United States
Environmental Protection
Agency
Office of
Solid Waste and
Emergency Response
Directive: 9355.0-27FS
April 1990
• Treat principal threats, wherever practicable. Principal threats
for which treatment is most likely to be appropriate are
characterized as:
- Areas contaminated with high concentrations of toxic com-
pounds;
- Liquids and other highly mobile materials;
- Contaminated media (e.g., contaminated ground water,
sediment, soil) that pose significant risk of exposure; or
- Media containing contaminants several orders of magni-
tude above health-based levels.
> Appropriate remedies often will combine treatment and con-
tainment. For a specific site, treatment of the principal
threat(s) may be combined with containment of treatment
residuals and low-level contaminated material.
> Containment will be considered for wastes that pose a relatively
low long-term threat or where treatment is impracticable. These
include wastes that are near health-based levels, are substan-
tially immobile, or otherwise can be reliably contained over long
periods of time; wastes that are technically difficult to treat or
for which treatment is infeasible or unavailable; situations
where treatment-based remedies would result in greater over-
all risk to the human health or the environment during implem-
entation due to potential explosiveness, volatilization, or other
materials handling problems; or sites that are extraordinarily
large where the scope of the problem may make treatment of all
wastes impracticable, such as municipal landfills or mining
sites.
>• Institutional controls are most useful as a supplement to engi-
neering controls for short- and long-term management. Institu -
tional controls (e.g. deed restrictions, prohibitions of well con-
struction) are important in controlling exposures during reme-
dial action implementation and as a supplement to long-term
engineering controls. Institutional controls alone should not
substitute for more active measures (treatment or containment)
unless such active measures are found to be impracticable.
>• Innovative technologies should be considered if they offer the
potential for comparable or superior treatment performance,
fewer/lesser adverse impacts, or lower costs for similar levels of
performance than demonstrated technologies.
>• Ground waters will be returned to their beneficial uses within
reasonable periods of time wherever practicable.
April 1990-1
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. .. Exhibit 2 . .... .
Key Steps hi the Development o' RemedlalA11ernativea
Develop Preliminary RemediaHon GoalS
. Health-based remediation goaJs (8.g.. 10.0 excess cancer risk as
point of departure, AFtARs: resulting in X ppm
. .. .
.....8..:......................."'...:......
. >X ppm .
. . .
",".","',' "."' .'....',
Identify Principal Threats!ha1 are Candidat" for Treatment
. Treat Iiquid8, highly toxic materials, n~nly mobil. materials
Exceptions include large municipaJ
landfills. areas where contaminants
are inaccessible. or othe, situations
where treatment is "01 i~lementabl.
Contain Treatment
Residuals and
Remaining Material
,
P aniaily Treat
Ide"tify Remedial
Atternatives lor
Delailed A"81y....
and Remedy
Seiection
. Treat to lev.is Ina. can
be reliably contair"ed
,
demonstrate that statutory require-
ments have been satisfied (Sec.
300.430(£)(1)). Each of these as-
pects of EPA's remedy selection
approach are described below.
GOAL AND EXPECTATIONS
OF THE REMEDY SELECTION
PROCESS
The national goal of the remedy
selection process is "to select reme-
dies that are protective of human
health and the environment, that
maintain protection over time, and
that minimize untreated waste"
(NCP Sec. 300.430(a)(1)(i)).
2 - OSWER Directive 9355.0-27FS
ExcectlOns
. Small volumes
. Sensitive exposure
. Containment unreliable
Fully Treal
. Treat 10 levels for
which access
restrictions are nOI
necessary
While protection of human
health and the environment can be
achieved through a variety ofmeth-
ods, this goal reflects CERCLA' s em-
phasis on achieving protection
through the aggressive, but realis-
tic use of treatment. The 1990 NCP
presents EP A's expectations regard-
ing circumstances under which
treatment, as well as engineering
and institutional controls, are most
likely to be appropriate (Sec.
300.430(a)(1)(iii), see Exhibit 1).
These expectations are intended pri-
marily to assist in focusing the de-
velopment of alternatives in the FS
(see The Feasibility Study: Devel-
opment and Screening of Alterna-
tives, OSWER Directive 9355.3-
01FS). These expectations do not
substitute for site-specific balanc-
ing of the nine criteria to determine
the maximum extent to which treat-
ment can be practicably used in a
cost-effective manner for a operable
unit.
Exhibit 2 illustrates the alter-
natives development process, as
shaped by the expectations. The
process begins with the identifica-
tion of preliminary remediation
goals, which provide initial esti-
mates of the contaminant concen-
trations/risk levels of concern. Based
on ARARs, readily available toxic-
ity information, and current and fu-
ture land use, preliminary remedia-
tion goals are initial health-based
levels and are used to define site ar-
eas that may require remedial ac-
tion (Le., action areas). Areas on-
site with contaminant concentra-
tions several orders of magnitude
(e.g., 2) above these preliminary re-
mediation goals are candidate ar-
eas for treatment. Areas onsi te with
contaminant concentrations within
several orders of magnitude of these
preliminary remediation goal levels
are candidate areas for containment.
The remediation goals, action ar-
eas, and target treatmentJcontain-
ment areas are refined throughout
the RVFS process as additional in-
formation becomes available. The
final determination of remediation
goals, action areas, and the appro-
priate degree of treatment and con-
tainment are made as part of the
remedy selection.
THE REMEDY SELECTION
PROCESS
Overview
The remedy selection process
begins with the identification of a
preferred alternative from among
those evaluated in detail in the FS
by the lead agency, in consultation
with the support agency. The pre-
ferred alternative is presented to
the public in a Proposed Plan that is
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~..
EXHIBIT 3: NINE EVALUATION
CRITERIA
5.
Cost includes estimated capital and
operation and maintenancerosts, and
net present worth costs.
EPA has developed nine criteria to
be used to evaluate remedial alterna-
tives to ensure all important considera-
tions are factored into remedy selection
decisions. These criteria are derived
from the statutory requirements of
Section 121, particularly the long-term
effectiveness and related ronsiderations
specified in Section 121(b)(1), as well as
other additional technical and policy
considerations that have proven to be
important for selecting amongremedial
alternatives.
Threshold Criteria
The two most important criteria
are statutory requirements that must
be satisfied by any alternative in order
for it to be eligible for selection.
1.
Overall protection of human health
and the environment addresses
whether or not a remedy provides
adequate protection and describes
how risks posed through each
exposure pathway(assuming a rea-
sonable maximum exposure) are
eliminated, reduced, or rontrolled
through treatment, engineering
controls, or institutional controls.
2.
Compliance with applicable or rele-
vant and appropriate requirements
(ARARs) addresses whether a rem-
edy will meet all ofthe applicable
or relevant and appropriate require-
ments of other Federal and State
environmental laws or whether a
waiver can be justified.
Primary Balancing Criteria
Five primary balancing criteria are
used to identify major trade-offs between
remedial alternatives. These trade-offs
are ultimately balimced to identify the
preferred alternative and to select the final
remedy.
1.
Long-term effectiveness and
permanence refers to the ability of a
remedy to maintain reliable protec-
tion of human health and the envi-
ronment overti me, once cleanu p goals
have been met.
Modifying Criteria
These criteria may not be considered
fully until after the formal public comment
period on the Proposed Plan and RJ/FS
report is romplete, although EPA works
with the State and rommu nity throughout'
the project.
1.
State acceptance addresses the sup-
port agency's comments. Where the
State or other Federal agency is the
lead agency, EPA's acceptance of the
selected remedy should be addressed
under this criterion. State views on
compliance with State ARARs are
especially important.
2.
Reduction of toxicity, mobility, or
volume through treatment is the an-
ticipated performance of the treat-
ment technologies a remedy may
employ. .
Community acceptance refers to the
public's general response to the alter-
natives described in the Proposed Plan
and the RI/FS report.
The 1990 NCP at 55 FR ~
describes how the detailed analysis of al-
ternatives is to be performed using these
criteria. The detailed analysis is the infor-
mation base upon which the remedy selec-
tion decision is made. Chapter 7 of the
"Interim Final Guidance for Conducting
Remedial Investigations and Feasibility
Studies Under CERCLA" (October 1988)
provides further detail on the process.
2.
issued for comment along with the
RI/FS. Upon receipt of public com-
ments on the Proposed Plan, the
lead agency consults with the sup-
port agency to determine if the pre-
ferred alternative remains the most
appropriate remedial action for the
site or operable unit. The final
remedy is selected and documented
in a Record of Decision.
Considering the Nine Criteria
The identification of a preferred
alternative and final selection of a
remedy is derived from considera-
tion of nine evaluation criteria in
three major steps, as described in
the 1990 NCP (Sec.
300.430(f)( l)(ii)(E)). The nine crite-
ria are presented in Exhibit 3. The
steps in which the criteria are con-
sidered are depicted in Exhibit 4
and discussed below.
3.
Short-term effectiveness addresses the
period oftime needed to achieve pro-
tection and any adverse impacts on
human health and the environment
that may be posed during the con-
struction and implementation period,
until cleanup goals are achieved.
4.
I mplementability is the technical and
administrative feasibility of a rem-
edy, including the availability of ma-
terials and services needed to imple-
ment a particular option.
Threshold Criteria
The first step of remedy selec-
tion is to identify those alternatives
that satisfy the threshold criteria.
Only those alternatives that pro-
vide adequate protection of human
health and the environment and
comply with ARARs (or justify a
waiver) are eligible for selection.
Alternatives that do not satisfy the
threshold criteria should not be
evaluated further.
Primary Balancing Criteria
The second step involves the
balancing of tradeoffs among pro-
tective and ARAR-compliant alter-
natives with respect to the five pri-
mary balancing criteria (and modi-
fying criteria, if known). In this
step, alternatives are compared with
each other based on their long-term
effectiveness and permanence, re-
duction in toxicity, mobility, or vol-
ume achieved through treatment,
implementability, short-term effec-
tiveness, and cost. The sequence in
which the criteria are generally con-
sidered, and pertinent considera-
tions related to each, are noted be-
low.
1.
Long-term effectiveness and
permanence is a major theme of
CERCLA Section 121, and,
therefore, is one ofthe two most
important criteria used during
remedy selection to determine
the maximum extent to which
permanence and treatment are
practicable. This factor will
often be decisive where alterna-
tives vary significantly in the
types of residuals that will
remain on site and/or their re-
spective long-term management
controls.
April 1990 - 3
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Exhibit 4
THRESHOLD
CRITERIA
BALANCING I
CRITERIA
Evaluate:
. Long-term Effectiveness
. Reduction oIT.M.V.
. Short-term Effectiveness
. Implementability
. Cost
Choose Preferred Altemative:
. . Balancing across Criteria
. Emphasize Long-Term
Effectiveness and Reduction of
T.M.V.
Proposed Plan Issued for Comment
MODIFYING
CRITERIA
I
State and
Community
Acceptance
Selected Remedy
2. Reduction in the toxicity, mobil-
ity, or volume of contaminants
achieved through the applica-
tion of treatment technologies
is the other criterion that will
be emphasized during remedy
selection in determining the
maximum extent to which per-
manent solutions and treatment
are practicable. Remedies that
use treatment to address mate-
rials comprising the principal
threats posed by a site are pre~
ferred over those that do not.
Treatment as part of CERCLA
remedies should general1y
achieve reductions of 90 to 99
percent in the concentrations or
mobility of individual contami-
nants of concern. There will,
however, be situations where
reductions outside the 90 to 99
percent range will be appropri-
ate to achieve site-specific re-
mediation goals.
3. The short-term effectiveness of
an alternative includes consid-
eration of the time required for
each alternative to achieve pro-
tection, as well as adverse short-
term impacts that may be posed
bytheirimplementation. Many
potential adverse impacts can
be avoided by incorporating
mitigative steps into the alter-'
4 - OSWER Directive 9355.0-27FS
native. Poor short-term effec-
tiveness can weigh significantly
against an option and can, in
fact, result in an alternative
being rejected as unprotective if
adverse impacts cannot be ade-
quately mitigated.
4. ImplementabHityis particularly
important for evaluating reme-
dies at sites with highly hetero-
geneous wastes or media that
make the performance of cer-
tain technologies highly uncer-
tain. Implementability is also
significant when evaluating
technologies that are less proven
and remedies that are depend-
ent on a limited supply offacili-
ties (e.g., TSCA - perm i tted land
disposal facility), equipment
(eug., in-situ vitrification units),
or experts. .
5. Cost may playa significant role
in selecting between options that
appear comparable with respect
to the other criteria, particu-
larly long-term effectiveness and
permanence, or when choosing
among treatment options that
provide similar performance.
Cost generally will not be used
to determine whether or not
principal threats will be treated,
except under. special circum-
stances that make treatment
impracticable (see expecta-
tions). Cost can never be used to
pick a remedy that is not protec-
tive.
Modifying Criteria
If known at the completion of
the RI/FS, state (support agency)
and community acceptance of the
alternatives should be considered
with the results of the balancing
criteria evaluation to identify the
preferred alternative. After the
public comment period, state and
community acceptance are again
considered, along with any new in-
formation, and may prompt modifi-
cation of the preferred alternative.
-------
Exhibit 5
Relationship of the Nine Criteria to the Statutory Findings
I":::':'::::::::::::::~'::~~~:::::::~::'~'~"':::':J::"::!~~:g.:'Qi,-~gB!I::':::'..~!:::::'::::::~::::::::~.:::'~::':':':.~::.:::!:.II:~11Ym~:Bi1::fi!~.P.JBg~::.'1
:>- PROTECTION OF HUMAN HEALTH
AND THE ENVIRONMENT
:>- COMPLIANCE WITH ARARs OR
JUSTIFICATION OF A WAIVER
PROTECTION OF HUMAN HEALTH
AND THE ENVIRONMENT
COMPLIANCE WITH ARARs
- - - - - - - - - - - - - - - - - - - - - - - - - - -.
I
I
:$
LONG-TERM EFFECTIVENESS :1
AND PERMANENCE I
.: TOXICITY, MOBILITY, OR ~
¥~~~~~~~~~~i~ENNT ~:::.~:::'::::.'
SHORT-TERM EFFECTIVENESS
. 0''',',",",",",",,,',',",",",",",",",",',',',',",",',",",'.",','...",',',','.".'.'.'.'.".".".".'.".'.".'.".'.','.'.-.'.',',',',',','.',',',',','...','.',',',',',',',',',',',',',',',',',','.'.',
IMPLEMENT ABILITY
COST-EFFECTIVENESS
UTILIZATION OF PERMANENT
;.....> SOLUTIONS AND TREATMENT OR
I RECOVERY TO THE MAXIMUM
I EXTENT PRACTICABLE rMEpW)
I COST '.
~
, :-.""",",","".";';';';';.,'",';.,';',"'"",.:.;.",,;';';';',';';':';';';';';';';';';';';';',';';';';';';',';';',';',';';';';',';"';';"""';""';';';""':".;.;.;.;.;...;.;.;.;.;::
I
I STATE AGENCY ACCEPTANCE
: COMMUNITY ACCEPTANCE
I
---------------------------.
Identification of a Preferred
Alternative
Once the relative perfonnance
of the protective and ARAR-compli-
ant alternatives under each crite-
rion has been established, prelimi-
nary detenninations of which op-
tions are cost-effective and which
alternatives utilize penn anent so-
lutions and treatment technologies
to the maximum extent practicable
are made to identify the preferred
alternative. Exhibit 5 illustrates
the relationship between the nine
criteria and the statutory require-
ments for remedy selection.
Cost-effectiveness is detennined
by comparing the costs of all alter-
natives being considered with their
overaH effectiveness to determine
whether the costs are proportional
to the effectiveness achieved. Over-
all effectiveness for the purpose of
PREFERENCE FOR TREATMENT
AS A PRINCIPAL ELEMENT OR
EXPLANATION AS TO WHY
PREFERENCE NOT SATISFIED
this detennination includes long-
tenn effectiveness and pennanence;
reduCtion of toxicity, mobility, and
volume through treatment; and
short-tenn effectiveness. More than
one alternative can be cost-effec-
tive.
The detennination of which cost-
effective alternative utilizes penna-
nent solutions and treatment to the
maximum extent practicable is a
risk management judgment made
by the decision maker who balances
the tradeoffs among the alterna-
tives with respect to the balancing
criteria (and modifying criteria to
the extent they are known). As a
general rule; those criteria that dis-
tinguish the alternatives the most
will be the most decisive factors in
the balancing. See Exhibit 6 for a
summary of criteria likely to be im-
portant in certain site situations.
The alternative detennined to pro-
vide the best balance of trade-offs,
as considered in light of the statu-
tory mandates and preferences, as
well as the NCP goal and expecta-
tions, is identified as the preferred
alternative and presented to the
public for comment in a Proposed
Plan.
Final Selection of Remedy
Upon receipt of public com-
ments, the preferred alternative is
reevaluated in light of any new in-
fonnation that has become avail-
able, including State and commu-
nity acceptance, if previously un-
known. This newinfonnation should
be considered to detennine whether
an option other than the preferred
alternative better fulfills the statu-
tory requirements. The decision- ;
maker's final judgment is docu-
mented in a Record of Decision.
April 1990 - 5
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v
Exhibit 6
EXAMPLES OF PROMINENT CRITERIA AND EXPECTATIONS
FOR SELECTED SITE SITUATIONS
SITUATION
Small area of high levels of toxic contaminants
(e.g., lagoon, hot spots)
Highly mobile contaminants (e.g., liquids, vola-
tiles, metals)
Very large volume of material contaminated
marginally above health-based levels (e.g., mine
tailings one order of magnitude above health-
based levels in soil)
Complex mixture of heterogeneous waste
without discrete hot spots (e.g., heterogeneous
municipal landfill waste)
Soils contaminated with high concentrations
ofVOCs
Contaminated ground water
PROMINENT CRITERIA
EXPECTED RESm,T OF REMEDY
SELECTION-
Long-term effectiveness,
Reduction of toxicity , mobility, or vol-
ume through treatment
Treatment- is preferred when highly toxic mate-
rial is a principal threat at a site
Long-term effectiveness,
Reduction of mobility through treat-
ment
Treatment is preferred when highly mobile
material is a principal threat at a site
Implementability,
Cost
Containment may afford high level oflong-term
effectiveness; treatment may be difficult to im-
plement because of insufficient treatment ca-
pacity for large volume of material, and cost of
treatment may be prohibitive due to large scope
of site
Implementability,
Short-term effectiveness,
Cost
Treatment of heterogeneous waste often diffi-
cult or infeasible, reducing implementability;
containment avoids short-term impacts and un-
certainties associated with excavation; cost of
treatment may be prohibitive
Long-term effectiveness,
Short-term effectiveness
In-situ treatment may be preferred over excava-
tion because of negative short-term impacts and
high cost of excavation
Long-term effectiveness,
Short-term effectiveness
Ground waters should be returned to beneficial
use as soon as is practicable
- These are only examples and have been highly simplified for illustration purposes. They are not intended to prescribe certain remedies
for certain situations. -
NOTICE: The policies set out in this memorandum are intended solely for the guidance of Government personnel. They are not intended, nor can they be relied
upon, to create any rights enforceable by any party in litigation with the United States. EPA officials may decide to follow the guidance provided in this
memorandum, or to act at variance with the guidance, baaed on an analysis ofspecilic site circumstances. Remedy selection decisions are made and justified on
a case-specific basis. The Agency also reserves the right to change this guidance at any time without public notice.
6 - OSWER Directive 9355.0-27FS
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