
time, then the groundwater plume should become a candidate for Source Control in the remedy
selection process or could become a candidate for Interim Measures (see below).
*• If contaminant concentrations in groundwater indicate that vapor intrusion cannot be eliminated as a
potential complete exposure pathway by the screening procedures recommended in the EPA
guidance (Section 1.10), then additional work to address the pathway will be required. The additional
work could include site-specific vapor migration modeling, soil gas sampling, sub-slab sampling,
indoor air sampling, or a combination of these approaches. The recommendations in the EPA
guidance should be used as a starting point for planning additional work.
2.2: Select and Plan Interim Measures
Interim Measures (IMs) are actions and responses needed for situations of such high concern for risk
management/risk reduction that they need to be addressed before the final remedy decisions for the site
are selected and announced. IMs are actions that go above and beyond additional sampling of
constituents. Some of the candidate situations are described above. They fall under the following
general categories:
• The presence of contamination or the physical state of contamination threaten actual or potential
contamination of drinking water supplies or sensitive ecosystems;
• A hazardous contamination situation exists that is a potential source for release or is a threat to health
or the environment, and EPA perceives that a long time will be needed to develop and implement a
permanent final remedy;
• The presence of hazardous waste and/or hazardous constituents in unstable containers or stored in
unreliable containment that poses a threat of release; significant risks of fire, explosion or sudden
release from hazardous wastes or hazardous constituents stored in unstable or unreliable containers;
• Groundwater is currently contaminated at significant concentrations levels near the boundaries of a
site such that off-site migration is imminent; off-site groundwater is already contaminated by
constituents that originated from on-site groundwater sources.
• Groundwater is currently contaminated at significant concentration levels and suitable near-term
actions could be taken to bring the migration under control;
• A contaminant source continues to be a significant release point for contaminants to soil; and/or a soil
contaminant location continues to be a significant release point for migration of contaminants to
groundwater;
• The presence of Non-Aqueous Phase Liquids (NAPLs) or "free product" contamination; NAPLs are
identifiable contaminant sources which should be candidates for recovery/remediation;
The following are brief examples of actions that could be taken as part of IM decisions:
*• installation of a pump-and-treat system to directly reduce contaminant levels in groundwater;
*• installation of a soil vapor extraction system to collect and treat volatile contaminants in soil gas;
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*• construction of cut-off walls as containment structures designed to prevent the migration of
groundwater from or into a source area. By preventing the migration of groundwater, cut-off walls may
minimize or prevent impacts from contaminants in groundwater. Common types of cut-off walls
include slurry trenches, sheet piling barriers, and grouted barriers.
*• construction of hydraulic containment barriers usually consisting of trenches, sumps, drains, and wells
designed to reverse localized groundwater flow gradients in such a manner as to reduce or prevent
the migration of contaminated groundwater. By preventing groundwater migration, hydraulic
containment barriers may minimize or prevent impacts from contaminants in groundwater.
*• clay caps and synthetic caps designed as protective covers to prevent the infiltration of precipitation
and surface water into a waste or contaminated media. The prevention of precipitation infiltration can
reduce leachate generation, the migration of contaminants in the subsurface soil and to groundwater,
and contaminant transport via erosion and surface water. Caps can also reduce vapor emissions from
waste and contaminated media, and prevent direct contact with waste or contaminated soil.
An additional consideration is that the RCRA program preference is that the outcome of IM actions should
be essentially equivalent to what would be achieved if the action were taken after "final remedy" selection.
As stated in the ANPR, "Generally, interim actions should be compatible with, or a component of, the final
remedy." In other words, the RCRA preference is that the technical or engineering part of an IM action
would not need to be re-visited in the final remedy selection. Ideally, the only part of an IM to be
addressed in the final remedy selection should be administrative requirements (e.g., future land use
restriction or land use covenant).
Key References:
Advance Notice of Proposed Rulemaking: Corrective Action for Releases from Solid Waste Management
Units at Hazardous Waste Management Facilities (Fed. Reg. 61: 19432, May 1, 1996).
http://www.epa.gov/docs/fedrgstr/EPA-WASTE/1996/May/Day-01/pr-547.pdf
RCRA Corrective Action Plan (Final); (OSWER Directive 9902.3-2A; May
1994)http://www.epa.gov/correctiveaction/resource/guidance/gen_ca/rcracap.pdf
2.3: Site-specific risk assessment
In previous Sections, the evaluation and ranking of health risks at a site were based on essentially
standardized or default procedures that could be used for risk-based screening and risk ranking. At
many sites, additional evaluation of health risk will need to be performed for situations or for exposure
scenarios that do not lend themselves to the application of standard or default assumptions. Several of
the situations requiring a site-specific risk evaluation were described in Section 1.7: "Are there land uses
and receptors for which risk screening should not be applied ?" (The PM should review Section 1.7 to
determine if any of the exposure scenarios described there apply to the site under investigation.)
An additional situation for which site-specific risk evaluation is often proposed is for a SWMU/AOC that is
perceived as having an original risk ranking that represents a significant overestimate of the actual risk.
The concept is that the application of additional site-specific risk evaluation could lead to a decision that
the SWMU/AOC should be moved to a lower risk category. The information needed to justify the
investment of additional time and resources for these situations would usually be submitted by the RP
and would entail one or both of the following:
*• A significant amount of analytical sampling data is available (or will become available) so that
statistical analysis can be used to generate alternative exposure point concentrations for chemical
constituents that will be lower than those employed for the original risk-based screening exercise (i.e.,
the Phase 1 risk screening). The EPA guidance on Exposure Point Concentrations should be
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consulted for performing data analysis tests to determine if a statistically derived mean value can be
used (e.g., the 95% UCL of the mean; see reference below). A PM should normally consult a Region
5 statistician before embarking on a statistical analysis or reviewing a proposal from an RP on using
statistical analysis.
*• Reliable and current site-specific information is available which shows that one or more of the
exposure factors or exposure parameters employed in the risk-based screening is a significant
overestimate of the actual situation at the site.
Consideration of Background in Risk Assessment
A site-specific risk assessment is conducted to characterize the current and potential threats to human
health posed by hazardous substances and chemical constituents at a site. EPA's Risk Assessment
Guidance for Superfund (RAGS; 1989) provides general guidance for selecting chemicals of concern and
considering background concentrations. In RAGS, EPA cautioned that eliminating chemical constituents
from risk evaluation based on background (because chemical concentrations are below background
levels or are attributable to background sources) could result in the loss of important risk information for
potentially exposed persons, even though the cleanup decision may or may not eliminate the source of
risk caused by the background levels.
In light of more recent EPA guidance for risk-based screening (EPA, 1996) and risk characterization (EPA
1995), the current EPA policy recommends a baseline risk assessment approach that retains constituents
that exceed risk-based screening concentrations (EPA 2002). This approach calls for addressing site-
specific background issues at the end of the risk assessment, in the Risk Characterization step.
Specifically, the chemical constituents with high background concentrations should be discussed in the
risk characterization, and if data are available, the contribution of the background concentration levels to
the site-related concentration levels should be distinguished. Chemical constituents that have both
release-related and background-related sources should be included in the risk assessment. When
concentrations of naturally-occurring substances (e.g., metals; inorganics) at a site exceed risk-based
screening levels, that information should be discussed qualitatively in the risk characterization. To
summarize:
*• The constituents retained in the quantitative risk assessment should include those with concentrations
that exceed risk-based screening levels.
*• The Risk Characterization should include a discussion of elevated background concentrations of
chemical constituents and their contribution to site risks.
This general approach is preferred in order to:
*• Encourage national consistency in this area;
*• Present a more thorough picture of risks associated with hazardous chemical constituents at a site;
*• Prevent the inadvertent omission of potentially release-related hazardous chemical constituents from
the risk assessment.
This approach is consistent with the Policy for Risk Characterization which calls for fully and clearly
characterizing risks (EPA, 1995). Risks identified during the baseline risk assessment should be clearly
presented and communicated for risk managers and for the public.
Key References:
Risk Assessment Guidance for Superfund: Volume I - Human Health Evaluation Manual; Part A
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(EPA/540/1-89/002; Dec. 1989) http://www.epa.gov/superfund/programs/risk/ragsa/index.htm
So;7 Screening Guidance: User's Guide (U.S. EPA Publication 9355.4-23; April 1996)
http://www.epa.gov/superfund/resources/soil/index.htm#user
Guidance for Risk Characterization (Science Policy Council; Feb. 1995)
http://epa.gov/osa/spc/htm/rcguide.htm
Risk Characterization Handbook (Science Policy Council; Dec. 2000)
http://epa.gov/osa/spc/htm/2riskchr.htm
CALCULATING UPPER CONFIDENCE LIMITS FOR EXPOSURE POINT CONCENTRATIONS AT
HAZARDOUS WASTE SITES (OSWER Directive 9285.6-10; December 2002)
http://www.epa.gov/superfund/programs/risk/tooltrad.htm
Role of Background in the CERCLA Cleanup Program (OSWER Directive 9285.6-07P; April 26,
2002)http://www.epa.gov/superfund/programs/risk/bkgpol ianOI .pdf
2.4: Ecological risk assessment
Corrective action remedies selected under RCRA must be protective for both the environment and human
health. Therefore, some form of ecological assessment will be necessary at all RCRA sites. This would
involve application of the ecological risk-based screening exercise described earlier (Section 1.12) as
well as a more formal site-specific ecological risk assessment.
EPA guidance defines ecological risk assessment as a "process that evaluates the likelihood that
adverse ecological effects are occurring or may occur as a result of exposure to one or more stressors."
Environmental stressors include any physical, chemical or biological entity that can induce responses
such as sublethal chronic effects, death of organisms, or loss of ecosystem functions.
An ecological risk assessment evaluates the potential adverse effects that chemical contamination has on
the plants and animals that make up ecosystems. The risk assessment estimates the likelihood that
adverse ecological effects (e.g. mortality, diminished growth, reproductive failure) will occur as a result of
releases of hazardous wastes at a site. The risk assessment process provides a way to develop and
analyze scientific information, assumptions, and uncertainties so that they are relevant to environmental
decisions.
When conducted at an industrial facility, the ecological risk assessment process can be used to identify
and characterize current and potential threats to the environment from a hazardous substance release, to
prioritize data collection activities, to identify vulnerable and valued ecological resources, to evaluate the
ecological impacts of alternative remediation strategies, and to establish clean-up levels protective of the
natural resources at risk.
The following are examples of why ecological risk assessment is important and has different needs from
a human health risk assessment:
*• Ecological Screening Levels (ESLs) are often derived from adverse health or population effects on the
animal and plant species most sensitive to the effects of a given chemical constituent. Many sites will
have constituent levels that exceed these sensitive ESLs. Based on readily obtainable local/regional
survey data and site-specific information, it may be possible to conclude that a highly sensitive
species is not present at the site and is not likely to frequent the site in the future. Alternative species
could be proposed as the focus of the ecological evaluation.
*• The locations on a site that are important for evaluating ecological species and eco-habitats are often
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different than the locations used to evaluate human health risk. The environmental media most
important for ecological evaluation are usually also different from those that dominate human health
risk, with eco-risk tending to be dominated by contaminant levels in surface water, sediment, and soil
rather than groundwater. Consequently, the site locations for sampling environmental media to
evaluate ecological risk will likely differ from those needed to evaluate human health risk.
*• In certain situations, especially where non-residential land use is applicable, remedial and cleanup
goals for ecological receptors may be more stringent (i.e., lower) than those needed for human health
protection. Therefore, ecological exposure pathways could be the driving force for remedial decisions
at major geographic areas of a RCRA site.
*• The presence of sensitive species and sensitive environments that may require special protection or
special consideration needs to be evaluated. Examples could include the presence of threatened and
endangered species or habitats and locations recognized as having a special ecological concern (e.g.,
proximity to Great Lakes habitats or designated nature preserves). (Additional examples are found in
Exhibit 1-1 of the ecological guidance forSuperfund; see reference below). Completion of an
evaluation for sensitive species and habitats will demonstrate compliance with the National
Environmental Policy Act of 1969 (NEPA) and the Endangered Species Act (ESA).
The Region 5 RCRA policy for conducting ecological risk assessment is outlined in the guidance Region
5: Ecological Risk Assessment Guidance for RCRA Corrective Action. This guidance describes what an
ecological risk assessment should cover and what approaches should be taken to streamline the
ecological risk assessment effort by applying a "tiered" approach that is consistent with EPA's national
guidance.
Ecological risk assessment can range from simple to complex and qualitative to quantitative depending
upon the site under investigation and the tier of the assessment itself. Region 5 recommends that the
ecological risk assessment effort should be partitioned into three tiers of effort. Each successive tier
requires more detailed and quantitative data collection, analysis, and evaluation than the preceding tier,
in order to determine the degree of risk. These three tiers are referred to as the screening ecological risk
assessment (SERA), preliminary ecological risk assessment (PERA), and detailed ecological risk
assessment (DERA).
Ecological risk assessment is an iterative process where at the culmination of each tier, a decision is
made on whether to conduct more work at the current tier, to progress to the next tier, or to terminate the
process. As the ecological risk assessment progresses from one tier to another, the assessment
becomes more quantitative, the base of information increases, the precision increases, and the allocation
of resources increases.
Key References:
Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological
Risk Assessments - Interim Final (EPA540-R-97-006; OSWER 9285.7-25; June 1997)
http://www.epa.gov/superfund/programs/risk/ecorisk/ecorisk.htm
Region 5: Ecological Risk Assessment Guidance for RCRA Corrective Action (Interim Draft; U.S. EPA-
Region 5; Waste Management Division; Office of RCRA; October 1994)
Region 5 RCRA Corrective Action: Ecological Screening Levels (EPA-Region 5 Waste, Pesticides and
Toxics Division) http://www.epa.gov/reg5rcra/ca/edql.htm
2.5: Risk Evaluation Report
At this point in the site investigationjhe nature and extent of releases from the facility have been
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characterized and the PM should have available the following information and analysis: a) the
identification of the High Risk Release Locations; b) the plans and/or decisions about source control
measures and Interim Measures; c) a site-specific human health risk assessment, if needed; and d) a
site-specific ecological risk assessment.
The RP should now generate a Risk Evaluation Report. The Report should draw from information that
likely is already available in other existing documents (e.g., site investigation reports; human health and
ecological risk assessments; IM Work Plans), and may be included as an attachment to these reports. It
does not need to provide a new technical evaluation of the data. At a minimum, the Report should
contain the following information:
• The results from the Risk-Based screening exercises on each SWMU/AOC or sampling location; a
summary of which SWMUs/AOCs were recommended for: "no further action"; recommended for
further sampling and study; recommended for further sampling and source control or IMs;
recommended for evaluation in the site-specific risk assessment. For projects being conducted under
traditional orders - this information would likely be provided in the Phase I RFI Report. For
Streamlined Orders - this information would be included in the Investigation Report. For Voluntary
Agreements - this information would be provided in the Final Corrective Measures Proposal. Facilities
conducting corrective actions under Voluntary Agreements may wish to submit the investigation
results in phases prior to submission of the Final Corrective Measures Proposal to keep EPA informed
of interim measures activities.
• The results from conducting site-specific human health risk assessment. The summary should include
a description of human exposure scenarios that were evaluated, the relationship between the
exposure scenario at specific SWMUs/AOCs, and the quantitative cancer risk and hazard index
estimates. For projects being conducted under traditional orders - this information would likely be
provided in the Phase II RFI Report. For Streamlined Orders - this information would be included in
the Investigation Report. For Voluntary Agreements - this information would be provided in the Final
Corrective Measures Proposal.
• A summary of the information to needed to support the CA 725 El decision of "Current Human
Exposures Under Control." The RP should consider attaching the completed draft CA 725 forms. For
projects being conducted under traditional orders, this information would likely be provided in the
Phase I and Phase II RFI Reports. For Streamlined Orders and Voluntary Agreements, this
information would be included in the Environmental Indicator Report.
• A summary of the information needed to support the CA 750 El decision of "Migration of
Contaminated Groundwater Under Control." The RP should consider attaching the completed draft
CA 750 forms. For projects being conducted under traditional orders - this information would likely be
provided in the Phase I and Phase II RFI Reports. For Streamlined Orders and Voluntary Agreements
- this information would be included in the Environmental Indicator Report.
• A summary of the results from conducting the site-specific ecological risk assessment. The summary
should include a description of the major results from each Tier of the assessment and their
relationship to specific SWMUs, AOCs, and sampling locations; for projects being conducted under
traditional orders - this information would likely be provided in the Phase II RFI Reports. For
Streamlined Orders - this information would generally be included in the Investigation Report. For
Voluntary Agreements - this information would generally be included in the Final Corrective Measures
Proposal.
Section 3: Phase 3 - Remedy Selection to Achieve Site-wide Risk Management Goals
After a PM decides that the site characterization is completed, the evaluation of the complete risk
management options for the site can begin. This has historically been referred to as the "Remedy
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Selection Process."
The Remedy Selection Process can be defined as the combination of residual risk goals, source controls,
technical/engineering remediation goals and institutional controls that the PM determines will achieve
long-range risk management for the entire site.
The Priority Factors designated as Phase 3 should be applied to put in place the remedies to accomplish
risk management goals for the site.
EPA has issued a number of criteria and guidance documents for evaluating remedial alternatives. For
example, the National Contingency Plan (NCR) outlines nine criteria that should used for evaluating
remedial alternatives to ensure that important considerations are factored into the selection. The 1996
ANPR also lists criteria which are very similar to those presented in the NCP. EPA also has issued other
guidance documents that clarify or expand on the remedy selection framework presented in the NCP and
the ANPR.
For the RCRA program, Region 5 has compiled the recommended criteria into a formal list titled:
"Expectations for Final Corrective Action Remedies" (Attachment 3). This list is divided into the
Fundamental Expectations, Remedy Selection Criteria, and Balancing Criteria that are recommended for
evaluating remedial alternatives. PMs and other stakeholders can review this list at any time to
understand EPA's fundamental approach for remedy selection. This list was reviewed to select specific
priority factors that should cover the major risk management decisions a PM would encounter as part of
selecting remedies for a site.
3.1: Human Health Risk Goals
The EPA has established preferences for the level of health risk for chemical constituents left in place
(residual risk) in a medium that can be the source of current and/or future exposure.
Cancer Risk
Under current EPA policy as interpreted from the NCP and Superfund guidance, the Agency has
established a policy that residual cancer risks in an exposure medium (soil, groundwater, and surface
water) can be considered acceptable when the cumulative (multi-chemical) cancer risk is within the range
of 1E-06 to 1E-04. The Agency has stated its preference that remedial decisions will be targeted to the
lower end of this risk range. Ultimately, the specific EPA program responsible for making decisions will
decide where within the acceptable range the residual cancer risk goal will be established for a given site
or a specific location within a site.
To further clarify the understanding of residual risk goals for sites under its jurisdiction, the Region 5
RCRA program establishes the following policy preferences:
A) When setting the risk-based remediation goals for individual chemicals, the Region 5 program will use
the 1 E-06 risk level as the starting point for the protection goal. This is consistent with the EPA
preference to achieve remediation at the lower end of the risk range, and is also consistent with the
concept that the 1 E-06 risk level should be used as the "point of departure" for setting chemical-
specific remediation goals.
B) The individual chemical cancer risk goal may then be revised to a different level within the acceptable
risk range based on consideration of the following primary categories of factors outlined in the
National Contingency Plan and other EPA guidance.
Exposure factors- including the reliability and conservativeness of the selected exposure parameters
to estimate the risks; the potential for exposure from multiple pathways at the site; population
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sensitivity, including the potential for exposure to children and the elderly; balance between the need
to achieve protection for individual chemical exposure and the need to achieve acceptable multiple
chemical exposure; the site-specific background levels of contaminants.
Uncertainty factors - including the level of uncertainty in the dose-response assessment of a specific
chemical and the toxicity factors employed in the risk assessment; reliability and verification of fate
and transport models used to estimate Exposure Point Concentrations; level of uncertainty in the
assumptions for future land use and future groundwater use;
Technical factors - including the actual amount and density of analytical sampling data and the
frequency of sampling in areas of known contamination; the actual chemical-specific
detection/reporting limits achieved in the site investigation; the presence of matrix interferences in
sampling for specific chemicals; the level of confidence to establish reliable and enforceable long-term
exposure controls for contaminants left in place.
C) The preferences and factors described above apply to the development of the risk-based remediation
goals at any RCRA site. They do not take into account the additional criteria of cost and technical
practicability. These criteria would be evaluated through additional site-specific studies such as the
traditional Corrective Measures Study (CMS) and the Corrective Measures Implementation Plan
(CMIP). Consequently, the risk-based remediation goals can be viewed as the starting point for
focusing the additional studies needed for the CMS and CMIP.
Residual soil contaminants - the goal is that residual cumulative cancer risk for multiple chemicals should
not exceed 1E-04. For setting the risk-based remediation goals for individual chemicals, the preferences
and factors described above should be used.
Residual qroundwater contaminants - for carcinogenic constituents which have final MCL values, the goal
is that the MCL should not be exceeded; for all other carcinogenic constituents, the goal is that the
residual cumulative cancer risk for multiple chemicals should not exceed 1E-04. For setting the risk-
based remediation goals for individual chemicals not having a final MCL, the preferences and factors
described above should be used.
Surface water used as drinking water - for carcinogenic constituents which have final MCL values, the
goal is that the MCL should not be exceeded; for all other carcinogenic constituents, the goal is that the
residual cumulative cancer risk for multiple chemicals should not exceed 1 E-04. For setting the risk-
based remediation goals for individual chemicals not having a final MCL, the preferences and factors
described above should be used.
Surface water not used as drinking water - for uses other than drinking water, EPA has established
values known as "Recommended Water Quality Criteria". These criteria are numeric values that protect
human health from the harmful effects of pollutants in ambient water. Under section 304(a) of the Clean
Water Act (CWA), water quality criteria are based solely on data and scientific judgments about the
relationship between pollutant concentrations and environmental and human health effects; they do not
consider economic or social impacts. The criteria also serve as guidance to the states and authorized
tribes in adopting water quality standards in support of the CWA. They also provide guidance to EPA
when it promulgates Federal regulations under the CWA. They are not regulations in themselves and do
not impose legally binding requirements on EPA, states, authorized tribes or the public. There are
currently approximately 80 numeric criteria available for specific chemicals. These are recommended
water concentrations for specific constituents that should not be exceeded in order to provide human
health protection for additional contaminant exposures through surface water (e.g., recreational use,
consumption offish and shellfish).
Non-cancer toxic hazard
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For constituents regarded as non-carcinogenic, the EPA policy is that for each residual contaminant, the
hazard quotient should not exceed a level of 1.0. In addition, for multiple contaminants that express their
threshold toxic effect on the same target organ or by the same mechanism of action, the cumulative (i.e.,
additive) hazard quotients should not exceed a level of 1.0. (The additive hazard quotients are referred to
as a Hazard Index.)
To further clarify and streamline the understanding of residual hazard goals for sites under its jurisdiction,
the Region 5 RCRA program establishes the following policy preferences:
Residual soil contaminants - the goal is the same as described in the paragraph above.
Residual qroundwater contaminants - for non-carcinogenic constituents which have final MCL values, the
goal is that the MCL should not be exceeded; for all other hazardous constituents, the goal is that the
hazard quotient for each constituent should not exceed a level of 1.0.; In addition, for multiple
contaminants that express their threshold toxic effect on the same target organ or by the same
mechanism of action, the cumulative (i.e., additive) hazard quotients should not exceed a level of 1.0.
Surface water used as drinking water - for non-carcinogenic constituents which have final MCL values,
the goal is that the MCL should not be exceeded; for all other hazardous constituents, the goal is that the
hazard quotient for each constituent should not exceed a level of 1.0.; In addition, for multiple
contaminants that express their threshold toxic effect on the same target organ or by the same
mechanism of action, the cumulative (i.e., additive) hazard quotients should not exceed a level of 1.0.
Surface water not used as drinking water - for uses other than drinking water, EPA has established
values known as Recommended Water Quality Criteria. These criteria are numeric values that protect
human health from the harmful effects of pollutants in ambient water. Under section 304(a) of the Clean
Water Act (CWA), water quality criteria are based solely on data and scientific judgments about the
relationship between pollutant concentrations and environmental and human health effects; they do not
consider economic or social impacts. The criteria also serve as guidance to the states and authorized
tribes in adopting water quality standards in support of the CWA. They also provide guidance to EPA
when it promulgates Federal regulations under the CWA. They are not regulations in themselves and do
not impose legally binding requirements on EPA, states, authorized tribes or the public. There are
currently approximately 80 numeric criteria available for specific chemicals. These are recommended
water concentrations for specific constituents that should not be exceeded in order to provide human
health protection for additional contaminant exposures through surface water (e.g., recreational use,
consumption offish and shellfish).
Risk goals for contaminated sediments
In 2002, EPA issued Principles for Managing Contaminated Sediment Risks at Hazardous Waste Sites
(OSWER Directive 9285.6-08). This Directive outlines 11 principles to assist site managers in making
scientifically sound and nationally consistent risk management decisions at contaminated sediment sites.
Plans to remediate, dispose, and manage contaminated sediments can be very complex and involve the
interests of the RP, public stakeholders, and government resource trustees (e.g., Federal and state
fisheries and natural resource agencies). The Directive recommends consultation with the Corrective
Action Branch of the Office of Solid Waste where proposed plans for actions on sediments for an entire
site will address more than 10,000 cubic yards or five acres of contaminated sediment.
Risk goals for specific constituents
Certain constituents present special challenges during the selection of risk goals because of factors
related to potential toxicity, regulatory requirements, background levels, or specific Agency policy.
Constituents for which these factors are likely to be encountered are described below.
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Lead
For potential exposures to lead, the Agency has not assigned either a cancer slope factor or a Reference
Dose. Therefore, a cancer risk level or Hazard Quotient cannot be established for lead when it is
encountered at a RCRA site, and the contribution of lead to cumulative cancer risk or cumulative Hazard
Index also cannot be determined. Consequently, a risk-based residual limit for lead must be established
separately from other constituents.
For hazardous waste cleanup sites and other situations where exposure to lead in soil could be
encountered, the stated goal of the Agency is: "... OSWER will attempt to limit exposure to soil lead
levels such that a typical (or hypothetical) child or group of similarly exposed children would have an
estimated risk of no more than 5% exceeding the 10 ug lead/dl blood lead level. This 10 ug/dl
[micrograms/deciliter] blood lead level is based upon analyses conducted by the Centers for Disease
Control and EPA that associate blood lead levels of 10 ug/dl and higher with health effects in children;
however, this blood lead level is below a level that would trigger medical intervention." This is the
strategy employed as part of determining a soil remediation goal for lead at hazardous waste sites (e.g.,
Superfund, RCRA, Brownfields).
To evaluate health risk from lead, the Agency uses a quantitative model that correlates potential adverse
health effects with lead intake levels and predicted blood lead levels following absorption (Integrated
Exposure Uptake Biokinetic Model; IEUBK). Numerous studies on adverse health effects from lead have
shown that children are a highly sensitive receptor because of the effects of lead on the developing
neurological system.
For lead exposure in the residential land use setting, young children (age 6 to 84 months) are known to
be the sensitive receptor. Based on running the IEUBK Model and taking into account reasonable
background levels of lead in other media (e.g., air, water, diet), the Agency has recommended that a soil
lead level of 400 mg/kg (400 ppm) can be adopted as an acceptable remedial goal for soil in the
residential use setting.
For lead exposure in the non-residential land use setting (e.g., industrial use, commercial use), the
exposed receptor is assumed to be an adult worker, and the sensitive receptor is a developing fetus
being carried by a pregnant female. For this situation, the Agency has developed an Adult Lead Model
which accounts for lead intake by an adult and transfer of lead to a developing fetus. Based on the most
recent Agency analysis, data on baseline blood lead levels in women of child-bearing age were derived
from the NHANES III national study. The data were further analyzed by geographic quadrants and ethnic
groups. The recommendation is that the combined data on ethnic groups in a specific quadrant (e.g.,
Midwest) should be used since the future worker population at most sites is likely to be heterogenous and
could consist of several ethnic groups. For the Midwest quadrant (including all Region 5 States), use of
the NHANES data in the Adult Lead Model resulted in calculation of a protective risk-based goal of 1100
mg/kg. Consequently, a soil lead remedial goal of 1100 mg/kg (1100 ppm) is recommended as an
acceptable goal for soil in the non-residential use setting where only adult workers would be the expected
exposure group.
Arsenic
For arsenic in soils, a problem often encountered at Midwestern sites is that naturally-occurring arsenic
background concentration levels actually exceed the calculated risk-based screening levels. For
example, the Illinois EPA reports that the statewide arsenic background soil concentrations at sites
unimpacted by industry show a mean concentration of 6.7 mg/kg with a range of 0.35-24 mg/kg. This
mean and upper range both exceed the concentration corresponding to the 1E-05 cancer risk screening
level for the typical residential and industrial land use scenarios. Consequently, arsenic will often be
retained as a constituent of concern at RCRA sites based on measured background levels. When final
remedial concentration goals are selected for arsenic, a comparison to the naturally-occurring
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background levels of arsenic at the site will often need to be evaluated.
PCBs
As stated earlier in Section 1.3, PCBs may be encountered as contaminants of concern at many RCRA
sites because of historical industrial activities. At some of these sites, the PCB contamination may trigger
the need to comply with TSCA regulations that could apply to both the site investigation and to remedial
requirements for the site. The remedial requirements could include specific numerical cleanup levels for
future industrial use or future residential use, or the option to base cleanup goals on a site-specific risk
assessment in certain cases. An explanation of the site remedial requirements under TSCA regulations
is presented in Attachment 1.
In addition, it should be noted that the Region 5 RCRA program will confer with the Region 5 TSCA
program (Toxics Program Section) to identify the TSCA requirements that apply at a RCRA site and to
ensure that compliance with TSCA requirements will be achieved through the remedial decisions.
Dioxin
As stated earlier in Section 1.3, the detection of dioxins in soil as a site related constituent is likely to be
encountered at sites where specific industrial or waste treatment practices occurred. Because the EPA
has not completed and released its comprehensive exposure, toxicology and dose-response analysis of
dioxin (the "Dioxin Reassessment"), the EPA has established interim goals for the remediation of dioxin in
soils at sites which are investigated under Superfund and RCRA. The interim goals are presented in the
OSWER Directive "Approach for Addressing Dioxin in Soil at CERCLA and RCRA Sites."
The Directive establishes recommended remedial goals for dioxin in soil under residential and industrial
land use. For current and future residential land use, the recommended remedial goal in soil is 1 ug/kg
TEQ (1 ppb TEQ), where TEQ refers to the "Toxic Equivalents" for the mixture of toxic congeners. For
current and future industrial land use, the recommended remedial goal in soil is a starting point of 5 ug/kg
TEQ (5 ppb TEQ) with a range that should not exceed 20 ug/kg TEQ (20 ppb TEQ).
The Directive addresses only direct contact to contaminated soil. Consequently, the actual site risks and
potential remedial goals for other exposure media (e.g., sediment, food crops, fish) and other exposure
scenarios (crop consumption, fish consumption) would be need to be developed through a site-specific
risk assessment.
Comparison of site-related constituent concentrations to naturally-occurring background levels
The importance of conducting sampling for evaluating the levels of naturally-occurring constituents at a
site was described earlier (Sections 1.3 and 2.3). EPA's preference is that the health risks from the site-
specific background concentrations should be calculated and understood in comparison to the risks from
the site-related chemical releases. EPA will also consider any additional supporting evidence that the
measured background levels are naturally-occurring or are regional background levels that were not
impacted by the site-specific industrial activities.
Generally, the RCRA program will not set cleanup goal concentrations for site releases (SWMUs/AOCs)
that are lower than the concentrations found for natural background levels at the site. For example, in
cases where a risk-based cleanup goal (e.g., 1E-05 cancer risk) for a chemical constituent would be
below the site-specific background concentrations, the cleanup goal may be established based on the
background level. Consequently, the RCRA program will not require remediation of naturally-occurring
metals to levels below the site-specific background of naturally-occurring metals.
Key References:
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NATIONAL OIL AND HAZARDOUS SUBSTANCES POLLUTION CONTINGENCY PLAN: Remedial
investigation/feasibility study and selection of remedy (Code of Federal Regulations; TITLE 40 -
PROTECTION OF ENVIRONMENT; CHAPTER I - ENVIRONMENTAL PROTECTION AGENCY; PART
300; Subpart E - Hazardous Substance Response; Sec. 300.430)
http://homer.ornl.gov/oepa/guidance/cercla/siteclosure/document.cfm?type=ncp&sh=31646&len=15175
Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions (OSWER Directive
9355.0-30; April 22, 1991) www.epa.gov/superfund/programs/risk/baseline.pdf
Compilation of National Recommended Water Quality Criteria (Office of Water; Dec. 2003)
http://www.epa.gov/waterscience/standards/wqcriteria.html
Principles for Managing Contaminated Sediment Risks at Hazardous Waste Sites (OSWER Directive
9285.6-08; February 12, 2002) www.epa.gov/superfund/resources/remedy/pdf/92-85608-s.pdf
Draft Contaminated Sediment Remediation Guidance for Hazardous Waste Sites;
www.epa.gov/superfund/resources/sediment/guidance.htm
Clarification to the 1994 Revised Interim Soil Lead (Pb) Guidance for CERCLA Sites and RCRA
Corrective Action Facilities (OSWER Directive (9200.4-27P; August 1998)
http://www.epa.gov/superfund/programs/lead/products/oswer98.pdf
Reference Manual: Documentation of Updates for the Integrated Exposure Uptake Biokinetic Model for
Lead in Children (IEUBK) Windows Version (EPA 540-K-01-007; OSWER 9285.7-44; May 2002)
http://www.epa.gov/superfund/programs/lead/products.htm
Recommendations of the Technical Review Workgroup for Lead for an Approach to Assessing Risks
Associated with Adult Exposures to Lead in Soil (EPA-540-R-03-001; OSWER 9285.7-54; Jan. 2003)
http://www.epa.gov/superfund/programs/lead/products.htm
BLOOD LEAD CONCENTRATIONS OF U.S. ADULT FEMALES: SUMMARY STATISTICS FROM
PHASES 1 AND 2 OF THE NATIONAL HEALTH AND NUTRITION EVALUATION SURVEY (NHANES
III) (OSWER #9285.7-52; March 2002)
http://www.epa.gov/superfund/programs/lead/products.htm#guidance
Adult Lead Methodology Frequently Asked Questions (EPA-OSWER; Technical Review Work Group for
Lead; April 2004) http://www.epa.gov/superfund/programs/lead/almfaq.htm
Approach for Addressing Dioxin in Soil at CERCLA and RCRA Sites (OSWER Directive 9200.4-26; April
13, 1998)
Role of Background in the CERCLA Cleanup Program (OSWER Directive 9285.6-07P; April 26, 2002)
http://www.epa.qov/superfund/proqrams/risk/bkqpol ianOI .pdf
3.2: Ecological Risk Management Goals
Establishing remediation goals for ecological receptors is considerably more difficult than establishing
such goals for the protection of human health due to the scarcity of broadly applicable and quantifiable
toxicological data for wildlife species. Remedial exposure levels are best established on a site-specific
basis because of the large variation in the kinds and numbers of receptor species present at sites, the
differences in their susceptibility to contaminants, and the tremendous variation in environmental
bioavailability of many contaminants in different media.
Since ecological receptors at sites exist within a larger ecosystem context, remedies selected for
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protection of these receptors should also assure protection of the ecosystem components upon which
they depend or which they support. Except at a few very large sites, RCRA and Superfund risk
assessments typically do not address effects on entire ecosystems, but normally gather effects data on
individuals in order to predict or postulate potential effects on local wildlife, fish, invertebrate, and plant
populations and communities that occur or that could occur in specific habitats at sites (e.g., wetland,
floodplain, stream, estuary, grassland, etc.). Ecological risk assessments incorporate a wide range of
tests and studies to either directly estimate community effects (e.g., benthic species diversity) or indirectly
predict local population-level effects (e.g., toxicity tests on individual species), both of which can
contribute to estimating ecological risk. RCRA remedial actions generally should not be designed to
protect organisms on an individual basis, but to protect local populations and communities of biota. (An
exception is legally designated protected resources, such as listed or candidate threatened and
endangered species that could be exposed to site releases). Contaminant levels that are expected to
protect local populations and communities can be estimated by extrapolating from effects on individuals
and groups of individuals using a lines-of-evidence approach.
For establishing remedial goals, the PM should consult with an ecological risk assessor to address the
following four questions, which highlight fundamental ecological risk assessment and risk management
concerns:
A. What ecological receptors should be protected?
EPA guidance provides information on identifying and selecting assessment endpoints for evaluating the
ecological risk to biotic receptors at sites. An assessment endpoint is defined as: "an explicit expression
of the environmental value that is to be protected." RCRA risk assessments use site-specific assessment
endpoints that address chemical-specific potential adverse effects to local populations and communities
of plants and animals (e.g., reductions in populations offish-eating birds, or reductions in survival,
reproduction or species diversity of indigenous benthic communities). The number of necessary
assessment endpoints depends on the number and type of contaminated habitats at the site. Risk
assessment measures (i.e., measures of effect, measures of exposure, measures of ecosystem and
receptor characteristics) should then be selected based on site-specific conditions and used to infer
effects on the local population or community of concern. Examples might include: toxicity test results,
tissue concentrations, and physical-chemical measurements related to fate and transport of the
contaminants.
B. Is there an unacceptable ecological risk at the site?
Unless the ecological impacts are readily apparent (e.g., no vegetation will grow on the contaminated
portion of the site or no benthic organisms exist in the sediment downstream from the release), site-
specific biological data should be developed in order to determine if there are unacceptable risks. The
baseline risk assessment may include site-specific toxicity tests with test organisms that address the
assessment endpoints selected for the site. These readily available test organisms are considered
surrogates for the actual species exposed. The ecological risk assessor can identify the tests and species
most appropriate for the site. Other techniques to estimate the magnitude and severity of risks may
include modeling to predict food-chain transfer and secondary toxicity of bioaccumulative chemicals to
upper trophic level receptors, the measurement of tissue concentrations, the performance of species
diversity studies (e.g., Rapid Bioassessment Protocols), and in-situ bioassays (e.g., caged fish/bivalves).
Through the use of field studies and/or toxicity tests, several types of data may be developed to provide
supporting information for a lines-of-evidence approach to characterizing site risks. This approach is far
superior to using single studies or tests or measurements to determine whether or not the observed or
predicted risk is unacceptable.
If studies or tests performed with site soil, sediment, or water demonstrate or predict serious adverse
effects (e.g., increased mortality, diminished growth, impaired reproduction, etc.) on the selected
assessment endpoints as compared to tests conducted at an appropriate reference site or using
reference media, there is usually sufficient evidence to assume that unacceptable adverse effects have
already occurred or may occur at the site.
Sufficient information should be collected in the ecological risk assessment to allow the risk assessor to
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make a decision about: (a) causality between levels of contamination and effects; (b) whether the
observed or predicted adverse effect on the site's local population or community is of sufficient
magnitude, severity, areal extent, and duration that they will not be able to recover and/or maintain
themselves in a healthy state; and (c) whether these effects appear to exceed the natural changes in the
components typical of similar non-site-impacted habitats (i.e., reference areas). The information gathered
in the ecological risk assessment should provide a clear and concise estimate of overall risk to the site
under review.
C. Will the cleanup cause more ecological harm than the current site contamination?
Whether or not to clean up a site based on ecological risk can be a difficult decision at some sites. When
evaluating remedial alternatives, the NCP highlights the importance of considering both the short-term
and long-term effects of the various alternatives, including the no action alternative. Even though an
ecological risk assessment may demonstrate that adverse ecological effects have occurred or are
expected to occur, it may not be in the best interest of the overall environment to actively remediate the
site. At some sites, especially those that have rare or very sensitive habitats, removal or in-situ treatment
of the contamination may cause more long-term ecological harm than leaving it in place.
The likelihood of the response alternatives to achieve success and the time frame for a biological
community to fully recover should be considered in remedy selection. Although most receptors and
habitats can recover from physical disturbances, risk managers should carefully weigh both the short-
and long-term ecological effects of active remediation alternatives and passive alternatives when
selecting a final response. This does not mean that there is a preference for passive remediation; all
reasonable alternatives should be considered. For example, the resilience and high productivity of many
aquatic communities would allow for aggressive remediation; whereas the removal of bottomland
hardwood forest communities in an area in which they cannot be restored due to water management
problems would argue against extensive action in all but the most highly contaminated areas.
D. What cleanup levels are protective?
When a decision is made that a response action should be taken at a site based on unacceptable
ecological risk, the risk manager selects chemical-specific cleanup levels that are acceptable. These
would be levels that provide adequate protection of the ecological receptors as determined from the
selected assessment endpoints. Appropriate cleanup levels can be identified by using the same toxicity
tests, population or community-level studies, or bioaccumulation models that were used to determine if
there was an unacceptable ecological risk. Sufficient testing and interpretation should be performed at
various site locations to quantify the relationship between chemical concentrations and effects. The data
can then be used to establish a concentration and response gradient to define the concentration that
represents an acceptable (i.e., protective) level of risk. At some relatively small sites, however, it may be
more cost effective to remove, treat, or contain all contamination rather than to generate a concentration
and response gradient.
An additional difficulty is the determination of the acceptable level of adverse effects for the receptors to
be protected (e.g., what percent reduction in fish survival or in benthic species diversity is no longer
protective?) There is no "magic" number that can be used. The acceptable level will be dependent on
the assessment endpoints selected and the risk assessment measures used, including the chemical and
biological data gathered from the range of contaminated locations. While it may be desirable to identify a
standard numerical level of risk reduction that is protective, it is impracticable to do this for each possible
species that could be exposed. For that reason, surrogate measures or representative species are used
to evaluate the ecological risks to the assessment endpoints at the site. The acceptable level of adverse
effects should be discussed and understood by the PM and risk assessor.
Key Reference:
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Ecological Risk Assessment and Risk Management Principles for Superfund Sites (OSWER Directive
9285.7-28P; Oct. 1999).
3.3: Source Control
Source Control was previously mentioned as a situation to address under High Risk Releases (Section
2.1). When final remedies are ready to be selected, the need for additional source controls not covered
under High Risk Releases should be considered. At least three situations are recognized where
additional source control activity could be recommended:
*• Source control at a SWMUs or AOCs which did not have High Risk Releases but have releases for
which the PM may want to set risk-based remedial goals. In this case, the original source continues to
be a release point for chemical constituents if left in place; the PM should consider permanent source
control or source removal to prevent the need for long-term chemical monitoring as the remedial
solution;
*• Remediation of free phase chemical or NAPLs even where groundwater is not expected to be highly
mobile or to be prime candidate for drinking water source; EPA regards free products and NAPLs as
sources for future chemical migration and for degradation of groundwater resource quality;
*• Removal or elimination of sources which prevent land from being converted or revitalized to a better or
more ideal future condition including enhancement of ecological quality and habitat;
3.4: Removal/Reduction
Removal/Reduction is the process of accomplishing the Residual Risk Goals through the direct
elimination or reduction of risk reduction by excavation and removal of chemical constituents and/or
reduction of concentrations by waste treatment in-situ. The following are recommended procedures that
would be employed to enhance appropriate removal/reduction decisions:
*• Develop or calculate the chemical-specific cleanup goals that will be needed to meet the Residual
Risk Goals at each SWMU or AOC that needs action; the chemical-specific cleanup goals can be
determined from the original PRG values used for risk-based screening (Section 1.10) and by taking
into account the desired cancer risk and Hazard Index goals. For exposure scenarios not covered
through risk-based screening, the chemical-specific cleanup goals will need to be determined by
utilizing the results of the site-specific risk assessments (RCRA risk assessors and ecologists can be
consulted for assistance in interpreting and utilizing the results of site-specific risk assessments);
*• For many locations, the problem will be dominated by a few "risk driving" chemicals; For soils and
sediments - the removal/reduction plan can often focus on the risk drivers; establish the risk-based
cleanup goal for the risk driving chemical(s); if reduction of risk driving chemicals is accomplished, the
cumulative risk and Hazard Index goals will be satisfied; For groundwater - set a cleanup goal at the
MCL for each chemical possessing an MCL; for chemicals not possessing an MCL, the chemical-
specific cleanup goals will need to be determined by utilizing the results of the site-specific risk
assessments (RCRA risk assessors and ecologists can be consulted for assistance in interpreting and
utilizing the results of site-specific risk assessments);
*• Conduct additional sampling of soil or sediments at SWMUs or AOCs if necessary to establish the
starting geographic boundaries (lateral and vertical) over which the initial removal action should occur.
Develop confirmatory sampling plans for excavated areas to determine if clean-up goals are achieved
or if excavation needs to continue. Some options to consider:
* allow statistical analysis of data in excavation zones and accept a mean chemical
concentration not exceeding the chemical-specific target cleanup goal as long as the highest
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concentration does not exceed some specific multiple of the cleanup goal (e.g., 2x of cleanup
goal).
* the depth of excavation should be linked to the risk-based management goal; all excavations
should be planned on basis of future exposure to contaminated surface soil; excavation
should account for other likely future activities at site (e.g., gardening, parking lot construction;
building excavation); all excavations should be planned to the depth needed to protect the
migration to groundwater pathway;
3.5: Engineered Controls
Engineered Controls are physical structures or barriers designed to minimize or prevent exposure when
contaminants are left in place. They can also be used to prevent the migration of chemical contaminants
to locations where unacceptable exposure might occur. They do not accomplish reduction of chemical
contaminant concentrations except through natural attention overtime.
Three categories of engineered controls that are commonly regarded as useful risk management options
are: caps, cut-off walls, and hydraulic containment barriers. They were previously described as examples
of Interim Measures (Section 2.2). For selection of these controls as final remedies, the following factors
should be considered:
• Why is an engineered control a necessary or desirable alternative to contaminant removal? EPA's
stated preference is that contaminant sources and contaminant migration should be addressed
through direct contaminant removal or direct reduction of contaminant concentrations. Consequently,
the selection of engineered controls should be accompanied by further analysis to show that controls
are suitable options after evaluating important factors such as technical practicability, implementation
time, and total cost overtime.
• These control methods may appear to be less costly for initial application, but may need to be
operated and maintained over a long time period. Successful implementation may also need
continued environmental sampling to demonstrate effectiveness.
• These controls usually also require placing institutional controls on the property to ensure that the
engineered control remains in place; institutional controls may need to remain in place for a very long
time if combined with natural attenuation (example - natural attenuation of volatile and semi-volatile
contaminants in soil and groundwater).
• Implementation and maintenance of the engineering control may affect the attractiveness and
revitalization options of the property.
3.6: Monitored Natural Attenuation of Chemical Contaminants
The term "monitored natural attenuation" (MNA) refers to the reliance on natural processes that can lead
to the reduction in concentration or mobility of chemical constituents. Within the context of a site
remediation approach, the objective of MNA is to achieve site-specific remediation objectives within a
time frame that is reasonable compared to that expected from the application of other more active
methods. The natural attenuation processes that are at work in such a remediation approach include a
variety of physical, chemical, or biological processes that, under favorable conditions, can act without
human intervention to reduce the mass, toxicity, mobility, volume, or concentration of contaminants in
groundwater and soil.
These in-situ processes include biodegradation; dispersion; dilution; sorption; volatilization;
radioactive decay; and chemical or biological stabilization, transformation, or destruction of contaminants.
When deciding to rely on natural attenuation processes for site remediation, EPA prefers those processes
that degrade or destroy contaminants. Also, EPA generally expects that MNA will only be appropriate for
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sites that have a low potential for contaminant migration.
Natural attenuation processes are typically occurring at all sites, but to varying degrees of effectiveness
depending on the types and concentrations of contaminants present and the physical, chemical, and
biological characteristics of the soil and groundwater. Natural attenuation processes may reduce the
potential risk posed by site contaminants in three ways:
(1) Transformation of a contaminant(s) to a less toxic form through destructive processes such as
biodegradation or non-biological transformations;
(2) Reduction of contaminant concentrations such that potential exposure levels may be reduced;
(3) Reduction of contaminant mobility and bioavailability through sorption onto the soil or rock matrix.
Where conditions are favorable, natural attenuation processes may reduce contaminant mass or
concentration at sufficiently rapid rates to be integrated into a soil or groundwater remedy for a site. After
source control measures are put in place, natural attenuation may be sufficiently effective to achieve
remediation objectives at some sites without the aid of other traditional active remedial measures.
However, EPA's expectation is that MNA will be used in conjunction with active remediation measures.
For example, active remedial measures should be applied in areas with high concentrations of
contaminants while MNA could be used for low concentration areas; or MNA could be used as a follow-up
to active remedial measures.
EPA does not view MNA to be a "no action" remedy, but rather considers it to be a means of addressing
contamination under a limited set of site circumstances where its use meets the applicable statutory and
regulatory requirements. MNA is not a "presumptive" or "default" remediation alternative, but rather
should be evaluated and compared to other viable remediation methods (including innovative
technologies) during the study phases leading to the selection of a remedy. The decision to implement
MNA should include a comprehensive site characterization, risk assessment where appropriate, and
measures to control sources.
For practical guidance in making a decision on whether MNA should be adopted as an appropriate
remedy at a site, the PM should evaluate the following criteria and recommendations:
Appropriate Situations Where MNA May Be Considered
• The RP can demonstrate that MNA would be able to achieve groundwater or soil cleanup objectives
such as the need to reduce contaminant concentrations to the acceptable risk-based goals (e.g.,
MCLs; chemical-specific risk limits);
• Measures for source control of the original groundwater or soil contamination are already in place;
• The dominant natural attenuation processes would cause degradation or destruction of contaminants
as opposed to those processes that merely dilute contamination or prevent its movement;
• The groundwater contaminant plume(s) is already stable or shrinking in extent;
• The estimated time frame to meet cleanup levels is reasonable considering factors such as the
desired groundwater use and the time frames required for other remedies; and the time frame is
comparable to that which could be achieved through active remediation;
• The MNA remedy would be used in conjunction with an active remedial system or as a follow-up
measure to active remediation.
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Evaluation of the MNA Proposal
A three-tiered approach to evaluating MNA as a potential remedy is recommended. In this approach,
successively more detailed information is collected as necessary to provide a specified level of
confidence on the estimates of attenuation rates and the remediation time frame. These three tiers of
site-specific information are:
(1) Historical groundwater and/or soil chemistry data that demonstrate a clear and meaningful trend of
decreasing contaminant mass and/or concentration overtime at appropriate monitoring or
sampling points. (In the case of a groundwater plume, decreasing concentrations should not be
solely the result of plume migration. In the case of inorganic contaminants, the primary attenuating
mechanism should also be understood.)
(2) Hydrogeologic and geochemical data that can be used to demonstrate or deduce the type(s) of
natural attenuation processes active at the site, and the rate at which such processes will reduce
contaminant concentrations to required levels. For example, characterization data may be used to
quantify the rates of contaminant sorption, dilution, or volatilization, or to demonstrate and quantify
the rates of biological degradation processes occurring at the site.
(3) Data from field or microcosm studies (conducted in or with actual contaminated site media) can
directly demonstrate the occurrence of a particular natural attenuation process at the site and its
ability to degrade the contaminants of concern (typically used to demonstrate biological
degradation processes only).
The decision to move to successive tiers of information should be made as follows:
If historical data are not of sufficient quality and duration to support the requirements of Tier Number 1,
move onto Tier Number 2 and obtain data to characterize the nature and rates of natural attenuation
processes at the site; If these data are also inadequate or inconclusive, move onto Tier Number 3 and
conduct the microcosm studies.
Contingency Remedies
• EPA recommends that RPs and regulators should consider the need for identifying one or more
contingency remedies; A contingency remedy (or contingency plan) is a cleanup approach specified
in a remedy decision document that functions as a "backup" remedy in the event that the selected
MNA remedy fails to perform as anticipated;
• Contingency remedies are especially appropriate for an MNA remedy that is selected based primarily
on predictive analyses or predictive models rather than documented analytical data demonstrating
trends of decreasing contaminant concentrations.
Monitoring Period
The MNA remedy should include conditions requiring the collection of constituent concentration data until
groundwater cleanup level goals are met at the point of compliance; Usually, monitoring would be
continued for some specified additional time period (e.g., 1-3 years) to demonstrate that concentration
levels are stable and remain below the cleanup goals.
Key Reference:
Use of Monitored Natural Attenuation at Superfund, RCRA Corrective Action, and Underground Storage
Tank Sites (Final) (OSWER Directive D9200.4-17; April 1999)
http://www.epa.gov/swerust1/directiv/d9200417.htm
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3.7: Institutional Controls
Institutional Controls (ICs) are restrictions on the use of land, water, and other resources that are used to
limit or prevent human activity that could result in exposure to environmental media containing chemical
contaminants. They are used most appropriately as an adjunct or supplement to other more direct risk
management and risk reduction options such as source control and engineered controls. ICs should not
be regarded as a substitute for active remedial efforts that will that prepare a site for the highest level of
beneficial reuse and revitalization. Consequently, EPA believes that ICs will seldom serve as the sole
remedy at a site.
ICs should be evaluated in the same level of detail as other remedy components because they are
considered to be response actions under Superfund and RCRA. ICs should be evaluated by the same
balancing criteria recommended when considering other remedial decisions for a RCRA site.
When is the placement of an 1C a necessity?
The need for an 1C can be driven by both the need to prevent potential exposure and to protect another
remedy option. The general requirement is: If any remedial option calls for leaving waste in place and
unrestricted land use and unlimited exposure should not be allowed, an 1C should be placed as a remedy
to ensure that unacceptable exposure from residual contamination does not occur. Typical situations that
would call for placement of an 1C would include the following:
• The RP elects to conduct risk screening, site-specific risk assessment and/or contaminant remediation
based on future industrial land use rather than evaluating or remediating contaminants for future
residential land use;
• Groundwater will remain contaminated above drinking water standards and/or acceptable risk
concentrations for residential water consumption so that use of groundwater as a drinking water
source must be prevented.
• Remedy options that leave residual wastes on-site including capping waste in place, construction of
containment facilities, and natural attenuation and long-term pumping-and-treatment of groundwater.
What are the types of ICs that could be applicable to the Region 5 RCRA Program?
The following types are recognized as being potential candidates for use as ICs in RCRA corrective
action remedies:
• Informational Devices: Informational devices provide information or notification. Common examples
include State registries of contaminated properties, deed notices, and advisories. Informational
devices themselves may often be non-enforceable. For example, deed notices are a common form of
institutional control because they effectively inform future owners about the residual contamination
and any use restrictions imposed on the facility. However, deed notices, like most informational
devices, have no legal force to limit or control land use or activities; they serve only as a notice
function and should not be relied upon as the sole institutional control at a site.
• Governmental Controls: Governmental controls are usually implemented and enforced by a State or
local government and are based on State or local authorities that restrict property use. Specific
examples include restrictions on the use of land and water, zoning restrictions, ordinances, building
permits or other permit requirements. Governmental controls can be useful in controlling potential
exposure. However, their effectiveness is dependent on enforcement by a third party (i.e., state or
local government) and the controls can be changed or terminated at any time without the involvement
of EPA. Consequently, for corrective action projects where Region 5 is the lead Agency, these
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controls should not be used as the sole institutional control.
• Proprietary Controls: Proprietary controls have their basis in private property law. There are
numerous controls within this category, including easements and covenants. Controls under this
category are unique in that they create legal property interests. In other words, proprietary controls
involve legal instruments placed in the chain of title for the property that convey a property interest
from the owner (grantor) to a second party (grantee) for the purpose of limiting the use or imposing
restrictions on land and/or water. An example of this type of control is an easement to provide access
rights to inspect and monitor. The principal benefit of this type of control is that it can be made to "run
with the land". It is binding on subsequent purchasers of the property (successors in title) and
transferable, which may make it more reliable in the long-term than other types of institutional controls.
Generally, proprietary controls are advisable when the restrictions on activities are intended to be
long-term or permanent, or when other controls are deemed unreliable. EPA's authority to acquire
proprietary controls at a site could become a complicated situation. Consequently, the PM should
consult with a Regional attorney to evaluate whether EPA has the authority to acquire proprietary
controls.
• Enforcement Actions with Institutional Control Components: EPA administrative orders and judicial
consent decrees may be used to require and ensure long-term compliance with institutional controls.
These enforcement documents can be used where the landowner agrees to limit or allow certain long-
term site activities. Although frequently used, certain limitations should be addressed. For example,
most enforcement actions do not "run with the land". This means that the restrictions in the
enforceable order/decree are only binding on the signatories. There are often provisions requiring
notification to EPA prior to a property transfer in these agreements. However, the property restrictions
themselves are not automatically transferred at the time of the property transaction. This limitation
may be addressed by having either the prior land owner remain responsible to EPA for continued
performance and adherence to the institutional control, or by imposing a separate order negotiated
with the subsequent purchaser.
Does the Region 5 RCRA Program have a policy for how ICs should be selected?
Based on considerable review of the types of available ICs and the potential effectiveness of ICs to serve
as remedies, the Region 5 RCRA program has developed the following policy preferences for how ICs
should be selected and implemented:
*• ICs should be selected only where the Region believes they will be effective and enforceable, both in
the short-term against the current facility owner/operator and in the long-term against potential future
property owners. To enhance the over-all effectiveness of institutional controls, project managers
should consider "layering" controls (i.e., using multiple types of ICs) to provide overlapping assurances
of protection from future contaminant exposure.
*• To ensure compliance with an 1C, a facility owner/operator must agree to a written enforceable order
which contains the specific requirements for the 1C and binds the owner/operator to notify subsequent
property owners of the 1C and the obligation to maintain the requirements of the 1C after the property
transfer.
*• EPA generally will ensure federal enforceability of the owner/operator's commitment to maintain and
operate the selected 1C through the use of consent orders and/or judicial consent decrees.
Depending upon site specific conditions, EPA may use its consent order authority under Sections
3008(h) or 7003 of RCRA or Section 106(a) of CERCLA. There are other statutory sections such as
Section 311 of the Clean Water Act which may also apply depending on the nature of the hazards
posed at the facility. For facility owners/operators with a permit or an approved closure/post-closure
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plan, EPA will require them to enter into a consent order separate and apart from the permit and/or
closure/post-closure permit. Similarly, owner/operators subject to voluntary agreements would have
to enter into a consent order for the component of the remedy which relies upon ICs.
More details on the enforceable consent order and the specific requirements it needs to contain can be
found in the Region 5 guidance document listed below.
Key Reference:
Use of Institutional Controls in the RCRA Corrective Action Program (EPA-Region 5; Waste, Pesticides,
and Toxics Division; March 2000)
3.8: Risk Management Plan
At this point in the site investigation, the PM should have received a set of proposed remedies from the
RP for review. For Voluntary and Streamlined Orders, this information would generally be included in the
Final Corrective Measures Proposal. For projects being conducted under traditional 3008(h) Orders, this
information would be included in the Corrective Measures Study. The proposed remedies submitted by
the RP should be the culmination of the site investigation work performed under the traditional RCRA
correction action activities such as the RFI and the CMS. The scope of the Plan should be discussed
with the RP to reach consensus on what it should contain. The proposed remedies would normally be
reviewed by and commented on by the PM, which would result in a set of acceptable remedies. The Plan
should focus on an explanation of the proposed remedies and not on re-evaluation of existing site data.
Ideally, the Plan should provide the following information that will directly assist the PM to convey the
proposed site decisions to RCRA Program Managers and the public:
• Describe each remedial action proposed to be performed or put in place to eliminate risk or reduce
risk to acceptable levels; the Plan should identify specific site locations (SWMUs, AOCs), specific
media (soil, groundwater, sediments), and specific chemical constituents that will be addressed by a
remedy; Explain whether the remedy is needed to address human health risk and/or ecological risk;
• Explain how each proposed remedial option will achieve EPA's remedial expectations. EPA's
expectations are as follows and are explained in more detail in Attachment 3 of this document:
*• To use treatment to address principle threat wastes.
*• To return groundwaters to their maximum beneficial use.
*• To use engineering controls for low-level threats.
*• To use institutional controls.
*• To control or eliminate sources.
*• To consider innovative technologies.
*• To use a combination of methods to achieve protection.
• Evaluate each proposed remedy using EPA's Remedy Threshold and Balancing Criteria. EPA's
criteria are as follows and are explained in more detail in Attachment 3 of this document:
*• Threshold Criteria: - Protect Human Health and the Environment
- Attain Media Cleanup Standards
- Control Sources to reduce or eliminate further releases
*• Balancing Criteria: - Long-term reliability and effectiveness
- Reduction oftoxicity, mobility, or volume of wastes
- Short-term effectiveness
- Implementability
-Cost
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- Community and State Acceptance
Identify remedies that require long-term technical monitoring or maintenance to accomplish the risk
management goal (e.g., continued groundwater monitoring to demonstrate migration under control);
describe the criteria used to decide when the long-term technical remedy achieves the risk
management goal;
Describe the approximate schedule or time line for implementing the remedies;
Identify any remedies already put in place at the site (e.g., IMs, source controls) and explain how they
accomplished a risk management goal(s); Explain any significant additional actions needed to
complete the remedies (e.g., addition of an 1C);
Provide a recommendation for the preferred remedy or combination of technologies evaluated that will
achieve EPA's remedial expectations and effectively provide a long-term solution which achieves the
project goals.
CHAPTER 5:
Relationship between the Risk Management Strategy and State RCRA Corrective Action Authority
By regulatory design and historical practice, the States have become primary implementers of many
provisions of the Federal RCRA program. In some states, nearly all of the Federal RCRA provisions
have been delegated to State authority. In EPA Region 5, all 6 States have been granted authority to
implement a large portion of Federal RCRA Corrective Action program.
The granting of authority means that the EPA determined that a State could implement a RCRA
corrective action program that provides for site investigations and site remedial decisions which would
provide for remedies and protections to land and water that would be equivalent to remedies provided by
the Federal program. In addition, the States may decide to implement standards or additional
requirements which could be interpreted as making the State RCRA program more "stringent" than the
federal program. The States must apply their own environmental law making authority in order to create
these additional requirements and standards.
Because of the large number of RCRA sites that must be addressed, the administrative need exists to
conduct RCRA corrective action under both Federal and State authority. As expected, certain problems
have been identified in achieving consistency and efficiency when several different agencies try to
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administer the same basic program. Therefore, Region 5 and several States have entered into
Memorandums of Understanding (MOUs) to help define the roles of the agencies in implementing RCRA
corrective action and to avoid administrative and legal conflicts between the agencies. MOUs are non-
binding documents which may be modified or rescinded by the discretion of one or both parties.
Because of the apparent "dual" authorities to implement RCRA corrective action, questions and concerns
have surfaced about the legal and practical relationship between Federal and State corrective action
programs. A major concern is that RPs may perceive that two distinct sets of corrective action
regulations apply to the same investigation. The RPs do not want to be required to conduct a separate
investigation to satisfy each agency (i.e., "be required to serve two masters"), and do not want to be
placed in the position of having one agency's decisions called into question by a second agency (i.e.,"be
caught in double jeopardy").
After reviewing its MOUs with the states and considering the need to expedite corrective action in a clear
and transparent manner, the Region 5 RCRA program will adopt the following working relationship to
avoid the problems described above and to expedite decision-making:
• When a State is the lead regulatory agency for a corrective action site project, the State will essentially
be the implementer of the federal RCRA program. Region 5 will recognize the authority of the State to
oversee site investigations and to make final decisions on site remediation. Region 5 will provide
comment and technical assistance to the particular state on the corrective action project if requested.
• When Region 5 is the lead regulatory agency for a corrective action site project, Region 5 becomes
the implementer of the State RCRA program for the State in which the project is located. Region 5
expects that States will recognize the authority of Region 5 to oversee site investigations, to exercise
its professional judgment in implementing the state's corrective action program, and to make final
decisions on site remediation.
As a complement to the above points, Region 5 will make significant efforts to understand each State's
corrective action program requirements (legal and policy), and to identify significant differences between
the state and federal programs. This will include participation in training programs, workshops, and active
technical exchanges between project managers, program managers and other staff. When developing
risk management decisions for a site, Region 5 will review State requirements and State standards that
would be reasonable to apply to the federal decisions. Region 5 will make clear where specific State
requirements and/or State standards are being applied in its decisions. However, Region 5 will still apply
its own professional judgment in making decisions and will favor accomplishing performance goals over
the application of specific processes.
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ATTACHMENT 1:
Criteria for determining compliance with Toxic Substances Control Act (TSCA) regulations at a
RCRA site found to have PCB contamination
RCRA sites found to be contaminated with PCBs must be remediated in a manner that satisfies
requirements of the Federal PCB regulations under TSCA at 40 CFR Part 761, particularly 761.50(b)(3)
and 761.61 (a) thru (c). An important consideration for the applicability of the PCB regulations is the
source of the PCBs at the site, and both the date and concentration of the original release or spill of the
PCBs. In some cases, depending on the date and concentration of the original release or spill and the
current concentration of PCBs found at the site, remediation may not be required.
If the PCBs at the site are the result of a regulated release or spill, specific information should be
submitted to the Region in the form of a notification or application which needs to include the following
types of information: sampling data (i.e., characterization of PCBs in environmental media and cleanup
verification); cleanup levels; engineering and institutional controls for PCBs remaining on site; and off-site
disposal procedures for remediation waste;
Parti: Site Investigation Phase
PCB Concentration Considerations (In-situ and Source)
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The source of the release or spill of PCBs is an important consideration to determine if and how any PCB
contamination as the site will or should be remediated. These regulatory considerations are discussed
below along with a table which summarizes the considerations.
If the source concentration of the original release or spill was < 50 ppm (< 50 mg/kg) PCBs, regardless of
the date of release, or if the release occurred before April 18,1978, regardless of the concentration at
time of release, the site is not required to be remediated under TSCA. The release can be characterized
and remediated under RCRA, as described earlier in Section 3 and Section 4 of this Risk Management
Strategy. If the release occurred before April 18,1978 and the concentrations of PCBs found at the site
are >50 ppm, cleanup is not required if the responsible party can demonstrate that the PCBs do not
present an unreasonable risk to human health or the environment.
For sites that have PCB contamination resulting from a release or spill that occurred prior to April 18,
1978, off-site disposal of any PCB contaminated material can be based on its "as found" concentration,
with the exception that PCB contaminated material with concentrations >50 ppm may be disposed of in a
hazardous waste (RCRA C) landfill if a notification or application as described below under "Notification
and/or Application Requirement" is submitted to the Region.
If the source of the original release or spill was >50 ppm PCBs and the release occurred on or after April
18, 1978, regardless of the concentration of PCBs found at the site, the site must be remediated in
accordance with the Federal PCB regulations, as described below under "Remedial Decision Phase."
If the date or concentration of the original release or spill is not known, it must be assumed that the PCBs
are regulated and are required to be remediated. In other words, the assumption must be made that the
source was >50 ppm and the release occurred on or after April 18, 1978.
April 18, 1978 is used since that is the effective date of the PCB Disposal and Marking Rule, when
releases of PCBs became regulated. (There are actually two applicable dates and concentrations, April
18, 1978, and July 2, 1979, and 50 ppm and 500 ppm. However, only one date and concentration, the
most conservative combination, are provided here to avoid confusion.)
Date of release
before
April 18, 1978
before
April 18, 1978
Source concentration
any concentration
(above or below 50
ppm)
any concentration
(above or below 50
ppm)
As found
concentration
< 50 ppm
>50 ppm
Cleanup required
under TSCA?
No
Possible, depending
on an evaluation of
the risk of releases
of PCBs from the
site. If the site
cannot demonstrate
that there is no
unreasonable risk,
than the PCBs
should be cleaned
up.
Comment
See761.50(b)(3)(i)and
definition of PCB
remediation waste
(761.3)
See761.50(b)(3)(ii).
The Region 5 PCB
program typically
requests the
responsible party to
demonstrate that there is
no unreasonable risk for
leaving the PCBs at the
site.
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on or after
April 18, 1978
on or after
April 18, 1978
< 50 ppm
>50 ppm
< 50 ppm
>50 ppm
No
Yes
See definition of PCB
remediation waste
(761.3).
Remediate per 761 .61
(a),(b),or(c).
Site Investigation and Characterization
If PCBs are known, assumed, or expected to be at a site, the site must be investigated to determine the
extent of the contamination. The Federal PCB regulations include guidance for characterization
sampling. It is essentially a 10 foot grid. Some compositing of samples can be conducted. The guidance
is at 40 CFR 761 Subpart N. However, the use of this guidance is not specifically required and other
characterization sampling procedures, such as any characterization sampling guidance developed and
used by the RCRA, Superfund, or Brownfields programs can be used.
Notification and/or Application Requirements
For almost all PCB sites being cleaned up under the PCB regulations, a notification or application should
be submitted to the Region. Specifically, if a site is remediating the PCB contamination under the self-
implementing option or risk-based option identified below, a notification or application should be
submitted to the Region which includes the following 5 elements (see 40 CFR 761.61 (a)(3)):
A) Description of the nature of contamination (soils, concrete, etc.);
B) Summary of characterization sampling procedures and results;
C) Map showing location and extent of contamination with sample sites noted;
D) Cleanup and disposal plan;
E) Certification on location of sampling information;
In addition to the above information, if a risk assessment is being used to determine the cleanup levels at
a site, the risk-assessment or any other information needed to demonstrate that there is no unreasonable
risk from the PCBs should also be submitted to the Region.
Part 2: Remedial Decision Phase
There are several options for remediating PCBs in accordance with the Federal PCB regulations: self-
implementing, performance based disposal, risk-based, coordinated approval (see, respectively
761.61 (a), 761.61 (b), and 761.61 (c), and 761.77). These options are discussed below, in order of what is
most likely to be used, not in order of when they appear in the regulations.
Self-implementing On-site Cleanup and Disposal of PCB Remediation Waste
PCBs may be remediated following specific cleanup, sampling, disposal, and control methods in
accordance with the PCB regulations for the self-implementing on-site cleanup and disposal of PCB
remediation waste. Self-implementing remediation of PCBs can be considered as an "approval by Rule",
since if the specific requirements are followed, a written approval is not required.
For self-implementing PCB remediation, a notification must be submitted to the Region which includes
the information specified in the 5 elements listed above. The notification must be submitted at least 30
days before remediation is to begin. Thirty (30) days after submitting the notification, if it is considered
complete, the responsible party may consider it approved.
The actual remediation is based on future occupancy of the area with the PCB contamination. If the area
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is going to be occupied for 6.7 hours or more per week, it is considered a high-occupancy area. If the
area is going to be occupied for less than 6.7 hours per week, it is a low-occupancy area.
For high occupancy areas, the responsible party has two options: 1) cleanup all the PCBs to 1 ppm, or 2)
cleanup all the PCBs to 10 ppm and cover the PCBs with a cap. A notice to the deed is required if the
option of cleaning to 10 ppm and covering with a cap is used.
For low occupancy areas, the responsible party has three options: 1) cleanup all the PCBs to 25 ppm; 2)
cleanup all the PCBs to 50 ppm and place a fence around and mark the PCB area; or 3) cleanup all the
PCBs to 100 ppm and cover the PCBs with a cap. A notice to the deed is required if any of the low
occupancy area options are used.
Specific verification sampling procedures must be followed (see 40 CFR 761 Subpart O). In summary, it
involves the use of a 5 foot grid. Compositing up to 9 samples is allowed.
Non-liquid remediation waste with any concentration of PCBs may be sent to a hazardous waste (RCRA
C) landfill and non-liquid remediation waste with less than 50 ppm PCBs may be sent to a municipal or
non-municipal non-hazardous waste (RCRA D) landfill.
The self-implementing remediation of PCBs does not apply to sites where the PCB contamination is in
sediments, groundwaters or surface waters, grazing lands, or vegetable gardens, sewers, or drinking
water source or distribution systems. If the PCB contamination is in any of these situations, the PCBs
must be remediated following the risk-based approval or performance-based disposal options described
below.
Risk-based Disposal Approval
If a proposal to cleanup, sample, dispose, or store PCB remediation waste is not provided for in other
parts of the PCB regulations, such as the regulations for self-implementing remediation of PCBs (as
described above), the activity may be approved if the responsible party demonstrates that it does not
present an unreasonable risk to human health or the environment. Such approvals are referred to as
risk-based approvals and are provided for in the PCB regulations at 40 CFR 761.61 (c).
The demonstration that an activity does not present an unreasonable risk is similar to and essentially the
same as the process followed by the RCRA program. The responsible party can eliminate the potential
for exposure by removing the PCBs to a level that does not present an unreasonable risk; or alternatively,
reduce the potential for exposure by using engineering and institutional controls.
An application or work plan fora risk-based disposal approval must be submitted and must include, at a
minimum, the information specified above under Notification and/or Application Requirements. It
must also include any addition information needed to demonstrate that the planned approach to
remediate the PCBs will not present an unreasonable risk. The procedures in the Risk Management
Strategy that are normally used by the RCRA program to evaluate risk may also be used to demonstrate
that the PCBs will not present an unreasonable risk.
The approvals must be issued in writing and be signed by the Division Director of WPTD. The authority
to issue TSCA risk-based disposal approvals has been delegated to the WPTD Division Director. So, a
RCRA corrective action document signed by the WPTD Division Director may also be considered a TSCA
risk-based approval. The approval document should specify the PCB activity being approved (cleanup,
sampling, disposal, storage), include any conditions needed for that activity, and note that the document
is a TSCA risk-based approval in accordance with 40 CFR 761.61 (c).
Coordinated Approval
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The PCB regulations also provide an option for the remediation of PCBs to be considered satisfied if the
remediation was conducted in accordance with a decision document, such as a permit or consent order
or agreement, issued by EPA, including by RCRA, which addresses the remediation of PCBs. If such a
document has been issued, a written TSCA Coordinated Approval may be issued and will satisfy
requirements of the Federal PCB regulations for remediation of the PCBs. The written TSCA
Coordinated Approval may simply be a letter signed by the WPTD Division Director, which references the
PCB remediation requirements in the decision document.
In evaluating the actual requirements to remediate the site, the cleanup objectives established by the
RCRA program, for instance, using the procedures in Section 3 and Section 4 of this Risk Management
Strategy, may also be acceptable for the remediation of PCBs.
For a TSCA Coordinated Approval for the remediation of PCBs, the responsible party must submit the
following information:
• A request for a coordinated approval;
• The name, organization, and telephone number of the contact person for the RCRA waste
management authority;
• A copy of the relevant waste management document (if the Region does not already have a copy of
the document);
• And a certificate that the person(s) who owns the site is aware of and will adhere to any applicable
PCB record keeping and reporting requirements.
Performance-based Disposal
A responsible party may also remediate all the PCBs at the site without obtaining any approval from the
Region. If a responsible party remediates all the PCB contamination at the site down to a concentration
of 1 ppm, and disposes of the remediation waste and cleanup material as regulated PCB waste in an
approved PCB incinerator or PCB landfill, no notification or application needs to be submitted to EPA,
and no approval needs to be obtained from EPA under the PCB regulations. The remediation and
disposal of PCBs following these requirements is known as performance-based disposal [40 CFR
761.61(b)].
ATTACHMENT 2:
Region 5 RCRA program policy on the use of occupational standards for evaluating
concentrations of chemical constituents in indoor air
The following outlines the current Region 5 RCRA policy for recognizing OSHA compliance limits as risk-
based screening concentrations for indoor air. This policy will apply unless and until the U.S. EPA
announces an Agency-wide policy on how OSHA compliance should be applied to RCRA corrective
action projects.
1. For Environmental Indicator determinations (i.e., CA 725 - Current Human Exposures Under Control
and CA 750 - Migration of Contaminated Groundwater Under Control), the Region 5 RCRA program
will recognize the use of OSHA Permissible Exposure Limits (PELs) as appropriate health based
screening levels for indoor air within on-site industrial buildings. This recognition will apply to buildings
under the direct control of the Responsible Party (RP) (owner/operator). This recognition is based on
a policy adopted by the Office of Solid Waste at EPA Headquarters. If the site also contains a
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building(s) which is not obviously industrial (e.g., cafeteria, day-care center, commercial space) or not
obviously under the control of the RP, then Region 5 may request the RP to provide evidence that the
building(s) is regulated under OSHA for the contaminants of concern.
2. For site remedial decisions beyond the El determinations (e.g., RFI determinations; CMS
requirements; Statement of Basis), OSHA PELs will not be recognized as the appropriate health
based screening levels for indoor air within any on-site industrial buildings. EPA's risk-based
screening levels for exposure to air contaminants will be applied according to the document titled:
"DRAFT GUIDANCE FOR EVALUATING THE VAPOR INTRUSION TO INDOOR AIR PATHWAY
FROM GROUNDWATER AND SOILS" (http://www.epa.gov/correctiveaction/eis/vapor/complete.pdf).
The RP may apply this guidance to demonstrate that vapor intrusion to indoor air is not a complete
exposure pathway for an on-site building(s). If vapor intrusion of all applicable contaminants cannot
be eliminated as a pathway of concern by the screening procedures recommended in the guidance,
then additional work to address the pathway will be required.
3. For off-site buildings (i.e., buildings not under control of the RP), OSHA PEL values will not be
recognized as appropriate health based screening levels for indoor air for El determinations or for
subsequent remedial decisions. EPA's risk-based screening levels for exposure to air contaminants
will be applied according to the guidance given above. However, the RP may apply this guidance in
an effort to demonstrate that vapor intrusion to indoor air at the off-site building(s) or location(s) in
question is not a complete exposure pathway. If vapor intrusion cannot be eliminated as a pathway of
concern by the screening procedures recommended in the guidance, then additional work to address
the pathway will be required.
ATTACHMENT 3:
EPA's Expectations for Final Corrective Action Remedies
These expectations were taken from the May 1, 1996, Advance Notice of Proposed Rulemaking (ANPR)
(61 FR 19432). Many of these expectations were first articulated in the discussion of remedy selection at
CERCLA sites in the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) (40 CFR
430(a)(1)). CERCLA and RCRA corrective action criteria address the same types of considerations and
should generally result in similar remedies when applied to similar site-specific conditions.
1. EPA expects to use treatment to address the principal threats posed by a site whenever practicable
and cost effective4. Contamination that represents principal threats for which treatment is most likely
4
The term "cost-effective" does not necessarily mean least costly.
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to be appropriate includes contamination that is highly toxic, is highly mobile, or cannot be reliably
contained, and that would present a significant risk to human health and the environment should
exposure occur.
Helpful References:
A Guide to Principal Threat and Low Level Wastes (OSWER Directive 9380.3-06FS, November
1991)
The Role of Cost in the Superfund Remedy Selection Process (EPA 540/F-96/018, September
1996)
2. EPA expects to return usable groundwaters to their maximum beneficial uses wherever practicable,
within a time frame that is reasonable given the particular circumstances of the site. When restoration
of groundwater is not practicable, EPA expects to prevent or minimize further migration of the plume,
prevent exposure to the contaminated groundwater and evaluate further risk reduction. EPA also
expects to control or eliminate surface and subsurface sources or effects of groundwater
contamination.
Helpful References:
Region 5 RCRA Subtitle C Corrective Action Risk Assessment Guidance (1998)
Corrective Action for Releases from Hazardous Waste Management Units; Proposed Rule
(Federal Register, May 1, 1996)
Guidance for Evaluating the Technical Impracticability for Ground-Water Restoration,
(Directive 9234.2-25, September, 1993).
3. EPA expects to use engineering controls, such as containment, for wastes and contaminated media
which can be reliably contained, pose relatively low long-term threats, or for which treatment is
impracticable.
4. EPA expects to use a combination of methods (e.g., treatment, engineering and institutional controls),
as appropriate, to achieve protection of human health and the environment.
5. EPA expects to use institutional controls such as groundwater and land use restrictions primarily to
supplement engineering controls as appropriate for short- and long-term management to prevent or
limit exposure to hazardous wastes and constituents. EPA does not expect that institutional controls
will often be the sole remedial action.
6. EPA expects to consider using innovative technology when such technology offers the potential for
comparable or superior treatment performance or implementability, less adverse impact, or lower
costs for acceptable levels of performance when compared to more conventional technologies.
7. EPA expects to remediate contaminated soils as necessary to prevent or limit direct exposure of
human and environmental receptors and prevent the transfer of unacceptable concentrations of
contaminants (e.g., via leaching, runoff or airborne emissions) from soils and subsurface soils to other
media.
With regard to media cleanup standards, EPA's risk reduction goal is to reduce the threat from
carcinogenic contaminants such that for any medium, the excess risk of cancer to an individual would be
between 10"6 to 10"4. For non-carcinogens, the hazard index should generally not exceed 1. EPA's
preference is to select remedies that are at the more protective end of the risk range. Therefore, 10~6
should be used as the point of departure when determining site-specific cleanup standards. Final
cleanup standards should consider factors such as exposure frequency, receptor or ecosystem
sensitivity, uncertainty, or technical limitations.
Remedy Selection Criteria
The 1996 ANPR reaffirmed the appropriateness of the remedy selection criteria proposed in 1990. (61 FR
19449, May 1, 1996). A summary of the remedy selection criteria is included in this section along with
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references that provide additional information. Another helpful reference is the National Contingency
Plan. RCRA and CERCLA remedy selection criteria are similar and the National Contingency Plan and
its preamble explain the criteria in greater detail.
Remedies will be evaluated in two phases. During the first phase, potential remedies are screened
against the following threshold criteria. Remedies must:
3. Protect human health and the environment.
4. Attain media cleanup standards (e.g., state cleanup standards)
5. Control the source(s) of releases so as to reduce or eliminate, to the extent practicable, further
releases of hazardous wastes (including hazardous constituents) that might pose threats to human
health and the environment.
6. Comply with applicable standards for waste management (e.g. Clean Air Act & Clean Water Act
emissions limitations, hazardous waste storage & transportation regulations, etc.)
Balancing Criteria
Remedies that meet the threshold criteria are then compared to the following balancing criteria:
1. Long term reliability and effectiveness. This pertains to the risk remaining at the facility after
completion of a remedial action. It considers:
(a) the level of threat posed by hazardous constituents remaining in place and the adequacy and
reliability of any engineering or institutional controls to manage those risks, and
(b) the risk associated with treatment residuals compared to the risk associated with untreated
waste.
2. Reduction of toxicity, mobility, or volume of wastes. This pertains to the preference for
remedies which, wherever practicable, involve treatment that permanently and significantly
reduce the toxicity, mobility, or volume of wastes that pose principal threats. (See also: "A
Guide to Principal Threat and Low Level Wastes" (OSWER Directive 9380.3-06FS, November
1991)
1. Short-term effectiveness. This criterion evaluates the effects of the remedial alternatives on
human health and the environment during their implementation. It considers factors such as:
(b) dust from excavation
(c) transportation of hazardous materials
(d) air quality impacts
(e) potential impacts to the environment from remedy construction and implementation and the
reliability of mitigation measures to prevent or reduce impacts.
4. Implementability. This addresses the technical and administrative feasibility of implementing
an alternative and the availability of services and materials.
5. Cost. Cost effectiveness is determined by comparing the costs and overall effectiveness of
alternatives to determine whether the costs are proportional to the effectiveness achieved. Criteria
used to evaluate cost effectiveness include long-term effectiveness and permanence, reduction of
toxicity, mobility, or volume through treatment, and short-term effectiveness. CSee also: The Role
of Cost in the Superfund Remedy Selection Process (EPA 540-F-96-018, September 1996)
6. Community acceptance. EPA encourages public involvement activities beyond the formal
requirements found in the regulations, especially when it fosters an early and open dialogue with
potentially affected parties. Efforts should be taken to involve interested parties in activities
throughout the corrective action process, instead of only at junctures specified in the regulations.
Public participation can also be very beneficial when provided at the initiation of corrective action,
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the selection of significant interim measures (as appropriate), prior to remedy proposal, and at the
completion of corrective action. (See also: RCRA Public Involvement Manual, EPA530-R-93-006,
September 1993)
7. State acceptance. State acceptance of the proposed action should be a very important
consideration in EPA's actions. Frequent coordination with State agencies that have an
interest in the action is highly recommended.
EXHIBIT 1: Performing risk-based screening of surface soil data
(Refer to Chapter 4; Sec 1.10)
The following is a general procedure for conducting the risk-based screening of surface soil sampling
data.
1) Set your Internet browser to:
Open the Web site titled: "Region 9: Superfund - Preliminary Remediation Goals"
Bullet links #1- #4 contains very useful background information on PRG values and how they are
calculated.
2) To view the chemical-specific PRG values for surface soil screening, scroll down the home page and
open the bullet link titled:
Soil Calculations. This is a Table of PRG values for the Residential Land Use and Industrial Land Use
scenarios. The PRG values have soil concentration units (i.e., mg/kg).
3) For each chemical constituent of interest, the PRG values should be located from the following
columns:
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RESIDENTIAL SOIL
Cancer Risk = 1E-06 Chronic HQ = 1
combined combined
INDUSTRIAL SOIL
Cancer Risk = 1E-06 Chronic HQ = 1
combined combined
For example, for the chemical Aldrin, the corresponding values are:
RESIDENTIAL SOIL
Cancer Risk = 1E-06 Chronic HQ = 1
combined combined
2.9E-02 mg/kg 1.8E+00 mg/kg
INDUSTRIAL SOIL
Cancer Risk = 1E-06 Chronic HQ = 1
combined combined
1.0E-01 mg/kg 1.8E+01 mg/kg
(NOTE: Some chemicals do not have listed Cancer Risk PRG values; and some chemicals do not have
listed HQ = 1 PRG values)
4) To calculate the PRG value corresponding to a Cancer Risk = 1E-04, multiply the PRG value for
Cancer Risk = 1E-06 by a factor of 100
For example, for the chemical Aldrin, the corresponding PRG values for Cancer Risk = 1E-04 are:
RESIDENTIAL SOIL
Cancer Risk = 1 E-04 is: 2.9E-02 mg/kg x 100= 2.9E+00 mg/kg
INDUSTRIAL SOIL
Cancer Risk = 1 E-04 is: 1.0E-01 mg/kg x 100= 1.0E+01 mg/kg
5) Collect all the sample analytical data for surface soil at each SWMU or AOC that is ready for
screening. Label each SWMU/AOC with a simple letter/number combination (e.g., S01, S02 , A01, A02,
etc.) Find and flag the maximum detected concentration (MAX) of each chemical constituent in each
SWMU/AOC.
6) Start comparing the MAX concentration of each chemical constituent to its corresponding PRG values
(as identified in Step #3 and Step #4 above) to determine the risk ranking of the chemical. For example,
suppose the MAX concentration of Aldrin at a SWMU is 2.1 mg/kg. For the Residential Use scenario, this
means that the MAX concentration is higher than the Cancer Risk = 1 E-06 PRG (2.9E-02 mg/kg) but
lower than the Cancer Risk = 1E-04 PRG (2.9E+00 mg/kg). The MAX concentration is also greater than
the HQ =1 PRG (1.8E+00 mg/kg).
7) Calculate the "Screening Level Cancer Risk" and the "Screening Level HQ" corresponding to the MAX
concentration. These values are calculated as follows:
Screening Level Cancer Risk = [(MAX) •*• (PRG for Cancer Risk of 1 E-04) ] x (1E-04)
For example, for the Aldrin case cited in Step #6 above:
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Screening Level Cancer Risk = [(2.1 mg/kg) •*• (2.9 mg/kg) ] x (1E-04)= 7.2E-05
Screening Level HQ = (MAX) + (PRG for HQ = 1)
For example, for the Aldrin case cited in Step #6 above:
Screening Level HQ = (2.1 mg/kg) •*• (1.8 mg/kg) = 1.2
8) If the SWMU/AOC contains additional chemical constituents for screening, repeat Step #3 through
Step #7 above for each chemical.
9) Then calculate a "Cumulative Screening Level Cancer Risk" by summing all the Screening Level
Cancer Risk values for each chemical constituent; and calculate a "Cumulative Screening Level HQ"
by summing all the Screening Level HQ values for each chemical constituent.
To obtain additional assistance with risk-based screening, contact a human health risk assessment
specialist from the WPTD-RCRA program.
EXHIBIT 2: Performing risk-based screening of groundwater and surface water data
(Refer to Chapter 4; Sec 1.10)
The following is a general procedure for conducting the risk-based screening of groundwater/surface
water sampling data.
1) Set your Internet browser to: < http://www.epa.gov/region09/waste/sfund/prg/index.htm >
Open the Web site titled: "Region 9: Superfund - Preliminary Remediation Goals"
Bullet links #1- #4 contains very useful background information on PRG values and how they are
calculated.
2) To view the chemical-specific PRG values for groundwater and surface water screening, scroll down
the home page and open the bullet link titled:
Air - Water Calculations. This is a Table of PRG values for the Residential Use of groundwater or
surface water. The PRG values have water concentration units (i.e., ug/Liter).
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3) For each chemical constituent of interest, the PRG values should be located from the following
columns:
TAP WATER
Cancer Risk = 1E-06 Chronic HQ = 1
combined combined
For example, for the chemical Aldrin, the corresponding values are:
TAP WATER
Cancer Risk = 1E-06 Chronic HQ = 1
combined combined
4.0E-03ug/L 1.1E+OOug/L
(NOTE: Some chemicals do not have a listed Cancer Risk PRG value; and some chemicals do not
have a listed HQ = 1 PRG value)
4) To calculate the PRG value corresponding to a Cancer Risk = 1E-04, multiply the PRG value for
Cancer Risk = 1E-06 by a factor of 100
For example, for the chemical Aldrin, the corresponding PRG value for Cancer Risk = 1 E-04 is:
TAP WATER
Cancer Risk =1 E-04 is: 4.0E-03 ug/L x 100 = 4.0E-01 ug/L
5) Collect all the sample analytical data for groundwater or surface water at each SWMU or AOC that is
ready for screening. Label each SWMU/AOC with a simple letter/number combination (e.g., S01,
S02, A01, A02, etc.) Find and flag the maximum detected concentration (MAX) of each chemical
constituent in each SWMU/AOC.
6) Start comparing the MAX concentration of each chemical constituent to its corresponding PRG values
(as identified in Step #3 and Step #4 above) to determine the risk ranking of the chemical. For
example, suppose the MAX groundwater concentration of Aldrin at a SWMU is 6.0E-01 ug/L. This
means that the MAX concentration is higher than the Cancer Risk = 1 E-06 PRG (4.0E-03 ug/L) and
higher than the Cancer Risk = 1 E-04 PRG (4.0E-01 ug/L). The MAX concentration is lower than the
HQ=1 PRG (1.1E+00 ug/L).
7) Calculate the "Screening Level Cancer Risk" and the "Screening Level HQ" corresponding to the MAX
concentration. These values are calculated as follows:
Screening Level Cancer Risk = [(MAX) •*• (PRG for Cancer Risk of 1 E-04) ] x (1E-04)
For example, for the Aldrin case cited in Step #6 above:
Screening Level Cancer Risk = [(6.0E-01 ug/L)- (4.0E-01 ug/L)] x (1E-04)= 1.5E-04
Screening Level HQ = (MAX) * (PRG for HQ = 1)
For example, for the Aldrin case cited in Step #6 above:
Screening Level HQ = (6.0E-01 ug/L) * (1.1E+00 ug/L) = 0.6
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8) If the SWMU/AOC contains additional chemical constituents for screening, repeat Steps #3 through #7
above for each chemical.
9) Then calculate a "Cumulative Screening Level Cancer Risk" by summing all the Screening Level
Cancer Risk values for each chemical constituent; and calculate a "Cumulative Screening Level HQ"
by summing all the Screening Level HQ values for each chemical constituent.
10) To screen the groundwater and surface data against EPA's Maximum Contaminant Levels (MCLs),
set your Internet browser to:
< http://www.epa.gov/safewater/mcl.htmltfmcls >
Open the web site titled: "List of Drinking Water Contaminants & MCLs"
11) Locate each chemical in your data set which has a listed MCL value (Note: only about 45
chemicals commonly detected at Superfund or RCRA sites have a published MCL value.)
12) Compare the MAX concentration of each chemical constituent with its corresponding MCL value to
determine if the MAX concentration exceeds the MCL. (Note: MCL values on the web site are
listed in units of mg/L. To convert to ug/L, multiply the listed value by a factor of 1000.)
To obtain additional assistance with risk-based screening, contact a human health risk assessment
specialist from the WPTD-RCRA program.
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