&EPA
United Stales
Environmental Protection
Agency
Office of
Solid Waste and
Emergency Response
Publication: 9355.3-02FS-4
April 1991
Guide to Addressing Pre-ROD
and Post-ROD Changes
Office of Emergency and Remedial Response
Hazardous Site Control Division OS-220W
Quick Reference Fact Sheet
Section 117(b) of the Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA) contains provisions for addressing and documenting changes to an alternative that occur between
the time the alternative is proposed as the preferred cleanup approach for a site and the final selection of a
remedy in a Record of Decision (ROD). In addition, sections 117(c) and (d) of CERCLA contain provisions
for addressing changes to the remedy that occur after the ROD is signed. The National Oil and Hazardous
Substances Pollution Contingency Plan (NCP) (55 FR 8666-8865, March 8, 1990) includes requirements for
public information and community relations (§300.155), and the preparation and documentation requirements
for remedial investigation/feasibility studies (RI/FSs) and remedy-selection documents (§300.430(c) and (f)(3)).
It also addresses post-ROD information and public comment in sections 300.435(c)(2) and 300.825(b) and (c).
This guide outlines the methods for categorizing pre- and post-ROD changes and the ways in which changes
should be documented. More detailed guidance for pre-ROD changes and both significant and fundamental
post-ROD changes (i.e., Explanations of Significant Differences (ESDs) and ROD amendments) can be found
in Chapters 5 and 8, respectively, of the Interim Final Guidance on Preparing Superfund Decision Documents
(OSWER Directive 9355.3-02).
I. PRE-ROD CHANGES
When a selected remedial action reflects a
significant change(s) from the preferred alternative
presented in the Proposed Plan for the remedial
action, Section 117(b) of CERCLA requires that
these changes be documented. A site-specific
determination of what constitutes a significant (as
opposed to minor) change, and, therefore, the
extent of documentation required, is made after
taking the following factors into consideration: (1)
the information previously made available to the
public; (2) the original description of the
alternatives presented in the Proposed Plan (and
outlined in detail in the RI/FS Report); and (3)
the impact that the changes may have on the
alternative's scope, performance, or cost. (See
NCP preamble, 55 FR 8772.)
Minor changes are those that have little or no
impact on the overall scope, performance, or cost
of the alternative originally presented in the
Proposed Plan as the preferred remedy for the site
or operable unit. (See Highlight 1 for examples of
minor changes).
In contrast to minor changes, significant
changes have a significant or fundamental effect on
HIGHLIGHT 1
EXAMPLES OF MINOR CHANGES
• Based on information received during the
public comment period, the lead agency
determines that the capital cost estimate in
the Proposed Plan was 10 percent too low.
Instead of a cost of $4.7 million the actual
capital cost of the remedy is $5.1 million.
• It was determined that a remedy will require
eight ground-water extraction wells, rather
than six wells as estimated originally in the
Proposed Plan, to achieve cleanup objectives
within the desired time period.
• The volume of material to be excavated and
treated is actually 120,000 cubic yards, rather
than the 110,000 cubic yards estimated
originally in the Proposed Plan.
the scope, performance, and/or cost of the
preferred alternative. They generally involve either
(1) selecting as the remedy an RI/FS alternative
other than the preferred alternative identified in
the Proposed Plan; or (2) substantially modifying
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a component of the previously identified preferred
alternative (e.g., addressing a substantially greater
or lesser volume of waste; addressing a new
exposure pathway; or by encompassing a
substantially greater physical area of the site).
Changes in treatment technologies or processes
that substantially alter the long-term effectiveness
or the short-term effectiveness of the alternative
constitute significant changes of the performance
of the preferred alternative. If the capital or
operation and maintenance costs for the final
alternative are considerably different from the
original estimates, this is considered a significant
change in the cost of the preferred alternative.
DOCUMENTING PRE-ROD CHANGES
Minor changes to the Proposed Plan should be
discussed in the Description of Alternatives section
of the ROD Decision Summary and should be
documented in the Administrative Record File.
The type of documentation required for
significant changes depends on whether or not the
change is a logical outgrowth of the information
available to the public for comment in the
Proposed Plan and the RI/FS Report. A logical
outgrowth occurs where the public could have
reasonably anticipated the change, based on
information available during the public comment
period and the comments submitted. A significant
change would be considered to be a logical
outgrowth where, based on the comments received
during the public comment period, the Agency
selects, from among the alternatives discussed in
the FS and/or Proposed Plan, an alternative (or
parts of alternatives) that differs from the
preferred alternative in the Proposed Plan. A
significant change that is a logical outgrowth of
information available to the public in the Proposed
Plan and RI/FS Report should be documented at
the end of the Decision Summary of the ROD in
the Documentation of Significant Changes section.
Additional public notice or comment on this type
of change is not necessary. Examples of types of
significant changes that are logical outgrowths are
presented in Highlight 2.
In those limited situations in which a significant
change is not a logical outgrowth of the Proposed
Plan and its supporting information (i.e., the
public could not reasonably have anticipated the
HIGHLIGHT 2
TYPES OF SIGNIFICANT CHANGES
THAT ARE LOGICAL OUTGROWTHS
• Changing a Component - In response to a
commenter, a change in the preferred
alternative's cost, timing, level of
performance, or applicable or relevant and
appropriate requirements (ARARs) that
could have been anticipated by other
members of the public.
• Combining Components of Alternatives --
In response to comments, the final remedy
combines one component of the preferred
alternative (e.g., for ground-water
remediation) and a component of a
different alternative (e.g., soil remediation)
presented in the RI/FS Report.
• Selecting a Different Alternative - An
alternative evaluated in the FS, other than
the preferred alternative in the Proposed
Plan, is determined to provide the most
appropriate balance of tradeoffs among
alternatives, with respect to the nine criteria,
in light of public comments.
change that is made) a revised Proposed Plan that
presents the new preferred alternative should be
issued for public comment (NCP section
300.430(f)(3)(ii)(B)). The revised Proposed Plan
must be prepared in accordance with the
requirements of both CERCLA section 117 and
the NCP. Appropriate supporting material that
provides the necessary engineering, cost, and risk
information for the new alternative(s), and
discusses how the new alternative(s) compares to
the other alternatives with respect to the nine
evaluation criteria, should be provided in the
revised Proposed Plan. (It may be appropriate to
provide this information as a supplement to the
RI/FS Report.) In addition, significant changes to
the revised Proposed Plan must be documented at
the end of the Decision Summary of the ROD in
the Documentation of Significant Changes section.
Examples of types of significant changes that
require a new Proposed Plan, additional public
comment, and documentation in the ROD are
presented in Highlight 3.
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HIGHLIGHT 3
TYPES OF SIGNIFICANT CHANGES THAT
ARE NOT LOGICAL OUTGROWTHS
• Selection of a new alternative that was not
previously considered and discussed and is not
a logical outgrowth ("e.g., combination) of
considered alternatives.
• Significant change to a component of the
selected alternative resulting in fundamental
changes to the remedy - A previously
unidentified ARAR now requires altering the
remedy design, thus substantially altering the
feasibility or performance of the alternative.
II. POST-ROD CHANGES
After a ROD is signed, new information may be
received or generated during the RD/RA that
could affect how the Agency believes the remedy
selected in the ROD should be implemented.
Where information is submitted by a PRP, the
public, or the support agency after a ROD is
signed, the lead agency should consider this
information when each of the following criteria are
met (NCP section 300.825(c)):
• The comments contain significant
information;
• The information is not contained elsewhere
in the Administrative Record File;
• The information could not have been
submitted during the public comment period;
and
• The information substantially supports the
need to alter significantly the response action.
The lead agency may also evaluate whether a
change to the remedy is warranted on its initiative,
even where the requirements of NCP section
300.825(c) are not met.
The lead agency's categorization of a change,
which will ultimately affect the documentation
procedure required, is a site-specific determination
and should consider the following factors:
. Does the change significantly alter the scope
of the remedy (e.g., the physical area of the
response, remediation goals, type and volume
of wastes)?
. Would the change alter the performance
(e.g., treatment levels to be attained) and
thus'raise concerns about the protectiveness
or long-term effectiveness of the remedy that
could not have been anticipated based on
information in the ROD?
• Are the changes in costs of such a nature
that they could not have been anticipated
based on the estimates in the ROD and the
recognized uncertainties associated with the
hazardous waste engineering process
selected?
Based on this evaluation and depending on the
extent or scope of modification being considered,
the lead agency determines that the post-ROD
change is (1) non-significant or minor; (2)
significant; or (3) fundamental. Examples of these
three types of post-ROD changes are presented in
Highlight 4 (see also NCP preamble, 55 FR 8772).
Each category is associated with a different
documentation procedure, as discussed below.
DOCUMENTING POST-ROD CHANGES
If non-significant or minor changes are made,
they should be recorded in the post-decision
document file. If the lead agency chooses, non-
significant changes can be documented for the
public in an optional Remedial Design Fact Sheet.
If significant changes are made to a component of
the remedy in the ROD, these changes should be
documented in an Explanation of Significant
Differences (BSD), as required by Section 117(c)
of CERCLA, If fundamental changes are made to
the overall remedy, they should be documented in
a ROD amendment.
EXPLANATION OF SIGNIFICANT
DIFFERENCES (ESDs)
When documenting significant changes made to
a remedy, the lead agency must comply with the
procedures specified in NCP section
300.435(c)(2)(i). An BSD should be prepared to
provide the public with an explanation of the
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HIGHLIGHT 4
EXAMPLES OF POST-ROD CHANGES
1) Minor. Testing during remedial design
shows that the volume of soil requiring
treatment is 75,000 cubic yards rather
than the 60,000 estimated in the ROD.
However, the cost of the remedy will
only increase by 5 percent because of
economies of scale that can be realized.
2) Significant. Residuals from a
treatment operation were not expected
to be hazardous and it was planned to
dispose of them on site in a Subtitle D
unit. However, testing after treatment
determines that the residuals are
hazardous wastes, and off-site disposal
at a Subtitle C facility is required.
3) Fundamental. The in-situ soil washing
remedy selected in the ROD proves to
be infeasible to implement after testing
during remedial design. A decision is
made to excavate and thermally treat
the waste instead.
nature of the changes made to the remedy, to
summarize the information that led to making that
change, and to affirm that the revised remedy
complies with the statutory requirements of
CERCLA section 121. Generally, a new nine
criteria analysis is not required; however, the ESD
should include a statement that the ROD meets
ARARs identified at the time the original ROD
was signed (NCP section 300.430(f)(l)(ii)(B)(l)
and (2)).
It may also be appropriate to prepare an ESD
document when the lead agency decides to exercise
a contingency remedy that was not sufficiently
described in the ROD (see Guide to Developing
Superfund No Action, Interim Action, and
Contingency Remedy RODs, Directive #9335.3-
02FS-3, March 1991).
During the period when the ESD is being
prepared and made available to the public, the lead
agency may proceed with the pre-design, design,
construction, or operation activities associated with
the remedy. The remedy can continue to be
implemented in this case because the ESD
represents only a notice of change, and the Agency
is not reconsidering the overall remedy. The lead
agency should consult with the support agency, as
appropriate, prior to issuing an ESD (see NCP
section 300.435(c)(2)). Although not specifically
required by CERCLA section 121 (f), it is also
recommended for the lead agency to provide the
support agency the opportunity to comment and to
summarize the support agency's comments in the
ESD. The agency also should publish a notice of
availability and a brief description of the ESD in a
local newspaper of general circulation (as required
by CERCLA Section 117(c)), and make the ESD
available to the public by placing it in the
administrative record file and information
repository. A formal public comment period is not
required when issuing an ESD. The Office of
Emergency and Remedial Response (OERR)
recommends issuing the ESD in a fact sheet format
as outlined in Highlight 5. The appropriate
Regional Manager may sign an ESD. (NOTE: In
some cases, an additional public comment period
or public meeting may be held voluntarily on a
planned ESD (see NCP section 300.825(b)). This
may be useful where there is considerable public or
PRP interest in the matter.)
ROD AMENDMENT
In a few cases, new information submitted by
the public post-ROD or developed by the lead
agency during the remedial design/remedial action
leads to the reconsideration of the hazardous waste
management approach selected in the ROD. Such
reconsideration of the remedy constitutes a
fundamental change. When fundamental changes
are made to the remedy selected in a ROD, the
lead agency should conduct the public participation
and documentation procedures specified in NCP
section 300.435(c)(2)(ii).
In general, the introductory sections of the
ROD do not need to be readdressed in the
amended ROD. The focus of the amendment
should be on:
• Documenting the rationale for the
amendment;
• Evaluating the original selected remedy and
the new proposed remedy using the nine
evaluation criteria; and
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HIGHLIGHT 5
SAMPLE FORMAT FOR ESD
Introduction: Begin with an introduction to the site and a statement of purpose for the ESD, including:
Site name and location;
Identification of lead and support agencies;
Citation of CERCLA section 117(c) and NCP section 300.435(c)(2)(i);
Summary of the circumstances that gave rise to the need for an ESD;
• Statement that the ESD will become part of the Administrative Record File (NCP 300.825(a)(2)); and
• Address of location where the File is available and hours of availability of the File.
Summary of Site History, Contamination Problems, and Selected Remedy: Summarize the following aspects
of the site or operable unit:
• The contamination problems and site history, including the date on which the ROD was signed; and
• The selected remedy, as originally described in the ROD.
Description of the Significant Differences and the Basis for those Differences: Summarize the significant
changes to the remedy and the basis for making those changes, including:
• Information that gave rise to significant differences from the selected remedy as it was originally specified,
which could include the following: (1) the results of treatability studies; or (2) other information developed
or provided during the remedial design process that supports the change. Reference any information in the
Administrative Record File that supports the need for the change.
• Description of the significant differences between the remedy as presented in the ROD and the action now
proposed. As appropriate, this description should summarize the differences in scope, performance, or cost
between the original and modified remedies, as nece_ssary. For example:
Original Remedy
Excavation and incineration of 7,500
cubic yards of contaminated soil.
Air stripping and ground-water
restoration.
Modified Remedy
Excavation and incineration of 11,500
cubic yards of contaminated soil.
Carbon adsorption for ground-water
restoration.
Support Agency Comments: Include a summary of support agency comments on the ESD.
Affirmation of the Statutory Determinations: Affirm that the modified remedy continues to satisfy the
requirements of CERCLA section 121 by including a statement such as the following:
"Considering the new information that has been developed and the changes that have been made to the
selected remedy, the [lead and support agencies] believe that the remedy remains protective of human health
and the environment, complies with federal and state requirements that were identified [(1) in the ROD/(2) in
this ESD] as applicable or relevant and appropriate to this remedial action (at the time [(1) the original
ROD/(2) this ESD] was signed), and is cost-effective. In addition, the revised remedy utilizes permanent
solutions and alternative treatment (or resource recovery) technologies to the maximum extent practicable for
this site.'1
Public Participation Activities: Document compliance with the appropriate public participation requirements:
• That notice has been issued that the contents of the Administrative Record File are available for public
review and comment; and
• The date of planned public information meetings, if applicable. (EPA is not required to hold public
meetings on ESDs but may choose to do so if warranted by public interest.)
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• Providing assurances that the proposed
remedy satisfies the statutory requirements.
The format for a ROD amendment is presented in
Highlight 6.
If the ROD to be amended addresses the entire
response action for the site or a series of operable
units (e.g., soil, surface water, and ground water),
only that portion of the remedy being changed
(e.g., ground water) requires an amendment.
Under SARA §121, for the portion of the ROD
being amended, a new nine criteria analysis,
including a new ARARs analysis, will be necessary.
Portions of the analysis in the original ROD can
be cross-referenced, where appropriate. Therefore,
the amount of information included in a ROD
amendment is a function of the type of change
made to the remedy and the rationale for that
change. RD/RA activities being conducted on
other portions of the site or operable units not
proposed for changes may continue during the
amendment process.
When there are fundamental changes proposed
to the ROD, the lead agency should conduct the
public participation and documentation procedures
conducted for the original ROD (e.g., Proposed
Plan, public comment period, Responsiveness
Summary). (See NCP section 300.435(c)(2)(ii)(A)-
(H).) When a fundamental change is proposed as
a result of negotiations with a PRP, the Proposed
Plan for the ROD amendment should be released
for public comment concurrently with the consent
decree. (If a change is made after a consent decree
has been entered, involvement of the court may be
required. Site managers should check with their
regional counsel on how this may be
accomplished.) ROD amendments should be
signed by the Regional Administrator.
HIGHLIGHT 6
SAMPLE FORMAT FOR ROD AMENDMENT
Introduction
• Site Name and Location;
• Identify lead and support agencies;
. Cite CERCLA §117 and NCP 300.435(c)(2)(ii);
• Date of ROD signature;
• Summarize circumstances that led to the need for a
ROD amendment;
• State that ROD amendment will become part of
the Administrative Record File (NCP section
300.825(a)(2)); and
• Provide address where File is available for public
review and hours of availability.
Reasons for Issuing the ROD Amendment
• Identify remedy selected in ROD; and
• Summarize rationale for changing remedy selected
in the ROD.
Description of the New Alternatives
• Describe the original selected remedy and the new
proposed remedies in the same manner requested
in a standard ROD, highlighting the:
• Treatment components;
• Containment or storage components;
• Ground-water components;
• General components; and
• Major ARARs.
Evaluation of Alternatives
• Profile the original selected remedy and the new
proposed remedies against the nine criteria.
Statutory Determinations
• Provide a statement that the modified remedy
satisfies CERCLA §121.
NOTE: See guidance on preparing RODs for scope
and detail of subjects to be addressed under each
point.
NOTICE: The policies set out in this memorandum 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. EPA officials
may decide to follow the guidance provided in this memorandum, or to act at variance with the guidance, based on
an analysis of specific site circumstances. The Agency also reserves the right to change this guidance any time
without public notice.
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