9355.4-16^
PB95-963531
EPA540/R-94/105
DRAFT SOIL SCREENING GUIDANCE; ISSUES DOCUMENT
I. Introduction
A. Background
B. Technical Changes
C. Supporting Efforts
II. Use of SSLs in the Remedial Investigation/Feasibility Study
A. Background
B. New Data Elements Required
C. Multiple Contaminants
D. Risk Communication
E. Ecological Risk
F. ARARs
III. Relationship to Other Federal Programs
A. Site Assessment
B. Removal
C. RCRA
IV. Relationship to Non-Federal Programs
A. Background
B. Relationship to ASTM
C. State and Voluntary Cleanup
D. Brownfields and Environmental Justice
I. introduction
A. Background
This document contains the substantive discussion of various
issues surrounding the application of the Draft Soil Screening
Guidance. Supporting the Fact Sheet which presents this guidance
are the Technical Background Document and this Issues Document.
The draft guidance has been developed as a tool to screen out
areas of certain Superfund sites from further assessment based on
soil contamination levels, thus narrowing the scope of such
assessments and expediting their completion.
The U. S. Environmental Protection Agency (EPA) responds to
releases of hazardous substances under the authority of the
Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA) as amended, commonly known as Superfund.
Regulations governing the response to hazardous substances are
contained in the National Oil and Hazardous Substances
Contingency Plan (NCP). The NCP generally requires that
contaminants of concern be identified at National Priorities List
(NPL) sites during the Remedial Investigation (RI) of a site
where hazardous substances have been released. As part of this
process the EPA assesses the risk posed by that contamination,
including the more common exposure pathways for soil
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contamination such as direct ingestion, inhalation and leaching
to groundwater. The "Risk Assessment Guidance for Superfund"
(RAGS) ' and the Standard Default Exposure Factors (OSWER
Directive # 9285.6-03) provide-the user with the parameters and
procedures most commonly used in this analysis. These parameters
and procedures form the basis of the risk-based Draft Soil
Screening Guidance.
While the RAGs document has been in use for several years by
EPA, its incorporation into the Draft Soil Screening Guidance
marks the first time EPA has presented the risk-based formulae
contained in RAGS in the form of a screening tool. In the course
of performing risk assessments, the use of EPA's toxicity
information has been widely accepted. This toxicity information
is contained in: the Integrated Risk Information System (IRIS);
and in the Health Effects Assessment Summary Tables (HEAST).
Further, EPA has gained considerable experience in quantifying
risks associated with contaminated soil. One of the lessons EPA
has learned is that some common exposure pathways can be
r^ generically modeled and represent most of the risk associated
^ with soil contamination at some sites. Based on this information,
Y the Draft Soil Screening Guidance lays out specific procedures
which may be used to compare soil contaminant levels to risk-
''; based values. Areas of a site which fall below such levels may
N be screened out from further assessment, while areas above the
SSL values must undergo further assessment. Particularly at
„ large NPL sites, it is expected that the Draft Soil Screening
\; Guidance will enable EPA to screen out areas of a site from
~^ further study of the soil contamination during the Remedial
Investigation, thus narrowing its scope and expediting its
completion.
On August 19, 1993, EPA's Office of Emergency and Remedial
Response (OERR) requested comment from many different groups on a
draft fact sheet entitled: "Interim Soil Screening Level
Guidance." This guidance discussed the development and use of
risk-based soil screening levels (SSLs) for 30 common Superfund
soil contaminants. Subsequently, a second "working draft" was
issued on September 30, 1993, to provide the basis for discussion
of the SSL project with stakeholders. Efforts to develop such a
guidance were requested under both the EPA Administrator's June
19, 1991, "30-Day Study," and the more recent Superfund
Administrative Improvements Initiatives announced by the Deputy
Administrator on June 23, 1993. A revised draft reflecting some
of the comments from the first review was issued September 30,
1993.
In July, 1994 a revised draft entitled "Draft Guidance for
Soil Screening Level Framework" and a revised Technical
Background Document were circulated for internal EPA review and
to key State participants. EPA received comment on the changes
made to reflect both technical and policy issues identified
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during numerous outreach activities from October of 1993 through
July of 1994. This latest round of comments has been
incorporated into the Draft Soil Screening Level Guidance,
noticed in the Federal Register, and available for public
comment.
It is important to avoid the misuse of "draft" numbers prior
to the EPA's further consideration of key technical and policy
issues. EPA is therefore limiting application of the Draft Soil
Screening Guidance to pilot projects at select Superfund National
Priorities List (NPL) sites, until the guidance is finalized.
For similar reasons, this guidance is not yet intended to be
applied at sites subject to Resource Conservation and Recovery
Act (RCRA) Corrective Action authority. However, EPA expects
that final SSL guidance will be used to update the "action level"
concept that was part of the proposed Subpart S Corrective Action
regulation (55 Federal Register 30798). This issue will be
examined in the context of developing that final regulation. As
described below, OERR is considering the value or impact of the
guidance on other phases of Superfund cleanup, and on other
Agency or State programs.
As many reviewers recognized, this guidance requires a
strong technical foundation. In addition, this guidance has many
practical and policy implications for Superfund and other
Federal, State, and local organizations. For these reasons, EPA
has pursued an aggressive program of technical analyses, review,
and outreach to address the wide range of issues over the past
year. This outreach activity is now culminating in a public
comment period and concurrent scientific peer review.
B. Technical Changes
Since the September 1993 interim draft, internal and
stakeholder review has resulted in several changes which are now
reflected in the Draft Soil Screening Guidance:
o The emphasis of the guidance has shifted from the generic
values to a soil screening framework, which has as its
primary focus a simple site-specific method for calculating
SSLs. This methodology uses some site measured values,
along with default assumptions to calculate SSLs. Under the
framework, generic SSLs may be sufficient in certain
situations and have been retained as one option. For other
more complex situations, detailed site-specific study is
warranted.
o Approximately 70 additional SSLs have been developed using
the same methods, adjusted to reflect those comments or
concerns raised by Agency staff, outside groups, or
technical peer review. There are now a total of 107
contaminants in the list of generic soil screening levels.
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Migration to Groundwater Pathway: The September 1993 draft
included two methods for calculating simple site-specific
SSL values which were distinguished by different techniques
for estimating leachate composition to assess potential
migration to ground water. One method used a partitioning
equation and the other used a leach test. These two options
are now both included in the simple site-specific method
because analysis indicates that the difference in the level
of conservatism between them is minimal. The leach test may
be more appropriate in some instances, depending on the
contaminants and site conditions, while in other situations,
inserting site-specific information into the partitioning
equation is more appropriate. EPA has attempted to provide
guidance on which is the more appropriate method to use for
individual applications of the SSL framework.
Inhalation Pathway: Dispersion for the inhalation of
volatiles and fugitive dusts will be modeled using an
updated dispersion model (AREA-ST, the updated version of
the Office of Air Quality Planning and Standards, Industrial
Source Complex Model, ISC2). Instead of using an average
for meteorological data, a set will be used that represents
"high-end" conditions. The saturation equation (Csat) has
been revised to correct for previous "double counting" of
the soil moisture content and a lower organic carbon content
is proposed (0.6%). Csat has also been modified to deal with
chemicals which are solids at room temperature. In addition
to the generic numbers, a simple site-specific approach to
inhalation is also proposed, which includes options for
source size variation and regional meteorological data.
Contaminant Distribution: The discussion in the Technical
Background Document (TBD) for the guidance has been changed
to presume that contaminants are distributed lognormally
when applying the soil screening guidance at a Superfund
site.
Approach to Sampling: Also included in this revised
version of the draft guidance is an approach to sampling
which dovetails with the Data Quality Objectives (DQO)
process. While the September 30, 1993, draft guidance had
loosely incorporated steps one through five of the DQO
process (as outlined in the September 1993 Interim Final
Data Quality Objectives Process for Superfund), this version
is more explicit in its use of the DQO process. In addition
to the prescriptive strategy outlined in the September 1993
draft guidance, this version includes a site-specific
sampling strategy based on statistical concepts. The draft
guidance now defines limits on uncertainty and the
relationship between sample size formulae, and it controls
limits on decision error. EPA invites comment on the use
of the DQO process and the site-specific sampling approach.
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C. Supporting Efforts
Other supporting efforts undertaken to bolster the technical
foundation of the guidance, clearly communicate its purpose, and
obtain feedback include:
o Completion of the Technical Background Document (TBD),
available in the Superfund docket and through NTIS, that
details the models, assumptions and rationale used in
preparation of the Draft Guidance;
o Consultation with EPA's Science Advisory Board on migration
to ground water issues;
o Detailed discussions with EPA Regional and Headquarters
offices, as well as other Federal agencies;
o A series of meetings with State representatives, organized
through the Association of State and Territorial Solid Waste
Management Officials (ASTSWMO); and,
o Additional meetings with outside stakeholders including
industry, environmental, and community groups, as well as
lenders, insurers and environmental auditors.
The Federal Register Notice seeks public comment on the
Draft Soil Screening Guidance. While EPA may not directly
respond to each and every public comment, as it would in a
rulemaking, the next steps are to review public comments on the
approach and, where appropriate, incorporate them into the
guidance. Publication of the draft guidance in the Federal
Register should not be construed as a rulemaking and the SSL
values should not be mistaken as "standards." Rather, EPA seeks
to solicit comments from the widest range of interested parties
possible. In addition, the technical foundation of the guidance
will undergo scientific peer review concurrent with the public
comment period.
EPA looks forward to receiving written comments on this
draft of the guidance. This document has already enjoyed the
benefits of considerable input, and broad public comment and
technical peer review will improve it even further. EPA believes
the promise this tool holds for accelerating decision making at
Superfund sites and potentially in other programs is sufficiently
great to warrant such efforts. Please contact the following
individuals with any questions or comments on specific sections
of this guidance: David Cooper (general issues, 703-603-8763) ;
Loren Henning (ground water, 703-603-8776) ; Janine Dinan (direct
contact pathways, 703-603-8824); Sherri Gill (sampling, 703-603-
9043).
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II. Use of SSLs in the Remedial Investigation / Feasibility Study
A. Background
The Draft Soil Screening Guidance was explicitly crafted for
use on sites which have been placed on EPA's National Priorities
List (NPL). The use of the guidance is intended to streamline and
expedite the Remedial Investigation process at NPL sites. While
there may be other parts of the Federal Superfund Program for.
which the guidance becomes useful, the current and primary focus
is on the Remedial Investigation and Feasibility Study of an NPL
site, with other potential applications to be pursued at some
future time.
The Draft Soil Screening Guidance is intended to be used,
where appropriate, to screen out areas of an NPL site where
further investigation is not warranted. The generic levels which
have been calculated and placed in Appendix A of the Draft Soil
Screening Guidance Fact Sheet for 107 chemicals use conservative
values for site soil characteristics in order to be protective
for Superfund sites across the country. The Agency recognizes
that this results in low screening levels, especially where
inhalation or leaching to groundwater are the pathways of
concern. For this reason, the emphasis of the guidance has
shifted from the generic levels to a soil screening framework,
which has as its primary focus a simple site-specific method.
The Draft Soil Screening Guidance contains a framework with
three methods to develop soil screening levels: generic levels
(from a table); the simple site-specific approach (the preferred
method); and the detailed site-specific method. Under the
framework, use of generic soil screening levels (SSLs) has been
retained as one option for certain situations where these
conservative values would be sufficient and more cost-effective
to apply. The simple site-specific method combines some site-
measured values and default assumptions to calculate screening
levels appropriate to an individual site. For other more complex
situations, a third option, detailed site-specific study, may be
warranted. In general, however, EPA believes the simple site-
specific method will provide the best balance between the costs
of investigating site-specific soil conditions and the level of
conservatism in the screening levels.
As the result of previous outreach activities several issues have
arisen regarding the application of the SSLs at NPL sites. Below
are responses to the most frequently asked questions.
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B. New Data Elements Required
Issue: Some reviewers of the September 30, 1993, Fact Sheet:
"Interim Soil Screening Level Guidance," commented that the site-
specific soil information required by the simple site-specific
method (then called "Tier 2) has not typically been collected or
evaluated as part of the RI in the past at Superfund sites. This
information may not be easily collected and analyzed for, and may
increase study costs.
Response: It is true that some site-specific soil information
required to calculate site-specific screening levels has not been
consistently collected for past Ris. For example, the simple
site-specific method would require, for the first time,
collection of information on soil porosity and water content, in
order to calculate air filled porosity to establish site-specific
soil screening levels. EPA's experience, however, indicates that
this information is important for estimating movement of
contaminants in soil and will be relatively cheap and easy to
obtain during the RI. Moreover, it is the kind of information
that would be necessary to conduct a more detailed site-specific
evaluation of the site and is more often collected during the
remedial action phase.
C. Multiple Contaminants
Issue: The soil screening guidance applies to individual
contaminants. How are risks from multiple contaminants taken
into account?
Response: For noncarcinogens, the fact sheet provides a method
of apportionment for groups of chemicals which affect the same
target organ.
For carcinogens, the generic soil screening values for
individual chemicals are back-calculated so that a risk of one in
one million (1X10 ) will not be exceeded in a residential
exposure. This risk level is at the low end of EPA's acceptable
risk range for Superfund of one in one million to one in ten
thousand (1X10 to 1X10" ) individual excess cancer cases. EPA
has analyzed typical combinations of soil screening levels and
feels confident that very few sites would pose cumulative risks
outside the risk range if each individual contaminant were at or
below its generic SSL.
For soil screening levels based on the migration to ground
water pathway which are derived from Maximum Contaminant Levels
(MCLs), some risk levels may be near the middle of EPA's risk
range. Since the back calculation itself contains conservative
assumptions about contaminant migration, however, EPA believes
very few multiple contaminant sites would actually exceed
Superfund's acceptable risk range.
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D. Risk Communication
Issue: Many reviewers of the Draft Soil Screening Guidance
have expressed their view that clear, straightforward risk
communication needs to occur at Superfund sites. During the
Remedial Investigation the assessment and management of risk need
to be explained to the affected community.
Response: The development of the Draft Soil Screening Guidance
provides an additional opportunity for the Agency to effectively
communicate the Superfund program's risk assessment process. EPA
is, therefore, considering development of a shortened, simplified
version of the SSL Fact Sheet for use in community involvement
programs at Superfund sites. EPA intends that presentation of
the guidance to the public at Superfund sites use the most
effective risk communication techniques available.
E. Ecological Risk
Issue: Some reviewers commented that the soil screening guidance
has limited utility because it cannot be used when there are
ecological risks.
Response: For some pathways, such as ecological impacts,
standard formulae are not yet available to capture risk in a
generic, quantitative way. There is a similar problem regarding
dermal exposure and exposure through food crops. To initially
address these issues, EPA has included a discussion which
indicates some chemicals may require additional consideration for
terrestrial ecological impacts, dermal exposure or exposure from
the soil through plants. In addition, EPA is currently
developing guidance for ecological risk assessments at Superfund
sites which, when completed, would complement the soil screening
guidance.
F. ARARS
Issue: Reviewers have inquired about the relationship between
the soil screening guidance and the process for identifying and
meeting Applicable or Relevant and Appropriate Requirements
(ARARs) during the Superfund remedy selection process.
Response: The Draft Soil Screening Guidance has been written
mainly for use during the Remedial Investigation, to identify
contaminants and site areas of concern, before a remedial action
decision is evaluated in the Feasibility Study (FS) and
documented in the Record of Decision (ROD) for the site. In some
cases, SSLs may be used as Preliminary Remediation Goals (PRGs),
i.e. draft clean-up numbers, provided site circumstances match
the conceptual site model on which the SSLs were based, including
a residential land use. PRGs may be modified as the result of
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the FS analysis and remedy selection process in which nine
criteria are considered. Among these criteria are the statutory
requirement for remedies to meet the applicable or relevant and
appropriate requirements (ARARs) of other environmental laws.
Some of these standards may require more stringent cleanup levels
than the PRGs. Therefore, SSLs may provide a starting point for
the establishment of cleanup levels, provided certain conditions
are met, but they do not in any way supersede the statutory
requirement to meet ARARs in the remedial action.
III. Relationship to Other Federal Programs
A. Site Assessment
The primary distinction between the tools used in the site
assessment program and the soil screening guidance is that the
evaluation in site assessment is performed before data collection
for the RI/FS occurs, while the Draft Soil Screening Guidance is
proposed to be used after that data collection. The purpose of
the site assessment program is to evaluate a large number of
sites for eligibility to be nominated to the NPL. For this
program the tool used to evaluate sites is the Hazard Ranking
System (HRS) which has been promulgated as a Federal Regulation
in the National Contingency Plan. EPA does not intend to conduct
a rulemaking to change the HRS Rule at this time.
The Superfund site assessment program evaluates sites in a
large inventory of suspected problem areas to determine whether
they warrant attention as a national priority. Preliminary
assessments (PA) and site inspections (SI) are performed on sites
in the Comprehensive Environmental Response, Compensation, and
Liability Inventory System (CERCLIS). The sites are scored under
the HRS if they appear to pose serious threats, and sites which
score above 28.5 on the HRS are eligible for nomination to the
NPL.
Issue: Reviewers have inquired about the difference between how
decisions are made about contaminated soils in the site
assessment/NPL listing program and under the Draft Soil Screening
Guidance.
Response: There are a number of key differences in purpose and
scope between the Draft Soil Screening Guidance and the site
assessment and NPL listing processes. The guidance, for example,
only considers soils while the HRS considers surface water, air
and ground water in addition to the soil pathway. In addition,
SSLs address exposure to humans while the HRS addresses both
human exposure and exposure to sensitive environments. A major
difference between SSL guidance and the NPL listing process is
sampling. Because of the limited resources available to do Site
Inspections (Sis), the SI stage of site assessment is designed to
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obtain information on "worst case" or "hot spot" contamination.
The Draft Soil Screening Guidance, however, is designed to be
used in the RI to indicate average soil concentrations at the
site to determine whether "gray areas" are of concern or not.
EPA will evaluate what, if any, role the guidance, as well as a
variety of other tools, might play in setting priorities for
sites to enter site assessment. Finally, methods have been
developed to calculate multipliers in the soil pathway of the
HRS, and the risk levels used are identical to those used in the
guidance. EPA is currently exploring the need for further
consistency in the exposure assumptions between the HRS guidance
and the Draft Soil Screening Guidance. A more detailed
evaluation of the HRS soil exposure pathway in conjunction with
the SSL values is contained in the Superfund Docket in a report
entitled "Comparison of Draft Soil Screening Levels to
Contaminant Levels Used in the Site Assessment and Removal
Programs."
B. Removals
In the Superfund Removal program many factors are taken into
account in order to determine where and how to take actions,
which are generally short term, to reduce risks. In support of
the Draft Soil Screening Guidance, the Superfund Docket contains
a report entitled "Comparison of Draft Soil Screening Levels to
Contaminant Levels Used in the Site Assessment and Removal
Programs."
The Superfund Accelerated Cleanup Model (SACM) integrates
the removal and remedial authorities to initiate early actions on
the worst problems at sites. Such sites will also generally be
subject to longer-term cleanups, such as restoration of
groundwater. The establishment of cleanup levels, in both the
removal and remedial programs requires consideration of many
site-specific and program requirements, including: Applicable or
Relevant and Appropriate Requirements (ARARs), which differ from
State to State; risk assessment; and in some cases consultation
with the Agency for Toxic Substances and Disease Registry
(ATSDR). Since removal actions are generally performed to
achieve effective risk reduction in the short term, relative to
NPL remedial actions, only current land use is typically taken
into account.
Issue: What is the relationship between soil contaminant levels
where removals are performed and the soil screening tool in the
guidance for remedial investigations?
Response: EPA is just beginning to explore potential roles for
the soil screening tool in Superfund's removal program. It could
be argued that some very high level of soil contamination,
relative to the soil screening levels, could be used to indicate
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the need for a removal assessment to be performed. EPA is
evaluating the potential utility of such a tool to set priorities
for removal assessment, particularly as increasing numbers of
non-time critical removals are performed. More importantly,
several reviewers have commented that screening levels alone are
only one element of a total soil remediation program. In
response, EPA is evaluating the potential for developing high
concentration values (higher than the SSLs), that, when exceeded
in soil at a site, would indicate some sort of response action is
likely to be appropriate. Many believe that the combination of
the complementary tools of high and low soil concentration levels
(which would bracket the acceptable range in which site-specific
cleanup levels would fall) would accelerate decision-making far
more dramatically than would the availability of only one such
tool.
C. RCRA
The Resource Conservation and Recovery Act (RCRA) program
regulates the generation, treatment, storage, transportation and
disposal of hazardous waste. This program is administered by EPA
or by delegated States to issue permits and conduct enforcement
of the rules governing hazardous waste handling. In some cases,
contaminated soils must be addressed by corrective actions at
RCRA facilities which are similar to remedial actions at
Superfund sites.
Issue: What is the relationship between the RCRA program and the
soil screening guidance developed for Superfund?
Response: EPA is endeavoring to ensure consistency between the
Superfund and RCRA Corrective Action programs. This includes
conceptual agreement between the SSLs and numerical soil values
from multi-pathway risk analysis, which EPA's Office of Solid
Waste is developing as part of its re-proposal of the Hazardous
Waste Identification Rule (HWIR). EPA's RCRA/CERCLA Leadership
Team is overseeing the progress toward this consistency. EPA
will also be examining whether the approach outlined in this
guidance should be used to update the "action level" concept that
was part of the proposed Subpart S Corrective Action regulation
(55 Federal Register 30798). This issue will be examined in the
context of developing that final corrective action regulation.
IV. Relationship to Non-Federal Programs
A. Background
Some reviewers have commented on the value or impact of the
Draft Soil Screening Guidance on programs other than Superfund.
The American Society for Testing and Materials (ASTM) has had
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some experience in developing similar guidance which is risk-
based, and some States are considering the use of such ASTM
guidance, or have already developed their own criteria. While
the Draft Soil Screening Guidance is intended to be used as a
screening tool to determine if further study is warranted at a
site, it does not represent cleanup standards for a site. EPA is
concerned that no matter how well this important difference is
communidated, the numbers may be misused as automatic indicators
of "dirty" property. This problem could have negative effects on
attempts, for example, to redevelop "brownfield" properties that
have soil contamination above screening levels, but that may not
pose a risk given the intended use of the property.
The Draft Soil Screening Guidance is not intended to be used
now for any purpose other than for screening decisions at
existing NPL sites. EPA may consider other potential
applications and the development of additional tools (screening
levels for other land uses, or action levels, for example,) in
the future. EPA could also seek recommended approaches from
ASTM, the States or others, for how to screen properties whose
use is other than residential. Some of the issues which have
been raised are discussed in categories below.
B. Relationship to ASTM
Issue: The American Society for Testing and Materials (ASTM),
is a management system for the development of voluntary consensus
standards. ASTM has standards writing committees and a balloting
process to poll its 33,000 members on new standards. Because of
an overriding need for risk-based assessment and cleanup
screening tools, ASTM has recently completed a draft guidance
which includes soil standards entitled "Guide for Risk-Based
Corrective Action (RBCA) Applied at Petroleum Release Sites."
How do the methods for soils in this ASTM guide compare with the
SSL methods?
Response: There is considerable consistency between ASTM's RBCA
and the Draft Soil Screening Guidance in deriving risk-based soil
values for further assessment. This is because both guidance
documents are based on EPA's existing guidance for risk and
exposure assessment, the Risk Assessment Guidance for Superfund
(RAGS) ' . The approaches diverge, however, because RBCA uses a
tiered, risk-based approach for selecting corrective actions for
petroleum releases, depending on contaminant concentrations
found. Superfund remedies, on the other hand, must be evaluated
and be selected in accordance with procedures laid out in the
NCP, which requires an analysis of options in relation to nine
criteria, including cost. For this reason, the soil screening
guidance does not attempt to address response action selection as
does RBCA.
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Issue: The Draft Soil Screening Guidance may be used outside the
Superfund program altogether. How can EPA prevent "abuse" of the
numbers?
Response: EPA is aware that the risk-based RBCA approach is
being considered by several States for adoption as guidance or an
interim rule. This may indicate a general move by industry,
groups such as ASTM and the States to adopt risk-based screening
tools for an efficient use of assessment resources. For this
reason EPA recognizes that the soil screening guidance may also
be considered for use outside the Superfund program. There are
several ASTM Committees and other groups interested in developing
guidelines for use of the screening methodology outside the
Superfund program. EPA is exploring these developments in
relationship to the soil screening guidance.
C. State and Voluntary Cleanup
Issue: With the range and diversity in State regulatory
programs for waste site cleanup, several reviewers have asked how
the Draft Soil Screening Guidance would be used outside of the
Federal Superfund program by the States.
Response: Development of the Draft Soil Screening Guidance has
been coordinated closely with technical staff and managers of
States who have developed their own soil criteria, are in the
middle of doing so, or who are contemplating doing so. A series
of meetings between EPA and the States has indicated a general
agreement and consistency of approach between this draft guidance
and State policies, guidance and regulations which include risk-
based assessment of hazardous substances in soil. While some of
the particular exposure assumptions may differ for some States,
other States have no risk-based soil standards and would welcome
the use of the guidance. The Superfund Docket contains
supporting information EPA has received to date on analogous soil
contaminant screening levels and on cleanup levels from selected
States and other countries. While many of them focus on the
"most restrictive" land use, such as residential, a few have
developed exposure scenarios for non-residential use. The
process to develop widely accepted soil screening tools would
benefit from further exploration of how the tool might be
modified for a variety of land uses.
Issue: Several reviewers have expressed concern that States
might adopt the generic levels from the SSL Fact Sheet as cleanup
levels, resulting in inappropriately conservative cleanup levels
in some States.
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Response: Use of the SSLs as cleanup numbers would not generally
be an appropriate use of the Draft Soil Screening Guidance since
it is explicitly designed as an assessment screening tool and not
for cleanup. Under certain circumstances, where the site
conditions fit the model in the guidance, SSLs may be used as
Preliminary Remediation Goals, however other Superfund criteria
must be taken into account before a remedy is selected. (See
discussion beginning on page 8.) While it is up to the
individual States to decide how to use the soil screening
guidance, EPA does not support strict use of the guidance as
unadjusted cleanup standards. EPA and the States will continue to
explore ways to address this concern.
Issue: Some reviewers commented that the publication of the
draft guidance may create a rush to do soil sampling at every
real estate or other land based transaction.
Response: The Draft Soil Screening Guidance does not require
soil sampling at all properties. The guidance is being used for
application at Superfund sites where a known source of
contamination has been identified and ranked as a National
Priorities List (NPL) site. A known or potential source of
contamination should be identified before any soil sampling
occurs. Source identification may be done as part of a
Preliminary Assessment or Phase I environmental audit. There is
no actual or implied requirement to perform soil sampling in all
areas of all sites, especially since a sampling plan must
incorporate information on known or suspected sources of
hazardous substances from earlier assessment work. The soil
screening guidance is expected to be most helpful in resolving
"gray area" portions of sites where the edge of contamination has
yet to be defined.
Issue: Several reviewers expressed concern on the need for
performance consistency and qualification of consultants,
especially in the area of voluntary assessment and cleanup.
Response: Although the soil screening guidance is not intended
for use outside of the Superfund program, EPA recognizes that
private parties may voluntarily use them as benchmarks. The SSL
Fact Sheet provides for the flexibility of using the Data Quality
Objective process in sampling where EPA or the States are
performing some level of oversight. This ensures that the
appropriate level of statistical expertise is available to
specify the limits on decision error. If there were to be no
government oversight, such as in a voluntary cleanup, the Fact
Sheet describes a prescriptive approach for soil sampling,
including size of source area, number of samples, depth
considerations and soil compositing which will not grossly
underestimate contaminant concentrations.
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D. Brownfields and Environmental Justice
issue: Two recent initiatives on the part of EPA warrant the
consideration of the Draft Soil Screening Guidance both inside
and outside the Superfund program. EPA's "brownfields"
initiatives include pilot studies which seek to make feasible the
safe and appropriate redevelopment and economic renewal of
abandoned urban/industrial sites. In addition there is a
recognition in EPA's Environmental Justice Initiative that
certain economically disadvantaged areas may be exposed to
inordinate environmental risks, including hazardous substances in
the soil.
Response: The brownfields initiatives will include pilot studies
to evaluate the challenges associated with reclaiming abandoned
land in economic empowerment zones. The current plan is for EPA
to fund eight to ten Brownfield Pilot projects. Each pilot
project will have some level of environmental assessment
performed by the project proponent in conjunction with a State
and/or voluntary cleanup program. EPA will evaluate the
information generated in these pilot projects to determine what
appropriate role, if any, the guidance may have.
Issue: Several issues arise in the simultaneous promotion of
brownfield development, which may be targeted at strictly
industrial zones and the issuance of Draft Soil Screening
Guidance, which is designed only for residential scenarios.
Response: While there are as yet no screening levels for
industrial use, the residential screening levels for Superfund
sites are an important first step toward developing scenarios for
other land uses. Even for urban areas in or adjacent to
residential use, however, there is a lack of information on
specific contamination levels that currently exist there. EPA is
aware that other Federal agencies are establishing various
programs to encourage economic development of abandoned urban
land in order to put it back into productive use. Because of the
lack of information on soil contaminant levels in these "economic
empowerment zones" evaluation of potential implications of the
guidance for these zones will be undertaken.
Issue: For both brownfield and Environmental Justice issues,
community involvement in land use decision making, especially
where adjacent use is or will be residential, should be an
important consideration in the constructive use of the Draft Soil
Screening Guidance.
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Response: The expectations of the community, the willingness of
the States, and clear communication regarding Environmental
Justice must all be addressed early in the cleanup process at NPL
sites, and throughout the study, remedy selection and
construction phases. It is important to acknowledge the
increasing significance of community involvement in the entire
Superfund process, especially if the soil screening guidance were
to be used outside of the Superfund program. Those who may wish
to adopt the guidance for non-Superfund use must be sensitive to
the fact that the benefits of community involvement in cleanup
decisions could be lost. EPA is further exploring the brownfield
and Environmental Justice issues in relationship to the soil
screening guidance.
Issue: The SSL Guidance may be misused by lenders, developers
and others to "redline" large tracts of property which would
otherwise be appropriate for economic redevelopment.
Response: Further discussion will be required on this issue and
how it might affect brownfields projects and Environmental
Justice efforts. The limitations of the guidance as a screening
tool for only residential exposures, designed for application at
Superfund sites must be clearly communicated. EPA also intends
to emphasize use of the simple site-specific method in assigning
contaminant screening values using a small number of site-
specific parameters. This method uses a cost-effective sampling
and analytical approach. In general the simple site-specific
approach will produce screening values which, while higher than
the generic numbers, are nonetheless protective for residents at
the site.
U.S. EPA. 1989. Risk Assessment Guidance for Superfund: Volume
1: Human Health Evaluation Manual, Part A, Interim Final.
EPA/540/1-89/002. Office of Emergency and Remedial Response,
Washington D. C. NTIS PB90-155581/CCE.
U.S. EPA. 1991. Risk Assessment Guidance for Superfund, Volume
1: Human Health Evaluation Manual (Part B, Development of Risk-
Based Preliminary Remediation Goals). Publication 9285.7-01B.
Office of Emergency and Remedial Response, Washington, D. C. NTIS
PB92-963333.
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