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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
APR 13 1998
OFFICE OF
SOLID WASTE AND EMERGENCY RESPONSE
OSWER Directive 9200.4-26
MEMORANDUM
SUBJECT: Approach for Addressing Dioxin in Soil at CERCLA and
RCRA Sites
FROM: Timothy Fields, Jr. Acting Administrator /s/
Office of Solid Waste and Emergency Response
TO: Director, Office of Site Remediation and Restoration
Region I
Director, Emergency and Remedial Response Division
Region II
Director, Division of Environmental Planning and
Protection
Region II
Director, Hazardous Waste Management Division
Regions IX
Director, Waste Management Division
Region IV
Director, Waste, Pesticides, & Toxics Division
Region V
Director, RCRA Multimedia Planning & Permitting
Division
Region V
Director, Superfund Division
Regions III, V, VI, VII
Assistant Regional Administrator, office of Ecosystems
Protection and Remediation
Region VIII
Director, Hazardous Waste Program
Region VIII
Director, Office of Environmental Cleanup
Region X
Director, Office of Waste and Chemical Management
Region X
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PURPOSE
The purpose of this Directive is to recommend preliminary
remediation goals (PRGs) or starting points for setting cleanup
levels for dioxin in soil at Comprehensive Environmental Response,
Compensation and Liability Act (CERCLA) and Resource Conservation and
Recovery Act (RCRA) corrective action sites. These recommended levels
are to be used pending the release of the U.S. Environmental
Protection Agency (EPA) comprehensive dioxin reassessment report and
cross-program assessment of the impacts of the report. One ppb (TEQs,
or toxicity equivalents) is to be generally used as a starting point
for setting cleanup levels for CERCLA removal sites and as a PRG for
remedial sites for dioxin in surface soil involving a residential
exposure scenario. For commercial/industrial exposure scenarios, a
soil level within the range of 5 ppb to 20 ppb (TEQs) should
generally be used as a starting point for setting cleanup levels at
CERCLA removal sites and as a PRG for remedial sites for dioxin in
surface soil. These levels are recommended unless extenuating
site-specific circumstances warrant a different level.
The dioxin levels discussed in this Directive are also
generally recommended for actions taken under RCRA at corrective
action sites. The recommended levels of 1 ppb (TEQs) for residential
soils and within the range of 5 ppb to 20 ppb (TEQs) for
commercial/industrial soils should generally be used as starting
points in setting soil cleanup levels at RCRA corrective action
sites. These levels are generally consistent with soil cleanup levels
set at RCRA facilities throughout the country where dioxin is a
principal contaminant of concern at the facility. However, because
states are the primary implementors of the RCRA Corrective Action
program, this Directive does not prescribe specific procedures for
implementation under RCRA.
This Directive sets forth the policy basis for these
recommended levels and prescribes procedures for implementing these
recommendations.
BACKGROUND
To date, EPA has generally selected 1 ppb as a cleanup level
for dioxin in residential soils at Superfund and RCRA cleanup sites
where dioxin is a principal contaminant of concern at the facility.
EPA has also, to date, generally selected a cleanup level for dioxin
within the range of 5 ppb to 20 ppb for commercial/industrial soils
at Superfund and RCRA cleanup sites where dioxin is a principal
contaminant of concern at the facility. The levels that EPA has
selected at these sites are protective of human health and the
environment. Based on presently available information, and using
standard default assumptions for reasonable maximum exposure
scenarios, the upper-
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bound lifetime excess cancer risk from residential exposure to a
concentration of 1 ppb dioxin is approximately 2.5 x 10~4, which is
at the higher end of the range of excess cancer risks that are
generally acceptable at Superfund sites. The calculated upper-bound
excess cancer risk associated with a lifetime commercial/industrial
exposure to 5 ppb, or the lower end of the range recommended for
commercial/industrial soils, is approximately 1.3 x 10~4, which is
also within the CERCLA risk range. It should be noted that there is
more difficulty in generalizing about the cancer risk associated with
commercial/industrial cleanup levels than there is with residential
cleanup levels due to the greater variability in exposures associated
with commercial/industrial scenarios. Accordingly, the consultation
process for Superfund sites referenced in the implementation section
of this Directive should be used to ensure the selection of
appropriate, protective dioxin levels at CERCLA commercial/industrial
sites. Similarly, for RCRA corrective action sites, please refer to
the implementation section of this Directive.
EPA is presently completing work on a comprehensive
reassessment of the toxicity of dioxin, to be embodied in the
documents entitled "Health Assessment Document for 2,3,7,8
tetrachlorodibenzo-p-dioxin (TCDD) and Related Compounds" and
"Estimating Exposure to Dioxin-like Compounds." The reassessment
report, which is scheduled to be issued in 1998, will represent the
culmination of an Agency-wide effort to collect, analyze and
synthesize all of the available information about dioxin. It has
undergone significant internal and external review and is one of the
most comprehensive evaluations of toxicity of a chemical ever
performed by the Agency. Following release of the report, the Office
of Solid Waste and Emergency Response (OSWER) will participate in a
cross-program review of the implications of the report for the
regulation and management of dioxin by EPA. We anticipate that this
review will culminate in OSWER guidance addressing the management of
dioxin at CERCLA and RCRA sites.
The Office of Solid Waste and Emergency Response does not
believe it is prudent to establish new, and possibly varying,
precedents for Superfund or RCRA dioxin levels just prior to the
release of this reassessment report. As with any other pollutant, it
is important that EPA ensure appropriate national consistency in
remediation efforts. The Agency has used 1 ppb as a residential
cleanup level and between 5 ppb and 20 ppb as a commercial/industrial
cleanup level at CERCLA and RCRA cleanup sites for dioxin in soil in
the past; it is anticipated that OSWER will be issuing guidance,
informed by the reassessment effort, that will provide a basis for
the selection of dioxin cleanup levels in the near future. In the
interim, for sites that require the establishment of a final dioxin
soil cleanup level prior to the release of the reassessment report
and
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development of OSWER guidance, EPA should generally use 1 ppb (TEQs)
as a starting point for residential soil cleanup levels for CERCLA
non-time critical removal sites (time permitting, for emergency and
time critical sites) and as a PRG for remedial sites. EPA should
generally use a level within the range of 5 ppb to 20 ppb (TEQs) as a
starting point for cleanup levels at CERCLA non-time critical removal
sites (time permitting, for emergency and time critical sites) and as
a PRG for remedial sites for commercial/industrial soil. These levels
should also be used as starting points in setting soil cleanup levels
at RCRA corrective action sites.
For CERCLA remedial sites, consistent with 40 CFR §
300.430 (f) (5) (iii) (D) , EPA should commit to reviewing Records of
Decision (RODs) (i.e., RODs in which this Directive has been used to
develop dioxin soil cleanup levels) promptly following the release
and analysis of the reassessment report and OSWER guidance, and, if
necessary, to making changes to the RODs and cleanup actions, based
on the information contained in the reassessment report and in the
OSWER guidance. Similarly, in the case of non-time critical removal
actions (time permitting, for emergency and time critical actions),
EPA should commit to reviewing Action Memoranda promptly following
the release and analysis of the reassessment report and OSWER
guidance, and, if necessary, to making changes to the Action
Memoranda and cleanup actions, based on the information contained in
the reassessment report and the OSWER guidance. EPA should similarly
commit to reviewing RCRA cleanup decisions (i.e., decisions for which
this Directive has been used) promptly following the release and
analysis of the reassessment report and OSWER guidance.
IMPLEMENTATION
Regional management should consult with the appropriate Office
of Emergency and Remedial Response (OERR) Regional Centers on all
proposed Fund and Potentially Responsible Party-lead site decisions
under CERCLA, including other Federal agency-lead and state-lead site
decisions, involving the development of dioxin soil cleanup levels
for non-time critical removal sites (time permitting, for emergency
and time critical removal sites) and remedial sites. Consultation
should be initiated at the risk assessment stage. For Federal
agency-lead sites, OERR will, in turn, notify the Federal Facilities
Restoration Reuse Office of ongoing consultations. The Office of Site
Remediation Enforcement will provide support if enforcement issues
are identified. For consultation procedures, refer to the OSWER
"Headquarters Consultation for Dioxin Sites", 9200.4-19, December 13,
1996, plus the OSWER "Consolidated Guide to Consultation Procedures
for Superfund Response Decisions", 9200.1-18FS, May 1997.
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In the case of EPA-lead RCRA corrective action sites, Regions
should provide the Office of Solid Waste Permits and State Programs
Division (OSW/PSPD) with proposed dioxin soil cleanup levels (i.e.,
prior to notice and comment) in order to ensure appropriate
implementation of this Directive. For state-lead RCRA corrective
action sites, it is also recommended that states use the dioxin
levels recommended by this Directive as starting points in setting
soil cleanup levels. States are encouraged to share their approaches
with the Regions in a manner consistent with established procedures
for EPA support and oversight of state RCRA Corrective Action
programs.
The levels in this Directive are recommended unless extenuating
site-specific circumstances warrant different levels, a more
stringent state applicable or relevant and appropriate requirement
(ARAR) establishes a cleanup level at CERCLA sites, or a more
stringent state requirement applies at RCRA sites. We recommend that
levels other than 1 ppb (TEQs) for residential soils and outside the
range of 5 ppb to 20 ppb (TEQs) for commercial/industrial soils be
used only where evidence exists that risks posed by the site differ
from risks estimated using standard national default guidance values.
These recommendations apply to RCRA corrective actions, CERCLA
non-time critical removal actions (time permitting, for emergency and
time-critical actions) and CERCLA remedial actions where cleanup
levels are to be developed for dioxin in soil, regardless of whether
dioxin itself drives the decision-making process.
The recommended levels found in this Directive, generally
considered protective of human health and the environment, apply to
surface soils. Please note that with respect to human health, these
levels are based on the direct contact exposure pathway. The
recommended levels in this Directive do not apply to other exposure
pathways, such as migration of soil contaminants to ground water or
to agricultural products. While the focus of this Directive is on
soils, these recommended levels also apply to sediments in the event
that this environmental medium is considered to be a direct exposure
pathway for human receptors.
This document provides guidance to EPA staff. The guidance is
designed to communicate national policy on dioxin cleanups for soil.
The document does not, however, substitute for EPA's statutes or
regulations, nor is it a regulation itself. Thus, it cannot impose
legally-binding requirements on EPA, states, or the regulated
community, and may not apply to a particular situation based upon the
circumstances. EPA may change this guidance in the future, as
appropriate.
If you have any questions concerning this Directive, please
contact either Marlene Berg at (703)603-8701 in Headquarters or Elmer
Akin of Region 4 at (404)562-8634, as Marlene and Elmer are
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co-chairs of the Superfund Dioxin Workgroup. For the RCRA Corrective
Action program, please contact Robert Hall of the Office of Solid
Waste Permits and State Programs Division at (703)308-8484. Attached,
for your information, is a list of Regional points of contact who are
serving on the dioxin workgroup.
Attachment: Superfund Dioxin Workgroup: Regional Points of
Contact
cc: Mike Shapiro, OSWER
Peter Grevatt, OSWER
Steve Luftig, OERR
Elaine Davies, OERR
Larry Reed, OERR
Gershon Bergeisen, OERR
David Bennett, OERR
Bruce Means, OERR
Betsy Shaw, OERR
Paul Nadeau, OERR
Tom Sheckells OERR
Murray Newton, OERR
John Cunningham, OERR
Dave Evans, OERR
Joe LaFornara, OERR
Mark Mjoness, OERR
Jim Woolford, FFRRO
Elizabeth Cotsworth, OSW
Barry Breen, OSRE
Tudor Davies, OW
Craig Hooks, FFEO
Earl Salo, OGC
Bill Sanders, OPPT
Bill Farland, ORD
Regional Counsel, Regions I-X
Peggy Schwebke, Region 5
Superfund Dioxin Workgroup
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