PB97-963126
EPA/541/R-97/070
June 1998
EPA Superfund
Explanation of Significant Difference
for the Record of Decision:
Fields Brook,
(Sediment Operable Unit)
Ashtabula, OH
8/15/1997
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EXPLANATION OF SIGNIFICANT DIFFERENCES
SEDIMENT OPERABLE UNIT
FIELDS BROOK SITE, ASHTABULA OHIO
I. Introduction
The Fields Brook Site ("Site") is located in northeast Ohio, in Ashtabula County, approximately
55 miles east of Cleveland, Ohio. The U.S. Environmental Protection Agency ("U.S. EPA") is
the lead agency for conducting the remedial action at the Site under the authority of the
Comprehensive Environmental Response, Compensation, and Liability Act of 1980, as amended
("CERCLA"), 42 U.S.C. Section 9601, et seq. The Ohio Environmental Protection Agency
("OEPA") served in a support role prior to 1996. Since that time, the OEPA has not been
providing technical support or oversight in an effort to reduce duplicative effort.
The U.S. EPA issued a Record of Decision ("ROD") on September 30, 1986, which outlined the
remedy selection process and the selected clean-up action for the Sediment Operable Unit
("SOU") of the Site. The State of Ohio ("State") concurred with the selected remedy in the
ROD
Over the past several years, U.S. EPA has engaged in discussions with several of the potentially
responsible parties ("PRPs") for the Site. Upon careful review of the documentation submitted by
the PRPs and information from pre-design studies, U.S. EPA has determined that several changes
to the ROD should be made. These changes are protective of human health and the environment
and are made pursuant to Section 117(c) of CERCLA, 42 U.S.C. §9617(c), and Section
300.43 5(c)(2)(I) of the National Contingency Plan ("NCP"). These changes, as described below,
do not fundamentally alter the overall approach intended by the remedy presented in the ROD and
they will be incorporated into the SOU remedial action to be implemented at the Site.
Section 117(c) of CERCLA, 42 U.S.C. 9617(c), and Section 300.435(c)(2)(I) of the NCP allows
the lead agency to determine that a significant change to the selected remedy described in a ROD
is warranted after the ROD is signed. If such action, settlement, or decree differs in any
significant respect from the final plan, U.S. EPA is required to publish an explanation of the
significant differences.
U.S. EPA has determined that five significant differences will be made to the ROD. The
significant differences to the remedy are:
1) Elimination of solidification requirements for excavated sediments which will be landfilled
on-Site;
2) Thermal Treatment of the excavated sediments will be conducted at an off-Site facility vs
an on-Site facility;
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3) Development and presentation of the cleanup goals/standards for the sediment to be
excavated;
4) Reduction of the excavated sediment estimated total volume from 52,000 cubic yards to
14,000 cubic yards, including a reduction of the estimated thermal treatment sediment
volume from 16,000 cubic yards to 3,000 cubic yards; and
5) Elimination of the chemical waste landfill requirement contained in Section 761.75(b)(3)
which specifies a fifty foot distance between the bottom liner and the historical high water
table.
As none of these significant differences are considered to be fundamental changes to the SOU
ROD, U.S. EPA has determined that no public comment period is required. However, U.S. EPA
will hold a meeting to discuss the changes noted herein. The State of Ohio's comments regarding
the significant differences are attached hereto as Appendix 1. U.S. EPA's responses to these
comments are attached as Appendix 2.
This document shall become part of the Administrative Record file, which is available for viewing
at the Ashtabula County District Library, 335 West 44th Street, Ashtabula, Ohio, and at U.S.
EPA's Records Center, 77 West Jackson Blvd., Chicago, Illinois, during normal business hours.
II. Background
A. Site History
Fields Brook drains a six square mile watershed including an industrial area where manufacturing
activities ranging from metal fabrication to chemical production have occurred over the past
50 years. Sediments of the brook are contaminated with polychlorinated biphenyls (PCBs),
chlorinated benzene compounds, chlorinated solvents, hexachlorobutadiene, polyaromatic
hydrocarbons (PAHs), arsenic, chlorinated ethenes (solvents), chromium, arsenic, arid other
organic and inorganic hazardous substances.
The Site was placed on the National Priorities List (NPL) for hazardous waste sites on September
8, 1983, and consists of Fields Brook, its tributaries, and any surrounding areas which contribute,
potentially may contribute, or have contributed to the contamination of the brook and its
tributaries. The Site is a multi-source site and involves multiple media, including soil, sediment,
groundwater and surface water.
The U.S. EPA divided the Site into four areas of concern, three of which have been designated as
"operable units" associated with the Site. The Sediment Operable Unit (SOU) involves the
cleanup of contaminated sediment in Fields Brook and its tributaries, and is the subject of this
ESD. The Source Control Operable Unit (SCOU) involves the location and cleanup of sources of
contamination to Fields Brook to prevent recontamination of Fields Brook and the
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Floodplains/Wetland Area (FWA). The Ashtabala River Area of Concern involves determining
the type and amount of contamination in the Ashtabula River, the effect the Fields Brook and
other contamination sources have had on the river sediments, and any risks to human health and
environment. The FWA Operable Unit involves the cleanup of contaminated soils and sediments
in the FWA which are located within the 100-year floodplain area surrounding Fields Brook and
outside of the channel and sideslope areas of Fields Brook.
The SOU has been divided geographically into distinct but continuous portions. In order to
facilitate locating features and sampling points along Fields Brook and its tributaries, the stream
and system has been divided into segments identified by a unique numbering system involving
stream reaches. The eastern portion of the Fields Brook watershed drains Ashtabula Township
and the western portion drains the eastern portion of the city of Ashtabula. The main channel is
3.9 miles in length and begins at Cook Road, just south of the Penn Central Railroad tracks.
From this point, Fields Brook flows northwest to Middle Road, then west to its confluence with
the Ashtabula River. From Cook Road downstream to State Route 11, Fields Brook flows
through an industrialized area. Downstream of State Route 11 to near its confluence with the
Ashtabula River, Fields Brook flows through undeveloped and residential areas in the City of
Ashtabula. Fields Brook discharges to the Ashtabula River approximately 8,000 feet upstream
from Lake Erie. The City of Ashtabula has a population of about 23,000.
The industrial zone of Ashtabula is concentrated around Fields Brook and is comprised of several
chemical industries and waste disposal sites. Manufacturing has occurred since the early 1940's in
this area. Activities ranging from metal fabrication to production of complex chemical products
occurred on approximately 18 separate industrial properties, and the decades of industrial activity
along Fields Brook and its tributaries resulted in the release of chemical contamination to the
Fields Brook watershed, particularly the sediments of Fields Brook, the FWA soils and sediments,
and the soils surrounding the industries.
Between April 1983 and July 1986, a Remedial Investigation/Feasibility Study (RI/FS) was
conducted for the SOU by the U.S. EPA. U.S. EPA completed the RI Report in March 1985 and
the FS report in July 1986. The RI included a baseline human health risk assessment which
demonstrated human health risks for the Brook sediment. The FS Report described several
alternatives for remedial action of the SOU. The U.S. EPA issued a Record of Decision (ROD)
for the SOU in September 1986 detailing a cleanup remedy that U.S. EPA, with the concurrence
of Ohio Environmental Protection Agency (OEPA), determined to be necessary for the Fields
Brook sediments.
B. Description of the Selected Remedy as Set Forth in the ROD
The response action selected in the 1986 SOU ROD involved excavation and containment of
contaminated sediments within an on-Site landfill, and on-Site thermal treatment of the
significantly contaminated or mobile sediments. Specifically, the ROD included the following
components:
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1) excavation of organically contaminated sediment with a greater than 1x10-6 excess
lifetime cancer risk level, and inorganically contaminated sediment to health based levels
or background levels, whichever is higher;
2) construction of an on-Site RCRA/TSCA landfill with separate cells for solidified
sediments, solidified sediments containing arsenic, and a temporary storage cell for
sediment to be thermally treated;
3) on-Site thermal treatment of both excavated sediments which are above 50 ppm PCB's,
and sediments with high potential for mobility which have a soil/water partition coefficient
(koc) of below 2400. Treated material would be disposed via landfilling in either: a) the
on-Site landfill if analysis of the ash from thermal treatment indicates it requires
management as a hazardous waste; or b) in the on-Site landfill or in an off-Site solid waste
landfill if analysis of the ash from thermal treatment indicates it does not require
management as a hazardous waste. The ROD estimated 16,000 cubic yards of sediment
would be thermally treated;
4) solidification of the remaining quantity of excavated sediment, and disposal via landfilling
in the on-Site landfill. The ROD estimated sediment volume before solidification was
24,000 cubic yards;
5) treatment of wastewaters generated during construction activities in an on-Site treatment
system, with discharge to the Ashtabula Publicly Owned Treatment Works or directly to
Fields Brook;
6) completion of various pre-design studies, including:
a) sediment quantification design investigation to determine the volume of
sediments which will need to be excavated and treated or disposed and to
outline initial cleanup boundaries;
b) thermal treatment design investigation to determine the best means of
thermal treatment of the sediments;
c) facility siting design investigation to determine the best location for the
thermal treatment unit and the landfill,
d) solidification design investigation to determine if solidification is an
acceptable method to reduce organic contaminant mobility;
e) aqueous treatment design investigation to determine the best means for
treating wastewater from the incineration, materials handling, and
excavation efforts;
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7) operation and maintenance of the remedy;
8) completion of a Remedial Investigation/Feasibility Study to address any ongoing sources
of contamination to Fields Brook; and
9) completion of an investigation to address the nature and extent of contamination in the
Ashtabula River.
III. Significant Differences
As a result of discussions with and information provided by the PRPs and information from pre-
design studies, the following significant changes will be made to the remedial action:
1) Elimination of solidification requirements for excavated sediments which will be landfilled
on-Site;
2) Thermal Treatment of the excavated sediments will be conducted at an off-Site facility vs.
an on-Site facility;
3) Refinement of the cleanup goals/standards for the sediment to be excavated;
4) Reduction of the excavated sediment estimated total volume from 52,000 cubic yards to
14,000 cubic yards, including a reduction of the estimated thermal treatment sediment
volume from 16,000 cubic yards to 3,000 cubic yards; and
5) Elimination of the chemical waste landfill requirement of Section 761.75(b)(3) which
specifies a fifty foot distance between the bottom liner and the historical high water table.
The significant changes are discussed in detail below.
1) Elimination of Solidification Requirements:
The ROD required solidification of most of the sediments to be excavated from the brook. The
significant change is to eliminate the need to solidify these excavated sediments before the
sediments are landfilled.
Specifically, the ROD required solidification of sediments "containing relatively immobile or lower
risk organic sediments, including sediments contaminated only with arsenic" (page 18 of the
ROD). As discussed on page 25, the ROD required that "a pilot or small bench scale study be
performed to demonstrate that the mobility of organic contaminants be reduced by means of
solidification". This language contemplated that studies conducted during the design might
indicate that mobility of organic chemicals would not be significantly reduced by solidification.
The ROD further noted, in Attachment A to the ROD, that the purpose of the solidification was
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"to remove free liquids" (Attachment A, page 8Y The need to solidify excavated sediments was
intended to provide assurance that liquid contamination would not be released from the sediments
after they are put into the landfill, and to provide assurance that human health and the
environment would be protected. The ROD chose solidification to meet this intent, and selected a
treatment method which used cement and polymers to bind up chemicals, metals and other
contaminants contained within the sediment into a solid cement-like mass to provide assurance
that liquid contamination would not be released from the sediments into the groundwater.
Pages 2-2 and 2-3, and Tables 2-3A through 2-3D of the 2/95 Solidification Design Investigation
Report (which is included within the 30% design documents) provide the results of several
leachate samples taken from untreated sediment samples taken from several areas of the highest
detected contamination in the Brook. The sediment samples were taken from reaches 2-1, 2-2
and 11-4 of the Brook and are from four locations which are downgradient of the major source
areas of contamination. The sediment in these areas had elevated levels of PCBs, volatile organics
and other contaminants. The leachate samples of the sediments did not contain any levels which
were above hazardous waste levels (i.e., the levels were below the Toxic Characteristic
Leachability Procedure (TCLP) levels established under U.S. EPA's RCRA program under 40
CFR 261.24) and thus did not exhibit the characteristic of toxicity. These studies, which are in
the information repositories, were conducted in part to help determine if solidification is an
acceptable method to reduce organic contaminant mobility. Thus, the sediments are not expected
to release toxic liquids once landfilled regardless of the volume of leachate produced.
Design studies which have been conducted since the issuance of the 1986 ROD indicate that the
excavated sediments are not expected to leach significant levels of contamination after the
sediments are dewatered and placed into the double-lined landfill without solidification. Even if
such releases did occur, there are a series of measures which will detect, stop and treat such
releases in the landfill area before any unacceptable risk to human health and the environmental
occurs.
The dewatering requirements and multiple landfill components discussed below will help assure
that no releases of leachate from the landfill will occur. The sediments will first be dewatered
prior to landfilling, and will meet the requirements of 40 CFR 264.228(a)(2), an ARaR *o be met
(this ARAR requires elimination of free liquids by removal or solidification if necessary). Thus,
no free liquids will remain in the sediments prior to disposal into the landfill unit. Liquids,
therefore, would not likely be released from the sediments once they are dewatered. In addition,
the landfill will include a low permeability cover which includes various layers including a foot of
gravel/clean soil, a 40-mil FML liner keyed in, a 1/4-inch thick geonet liner, 24 inches of topsoil,
and revegetation. These multiple layers will provide a high degree of assurance that future
rainwater will not reach the contained sediments. The landfill will also have a double lined unit
(with two separate layers of a 60-mil FML liner separated by gravel), with a leachate detection
system and leachate collection system to monitor, collect and treat any leachate which might be
generated. Below these layers there will be a bottom clay liner which shall be at least 5 feet above
the historical high ground water table. In addition, long term monitoring, access restrictions, and
institutional controls will provide protection to human health and the environment against
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unreasonable risks of injury. Also, no future development will be allowed on top of the landfill
once it is closed, in order to provide assurance of future integrity of the landfill.
The ROD placed particular emphasis on solidifying arsenic. Design studies, however, indicated
that arsenic is not present in brook sediment at significant levels which create a particular need to
be concerned about its leachability. Furthermore, because arsenic was found during design
studies to be present in the watershed at naturally high levels, a particular emphasis to solidify this
contaminant does not appear to be warranted. The cleanup goal (CUG) for arsenic in the
sediment is lower than the background levels indicated at the Site. While the calculated arsenic
CUGs are 5.8 ppm for residential areas and 13.6 ppm for industrial areas, the background
concentration of arsenic in the Brook is 27 ppm. The high background level is probably due to
naturally high arsenic terminal moraine and glacial deposits which occurs in various locations
throughout Ohio. Because background is higher than the calculated CUG, the CUG has been
revised to the background level of 27 ppm. While the maximum detected concentrations for
arsenic in the Brook sediment to be excavated was 180 ppm, the average arsenic concentration
for sediments to be excavated is below 27 ppm, and none of the leachate samples from
unsolidified sediments had arsenic detections above 5 mg/1, which is the TCLP level that indicates
that the sediment was hazardous and exhibited the characteristic of toxicity.
The cost associated with solidification, as taken from the 1986 SOU ROD, are $1.23 million,
using 1986 dollars present worth These costs have escalated since 1986, and would be saved if
solidification of the SOU excavated sediments was not required.
For the above reasons, and since the intent of the SOU ROD can be met without the need for
solidification, this ESD eliminates the requirement of solidification.
2) Off-Site Thermal Treatment:
The ROD required on-Site thermal treatment of certain highly contaminated sediments. The
significant change is to eliminate the need to thermally treat these excavated sediments on-Site,
and to conduct this activity off-Site.
As noted on page 16, last paragraph of the ROD, construction of a temporary thermal treatment
facility at or near the Site was anticipated. Also, on page 23 under Community Relations, it was
noted that the Ashtabula Township Trustees expressed a willingness to work with U.S. EPA to
identify potential locations for the construction of a thermal treatment facility. However,
Appendix C of the SOU ROD provides an analysis of off-Site vs. on-Site thermal treatment
facilities, and this analysis does not state a preference either for or against either on-Site or off-
Site thermal treatment. During design studies, the PRPs indicated that the estimated sediment
volumes slated for thermal treatment are sufficiently low enough that off-Site thermal treatment of
the sediments would be more cost-effective. Off-Site thermal treatment will achieve all of the
treatment requirements set forth in the ROD, which were later detailed by U.S. EPA to the PRPs
during design, and will occur in a protective manner.
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The specifications for off-Site thermal treatment will be detailed in the 90% remedial design (RD)
document. These treatment and performance requirements for off-Site thermal treatment will be
similar to those requirements already set for on-Site thermal treatment. Thus, the treatment and
performance requirements do not need to be described in detail in this Explanation of Significant
Differences. There is no change in the criteria determining which sediments will be thermally
treated (i.e., sediments contaminated with above 50 ppm PCB's, and those sediments with high
potential for mobility which have a soil/water partition coefficient (koc) of below 2400).
Appendix C of the ROD listed requirements for thermal treatment, and the thermal treatment
design investigation outlined treatment requirements to be met. However, because the thermal
treatment will occur at an off-Site facility, the performance specifications will require that the off-
Site facility be a permitted facility in compliance with environmental-related permits (see 3/8/90
NCP, page 8690-91), and also will meet the requirements of U.S. EPA's 'Off-Site Rule1, 40 CFR
300.440 (9/22/93).
Information submitted by the PRPs regarding off-Site thermal disposal indicate that the current
plan for transporting the excavated materials from the Brook area to the off-Site facility would be
protective of human health and the environment and would not have any unacceptable short-term
risks which would prohibit the off-Site disposal of the materials. The sediments would first be
containerized in watertight roll-on/roll-off boxes at the excavation location and transported by
truck to the pretreatment area prior to off-Site transportation. Before the containers are moved
they will be inspected to ensure that no free liquids would be left in the containers before
movement. The sediments will be dewatered in a pie-treatment facility to be located on-Site, and
all of the liquids produced from the dewatering process on-Site would be collected and treated.
The smaller sediments (i.e., below two inches diameter) will be dewatered and transported via rail
from the Site to the off-Site treatment and disposal facility. In general, thermal treatment does
not efficiently meet performance specifications if large particles of sediment or other material are
present. The larger particles collected from the sediment areas (such as rocks or debris above two
inches diameter) and which are slated for thermal treatment will be decontaminated if possible
using spray wash techniques and transported off-Site via truck to an off-Site solid waste
management unit for disposal. Organic materials such as roots and stumps will be thermally
treated and not deconned Information will be submitted by the PRPs to U.S. EPA prior to off-
Site transportation, treatment and disposal to ensure these activities will be conducted in a
protective manner, including the following: a) volumes of the materials to be shipped; b) the
name, location, and ID number of each facility planned to receive the sediment materials and the
volumes to be disposed at each; c) sampling/analysis procedures to meet off-Site disposal
acceptance; d) the QA/QC and sampling requirements; e) manifesting procedures and regulations
to be followed; and f) assurances that regulations concerning transportation, treatment and
disposal of all materials will be followed.
Various other procedures will be followed to help ensure safe transport. Regulations of the U.S.
EPA, OEPA, and U.S. Department of Transportation will be followed. The transportation
specification will include requirements for engineering controls (e.g., liners, cover, gasketed
tailgates) in trucks or railcars to minimize the potential for releases such as leaks, dusts or spills
during transport. Treated sediments will only be disposed of in a solid waste unit which is in
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compliance with applicable regulations and is able under the regulations to accept such waste
streams for disposal. The long-term effectiveness of the off-Site treatment and disnosal facilities
would be high, because these facilities are separately permitted and regulated by the State and
U.S. EPA for protectiveness and would be in compliance with the applicable regulations
appropriate for disposal.
There are other reasons why on-Site thermal treatment may not be preferable, including potential
for schedule delay, increased costs, and significant public concern (as indicated in part by public
comments expressing concern regarding potential for risks to local citizens, raised at the 5/93
availability sessions and public meeting). EPA's review of information submitted by the PRPs
regarding on-Site vs. off-Site thermal treatment costs also indicate that there would be a cost
advantage of off-Site over on-Site thermal treatment. The off-Site treatment option is estimated
to cost approximately 70% of the on-Site thermal treatment option, according to the PRPs
1/10/96 "Analysis of Off-Site Treatment and Disposal Option" report which are in the information
repositories.
For the above reasons, and since the intent of the SOU ROD can be met without the need for on-
Site thermal treatment, this ESD eliminates on-Site thermal treatment.
3) Refinement to Sediment Cleanup Goals/Standards:
The ROD did not list the Cleanup Goals ("CUGs") which represent the maximum average
concentration of contaminants that can be left within an exposure unit in the Fields Brook
Sediment. Using statistics, these CUGs are translated into Confidence Removal Goals (CRGs)
which will identify concentration cut lines for excavation in order to be able to meet a CUG for an
exposure unit. Rather, the ROD provided a risk-based goal which the sediment remedy was to
achieve. This Explanation of Significant Differences explains how that risk-based goal is being
met and defines all of the SOU CUGs.
The CUGs identify the final average concentrations of contaminants within the Brook sediment.
The CRGs define the contaminant concentration levels above which sediment must be removed
and/or addressed as part of the SOU cleanup. The SOU ROD noted on page 18 that excavation
of all contaminated sediment to the "defined" 10"* excess lifetime cancer risk levels was required,
and that for inorganic contaminants, the health-based guidelines be used to define the level of
sediment removal. Also, the ROD noted that if any of these levels were below background levels,
then the background level would be used to define the cleanup goal. The ROD did not define or
list these CUGs explicitly. The 1986 Feasibility Study (FS), Appendix B, did, however, calculate
and list CUGs. During the design process of the SOU remedy the CUGs were defined in a
manner consistent with the risk level goals noted above, and these CUGs were consistent with the
procedures outlined in the NCP and U.S. EPA guidance and policy to ensure protectiveness.
Several U.S. EPA's guidances were used to define the CUGs including the following: 1989 Risk
Assessment Guidance Parts A and B; 1992 Data Useability Guidance for Superfund Risk
Assessments: 1989 Exposure Factors Handbook: 1992 Dermal Exposure Assessment Guidance:
and 1992 Guidelines for Exposure Assessment. Also, OEPA's 1991 How Clean is Clean was
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used to develop the CUGs.
The CUGs were developed by U.S. EPA after discussions with the Fields Brook PRP group, in
coordination with the OEPA. Many of the discussions and issues are documented in letters and
reports which are included in the Site's Administrative Record. The OEPA does not agree with
the CUGs due to differences of opinion over appropriate exposure frequencies. However, various
U.S. EPA health risk experts within U.S. EPA's Region 5 (Chicago IL), Office of Research and
Development (Cincinnati OH), and Headquarters (Washington DC) offices have reviewed the
CUGs, the CRG method, and their application for this Site, and they agree that these CUGs,
coupled with how they will be addressed within cleanup activities for this Site, will result in a
protective remedy for human health and the environment.
The CUGs were calculated to assure protection of human health from noncarcinogenic and
carcinogenic effects. Four major components were used to develop the CUGs: 1) identification of
chemicals of potential concern; 2) exposure assessment; 3) toxicity assessment; and 4) risk
characterization, as described below.
A) Identification of chemicals of potential concern:
U.S. EPA selected the chemicals of concern (COCs) for establishment of CUGs. The COCs are
chemicals present in Brook sediments which might be of potential concern to public health. The
1986 FS identified approximately 49 COCs which were quantitatively assessed as part of the 1984
exposure assessment (as noted in Table 2-1 of the 1986 FS). The design investigations identified
approximately 67 COCs for which CUGs were established, and of these 67 COCs the primary
COCs which drive cleanup in the SOU and which are also noted in Table 2-1 of the FS are:
1,1,2,2-tetrachloroethane, tetrachloroethene, trichloroethene, vinyl chloride, benzo(a)pyrene,
hexachlorobenezene, hexachlorobutadiene, hexachloroethane, PCBs, arsenic, and beryllium. A
list of all of the COCs and of the CUGs is indicated in the CUG list provided within the "Sediment
Quantification Design Investigation" report which was submitted as part of the 30% design
document for the SOU, and is also provided in Appendix 3 of this Explanation of Significant
Differences.
Radionuclides were investigated separately within the Brook sediments. The maximum
concentrations of radionuclides measured at any location in the Brook were the Nuclear
Regulatory Commission and U.S. EPA standards/levels of 30 Picocuries per gram. It is therefore
unlikely that uranium contamination is contributing to the risk at Fields Brook and thus uranium is
not considered a chemical of concern at the Site. U.S. EPA's 1/31/94 letter indicates the
Radionuclide Contamination CUGs and factors which went into the development of these
radionuclide CUGs; these radionuclide CUGs are also attached to this Explanation of Significant
Differences (Appendix 3).
B) Exposure assessment
The exposure assessment identified potential pathways by which exposures can occur and
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characterizes various factors including the potentially exposed populations and the type,
frequency and duration of these exposures Regarding the selection of the routes by which
contaminants may enter the body, the only exposure route ultimately considered in the
development of CUGs during the design of the SOU remedy was ingestion of sediments during
direct contact with Fields Brook. Screening risk calculations showed that the other possible
exposure routes which were considered in the FS (e.g., dermal absorption and inhalation) were
insignificant when compared to the ingestion exposure route. Ingestion would occur
inadvertently from hand to mouth activity by persons having soils or sediments on their hands due
to contact with the Brook sediments. Inhalation was eliminated because volatilization and
paniculate emissions from Brook sediments which may mostly be wet will not be significant.
Dermal absorption risk was also relatively small compared to direct ingestion risk. Thus, U.S
EPA determined that CUGs based on the sediment ingestion exposure route will also assure
protectiveness from the other exposure routes associated with the Brook sediment.
The 1986 FS assumed residential use exposure frequency estimates of 243 days per year for 70
years, which were refined to the following exposure frequencies: 20 days per year for the
residential child (ages 5-6), 60 days/year for adolescents, and 20 days per year for adults, for a
total of 26 years. Also, the 1986 FS assumed that industrial exposures occurred at an exposure
frequency of 243 days per year for 40 years, which were refined to 60 days per year for 25 years
during the design process. Further, the sediment ingestion rates assumed in the calculation were
changed. The 1986 FS estimated that residential ingestion rates were 1 granVday for three years,
10 grams/day for two years, and 0.1 grams per day for 66 years, which were refined to 0.2
grams/day for two years, 0.1 grams per day for 9 years, and 0.05 grams per day for 15 years.
Also, the 1986 FS assumed that industrial ingestion rates were 0.1 grams/day for 40 years, which
were refined to 0.05 grams/day for 25 years.
The reassessment of exposure considered a number of factors, including the types/ages of people
exposed, the frequency, and the exposure routes. The Brook was divided into two major
segments, based on demographics and land use: a residential segment, west of State Road, and an
occupational segment east of State Road. Different types of and frequencies of exposures were
assumed to be different in residential versus occupational areas; higher exposures, leading to
lower CUGs, occurred in the residential segment. U.S. EPA considered a variety of factors when
assessing exposure, including a survey conducted by the Fields Brook PRPs of residents and
workers within the area, discussions with local residents on evidence of exposure along the
Brook, best professional judgement of future unrestricted residential exposures to sediments, and
a balance of various other factors including expected future land use.
The areal size of the Fields Brook sediment exposure units (SEUs) was a source of uncertainty in
the applications of the CUGs. Considerable discussions occurred between the State of Ohio, U.S.
EPA and the PRPs regarding what is the appropriate size of the Fields Brook SEUs. These
discussions considered what would be the appropriate length of the SEUs which adequately
represents the geographic area to which a given individual would be exposed. Upon
consideration of this information, U.S. EPA judged that it would be acceptable to divide the
Fields Brook sediment areas into ten separate SEUs, each of approximately 2000 feet in length
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along the Brook, which represent the geographic area to which a given individual would be
exposed. U.S. EPA has reviewed these lengths and concluded that if after cleanup activities
occurred contamination levels were on average at or below the Cleanup Goals for each SEU, the
remedy would be protective of human health and the environment. The development of the SEUs
followed U.S. EPA guidance for their development (i.e., U.S. EPA's 1989 Risk Assessment
Guidance (RAGs), pages 3-3, 6-4, 6-19, and 6-30) and considered a variety of factors which are
considered such as differences in land use, terrain, accessibility or medium type which can affect
exposure, and homogeneousness regarding contamination. The use of the SEU concept for
cleanup of the Brook sediment is also consistent with U.S. EPA's 1992 "Calculating the
Concentration Term" Supplemental Guidance to RAGs. The SEUs associated with each
designated land use and reach of the Brook are as follows:
• Residential:
SEU1 Reach 1
SEU2 Reach 2-1,2-2, and part of 9
SEU3 Reach 3
SEU4 Reach 4
SEUS Reach 11-1 and 11-2
SEU6 Reach 5-1 and 5-2
• Industrial:
SEU7 Reach 11-3 and 11-4
SEUS Reach 6 and 7-1
SEU9 Reach 7-2 and 8-1
SEU 10 Reach 8-2, 8-3, 8A, 13-1, 13-2, and 13A
U.S. EPA designated, for risk purposes, residential use cleanup goals for all sediment areas west
of State Road and industrial use for all sediment areas east of State Road. SEUs 7-10 are thus
considered to have industrial use. U.S. EPA considers this to be protective since there is a buffer
zone of approximately 4000* of brook between the areas where contamination was released from
the industries and the residences. The area between State Road and Route 11 is considered a
"mixing zone" between the industry and residence CUGs, and while no residences exist there, the
area will be remediated to residential development levels.
Various U.S. EPA staff who are responsible for reviewing and developing risk documents and
making risk management decisions were consulted, and these staff agreed that the selected
exposures and considerations used to calculate the residential and occupational CUGs were
acceptable. This included the assumption that no exposures under age five reasonably occurred
because parents would restrict access of small children to flowing bodies of water. These U.S.
EPA staff agreed that the overall proposed integrated approach was acceptable and consistent
with U.S. EPA risk assessment guidance and practice, and that the assumptions which were based
on survey information, use of safety factors, comparison to other Superfund sites, consultation
with U.S. EPA experts, and U.S. EPA's best professional judgment represented the RME
("reasonable maximum exposure").
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13
C) Toxicity assessment:
The toxicity assessment identified the type of hazards or health effects associated with the
exposure to the chemicals of potential concern; it also described the dose-response relationships
of those chemicals.
Changes to the 1986 FS reference dose (RfD) values occurred during the design process for the
calculation of non-cancer risk CUGs for naphthalene, 1,2,4-trichlorobenzene, and zinc; the most
current RiD values were used. Also, RfD values derived from dietary studies were used to refine
the CUGs for cadmium, manganese and selenium.
Several cancer risk slope factors (CSF) were updated when changing the CUGs. CSFs for the
various polyaromatic hydrocarbons (PAH's) such as benzo(a)pyrene, benzo(a)fluoranthene and
others were changed. The method used to develop the ROD's PAH CUGS involved use of the
benzo(a)pyrene (BaP) CSF as the default to determine the risks of all PAH's. During design, U.S.
EPA used the toxicity equivalency factors (TEF) approach for assessing PAH risks. The TEF
approach used the CSF of each separate PAH as the CSF rather than the BaP CSF to determine
the risks for each PAH, which resulted in different CUGs for each PAH. This is the currently
accepted procedure within U.S. EPA to assess PAH risks.
PCBs encompass a class of chlorinated compounds which includes up to 209 variations, or
congeners, with different physical and chemical characteristics. Specific combinations of PCB
congeners are generally unique to each site. PCB congeners are grouped into categories of PCBs
which are known as Aroclors. Certain Aroclors are commonly associated with insulation systems,
others used in hydraulic, lubricating and heat transfer fluids, and still others as dielectric fluids in
transformers. These three types of Aroclors were used within the Fields Brook site. It was
agreed upon by both U.S. EPA and the PRPs during meetings in 1994 and 1995 to consider all of
the Aroclor's and congeners together as-total PCBs in the CUG calculation.
It should be noted that the PCB CSF was recently revised to 2.0 (mg/kg-day)"1 which was entered
onto the Integrated Risk Information System (IRIS) October 1, 1996. The recently revised and
current CSF of 2.0 results in PCB cancer risk CUGs of 5.0 ppm on average in residential areas
and 11.9 ppm on average in industrial areas. The former CSF of 7.7 results in PCB cancer risk
CUGs of 1.3 ppm on average in residential areas and 3.1 ppm on average in industrial areas.
Upon consideration of the various issues associated with PCB risks at the Fields Brook site, U.S.
EPA has set the total PCB CUGs for the SOU as follows: 1.3 ppm on average in residential areas,
and 3.1 ppm on average in industrial areas. These SOU PCB CUGs are slightly lower in
concentration than CUGs based solely on the recently revised CSF. These SOU PCB CUGs are
based on U.S. EPA's risk management decision to be protective of ecological receptors at the
site, and to attempt to be protective and account for the uncertainties regarding the endocrine
disrupter health effects. Also, this decision reflects U.S. EPA's attempt to account for the
potential synergistic effects of the multiple contaminants in the SOU which may increase health
risks associated with the predominant chemical of concern in the SOU, which is/are PCBs.
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14
Regarding the need to be protective of ecological receptors at the site in developing the SOU
PCB CUGs, a 2/97 "Focused Ecological Risk Assessment" of the brook sediment was recently
prepared by U.S. EPA to estimate post-remediation risk levels to ecological receptors such as
mink which are or may be exposed to the Brook; this report is in the Site's Administrative
Record. This focused assessment indicated the potential for significant risks to ecological
populations associated with exposure to PCBs. The assessment notes that post-remediation
average concentration chronic hazard quotient (HQ) calculations using the above noted PCB
CUGs indicated that there may be several species with HQ exceedences of 1. HQs above 1 may
indicate a risk of adverse effects to species. However, U.S. EPA believes that a SOU remedy
which meets the above noted PCB CUGS would protect the various populations of ecological
receptors which exist or may exist within the Brook or rely upon food sources associated with the
Brook. The response actions would reduce the short- and long-term risks to ecological
populations and reduce these population's potential uptake of contamination via soil and food to
acceptable levels of exposure. It should also be noted that the HQ calculations were developed
using conservative assumptions based on "no observable adverse effect levels" to ecological
receptors, which would help provide for protectiveness to ecological receptors. The Ohio EPA,
as a natural resource trustee, is concerned that the SOU remedy may not be protective of
ecological receptors and intends to conduct, post remediation biomonitoring to assess the extent
to which injuries to the natural resources continue to occur.
Regarding the need to attempt to be protective and account for the uncertainties regarding the
endocrine disrupter health effects in developing the SOU PCB CUGs, it should be noted that
although the PCB cancer risk slope factor changed from 7.7 to 2, at this time there is no
agreed-upon quantitative method within U.S. EPA to incorporate the endocrine disruption data
into a toxicity value. There is reason to believe that the endocrine disrupter effect may be the
most sensitive health effect of PCB exposure. Also, U.S. EPA's general practice is to err on the
side of caution regarding use of uncertain data; the endocrine disruption uncertainties provide
justification for the use of a conservative PCB cleanup goal calculation. As endocrine disrupters,
PCBs have the potential to negatively impact the developing fetus, increase vulnerability to certain
cancers, and possibly decrease fertility. While an RFD has not been calculated based on these
endpoints, the current evidence suggests that PCBs have the potential to disrupt the endocrine
system.
D) Risk characterization:
The risk characterization integrated the information developed during the toxicity and exposure
assessments to estimate the potential risks to public health from exposure to Site contaminants.
These risk estimates were then used to calculate the CUGs. To recalculate the CUGs, the risk
characterization effort integrated the above-noted changes to the COCs which were identified, the
exposure assessment default parameters, and toxicity assessment considerations with other risk-
related assumptions which did not change from the assumptions made in the ROD. The ROD
also noted that cleanup to a 10"6 risk level for carcinogens was required, and the recent
recalculation of the CUGs was based on a IxlO"6 risk. This clarification is made to make clear
what specific risk level was used. The specific risk level determination was made based on Site-
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15
specific factors, including that there are multiple contaminants ofconcefn involving multiple
media associated with exposure to Brook sediments.
A list of all of the SOU CUGs is provided in Appendix 3 of this Explanation of Significant
Differences.
For the above reasons, this Explanation of Significant Differences explains how the SOU ROD's
risk-based goals were met and defines all of the SOU CUGs.
4) Reduction in ROD Estimated Excavation Volumes;
The ROD estimated that 52,000 cubic yards would be excavated from the Brook. Design studies
indicate that approximately 14,000 cubic yards need to be excavated.
The SOU ROD's "Recommended Alternative" section indicates that sediment was required to be
excavated to the cancer risk and health based levels discussed in the above section. The ROD
does note on page 18 that 36,000 cubic yards of sediment were estimated to be contaminated with
arsenic, relatively immobile or lower risk organic contaminants, and that 16,000 cubic yards of
sediment was estimated to be designated for thermal treatment. The ROD did not explicitly state
that all sediment in the Brook be removed or that sediment from each excavation location should
be excavated to the soil/sediment or bedrock/sediment interface. The ROD, on page 18, second
bullet, referenced Appendix M of the 1986 SOU FS for a complete breakdown of remedial
components including a sediment excavation volume of approximately 38,700 total yards.
However, this FS estimate is inconsistent with the total ROD estimated volume discussed above
(52,000 cubic yards: the sum of the 36,000 and 16,000 cubic yard volumes noted above) and is
also inconsistent with the estimated sediment excavation volume of 43,500 cubic yards in
Appendix H of the FS. The ROD notes on page 24 that sediment quantification design studies
were necessary to determine the overall sediment quantities to be excavated as well as determine
which sediments would be thermally treated vs. landfilled. Also, the ROD notes in this section
that the size of the remedial facilities would be adjusted during design in the event that sediment
quantities changed significantly. Appendix M also indicates, in Table M-4, that 24,000 linear feet
of the Brook was anticipated to be excavated The FS also estimated a sediment excavation depth
of 30 inches for all remedial alternatives including the selected remedy, and noted that additional
sampling and testing during design and implementation would better define the extent (horizontal
and vertical) of sediment removal (as discussed on page 5-23 of the 1986 SOU FS).
The sediment quantification studies, which are part of the February 1995 30% design documents,
indicate that sediment quantification sampling, scour analyses, and statistical application of the
CUGs efforts conducted during design of the Brook ROD have reduced the total sediment
excavation volume from the ROD-estimated 52,000 cubic yards to approximately 14,000 cubic
yards, and have reduced the ROD-estimated 16,000 cubic yards volume of sediments to be
thermally treated to approximately 3,000 cubic yards. Also, the 24,000 linear feet of the Brook
anticipated to be excavated has been reduced from the ROD-estimated 24,000 linear feet to the
current estimate of 8,305 linear feet, as noted in the October 1995 60% design report's
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16
excavation plan and profile sheets. Also, the excavation depths were changed from the 30 inches
total depth assumed in the ROD to excavation depths varying between twelve inches to forty-two
inches, depending on scour depth in that sediment location as determined through the hydrologic
and scour analyses which were conducted and reported in August 1994. It is also possible that
these estimated sediment excavation volumes, lengths and depths may further change based on
data from the delineation sampling that was conducted in the spring of 1997. The results
of this sampling effort are currently being reviewed. It is not expected that the results will
significantly change the estimated sediment excavation volumes, lengths and depths.
The sediment quantification sampling, scour analyses, and statistical application of the CUGs
efforts conducted during design of the Brook ROD are further discussed below.
A) Sediment Quantification Sampling Summary
A total of approximately 70 Phase I Sediment Quantification Design Investigation (SQDI)
sediment sample locations were sampled along the Brook, followed by approximately 140 Phase
II SQDI additional sample locations, with samples spread relatively evenly across each SEU
ranging from approximately 100-250 feet spacings. During the Phase II Study, a sufficient
number of sampling locations were located within each SEU to represent a statistically valid
number of samples. The sampling locations involved taking a surface sediment sample at each
location along the upper one foot of the sediment; also, if sediment extended to three foot or
more in depth, an additional sample was frequently taken between the two and three foot thick
depth
The Phase I SQDI samples were analyzed for approximately 130 different chemicals (i.e., the
TCL and TAL parameters). The Phase II samples were analyzed for the eleven COCs discussed
previously which exceeded CUGs in the Phase I SQDI samples. The COC concentrations vary
from background and nondetect levels to several hundred parts per million (ppm or mg/kg). No
CUG compounds were exceeded in background except for arsenic. As indicated in the 30% and
60% design reports, the data indicated that there were no exceedences in the sediment above the
CUGs in SEUs 9 and 10 from the Phase I and II SQDI sampling results, and therefore these SEUs
were eliminated from further consideration for remedial work. The data also indicated a number
of lengths of the Brook sediment in the other SEUs where there were no CUG exceedences. As
discussed previously, additional delineation sampling will be conducted in the brook sediment
during the spring of 1997. However, it is not expected that this sampling will significantly
change the estimated sediment excavation volumes, lengths and depths.
B) Scour Analysis:
The PRPs conducted a 1994 scour analysis to determine the depth at which hydraulic scour could
occur from a 100-year storm into or below the Brook sediment. The following methodology was
used by the PRPs at U.S. EPA direction to calculate scour depth from a 100-year storm event in a
uniform reach with a consolidated cohesive bed and negligible bed material:
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17
1) Develop an erosion rate vs. shear stress curve for the stream bed.
2) Develop a shear stress vs. discharge rating curve.
3) Using the flow duration curve and/or the 100 year hydrograph, develop a shear
stress "hydrograph"
4) Integrate the 100-year "shear stress hydrograph" and/or the "shear stress duration
curve" with the erosion rate vs. shear stress rating curve, to obtain scour depth.
The methodology first calculated the average sediment scour depth using engineering properties
for the calculation, and integrating the flood event down to the depth of the sediment. Where the
sediment was scoured to soil depth, the integration was continued on the soil below the sediment,
calculating scour using the different erosion properties of the soil for the calculation, to determine
the depth of total scour/erodibility for that location. These efforts included developing computer
models (e.g., HEC-1 and HEC-2 flow model analysis) approved by U.S. EPA and the U.S. Army
Corps of Engineers, and used data collected from the field including actual cross
sections/surveying information (approximately 18 sections were taken in the field), and physical
data of the sediment and soil including Atterberg Limits, grain size analysis, and moisture content.
The scour analyses indicated that depth of maximum scour in particular locations would be
between one and 3.5 feet of total sediment depth. There are several areas where the sediment was
calculated to scour to bedrock depth; in these locations the maximum excavation depth is the
depth of bedrock. The depth of excavation will be limited to depth of scour and not the depth of
sediment. In certain areas sediment below a one foot or two foot depth will be left after
remediation based on scour analysis.
U.S. EPA has determined that it is acceptable to leave contaminated materials below the
calculated scour depth in the Brook sediment and install erosion-protection materials in
excavation areas, because these materials would not scour nor be exposed to present a danger to
human health or the environment in the future, even if a worst-case event, such as the largest
rainstorm which would occur every 100 years, occurs. Also, regarding the potential for
recontamination of Brook sediments from the underlying sediments, there is no significant
potential that recharging groundwater might mobilize contamination from these deeper contained-
in-place sediments and rerontaminate cleaner sediment. U.S. EPA's risk assessment guidance and
policies do not require cleanup of areas which are not or would not become exposed to human
health or the environment.
To ensure protectiveness, erosion-resistant materials will be installed in all sediment excavation
areas during the construction of the remedy, to assure that these areas will not be released in the
future. In addition, erosion-resistant materials will be installed in all potentially scourable areas
from areas where excavation is planned in the Brook downstream regardless of excavation
location. The PRPs also propose to install geotextile liners on top of sediment areas to receive
erosion protection; this proposal will be considered acceptable if information regarding chemical
compatibility, durability and long-term effectiveness is provided as part of this proposal. U.S.
EPA will review this information when it is submitted within the 90% design document. Also,
operation and maintenance inspections will help ensure that all areas of the Brook which had
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18
excavation activity and erosion protection installation remain protective. In addition, post-
remediation monitoring will be conducted and include sampling of sediment within the Brook to
evaluate Site conditions following clean-up. The post-remediation chemicals to be monitored will
focus on the eleven primary chemicals of concern noted above, and primarily on PCBs and HCB.
The eleven primary COCs will be analyzed yearly for at least five years after cleanup, and these
contaminants are the key indicators regarding whether the SOU remedy remains protective and
whether chemical concentrations are increasing or not in the Brook sediment after cleanup.
Regarding duration of sampling, U.S. EPA's current recommendation is for post-remediation
monitoring to extend for a period of 5 years. At the end of the 5 year period, a re-evaluation will
be made as to the appropriateness of extending the monitoring time period. Post-remediation
monitoring will not necessarily terminate after 5 years.
For the above reasons, this ESD changes the sediment volumes to be excavated.
S) Elimination of the chemical waste landfill requirement contained in Section 761.75(b)(3) which
specifies a fifty foot distance between the bottom liner and the historical high water table:
As part of the Record of Decision for the Floodplains/Wetlands Operable Unit (signed on June
30, 1997), U.S. EPA Region V waived the requirement of Section 761.75(b)(c) which specifies a
fifty-foot distance between the bottom liner and the historical high water table. This waiver was
proper in this case because the final remedial action v/ill provide protection to human health and
the environment against unreasonable risks of injury. No significant reduction in the long-term
risks would be gained from the off-site disposal of the PCBs contained within the sediments and
soils to be excavated, and the costs for the analyses to detect the extent of PCBs and for off-site
disposal of the PCBs are potentially large. The consolidation unit to be built will provide for
adequate protection of the underlying groundwater resource, in part because the landfill to be
constructed will include a low permeability site cover, double lined unit, leachate collection
system, leachate detection system, a bottom clay liner which shall be at least 5 feet above the
historical high ground water table, long term monitoring, access restrictions, and institutional
controls.
This Explanation of Significant Differences documents the waiver of the TSCA landfill
requirement discussed above for the construction of the on-site landfill to be built to house
excavated material from the Sediment, Floodplain/Wetland and Source Control Operable Units.
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19
IV. Conclusion
U.S. EPA has reviewed the new information that has been developed and has considered the
changes that have been made to the selected remedy Based upon this review, U.S. EPA has
determined that the selected remedy, with the changes described above, will remain protective of
human health and the environment, will comply with federal and State requirements that are
applicable or relevant and appropriate to this remedial action, and will be cost-effective. In
addition, the revised remedy utilizes permanent solutions and alternative treatment technologies to
the maximum extent practicable for this Site Upon careful scrutiny of the suggested changes and
the information submitted to support such changes, U.S. EPA, therefore, has changed the remedy
set out in the ROD in the manner described above.
William E. Muno 7 Date
Director, Superfund Division
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Appendices
Appendix 1: State Comments
Appendix 2: U.S. EPA Response to State Comments
Appendix 3: List of Cleanup Goals (CUGs)
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APPENDIX 1
COMMENTS
FROM
THE STATE OF OHIO
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OhfeBft
SUte of Ohio Environmental Protection Agency
ACORESS: MAJUMC ADDRESS
1800 WaterMark Drive TELE: (SMI 644-3020 FAX: (suj 6*4-2329 P.O. Box 1049
Columbus. Oh 43215-1099 Columbus, OH 43216-1049
June 10, 1997 RE Fields Brook
Sediment Operable Unit
Ohio EPA ID# 204-0300
Ashtabula County p r*r £ | \f *z
Valdas V Adamkus
Regional LMre^or
USEPA Region V JUN i > "'"
77 West Jackson Blvd.
Chicago. 0. 60604
Dear Mr. Adamkus:
This letter is in regard to the Explanation of Significant Differences (ESD) issued for the Fields
Brook Superfund Site, Sediment Operable Unit (SO J) in Ashtabula, Ohio. As you know, Ohio
EPA has made an effort to reduce duplicative efforts by state and federal agencies on certain
Superfund Sites in Ohio. As such, we have not been providing technical support and oversight
assistance to USEPA for the Fields Brook Site for the past year. The State of Ohio did,
however, concur with the original 1986 Record of Decision for the SOU and accordingly we
welcome the opportunity to provide comments on the ESD. Our specific comments are detailed
below.
State of Ohio f^ommeiif.s on the Explanation of Significant Differences for the Sediment
Operable Unit of the Fields Brook Superfund Site, Ashtabula, Ohio
1. Paragraph 1 on page 1. Ohio EPA is no longer acting as a support agency for this
project. .
2. Page 6 under Section III, Significant Differences The 1986 ROD specifies construction
of a RCRA/TSCA landfill with separate cells for solidified sediments. It is not our .
present understanding that USEPA or the FBAG intends to construct a RCRA/TSCA
landfill. Off-Site disposal was considered likely for the last few years because the
volume estimates dropped from 52,000 cu. yd. to 14,000 cu.yd. due to changes in the
Cleanup Goals ( CUGs), statistical application of the CUGs by averaging over, the
exposure units and by limiting the depth of excavation in most areas to 2 feet. Recently
the On-Site option was reconsidered for disposal of the brook sediments and the
sediment/soil from the Floodplain/Wetland Area. This facility would not be a
Prirtaa on ftacycfed Pape<
George V. Voinovich. Governor
Nancy P. Hollister. U Governor
Donald R. Scniegardus, Director
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Valdas V. Adamkus
Page - 2 -
RCRA/TSCA landfill but rather a modified design in terms of bottom liner and cap
requirements. There is no mention of this modified landfill design in this ESD If the
proposed facility is to be anything less than a RCRA/TSCA landfill that meets ARARs
the differences should be included in this ESD.
3. Page 12, item 3. The first paragraph under item 3 states that CUGs would be the
concentrations of contaminants in the sediments which must be excavated. This is
usually true but USEPA is allowing the use of the confidence removal goal (CRG)
approach in this case. The CRG method is a statistical approach to arriving at the CUG
on average over a given exposure unit. The sediment concentration that determines
where sediment is removed is the CRG, not the CUG. The CUG will be the post
excavation surface weighted average concentration. The CRG will be different for each
exposure unit and will always be higher (in this case up to 7 times higher) than the CUG.
This is a significant departure from using the CUG to determine where cut lines are
drawn (as USEPA originally intended to do) and is a major reason for the reduction in
sediment volume from 52,000 to 14,000 cu. yd.
4. Page 13, second paragraph. USEPA states that the CUGs were developed in
coordination with Ohio EPA after discussions with FBAG. It should be noted that Ohio
EPA does not agree with the CUGs finally agreed upon between USEPA and FBAG due
to differences of opinion over appropriate exposure frequencies.
5. Page 18 last paragraph and page 19, first paragraph. It states that a Focused Ecological
Risk Assessment was done regarding the need to be protective of ecological receptors at
the Site in developing the SOU PCB CUGs. It further states that USEPA believes that a
remedy which meets the PCB CUGs would protect the various populations of ecological
receptors which may exist within die Brook. The ecological risk assessment was not
considered in developing the SOU CUGs; this document was produced after the CUGs
were negotiated and, in fact, concludes that there are post remediation Hazard Quotients
in exceedance of 1 for several species. In addition, a full biological sampling and
assessment of the SOU was never done. The State of Ohio, as a natural resource trustee,
is concerned that the SOU remedy may not be protective of ecological receptors and
intends to conduct post remediation biomonitoring to assess the extent to which injuries
to the natural resources continue to occur.
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Valdas V. Adamkus
Page - 3 -
Please feel free to contact Ohio EPA should you have any questions or concerns about this letter.
Sjaeecejy
Ohio Environmental Protection Agency
DRS/RSW.wmk
cc: Jenny Tiell, Deputy Director, CO
Jan Carlson, DERR, CO
Mike Czeczele, DERR, CO
Ray Beaumier, DERR, CO
Bill Skowronski, District Chief, NEDO
Bob Wysenski, Assistant District Chief, NEDO
Rod Beals, DERR, NEDO
Steve Love, DERR, NEDO
Sig Williams. DERR, NEDO
Heidi Sorin, DERR, CO
JeffHurdley, Legal, CO
Vanessa Steigerwald, DERR, CO
Peter Whitehouse, DERR, CO
Tim Kern, Ohio AGO
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APPENDIX 2
U.S. EPA's RESPONSES TO COMMENTS
FROM THE
STATE OF OHIO
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APPENDIX 2
U.S. EPA's RESPONSES TO COMMENTS
FROM THE
STATE OF OHIO
ON THE
EXPLANATION OF SIGNIFICANT DIFFERENCES
FOR THE
SEDIMENT OPERABLE UNIT
FIELDS BROOK SITE, ASHTABULA OHIO
PIIRPOSF
This document summarizes written comments received from the Ohio Environmental
Protection Agency (OEPA) on its review of the draft Explanation of Significant Differences.
OEPA's comments are, as follows:
Comment 1: OEPA is no longer acting as a support agency for this project.
Response: The text of the ESD was revised to clarify OEPA's role.
Comment 2: The landfill to be built on site would not meet the requirements of RCRA and
TSCA. The ESD does not describe the landfill design and identify ARARs
that will not be met.
Response: . The ESD was modified based on this OEPA comment. A fifth "difference" was
added to clarify ARARs that would not be met. Specifically, the landfill to be
constructed pursuant to the Floodplain/Wetland ROD (6/30/97) would not meet
Section 761.75(b)(3) of TSCA, which specifies a fifty foot distance between the
bottom liner and the historical high wate, table.
Comment 3: The ESD does not describe how Confidence Removal Goals (CRGs) would be
used to meet CUGs, on average, within an exposure area.
Response: The ESD was modified to include a discussion of CRGs.
Comment 4: OEPA does not agree with CUGs and the exposure frequencies upon which
they are based.
Response: The ESD was modified to include a statement of OEPA's position concerning the
the exposure frequencies and the CUGs.
Comment 5: OEPA notes that a full biological sampling and assessment of the Sediment
Operable Unit never done. The Focused Ecological Risk Assessment was
developed after the CUGs were finalized. There are post-remediation
Appendix 2 - Page 1
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Hazard Quotients in exceedance of 1 tor several species. The State of Ohio is
concerned that the Sediment Operable Unit remedy may not be protective of
ecological receptors and will conduct post-remediation biomonitoring to
assess the extent to which injuries continue to occur.
Response: U.S. EPA acknowledges that it did not perform a full biological assessment of the
Sediment Operable Unit and that the Focused Ecological Risk A'ressment was
prepared after the CUGs were developed. According to the Focused Ecological
Risk Assessment, there are post-remediation Hazard Quotients exceeding 1.
However, as discussed in the ESD text on page 14, U.S. EPA believes that the
remedy will be protective The response actions will reduce the short- and
long-term risks to ecological populations and reduce these population's potential
uptake of contamination via soil and food to acceptable levels of exposure. US.
EPA supports OEPA's decision to perform post-remediation biomonitoring.
Appendix 2 - Page 2
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APPENDIX 3
CLEANUP OOAr
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TABLE 2.5.0
CLEANUP GOALS
SEDIMENT OPERABLE UNIT - FIELDS BROOK SITE
ASHTABULA, OHIO
Woodward-Clyde
(ms/ke)
Chemical of Concern
.1.1-Trichloroethane
. 1 ,2.2-Tetrachloroeihane
,1.2-Trichloroethane
. 1 -Dichloroetlienc
.2,4-Trjchlorobenzene
,2-Dichlorobenzene
.2-Dichloroethcne (trans)
,4-Dichlorobenzene
2-ChIorophenol
Acenaphthene
Anthracene
Antimony
Arsenic*
Benzene
Benzidine
Benzo(a)anthracene
Benzo(a)pyrcne
Benzo(b)fluoranthene
Benzo(k)fluoninthcne
Beryllium
Alpha-BHC
Gama BHC (Lindane)
Bis(2-ethylhexyl)phthalate
Cadmium
Chlorobenzene
Chloroform
Chromium III
Chromium VI
Chrysene
Copper
Cyanide
Di-n-butylphthalate
Di-n-octvlphthalate
Dibenzf a. h (anthracene
Diethyl phthalaie
Dimethyl phihalaic
Ethvlhenzene
Fluoranthcnc
Ruorene
Heptachlor
Hexachloronenzeru: (p)
Hexachlombenzenf (si
Residential
393.451.00
51.00
179.00
17.00
43.717.00
393,451-00
87.433.00
425.00
21.858.00
262JOO.OO
Ul 1.502.00
1.749.00
5.80
35100
0.04
13.97
1.40
13.97
13.97
2.40
1.60
7.80
729.00
2.186.00
87.43300
1.672.00
4.371.673.00
21.858.00
139.73
161.752.00
87.433.00
437.167.00
87.433.00
1.40
3.497.338.00
437.167.00
437.167.00
174.867.00
174.867.00
2.30
6.38
6.38
Occupational
766.500.00
119.00
418.00
40.00
85.167.00
766.500.00
170.333.00
994.00
42.583.00
511.000.00
2.555,000.00
3.407.00
14.00
822.00
0.10
33.00
3.30
33.00
33.00
5.50
3.80
18.00
1.703.00
4.258.00
170.333.00
3,909.00
8.516.667.00
42.583.00
327.00
315.117.00
170.333.00
851.667.00
170.333.00
3.30
6.813.333.00
851.667.00
851.667.00
340.667.00
340.66700
5.30
1500
15.00
U.:00\FB20\SQDI\TABLn:.'>0 XLS
Page I of?
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TABLE 2.5.0
CLEANUP GOALS
SEDIMENT OPERABLE UNIT - FIELDS BROOK SITE
ASHTABULA, OHIO
Woodward-Clyde
(mp/kp')
Chemical of Concern
Hexachlorobutadiene
Hexachloroethane
Indeno( 1 ,2,3-cd)pyrene
Isophorone
Lead
Mercury
Methylene chloride
N-nitrosodiphenylarnine
Naphthalene
Nickel
Nitrobenzene
Total PCB
Phenol
Pyrene
Selenium
Tetrachloroethene
Thallium
Toluene
Trichloroethene
Vinyl Chloride
Zinc
Residential
131.00
729.00
14.00
10.737.00
500.00
1.312.00
1,360.00
2.081.75
174,867.00
87.433.00
2,186.00
1.30
2.623,004.00
1.311.502.00
21.858.00
196.00
262.00
874,335.00
927.00
5.40
847.335.00
Occupational
306.00
1.703.00
33.00
25,102.00
500.00
2.555.00
3.180.00
4.867.00
340,667.00
170.333.00
4.258.00
3.10
5.110.000.00
2,555.000.00
42,583.00
459.00
511.00
1.703.333.00
2,168.00
13.00
1.703.333.00
*»
**
Radionuclides
Uranium (soluble salts) in mg/kg
Uranium - 234 in pCi/kg
Uranium - 235 + D in pCi/kg
Uranium - 238 + D in pCi/kg
Technetium - 99 in pCi/kg
11,000.00
668.00
5.00
31.00
8,326.00
26,000,000.00
817.00
5.00
32.00
10,206.00
Notes:
- The CUG for arsenic has been replaced with the background concentration (*).
- Results for several compounds are greater than 1 million parts per million (**).
assumptions provided by USEPA.
LL200\FB20\SQDI\TABLE250.XLS
Page 2 of 2
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