PB99-964507
EPA541-R99-094
1999
EPASuperfund
Record of Decision Amendment:
Koppers Company Inc. Site
(Oroville Plant)
Oroville, CA
9/23/1999
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AMENDMENT #2
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
September 23, 1999
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Table of Contents
Section Page
PART 1: THE DECLARATION I
A. Site Name and Location 1
B. Statement of Basis and Purpose 1
C. Assessment of Site 1
D. Description of Selected Remedy 1
• Technical Impracticability Waiver 2
• Enhanced in-situ Bioremediation 3
• Monitored Natural Attenuation As Contingency Remedy 3
E. Statutory Determinations 4
F. Data Certification Checklist 4
G. Authorizing Signature 4
PART 2: THE DECISION SUMMARY 5
A. Site Name, Location, and Brief Description 5
B. Site History of Contamination and Selected Remedy 5
On-Property Groundwater Treatment 9
Off-Property Groundwater Treatment 10
C. Community Participation 10
D. Basis for the ROD Amendment 12
Remedy Change 1) TI Waiver 12
Remedy Change 2) Enhanced in-situ Bioremediation 12
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Section Page
Remedy Change 3) MNA As Contingency Remedy 14
E. Site Characteristics 13
• Source Remediation 13
TIZone 16
• Groundwater 16
F. Current and Potential Future Site and Resource Uses 18
- Land Uses 18
• Groundwater Uses 18
G. Summary of Site Risks 18
Human Health Risks 19
• Ecological Risks 19
H. Remediation Standards 19
• TIZone 20
• Outside the TI Zone 20
I. Description of Alternatives 21
• TI Waiver Alternatives 1 through 6 21
• On-Property Groundwater Alternatives 1 through 3 23
• Off-Property Groundwater Alternatives 1 through 4 23
J. Comparative Analysis of Remedy Alternatives 28
• Overall Protection of Human Health and the Environment 28
TI Waiver • 28
On-Property Groundwater 28
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Section Page
Off-Property Groundwater 28
• Compliance with ARARs 29
TI Waiver 29
On-Propertv 29
Off-Property 29
« Long-Term Effectiveness and Permanence 29
TI Waiver 29
On-Propertv 29
Off-Property 29
Reduction of Toxicity, Mobility and Volume Through Treatment 30
TI Waiver 30
On-Propertv 30
Off-Property 30
Short-Term Effectiveness 30
TI Waiver 30
On-Propertv 31
Off-Property 31
• Implementability 31
TI Waiver 31
On-Property 31
Off-Property 31
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Section Page
• Cost 31
TI Waiver 31
On-Propertv 31
Off-Property 32
• State Acceptance 32
• Community Acceptance 32
K. Selected Remedy 36
" Tl Waiver (Remedy Change On-Property Alternative 6, TI Waiver) 36
* Enhanced in-situ Bioremediation (Selected Remedy On-Property 37
Alternative 2 and Off-Property alternative 3)
• MNA As Contingency Remedy (Selected Contingency Remedy On- 39
Property alternative 2 and Off-Property Alternative^
L. Statutory Determinations 39
• Protection of Human Health and the Environment 40
TI Waiver 40
Enhanced in-situ Bioremediation On and Off-Property 40
MNA As Contingency Remedy 40
* Compliance with ARARs 40
• Waiver of Groundwater Cleanup ARARs 45
" Cost-Effectiveness 45
IT Waiver 45
On-Pronertv Groundwater Remedy Change 46
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Section £»
Off-Property Groundwatcr Remedy Change 46
• Utilization of Permanent Solutions and Alternative Treatment 46
Technologies or Resource Recovery Technologies to the
Maximum Extent Practicable
TI Waiver 46
On-Property Groundwater Remedy Change 46
Off-Propertv Groundwater Remedy Change 47
• Preference for Treatment as a Principle Element 47
TI Waiver 47
On-Propertv Groundwater Remedy Change 47
Off-Propertv Groundwater Remedy Change 47
M. Documentation of Significant Changes from Preferred 47
Alterative of the Proposed Plan
PART 3: RESPONSIVENESS SUMMARY 48
A. Stakeholder Issues and EPA Responses 48
B. Technical and Legal Issues 48
List of Figures
No. Title
2A-1 Site Location
2A-2 PCP Plume Contour Map 7
2A-3 Aquifers Section 8
2E-1 Plan View TI Zone 13
2E-2 Source Removal Areas * 5
2K-1 Flow Chart for EEB and MNA Implementation On and Off- 38
Properly Plumes Koppers ROD amendment #2
-VI-
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List of Tables
No. Title Page
2E-1 1998 Groundwater Sampling Data 17
2H-1 Summary of Groundwater Cleanup (CU) Value Changes 21
21-1 Description of Remedy Change Alternatives 25
21-2 Cost of TI Zone Waiver Alternatives 26
21-3 Cost of On-Property Groundwater Remedial Change Alternatives 26
21-4 Cost of Off-Property Groundwater Remedial Change Alternatives 27
2J-1 Comparison of TT Waiver Alternatives 33
2J-2 Comparison of On-Property Groundwater Remedial Alternatives 34
2J-3 Comparison of Off-Property Groundwater Remedial Alternatives 35
2L-1 ARARs for Groundwater ROD Amendment 42
2L-2 Cleanup Standard for Chemicals of Concern Outside the TI Zone 44
-VII-
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PART 1: THE DECLARATION
A. Site Name and Location
Koppers Company, Inc.
Oroville, California
B. Statement of Basis and Purpose
This decision document presents the U.S. Environmental Protection Agency's (EPA's)
amended selected remedial actions for contaminated groundwater at the Koppers Company, Inc.
(Koppers) site in Oroville, California, which were chosen in accordance with the Comprehensive
Environmental Response, Compensation and Liability Act (CERCLA), as amended by the
Superfund Amendments and Reauthorization Act (SARA), and 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 amendments to the remedy.
C. Assessment of Site
Actual or threatened releases of hazardous substances from this site, if not addressed by
implementing the response action selected in the Record of Decision (ROD), as modified by this
ROD Amendment, may present an imminent and substantial endangerment to public health,
welfare, or the environment.
D. Description of Selected Remedy
This ROD Amendment modifies the. previously selected remedy for contaminated
groundwater at the Koppers site. The revision affects both the cleanup standards and the cleanup
technologies selected in the 1989 ROD for the site's single operable unit. This ROD
Amendment does not affect the soils remedy selected in the August 1996 ROD Amendment.
The 1989 ROD specified Pump and Treat (P&T) as the groundwater remedy and a P&T facility
was installed both on and off-property to achieve groundwater restoration for drinking water use.
Amendment #2 to the ROD provides for 1) a Technical Impracticability (TI) Waiver due
to Dense Nonaqueous-Phase Liquid (DNAPL) contamination, 2) adding enhanced in-situ
bioremediation to the remedy to augment pentachlorophenol (PCP) destruction, and 3) adding
Monitored Natural Attenuation (MNA) as a contingency remedy should enhanced in-situ
bioremedialion nutrient distribution not be fully achieved in the aquifers. The major components
of the revised groundwater remedy are. as follows:
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• Technical Impracticability Waiver
The nature and extent of DNAPL impacts at the Koppers site are better understood now
than they were when the Remedial Investigation/Feasibility Study (RI/FS) was completed. The
factual presentation providing the basis for a TI Waiver is documented in the "Final Evaluation
of Technical Impracticability of Groundwater Restoration in the Former Creosote Pond and
CELLON BLOWDOWN Areas submittal dated March 8, 1999, which will be referred to as TI
Evaluation Reference "A". The described four-acre area of the 200-acre site composed of the
former creosote pond area and CELLON BLOWDOWN area will be referred to as the TI Zone.
Based on TI Evaluation Reference "A" and site monitoring data, the EPA has concluded that the
existing P&T remedy and/or presently available technology will not restore the aquifer within the
TI Zone to meet the groundwater cleanup standards of the 1989 ROD even though surface and
near surface source material have been removed. The principal threat wastes to groundwater in
the TI Zone are polychlorinated dibenzo-p-dixoins/dibenzofurans (PCDDs/PCDFs) which will be
referred to as dioxin, and high concentration carcinogenic and non-carcinogenic Polynuclear
Aromatic Hydrocarbons (cPAH & PAH) all present in DNAPL. The low-level threat waste in
the TI Zone DNAPL is pentachlorophenol (PCP). This ROD amendment documents a waiver of
the groundwater cleanup standards for the TI Zone based on the EPA's conclusion that it is
technically impracticable from an engineering perspective, to achieve the groundwater cleanup
standards in the TI Zone. The major components of the TI Waiver are as follows:
• sampling of monitoring wells for Contaminants of Concern (COC) both within the TI
Zone and down-gradient;
• installation of one new monitoring well down-gradient of the TI Zone;
• develop an acceptable contingency plan to maintain the P&T facility and resume its
operation if the EPA determines that a contaminant is leaving theTI Zone;
• implementation of institutional controls through land use covenant deed restrictions to
prevent exposure to contamination remaining in the TI Zone, to prohibit drilling of
wells within the TI Zone for purposes other than monitoring or remedial activities, to
prohibit use of groundwater within the TI Zone except for wood-treating operations,
and to limit future land use to industrial; and
• continued operation of the existing Product Recovery well (PR-1) and the PAH in-situ
groundwater bioremediation well (BW-l) until creosote recovery is less than one
gallon per year at PR-1.
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• Enhanced in-situ Bioremediation
Based on general PCP wood treating site data and site specific data, the EPA has
concluded that the restoration of groundwater for use as a public drinking water supply outside
the TI Zone could be expedited significantly if enhanced in-situ bioremediation were added to the
remedy to remediate PCP both on and off-property. Off-property the only COC is low-level
threat waste PCP. On-property and outside the TI Zone, the COC above the groundwater cleanup
standards are low-level threat wastes boron and PCP. The major components of the enhanced in-
situ bioremediation are as follow:
• nutrient addition (primarily oxygen, nitrogen and phosphorus) to existing wells on
and off-property to provide optimum conditions for PCP degradation, in conjunction
with monitoring down-gradient;
• continued operation of the existing on-property P&T to restore groundwater outside
the TI Zone and prevent contaminate migration off-property;
• annual evaluation and adjustment, as needed, to enhance bioremediation;
• due to nutrient addition to monitoring well RI-11 the alternative water supply
termination criteria (AWSTC) for water supply wells 59, 60, 61, 62 and 81 .is
modified as follows: 1) verification sampling for PCP to end the subsidy cannot be
conducted until nutrient addition in the area of these wells has been terminated and
nutrient levels have returned to background levels for at least one year and 2) to end
the subsidy for each individual drinking water well the PCP level must be less than
0.5 ppb for four consecutive quarters.
If the EPA determines enhanced in-situ bioremediation will not achieve cleanup standards
or that migration of a contaminant is occurring, the EPA will select appropriate contingency
action in accordance with remedies available in the ROD.
• Monitored Natural Attenuation As Contingency Remedy
Site data has shown that PCP degradation occurs naturally both on and off-property.
Provision is made for implementing MNA as a contingency remedy outside the TI Zone if the
EPA determines that 1) enhanced in-situ bioremediation nutrient distribution cannot be
adequately achieved, 2) other active restoration measures are not necessary, 3) site conditions
continue to demonstrate that PCP degradation is occurring, and 4) natural attenuation is expected
to achieve cleanup levels within a reasonable time frame achievable by a treatment remedy.
Groundwater monitoring data will be submitted to the EPA for review until cleanup standards are
achieved in accordance with an approved monitoring plan. If the EPA determines MNA will not
achieve cleanup standards ordinal migration of a contaminant is occurring, the EPA will select
appropriate contingency action in accordance with remedies available in the ROD.
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E. Statutory Determinations
The selected remedy is protective of human health and the environment, complies with
the requirements of CERCLA Section 121 for a waiver of federal and State requirements in the
TI Zone that are legally applicable or relevant and appropriate, complies with the federal and
State Applicable or Relevant and Appropriate Requirements (ARARs) that are not subject to the
waiver (the groundwater outside the TI Zone) and is cost-effective. This remedy utilizes
permanent solutions and alternative treatment technologies to the maximum extent practical for
this site. The revised groundwater remedies utilize both containment and treatment technologies
to reduce toxicity, mobility, or volume of contaminants. However, because treatment of the
DNAPL in the TI Zone was not found to be practicable, this remedy does not satisfy the statutory
preference for treatment as a principal element of the remedy for groundwater in the TI Zone.
Because the TI Waiver will result in hazardous substances remaining on-site above
health-based levels, the EPA will conduct a review pursuant to Section 121 (c) of CERCLA, 42
U.S.C. 962 l(c), within five years of commencement of this amended remedial action to insure
that the remedy continues to provide adequate protection of human health and the environment.
F. Data Certification Checklist
The Declaration certifies that the following information is included in the ROD amendment:
• COC and their respective concentrations;
• baseline risk represented by the COC;
• cleanup levels established for the COC and the basis for these levels;
• how source materials constituting principal threats are addressed;
• current groundwater use assumptions used in the baseline risk assessment and ROD;
• potential groundwater use that will be available at the site as a result of the Selected Remedy;
• estimated capital, operating and maintenance (O&M), and total present worth; discount rate;
and the number of years over which the remedy cost estimates is projected; and
• key factor(s) that led to selecting the remedy.
G. Authorizing Signature
7a(6a
Date Keith Takata
Director, Superfund Division
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PART 2: THE DECISION SUMMARY
A. Site Name, Location, and Brief Description
The Koppers Company Superfund site is located in Butte County just south of the city
limits of Oroville, California (see Figure 2A-1). The site's Comprehensive Environmental
Response, Compensation and Liability Information System (CERCLIS) identification number is
CAD009112087. The lead-agency for the site is the EPA. The site type is an active industrial
wood treating facility with groundwater contamination on property and extending to the south of
property (see Figure 2A-2). The Koppers plant lies in the flood plain 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 Corporation facility,
which has been removed from the National Priority List (NPL) as a Superfund site.
Land use in the vicinity of the site is mixed industrial, commercial, agricultural and
residential. Residential areas are outside a buffer of industrial and commercial areas directly
adjacent to the site. 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 dredge mining operations. Interconnecting
aquifer zones A, B-Upper, B-Lower and C have been identified on and off-site (see Figure 2A-3).
The regional groundwater flow is generally to the south.
B. Site History of Contamination and Selected Remedy
Hutchinson Lumber Mill owned the Oroville, California property prior to 1948. In 1948,
the National Wood Treating Corporation acquired the property and began wood treating
operations. Georgia-Pacific acquired the site in 1951, and Koppers Co., Inc. acquired the site
from Georgia-Pacific in 1955. Beazer East, Inc. (BEI) purchased Koppers Co., Inc. between June
and November 1988. In December 1988, BEI subsequently sold the assets of its Tar and Treated
Wood Sector, including the Oroville, California plant operations and property, to a management
buy-out group known as Koppers Industries, Inc. (KIT). Kn continues to operate the plant today,
however, BEI retained responsibility for the environmental cleanup issues at the site.
The Koppers facility encompasses approximately 200 acres and has been used for wood
treating operations since 1948. Historically, wood poles and ties have been pressure treated with
PCP, creosote, and inorganic formulations, including chromium and arsenic. Soil and
groundwater contamination at the site have resulted from both past wood treatment operations
and related waste disposal practices. A fire occurred in the CELLON process area in 1963 and
again in 1987. The State identified the Koppers site as an environmental problem during the
early 1970's when constituents associated with wood treatment activities were identified at the
site in soils and groundwater. The site was placed on the NPL in 1984. Koppers began the
Remedial Investigation (RI) in April 1986 and submitted the RI in July 1988. Use of PCP was
discontinued at the site in 1988. In November 1988, the EPA completed the Endangcrment
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0 40 80
=*-
APfflOXUlATE 6CM£ M MLES
SITESLOGATIQN
Kopp«f* Company, he.
Supcrtuid S««
REFERENCE OSGS T.ff Qu»*8f«te. Patemw. (X, 1980.
STIE LOCATION
FIGURE 2A-1 - SITE LOCATION
KOPPERS CO.. INC. SUPERFUNO SfTE
FEATHER RIVER PIANT
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0 600 1200
Scale in Feet
EXPLANATION
• - Domestic Wefc
•& • Industrial Wete.
^ - Mor*oring.^e*?and Remedial
Investigation Wens
• -Extraction and Injection Wens
R -Unused Wens
c,"_^'> - Property Boundary
^y> - PCP Concentration (ug/l) in
Groundwaler Nov.. Dec. 1998
Palermo Road • s
RGURE 2A-2 - PCP PLUME CONTOUR MAP
NOVJOEC. 1998 DATA
KOPPERS CO., INC. SUPERFUNO SITE
FEATHER RIVER PLANT
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A-B Aquitard
BU-BL Aquitard
B-C Aquitard
Explanation
Sill and Cloy
Sond and Silt
Gravels
Static Water Level
Figure Based on: Dames tf. Moore. 100% Design Report Initial
Phase On—Property Groundwater Remediation
System. July 1993
M
FIGURE 2A-3 - AQUIFERS SECTION
KOPPERS CO.. INC. SUPERFUND SITE
FEATHER RIVER PLANT
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Assessment (EA). In May 1989, a Feasibility Study (FS) was conducted to evaluate a wide
range of soil and groundwater cleanup alternatives.
In September 1989, the EPA issued a ROD for the site. The groundwater remedy
specified to restore groundwater to drinking water standards was pump and treat. In January
1991, the EPA issued an Explanation of Significant Difference (BSD) to clarify the ROD. The
ESD specified that the existing remedial objectives for soil remain in effect for surface soils
down to a depth of five (5) feet below ground surface and included institutional control actions as
part of the remedy for soil and groundwater. Under the EPA's oversight, BEI is currently
performing the cleanup work under the terms of a Consent Decree, signed in February 1992. BEI
began design work for the groundwater remedy in 1990 and started construction of the first
groundwater treatment plant in late 1992.
In 1996, the EPA issued ROD Amendment #1 modifying and clarifying certain features
of the 1989 ROD. The site cleanup standard was changed from residential use to industrial. With
the change in land use the soil remedy was changed to place contaminated soil in a second on-
site landfill with a capacity of 145,000 cubic yards. With the exception of an estimated 20,000
cubic yards of soil in the process area, the soil remedy is complete. The 1996 ROD allows the
remaining contaminated soil to remain until either the process equipment is replaced or wood
treating ceases. The EPA has no forecast date for Koppers replacement of their process
equipment or a date when wood treating operation will cease at the site to allow completion of
the soil remedy.
On-Property Groundwater Treatment
The on-property P&T system was designed to prevent contaminated groundwater from
flowing off the Koppers site by pumping groundwater from beneath the Koppers site, treating the
water to the cleanup standards established by the EPA in the 1989 ROD and returning the water
to the groundwater basin. In February 1994, a four hundred (400) gallons per minute (g.p.m.) on-
property P&T system began operation and continues to operate today. The monitoring data for
• wells RI-20A and RI-20B confirm that the on-property P&T system is effectively capturing the
on-property contamination plume. The P&T system prevents further contaminated groundwater
from migrating south of the Koppers facility to feed the off-property plume. Due to the efforts of
the P&T system, the original plume has separated into two plumes designated on-property and
off-property. The PCP levels, the major COC, entering the P&T system have significantly
reduced from 350 parts per billion (ppb) in February 1994 to approximately 35 ppb to date. The
EPA expects groundwater contamination to continue to decrease based on the soil remediation
conducted in 1996 and 1997.
A product recovery well (PR-1) was installed in September 1994 on-property at the
former creosote pond area to assist in creosote recovery. In July 1995, BEI installed a pilot in-
situ groundwaler biolreatment system to aid in creosote degradation near PR-1. In a little more
than four years of operation, the on-property product recovery well PR-1 has removed
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approximately 160 gallons of creosote and an additional 220 gallons of creosote emulsion of a
potential available one million gallons of free creosote beneath the former creosote pond. The
three and half year pilot PAH in-situ groundwater biotreatment sample data have not
conclusively shown that adjustments of the subsurface conditions near the on-property injection
well BW-1 has enhanced the deterioration of the mobile PAHs in creosote. A pilot enhanced
bioremediation program for on-property groundwater was initiated March 6, 1998 for PCP
degradation.
Off-Property Groundwater Treatment
In March 1993, a six hundred (600) g.p.m. off-property P&T system began operation.
The off-property P&T system was designed to remove and treat the contaminated groundwater
plume that migrated off Koppers' plant property. The groundwater was pumped from two
extraction wells (E-3 & E-4), located near the intersection of Prince Road and Horny Toad Road.
From these extraction wells, the contaminated water flowed to the off-property P&T system and
was filtered through two carbon filters in series. The treated water was then remjected back into
the groundwater basin up-gradient (North) of the extraction wells. The off-property P&T system
prevented the plume from moving farther south and helped to shrink the plume to the vicinity of
monitoring well RI-11. The southern edge of the off-property plume is currently located
approximately half a mile up-gradient from the off-property P&T system extraction wells EW-3
and EW-4. In December 1995, the P&T system was taken off-line (held in reserve) because the
system achieved the cleanup standards within its zone of capture at extraction wells EW-3 and
EW-4 and was unable to affect the up-gradient residual plume. Since December 1995, these two
extraction wells have remained within the cleanup standard. Monitoring wells RI-2 and RI-3 are
located within the heart of the remaining residual off-property groundwater plume. Since
November 1994, RI-2 and RI-3 monitoring well data has been relatively stable, with
concentrations in the range of 15 to 65 parts per billion (ppb) for PCP. Monitoring and sampling
data have shown that twenty-six (26) of the thirty-four (34) private drinking water wells, which
had a potential impact to public health, are no longer contaminated by PCP. The residents of
these twenty-six (26) private drinking water wells no long require an alternative drinking water
supply. The remaining eight (8) private drinking"water wells will undergo further review and
evaluation. Until the eight (8) remaining private drinking water wells are verified to have
reached the cleanup criteria, these eight (8) well owners will continue to be provided with an
alternative drinking water supply and receive reimbursement for water use based on a computed
average usage rate. A pilot enhanced bioremediation program for off-property groundwater was
initiated August 26, 1998 for PCP degradation.
C. 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. Since the Consent Decree in 1991, a fact sheet has been issued to the public
annually to address key progress points in the investigation and cleanup of the site.
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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.
In preparation for developing the proposed plan for this ROD Amendment, a phone
survey of more than 50% of replacement water supply recipients was conducted in December
1998. The survey solicited comments on the August 1998 groundwater progress fact sheet and
pending groundwater remedy changes.
The 1989 ROD and both ROD Amendments for the site have met the criteria specified in
CERCLA Sections 113(k)(2)(B)(i through v) and 117(a)(l & 2) through establishing and
maintaining an administrative record; public notification and distribution of a proposed plan for
public comment; and holding of a public meeting and addressing comments. Specifically for this
proposed ROD Amendment #2, a proposed plan was issued in March 9, 1999 and public
comment sought from March 15 through April 13, 1999. Public notice appeared in two local
newspapers prior to the start of the public comment period. A formal public meeting was held
March 23, 1999 and no comments against the proposed plan were presented. Media attendance
at the public meeting included KHSL-TV, Enterprise Record and News and Review which
provided TV and newspaper coverage of the event. A transcript of the meeting can be found in
the administrative record for the site which resides at the following three locations:
Oroville Butte County Public Library California State University Superfund Records Center
180 Mitchell Ave Meriam Library 95 Hawthorne Street
Oroville, CA 95966 400 West first Street San Francisco, CA 95104
Chico, CA 95929
Two written comments were submitted during the public comment period; however, they
did not offer comment on the proposed groundwater remedy changes. The EPA replied to the
written comments by letter providing appropriate federal and State contacts. The EPA also
provided copies of the letters and the EPA's response to the Agency for Toxic Substances and
Disease Registry and the California Department of Health Services.
Public input on reasonably anticipated future land use was sought as part of ROD 1996
Amendment #1 when the site cleanup standards were changed to industrial and deed restrictions
required to prohibit future residential development. Public input was again sought in 1999 for
site deed restrictions and industrial use. No opposition to deed restrictions or continued
industrial use of the land has been posed.
Public input on potential future groundwater use was sought as part of this ROD
Amendment #2. No opposition was presented to amending the ROD for a TI Waiver in which
groundwater would not be restored to public drinking standards in the four-acre TI Zone.
Page 11 of 48
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D. Basis for the ROD Amendment
The three selected groundwater remedial changes address groundwater contamination as
part of the single operahle unit for the Koppers site. The 1989 ROD specified P&T as the only
groundwater remedy to restore groundwater to drinking water use. Amendment #2 revises the
groundwater remedy selected in the 1989 Operable Unit Record of Decision to 1) provide a TI
Waiver for groundwater ARARs at the former creosote pond and CELLON BLOWDOWN areas
due to DNAPL contamination, 2) add enhanced in-situ bioremediation to the remedy to augment
PCP remediation and 3) add Monitored Natural Attenuation (MNA) as a contingency remedy
should enhanced in-situ bioremediation nutrient distribution not be fully achieved in the aquifers.
The planned sequence of actions is to implement enhanced in-situ bioremediation on and off-
property and to develop deed restriction language for the TI Zone. The EPA will review the
contingency remedy option if it determines that enhanced in-situ bioremediation is not fully
effective.
The revision to the groundwater remedy is supported by the following information:
Remedial Change 1) TI Waiver
Data defining the extent of creosote DNAPL contamination was collected as part of the
RI, but the FS did not address how ARARs would be met in areas containing free residual and
emulsified DNAPL. The former creosote pond and adjacent CELLON BLOWDOWN areas have
had the surface and near-surface soil contamination removed; however, DNAPL contamination
remains beneath and slightly down gradient, affecting approximately four acres of the 200-acre
Koppers plant to a depth of 125 and possibly 250 feet below ground surface (see Figure 2E-1).
The creosote DNAPL is composed of PAHs that make up the creosote and some cosolved PCP.
Dioxin (PCDDs/PCDFs) also exists in the DNAPL as an impurity contained within the cosolved
PCP. TI Evaluation Reference "A" provides detail on past remediation efforts and studies,
DNAPL extent and appropriateness of the TI Waiver. Residual saturation will result in high
concentrations of creosote persisting in soil and groundwater even though the DNAPL is no
longer present in a mobile phase. The low solubility and slow dissolution rates of creosote
DNAPL will persist indefinitely until a technology is developed that will remove all the DNAPL.
Remedial technology is not available at this time to restore the aquifer within the TI Zone to
drinking water standards, therefore, EPA has concluded that a TI Waiver is appropriate.
Remedial Change 2) Enhanced in-situ Bioremediation
The 1989 ROD required the groundwater restoration using P&T as the groundwater
remedy. Based on wood treating site data and site specific data, the EPA has concluded that
groundwater restoration for use as a public drinking water supply could be expedited
significantly if enhanced in-situ bioremediation were added to the remedy to remediate PCP.
On-property enhanced in-situ bioremediation would be initiated to enhance the existing P&Tr
destruction of PCP and potentially reduce the on-property P&T operation time from 30 to 20
years. Off-property the PCP plume is no longer connected to the on-property plume due to the
Page 12 of 48
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Soil Disposal Cell
No
Soil Disposal Cell
No. 1
\
Former Creosote
Pond Area
Former Cellon
Slowdown Area
I —
"•-••-_ .;:r----.. I Washer Area
__ „ '-=-^^:' -/.. • . :-,',V" 4
^ - • % ~-~..m-f-:-- '• '.' (L.
— • — Property Boundary
Qr TIZone
Scale: 1 "=6OO'
Monitoring, test, and Remedial Investgation Wells
Domestic Wells
Extraction and Injection Wells
FIGURE 2E-I - PLAN VIEW Tl ZONE
KOPPERS CO.. INC. SUPERFUNO SUE
FEATHER RIVER PIANT
Page 13 of 48
-------
effectiveness of the on-property P&T facility and the PCP plume has retreated almost half a mile
up-gradient from the off-property P&T extraction wells. The off-property P&T facility was
placed on standby in December 1995 and the extraction wells have remained PCP free to date.
Monitoring data for the residual off-property PCP plume indicates the overall plume size and
location has changed little since 1997. By adding enhanced in-situ bioremediation as a remedy,
active remediation of the off-property PCP plume could occur faster and more cost effectively
than installing new extraction and reinjection wells and piping to the existing off-property P&T
facility.
Remedy Change 3) MNA As Contingency Remedy
Site data has shown that PCP degradation occurs naturally both on and off-property.
Provision is made for implementing MNA as a contingency remedy outside the TI Zone if EPA
determines that 1) enhanced in-situ bioremediation nutrient distribution cannot be adequately
achieved, 2) other active restoration measures are not necessary, 3) conditions off-property
continue to demonstrate that PCP degradation is occurring and 4) natural attenuation is expected
to achieve cleanup levels within a reasonable time frame achievable by a treatment remedy.
E. Site Characteristics
The 1989 ROD provided detailed information on the site characteristics for both soil and
groundwater from the RL The 1996 ROD Amendment #1 updated site data based on RD/RA for
soils. The Site Characteristics provided under this section will address post ROD groundwater
RD/RA data supporting changes to the groundwater remedy contained in the 1989 ROD and
completed source area remedial actions for the site since ROD Amendment #1.
• Source Remediation - In 1996 and 1997 107,000 cubic yards of surface and near surface soils
were excavated and placed in an on-property Corrective Management Unit (CMU) Cell#2 (see
Figure 2E-2). The excavation completed the site soil remediation except for an estimated
20,000 cubic yards of contaminated soil remaining below the process area, designated Area
8c, which is covered by concrete foundations, asphalt roadways or chip seal. The process area
cover is inspected annually. The 1989 ROD allows the process area contamination to remain
in place until process area equipment is replaced or wood treating operations cease. Due to
limited sampling data at the processing area, it is possible that some dioxin exceeding the 10"3
risk level (principle threat waste) may reside in soil under the process area. Low-level threat
waste soil contaminants of concern placed in Cell #2 included PCP, PAHs, Arsenic and
Chromium. Soil excavation below 5 feet occurred at the following areas and depths:
Area 4 - Former Creosote Pond excavated to a depth of approximately 13 feet below ground
surface (bgs.)
Area 4 - Former CELLON SLOWDOWN area excavated to a depth of up to 10 feet bgs.
Area 5 - Former Pole Washer area excavated to a depth of up to 18 feet bgs.
Cell #2 source removal effort documentation is contained in the Construction Documentation
and Closure Report for Cell #2 and Associated Soil Removal Activities dated December 1998,
which will be referred to as Reference "B".
Page 14 of 48
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«!%«»•
N 14.HO.
\ ,
Nil 1011
EXISTING (OIL DISPOSAL CELL NO. 1
REMOVAL ACTION 1995
1S.OOO CUBIC YARDS
EXISTING SOIL DISPOSAL CELL NO. 2
107.000 CUBIC YDS. REMEDIAL ACTION 1886 S 1997
107.000 CUBIC YDS. VS. CELL CAPACITY
149,000 CUBIC YDS.
ESTIMATED VOLUME REMAINING
AREA «c 20,000 CUBIC YDS.
POTENTIAL SITE OF ADDITIONAL LANDFILL CELL
\
\
\
>' ^ ...\
I ^ /,. c©,r"--x
f". / ^ y'JI'v' "'-'''
T 8 '5 ! ! S S 8
f t '
"©//
»
I
t
I
Kopptrm Co., Inc. Sit* Boundary
Approximate »r*» of soil rtmoval
Soil dlspotal cell*
Potential iHe of futur* landfill eill
8C - rttnalnlng soil area to b«
remediated
SYMBOL
1
3
4
6a,b
8a,b.c.d
9
10
AREA IDENTIFICATION VOLUME BY TRUCK APPROXIMATE TIE TO
CUBIC YARDS 89 ROD SOIL UMITS
FORMER BIOLOGICAL
TREATMENT FACILITY
SOIL STORAGE BUILDING
FIRE DEBRIS STORAGE AREA
FORMER CREOSOTE POND *
CELLON SLOWDOWN AREA
;ORMER POLE WASHER AREA
FORMER DRIP TRACKAREAS
FORMER LOG DRYING AREAS
FORMER PROCESS AREAS
FIRE WATER POND
FORMER BIOLOGICAL TEST PLOTS
TOTAL
21,000
600
20,500
4,830
15,200
10.200
3.600
1,800
109,130
•
S-2
S-1
S-1=6a&S-3=6b
S1 »7b.c,d.» & S-2«7a
S-1=8a, S-2«8b, S-3»8e & S4«8d
S2
- 3urv«Y«d volum* • 107,000
400
800
Seals In Feet
FIGURE 2E-2 -SOURCE REMOVAL AREAS
KOPPERS CO., INC. SUPERFUND SITE
FEATHER FIVER PLANT
Page 15 of 48
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TlZone - The TI Zone consists of approximately four acres covering the former creosote pond
area and CELLON SLOWDOWN area described in TI Evaluation Reference "A"(see Figure
2E-2). Groundwater in the TI Zone is approximately 30 bgs. with a hydraulic gradient of from
0.001 to 0.004 ft./ft. and a ground water flow velocity of approximately of 500 feet per year
toward the south. Groundwater aquifers at the Site have been separated into A, B, and C zone
aquifers with A zone above the water table on-property (see Figure 2A-3). The B zone is also
divided into upper and lower B zones. Aquifer pumping tests and groundwater remediation
pumping have demonstrated that, on a site-wide basis, the upper B, lower B and C zone
aquifers are hydraulically connected. Within the TI Zone, however, the upper and lower B
zone aquifers may be separated by a thick clay zone. Principal threat wastes in the TI Zone
are high level dioxin, cPAH and PAHs which exist in the creosote DNAPL and cosolved PCP
and do not exist outside the TI Zone. The DNAPL resides on three clay layers in the TI Zone
(see Figure 2A-2). The pore volume of the aquifer is estimated at approximately 67 million
gallons. From RI data the area containing free creosote (exceeding residual saturation) is
estimated at approximately 60,000 square feet or 1.4 acres. As much as 336,600 gallons of
free creosote may be present at the base of each of the upper B, lower B and C aquifer clay
layers for a total estimated free creosote of 1,009,800 gallons. The only ROD COC that have
been detected directly down-gradient from the TI Zone are boron and potentially the non-
carcinogenic PAH (pyrene). In the TI Zone from the December 1998 sampling, PCP ranged
from 0.8 to 1,200 ppb; and total PAHs ranged from no detection to 6,980 ppb for total cPAHs
and from no detection to 745,000 ppb for total non-carcinogenic PAHs.
Groundwater - Groundwater wells were installed to cover the extent of contamination both on
and off-property and contaminant plume contours are drawn from the monitoring data taken at
these wells. Individual well sampling frequency varies from quarterly to biennially depending
on the well COC history. Groundwater data is collected quarterly and semiannual reports
evaluate the data. Figure 2A-2 shows the extent of groundwater contamination on and off-
property for PCP based on a 2.2 ppb contour line for the B aquifer from the Annual 1998
Remedial Action Groundwater Monitoring Report dated April 13, 1999, which will be
referred to as 98 Groundwater Report Reference "C". Table 2E-1 provides on and off-
property COC detection frequency with low to high range of readings tabulated from the
Annual 1998 Groundwater Report Reference "C". PCP is the only off-property COC and
contaminates the B aquifer. Off-property the PCP plume has contracted resulting in a
shutdown of the off-property P&T and the plume has been relatively stable over the past few
years. On-property outside the TI Zone boron, PCP, and PAH as pyrene are the only COC
delected in the B aquifer (On-property the A aquifer is above the groundwater table). Pyrene
was detected in a single well outside the TI Zone in the last sampling round documented in the
Annual 1998 Groundwater Report Reference "C". The on-property P&T has been effective in
containing contaminants on-property, preventing contaminants from feeding the off-property
contamination, creating two distinct plumes from what was originally a single long plume.
Page 16 of 48
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Table 2E-1 1998 Groundwater Sampling Data
1 "— •
Chemical
Off-Propertv
Pentachlorophenol
On-Property
Pentachlorophenol
Isopropyl Ether
Barium
Boron
Arsenic
Chromium
Copper
Mercury -
II Benzene
Ethyl benzene
Total Xylenes
Total PAHs
Total cPAHs
Toxic Equiv. 2,3,7,8-
TCDD (dioxin)
Detection Frequency
8/34
23/31
2/4
7/7
22/22
0/7
0/9
0/7
0/4
3/12
3/12
3/12
5/16**
5/16***
1/1
Lowest Reading
Not detected (ND)
ND
26 ppb
38 ppb
427 ppb
ND
ND
ND
ND
ND
ND
ND
ND
ND
1 22,296 ppq
(inside the TI Zone)
Highest Reading
64 ppb
1,200 ppb
89 ppb
170 ppb
3,890 ppb
ND I
ND ||
ND |
ND 1
9 ppb* |
54 ppb 1
270 ppb §
745,000 ppb
6980ppb
-
PAH = Polynuclear Aromatic Hydrocarbon
cPAH = Carcinogenic Polynuclear Aromatic Hydrocarbon
TCDD = Dioxin (Tetrachlorodibenzo-p-dioxin)
ppb = parts-per-billion
ppq = parts-per-quadrillion
* 9 ppb reading was the only reading outside the TI Zone - not verified in next sampling round
** only one reading outside TI Zone pyrene at 3.5 ppb - verified in the next sampling round
*** no readings outside the TI Zone
Page 17 of 48
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F. Current and Potential Future Site and Resource Uses
• Land Uses - The 2(K) acre Koppers site is an active wood treating facility for the foreseeable
future. Residential areas are outside a buffer of industrial and commercial areas directly
adjacent to the site. Directly to the north, east and west of the site the land is used for
commercial and light industrial purposes. To the south of the site, land use is agricultural and
rural residential. During the 1996 ROD Amendment #1 process elected officials and staff for
Butte County and the City of Oroville were contacted and a determination was made that
industrial use of the site was consistent with the City's long range plans for the area. No
concerns were raised at the 1996 or 1999 public meetings on the continued industrial use of
the site. Land use covenant deed restriction language is being developed by California
Department of Toxic Substances Control (DTSC) restricting the 200 acre site to industrial use
and restricting access to groundwater in the TI Zone,
• Groundwater Uses - Groundwater is intended for beneficial uses such as irrigation and
drinking water in accordance with the water quality goals for the State of California. On and
off-property surface water primarily infiltrates back to the aquifer. On-property some surface
water flows to two open unlined ditches called the Louisiana-Pacific Ditch (L-P Ditch) and the
Koppers Ditch. Both ditches flow to the Louisiana-Pacific Pond (L-P Pond) which has no
surface discharge. During a 100 year storm event, it is possible that the L-P Pond could
discharge to the Feather River. Groundwater on site is no longer used for drinking water but
is used for wood treating processes. With the exception of the TI Zone, on property
groundwater is expected to be restored to drinking water standards within 20 years. The
portion of the groundwater aquifer below the four acre TI Zone will not be usable for drinking
water for an indefinite period without new technology. South of Baggett Marysville Road
(off-property) the groundwater is used for drinking water and irrigation. Presently an
alternative water supply is furnished to eight drinking water well owners whose water supply
wells remain out of service until they can be shown to be free of PCP. It is estimated that the
off-property aquifer will be fully restored for drinking water use within 30 years with
enhanced in-situ bioremediation.
G. Summary of Site Risks
The EPA completed an EA for the site in 1988 providing the current and potential future
risks to public health from contamination at the Koppers site. The EA used results from the RI to
determine the COC. The EA determined the possible exposure pathways that people could be
exposed to now and in the future and calculated the risks associated with those exposures based
on residential use. The EA concluded there are unacceptably high cancer and non-cancer human
health risks for people using on or off-property contaminated groundwater as a drinking water
source. Aggregate excess lifetime cancer risks for the maximum plausible exposure scenario, the
highest exposure which is reasonably expected to occur, ranged from IxW3, for off-property use
of groundwater for drinking and domestic uses, to 8x10'' for use of on-property groundwater as a
source of drinking water (from Table 6-5, 1989 ROD). Both values significantly exceed EPA's
Page 18 of 48
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acceptable target risk range of 1()'6 to 10"4 for Superfund sites. The EA also demonstrated
aggregate non-cancer hazard indexes greater than one (1.0) for both scenarios, indicating the
potential for non-cancer health effects from use of the groundwater for drinking water purposes,
cither on or off-property. It should be noted, however, that groundwater exposure routes have
been reduced by removing contaminated drinking water wells from service and providing
Oroville-Wyandotte Irrigation District drinking water both on and off-property. The basic
conclusion of the EA that on and off-property groundwater requires remediation to minimize the
potential human health risks associated from use of contaminated groundwater remains valid.
• Human Health Risks - Off property the only COG is PCP. On property the COC are listed in
Table 2E-1 with the detection frequency and range from the Annual 1998 Groundwater Report
Reference "C". On-property in the TI Zone COC include carcinogenic and high concentration
PAHs, cPAH, dioxin and PCP. On-property COC outside the TI Zone above ARARs and To
Be Considered (TBC) criteria include PCP and boron. Excess lifetime cancer risks for the
maximum plausible exposure scenario, the highest exposure which is reasonably expected to
occur, ranged from IxlO"3 to SxlO'1 from the EA. Since the EA, PCP has been classified as a
carcinogen. When PCP is present at a concentration equal to the current MCL of 1 ppb, the
residual excess lifetime cancer risk from drinking water usage of groundwater would be
4x 1C"6. The primary risk for current and any future groundwater use is associated with
domestic uses of contaminated drinking water.
A major assumption for the TI Waiver is that deed restrictions will be implemented to restrict
groundwater use in the TI Zone. On-property outside the TT Zone major assumptions are that
deed restrictions will prevent damage to installed caps, no new source of water to subsurface
soils will be introduced through irrigation or other activities; and on-site disposal Cells #1 & 2
will not be breached.
• Ecological Risks - The COC for ecological risks are the same as listed in table 2E-1 with the
exclusion of barium and isopropyl ether. The 1988 EA and the five year review conducted in
December 1997 did not find ecological risk impacts. As part of the five year review, the EPA
reviewed the National Pollution Discharge Elimination System discharge data records which
supported the conclusion that there are no ecological risk impacts.
H. Remediation Standards
The 1989 ROD provided for restoration of groundwater for drinking water use using
P&T. This ROD Amendment provides for revising the 1989 ROD to 1) change the remedy
objective within the TI Zone, due to DNAPL, from groundwater restoration to contaminant
containment, and 2) change outside the TI Zone two of the eight cleanup standards for
groundwater while retaining the 1989 ROD standards for groundwater restoration as detailed as
follows:
Page 19 of 48
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TIZone - The ARARs lor groundwater cannot be achieved within the four acre TI Zone due to
DNAPL contamination and the remedy is being changed to containment. The rationale for the
changes are as follows: 1) surface and near surface soil contamination has been remediated
and the DNAPLs are contained, 2) it is not technically feasible to meet the cleanup standards,
3) deed restrictions can provide adequate protection to control groundwater use within the TI
Zone, 4) contaminants will be monitored inside and down-gradient of the TI Zone until such
time as the EPA may determine that it is no longer necessary for the protection of human
health and the environment, and 5) the TI Zone contingency plan includes a provision to
restore operation of the on-property P&T if a contaminant is determined by the EPA to be
leaving the TI Zone.
Outside the TI Zone - As part of the ROD Amendment, a review of ARARs was conducted for
groundwater cleanup levels at the Koppers site. A review of current drinking water standards
compared to the 1989 ROD was conducted, along with changes in the risk assessment process
since the 1989 ROD. The EPA determinated that the new Federal and State MCLs for barium
and PCP would become cleanup standards under this ROD amendment. No other changes are
being made to the 1989 ARARs. The ARAR changes for barium and PCP do not modify the
conclusion in the EA.
Barium: The 1989 ROD TBC risk based cleanup level of 680 ppb (ug/1) for barium is being
changed to 1000 ppb (ug/1) to comply with the current California MCL and reflects a
subsequent change in the oral reference dose for barium. The California MCL is more
stringent than the Federal MCL. Consistent with the 1989 ROD, the residual non-cancer risk
at this remediation standard corresponds to a hazard index of 0.4, using current standard
Superfund risk assessment values and procedures. Barium removal is achieved through the
existing on-property P&T system.
Pentachlorophenol: There was no MCL for PCP at the time of the 1989 ROD. The 1989
ROD groundwater cleanup value of 2.2 ppb (ug/1) for PCP is being changed to 1.0 ppb (ug/1)
to comply with the new Federal MCL. Since the 1989 ROD, PCP has been classified as a
carcinogen. Residual excess lifetime cancer risks from drinking water usage of groundwater
cleaned to a PCP concentration of 1 ppb would be 4xlO"6 using current standard Superfund
risk assessment values and procedures. The rationale for lowering the MCL for PCP is to
maintain the objective of restoring the groundwater aquifers for drinking water use. On-
property PCP removal will be achieved through the existing on-property P&T facility.
Amendment #2 to the ROD provides additional remedy options to the 1989 ROD to achieve
faster destruction of PCP for the restoration of the groundwater aquifers for drinking water
use.
Page 20 of 48
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Table 2H-1 - Summary of Groundwater Cleanup (CU) Value Changes
Contaminant
Pentachlorophenol (PCP)
Barium
1989 ROD
CU Value
(ppb)
2.2
680
Proposed
CU Value
(ppb)
1
1000
Comment
U.S. EPAMCL
California MCL
I. Description of Alternatives
The remedial alternatives for ROD Amendment #2 are listed in Table 21-1 and the cost
data is provided in Tables 21-2, 21-3 and 21-4. The remedial alternatives developed for each of
the groundwater remedy changes are as follows:
• TI Waiver Alternatives 1 through 6
- Alternative 1 - No Action
Operation of the existing BW-1 and PR-1 remediation well systems inside the TI Zone
would be discontinued and no monitoring or institutional controls (1C) would be in place to
protect public health and the environment.
- Alternative 2 - Grout Curtain Wall
This alternative would potentially contain the DNAPL with a grout curtain wall
approximately 1800 ft. long by 125 ft. deep created by grout injected into wells drilled in the
ground approximately 10 ft. on centers but would not perform any treatment. The wall
would be constructed in less than one year. ICs would be provided to prevent drilling of
wells within the TI Zone for purpose other than monitoring or remedial activities, to prohibit
use of groundwater within the TI zone except for wood-treating operations and to limit
future land use to industrial. Monitoring inside and down-gradient of the TI Zone would be
as long as the EPA determines is needed for protection of human health and the
environment. The existing BW-I and PR-1 remediation well systems inside the TI Zone
would remain in operation.
- Alternatives 3 - Contained Recovery of Oily Wastes (CROW) Method
This alternative would mobilize a portion of the DNAPL by thermal processes using
temperatures below the boiling point of water. Approximately 275 wells would be installed
at depths of up to 225 bgs. to inject heated water to mobilize the DNAPL for treatment at the
existing on-property P&T. After 20 years of operation significant DNAPL would remain
and the ARARs would not be achieved. ICs and monitoring as described in Alternative 2
would be implemented. Operation of the existing BW-1 and PR-1 remediation well systems
inside the TI Zone would be discontinued.
Page 21 of 48
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- Alternative 4 - Steam Enhanced Extraction
This alternative has the potential to mobilize more DNAPL than Alternative 3 through a
thermal process using steam. Steam would be injected into new wells installed around and
in the TI Zone. It is anticipated the system would be operated two years. The chemical
composition of the creosote at the site is such that it is anticipated that the ARARs would
not be achieved. ICs and monitoring as described in Alternative 2 would be implemented.
Operation of the existing BW-1 and PR-1 remediation well systems inside the TT Zone
would be discontinued.
- Alterative 5 - Continued Operation of On-property P&T
The existing on-property P&T is down gradient from the TI Zone and would treat any
contaminant leaving the TI Zone. However, the on-property P&T has no hydraulic influence
the TI Zone DNAPLs. It is anticipated that in 30 years the ARARs will be met outside the
TI Zone. The DNAPL in the TI Zone will exist for an extended period of time, well beyond
30 years. Operation of the P&T after ARARs are met outside the TI Zone will result only in
treating groundwater that no longer needs treatment. ICs and monitoring as described in
Alternative 2 would be implemented. The existing BW-1 and PR-1 remediation well
systems inside the TI Zone would remain in operation.
• Alternative 6 - Monitors Groundwater After the On-property P&T Achieves ARARs Outside
TI Zone (Selected Remedy)
Once the on-property P&T achieves ARARs, the P&T would be turned off and maintained
in ready reserve for future use. Contaminants will be monitored at locations inside and
down-gradient of the TI Zone for COC until such time as the EPA may determine that it is
no longer necessary for the protection of human health and the environment (over a hundred
years). If a contaminant was determined to be leaving the TI Zone, the on-property P&T
would be reactivated to capture and treat the contaminated groundwater. Deed restrictions
would be implemented as described in Alternative 2. The existing BW-1 and PR-1
remediation well systems inside the TI Zone would be remain in operation until creosote
recovery is less than one gallon per year at PR-1.
Summary of TI Waiver Alternatives 1 through 6
None of the Alternatives would restore groundwater to drinking water standards and
Alternative 1 (No Action) is not protective of human health and the environment because
there is no monitoring or plan of action if contaminants leave the TI Zone. Alternatives 2
through 6 would require deed restrictions and monitoring. The selected remedy Alternative
6 (Monitor Groundwater After the On-property P&T Achieves ARARs Outside TI Zone) is
protective of human health and the environment (adds an additional monitoring well and a
contingency plan for operation of the P&T if the EPA determines a contaminant is leaving
the TI Zone), is easily implemented and cost effective.
Page 22 of 48
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On-Property Groundwater Alternatives 1 through 3
- Alternative I - No Action
This alternative would not provide any monitoring or groundwatcr treatment.
- Alternative 2 - Supplement On-Property P&T with Enhanced in-situ Bioremediation
Selected Remedy
This alternative provides for supplementing the existing P&T in remediating COCs by
adding nutrients to selected groundwater wells. It is anticipated that cleanup levels would be
reached in 20 years. The present on-property monitoring program would be augmented to
provide well sampling to measure bioremediation progress until cleanup levels are achieved.
- Alternative 3 - Continued Operation of the Existing On-Property P&T
This alternative provides for continued operation of the existing on-property P&T. It is
estimated that cleanup levels will be achieved in 30 years. The present on-property
monitoring program would be continued.
- Summary of On-Property Groundwater Alternatives I through 3
The No Action alternative is not protective. Alternatives 2 and 3 will both achieve ARARs.
The selected remedy Alternative 2 (Supplement On-Property P&T with Enhanced in-situ
Bioremediation) has the potential to achieve ARARs the quickest and at the lowest cost.
Off-Property Groundwater Alternatives 1 through 4
- Alternative 1 - No Action
This alternative would not provide any monitoring. While natural attenuation of PCP will •
occur without monitoring drinking water wells are not being protected. It is anticipated that
ARARs would be reached in 50 years with no action.
- Alternative 2 - Modify Off-Property P&T
This alternative would install two new extraction wells off-property approximately a quarter
to half a mile up-gradient of the existing P&T. Piping would be installed from the new
extraction wells to the existing P&T. It is anticipated that ARARs would be reached in 30
years. The present monitoring program would be continued.
- Alternative 3 - Enhanced in-situ Bioremediation
This remedy would add nutrients to existing off-property wells to enhance the remediation
of PCP. It is anticipated ARARs would be reached in under 30 years. The present off-
property monitoring program would be augmented to provide sampling of wells to measure
bioremediation progress. If the EPA determines enhanced in-situ bioremediation will not
achieve cleanup standards or that migration of a contaminant is occurring, the EPA will
select appropriate contingency action in accordance with remedies available in the ROD.
Page 23 of 48
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• Alternative 4 - Monitored Natural Attenuation
This remedy would provide for the use of the natural biological degradation of PCP to
achieve ARARs. It is anticipated ARARs would be reached in 50 years. Site data has
shown that natural biological degradation of PCP in groundwater has occurred through the
shrinking of the off-property PCP plume. The present off-property monitoring program
would be augmented to provide sampling of wells to measure bioremediation progress. If
the EPA determines MNA will not achieve cleanup standards or that migration of a
contaminant is occurring, the EPA will select appropriate contingency action in accordance
with remedies available in the ROD.
• Summary of Off-Property Groundwater Alternatives 1 through 4
All the alternadves, including no action, should eventually achieve the ARARs. Alternative
I (No Action) will not protect drinking water wells because no monitoring will be
performed. Alternatives 2, 3 and 4 are expected to achieve ARARs. The selected remedy
Alternative 3 (Enhanced in-situ Bioremediation) is protective and the most cost effective
protective alternative.
Page 24 of 48
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Table 21-1 Description of Remedy Change Alternatives
TI ZONE WAIVER ALTERNATIVES
Alternative 1
No Action
Alternative 2
Grout Curtain Wall
Alternative 3
Thermal Treatment
Contained Recovery of
Oily Wastes Method
Alternative 4
Thermal Treatment - Steam
Enhanced Extraction
Alternative 5
Continued
Operation of
On-Property
P&T
Selected Remedy
Monitor After I»feT
Achieves ARARs
Outside TI Zone
ON-PROPERTY GROUNDWATER ALTERNATIVES
Alternative 1
No Action
Alternative 2
Selected Remedy-
Supplement Qn*Prop«1y
P&T with Enhanced in*
situ Blotemedlattort with
Monitored Natural
Attenuation (MNA) as
Contingency Remedy"
Alternative 3
Continued Operation of
On-Property P&T
OFF-PROPERTY GROUNDWATER ALTERNATIVES
Alternative 1
No Action
Alternative 2
Modify Off-Property P&T
Selected Renjedjf
Enhanced fn.j/ta
Btoreatedfatton
Alternative 4
Contingency Remedy
MNA
Page 25 of 48
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Remedy Cost
Estimate
Summary
Capital S
O&M
O&M period
Discount rate
Total O&M
discount rale
Total Present
Worth Cost
Alternative 1
No Action
SO
SO
-
-
so
so
Alternative 2
Grout Curtain Wall
$22 million
SO
$0
•
SO
$22 million
-~»..-. X."£L^l£
Alternatives
Thermal Treatment
Contained Recovery of
Oily Wastes Method
$13.75 million
$955.000
20 years (1999 thru 2018)
4%
$13 million
$26,8 million
Alternative 4
Thermal Treatment - Steam
Enhanced Extraction
-"'' '-n L '• ' J- - -"'^^"•aiamiBiE^^;
$5 tf[
$33.5 million
2 years (1999 and 2000)
4%
$62 million
$67 million
Alternative S
Continued Operation of
On-Property P&T
SO
$258,000
30 years (1999 thru 2028)
4%
$4.5 million
$4.5 million
AILS Selected Remedy
Mpnltpr:Afler P&T
;AiJileves ARARs Outside
S82£6o:>'
$12,000:12008 thru 2018)
$20,006 (2019 thru2037)
.:$5j006:p63athru2[Q7)
3i5^yeats;C?008 thru 2107)
TABLE 21-3 COST OF ON-PROPERTY GROUNDWATER REMEDIAL CHANGE ALTERNATIVES
""' """' '""•?! —. , —r^ns
Alternative 3
Remedy Cost Estimate
Summary
Capital S
O&M
O&M period
Discount rate
Total O&M discount rate
Total Present Worth Cost
Alternative 1
No Action
$0
so
-
-
$0
so
^Alternative 2Selected Remedy
,
Enhanced £#•$#** Bioremediatlon ttitb )^KA '
"
^30,000
$2S2,«X> (W* thru 2002)
"
4%
$1.35 ttaf&an-
Continued Operation of On-Property P&T
$0
$258,000
30 years (1999 thru 2028)
4%
$4.5 million
$4.5 million
Page 26 of 48
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Remedy Cost
[Estimate Summary
Capital $
O&M
O&M period
Discount rale
Total O&M discount rale
Total Present Worth Cost
Alternative 1
No Action
$0
$0
-
-
$0
$0
TABLE 21-4 COST OF OFF-PROPERTY GROUNDWATER REMEDIAL CHANGE ALTERNATIVES
Modify Off-Property P&T
elected Remedy '-
Biwemediation
- V ' "
S) ,
g> ,
%)^
• i i ii i_i_i LTE^^^^^
Alternative 4 Contii
Monitored Natural A
$0
$60,000
50 years (1999 thru 2048)
4%
$1.3 million
$1.3 million
Page 27 of 48
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J. Comparative Analysis of Remedy Alternatives
In this section, the remedial alternatives arc evaluated in relation to one another for each oi"
the nine evaluation criteria. The comparison of alternatives is based on the nine key criteria
required under the NCP and CERCLA Section 121 for use in evaluation of remedial alternatives
by the EPA. A comparison analysis of remedy alternatives is provided in the following three
matrix tables: 1) Comparison of TI Waiver Alternatives Table 2J-1; 2) Comparison of On-
Property Groundwater Remedial Alternatives Table 2J-2; and 3) Comparison of Off-Property
Groundwater Remedial Alternatives Table 2J-3.
• Overall Protection of Human Health and the Environment
TI Waiver - Alternative 1 (No Action), Alternative 3 (Contained Recovery of Oily Waste)
and Alternative 4 (Steam Enhanced Extraction) are not protective of human health and the
• environment because DNAPL will remain to contaminate groundwater and no effective
engineering or institutional controls-are provided. The remaining alternatives are protective
of human health and the environment by reducing or controlling risk posed by site
contaminated groundwater through engineering and institutional controls inside the TI
Zone. Alternative 2 (Grout Curtain Wall) would use an engineering control to provide a
physical barrier to prevent groundwater migration from the TI Zone and institutional
controls on access and use of groundwater inside the TI Zone. Alternative 5 (Continued
Operation of the P&T) and Alternative 6 (Monitor After P&T Achieves ARARs Outside
the TI Zone) provides for treatment of the contaminated groundwater leaving the TI Zone
and institutional controls on access and use of groundwater inside the TI Zone.
On-Propertv Groundwater - Of the three alternatives for on-property groundwater only
Alternative 1 (No Action) is not protective of human health and the environment because
contaminated groundwater would not be treated or monitored. The remaining alternatives
provide for protection of human health and the environment by reducing risk through
treating the groundwater. Alternative 2 (Supplement On-Property P&T with Enhanced in-
situ Bioremediation) provides treatment of groundwater by P&T and bioremediation for
enhanced PCP degradation. Alternative 3 (On-Property P&T) continues groundwater
treatment by P&T.
Off-Property Groundwater - Of the four alternatives for off-property groundwater only
Alternative 1 (No Action) is not protective of human health and the environment because
contaminated groundwater would not be treated or monitored. The remaining alternatives
provide for protection of human health and the environment by eliminating, reducing or
controlling risks posed by the site through treatment or biological process in conjunction
with monitoring. Alternative 2 (Modify Off-Property P&T) would resume treatment of
groundwater by installing new extraction wells in the residual PCP plume with new piping
to the existing off-property P&T. Alternative 3 (Enhanced in-situ Bioremediation) would
expedite the biological degradation of the remaining residual PCP plume through the
addition of nutrients. Alternative 4 (MNA) provides for monitoring of the natural
Page 28 of 48
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degradation of the remaining residual PCP plume and EPA review of remedy action if
monitoring data shows MNA is not protective of public health and the environment.
Compliance with Applicable or Relevant and Appropriate Requirements
TI Waiver - Due to DNAPL none of the six alternatives meet ARARs for the four acre TI
Zone requiring a waiver for cPAH, PGP and dioxin. Because hazardous substances will
remain in the TI Zone a five year review will be conducted pursuant to Section 121(c) of
CERCLA, 42 U.S.C. 962l(c).
On-Propcrtv Groundwater - Of the three alternatives for on-property groundwater only
Alternative 1 (No Action) does not comply with ARARs. Alternative 2 (Supplement On-
Property P&T with Enhanced in-situ Bioremediation) is expected to achieve ARARs within
20 years and Alternative 3 (On-Property P&T) within 30 years.
Qff-Propertv Groundwater - Of the four alternatives for off-property groundwater only
Alternative 1 (No Action) does not comply with ARARs because contaminated
groundwater would not be monitored for protection of drinking water wells. Alternative 2
(Modify Off-Property P&T) and Alternative 3 (Enhanced in-situ Bioremediation) are
expected to achieve ARARs within 30 years. Alternative 4 (MNA) is expected to achieve
ARARs in 50 years.
Long-Term Effectiveness and Permanence
TI Waiver - Only Alternative 1 (No Action) provides no reduction in risk over the life of
the remedy. Alternative 3 and 4 (Thermal Treatments) provide some removal of DNAPL
but do not restore groundwater to ROD cleanup standards. Alternative 5 (Continue
Operation of P&T) and Alternative 6 (Monitor After P&T Achieves ARARs Outside of the
TI Zone) do not treat DNAPL in the TI Zone but reduce risk by treating contaminants if
they leave the TI Zone) and are effective over the life of the remedy. Because hazardous
substances will remain in the TT Zone a five year review will be conducted pursuant to
Section 121(c) of CERCLA, 42 U.S.C. 9621 (c).
On-Propertv Groundwater - Only Alternative 1 (No Action) of the three alternatives
provides no reduction in risk over the life of the remedy. Alternative 2 (Supplement On-
Property P&T with Enhanced in-situ Bioremediation) and Alternative 3 (On-Property P&T)
will both reduce risk and be effective over the life of the remedy. Alternative 2 is expected
to achieve groundwater cleanup standards for PCP 10 years sooner than Alternative 3.
Off-Property Groundwater - Only Alternative 1 (No Action) of the four alternatives
provides no reduction in risk over the life of the remedy. Alternative 2 (Modify Off-
Property P&T) and Alternative 3 (Enhanced in-situ Bioremediation) will effectively
achieve cleanup standards within 30 years. The long term effectiveness of Alternative 3
depends on how well nutrients are distributed in the groundwater. Alternative 4 (MNA)
monitors the natural biological degradation of PCP and the long term effectiveness will
Page 29 of 48
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depend on the quantity of the naturally available nutrients in the aquifer.
Reduction of Toxicily, Mobility and Volume Through Treatment
TI Waiver - All the alternatives have a treatment component except Alternative 1 (No
Action). Alternative 2 (Grout Curtain Wall), Alternative 5 (Continue Operation of P&T)
and Alternative 6 (Monitor After P&T Achieves ARARs Outside of the TI Zone) provide
for the continued operation of PR-1 and BW-1 in the TI Zone also, Alternative 2 reduces
mobility through the construction of a physical barrier (engineering control). Alternative 3
(Contained Recovery of Oily Wastes Method) reduces 12% of the DNAPL volume over 20
years. Alternative 4 (Steam Enhanced Extraction) has the potential to reduce 85 to 90% of
the DNAPL volume over two years.
On-Propertv Groundwater - All three Alternatives will reduce toxicity, mobility and
volume. Alternative 1 (No Action) will not degrade Boron through MNA. Alternative 2
(Supplement On-Property P&T with Enhanced in-situ Bioremediation) will achieve a faster
degradation of PCP than Alternative 3 (On-property P&T).
Off-Propertv Groundwater - All four Alternative will reduce toxicity, mobility and volume.
The difference between Alternative 1 (No Action) and Alternative 4 (MNA) is that the
Alternative 4 provides for the monitoring of the contamination and EPA review of remedy
action if monitoring data shows cleanup levels will not be accomplished in a reasonable
time frame or containment is lost. Alternative 2 (Modify Off-property P&T) and
Alternative 3 (Enhanced in-situ Bioremediation) are expected to achieve the groundwater
cleanup stand for PCP 20 years faster than Alternative 1 or 4.
* Short-Term Effectiveness
TI Waiver - All the alternatives have some short term effectiveness except Alternative 1
(No Action) which can not be considered effective because there is no monitoring to insure
the contaminants do no leave the TI Zone and no ICs are implemented to prevent access to
groundwater for an indefinite period of time (over one hundred years) it would take for
natural degradation of contaminants within the TI Zone. Alternative 1 (grout Curtain Wall)
would only take a year to install and deed restrictions would control access to groundwater
within the TI Zone. Alternative 3 (Contained Recovery of Oily Wastes Method) would
take a year to install but would need to operate over 20 years. Alternative 4 (Steam
Enhanced Extraction) would operate for 2 years injecting steam. Alternative 5 (Continue
Operation of P&T) requires no new construction by the existing system would have to
operate over a hundred years to capture contaminants that might leave the TI Zone.
Alternative 6 (Monitor After P&T Achieves ARARs Outside the TI Zone) would not
require any construction and the P&T would only be operated if contaminants were
determined to be leaving the TI Zone.
Page 30 of 48
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On-PropertyGronndwaTe.r - Alternative 1 (No Action) is not effective because plume
control will be lost and contaminants would be allowed to migrate off-property
Alternative 2 (Supplement On-Property P&T with Enhanced in-situ Bioremediation)
requires the adding of non hazardous nutrients to existing wells (new well remain an
option) over a remedy life of up to 20 years. Alternative 3 (On-Property P&T) requires no
new construction but the operation of the existing P&T for 30 years.
Off-Property Groundwater - All four alternatives are short-term effective. Alternative 1
(No Action) requires no construction and will have no impact to the community over the
estimated 50 year PCP natural degradation period as long as the residual plume remains
contained. Alternative 2 (Modify Off-Property P&T) would take a year of construction and
the P&T would have to be operated an estimated 30 years. Alternative 3 (Enhanced in-situ
Bioremediation) requires the adding of non hazardous nutrients to existing wells (new
nutrient wells remain an option) over a remedy life of up to 30 years. Alternative 4 (MNA)
requires no construction and will have no impact on the community over the estimated 50
year PCP natural degradation period.
Implementability
TI Waiver - All six Alternatives are easily implemented. All materials and services
required for implementation are readily available. Alternatives 3 and 4 (Thermal
Treatments) use standard components, however, engineering design must be carefully done
to insure that mobilized contaminants are properly controlled and captured.
On-Propertv Groundwater - AH three Alternatives are easily implemented. Only
Alternative 3 (Supplement On-Property P&T with Enhanced in-situ Bioremediation)
requires any new action and all materials and services required for implementation are
readily available.
Off-Property Groundwater - AH four Alternatives are easily implemented. Alternative 2
(Modify Off-Property P&T) and Alternative 3 (Enhanced in-situ Bioremediation) use
readily available materials and services. •
Cost
TI Waiver - The estimated present worth costs for the alternatives, excluding the No
Action alternative, range from $244,500 for Alternative 6 (Monitor After P&T Achieves
ARARs Outside the TI Zone) to $67 million for Alternative 4 (Steam Enhanced Extraction)
as shown on Table 21-2.
On-Propcrtv Groundwater - The estimated present worth costs for the alternatives,
excluding the No Action alternative, range from $1.7 million for Alternative 2 (Supplement
On-Property P&T with Enhanced in-situ Bioremediation) to $4.5 million for Alternative 3
(Continued Operation of On-Property P&T) as shown on Table 21-3.
Page 31 of 48
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Off-Property Groundwater - The estimated present worth costs for the alternatives,
excluding the No Action alternative, range from $606,000 for Alternative 3 (Enhanced in-
situ Bioremedialion) to $4.9 million for Alternative 2 (Modify Off-Property P&T) as shown
on Table 21-4.
State Acceptance
The State did not provide comments on the individual alternatives for remedy changes (TI
Waiver, On-Property Groundwater and Off-Property Groundwater) but provided a letter of
acceptance of the proposed plan and concurrence with the this ROD Amendment.
Community Acceptance
The community during the public comment period did not provide comments on the
individual alternatives for remedy changes (TI Waiver, On-Property Groundwater and Off-
Property Groundwater). After the public comment period one phone comment was
received against granting any TI Waiver.
Page 32 of 48
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TABLE 2J-1 COMPARISON OF TI WAIVER ALTERNATIVES
Evaluation
Criteria
Protection of
Human
Health and
the
Environment
MeetARARs
Long-Term
Effectiveness
and
Permanence
Reduction of
Toxicity,
Stability, or
Volume
Short-Term
Effectiveness
Implement-
ability
Total Present
Worth Cost
Alternative I
No Action
Does not provide
overall protection
of human health
and the
environment.
Does not comply.
Least effective.
Does not reduce
toxicity,
mobility, or
volume.
Not effective -
DNAPLmaynot
remain contained
and no 1C to
prevent exposure.
Easy to
implement
Because no
action required.
SO
Alternative 2
Grout Curtain
Wall
Provides moderately
high degree of overall
protection of human
health and the
environment.
Does not comply.
Does not remove
DNAPLintheTIZone
but provides a physical
barrier to contaminants
within the TI Zone as
long as cracks and
fissures do not develop
in the wall.
Does not reduce
loxicity or volume, but
effective in reducing
mobility.
Effective with only one
year for installation,
but requires adherence
to a health and safety
plan.
Implement able, but
suitability of the soil
condition must be
evaluated for wall
construction.
E22 million
Alternative 3
Thermal Treatment
- Contained
Recovery of Oily
Wastes Method
Provides low degree of
overall protection of
human health and the
environment.
Does not comply.
Partially effective
because 12% of
DNAPL would be
removed over a 20 yr
period. Remaining
DNAPL would prevent
restoration of
groundwater to cleanup
standards.
Effective in reducing
toxicity and volume,
but not effective in
reducing mobility.
Limited short term
effectiveness due to 20
yr. duration of remedial
action. Requires
adherence to a health
and safety plan.
Difficult to implement
echnically due to
depth of DNAPL.
Bench scale testing &
computer modeling
ndicated 12% to 65%
of free creosote could
>e removed within 20
'ears. Pilot scale test is
equired.
126.8 million
Alternative 4
Thermal Treatment -
Steam Enhanced
Extraction
Provides low degree of
overall protection of
human health and the
environment.
Does not comply.
Moderately effective with
potential for significant
DNAPL removed.
However, some residual
DNAPL would remain
preventing restoration of
groundwater to cleanup
standards.
Effective in reducing
loxicity and volume, but
not effective in reducing
mobility.
Effective, but requires
adherence to a health and
safely plan during two
years of steam injection.
Difficult to Implement
echnically because of
existence of DNAPL in
deeper depths. A pilot
scale treatability test is
required.
167 million
Alternative 5
Continue
Operation of P&T
Provides moderately
high degree of overall
protection of human
health and the
environment.
Does not comply.
Does not remove
DNAPLintheTIZone
but the P&T will be
able to capture any
'contaminants coming
from the TI Zone for
effective control.
Does not reduce
toxicity or volume, but
effective in controlling
mobility if
contamination leaves
TTI Zone.
The P&T is already in
place but the
operation period would
be over 100 years
Easy to implement
P&T already in place
& operating.
»4.S million
Alt. 6 Selected
Remedy
Monitor After
t&T Acbfevcs
ARARs Outside of
iflie TtZofte
Provides moderately
ht£h dejtt* of overall
protection of human
iealthjujdtie
«nvuromneirt»
ttoesnatcaa&ly
Does riot remove
ONAPUirtheTIZoii*
but af monitoring '
showed contaminants
coming .from the TJ
Zone, ths1?&TwUfce
operated :to achieve
effective contra)
No reduction J«
toxicity or volume, bm
effective m controlling
contamination leaving
TlZone. "
Hignly«ffectlv< P&t
would t« mjuatajfted"
ready for teactivauoh
ft cotttnrnfitsnon left
TlZone
EasyWJtttpienXnt
ceQtiirBjt-aflly
maintenance of
existagP&T.
$0.25 million
Page 33 of 48
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-2 COMPARISON OF ON-PROPERTY GROUNDWATER REMEDIAL ALTERNATIVES
Evaluation Criteria
Protection of Human
Health and the
Environment
ARARs Compliance
LooE-Term Effectiveness
tad Permanence
Reduction of Toxicity,
Mobility, or Volume
Short-Term Effectiveness
Implcmcnttbility Short-
Tcrm Effectiveness
Total Present Worth Cost
Alternative 1
No Action
Does not provide overall
protection of human health and
the environment.
Does not comply.
Least effective.
Partially effective in reducing
toxicity, mobility, or volume
due to natural attenuation of
PCP.
Not effective - Present P&T
plume control would be lost..
Easy to implement because no
action required.
SO .
Alternative 2 Selected Remedy
Supplement On-Property P&T
With Enhanced in-situ <.••••• • "••
Blpremedlatian with Monitored
•jtfertursil Attenuation a$; • ' ; ' -
«awonnieiiC' '. "^s "1-2 ''• • '"
Compiles. - ,-, y, , ,'>-.'
bioacgraded to'rionhszanSoussubstence
attenuation Long'jcmi,rffecfiyeness \''
will dftp61'^1? howsreJlttie sfldeii
.ground wsaier for tiwrfl to ^ct on the. ?CX.
-MNA »Ssded as contingency ifindt'SU;
jpojftjbn$<>f thVp)M|t\e receive Jiuirients,'
-------
.ABLE2J-3C
Evaluation
Criteria
==^^=^=
Protection of
Human Health
and the
Environment
ARARs
Compliance
Long-Tcrm
Effectiveness and
Permanence
Reduction of
'oxicity.
Mobility, or
/olume
Snort-Term
Effectiveness
Implementability
Total Present
Worth Cost
OMPARISON OF OFF-PROPERTY GROUNDWATER REMEDI
Alternative I
No Action
Does not provide
overall protection of
human health and the
environment.
Does not comply.
Least effective.
Partly effective in
reducing toxicity,
mobility, or volume
due to natural
attenuation.
Highly effective as no
construction needs to
be performed.
Easy to implement
because no action
required.
$0
Alternative 2
Modify Off-Property
P&T
Provides high degree of
overall protection of human
health and the environment
Complies.
Effective as shown by
existing P&T.
Effective in reducing
toxicity, mobility, or volume.
Effective, but requires
adherence to a health and
safety plan.
Easy to implement as P&T
already in place and
operation.
$4.9 million
Alternative 3
Selected Remedy
Bioremediatiotv - ; . ; „
JProvicJesOTroderafelyjfiigh '
degree of w«raitl protection * -
of. titini&f,.neanh &nd die1" ~ * \
^etrvtfonmeal. ' " A "> ' "'
Compiles, ~ ...,- , •
Effectiyesstlie 1?iGP in the* - C
'<|je,addedsnutr|enls,;Lpng -
term eftettivenegs will/ '/*^
'depend on how'weaaapents"
•caidfePCPV >c ',•/••
Effectiyaln reducing \ ..4 " --<
Safety 'pliaC- : J~ ' •" '•""" '-i'
Easy to inptwftaf. Hckwe^' '
duWUottof «njedjat£ot)jte:nol I
^dr^ed;usli^rh6nKor1rjg-" '-]
data coljecifftct^unng (fig. »; &.
jo^^^^V;;-
AL ALTERNATIVES
T
Contingency Remedy
Monitored Natural
Attenuation
Provides overall protection of
human health and the
environment thru monitoring &
EPA review of remedy action.
Complies.
Moderately effective. PCP in the
plume will be biodegraded to
nonhazardous substance by
natural biological condition of
the aquifer. Long term
effectiveness will depend on the
quantity of the naturally
available nutrients in the aquifer.
Moderately effective in reducing
toxicity, mobility, or volume.
Effective.
Easy to implement. However,
duration of remediation is not
known now, but can be
estimated using monitoring data
collected during the progress of
natural attenuation.
$1.3 million
Page 35 of 48
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K. Selected Remedy
The following sections describe the modifications to the 1989 ROD, including the waiver of
the cleanup standards for the TI Zone, and additional enhancements and modifications. Table 2L-
1 summarizes the Applicable or Relevant and Appropriate Requirements (ARARs) for
groundwater and provides the cleanup standard for COCs.
• Technical Impracticability Waiver (Remedy Change On-Property Alternative 6, TI Waiver)
• Contaminants will be monitored inside and down-gradient of the TI Zone until such time
as the EPA may determine that it is no longer necessary for the protection of human health
and the environment. Monitoring will be conducted at the locations and frequency
specified in TI Evaluation Reference "A". The EPA reserves the right to modify TI
Evaluation Reference "A" as necessary based on the latest site data. Once the on-property
P&T facility is placed in standby reserve, operation will resume if 95% of the upper
confidence limit of the mean for four consecutive sampling events for a COC exceeds the
ROD standard. If a contaminant is detected outside the TI Zone, sample frequency for the
contaminant will change to quarterly. After four consecutive quarters of non-detect the
sampling frequency may revert to the next monitoring plan level. Monitoring data will be
submitted with the Remedial Action Groundwater Monitoring Report submittal or another
approved reporting mechanism.
• Install one new monitoring well down-gradient of the TI Zone in aquifer B. A minimum of
one year of monitoring data from the new well will be incorporated in the data to establish
cleanup levels have been met outside the TI Zone prior to placing the on-property P&T
facility in standby reserve.
• Six months prior to placing the P&T facility on standby reserve, a detailed contingency
plan will be submitted to the EPA for approval. The TI Zone contingency plan will
describe the activities necessary to maintain the on-property P&T facility in good working
order with the ability to resume normal operations within one month of determination that
COC are leaving the TI Zone.
• Six months prior to placing the P&T facility on standby reserve the TI Zone monitoring
plan provided in TI Evaluation Reference "A" will be reviewed and updated as necessary
for EPA approval.
• Operation of the existing Product Recovery well (PR-1) and the PAH in-situ groundwater
bioremediation well (BW-1) will continue until creosote recovery is less than one gallon
per year at PR-1.
• Institutional controls in the form of deed restrictions will be developed to prevent access to
groundwater, surface disturbance and the addition of new sources of surface water to
groundwater in the TI Zone. Access to groundwater for wood treating operations,
Page 36 of 48
-------
Superfund remediation and Superfund monitoring will be an authorized exclusion. Land
use covenant deed restrictions will be prepared in accordance with DTSC guidance.
DTSC will oversee and approve the preparation and recording of the deed restrictions by
the property owner.
Enhanced in-situ Bioremediation (Selected Remedy On-Property Alternative 2 and Off-
Property Alternative 3)
• Nutrients will be added to monitoring wells in accordance with proposals from HSI
Geotrans 1) June 10, 1998 Revised Off-Property Groundwater in-situ Bioremediation
Program and 2) August 21, 1997 On-Property Groundwater in-situ Bioremediation
Program or latest EPA approved modification of either document. Existing wells will be
utilized on and off-property for nutrient addition (primarily oxygen, nitrogen and
phosphorus) to provide optimum conditions for PCP degradation in conjunction with
down-gradient monitoring. As indicated in Figure 2K-1, provision is made for the
addition of new wells for nutrient addition should field conditions warrant. The enhanced
in-situ bioremediation program integrates with the other ROD remedies as shown on
Figure 2K-1.
• The existing on-property P&T facility will remain in operation during the on-property
enhanced in-situ bioremediation program to restore groundwater on-property and prevent
contaminants from migrating off-property and feeding the off-property plume. The on-
property P&T will remain in operation until the EPA confirms that cleanup levels are met
on-property, outside the TI Zone.
• An annual evaluation of the on and off-property enhanced in-situ bioremediation program,
including adjustments, as necessary, to nutrient frequency and quantity to maintain
optimum PCP degradation will be conducted and submitted to the EPA for approval.
Unless another reporting mechanism is approved, enhanced in-situ bioremediation
monitoring data and status will be provided as part of the Remedial Action Groundwater
Monitoring Reports, including the annual evaluation.
• The off-property enhanced in-situ bioremediation program will be used as the primary
method to destroy the remaining PCP in groundwater. However, P&T still remains a
remedy option.
• Due to nutrient addition to monitoring well RI-11 the alternative water supply termination
criteria (AWSTC) for water supply wells 59, 60, 61, 62 and 81 is modified as follows: 1)
verification sampling for PCP to end the subsidy cannot be conducted until nutrient
addition in the area of these wells has been terminated and nutrient levels have returned to
background levels for at least one year and 2) to end the subsidy for each individual
drinking water well the PCP level must be less than 0.5 ppb for four consecutive quarters.
Page 37 of 48
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Yes
CR - Contingency Remedy
EIB - Enhanced in-situ Biorcmediation
ESD - Explanation of significant difference
MNA- Monitored Natural Attenuation
Modify EIB Prog. - Review nutrient program for well
locations, nutrient amounts, new wells, etc.
If change submit TM.
P&T - Pump and Treat
ROD - Record of Decision
TM - Technical Memorandum
All decision blocks are EPA decision points
TM-technical &
economical evaluation
to change (o MNA
Figure 2K-1 - Flow Chart for EIB and MNA
Implementation On and Off-Property Plumes
Koppers ROD Amendment #2
Page 38 of 48
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If the EPA determines enhanced in-situ bioremediation will not achieve cleanup standards
or that migration of a contaminant is occurring, the EPA will select appropriate contingency
action in accordance with remedies available in the ROD.
• Monitored Natural Attenuation As Contingency Remedy (Selected Contingency Remedy On-
Property Alternative 2 and Off-Property Alternative 4)
• Provision is made for implementing MNA as a contingency remedy on and off-property if
the EPA determines that 1) enhanced in-situ bioremediation nutrient distribution cannot be
adequately achieved, 2) other active restoration measures are not necessary, 3) conditions
on and off-property continue to demonstrate that PCP degradation is occurring and 4)
natural attenuation is expected to achieve cleanup levels within a reasonable time frame
achievable by a treatment remedy. The MNA remedy integrates with the other remedies as
shown on Figure 2K-1.
• If the MNA contingency remedy is implemented, a monitoring plan will be developed for
EPA approval.
• If the EPA determines MNA will not achieve cleanup standards or that migration of a
contaminant is occurring, the EPA will select appropriate contingency action in
accordance with remedies available in the ROD.
L. 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 that
permanently and significantly reduces the volume, toxicity, or mobility of hazardous wastes as
their principal element. The following section discuss how the selected remedy addresses these
statutory requirements and preferences.
• Protection of Human Health and the Environment
TI Waiver - Waiving the groundwater ARARs for contaminants of concern (dioxin, cPAHs,
and PCP) for the four acre TI Zone is still protective of human health because 1) surface and
near surface soil contamination has been remediated, preventing worker exposure in the TI
Zone and further contamination of the aquifer, 2) the DNAPLs are contained based on
monitoring data down gradient, 3) an additional monitoring well will be installed prior to
Page 39 of 48
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taking the P&T offline and placing it in a maintained ready reserve state, 4) deed restrictions
will be implemented to control access to groundwater under the TI Zone, 5) the groundwater
in the TI Zone and down gradient of the TI Zone will be monitored and evaluated semi-
annually prior to placing the P&T in ready reserve and then annually until such time as EPA
may determine that it is no longer necessary for the protection of human health and the
environment, 6) the TI Zone is down gradient from the on-property P&T and the TT Zone
contingency plan makes provision to maintain and then operate the on-property P&T if a
contaminant is determined to be leaving the TI Zone and 7) remedy effectiveness will be
reviewed at least every five years.
Because this remedy will result in contaminants remaining on-site above levels that allow
for unlimited use and unrestricted exposure, a statutory Five-Year review will be conducted
within five years of the commencement of this amended remedial action to ensure that the
remedy continues to provide adequate protection of human health and the environment.
Enhanced in-situ Bioremediation On and Off-Property - The nutrient added to enhance PCP
degradation are not harmful to human health in the quantities used and nutrient concentration
in groundwater will be monitored. The process uses bacteria already available in the soil.
The addition of the nutrients on-and off property has the potential to reduce the remediation
effort significantly, allowing early return of the drinking water aquifer. On-property enhanced
in-situ bioremediation will supplement the exiting P&T. If the EPA determines enhanced in-
situ bioremediation will not achieve cleanup standards or that migration of a contaminant is
occurring, the EPA will select appropriate contingency action in accordance with remedies
available in the ROD.
MNA As Contingency Remedy - Natural attenuation if implemented as a contingency remedy
is protective of public health because 1) the monitoring will continue until it has been
demonstrated that ARARs have been achieved, 2) MNA will be implemented only for
contained or shrinking PCP plumes, 3) natural attenuation is expected to achieve cleanup
levels within a reasonable time frame achievable by a treatment remedy (see Figure 2K-1),
and 4) the EPA will review remedy action if monitoring data shows that a contaminant
threatens water supply wells or cleanup levels will not be met.
Compliance with ARARs
This ROD Amendment modifies the groundwater remedy selected in the 1989 ROD and
documents a waiver of the groundwater cleanup standards for all areas within the TI Zone.
The EPA has waived the ARARs that apply to the TI Zone because it is technically
impracticable, from an engineering perspective, to meet the standards. See, CERCLA section
121(d)(4)(c), 42 U.S.C. Section 9621(d)(4)(c). This ROD Amendment will not affect the
ARARs selected for the Soils Remedy (ROD Amendment #1 1996); however, it will affect
groundwater ARARs outside the TI Zone by changing the MCL for Barium and PCP.
Page 40 of 48
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Remedial actions selected under CERCLA must comply with all ARARs under federal
environmental laws or, where more stringent than the federal requirements, Slate or Slate
subdivision environmental or facility siting laws. Where a Slate is delegated aulhorily lo
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 law.
Applicable or relevant and appropriate requirements are identified on a site-specific basis
from information about site-specific chemicals, specific actions that are being considered, and
specific features of the site location. There are three categories of ARARs: (1) chemical-
specific requirements; (2) action-specific requirements; and (3) location-specific
requirements. Where no ARARs exist 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 TBC, those standards are legally enforceable.
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 COC.
Location-specific ARARs are restrictions placed on concentrations of hazardous substances or
the conduct of activities because of the special locations, which have important geographical,
biological or cultural features. Examples of special locations include wetlands, flood plains,
sensitive ecosystems and seismic areas.
Action-specific ARARs are technology-based or activity-based requirements or limitations on
actions to be taken to handle hazardous wastes. They are triggered by the particular remedial
activities selected to accomplish a remedy.
The ARARs adopted in the 1989 ROD were "frozen" as of the date EPA signed the ROD.
The ARARs are being modified in this ROD Amendment in the following three respects: I)
modification to the groundwater remedy requires a waiver of all ARARs within the TI Zone,
2) the this ROD Amendment provides for new remedial activities that require the adoption of
additional action specific ARARs and 3).this ROD Amendment incorporates newly
promulgated requirements that are necessary to ensure the protectiveness of the selected
remedy. See 40 CFR Section 300.430(f)(ii)(B); 55 Federal Register 8747, 8758 (March 8,
1990). The ARARs for this ROD Amendment are identified in Table 2L-1.
Page 41 of 48
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Table 2L-1 Applicable or Relevant and Appropriate Requirements for (iround water ROD Amendment
Source
Standard, Requirement,
Criterion, or Limitation
Applicable or Relevant
and Appropriate
ARAR or Performance
Standard Applicability
Porter-Cologne Water
Quality Control Act
(California Water Code
Sections 13000,13140,
13240,13260,13263,
13267,13300,13394,
13307).
State Water Resources
control Board Resolution
No. 92-49 (as amended
April 21,1994)
(Subparagraph IIIG)
Relevant and Appropriate
Applies to groundwater
remedial actions. The
groundwater cleanup
system will be operated in
such a way that the best
water quality reasonable
is restored.
Porter-Cologne Water
Quality Control Act
(California Water Code
Sections 13140-13147,
13172,13260,13262,
13267,13304
Title 27, CCR, Section
20410, TiUe 23, CCR,
Section 2550.6
Applicable
Applies to groundwater
remediation and
monitoring of sites.
Qroundwater will be
remediated and monitored
according to TiUe 27/Title
23 regulations.
Safe Drinking Water Act
(40U.S.C.300etseq.).
National Primary
Drinking Water Standards
(40 CFR Part 141)
Relevant and Appropriate
Table Continued
Chemical-specific
drinking water standard
MCLs have been
promulgated under the
Safe Drinking Water Act
(SDWA). Drinking-water
MCL standards has also
been promulgated under
die SDWA. MCLGs
above zero are considered
chemical-specific ARAR
under die NCP (40 CFR
300.430(e)(2)(I)(B)).
When the MCLGs are
equal to zero ( which is
generally the case for
chemical considered to be
a carcinogen), die MCL is
considered to be a
chemical-specific ARAR,
instead of die MCLG (40
CFR 300.430(e)(2)(I)(C)).
In 1989, a Federal MCL
for PCP did not exist. A
Federal MCL for PCP
was recently set at 1 ppb.
This MCL is waived in
the TI Zone.
Page 42 of 48
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Source
Standard, Requirement,
Criterion, or Limitation
Applicable or Relevant
and Appropriate
ARAR or Performance
Standard Applicability
California Safe Drinking
Water Act
CCR Tide 22, Division 4,
Chapter 15, Articles 4,
5.5, and 8.
Relevant and Appropriate
Table Continued
California primary
drinking water standards
establish enforceable
limits for chemicals that
may affect public health
or the aesthetic qualities
of drinking water.
However, only those State
requirements that are
more stringent than
federal standards are
ARARs. Recently, a
State MCL for barium
was changed to 1000 ppb.
Hazardous Waste Control
Act (California Health
and Safety Code 25100 et
seq.).
27 CCR, Division 2,
Subdivision 1.
Applicable
Table Continued
Title 27 establishes waste
and siting classification
systems and minimum
waste management
standards for discharges
of waste to land for
treatment, storage, and
disposal. Title 27 also
contains corrective action
provisions for responding
to leaks and other
unauthorized discharges
Spent GAC will be
classified and handled in
accordance with Title 27
requirements.
Page 43 of 48
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Source
Standard, Requirement,
Criterion, or Limitation
Applicable or Relevant
and Appropriate
ARAR or Performance
Standard Applicability
Resource Conservation
and Recovery Act Subpart
A A (22 CCR 66265.1030
el seq.).
Article 27 Air Emission
Standards for Process
Vents (22 CCR
66265.1030-66265.1035).
Relevant and Appropriate
Table Continued
Applies to treatment,
storage, and disposal
facilities widi process
vents associated widi
solvent extraction or air or
steam stripping operations
managing RCRA
hazardous wastes widi
organic concentrations of
at least 10 ppm. These
operations must reduce
total organic emissions
below specified device to
reduce total organic
emissions by 95 percent
by weight. The
requirements are relevant
and appropriate for
groundwater extraction
and air-stripping
operations.
Based on the above ARARs analysis die cleanup standards dial must be met for die COC outside die TI Waiver Zone
are set forth in die following table.
Table 2L-2 Cleanup Standard for Chemicals of Concern (COC) Outside the TI Zone
COC
Pentachlorophenol
Isopropyl Ether
Barium
Boron
Arsenic
Chromium
PCDDs/PCDFs (dioxin) as 2,3,7,8-
TCDD Toxic Equivalency Factor
Total cPAHs
Remedial Action Level
1 ppb*1 **
2,800 ppb
1,000 ppb*
1,200 ppb ;
Background (27 ug/L)
50 ppb .
5.3xlO'7 ppb**
0.007 ppb**
ARAR or Performance Standard
Applicability
Fed. MCL
TBC from 1989 ROD
Calif. MCL
TBC from 1989 ROD
Remedial standard, 1989 ROD
Calif. MCL
Remedial standard, 1989 ROD
Remedial standard, 1989 ROD
* update from remediation standard in 1989 ROD - odier standards unchanged
** waived forTI Zone
Page 44 of 48
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Waiver of Groundwater Cleanup ARARs
In this ROD Amendment, EPA concludes that it is technically impracticable from an engineering
perspective to achieve cleanup standards for groundwater within the TI Zone. Groundwater
outside the TI Zone will be remediated to the ROD cleanup standards.
The EPA is invoking a waiver of groundwater cleanup ARARs in the TI Zone because
contaminant and hydrogeologic conditions inhibit restoration. Pentachlorophenol and creosote,
as DNAPL, are present in the TI Zone. The presence of a DNAPL, combined with the very low
permeability clay present in the H Zone, makes groundwater restoration within the Zone
technically impracticable given current technologies. The factual basis for the TI Waiver is set
forth in more detail in TI Evaluation Reference "A".
The EPA's long term objective is to address contamination situations which pose an actual or
potential threat to groundwater resources. DNAPL remediation options beyond pump and treat
have historically been limited. Recent developments suggest that alternatives are emerging which
will allow effective removal of DNAPL contamination, eliminating the need for or reducing the
duration of pump and treat operations. EPA intends to review the technical impracticability of
remediation as additional information and experience becomes available.
• Cost-Effectiveness - Cost-effectiveness is determined by evaluating three of the balancing
criteria (long-term effectiveness and permanence; reduction of toxicity, mobility or volume
through treatment; and short-term effectiveness). Overall effectiveness is then compared to
cost to ensure that the remedy is cost-effective.
TI Waiver - Only Alternative 2 (Grout Curtain Wall) has long-term effectiveness. Alternatives
3 & 4 (Thermal Treatments) both reduce toxicity and volume but not mobility and Alternative
5 (Continued Operation of On-Property P&T) only reduces toxicity. Alternative 5 (Continued
Operation of On-Property P&T) can reduce toxicity but once the ARARs are met outside the TI
Zone the P&T will be wastefully treating clean water for a significant period of time. The
treatment technologies have the potential to contaminate clean areas and leave significant
contamination in-place. Alternative 5 (Continued Operation of On-Property P&T) and 6
(Monitor After P&T Achieves ARARs) have the highest short-term effectiveness because they
required the least disruption. Alternatives 2 (Grout Curtain Wall) and 4 (Steam Enhanced
Extraction) pose some hazard during implementation. Alternative 3 (Contained Recovery of
Oily Wastes Method) has the lowest short-term effectiveness due to the duration of remedial
action. The total cost of the treatment alternatives run 18 to 268 times more expensive than the
selected remedy Alterative 6 (Monitor After P&T Achieves ARARs).
Page 45 of 48
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On-Propertv Groundwater Remedy Change - Alternatives 2 (On-Property P&T with Enhanced
in-situ Bioremediation) and 3 (Continued Operation of On-Property P&T) are both effective
long-term and both reduce loxicily, volume and mobility but Alternative 2 (On-Property P&T
with Enhanced in-situ Bioremedialion) has the potential to restore groundwater twice as fast.
Both Alternates 2 and 3 have good short-term effectiveness. The total cost of the selected
remedy, Alternative 2 (On-Property P&T with Enhanced in-situ Bioremediation), is less than
half the cost of Alternative 3 (Continued Operation of On-Property P&T).
Off-Property Groundwater Remedy Change - Alternatives 2 (Modify Off-Property P&T) and 3
(Enhanced in-situ Bioremediation) are both effective in long-term and both reduce toxicity,
volume and mobility. Alternatives 3 (Enhanced in-situ Bioremediation) and 4 (MNA) were the
most effective in the short-term due to minimal implementation impacts than Alternative 2
(Modify Off-Property P&T). The total cost of the selected remedy, Alternative 3 (Enhanced in-
situ Bioremediation), is 2 to 8 times less than the other alternatives.
Utilization of Permanent Solutions and Alternative Treatment Technologies or Resource
Recovery Technologies to the Maximum Extent Practicable
TI Waiver - The EPA has determined that the selected remedy (Alternative #6 - Monitor After
P&T Achieves ARARs Outside of the TI Zone) represents the maximum extent to which
permanent solutions and treatment technologies can be used in a cost-effective manner for
groundwater 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.
The selected remedy for the TI Zone does result in some treatment of contaminants through the
continued operation of the Product Recovery well (PR-1) and the PAH in-situ groundwater
bioremediation well (BW-1). Some TI Zone DNAPL contamination will degrade over time
through biological action. The alternative remedies reviewed cannot remove all the DNAPL
and thus, the drinking water aquifer will not be restored. DNAPL remediation options with
present day technology have been limited and will continue .to be reviewed as new technologies
emerge.
Qn-Property Groundwater Remedy Change - The selected remedy (Alternative 2 - On-Property
P&T with Enhanced Bioremediation) will provide a permanent solution for groundwater
restoration to the maximum extent possible outside the TI Zone. The intent of supplementing
the P&T is to speedup the groundwater restoration through the early destruction of PCP.
Page 46 of 48
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On-Property Groundwaler Remedy Chanr. - The selected remedy (Alternative 3 - Enhanced
m-situ Bioremediation) will provide a permanent solution to the maximum extent possible
Site data has shown that nutrient addition will aid in the destruction of PCP, the remaining
COC off-property.
• Preference for Treatment as a Principal Element
TI Waiver - Although contaminated groundwaters generally are not considered to be principal
threat wastes, DNAPLs may be viewed as a principal threat waste because of their potential to
be sources of toxic contaminants to groundwater. For this reason, the EPA expects to remove
or treat DNAPLs to the extent practicable which is being accomplished at Koppers site through
the continued operation of 1) the existing product recovery well (PR-1) for removal of mobile
creosote DNAPL and 2) the existing in-situ groundwater bioremediation well system (BW-1)
for bioremediation of PAHs. However, as previously stated the available treatment
technologies are not capable of removing and treating all of the DNAPLs necessary to allow
attainment of ARARs/groundwater restoration in the TI Zone. The EPA expects that the PR-1,
BW-1 efforts with monitoring inside and down gradient of the TI Zone represent adequate
control for migration and continued reduction of DNAPLs. The selected groundwater remedy
(Alternative #6 - Monitor After P&T Achieves ARARs Outside of the TI Zone) for the TI Zone
uses containment and monitoring, rather than treatment, to address the threats posed by
DNAPL in the TI Zone. The available treatment technologies will not achieve the restoration
of drinking water standards within the TI Zone after significant capital investment. Until a
technology is available that will remove all the DNAPL, this zone cannot be restored to
drinking water standards.
Qn-Property Groundwater Remedy Change. - The selected remedy (Alternative 2 - On-Property
P&T with Enhanced Bioremediation) is a treatment that has been demonstrated to be effective
on site.
Off-Property Groundwater Remedy Chanp^ - The selected remedy (Alternative 3 - Enhanced
in-situ Bioremediation) is a treatment that has been demonstrated to be effective on site.
M. Documentation of Significant Changes from Preferred Alterative of the Proposed Plan
In the absence of public comments and/or any new information regarding the 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.
Page 47 of 48
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PARTS: RESPONSIVENESS SUMMARY
A. Stakeholder Issues and EPA Responses
As described in Part 2(C) the issues raised by the community stakeholders did not directly
address the Proposed Plan. During the phone survey conducted in December 1998 one individual
felt his water subsidy should have been for life vs. ending when it was determined that his water
supply well was free of contaminants from Koppers. No expressed opposition to the proposed plan
was received at the public meeting held March 9, 1999. Only two comments were received during
the 30 day comment period March 15 though April 13,1999 even though 400 fact sheets had been
mailed and the public meeting presentation was well covered by the media (local newspaper
articles and local TV evening and morning news spots). Of the two comments received during the
public comment period, one expressed a concern of excess cancer deaths north of the site and one
expressed concern for protection, compensation and education of the Koppers employees of site
dangers. Both written comments were answered individually by letter April 23, 1999 providing
answers to questions and points of contact for questions outside Superfund. No further information
was requested by the responders. After the public comment period one phone call was received, in
which the caller expressed the view that public participation was light because of the deaths of the
active community members and that the TI Waiver should not be approved because the
contamination would be forgotten over time and would be allowed to re-contaminate the water
supply. The call was responded to by phone and a description of the monitoring and review
process for the TI Waiver was explained.
The California Regional Water Quality Control Board Central Valley Region and the
California Department of Toxic Substances Control individually replied by letters dated May 10,
1999 concurring with the three remedy changes contained in the Proposed Plan.
D. Technical and Legal Issues
No technical or legal issues were raised by the stakeholders during the public comment period.
The single oral comment received after the public comment period pertaining to allowing re-
contamination of groundwater from the TI Zone is addressed in Part 2(K).
Page 48 of 48
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