Section 121(d)(2) of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as
amended by the 1986 Superfund Amendments and Reauthorization Act (SARA), requires that on-site remedial actions must
attain (or waive) Federal and more stringent State applicable or relevant and appropriate requirements (ARARs) of
environmental laws upon completion of the remedial action. The revised National Contingency Plan of 1990 (NCP) requires
compliance with ARARs during remedial actions as well as at completion, and compels attainment of ARARs during
removal actions to the extent practicable, considering the exigencies of the situation. See the NCP, 40 CFR section
300.415(i) (55 FR 8666, 8843) and section 300.435(b)(2) (55 FR 8666, 8852) (March 8, 1990).
To implement the ARARs provision, EPA has developed guidance, CERCLA Compliance With Other Laws Manual:
Parts I and II (Publications 9234.1-01 and 9234.1-02), and has provided training to Regions and States on the identification
of and compliance with ARARs. These “ARARs Q’s and A’s” are part of a series of Fact Sheets that provide guidance on
a number of questions that arose in developing ARAR policies, in ARARs training sessions, and in identifying and
complying with ARARs at specific sites. This particular 0’s and A’s Fact Sheet, which updates and replaces a Fact Sheet
first isstjed in May 1989, addresses the ARARs general policy; compliance with the Resource Conservation and Recovery
Act (RCRA), the Clean Water Act (CWA), and the Safe Drinking Water Act (SDWA); Post-ROD Information and
Administrative Record requirements: and “contingency” waivers of ARARs.
I. General Policy
Qi. What difference does it make whether a requirement
is “applicable” or “relevant and appropriate”? Why
make that distinction?
A. It is true that once a requirement is determined to be
relevant and appropriate, it must be complied with as
if it were applicable. However, there are significant
differences between the identification and analysis of
the two types of requirements (see Highlight 1).
“Applicability” is a legal and jurisdictional deter-
mination, while the determination of “relevant and
appropriate” relies on professional judgment, con-
sidering environmental and technical factors at the
site. There is more flexibility in the relevance and
appropriateness determination: a requirement may
be “relevant,” in that it covers situations similar to
that at the site, but may not be “appropriate” to apply
for various reasons and, therefore, not well suited to
the site. In some situations, only portions of a
requirement or regulation may be judged relevant and
appropriate; if a requirement is applicable, however,
all substantive parts must be followed. (See Overview
of ARARs: Focus on ARAR Waivers . Publication
9234.2-03/FS, December 1989, for further discussion
on compliance with ARARs.)
For example, if closure requirements under Subtitle
C of RCRA are applicable (e.g., at a landfill that
received RCRA hazardous waste after 1980 or where
the Superfund action constitutes disposal of
hazardous waste), the landfill must be closed in
compliance with one of the closure options available
in Subtitle C regulations. These options are closure
by removal (clean closure), which requires decontam-
ination to health-based levels, or closure with waste
in place (landfill closure), which requires imperme-
able caps and long-term maintenance.
However, if Subtitle C closure requirements are not
applicable, but are determined to be relevant and
appropriate, then a “hybrid closure,” which includes
other types of closure designs, may also be used. The
hybrid closure option arises from a determination
that only certain closure requirements in the two
Subtitle C closure alternatives are relevant and
appropriate. (See proposed NCP, 53 FR at 51446,
and preamble to the NCP, 55 FR at 8743, for further
discussion of RCRA closure requirements and the
concept of hybrid closure.)
United States
Environmental Protection
Agency
GEPA
Office of
Solid Waste and
Emergency Response
ARARs Q’s & A’s:
Publication 9234.2-01/ES-A
July 1991
Office of Emergency and Remedial Response
Office of Program Management OS-240
General Policy, RCRA, CWA, SDWA,
Post-ROD Information, and
Contingent Waivers
Quick Reference Fact Sheet

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Q2. Does an applicable requirement take precedence over
one that is relevant and appropriate? In other
words, if an applicable requirement is available, will
that be the ARAR, rather than one that might
otherwise be relevant and appropriate?
A. No, a requirement may be relevant and appropriate
even if another requirement legally applies to that
situation, particularly when the applicable require-
ment was not really intended to address the type or
magnitude of problems encountered at Superfund
sites. For example, RCRA Subtitle D requirements
for covers for solid waste facilities may be applicable
when RCRA hazardous waste is not present at the
site. However, the soil cover required under Subtitle
D may not always be sufficient to limit leachate at a
Superfund site that has substantial amounts of waste
similar to RCRA hazardous waste. In such a
situation, some Subtitle C closure requirements may
be relevant and appropriate to some parts of the site,
even though Subtitle D requirements legally apply.
However, one factor that affects whether a
requirement is relevant and appropriate is whether
another requirement exists that more fully matches
the circumstances at the site. In some cases, this
might be a requirement that was directly intended for,
and is applicable to, the particular situation. For
example, Federal Water Quality Criteria generally
will not be relevant and appropriate and, therefore,
not ARAR when there is an applicable State Water
Quality Standard promulgated specifically for the
pollutant and water body, which therefore “more fully
matches” the situation. (Sec Overview of ARARs:
Focus on ARAR Waivers , Publication 9234.2-03/FS,
December 1989, for further discussion on compliance
with ARARs, and CERCLA Compliance With the
CWA and SDWA , Publication 9234.2-06/FS,
February 1990, for additional discussion on the
resolution of potentially conflicting water ARARs.)
Q3. Is compliance with ARARs required for a “no action”
decision?
A. No. CERCLA Section 121 cleanup standards, in-
cluding compliance with ARARs, apply only to
remedial actions that the Agency determines should
be taken under CERCLA Sections 104 and 106
authority. A “no action” decision can only be made
when no remedial action is necessary to reduce,
control, or mitigate exposure because the site or
portion of the site is already protective of human
health and the environment. See Guidance on
Preparing Superfund Decision Documents (OSWER
Directive 9355.3-02) for further discussion of “no
action” decisions.
Q4. Does an ARAR always have to be met, even if it is
not necessary to ensure protectiveness?
A. Yes, unless one of the six waivers can be used.
Attainment of ARARs is a “threshold requirement”
in SARA, as is the requirement that the remedies he
protective of human health and the environment. If
a requirement is applicable or relevant and appro-
priate, it must be met, unless an ARAR waiver can
be used. ARARs represent the minimum that a
remedy must attain; it may sometimes be necessary,
where there are multiple contaminants with poten-
tially cumulative or synergistic effects, to go beyond
what ARARs require to ensure that a remedy is pro-
tective. (See Overview of ARARs: Focus on ARAR
Waivers , Publication 9234.2-03/FS, December 1989
for further discussion on compliance with ARARs.)
QS. If wastes from non-contiguous facilities are combined
on one site for treatment, is the treatment viewed as
off-site activity, and the unit therefore subject to
permitting?
A. No. Because the combined remedial action consti-
tutes on-site action, compliance with permitting or
other administrative requirements would not be
required (see Highlight 2). CERCLA Section
104(d)(4) authorizes EPA to treat two or more non-
contiguous facilities as one site for purposes of
response, if such facilities are reasonably related on
Highlight 1: DEFINITIONS OF “APPLICABLE”
AND “RELEVANT ANI) APPROPRIATE”
“ Applicable requirements mean those cleanup
standards, standards of control, and other
substantive environmental protection requirements,
criteria, or limitations promulgated under Federal
environmental or State environmental or facility
siting law that specifically address a hazardous
substance, pollutant, contaminant, remedial action,
location, or other circumstance at a CERCLA site.”
[ Section 300.5 of the NCP, 55 FR at 8814] In
other words, an applicable requirement is one with
which a private party would have to comply by law
if the same action was being undertaken apart from
CERCLA authority. All jurisdictional prerequisites
of the requirement must be met in order for the
requirement to be applicable.
If a requirement is not applicable, it still may be
relevant and appropriate. “ Relevant and
appropriate requirements mean those cleanup
standards [ that] ... address problems or situations
sufficiently similar to those encountered at the
CERCLA site that their use is well suited to the
particular site.” [ Section 3005 of the NCP, 55 FR
at 8817] A requirement that is relevant and
appropriate may “miss” on one or more jurisdic-
tional prerequisites for applicability but still make
sense at the site, given the circumstances of the site
and release .

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the basis of geography or their potential threat to
public health, welfare, or the environment. In
keeping with the Statutory criteria under CERCLA
Section 121( h), combining facilities as one site for
remedial action must also he shown to be cost-
effective and not result in any significant additional
short-term impacts on public health and the environ-
ment. (See preamble to the NC?, 55 FR at 8690-
8691; Interim RCRA/CERCLA Guidance on Non-
Contiguous Sites and On-Site Management of Waste
Residue , OSWER Directive 9347.0-1, March 1986;
and 49 FR at 37076, September 21, 1984.)
Q6. Are environmental resource laws, such as the
Endangered Species Act, the National Historic Pres-
ervation Act (NIIPA), and the Wild and Scenic
Rivers Act, potential ARARs for CERCLA actions?
A. Yes, requirements in these laws are potential
ARARs, However, these laws frequently require
consultation with, and under some laws, concurrence
of, other Agencies or groups, such as the Fish and
Wildlife Service or the Advisory Council on Historic
Preservation. Administrative requirements such as
consultation or obtaining approval are not required
for on-site actions. However, it is strongly recom-
mended that the lead agency nevertheless consult
with the administering agencies to ensure compliance
with substantive requirements, e.g., the NHPA
requirement that actions must avoid or minimize
impacts on cultural resources. (See preamble to the
NCP, 55 FR at 8757. Also, see Summary of Part II:
CAA, TSCA, and Other Statutes , Publication 9234.2-
O7IFS, April 1990, for further discussion of resource
protection laws.)
Q7. Are environmental standards and requirements of
Indian Tribes potential ARARs?
A. Yes. Indian Tribal requirements are potential
ARARs for CERCLA actions taken on Tribal lands
and are treated consistently with State requirements.
Tribal requirements that meet the eligibility criteria
for State ARARs, i.e., those that are promulgated
(legally enforceable and of general applicability), are
more stringent than Federal requirements, and are
identified in a timely manner, are potential ARARs.
(See preamble to the NCP, 55 FR at 8741-8742;
section 300.5 of the NCP, 55 FR at 8816 for a
definition of Indian Tribe; and the Revised Interim
Final Guidance on Indian Involvement in the
Superfunci Program , OSWER Directive 9375.5-02A,
November 28, 1989.)
II. Resource Conservation and Recovery Act (RCRA)
Q8. how can RCRA listed waste be “delisted” when
wastes will remain on-site?
A. By documenting in the ROD that the substantive
requirements in RCRA for delisting have been met,
a RCRA listed waste may he “delisted” when wastes
remain on-site.
Once a listed waste is “delisted,” it is no longer
considered a ‘hazardous waste’ and is, therefore,
subject to RCRA Subtitle D requirements for solid
waste, rather than the more stringent RCRA Subtitle
C requirements.
The substantive requirements that must be met for
delisting a RCRA hazardous waste that will remain
on-site are the standards in 40 CFR sections
260.22(a)(1) and (2), which state that a waste that
“does not meet any of the criteria under which the
waste was listed as hazardous or an acutely hazardous
waste” and for which there is no “reasonable basis to
believe that factors (including other constituents)
other than those for which the waste was listed could
cause the waste to be a hazardous waste” is
“delistable.” Administrative requirements, which
include requirements to undergo a petition and
rulemaking process and to develop and supply specific
highlight 2: ON-SITE VS. OFF-SITE ACTIONS
The requirements under CERCLA for compliance
with other laws differ in two significant ways for on-
site and off-site actions. First, the ARARs pro-
vision applies only to on-site actions; ot1 site
actions must comply fully only with any laws that
legally apply to that action. Therefore, off-site
actions need only comply with “applicable”
requirements, not with “relevant and appropriate”
requirements; ARAR waivers are not available for
requirements that apply to off-site actions.
Second, on-site actions must comply only with the
substantive portions of a given requirement; on-site
activities need not comply with administrative
requirements, such as obtaining a permit or record-
keeping and reporting. (Monitoring requirements
arc considered substantive requirements.) Off-site
actions must comply with both substantive and
administrative requirements of all applicable laws .
[ Note: ARARs arc the requirements of environ-
mental and facility siting laws only. Independent of
ARARs, on-site activities also must comply with
applicable requirements of non-environmental laws
(e.g., building codes and safety requirements),
excluding permit requirements.]

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information, need not be met on-site. (See A Guide
to Delistin of RCRA Wastes for Superfund
Remedial Responses , Publication 9347.3-09/FS,
September 1990.)
Wastes containing constituents at health-based levels,
assuming direct exposure, generally will meet the
standards for delisting. Wastes with constituents at
higher levels may also be delistable, since the RCRA
delisting process allows fate-and-transport modeling,
generally based on the waste being managed in a
solid waste unit. The models used by the RCRA
program for delisting are recommended for use in
determining whether constituent concentrations above
health-based levels are delistable, e.g., for wastes that
will be land disposed (See 50 FR 48886, November
27, 1985 and 51 FR 41082, November 13, 1986). The
Waste Identification Branch in the Office of Solid
Waste (FTS 382-4770) can also provide assistance
and advice in delisting a waste.
Substantive requirements for a waste to meet
delisting levels should be documented in the RI/FS
and the ROD, and a general discussion of why
delisting is warranted should be included (see
Guide to Delistinn of RCRA Wastes for Superfund
Remedial Responses , Publication 9347.3-09/FS,
September 1990). Generally, the constituent levels
that must be achieved in order for the waste to be
considered non-hazardous should be identified in the
ROD. Unless treatability studies done during the
RI/FS make delisting reasonably certain, the ROD
should also address, as a contingency, how the waste
will he handled if it does not achieve delistable levels,
based Ofl full-scale treatahility studies or actual
performance of the remedy during RD/RA. If the
waste cannot he delisted, and this contingency is
expressly noted in the ROD, a fact sheet may h’
needed to notify the public that the contingenc\,
remedy will be implemented.
Q9. Are RCRA financial responsibility requirements
potential ARARs for Superfund?
A. No, because they are considered to be administrative
requirements, not substantive environmental re-
quirements. RCRA financial responsibility require-
ments support implementation of RCRA technical
standards by ensuring that RCRA facility owners or
operators have the financial resources available
to address releases and comply with closure and
post-closure requirements. CERCLA agreements
with PRPs and, ultimately, the Fund itself, achieve
essentially the same purpose.
Q10. RCRA hazardous waste is placed into an existing
pit that had received hazardous waste in the past,
but is not subject to RCRA Subtitle C regulations
because the pit closed before 1980. Would the
minimum technology requirements (MTR) be
applicable?
A. Yes; although the pit is not considered a “new unit,
all surface impoundments (i.e., both new and
existing) are subject to MTR if they receive
hazardous wastes (i.e., wastes that were hazardous as
of November 7, 1984) after November 1988. In
addition, the land disposal restrictions (LDRs)
prohibit placement of restricted wastes (which are
under a national capacity variance) in landfills or
surface impoundments that are not in compliance
with MTR. If such a waste is placed in the existing
waste pit, the pit would have to comply with MTR,
even though it is not a “new unit.” See Superfund
LDR Guide #3: Treatment Standards and
Minimum Technolo iv Requirements Under Land
Disposal Restrictions (LD . Publication 9347.3-
03/FS, July 1989.
III. Clean Water Act (CWA) & Safe Drinking Water Act (SDWA)
Qil. I)o antidegradation laws hr ground water, which are
increasingly common in State laws, mean that the
aquifer must be restored to its original quality before
contamination from the site occurred?
A. In most cases, no. Antidegradation laws are
prospective and are intended to prevent further
det radaiion of water quality. At a CERCLA site,
therefore, a State ground-water antidegradation law
might preclude the injection of partially treated water
into a pristine aquifer. It would not, however,
require cleanup to the aquifer’s original quality prior
to contamination. If more stringent State standards
than those imposed under Federal law are determined
to he ARARs for the site, they would have to he met
(e.g., by meeting the discharge requirements) or
waived (e.g, by the interim remedy waiver). Where
temporary degradation of the ground water may be
required during remedial action, protection should
be provided by restricting access or providing
institutional controls, and EPA response actions
should ultimately result in restoration of the ground
water’s beneficial uses. (Sec ARARs Q’s & A’s:
State Ground-Water Antidegradation Issues ,
Publication 9234.2-1 1/FS, July 1990.)
Q12. There are some situations where an aquifer that is
a current or potential drinking-water source, treat-
able to MCLs at the tap, cannot be remediated to
non-zero MCLCs or MCLs in the aquifer. Would
non-zero MCLGs or MCLs still he relevant and
appropriate?

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A. In general, yes. The non-zero MCLGs and, if none,
the MCLS, are generally relevant and appropriate for
any aquifer that is a potential drinking-water source
(see Highlight 3) (see section 300.430(e)(2)(i)(B)-(D)
of the NCP, 55 at 8848). If they cannot be at-
tained (e.g., because of complex hydrogeology due to
fractured bedrock), an ARAR waiver for technical
impracticability should be used. If attainment of a
non-zero MCLG or MCL is impossible because the
background level of the chemical subject to CERCLA
authority (e.g., a man-made chemical) is higher than
that of the MCLG or MCL, attainment of the MCLG
or MCL would not be relevant and appropriate. (See
CERCLA Compliance With the CWA and SDWA ,
Publication 9234.2-06/FS, January 1990.)
QI3. Many new MCLGs and MCLs will be promulgated or
existing ones revised in upcoming years. Will new or
i-evised MCLGs and MCLs, when promulgated, need
to he incorporated into the remedy, possibly altering
it? Should a proposed non-zero MCLG or MCL he
used as the remediation goal in the ROl)?
A. Under the NCP, if a new rcquircment is promulgated
alter the ROD is signed, and the requirement is
determined to he applicable or relevant and
ppr )pnatc, the remedy should be examined in light
of the new requirement (at the 5-year review or
earlier) to ensure that the remedy is still protective .
If the remedy is still protective, it would not have to
he modified, even though it does not meet the new
requirement. Since non-zero MCLGs and MCLs
often arc a key component in defining rcmcdiation
levels, new or revised MCLGs and MCLs may reveal
that the chosen remedy is not protective. In such
cases, the remedy would have to he modified
accordingly. This could occur at any time after the
ROD is signed -- during remedial design, remedial
action, or at the 5-year review.
However, a new non-zero MCLG or MCL usually
will not mean the remedy must be changed. If the
existing remedy is still within the risk range, even
considering the new MCLG or MCL, the remedy
would not have to be modified because the remedy
is still protective . For example, if the new non-zero
MCLG or MCL represents a risk of 10-6, while the
selected remediation level results in a i0 5 risk, the
remedy is still considered protective.
At some sites, however, a new MCLG or MCL
could require modification to the remedy after
implementation of the remedy has begun. There-
fore, if a proposed non-zero MCLG or MCL is
available before the ROD is signed, the preferred
remedy should be evaluated to determine how the
MCLG or MCL, if promulgated as proposed , would
affect the remedy. Will the preferred remedy
achieve the proposed MCLG or MCL? Could the
remedy achieve the proposed MCLG or MCL with
minor design modifications? Would the proposed
MCLG or MCL require significant changes, such as
requiring remediation in ground water that is
currently deemed fully protective?
The proposed non-zero MCLG or MCL may be
used as a “to-be-considered” (TBC) in establishing a
protective remediation level in the ROD, provided
that: (1) the new standard would make a remedy
based Ofl the current standard unprotective; and (2)
the proposed standard is not controversial or
otherwise is unlikely to change. This reflects the
importance of non-zero MCLGs and MCLs in
Superfund’s determination of protectiveness and as
a cleanup standard for the community. It also
minimizes the need for later changes to the remedy
when changes may he more difficult and ccst to
make. (See CERCLA Compliance With the CWA
and SDWA , Publication 9234.2-06/FS, January
1990.)
Highlight 3:
ARARs FOR GROUND-WATER CLEANUP
Non-zero MCLGs, and, if none, MCLs promulgated
under SDWA, generally will be the relevant and
appropriate standard for ground water that is or
may be used for drinking, considering its use, value,
and vulnerability as described in the EPA’s Ground-
Water Protection Strategy (August 1984), e.g., for
Class I and II aquifers.
Note: In the May 1989 version of this fact s ce’
Question 14 addressed the use of the 106 risk level
when non-zero MCLGs or MCLs exist for some,
but not all, significant contaminants. Question 14
has been omitted from this fact sheet because this
issue is currently being clarified by the Agency.
Final resolution of this issue will be addressed in
guidance in the near future.

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IV. Post-ROD Information and the Administrative Record
Q14. Should remedies be revised to attain requirements of
Federal or State environmental law that are
promulgated or modified after signature of the ROD?
A. In general, no. The requirements that are determined
to be ARARs for a site “freeze” at the time of
signature. Requirements that are newly promulgated
or modified post-ROD need to he attained (or
waived) only when EPA determines that these
requirements are ARARs and that they must be met
in order for the remedy to be protective (see section
300.430(f)(1)(ii)(B)(1) of the NCP). Newly prom-
ulgated or modified requirements will he considered
during the five-year review or sooner, if appropriate,
to determine whether the remedy is still protective.
(See Question 13 of this fact sheet and Question 6 of
the fact sheet entitled ARARs p’s & A’s:, Com-
pliance With the Toxicity Characteristics Ruj ,
Part I , (Publication 9234.2-08/FS, May 1990) for
examples of how the “freezing” regulation applies to
specific ARARs.)
Q15. What ARARs apply if information not known at the
time of ROD signature is discovered post-ROD (e.g.,
RCRA hazardous wastes are identified on the site for
the first time during construction activities)?
A. If, based on the new information, the Region decides
to change the remedy (e.g., in order to assure
protection), the Region must meet or waive all
ARARs identified at that time.
First, Regions must determine whether the new
information is such that the ROD should be revised
(and an Explanation of Significant Differences (ESD)
issued), or amended (and a ROD amendment issued).
If the Region believes that significant, but non-
fundamental, changes should be made in the selected
remedy based on new information (e.g., the discovery
of a new contaminant triggers an MCL that is more
difficult to meet, resulting in a decision to operate
the pump-and-treat system for 15 years instead of 10
years), then an ESD should be issued (see section
300.435(c)(2)(i) of the NCP). If the Region decides
to make a fundamental change in the remedy based
on the new information (e.g., to change from an
engineering control to an incineration remedy), the
process for a ROD amendment must be followed (see
section 30 0.435(c)(2)(ii) of the NCP). Regions
should include in the administrative record file any
documents upon which they base their determinations
to issue an ESD or ROD amendment (see section
300 .825(a)(2) of the NCP). For additional
information on this issue, see Guide to Addressing
Pre-ROD and Post-ROD Changes , Publication
9355.3-O2FS/4, April 1990.
If, however, the Region decides not to revise or
amend the ROD based on the new information,
then no new ARARs apply because the remedy is
not being changed. To the extent that the Region
wishes to document its reasoning on this point (e.g.,
to explain why the remedy remains protective even
taking into account newly-discovered RCRA wastes),
this information could be included in the admini-
strative record file. (Note: section 300.825(a)(1) of
the NCP allows EPA to add documents to the
administrative record file, after ROD signature, that
“concern a portion of a response action decision
that the decision document does not address or
reserves to be decided at a later date.”)
Q16. If a ROD does address an action, location, or
chemical such that the proper set of ARARs could
have been identified prior to the signing of the
ROD, but one or more ARARs were not identified,
how should the Regions respond if those
requirements are identified post-ROl)?
A. The selected remedy would generally not be
required to meet such late-identified requirements.
If the promulgated requirement existed prior to
ROD signature, and the waste, action, or location to
which the requirement potentially applied was also
known at the time of ROD signature, the failure of
a party to identil ’ the requirement as an ARAR
within the meaning of CERCLA, during the public
comment period of the proposed plan, would likely
preclude the party from raising the issue after ROD
signature.
[ Note that section 300 .825(c) of the NCP requires
EPA to consider comments submitted by interested
persons after the close of the comment period only
“to the extent that the comments contain significant
information not contained elsewhere in the
administrative record file which could not have been
submitted during the public comment period and
which would substantially support the need to
significantly alter the response action.” This may he
a difficult test to meet where information on the
requirement was available during the public
comment period, and therefore, in most cases, could
have been brought to the Agency’s attention at that
time.]
With regard to State ARARs, CERCLA Section
121(d)(2)(A)(ii) specifically provides that a
requirement of a State environmental or facility
siting law may be considered to be an ARAR only
if it is identified in a timely manner. (Sections

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300.400(g)(5), 300.5 15(d)(1), and 300.5 15(h)(2) of the
NCP indicate that State ARARs identification must
take place well before the signature of the ROD in
order to be considered “timely.”)
EPA could decide to take a newly-identified require-
ment into consideration on a site-specific basis.
However, because no new information on the waste
composition or nature of the site is being brought
before the Region, it is likely that the risk assessment
performed at the site in question will have considered
all appropriate risks, and that the site is protective of
human health and the environment even in light of
the late-identified regulatory standard. In rare cases
where the Region evaluates the standard and decides
that the remedy should be changed or amended (e.g.,
based on a finding that the ARAR was incorrectly
analyzed and the remedy is not protective), an ESD
or ROD amendment should be considered. In such
cases any new components of the remedy would be
required to attain (or waive) those ARARs
identified at the time the ESD or ROD amendment
is issued. (Note: the ESD or ROD amendment
would be documented in the administrative record
file pursuant to section 300.825(a)(2) of the
NCP.) If the Region were to decide not to change
the remedy, but wanted to memorialize the analysis
of the late-identified requirement, an optional
Remedial Design Fact Sheet could be added to the
post-decision document file. Alternatively, the issue
could be addressed in a new comment period and
the analysis placed in the administrative record file
for the site, as discussed in section 300.825(b) of the
NCP.
V. Contingent Waivers
Q17. What are ‘contingent waivers” and when should they
be used?
A. When sufficient information is available at the time
of ROD signature indicating the possibility that an
ARAR waiver may be invoked at a site (e.g., the
RI/FS indicates that it may be technically impracti-
cable to attain non-zero MCLGs or MCLs in the
ground water based upon final determinations of the
size and scope of the contaminated plume), the lead
agency may consider including a contingent waiver in
the ROD. RODs with contingent waivers should
provide a detailed and objective level or situation at
which the waiver would be triggered. In addition, the
ROD should specify that the contingency is “reserved
to be decided at a later date,” so that if the
contingency is invoked, the resulting documentation
becomes part of the administrative record (see NCP
section 300.825(a)(1), 55 FR at 8861). [ Note: in
some situations, the Agency may not wish to identify
a separate trigger for waivers. For example, in some
ground-water cleanups, the Agency may wish to re-
tain the flexibility to vary pump rates or assess the
effects of temporary shutdown before invoking a
technical impracticability waiver.]
The decision to invoke the contingency should be
documented in a fact sheet which is placed in the
administrative record file. The Region may also
decide to issue a public notice (e.g., in a major local
newspaper of general circulation) that the contin-
gency has been invoked. An ESD is not required to
invoke a contingency specifically contemplated in
the ROD. (See Guide to Developing Superfund No
Action, Interim Action, and Contingency Reme y
RODs , Publication 9355.3-02/FS-3, April 1991, for
a general discussion of contingent remedies.)
NOTICE: The policies set out in this fact sheet are not final Agency action, but are intended solely as guidance.
They are not intended, nor can they be relied upon, to create any rights enforceable by any party in litigation with
the United States. Response personnel may decide to follow the guidance provided in this fact sheet, or to act at
variance with the guidance, based on an analysis of site-specific circumstances. The Agency also reserves the right
to change this guidance at any time without public notice.

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