PB94-964124
EP A/ROD/R05-94/250
September 1994
EP A Superfund
Record of Decision:
Koppers Coke Site,
St. Paul, MN,
4/21/1994
Hazardous Waste Collection
Information Resource Center
US EPA R~glon 3
PhUodelph(o'c PA t 9107

....-/'
o
EP A Report Collection
Information Resource Center
US EP A Region 3
Philadelphia, PA 19107
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DECLARA nON FOR THE RECORD OF DECISION
SITE NAME AND LOCATION
Koppers Coke Site
St. Paul, Ramsey County
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for contaminated ground water at the
Koppers Coke site (Site) in St. Paul, Minnesota. The decision was chosen in accordance with
Minnesota Environmental Response and Liability Act (MERLA), Comprehensive Environmental
Response, Compensation, and Liability Act. (CERCLA), as amended by the Superfund
Amendments Reauthorization Act (SARA) and, to the extent practicable, the National Contingency
Plan (NCP). This decision is based on the administrative record file for this Site.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances for the Site, if not addressed by
implementing the response action selected in this Record of Decision (ROD), may present an
imminent and substantial endangennent to public health, welfare, and the environment.
DESCRIPTION OF THE SELECTED REMEDY
This ROD presents the selected remedial action for the ground water operable unit which is the
first of two operable units that are planned for the Site. The selected remedy is in-situ
bioremediation induced by enhanced oxygen delivery and the possible addition of nutrients to the
ground water. In this alternative, oxygen will be injected to the aquifer below the water table.
These injection points can also be used to introduce nutrients to the ground water if necessary to
promote bioreclamation; however, nutrient injection would require a variance to Minn. Rules
ch. 7060 from the Commissioner of the Minnesota Pollution Control Agency (MPCA), and a
variance to Minn. rules pt. 4725.2050 (Well Code) from the Director of the Division of
Environmental Health of the Minnesota Department of Health. Degradation of the contaminants
will prevent their moving off Site in the ground water.
A second ROD may be needed to address the soils operable unit. As part of the implementation of
the ground water remedial action the MPCA staff will require additional soil investigations of the
Site during well installation. The contaminated soils identified in initial investigations of the Site
were removed as part of the May 2, 1978, Air Quality Stipulation Agreement and during the
redevelopment of Energy Park. However, recent expansion of the First Banks/ETA Building on
Site encountered soil contamination. Therefore, there is reason to suspect that there may be
additional soil contamination that continues to affect ground water. If so, a soil ROD may be
necessary .

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STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment, complies \vith state and
federal requirements that are legally applicable or relevant and appropriate to the remedial action,
and is cost-effective. This remedy utilizes pennanent solutions and alternative treatment (or
resource recovery) technologies to the maximum extent practicable and satisfies the statutory
preference for remedies that employ treatment that reduces toxicity, mobility, or volume as a
principal element. .
This remedy is the preferred alternative but it does contain a contingency. Ground water extraction
will be added later if perfonnance monitoring data indicate this alternative by itself is not achieving
clean-up levels and/or preventing contaminant from moving off Site at concentrations exceeding the
clean-up levels. CE CLA five year reviews will be conducted until the contaminants in the ground
water have been ced to levels that provide protection of public health, welfare, and the
environment, complies with all applicable state and federal requirements.



Charles. Williams ~ ~

Commissioner
Minnesota Pollution Control Agency

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JRECOJIW OF DECiSION
DECRS!ON SUMMARY
FOR GROUND W A TJER REMEDIA TJION
FOIRMER lKOJ?JP>JERS COKE SITE
ST.PAUL,MJINNESOTA
SITE NAME. JLOCA nON. AND DESCRIPTION
The former Koppers Coke site (Site) is located in St. Paul, Ramsey County, Minnesota. The Site
is triangular in shape and includes an approximately 38 acre track of land in Section 27, T29N.
R23W, in the Midway Area/Energy Park District of St. Paul. The location of the Site is shown in
Figure I.
The Site is bounded on the east by Lexington Parkway with commercial development and
residential homes further to the east. The Site is bounded on the south by Burlington Northern
Railroad property and railroad tracks with light industrial development and residential homes
further to the south. Currently the northern boundary of the Site is located just north of Energy
Lane. Formerly it was bounded on the north by Rosen Road; a vacant strip of land and Liquid Air
Products, Inc. (Liquid Air). Energy Park Drive fOlmed the northern boundary of Liquid Air. To
the north of Energy Park Drive are apartments and condominiums and commercial development.
Th~ Site has been partially developed by the St. Paul Port Authority (Authority) as a commercial, .
residential, and industrial park, known as Energy Park. The structures in the Energy Park
development are shown in Figure 2.
No wetlands or surface-water areas are present at the Site with the exception of two small retention
ponds that were developed for dewatering purposes as a part of the expansion of the ETA/First
Bank building at the east end of the Site. Two surface water bodies are located near the Site.
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ground water. The primary contaminants detected as a result of this contamination include volatile
organic compounds (VOCs). semi-VOCs (SVOCs), polynuclear aromatic hydrocarbons (PAHs).
metals. and cyanide compounds.
The following Site features are considered the most significant potential sources areas of ground
water contamination at the Site:
I) OW-IO Area - West End Disposal Area
2) G-3 - Diesel fuel tank
3) Area 2 or OW-2 Area - Tank Farm Area
4) Area 7 - Spray Pond Area
5) Area 8 - Effluent Sump Area
6) Area 9 - Sump Area adjacent to Tank Farm
7) Area 10 - Gas Holders, Benzol Washers, and Final Coolers Area
8) Area II - Tar Storage Tanks and Flushing (Devil) Liquor Settling Basin
9) Area 12 - Naphthalene Pit
This Record of Decision (ROD) presents the selected remedial action for the ground water that has
been contaminated by the above sources. The ground water operable unit (OUl) is the first of two
potential operable units at the Site. The selected remedy for OU 1 is in-situ bioremediation induced
by enhanced oxygen delivery and the possible addition of nutrients to the ground water. In this
alternative. oxygen will be injected into the aquifer below the water table. These injection points
can also be used to introduce nutrients into the ground water, if necessary, to promote
bioremediation: however, nutrient injection may require a variance from current state rules. The
injection of oxygen and nutrients will encourage increased degradation of contaminants and prevent
them from moving off-Site in the ground water. Ground water extraction will be added later if
performance monitoring data indicate this alternative by itself is not achieving cleanup levels
and/or preventing contaminants from moving off-Site at concentrations exceeding the cleanup
levels. Please refer to the section labeled Selected Remedy for a complete discussion of this
remedy.
The second operable unit (OU2) would address soil contamination at the Site if necessary. From
1979 to 1986, during the demolition and development of the Site, it was believed that all the soil
contamination was removed. Table 2 (enclosed) lists remediation that was conducted. including
remediation of the source areas iisted above, as part of Site development. As indicated in Table 2, .
recent expansion of the ETA/First Banks Building encountered soil contamination. The
contaminated soil was remediated in accordance with the Minnesota Pollution Control Agency
(MPCA) staff requirements. However, these findings have caused the MPCA staff to question the
completeness of contaminated soil removal. As part of the implementation of the ground water
remedial action, the MPCA staff will require the RP to conduct additional soil investigations at the
Site. Depending on the outcome of the investigations, a ROD for OU2 mayor may not be
necessary .
Site History. On February L 1977, and May 2. 1978, Koppers and the MPCA entered into
Stipulation Agreements in order to correct air quality problems and investigate contamination at
the Facility. Koppers decided to cease operations at the Facility and demolish the structures rather
than make costly investments in air pollution control equipment to meet air quality standards as
required by the February I, 1977, Stipulation Agreement. Demolition was completed in
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October 1982: The May 2, 1978, Stipulation Agreement required Koppers to investigate the extent
and magnitude of soil and ground water contamination at the Site.
From May to September of 1979, during the demolition of the Facility, Koppers perfonned soil
and ground water investigations at the Site. The results of the investigation were presented in a
November 8, 1979, Hydrogeologic Study report, prepared by Koppers. The report identified soil
contamination associated with the spray pond sludge pit, flushing liquor settling basin and adjacent
tar sbdge pit, the naphthalene pit Sump adjacent to the benzol building and the tank fann area, and
the west end disposal area, as potential source areas of contamination (Areas 7, 11, 12,2, and
OW-IO, respectively). In addition, shallow ground water had been degraded with elevated
concentrations of phenol, oil and grease, ammonia and nitrate nitrogen, and cyanide.
While the investigations and demolition were occurring at the Site. the Authority began expressing
interest in purchasing and developing the Site as Energy Park. On April 29. 1982, the MPCA gave
tentative approval for limited Site development to take place. The MPCA staff was to be present
during grading and development so any contaminated soil discovered could be disposed of
properly. In October of 1982. the Authority purchased the Site. Under the tenns of the purchase
agreement the Authority agreed to stockpile contaminated soils encountered during development
and Koppers agreed to dispose of the stockpiled soils. During the development of Energy Park, the
Authority hired Soil Exploration Company, Inc., and Braun Engineering and Testing Inc, to
conduct additional subsurface investigations. These reports are available for review in the
Administrative Record. The Site investigations that lead to the removal of contaminated soil and
this ROD for ground water are discussed below.
The September 1992, Remedial Investigation (RI) report for the Site, prepared by Beazer provides
a good summary of past activities. Table 2 outlines the Summary of Remedial Actions at the Site.
As indicated in the RI report, Phase I of the demolition of the Facility began in May of 1979 with
the demolition of the coke battery and by-product processing areas and continued to January of
1980. During Phase 1,20,000 cubic yards of coal tar wastes and contaminated soil were excavated
and shipped to Chemical Waste Management (CWM) Landfill, an approved hazardous waste
landfill, in Calumet, Illinois. Koppers also shipped 2,500 cubic yards of lesser contaminated soil
to Total Asphalt of St. Paul for use as a road base material for Energy Park road construction.
In 1980, Koppers hired Geraghty & Miller, Inc., to study the extent of ground water contamination
at the Site. The investigation began in July of 1980 and was completed in December of 1980.
Results of the investigation were presented by Geraghty & Miller, Inc., in an April 1981,
Evaluation of Ground Water Conditions in the Unconsolidated Deposits report. The investigation
identified the benzol building, devil liquor settling basin and adjacent storage tanks, the area
immediately upgradient of spray pond/sludge pit, areas southeast of spray pond/sludge pit, tar
storage tanks on the western end of the Site, and the west end disposal area (Areas 10, 11, 7, 2;
and OW-IO, respectively) as potential source areas of ground water contamination. Ground water
samples collected from the unconsolidated deposits and the Decorah Fonnation were analyzed for
major cations and anions, and P AHs. The analysis confinned the presence of elevated
concentrations of these compounds in both the unconsolidated deposits and the Decorah Fonnation
aquifers.
Phase II of the Facility demolition began in November of 1980 with the demolition of the remaining
buildings, and continued until February of 1981. Underground pipes, demolition debris, and
foundations were also removed during this phase. Approximately 240,000 gallons of tar products
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from 20 tanks were removed. and 20,000 cubic yards of surface and subsurface soils were
excavated and shipped to CWM Landfill in Calumet Illinois.
On November 5. 1980. Koppers submitted the St. Paul Coke Plant West End Disposal Site
Investigation. According to the 1992 Rl report, 2,600 cubic yards of soil were determined to be
impacted by past releases. In 1981, the contaminated soils were excavated and disposed of in the
CWM Landfill or used in the road development in Energy Park Area..
From 1981 to 1983. at the request of the MPCA staff, a U.S. Environmental Protection Agency
(EP A) Remedial Planning/Field Investigation Team (REM/FIT) performed ground water
investigations to establish both vertical and lateral extent of contamination. This effort included
the installation and monitoring of off-Site wells. A draft REM/FIT report was submitted to the
MPCA in April of 1984. The report indicated that both on-Site and off-Site ground water was
contaminated with PAHs and VOCs.
During the Site Clearing and Grading Phase of the demolition project (1982-1983),85.000 cubic
yards of soil were excavated. The soil was visually screened to determine if it had been
contaminated by oil or tar, and was also checked for noticeable odor. Some contaminated soil was
shipped to the CWM Landfill, while the less contaminated soil was processed through an asphalt
plant. From July to September of 1982, an unknown volume of soil from the west end disposal
area of the Site (OW-IO Area) was excavated and some contaminated soil was shipped to the
CWM Landfill, while the less contaminated soil was processed through an asphalt plant. In
November of 1983, 3,500 cubic yards of contaminated soil from Area 2 and Area 9 were
processed through an asphalt plant. In 1983, 12.100 and 4,800 cubic yards of contaminated soil
were removed from the Area 7. Spray Pond. and Area 8. Effluent Sump, and shipped to the CWM
Landfill. Also in 1983. 360,000 cubic yards of soil were excavated from the Site, and soil visibly
contaminated by oil or tar was separated and stockpiled for later disposal at the CWM Landfill.
Uncontaminated soil was used as fill along Lexington Avenue in the eastern portion of the Site.
On July 30. 1982, the Site received a Hazardous Ranking System (HRS) score of 55.
Consequently, in September 1983. the Site was placed on the National Priority List. and the state
Permanent List of Priorities in October 1984.
During the Construction Phase, between September 1984 to February 1986, 3,235 cubic yards of
contaminated soil were exca:vated. The soil was visually screened to detennine if it had been
contaminated by oil or tar and was also checked for noticeable odor. Some contaminated soil was
shipped to the CWM Landfill, while the less contaminated soil was processed through an asphalt
plant.
On March 25, 1986, the MPCA Citizens' Board issued a Request for Response Action (RFRA) to
Koppers, to conduct a Remedial Investigation/Feasibility Study (Rl/FS) and implementation of a
Remedial Design/Response Action (RD/RA) Plan regarding contamination at the Site. The RFRA
described a series of actions necessary to further evaluate the ground water contamination and to
gather information in order to identify, assess, select. design, and implement response actions. The
RFRA also recognized the necessity for limited actions to gather additional information on
contaminated soils at the Site. A Consent Order was not successfully negotiated, so on
September 24, 1986, the MPCA staff requested Koppers to proceed under the schedule in the
RFRA.
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After issuance of the RFRA. Koppers conducted a series of soil and ground water investigations
for the development of the September 30. 1992. Rl/FS report. The data generated from ground
water investigations as well as investigative data collected prior to the issuance of the RFRA were
compared with current ground water standards that will be applied to the Site: I) Minnesota
Depan:ment of Health (MDH) Recommended Allowable Limits (RALs) for drinking water
contanlinants, 2) MDH Health Risk Limits (HRLs) for ground water, and 3) federal Maximum
Contaminant Levels (MCLs) for public water supplies. The HRLs supersede the RALs for
contanlinants having both criteria. The lowest of the numbers from the above categories is used as
the ground water cleanup level for the Site, as shown in Table 3. The RALs. HRLs, or MCLs
were exceeded in samples collected from on-Site Upper and Lower Glacial Unit monitoring wells
for the following contaminants: acetone. benzene. hexachloroethane, methylene chloride, bis(2-
ethylhexyl) phthalate, total carcinogenic PAHs (cPAHs), total noncarcinogenic PAHs (nPAHs),
trichloroethene, arsenic, beryllium (total), lead (total), nickel (total), and total and free cyanide.
Contaminants that have exceeded the RALs. HRLs. or MCLs in off-Site Upper or Lower Glacial
Unit monitoring wells are benzene. 1,2-dichloropropane, methylene chloride. bis(2-ethylhexyl)
phthalate, di-n-octyl phthalate. styrene. cP AHs, nP AHs, m-cresol. o-cresol, cyanide. arsenic,
chromium (total), lead (total). nickel (total). thallium. vanadium (total), and zinc. Ground water
analyt:cal data indicated that bis(l-ethylhexyl) phthalate. cP AHs, benzene, arsenic. chromium.
lead, zinc, and cyanide were detected at concentrations above the RALs, HRLs, or MCLs in
samples collected from the Platteville Fornlation manitoring wells. Ground water analytical data
indicated that bis(2-ethylhexyl) phthalate, cP AHs, dissolved arsenic and dissolved zinc (off-Site
upgradient well) were detected at concentrations above the RALs, HRLs, or MCLs in the S1. Peter
Sandstone monitoring wells. Additionally, cP AHs and nP AHs exceeding their respective water
quality criteria have been detected in a ground water sample collected from the up-gradient off-Site
S1. Peter Sandstone well, but no evidence suggests the contaminants originate from the Site. No
contanlinants were detected above the RALs. HRLs, or MCLs in samples collected from the
Prairie du Chien aquifer monitoring wells. Ground water analytical data indicated that cyanide and
arsenic were detected at concentrations above the RALs, HRLs, or MCLs in samples collected
from Lle M1. Simon Sandstone monitoring wells. The presence of cyanide was attributed to well
construction materials. MPCA staff consider the presence of arsenic in that sample to be
naturally-occurring.
Ground water monitoring, conducted after the Final R1/FS submittal, generated ground water
quality data that indicated only some of the contaminants discussed above have persisted on the
Site. 111 particular, water quality data indicate that benzene, cP AHs, nP AHs, arsenic, chromium,
lead, nickel, and cyanide are present on-Site in the ground water of the glacial aquifer. Water
quality data for the glacial aquifer off-Site indicate the presence of benzene, cP AHs, nP AHs,
arsenic, chromium, lead, nickel. zinc, and cyanide. The metals concentrations indicated total
metals analysis, except for some samples that contained dissolved arsenic and zinc. The bedrock
aquifers at the Site appear minimally impacted by the Site releases. The upgradient wells screened
in the Platteville Limestone (Well B-3) and the S1. Peter Sandstone (Well B-4) produced samples
containing cP AHs and nP AHs, which are not presently attributable to activities from the Site.
Data for the Platteville Limestone from samples collected from Well SW-3 are not considered
reliable, since the well, which is being abandoned, is not properly screened within that fonnation.
The remaining parameters detected in samples collected from the Platteville aquifer are total lead
and zinc, and total and dissolved arsenic. Bis(2-ethylhexyl)phthalate was detected in samples of
Platteville ground water in January 1992, but not during the October 1993 sampling round.
Continued ground water monitoring will be required to evaluate whether it presents a persistent
problem for the Site. Samples of ground water collected from the S1. Peter Sandstone aquifer
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contained dissolved and total arsenic. However, arsenic concentrations found in the ground water
of the St. Peter Sandstone. as well as the other aquifers. in the vicinity of the Site may be naturally
occumng.
As indicated above, on September 30, 1992, Beazer submitted a Final RI Report. On October 29,
1992, the MPCA staff approved the Final RI Report with modifications. The RI report presents
the source areas (Table 1) and the Constituents of Interest (COl) in the ground water.. The MPCA
staff revised the cor list and provided remediation levels for the COr. The cor and remediation
levels are shown on Table 3. It will be necessary for the RPs to achieve these clean-up levels in
order to obtain Site closure without restrictions. .
Given the extensive amount of soil remediation that occurred, the RI Report focused primarily on
the ground water. As indicated above, recent construction activity for the expansion of the First
Banks/ET A Building on-Site encountered soil contamination. This indicates that there is reason to
suspect that there may be additional soil contamination that continues to affect ground water.
Therefore, the MPCA staff has required Koppers to conduct additional soil investigations during
the implementation of the ground water treatment system. Once the soil investigation work is
complete, the MPCA staff will decide if a ROD for OU2 (soils) will be necessary.
On August 20, 1992, Twin City Testing submitted th~ Soil Disposal Assessment ReportJWork
Plan for the First Bank Expansion on the Site. Approximately three five-gallon buckets of soil
contaminated with a tar like substance were removed and are currently being stored on the First
Banks' property until an appropriate disposal method can be determined, Approximately 15,000
cubic yards of soil with low levels of contamination (below a level of concern) were placed in a
vacant area of the Site, adjacent to and west of the First Banks Building, and covered with 12
inches of clean soil.
On June 15, 1993, and October 22, 1993, Beazer submitted the Detailed Analysis Report (OAR)
and the Addendum to the OAR (OAR Addendum), respectively. On November 5, 1993, the
MPCA staff approved of the OAR and OAR Addendum with modifications. A more detailed
discussion of the OAR is given below in the Description of Alternatives Section.
HIGHLIGHTS OF COMMUNITY PARTICIPATION
The RI and OAR Report and the Proposed Plan for the Site were released to the public for
comment on November 15, 1993. These two documents were made available to the public in both
the administrative record at the MPCA and an information repository maintained at the EP A
Docket Room in Region V. The notice of availability for these two documents was published in
the St. Paul Pioneer Press on November 29, 1993, and the Midway Como Monitor on
December 9, 1993. A public comment period on the document was held from November 30, 1993,
to December 31, 1993. In addition, an availability session was held on December 16, 1993. At
this meeting representatives from the MPCA and a representative from Chester Environmental,
Beazer's consultant, were available to answer questions about problems at the Site and the remedial
alternatives. No one attended the availability session. Please see the Responsiveness Summary,
which is a part of this ROD, for more information. This decision document presents the selected
remedial action for the Site, which is chosen in accordance with MERLA, CERCLA, as amended
by SARA and, to the extent practicable, the National Contingency Plan (NCP). The ROD is based
on the administrative record.
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SCOPE AND ROLE OF OPERABLE UNIT
As indicated above. there are two operable units for this Site:
OU 1: Contaminated Ground Water
OU2: Contaminated Soil
This ROD presents the selected remedial action for ground water (OUl) that has been
contaminated by the source areas listed in Table 1. 111e selected remedy for the ground water is
in-situ bioremediation induced by enhanced oxygen delivery and the possible addition of nutrients
to the ground water. In this alternative, oxygen will be injected to the aquifer below the water
table. These injection points can also be used to introduce nutrients into the ground water if
necessary to promote bioremediation; however, nutrient injection may require a variance from
current state rules. Investiga~ions indicate that the glacial aquifer has been impacted by Site
releases, but do not conclusively indicate that the bedrock aquifers (Platteville Limestone and St.
Peter S"ndstone) have been impacted. However. continued monitoring of the ground water quality
at the Site will be used to evaluate whether those units are impacted by the Site, and if so, whether
remedial action is required. Additionally, because remediation of the drift aquifer involves the
introduc:tion of oxygen and nutrients. the natural flow of ground water will bring the oxygen and
nutrients to the bedrock aquifer thereby remediating the bedrock aquifers. should monitoring data
indicate that they are being impacted by the Site. 111e injection of oxygen and nutrients will also
encourage the increase in the degradation of the contaminants and prevent them from moving off-
Site in the ground water. Ground water extraction \\-ill be added later if performance monitoring
data indicate this alternative by itself is not achieving cleanup levels and/or preventing
contaminants from moving off-Site at concentrations exceeding the cleanup levels. Please refer to
the section labeled Selected Remedy for a complete discussion of this remedy.
The second operable unit (OU2) would address soil contamination at the Site if necessary. From
1979 to 1986, during the demolition and development of the Site, it was believed that all the soil
contamination was removed. Table 2 lists areas where soil remediation was conducted. However.
recent expansion of the First Banks/ETA Building on-Site encountered soil contamination. As part
of the implementation of the ground .water r.emedial action, the MPCA staff will require the RP to
conduct. additional soil investigations at the Site to evaluate whether additional soil contamination
continues to affect ground water. If so, a ROD for OU2 may be necessary.
SUMMARY OF SITE CHARACTERISTICS
Soil borings at the Site indicated the presence of 75 to 117 feet thick glacial outwash deposits
beneath the Site. The outwash is characterized as fine to medium grained sand and medium to
coarse grained sand, with gravel and cobbles and thin layers of silty clay. In some areas of the
Site. the glacial outwash deposits are underlain by the Oecorah Shale, which acts as an aquitard.
Where the Oecorah Shale is not present, the glacial outwash deposits are in contact with the
Platteville Formation.
Monitoring wells installed in the glacial deposits indicate that ground water in the glacial deposits
is up to 55 feet below ground surface. Ground water flow direction in the glacial outwash is
generally to the southeast. Ground water flow direction in the Platteville Formation is to the
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southeast and southwest. All ground water movement is in a downward direction at varying rates
depending on the presence of the Decorah Shale, which is an effective aquitard.
The storage and disposal practices along with the dumping of wastes on the land surface and
various operation leaks and spills resulted in contamination of both soil and ground water. The
primary contaminants detected as a result of this include VOCs, SVOCs, P AHs, metals, and
cyanide compounds. Table 3 lists the COI detected in each of these categories.
During the demolition and development of the Site, soil contamination was removed (Table 2) that
eliminated routes of potential exposure as well as a continued source for ground water
contamination. Recent expansion of the ETNFirst Banks Building encountered contaminated
soils. These soils were remediated in accordance with the MPCA staff requirements. These recent
findings have caused the MPCA staff to question the completeness of soil removal. Therefore,
additional soil investigations will be conducted to locate any additional potential sources. As
presented in this ROD, ground water remedial action will be necessary to address the ground water
contamination resulting from the above releases. The COI and remediation levels are shown on
Table 3. It will be necessary for the RPs to achieve these clean-up levels in order to obtain Site
closure without restrictions on the ground water.
SUMMARY OF SITE RISKS
Human Health Risks. On June 27, 1989, the MDH completed a Preliminary Health Assessment
for the Site. The health assessment concluded that the most significant potential human exposure
pathways associated with the Site are through use (ingestion, inhalation, and dermal contact routes)
of contaminated ground water. Residents in the area are connected to potable municipal water
supplies. However, there are three private (residential and commercial) wells near the Site that
show elevated concentrations of contaminants. These wells are not used for drinking water but
may occasionally be used for watering lawns and gardens. Current efforts have not identified any
additional users of ground water potentially impacted by the Site. However, the MDH is
evaluating whether other such users may exist. The RPs shall assist MDH in their efforts to
identify all users that may be impacted by Site releases. The RPs shall also identify the use and
sample all wells identified in the well search that may be impacted by the Site. Based on the results
of the sampling the MDH will determine whether actions are necessary to prevent exposure above
health based limits and nQtify well owners of their exposure. If necessary, the RPs shall implement
actions as directed by the MDH such as abandonment and alternative water supply such as city
hookup. Since at this time it has been detennined that well water in the area is not used for
drinking purposes, the only potential human exposure to contaminated ground water would be
through the use of non potable water for watering lawns and gardens.
The Human Health Risk Assessment, contained in the September 1992 Remedial Investigation
report for the Site, used monitoring data collected up to that time to evaluate potential
off-Site risks to human health. Benzene was determined to be the most significant contributor to
off-Site potential carcinogenic risks associated with the Site. The total potential carcinogenic risks
from exposure to off-S ite ground water exceeded the 10-5 reference risk level on the basis of the
ground water quality of the glacial unit as indicated by monitoring of Wells KC-3S and KC-5M.
The noncarcinogenic risk levels were most significantly impacted by dissolved arsenic, dissolved
zinc, and total cyanide in all water bearing zones, except for the Prairie du Chien Group and
Mt. Simon Sandstone aquifers. However, the hazard indices calculated were less than unity,
except for ground water in the Upper Glacial Well KC-3S, indicating that the ground water is
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generally safe and protective of public health from systemic toxic effects. Without a remedy in
place, continued monitoring will likely indicate changes in the ground water quality at those
off-Site locations. resulting in different risk level estimates. However, implementation of the
selected remedy will reduce carcinogenic and noncarcinogenic risks to within acceptable levels for
ground water on-Site and off-Site.
As indicated above. additional soil investigations will be conducted during the implementation
installation of the ground water treatment system. If soil contamination is encountered additional
risk evaluations will be necessary to detennine if soil cleanup is necessary.
Envir'onmental Risks. On July 15, 1992, Beazer submitted an Ecological Risk Assessment
(ERA) for the Site. The ERA concluded that on-Site surface water samples did not exhibit acute
toxicity to test organisms and therefore do not impact aquatic life. The ERA also concluded that
Site soil samples did not impair lettuce seed gennination and earthwonn survival indicating that
this pathway does not pose a threat to representative Site flora and fauna. Technical review of the
ERA by EP A staff concluded that ecological risk at the Site is likely small due to minimal
ecological habitat and the absence of acute toxicity.
DESCRIPTION OF AL TERNA TIVES
The June 1993, OAR and October 1993 OAR Addendum, prepared by Chester Environmental,
identified and evaluated 11 response alternatives (Table 4) that could be used to address current or
potential health or environmental threats at the Site. The numbers listed below are not consecutive
because there were five additional alternatives that did not pass initial screening for the OAR. The
followmg are the alternatives that were evaluated to remedy the ground water contamination
assoc:ated with the fonner Koppers facility:
Alternative I: No Action. This alternative involves taking no action to remediate the ground
water at the Site. This alternative is considered at all Superfund Sites to provide a baseline
comparison to the other alternatives considered. This alternative would not contain or treat
residual or dissolved contamination that is impacting the aquifer. 111e length oftime required to
meet the clean-up criteria for ground water under the No Action alternative is unknown, but the
ground water quality criteria is not expected to be achieved in a timely manner. This alternative
does lIot involve any remedial activities, or treatment. However, costs associated with monitoring
the Site over a 30-year period for benzene, P AHs, arsenic, cyanide., and zinc are estimated to be
$320,000.
Alternative 3: Ground Water Extraction. Pretreatment. In-Situ Bioremediation.
Rechan!:e/Sal1litarv Sewer Dischar2e. This alternative would provide hydraulic containment of
contaminated ground water on-Site through pumping from the surficial glacial aquifer using six
wells pumping approximately 250 gallons per minute (gpm). The extracted water would be
pretreated to remove floating substances, such as oils or suspended solids, if present. Pretreatment
may include pH adjustment, oiVwater separation, precipitation, and/or filtration. OiVwater
separation techniques may consist of gravity settling, slant rib coalescing separation, and/or
coagulation/flocculation, depending on the characteristics of the oil and water and on the discharge
limits specified for the individual contaminants. Following pretreatment, the discharge stream
would be split. Approximately 20 percent of the total flow (50 gpm) would be amended with
nutrients, such as nitrogen and phosphorus, and reinjected via three injection wells into the ground
to promote biological breakdown of the remaining contaminants. The remainder of the pretreated
9
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water (approximately 200 gpm) would be discharged to the Metropolitan Waste Control
Commission (MWCC) sanitary sewer system for fmal treatment. The estimated net present worth
cost of this alternative is $9,720,000.
Alternative 6: Ground Water Extraction, Pretreatment, Carbon Adsorotion,
Rechar~e/Sanitarv Sewer Dischar~e. This alternative would involve the extraction of
contaminated ground water using six wells pumping approximately 250 gpm. The water extracted
would be pretreated as discussed under Alternative 3, and the stream would be split, with
approximately 200 gpm of the total stream. discharged to the MWCC sanitary sewer system for
final treatment. The remainder of the discharge stream (approximately 50 gpm) would be treated
with granular activated carbon to remove remaining residual contamination and would be
reinjected into the aquifer through injection wells to partially replenish the extracted water. The
spent carbon would be tested for hazardous characteristics and, if necessary, would be properly
disposed or regenerated in a Resource Conservation and Recovery Act (RCRA) approved waste
management facility. Although this alternative provides hydraulic containment of the contaminated
ground water, it is not expected to accelerate remediation of the aquifer to achieve ground water
quality criteria in a timely manner. The estimated net present worth cost of this alternative is
$11,298,000.
Alternative 9: Ground Water Extraction, Pretreatment, and Dischar~e to Sanitary Sewer.
This method would extract ground water, as described in Alternatives 3 and 6, at a total discharge
of 200 gpm. The entire flow stream would be pretreated, using the methods described in
Alternative 3, so that MWCC pretreatment standards are met. All the pretreated water would be
discharged to the MWCC sanitary sewer system for final treatment. This alternative would
prevent contaminated ground water from migrating off-Site, but would not accelerate the
degradation of contaminants in the aquifer. The estimated net present worth cost of this alternative
is $12,522,000.
Alternative 10: Ground Water Extraction, Dischar~e to Sanitary Sewer. This alternative
involves extracting ground water at a total discharge of approximately 200 gpm. This alternative
is identical to Alternative 9, except that the extracted water would be discharged directly to the
MWCC sanitary sewer system without pretreatment. This alternative could be implemented if the
average concentrations in the total discharge stream are found to meet the MWCC pretreatment
standards without pretreatment. Although this alternative provides hydraulic containment of the
contaminated ground water, it is not expected to accelerate remediation of the aquifer to achieve'
ground water quality criteria in a timely manner. The estimated net present worth cost of this
alternative is $3,865,000. .
Alternative 11: Ground Water Extraction, Pretreatment, Carbon Adsorotion, In-Situ
Bioremediation, Rechar~e/Dischar~e to Sanitary Sewer. This alternative is a combination of
Alternatives 3 and 6. It would involve the extraction of approximately 250 gpm of contaminated
ground water, which would undergo pretreatment as described for Alternative 3, and also included
in Alternatives 6 and 9. Following pretreatment, the flow stream would be split, with
approximately 200 gpm being discharged to the MWCC sanitary sewer system for final treatment.
The remainder would be treated in a series of granular activated carbon adsorbers that would
remove residual organic constituents, and then would be amended with appropriate reagents and .
nutrients prior to reinjection into the aquifer through three weBs to promote bioremediation of the
aquifer. The spent carbon would be tested for hazardous characteristics and, if necessary, would
be properly disposed or regenerated in a RCRA-approved waste management facility. This
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alternative would provide containment of contaminated ground water and would remediate the
aquifer through bioremediation. The estimated net present worth cost of this alternative is
$10,250.000.
Alternative 12M: In-Situ Bioremediation. This alternative was proposed in the OAR
Addendum and involves the use of approximately 45 injection wells to deliver oxygen and, if
necessary, nutrients to the surficial glacial aquifer to promote the biological breakdown of
contaminants. The injection wells will be placed in systematic arrays throughout the Site in areas
where the contamination is highest, using ground water flow direction to optimize their effect.
Additionally, injection wells placed at the downgradient edge of the Site will provide a zone of
enhanced biological activity to ensure that contaminants do not migrate off-Site. Oxygen will be
delivered to the aquifer using sparging techniques. Field studies will determine if the addition of
nutrients is necessary and, if so, the types and loading rates required to promote in-situ
bioremediation. Ground water extraction will be added later if performance monitoring data
indicate this alternative by itself is not achieving cleanup levels and/or preventing contaminants
from moving off-Site at concentrations exceeding t ; cleanup levels. If ground water extraction is
found to be necessary, treatment and discharge options, similar to those in Alternatives 13, 14, and
15, will be evaluated as an addition to this system. TI1e estimated net present worth cost of
Alternative 12M is $2,255,000.
Alternative 13: Ground Water Extraction, Pretreatment, Dischar1!e to Sanitary Sewer,
Alonl! With In-Situ Bioremediation. This alternative is similar to Alternative 3, without recharge
to the aquifer. The contaminated ground water would be extracted with five pump-out wells at a
total approximate discharge of 200 gpm. The entire flow stream would be pretreated as described
under Alternative 3, and the entire effluent would be discharged to the MWCC sanitary sewer
system. A system of 20 injection wells would be used to introduce oxygen and appropriate
nutrients in periodic pulses to the aquifer to promote in-situ bioremediation of the ground water.
This alternative would contain contaminated ground water and would accelerate remediation of the
aquifi;r. The estimated net present worth cost of this alternative is $10,800,000.
Alternative 14: Ground Water Extraction and Dischan!:e to Sanitary Sewer Alon2 With
In-Situ Bioremediation. This alternative is identical to Alternative 10 with the addition of 20
injection wells to promote bioremediation. This alternative involves extracting ground water at a .
total discharge of approximately 200 gpm and discharging the water to the MWCC sanitary sewer
system without pretreatment, provided that concentrations in the total discharge stream are found
to meet the MWCC pretreatment standards. A system of 20 injection wells would be used to
introduce oxygen and appropriate nutrients in periodic pulses to the aquifer to promote in-situ
bioremediation of the ground water. This alternative would contain contaminated ground water
and would accelerate remediation of the aquifer. The estimated net present worth cost of this
alternative is $4,636,000.
Alternatiye 15: Ground Water Extraction, Pretreatment, Carbon Adsorption, and Dischan?:e
to Storm Sewer. This alternative would pump ground water from five wells at a total discharge of
200 gpm. The discharged water would be pretreated as described under Alternative 3, followed by
filtration through granular activated carbon. The water would then be discharged through a storm
sewer to the Mississippi River. The spent carbon would be tested for hazardous characteristics
and, if necessary, properly disposed or regenerated in a RCRA-approved waste management
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facility. This alternative would stop the off-Site migration of contaminated ground water, but
would not accelerate remediation of the aquifer to achieve ground water quality criteria in a timely
manner. The estimated net present worth cost of this alternative is $14,750,000.
Alternative 16: Ground Water Extraction. Pretreatment. Carbon Adsorotion, and Dischan!e
to Storm Sewer Alon2 With In-Situ Bioremediation. This alternative is identical to
Alternative 15 with the addition ofan in-situ bioremediation system as described under
Alternative 14. Ground water would be pumped from five wells at a total discharge of200 gpm,
and then pretreated as described under Alternative 3, followed by filtration through granular
activated carbon. The water would then be discharged through a storm sewer to the Mississippi
River. The spent carbon would be tested for hazardous characteristics and. if necessary, properly
disposed or regenerated in a RCRA-approved waste management facility. A system of 20 injection
wells would be used to introduce oxygen and appropriate nutrients in periodic pulses to the aquifer
to promote in-situ bioremediation of the ground water. This alternative would contain
contaminated ground water and would accelerate remediation of the aquifer. The estimated net
present worth cost of this alternative is $12.193,000.
SUMMARY OF THE COMPARATIVE ANAL YSIS OF AL TERNA TIVES
The following is a comparative analysis of the Alternatives based on nine evaluation criteria
presented in the NCP. The OAR uses the MPCA's criteria approach in place of the NCP nine
criteria approach. The MPCA criteria approach uses the same two threshold criteria that is used in
CERCLA to evaluate all of the alternatives. The MPCA then evaluates the passing alternatives
according to balancing criteria. The MPCA's balancing criteria are sufficiently similar to the
balancing and modifying criteria required in CERCLA cleanups. Below is MPCA's nine criteria
analysis of the alternatives. This analysis is sufficiently similar to the five criteria analysis
performed in the DAR. Therefore, the ROD will result in a CERCLA-quality cleanup. These nine
criteria are grouped into three categories: threshold criteria, primary balancing criteria, and
modifying criteria. The criteria and the comparative analysis of alternative are presented in the
following sections and summarized on Table 5.
A. ThreshoKd Criteria.
The threshold criteria includes the first two criteria, which are: I) overall protection of human
health and the environment, and 2) compliance with applicable or relevant and appropriate
requirements (ARARs).
The ARARs used for the Site are based on the requirements of CERCLA and the NCP as adopted
by EP A in March 1990, as well as state requirements under MERLA. Additional remediation of
ground water at the Site shall adhere to criteria established in other Minnesota statutes ,and rules
for protecting ground water in the state. The clean-up objectives are briefly discussed with respect
to the federal and state standards and criteria in the following paragraphs.
Minnesota Statutes. MERLA (Minn. Stat. 9115B (1992» identifies remedial actions as response
to a release to the environment and states that such actions be "consistent with a permanent remedy
taken... to prevent, minimize, or eliminate the release in order to protect the public health or
welfare or the environment" (Minn. Stat. 9115B.02, subd. 16 (1992». The Minnesota Water
Pollution Control Act (Minn. Stat. 9115.061 (1992» provides for protection of the waters of the
state by requiring the responsible person to "recover as rapidly and as thoroughly as possible such
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substance or material and take immediately such other action as may be reasonably possible to
minimize or abate pollution of waters of the state caused thereby."
MPCA may require and enforce a permit for any discharge to the waters of the state (Minn. Stat.
9 115.03). Discharge of extracted waters shall be conducted in accordance with a National
Pollutant Discharge Elimination System (NPDES) permit if it is discharged to the Mississippi
River via a storm sewer pursuant to Minn. Stat. 9 115.03 (1992). Discharge of extracted waters to
the MWCC sanitary sewer system for final treatment shall be subject to the discretion and
approval of MWCC, which must adhere to Minnesota statutes and rules for discharge to the
Mississippi River. .
Minnl~sota Rules. Under its broad statutory authority to protect the quality of water of the state,
the MPCA has adopted general policies and standards for the protection of ground water from
pollution under Minn. Rules ch. 7060 (1991), which were promulgated "to preserve and protect the
underground water of the state by preventing any new pollution and abating existing pollution"
(Minn. Rules pt. 7060.0100). Minn. Rules pt. 7060.020~ states, "It is the policy of the agency to
consider the actual or potential use of the underground waters for potable water supply as
constituting the highest priority use and as such to provide ma.ximum protection to all underground
waters. The ready availability nearly statewide of underground water constitutes a natural
resource of immeasurable value which must be prorected as nearly as possible in its natural
condition. For the conservation of underground water supplies for present and future generations
and prevention of possible health hazards, it is necessary and proper that the agency employ a
nondegradation policy to prevent pollution to the underground waters of the state."
Minn. Rules pt. 7060.0400 provides that "all underground waters are best classified for use as
potable water supply in order to preserve high quality waters by minimizing spreading of
pollutants, by prohibiting further discharges of wastes thereto, and to maximize the possibility of
rehabilitating degraded waters for their priority use." Minn. Rules pt. 7060.0600 provides
standards relevant to contamination of the saturated and unsaturated zones. Subpart I prohibits
discharge of pollutants to the saturated zone and subpart 2 prohibits the discharge of pollutants to
the unsaturated zone. Subpart 2 states that. "No sewage, industrial waste, other waste. or other
pollutants shall be allowed to be discharged to the unsaturated zone or deposited in such place.
manne:r. or quantity that the effluent or residue therefrom, upon reaching the water table, may
actually or potentially preclude or limit the use of the underground water as a potable water
supply, nor shall any such discharge or deposit be allowed which may pollute the underground
waters." Finally, Subpart 3 provides that, "Treatment, safeguards, or other control measures shall
be provided by the person responsible for any sewage, industrial waste, other waste, or other
pollutants which are to be or have been discharged to the unsaturated zone or deposited there, or
which have been discharged to the zone of saturation, to the extent necessary to ensure that the
same will not constitute or continue to be a source of pollution of the underground waters or impair
the natural quality thereof."
Minn. Rules pt. 7050 classifies surface waters of the state and provides water quality standards for
these classified waters. Discharge of extracted ground water to the Mississippi River (main use
classified as 2B--for fisheries and recreational use) shall adhere to the water quality standards
estabEshed in this rule for Class 2B surface waters. Additionally, direct discharge via storm sewer
shall be regulated under an NPDES permit. Discharge to the MWCC sanitary sewer system will
require that MWCC pretreatment standards are achieved prior to discharge to ensure that final
treatment is compatible with the discharge standards of this rule.
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The HRLs are promulgated by the MDH as Minn. Rules pts. 4717.7100 to 4717.1800. HRLs are
applicable to ground water cleanup and are based on the risk associated with ingestion of water
ITom a private well. HRLs replace nonpromulgated RALs where both exist for a contaminant as
HRLs are based on more recent risk infonnation and are promulgated. Also, HRLs, at present, are
based only on risk data available in the IRIS data base.
Federal Statutes. CERCLA was amended by the Superfund Amendments and Reauthorization
Act of 1986 (SARA), which added Section 121 to CERCLA. which provides some specific
cleanup requirements. Among the changes is the preference for pennanence in selecting a remedy
and the use of applicable or relevant and appropriate requirements.
The Resource Conservation and Recovery Act (RCRA), passed in 1976 and amended by the
Hazardous and Solid Waste Amendments in 1984, is an amendment to the Solid Waste Disposal
Act of 1965, and is intended to ensure that solid wastes are managed in an environmentally sound
manner. The objectives of RCRA are to protect human health and the environment, reduce waste
and conserve energy and natural resources, and reduce or eliminate the generation of hazardous
waste as expeditiously as possible. Subtitle C of RCRA establishes Land Disposal Restrictions
(LDRs), which restrict the land disposal of RCRA hazardous wastes, and would apply to any
hazardous waste or medium containing a listed hazardous waste that is moved off-Site for
treatment, disposal, or storage.
Federal Rules. The NCP implements the requirements of CERCLA Section 121 for using
ARARs, as well as other standards and criteria, to guide cleanup decisions at Superfund Sites
where EP A or the state under a cooperative agreement with EP A exercises cleanup authority.
The NCP defines the "relevant and appropriate requirements" portion of the ARARs as being
"those cleanup standards, standards of control, and other substantive requirements, criteria, or
limitations promulgated under federal environmental or state environment or facility siting laws
that, while not "applicable" to a hazardous substance, pollutant, contaminant, remedial action,
location, or other circumstances at a CERCLA site, address problems or situations sufficiently
similar to those encountered at the CERCLA site that their use is well-suited to the particular site.
Only those state standards that are identified in a timely manner and are more stringent than federal
requirement may be relevant and appropriate" (40 CFR 300.5 (1990».
The federal MCLs (40 CFR 141 - 143) promulgated by the U.S. Environmental Protection
Agency are health and treatment based numbers for regulating public water supplies.
To Be Considered. The RALs, Minnesota Department of Health (MDH), Release No.3,
January 1991, are not promulgated standards and, therefore, are not considered applicable or
relevant and appropriate requirements (ARARs). However, the RALs may be included in the
category of "to be considered" guidance. This category includes criteria, advisories, and proposed
standards issued by federal or state governments that are relevant because they address
circumstances sufficiently similar to those at this Site and their application is well suited in
determining whether response actions are reasonable and necessary to protect the public health and
welfare, or the environment. RALs use infonnation ITom the Integrated Risk Infonnation System
(IRIS) and HEAST data bases as well as other references and are used for detennining the risk
associated with ingestion of water ITom a private well. Water quality cleanup levels will be
consistent with MCLs and HRLs/RALs, whichever is lower for a specific contaminant.
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The 11 remediation alternatives considered for the Site were evaluated using the Threshold Criteria
as follows:
Alternative 1: No Action. This alternative does not protect human health or the environment.
This alternative will neither contain or treat the contaminants from the Facility that have impacted
the ground water. This alternative does not comply with ARARs.
Alternative 3: Ground Water Extraction. Pretreatment. In-Situ Bioremediation.
Rechar~e/Sanitary Sewer Dischan!e. The remedial activities prescribed under this remedy
provides hydraulic containment of contaminated ground water on-Site, and reduces the
contaminant levels through in-situ bioremediation. This alternative protects human health and the
environment by preventing further off-Site migration of contamination and treating the e~'tracted
ground water. Although contaminant concentrations would be reduced through in-situ
bioremediation, the proposed system using three injection wells is not expected to provide the areal
coverage to remediate the entire Site. Therefore, contaminant levels in the ground water are not
expected to be reduced throughout the Site to levels that comply with ARARs. In addition.
implem(~nting the in-situ bioremediation may require variances from MPCA and MDH for injection
into the aquifer.
Alterml1tive 6: Ground Water Extraction. Pretreatment. Carbon Adsorption.
Rechar2e/Sanitary Sewer Dischar2e. This alternative provides hydraulic containment of
contaminated ground water on-Site. This alternative protects human health and the environment by
preventing further off-Site migration of contamination and treating the extracted ground water, but
does not reduce the contamination concentration levels in the ground water. It does not comply
with AltARs, since it fails to treat the residual and dissolved contaminants in the ground water. In
addition, implementing recharge may require variances from MPCA and MDH for injection into
the aquifer.
Alternative 9: Ground Water Extraction. Pretreatment. and Dischar2e to Sanitarv Sewer.
As with Alternative 6. this alternative provides hydraulic containment of contaminated ground
water on-Site. It protects human health and the environment by preventing further off-Site
migrati0n of contamination and treating the extracted ground water, but does not reduce the
contamination concentration levels in the ground water. It does not comply with ARARs. since it
fails to treat the residual and dissolved contaminants in the aquifers.
Alternative 10: Ground Water Extraction. Dischar2e to Sanitary Sewer. As with
Alternatives 6 and 9, this alternative provides hydraulic containment of contaminated ground water
on-Site. It protects human health and the environment by preventing further off-Site migration of
contamination and treating the extracted ground water, but does not reduce the contamination
concentration levels in the ground water. It does not comply with ARARs, since it fails to treat the
residual and dissolved contaminants in the aquifers.
Alternative 11: Ground Water Extraction. Pretreatment. Carbon Adsorption. In-Situ
Bioremediation. Rechar2e/Dischar2e to Sanitary Sewer. Because this alternative is essentially
the same as Alternative 3, except that granular activated carbon is included in the treatment train
for the extracted water, it satisfies'the threshold criteria used to evaluate the various alternatives.
The pump-out system provides hydraulic containment of contaminated ground water on-Site, and
in-situ bioremediation reduces the contaminant levels within the aquifers. This alternative protects
15
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human health and the environment by preventing further off-Site migration of contamination and
treating the extracted ground water. Although contaminant concentrations would be reduced
through in-situ bioremediation, the proposed system using three injection wells is not expected to
provide the areal coverage to remediate the entire Site. Therefore, contaminant levels in the ground
water are not expected to be reduced throughout the Site to levels tha.t comply with ARARs.
Implementing the in-situ bioremediation may require variances from MPCA and MDH for injection
into the aquifer.
Allfl:~IrlIJJative 12M: In-Situ Bioremediation. This alternative treats contamination in-place by
supplying oxygen and the appropriate nutrients, if necessary, to the aquifers. Since off-Site
migration of contaminants will be tenninated by an array of injection wells at the downgradient
property boundary, this alternative is protective of human health and the environment. Moreover,
if the system does not function as expected. and contaminants continue to migrate off-Site. a
ground water extraction system shall be implemented to provide hydraulic containment of
contaminated ground water. The use of in-situ bioremediation to reduce the contaminant
concentrations to below water quality criteria further protects human health and the environment
and also complies with ARARs. Variances may be required from MPCA and MDH for injection
wells if nutrients are required to enhance the bioremediation process.
AltelJ"l1Iative 13: Ground Water Extraction. Pretreatment. Dischar~e to Sanitary Sewer.
Almu! With In-Situ Bioremediation. This alternative provides hydraulic containment of
contaminated ground water, followed by treatment of the extracted ground water. In-situ
bioremediation is implemented through a system of 20 injection wells that would be used to
introduce oxygen and appropriate nutrients in periodic pulses to the aquifer to promote in-situ
bioremediation of the ground water. Although contaminant concentrations would be reduced
through in-situ bioremediation, the proposed system is not expected to provide the areal coverage
to remediate the entire Site, because of the very limited influence of each of the injection points.
Therefore. contaminant levels in the ground water are not expected to be reduced throughout the
Site to levels that comply with ARARs. Implementing the in-situ bioremediation may require
variances from MPCA and MDH for injection into the aquifer. The hydraulic containment of the
ground water would make this alternative somewhat protective of human health and the
environment. However. it is not as protective as it could be if it had an adequate in-situ
bioremediation program. Additionally, since it lacks an adequate means to reduce contaminant
concentrations in the ground water, this alternative does not comply with ARARs.
AJternative 14: Ground Water Extraction and Dischar2e to Sanitary Sewer Alon~ With In-
Situ! Bnoremediation. As with Alternative 10, this alternative provides hydraulic containment of
contaminated ground water on-Site; It protects human health and the environment by preventing
further off-Site migration of contamination and treating the extracted ground water through the
MWCC sanitary sewer system, but does not adequately reduce the contamination concentration
levels in the ground water throughout the Site. The in-situ bioremediation system is the same as
that proposed in Alternative 13, and as such, is not considered adequate to comply with ARARs,
since it fails to provide an effective reduction in contaminant concentrations in the ground water.
In addition, implementing the in-situ bioremediation may require variances from MPCA and MDH
for injection into the aquifer. .
Allfi:elJ"Inative i5: Ground Water Extraction. Pretreatment. Carbon Adsorotion. and Dischar2e
to Sfl:mrl!!l11 Sewer. This alternative would protect human health and the environment by preventing
further off-Site migration of contamination and treating the extracted ground water, but would not
16
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reduce the contamination concentration levels in the ground water. It does not comply with
ARARs, since it fails to treat the residual and dissolved contaminants in the aquifers.
Alternative 16: Ground Water Extraction. Pretreatment. Carbon Adsorption. and Dischar!!e
to Storm Sewer Alon!! With In-Situ Bioremediation. This alternative would provide hydraulic
containment of contaminated ground water and treat and discharge the pumped water as described
under AI:ernative 15. However, the in-situ bioremediation system is the same as that proposed in
Alternatives 13 and 14. and as such, is not considered adequate to comply with ARARs, since it
fails to provide an effective reduction in contaminant concentrations in the ground water. In
addition, implementing the in-situ bioremediation may require variances from MPCA and MDH
for injection of nutrients into the aquifer.
Summary of Threshold Criteria.
Only those alternatives that stop off-Site migration of contaminants in ground water, and reduce
the contaminant concentrations within the aquifers to below. ground water quality criteria are fully
protective of human. health and the environment and comply \\ith-ARARs. Off-Site migration of
contaminants can be achieved through hydraulic containment using a ground water extraction
system, or through a "microbial fence," which is comprised of an array of injection points that
provide oxygen and possibly nutrients to the aquifer so that contaminants within the ground water
flowing through it are biodegraded. The only alternative that is practical to implement for reducing
conta.l11i&ant concentrations within the ground water is bioremediation.
The alternatives that include ground water extraction and/or bioremediation include Alternatives 3,
II, 12M. 13. 14, and 16. However, Alternatives 3 and II implement bioremediation through three
injection wells, which are not considered to provide adequate areal hydraulic coverage for
effective:y implementing bioremediation throughout the entire Site. Similarly, Alternatives 13, 14,
and 16 are based on bioremediation systems comprised of 20 injection points through which
oxygen and nutrients are periodically pulsed. Contaminant concentrations are not expected to be
reduced throughout the Site because the proposed system is not expected to remediate the entire
Site, owing to the very limited influence of each of the injection points.
However, Alternative 12M, bioremediation using approximately 45 injection points. is expected to
provide adequate areal distribution of oxygen and, if necessary, nutrients to the impacted ground
water. Flexibility in this alternative will allow expansion of the injection point network, if
necessary. Additionally, a ground water extraction system will be implemented as a contingency if
bioremediation alone does not stop the off-Site migration of contamination in ground water. This
alternative is protective of human health and the environment. and reduces the contaminant
concentrations to levels that comply with ARARs.
The use of injection wells in the aquifer proposed by Alternatives 3, 6, 11, 13. 14, and 16 would
require variances from the MPCA and MDH. Specifically, the Commissioner of the MPCA must
grant a variance to Minn. Rules ch. 7060, and the Director of the MDH Division of Environmental
Health must grant a variance to Minn. Rules pt. 4725.2050. Alternative 12M would require a
similar variance if, in addition to oxygen, nutrients or other reagents are introduced into the
aquifer.
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B. Primary Balancinl! Criteria
The five primary balancing criteria are: I) long-term effectiveness and permanence: 2) reduction of
toxicity, mobility, or volume through treatment: 3) short-term effectiveness; 4) implementability;
and 5) cost. Of these, the first two, long-term effectiveness and permanence and reduction of
toxicity, mobility, or volume through treatment, receive the most emphasis of the balancing criteria
in evaluating remedial alternatives. The 11 remediation alternatives considered for the Site were
evaluated using the Primary Balancing Criteria as follows:
AJ~elJ"lf1l21\1:nviC 1: No Action. This alternative does not provide long-term effectiveness or a
permanent solution for remediating the contaminated ground water. It does nothing to reduce the
toxicity, mobility, or volume of the contamination through treatment. It is not effective in the short
term. However. ~ecause no action would be taken. it is readily implemented. This alternative is
considered the no-cost alternative for addressing ground water contamination. However. costs
associated with ground water monitoring at the Site over a 30-year period are estimated to be
$320.000.
A~~elJ"lf1la~nve 3: Ground Water Extraction, Pretreatment, In-Situ Bioremediation,
RetJrnalJ"$!:e/Sanitarv Sewer Dischar2e. In-situ bioremediation is considered effective in providing
long-term effectiveness and permanence, and in reducing the toxicity, mobility, and volume of the
contamination at the Site. However, the bioremediation system as proposed with three injection
wells is not considered adequate to remediate the entire Site. The alternative would be effective in
the short term by preventing the off-Site migration of contaminants in ground water. This
alternative uses standard methods that can be readily implemented. However, implementation of
this alternative will require approval from MWCC to discharge into the sanitary sewer system, as
well as making the connection to the system. The estimated net present worth cost pf this
alternative is $9,720,000.
AI~e!J"l!1la~nve 6: Ground Water Extraction, Pretreatment, Carbon Adsorption,
lRed1l2llJ"ge/Sanitarv Sewer Discharl!e. This alternative does not provide an effective long-term or
permanent solution, because it fails to reduce the toxicity, mobility, or volume of the contaminants
within the aquifer. It is effective in the short term. since it stops off-Site migration of contaminated
ground water through hydraulic containment. This alternative uses standard methods that can be
readily implemented. However, implementation of this alternative will require approval from
MWCC to discharge into the sanitary sewer system. as well as making the connection to the
system. Additionally, the use of carbon adsorption transfers the contamination from the ground
water to granular activated carbon, which would require off-Site treatment or disposal. Disposal
or treatment of the spent carbon will De in accordance with RCRA and LDRs if it is determined to
be hazardous. The estimated net present worth cost oftrus alternative is $11,298,000.
AhelJ"If1l2l~nve 9: Ground Water Extraction, Pretreatment, and Dischar2e to Sanitary Sewer.
The solution offered by this alternative is neither effective in the long term or permanent, because it
fails to reduce the toxicity, mobility, or volume of the contaminants within the aquifer. It is
effective in the short term, since it stops off-Site migration of contaminated ground water through
hydraulic containment. The standard techniques proposed in this alternative can be readily
implemented. However, implementation of this alternative will require approval from MWCC to
discharge into the sanitary sewer system, as well as making the connection to the system. The
estimated net present worth cost of this alternative is $12,522,000.
18
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Alternative 10: Ground Water Extraction, Dischan!e to Sanitary Sewer. This alternative is
neither effective in the long term or permanent, because it fails to reduce the toxicity, mobility, or
volume of the contaminants within the aquifer. It is effective in the short term. since it stops
off-Site migration of contaminated ground water through hydraulic containment. The standard
techniques proposed in this alternative can be readily implemented. As with Alternatives 3, 6, and
10, implementation of this alternative will require approval from MWCC to discharge into the
sanitary sewer system, as well as making the connection to the system. The estimated net present
worth cost of this alternative is $3,865.000.
Alternative 11: Ground Water Extraction, Pretreatment, Carbon Adsorption, In-Situ
Bioremediation, Rechan!e/Dischan!e to Sanitary Sewer. As explained under Alternative 3,
in-situ bioremediation is considered effective in providing long-term effectiveness and permanence,
and in reducing the toxicity, mobility, and volume of the contamination at the Site. However, as
with Alternative 3, the bioremediation system as proposed is not considered adequate to remediate
the entire Site. The alternative would be effective in the short term by preventing the off-Site
migration of contaminants in ground water. This alternative uses standard methods that can be
readily implemented, but will require approval from MWCC to discharge water into the sanitary
sewer system, as well as to make the connection to the system. Additionally, the spent granular
activated carbon would require off-Site treatment or disposal in accordance with RCRA and LDRs
if it is determined to be hazardous. The estimated .net present worth cost of this alternative is
$10,250,000.
Alternative 12M: In-Situ Bioremediation. By remediating the contamination in the aquifers
through in-situ bioremediation, this alternative offers long-term effectiveness and permanence, and
reduces the toxicity, mobility, and volume of the contaminants. It offers short-term effectiveness
by stopping the off-Site migration of contaminants in ground water. Ground water extraction will
be added later if performance monitoring.data indicate this alternative by itself is not achieving
cleanup levels and/or preventing contaminants from moving off-Site at concentrations exceeding
the cleanup levels. Please refer to the section labeled Selected Remedy for a complete discussion of
this remedy. The estimated net present worth cost of this alternative is $2.255,000.
Alternative 13: Ground Water Extraction, Pretreatment, Dischan!e to Sanitary Sewer,
Alonf! With In-Situ Bioremediation. In-situ bioremediation is considered effective in providing
long-term effectiveness and permanence, and in reducing the toxicity, mobility, and volume of the
contamination at the Site. However, ~plementation of in-situ bioremediation of the ground water
through a system of 20 injection wells to introduce oxygen and appropriate nutrients in periodic
pulses to the aquifer is not considered adequate to remediate the entire Site. Therefore, this
alternative is considered to be neither effective in the long term or permanent. However, it does
adequately reduce the mobility, toxicity, or volume of contaminants through treatment. Ground
water c:xtraction would be effective in stopping off-Site migration of ground water in the short.
term. This alternative uses standard methods that can be readily implemented. However,
implementation of this alternative will require approval from MWCC to discharge into the sanitary
sewer system, as well as making the connection to the system. The estimated net present worth
cost of this alternative is $10,800,000.
Alternative 14: Ground Water Extraction and Discharf!e to Sanitary Sewer Alonf! With
In-Situ Bioremediation. As described under Alternative 13, implementation of this alternative,
which uses a system of 20 injection wells to introduce oxygen and appropriate nutrients in periodic
pulses to the aquifer, is not considered adequate to remediate the entire Site. Therefore, this
19
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alternative is neither effective in the long tenn or pennanent. because it fails to reduce the toxicity.
mobility, or volume of the contaminants within the aquifer. It is effective in the short tenn, since it
stops off-Site migration of contaminated ground water through hydraulic containment. The
standard techniques proposed in this alternative can be readily implemented. However, its
implementation will require approval from MWCC for connection and discharge into the sanitary
sewer system. The estimated net present worth cost of this alternative is $4,636,000.
Alternative 15: Ground Water Extraction, Pretreatment. Carbon Adsorotion, and Dischar~e
to Storm Sewer. This alternative does not provide an effective long-tenn or pennanent solution,
because it fails to reduce the toxicity, mobility, or volume of the contaminants within the aquifer.
However, it is effective. in the short tenn, owing to the hydraulic containment that stops
contaminated ground water from moving off-Site. This alternative uses standard methods that can
be readily implemented, but will require an NPDES pennit to discharge the water to the
Mississippi River via the stonn sewer. Additionally, the use of carbon adsorption transfers the
contamination from the ground water to granular activated carbon requiring its off-Site treatment
or disposal, which must be in accordance with RCRA and LDRs if the material is detennined to be
hazardous. The estimated net present worth cost of this alternative is $14,750,000.
Alternative 16: Ground Water Extraction, Pretreatment, Carbon Adsorotion, and Dischar~e
to Storm Sewer Alon~ With In-Situ Bioremediation. Similar to Alternatives 13 and 14, this
alternative proposes an in-situ bioremediation system that is not considered adequate to remediate
the entire Site. Therefore, this alternative would not provide a remedy that is effective in the
long-tenn or pennanent. because it fails to reduce the toxicity, mobility, or volume of the
contaminants within the aquifer. However, it is effective in the short tenn, since the ground water
extraction system would stop off-Site migration of contaminated ground water. This alternative
uses standard methods that can be readily implemented but. as with Alternative 15, it will require
an NPDES pennit to discharge the water to the stonn sewer. Additionally, the spent carbon would
require off-Site treatment or disposal, which must be in accordance with RCRA and LDRs if it is
detennined to be hazardous. The estimated net present worth cost of this alternative is
$12,193,000.
Summarv of Primary Balancin!! Criteria.
In-situ bioremediation can provide long-tenn effectiveness and pennanence, as well as a reduction
in toxicity, mobility, or volume of contaminants through biodegradation of the contaminants within
the aquifer. The alternatives that include ground water extraction and/or bioremediation include
Alternatives 3, II, 12M, 13, 14, and 16. However, Alternatives 3 and 11 implement
bioremediation through three irtjection wells, which are not believed to provide adequate areal
hydraulic coverage for effectively implementing bioremediation throughout the entire Site.
Similarly, Alternatives 13, 14, and 16 are based on bioremediation systems comprised of20
injection points through which oxygen and nutrients are periodically pulsed. Contaminant
concentrations are not expected to be adequately reduced for these alternatives because they are not
expected to remediate the entire Site, owing to the very limited influence of each of the injection
points. However, Alternative 12M, bioremediation using approximately 45 injection points is
expected to provide adequate areal distribution of oxygen and, if necessary, nutrients to the
impacted ground water, and is expected to provide a remedy that is pennanent and effective over
the long tenn. Additionally, Alternative 12M will reduce the toxicity, mobility, and volume of
contaminants in the ground water by treatment through in-situ bioremediation.
20
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ShorHenn effectiveness occurs by stopping contamination from migrating with ground water
off-Site. and would be achieved by all the alternatives except Alternative L the No Action
alternative. Alternative 12M would stop contamination migration by ensuring adequate
biorer.'1ediation in the ground water occurs before it moves off-Site. The remaining alternatives
provide effectiveness in the short tenn by hydraulically containing the contaminated ground water
through ground water extraction. .
All the alternatives use standard techniques that can be readily implemented. However, MWCC
approval would be required to implement the discharge to the sanitary sewer as proposed in
Alternatives 3. 6, 9. 10, 11, 13, and 14. An NPDES pennit would be required for Alternatives 15
or 16 to allow discharge of water into the Mississippi River via the stonn sewer system. The use
of granular activated carbon adsorption in Alternatives 6, 11, 15, and 16 would require off-Site
treatment or disposal of the spent carbon in accordance with RCRA and LDRs if it is detennined
to be hazardous.
The costs of the alternatives range from $320,000 to cover monitoring costs for the No-Action
scenario of Alternative 1 to $14,750,000 for Alternative 15 (Ground water Extraction,
Pretreatment, Carbon Adsorption, and Discharge to Stonn Sewer). Pretreatment and the use of
granular activated carbon to treat extracted ground water clearly increase the overall cost in the
alternatives. The next lowest cost is for Alternative 12M (In-Situ Bioremediation), since it does
not involve ground water extraction. pretreatment. and discharge. Although alternatives other than
the selected remedy will also remediate the aquifer, those involving ground water extraction will
entail costs that do not offer additional protection of human health or the envirorunent over the
selected alternative. Therefore, Alternative 12M, the lowest cost alternative that will actually
remediate ground water impacted by the Site. is considered the most cost-effective.
C. Modifvin2 Criteria
Two modifying l.citeria were used to evaluate the II alternatives: I) community acceptance and
2) state acceptance. The analysis of community acceptance is based on the lack of comments
during the comment period and at the public availability meeting. The lack of opposition to the
preferred alternative presented by the MPCA in the Proposed Plan is interpreted to be implicit
support for the MPCA staffs position regarding the choice of remedial action at the Site. State
acceptance is based on the position of the MPCA. The 11 remediation alternatives considered for
the Site were evaluated using the Modifiying Criteria as follows:
Alternative 1: No Action. This alternative is not acceptable to the community or to the state.
Alternative 3: Ground Water Extraction. Pretreatment. In-Situ Bioremediation.
Rechar2e/Sanitarv Sewer Dischar2e. This alternative provides a method of stopping the off-Site
migration of contaminated ground water that is acceptable to the community and the state.
However, the in-situ bioremediation. as designed, fails to adequately degrade the ground water
contaminants throughout the Site and, therefore, is not considered acceptable to the community or
the stite.
Alternative 6: Ground Water Extraction. Pretreatment. Carbon Adsorption,
Rechar2e/Sanitarv Sewer Dischar2e. This alternative is not acceptable to the state, since it fails
to remediate the aquifer.
21
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Alternative 9: Ground Water Extraction, Pretreatment, and Dischan.!e to Sanitary Sewer.
This alternative is not acceptable to the state, since it fails to remediate the aquifer.
Alternative 10: Ground Water Extraction, Dischan!e to Sanitary Sewer. This alternative is
not acceptable to the state, since it fails to remediate the aquifer.
Alternative 11: Ground Water Extraction, Pretreatment, Carbon Adsorption, In-Situ
Bioremediation, Rechar2:e/Dischan!eto Sanitary Sewer. This alternative provides a method of
stopping the off-Site migration of contaminated ground water that is acceptable to the conununity
and the state. However, the in-situ bioremediation, as designed, fails to adequately degrade the
ground water contaminants throughout the Site and. therefore. is not considered acceptable to the
community or the state.
Alternative 12M: In-Situ Bioremediation. This alternative is acceptable to the community and
the state.
Alternative 13: Ground Water Extraction, Pretreatment, Discharl?:e to Sanitarv Sewer,
Alon2: With In-Situ Bioremediation. This alternative provides a method of stopping the off-Site
migration of contaminated ground water that is acceptable to the community and the state.
However, the in-situ bioremediation. as designed, fails.to adequately degrade the ground water
contaminants throughout the Site and, therefore, is not considered acceptable to the conununity or
the state.
Alternative 14: Ground Water Extraction and Dischan!e to Sanitary Sewer Alon~ With
In-Situ Bioremediation. This alternative provides a method of stopping the off-Site migration of
contaminated ground water that is acceptable to the conununity and the state. However, the in-situ
bioremediation, as designed, fails to adequately degrade the ground water contaminants throughout
the Site and, therefore, is not considered acceptable to the community or the state.
Alternative 15: Ground Water Extraction, Pretreatment, Carbon Adsorption, and Dischar~e
to Storm Sewer. This alternative is not acceptable to the state, since it fails to remediate the
aquifer.
Alternative 16: Ground Water Extraction, Pretreatment, Carbon Adsorption, and Dischar2:e
to Storm Sewer Alon~ With In-Situ Bioremediation. This alternative provides a method of
stopping the off-Site migration of contaminated ground water that is acceptable to the conununity
and the state. However, the in-situ bioremediation, as designed, fails to provide adequate
degradation of the ground water contaminants throughout the Site and, therefore, is not considered
acceptable to the conununity or the state.
Summary of Modifvin~ Criteria
Alternative I is not considered acceptable to the conununity or the state. Although Alternatives 6,
9, 10, and 15 provide for stopping off-Site migration of contaminants in ground water, they are not
acceptable to the community or the state, since they fail to clean up the contaminants within the
aquifer. In addition to providing hydraulic containment of contaminated ground water,
Alternatives 3, II, 13, 14 and 16 also propose in-situ bioremediation to remediate the contaminated
ground water. However, because these systems fail to remediate the ground water throughout the
22
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entire Site, these alternatives are not acceptable to the community or the state. Alternative 12M,
proposed to stop off-Site migration of contaminants in ground water and to remediate the ground
water contamination, is acceptable to the community and the state.
SELJECTED REMEDY
The remedy selected to remediate ground water contamination at the fonner Koppers Coke facility
is Alternative 12M, as previously discussed. The RP shall implement this remedy in a phased
approach as follows:
.
Pre-design laboratory and field work (monitoring well decommissioning and
replacement, LNAPL investigation, soil and ground water characterization, microbial
characterization. bench scale nutrient study. and slurry/respirometry study);
Phase I RD/RA (ground water pilot study); and
Phase 2 RD/RA (full scale ground water treatment system)
.
.
The purpose of this phased approach is to optimize the fmal remedial design. The laboratory and
field studies shall be conducted by the RP. as approved by the MPCA staff, to detennine if the
addition of nutrients is necessary and, if so. the types and loading rates required to promote in-situ
bioremediation. The RP shall obtain variances, if necessary, from MPCA and MDH if nutrient
addition is required. The final system design will be dependent on the MPCA staff's review of the
results of pre-design laboratory and field work, and pilot study. As part of the full scale ground
water treatment system. the RP shall install approximately 45 injection wells to deliver oxygen and,
if necessary, nutrients to the surficial glacial aquifer to promote the biological breakdown of
contaminants. The injection wells shall be placed in systematic arrays throughout the Site in areas
where the MPCA staff detennines that contamination is highest. Additionally, The RP shall place
injection wells at the downgradient edge of the Site that will provide a zone of enhanced biological
activity to ensure that contaminants do not migrate off-Site. Figure 2 shows the tentative locations
for th::: injection wells. The RP shall deliver oxygen to the aquifer using sparging techniques. The
MPCA staff will review perfonnance monitoring data to detennine if this alternative by itself is
preventing contaminants from moving off-Site at concentrations exceeding the cleanup levels. If
the MPCA staff detennine that the perfonnance monitoring data shows that this alternative is not
adequate and ground water extraction is necessary. the RP shall implement. as approved by the
MPCA staff, ground water extraction, treatment, and discharge options, similar to those in
Altematives 13, 14, and 15.
Table 3, Ground Water COIs and Cleanup Levels, presents the remediation levels to be attained by
the ground water treatment system. The remediation levels for individual contaminants are based
on the federal MCLs or the MDH criteria, HRLs or RALs. For contaminants that have both a
HRL and RAL, the HRL shall be used. Water quality clean-up levels will be consistent with
MCLs and HRLs/RALs, whichever is lower for a specific contaminant. Additionally, any
discharge to stonn or sanitary sewers will require compliance with NPDES penn it conditions or
MWCC pretreatment levels, respectively. The RP shall monitor ground water quality for a
minimum of four years beyond the final tennination of operation of this system. The RP shall
resume system operation if ground water quality is found not to comply with the remediation levels
for ground water.
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The estimated capital cost of the selected remedy is $1,565,880. The annual operating and
maintenance costs are estimated to be $135,762 over a six-year period. The estimated net
present-worth cost of this alternative is $2,155,000. These costs are broken down in Table 6. The
RP shall take responsibility for all costs associated with implementation of this alternative.
The selected remedy is intended to incorporate flexibility in its implementation so that the best and
most cost-effective means of achieving the remediation levels is used. Because of this, changes to
the remedy may occur during its implementation, based on remedial design, construction processes,
and monitoring data. No changes shall be made without MPCA staff approval. If the MPCA staff
detennines that the selected remedy is not reducing contaminant concentrations, within two full
years of full scale implementation, as indicated by ground water quality data, the MPCA staff will
re-evaluate the selected remedy against other remedial options. In addition, if biodegradation rates
fall to asymptotic levels and contaminant concentrations continue to exceed MCL. HRL, or RAL
standards, the MPCA staff will re-evaluate the selected remedy and consider implementation of one
of the following alternatives:
.
Continuation of the bioremediation effort without changes;
Stimulation of the microbial population through the addition of an alternative
microbial energy source, thereby enabling further reduction of the contaminants
through biodegradation;
Reconsideration of bioremediation as the selected remedy.
.
.
Finally, if within two to five years, the ground water quality data indicate that the selected remedy
is not preventing off-Site migration of contaminated ground water, the RP shall install a ground
water extraction system to meet this objective. The RP shall evaluate and propose the ground
water extraction, treatment and disposal options as described in Alternatives 13, 14, and 15, to
detennine the best ground water alternative method for disposing the water. The RP shall
implement an MPCA approved ground water treatment system,
Current efforts have not identified any additional users of ground water potentially impacted by the
Site. However, the MDH is evaluating whether other such users may exist. The RPs shall assist
MDH in their efforts to identify all users that may be impacted by Site releases. The RPs shall
identify the use and sample all wells identified in the well search that may be impacted by the Site.
Based on the results of the sampling the MDH will detennine whether actions are necessary to
prevent exposure above health based limits and notify well owners of their exposure. If necessary,
the RPs shall implement actions as directed by the MDH such as abandonment of the well and
implementation of an alternative water supply such as city hookup. Since at this time it has been
detennined that well water in the area is not used for drinking purposes, the only potential human
exposure to contaminated grouild water would be through the use of nonpotable water for watering
lawns and gardens.
STATUTORY DETERMINATIONS
Overall Protection of Public Health, Welfare, and the Environment. The selected remedy will
provide adequate protection of human health and the environment by containing and treating
contaminated ground water through in-situ bioremediation, which will degrade contaminants in
ground water before they move off-Site.
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. Compliance with Applicable and Relevant and Appropriate Requirements. The selected remedy
will comply with the requirements of federal and state statutes and rules. The federal statutes that
the remedy must be in compliance with include CERCLA and SARA, which added Section 121 to
CERCLA to provide specific cleanup requirements. Federal ARARs that the remedy will satisfy
include the NCP as adopted by the EP A in March 1990, and MCLs for public drinking water
supplies. This remedy will also comply with Minnesota statutes, including MERLA, Minn. Stat.
9 I J.5B (1992) and the Minnesota Water Pollution Control Act (Minn. Stat. 9 15.061 (1992».
State requirements that the remedy will satisfy include Minn. Rules pt. 7060, Minn. Rules
pt. 7050, Minn. Rules pt. 4717, which establish MDH HRLs as ground water quality standards,
and non promulgated MDH RALs, regarded as to-be-considered criteria. The HRLs are considered
to be ARARs.
Cost-Effectiveness. Except for the No Action Alternative (Alternative I), the selected remedy
provides the most treatment for the least amount of costs as well as the lowest net present worth of
all the alternatives evaluated, and is cost-effective in meeting the remediation objectives.
Utilization of Permanent Solutions and Alternative Treatment (or Resource Recoverv)
Technologies to the Maximum Extent Practicable. The selected remedy uses permanent solutions
and treatment technologies to the maximum extent practicable. The in-situ bioremediation will
provide a permanent remedy for the ground water contamination by degrading the contaminants
witr..in the ground water. If the MPCA staff determine that the performance monitoring data shows
that this alternative is not adequate and ground water extraction is necessary, the RP shall
imp~ement, as approved by the MPCA staff, ground water extraction, treatment, and discharge
options, similar to those in Alternatives 13, 14, and 15.
Preference for Treatment as a Principal Element. The selected remedy satisfies the preference for
treatment through in-situ treatment of the contaminants in the ground water. Ifground water
extraction is necessary to prevent off-Site migration of contaminants, treatment methods will be
employed to reduce the contaminant concentrations in the discharged ground water.
25
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o
4000
- -
- -
6000 feet
2000
Reference:
. U.S.G.S. 7.5 Minute Topographic Map
S1. Paul West, Minn. Quadrangle
1967 Photorevised 1972 and 1977
t

-N-

I
FIGURE 1
SITE LOCATION MAP
FORMER KOPPERS COKE PLANT SITE
ST. PAUL. MINNESOTA
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TABLE 1
SOURCE AREAS
1) OW-10 Area - West End Disposal Area
2) G-3 - Diesel fuel tank
3) Area 2 or OW-2 Area -Tank Farm Area
4) Area 7 - Spray Pond Area
5) Area 8 - Effluent Sump Area
6) Area 9 - Sump Area adjacent to Tank Farm
7) Area 10 - Gas Holders, Benzol Washers, and Final Coolers Area
8) Area 11 - Tar Storage Tanks and Flushing (Devil) Liquor Settling Basin
9) Area 12 - Naphthalene Pit
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TABLE 2
Remedial Actions Conducted 
 Volume 01  
 Material Disposal Date 01
Task Removed Destination Action
Phase I Demolition.   May 1979 to Jan. 1980
Koppers by WCA   
- Demolition of coke battery -  
- Demolition of by-product   
processing areas NA  
- Removal of by-products and soil 20,000cy CWM Landfill May 1979
 2,500cy Road Base May 1979
Phase II Demolition and   Nov. 1980 to Feb. 1981
Execution - Koppers by FEC   
- Demolition of remaining buildings -  
- Removal of demolition debris 16,500cy  
- Removal of foundations and backfill - Road Base 
- Trenches cleared and backfilled -  
- Removal of Tar Products 240,000cy CWM 
- Removal of surface and subsurface soils 20,000cy CWM 
- Removel of 12" benzol building pipe NA Naphthalene Recovery 
- Removal of 18"pipe near G-18 NA  
Site Cleanring &. Grading Phase -   
Authority by TKDA   
- Soil Excavation and Removal 85,000cy Asphalt Plant and End of 1982
,  CWM Landfill 
Area 9 (Tank Farm) NA  End of 1982
OW - 10 West End Disposal Area cy Asphalt Plant and July to
  CWM Landfill September 1982
Area 2 (OW- 2) and Area 9 3,500cy ASp'halt Plant November 1983
 37,950cy Capped in Place 1983
Area 7 (Spray Pond), Area 8 (Effluent Sump) 1 2,1 OOcy CWM Landfill 1983
  CWM Landfill 1983
Soil Excavation Removal (2) Fill along Lexington Ave. 1983
Construction Phase - Authority   
by TKDA   
- Area 7,8, 10, 12 61 5 cy Asphalt Plant and September 1984
  CWM Landfill 
- Area 2 1 ,000 cy Asphalt Plant and September 1984
  CWM Landfill 
ETA/First Banks Building Construction 660 cy CWM Landfill February 1986
 960 cy Asphalt Plant February 1986
 5 cy Stored on First Banks Property 1992
 15,000 cy Thinspread on-Site and 1992
  Capped 
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TABLE 3
GROUND WATER CONSTITUENTS OF INTEREST AND REMEDIATION LEVELS
       CLEAN UP
MA TRIX/COMPOUND   RAL (2) HRL (3) MCL (4) LEVEL
  (1)  IIgll IIg/~ IIgll I1gl1
METALS      
Aluminum       
Antimonv    2.0 6.0 6.0 2.0
Arsenic  c  0.20  50 cum 151
Bervllium  c  0.08 0.08 4.0 cum
Cedmium    4 4.0 5.0 4
Chromium VJ Total   100 100 100 100
CODDer    1000  1.300 1.000
Lead    20  15 15
Mercurv    2.0  2.0 2.0
Nickel    140 100 100 100
Selenium    20 30 50 20
Silver    20 30 100. 20
Thallium    0.6  2 0.6
Vanadium    40   40
Zinc    1 .400  5,000. 1.400
VOLA TILE ORGANICS      
Acetone    700 700  700
Acrolein       
Benzene  c  10 10 5.0 cum
Chlorobenzene   100 100  100
1 2-DichloroIJrODane   5  5 5
Ethvlbenzene   700 700 700 700
Hexachloroethane   1.0   1.0
Methvl Ethvf Ketone 12-Butanone)   300.0   300.0
Methvlene Chloride IDichloromethane) c  50 50 5.0 cum
N-NitrosodiD henvt ami ne   70 70  70
Styrene  c  10  100 cum
Toluene    1,000 1,000 1,000 1.000
Trichloroethvlene c  30  5.0 cum
1 1,1- Trichloroethane   600  200 0.2
Xvlenes Itotal m, D. and 01   10,000 10,000 10,000 10.000
SEMI- VOLA TILE ORGANICS      
Acenaphthene   4000 400  400
AcanaDhthvlllne      
Anthracene   .' 2.000 2000  2.000
..   
Benzola)anthracene c    0.1 cum
Benzo(b)fluoranthene c    0.2 cum
Benzo(k)fluoranthane c    0.2 cum
Benzo(ahi)Dervlene c     cum
Benzo(e) Dvrane c    0.2 cum
,. 1-BiDhenvl (DiDhenvl)    300  300
bis (2-Ethvl hexvl )Dhthalate     6.0 6.0
Carbazole       
4-Chloro-3-methvIDhenol      
Chrvsene      0.2 0.20
Dibenzo(a, h)emthracene c    0.3 cum
Dibenzofuran      
2 4-Dimethvh)henol   600 100  100
Dimethvf Phthalate   7.000   7.000
Di-n-octyl Phthalata      
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TABLE 3
GROUNDWATER CONSTITUENTS OF INTEREST AND REMEDIATION LEVELS
      CLEAN UP
MA TRIX/COMPOUND  RAL (2) HRL (3) MCL (4) LEVEL
  (1) pgll pgll pgll pgll
SEMI- VOLA TILE ORGANICS (continued)     
Auoranthene  300 300  300
Auorene (9H-Fluorene)  300 300  300
Indeno(1 2 3-cd)nvrene c   0.4 cum
2-Methv nanhthalene     
2-Methv IDhenol (o-cresol)  30 30  30
3-Methv IDhenol (m-cresol)  30 30  30
NaDhthalene  30   30
PAHs (total carcinoaenic) - (5) c 0.03   cum
PAHs (total noncarcinoaenic)  0.30   0.3
Phenanthrene     
Phenol   4,000 4,000  4.000
Pvrene   200 200  200
INORGJJ.NICSfNO"-"- a LS!     
Cvanide   100.. 1 00 .. 200 100
Sulfate     250. 
Thiocvanate     
Ammonia     
. Secondary MCL
.. Free Cyanide
(1) (c) This notification indicates that a compound is classified as a possibla carcinogen.
(2) Recommended Allowable Limits for Drinking Water (RALs), Minnesota Department of Health (MDH). Release
No.3. January 1991. The RALs are not promulgated standards and, therefore, are not considered
applicable or relevant and appropriate critaria. However, the RALs may be included in the category of "to
be considered" requirements. This category includes criteria, advisories, guidance, and proposed standards
issued by federal or state governments that are relevant because they address circumstances sufficiently
similar to those at this Site and their application is well suited in determining whether response actions are reasonable
and necessary to protact the public health and welfare, or the environment. RALs use information from the
Integrated Risk Information System (IRIS) and HEAST data bases as well as other references.

(3) Health Risk Limits (HRLs) are presented in Minn. Rules pts. 4717.7100 to 4717.800. HRLs are applicable
to ground water. HRLs replace RALs where both exist for a contaminant as HRLs are based on more recent
risk information. Also, HRLs are based on risk data available in the IRIS data base.
(4) Maximum Contaminant Levels (MCLs) promulgated by the U.S. Environmental Protection Agency.
(5) To determine if the health risk limit for a mixture of carcinogens is exceeded, a cumulative cancer risk
index must be calculated using the procedure in this part.
A. A cumulative cancer risk index shall be determined for substances or chemicals with a toxic endpoint
of cancer as specified in Minn Rule pt. 4717.7650 using the following equation:
Cumulative Cancer Risk
EC1
HRLC1
!£.
HRLC2
+ ....+
~
HRLCn
Where:
(1) ECn represents the concentration of the first, second, ." nth carcinogen detected in ground water; and
(2) HRLCn represents the health risk limit of the first, second, ... nth ~arcinogen as specified in pt.4717.7500

B. A cumulative cancer risk index of one indicates a lifetime risk level of one in 100,000.
C. A cumulative cancer risk index of one equals the health risk limit.
D. A cumulative cancer risk index greater than one exceeds the health risk limit.
2
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Table 4
Evaluated Alternatives
Alternetive 1: No Action
Alternetive 3: Ground weter Extrection, Pretreetment, In-Situ Bioreclemetion, Recherge!Sanitary Sewer Discharge
Alternative 6: Ground Water Extraction, Pretreatment, Carbon Adsorption, Recharge/Sanitary Sewer Discharge
Alternative 9: Ground Watar Extraction, Pretreatment, and Discharge to Sanitary Sawer
Alternative 10: Ground Water Extraction, Diecharge to Sanitary Sawer
Alternativa 11: Ground Water Extraction, Pratreatment, Carbon Adsorption, In-Situ Bioreclamation, Recharge/Discharge to Sanitary Sewer
Alternative 12M: In-eitu Bioreclemation
Alternativa 13: Ground Water Extraction, Pretreatment, Discharge to Sanitary Sewer, Along With In -Situ Bioreclamation
Alternative 14: Ground Watar Extraction and Discharge to Sanitary Sewer, Along With In -Situ Bioreclamation
Alternative 15: Ground Water Extraction, Pretreatment, Carbon Adsorption, and Discharge to Storm Sewer,
Alternative 16: Ground Water Extraction, Pretreatment, Carbon Adsorption, and Discherge to Storm Sawer, Along With In -Situ Bioreclamation
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TABLE 5
      Alternatives     
Criteria 1 3 6 9 10 11 12m 13 14 16 16
1) . Overall Protection of Public Health,           
Welfare and the Environment 0 5 0 0 0 5 5 5 5 0 5
2) ComDliance with ARARs 0 5 5 5 5 5 5 5 5 5 5
3) Lona-term Effectiveness 0 5 2 1 1 5 5 5 5 1 5
4) Reduction of Toxicity, Mobility,           
and Volume Throuah Treatment 0 5 2 2 2 5 5 5 5 2 4
51 Short-tarm Effectiveness 1 5 4 3 2 5 4 5 5 3 5
61 ImDlamentabilitv 5 3 2 3 4 1 5 3 3 2 2
71 Cost 5 2 2 1 4 2 5 2 4 1 1
81 State AcceDtanca 0 5 2 2 2 5 5 5 5 2 4
91 Communitv AcceDtance 0 0 0 0 0 0 5 0 0 0 0
Total 11 35 19 17 20 33 44 36 37 16 31
Comparison Ratings of Feasible AJternatives
(rankings in each catagory from 1 (least satisfactory] to 5 [most satisfactory))
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TABLE 6
COST ESTIMATE
ALTERNATIVE 12M
IN SITU BIORECLAMATION
FORMER KOPPERS COKE PLANT SITE
SAINT PAUL, MJNNEsOT A
CAPITAL c:OSTS
Unit
Quantity
Unit Cost
Total
Subtotal
Nutrient Mix: Tank (SS-Gal Drum) Each 4 $1.SOO $6.000 
Pump (Water Supply to Nutrient Tank: 10 gpm) Each 2 $3,000 $6.000 
Delivery Piping (Nutrients and Oxygen to Wells) Ft 11.200 $3.S $39.200 
Delivery Piping (Water Supply to Mix: Tank) Ft 5.000 $6 $30.000 
Injection Wells (Stainless Steel) Each 4S $11,600 SS22.ooo 
Monitoring Wells (Stainless Steel) Each 10 $11,000 S110,ooo 
     $713.200
Miscellaneous Piping     
(S % Installed Equipment Cost) Lump Sum   $32.200 $32,200
Electrical & Instrumentation     
(25% Installed Equipmcm Cost) Lump Sum   $178,300 $178,300
Engineering     
(IS% InstaJlcd Equipment Cost) Lump Sum   $106.980 $106.980
Site Devclopro.ent . Lump Sum   $36,000 $36.000
Treatability Studies Lump Sum   $50,000 $50.000
General Requirements Lump Sum   $36,000 $36.000
Concrete Lump Sum   $SO,ooo $SO.OOO
Architectural (Building, Structural) Lump Sum   $50.000 $50.000
Subtotal    $1.252.680 $1.252.680
Contingency (25 9!i)    $313,200 $313.200
Total Capital Cost    SI.565.880 1,565,880
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RESPONSIVENESS SUMMARY
KOPPERS COKE SITE
ST. PAUL, MINNESOTA
This community responsiveness summary has been developed to docwnent the Minnesota Pollution
Control Agency's (MPCA) efforts to ensure public participation during selection of a remedial
alternative for the Koppers Coke Superfund site in St. Paul, Minn. The MPCA's recommended
cleanup alternative for the Koppers site was announced to the community through a news release to
local newspapers, the Midway Como Monitor on December 9, 1993, and a legal notice in the St.
Paul Pioneer Press (the local newspaper of record) on November 29, 1993. Fact sheets were
mailed to a list of interested parties, including city-government officials. In addition, an
announcement of the proposal was posted at the two large housing complexes nearest the site and
at the nearby Bandana Square shopping center. The recommended alternative is in-situ
bioremediation with oxygen enhancement. The public comment period ran from November 30
through December 31, 1993. An availability session on the proposed plan was held at a state
office at the site on the evening of December 16.
Records show that since the original Koppers manufacturing complex was dismantled and the site
was redeveloped as part of the Energy Park area, the Koppers Coke site has created very little
interest on the part of the community. Contaminated soil was mostly removed during the
redevelopment, and there are no known users of ground water in the area of the site (residents are
connected to municipal supplies). Therefore, the remaining contamination has seemed to be a case
of "out of sight, out of mind" for the community. .
This perception seems to be borne out by the fact that no one attended the availability session, nor
did anyone request a public meeting, which option on request was advertised as part of the
propose:d plan. The MPCA received no comments on the proposed plan during the public comment
period. or (as of this writing) afterward.
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KOPPERS COKE ADKINISTRATIVE RECORD
DATA
U.S.G.S. Seismic Data
March 1983
DATA
Vater Analysis and Data
July 7, 1983
DATA
Vater Analysis
1986
DATA
VeIl Analysis - 2nd Round 1988
Keystone Environmental Resources
December. 13, 1988
DATA
2nd and 3rd Round Analytical Results
Keystone Environmental Resources, Inc.
February 6, 1989
PAISI
Report of Ground
Soil Exploration
July 9, 1980
Vater Study - Proposed Energy Park Site
Company
PAISI
Engineering Geology of the St. Paul Energy
Honeywell Technology Strategy Center
May 1981

PAISI
Vest End Disposal Site
Koppers Company, Inc.
November 5, 1980
Park and Vicinity
Investigatio.n
PAISI
Field Sampling and Chemical
Soil Exploration Company
September 13, 1982
Analysis - VeIls TB-1 and TB-2
PA/SI
HRS Scor.ing Package
August 10, 1982
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-2-
PAISI
Draft of the Final Report
CH2M Hill
submitted March 26, 1984
on the Extent of Contamination
PAISI
Draft of the Final
CH2M Hill
April 3, 1984
Report on the Extent of Contamination
PAISI
Subsurface Investigation
Soil Exploration Company
April 3, 1984
Program - Energy Park Area
PAISI
Check for Subsurface Contamination
Soil Exploration Company
May 18, 1984
- Energy Park Area
PAIS!
FoundaHon Investigation Proposed Office/Varehouse Building
Braun
.September 19, 1984
BRD ITM/COM AUT/PERMIT
Request for Response Action
Minnesota Pollution Control
March 25, 1986
Agency
RISK AND DAMAGES ASSESSMENT
Endangerment Assessment
GCA Corporation
July 1986

RISK AND DAMAGES ASSESSMENT
Health Assessment
Minnesota Department of Health
June 27, 1989
RISK AND DAMAGES ASSESSMENT
Qualitative Ecological Assessment
Keystone Environmental Resources, Inc.
December 1991
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-3-
RISK AND DAMAGES ASSESSMENT
Ecological Risk Assessment
Keystone Environmental Resources, Inc.
July 1992

REMEDIAL ACTION AND DESIGN
First Bank/Ryan Construction
for Soil Disposal
Twin City Testing
August 20, 1992
Results of Soil Disposal Assessment and Vork Plan
RIfFS
Hydrogeologic Study
Environmental Resources
NovembE!r 8, 1979
and Occupational Health Department
RIfFS
Evaluation
Geraghty &
April 1.981
of Ground-Vater Conditions in the Unconsolidated Deposits
Miller, Inc.
RIfFS
Subsurface Exploration, Monitoring Vell
Sampling/Analytical Program
Soil Exploration Company
January 13, 19~4
Installations, Field
RIfFS
RI/FS Scope of Vork
Keystone Environmental
received July 11, 1986
ResQurces/ReTeC
RIfFS
Remedial Investigation and Feasibility
Keystone Environmental Resources, Inc.
June 1987
Study Vork Plan
RIfFS
Remedial Investigation Appendices
Keystone Environmental Resources, Inc.
June 1987
RIfFS
Supplemental Groundwater Sampling Plan
Keystone Environmental Resources, Inc.
November 1991
/'
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-4-
RIIFS
Remedial Investigation
Keystone Environmental
Septemb«~r 1992
Volume I
Resources, Inc.
RIIFS
Remedial Investigation
Keystone Environmental
September 1992
Volume II Appendices A - C
Resources, Inc.
RIIFS
Remedial Investigation
Keystone Environmental
September 1992
Volume III Appendices D - L
Resources, Inc. .
RIIFS
Alternatives Report
Keystone Environmental
December 1992
Resources, Inc.
RIfFS
Detailed Analysis Report
Chester Environmental
June 1993
RIfFS
Addendum to Detailed Analysis
Chester Environmental
October 1993
Report
QAPP
Quality Assurance Project Plan for the RIfFS
Keystone Environmental Resources, Inc.
June 1987
QAPP
Draft auality Assurance Project Plan -
Risk Assessment
Keystone Environmental Resources, Inc.
March 1992
Second Addendum, Phase II Ecological
QAPP
Aquatic Toxicity Testing Quality Assurance
Keystone Environmental Resources, Inc.
received April 14, 1992
Manual
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-5-
QAPP
Appendi~: A - EPA Standard Operating Procedures for Earthworm Assays
received April 14, 1992
GUIDANCI~ DOCUMENTS
Comprehfmsive Environmental
(CERCLA)
1980
Response, Compensation, and Liability Act of 1980
GUIDANCg DOCUMENTS
Minnesota Environmental Response and Liability Act (MERLA)
1983
GUIDANCE DOCUMENTS
The Superfund Amendments and Reauthorization Act of 1986 (SARA - within CERCLA)
1986
GUIDANCE DOCUMENTS
Performance of RCRA Method 8280 for the-Analysis of
Dibenzofurans in Hazardous Waste Samples
Environmental Protection Agency
April 1.986

GUIDANCE DOCUMENTS
Draft RCRA Method 8280 with Revisions Based on Multi-Laboratory Testing:
Method of Analysis for Polychlorinated Dibenzo-P-Dioxins and Polychlorinated
Dibenzofurans -
June 12, 1986
Dibenzo-P-Dioxins and
GUIDANCE DOCUMENTS
Minnesota Superfund Fact Sheets 1-9
Minnesota Pollution Control Agency
May 1 and November 1, 1989
GUIDANCE DOCUMENTS
Guidance for Conducting Remedial
CERCLA, Interim Final
Office of Emergency and Remedial
October 1988
Investigations and Feasibility Studies under
Response/U.S. Environmental Protection Agency
GUIDANCE DOCUMENTS
Guidance on Preparing Superfund Decision Documents: The Proposed Plan, The
Record of Decision, Explanation of Significant Differences, The Record of
Decision Amendment, Interim Final
OfficE! of Emergency and Remedial Response/U.S. Environmental Protection Agency
July 1989
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-6-
GUIDANCE DOCUMENTS .
Determin.ing Soil Response Action Levels Based on Potential Contaminant
Migration to Ground Vater: A Compendium of Examples
Office of Emergency and Remedial Response/U.S. Environmental Protection
October 1989
Agency
GUIDANCE: DOCUMENTS
National Oil and Hazardous Substances
(National Contingency Plan)
Environmental Protection Agency
March 8, 1990
Pollution Contingency Plan, Final Rule
GUIDANCE DOCUMENTS
Conducting Remedial
Landfill Si tes
Office of Emergency
February 1991
Investigations/Feasibility Studies for CERCLA Municipal
Remedial Response/U.S. Environmental Protection Agency
GUIDANCE DOCUMENTS
Superfund Permanent List of Priorities
Minnesota Pollution Control Agency
issued every six months
list revised April 25, 1994
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Minnesota Pollution Control Agency
April 25, 1994
Mr. David Wilson
Remedial Project Manager
U. S. Environmental Protection Agency
Region 5
77 West lacksonBoulevard
Chicago, Illinois 60604-3590
RE: U.S. Environmental Protection Agency's March 9, 1"994, Conunents to the Minnesota
Pollution Control Agency's February 2, 1994. Draft Record Of Decision for the Koppers
Coke Site .
Dear Mr. Wilson:
Thank you for providing the conunents to the Minnesota Pollution Control Agency (MPCA) staffs
February 2. 1994,.draft Record of Decision (ROD) for the Koppers Coke site. Attached is a
summary of how the MPCA staff modified the draft ROD to address your conunents' Enclosed is
. a copy of the final ROD. .
If you hilVe any questions regarding the MPCA staff conunents and the ROD, please contact me at
(612) 296-7813. .
Sincerely, 0'
-7
0' I
l~"t1 f j~,-
Br;~:f.:tj inkIer
Pr~~~er
Responsible Party Unit 1
Site Response Section
BW:ch
Enclosures
520 Lafayette Rd. N.; St. Paul, MN 55155-4194: (612) 296-6300 (voice); (612) 282-5332 (TTY)
Regional Offices: Duluth'. Brainerd. Detroit Lakes. Marshall. Rochester
Equal Opportunity Employer. Printed on recycled paper containing at least 10% fibers from paper recycled by consumers.
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MPCA STAFF COMMENTS
Koppers Coke Site
The Minnesota Pollution Control Agency (MPCA) staff response to the U.S. Environmental
Protection Agency's March 9. 1994. comments on the February 2. 1994. Draft Record Of Decision
(ROD).
General Comments
L
I. The MPCA staff agrees with your suggested changes and have included the language in the
section titled Summary of the Comparative Analysis of Alternatives.
2. Enforcement language has been included in the Selected Remedy section. as well as throughout
the ROD.
Specific Comments
I. Draft documents as well as final documents were used in the preparation of the ROD.
Therefore. the draft documents are a part of the Administrative Record. A copy of the updated
Administration Record is enclosed.
2. The Selected Remedy section has been modified to include trigger points to determine if/when
ground water extraction will be required.
In your letter you recommended that the MPCA staff fully describe and relate one of the
alternatives for the ground water contingency such as Alternative 13 or 14. The contingency is
to extract ground \'v'ater. Treatment options for the extracted ground water cannot be
determined until its quality has been fully characterized. Therefore. the MPCA staff do not
advise choosing a treatment alternative at this time. If ground water extraction is necessary.
the MPCA staff will determine if and how the ground water should be treated. As part of this
evaluation, the MPCA staff will determine whether the ground water can be discharged to the
sanitary or the storm sewer. The MPCA staff feel that the wording in the ROD \s appropriate,
and that if ground water extraction is nece.ssary, the ROD will not require an amendment.
'"
,).
All cleanup "goals" have been changed to cleanup "levels."
4. The MPCA staffhas modified the Site History section to address your concerns on origination
of contaminants and whether they exceed recommended allowable levels (RALs), maximum
contaminant levels (MCLs), and health risk limits (HRLs). .
5. The Selected Remedy section has been modified to include all of the requirements of the ROD
including soil investigations.
6. The Scope and Role of Operable Units section has been modified to address your concerns.
7. The Health Assessment section has been modified to address your concerns.
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8. Deed restrictions were discussed with the MPCA legal council. It would be difficult and
urmecessary for the MPCA to request Koppers to place a deed restriction on the property
be:cause they no longer own the property. Currently. there are two types of institutional
controls in place: the Minnesota Department of Health (MDH) Water Well Code and the State
Plumbing Code. The requirements of the MDH Well Code would not allow a home owner in
this area to install a well without a variance. This is because the lot sIzes in this area are
ge:nerally not large enough to meet the Well Code isolation distances. If someone pursued
obtaining a variance the MDH would not grant a variance because of the known contamination
in the area. In addition, if a structure were to be built in the area, the plumbing code requires
that if a municipal water supply is available you must hook up to the water supply. The
MPCA staff will pursue a deed restriction if the cleanup levels have not been achieved at the
completion of the remedial actions.
As indicated in the ROD. the RPs shall assist MDH in their efforts to identify all users that
may be impacted by Site releases. The RPs shall identify the use. and sample all wells
identified in the well search that may be impacted by the Site. Based on the results of the
sampling the MDH will determine whether actions are necessary to prevent exposure above
health based limits and notify well owners of their exposure. If necessary. the RPs shall
implement actions as directed by the MDH. such as abandonment and alternative water supply,
(rnunicipal water supply connections).
9. Please see comment 2 above.
10. Tbe Summary of Balancing Criteria - Cost section has been modified to address your concerns.
II. The Selected Remedy section has been modified to include all of the requirements of the ROD.
12. Table 3 has been modified to address your concerns.
13. The Compliance with Applicable or Relevant and Appropriate Requirements (ARARs) section
has been modified to include "state" after "federal statutes..." to address your concerns.
14. The Cost-Effectiveness section has been modified to include this information.
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.. Minnesota Pollution Control Agency
~.
April 2S, 1994
Mr. Robert S. Markwell
Program Manager, Environmental Services
Beazer East. Inc.
436 Seventh Avenue
Pittsburgh, Pennsylvania 15219
RE: Record of Decision for the Koppers Coke Site
Dear Mr. Markwell:
Enclosed is a copy of the Minnesota Pollution Control Agency's (MPCA) Record of
Decision (ROD) for the Koppers Coke Superfund site (Site) in St. Paul. Minnesota. The
decision was developed in accordance with the March 25. 1986. Request for Response
Action. the Minnesota Environmental Response and Liability Act (MERLA).
Comprehensive Environmental Response. Compensation. and Liability Act (CERCLA). as
amended by the Superfund Amendments Reauthorization Act (SARA) and. to the extent
practicable. the National Contingency Plan (NCP).
As required by the RFRA. and amended by the MPCA's letter of March 25. 1994. Beazer
was required to submit the pre-design laboratory and field work. work plan (Work Plan)
and quality assurance project plan (QAPP) by March 28. 1994. Due to the delay in
issuance of the ROD. this date has not been met. The MPCA staff request Beazer to
submit the Work Plan and QAPP by May 2. 1993. and to make every attempt possible to
get back on track with the schedule presented in the letter dated March 25. 1994.
520 Lafayelte Rd. N.; St. Paul. MN 55155-4194: (612) 296.6300 (voice); (612) 282.5332 (TTY)
Regional Offices: Duluth. Brainerd. Detroit Lakes. Marshall. Rochester
Equal Opportunity Employer. Prlnled on recycled paper containing al leasl 10% fibers from paper recycled by consumers.
-------
Mr. Robert S. Markwell
Page 2
April 25, 1994
If you have any questions regarding this letter, or with the schedule, please contact me at
(612) 296-7813.
Sincerely,
BW:ch
Enclosures:
cc: Kurt Geiser, P.E., Remediation Technologies Inc.
David Wilson, U.S. Environmental Protection Agency
David Jones, MiMesota Department of Health
eC.S. GOVEi\.~T PRINTI~G OFFICE: 1994-386-541/03070
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