OSUER Directive '^S^f.L-
A COMPARATIVE ANALYSIS OF
REMEDIES SELECTED IN THE
SUPERFUND PROGRAM
DURING FY 87, FY 88, AND
FY89
June 20, 1990
This report has been drafted by the Office of Waste Programs Enforcement and the
Office of Emergency and Remedial Response in response to the request made from
Senators Lautenberg and Durenberger
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TABLE OF CONTENTS
SECTION PAGE
Executive Summary i
1.0 Introduction 1- 1
1.1 Purpose and Scope 1- 1
1.2 Framework for Remedy Selection 1- 2
1.3 How PRPs May Potentially Influence Remedy
Selection 1- 2
1.4 Analytical Approach 1- 3
1.5 Contents of This Report 1- 4
2.0 General Analysis 2- 1
2.1 Purpose and Scope 2- 1
2.2 Methodology 2-1
2.2.1 Site Classification 2- 2
2.2.2 Lead Identification 2- 6
2.2.3 Type of Remedy 2-7
2.2.4 Treatment Approaches for Superfund
Source-Control 2- 8
2.2.5 Qualifications and Limitations 2-10
2.3 Findings 2-13
3.0 Paired Analysis 3- 1
3.1 Purpose and Scope 3- 1
3.2 Methodology 3-1
3.2.1 Site Selection Process 3- 1
3.2.2 Site Compa .son Process 3- 4
3.3 Findings 3- 5
4.0 Next Steps 4-1
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LIST OF FIGURES
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Figure 10
Figure 11
Figure 12
Figure 13
Relative Proportions of 16 Site Types
Changing Proportion of Site Types by
Fiscal Year
Number of Sites by Site Type - RI/FS Lead
Number of Sites by Site Type - RD/RA Lead
Treatment Selected by Fiscal Year
Remedy Selection Trends are Consistent
with NCP Expectations
Remedy Selected for Fund-lead RI/FS RODs
Remedy Selected for Enforcement-lead
RI/FS RODs
Remedy Selected Where RD/RA is Expected
Fund-lead
Remedy Selected Where RD/RA is Expected
Enforcement-lead
Average Cost of RODs by RI/FS Lead
Average Cost of RODs by RD/RA Lead
Mean Cost and Standard Deviation for
Each Site Type
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LIST OF TABLES
Table
Table -
Table
Table
Table
Table
Table
Table
Table
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7
8
9
Table
Table
Table
The Sixteen Site Type Categories for the
General Analysis
Percent of RODs Selecting Treatment for
Fund-lead RI/FSs
Percent of RODs Selecting Treatment for
Enforcement-lead RI/FSs
Percent of RODs Selecting Treatment for
Fund-lead RD/RA
Percent of RODs Selecting Treatment for
Enforcement-lead RD/RA
Innovative Technology Selection Trends
in Treatment RODs
Innovative Technology Selection Trends
for Fund-lead RI/FSs
Innovative Technology Selection Trends
for Enforcement-lead RI/FSs
Average Cost of Final Source Control
Remedies Selected
10 Average Cost of RODs by RI/FS Lead
11 Average Cost of RODs by RD/RA Lead
12 Factors Affecting Remedy Selection
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Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
Appendix F
OSWER Directive 9835.13
LIST OF APPENDIXES
Statistical Methods
Technology Selection Trends
Details of Cost Analysis
Summary Comparisons of Sites in Four Sites Categories
NCP Expectations for Treatment
Treatment versus Containment Comparison
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LIST OF REFERENCES
1. FY 1987, 1988, and 1989 ROD Annual Reports
2. All RODS in FY 1987, 1988, and 1989
3. RI/FS and Risk Assessments for Paired Sites
4. Data Base Summary and Reports compiling ROD Annual Report Data
and Correlations
o "Data Base Summary
o Treatment vs. Containment by RI/FS lead
o Treatment vs. Containment by RD/RA lead
5. Comprehensive Environmental Response, Compensation, Liability
Act (CERCLA), 1980 and Superfund Amendments and
Reauthorization Act (SARA), 1986
6. National Contingency Plan - 1985
Proposed National Contingency Plan - 1988
National Contingency Plan - 1990
7. Interim Final Guidance on Preparing Superfund Decision
Documents; The Record of Decision. USEPA, June 1989
8. Guidance for Conducting Remedial Investigations and
Feasibility Studies Under CERCLA. USEPA, October 1988
9. FY 1989 ROD Evaluation Report. USEPA, March 31, 1990
10. Draft Guidance, An Annotated Technical Reference for Hazardous
Waste Sites. USEPA, 1989
11. Radiation References
o Mixed Waste Training Course, USEPA, 1989/1990
o Assessment of Technologies for the Remediation of
Radioactively Contaminated Superfund Sites, USEPA, 1990
12. USEPA CERCLIS Data Base
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LIST OF ACRONYMS
ARARs - applicable, relevant and appropriate requirements
ATR - An Annotated Technical Reference for Hazardous Waste
Sites
FY - fiscal year
NCP - national contingency plan .
PCB - polychlorinated biphenyls
PRPs - potentially responsible parties
RD/RA - remedial design/remedial action
RI/FS - remedial investigation/feasibility study
ROD - record of decision
RPM - regional project manger
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Executive Summary
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OSWER Directive 9835.. 13
EXECUTIVE SUMMARY
The overall purpose of this comparative analysis of remedies
selected at Superfund sites was to determine if there is a
difference between remedies selected at Fund-lead and Enforcement-
lead sites. For the bulk of this analysis, sites whose remedial
investigation/feasibility study (RI/FS) was conducted with
Superfund money (Fund-lead) were compared with those whose RI/FS
was conducted by potentially responsible parties (PRPs)
(Enforcement-lead). In addition, sites whose remedial
design/remedial action (RD/RA) is expected to be conducted by PRPs
were compared with sites where the Fund was expected to conduct the
RD/RA. The latter comparison was developed to consider potential
influence where Potentially Responsible Parties do not conduct the
RI/FS, but offer or are expected to conduct the RD/RA.
A two-tiered approach was used to compare remedies selected
at Fund-lead and Enforcement-lead sites. The first is the General
Analysis, and the second is the Paired Analysis.
In the General Analysis, all FY 1987, 1988, and 1989 final
source-control RODs were reviewed. In order to compare remedies
at sites that have similar characteristics, each of the sites for
which a ROD was signed was assigned to one of 16 site-type
categories. The remedies selected were reviewed to determine if
NCP expectations for treatment were met and to identify areas of
significant difference between remedies selected at Fund-lead sites
and those selected at Enforcement-lead sites.
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The Paired Analysis was designed to compare remedy selection
at a more detailed level at a select number of sites identified as
appearing similar, except that some were Fund-lead and others were
Enforcement-lead. This analysis was conducted to determine if
additional areas of significant difference exist between remedies
selected at Fund-lead sites and those selected at Enforcement-lead
sites. Paired sites were compared in terms of risk management
decisions, cleanup goals, and the extent to which remedy selection
was consistent with the proposed NCP. The sites for this detailed
comparison were selected from among 1989 final source-control RODs
in order to consider the most current remedial decisions.
FINDINGS
Major findings of the General Analysis are:
1. The over-all number and percentage of final source-control
remedies selecting treatment, as opposed to containment or no
action/no further action, increased from FY-87 to FY-89.
2. Program expectations - to treat highly toxic and mobile
wastes, and to contain low-toxicity, high-volume wastes - are
being realized.
3. Patterns of where treatment is chosen instead of containment
for the sites requiring remedial action are generally the same
for Fund-lead and Enforcement-lead sites. In all but a few
instances, it is clear that treatment versus containment
decisions for the sites reviewed in the general analysis (238
sites), were based on site characteristics rather than the
lead of the RI/FS or the RD/RA. A few RODs did not provide
sufficient documentation to adequately determine why
containment was selected instead of treatment.
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4. The use of innovative treatment technologies (treatment
technologies other than incineration and solidfication/
stabilization) increased significantly between FY-87 and
FY-89. As a percentage of treatment technologies selected,
more innovative treatment technologies are being used at
Enforcement-lead sites than at Fund-lead sites.
5. The average cost of final source-control remedies selected in
FY-87, FY-88, and FY-89, for all sites types combined, is
$11.6M. Fund-lead sites showed higher average costs in six
site types than Enforcement-lead sites. Enforcement-lead
sites had higher average costs in five site types than Fund-
lead sites.
Major Findings of the Paired Analysis are:
1. While remedies may be compared among sites that are generally
similar, as determined by the nature or category of the site,
characteristics unique to particular sites may result in the
choice of different remedies at such sites.
2. At both Fund-lead and Enforcement-lead sites the baseline risk
was sufficient to require remedial action. There were some
differences in how risks were developed.
3. Risk Management levels for both Fund-lead and Enforcement-
lead sites were within bounds deemed acceptable by the
Superfund Program. In general, RODs specified cleanup goals
and, in most cases, cleanup goals were similar.
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4. Remedies selected appeared consistent with the NCP expectation
that principal threats posed by the site be addressed through
treatment.
5. No inappropriate influences by PRPs were detected.
NEXT STEPS
Although the study did not demonstrate great differences in
the remedies selected at Fund-lead and Enforcement-lead sites, to
further strengthen the program, EPA intends to implement the
following:
1. EPA (or the State if PRP oversight is Federally funded) will
develop all risk assessments in the future.
2. Consultation with Headquarters will be required on
"containment only" remedies in future RODS.
3. The Agency will closely evaluate how principal threats are
defined and will determine if more prescriptive guidance is
required.
4. EPA will utilize the ROD Forums in which EPA Headquarters
confers with the Regions to assure that Regions are aware of
areas that should be addressed in RODs. Other information
exchange programs will continue to be emphasized.
5. EPA will continue to strengthen oversight of PRP actions to
assure that activities are conducted consistent with Agency
policy and guidance.
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6. Efforts in FY-91 will focus on providing updated cost data
from ongoing remedial actions to the Regions, and in enhancing
regional cost estimating capabilities.
7. EPA will look further into several of the sites discussed in
the general analysis where containment was selected over
treatment.
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Section 1.0
Introduction
Purpose and Scope
Framework for Remedy
Selection
How PRPs may Potentially
Influence Remedy Selection
Analytical Approach
Contents of This Report
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1.0 INTRODUCTION
1.1 PURPOSE AND SCOPE
The overall purpose of this comparative analysis of remedies
selected at Superfund sites was to determine if there is a
difference between remedies selected at Fund-lead and Enforcement-
lead sites. For the bulk of this analysis, sites whose remedial
investigation/feasibility study (RI/FS) was conducted with
Superfund money (Fund-lead) were compared with those whose RI/FS
was conducted by potentially responsible parties (Enforcement-
lead) . In addition, sites whose remedial design/remedial action
(RD/RA) is expected to be conducted by PRPs were compared with
sites where the Fund was expected to conduct the RD/RA. This
comparison was developed to consider potential influence where
Potentially Responsible Parties (PRPs) do not conduct the RI/FS,
but offer to or are expected to conduct the RD/RA.
Influence can be either appropriate or inappropriate. All
remedies selected are subject to public comment. Comments received
can provide valuable information which the Agency uses to select
the best remedy for that site. The main focus of this report was
to determine if remedies selected are indeed independent of who has
the lead for the RI/FS and RD/RA, or, viewed from another
perspective if inappropriate influence entered into the remedy
selection process.
The universe under analysis was limited to sites for which
records of decision (RODs) were signed between fiscal year (FY)
1987 and FY 1989 and whose remedies are final source-control
remedies.
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1.2 FRAMEWORK FOR REMEDY SELECTION
The standards for remedy selection are determined by statute
and by regulation. The Superfund amendments in 1986 added
significant new requirements relating to the use of available and
innovative treatment technologies in remedial actions. These
requirements were implemented through program guidance until the
regulation implementing Superfund, the National Contingency Plan
(NCP), was revised and promulgated in 1990. Perhaps the most
important interim guidance in the period between 1986 and 1990 was
the proposed NCP itself, issued late in 1988.
Both the proposed and final NCP emphasize the use of treatment
in remedial actions within the bounds of practicability. The
preamble to the proposed NCP established a set of program
expectations for when treatment would most likely be practicable
(see Appendix E) . The expectations provide an appropriate
framework for analyzing remedies selected in this period, as they
are the clearest criteria for remedy selection provided by national
program managers to site decision-makers in EPA's Regional offices.
The standards and expectations for remedy selection hold for
any remedial action under CERCLA; they are independent of the party
who conducts the RI/FS or the RD/RA.
1.3 HOW PRPS MAY POTENTIALLY INFLUENCE REMEDY SELECTION
For this analysis, it was assumed that if PRPs could unduly
influence the remedy selection process, their influence would
manifest itself through the description and analysis in the RI/FS,
or when they offer to or are expected to conduct the RD/RA. On the
other hand, comments may be received from PRPs during the public
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comment period for the proposed remedial action plan regardless of
who conducts the RI/FS and RD/RA, and it is entirely appropriate,
and legally necessary, for EPA to take such comments into account.
Therefore, the potential influence of public comments from PRPs was
not analyzed in detail in this study.
Critics have questioned if PRPs have inappropriately
influenced remedy selection such that remedies that are less
protective or less permanent than appropriate are being selected.
This influence could be generated from a biased RI/FS supporting
lesser remedies or, during remedy selection, from the Agency's
desire to obtain a settlement through which the PRPs would perform
the RD/RA.
1.4 ANALYTICAL APPROACH
EPA was asked to conduct an analysis of general trends and
also to look in depth at a few sites to see if issues on the type
of remedies selected differ depending on the site lead. A two-
tiered approach was used to compare remedies selected at Fund-lead
and Enforcement-lead sites. The first is the General Analysis, and
the second is the Paired Analysis. In the General Analysis, all
FY 1987, 1988, and 1989 final source-control RODs were reviewed.
In order to compare remedies at sites that have similar
characteristics, each of the sites for which a ROD was signed was
assigned to one of 16 site-type categories. The remedies selected
were reviewed to determine if NCP expectations for treatment were
met and to identify areas of significant difference between
remedies selected at Fund-lead sites and those selected at
Enforcement-lead sites. Data in the General Analysis is subject
to several qualifications and limitations listed in the General
Analysis, Methdology Section (Section 2.2.4).
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The Paired Analysis was designed to compare remedy selection
at a more detailed level at a select number of sites identified as
appearing similar, except that some were Fund-lead and others were
Enforcement-lead. Paired sites were compared in terms of risk
management decisions, cleanup goals, and the extent to which remedy
selection was consistent with the proposed NCP. The sites for this
detailed comparison were selected from among 1989 final source-
control RODs in order to consider the most current remedial
decisions.
1.5 CONTENTS OF THIS REPORT
The contents of this report on the Comparative Analysis of
Remedies Selected in the Superfund Program for Fiscal Years 1987,
1988, and 1989 are as follows:
o General Analysis
Purpose and Scope
Methodology
Findings
o Paired Analysis
Purpose and Scope
Methodology
Findings
o Next Steps
o Appendixes
Appendix A: Statistical Methods
Appendix B: Technology Selection Trends
Appendix C: Details of Cost Analysis
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Appendix D: Summary Comparisons of Sites in Four
Site Categories
Appendix E: NCP Expectations for Treatment
Appendix F: Treatment versus Containment
Comparison
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Section 2.0
General Analysis
Purpose and Scope
Methodology
Findings
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2.0 GENERAL ANALYSIS
2.1 PURPOSE AND SCOPE
The purposes of the General Analysis were to quantitatively
review remedies, by category of site, to determine whether NCP
expectations were met, and in particular to ascertain whether the
selection of remedies involving treatment appeared to differ
between Enforcement-lead sites and Fund-lead sites. The scope of
this analysis is limited to remedies selected in RODs signed in
fiscal year (FY) 1987, 1988, and 1989 that addressed final source-
control as part of the selected remedy. Remedies that selected
interim actions or temporary storage as the source-control remedies
are not included in this analysis, nor are remedies that addressed
exclusively ground-water contamination. Final source-control was
defined as final remedial actions for a particular area of the
site. This definition is consistent with EPA's FY-89 ROD Annual
Report definition for final source-control.
2.2 METHODOLOGY
For the General Analysis, all final source-control RODs signed
in fiscal years 1987, 1988, and 1989 were reviewed to obtain basic
information concerning the nature of the sites and remedies
selected.
First, a site classification system that was under development
was refined and is discussed in more detail in Section 2.2.1.
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Thereafter, each site was analyzed and placed into one of these 16
site-type categories.1 For each site, the actual or expected leads
on the RI/FS and RD/RA (Fund/Enforcement) were identified.
Finally, each source-control remedy was reviewed to derive the
following information:
o Was treatment selected at the site?
o . What type of treatment technology was selected?
o What is the total present-worth cost of each remedy
selected at each site?
Second, on the basis of this information, EPA evaluated
quantitatively, by category of site:
o For sites in categories where treatment generally is
expected, were treatment remedies selected in roughly the
same proportions at Fund-lead and Enforcement-lead sites?
o Were similar treatment technologies chosen at Fund-lead
and Enforcement-lead sites?
o Were present worth costs comparable at Fund-lead and
Enforcement-lead sites?
2.2.1 SITE CLASSIFICATION
Sixteen site type categories were developed for the purpose
of classifying each final source-control ROD signed during fiscal
years 1987-1989 (See Table 1).
1 If the ROD addressed more than one NPL site, it was counted
consistent with the ROD annual report. In addition, a site may
have more than one ROD and, therefore, the site could be counted
more than once if each ROD selected a final source-control remedy
for a portion of the site.
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Table 1
The Sixteen Site Type Categories for the General Analysis
Asbestos Sites - Sites where asbestos has been mined, milled,
manufactured, used, or where asbestos-containing products were
disposed of.
Battery/Lead Recycling Sites - Sites where lead, usually from scrap
lead batteries, has been recovered and recycled. The primary
contaminant is generally lead, but other metals may be present as
well.
Dioxin Sites - Sites where dioxin-contaminated materials have been
used or disposed of.
Landfill Sites - Sites where soil has been excavated and the cavity
filled with solid waste. This category also includes sites where
a natural surface depression has been filled with solid waste.
Other areas of contamination, such as septic lagoons and drum
disposal areas, are sometimes associated with these sites.
Landfills also contain varying quantities of industrial wastes and
generally range in areal size from 10 to 100 acres.
Municipal Landfills - landfills where primarily municipal and
household waste materials have been disposed of. Municipal
Landfills may also contain significant quantities of industrial
wastes and generally range in areal size from 10 to 100 acres.
Industrial Landfills - Landfills where primarily industrial wastes
have been disposed of. Industrial Landfills can also contain
varying quantities of municipal-type wastes and are generally less
than 10 acres in areal size but can be in excess of 100 acres.
Metal Sites - Sites where metals are the contaminants of concern.
For the purpose of this analysis, arsenic and other inorganic
contaminants are included in this category.
Metals/Organic - Sites contaminated by a variety of organic,
metallic, and other inorganic compounds. For this category there
is no single predominant contaminant or group of contaminants of
concern. Sites in this category may be abandoned chemical
manufacturing or waste disposal facilities and often consist of
drummed wastes, equipment, waste lagoons, and disposal pits.
Mining Waste Sites - Sites where metallic ores have been mined,
resulting in metal-contaminated tailings.
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Radioactive/Mixed Waste Sites - Sites contaminated by radioactive
contaminants or a combination of radioactive and other hazardous
contaminants.
Munitions Sites - Sites where the manufacture of explosives has
resulted in contamination with explosives and other hazardous
compounds.
Organic - Sites contaminated by a variety of organic compounds,
where there is generally no single predominant contaminant or group
of contaminants of concern. This category includes sites that are
abandoned chemical manufacturing or waste disposal facilities and
that may consist of drummed waste, waste containing process tanks,
contaminated process equipment, waste lagoons, and disposal pits.
PCS Sites - Sites where PCBs are the predominant contaminants of
concern. Other contaminants, including both organic chemicals and
metals, are often present in significant concentrations at these
sites. Contamination at these sites is generally from the disposal
of spent transformers or waste oil.
Pesticide Sites - Sites where pesticides have been manufactured,
handled, or applied.
Plating Metal - Sites contaminated by any one of several types of
metal plating processes. Metals are usually the major
contaminants, but other contaminants, such as cyanide oils, acids,
and organic solvents, may be present as well.
Solvents - Sites where organic solvents are the principal
contaminants.
Wood Preserving Sites - Sites where wood preserving operations,
either oil- or water-based, have occurred. Major contaminants
associated with oil-based treatment methods include PCP, creosote,
oils, aromatic hydrocarbons, and octachlorodibenzo-p-dioxin. Major
contaminants associated with water-based methods include arsenic,
chromium, copper, zinc, and fluorides.
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In developing this system, EPA sought to achieve a middle
ground between large numbers of categories each containing a few
very similar sites, and a small number of categories each
containing many possibly dissimilar sites. The categories expand
upon those in a draft Agency manual An Annotated Technical
Reference for Hazardous Waste Sites (ATR), which is being developed
as an information source for Regional Project Managers (RPMs).
Some classifications are facility-based, such as Wood Preserving
or Plating sites or Municipal Landfills, while others are chemical-
based, such as PCBs, Dioxin, or Solvent sites.
Each final source-control ROD signed between FY 1987 and FY
1989 was categorized into one (and only one) of the 16 site type
categories, based on site descriptions contained in the signed
RODs.
In a limited number of cases, the scope of the ROD addressed
only part of the source of contamination, since previous or future
operable units addressed or were intended to address the remaining
sources. To the extent possible, such a site was classified
according to the nature of the contamination of the operable unit
addressed by the ROD. For example, if the scope of the ROD at a
municipal landfill was confined to off-site soils contaminated by
metals, the ROD was classified as a Metals site rather than as a
Municipal Landfill.
There are two factors that argue against placing too much
confidence in site classification as a determiner of type of remedy
selected. The first is that a site's classification is by no means
the only factor, or may not even be the most important factor, that
determines what type of remedy is, or should have been, selected.
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Many other factors, including volume of waste, areal extent of the
site, degree of risk, prior remedial actions taken, topography,
potential technologies, applicable or relevant and appropriate
requirements (ARARs) that pertain, and the preferences of the state
and/or community, among others, influence the selection decision.
Therefore, the fact that sites are in the same category does not
mean the remedies selected for all of those sites will be similar.
Second, classification decisions involve judgment calls. For
example, a site contaminated by Polychlorinated biphenols (PCBs),
as well as other organic chemicals, might have been placed in the
PCBs site category rather than in the Organic site category, if the
reviewers felt that the quantity of PCBs justified so classifying
the site. Another review team, however, might place the same site
in the Organic category.
2.2.2 LEAD IDENTIFICATION
To obtain a numerical indication of whether PRP's conduct of
the RI/FS, or actual or anticipated settlement with a PRP for the
RD/RA may have affected Agency remedy decisions, sites in each site
category were grouped by lead categories.2
RI/FS Influence:
o Fund-lead The RI/FS was federally funded
o Enforcement-lead The RI/FS was conducted by the
PRPs
2 Planning information for individual sites, such as planned
leads for the RD/RAs, is considered enforcement confidential, and
thus site names or other related information * is omitted.
Information concerning the identity of the lead for the RI/FS and
RD/FA for a particular site was obtained from site reports
generated February 8, 1990, from the CERCLIS data base.
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PRPs Settlement Influence:
o Fund-lead for the RD/RA
The RD/RA was expected to be federally funded
o Enforcement-lead for the RD/RA
The RD/RA was expected to be conducted by the PRPs
If a reference is made to Enforcement- or Fund-lead without
specifying RI/FS or RD/RA, one should assume it is meant for the
RI/FS.
2.2.3 TYPE OF REMEDY
Final source-control decisions were categorized as Treatment,
Containment Only, or No Action/No Further Action3. Consistent with
the definition used in the FY 89 EPA ROD Annual Report, Treatment
was defined as any operation or series of unit operations that
alters the composition of a hazardous substance, or pollutant, or
contaminant through chemical, biological, or physical means - so
as to reduce the toxicity, mobility, or volume of the contaminated
materials being treated. If any treatment technology was selected
for any portion of a site, that site's remedy was classified as
treatment consistent with the definition in the FY 1989 ROD Annual
Report.
Containment Only refers to operations or technologies that
are intended to prevent the further migration of contaminants;
treatment is not involved. Placement of a RCRA cap or off-site
disposal without treatment would be considered containment
remedies.
Information describing the selected remedial actions was
obtained from EPA ROD Annual Reports (FY 1987, FY 1988, and FY
1989) .
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No Action/No Further Action refers to the selection of no
remedial action or no further remedial action for a specified
portion of the site. Previous remedial actions/removal actions or
implementation of fences and institutional controls would be
included in this category.
For those sites whose RODs revealed that a treatment remedy
had been selected, a distinction was made between whether the
remedy involved available or innovative technologies based on the
definition in the FY89 ROD annual report/ Technologies defined
as "Available" included incineration/thermal treatment and
solidification/stabilization. Those considered "Innovative"
included vacuum/vapor extraction, biodegradation/land application,
soil washing/flushing, solvent extraction, volatilization/soil
aeration, innovative thermal treatment, innovative
solidification/stabilization, and low temperature thermal
treatment, as well as other innovative or non-specified
technologies.
2.2.4 TREATMENT APPROACHES FOR SUPERFUND SOURCE-CONTROL
The treatment of contaminated source material at Superfund
sites is a complex technical problem. The following describes
basic mechanisms for treatment of contaminated sources.
4 When more than one technology was selected at a site, except
for treatment trains, each technology selected was counted
separately in the General Analysis. In the case of treatment
trains, only the primary or innovative technology was counted (FY
89 ROD Annual Report definition). Therefore, the number of
occurrences of technologies selected exceeds the number of RODs
selecting treatment.
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The first is destruction of contaminants, using
biodegradation, incineration, and other thermal destruction
technologies, and dechlorination. Another is physical transfer of
the contaminants to another medium for recovery or subsequent
treatment, using solvent extraction, vacuum/vapor extraction, soil
washing, soil flushing, low temperature thermal treatment,
volatilization/soil aeration, and thermal distillation. A third
is reduction in mobility of the contaminants, using
solidification/stabilization and in-situ vitrification.
Each of these three approaches is appropriate for different
types of wastes. Many sites contain a combination of organic and
inorganic contaminants which require different treatment approaches
o meet the NCP goals of reduction in toxicity, mobility, or
volume.
In general, organic contaminants can be destroyed through a
treatment process and reduced to individual elements or basic
compounds such as carbon dioxide and water, or by physically
transferring the compounds to an air stream or to a liquid stream
for treatment, which can be accomplished with low temperature
thermal treatment and solvent extraction, respectively.
Solidification/stabilization of organics is an area undergoing
considerable research at this time. Preliminary findings indicate
that the technology is not effective for volatile compounds; in
fact, these are likely to be released in the exothermic
stabilization reactions. However, the potential effectiveness of
solidification/stabilization for some non-volatile compounds at
relatively low concentration levels, warrants continued research.
2-9
-------
OSWER Directive 9835-13
Inorganic contaminants differ from organic contaminants in
that they cannot be destroyed. Instead, the only applicable
approaches for these contaminants are to reduce their mobility
through technologies such as solidification/stabilization or in-
situ vitrification, or to physically transfer them to another
medium for subsequent solidification/stabilization, recovery, or
in-situ vitrification.
2.2.5 QUALIFICATIONS AND LIMITATIONS
The data in this report were derived by means of a data
extraction and analysis process that is subject to several
qualifications and limitations. Any persons interpreting or using
this information must be cognizant of the following caveats.
Subjectivity in Data Analysis
The data from the FY-1987, 1988 and 1989 ROD Annual Reports were
used for the General Analysis portion of this report. In many
instances, subjectivity occurred in categorizing sites into site
types (See Section 2.2.1 Site Classification). Subjectivity also
occurred in correlating FY-1987 and FY-1988 sites to the FY-1989
ROD Annual Report definitions in three areas: if the state
selected a final source-control remedy, if treatment was selected,
and if the treatment was innovative or available5. EPA is
expecting to revise the FY-87 and FY-88 ROD annual reports to
correspond to the FY-89 ROD annual report definitions or other
definitions refined in FY-90.
5 EPA is expecting to revise the FY-87 and FY-88 ROD annual
report data to correspond to the FY-89 ROD annual report
definitions or other definitions refined in FY-90. The data
contained in this report has attempted to make those changes.
2-10
-------
OSWER Directive 9835.13
For example, for defining if the ROD was for final source-
control, questions arose as to if the remedial action was all that
was going to be done for that area. Sometimes RODs stated that
sampling would occur to determine if anything else was needed.
Judgement was used if this was expected to cause an additional
remedial action for that area. An example of "if treatment was
selected" is a landfill gas collection and treatment system under
a cap. This remedial action was not considered to be final source-
control treatment in this study for two enforcement sites. There
is also some subjectivity involved in classifying treatment in
terms of available or innovative technology employed. As more
technologies are developed and applied, the distinction between
Available and Innovative treatment technologies undergoes
reexamination and revision. Another review team might have made
different decisions concerning the classification areas discussed.
Small Sample Size
For a number of waste site categories, the size of the sample
population, or "data set", upon which statistical values have been
derived is small. Often, the size is below that number required
to support a statistically reliable extrapolation of analytical
results to the larger program universe but was still deemed the
best way to compare sites. For example, the number of sites in
mining are small; however, these sites have many comparable
characteristics.
Cost Data Limitations
There are several significant limitations associated with the
cost data used in this analysis. The Agency has determined that
2-11
-------
OSWER Directive 9835.13
collectively, these limitations are sufficiently material to limit
any extrapolation of cost-related analyses or statistics to the
Superfund Program as a whole.
o Program guidance requires that cost estimates be accurate
only to within a range of +50 to -30 percent.
o Cost data in the general analyses can not be normalized
'to common, comparable unit-costs, such as volume treated
in dollars per cubic yard, or area capped in dollars per
square foot, due to lack of data in the RODs.
o In some instances, the available present-worth cost
information also includes costs for non-source-control
treatment when the ROD did not provide a basis for
excluding these costs.
o No adjustment was made to the present-worth cost values
extracted from the ROD source documents. Thus, the cost-
related data in this document are assumed to be the
present-worth values for the year in which individual RODs
were prepared, without an adjustment for inflation.
The cost analysis which was conducted for the General Analysis
was prepared using three clarifying assumptions:
o All cost evaluated in the cost analysis were total present
worth costs, or an equivalent. Where total present worth
costs were not available, equivalent costs were only sued
if capital costs were equal to present worth costs (that
is, there were no operation and maintenance costs), or if
a range was provided for present worth costs, an average
present worth cost was calculated.
o Where total present worth cost data or its equivalent were
not available, the costs were considered to be not
2-12
-------
OSWER Directive 9835.13
available. Fifty-three sites were not included in the
cost analysis because present worth costs were not
available.
o In several instances, the ROD addressed multiple sites
and the costs were equally allocated among the sites.
2.3 FINDINGS
The findings presented here follow the order in which the
various phases of the General Analysis were performed, as discussed
under METHODOLOGY; that is, information pertaining to the universe
of sites is presented first, followed by findings related to
overall treatment trends, treatment trends within site types, use
of innovative technologies, and finally, cost.
Several appendices contain more detailed information on or
explanations of the results of the General Analysis and/or how
those results were arrived at. Appendix A describes the
statistical methods used to test the results of the analysis
statistically. Appendix B contains a series of tables that show
the numbers/proportions of available and innovative technologies
selected, by site type and by lead for FY87, FY88 and FY89 final
source-control RODs selecting treatment. Appendix C presents
detailed statistical cost data.
In addition to the following specific findings, some general
observations can also be made: the percentages of sites in the
various site type categories are not evenly distributed (Figure
1); the percentages vary from year to year (Figure 2); for 13 of
the 16 site types, the majority of the RI/FSs were conducted by
the Fund (Figure 3); for 10 of the 16 site types, the majority of
the RD/RAs were designated Enforcement-lead (Figure 4).
2-13
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OSWER Directive 9835.13
1. Tbe number and percentage of final source-control remedies
selecting treatment, as opposed to containment or no
action/no further action, increased from FY-87 to FY-89.
Since FY 1987 the number and proportion of sites receiving
treatment has increased. In 1989, two thirds of the final source-
control RODs sites selected treatment remedies. Further, the
proportion of sites for which containment is selected appears to
be falling (Figure 5).
2. Program expectations - to treat highly toxic and mobile
wastes, and to contain low-toxicity, high-volume wastes - are
being realized.
The data show that for 11 of the 16 site type categories,
"treatment" was selected instead of containment. In most of these
11 categories, there is both a high incidence of highly toxic and
often mobile wastes and a relatively low incidence of practical
constraints (e.g., size) expected. These 11 categories are:
Battery/Lead, Dioxin, Industrial Landfills, Metals, Metal/Organics,
Organics, PCBs, Pesticide, Plating, Solvents, and Wood Preserving
(Figure 6). (The remedy expectation for Industrial Landfills may
be either treatment or containment depending on the type and volume
of the waste, and the ability to locate and access areas containing
principal threats.)
The five site categories for which containment was the
predominantly chosen remedy are Asbestos, Mining, Radioactive/Mixed
Waste, Municipal Landfills, and Munitions Waste. Three of these
categories (Asbestos, Mining, and Municipal Landfills) generally
involve high-volumes of generally low-toxicity substances that are
2-18
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2-19
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2-20
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OSWER Directive 9835,13
expected to be handled by means of containment. For
Radioactive/Mixed Waste sites, the waste cannot be destroyed.
Expectations have been to contain low-level radiation material
waste. Research on Stabilization/Solidification technologies and
separative techniques (physical and chemical) are currently
underway. In a recent EPA guidance document dated January, 1990
titled,. Assessment of Technologies for the Remediation of
Radioactively Contaminated Superfund Sites, treatability and field
testing of treatment technologies for soils contaminated with
radioactive wastes are being initiated since there is a "prevalence
of contaminated soils and a lack of technologies suitable for their
cleanup." This guidance document discusses these potential
treatment technologies. Munitions sites present special obstacles
for treatment.
3. Patterns of where treatment is chosen instead of containment
for the sites requiring remedial action (238 sites) are
generally the same for Fund-lead and Enforcement-lead sites.
In all but a few instances/ it is clear that treatment versus
containment decisions for the sites reviewed in the general
analysis, was selected based on site characteristics rather
than the lead of the RI/FS or the RD/RA. A few RODs did not
provide sufficient documentation to adequately determine why
containment was selected instead of treatment.
For all 16 site types, EPA evaluated final source-control RODs
signed in fiscal years 1987, 1988 and 1989 to determine if the
remedy was a treatment or containment remedy. Fund-lead and
Enforcement-lead decisions for sites requiring remedial action (238
sites) were compared. Trends were reviewed for both RI/FS and
RD/RA leads (Figures 7, 8, 9,10, and Tables 2, 3, 4, and 5).
2-21
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2-29
-------
OSWER Directive 9835.13
Fund- and Enforcement-lead RODs selected treatment for all
RODs in four site types where treatment is generally appropriate
(Battery/Lead, Dioxin, Solvents, and Wood Preserving).
In two of the three site types where containment was generally
expected, Asbestos and Mining, containment remedies were chosen.
In the other site type where containment was generally expected,
Municipal Landfills, RODs selected containment. The percentages
of Municipal Landfill RODs selecting containment for Fund- and
Enforcement-lead RI/FSs and RD/RA were comparable. For the
Munitions category, the RI/FS and the RD/RA were Fund-lead for all
three sites, therefore a comparison of Fund versus Enforcement
remedy selection could not be conducted. For the Radioactive/Mixed
Waste category, all sites were projected Enforcement-lead for the
RI/FS and the RD/RA, so again a comparison cannot be conducted,
however, since these six sites selected containment, these RODs
were reviewed to determine if the choice of containment was
appropriate. For the Radioactive/Mixed Waste category, all sites
were reviewed. Five sites were low-level radioactive waste sites
and one site was a Mixed Waste site with low-level radioactive
waste. Low-level radioactive wastes are currently expected to be
contained since radioactive materials cannot be destroyed. When
reviewing the remedies for these sites, no differences were noted
except that the Mixed Waste site also apropriately called for
disposal of the hazardous waste in accordance with appropriate
requirements for mixed waste.
The remaining seven site types are Industrial Landfills,
Metals, Metals/0r*ganic, Organic, PCB, Pesticides and Plating. These
seven site types were reviewed for patterns based on who conducted
the RI/FS and who has or is expected to conduct the RD/RA. The
number of sites where RODs selected containment in each of these
remaining seven site types and the number of sites with RODs
2-30
-------
OSWER Directive 983-5; 13
selecting containment for Enforcement-lead and Fund-lead sites were
within one site of each other for six of these site types
(Industrial Landfills, Metals, Metal/Organic, PCB, Pesticides, and
Plating) and within two for the other site type (Organic). The
percentages for Enforcement-lead versus Fund-lead RI/FS sites for
RODs choosing containment over treatment are within ten percent for
four of the site types (Metals, Organic, PCB, and Pesticides).
A comparison based on the lead for the RD/RA revealed no
change to the above analysis in three site types (Metals,
Pesticides and Plating). In the Industrial Landfill category, five
sites with RODs selecting treatment and two sites selecting
containment are expected to change from Fund-lead to Enforcement-
lead. In the Metal/Organics category, twelve sites selecting
treatment and three sites selecting containment are expected to
change to Enforcement-lead. In the Organics category, three sites
selecting treatment and one site selecting containment are expected
to change to Enforcement-lead. In addition, two Enforcement-lead
sites with RODs selecting treatment in this category are expected
to switch from Enforcement-lead to Fund-lead for the RD/RA. In
the PCB category, seven sites with RODs selecting treatment and one
site selecting containment are expected to switch to Enforcement-
lead in RD/RA.
All containment RODs in these seven site types were reviewed
for the rationale for selecting containment (Industrial Landfill,
Metals, Metal/Organics, Organics, PCB, Pesticides, and Plating)(see
Appendix F) . Size of the site(over 100,000 cubic yards), a
baseline risk for the source materials was within the 10"4to
10"6 risk range, or relatively low levels of contamination,
previous removal actions reduced the contaminant levels,
availability of treatment equipment, technical infeasibility,
excavation would cause unsafe exposure to contaminants, and public
concerns were the reasons provided for selecting containment.
2-31
-------
OSWER Directive 9835.13
These may be acceptable rationale within program expectations.
Some of these RODs gave clear rationale that appeared appropriate
and that showed that the choice of containment was based on site
characteristics rather than the RI/FS or RD/RA lead, (ten Fund-
lead, seven Enforcement-lead), some of these RODs would need
further analysis to determine if they were appropriate or if biases
entered into decision making (two Fund-lead, seven Enforcement-
lead) .
Out of 238 final source-control RODs, nine RODs have been
identified as needing further analysis to determine if influence
occurred from the PRPs such that containment was selected over
treatment. This represents four percent of the universe.
4. The use of innovative treatment technologies (treatment
technologies other than incineration and
solidification/stabilization) increased significantly between
1987 and 1989. As a percentage of treatment technologies
selected/ significantly more innovative treatment technologies
are being used at Enforcement-lead sites than at Fund-lead
sites.
During FY 1987-1989, when treatment was selected as part of
the remedial action, innovative technologies were selected
approximately 45 percent of the time. The selection of innovative
technologies over the three-year period increased significantly
from 33 percent in FY 1987 to 53 percent in FY 1989. (Table 6)
At sites selecting treatment where the Fund conducted the
RI/FS, more conventional remedies were selected. Primary treatment
categories for Fund-lead sites included Incineration/Thermal
treatment (41%) and Solidification/Stabilization (23%). For
Enforcement-lead sites, primary treatment categories selected
included Solidification/Stabilization (21%), Vacuum/Vapor
Extraction (20%) , Incineration/Thermal treatment (15%), and
2-32
-------
Table 6 - Innovative Technology Select'en T,-e*>ds !n Treatment RC^
1037
Y '988
-.ea:^e.t .gj.^-gy
A .'A' ABL- ~"-MC cs;rs
; -,- . re'at on/7"erpflal T-eatment*
Sc'. -d' f i cat i en/Stab i I zation
S-fctstar. Ava dble
.ki,^,,A,.vc .r_Jlc,OG.ES
^acuurV Vacc r extraction
S'oaeg'aaat : on/ ll'anc Appl i cat ion
Soil -as.h'ng/ Blushing
Solvent Extraction
Vc.at ; '. i zat ' on/Soi I Aeration
Ct-er/Nct Specified Treatment
Innovative Thermal Treatment
Innov. Sol idi f i cat ion/Stab i I i zat ion
LOW Temperature Thermal Treatment
Subtotal Innovative
"cta.s**
S-rpe' cl RODs Selecting Treatment
* /
13 /
9 /
22 /
1 /
1 /
2 /
1 /
1 /
4 /
0 /
0 /
1 /
11 /
33 /
26
=i
39
27
66
3
3
6
3
3
12
0
0
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33
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27 /
18 /
45 /
9 /
6 /
7 /
2 /
1 /
0 /
1 /
0 /
4 /
30 /
75 /
66
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36
24
60
12
8
9
2
1
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40
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9
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18
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16
8
6
6
4
5
2
1
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49
92
/
/
/
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/
/
/
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/
69
%
27.2
19.6
46.7
17.4
8.7
6.5
6.5
4.3
5.4
2.2
1 .1
1.1
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100
-
65 '
-5 /
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26 /
'5 /
15 /
9 /
6 /
9 /
3 /
1 /
6 /
90 /
200 /
161
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100
ğ Numoer o* Occurrences of Technology Selection
'; Percentage of Total Occurrences
* Category includes thermal distillation.
** *ne total numoer of occurrences may exceed the number of RODs where
t-eatment was selected, because different technologies for different
areas may have been selected in each ROD, only the primary or innovative
porfons of a treatment train were counted (consistent with the FY-89
RCD Annual Report definition of treatment).
Source: 1987 to 1989 Final Source Control RODs
2-33
-------
OSWER Directive 9835.13
Biodegradation/Land Application (14%). (Tables 7 and 8) Since
Solidification/Stabilization percentages were similar, the
remaining treatment category percentages tend to suggest that Fund-
lead sites, as compared to Enforcement-lead sites, tend to select
incineration over vacuum/vapor extraction and biodegradation. The
paired analysis portion of this report tends to support this
observation.
In eight site types, Enforcement-lead RODs selected innovative
technologies in greater percentage than Fund-lead RODs (Industrial
Landfill, Metals, Metal/Organics, Municipal Landfill, organics,
PCB, Solvents, Wood Preserving). In three site types, a higher
percentage of innovative treatment was selected at Fund-lead than
at Enforcement-lead sites (Battery/Lead, Pesticides and Plating).
In three site types, no innovative treatment technologies were
selected (Asbestos, Dioxin, Mixed Waste), and two site types did
not have sites in both Fund- and Enforcement-leads (Mining and
Munitions). (See Appendix B)
5. The average cost of final source-control remedies selected in
FY-87, FY-88, and FY-89, for all site types combined is
$11.6M. Fund-lead sites showed higher average costs in six
site types than Enforcement-lead sites. Enforcement-lead
sites had higher average costs in five site types than Fund-
lead sites.
Based on the RI/FS lead, final source-control RODs at Fund-
lead sites had higher overall average costs when compared to final
source-control RODs at Enforcement-lead sites ($12.8M compared to
$8.7M). RODs at Fund-lead sites had higher average costs in FY-
1988 and FY-1989. RODs at Enforcement-lead sites had higher
average costs in FY-1987. (Table 9)
2-34
-------
Table 7 - Innovative Tecrinclogy Seiecticr Trenes .'n T-
*er Fund-leaa R!/-S
-939
--ea:-e-t -*-.--:. :SY.
. .. i3 - ...^.,,,.,.3
:^c-~era:icn/-'-e--ai T^eatme^f
S:. -c- --cat 'on/ Stab' i 'zafon
S-ctcta . Ava1 table
.liN,.i.r,v. -;-UVOLOG.ES
vacjjr/vapcr Extraction
5 ' cceg-sca 1 1 c'VL and Application
S:1 . was"' "g/ Flush ing
Sc.ve~t Extraction
. :,a: i rat cn/Sci I Aeration
C-.-.e-Ac: Specified Treatment
;--cvafve Tne-mal Treatment
! .cv. Soiici f i cat ion/Stab i I ization
.cw :emperature Thermal Treatment
S-ctota. .'inovative
"::a.s**
s--.ce- 2* RODs Selecting Treatment
a
11
8
19
2
1
1
0
0
0
1
6
25
/
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! 110
s--De~ c* Occurrences of Technology Selection
-e^ce-tage of Total Occurrences
* Category includes thermal distillation.
* T-e tcta> numbe-- of occurrences may exceed the number of RODs where
:^eat~er;t was selected, because different technologies for different
a-eas rnay nave been selected in each ROD, only the primary or innovative
oc-''crs of a treatment train were counted (consistent with the FY-89
R" Annual Report definition of treatment).
Source: 1987 to 1989 Final Source Control RODs
2-:
-------
Treatment Technology
AVAILABLE TECHNOLOGIES
Incineration/Thermal Treatment*
So I i d i f i cat i on/Stabi I i zat i on
Subtotal Available
INNOVATIVE TECHNOLOGIES
Vacuum/Vapor Extraction
8 iodegradat ion/Land Appl i cat ion
Soil Wash ing/ Flush ing
Solvent Extraction
VoL at ili zat ion/Soil Aeration
Other/Not Specified Treatment
Innovative Thermal Treatment
Innov. Solidif ication/Stabi lization
Low Temperature Thermal Treatment
Subtotal Innovative
Totals*"
Number of ROOs Selecting Treatment
Fr 1987
* / %
2 1 25.0
1 / 12.5
3 / 37.5
0 / 0.0
1 / 12.5
0 / 0.0
0 / 0.0
0 / 0.0
4 / 50.0
0 / 0.0
0 / 0.0
0 / 0.0
5 / 62.5
8 / 100
6
FY 1988
# / X
3 / 15.8
4 1 21.1
7 / 36.8
4 I 21.1
2 / 10.5
3 / 15.8
1 / 5.3
1 / 5.3
0 / 0.0
0 / 0.0
0 / 0.0
1 / 5.3
12 / 63.2
19 / 100
18
FY 1989
* / X
5 / 12.8
9 / 23.1
14 / 35.9
9 / 23.1
6 / 15.4
1 / 2.6
1 / 2.6
4 / 10.3
3 / 7.7
0 / 0.0
1 / 2.6
0 / 0.0
25 / 64.1
39 / 100
27
FY 1987-89
# / %
10 / 15.2
14 / 21.2
24 / 36.4
13 / 19.7
9 / 13.6
4 / 6.1
2 / 3.0
5 / 7.6
7 / 10.6
0 / 0.0
1 / 1.5
1 / 1.5
42 / 63.6
66 / 100
51
Table 8 Innovative Technology Selection Trends In Treatment RODS
for enforcement-lead RI/FS
# - Number of Occurrences of Technology Selection
% Percentage of Total Occurrences
Note: * Category includes thermal distillation.
** The total number of occurrences may exceed the number of ROOs where
treatment was selected, because different technologies for different
areas may have been selected in each ROD, only the primary or innovative
portions of a treatment train were counted (consistent with the FY-89
ROD Annual Report definition of treatment).
Source: 1987 to 1989 Final Source Control RODs
2-36
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OSWER Directive 9835*13
Based on the RD/RA lead, Fund-lead sites continued to have
higher average costs than Enforcement-lead sites but the range
narrowed ($12.9M compared to $10.2M).
Based upon the RI/FS lead, Fund-lead RODs showed higher costs
than Enforcement-lead RODs for six site types (Asbestos,
Battery/Lead, Dioxin, Metals, Metal/Organics, and Pesticides)(see
Figure 11). For four site types, Enforcement-lead sites showed
higher average costs than Fund-lead sites (Industrial Landfill,
Organics, Plating, and Solvents). For three sites types (Wood
Preserving, PCBs, Municipal Landfill), the average costs were
similar (within 10 percent). Three site types did not have either
Fund-lead or Enforcement-lead sites for comparison (Munitions,
Mixes Waste/Radioactive Waste, and Mining).
Based on the RD/RA lead, Fund-lead RODs had higher average
costs in seven of the sites types and Enforcement had higher
average costs in four of the site types (Figure 12) . Average
costs were comparable for one site type. The remaining four site
types had only one lead-type sites.
Figures 3, 4, 11, 12, and Tables 10 and 11 illustrate that
many of the Fund-lead sites are in five site types (Municipal
Landfill, Industrial Landfill, Solvents, PCB, and Metal/Organic).
These five site types also have the highest average cost. This may
account, in part, for the difference in the average cost between
Fund- and Enforcement-lead sites. By this it is meant that if the
Fund conducted more RI/FSs in site types that generally cost more,
than the average cost for all Fund-lead sites would be expected to
exceed those for Enforcement-lead sites. This only holds true if
Enforcement-lead costs for those site types were comparable. If
Enforcement-lead sites were costing less, than the difference might
have been more attributable to the lead than the site type.
Analysis of Fund- and Enforcement-lead RODs in these five site
2-38
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2-42
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OSWER Directive 9835;13
types revealed that. Enforcement-lead sites in four of the five
of these site types were comparable or higher (Municipal Landfill,
Industrial Landfill, Solvents, PCBs). Only one site type showed
that Fund-lead costs were higher than Enforcement-lead costs
(Metals/Organics).
Thus, it appears that except for the Metal/Organics category,
the higher average cost of Fund-lead sites may be driven in part
by the number of sites falling into high cost site types rather
than by an Enforcement- versus Fund-lead explanation. It may also
be due to the greater use of innovative technologies by
Enforcement-lead sites, and in a few instances by containment
versus treatment decisions.
The costs within site types, however, do vary widely, such
that the standard deviation in 14 site types exceeds the mean costs
for those site types. (Figure 13) Generally, these large
deviations mean that it is highly probable that the projected costs
could actually be a small fraction of the reported average, or more
than twice the average, thus limiting their analytical use. This
wide degree of variability reflects the inherent volatility of the
reported present value cost figures, due to factors such as the
size or location of a site, the amount of wastes actually treated,
the degree and duration of treatment, and the technology or
combination of technologies used. Other statistical cost analysis
was performed and can be found in Appendix C.
2-43
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-------
Section 3.0
Paired Analysis
Purpose and Scope
Methodology
Findings
-------
-------
OSWER Directive 9835,13
3.0 PAIRED ANALYSIS
3.1 PURPOSE AND SCOPE
The Paired Analysis was designed to compare remedies selected
for a limited number of similar sites, some of which were Fund-
lead for the RI/FS, and others, Enforcement-lead for the RI/FS.
Paired sites were compared in terms of risk management decisions,
cleanup goals, and the extent to which remedy selection was
consistent with program expectations, as stated in the National
contingency Plan (NCP). Particular attention was paid to whether
there was any evidence that potentially responsible parties (PRPs)
adversely influenced remedy selection decision-making, such that
remedies chosen for Enforcement-lead sites were inappropriate. For
this paired analysis, only FY 1989 final source-control RODs were
reviewed.
3.2 METHODOLOGY
Two panels were chosen for the Paired Analysis. One panel was
responsible for selecting the sites that would be compared, and the
other was responsible for evaluating and comparing those sites and
the remedies selected.
3.2.1 SITE SELECTION PROCESS
Before the site selection process began, the Agency decided
to narrow the universe of RODs from which the paired sites would
be chosen. The universe was limited to FY 1989 RODs for two
reasons: (l) FY89 RODs should be consistent in that they would
have been prepared when the same guidance and regulatory documents
3-1
-------
OSWER Directive 9835.13
were available and (2) the FY89 RODs present a more current picture
of the Superfund program. The universe was also limited to final
source-control RODs.
FY89 RODs for final source-control were separated into site
categories based on the draft "Annotated Technical Reference for
Hazardous Waste Sites." These categories included1:
1. Asbestos 8. Munitions
2. Battery Recyclers/Lead 9. PCBs
3. Dioxin 10. Pesticides
4. Landfills 11. Plating
5. Metal 12. Solvent
6. Mining 13. Wood Preserving
7. Radioactive/Mixed Waste
Because of resource constraints, only between 15 and 20 sites
could be evaluated in the Paired Analysis portion of the study.
In view of the risk of a lack of representativeness if one Fund-
lead site were compared to one Enforcement-lead site, the study
managers adopted the objective of studying four sites in four
categories. Moreover, it was initially decided that the first
1 For the General Analysis, two of these categories,
Landfills, and Solvents, were subdivided to reduce the amount of
judgment necessary to assign sites to categories. The landfill
category was divided into Municipal Landfills, and Industrial
Landfills. The categories Organics and Metals/Organics were added,
in addition to the Solvent category. At the time the Agency chose
the categories from which the site selection panel would choose
sites to be evaluated, the 13 categories had not yet become 16;
therefore, the panel chose from the non-subdivided Landfill and
Solvents categories. As it turns out, however, three of the
Landfills sites chosen were placed in the Industrial category
(however, it had an Industrial Landfill portion), and three of the
Solvents sites selected were eventually placed in the
Metal/Organics category and one remained in Solvents.
3-2
-------
OSWER Directive 983,5.13
panel would attempt to choose sites from among only the PCB, Wood
Preserving, Landfill, and Battery/Lead sites.2
The Agency felt it important to avoid any bias in selecting
sites to review for the Paired Analysis. With that objective in
mind, three EPA personnel, who are knowledgeable about chemical
characteristics, risk assessments, and remedial technologies, but
who are- not directly involved in the Superfund remedy selection
process, were chosen as the site selection panel. Panel members
were provided with notebooks that contained objective information
necessary to compare sites (e.g., site description, baseline risk,
major contaminants, concentrations of contaminants, and size).
Information such as site name, Region, the date the ROD was signed,
cleanup goals, and information related to the remedy selected was
omitted.
The panel was tasked to select at least four sites from among
the four site categories. The panel was also provided information
on Pesticides, Solvents, and Metal Sites in case they could not
select enough sites in the four site types previously mentioned.
Since only three FY89 RODs could be classified as Battery/Lead, the
panel decided instead to choose from among the Solvent sites. The
panel was told that some sites in each category should be Fund-
lead for botn the RI/FS and the RD/RA, and some should be
Enforcement-lead for both the RI/FS and the RD/RA. However, the
final decision on what sites to analyze was left to the panel.
These particular site categories were chosen because a
report by the Office of Technology Assessment, Coming Clean;
Superfund Problems Can be Solved, evaluated remedy selection at
these types of sites.
3-3
-------
OSWER Directive 9835,13
Ultimately, the panel chose 17 sites to be evaluated in
detail. Unknown by the panel, many of these happened to be in the
same Region. Despite the heavy concentration in this one Region,
however, the selection was allowed to stand, because altering it
could mean introducing a bias, which the Agency had taken pains to
avoid, and a delay.
Once the sites and categories to be evaluated were finalized,
another panel convened to evaluate and compare the remedies
selected.
3.2.2 SITE COMPARISON PROCESS
The panel formed to evaluate and compare the remedies selected
for the 17 sites consisted of members of the Office of Waste
Programs Enforcement (OWPE), the Office of Emergency and Remedial
Response (OERR), and the Office of Solid Waste and Emergency
Response (OSWER). The Office of Research and Development (ORD) was
also invited to participate to the extent possible. The panel
interviewed as a group the regional project managers (RPM) or other
Regional representatives for the sites selected in each category.
Each Regional representative discussed the site, the remedy
selected, and the rationale for the selection. The group discussed
similarities and differences among the sites, as well as factors
that influenced the remedy selected.
To ensure that similarities and differences among sites were
evaluated in a consistent manner, the OWPE and OERR personnel
conducting the analysis agreed to address the following questions:
o What characteristics make one site similar or different
from other sites (e.g., type and quantities of waste
3-4
-------
OSWER Directive 9835.13
disposed, proximity to residential areas, expected future
use of site, proximity to surface water, ground water
use)?
Were similar exposure pathways evaluated? Are baseline
risks similar for sites that appear similar?
Are cleanup goals similar for sites that appear to be
similar?
Are selected remedies consistent with NCP expectations
concerning treatment versus containment? Are similar
sites selecting similar remedies?
Does it appear that remedy selection decisions were
influenced by comments made by the community, PRPs, or
the State?
A panel member was designated as leader for each one of the
four site categories. This individual read the RODs and major
portions of the RI/FS and also developed the summary and findings
pertaining to the sites in that category which are included in this
report.
The findings and recommendations for each site category are
incorporated into the Pair Summary Findings and Pair Recommendation
Section which follow.
3.3 FINDINGS
Overall, the findings from the Paired Analysis suggest that
there is no significant difference between Fund-lead and
Enforcement-lead sites in terms of whether the remedies selection
process and the remedies selected are consistent with expectations
set forth in the National contingency Plan (NCP). In addition,
there is no evidence that comments or preferences of PRPs result
in selection of remedies that are inappropriate. Specific findings
relating to the paired analysis follow.
3-5
-------
OSWER Directive 9835.13
1. While remedies may be compared among sites that are generally
similar/ as determined by the nature or category of the site,
characteristics unique to particular sites may result in the choice
of different remedies at such sites.
A. In an effort to compare similar sites, source control sites
were divided into categories such as type of facility where the
waste was generated, type of waste or disposal area. After
analyzing 17 sites in four categories in detail, sites in some
categories proved more comparable than sites in others.
Specifically, sites within the Wood Preserving and PCBs categories
were more similar than those in the Solvents and Industrial
Landfills categories.
B. Superfund sites vary considerably such that different remedies
are appropriate for sites in the same category. Table 12 lists
factors that were found to have influenced remedy selection.
2. At both Fund-lead and Enforcement-lead sites the baseline risk
was sufficient to require remedial action. There were some
differences in how risks were developed.
A. The baseline risk assessment is used to determine whether,
under current or potential future land use conditions, the site
presents a risk that warrants remedial action. The major
conclusion is that the baseline risk was sufficient, at both Fund-
lead and Enforcement-lead sites, to support the need for
remediation.
B. There were some differences in various components of the risk
assessments as summarized in the 17 RODs. While all risk
assessments preceded the current guidance, one preceded any
3-6
-------
OSWER Directive 9835.13
Table 12
Factors Affecting Selection of similar Remedies
I. Risks concerns
Site setting: proximity to residential area;
industrial/residential land use of site; anticipated
land use goals
Active operating facility
Primary exposure routes/concerns
Concentration of contaminants
Environmental concerns: endangered species, wetlands, flood
plain
II. similarity of Physical Characteristics of sites
Size of site
Volume of wastes
Complexity of site
Are hot spots present?
Extent and nature of contamination
Soil type
Topography
Class of aquifer
III. Similarity of Waste
Are similar wastes present?
Additional contaminant requirements: pre-treatment; factors
that would preclude certain treatment technologies (e.g.,
if there were certain metals present, bio-remediation
would not be feasible)
IV. Treatment Technologies
Available alternatives to incineration
Available innovative technologies
V. ARARS
Required treatment level
Residuals management
General RCRA closure/LDR requirements/TSCA requirements/state
requirements
VI. Other Factors
Previous removal actions
Time available/needed to implement remedy
State concerns
Public concerns
Preference to select innovative technologies
Ability to use institutional/engineering controls
3-7
-------
OSWER Directive 9835,13
guidance, one Enforcement-lead site (State Enforcement-lead) did
not follow available guidance and one Fund-lead site assumed that
the risk was substantial in the area of be remediated.
C. Estimates of current risk varied, in part, due to current land
uses. Future risks tended to drive the remedy selection process
rather than current risks (e.g., current risk was lower than the
risk in the assumed future use scenario) . There were some
inconsistencies on considering risks at sites concerning worker
exposure. This Paired Analysis study reviewed a few exposure
assumptions at most of these sites and findings suggest that
careful implementation of the recent guidance to standardize the
risk assessment methodology, and more consistency, is needed in
risk assessment development. The baseline risk assessments
performed by EPA often used very conservative exposure assumptions
and low toxicity values. Most of the PRP risk assessments used
site data and exposure assumptions that were less conservative.
0. Future risk was generally based on residential use and
exposure to soils and ground water. At some active sites
(Enforcement-lead) in some Regions, future use was assumed to be
commercial. This did not appear to be unreasonable.
3. Risk Management levels for both Fund-lead and Enforcement-
lead sites met Superfund program expectations. In general/ RODS
specified cleanup goals and, in most cases/ cleanup goals were
similar.
A. An important element in determining the remediation approach
is the projection of future land use conditions. This requires
the application of judgment relative to the site and its
surroundings. The determinations in the RODs studied appeared
reasonable.
3-8
-------
OSWER Directive 9835.13
In addition, a numerical tally of land use assumptions
indicates that the identification of future residential or
industrial use was not driven by whether the RI/FS was Fund-lead
or Enforcement-lead. Unrestricted land use was assumed at six
(three Fund-lead RI/FS, three Enforcement-lead RI/FS). This
assumption tended to arise at smaller sites in or near residential
areas. Two sites (both Fund-lead) provided for adjacent
residential use. At six sites (two Fund-lead, four Enforcement-
lead) the future land use scenario was development, but the nature
of the development was not specified. Two sites retained the
current industrial use as the goal (one Fund-lead, one Enforcement-
lead) . At one site (Fund-lead) the goal was not clear.
B. A second element, which is critical to achieving the
overarching statutory goal of protection of human health and the
environment, is the reduction of risk. The NCP now provides for
reduction of risk to within a range of 10"4 to 10"6 individual
excess lifetime cancer risk (a range of 10"4 to 10"7 had been
proposed at the time that the RODs were written.) This goal was
specified at both sites where the RI/FS was prepared by EPA and the
PRPs.
From a risk management standpoint, most sites selected risk
levels between 10"5 and 10"6. A 10"6 goal was established for source
control at eight sites (five Fund-lead RI/FS and three Enforcement-
lead RI/FS) . These were in or near residential areas or in one
particular EPA Region. Five sites (two Fund-lead; three
Enforcement-lead) had a target of 10"5' These sites were
commercial, industrial or were viewed as being unlikely for
residential development. A range of 10"5 to 10"6 was established at
four sites (three Fund-lead, one Enforcement-lead). One site
(Enforcement-lead) was slated for a RCRA clean closure, while
another site projected a 10'6 cleanup which was not based on a clear
methodology (Enforcement-lead, State oversight). Ten sites
3-9
-------
OSWER Directive 9835.13
specified remedial action soil concentration goals (five Fund-
lead, five Enforcement-lead).
4. Remedies selected appeared consistent with the NCP expectation
that principal threats posed by the site be addressed through
treatment.
A. In the Wood Preserving category, where the sites were most
alike, incineration was chosen at the two Fund-lead sites and
bioremediation was chosen at the two Enforcement-lead sites. The
two Fund-lead and one of the Enforcement-lead sites had similar
action levels; the level at the other Enforcement-lead site was
not specified but risk goals were provided.
In the PCB category, where the sites were also similar, at
three sites (two Fund-lead and one Enforcement-lead) , which were
in the same EPA Region, solvent extraction followed by incineration
was chosen. At the third Fund-lead site, a prior ROD provided for
capping of low level PCBs and incineration of hot spots
contaminated with dioxin. The ROD for the site reviewed for this
paired analysis provided for incineration of hot spots containing
dioxin, and a synthetic cap. The final site (Enforcement-lead),
which had considerable metals content, included incineration of hot
spots with the remainder treated off site to meet RCRA land
disposal restrictions associated with the sludge at the site.
In the Solvents category, the ROD at one Fund-lead site
required incineration of hot spots, with capping of some areas and
t
no action at others. A second Fund-lead site, where contamination
was relatively low, provided for soil flushing in some areas. One
Enforcement-lead site included solidification/stabilization. The
other Enforcement-lead site provided for soil vapor extraction
followed by solidification. Both Enforcement-lead RODs required
that the treatment be sufficiently effective so that leaching from
3-10
-------
OSWER Directive 9835.13
residuals would not cause an exceedence of health based levels in
ground water. A treatability test will be performed to assure the
remedy will reach those levels.
In the Industrial Landfill category, one ROD called for total
incineration at a Fund-lead site. This was the smallest of the
Industrial Landfill sites, and incineration was the most feasible
remedy, due to the location of residences. The other Fund-lead
site required low temperature thermal treatment of principal
threats and a RCRA Subtitle C cap. One Enforcement-lead site
required soil vapor extraction of principal threats and a RCRA
Subtitle C cap. The other, where soils did not constitute a
threat, provided for a RCRA Subtitle C cap and treatment of
leachate.
B. Differences in the treatment selected at similar sites may be
appropriate if the remedy achieves similar remedial action
objectives. The allowable concentration of residuals remaining in
the source would be expected to differ between sites because of
differences in land use assumptions (e.g., unrestricted residential
versus industrial), target risk levels, designation of principal
threats (e.g., ingestion of soils versus ingestion of ground water
affected by leaching) and engineering controls. Selected residual
levels may also be affected by other contaminants, environmental
factors, and State ARARs. A standard methodology has not been
defined for the process of determining principal threats, which
necessitates flexibility in selecting soil levels to be treated.
For the Wood Preserving category, treatment was selected at
all sites. The soil cleanup levels at three of the four sites were
similar; visual contamination plus a buffer zone was selected at
the fourth site (Enforcement-lead, state oversight) with
confirmation sampling to assure health based levels were reached.
3-11
-------
OSWER Directive 9835.13
For PCB sites, treatment was selected at all the sites
studied. The PCB soil cleanup levels selected were within an order
of magnitude (1-lOppm) at two Fund-lead sites and one Enforcement-
lead sites in one Region. In the other Region cleanup levels were
visual contamination at the Fund-lead site arid meeting clean
closure levels at the Enforcement-lead site.
For the Solvent sites, treatment was selected at all sites.
The two Enforcement-lead sites specified soil cleanup levels. For
one of the Fund-lead sites no cleanup levels were provided since
the risks posed by direct contact were within acceptable levels.
The risks posed by contaminants leaching into the ground water
were, however, unacceptable. At the other Fund-lead site, no
cleanup level was provided other than risk goals. At the two
Enforcement-lead sites, solidification technologies were selected
with treatability studies planned during the remedial design rather
than the RI/FS (One site did call for soil vapor extraction prior
to solidification to reduce the organics). Present guidance
encourages treatability studies during the RI/FS to reduce
uncertainty. Since performance goals were established in these
RODs; the uncertainty will be addressed before implementation.
For Industrial Landfills, treatment was selected at three
sites. One Fund-lead ROD (which selected incineration for the one
acre site) provided for soil cleanup concentrations.
Regional variations may occur in the type of treatment
preferred if the Region has previous knowledge or experience with
specific treatment remedies.
5. No inappropriate influences by PRPs were detected.
A. The PRPs submitted comments at Fund-lead sites and conducted
RI/FS at Enforcement-lead sites. The opportunity to influence
3-12
-------
OSWER Directive 9835.13
decisions with technical comments was available at both Fund-lead
and Enforcement-lead sites. EPA considered PRP comments, and made
revisions to risk assessments and volume of waste calculations, and
considered innovative technologies that may be more cost effective
while still providing the appropriate level of protection to public
health and the environment, at both Fund- and Enforcement-lead
sites. At one of the ten Fund-lead sites, the PRPs submitted
comments concerning the amount of hazardous waste disposed of in
one area of the site. This information caused the Agency to select
a cap more similar to a municipal landfill than an industrial
landfill for this portion of the site. (The term municipal
landfill was meant to refer to sites with relatively smaller
amounts of hazardous waste disposed of versus industrial landfills
where relatively large amounts of hazardous waste are disposed
compared to municipal trash).
B. For two Enforcement-lead sites in the Wood Preserving
category, the PRP's ability to control access over a long period
of time allowed bioremediation to be a feasible option. For all
seven Enforcement-lead sites, the type of remedy selected was not
changed based on input from the PRPs. For two Enforcement-lead
sites, the option of reinjection of the treated ground water into
a drinking water aquifer was added as an alternative to deep well
injection, if conducted in such a way that it would not cause
spreading of the existing salt plume.
C. States must concur on remedies selected in order for EPA to
use Fund monies with state match for remedial action. EPA and the
State work closely together to develop remedies that are consistent
with State ARARs. The state influenced cleanup levels in three of
the five PCB sites evaluated (two Fund, one Enforcement). The
State also influenced the choice of off-site disposal rather than
on-site disposal for residuals at one of the PCB sites.
3-13
-------
OSWER Directive 983,5^13
D. PRPs do tend to draft risk assessments to show low risks at
sites. These risk assessments tend to need extensive modifications
by the Regions, or variations occur.
E. Public comments were extensive on over half of the sites.
The major topics were incineration, deep well injection and future
land use. Public comments resulted in changes to remedies
considered and selected in four Fund-lead and one Enforcement-lead
site.
3-14
-------
Section 4.0
Next Steps
-------
-------
OSWER Directive 9835.13
4.0 NEXT STEPS
1. EPA (or the state if Federally Funded) will develop all risk
assessments in the future.
The findings of this comparative analysis suggest that there
are twp main concerns related to the development of baseline risk
assessments. The first concern is that there continues to be
substantial inconsistency in the calculation of risks, including
assumptions used such as land-use scenarios and routes of exposure,
and in how the data is organized and presented in both Fund- and
Enforcement-lead sites. EPA issued in December, 1989 The Human
Health Evaluation Manual which provides general guidance on how to
develop baseline risk assessments. Second, some PRP-drafted risk
assessments tend to underestimate the risk posed by a site, in many
cases requiring a redraft by the Region.
Since there is extensive judgment in risk assessment
development and since risk assessments serve as the basis for
taking action and are a determinant in choosing treatment instead
of containment, and potentially affect what cleanup levels are
established, EPA will assume the development of all risk
assessments in the future.
OSWER will also continue its efforts to further define the
application of the risk range in assessing if action needs to occur
(baseline risk) and selection of remediation goals. Further work
will also address refining risk assessment assumptions (e.g.,
exposure factors and land use assumptions).
4-1
-------
OSWER Directive 9835.13
2. Consultation with Headquarters will be required on remedies
selecting "containment only" on all future RODS.
After reviewing selection of containment versus treatment
remedies in the general analysis, some improvement could occur in
considering some treatment technologies and in documenting why
treatment was not selected. In order to further improve
consistency in this area, the Agency will do several things.
The Agency will develop a process whereby remedies selecting
"containment only" will require consultation with the appropriate
Headquarters Division Director, Headquarters Office Director or the
Assistant Administrator for OSWER.
The Agency will continue to develop the START team/Regional
ORD coordinators concept to provide up-to-date information to the
RPMs on the results of various innovative technologies and their
effectiveness.
HQ Regional Coordinators or ORD will also initiate a review
of some projects at the workplan stage to ensure that innovative
technologies and treatability studies are considered.
3. The Agency will closely evaluate how principal threats are
defined and will determine if more prescriptive guidance is
required.
As described in the general and paired analyses, RODs
generally provided for treatment of principal threats. The process
of defining principal threats will be evaluated to determine if
additional guidance could be provided to enhance consistency.
4-2
-------
OSWER Directive 9835.13
4. EPA will utilize the ROD Forums to assure that Regions are
aware of areas that should be addressed in RODs. Other
information exchange programs will continue to be emphasized.
As found in the paired analysis portion of this report as well
as in the FY89 ROD evaluation report, remediation goals are not
always clearly or completely specified. ROD forums will serve as
the basis for discussing what is required in specifying remediation
goals and for clarifying other areas found in the FY89 ROD
evaluation report.
Other information exchange mechanisms such as the RODs data
base, publishing of the ROD Annual Report, finalization of the
Annotated Technical Reference will continue to be emphasized.
In addition, based on the Superfund Management Review. HQ
Regional Coordination efforts will be increased to meet the need
of providing assistance to the Regions to promote consistency in
ROD development.
5. EPA will continue to strengthen oversight of PRP actions to
assure that activities are conducted consistent with Agency
policy and guidance.
EPA has already increased the Regional budget pricing factors
in FY90 and FY91 based on the Superfund Management Review. These
increased resources will enhance the Regions' ability to oversee
PRP-lead RI/FS sites. Regions will also be reminded in the ROD
forums that vigilant oversight of PRP and State efforts is
important to ensure program consistency.
4-3
-------
OSWER Directive 9835,13
In addition, the Agency will soon release for Regional use,
a recent Agency-conducted evaluation of PRP-conducted RI/FSs which
identifies areas in RI/FS oversight that need improvement. The
Agency is also developing an RI/FS oversight manual for Regional
use at sites where the RI/FS is being conducted by PRPs. This
manual is being designed to assist RPMs in identifying problem
areas.
6. Efforts in FY91 will focus on providing updated cost data from
ongoing remedial actions to the Regions, and in enhancing
regional cost estimating capabilities.
The remedial action costs for some of the site types do show
differences. Some site types show Fund-lead sites as having
greater average costs and others show Enforcement-lead sites as
having greater average costs. In order to provide the Regions with
better cost estimating capabilities and to better evaluate cost in
the future, EPA for the FY-1991 RODs will provide the Regions with
actual cost data from ongoing remedial actions and will assure that
better defined cost data is provided in RODs.
7. EPA will look further into several of the sites discussed in
the general analysis where containment was selected over
treatment.
Several of the sites analyzed in the general analysis did not
clearly or thoroughly document why treatment was not selected.
Headquarters will continue to gather information on these sites to
evaluate the rationale used. If issues are found that cause
concern, the Agency will take steps to assure that future remedial
actions selected do not repeat that problem.
4-4
-------
Appendixes
Statistical Methods
Technology Selection Trends
Details of Cost Analysis
Summary Comparison of Sites in
Four Site Categories
NCP Expectations for Treatment
-------
-------
Appendix A
Statistical Methods
-------
-------
OSWER Directive 9835.13
INTRODUCTION
This appendix contains statistical analyses of data used in the
Comparative Analysis Study. Analytic methods and techniques were
used to go beyond simple summary statistics (such as averages and
percentages) and test the statistical significance of differences
found in that study. The results of these analyses statistically
justify these statements from the original study:
o The proportion of sites receiving treatment increased
significantly between 1987 and 1989.
o With respect to treatment vs. containment, there are no
systematic differences among combinations of lead and phase.
o The proportion of innovative treatment selection increased
significantly between 1987 and 1989.
o Enforcement leads selected a significantly larger proportion
of innovative technologies than did fund leads. Differences
between the two leads were significant in different time
periods.
The Comparative Analysis presented a number of other assertions,
but those do not demand statistical analyses.
We remind the reader to exercise caution when interpreting the
results, because of the many caveats associated with the data and
with the data-gathering and classification procedures.
The next major section presents the details of the statistical
techniques used to arrive at the aforementioned conclusions. The
analyses section presents the results of applying the techniques.
A-l
-------
OSWER Directive 9835.. 13
STATISTICAL TESTS USED
All tests were performed at the .05 level of statistical
significance. That is, in order to reject any null hypothesis, the
obtained values of our test statistics had to be sufficiently high
such that false rejection would result in an error less than 5% of
the time.
2-Test of the Difference Between Proportions
This technique was used to answer questions about the proportion
of sites receiving treatment, about innovative treatment selection,
and about technology selection by enforcement leads vs. fund leads.
It assesses the statistical significance of the difference between
two proportions by converting this difference into a z-score. The
sampling distribution of such a difference is approximately
normally distributed with a mean of zero and a standard error equal
to
in which o is estimated by
P
A// i
Then
A/I A/"?
in which each x is a frequency of events of interest and each n
represents a sample size. Calculated values are compared against
table values of the standard normal distribution.
Chi- square Test of Independence in a Contingency Table
This technique was used to test whether or not remedy selection was
independent of site lead. In this case, the data are cast as cell
frequencies in a contingency table of r rows and c columns,
resulting in a chi-square test with (r-1) X (c-l) degrees of
freedom. The chi-square is calculated as
A-2
-------
OSWER Directive 9835.13
in which 0 is an observed cell frequency, and E is the expected
frequency for that cell. The expected frequency for a cell is
calculated by dividing the product of its row and column totals by
the grand total of all observed frequencies.
Friedman Test
This test was used to see if there were systematic effects among
combinations of lead and phase. It is a non-parametric analog of
a randomized block analysis of variance. To carry out this test,
values of the dependent variable were ranked within each site-type
category/ and the ranks, rather than the original values, formed
the basis of the analysis. Within each combination of lead and
phase, the ranks were totalled over the site-type categories so
that
where n is the number of site-type categories, k is the number of
combinations of lead and phase, and R is the total of the ranks
for combination k. As the left side of the equation indicates, the
result was tested against tabled values of chi-square with k-1
degrees of freedom.
A-3
-------
OSWER Directive 9835.13
ANALYSES
Proportion of sites Receiving Treatment
The data in Figure 5 suggest that since 1987, the proportion of
sites receiving treatment has increased. Analysis confirms this.
The proportion of sites receiving treatment in 1987, .473, when
compared with the proportion of sites receiving treatment in 1989,
.67, results in a z-score of -2.41 (p < .05).
Treatment vs. Containment in Lead-Phase combinations
Tables 2-5 depict treatment and containment in the four
combinations of lead and phase. To analyze treatment and
containment, we formed the ratio T/(T + C) in which T is the number
of sites in a category for which treatment was selected, and C is
the number of sites for which containment was selected; if T and
C were both zero, the ratio was defined to be zero.
The ratio was analyzed for each of the four combinations of Lead
(Fund or RP) and phase (RI/FS or RD/RA) over all 16 site-type
categories. Friedman's Test was used in this analysis rather than
a randomized block analysis of variance because (a) the quantity
(T + C) varied widely within a category and between categories, and
(b) we couldn't be certain that T/(T + C) was normally distributed.
Our calculated value, 4.725, is not significant, indicating that
we cannot reject a hypothesis of no systematic effects among Lead
X Phase combinations. This supports the idea that the selection
of treatment or containment is independent of lead for either of
the phases of the remedial process.
Selection of Innovative Treatments
The data in Table 6 deal with the selection of innovative
treatments. The question of interest is the following: Is the
proportion of innovative treatment selection greater in 1989 than
in 1987? The difference in proportions (.33 vs. .53) results in a
z-score of -1.97 (p < .05), indicating that the 1989 proportion is
significantly higher than the 1987 proportion.
Did enforcement leads select a higher proportion of innovative
technologies than did fund leads? The relevant data, in Tables 7
and 8 result in proportions that are significantly different (.36
vs .64; z = -3.72; p < .05). This indicates that Enforcement leads
selected innovative technologies a significantly greater proportion
of the time than did fund leads.
A-4
-------
OSWER Directive 9835.13
Is this difference significant in all time periods? Two z-scores
(based on the data in Tables 7 and 8) answered this question.
First, the data from 1987 and 1988 were combined (because of too
few enforcement lead cases in 1987). The '87-'88 combined data show
that Enforcement leads selected a significantly higher proportion
of innovative technologies than did Fund leads (.30 vs. .63; z =
-.3.09; p < .05) in that time period. The second test, for 1989,
shows a similar result (.45 vs .64; z = -1.79; p < .05).
A-5
-------
-------
Appendix B
Technology Selection Trends
-------
OSWER Directive 983.5.13
The following tables describe which treatment technologies have
been selected in FY 1987-89 RODs, both the numbers of times a
technology has been selected, and the percentage of the whole that
selection represents. The totals are provided, as are the
subtotals by Fund- and Enforcement-lead. The technologies are
divided into two categories, available and innovative technologies.
Table B-l contains the figures for all treatment RODs; tables B-
2 through B-17 break the total figures down according to site type
category.
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Appendix C
Details of Cost Analysis
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OSWER Directive 9835.13
Appendix C comprises six graphs which illustrates the costs of the
RODs reviewed for the comparative analysis, including mean costs,
standard deviations, costs by site type, and costs by site type by
RI/FS and RD/RA lead.
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Appendix D
Summary Comparisons of Sites in
Four Site Categories
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OSWER Directive 9835.13
This appendix contains summary descriptions of the sites whose
characteristics and remedies were compared for the Paired Analysis.
Each site in the four site type categories is discussed in terms
of site characteristics, baseline risk assessment, remediation
goals, remedy selected, treatment versus containment, and
involvement and/or influence of potentially responsible parties and
others.
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OSWER Directive 9835.13
PAIRED ANALYSIS SUMMARY: LANDFILL (Industrial) SITES
The independent selection panel, choose four (4) sites for the
paired analysis in the landfill category.
SITE DESCRIPTIONS
Site A RI/FS Lead - Fund Planned RD/RA Lead - Fund
Site Description: Site A is approximately 1 acre in size and
approximately 20 feet deep. This site was initially operated as
a sand and gravel quarry which was subsequently filled with
hazardous and non-hazardous wastes. It is located in a rural
recreational use area; residences are located nearby. Bulk and
drummed wastes disposed at this site include oily wastes, solvents,
toluene-diisocyanate residue, and other hazardous and non-hazardous
wastes. Approximately 25,000 to 35,000 cu yd of hazardous waste
and contaminated soils are present at this site. Residents within
1/2 mile of the site use ground water for drinking. Ground water
in the source area at this site is also contaminated; however
contamination from the source area has not yet been found in the
nearby residential wells.
Remedy Selected: Major components of the selected remedy include
the following: Excavation and incineration of waste and
contaminated soils; disposal of treated material by backfilling it
on-site; ground water collection and treatment; and deed
restrictions to prohibit installation of drinking-water wells in
the contaminated plume until cleanup goals are met.
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OSWER Directive 9835.13
Site B RI/FS Lead - Fund Planned RD/RA Lead - FRP
Site Description: Site B is an inactive chemical and industrial
waste disposal site approximately 17 acres in size. It is located
in an area of mixed industrial, commercial, and residential use.
Nine acres of this site are highly contaminated. Bulk and drummed
wastes disposed at this site include waste oils, paint solvent,
resins, acids, and a variety of other hazardous and non-hazardous
wastes. Approximately 100,000 cu yd of waste material is present
at this site, 36,000 cu yd of which is highly contaminated. Due
to the high water table the buried wastes are in contact with
ground water. Ground water at this site is highly contaminated.
There is an oil layer floating on top of the ground water
approximately 5 feet below the ground. A previous operable unit
ROD (OU1) addresses the floating oil layer. Approximately 1/4 mile
from this site there is another superfund site which is believed
to have added to the ground water contamination at this site. In
addition, ground water contamination at this site is complicated
by high dissolved solids from a nearby highway maintenance salt
storage facility. Residents near the site use ground water for
drinking; however, none of the ground water wells are currently
contaminated.
Remedy Selected: Major components of selected remedy include the
following: Low-temperature thermal treatment of highly
contaminated soils (hot spots); RCRA Subtitle C cap over the other
contaminated soils; ground water pump and treat; reinjection of
treated water to promote flushing; deed restrictions to prohibit
use of ground water under the site and to protect cap.
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OSWER Directive 9835.13
Site C RI/FS Lead - Fund Planned RD/RA Lead - PRP
Site Description: This site is located on approximately 65 acres
of county-owned land. Site C is located in a mixed agricultural,
residential, and industrial use area. The site consists of the
incinerator building and adjacent property. Areas addressed in the
ROD include a former scrubber wastewater lagoon, an ash disposal
pit, aji ash pile, liquid disposal area and trench, and fill
landfill areas. This site is currently operating as a waste
transfer station. Different areas of this site have received
different type of wastes. Two very large areas of this site have
received mainly municipal wastes (trench and fill landfill areas),
therefore Site C has now been categorized as a municipal landfill.
Liquid hazardous wastes were disposed in one relatively small area
of this site. This portion of Site C, which has characteristics
similar to the other industrial landfill sites evaluated in this
category, will be the focus of comparison. The liquid disposal
area is believed to be the principal source of ground water
contamination at this site. Ground water contamination from this
site has affected the drinking water wells at residences and
businesses near this site. The process of implementing an
alternate water supply for the residences and business affected is
underway.
Remedy Selected: Major components of the selected remedy for the
liquid disposal area include the following: Soil vapor extraction;
vapor phase carbon treatment; ground water pump and treat; closure
with a RCRA Subtitle C cap; and deed restrictions to protect the
cap and use of contaminated ground water.
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OSWER Directive 9835.13
Site D RI/F8 Lead - PRP Planned RD/RA Lead - PRP
Site Description: Site D is approximately 3 acres in size and
approximately 45 feet deep. This landfill is located in a remote
area of mixed industrial and rural residential use. It was
permitted for the disposal of dry, non-hazardous industrial waste.
A predominant feature of this site is its rugged topography with
high relief. The surface of the landfill is capped with silty
clays, sand, and silty soils. Drummed and bulk wastes disposed at
this site include styrene, oily wastes, coal tar compounds, a
large quantity of foam materials, and other hazardous and non-
hazardous wastes. Total volume of waste disposed in the landfill
is believed to be 70,000 cu yds. In addition, it is estimated that
there is 30,000 cu yd of contaminated soil beneath the landfill.
The total leachate volume in the landfill is estimated at 7
million gallons. Ground water at this site is not presently
contaminated; however, there is potential for future soil, surface-
water, and ground water contamination from leachate.
Remedy Selected: Major components of the selected remedy include
the following: Dewatering landfill of leachate; leachate treatment
and discharge; RCRA Subtitle C cap; and deed restrictions, ground
water monitoring.
SUMMARY OF FINDINGS
I. Site Characteristics
The sizes of sites A, B, C, and D range from approximately 1 acre
to 17 acres. Sites A, B, and C are located on relatively flat
land, while a predominant feature of Site D is its rugged
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OSWER Directive 9835.13
topography with high relief. Even though sites A and D are closer
in size, the depth and rugged topography of Site D would make
excavation at this site much harder and would greatly increase the
short-term risks to workers.
Sites A, B, and C have extensive ground water contamination. At
Site B, other sources of ground water contamination exist.
Contaminants from the source area have not affected the ground
water at Site D.
II. Baseline Risk Assessment
EPA conducted the risk assessment for Sites A, B, and C. The risk
assessment for Site D was conducted by the responsible party. For
all sites, current risk from direct contact and ingestion of soils
were calculated using assumptions based on a trespassing scenario.
For Site A, risks were calculated only for soils outside the source
area; potential risks from soils in the source area were not
quantified. Current risks for soils outside the source area at
Site A were found to be less than 1 x 10"6 for ingestion. It was
presumed that risk would be higher in the source area. The maximum
current risk at Site B was from dermal absorption of contaminated
soils (1.5 x 10'2) , whereas the risk from ingestion was
8.8 x 10"5. Current risk for ingestion of soils at Site C was found
to be less than 1 x 10"6. Current and future risks from soil
ingestion at Site D exceeded 1 x 10"6 level for arsenic and
manganese only; however the ROD stated that these risks were
comparable to risks from naturally occurring background
concentrations of these substances in the U.S. Exposure to other
chemicals in soils at Site D did not exceed the 1 x 10"6 cancer
risk.
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OSWER Directive 9835.13
Three risk assessments were reviewed. There were inconsistencies
in the risk assessments reviewed. One risk assessment performed
by EPA was predicated on a worst case analysis, while another used
a low ingestion rate. At a site where the PRPs performed the risk
assessments (site D) low absorption factors were used and some
chemicals were not included in the group of indicator chemicals.
Potential future risks from source-area soils were calculated only
at Sites B and C. At Site A risks were not calculated for source-
area soils. At Site D, the present and future scenarios were the
same. Future risks from soils at Sites B and C were calculated
under the assumption that residents were living on site. Potential
maximum future risks from soils at Site B are 8 x 10"2 (dermal) and
1.4 x 10"3 (ingestion); for Site C ingestion risks range from 2 x
10"3 to 3 x 10"5.
Present and future risks from ground water exposure at all four
sites were calculated assuming daily use of ground water for
drinking and bathing. None of the drinking water wells near Sites
A and B were found to be contaminated. Maximum current risk for
ground water ingestion at the drinking water well at Site C is 1
x 10"4. Arsenic and two other chemicals exceeded the 1 x 10'6
carcinogenic risk level in ground water at Site D. Arsenic
contamination is believed to be from naturally occurring arsenic.
Concentrations of the other two chemicals were below MCLs. Current
risks from exposure to leachate at Site D exceeded 1 x 10"6 risk.
Potential future risks from ground water at Site A ranged from 1
x 10"2 (water table aquifer) to 4 x 10"5 (bedrock aquifer) .
Potential future risks from exposure to contaminated ground water
at Site B were found to be extremely high (greater than 1 for
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OSWER Directive 9835.13
ingestion)'. Potential future risk at Site C ranged from 1 x 10"1
to 1 x 10"3. Potential future risks at Site D were found to be due
to further contamination of ground water by leachate.
In summary, soils and ground water pose significant risks at Sites
B and C, and ground water at Site A also poses a significant risk.
Risks at Site D are due to potential of further contamination of
soil and ground water by leachate.
III. Remediation Goals/Remedy selected
Remediation goals at Sites A, B, C, and D included eliminating
direct contact risks from soils posing greater than 10"6
carcinogenic risk and reducing migration of contaminants from soils
to ground water. This will be accomplished by treatment of highly
contaminated material (principal threat) at Sites A, B, C, and D.
At Site A all wastes and contaminated soils would be removed and
incinerated. At Site B highly contaminated waste and soils will
be treated by low-temperature thermal treatment. At Site C the
principal source of contamination will be treated via soil vapor
extraction, and at Site D the landfill will be dewatered and
leachate collected will be treated and discharged. Since some
contaminated material is being left (under RCRA Subtitle C cap)
at Sites B, C, and D, deed restrictions on land and ground water
use will be placed at these Sites to protect the cap and prevent
the use of contaminated ground water.
The target cleanup goal for ground water at Site A is 10"6. Since
other sources added to the contamination at Site B, and since
cleanup to 10~6 would be below the detection limit for some
contaminants, 1 x 10"5 or attainment of MCLs, whichever is more
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OSWER Directive 9835.13
stringent was selected as the target cleanup goal for Site B. The
point of compliance will be monitoring wells at the down-gradient
edge of the slurry wall (from OU1) and RCRA Subtitle C Cap. site
C is an active industrial facility. The target cleanup level for
Site C is 10"6 and MCLs at waste boundary, nearest receptor. Ground
water monitoring is included as part of the remedial action for
Site D.
IV. Treatment vs. Containment
Selected remedial actions for all sites met NCP expectations in
that highly toxic and highly mobile wastes will be treated, and
engineering controls (capping) will be adopted for large-volume,
low-toxicity wastes.
All sites evaluated incineration of source materials. Total
incineration was selected only at Site A, the smallest site because
of implementation problems with capping. Capping at this site
would have required that approximately ten houses be demolished and
a road rerouted. Low-temperature thermal treatment of principal
threats (highly contaminated materials) was selected as the remedy
for Site B. Treatment of principal threats from VOCs at Site C was
handled via soil vapor extraction; incineration at this site would
cost approximately $53 million more than the selected treatment
alternative. At Site D, where the principal threat is from
leachate, the landfill will be dewatered and collected leachate
liquids will be treated and discharged to surface water. Since
some hazardous waste will remain at Sites B, C, and D, engineering
controls (RCRA Subtitle C cap) will also be implemented at these
sites.
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OSWER Directive 9835.13
V. involvement of PRPs and other influence
PRPs commented extensively on the RI/FSs and other technical
documents at the three Fund-lead sites. Substantial Regional
involvement and close oversight was required in the preparation of
the final FS for Site D (PRP lead). Public interest was also high
at the three Fund-lead sites. The PRP lead site generated very
little public interest.
The remedy at Site B was changed from incineration to low-
temperature thermal treatment to accommodate community concerns
regarding air emissions from incineration and to allow PRPs to
pilot test low-temperature thermal treatment. At a portion of Site
C not included in this comparison, based on additional technical
data provided by the PRPs, EPA changed the selected remedy from a
RCRA Subtitle C cap to a RCRA Subtitle D cap.
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OSWER Directive 9835.13
PAIRED ANALYSIS SUMMARY: FOB SITES
The independent selection panel chose five sites for the
paired analysis in the PCB category.
SITE DESCRIPTIONS
Site A RI/FS Lead - Fund RD/RA Lead - Fund
Site Description: This is a 1/2-acre site within a 9-acre parcel.
Activities at the site consist of a semi-active vehicle repair
facility and salvage yard. There was a spill of about 1000 gallons
of PCB dielectric fluid, which caused the site contamination. The
site surroundings are partially undeveloped, with some agriculture.
There has been surface migration of contaminants to between 6
inches and 2 feet of the soil. Near the spill area there is
localized ground-water contamination. The residences near the site
use private wells. The site is near a river. A former action
removed 800 cu yds of contaminated soil.
Remedy Selected: On-site solvent extraction with off-site
thermal destruction of hot spots where PCB concentrations exceed
50 ppm. Off-site incineration of concentrated extract.
Site B RI/FS Lead - Fund RD/RA Lead - Fund
Site Description: The site includes a 26-acre area. In the past
there was PCB disposal from industrial activities at the site. The
site setting includes active manufacturing, light industrial use,
commercial activities, and residences. Contamination extends very
deep, over 20 feet into the bedrock. The contaminated ground water
has not migrated off-site. There is some-surface water
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OSWER Directive 9835.13
contamination of a stream. In the past, 518 tons of soil
contaminated with PCBs greater than 50 ppm were removed.
Remedy Selected: On-site solvent extraction of unsaturated soils
with off-site thermal destruction of concentrated extract. On-
site thermal destruction is a contingent remedy if cleanup goals
cannot be achieved by solvent extraction.
Site c RZ/FS Lead - Fund RO/RA Lead - Fund
Site Description: This site has been contaminated by waste oil
containing PCBs used to fire boilers at a greenhouse. There are
Ğ
contaminated lagoons on site. Soil contamination extends to 40
feet; contamination decreases with depth. The shallow ground water
is contaminated, but the deep aquifer is not because of a clay
layer of very low permeability. A past ROD provided for
remediation of highly contaminated source materials in oil, pits,
lagoons, and surrounding soil by on-site incineration.
Remedy Selected: On-site thermal destruction of hot spots
containing dioxin and construction of a synthetic cap over the
majority of soils that are close to health-based levels.
Site D RI/FS Lead - PRP RD/RA Lead - PRP
Site Description: This 9-acre site is located within a larger
65-acre expanse of property with residences adjacent to the site.
The site consists of former transformer work areas, a scrap area,
and two lagoons. There are numerous contaminants in addition to
PCBs, including polyaromatic hydrocarbons (PAHs), chlorinated
benzene, and lead. Soils are contaminated to a depth of 10-12 feet
near transformer work areas, and there is ground-water
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OSWER Directive 9835.13
contamination. Past removal actions involved removal of tanks and
containers and installation of fences and signs.
Remedy Selected: On-site solvent extraction with off-site
thermal destruction of concentrated extract and post-extraction
treatment of some materials before disposal.
Site E RI/FS Lead - PRP RD/RA Lead - PRP
Site Description: This 4.8-acre active manufacturing site with
an unlined wastewater lagoon and sludge pit is in a mixed
industrial and residential area within a flood plain. No previous
removal actions have taken place. There are more than 5,500 cu yds
of sludge in a basin and pit on the site. Sludge (3,300 cu yds)
has also overflowed to a wooded swamp. The PCBs are in the upper
part of the sludge in the swamp area. The sludge consists
primarily of aluminum oxyhydroxides, calcium carbonate, and calcium
sulfate, and metals. The extent of ground-water contamination will
be addressed as a subsequent operable unit.
Remedy Selected: Excavation and off-site reclamation, if
available, or treatment to meet RCRA LDRs using the best
demonstrated available technologies. Off-site thermal destruction
of hot spots where PCB concentrations exceed 500 ppm.
SUMMARY OF FINDINGS
I. Site Characteristics
The source areas at the sites were somewhat different because of
differences in the operations that contaminated the sites. At
Sites A and D, PCB contamination resulted from handling capacitors
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OSWER Directive 9835.13
and transformers; at Site B, from industrial waste disposal; at
Site C, from waste oil tanks and pits. In contrast, PCBs were
found in some sludge materials at Site E.
Contamination at Site A is predominately restricted to the 1979
spill area and at Site E to the two disposal areas where disposal
occurred relatively recently. Disposal practices at Sites B, C,
and D occurred over several years, involved several on-site
disposal areas, and have resulted in extensive surficial and
vertical migration of contamination. At Site D, the contamination
extends 10-12 feet. At Site B the extent of contamination is
greater than 20 feet, and the deep aquifer is contaminated. At
site C surface contamination covers an extensive area; however, the
confining layer prevents vertical migration of contamination to the
deep aquifer.
The close proximity to residential areas and current use of the
sites vary. Residences are close to Sites A, B, and D, and two
persons (PRPs) reside on Site C but will relocate before
remediation begins. At Sites A and B industrial use continues.
Industrial use also continues at Site E, although not in the
contamination area.
II. Baseline Risks
EPA performed the risk assessment at all sites except Site E. For
Site E, the PRPs conducted the risk assessment, with EPA oversight.
The primary exposure routes at all sites were direct contact and
ingestion of ground water (except for Site E, where ground water
will be addressed as a subsequent operable unit). In addition,
D-13
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OSWER Directive 9835.13
there were environmental risks at Sites B and D. Other than PCBs,
the chemicals to which people could be exposed varied among the
sites.
Two risk assessments were reviewed and no variances were found.
The present risk at the sites was based on varying exposure
scenarios. At all sites the risk was premised on direct contact
by nearby residents who could enter the site. In addition, since
industrial use continues at Sites A, B and E, direct contact
exposures of workers to surface contamination were evaluated. For
Site B, the risk assessment, separates residential and worker
exposures for the site, because access to some areas of
contamination would be limited to workers.
The future risk at all sites was based upon an on-site residential
scenario. For all sites (except Site E) , future residential risks
from ingestion of on-site contaminated ground water and direct
contact with contaminated surface soil was evaluated because
residential areas are adjacent to the sites; at Site B residents
are living on-site but are not consuming ground water. Again,
direct contact with PCB-contaminated soils represents the highest
potential future risk.
The baseline risk was greater than 10'3 at all sites and was
primarily due to PCBs from current direct contact risks to
residents and workers, and to future ingestion of PCBs and organics
in on-site ground water.
III. Remediation Goals
The remedial goals at Sites A, D, and E provide for unlimited
future residential use. Of the five sites, these three had a
lesser extent of contamination. Also, for Site B, industrial use
D-14
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OSWER Directive 9835.13
areas of the site will receive partial treatment and containment,
and soils near residential areas will be excavated and treated to
achieve 1 by 10"6 levels and MCLS. For Site C, a previous ROD
addressed highly contaminated materials, and the 1989 ROD specified
that containment of the remaining contamination would approach
health-based levels.
Principal threats will undergo treatment at all sites. Sites A,
B, and D involve excavation and treatment. At Site C, treatment
of some areas containing dioxin is provided in this ROD, and
treatment of major source areas is provided in a prior ROD. In
addition, at Sites A, B, and D there were prior removals of highly
contaminated materials.
At all sites, the remediation goals to protect against direct
contact threats and ingestion of ground-water were in the 10"5 to
10"6 range, with a hazard index less than 1.0 for non- carcinogens.
The variation within the 10"5 to 10'6 range appeared to be based in
part on the EPA Region where the Site was located. Sites A, B, and
D were in one Region where the goal was at least 10"5 whereas Sites
D and E were in a different Region where the goal generally was
lO'6.
In addition, there were other variables. One variable was
commercial areas. At Site B, the areas near residents and
wetlands will be remediated to 10"6, while commercial areas, will
be remediated to 10"5 with soil cover which, as indicated by the
TSCA program, would reduce the risk by about one order of
magnitude. Site B did start with a 10~6 point of departure for the
remedial action goal for the commercial area, but it was adjusted
to 10"5 after weighing the technical feasibility of removing soils
under a building down to bedrock. Moreover, state ARARs and
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OSWER Directive 9835.13
environmental concerns resulted in more protective cleanup goals
at Sites A and D. In addition, the presence of another
contaminant, dioxin, affected cleanup goals at Site C. Finally,
RCRA clean closure levels will affect Site E levels.
A complete comparison of remediation goals in terms of
concentrations of contaminants is not possible because these were
identified by one Region (Sites A, B, and D) and not another (Sites
C and E).
IV. Treatment vs. Containment
All of the selected remedies are consistent with NCP and Superfund
program expectations. All RODs considered incineration, innovative
treatment of principal threats, as well as containment remedies.
Different treatment remedies were chosen for the sites based on the
consideration of specific criteria as presented in the NCP. The
criteria that were most important for the sites depended on site-
specific factors. A total incineration alternative was not
selected for any site due to high costs and other site-specific
factors.
As indicated above, at Sites A, D, and E all source materials above
health-based levels will be excavated to allow for unrestricted
future residential use (direct contact and ground water). sites
A and D will employ on-site solvent extraction with off-site
thermal destruction of concentrated extract. At Site D, this is
supplemented by post-extraction treatment as necessary before off-
site disposal, at Site A, by off-site incineration of soils with
relatively high levels of contamination. Site E involves off-site
incineration of a relatively small amount of highly contaminated
material. The sludge material is within RCRA waste F019. The
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OSWER Directive 9835.13
remedy complies with the proposed land disposal restriction
providing for chemical oxidation-reduction and/or stabilization.
The two sites where contaminants will remain at concentrations
above health based levels have the most contamination. The Site B
remedy involves solvent extraction with off-site incineration of
the residuals. A past ROD for Site C selected incineration of
highly .contaminated areas, and the more recent ROD specifies
containment of other areas.
For Site E, the selected remedy of excavation followed by off-site
treatment included contingencies in order to comply with RCRA LDRs
which were only proposed at the time the ROD was signed. The on-
site C cap is a result of a second ROD that responded to lower
levels of contamination. The remedy was considered to be effective
in part because of the nearly impermeable cap and because of a
confining layer above the lower aquifer.
V. Involvement of PRPs and Other Influences
PRP involvement did not influence EPA to select less effective or
less protective remedies at the PCB sites. For Sites D and E,
Enforcement-lead sites, the selected remediation goals will allow
for unlimited future access, and cleanup goals for these sites are
considered protective of human health and the environment. At the
Fund-lead Site C, PRPs were active in reviewing and commenting on
the remedial approach.
Community concerns affected the remedy selection decisions for some
sites, in particular, complete incineration of all contamination
was not selected in part because of public opposition at Site C.
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For Site D, citizens expressed a desire to have no restricted
future uses of the site.
State involvement affected the remedy selection at a few sites,
particularly at Site A, where the State modified the remediation
goal and requested that the treatment residuals receive post
treatment and be disposed off-site rather than on-site.
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PAIRED ANALYSIS SUMMARY: SOLVENTS SITES
The independent selection panel chose four sites for the paired
analysis in the solvents category.
SITE DESCRIPTIONS
Site A RI/FS Lead - Fund RD/RA Lead - Fund
Site Description: The site is roughly 50 acres in area, of which
about 25 acres were contaminated by a former, on-site waste oil and
solvents recycling operation. The site is in a rural setting with
croplands and uncultivated areas, along with residential and
industrial development. Residences and a high-density residential
facility adjoin the site. In addition to oil residues, the main
contaminants are VOCs, PAHs, PCBs, phenols, phthalates, pesticides,
and metals. There are nine separate contaminated areas, lying
mainly in a flood plain. Buried wastes consisting of sludges and
filtering materials from site operations are in one site area,
whereas contaminated soils and sediments, ranging to depths of 15
feet are found in the remaining areas. Contaminated ground water
occurs in alluvial overburden and bedrock at the site. The river
adjacent to the site receives surface drainage and ground-water
seepage.
Remedy Selected: Excavation and on-site thermal treatment for
waste materials from one area and the contaminated on-site
sediments, with backfilling or solidification and backfilling of
the residues (depending on toxicity) ; contaminated source materials
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left in place in other areas and covered either with a stabilizer
layer and revegetated soil or with revegetated soil only; deed
restriction to prevent on-site soil disturbance and well drilling.
site B RI/FS Lead - Fund (State) RD/RA Lead - Fund
Site Description: The site comprises 20 acres, where nearly 10
acres are contaminated by off-site industrial waste disposal from
a former salvage operation for containers used to store and
transport chemicals/chemical wastes. The site, with an on-site
residence, is located in a wooded area among small farms and
residences in a rural-agricultural setting. site soils and the
upper portion of the shallow aquifer are contaminated by VOCs,
semi-volatiles, and PCBs. The ground water also contains metals.
A removal action conducted earlier eliminated the major
contamination in source materials.
Remedy selected: Flushing system for soils to remove low-level
residual contamination from further contaminating groundwater in
a portion of the site; vegetative soil cover over the complete area
of contamination; if found, contaminated soils in hot-spot areas
will be excavated and incinerated; ground water pumping and
treatment; access restriction by fencing during remedial actions;
deed restriction for notification of on-site intrusive activities.
Site C RZ/FS Lead - RP RD/RA Lead - Fund
Site Description: This site is a 7-acre, abandoned, industrial
waste storage and disposal facility in a semi-urbanized area.
There is light industrial and commercial development nearby, with
the nearest residence about a mile away. Remnants of natural areas
and wetlands surround the site. The principal contaminants are
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VOCs, including benzene, toluene, and TCE; other organics,
including PAHs, PCBs, and phenols; and metals. VOCs are less than
0.4% in source materials. Roughly 3.5 acres of the sandy soils and
fill are contaminated to depths that extend beneath the 10-foot-
deep water table at the site. Sediments adjacent to the site also
are contaminated. A plume of contaminated ground water leaves the
site, although the surficial aquifer is also contaminated from
multiple other sources and is saline. Private wells, not intended
as a source of drinking water, are about a mile away from the site.
Contaminated ground water and surface waters from the site seep
into the wetlands and an adjacent drainage way. An earlier surface
removal action took place at the site.
Remedy Selected: On-site treatment of soils and sediments by soil
vapor extraction followed by solidification/stabilization followed
by on-site deposition; final RCRA cover, if applicable (determined
by testing of solidified materials) ; ground-water pumping and, deep
well injection or treatment (for hazardous substances) and either
deep well injection or aquifer reinjection (for treated, salt-
contaminated water); restrictions on site access and deed
restrictions, as necessary.
Site D RI/FS Lead - RP RD/RA Lead - Fund
Site Description: The site comprises roughly 4 acres and is an
abandoned, off-site industrial waste storage, recycling, and
disposal facility. The site is within one-quarter mile of a
residential development and is located in a semi-urbanized area of
mixed residential, commercial, and light industrial land use. It
is bordered by commercially developed land and undeveloped land
having low sand dunes and wetlands. About 2.6 acres of sandy soils
and fill at the site have contaminated soils that extend below the
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5-foot-deep water table. The major contaminants at the site are
VOCs, including benzene, toluene, and TCE; other organics,
including PAHs, PCBs, and phenols; and metals, including chromium,
and lead; and cyanide. VOCs are as high as 1.1% by weight in
source materials. Contaminated ground water has migrated off-
site; however, the aquifer is saline and contaminated from multiple
other sources. Contaminated ground water seeps into adjacent
wetlands; surface water runoff from the site also enters the
wetlands. A prior removal action for surface materials took place
at the site.
Remedy Selected: On-site treatment of soils by a combination of
vapor extraction and solidification/stabilization with on-site
deposition of solidified materials; final RCRA site cover if
applicable (depending on testing of solidified materials); ground-
water pumping and deep well injection or, treatment of hazardous
constituents and either deep well injection or aquifer reinjection
of the salt-contaminated effluent; restrictions on site access and
deed restrictions, as needed.
SUMMARY OF FINDINGS
I. Site characteristics
Although site-characteristics have similarities, there are also
differences in features which make each site distinct.
Physical conditions at the sites have both similarities and
differences. Site A is mainly situated in a flood plain adjacent
to a major river where it is underlain by alluvial soils and other
overburden. In contrast, Site B is in an upland area having
permeable sandy soils, and Sites C and D are each in partially
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filled lowland areas with wetlands in sand dune and swale
topography occurring adjacent to the sites.
Sizes of the sites differed, as did the operational and waste
management practices that took place at some of the sites, which
have bearing on the distribution of contaminated materials. Site
A is larger than the other sites; it is a former recycling facility
for waste oils and solvents. Wastes (sludges and filter materials)
from processing were disposed of in nine separate areas covering
a total of 25 acres. At Site B, drums and pails were recycled,
which resulted in discharges of residuals from the containers as
well as solvents that were used in the cleaning process. As
compared to Sites A, C, and D, relatively lower volumes of wastes
and solvents were released in the 10-acre contaminated area at Site
B. Sites C and D (operated under the same general ownership and
waste management practices), are abandoned facilities which
accepted large volumes of bulk and liquid industrial wastes for
storage, recycling, and disposal. Roughly 2.5 acres of land at
Site C and 3.5 acres at Site D have source materials remaining on-
site that are generally contaminated above levels of concern.
Greater volumes of waste were disposed of at Site D than Site C.
Types of contaminants at the sites, although similar (predominantly
solvents), differ in concentrations. Contamination may be
categorized as organics/metals at Sites A, C, and D, as opposed to
organics at Site B. Site A has one area where concentrated
processing wastes are found; contaminant levels in source materials
are higher at this location than in the other areas of soils and/or
sediment contamination. Site B, as now known, has only relatively
low-level contamination in source materials subsequent to the
earlier removal action. Sites C and D have generally higher levels
of contamination that remain after removals at the sites, than at
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any of the other sites. Site source materials exhibit higher
contamination at Site C than at Site D. Ground water at all four
sites is contaminated.
Variations in site setting are found among the sites. Site A is
in a rural area with mixed agricultural, residential, and
industrial land use. Site B is in a rural, agricultural area with
scattered residential development and includes an on-site
residence. Sites C and D are each in semi-urbanized areas with
mixed residential, commercial, and light-industrial development.
The area surrounding Site C is more developed than that near Site
D. Although further residential development is unlikely near
either Site C or Site D, there is a greater chance that such
development will occur near Site D.
II. Baseline Risks
Similar exposure routes were examined in the risk assessment for
the four sites. In all cases, the greatest threats were determined
to be associated with ingestion of contaminated soils and ingestion
of contaminated ground water. Other exposure routes associated with
or incidental to ingestion were sometimes included in the exposure
scenarios representing the greatest threats. With regard to Site
A, incidental exposures were considered along with ingestion for
both source materials and ground water; modelling was used to
estimate the affects of contaminated ground water on the water
quality of the river, a downstream source of drinking water, and to
estimate risks from ingestion of fish from the river. For Site B,
exposure routes were screened to eliminate incidental exposures,
with only the routes presenting the greatest exposure and potential
health threats (i.e., ingestion of contaminated soil and of
contaminated ground water) used in risk estimation. Ingestion of
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contaminated soils and ground water connected with Sites C and D
included incidental exposures, for which inhalation of volatiles
during household use of ground water made a significant increase in
estimated risks.
Three risk assessments were reviewed and the two Fund-lead risk
assessments selected ultra-conservative exposure assumptions.
Specific indicator chemicals, selected from the contaminants
presenting the greatest threats at the sites, were used as the basis
for risk calculations at Sites A and B. For Sites C and D, however,
risks were estimated from exposure to all hazardous substances found
at the sites.
There were different determinations of current and future threats.
In the baseline risk assessment for Site A, current exposures to
source materials were examined, but only future exposure to ground
water was considered since the only on-site well was closed due to
contamination which the ROD indicates was not associated with the
site. At Site B, the risk assessment was predicated upon both
current and future options for land and ground water use. For Sites
C and D, the risk assessments were based on future development of
the sites and site areas, without site remediation, including
exposure to soils, sediments, and surface waters, and residential
use of the ground water. Information was not given for exposures
under present conditions. (There is now security fencing around
both Sites C and D.)
Estimated maximums for cumulative, lifetime carcinogenic risks (in
rounded numbers) ranged from 4 x 10"4 to 3 x 10"6 for soils/source
materials and 2 x 10 to 5 x 10 for associated ground water at the
sites. By site, for soils these are 6 x 10"5 for Site A,
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3 x 10~6 for Site B, 4 x 10"4 for Site C, and 7 x 10~5 for Site D.
For ground water they are 2 x 10"1 for Site A, 5 x 10"3 for Site B,
3 x 10"2 for Site C, and finally, 5 x 10~2 for Site D.
Corresponding estimates of non-carcinogenic risks (as indices) were
calculated but are not shown here. All sites were considered to
have non-carcinogenic risks from contaminants in source materials
and ground water.
III. Remediation goals
Remedial goals for the sites are based on current and anticipated
future use of the sites and the site areas. The remedial objectives
for Site A are somewhat different from the objectives for Sites B,
C, and D. Objectives for Site A are to reduce risks associated with
exposure to contaminated materials in the site areas and to prevent
exposure to contaminated ground water beneath the site, located in
a flood plain area. For Sites B, C, and D, there may be future
development since they are upland locations. The ROD for site B
contemplated unrestricted use of the site arid area, including
residential use, while the RODs for Sites A, C, and D did not
specify the nature of possible development. Remedial goals for
source materials are not established for Site A; however, maximum
limits for no action were determined at approximately 10"5 for one
area, 10"5 to 10"6 for four areas, and 10*6 for the other four
contaminated areas. At Site B, an objective for remediation of
source materials is to prevent further contamination of ground
water. Additionally, since the site is to be returned to conditions
for unrestricted or residential use, a cleanup goal of 10"6 is
established. Remedial objectives for Sites C and D are to reduce
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health threats to future development of each of the sites. Remedial
goals for soi
respectively.
goals for source materials at Sites C and D are 10'5 and 10~6,
Ground water goals also differ among the four sites. According to
the ROD, conditions for establishing Alternative Concentration
Limits (ACLs) for ground water are met at Site A, CERCLA ACLs are
established in the ROD because of the flood plain location. Well-
drilling restrictions, furthermore, are determined to be a necessary
part of any remedial action. Remedial goals at Site B are 10"6 or
the attainment of MCLs for allowing unrestricted use, corresponding
to site land use. For Sites C and D, the remedial goals for ground
water (10'5 amd the attainment of MCLs) are less stringent than at
Site B due to: the semi-industrialized settings, the multiple other
sources of contamination, and the unacceptable salt in the ground
water from off-site areas and fill.
Differing approaches for determining the risk-based need for
remediation and remedial goals occurred among the sites. The Region
where Site A is located uses internal peer review and evaluation by
toxicologists and appropriate experts to determine these. Under
this method, the remedial goals may, or may not have definite
relationships to EPA's accepted risk range. Another Region, with
Sites B, C, and D uses 10"6 as the cleanup goal and as a lower
boundary point of departure for determining relative need for
cleanup, unless conditions at the site and within the area of
influence of the site suggest differently.
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IV. Remedies Selected
The selected remedy for Site A combines treatment of contaminated
materials (i.e., waste filtering materials and sludges) by
excavation and incineration from the site area that poses the
greatest threats, combined with soil covering or no action for the
other contaminated areas. On-site thermal treatment (incineration)
and backfilling of treatment residues (ash) was selected because it
provides a permanent and cost-effective remedy for the wastes,
although capping requirements for the residues remains to be
determined. In certain areas of site A, the addition of a layer of
stabilizer followed by placement of a revegetaged soil cover or
placement of a revegetated soil cover only are selected as remedies
for the less-significant contamination. No Action is considered
appropriate for two areas having minimal risks. After remediation,
Site A still requires restricted access and restrictions on well
drilling and use of ground water.
In order to reduce leaching of contaminants into the ground water
at Site B, soil flushing is selected to further reduce levels of
contamination in a portion of the contaminated area where the levels
in the soil remain the highest after the past removal actions. The
levels are relatively low, thus further treatment is not warranted.
According to the ROD, it is expected that the flushing will provide
the reduction in soils contamination to prevent further ground-
water degradation since organic chemicals in source materials are
the concern; metals in soils are not considered to be a problem.
As an additional measure prior to soil flushing, the ROD provides
for investigation and excavation and incineration of material
containing a particular organic contaminant which may be present at
higher levels in hot spots. Soil covering and revegetation of the
entire area of contamination is to take place because contaminated
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materials are being left in place, at least to some extent.
However, upon completion of soil and ground-water remediation, Site
B will have unrestricted land and ground-water use.
For Sites C and D, there is a contingency in the selected remedy
which affects only the ground-water portion of the remedy. For
source-control at each site, solidification/stabilization is
selected as the principal component for materials above the water
table. The ROOs indicate that this is the least expensive
alternative that will permanently reduce the toxicity, mobility,
and volume of the source and be fully protective; implementation,
however, depends on results of treatability tests.
Solidification/stabilization will be considered successful when it
reduces the mobility of contaminants so that leachate from the
solidified mass will not cause exceedance of health-based levels in
the ground water. Pretreatment by soil vapor extraction is included
in the remedy for Site D but not for Site C. It is intended to
reduce VOCs (greater than 1% by weight), which are still in soils
after the removal action, until they are below levels that would
pose a health threat and to levels that will allow
solidification/stabilization to proceed successfully. Depending on
toxicity levels, a RCRA cap or soil covering will be placed over the
stabilized mass at each site to reduce residual risks. Emissions
at Sites C and D from soil excavation and handling,
solidification/stabilization, and ground-water treatment, as well
as soil vapor extraction at Site D are to be controlled. Both Sites
C and D are expected to have land capable of being developed to some
extent, although residual risks from contamination will be different
for the sites. Ground-water cleanup for the sites will permit
future use, although at degraded quality.
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The ROD for Site A established CERCLA ACLs for ground water. Ground-
water remediation for Site B is by treating water that is extracted
by pumping operations, until the MCLs are met. For Sites C and D,
ground-water contingencies are to: pump and deep well inject the
contaminated water; if the salinity is not being removed, pump,
treat, and either deep well inject or aquifer reinject the effluent
from treatment (if aquifer reinjection does not cause spreading of
the existing salt plume). For the portions of the aquifer affected
by each site, 10"5 levels and MCLs are to be reached in remediation.
Maximum allowable contaminant concentrations were not established
for source materials and ground water at Sites A and B but were
established for Sites C and D; CERCLA ACLs were set for ground water
at Site A. These allowable levels were determined by calculations
based on remediation goals using carcinogenic and non-carcinogenic
risks.
Selected remedies for the sites are all consistent with the goals
of the NCP. That is, the remedies reduce the mobility, toxicity,
and volume of the contaminated materials, with treatment preferred,
or treat the principal threats or hot spots and contain the lower
levels of contaminated materials.
Levels of contamination and economics play a role in remedy
selection. For Site A, on-site incineration was chosen for
contaminated materials posing the highest threats, which mostly
consist of highly concentrated wastes, and areas of lower-level
contamination were remediated by soil covers. At Site B, due to
relatively low contamination levels and sandy soil, incineration
was not considered except for possible hot spots, which may or may
not be identified. Soil flushing using treated ground water
alleviates disposal problems for effluent from ground-water pumping
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and treatment, assuming the contaminated ground water and flushed
contaminants are collected and treated effectively. Since soil
vapor extraction and solidification/stabilization at Site D, and
solidification/stabilization at Site C are considered to be as
effective in reducing mobility and toxicity as the other full-
spectrum treatments evaluated, there were considerable cost savings.
V. Involvement of PRPs and Other Influences
The PRPs of Site A for which the Fund conducted the RI/FS agreed
with the selected remedies for all but one of the contaminated
areas, the area with materials slated for incineration. PRPs for
Site B did not offer substantive comment regarding remediation.
For each of Sites C and D, the PRPs initially did not respond to
court actions to conduct the RI/FSs but later took over the work
and agreed to continue the work following EPA's work plans. The
RI/FSs prepared by the PRPs indicted that solidification/
stabilization would be effective. After modifying the RI/FSs, EPA
proposed that remedy for the sites, but added soil vapor extraction
for Site D to treat the volatiles. The PRPs commented extensively
on the proposed remedies. Because of the comments, the option for
reinjection of treated ground water into the saline aquifer was
added as an alternate to deep well injection, if spreading of the
salt plume is not caused. PRP comments, therefore, did not
substantially alter the selected remedies for Sites C and D,
although a possible alternative was added.
The state concurred with the selected remedy for Site A, although
conditions for the concurrence were stipulated. For Site B, the
state conducted site investigations under cooperative agreement with
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EPA. The state's position was reflected in the reports used by EPA
in preparing the ROD, upon which the state concurred. Remedies for
Sites C and D had state backing and concurrence.
Public comment on remedy selection at Site A was not substantial,
although there was opportunity for input through public meetings.
Community interest in Site B was nominal, without preference for a
particular remedy. Public interest in Sites C and D was moderate.
The main comments were questions relating to deep well injection,
as well as opposition to it. Changes in the selected remedies were
not necessary because of public participation in remedy selection.
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PAIRED ANALYSIS SUMMARY: WOOD PRESERVING SITES
The independent selection panel, chose four sites for the paired
analysis in the wood preserving category.
SITE DESCRIPTIONS
Site A RI/FS Lead - Fund RD/RA Lead - Fund
Site Description: This 55-acre abandoned facility consists of waste
piles (5000 cu yd) and sediments (150,000 cu yd) contaminated with
polynuclear aromatic hydrocarbons (PAHs) which have been targeted
for remediation. The site is adjacent to a residential area.
Remedy Selected: On-site thermal destruction.
Site B RI/FS Lead - Fund (State) RD/RA Lead - Fund
Site Description: This 100-acre site is an abandoned facility that
was redeveloped for residential and commercial use. Contaminated
soil from the residential area (20,000 cu yd) and industrial area
(9,500 cu yd) and contaminated material from waste lagoons (40,000
cu yd) have been targeted for remediation. Contaminants of concern
are PAHs, pentachlorophenol (PCP), and some dioxins/furans.
Remedy Selected: On-site supercritical fluid extraction followed
by off-site thermal destruction of concentrated residuals.
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Site C
RI/FS Lead - PRP
RD/RA Lead - PRP
Site Description: This active industrial facility was formerly a
wood-treating facility and has soil contamination in waste pit and
dip areas consisting predominantly of PAHs, PCP, and some
dioxins/furans. The RI/FS identified 15,000 yd3 of contaminated
material for remedial action. Residential area is nearby. Ground-
water contamination is a major focus of this ROD.
Remedy Selected:
unit.
On-site bioremediation in a lined land treatment
Site D RI/FS Lead - PRP (State oversight) RD/RA Lead - PRP
Site Description: This 105-acre active wood-treating facility has
soils and sediments from former lagoons and drip areas contaminated
with PAHs, PCP, and some dioxins/furans. The remedial
investigation/ feasibility study (RI/FS) identified 15,000 yd3 of
contaminated material for remedial action. The closest residence
is 3/4 of a mile away; few residents are near the site. Ground-
water remediation is the primary focus of remedial action at this
site.
Remedy Selected: On-site bioremediation in an "engineered cell."
The RODs for all of these sites are final source-control actions.
Sites A, C, and D also include ground-water actions as part of the
current Records, of Decision. No-Action was selected for ground
water at Site B in a previous ROD. Interim actions previously
occurred at Sites B and C to limit exposures or prevent contaminant
migration.
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SUMMARY OF FINDINGS
The following conclusions can be drawn from the analysis for these
four wood preserving sites:
I. Site characteristics
The contaminants present in soils at the four sites are similar and
resulted from oil-borne wood preserving processes. PAH
contamination is present at all sites. Sites B, C, and D also have
contaminated pentachlorophenol (PCP) and dioxins/furans.
The volume of contaminated soils, which varied from 15,000 cu yd to
155,000 cu yd, was a factor affecting the implementability of
particular remedies.
II. Baseline Risk Assessment
Major exposure routes considered for the four sites varied.
Exposure pathways of concern at Site A included ingestion of
contaminated ground water, ingestion of contaminated soil, ingestion
of contaminated sediments, and dermal contact with bayou sediments.
For the 1989 ROD at Site B, only risks due to exposures to
contaminated soil were investigated. A 1986 ROD selected natural
attenuation for the contaminated ground water, which is not a
potential source of drinking water. For Site C, ingestion of soil,
inhalation of contaminants attached to soil, dermal contact, and
ingestion of ground water were considered in the baseline risk
assessment. For Site D, risks associated with consumption of
contaminated ground water and inhalation of volatilized contaminants
from the site were the only exposure routes quantified. No direct
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contact or on-site exposures were considered in the risk assessment
for Site D, despite the presence of surface contamination. (Note:
Site D was State-lead and EPA did not concur on the risk
assessment.)
Only one risk assessment was reviewed. This risk assessment
performed by the PRPs used some limited exposure assumptions and
eliminated some chemicals which may underestimate risk.
Risk assessments for Sites A, B, and C considered both residential
and commercial use of the land. Site A is currently adjacent to
residential areas but is not expected to have residents living on
site. Commercial use or recreational use is more likely. For Site
B, these land uses represent both the current and future use
expected for the site, since it is currently used for both purposes.
For Site C, the current land use is industrial but the risk
assessment addressed future residential use of the land, current
industrial use, and future on-site construction. At Site D the risk
assessment focused on future residential use adjacent to the site.
No risks for the industrial land use were considered, despite that
being the current and future land use.
Risks at site A were initially considered before Superfund risk
assessment guidance was issued in 1986; therefore different
methodology was used to consider risk. For this site, instead of
calculating a baseline risk, an action level that was associated
with acceptable risk (10~5 excess cancer risk for residential use,
10~6 excess cancer risk for commercial use) defined areas of the
site that would require cleanup. For Site B, worst-case lifetime
excess cancer risks associated with residential exposure are
estimated to be no greater than 7 x 10"2. The lifetime excess cancer
risk associated with future residential use of Site C is 4 x 10"3 for
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the site as whole. For industrial use and construction worker
scenarios at Site C, the lifetime excess cancer risk associated with
the site as a whole is approximately 2 x 10"4. Residential use of
the ground water (2 liters of water per day) is associated with a
risk of 3 x 10"4 excess cancer risk. For Site D, the estimated total
excess incremental cancer risk due to consumption of drinking water
is between 2 x 10"4 and 5 x 10"4. An inhalation risk was calculated
assuming that a residence was established immediately adjacent to
the site, and the lifetime excess cancer risk was estimated to be
1.5 x 10"5. No on-site or direct contact exposure was considered at
Site D; these exposures may potentially be associated with risk.
Consideration of on-site exposures to workers at a currently
operating facility is inconsistent between the two active industrial
sites. Exposures to on-site workers was evaluated at Site C
according to Superfund risk assessment guidance. Direct contact was
not considered at Site D because the PRPs argued that because the
facility was currently operating, any workers that may have access
to the surface contamination at the site would be observing OSHA
regulations and would therefore not be exposed to harmful
contamination, which discounts inadvertent exposure to
contamination. (Note: Site D was State-lead and EPA did not concur
on the risk assessment.)
Site D also assumed that fencing would be sufficient to eliminate
direct contact exposures. The PRPs argued that because the facility
is active and surface contamination was present in secured (fenced)
areas of the site, no trespassers would have access to the site.
Sites A, B, and C quantified the risk of direct contact to
contaminants at the site.
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The threat' of dioxins/furans was not handled consistently between
the sites. At Sites B and C, a dioxin-equivalence approach was used
to evaluate the risk of dioxins and furans. However, with
apparently comparable levels of contamination, dioxins and furans
were eliminated from consideration at Site C but at Site B were
considered a significant concern. At Site D, concentrations were
compared to an ATSDR action level and determined to be below a level
of concern. (Site A had no dioxins or furans or their precursors
on the site.) A consistent policy on addressing dioxin/furan
contamination would be useful.
III. Remediation Goals
Two Sites, A and B, developed cleanup goals assuming frequent
exposure due to residential land use either on or adjacent to the
site. At Site A, it was anticipated that residents would remain
adjacent to the site but that no residences would be on-site. At
Site B, cleanup goals were developed assuming current residents will
remain on-site. Cleanup goals for Sites C and 0 assumed that the
sites would remain industrial. At Site C, cleanup levels will allow
unrestricted industrial use of the site. For Site D, institutional
controls (OSHA requirements) are factored into the cleanup decision.
Site conditions resulted in different remedial action objectives at
the different sites. Although some ground water was remediated at
Site A, direct contact was the primary concern to be addressed.
Site B was remediated primarily to prevent direct contact exposures.
At Site C, remedial action focused on both ground water remediation
and prevention of direct contact exposures. At Site D, soil and
waste pits were remediated primarily to prevent further
contamination of ground water. Direct contact could have been
considered here but was not.
D-38
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OSWER Directive 9835.13
IV. Remedy Selected
Some form of treatment was used at all four sites. Incineration
was selected for Site A. Critical fluid extraction and incineration
of the concentrate was selected at Site B. Biotreatment was
selected for the two Enforcement-lead sites.
Two different biotreatment technologies were examined. For Sites
C and D, a landfarming type of biotreatment is contemplated, which
is less costly than incineration if space is available. Sites A
and B do not have space available for landf arming, so a biotreatment
reactor was examined. Bioreactors cost as much or more than
incineration at Sites A and B.
Three of the sites (A, B, and C) used consistent, risk-based
approaches in determining remediation goals that were expressed as
contaminant concentrations in soil. Consistent levels were selected
for remediation, given the exposure assumptions appropriate for
these sites. These three sites all had residents living on or near
the site. A 10"5 lifetime excess cancer risk level was chosen for
the residential use of Site A, because residential use of the site
is unlikely, but residential areas are adjacent. An excess cancer
risk of 10"6 was chosen as the goal for the residential portions of
Site B because residents are living on site and will continue to do
so. The commercial portions of Site B will be cleaned up to 10"5
excess cancer risk level, as will Site C, a currently operating
industrial facility.
At the fourth site (D) , which is an active RCRA facility with no
nearby residents, the cleanup goals were selected based on source
removal to preclude further ground water contamination, as opposed
to direct-contact risks. The ROD for Site D calls for bioassays on
D-39
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OSWER Directive 9835.13
the soil to determine that the soil presents no greater than a
10"6 excess cancer risk. However, there is no established protocol
for using soil bioassays to relate to cancer risks.
V. Treatment versus containment
A treatment remedy, consistent with the expectations in the proposed
NCP, was chosen for all four of these sites. At two Enforcement
sites biotreatment was selected; at the other two Fund-lead sites,
incineration was selected.
Long-and short-term effectiveness, implementability, reduction of
toxicity, mobility, or volume through treatment, and cost were
important criteria in deciding what method of treatment was
appropriate. Both incineration and biotreatment will achieve
significant reduction in toxicity, mobility, or volume of
contamination at the sites.
Time of implementation was a significant factor in the Fund
selecting incineration over biotreatment at Sites A and B. This
decision was influenced by the existence of residents on or adjacent
to both sites and the respective Region's concerns to limit the
residents' short-term exposure. Capping is included as part of the
remedy at all Sites. At Sites A and B, low-level waste (i.e., below
a health-based action level) will be contained in place. At Site
C, all source contamination above the concentration associated with
the 10"5 excess cancer level will be excavated and treated; however,
the residue from biotreatment. will be contained in a lined RCRA
unit. Similarly, at Site D the biotreated material will be capped
after treatment.
Sites A, B, C, and D each considered risk in determining what soil
should be excavated. Industrial versus residential future-use
D-40
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OSWER Directive 9835.13
scenarios caused risk numbers to vary from 10"5 to 10"6. Site D,
although selecting a 10"6 level, did not provide concurrent chemical-
specific cleanup levels.
VI. Involvement of PRPs and other Influences
PRP involvement at the Fund-lead sites was insignificant; however,
community interest was strong due to the existence of residences on
or near these sites. This interest was a strong factor in the
selection of destruction technologies. Biotreatment was found not
to be effective for Site A because of site-specific limitations and
costs equal to or exceeding incineration. Biotreatment was rejected
at Site B due to questionable effectiveness in local soils and the
length of time needed for remediation.
Biotreatment, an innovative technology, was selected in both
Enforcement-lead RODs, based on a full evaluation of the nine
evaluation criteria, consistent with Agency guidance. Given the
same degree of protectiveness as incineration alternatives,
biotreatment was significantly more cost effective, a requirement
of CERCLA, and appears to be an appropriate decision.
The presence of residents on or adjacent to the site influenced
remedy selection and the cleanup goals. Public comments on Sites
A and B affected remedy selection.
At Site D, the analytical method for determining which soils are
associated with a greater than 10"6 cancer risk level and exposure
assumptions for risk assessment, which could affect ultimate cleanup
levels, were influenced by the PRP. Each of these areas should be
re-evaluated.
D-41
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Appendix E
NCP Expectations For Treatment
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51422 Federal Regular / Vol. 53. No. 245 / Wednesday, December 21, 1988 / Proposed Rules
Section 300.430 Remedial
Investigation/Feasibility Study (RI/FS)
and Selection of Remedy.
Today EPA is proposing major
revisions to Subpart E to incorporate the
new requirements of the 1986 CERCLA
reauthohzation amendments into
existing procedures, and to reflect
program management principles EPA
intends to follow in order to promote the
efficiency and effectiveness of the
remedial response process. Chief among
these principles is a bias for action.
The 1988 CERCLA amendments
include a number of requirements
related to the remedial alternatives
development and remedy selection
process. Section 121 of the statute
retains the original CERCLA mandates
to select remedies that an protective of
human health and the environment and
that are cost-effective. In addition.
today's proposed revisions address the
new statutory requirement! for remedial
actions to attain the applicable or
relevant and appropriate requirements
of other Federal and State
environmental laws, the mandate to
utilize permanent solutions and
alternative treatment technologies or
resource recovery technologies to the
maximum extent practicable, and the
preference for remedies that employ
treatment that permanently and
significantly reduces the toxicity,
mobility, or volume of hazardous
substances, pollutants, or contaminants
as their principal element over those
that do not.
The overarching mandate of the
Superfund program is to protect human
health and the environment from the
current and potential threats posed by
uncontrolled hazardous waste sites.
This mandate applies to all remedial
actions and cannot be waived. The
mandate for remedies that protect
human health and the environment can
be fulfilled through a variety of means.
including the destruction, detoxification.
or immobilization of contamjnantf
through the application of treatment
technologies, and by controlling
exposure to contaminants through
engineering controls (such as
containment) and/or institutional
controls which prevent access to
contaminated areas.
The CERCLA amendments emphasize
achieving protection that will endure
over long periods of time by mandating
the use of permanent solutions to the
maximum extent practicable and by
specifying long-term effectiveness
factors that must be assessed under
section 121(b)(l) (A-G). The
amendments also express a clear
preference for achieving this protection
through the use of treatment
technologies as the principal element of
remedies. These provisions reflect the
belief that treatment that destroys or
reduces the hazardous properties of
contaminants (e.g., toxiciry or mobility)
frequently will be required to achieve
solutions that afford a high degree of
permanence. The highest degrees of
permanence are clearly afforded by
remedies that are not heavily reliant on
long-term operation and maintenance
following the completion of an
implemented action.
61 addition to these new mandates,
the amended CERCLA retained the
mandate for selecting remedies that are
cost-effective. Although cost-
effectiveness cannot be used to select a
nonprotective remedy, this mandate
does require EPA to evaluate closely the
costs required to implement and
maintain a remedy and to select
protective remedies whose costs are
proportionate to their overall
effectiveness. This mandate establishes
efficient use of resources as a standard
for Superfund remedial actions and
reflects Congress' intent to maximize the
use of the Fund across a large number of
sites. EPA intends to focus available
resources on selection of protective
remedies that provide reliable, effective
response over the long-term.
This combination of mandates (i.e.,
remedies that provide permanent
solutions to the maximum extent
practicable, the preference for treatment
as a principal element and cost-
effectiveness) creates dynamic tensions
for the Superfund program. In today's
proposal EPA extends some of the
fundamental features of the current NCP
in proposing to resolve these competing
goals through a process that examines
the characteristics of sites and
alternative approaches for remediating
the problems those sites pose. This
process evaluates alternative hazardous
waste management strategies using nine
criteria related to CERCLA's mandates
to determine advantages and
disadvantages of the various remedial
action alternatives. This analysis
identifies site-specific trade-offs
between options, and facilitates the risk
management decision which is the
fundamental nature of remedy selection
decisions at CERCLA sites. In balancing
trade-offs among options and selecting
the protective alternative which seems
to offer the best combination of
attributes in terms of the nine criteria
and is thus most appropriate for a given
site. EPA is exercising the discretion
granted by CERCLA to determine the
maximum extent to which permanent
solutions and treatment or resource
recovery technologies can be
practicably utilized in a cost-effective
manner.
EPA believes that the solutions that
are most appropriate for a given site wii
vary depending on the size, complexity.
and location of the site, the magnitude
of the threats posed, the timing of the
availability of suitable treatment
technologies, and the proximity of
human and environmental receptors.
among other factors. While the CERCLA
amendments strongly encourage the use
of treatment technologies in CERCLA
remedial actions, they allow for
discretion in dealing with site
circumstances and technological,
economic, and implementation
constraints that place practical
limitations on the use of treatment
technologies. Treatment is most likely to
be practicable for wastes that cannot be
reliably controlled in place, such as
liquids, highly mobile materials (e.g..
solvents), and high concentrations of
toxic compounds (e.g., several orders of
magnitude above levels that allow for
unrestricted use and unlimited
exposure). Treatment is less likely to be
practicable where sites have large
volumes of low concentrated material.
or where the waste is very difficult to
handle and treat (e.g.. mixed waste of
widely varying composition). Specific
situations that may limit the use of
treatment could include sites where: (1J
Treatment technologies are not
technically feasible or are not available
within a reasonable timeframe: (2) the
extraordinary size or complexity of a
site makes implementation of treatment
technologies impracticable: (3)
implementation of a treatment-based
remedy would result in greater overall
risk to human health and the
environment due to risks posed to
workers or the surrounding community
during implementation: or (4) severe
effects across environmental media
resulting from implementation would
occur. In addition, there are CERCLA
sites or portions of sites where the
concentrations of the wastes are at low
levels or are substantially immobile, and
where the wastes can be reliably
contained over a long period of time
through the use of engineering controls.
In these situations, treatment may not
always offer a sufficient degree of
increased permanence and long-term
protection to be cost-effective.
CERCLA sites are frequently complex
and involve a number of different
problems. EPA believes that it often will
be the case that the most appropriate
solution for a site will involve a
combination of methods of achieving
protection of human health and the
environment. Most frequently. EPA
expects that treatment of the principal
threats posed by a site, with priority
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Federal Register / Vol. 53. No. 245 / Wednesday, December 21. 1988 / Proposed Rules 51423
placed on treating highly toxic highly
mobile waste, will be combined with
engineering controls (such as
containment) for treatment residuals
and untreated waste.
As appropriate, institutional controls
such as water use and deed restrictions
may supplement engineering controls for
short- and long-term management to
prevent or limit exposure, to hazardous
substances, pollutants, or contaminants.
Institutional controls will be used
routinely to prevent exposures to
releases during the conduct of a
remedial investigation and feasibility
study, during remedial action
implementation, and as a supplement to
engineering controls designed to manage
wastes over time. The use of
institutional controls to restrict use or
access should not however, substitute
for active response measures (e.g.,
treatment and/or containment of source
material, restoration of ground waters to
their beneficial uses) as the sole remedy
unless such active measures an
determined not to be practicable, bated
on the balancing of trade-offs among
alternatives that is conducted during the
selection of remedy. These trade-offs.
based on the nine criteria, are identified
during the analysis of alternatives.
EPA recognizes that the approach
presented in today's proposed rule is not
the only approach possible for resolving
the competing goals and requirements of
Ihe Superfund program. Therefore, later
in this preamble EPA presents four
alternative approaches. Two of those
alternatives are site-specific balancing
approaches that while similar to the one
proposed in today's rule, differ primarily
in terms of how they organize the
evaluation criteria, and how they
incorporate the statutory requirements
to select remedies that are cost-effective
and that use permanent solutions and
treatment technologies to the maximum
extent practicable. The two additional
alternatives presented later represent
different approaches to remedy
selection, based on different views of
the goals and purposes of the Superfund
program. EPA solicits comments on
these four alternative approaches as
well as the approach presented in
today's proposed rule.
A. Program Management Principles
Today's proposal also includes
revisions to the 1985 NCP that are not
mandated by CERCLA. These revisions
reflect principles by which EPA intends
to manage the Superfund remedial
program. These principles stem from
experience gained over the first eight
years of the program. In managing
CERCLA sites. EPA must balance the
goal of definitively characterizing site
risks and analyzing alternative remedial
approaches for addressing those threats
in great detail, and the desire to
implement protective measures quickly.
EPA intends to balance these goals with
a bias for initiating response actions
necessary or appropriate to eliminate,
reduce, or control hazards posed by a
site, as early as possible. EPA will
promote the responsiveness and
efficiency of the Superfund program by
encouraging action prior to or
concurrent with conduct of an RI/FS as
information is sufficient to support
remedy selection. While the bias for
action promotes multiple actions of
limited scale, the program's ultimate
goal continues to be to implement final
remedies at sites.
Early action may be taken at a site via
enforcement or Fund-financed activities
taken under removal or remedial
authorities. In deciding between using
removal and remedial authorities, the
lead agency should consider (i) The
criteria and requirements for taking
removal actions in 1300.415 of today's
proposed rule; (ii) the statutory
limitations on removal actions and the
criteria for waiving those limitations;
(iii) the availability of resources: and the
(ivj urgency of the site problem. Specific
actions that may be taken under
removal authorities include emergency
action, non-time-critical removals, and
expedited response actions. A
discussion of these activities is included
in the i 300.415 preamble section. Early
actions using remedial authorities are
initiated as operable units.
The Superfund program has long
permitted remedial actions to be staged
through multiple operable units.
Operable units an discrete actions that
comprise incremental steps toward the
final remedy. Operable units may be
actions that completely address a
geographical portion of a stte or a
specific site problem (e.g., drums and
tanks, contaminated ground water) or
the entire site. Operable units include
interim actions (e.g.. pumping and
treating of ground water to retard plume
migration) that must be followed by
subsequent actions which fully address
the scope of the problem (e.g.. final
ground water operable unit that defines
the remediation level and restoration
timeframe). Such operable units may be
taken in response to a pressing problem
that will worsen if unaddressed. or
because there is an opportunity to
undertake a limited action that will
achieve significant risk reduction
quickly.
The appropriateness of dividing
remedial actions into operable units is
determined by considering the
interrelationship of site problems and
the need or desire to initiate actions
quickly. To the degree that site problems
an; interrelated (e.g.. contaminated soils
and ground water), it may be most
appropriate to address the problems
together. However, where problems are
reasonably severable. phased responses
implemented through a sequence of
operable units may promote more rapid
risk reduction.
Related to the bias for action is the
principle of streamlining, which EPA
intends to emphasize in managing the
Superfund program as a whole and in
conducting individual remedial action
projects. On a project-specific basis.
recommendations to ensure that the RI/
FS and remedy selection process is
conducted as effectively and efficiently
as possible include:
a. Focusing the remedial analysis to
collect only additional data needed to
develop and evaluate alternatives and
to support design;
b. Focusing the alternative
development and screening step to
identify an appropriate number of
potentially effective and implementable
alternatives to be analyzed in detail.
Typically, a limited number of
alternatives will be evaluated that are
focused to the scope of the response
action planned:
c. Tailoring the level of detail of the
analysis of the nine evaluation criteria
(set below) to the scope and complexity
of the action. The analysis for an
operable unit may well be lees rigorous
than that for a comprehensive remedial
action designed to address all site
problems;
d. Tailoring selection and
documentation of the remedy based on
the limited scop* or complexity of the
site problem and remedy. In particular.
operable units initiating interim
remedies may require less complex
justifications because they are limited
actions that will only require minimum
j
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Appendix F
Treatment Versus Containment
Comparisons
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OSWER Directive 9835.13
Seven site types were evaluated in detail to determine why
containment was selected over treatment. Twenty-six RODs were
reviewed - 14 were for Enforcement-lead sites and 12 were for Fund-
lead sites. The other nine site types were analyzed, but not in
detail, because: treatment was selected for all sites in that site
type (Battery/Lead, Dioxin, Solvents, and Wood Preserving);
containment was expected in that site type (Asbestos,
Radioactive/Mixed Waste, Mining and Municipal Landfill); or, no
comparison of Fund-lead versus Enforcement-lead could be conducted
(Munitions). Described below are the findings as to why
containment was chosen over treatment.
Industrial Landfill Sites
Of the five Enforcement-lead sites where some action was
taken, four RODs (80%) chose containment and one chose treatment.
Of the RODs for the 13 Fund-lead sites where some action was taken,
10 chose treatment and three (23%) chose containment. Both
treatment and containment RODs were reviewed.
The seven sites choosing containment, both Fund- and
Enforcement-lead, were reviewed to determine if there were any
principal threats at the sites that should have been treated, or
if site characteristics or other factors justified the selection
of an exclusively containment alternative.
The results of the review showed the following explanations
for why containment was chosen. Some sites have more than one
reason supporting their decision.
F-l
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OSWER Directive 9835.13
Size (Greater
RI/FS than Acceptable No Hot Cost
Site Lead 100.000 yd3) Risk Levels Spots F>*-*inr
Site IP xx
Site 2 P x x
Site 3 P x x
Site 4 P x x
Site 5 F x x
Site 6 F x x x
Site 7 . F x x
RODs at five of the seven sites (three Enforcement-lead RI/FSs
and two Fund-lead RI/FSs) selected containment due to the
considerable size of the site (greater than 100,000 yd3 of
contaminated material) , and the associated difficulties in
implementation posed by this size. Other factors included risk
levels for source material within an acceptable risk range (three
Enforcement-lead, two Fund-lead), no hot spots identified (two
Enforcement-lead), and Cost factors (three Fund-lead).
Of the RODs for the five sites that noted that the risk levels
were within an acceptable range, one had a soil risk of 5 x 10"6,
one had a worse case dermal exposure risk of 5 x 10"6, and a third
had an on-site air risk of 6.2 x 10"7. A fourth stated that the
risk assessment indicated low exposure, and the fifth stated there
was no current risk.
For the sites listing cost as a decision factor, one chose a
$3 million cap and dike remedy over a $100 million incineration
remedy. Another Fund-lead site which listed cost as an explanation
of its choice of containment considered treatment alternatives, but
only incineration was considered implementable due to the diversity
of waste. The cost associated with incineration at this site was
$214 million with a 30 year implementation period, or $486 million
F-2
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OSWER Directive 9835.13
over 10 years. The containment treatment chosen for this site (cap
and off-site disposal) is projected to cost $28.7 million. The
third site listing cost as a factor selected a soil cover with a
projected cost of $1.6 million. This Fund-lead site considered,
but never projected costs, for treatment remedies.
*
A survey of the RODs selecting treatment for Industrial
Landfills showed that six Fund-lead remedies treated the entire
contaminated volume ranging from 90 to 48,000 yd3. Three Fund-
lead remedies selected partial treatment for the most contaminated
wastes at the site. Each of these three sites treated
approximately 30,000 yd3, out of total volumes ranging from 100,000
to 535,000 yd3. The tenth ROD, signed in 1988, was amended in 1989
to treat the entire waste volume.
The one Enforcement-lead site that selected treatment treated
the entire contaminated volume (180,000 yd3). Judicial review is
presently occurring on this site.
All RODs in this category provided sufficient rational for
selecting containment over treatment.
Metal Sites
The percentage of RODs selecting containment compared to
treatment for Metal sites were similar for Fund-lead and
Enforcement-lead sites: Enforcement-lead, one of four (25%)
selected containment; Fund-lead, one of five (20%) selected
containment. For both leads, most RODs choose treatment. However,
because treatment generally may be expected for metal sites, the
two containment RODs (one Enforcement- and one Fund-lead RI/FS)
were reviewed.
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OSWER Directive 9835.13
Both sites appeared to have unique characteristics that made
treatment technically infeasible. The soils at the Fund-lead site
were mixed with large quantities of debris. This mixture does not
lend itself to solidification, which normally would be expected
treatment at metal contaminated sites.
The remedy at the one Enforcement-lead site was sludge
application and vegetation on the steep slopes (in excess of 20%
grade) around the site, in order to reduce surface water run-off.
In-situ chemical precipitation was ruled out due to expected poor
performance and unreliability. The ROD for the Enforcement-lead
site did not provide sufficient documentation or rationale as to
why containment was selected over treatment.
Metals/Orqanics Sites
For Enforcement-lead sites, the RODs at four of 10 (40%) chose
containment. For the Fund-lead sites, four of 30 (13%) chose
containment. All the Fund-lead and Enforcement-lead sites where
RODs chose containment were reviewed to determine why treatment was
not chosen.
In general, treatment at Metals/Organics sites is complicated
due to the technical uncertainties of treating wastes that are a
mixtures of organic and inorganic contaminants. The decisions to
contain wastes at these eight sites were based upon varying
rationales.
F-4
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OSWER Directive 9835.13
Previous No Significant
RI/FS Removal Contamination Technical
Site Lead Action Low Risk Feasibility
Site 1 P x
Site 2 P x
Site 3 P x
Site 4 F x
Site 5 F x
site 6. F x
Site 7 F x
Site 8 P x
One Fund-lead site eliminated soil washing because there was
questionable effectiveness. At another Fund-lead site, the size
of the site (over one million cubic yards) , the two to three
additional years necessary to conduct treatability testing, and the
unavailability of equipment justified selecting containment rather
than treatment. A third Fund-lead site eliminated treatment due
to low volume and the low risk levels associated with contaminated
soil. The fourth Fund-lead site had already had a major source-
control removal action.
Two Enforcement-lead sites also had already had major source
control actions which limited the extent and level of contamination
remaining. A third Enforcement-lead site had limited health risks,
therefore justifying the use of containment. The baseline risk
levels were not, however, provided in the ROD. At the remaining
Enforcement-lead site, the major contaminant in the soil is lead.
This site had some VOCs above background in soils, and VOCs in
ground water, but the soils had lead levels above health based
levels. Since lead cannot be destroyed, the primary options are
containment or stabilization. These two approaches both reduce
mobility; however, the treatment process (stabilization) results
in significant volume increases. It was decided, therefore, that
F-5
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OSWER Directive 9835.13
the benefits of treatment (the reduction in mobility) are not
expected to offset the volumetric increase in contaminated
material.
Three of the eight RODs (two Fund-lead, one Enforcement-lead)
in the Metals/Organics category that were reviewed did not provide
sufficient documentation or rationale to clearly demonstrate why
containment was selected over treatment.
Organic Sites
For Enforcement-lead sites, three of 10 (30%) chose
containment. For Fund-lead sites, one of five (20%) chose
containment. The four containment RODs (one Fund-lead, and three
Enforcement-lead) were reviewed.
No Significant
RI/FS Technical Contamination
Site Lead Volume Feasibility_ Low Risk
Site IPX X
Site 2 P X X
Site 3 P X
Site 4 F X
One Fund-lead site, and one Enforcement-lead site had
relatively low residual levels of contamination. The Fund-lead
site had a previous source control removal action and baseline
risks are in the 10"5 to 10"6 range, which is in the acceptable risk
range. The Enforcement-lead site had contaminants in the 10"7 to
10"9 range in most site areas and one area with contaminants in the
10"5 to 10"7 range, which is in the acceptable risk range.
F-6
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OSWER Directive 9835.13
The technical infeasibility of treatment was a major reason
why containment was selected at the two other Enforcement-lead
sites. In both cases the large volume of wastes (52,000 yd3) were
considered to be very difficult to reliably treat, because of the
high levels of organics in the soils. Several technologies were
considered including bioremediation, solidification, and
vitrification. Bioremediation was not selected due to the very
high organic concentrations. Likewise, solidification was
determined to be incompatible with wastes at the site.
Vitrification was not selected because of the lack of long term
demonstration and the frequency of electrode burnout. In addition,
treatment equipment for such large waste volumes was not considered
to be available.
Three of the four RODs in the Organics category (All
Enforcement-lead) did not provide sufficient documentation or
rationale as to why containment was selected over treatment.
PCB Sites
Enforcement-lead sites chose treatment 100% of the time (six
sites). For Fund-lead sites, one of fifteen (7%) chose
containment. No lead-related differences were noted for PCB sites
in selecting remedial action. Even though only one ROD selected
containment, treatment is a readily available option for PCB
contaminated sites, so it was decided to analyze this containment
ROD.
*
For the Fund-lead site where containment was selected,
treatment options were considered but rejected for two reasons:
public concerns about incineration and the desire for the future
land use to be residential; treatability study results that showed
F-7
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OSWER Directive 9835.13
that dechlorination was impractical because of the soil's clay
content. In this case, therefore, both public concerns, and
technical infeasibility drove the selection of containment.
The ROD for the site where containment was selected provided
sufficient rationale for selecting containment over treatment.
Pesticide Sites
Enforcement-lead sites chose containment at. one of the two
sites where action was taken (33%). At the Fund-lead sites,
containment was chosen in two of the seven (29%) cases where action
was taken. The three containment RODs were reviewed because
treatment is the expected alternative for pesticide contaminated
sites.
For the one Enforcement-lead site, the decision to contain
wastes was predominantly a function of technical feasibility.
Treatment was ruled out because of difficulties in expeditiously
implementing this remedial alternative and because treatment was
determined to be ineffective in controlling short-term risks. At
this site the quantity of dioxin containing waste (70,000 yd3) to
be treated would require approximately six years of capacity of a
specially permitted unit.
For one of the Fund-lead sites where containment was selected,
the remedy consisted of excavation and off-site disposal in a
permitted RCRA Subtitle C landfill of approximately 4050 yd3 of
wastes. This decision was based primarily on cost effectiveness.
The cost differential was $2.1 million for containment and $7.6
million for on-site incineration. The current risk is estimated
at 7xlO"5. It was determined that either containment or treatment
F-8
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OSWER Directive 9835.13
of soils with contamination at this level would have similar,
effective long-term results, but treatment would have a much higher
cost.
At the other Fund-lead site, the presence of arsenic, in
addition to the expected organics, would have required the use of
an unproven innovative technology train approach which was not
expected to be effective on impermeable soils. Incineration would
remove"the organic contaminants from the soil; however, the most
toxic contaminant, arsenic, would continue to be present in
residual ash/soil following treatment. In addition, the continued
land use of this airport facility necessitates the minimization of
short-term impacts.
The Enforcement-lead ROD in the Pesticides category did not
provide sufficient documentation or rationale to clearly
demonstrate why containment was selected over treatment.
Plating Sites
RODs at Enforcement-lead sites chose containment in one out
of the three (33%) of the cases. Fund-lead sites chose treatment
100% of the time (five sites).
The Enforcement-lead site selected containment over treatment
as the most practical and cost-effective remedy based on the risks
involved, and the protectiveness offered by the selected
alternative. The baseline risks provided by the region were
stated as 10"* .for soils, and protectiveness referred to the
handling of the asbestos containerized waste in the landfill. In
addition, this site contained over 132,000 yd3 of material. The
cost for incineration versus containment was $40.3 versus $6.7
million.
F-9
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