UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
APR 1 1
OFFICE OF
SOLID WASTE AND EMERGENCY RESPONSE
Directive no. 9200.4-35P
MEMORANDUM
SUBJECT:
FROM:
Remediation Goals for Radioactively Contaminated CERCLA Sites Using
the Benchmark Dose Cleanup Criteria in 10 CFR Part 40 Appendix A, I,
Criterion 6(6)
TO:
Stephen D. Luftig, Director
Office of Emergency and Remedial Response (OE|
Office of Solid Waste and Emergency Response/
Stephen D. Page, Director
Office of Radiation and Indo
Office of Air and Radiation
Addressees
PURPOSE
This memorandum addresses the use of the soil and structure cleanup criteria in 10
CFR 40 Appendix A, I, Criterion 6(6) when setting remediation goals at CERCLA sites
with radioactive contamination. In particular, it clarifies the relationship between the soil
standards under 40 CFR Part 192 and the radium benchmark approach under the 10 CFR
40 Appendix A, I, Criterion 6(6) in setting remediation levels for soil and structures.
Because of the interrelationship between the standards under 40 CFR Part 192 and those
under 10 CFR 40 Appendix A, I, Criterion 6(6), today's memorandum should be used in
conjunction with the memorandum from OERR and ORIA, to the Regions entitled: "Use
of Soil Cleanup Criteria in 40 CFR Part 192 as Remediation Goals for CERCLA Sites"
(OSWER Directive no, 9200.4-25, February 12, 1998). Today's memorandum will be of
interest to site decisionmakers that have any of the following radionuclMes as
contaminants of concern: radium-226, radium-228, thorium-230, thorium-232, uranium-
234 and/or uranium-238 in soil and/or structures at their CERCLA site.
This document provides guidance to Regional staff, in dealing with the public and
the regulated community, regarding how EPA intends to implement the National Oil and
Printed on Recycled Paper
-------
Hazardous Substances Pollution Contingency Plan (NCP). It describes national policy.
This document is not a 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.
BACKGROUND
All remedial actions at CERCLA sites must be protective of human health and the
environment and comply with applicable or relevant and appropriate requirements
(ARARs) unless a waiver is justified. Cleanup levels for response actions under CERCLA
are developed based on site-specific risk assessments, ARARs, and/or to-be-considered
material1 (TBCs). The determination of whether a requirement is applicable, or relevant
and appropriate, must be made on a site-specific basis (see 40 CFR Part 300.400(g)).
On January 5,1983, EPA promulgated in Subpart B of 40 CFR Part 192 (48 FR
590 to 606) Standards for Cleanup of Land and Buildings Contaminated -with Residual
Radioactive Materials from Inactive Uranium Processing Sites (EPA's UMTRCA rale).2
Included in these standards is a concentration criterion for radium-226 in soil. These
standards were developed specifically for the cleanup of uranium mill tailings at 24 sites
designated under Section 102(a)(l) of UMTRCA (Title I sites). The Est of 24 Title I sites
is a closed set chosen in 1979 that cannot be added to. Later, EPA determined that these
standards were suitable for remediation of radium-228 at Title II sites (see Subpart E of
40 CFR Part 192 (48 FR 45947) Standards for Management of Thorium Byproduct
Materials Pursuant to Section 84 of the Atomic Energy Act of 1954, as Amended).
On October 16,1985 the Nuclear Regulatory Commission (NRC) promulgated
standards under 10 CFR Part 40 (NRC's UMTRCA rale) to address uranium mill tailings
(50 FR 41852), Part of these 1985 regulations established soil cleanup standards for
radium-226 and radium-228. The concentration criterion for soil is 5 pCi/g at the surface
and 15 pCi/g in the subsurface. The radium soil standards under the NRC's UMTRCA
rule were intended as conforming standards to EPA's UMTRCA soil standards under 40
CFR Part 192.3 Because EPA's soil standards under EPA's UMTRCA rule were
To-be-considered material, TBCs are non-promulgated advisories or guidance issued by Federal or State
governments that are not legally binding and do not have the status of potential ARARs. However, TBCs will be
considered along with ARARs as part of the site risk assessment and may be used in determining the necessary level of
cleanup for protection of health and the environment.
*5
These standards were developed pursuant to Section 275 of the Atomic Energy Act (42 U.S.C. 2022), as
amended by Section 206 of the Uranium Mill Tailings Radiation Control Act (UMTRCA) of 1978 (42 U.S.C, 7918).
Under section 18(a) of Public Law 97-415, the Nuclear Regulatory Commission Authorization Act for
fiscal years 1982 and 1983, the Commission was directed to conform its regulations to EPA's with notice and
opportunity for public comment,
-2-
-------
applicable to NRC and Agreement State licensees (including those for which NRC's
UMTRCA rule govern), and the NRC's UMTRCA rule standards were no more stringent,
compliance with the EPA's UMTRCA rule (40 CFR Part 192) constitutes compliance
with the NRC's UMTRCA rule (10 CFR Part 40) for radium 226 and radium-228 for
these sites.4
On April 12,1999, NRC amended its UMTRCA rule by adding Criterion 6(6) to
Appendix A (69 FR 17506 to 17510) Radiological Criteria for License Termination of
Uranium Recovery Facilities (Criterion 6(6) rule). The amendment uses the existing soil
radium standard to derive a dose criterion (benchmark approach) for cleaning up
byproduct material, including radium in soil, and for cleanup of surface activity on
structures to be released for unrestricted-use. In areas where there is more than one
residual radionuclide, the benchmark dose applies to the sum of all radionuclides present in
that area (i.e., radium, uranium, thorium, etc). NRC intends that the benchmark approach
result in a common dose criterion across an entire uranium recovery (UK) site.
The Criterion 6(6) rule addresses the lack of remediation standards for residual
radionuclides, other than radium in soil, for decommissioning of lands and structures
(excluding radon) at uranium recovery facilities. Criterion 6(6) uses the existing soil
radium standard (5 pCi/g surface and 15 pCi/g subsurface) to derive a dose criterion
(benchmark approach) for cleaning up byproduct material, and for cleanup of surface
activity on structures to be released for unrestricted use. The NRC intends to include the
dose from the subsurface soil radium standard (from NRC's UMTRCA rule) when
estimating the benchmark dose, only in those areas that require subsurface cleanup. NRC
expects that a benchmark dose estimate to address most of the site contamination will be
estimated solely from doses resulting from the radium surface standard.
The radium dose benchmark approach of the Criterion 6(6) rule requires licensees
subject to the rule to calculate the potential peak effective dose equivalent (excluding
radon) to an individual at the site within 1,000 years from exposure to the residual levels
allowed under the radium soil standard. Licensees are then to remediate the site such that
the residual site-related radionuclides (including radium) remaining on the site, both in soil
and the surface radioactivity in structures, would not result in a dose greater than the
radium soil standard. The radionuclides of concern being addressed by the Criterion 6(6)
rule are thorium, natural uranium, and radium.
For information related to 40 CFR 192 as an ARAR, please see memorandum from Steve Luftig (Director of
OERR) and Larry Weinstock (Acting Director, OAR) to the Regions entitled: "Use of Soil Cleanup Criteria in 40 CFR
Part 192 as Remediation Goals for CERCLA Sites" (Directive no. 9200,4-25, February 12,1998). As noted in the
memorandum, because the risk from uranium and thorium byproducts is additive, and because the 5 pCi/g and 15 pCi/g
standards are based on total acceptable risk, whenever the 5 pCi/g and/or 15 pCi/g standards are used as relevant and
appropriate requirements (or TBC's) at CERCLA sites with some combination of radium-226 and radium-228 (or
thorium-230 and thorium-232), these soil standards should apply to the combined level of contamination of radium-226
and radium-228 (or thorium-230 and thorium-232).
.3.
-------
IMPLEMENTATION
The following subsections will clarify the use of 10 CFR Part 40 Appendix A,
Criterion 6(6) is setting remediation levels for soil and structures.
CRITERION 6(6) RULE AS AN APPLICABLE REQUIREMENT
The standards contained within Criterion 6(6) are potentially applicable
requirements only for the Title II sites designated under Section 206 of UMTRCA.
CRITERION 6(6) RULE AS A RELEVANT AND APPROPRIATE
REQUIREMENT
If the majority of radiological risk is posed by contaminants of concern at a site in
the soil and structures that are the same (i,e., radium-226, radium-228, thorium-230,
thorium-232, uraniurn-234 and/or uranium-238) as those existing at NRC thorium mills
and uranium recovery facilities, then the Criterion 6(6) rule's benchmark dose limit is a
potentially relevant and appropriate requirement for those contaminants (i.e.,
radium-226, radium-228, thorium-230, thorium-232, uranium-234 and/or uranium-
238) found in soil and/or structures at the site. The rule would generally not be an ARAR
for radiological contaminants other then those specified above since other contaminants
are not generally found at sites subject to these standards and were not considered in the
rule.
Assumptions used in rulemaking documents during the development of the
Criterion 6(6) rule and/or found in accompanying NRC guidance documents, such as
NRC's dose assessment methodology or its land use assumption that the UR sites would
be released for unrestricted use, would generally not be considered relevant and
appropriate requirements under CERCLA nor used as guidance for making remedy
decisions at CERCLA sites.
EPA's UMTRCA RULE (40 CFR 192) AS A RELEVANT AND APPROPRIATE
REQUIREMENT
The Criterion 6(6) rule should not affect the ARAR status of requirements under
the EPA's UMTRCA rule (40 CFR Part 192). In particular, the guidance in OSWER
Directive 9200.4-25 "Use of Soil Cleanup Criteria in 40 CFR Part 192 as Remediation
Goals for CERCLA sites", still applies. This means that when the 5 pCi/g and/or 15 pCi/g
standards are used as RARs or TBCs, these soil standards should continue to apply to the
combined levels of radium-226 and radium-228, as well as the combined levels of thorium-
230 and thorium-232.
.4.
-------
The Criterion 6(6) rule is a supplement to the radium standards of 40 CFR Part
192, to address other site-related radionuclides. Therefore, when the 5 pCi/g and 15 pCi/g
standards under EPA's UMTRCA rule are not RARs for either radium-226 and/or
radium-228, the Criterion 6(6) rule is generally not appropriate. In addition, when
supplemental standards in 40 CFR Part 192, Subpart C are used instead of EPA's
UMTRCA 5/15 pCi/g soil standards as RARs, then the Criterion 6(6) rule is generally not
appropriate.
Even if EPA's UMTRCA soil standards were used as TBCs, we recommend that
the Criterion 6(6) rule's benchmark dose approach should not be used as a TBC. This is
consistent with EPA's prior guidance that, in general, dose assessments should only be
conducted under CERCLA where necessary to demonstrate ARAR compliance5.
CONDUCTING DOSE ASSESSMENT FOE CRITERION 6(6) RULE ARAR
COMPLIANCE
The Criterion 6(6) rule provides a benchmark approach for setting cleanup levels
for radionuclides. Specifically the Criterion 6(6) rule specifies:
"Byproduct material containing concentrations of radionuclides other than radium
in soil and surface activity on remaining structures, must not result in a total
effective dose equivalent (TEDE) exceeding the dose from cleanup of radium
contaminated soil to the above standard (benchmark dose),..."
Site-specific application of the Criterion 6(6) rule as a RAR will involve both a dose
assessment to establish potential cleanup levels for the residual radionuclides as well as a
determination of whether the dose assessment developed under the rule is protective
enough to establish cleanup levels under CERCLA.
Dose Assessment Methodology
Dose assessments (excluding radon) are conducted to convert the radium soil
standards into a benchmark dose for all radionuclides at the site. When the Criterion 6(6)
rule is considered a relevant and appropriate requirement, then dose assessments that are
conducted to develop the benchmark dose for a site, and to show compliance of
remediation goals for soil and structures with the benchmark dose (the "compliance
dose"), should be conducted site-specifically, using Superfund reasonably maximum
For fiuther information regarding this EPA determination, see the memorandum from Stephen D. Luftig titled;
"Establishment of Cleanup Levels for CERCLA Site with Radioactive Contamination" (OSWER Directive 9200.4-18),
August 22,1997, p. 3. Further clarification of this EPA determination is also provided in the memorandum from Stephen
D. Luttig titled "Distribution of OSWER Radiation Risk Assessment Q & A's Final Guidance" December 17,1999, pp. 2-
3 and the guidance entitled "Radiation Risk Assessment at CERCLA Sites: Q & A" (OSWER Directive 9200.4-31P)
December 1999 pp 13-14.
-5-
-------
exposure (RME) scenario parameters that are consistent with the reasonably anticipated
land use6 of the site.
Both the benchmark dose and the dose analysis to confirm compliance with the
benchmark dose (the "compliance dose") should be estimated as the sum of doses from all
appropriate exposure pathways. For soil these pathways would typically include; direct
ingestion of soil; inhalation of fugitive dusts; ingestion of contaminated ground water
caused by migration of radionuclides through soil to an underlying potable aquifer;
external radiation exposure from radionuclides in soil; and ingestion of homegrown
produce that has been contaminated via plant uptake. For structures these pathways
would typically include: external radiation exposure from radionuclides in building
material; and inhalation of fugitive contaminated building materials.
The benchmark dose from soil should be met for the sum of exposures from both
soil and structures. All radionuclides of concern should be included in dose assessments
to show compliance with the benchmark dose. The dose assessments, both for the
benchmark dose and the compliance dose evaluation, should be for the year of peak dose
over the next 1,000 years. The compliance dose evaluation should also assess non-surface
radioactivity in contaminated structures.
The benchmark dose assessment should only include estimates of doses from
subsurface radium contamination only for those portions of the site where subsurface
radionuclide contaminants require cleanup under CERCLA. This cleanup action could be
triggered either by exceedances of ARARs (e.g., radionuclides may migrate to the through
the soil to an underlying aquifer at levels exceeding the MCL) or where protective risk
levels are exceeded (radionuclide contaminants levels result in risks outside the risk range,
or when summed with other nonradiological contaminants and/or radionuclide
contaminants at the surface will proceed to drive risk estimates outside of the risk range. If
the benchmark dose includes estimates of doses resulting from subsurface contamination,
both the benchmark and the compliance dose should be estimated based on the extent of
the depth of the contamination using 15 cm increments (e.g., 15 through 30 cm, then 30 to
45 cm, etc.).
Criterion 6(6) Rule Dose Evaluation and Risk Assessment for Establishment of
Cleanup Levels for CERCLA Sites
If the Criterion 6(6) rule is considered to be an ARAR at a CERCLA site, then a
site-specific dose assessment needs to be made to determine whether the Criterion 6(6)
rule is used to set cleanup levels under CERCLA. If a site-specific dose assessment
In developing land use assumptions, decision makers should consult the guidance provided in the memorandum
from Elliot Laws A.A. OSWER entitled: "Land Use in the CERCLA Remedy Selection Process" (OSWER Directive No.
9355.7-04), May 25,1995.
-6-
-------
indicates that the radium benchmark dose will be above 15 mrem/yr EDE, the dose limit
that EPA generally considers minimally acceptable under CERCLA, then the NRC rule
should generally not be used to establish cleanup levels at that CERCLA site. EPA has
previously determined that dose limits greater than 15 mrem/yr generally will not provide
a protective basis for establishing preliminary remediation goals (PRGs) under CERCLA.7
Please note that 15 mrem/yr is not a presumptive cleanup level under CERCLA, but
rather site decision-makers should continue to use the risk range when ARARs are
not used to set cleanup levels.
In addition to the dose assessments that are required to show compliance with
Criterion 6(6) as a RAR, a site-specific risk assessment must generally be conducted to
confirm that the residual levels allowed to meet the compliance dose evaluation, are
sufficiently protective (e.g., generally meets the 10"4 to 10"6 risk range, hazard index less
than 1) to be used as cleanup levels under CERCLA.8 This additional risk assessment step
is recommended for two reasons. First, the benchmark dose concept in Criterion 6(6) was
developed using the ICRP/NCRP regulatory approach, which assumes that doses less than
100 mrem/yr are protective, rather than the risk range generally used to determine
protectiveness under CERCLA. This 100 mrem/yr approach has previously been
determined by EPA to not be protective under CERCLA. In addition, there is no basis for
demonstrating that even compliance doses below 15 mrem/yr will be protective for the
radionuclides that may be addressed by the Criterion 6(6) rule. Please note that this risk
assessment recommendation generally does not apply to other ARARs.
Since the NRC's UMTRCA rule radium standards in 10 CFR Part 40 are intended
as conforming standards to EPA's UMTRCA standards under 40 CFR Part 192, when
conducting a dose assessment to show compliance with Criterion 6(6) rule as a relevant
and appropriate requirement, a concentration of 5 pCi/g should be used as the radium
concentration for assessing a benchmark dose, in the subsurface as well as the surface. A
concentration value of 5 pCi/g for radium in the subsurface, rather than 15 pCi/g, should
be used as the starting point when developing a benchmark dose to demonstrate
compliance with the Criterion 6(6) rule as a relevant and appropriate requirement at a
CERCLA site. This recommendation is consistent with EPA's determination that soil
cleanups occurring at UMTRCA sites using the 15 pCi/g "finding tool" standard in 40
For further information regarding this EPA determination, see the memorandum from Stephen D. Luftig titled:
"Establishment of Cleanup Levels for CERCLA Sites with Radioactive Contamination" (OSWER Directive 9200.4-18),
August 22,1997, p. 3. Further clarification of this EPA determination is also provided in the memorandum from Stephen
D. Luftig titled "Distribution of OSWER Radiation Risk Assessment Q & A's Final Guidance" December 17,1999, pp. 2-
3 and the guidance entitled "Radiation Risk Assessment at CERCLA Sites: Q & A" (OSWER Directive 9200.4-3 IP)
December 1999 pp 13-14.
^or further information regarding conducting risk assessments for radiological contaminants at CERCLA sites,
see the guidance entitled "Radiation Risk Assessment at CERCLA Sites: Q & A" (OSWER Directive 9200.4-3IP)
December 1999.
-7-
-------
CFR Part 192 would result in residual soil concentrations of no more than 5 pCi/g.9 If
cleanup using the 15 pCi/g "finding tool" would not result in concentrations of 5 pCi/g or
less, then 40 CFR Part 192 would not be expected to be an ARAR since the site would be
inherently different from that for which the EPA UMTRCA regulations were written. As
discussed earlier, if 40 CFR Part 192 is not an ARAR then Criterion 6(6) would also not
be an ARAR.
RELATION OF TODAY'S GUIDANCE AND PREVIOUS EPA GUIDANCE ON
NRC DECOMMISSIONING
It should be noted that today's memorandum does not alter previous EPA
guidance regarding NRC's Radiological Criteria for License Termination (see 62 FR
39058, July 21, 1997). NRC's 1997 decommissioning rule should still generally not be
used as the basis for establishing remediation goals under CERCLA, since the dose limits
in that rule were determined by EPA to generally not provide a protective basis for
establishing remediation goals.
However, since the 1999 Criterion 6(6) rule requires the establishment site-
specifically of a benchmark dose that functions as an enforceable dose limit, this rule must
be assessed on a site specific basis to determine if the dose limit is above the 15 mrem/yr
level that EPA has previously determined was the highest acceptable dose limit.
HYPOTHETICAL SITE EXAMPLE OF IMPLEMENTATION OF TODAY'S
GUIDANCE
Below is an example of how today's guidance might be implemented at a site
where the Criterion 6(6) and EPA UMTRCA rules are considered relevant and
appropriate requirements.
Example. Radionuclide contaminants of concern at site X are uranium 238,
uranium 234, thorium-230, radium-226, and actinium-227. These contaminants
are located both in soil (surface and subsurface) and structures. To comply with
the EPA UMTRCA rule as a relevant and appropriate requirement, the
remediation goal for both thorium-230 and radium-226 (each, not combined),
would be 5 pCi/g both in the first 15 cm of depth at the surface, and any 15 cm
that are contaminated in the subsurface. In addition, to comply with the Criterion
6(6) rule as a relevant and appropriate requirement, the following steps were
taken. First, a benchmark dose of 12 mrem/yr was estimated on a site-specific
basis using EPA Superfund risk/dose assessment exposure assumptions, if a
'For further information regarding this EPA determination, see the memorandum from Stephen D. Luftig
title: "Use of Soil Cleanup Criteria in 40 CFR Part 192 as Remediation Goals for CERCLA sites" (OSWER
Directive No. 9200.4-25), February 12, 1998.
-8-
-------
residual level of radium-226 in the soil of 5 pCi/g existed in both the surface and
subsurface. Then cleanup concentration levels were developed to attain the
compliance dose of 12 mrem/yr for the peak dose year over the next 1,000 years of
all radiological contaminants of concern. This means the sum of the doses from
the cleanup concentration levels of all the radionuclide contaminants (uranium 238,
uranium 234, thorium-230, radium-226, and actinium-227), in the soil and the
structures, must not exceed 12 mrem/yr to an RME individual using exposure
parameters consistent with the selected land use for the site in order to attain the
compliance dose. Thus compliance with the Criterion 6(6) rule would achieve a
remediation level of less than 5 pCi/g for radium-226 in soil as the dose from the
other radionuclides are taken into account.
FURTHER INFORMATION
The subject matter specialist for this directive is Stuart Walker of OERR (703-
603-8748. General questions about this directive, should be directed to 1-800-424-9346.
Addressees:
National Superfund Policy Managers, Regions 1-10
Superfimd Branch Chiefs, Regions 1-10
Superfund Branch Chiefs, Office of Regional Counsel, Regions 1-10
Radiation Program Managers, Regions 1,4, 5,6, 7,10
Radiation Branch Chief, Region 2
Residential Domain Section Chief, Region 3
Radiation and Indoor Air Program Branch Chief, Region 8
Radiation and Indoor Office Director, Region 9
Federal Facilities Leadership Council
OERR Center Directors
CC:
Jim Woolford, FFRRO
Elizabeth Cotsworth, OSW
Craig Hooks, FFEO
Barry Breen, OSRE
Joanna Gibson, HOSC/OERR
Earl Salo, OGC
-9-
------- |