PB96-963120
EPA/AMD/R09-96/151
January 1997
EPA Superfund
Record of Decision Amendment:
Koppers Company, Inc.,
Superfund Site, (Soil and Groundwater
Operable Unit) (Oroville Plant),
Oroville, CA
8/29/1996
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AMENDMENT #1
to the
RECORD OF DECISION
for the
SOIL AND GROUND WATER OPERABLE UNIT
KOPPERS COMPANY, INC. SUPERFUND SITE
OROVILLE, CALIFORNIA
U.S. Environmental Protection Agency
Region 9
San Francisco, California
August 1996
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Koppers ROD Amendment #1
Table of Contents
Section Page
I. DECLARATION 1
II. DECISION SUMMARY 3
1.0 SITE NAME, LOCATION, AND DESCRIPTION 3
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES 3
»
3.0 COMMUNITY PARTICIPATION 8
4.0 SCOPE AND ROLE OF DECISION 9
5.0 SUMMARY OF SITE CHARACTERISTICS 10
5.1 Nature and Extent of Contamination 10
5.2 Soil Stratigraphy and Contaminant Migration 12
5.3 Principal and Low Level Threat Wastes 12
6.0 SUMMARY OF SITE RISKS 13
7.0 DESCRIPTION OF ALTERNATIVES 16
8.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 19
9.0 SELECTED REMEDY 23
9.1 Cleanup Standards 23
9.2 Selected Remedial Action 24
9.2.1 Soil Excavation and Handling 24
9.2.2 Landfill Design and Construction 25
9.2.3 Corrective Action Management Unit 25
10.0 STATUTORY DETERMINATIONS 27
10.1 Protection of Human Health and the Environment 28
10.2 Compliance with ARARs 28
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10.3 Cost Effectiveness 32
10.4 Utilization of Permanent Solutions and Alternative Treatment
Technologies to the Maximum Extent Practicable 33
10.5 Preference for Treatment as a Principal Element 34
11.0 DOCUMENTATION OF SIGNIFICANT CHANGES 35
III. RESPONSE SUMMARY 36
1.0 INTRODUCTION 36
2.0 SUMMARY OF COMMENTS AND AGENCY RESPONSES 36
LIST OF TABLES
No. Title Page
2-1 Results of Initial Phase Treatability Studies 7
5-1 Soil Contaminants of Concern (by soil unit), Post-Removal Data, < 5 ft bgs 11
6-1 Toxicity Criteria for Soil Contaminants of Concern 15
6-2 Risk Based Remedial Goals 16
8-1 Comparative Analysis of Alternatives 20
9-1 Cleanup Standards for Surface Soil 23
10-1 Applicable or Relevant and Appropriate Requirements 30
LIST OF FIGURES
No. Title Page
1-1 Map of Koppers site 4
2-1 Soil Unit Boundaries in 1989 ROD 6
7-1 Areas of Soil Cleanup 18
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Koppers ROD Amendment #1
I. DECLARATION
SITE NAME AND LOCATION
Koppers Company, Inc.
Oroville, California
STATEMENT OF BASTS AND PURPOSE
This decision document presents the revised selected remedial action for contaminated
soils at the Koppers Company, Inc. (Koppers) site in Oroville, California, which was chosen
in accordance with the Comprehensive Environmental Response, Compensation and Liability
Act (CERCLA), as amended by the Superfund Amendments and Reauthorization Act
(SARA), and, to the extent practicable, the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP). This decision is based on the administrative record for this site.
The State of California concurs with the selected remedy.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this site, if not addressed
by implementing the response action selected in this Record of Decision (ROD), may present
an imminent and substantial endangerment to public health, welfare, or the environment.
DESCRIPTION OF THE SELECTED REMEDY
This Record of Decision (ROD) amends the previously selected remedy for soils at the
Koppers site. The revisions affect both the cleanup standards and the cleanup technologies
selected in the 1989 ROD for this site. The major components of the revised soil remedy are:
Cleanup standards based on continued industrial use of the site;
Excavation of contaminated surface soils and placement in a new on-site
landfill;
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Excavation of subsurface soils in the former pole washer and creosote pond
areas (including a small volume of principal threat waste) and placement of
these soils in a new on-site landfill;
Excavation of the former soil filtration bed and placement in a new on-site
landfill;
Backfilling and grading the excavated areas; and
Deed restrictions to prohibit future residential development (and other
inappropriate uses) of the site.
This remedy addresses the risks to human health and the environment posed by the
contaminated soils and debris at the site. As provided in the 1989 ROD, the cap in the
process area will remain as an interim remedy for that area of the site so that the Koppers
plant can continue to operate without major disruption. When soils beneath the capped area
are accessible, this contaminated soil will be remediated to achieve the same cleanup
standards selected in this ROD.
The excavation of subsurface soil hi the former pole washer area will also enhance the
ongoing ground water remedy by facilitating the removal of a significant volume of highly
contaminated perched ground water.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment, complies with
Federal and State requirements that are legally applicable or relevant and appropriate, and is
cost-effective. This revised soil remedy utilizes containment rather than treatment
technologies to address the wastes at the site. Because this remedy will result in hazardous
substances remaining on-site above health-based levels, EPA shall conduct a review pursuant
to Section 121(c) of CERCLA, 42 U.S.C. §9621, within five years after commencement of
remedial action to ensure that the remedy continues to provide adequate protection of human
health and the environment.
L Keith Takata
7j Director, Superfuqd Division
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Koppers ROD Amendment #1
II. DECISION SUMMARY
1.0 SITE NAME, LOCATION, AND DESCRIPTION
The Koppers Company Superfund site is located in Butte County just south of the city
limits of Oroville, California. The site comprises an operating, 200-acre wood-treating plant
and an area primarily south of the plant defined by a plume of contaminated groundwater
originating beneath the plant (see Figure 1-1). The Koppers plant itself lies in the floodplain
about 3000 feet east of the Feather River, on the fringe of an area where dredge mining
operations occurred in the early 1900s. The Koppers plant is bordered on the west by the
Louisiana-Pacific Corp. facility, which is also a Superfund site.
Land use in the vicinity of the site is mixed industrial, commercial, agricultural, and
residential. Residential areas are located primarily to the west (beyond the Louisiana-Pacific
site) and south.
The geology underlying the site consists of gravels, sands and clays that were
deposited by the Feather and ancestral Feather River systems. In the northern portion of the
Koppers property, the soils have been disturbed by the dredge mining operations. Several
interconnected aquifer zones have been defined on and off the site. The regional groundwater
flow is generally to the south.
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
The site has been used for wood treatment operations since 1948. Koppers purchased
the property in 1955 and has used a variety of chemical preservatives in its wood treating
processes. Wood products including utility poles and railroad ties have been pressure-treated
using chemicals that include pentachlorophenol (PCP), creosote, chromium and arsenic.
Koppers discontinued the use of PCP in 1988.
Soil and groundwater contamination at the site have resulted from both wood
treatment operations and related waste disposal practices. In addition, two process-related
fires at the plant (in 1963 and 1987) released PCP and its associated combustion products,
including dioxin, onto surrounding soils.
The State first identified the Koppers site as an environmental problem in the early
1970s. EPA placed the site on the National Priorities List (NPL) in 1984. Koppers began the
Remedial Investigation (RI) in April 1986 and issued the RI report in July 1988. EPA
completed the Endangerment Assessment, which evaluated risks to human health and the
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Koppers
Superfund
Site
Koppers
Plume
Area
Figure 1-1. Map of Koppers site
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Koppers ROD Amendment #1
environment from contamination at the site, in November 1988. The original Feasibility
Study (FS), which evaluated a wide range of soil and groundwater cleanup alternatives, was
issued in May 1989, along with a proposed plan.
In April 1987, an explosion and fire occurred at one of Koppers1 pentachlorophenol
wood treating processes. EPA issued a unilateral order requiring cleanup of fire debris and
stabilization of surface soils. The chip seal cap placed over process area soils remains in
place, and drummed fire debris is still stored at the site.
In September 1989, EPA selected soil and groundwater cleanup remedies for the
Koppers site. EPA documented the selection of these remedies in an Operable Unit Record
of Decision (ROD). The 1989 ROD divided the contaminated soils at the site into four
different areas, or units, and selected a specific soil remedy for each unit (see Figure 2-1).
EPA selected three innovative technologies as remedies for three of the soil units: in situ
bioremediation, soil washing, and fixation. The capping remedy selected for the remaining
soil unit was designated as an interim remedy that would eliminate exposure to contaminated
soil while allowing Koppers to continue plant operations. The area of capped soils was to be
cleaned up at a later date, when excavation of the soil would not disrupt plant operations.
The 1989 ROD selected risk-based cleanup goals for the following major contaminants
of concern in site soils: pentachlorophenol, carcinogenic polynuclear aromatic hydrocarbons
(cPAHs), polychlorinated dibenzo-p-dioxins/dibenzofurans (referred to collectively in this
ROD as either PCDD/PCDFs or dioxin), arsenic and chromium. The soil cleanup goals were
set at a level that would allow future residential use of the site.
In January 1991, EPA issued an Explanation of Significant Differences (ESD) that
clarified and made minor revisions to the 1989 ROD. The ESD changed the ROD to provide
for separate cleanup standards for subsurface soil at the Site and to clarify the use of
institutional controls as part of the selected remedy.
In February 1992, a consent decree between EPA and Beazer East, Inc. (which bought
the former Koppers Company) was entered in federal district court. The decree requires
Beazer to carry out remedial design/remedial action (RD/RA) work to implement the 1989
ROD. Because the three innovative soil cleanup technologies had not been tested at the site,
the soil remedy has been implemented using a phased approach. In the initial phase,
additional soil sampling was conducted and the ROD's soil remedies were evaluated using
site-specific treatability studies. The results indicate that cleanup technologies were
unsuccessful because they could not reduce contaminant levels to the residential cleanup
standards and/or they could not effectively treat the combination of organic contaminants and
metals typically present in soils at the site (see Table 2-1).
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L-P
NOTE: Soil areas are identified by the
letter "S° followed by a number, e.g. S-1.
S-1 - In situ Bioremediation
S-2 - Soil Washing
S-3 - Process Area Cap
S-4 - Fixation
Figure 2-1. Soil unit boundaries in 1989 ROD
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Koppers ROD Amendment #1
In Situ Bioremediation
In a laboratory treatability study conducted during RD, bioremediation effectively reduced
PCP levels in soil but was much less effective (i.e., could not achieve the cleanup goals)
for cPAHs. Bioremediation also did not reduce the dioxin levels in the test soils, and it had
no effect on metals (such as arsenic or chromium), which do not biodegrade. The in situ
bioremediation pilot project was cancelled because dioxin levels in the test plots were
found to be much higher than anticipated and the test plot area was excavated as part of
the removal action.
Soil Washing
Soil washing was evaluated in a pilot project conducted at the site in November 1993, in
which about 400 tons of soil were put through the soil washing unit. The process could not
consistently meet cPAH and dioxin cleanup goals, though it showed better (but not fully
successful) results in meeting the PCP cleanup goal. There was also no significant
reduction in the overall volume of soil exceeding cleanup goals.
Fixation
In laboratory treatability studies, fixation was effective in reducing the mobility of arsenic,
chromium and other metals. Results were variable for organic contaminants such as PCP,
cPAHs and dioxin. In general, a higher reagent concentration was required to -achieve
significant mobility reduction for the organic contaminants. Additional sampling indicates
that most areas with metal-contaminated soils at the site, including the S-4 area, also have
PCP, dioxin and/or cPAHs present.
table 2-1. Results of Initial Phase Treatability Studies
As part of the capping remedy for soil unit S-3 (and to comply with new EPA
regulations for wood treaters), drip pads for the process area were constructed in 1992.
Contaminated soil excavated during construction of the pads was stockpiled in a new soil
storage building at the site.
During initial sampling of the test plots for the S-l bioremediation pilot project,
unexpectedly high levels of dioxin were found in the surface soils, including levels exceeding
the recommended limit for worker exposure. Because of the risk posed to current workers at
the site, EPA directed Beazer to remove 15,000 cubic yards of dioxin-contaminated soil and
place it in a newly-constructed on-site landfill. This removal action was completed in August
1995. The landfill was designed and constructed to meet the requirements of Subtitle C of
the Resource Conservation and Recovery Act (RCRA).
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Two groundwater treatment systems, one located at the Koppers plant and the other
near the toe of the plume, have been constructed as part of the groundwater remedy.
3.0 COMMUNITY PARTICIPATION
The EPA has encouraged public participation throughout the RI/FS and remedial
design/remedial action (RD/RA) stages of the project, in accordance with CERCLA
requirements.
Fact sheets have been sent out to the public at key progress points in the investigation
and cleanup of the site. Informational meetings and site tours have been held during the
RD/RA phase, with representatives of public agencies and local citizen groups invited to
attend. RD/RA documents, including the 1996 Site-Wide Soils Remedy Report, were sent to
local libraries.
In December 1995, EPA issued a fact sheet describing its ongoing reevaluation of soil
remedies. This fact sheet, which was mailed to all interested parties, described both the
reconsideration of future land use scenarios for the site and the reevaluation of remedial
alternatives for soils. The results of the bioremediation, soil washing and fixation treatability
studies were discussed in the fact sheet. In addition, incineration, thermal desorption and
landfilling were presented as technologies being considered to replace the unsuccessful
innovative treatment technologies. The fact sheet encouraged the public to contact EPA with
any comments or ideas regarding the reevaluation of soil cleanup.
Shortly after the fact sheet was issued, EPA's Remedial Project Manager met with
elected officials and staff for both Butte County and the City of Oroville to discuss the
reevaluation of soil remedies and solicit any comments they had on the issue. No specific
concerns were expressed during those meetings, and representatives from the City's planning
department indicated that continued industrial use of the site was consistent with the City's
long range plans for the area. Two drop-in sessions for the public were also held in Oroville,
and no specific concerns or objections were raised during those lightly-attended sessions.
Public participation requirements for EPA's selection of the final remedy as defined in
CERCLA sections 113(k)(2)(B)(i-v) and 117(a) were met by the activities described below.
The proposed plan for the revised soil remedy was distributed using EPA's mailing list
for this site. A public comment period on the proposed plan was held between April 2, 1996
and May 2, 1996. Public notice appeared in a local newspaper, the Chico Enterprise Record,
prior to the start of the public comment period. A formal public meeting was held on April
16, 1996. A transcript of the meeting can be found in the Administrative Record for this site.
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There were no written comments submitted during the public comment period, and no
verbal comments were made during the April 16, 1996 public meeting. In a telephone
conversation with a City of Oroville official toward the end of the comment period, EPA's
Remedial Project Manager was told that the City had no objections to EPA's proposed change
in the soil remedy.
4.0 SCOPE AND ROLE OF DECISION
The selected remedial action addresses contamination in on-site soils and debris at the
Koppers plant. This action revises the soil remedy selected in the 1989 Operable Unit ROD.
Based on the results of treatability studies and additional site characterization work
performed since the 1989 ROD was issued, EPA concluded that the previously selected soil
cleanup remedies cannot achieve the 1989 ROD cleanup goals. The results of the initial
phase work on each of the three cleanup technologies are discussed in detail in the Site-Wide
Soils Remedy Report. In brief, the 1989 ROD's cleanup technologies were unsuccessful
because they could not reduce contaminant levels to the residential cleanup standards and/or
they could not effectively treat the combination of organic contaminants and metals typically
present in soils at the site.
EPA is selecting containment in an on-site landfill as the revised soil remedy for the
Koppers site. EPA is also changing the future use exposure scenario used to determine soil
cleanup levels from residential to continued industrial use of the site. The revised soil
remedy will reduce contamination to health protective levels consistent with continuing
industrial exposures to these soils. As described in the 1989 ROD, soils beneath the capped
portions of the process area will be addressed, consistent with the overall remedial objectives
for the site, when these soils are accessible (i.e., when operations cease or when process
equipment or structures are replaced). At that time, the soils will be further sampled to
determine whether they are principal threat wastes (see Section 5.3); if so, EPA may require
treatment of these soils prior to disposal in an on-site landfill cell.
In 1991, EPA issued an Explanation of Significant Differences (ESD) modifying and
clarifying certain features of the 1989 ROD. The ESD stated that EPA would establish a
separate set of cleanup standards for subsurface soil (defined as soil deeper than five feet) to
ensure groundwater protection. Based on the Leachability and Degradation Study (contained
in Appendix A of the Site-wide Soils Remedy Report), EPA has identified two areas of the
site with potential to impact groundwater: the former pole washer area and the former
creosote pond area. The revised remedy involves removal of the potential source material in
both areas as part of the soil cleanup. As a result, EPA does not currently plan to establish
separate cleanup standards for subsurface soils.
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The selected action addresses the documented potential threats from contaminated soil
at the Koppers plant. No modifications to the groundwater remedy are being made at this
time. The State of California is continuing its investigation of trace dioxin contamination in
off-site soils and associated animal products. Since dioxin contamination has been
documented on-site at Koppers, it is possible that the Koppers site is a contributor to the off-
site dioxin levels, although there are several potential sources. The outcome of the State's
investigations may result in further actions regarding the Koppers site.
5.0 SUMMARY OF SITE CHARACTERISTICS
The 1989 ROD provided a detailed summary of site characteristics for both soil and
groundwater based on data from the RI. The following discussion will therefore address only
the additional data gathered during RD/RA and the extent to which they have changed the
1989 ROD's conclusions about soil contamination, soil conditions and contaminant migration
at the site.
5.1 Nature and Extent of Contamination
The soils at the Koppers site are contaminated with a variety of chemicals used in the
wood treatment processes, including the F032, F034 and F035 wastes listed pursuant to 40
CFR Part 261 of the RCRA regulations. In addition, K001 wastes are present in the creosote
pond area because the pond bottoms were never removed at the time the ponds were closed.
The contaminants of concern in soils at the site are PCP, arsenic, chromium and carcinogenic
polynuclear aromatic hydrocarbons (cPAHs), which are compounds found in creosote. In
addition, polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/PCDFs) are present in soils
as a result of process fires and also because they were present as trace contaminants in the
PCP used for wood treatment.
Additional sampling was conducted as part of remedial design activities to better
define the physical characteristics of soils at the site as well as the distribution of
contaminants within the three soil units (S-l, S-2, and S-4) where treatment technologies were
to be used as part of the remedy. In addition, sampling conducted as part of the 1995
removal action provided significant data on the distribution of contaminant concentrations
with depth.
These sampling activities, summarized in the Site-Wide Soils Remedy Report, showed
that surface soils are typically contaminated with a mix of ail of the contaminants of concern
(with the exception of chromium, which rarely exceeds background levels). The additional
soil sampling also showed that dioxin levels in surface soils outside of the process area were
higher than anticipated. Contaminant concentrations in surface soils remaining at the site
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(i.e., not including those soils excavated during the recent removal action) are summarized in
Table 5-1.
Compound
Organics
PCP
(mg/kg)
Dioxin
(M9/kg)
cPAHs TEQ
(mg/kg)
Total cPAH
(mg/kg)
Inorganics
Arsenic
(mg/kg)
Chromium
(mg/kg)
Detection Frequency
SI
S2
S3
S4
90/117
69/71
74/77
73/75
29/30
11/11
30/30
30/30
69/79
3/3
39/39
39/39
1/1
79/80
80/80
25/29
30/30
36/36
36/36
6/9
9/9
Range
SI
S2
S3
S4
0.014 - >800
0.005 - 6.96
0.01 - 15.9
0.078 - 108.4
0.01 - 570
0.07-28.57
0.02-22.11
0.086 - 86.5
0.01 -5,100
37.8- 113.2
0.07-71.3
0.05 - 390.2
1.12
1.1 -160
29 - 151
2.8 - 93
76.7 - 224
3.9 - 563
52 - 620
3.6 - 53
48.2 - 137
Table 5-1. Soil Contaminants of Concern (by soil unit), Post Removal Data, < 5 ft bgs
Two of the contaminants of concern, arsenic and chromium, are also naturally
occurring metals. During RD, detailed sampling was conducted to determine background
levels in both dredge tailings and native (undisturbed) soils. The data showed that the
difference in background levels between these two soil types was not significant, and
background levels for all soils were set at 7.15 mg/kg for arsenic and 181 mg/kg for
chromium.
, Spil unit S-4 was described in the 1989 ROD as an area contaminated with arsenic
and chromium. Although the RI documented several areas with arsenic concentrations above
the expected background level, the S-4 area was defined on the basis of one sample with very
high arsenic and chromium levels collected in an area where wood was stored after being
treated with these chemicals. Subsequent sampling during RD found only moderately
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elevated levels of arsenic in the S-4 area (and in most areas where treated wood was stored).
In addition, soils with elevated levels of arsenic or chromium also typically are contaminated
with dioxin, cPAHs and/or PCP.
5.2 Soil Stratigraphy and Contaminant Migration
Data collected during RD and the 1995 removal action was combined with data from
the RI to provide an improved definition of surface soil stratigraphy. The two most prevalent
soil types at the site are (1) thin roadbase material underlain by native soils and (2) roadbase
fill material underlain by dredge tailings. The roadbase material typically consists of dredge
tailings (clayey gravels) which have been highly compacted by vehicle traffic. The upper
portion of the roadbase material in the wood storage areas also contains wood splinters and
fragments that slowly get ground into a wood dust by the heavy equipment used to transport
treated wood into and out of these areas.
The surface layers of the roadbase material have low infiltration rates (approximately
10"4 cm/sec) while the material below the upper compacted layer has relatively rapid
infiltration rates (10"1 to 10~2 cm/sec). The native soils have a lower permeability than the
overlying roadbase material, while the dredge tailings have permeabilities similar to the lower
roadbase material. The dredge tailings extend to depths of 20 feet, at which point native soils
are encountered.
The depth of contaminated soil in treated wood drying/storage areas is typically
limited to one foot because of the low permeability of the compacted roadbase material. The
former pole washer is located primarily over dredge tailings and contaminants are found here
at much greater depths. Although the creosote ponds were drained and backfilled in 1973,
the contaminated pond bottoms are still present in the subsurface, at depths of up to eight
feet.
5.3 Principal and Low Level Threat Wastes
The remaining soils to be addressed at the site were evaluated to determine whether
any of them should be characterized as principal threat waste (i.e., source materials that are
highly toxic or highly mobile that generally cannot be reliably contained or would present a
significant risk to human health or the environment should exposure occur). There is no
fixed threshold level of toxicity/risk that is used to define principal threats. For the purpose
of evaluating soils at the Koppers site, a potential risk of 10~3 (taking into account toxicity
and mobility) was used as the basis for identifying principal threat wastes.
With the possible exception of the capped process areas, surface soils at the site are
typically low-level threat wastes in terms of both toxicity and mobility. Contaminant levels
in surface soils outside the capped process area are typically less than 2 orders of magnitude
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above the 10"5 acceptable exposure levels for workers (described below in Section 6). In
addition, the most toxic compound, dioxin, is relatively immobile. There is one location near
the creosote pond area where dioxin levels exceed the 10~3 risk threshold; however, there is no
unique or distinctly different waste present at this location, and the result is considered to be
an anomaly and not an indication that principal threat waste is present.
There is only limited data on the soils beneath the capped portions of the process area,
and it is possible that some of these soils have dioxin levels that would exceed the 10~3 risk
level.
Based on the limited data available from soil borings and test pits, the former creosote
pond sediments have dioxin concentrations that exceed the 10"3 risk level. The layer of pond
sediments is one to two feet thick, and it is present at depths of roughly six to eight feet
below ground surface (bgs). The toxicity of these sediments is offset by the fact that they are
highly immobile, and thus do not pose a significant threat in their current location.
Nonetheless, these sediments may be considered principal threat waste solely on the basis of
their toxicity. EPA's rationale for how this principal threat waste will be addressed is
provided in Section 10.5.
6.0 SUMMARY OF SITE RISKS
In November 1988, EPA completed an Endangerment Assessment (EA), which
examined the current and potential future risks to public health from contamination at the
Koppers site. The EA used results from the Remedial Investigation (RI) to determine the
contaminants of concern. The EA then determined the possible exposure pathways (that is,
ways people could be exposed to contaminants now and in the future) and calculated the risks
associated with those exposures. The assessment showed that contaminant levels in soil were
too high to allow unrestricted use of the site. The highest risks from soil were associated
with future residential use of the site.
Although the conclusions of the 1988 risk assessment are still generally valid, there
have been some changes since then in how EPA conducts risk assessments and how EPA
views the toxicity of some of the contaminants found at the Koppers site. For example, in
1988, EPA had not yet classified PCP as a carcinogen (it now has), and thus no cancer risk
was calculated for exposure to PCP in soil. In 1988, all cPAHs were assumed to be equally
toxic, whereas currently EPA assigns each cPAH a specific toxicity factor (relative to
benzol(a)pyrene), similar to the way the toxicity of dioxin compounds is evaluated. Finally,
the toxicity of dioxin is currently being reassessed by EPA, with indications that its non-
carcinogenic effects on human health may be more significant than previously thought. The
net result of these changes is that risk-based soil cleanup standards for residential use, if
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calculated today, would be different than the ones calculated in 1988.
The soil cleanup goals in the 1989 ROD are primarily health-based levels established
based on the assumption that, in the future, the site might be developed for residential use.
However, after further discussion with local officials, land use planning authorities and the
public, it was apparent that continued industrial use of the site was consistent with local land
use plans and more likely than future residential development. As a result, the reevaluation
of soil remedies included the development of risk-based soil cleanup standards for the
industrial worker exposure scenario.
The development of the revised standards is summarized below and discussed in detail
in Appendix B (Reevaluation of Human Health Risks) of the Site-Wide Soils Remedy Report.
The potential exposure pathways for the on-site industrial worker are:
Incidental ingestion of soil,
Dermal contact with soil, and
Inhalation of dust derived from soil.
For each of these pathways, risk-based remedial goals (RBRGs) for all contaminants except
dioxin were back-calculated from a target excess cancer risk of one in 100,000 (or 1 x 10"5)
and a hazard quotient of 1 for noncarcinogenic risks. The calculations relied upon a set of
worker exposure factors for each pathway and toxicity criteria for each contaminant.
The exposure factors used in the evaluation were selected to represent a Reasonable
Maximum Exposure (RME) for workers. The RME is defined as the highest exposure that is
reasonably expected to occur at the site, and the use of the RME represents a conservative
approach to evaluating risks. The exposure factors used were a combination of EPA default
values and site specific estimates. For example, the respirable dust level was assumed to be
equal to the EPA PM10 standard in order to reflect the dust generated by vehicle traffic at the
Koppers site.
Table 6-1 lists the toxicity criteria for the contaminants of concern in soils at the
Koppers site. For both PCDD/PCDFs and cPAHs, the risks of exposure were calculated using
the toxicity equivalent factors (TEF) approach. This approach expresses the toxicity of each
compound in terms of the most toxic compound within the group (e.g., the toxicity of
PCDD/PCDFs is expressed in terms of 2,3,7,8-tetrachlorodibenzodioxin, or 2,3,7,8-TCDD,
equivalents and the toxicity of cPAHs is expressed in terms of benzol(a)pyrene, or B(a)P,
equivalents). When the concentrations of PCDD/PCDFs and cPAHs are discussed in this
ROD, they are expressed in terms of these toxic equivalents (TEQ).
- 14-
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Chemical
Arsenic
Chromium VI
Carcinogenic PAHs:
Benzol(a)anthracene
Benzol(a)pyrene
Benzol(b)fluoranthene
Benzol(k)fluoranthene
Chrysene
Dibenz(a,h)anthracene
lndeno(1 ,2,3-cd)pyrene
PCDD/PCDFs
Pentachlorophenol
Dermal
Absorbance
0.03
0.01
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.03
0.25
Noncarcinogenic Effects
Chronic Reference Dose
(RfD)a
Oral Inhalation
(mg/kg/day) (mg/kg/day)
3.00E-04 NA
5.00E-03 NA
4.00E-02 (d) NA
4.00E-02 (d) NA
4.00E-02 (d) NA
4.00E-02 (d) NA
4.00E-02 (d) NA
4.00E-02 (d) NA
4.00E-02 (d) NA
NA NA
3.00E-02 3.00E-02
Carcinogenic Effects
Slope Factor
(SF)B
Oral Inhalation
(mg/kg/day)'1 (mg/kg/day)'1
1.50E+00 1.50E+01
NA 2.90E+02
0.1 (c) 0.1 (c)
7.30E+00 7.30E+00 (r)
0.1 (c) 0.1 (c)
0.01 (c) 0.01 (c)
0.001 (c) 0.001 (c)
1 (c) 1 (c)
0.1 (c) 0.1 (c)
1.50E+05 1.50E+05
1.20E-01 1.20E-01(r)
Table 6-1. Toxicity Criteria for Soil Contaminants of Concern
NA - Not Available
a - RfDs were obtained from IRIS, HEAST, ECAO and EPA Region IX
b - Slope factors were obtained from IRIS or HEAST
c - EPA Toxicity Equivalent Factor (TEF) relative to Benzol(a)pyrene
d - Noncarcinogenic health effects of PAHs were evaluated using the oral RfD for naphthalene
r - route extrapolation
f
50
§
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Koppers ROD Amendment #1
The resulting RBRGs are shown in Table 6-2. These RBRGs represent the
concentration at which each contaminant by itself would pose 'either a 1 x 10'5 cancer risk or
a hazard quotient of one.
For dioxin, the reevaluation of soil remedies was done using a 1 ug/kg cleanup
standard for industrial exposures. This level is more stringent than the earlier industrial
exposure level recommended by the Centers for Disease Control (5-7 ug/kg) and thus reflects
the tentative findings of EPA's recent reassessment of dioxin toxicity.
The site risks associated with ecologic receptors were discussed in the original
Endangerment Assessment. The primary environmental concern regarding contaminated soils
at the site is soil erosion, i.e., migration of contaminated soil or sediment to surface waters.
Construction of the drip pads and excavation of highly contaminated soil as part of the 1995
removal action have reduced those risks, although no quantitative assessment has been
performed to determine the magnitude of that reduction.
Chemical
Arsenic
Total Chromium
cPAHs
POP
Units
mg/kg
ii
n
ii
Carcinogenic Effects
Target Risk = 1 x 10"5
21
614*
2.6
79
Noncarcinogenic Effects
Target Hazard Quotient = 1
379
527,751
27,073
10,186
Calculated using a Cr VI slope factor of 290 (mg/kg-day)"1 and a site-specific Cr VI to Cr III ratio of 1:61.
Table 6-2. Risk Based Remedial Goals
7.0 DESCRIPTION OF ALTERNATIVES
The 1996 Site-Wide Soils Remedy Report identified and evaluated a variety of
alternatives that could be used to clean up contaminated soils at the site. As noted earlier,
additional soil sampling has shown that the contaminants (both organic and inorganic) tend to
be mixed together throughout the surface soils at the site. Therefore, the 1989 ROD's
approach of developing remedial alternatives based on the predominant contaminant(s) in a
given area is no longer appropriate. The only distinction among soils that was carried over
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Koppers ROD Amendment #1
from the 1989 ROD is between those soils beneath the capped portions of the process area,
which cannot be removed without causing major disruption of plant operations, and the
remainder of contaminated soil at the site.
Using the RBRGs for industrial site use shown in Table 6-2, the area and volume of
contaminated soil and debris that would require cleanup was reassessed. As described below,
the resulting area and volume of contaminated soil and debris are about one-half and one-
third, respectively, of the 1989 ROD estimates.
In most areas, soil contamination extends to a depth of one foot or less below ground
surface. Deeper contamination exists in the areas of the former creosote pond and the former
pole washer. There are also areas of contaminated soil and debris not addressed explicitly by
the 1989 ROD which are now being included as part of the overall soil cleanup: 1) the
drums of debris from the 1987 post-fire cleanup, which are currently stored on site; 2) the
soil filter bed, which was part of a wastewater treatment system; and 3) the sediments in the
fire pond. The estimated total area of soil to be cleaned up is roughly 22 acres (including the
capped process area), and the estimated volume is 100,000 cubic yards (see Figure 7-1).
Soil Cleanup Alternatives
Cleanup alternatives were evaluated in terms of their ability to address the
combination of contaminants found in soils and to achieve the RBRGs for industrial use for
the Koppers site. The development and screening of treatment and containment alternatives
was conducted without attempting to distinguish between principal and low level threat
wastes. Using the EPA presumptive remedy guidance for wood treater sites and related
documents as a guide, a variety of treatment and containment technologies (including those
selected in the Koppers 1989 ROD) were screened in order to develop alternatives that would
be able to handle both organic and inorganic contaminants. Based on experiences from
Koppers and other wood treating sites, there are a limited number of alternatives that can be
used, particularly for soils contaminated with dioxin. The following cleanup alternatives were
evaluated in detail:
1) On-site Incineration - Under this alternative, organic contaminants would be destroyed
by burning the soil at high temperatures in an on-site incinerator. The soil is first excavated
and screened to remove oversized material, which cannot be treated by incineration. This
material (approximately 20% of the original soil volume) would be placed in a new on-site
landfill. Following incineration, treated soil would be placed in the landfill if metals exceed
the cleanup standard (50% of the treated soil was assumed to fall into this category). The
excavated area would be backfilled with clean fill (or treated soil if metals are within cleanup
goals). Long-term management includes maintenance of the landfill cover and groundwater
monitoring around the landfill. The estimated volume of soil and debris to be placed in the
landfill is 60,000 cubic yards.
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Koppers ROD Amendment #1
r
New landfill
area
^existing
landfill
Former Pole
/ Washer Area
Wood . Fire Popd
Storage!
Area |t, "V
;WM ' .
Former Creosote
Pond Area
\ 1,,-v /^r
^^_. 8'V** /$%&?
.-^4^? /i&t&'i
i
/
'Soil Storage
Building
/
I
LEGEND
sssi
Area Excavated in 1995
Areas to Be Excavated
Figure 7-1. Areas of soil cleanup
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Koppers ROD Amendment #1
2) On-site Thermal Desorption - This alternative deals with soils in a manner similar to
incineration (including the landfill for oversized material), except that thermal desorption is
the treatment technology, rather than incineration. Screened soil is heated to vaporize the
contaminants, and the gases produced during this thermal desorption step are treated to
destroy contaminants using an on-site gas-phase incinerator or other technology. Treated soil
would be placed in an on-site landfill if metals exceed the cleanup standard. The excavated
area would be backfilled with clean fill (or treated soil if metals are within cleanup goals).
Long-term management includes maintenance of the landfill cover and groundwater
monitoring around the landfill.
3) On-site Landfill - This alternative involves the excavation and placement of
contaminated soil and debris in a hazardous waste landfill to be constructed on the northern
portion of the Koppers property. No treatment of the soil would occur before placement.
The design of the landfill would be similar to the existing one constructed at the site in 1995.
The excavated area would be backfilled with clean imported fill. The landfill would occupy
roughly seven acres. Long-term management includes maintenance of the landfill cover and
groundwater monitoring around the landfill.
For each of the three alternatives described above, institutional controls would be
included as part of the remedy. These controls would consist of deed restrictions which
prohibit certain future uses of the property (such as residential development).
Each of the three alternatives would also utilize a Corrective Action Management Unit
(CAMU), as defined by RCRA Subtitle C, for the management of soil and debris that contain
listed hazardous waste or which themselves exhibit a hazardous waste characteristic. The
alternatives would comply with all substantive portions of the CAMU rule as ARARs.
Therefore, the CAMU is not subject to the requirements of the RCRA Land Disposal
Restrictions (LDRs).
8.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
This section presents a comparison of alternatives according to nine evaluation criteria
which are used in the selection of Superfund remedies. Table 8-1 provides a summary of this
comparison. Since comments on each alternative were not received from the State of
California or the community, the criteria regarding state and community acceptance are not
included in the table.
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Koppers ROD Amendment #1
Description
Overall Protection
ARARs Compliance
Long-term
effectiveness
Reduction of
toxicity, mobility or
volume through
treatment
Implementability
Short-term
effectiveness
Cost (expressed as
present value)
ALTERNATIVES (all on-site)
Incineration
Soil is burned in an on-site
incinerator. Oversized
material is placed without
treatment in a new on-site
landfill. Treated soil with
elevated levels of inorganics
is also put in the on-site
landfill. Estimated landfill
volume is 60,000 cubic
yards.
Reduces risk by destroying
organic contaminants in soil
and by eliminating exposure
to metals as well as organic
contaminants in oversized
rocks & debris.
Complies
Effective as long as landfill
cover & institutional controls
are maintained
Destroys PCP, cPAHs &
dioxin in treated soil; toxicity,
mobility and volume of
arsenic in soil and of all
contaminants in oversized
rocks & debris are not
reduced by treatment.
Process is commercially
available. Significant
administrative issues likely
to be encountered for siting
treatment unit. Pilot testing
would be necessary.
Incinerator stack emissions
must be closely monitored.
Vehicular & airborne
transport of contaminants
during excavation and soil
handling are likely hazards.
Additional soil handling is
required.
Capital: $82,900,000
30 yr.O&M: $1,200,000
Total: $84.1 million
Thermal Desorption
Soil is treated in on-site
thermal desorption unit.
Oversized material is placed
without treatment in a new
on-site landfill. Treated soil
with elevated levels of
inorganics is also put in the
on-site landfill. Estimated
landfill volume is 60,000
cubic yards.
Reduces risk by destroying
organic contaminants in soil
and by eliminating exposure
to metals as well as organic
contaminants in oversized
rocks & debris.
Complies
Effective as long as landfill
cover & institutional controls
are maintained
Destroys PCP, cPAHs &
dioxin in treated soil; toxicity,
mobility and volume of
arsenic in soil and of all
contaminants in oversized
rocks & debris is not
reduced by treatment.
Process is commercially
available, although track
record with wood treating
sites is limited. Significant
administrative issues likely
to be encountered for siting
treatment unit. Pilot testing
would be necessary.
Off-gas stack emissions
must be closely monitored.
Vehicular & air-borne
transport of contaminants
during excavation and soil
handling are likely hazards.
Additional soil handling is
required.
Capital: $61,400,000
30 yr.O&M: $1,200,000
Total: $62.6 million
Landfill
Soil is excavated and
placed without treatment in
a new hazardous waste
landfill to be constructed at
the site. Estimated landfill
volume is 100,000 cubic
yards.
Reduces risk by using
engineering controls to
eliminate exposure to
contaminants in soil &
debris.
Complies
Effective as long as landfill
cover & institutional
controls are maintained
Does not reduce toxicity,
mobility or volume of
contaminated soil through
treatment.
Can be readily
implemented. A smaller
landfill was recently
constructed at the site.
Vehicular & airborne
transport of contaminants
during excavation and
landfilling are likely
hazards. Has the shortest
implementation period.
Capital: $12,700,000
30 yr.O&M: $1,200,000
Total: $13.9 million
Table 8-1. Comparative Analysis of Alternatives
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Koppers ROD Amendment #1
Protection of Human Health and the Environment
All three of the alternatives would achieve overall protection of human health and the
environment. Excavation of contaminated soil would be identical for each alternative,
resulting in a site-wide average worker exposure risk from residual contamination that is
within the acceptable risk range. Under each alternative, wastes would remain on-site, with
reliance on engineering controls to prevent future exposure.
Compliance with ARARs
All three alternatives would comply with ARARs. The three alternatives are not
required to comply with RCRA Land Disposal Restrictions (LDRs) because the alternatives
utilize a CAMU for management/disposal of remediation wastes.
Long-term Effectiveness and Permanence
All three alternatives would immobilize contaminants by use of an on-site landfill to
permanently dispose of some or all of the contaminated soil. While the treatment alternatives
provide a slightly higher degree of permanence, the advantage is limited because neither
treatment would reduce the total volume of contaminated material by more than 40%.
Oversized soil and debris that cannot be treated by incineration or thermal desorption
typically is contaminated with dioxin and therefore cannot be sent to an off-site landfill.
Thus, for the treatment alternatives, untreated oversized material and treated material which
still contains inorganic contaminants would be placed in an on-site landfill.
The contaminants of concern (particularly dioxin) are relatively immobile in the
absence of a solvent, and it is therefore highly unlikely they would leach out of the landfill if
the liner should develop a leak. Thus, the long-term effectiveness of each alternative relies
primarily upon maintenance of the landfill cover to prevent direct exposure to contaminants,
as well as institutional controls to insure that the property is not developed in the future for
residential or other land uses that could result in unsafe exposure to residual contamination.
The residual risk of exposure to contaminants and the long-term maintenance requirements
would be approximately the same under all three alternatives.
Reduction of Toxicity, Mobility or Volume Through Treatment
Incineration and thermal desorption would provide permanent destruction of organic
soil contaminants except for those present on the oversized material (cobbles greater than two
inches in size) and the drummed fire debris. These materials are too large to be processed in
the treatment units. Neither incineration nor thermal desorption would remove or destroy
inorganic contaminants (arsenic and chromium).
Both technologies would reduce the total volume of contaminated soil by about 40%,
with the remaining 60% (i.e., 60,000 cubic yards) placed in an on-site landfill. However, this
reduction in landfill size would not achieve a corresponding reduction in risk from the
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Koppers ROD Amendment #1
presence of an on-site landfill over time. Nor would treatment better achieve the health-based
cleanup standards or other remedial objectives at the Site.
Implementability
While incineration and thermal desorption are each commercially available, site-
specific treatability studies would be needed to demonstrate their effectiveness and to provide
the basis for design of a full-scale system. Significant administrative issues (such as
coordination with other regulatory agencies) could make implementation difficult. EPA's
experience at other sites has also shown that implementation of thermal destruction
alternatives such as incineration of soil or off-gases from thermal desorption units is often met
with strong community opposition. Landfill technology previously has been used successfully
at the site and is readily implementable.
Short-term Effectiveness
Each alternative presents a limited short-term risk associated with the excavation,
transport and handling of contaminated soil. The risks are primarily to workers at the site,
with a lesser risk to nearby residents due to potential migration of contaminated dust. In
addition, stack emissions from either the incinerator or the thermal desorption alternative's
vapor-phase treatment unit pose a potential threat to on-site workers and would have to be
closely monitored to insure compliance with air quality standards.
Unlike the landfilling alternative, the treatment alternatives would require a high
degree of soil handling both before and after treatment. In addition, the landfilling alternative
can be implemented in less time (two years) than the treatment alternatives (three and one-
half to six years). Overall, the short-term risks of the landfilling alternative would be lower
than the treatment alternatives.
Cost
There are significant differences in cost between the alternatives that include treatment
(present worth of $84.1 million for incineration, $62.6 million for thermal desorption) and the
landfilling alternative that does not include treatment (present worth of $13.9 million).
Community Acceptance
There were no comments received from the community during the public meeting and
no written comments were submitted during the comment period.
State Acceptance
The State of California supports the landfill alternative proposed by EPA as well as
the use of the industrial worker exposure scenario for setting cleanup standards. The State's
support of the landfill alternative is contingent upon inclusion of adequate deed restrictions
and the establishment of an enforceable long-term operations and maintenance agreement.
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Koppers ROD Amendment #1
9.0 SELECTED REMEDY
9.1 Cleanup Standards
The new soil cleanup standards are presented in Table 9-1. The soil cleanup will be
designed to achieve a site-wide excess cancer risk no greater than one in 100,000 (or 1 x 10"s)
for industrial workers based on exposure to arsenic, chromium, cPAHs and PCP in surface
soils (i.e., soils up to five feet below ground). Because soils at the Koppers site typically
contain a mixture of contaminants, the cleanup standard is defined in terms of the combined
risk from arsenic, chromium, cPAHs and PCP. For dioxin, the cleanup standard is 1 ug/kg.
Achievement of the cleanup standards will lower the overall risk from contaminants at the site
to a level considered safe for industrial workers.
Contaminant
Arsenic
Chromium
PCP
cPAHs
Dioxin
ID'5 Risk Level
for
Industrial Workers1
21 mg/kg
477 mg/kg
79 mg/kg
2.6 mg/kg
0.24 ug/kg
Cleanup
Standard
Combined
Site-Wide
Cancer Risk
of10'5
1 Mg/kg
Table 9-1. Cleanup Standards for Surface Soil
1 From Appendix B of the Site-Wide Soils Remedy Report (March
1996). The concentrations shown represent the level at which
the contaminant by itself would present a 10"5 cancer risk to
industrial workers.
Based on the results of the Leachability and Degradation Study (contained in
Appendix A of the Site-wide Soils Remedy Report), there are only two areas of the site
where subsurface soils (i.e., soils deeper than five feet) have the potential to impact
groundwater: the former pole washer area and the former creosote pond area (see Figure 7-1).
In both areas, the selected remedy involves removal of the source material. As a result, the
objectives of the BSD with respect to this issue (see Section 4.0) will be satisfied, and there is
no need to establish separate cleanup standards for subsurface soil.
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Koppers ROD Amendment #7
9.2 Selected Remedial Action
The selected remedial action for contaminated soil and debris is excavation and
disposal in an on-site landfill. As described below, approximately 100,000 cubic yards of
contaminated soil and debris will be excavated or moved from existing storage locations and
placed in a newly-constructed on-site landfill.
Institutional controls consisting of deed restrictions limiting future uses of the site to
industrial activities are also part of the remedy. The deed restrictions will prohibit future uses
of the property (such as residential development) that are not consistent with the level of
protectiveness achieved by the cleanup. Deed restrictions may also include routine
maintenance or repair activities of the landfill cover. Deed restrictions shall be set forth in an
EPA-approved form running with the land and enforceable against present and future owners
of the property.
9.2.1 Soil Excavation and Handling
As described in more detail in the 1996 Site-Wide Soils Remedy Report, the locations
and approximate volumes of soil and debris to be placed in the landfill are as follows:
Estimated Estimated
Location Area (sq ft) Volume (cu yd)
Soil Storage Building na 4,000
Log Drying Areas 240,000 9,000
Process Areas (combined) 400,000 33,000
Creosote pond area 80,000 21,000
Fire pond sediments 40,000 5,000
Pole Washer area 10,000 4,000
Fire Cleanup Debris na 1,000
Soil Filtration Bed 85.000 15.000
SUBTOTAL 855,000 92,000
Contingency (approx. 10%) 85.000 8.000
TOTAL 940,000 100,000
The RBRGs listed in Table 9-1 will be used as the basis to determine the extent of
surface soil excavation. In the wood storage areas, the depth of excavation is expected to be
no more than one foot. Soils in the creosote pond area will be excavated to the bottom of the
former creosote ponds (estimated average depth is seven feet). Soils in the former pole
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Koppers ROD Amendment #1
washer area will be excavated down to a depth of approximately 17 feet in order to remove,
to the maximum extent practicable, contaminated soil and perched groundwater that is serving
as a continuing source of groundwater contamination in the regional aquifer. All excavated
areas will be backfilled with clean soil.
Soils beneath the capped portions of the process area (defined as the drip pads,
secondary containment facilities and permanent facilities shown in Figure 1 of the "Final
Design Report, Operable Unit S-3 Cap and Operations and Maintenance Plan, Koppers
Company, Inc., Superfund Site (Feather River Plant), Oroville, California," dated March 11,
1994) will continue to be left in place until the soil is accessible, i.e., until wood treating
operations cease or process equipment is replaced. When the soil is accessible, the capped
area will be remediated to meet the cleanup standards described above. At that time, the soils
will be further sampled to determine whether they are principal threat wastes; if so, EPA may
require treatment of these soils prior to disposal in an on-site landfill cell.
9.2.2 Landfill Design and Construction
The landfill will be constructed above grade and will occupy approximately seven
acres in the northeast portion of the Koppers property. It will be built as an extension of the
existing 15,000 cubic yard landfill. Design and operation of the landfill will meet the
requirements listed in Section 10.2 below. The time required to construct the landfill cell,
excavate and place the contaminated soil and construct the final cover is estimated to be two
years (based on two construction seasons). A temporary cover will be placed over the landfill
between construction seasons to prevent infiltration of rainfall and generation of contaminated
runoff from the landfill cell, as well as to prevent exposure to contaminated soil.
Capital costs for the landfill remedy, including design, permits, construction and soil
excavation, are approximately $12.7 million. The present worth of operation and maintenance
costs, including groundwater sampling and cap maintenance for 30 years, is approximately
$1.2 million.
9.2.3 Corrective Action Management Unit
In issuing this ROD Amendment, EPA designates as a Corrective Action Management
Unit (CAMU) the area designated for a landfill under the selected remedial alternative.
Accordingly, the CAMU regulation is an ARAR as discussed in Section 10.2 of this ROD
Amendment. The approximate size and location of the landfill area is shown on Figure 7-1.
The final' size and location will be determined during remedial design.
This ROD amendment documents the CAMU designation pursuant to 40 CFR Part
264.552(f), as implemented through the California EPA, Department of Toxic Substances
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Koppers ROD Amendment #1
Control, Hazardous Waste Regulations, Title 22, Chapter 14, §66264.552. Hereinafter, the
CAMU regulations will be referred to as Title 22, §66264.552. The notice requirements for
this ROD amendment shall satisfy public notice requirements under such CAMU regulations.
Without a CAMU, the remedy would require treatment of K001 waste (and, in the
future, possibly F032, F034 and F035 wastes) prior to placement in the landfill in order to
satisfy RCRA LDRs. The LDR treatment standards are much lower than the cleanup
standards for the site. Further, the remedy is designed to be reliable and protective for
addressing (via containment only) the risks posed by these listed wastes. The costs and short-
term risks associated with adding a treatment component to satisfy LDRs would be
unwarranted and unjustified.
In designating the CAMU, EPA has considered the criteria set forth in Title 22,
§66264.552 and determined that the CAMU satisfies the following criteria:
the CAMU will facilitate the implementation of a reliable, effective, protective and
cost-effective remedy;
the management of waste at the designated CAMU will not create unacceptable risk to
human health or the environment resulting from exposure to hazardous wastes or
hazardous constituents;
wastes in the CAMU shall be managed and contained to minimize future release, to
the extent practicable;
the CAMU expedites the timing of remedial activity implementation, when appropriate
and practicable; and
the CAMU, to the extent practicable, minimizes the land area of the facility upon
which wastes will remain in place after closure of the CAMU.
The CAMU regulations also provide that the CAMU "shall include uncontaminated
areas of the facility, only if including such areas for the purpose of managing remediation
waste is more protective than management of such wastes at contaminated areas of the
facility." Title 22, §66264.552(c)(3). While the CAMU at the Site will be located in an
uncontaminated area, management of waste in this area is more protective than management
of the waste at contaminated areas at the Site because it enhances both the short-term and
long-term reliability of the remedy for the reasons discussed below.
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Koppers ROD Amendment #7
The CAMU will be located in an area out of the floodplain and adjacent to an existing
landfill. The "bottom" of the landfill cell (i.e., soil berms, vadose zone monitoring system
and bottom liners) can be constructed in a clean area, thereby eliminating worker exposure to
soil contaminants during this phase. Further, contaminated soil will only have to be
excavated and transported once (at the time it is placed into the landfill), thereby minimizing
the risks of both worker exposure during handling as well as off-site residents' exposure to
contaminated wind-borne dust. In addition, limited areas are available for locating a landfill
of this size on-Site.1 Creation of a single contiguous landfill area in an isolated corner of the
Site will reduce the possibility of damage to the landfills from ongoing plant operations or
future activities at the site, as well as simplifying long-term maintenance of the landfill cover.
EPA also has considered the criteria in subparagraph (6) of Title 22, §66264.552(c)
and determined that the concerns expressed in such criteria are inappropriate and/or
inapplicable to the Site for the reasons discussed below. The regulations in this subparagraph
provide that the CAMU "shall enable the use, when appropriate, of treatment technologies
(including innovative technologies) to enhance the long-term effectiveness of [remedial]
actions by reducing the toxicity, mobility or volume of wastes that will remain in place after
closure of the" CAMU. The CAMU landfill will effectively and reliably contain and
immobilize the untreated wastes at the Site. As discussed earlier, treatment technologies to
reduce toxicity, mobility or volume are not appropriate for the Site. Therefore, in designating
this CAMU, EPA has considered this criteria, and determined that it is not a factor for this
Site. EPA has determined that the remedy described in this ROD Amendment complies with
the requirements set forth in Title 22, §66264.552(e). EPA has made such determination
pursuant to its authority to determine compliance with ARARs.
10.0 STATUTORY DETERMINATIONS
Under its legal authorities, EPA's primary responsibility at Superfund sites is to
undertake remedial actions that achieve adequate protection of human health and the
environment. In addition, section 121 of CERCLA establishes several other statutory
requirements and preferences. These specify that, when complete, the selected remedial
action must comply with applicable or relevant and appropriate environmental standards
established under federal and State environmental laws unless a waiver is justified. The
selected remedy must also be cost-effective and utilize permanent solutions and alternative
treatment technologies to the maximum extent practicable. Finally, the statute includes a
preference for remedies that employ treatment mat permanently and significantly reduces the
1 The majority of the contaminated soils are located in the currently operating central process
area and adjoining wood storage area. Locating the CAMU in this area would not only disrupt
the facility, but also pose logistical difficulties for removing the soil and constructing the landfill.
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Koppers ROD Amendment #1
volume, toxicity, or mobility of hazardous wastes as their principal element. The following
sections discuss how the selected remedy addresses these statutory requirements and
preferences.
10.1 Protection of Human Health and the Environment
The selected remedy protects human health and the environment through containment
of contaminated soil and debris in an on-site landfill. The landfill will be constructed above
grade and will comply with RCRA requirements for hazardous waste landfills. Excavation of
surface soils to achieve the soil cleanup standards will ensure that residual contamination does
not pose unacceptable risks to workers at the site. In addition, backfilling of excavated areas
with clean fill will provide a further measure of protection.
Deed restrictions will prevent any future uses of the site (such as residential
development) that would result in unacceptable levels of exposure. There are no short-term
threats associated with the selected remedy that cannot be readily controlled. In addition, no
adverse cross-media impacts are expected from the remedy.
The primary long term risk posed by the landfill is direct exposure to (i.e., direct
contact with) the contaminated material it contains. Exposure is highly unlikely, however,
because of the 15 to 55 foot thick berm of clean soil surrounding the lower third of the
above-grade landfill and the two and one-half feet of cover material (which includes a flexible
membrane liner) over the area above the berm. In addition, the landfill will be surrounded by
a chain link fence.
The potential for exposure due to migration of contaminants through a leaking liner
and into groundwater that is used for water supply is exceedingly small. The contaminants
are currently adsorbed onto soil and debris, including wood fragments. Further, the soil and
debris will be placed in the landfill in a relatively dry state (i.e., very low moisture content
and no free liquids), with at most only trace levels of solvents (such as diesel fuel). In order
for contaminant migration to occur, there would have to be long-term undetected leaks both
in the upper liner (to allow sufficient water to enter the landfill cell) and the two bottom
liners, as well as the underlying clay layer. Certain contaminants, such as dioxin and cPAHs,
are hydrophobic, and their migration would occur only through transport of soil particles
along with the water. The landfill design, monitoring systems and maintenance requirements
are expected to prevent these conditions from ever developing.
10.2 Compliance with ARARs
Remedial actions selected under CERCLA must comply with all Applicable or
Relevant and Appropriate Requirements ("ARARs") under federal environmental law or,
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where more stringent than the federal requirements, state or state subdivision environmental
or facility siting law. Where a State is delegated authority to enforce a federal statute, such
as RCRA, the delegated portions of the statute are considered to be a federal ARAR unless
the State law is broader or more stringent than the federal.
ARARs are generally categorized as follows: (1) chemical-specific requirements, (2)
action-specific requirements, and (3) location-specific requirements. Where no ARAR exists
for a given chemical, action or location, EPA may consider non-promulgated federal or state
advisories and guidance as To Be Considered criteria ("TBC"). Although consideration of a
TBC is not required, if standards are selected based on TBCs, those standards are legally
enforceable as if the TBC were an ARAR. As the ROD amendment addresses only the soils,
no changes are being made to the groundwater remedy ARARs. The selected remedy will
comply with ARARs which apply to the soils. These ARARs are summarized in Table 10-1
and described below.
Chemical-specific ARARs are risk-based cleanup standards or methodologies which,
when applied to site-specific conditions, result in the development of cleanup standards for
contaminants of concern. No numerically set standards exist for soils under federal or State
law.
Location-specific ARARs are restrictions placed on the concentration of hazardous
substances or the conduct of activities because of the special location, which have important
geographical, biological or cultural features. Examples of special locations include wetlands,
flood plains, sensitive ecosystems and seismic areas. The location-specific ARARs which
apply to the landfill are those addressing seismic considerations and floodplains (40 CFR
264.18 as implemented through California EPA Department of Toxic Substances Control,
Hazardous Waste Regulations, Title 22, Chapter 14 ("Title 22"), 66264.18).
Action-specific ARARs are technology-based or activity-based requirements or
limitations on actions taken to handle hazardous wastes. They are triggered by the particular
remedial activities selected to accomplish a remedy.
Selection of a landfill remedy triggers a number of action-specific ARARs which
govern design, construction, and operation and maintenance of the landfill. The landfill must
meet specified design standards for the liner system, the leachate collection and removal
systems, leak detection systems and the final cover. In addition, the State regulations require
that the foundation be placed on a foundation or base capable of providing adequate support
to prevent liner failure. ARARs also address construction of a run-on control and run-off
management system, management of a collection and holding facilities for such systems,
control of any wind dispersal of particulate matter from the landfill and preparation of a post-
closure plan. In addition, U.S. EPA 1987 Technical Guidance on Bottom Liners and U.S.
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Citation
Chemical Specific
none
Location Specific
40 CFR 264.18 as implemented through
California EPA, Department of Toxic
Substances Control, Hazardous Waste
Regulations, Title 22, Chapter 14 ("Title
22"), 66264.18.
Action Specific
40 CFR 264.301 (c) as implemented through
Title 22, 66264.301 (c)
Title 22, 66264.301 (a)(1)(B)
40 CFR 264.301 (g)-(i) as implemented
through Title 22, 66264.301 (g)-(i)
40 CFR 264.303(a) as implemented through
Title 22, 66264.303(a)
40 CFR 264.31 0(a) as implemented through
Title 22, 66264.310(a)
40 CFR 264.14 as implemented through
Title 22, 66264.14
40 CFR 264.15 as implemented through
Title 22, 66264.15
Requirement
Requires that new facilities not be located
within 61 meters of a fault which has been
displaced in Holocene time. In addition, a
landfill located in a floodplain must be
designed, constructed, operated and
maintained to prevent washout by a 100
year flood or must otherwise meet
standards designed to withstand such a
flood.
Design standards for the liner system, the
leachate collection and removal systems,
and leak detection systems.
Requires foundation to be placed on a
foundation or base capable of providing
adequate support to prevent liner failure.
Construction of a run-on control and run-off
management system, management of a
collection and holding facilities for such
systems and control of any wind dispersal
of particulate matter from the land fill.
During construction, the landfill liner must
be inspected to insure that it meets the
standards.
Requirements for the design and
construction of the landfill cover.
Maintaining security during placement of
contaminated soil and debris in the landfill.
General requirements for inspection of the
landfill during placement of contaminated
soil and debris.
Table 10-1. Applicable or Relevant and Appropriate Requirements
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Citation
Action Specific (con't)
40 CFR 264.314 and 264.316 as
implemented through Title 22, 66264.314
and 66264.316.
40 CFR 264.117 as implemented through
Title 22, 66264.117.
40 CFR 264.118 as implemented through
Title 22, 66264.118
40 CFR 264.91 (a), 264.94, 264.97 and
264.98 as implemented through Title 22,
66264.91 (a), 66264.94, 66264.97 and
66264.98
40 CFR 264.303(b)as implemented through
Title 22, 66264.303(b)
40 CFR 264.552 as implemented through
Title 22, 66264.552
Butte County Air Pollution Control District
Rules 201, 202, 203, & 207
40 CFR 6.302(a) and Appendix A;
Executive Order 11990
Requirement
Requirements for management of liquids
and containers in the landfill.
Requirements for post-closure maintenance
and care of the landfill.
Requires written post-closure plan.
Requirements for detection and evaluation
monitoring, including monitoring of soil pore
liquids, to assure that the landfill does not
release any contaminants to groundwater.
Requirements for inspections during the
time when placement of contaminated soil
and debris in a landfill is occurring.
Requirements for designating and
managing CAM Us.
Requirements regarding nuisance
conditions, emissions & fugitive dust
Requirements to avoid or mitigate impacts
to wetlands.
Table 10-1 (con't). Applicable or Relevant and Appropriate Requirements
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EPA 1989 Technical Guidance on Covers will be considered in the design and construction of
the landfill.
During construction, the landfill liner must be inspected to insure that it meets the
standards set forth in federal and state standards. ARARs also require maintaining security
from the time that contaminated material is first placed in the landfill until the cover is in
place. Finally, there are ARARs for disposal of liquids and containers in the landfill. Soil
remediation work must also comply with emission limits and monitoring requirements issued
by the Butte County Air Pollution Control District.
Upon completion and closure of the landfill, there are ARARs addressing maintenance
and care of the landfill, detection and evaluation monitoring (including monitoring of soil
pore liquids) to assure that the landfill does not release any contaminants to groundwater, and
periodic inspections.
As discussed above, this amendment to the ROD designates the landfill as a CAMU
pursuant to 40 CFR 552. As a consequence, the K001 waste from the creosote pond may be
placed in the landfill without violating any Land Disposal Restrictions (LDRs) that might
otherwise apply to such waste. The remainder of the waste is classified under the wood
treater listings as F032, F034 and/or F035 waste. LDRs have not been promulgated for such
wastes as of the date of this ROD amendment. The selected remedy complies with the
ARARs set forth in 40 CFR 552(e).
The Koppers fire pond and its surroundings are a "wet riparian habitat," and the
excavation of contaminated soil must comply with federal policies and requirements to avoid,
repair or replace impacts to wetlands.
10.3 Cost -Effectiveness
Cost-effectiveness is determined by evaluating three of the balancing criteria
(long-term effectiveness & permanence; reduction of toxicity, mobility or volume through
treatment; and short-term effectiveness) to determine overall effectiveness. Overall
effectiveness is then compared to cost to ensure that the remedy is cost-effective.
There is not a significant difference in long-term effectiveness among the three
alternatives. The area and depth of soil excavation is the same under each alternative, so the
residual risk from contamination in these areas does not vary. In addition, each alternative
would require an on-site landfill for untreated or partially treated soil and debris. Although
the landfill for the treatment alternatives would be somewhat smaller, the residual risks
associated with long-term management of the landfills would not vary significantly among
alternatives.
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The treatment alternatives rank somewhat higher in terms of permanence because they
would reduce the volume of waste by approximately 40% through treatment and would
provide permanent destruction of organic contaminants in those soils which are treated.
However, the treatment alternatives would still leave a substantial volume (60,000 cubic
yards) of untreated or partially treated soil and debris that would have to be landfilled at the
site.
The treatment alternatives rank lower in terms of short-term effectiveness due to the
risks associated with the increased handling of contaminated soils, the possibility of
inadequately treated stack-gas emissions, and a longer period of implementation. In terms of
overall effectiveness, the benefits of treatment are diminished by the higher short-term risks
and the ultimate need to landfill more than half of the initial waste volume. Given these
considerations, the landfill alternative is comparable in overall effectiveness to incineration
and thermal desorption alternatives.
The estimated total costs of the treatment alternatives ($62.6 to 84.1 million) are at
least four times greater than the selected remedy ($13.9 million), with the difference being in
capital costs (see Table 8-1). In comparison to the other alternatives, the selected remedy
achieves a comparable degree of overall effectiveness at a substantially lower cost and is
therefore the most cost-effective alternative.
10.4 Utilization of Permanent Solutions and Alternative Treatment Technologies (or
Resource Recovery Technologies) to the Maximum Extent Practicable
EPA has determined that the selected remedy represents the maximum extent to which
permanent solutions and treatment technologies can be used in a cost-effective manner for
soils at the Koppers site. Of the alternatives evaluated, EPA has determined that the selected
remedy provides the best balance of tradeoffs in terms of the nine criteria used for remedy
selection. In particular, this remedy represents the best balance among long-term
effectiveness and permanence, reduction of toxicity, mobility or volume through treatment,
implementability, short-term effectiveness, and cost.
While the selected remedy does not result in the destruction of contaminants and
therefore does not offer as high a degree of permanence as the incineration or thermal
desorption alternatives, it is comparable in terms of long-term effectiveness, in part because
all three alternatives rely to some degree on containment within a landfill to prevent exposure
to organic and inorganic contaminants. Because the waste material contains only trace
amounts of solvents and therefore the contaminants are relatively immobile, the landfill
remedy will provide effective containment such that the material can be managed with a high
degree of certainty over the long term. The two treatment alternatives would reduce the
volume of contaminated soil and debris by only 40%, and each would require a similar
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(though somewhat smaller) on-site landfill. As described above, the selected remedy ranks
higher in terms of short-term effectiveness and will require less time to implement (two years)
than either of the treatment alternatives (three and one-half to six years).
The selected remedy ranks highest in terms of implementability, since the technology
has already been used successfully at the site. The two treatment alternatives would require
pilot tests to demonstrate their effectiveness. While no explicit comments on the use of
incineration or thermal desorption were submitted during the public comment period, EPA
expects that, based on the history of this site (i.e., the 1987 explosion and fire in the PCP
treatment process) and experiences at other sites where thermal treatment has been proposed,
there would be significant community opposition to siting such a unit for treating dioxin-
contaminated material.
10.5 Preference for Treatment as a Principle Element
The selected soil remedy uses containment, rather than treatment, to address the threats
posed by contaminated soil and debris. Incineration and thermal desorption, the two
treatment alternatives carried through the detailed analysis, are theoretically capable of
destroying dioxin, although treatability studies would be necessary to demonstrate the
effectiveness of either alternative. As noted above, it is highly unlikely that EPA would be
successful in getting community acceptance of an on-site thermal treatment unit for dioxin-
contaminated soil. In screening treatment alternatives, EPA also considered the possibility of
sending the soil to an off-site commercial incinerator, but the treatment costs for 100,000
cubic yards (i.e., 150,000 tons) of soil are prohibitive. EPA therefore has concluded that
treatment of the total waste volume via incineration or thermal desorption would not be
practicable.
Based on treatability studies at Koppers and other wood treater sites, fixation is an
alternative treatment process that is potentially effective for immobilizing the contaminants in
the soil and could be implemented at the site. Although this technology would result in
further reduction of contaminant mobility, it would not reduce the toxicity of the
contaminants per se, nor would it reduce the volume of contaminated material (in fact, the
volume of treated material would be greater than the original volume). The net result would
be an incremental reduction in mobility (for a waste whose primary contaminant of concern,
dioxin, is relatively immobile to start with) at a cost that is equal to or greater than
landfilling. Placement of the soil and debris in the on-site landfill will be equally effective in
eliminating the threat of direct exposure and reliably reducing mobility. EPA therefore has
concluded that treatment via fixation of the waste would not offer a significant added benefit
to the selected soil remedy.
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Since the vast majority of the total waste volume can be classified as low level threat
waste, for which containment is an appropriate remedy, EPA also considered whether
treatment of only the principal threat wastes (i.e., the former creosote pond sediments) was
practicable. For these sediments, the implementability of on-site thermal treatments is equally
low, and the cost of off-site incineration for the estimated 2,000 cubic yards of this material
would be at least $9 million. EPA therefore has concluded that treatment via incineration or
thermal desorption of this potential principal threat waste would not be practicable.
The limitations of fixation as a treatment option for the pond sediments are similar to
those described above - no reduction in toxicity, an increase in volume of material, and the
minimal benefits of further reducing the mobility of a relatively immobile contaminant.
Again, placement of the pond sediments in the on-site landfill will be equally effective in
eliminating the threat of direct exposure and reliably reducing mobility. EPA has therefore
concluded that treatment via fixation of this potential principal threat waste would not offer a
significant added benefit to the selected soil remedy.
In summary, the selected soil remedy does not satisfy the statutory preference for
treatment; however, the groundwater cleanup underway at this site does continue to use
treatment as a principal element of the remedy.
11.0 DOCUMENTATION OF SIGNIFICANT CHANGES
The Proposed Plan for revising the soil remedy at the Koppers site was released for
public comment in March 1996. EPA's preferred alternative, excavation and disposal in an
on-site landfill based on continued industrial use of the site, was documented in the Plan.
EPA did not receive any written or verbal comments on the Proposed Plan during the public
comment period. In the absence of public comments and/or any new information regarding
remedial alternatives or site characteristics, it was determined that no significant changes to
the remedy, as it was originally identified in the Proposed Plan, were necessary.
The Proposed Plan did not discuss the designation of a CAMU as a common element
among all alternatives, nor was it specified as part of the proposed remedy. However, the use
of a CAMU designation for the landfill area does not materially change the nature of the
remedy. EPA has decided to designate a CAMU in order to facilitate implementation of a
remedy that would otherwise be precluded by a RCRA regulatory impediment.
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III. RESPONSE SUMMARY
1.0 INTRODUCTION
The United States Environmental Protection Agency ("EPA") held a public comment
period from April 2 through May 2, 1996 on EPA's Proposed Plan for revisions to the soil
cleanup remedy at the Koppers Company, Inc. ("Koppers") Superfund Site in Oroville,
California. The purpose of the comment period was to provide interested parties with an
opportunity to comment on the Proposed Plan and related documents prepared since the 1989
Record of Decision for the Koppers site. The Proposed Plan and other documents comprising
the Administrative Record were made available on April 2, 1996.at the Butte County Public
Library in Oroville and at the Meriam Library, California State University at Chico. By April
2, 1996, fact sheets containing EPA's Proposed Plan had been mailed to all interested parties.
Notification of the public comment period was published in the Chico Enterprise-Record
newspaper.
EPA held a public meeting on April 16, 1996 at the Oakdale Heights School in
Oroville, California. At this meeting, EPA representatives described the alternatives
evaluated, presented EPA's preferred alternative and answered questions about the evaluation
of the Koppers site and the remedial alternatives under consideration.
Section 113(k)(2)(B)(iv) of the Comprehensive Environmental Response, Compensa-
tion and Liability Act ("CERCLA") requires that EPA respond to significant comments on the
Proposed Plan.
2.0 SUMMARY OF COMMENTS AND AGENCY RESPONSES
During the April 2 - May 2, 1996 public comment period, EPA did not receive any
verbal or written comments on the Proposed Plan. In a telephone conversation with a City of
Oroville official toward the end of the comment period, EPA's Remedial Project Manager was
told that the City had no objections to EPA's proposed change in the soil remedy.
In December 1995, EPA issued a fact sheet describing its ongoing reevaluation of soil
remedies. This fact sheet, which was mailed to all interested parties, described both the
reconsideration of future land use scenarios for the site and the reevaluation of remedial
alternatives for soils. The results of the bioremediation, soil washing and fixation treatability
studies were discussed in the fact sheet. In addition, incineration, thermal desorption and
landfilling were presented as technologies being considered to replace the unsuccessful
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innovative treatment technologies. The fact sheet encouraged the public to contact EPA with
any comments or ideas regarding the reevaluation of soil cleanup.
Shortly after the fact sheet was issued, EPA's Remedial Project Manager met with
elected officials and staff for both Butte County and the City of Oroville to discuss the
reevaluation of soil remedies and solicit any comments they had on the issue. No specific
concerns were expressed during those meetings, and representatives from the City's planning
department indicated that continued industrial use of the site was consistent with the City's
long-range plans for the area. Two drop-in sessions for the public were also held in Oroville,
and no specific concerns or objections were raised during those lightly-attended sessions.
In a letter dated May 9, 1996, the State of California, through the California
Environmental Protection Agency's Department of Toxic Substances Control (DTSC)
concurred with the proposed remedy on the condition that adequate deed restrictions and
operations and maintenance (O&M) controls (as described in the letter) be included in the
remedy. The selected remedy includes deed restrictions, which will be developed to
incorporate DTSC's requested provisions. EPA will be amending the consent decree with
Beazer to include enforceable O&M requirements for the landfill.
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