EPA Superfund
Record of Decision:
PB99-964302
EPA541-R99-030
1999
Ace Services Site
Colby, KS
5/5/1999
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RECORD OF DECISION
Ace Services Site
Colby, Kansas
Prepared by:
U.S. Environmental Protection Agency
Region VII
Kansas City, Kansas
April 1999
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Table of Contents
Abbreviations and Acronyms i
I. Declaration • D-1
II. Decision Summary • • • DS-l
1.0 Site Name, Location, and Description DS-l
2.0 Site History and Enforcement Activities DS-l
3.0 Community Participation • DS-3
4.0 Site Characteristics - DS-3
4.1 Groundwater DS-3
4.2 Exterior Soils • - • • DS-4
4.3 On-site Buildings DS-5
5.0 Current and Potential Future Site and Resource Uses DS-6
6.0 Summary of Site Risks °S-6
6.1 Human Health Risk Assessment • • DS-7
6.2 Ecological Risk Assessment DS-8
7.0 Remediation Objectives '..... - • • DS-8
8.0 Description of Alternatives . DS-9
8.1 Groundwater Alternatives DS-10
8.1.1 Groundwater Alternative 1: No Action DS-10
8.1.2 Groundwater Alternative 2: Contairiment/Reduction/Precipitation/
Coagulation-Flocculation DS-11
8.1.3 Groundwater Alternatives: Active Restoration/Reduction/
Precipitation/Coagulation-Flocculation DS-l 4
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8.1.4 Groundwater Alternative 4: Containment/Ion Exchange DS-16
8.1.5 Groundwater Alternative 5: Active Restoration/Ion Exchange . . DS-17
8.1.6 Groundwater Alternative 6: Active Restoration/ Reduction/ Precipitation/
Coagulation-Flocculation/In-Situ Bioremediation . DS-18
8.2 Buildings/Soils Alternatives DS-21
8.2.1 Buildings/Soil Alternative 1: No Further Action DS-21
8.2.2 Buildings/Soil Alternative 2: Limited Action DS-21
8.2.3 Buildings/Soil Alternative 3: Surface Cleaning/Disposal DS-22
8.2.4 Buildings/Soils Alternative 4: Surface Layer Removal/Disposal . DS-22
8.2.5 Buildings/Soil Alternative 5: Encapsulation/Disposal DS-23
9.0 Comparative Analysis of Alternatives DS-24
9.1 Groundwater Alternatives DS-24
9.1.1 Overall Protection of Human Health and the Environment .... DS-24
9.1.2 Compliance with Applicable or Relevant and Appropriate
Requirements (ARARs) ., DS-25
9.1.3 Long-Term Effectiveness and Permanence DS-26
9.1.4 Reduction of Toxicity, Mobility, and Volume Through Treatment DS-27
9.1.5 Short-Term Effectiveness DS-28
9.1.6 Implementability DS-28
9.1.7 Cost DS-29
9.1.8 State Acceptance DS-30
9.1.9 Community Acceptance •. DS-30
9.2 Buildings/Soils Alternative Analysis . DS-30
9.2.1 Overall Protection of Human Health and the Environment .... DS-30
9.2.2 Compliance with ARARs DS-31
9.2.3 Long-Term Effectiveness and Permanence DS-31
9.2.4 Reduction of Toxicity, Mobility, and Volume DS-32
9.2.5 Short-Term Effectiveness DS-32
9.2.6 Implementability DS-32
9.2.7 Cost . . DS-33
9.2.8 State Acceptance DS-33
9.2.9 Community Acceptance DS-33
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10.0 Selected Remedy DS-34
10.1 Description of Selected Remedy DS-34
10.1.1 Groundwater DS-34
10.1.2 Buildings/Soil DS-42
10.2 Summary of Estimated Costs DS-43
10.3 Cleanup Levels DS-43
10.4 Expected Outcomes of the Selected Remedy DS-44
11.0 Statutory Determinations DS-44
11.1 Protection of Human Health and the Environment DS-44
11.2 Compliance with ARARs DS-45
11.3 Cost Effectiveness DS-49
11.4 Utilization of Permanent Solutions and Innovative Treatment
Technologies to the Maximum Extent Practicable DS-49
11.5 Preference for Treatment which Reduces Toxicity, Mobility, or
Volume DS-50
12.0 Documentation of Significant Changes DS-50
III. Responsiveness Summary RS-1
Table 1 Preferred Groundwater Alternative Present Worth Cost Estimate:
Active Restoration/Reduc/Precip/Coag-Flocc/In-Situ Bioremediation
Table 2 Preferred Building/Soil Alternative Present Worth Cost Estimate: Grit-Blasting
Table 3 Final Cleanup Levels: Groundwater, Interior Air, Interior Dust/Concrete, and
Exterior Soil
Figure 1 Site Location
Figure 2 Site Map
Figure 3 Hexavalent Chromium Isoconcentration Contour Map
Figure 4 Vertical Extent of Hexavalent Chromium
Figure 5 Groundwater Alternatives 2 and 4 Containment Site Plan
Figure 6 Groundwater Alternatives 3, 5, and 6 Active Restoration Site Plan
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Abbreviations and Acronyms
ARARs Applicable or Relevant and Appropriate Requirements
AWQC Ambient Water Quality Criteria
ATSDR Agency for Toxic Substances and Disease Registry
BGS Below Ground Surface (bgs)
CERCLA Comprehensive Environmental Response, Compensation, and
Liability Act
CFR Code of Federal Regulations
COC Contaminant of Concern
Cr Chromium
Cr(III) Trivalent Chromium
Cr(VI) Hexavalent Chromium
DO Dissolved Oxygen
ECP Electrochemical Precipitation
Eh Oxidation/Reduction Potential
EPA U.S. Environmental Protection Agency
EP&RB Emergency Planning and Response Branch
EX Extraction Well
FS Feasibility Study
FT Feet (ft)
GPM Gallons Per Minute (gpm)
HBSL Health-Based Screening Levels
HDPE High Density Polyethylene
HP Horsepower
IRIS Integrated Risk Information System
KDHE Kansas Department of Health and Environment
MCL Maximum Contaminant Level
MG/KG Milligram Per Kilogram (mg/kg)
MPW Multiport Well
MW Monitoring Well
NCP National Contingency Plan
NPDES National Pollutant Discharge Elimination System
NPL National Priorities List
O&M Operation and Maintenance
OSHA Occupational Safety and Health Administration
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Abbreviations and Acronyms (Continued)
OSWER
PEL
PA/SI
pH
POTW
PLC
PVC
PWS
RAO
RBC
RCRA
RD
RI
RI/FS
ROD
RW
SARA
SDWA
SSW
TBC
TCLP
use
WWT
Office of Solid Waste and Emergency Response
Permissible Exposure Level
Preliminary Assessment and Scanning Site Investigation
Log Concentration of Hydrogen Ions
Publicly Owned Treatment Works
Programmable Logic Controller
Polyvinyl Chloride
Public Water Supply
Remedial Action Objective
Risk Based Concentration
Resource Conservation and Recovery Act
Remedial Design
Remedial Investigation
Remedial Investigation/Feasibility Study
Record of Decision
Residential Well
Superftmd Amendments and Reauthorization Act
Safe Drinking Water Act
Shallow Sampling Well
To Be Considered
Toxicity Characteristic Leaching Procedure
Micrograms Per Liter
United States Code
Wastewater Treatment
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I. DECLARATION
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Declaration for the Record of Decision
Ace Services Site
Colby, Kansas
Site Name and Location
The Ace Services Site, CERCLIS identification number KSD046746731, is located
in Colby, Kansas. Colby, Kansas, is an agricultural community in the central section of
Thomas County, about 350 miles west of Kansas City, Kansas.
Statement of Basis and Purpose
This decision document presents the selected remedial action for the Ace Services
Site, in Colby, Kansas, which was chosen by the United States Environmental Protection
Agency in accordance with Comprehensive Environmental Response, Compensation and
Liability Act of 1980 (CERCLA), as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), and, to the extent practicable, the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP), 40 C.F.R. Part 300. This
decision is based on the administrative record for this site. The state of Kansas concurs
with the selected remedy.
Assessment of the Site
Actual or threatened releases of hazardous substances from this site, if not addressed
by implementing the response action selected in this Record of Decision (ROD), may
present an imminent and substantial endangerment to public health, welfare, or the
environment.
Description of Selected Remedy
This ROD addresses contaminated groundwater and contamination within on-site
buildings. Evaluation of soil data has determined that removal actions performed at the
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site have eliminated health concerns from exposure to contaminated surface soils at the
site. The principal threat at this site is metals contamination in the on-site buildings;
another major threat is metals contamination in groundwater. The specific metals which
have been identified as contaminants of concern (COCs) are hexavalent chromium [Cr(VI)]
and lead.
The presence of hexavalent chromium in the groundwater at the site presents a threat
to any future on-site or off-site resident users of groundwater. The major components of
the selected remedy for groundwater include the following:
• Institutional controls including deed restrictions, as permitted by law, to prevent
use of contaminated groundwater.
• Active restoration of the aquifer by pumping and treating the contaminated
groundwater.
• Treatment of contaminated groundwater by electrochemical reduction and
precipitation techniques.
• Discharge of treated groundwater to the on-site tributary to Prairie Dog Creek.
Alternatively and as appropriate, treated and untreated groundwater will be
discharged to the local Colby publically owned treatment works (POTW) and, at
the option of state and local authorities, the treated groundwater may be
beneficially reused rather than discharged.
• In-situ bioremediation of contaminated groundwater is possible, as indicated by
the results of treatability studies during design.
• Groundwater monitoring and periodic review of results.
The presence of lead in dust in on-site buildings and contamination on interior
surfaces poses potential health concerns for industrial or commercial uses. The major
components of the selected remedy for on-site buildings include the following:
• Institutional controls, as permitted by law, to prevent residential use of the site
and buildings and to prevent removal of floors and soils beneath the building.
• Removal of contaminated ulterior concrete surfaces by grit blasting.
• Decontamination of building interiors by dusting, vacuuming, and wiping.
• Disposal of decontamination debris as appropriate, if necessary at a Resource
Conservation and Recovery Act (RCRA) facility.
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Statutory Determinations
The selected remedy is protective of human health and the environment, complies with
federal and state requirements that are legally applicable or relevant and appropriate to the
remedial action, is cost-effective, and utilizes permanent solutions and alternative treatment
(or resource recovery) technologies to the maximum extent practicable. This remedy also
satisfies the statutory preference for remedies that employ treatment as a principal element
(i.e., reduce toxicity, mobility, or volume of contaminants through treatment). Because
hazardous substances above health-based levels are expected to continue to be on-site in
5 years, a review will be conducted within 5 years after commencement of remedial action
to ensure that the remedy continues to provide adequate protection of human health and
the environment.
Data Certification Checklist
The following information is included in the Decision Summary section of the Record
of Decision. Additional information can be found in the Administrative Record for this
site.
• Contaminants of concern (COCs) and their respective concentrations.
• Baseline risk represented by the COCs.
• Cleanup levels established for COCs and the basis for the levels.
• Current and future land use assumptions from the baseline risk assessment.
Land use that will be available at the site as a result of the selected remedy.
• Estimated capital, operation and maintenance (O&M), and total present worth
costs; discount rate; and the number of years over which the remedy cost
estimates are projected.
• Decisive factors that lead to selecting the remedy.
Authorizing Signature
Michael J. Sand*fson Date
Director
Superfund Division
U.S. Environmental Protection Agency
Region VII
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II. DECISION SUMMARY
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Decision Summary
1.0 Site Name, Location, and Description
This Record of Decision (ROD) was developed by the U.S. Environmental
Protection Agency (EPA), as lead agency, with support from the Kansas Department of
Health and Environment (KDHE).
The Ace Services site (EPA Identification No. KSD046746731) contains the Ace
Services property and includes the chromium groundwater plume for the area where
chromium concentrations are greater or equal to 100 micrograms per liter (,ug/L). The
Ace Services property is located at 345 Convesse Avenue in Colby, Kansas, Thomas
County. The site lies in the southeast 1/4 of Section 31, Township 7 South, Range 33
West. The geographic coordinates are approximately 100° 2' 10" west longitude and 39°
23' 47" north latitude. A location map is presented as Figure 1. A site map is presented
as Figure 2. The approximate site boundary as indicated by the 100 /zg/L Cr(VI) contour
plume is illustrated on Figure 3.
2.0 Site History and Enforcement Activities
The Ace Services facility was a plating shop where chrome plating was applied to
sickle bar knives used on farm equipment. The facility currently includes two buildings
(a former plating shop and a former machine shop/office building), an inactive
groundwater recovery well, and an area of soil and concrete rubble fill at the location of
the former lagoon. The former plating shop contained three concrete/cinder block
troughs where vats of plating solutions were located during former business operations.
A 1,000-square-foot building that was attached to the east side of the plating shop housed
a wastewater treatment (WWT) facility, used by Ace Services. The WWT annex had four
concrete basins that contained fluids during the wastewater treatment process. A 200-
square-foot cinder block building that was located directly south of the WWT building
contained an acetylene generator used by Ace for welding operations. The WWT
building and acetylene generator/chemical storage building were demolished during an
EPA removal action in 1994. The machine shop is immediately south of the plating
shop.
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The KDHE records indicate that a chrome plating facility has operated at the present
location of the Ace Services facility from approximately 1954 to 1990. The facility was
owned and operated by a company known as Northwest Manufacturing from
approximately 1954 until 1969, when Ace Services was formed and began operations at
the facility. Prior to the chrome plating operations, a brick making plant may have been
located at the site in the early 1900s.
The contaminants at the Ace Services facility were released as a result of chromium
electroplating operations. The source of chromium was the chromic acid solution in the
plating vats. Lead was also present, probably as lead chromate, which is formed when
lead anodes are used in the plating process. Both contaminants entered the environment
from leaks and spills during plating operations, and from discharges of the faulty
wastewater treatment system.
The treatment system inadequately treated wastes and resulted in discharges from the
facility exceeding wastewater effluent limitations. The facility added a surface
impoundment, or lagoon, to the system to control discharges to the unnamed tributary of
Prairie Dog Creek east of the site. Resulting sludges from the surface impoundment and
the underlying soils were found to be contaminated with lead and chromium;
groundwater in the area has been found to be contaminated with chromium.
The KDHE and EPA involvement with the site began in 1971 after KDHE received a
citizen complaint reporting that Ace Services was discharging wastewater to the ground
and the nearby unnamed tributary of Prairie Dog Creek. The Ace Services site was first
identified for investigation under the Superfund program in 1980 by KDHE. A
Preliminary Assessment and Scanning Site Investigation (PA/SI) was performed by
KDHE in 1989. A Listing Site Investigation was performed by KDHE in 1991 which
included the installation of three groundwater monitoring wells. Removal actions were
performed by KDHE in 1981 and 1992 for contaminated sludges and remaining process
wastes, and by EPA in 1994 for contaminated soils and contaminated building debris.
The site was added to the National Priorities List (NPL) in September 1995. In 1996,
EPA continued remedial investigation activities for groundwater and also conducted
surface soil and building media sampling. .
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3.0 Community Participation
The Human Health Baseline Risk Assessment, the Remedial Investigation (RI)
Report, the Final Feasibility Study (FS) Report, and supporting documentation in the
Administrative Record were made available to the public for a public comment period
which began on December 4, 1998, and ended on January 4, 1999. The documents were
available at EPA Region VII Headquarters in Kansas City, Kansas, and the Pioneer
Memorial Library in Colby, Kansas. The notice of the availability of these documents
and the time and location of the public meeting was published in the Colby Free Press on
December 4, 1998. A fact sheet summarizing the proposed plan and preferred alternative
was mailed to residents and local authorities on December 2, 1998. A public meeting
was held during the public comment period at Colby, Kansas, on December 16, 1998. At
the meeting, the conclusions of the Remedial Investigation/Feasibility Study (RI/FS) of
the site were presented to highlight the reasons for recommending the preferred remedial
alternative and public comments were received.
Comments received at the public meeting, as well as written comments submitted
during the comment period, are addressed in the Responsiveness Summary Section of this
ROD, the document which formalizes the selection of the remedy.
4.0 Site Characteristics
An RI was conducted to determine the nature and extent of contamination at the site
and potential contaminant fate and transport scenarios. Also, KDHE and EPA have
performed removal actions at the site. The following sections present brief descriptions
of the site characteristics based on the previous investigations and removal actions at the
site.
4.1 Groundwater
The Ogallala Aquifer is the aquifer below the site that has been contaminated by
releases at the site. Groundwater at the site flows predominantly to the east.
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Groundwater sampling and analysis efforts have been performed at the site since
1980. The KDHE performed extensive groundwater sampling and analysis in 1996. This
investigation was followed by a Phase 1 Remedial Investigation (RI) for groundwater that
was conducted by EPA in 1996 and a Phase 2 RI conducted in 1997. During the KDHE
investigation and the EPA RI, chromium contamination of the groundwater was
identified.
The nature and extent of contamination in groundwater at the site were evaluated
during the RI by sampling 13 wells and developing a groundwater model using
MODFLOW and MODPATH. Analytical results of the groundwater samples indicate the
presence of chromium in the groundwater; lead was not present above detection limits in
the groundwater. Comparing results of the total chromium (Cr) and hexavalent
chromium (Cr(VI)) analyses indicates that most or all of the total chromium is in the
hexavalent state. Furthermore, comparing total analyte results with dissolved analyte
results indicate all chromium present is in the dissolved state, i.e., hexavalent chromium.
The extent of hexavalent chromium contamination in the groundwater is presented in
Figures 3 and 4.
4.2 Exterior Soils
Contaminated soils were identified at the site in 1980. Sediment samples collected
from the unnamed tributary of Prairie Dog Creek during the PA/SI by KDHE in 1989
were found to be below site action levels, selected by EPA in consulatation with KDHE,
for total chromium and lead (1,500 mg/kg and 500 mg/kg, respectively). A removal
action for chromium and lead contaminated soil from the Ace Services site was
completed by EPA Region VII Emergency Planning and Response Branch (EP&RB) in
1994. Following the removal of contaminated soil based on the action levels, the
excavated areas of the lagoon and former location of the wastewater treatment building
were backfilled with clean soils. The areas were seeded, watered, and covered with straw
prior to de-mobilization. The risk assessment re-evaluated exterior soils by comparing
concentrations of remaining contaminants to current industrial action levels. The re-
evaluation concluded there is adequate protection of human health and the environment
for an industrial setting from exposure to contaminated soils.
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4.3 On-site Buildings
The 1994 removal action remediated the buildings for chromium and lead
contaminated concrete, cinder blocks, associated soils, and dust. The plating vat troughs
and the underlying soil in the plating shop were excavated and disposed. Following the
removal of contaminated soil based on the action levels, the plating troughs excavation
area was backfilled with clean soil. The troughs were capped with a 4- to 6-inch layer of
concrete in order to complete the floor inside the plating shop. To prevent the building
from collapsing, contaminated soil was not removed from around the building support
piers.
After excavation, chromium-colored staining was observed collecting at the
excavation face. This was believed to be caused by chromium-contaminated water in the
soil moving to the open face due to the low humidity. These issues were discussed with
the Agency for Toxic Substances and Disease Registry (ATSDR). The ATSDR
concurred with EPA's evaluation that the removal action continues to be protective of
human health.
The decision was also made that a deed restriction or some other type of institutional
control be placed on the property to keep a future property owner from disturbing any
contamination that might remain beneath the concrete and fill material. The deed
restriction or other control will be put in place with the cooperation of the property
owner; or if necessary, EPA will seek through the legal process to impose such deed
restrictions or other institutional controls as may be imposed by legal process without the
cooperation of the property owner. In addition to the contamination found in the soil and
trough concrete, there was evidence of contamination in the concrete floors in the plating
shop. The concrete floor was treated to remove the chromium contamination.
Near the end of the EPA removal action in 1994, paniculate air samples were
collected from the interior of the plating shop. The results of the indoor air sampling and
analysis were below cleanup levels established for interior air for the removal action.
Additional indoor air and indoor dust sampling was performed by EPA in both
buildings during a site visit in 1996. Results from this sampling event were also below
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cleanup levels for indoor air; however, lead concentrations in indoor dust samples from
both buildings were above health-based screening levels established for indoor dust. The
risk levels for indoor air and indoor dusts were evaluated in the Baseline Risk
Assessment prepared for the site.
5.0 Current and Potential Future Site and Resource Uses
The site is currently used as a storage facility and is surrounded by residential and
commercial areas. Future use of the site is to continue to be industrial or commercial.
Comments presented by the community did not include concern for use of the site as
anything other than these uses. The proposed remedy proposes institutional controls to
prevent future use of the site as residential.
The Ogallala aquifer below the site is used as a primary potable water resource for
the region, and specifically is a municipal source for Colby, Kansas, and for individual
residences in the site area that are not connected to the municipal water system of Colby.
A Colby municipal water supply well has been contaminated and has been taken out of
service because of the contamination. The community has expressed a strong interest in
being able to return the well to service in the near future.
6.0 Summary of Site Risks
The baseline risk assessment estimates what risks the site poses if no action were
taken. It provides the basis for taking action and identifies the contaminants and
exposure pathways that need to be addressed by the remedial action. This section of the
ROD summarizes the results of the baseline risk assessment for this site.
Actual or threatened releases of hazardous substances from this site, if not addressed
by implementing the response action selected in this ROD, may present an imminent and
substantial endangerment to public health, welfare, or the environment.
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6.1 Human Health Risk Assessment
A human health baseline risk assessment was prepared for the Ace Services site.
This summary presents an overview of the risk assessment prepared for the site. The
complete risk assessment may be consulted in the administrative record file for a more
detailed evaluation of the site risks.
Risk assessment is an analysis of the potential adverse health effects that may result
from human exposure to chemical contaminants present at the site. The primary COC's
at the Ace Services site are hexavalent chromium in groundwater and lead in indoor
building dust. These metals may pose adverse health effects at relatively high
concentrations or exposures. Exposures to contaminated groundwater from ingestion and
dermal contact while bathing were evaluated. Pathways of exposure to contaminated soil
and dust were also evaluated. Hexavalent chromium is considered to be a probable
human carcinogen only if inhaled, however, these effects are only typical to plating
facility workers because the plating equipment caused greater volatilization of
contaminants into the air. The volatilization of chromium dissolved in groundwater
should not occur during typical residential use. Consequently, exposure to hexavalent
chromium from inhalation was not evaluated.
To ensure protection of human health, the risk assessment assumes that no action has
been taken at the site to remove the contamination, and the highest exposure that may
reasonably be expected to occur at the site was evaluated. For the Ace -Services risk
assessment it was assumed that a future Colby resident drills a new well within the area
of the groundwater contamination and then drinks and bathes with contaminated
groundwater.
To evaluate the potential for adverse health effects, excluding cancer, a hazard index
is used. The evaluation of noncarcinogenic risks for current downgradient residents and
future onsite and offsite residents through the groundwater exposure pathway resulted in
hazard indices of 0.42 and 20.0, respectively. A hazard index calculated for a site in
excess of 1.0 indicates that potential adverse health effects may occur from exposure to
the site contaminants. For the Ace Services site, the hazard index exceeded 1.0 for future
residents drinking and bathing in groundwater contaminated with hexavalent chromium.
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In other words, there is a potential for adverse health effects to occur when the
contaminated water is ingested or comes in contact with the skin. Carcinogenic risk has
not been established for dermal contact and ingestion of hexavalent chromium.
The risk evaluation for exterior surface soils, indoor dust, and indoor air consisted of
comparing the post-removal action concentrations of hexavalent chromium, lead, and
other heavy metals in these media to accepted industrial health-based screening levels.
These health-based screening levels included applicable or relevant and appropriate
requirements, risk-based concentrations, and other published exposure limits. The
evaluation found that only the lead level in indoor dust continues to be a potential health
concern for industrial and commercial uses. In addition, it is recognized that the
contaminants deposited in and on the interior building materials are the likely source of
dust contamination.
The EPA has assumed that this site will continue to be used for industrial or
commercial purposes. The levels of contamination remaining on site render the property
unsuitable for other land uses, such as residential.
6.2 Ecological Risk Assessment
The lack of any substantial contact of groundwater with flora or fauna and the
absence of threatened and endangered species critical habitat in the area indicate that an
imminent and substantial threat to the surface environment no longer exists. Therefore,
further actions taken solely to protect surface environmental receptors are unnecessary.
7.0 Remediation Objectives
The primary focus of the remedial actions is to remediate the contaminated
groundwater and on-site building interiors, which are the major risks posed from.the site,
and limit future use of the facility to industrial or commercial purposes.
Remedial action objectives developed for contaminated groundwater are to prevent
ingestion, inhalation, or direct contact with groundwater having chromium concentrations
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in excess of current regulatory drinking water standards and to prevent further migration
of chromium to prevent further degradation of natural resources.
Remedial action objectives developed for contaminated soil are to maintain
prevention of exposure to soils having total chromium or lead concentrations in excess of
current action levels and to prevent migration of chromium and lead that would result in
groundwater contamination.
Remedial action objectives developed for the contaminated buildings are to prevent
exposure to indoor air or interior dusts/concrete having total chromium, hexavalent
chromium lead, arsenic, cadmium, manganese, or nickel concentrations in excess of
industrial health-based screening levels and to prevent migration of chromium and lead
that could result in groundwater contamination.
The EPA has assumed that this facility will continue to be used for industrial or
commercial purposes. The cleanup levels have been determined to allow future use of the
facility as an industrial or commercial facility. The levels of contamination remaining on
site render the property unsuitable for other land uses, such as residential. Access
restrictions would be implemented during remediation efforts to minimize exposure to
humans.
8.0 Description of Alternatives
The Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA) requires that the selected site response action alternative be protective of
human health and the environment, be cost effective, comply with other environmental
laws, and utilize permanent solutions, alternative treatment technologies, and resource
recovery alternatives to the maximum extent practicable. In addition, the statute includes
a preference for the use of permanent treatment as a principal element for the reduction of
toxicity, mobility, or volume of the hazardous substances versus leaving the waste
untreated.
The EPA's November 1998 Feasibility Study (FS) Report evaluated in detail
remedial alternatives for addressing the contamination associated with the groundwater
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plume, on-site buildings, and exterior soils at the site. This evaluation included
consideration of the no action alternative. The alternatives for remediating the buildings
and exterior surface soil are independent of the alternatives for remediating the
groundwater. Implementation of the remedial efforts for groundwater will be complex
compared to the remedial efforts for the buildings and soil. To allow the remedial
alternative evaluation to be more effective, the groundwater alternatives were developed
separately from the buildings and soil alternatives. The FS considered six alternatives for
remediating the groundwater plume and five alternatives for remediating the on-site
buildings/soil. The groundwater alternatives are discussed in Section 8.1, and the
building and soil alternatives are discussed in Section 8.2. As part of the process of
choosing a remedy, the remedial alternatives from the FS are compared and evaluated
using nine criteria that appear in the NCP (these are discussed in Section 9 below).
For the purpose of analyzing and comparing the remedial alternatives, EPA
estimated costs of the alternatives by making certain assumptions to allow costs to be
estimated, such as estimating the remediation time for pumping and treating groundwater.
The EPA Superfund policy is to try to estimate costs within +50/-30 percent accuracy.
The present worth cost of each alternative, a summary measure of cost that, for
comparison purposes, turns a stream of payments or costs over a future period of years
into the equivalent of a single lump sum in the present, was calculated for all alternatives
assuming a 5 percent discount rate for up to 30 years. The cost estimates, as discussed
above, are conceptual, with an estimated +50 percent to -30 percent level of accuracy.
The alternatives from the FS report are described below in the remainder of Section 8.
Section 9 compares the alternatives. Section 10 discusses the selected alternative.
Section 10 also discusses several additional measures that will be taken as part of the
selected remedy, including remedial design activities.
8.1 Groundwater Alternatives
8.1.2 Groundwater Alternative 1: No Action
Capital Cost: $0
Present Worth of Annual O&M Cost: $41,700
Total Present Worth Cost: $41,700
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Construction time: 0
Cleanup time: Indefinite, unknown
Pump rate: N/A
Number of monitoring wells: N/A
Alternative 1 would not involve any remedial actions, and the site would remain in
its present condition. This alternative is a baseline alternative against which the
effectiveness of the other alternatives can be compared, as required by the National
Contingency Plan (NCP) and CERCLA. Under the no action alternative, the site is left
"as is" and no funds would be expended for monitoring, control, or cleanup of the
contaminated groundwater. However, 5-year reviews of the site would be required under
CERCLA, and accordingly, the computed "total present worth" cost was estimated to
include funds that would be expended to conduct the 5-year reviews.
8.1.2 Groundwater Alternative 2: Containment/Reduction/
Precipitation/Coagulation-Flocculation
Capital Cost: $1,398,500
Present Worth of Annual O&M Costs: $2,241,400
Total Present Worth Cost: $3,639,900
Construction time: 19 months
Cleanup time: 32 years
Pump rate: 80 gallons per minute total
Number of extraction wells: One 3-well nest
Groundwater Alternative 2 entails extraction of contaminated groundwater at the
containment rate, treatment of contaminated groundwater by electrochemical
reduction/precipitation/coagulation-flocculation, discharge of treated groundwater, and
focused groundwater monitoring.
The extraction wells would be pumped at a rate resulting in establishment of a
hydraulic barrier to prevent migration of the contaminant plume. One extraction well
nest (EX-1) would be located near the downgradient edge of the 100 fj-g/L chromium
contamination contour. The extraction well nest would consist of three wells at various
depths to address shallow, intermediate, and deep groundwater. The shallow extraction
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well would be screened from the water table (approximately 100 feet below ground
surface (bgs) to 20 feet below the water table, the second (intermediate) well would be
screened from approximately 150 to 170 feet bgs, and the third (deep) well would be
screened from the bedrock surface up 20 feet (approximately 200 to 220 feet bgs). To
achieve containment, the total groundwater extraction rate would be approximately 80
gallons per minute (gpm). Pumping rates from each extraction well would be optimized
to capture the maximum amount of contaminants. Extracted groundwater would be
pumped to an on-site treatment system by double containment underground piping. If
shallow sampling well SSW-1 is found to be contaminated above 100 //g/L total Cr, the
contaminated groundwater would be periodically recovered from this well also.
Groundwater would be collected with a submersible pump and placed in a portable tank.
The collected groundwater from well SSW-1 is estimated to be less than 200 gallons and
would be discharged into the treatment system for treatment.
In addition to the extraction well nests, four additional observation well nests would
be installed along the downgradient edge of the 100 yUg/L contour. The observation well
nests would consist of three wells and would be constructed in the same manner as the
extraction wells. One well would be screened in the shallow zone, one in the
intermediate zone, and one in the deep zone. This configuration would allow
simultaneous monitoring of drawdown in each zone and would provide information to
verify the chromium contamination capture zone of the extraction wells. Proposed well
locations are shown on Figure 5.
Groundwater monitoring would be performed to evaluate the aquifer's ability to
lower contaminant concentrations through natural attenuation. A detailed sampling and
quality assurance plan would need to be prepared. The sampling and quality assurance
plans would include the sampling locations, frequency, procedures, analysis methods, and
documentation. New monitoring wells would be added to the existing network if the
contaminant plume migrates further to the east or if further definition of the plume is
required. Any additional wells would be installed using the techniques described above.
Five additional multiport sampling wells and one shallow sampling well would be
installed. The multiport sampling wells would be constructed of 4-inch PVC casing, the
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observation wells would be constructed using 2-inch PVC, and the extraction wells would
be constructed using 6-inch PVC casing.
The multiport sampling wells would be located near MW-2, PWS-8, north of
PWS-8, south of PWS-8, and between residential well RW-1 and PWS-8. Each multiport
sampling well would be screened at three different intervals. The first screen would be
set from the static water level (approximately 100 feet bgs to 20 feet below the water
table). The next screen would be installed from 150 to 170 feet bgs with the final screen
installed from the bedrock surface (approximately 220 feet bgs) and up 20 feet.
A shallow sampling well (SSW-1) would be installed in the area of the perched
aquifer identified by KDHE during its September 1980 site investigation and would allow
for monitoring of the perched aquifer. This well would be installed to approximately 30
feet bgs with the screen interval from 20 to 30 feet bgs. The proposed locations of the
new monitoring wells are shown on Figure 5. The locations were selected to monitor the
effectiveness of the remedial efforts.
The new and previously sampled monitoring and residential wells would be sampled
quarterly for the first year and semi-annually thereafter until remedial action objectives
are attained. Frequency of the monitoring would be reevaluated and modified based upon
the effectiveness of the alternative.
The results of the sample analysis would be used with screening models to evaluate
the rate of natural attenuation and the migration of contaminants. If monitoring results
indicate that natural attenuation is occurring at an acceptable rate, further remediation
may not be necessary after the more concentrated portion of the Cr(VI) plume is
extracted.
Institutional controls would be implemented to ensure that exposure pathways are
not completed where the contaminant concentrations are above cleanup goals. Access
restrictions would consist of deed restrictions, permits, and public education. Deed
restrictions as permitted by law would be placed on properties within or near the
contaminant plume to prevent use of the contaminated groundwater as a potable water
supply. Installation of new wells would be for nonpotable uses only and would be
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allowed by permit only. Public education would be performed to inform the public of the
potential hazards associated with the contaminated groundwater and discourage the use of
it for drinking or bathing. Public education would be conducted through informational
meetings and flyers.
An electrochemical reduction process would be used to treat the contaminated
groundwater in this alternative (and all alternatives subsequently discussed). This
treatment process would involve a reduction process. A packaged treatment system using
electrochemical reduction would chemically change (reduce) the hexavalent chromium to
trivalent chromium and coprecipitate the trivalent chromium as chromium hydroxide
along with iron oxide. A treatability study would be performed as part of remedial design
efforts. The groundwater treatment system would be a packaged electrochemical
reduction/precipitation/coagulation-flocculation system that would be delivered to the
site.
Treated groundwater would be discharged on-site to the unnamed tributary to Prairie
Dog Creek. Alternatively and as appropriate, treated and untreated groundwater would
be discharged to the local Colby POTW and, at the option of state and local authorities,
the treated groundwater may be beneficially reused rather than discharged. Discharged
water would meet National Pollutant Discharge Elimination System (NPDES)
requirements. The discharge would occur on-site so a NPDES permit would not be
required, but limitations for contaminant discharge would be met.
Residual wastes (solids) generated by the chemical reduction/precipitation/
coagulation-flocculation process would be analyzed using EPA's Toxicity Characteristic
Leaching Procedure (TCLP). Residual wastes would then be disposed of as either a
hazardous or nonhazardous waste depending on the results of the TCLP analysis.
8.1.3 Groundwater Alternative 3: Active Restoration/Reduction/
Precipitation/Coagulation-Flocculation
Capital Cost: $2,170,900
Present Worth of Annual O&M Costs: $2,222,600
Total Present Worth Cost: $4,393,500
Construction time: 20 months
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Cleanup time: 17 years
Pump rate: 210 gpm total
Number of extraction wells: Two 3-well nests and PWS Well #8
Groundwater Alternative 3 entails extraction of contaminated groundwater at the
active restoration rate, treatment of contaminated groundwater by electrochemical
reduction/precipitation/coagulation-flocculation, discharge of treated groundwater, and
focused groundwater monitoring.
Five multiport sampling wells and one shallow sampling well would be installed.
The groundwater would be sampled and analyzed to evaluate natural attenuation as
described in Groundwater Alternative 2.
Two extraction well nests would be installed and used in conjunction with PWS Well
#8 to achieve remediation goals. The turbine pump in PWS Well #8 would be removed
and replaced with a submersible pump capable of pumping 70 gpm. Each extraction well
nest would be pumped at an approximate rate of 70 gpm for a total flow of 210 gpm.
Pumping rates from each individual extraction well and well nest would be optimized to
capture the maximum amount of contaminants. One extraction well nest (EX-2) would
be located near MW-2. The well nest would include the installation of shallow and
intermediate-depth extraction wells to complete the extraction well nest. The other
extraction well nest (EX-1) would be located at the downgradient edge of the 100 Aig/L
chromium contamination plume contour. Four observation well nests would be installed
as described in Groundwater Alternative 2, with the addition of two more observation
well nests installed in the same manner to evaluate the capture zone of the upgradient
extraction well nest EX-2. The additional observation well nests would be located
approximately 120 feet north and 150 feet southeast of extraction well EX-2,
respectively. If shallow sampling well SSW-1 is found to be contaminated above 100
/^g/L total Cr, the contaminated groundwater would be extracted from this well as
described in Groundwater Alternative 2. Proposed well locations are shown on Figure 6.
Contaminated groundwater would be pumped to an on-site treatment system by
double containment underground piping similar to that in Groundwater Alternative 2.
Hexavalent chromium would be reduced to trivalent chromium by electrochemical
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precipitation. Trivalent chromium would then be co-precipitated out of solution as
chromium hydroxide along with iron oxide. The treatment process for this alternative
is similar to the process described for Groundwater Alternative 2.
Treated groundwater would then be discharged on-site to the unnamed tributary to
Prairie Dog Creek. Alternatively and as appropriate, treated and untreated groundwater
would be discharged to the local Colby Publicly Owned Treatment Works (POTW), and
at the option of state and local authorities, the treated groundwater may be beneficially
reused rather than discharged. Discharged water would meet NPDES requirements. The
discharge would occur on-site so a NPDES permit would not be required, but limitations
for contaminant discharge would be met.
Residual wastes (solids) generated by the electrochemical reduction/precipitation
process would be analyzed using EPA's TCLP analysis procedure. Residual waste would
then be disposed of as either a hazardous or nonhazardous waste based on the results of
the TCLP analysis.
Institutional controls would be implemented at the site as described under
Groundwater Alternative 2.
8.1.4 Groundwater Alternative 4: Containment/Ion Exchange
Capital Cost: $1,581,900
Present Worth of Annual O&M Costs: $2,348,800
Total Present Worth Cost: $3,930,700
Construction time: 19 months
Cleanup time: 32 years
Pump rate: 80 gpm total
Number of extraction wells: One 3-well nest
Groundwater Alternative 4 entails extraction of contaminated groundwater at the
containment rate, treatment of contaminated groundwater by ion exchange, discharge of
treated groundwater and focused groundwater monitoring.
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The number, location, size, and depth of extraction, observation, and sampling wells
for this alternative are as described in Groundwater Alternative 2 and as illustrated on
Figure 5.
The groundwater treatment system would be a packaged ion exchange system that
would be delivered to the site. A treatability study would be performed as part of
remedial design efforts.
Extracted groundwater would be pumped from the extraction well system to the
influent holding tank for flow equalization. Groundwater would then be sent to the anion
exchanger where hexavalent chromium would be removed by the ion exchange process.
Following hexavalent chromium removal, trivalent chromium would be removed in the
cation exchanger. Groundwater would then be discharged.
Treated groundwater would then be discharged on-site to the unnamed tributary to
Prairie Dog Creek. Alternatively and as appropriate, treated and untreated groundwater
would be discharged to the local Colby POTW and, at the option of state and local
authorities, the treated groundwater may be beneficially reused rather than discharged.
Discharged water would meet NPDES requirements. The discharge would occur on-site
so a NPDES permit would not be required, but limitations for contaminant discharge
would be met.
Residual wastes (solids) generated by the ion exchange process would be analyzed
using EPA's TCLP analysis procedure. Residual wastes would then be disposed of as
either a hazardous or nonhazardous waste based on the results of the TCLP analysis.
Institutional controls would be implemented at the site as described under
Groundwater Alternative 2.
8.1.5 Groundwater Alternative 5: Active Restoration/Ion Exchange
Capital Cost: $2,310,600
Present Worth of Annual O&M Costs: $2,249,700
Present Worth Cost: $4,560,300
Construction time: 20 months
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Cleanup time: 17 years
Pump rate: 210 gpm total
Number of extraction wells: Two 3-well nests and PWS Well #8
Groundwater Alternative 5 entails extraction of contaminated groundwater at the
active restoration rate, treatment of contaminated groundwater by ion exchange,
discharge of treated groundwater, and focused groundwater monitoring.
The number, location, size and depth of the extraction, observation, and sampling
wells are identical to those described in Groundwater Alternative 3, including pumping
well SSW-1, and as illustrated on Figure 6. The process units and the ion exchange
treatment processes would be similar to that described under Groundwater Alternative 4.
Treated groundwater would then be discharged on-site to the unnamed tributary to
Prairie Dog Creek. Alternatively and as appropriate, treated and untreated groundwater
will be discharged to the local Colby POTW and, at the option of state and local
authorities, the treated groundwater may be beneficially reused rather than discharged.
Discharged water would meet NPDES requirements. The discharge would occur on-site
so a NPDES permit would not be required, but limitations for contaminant discharge
would be met.
Residual wastes (solids) generated by the ion exchange process would be analyzed
using EPA's TCLP analysis procedure. Residual wastes would then be disposed of as
either a hazardous or nonhazardous waste based on the results of the TCLP analysis.
Institutional controls would be implemented at the site as described under
Groundwater Alternative 2.
8.1.6 Groundwater Alternative 6: Active Restoration/Reduction/
Precipitation/Coagulation-Flocculation/In-Situ Bioremediation
Capital Cost: $2,552,500
Present Worth of Annual O&M Costs: $ 1,937,000
Present Worth Cost: $4,489,500
Construction time: 21 months
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Cleanup time: 13 years
Pump rate: 210 gpm total
Number of extraction wells: Two 3-well nests and PWS Well #8
Groundwater Alternative 6 entails extraction of contaminated groundwater at the
active restoration rate, treatment of contaminated groundwater by electrochemical
reduction/precipitation/coagulation-flocculation, discharge of treated groundwater, and
in-situ bioremediation.
The number, location, size, and depth of the extraction, observation, and sampling
wells are identical to those described in Groundwater Alternative 3, including pumping
well SSW-1, and as illustrated on Figure 5. The process units and the
reduction/precipitation treatment processes would be similar to that described under
Groundwater Alternative 2.
Treated groundwater would be discharged on-site to the unnamed tributary to Prairie
Dog Creek. Alternatively and as appropriate, treated and untreated groundwater would
be discharged to the local Colby POTW and, at the option of state and local authorities,
the treated groundwater may be beneficially reused rather than discharged. Discharged
water would meet NPDES requirements. The discharge would occur on-site so a NPDES
permit would not be required, but limitations for contaminant discharge would be met.
Residual wastes (solids) generated by the chemical reduction/precipitation/
coagulation-flocculation process would be analyzed using EPA's TCLP analysis
procedure. Residual wastes would then be disposed of as either a hazardous or
nonhazardous waste depending on the TCLP results analysis.
Included in this alternative is in-situ bioremediation which would be implemented to
enhance remediation efforts provided successful implementation of the process is
demonstrated during the Remedial Design (RD) treatability studies. One criteria for
determining successful implementation would be an evaluation as to whether the
groundwater remaining in the remediated aquifer zone would be acceptable for possible
beneficial reuse after bioremediation was completed. In-situ bioremediation would be
used to complement the extraction of contaminated groundwater. In-situ bioremediation
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would be implemented provided treatability studies during remedial design show the
reduction process to be successful. In-situ bioremediation would help reduce rebound
and tailing effects common to pump-and-treat remedial actions. The volume of extracted
groundwater would be comparatively less than other alternatives because the estimated
number of pore-space flushings needed to remove the chromium would be less.
In-situ bioremediation would consist of two primary components: the process
system and the distribution system. The process system would include a carbon source
storage tank, mixing tank, potable water supply, and circulation pump. The carbon
source would be diluted with water to the desired concentration in the mixing tank and
the mixture would be recirculated until injection. The five multiport monitoring wells
would be used as the injection wells unless the treatability study indicates that separate
wells in a well nest would be needed.
During remedial design, a field scale groundwater treatability study would be
performed to confirm microbial reduction of Cr(VI) by the carbon source, determine the
optimum concentration of the carbon source, and evaluate potential biofouling affects.
The injection rate of the carbon source would initially be estimated through groundwater
modeling efforts and would ultimately be determined during the field scale treatability
study.
Groundwater would be monitored to detect changes in the migration and reduction of
contamination and to assess the effectiveness of the remedial action. The observation
wells, monitoring wells, and extraction wells would be monitored and used to evaluate
the treatment system.
Parameters included in the monitoring program include total chromium, hexavalent
chromium, temperature, pH, specific conductivity, dissolved oxygen, oxidation/reduction
potential, and organic carbon.
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8.2 Buildings/Soils Alternatives
The buildings to be remediated include both the plating shop and the machine shop
as illustrated on Figure 2. Exterior soils media have also been included in the remedial
alternatives.
8.2.1 Buildings/Soil Alternative 1: No Further Action
Capital Cost: $0
Present Worth of Annual O&M Costs: $41,700
Present Worth Cost: $41,700
Construction time: N/A
O&M duration: + 30 years
Building/Soil Alternative 1 would not involve any further remedial action for the soil
or buildings beyond the efforts performed as part of the removal action. Under the no
further action alternative, the site would remain in its present condition. Previous
removal action efforts involved washing the interior of the plating shop building, removal
of the plating vat troughs A, B, and C and removal of contaminated soil. In addition, the
floor was also treated with sulfuric acid and sodium metabisulfite to reduce the
hexavalent to trivalent chromium. The no action alternative is a baseline alternative
against which the effectiveness of the other alternatives can be compared, and was
evaluated as required by the National Contingency Plan (NCP) and CERCLA. The only
additional activity would be CERCLA Section 121(c) periodic reviews of the site
performed by the EPA as required by the NCP. The CERCLA Section 121 (c) periodic
reviews are required if a remedial action is selected that results in hazardous substances,
pollutants, or contaminants remaining at the site above levels that allow for unlimited use
and unrestricted exposure.
8.2.2 Buildings/Soil Alternative 2: Limited Action
Capital Cost: $9,700
Present Worth of Annual O&M Costs: $41,700
Present Worth Cost: $51,400
Construction time: N/A
O&M duration: +30 years
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Building/Soil Alternative 2 would involve placement of deed restrictions as
permitted by law to prevent exposure to contaminants, and also includes 5-year reviews.
The deed restrictions would be implemented to notify future owners of the contamination
present in the foundation soils beneath the concrete floor of the plating shop building and
the exterior soils. Zoning restrictions would be implemented by local authorities to
restrict changing the zoning of the site to residential, in addition to limiting the types of
industries that could occupy both buildings. Industries such as human health care, child
care centers, and food processing/handling businesses would be restricted from using the
site.
5.2.3 Buildings/Soil Alternative 3: Surface Cleaning/Disposal
Capital Cost: $83,300
Present Worth of Annual O&M Costs: $163,700
Present Worth Cost: $247,000
Construction time: 2 months
O&M duration: +30 years
Building/Soil Alternative 3 would include the dusting, vacuuming, and wiping of all
surfaces in the interior of both buildings, including the floors, walls, ceiling, and exposed
trusses. Since these activities may not involve the removal of the source of the lead and
chromium contamination in the dust, a deed restriction would still be required to limit
future use of the site and buildings as discussed in the previous sections. The debris from
the dusting, vacuuming, and wiping would be disposed in a Resource Conservation and
Recovery Act (RCRA) hazardous or a solid waste landfill, as required. The deed
restrictions described under Building/Soil Alternative 2 are also included under this
alternative.
8.2.4 Buildings/Soils Alternative 4: Surface Layer Removal/Disposal
Capital Cost: $228,200
Present Worth of Annual O&M Costs: $41,700
Present Worth Cost: $269,900
Construction time: 4 months
O&M duration: + 30 years
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Building/Soil Alternative 4 would involve the decontamination of both buildings by
removing the contaminated surface concrete. Wipe samples would be collected at various
depths and surfaces prior to and during remedial design to determine the areas requiring
removal. The remediation levels would allow the buildings to only be used for industrial
or commercial uses.
The surface concrete would be removed by grit blasting. The material to be used and
the depth required for complete removal would be determined during the remedial design.
Since all surfaces within the buildings are not concrete, other surfaces within the
buildings may require additional dusting, vacuuming and wiping to ensure the complete
cleaning of all surfaces within the buildings. The cleaning and concrete debris and
grit-blasting material would be disposed in roll-off containers. The debris and
grit-blasting materials would be analyzed and all materials would be disposed in a RCRA
hazardous or a solid waste landfill, as appropriate.
Land use restrictions would be implemented to limit future use of the site to certain
industrial or commercial uses as discussed for Building/Soil Alternative 2.
8.2.5 Buildings/Soil Alternative 5: Encapsulation/Disposal
Capital Cost: $127,100
Present Worth of Annual O&M Costs: $177,700
Present Worth Cost: $304,800
Construction time: 4 months
O&M duration: + 30 years
Building/Soil Alternative 5 would prepare the interior surfaces by dusting,
vacuuming, and wiping the dust and debris from both buildings for the subsequent
application of encapsulation coatings to all interior surfaces in both buildings. Wipe
sampling would be conducted on all representative surfaces to determine the need for
encapsulation. The specific encapsulation coatings would be determined during the
remedial design. The debris from the dusting, vacuuming, and wiping and other
encapsulation debris would be disposed in a RCRA hazardous or a solid waste landfill, as
appropriate.
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Since the contaminants would still be in place, land use restrictions would be
implemented to limit future use of the site to certain industrial or commercial uses. A
maintenance program would be required as part of the deed restriction to maintain the
integrity of the encapsulation and ensure the continued effectiveness of the containment
of contaminants.
9.0 Comparative Analysis of Alternatives
During the comparative analysis of the alternatives, each alternative is assessed
against nine evaluation criteria. These criteria are: overall protection of human health
and the environment; compliance with applicable or relevant and appropriate require-
ments; long-term effectiveness and permanence; reduction of toxicity, mobility, or
volume; short-term effectiveness; implementability; cost; state acceptance and
community acceptance.
The following comparative analysis presents the strengths and weaknesses of the
alternatives relative to one another with respect to each of the nine criteria, and how
reasonable variations of key uncertainties could change the expectations of their relative
performance. Under each individual criterion, the altemative(s) that performs the best
overall in that category is discussed first, with other alternatives discussed in the relative
order in which they perform.
9.1 Groundwater Alternatives
9.1.1 Overall Protection of Human Health and the Environment
Overall protection of human health and the environment addresses whether or not a
remedy provides adequate protection and describes how risks posed through each
pathway are eliminated, reduced, or controlled through treatment, engineering controls, or
institutional controls.
Groundwater Alternative 6 would be the most protective of human health and the
environment. Not only would all groundwater with contaminant concentrations greater
than cleanup levels be actively remediated, the cleanup goals would be reached earlier
than all other alternatives. The treatment technology, including reduction and
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precipitation, is anticipated to be the most effective treatment option for the extracted
contaminated groundwater. In-situ bioremediation would also occur to help reduce
contamination.
Groundwater Alternative 1 would not protect human health and the environment
from the contaminants in the groundwater in the vicinity of the site. Because no actions
would occur under Alternative 1, the groundwater contaminants may continue to migrate
and eventually contaminate downgradient residential and public supply wells and produce
a larger contaminant plume. Alternatives 2 and 4 would be more protective of human
health and the environment than Alternative 1. The containment and treatment system in
Alternatives 2 and 4 would be effective in ensuring that further migration of contaminants
does not occur; thus, the contaminants would not further contaminate additional wells.
However, only some protection of the environment would occur because although
groundwater would be extracted and treated, it would not be actively remediated. Thus,
groundwater would continue to be contaminated for an extended period
Groundwater Alternatives 3 and 5 would be more protective of human health and the
environment than Alternatives 1, 2, and 4 because all groundwater with contaminant
concentrations greater than cleanup levels would be actively remediated. The cleanup
goals would be reached earlier with Alternatives 3 and 5 than with Alternatives 2 and 4.
The technologies used in Alternatives 2 and 3 (extraction and treatment by reduction/
precipitation/coagulation-flocculation) are proven effective for the removal of chromium
from groundwater and have been used at numerous sites. The technologies used in
Alternatives 4 and 5 (extraction and ion exchange) are also proven effective in the
removal of chromium from groundwater.
Other than contamination that remains until cleanup goals are met, no short-term
risks would be expected in any of the alternatives. The no action alternative would not
address groundwater contamination, and would result in risks.
9.1.2 Compliance with Applicable or Relevant and Appropriate Requirements
(ARARs)
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Compliance with ARARs addresses whether or not a remedy would meet all of the
applicable or relevant and appropriate requirements of other federal and state
environmental statutes and requirements or provide grounds for invoking a waiver.
All alternatives, excluding Alternative 1, would comply with all location- and action-
specific ARARs and would be anticipated to comply with all chemical-specific ARARs.
9.7.3 Long-Term Effectiveness and Permanence
Long-term effectiveness and permanence refers to the ability of a remedy to maintain
reliable protection of human health and the environment over time, once cleanup goals
have been met.
Groundwater Alternatives 2, 3, 4, 5, and 6 would have less of a long-term risk than
Alternative 1. A long-term risk would not be associated with the treated groundwater in
Alternatives 2, 3, 4, 5, and 6. However, a long-term risk would remain with the untreated
aquifer until cleanup levels would be met. Alternative 6 would offer effectiveness and
permanence earlier than all other alternatives because water would be remediated at a
faster rate. Alternative 6 is expected to reach cleanup goals in 13 years. Alternatives 3
and 5 would be expected to reach cleanup goals in 17 years. The amount of time to reach
cleanup goals if Alternatives 2 or 4 are implemented is estimated to be 32 years.
Because no remedial actions would occur, a long-term risk would be associated with
Groundwater Alternative 1 as long as cleanup goals are not met. The possibility exists
for the contaminant plume to expand and no mechanism would be in place to monitor
whether the plume is expanding so as to threaten additional water wells.
Five-year reviews would be required for all alternatives. Groundwater Alternative 1
would require the greatest number of 5-year reviews because restoration, if achieved,
would take the longest. Fewer reviews would be required for Alternatives 3 and 5 than
for Alternatives 2 and 4, and the fewest reviews would be required for Alternative 6.
The proposed monitoring plan and treatment technologies in Groundwater
Alternatives 2,3,4, 5, and 6 should adequately and permanently achieve the performance
specifications established in the remedial action objectives. Because no action would
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occur in Alternative 1, there would be no mechanism to determine if remedial action
objectives would be met.
Long-term management would be required for all the alternatives with the exception
of Groundwater Alternative 1. Maintenance, along with a long-term monitoring program,
would need to be performed on a regular basis for Groundwater Alternatives 2, 3,4, 5,
and 6. Maintenance would be more involved with Alternatives 3 and 5, and the most
involved with Alternative 6 because more wells and equipment would be required. The
monitoring program and maintenance for all alternatives would be extensive, but easily
implemented. Components of the treatment system such as pumps and valves in
Alternatives 2, 3, 4, 5, and 6 may require replacement during site remediation. However,
proper maintenance of the equipment should minimize the need for costly repairs and
replacements.
9.1.4 Reduction ofToxicity, Mobility, and Volume Through Treatment
Reduction of toxicity, mobility, or volume through treatment is the anticipated
performance of the treatment technologies a remedy may employ.
It is unknown if a reduction in toxicity, mobility, or volume would occur in
Groundwater Alternative 1. Alternative 1 provides no mechanisms to determine if
reduction is occurring. A reduction in toxicity, mobility, and volume would occur in
Groundwater Alternatives 2, 3, 4, 5, and 6. The reduction would take much longer under
Alternatives 2 and 4 than Alternatives 3 and 5, and would be the shortest period under
Alternative 6. The groundwater treatment would permanently remove contamination
from groundwater to the extent the system was effective at contaminant removal. Wastes
would be produced from Alternatives 2, 3,4, 5, and 6, except for any portion directly
discharged to the POTW. Alternatives 3,5, and 6 would generate residual waste at a
faster rate then Alternatives 2 and 4. However, Alternatives 3, 5, and 6, would require
shorter operational times thus residual wastes may be generated faster, but for a shorter
duration. All the alternatives except Alternative 1 would meet the statutory preference
for treatment as a principal element.
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9.7.5 Short-Term Effectiveness
Short-term effectiveness addresses the period of time needed to achieve protection
and any adverse impacts on human health and the environment that may be posed during
the construction and implementation period until cleanup goals are achieved.
Nearby residents may be exposed to contaminated dusts during installation of
monitoring and extraction wells. This risk would be controlled by the use of dust
suppressants. The risk to workers involved with remediation activities would be
controlled by proper use of personal protection equipment and monitoring during site
activities.
9.1.6 Implementability
Implementability is the technical and administrative feasibility of a remedy,
including the availability of materials and services needed to implement a particular
option.
Because no actions would be taken during Alternative 1, this criteria is not
applicable. Groundwater Alternatives 2, 3,4, 5, and 6 include installation of 5 multiport
sampling wells and a groundwater sampling program, and also require the installation of
observation and extraction wells and more extensive treatment system components.
Alternatives 2 and 4 (containment) would be easier to implement than Alternatives 3, 5,
and 6 (active restoration) because fewer extraction and observation wells would be
required. Alternative 6 also includes implementation of the in-situ bioremediation
efforts. The groundwater treatment system components (pumps, piping, treatment unit,
etc.) for Alternatives 3, 5, and 6 would also be substantially larger and may require more
maintenance than Alternatives 2 and 4.
Groundwater Alternatives 2 and 3 (reduction/precipitation/coagulation-flocculation)
offer more flexibility for treating variable influent contaminant concentrations than
Alternatives 4 and 5 (ion exchange). It is assumed that in Alternatives 2 and 3,
replacement of the electrodes would be required on a monthly basis. This can be done
quickly and inexpensively. Alternatives 4 and 5 do not require monthly replacements of
components but would require replacement of the ion exchange resin at some point in
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time. It is difficult to anticipate the schedule for replacement of the resin, but when
needed it would require a more substantial effort than replacement of the electrodes.
Groundwater Alternative 6 would be the most difficult to implement since it consists
of the active restoration extraction and treatment system equipment and the in-situ
bioremediation system. Implementability of in-situ bioremediation will be evaluated
during remedial design treatability studies. One criteria for determining successful
implementation would be an evaluation as to whether the groundwater remaining in the
remediated aquifer zone would be acceptable for possible beneficial reuse after
bioremediation was completed. The in-situ bioremediation system would require
additional injection equipment that would need to be installed, including batch-mixing
equipment, discharge lines, and associated equipment. More intensive operation and
maintenance of the system would also be required.
The necessary equipment and personnel required to implement each alternative
would be readily available. A treatability study would be required for Groundwater
Alternatives 2, 3, 4, 5, and 6. More than one vendor is available for each alternative to
provide a competitive bid.
9.7.7 Cost
Cost includes estimated capital and operation and maintenance costs, and net present
worth costs. The cost comparisons for the alternatives includes the detailed cost
estimates for each alternative.
A cost comparison for the groundwater alternatives includes the detailed cost
estimates for each alternative.
The sole costs associated with Groundwater Alternative 1 would be O&M costs
converted to a total present worth. The total present worth of Groundwater Alternative 1
would be the lowest at a cost of $41,700. The total present worth cost of Groundwater
Alternative 5 would be the greatest at a cost of $4,560,300. The total present worth costs
of Groundwater Alternatives 2, 3, 4, and 6 are $3,639,900, $4,393,500, $3,930,700 and
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54,489,500 respectively. In general, the cheaper the alternative, the lesser its
effectiveness at meeting cleanup goals and the longer the period of time to achieve
cleanup goals.
9.1.8 State Acceptance
State acceptance indicates whether, based on its review of the RI and FS reports and
Proposed Plan, the state concurs, opposes, or has no comment on the preferred
alternative.
The state of Kansas has been involved with this site since the beginning of closure
activities and has reviewed the RI Report, the FS Report, and the Proposed Plan. The
state of Kansas prefers that a permanent solution, with low O&M costs, be selected. The
State has indicated its support of the selected remedy.
9.1.9 Community Acceptance
Community acceptance of the selected remedy is discussed in detail in the
Responsiveness Summary of this ROD. In general, the community has supported the
conclusions of the FS and the preferred alternative presented in the Proposed Plan. The
public comments concentrated on consideration of reuse of the treated groundwater rather
than discharge, because this water is a valuable resource in western Kansas.
9.2 Buildings/Soils Alternative Analysis
For each Buildings/Soils Alternative, the soils around the foundation of the plating
shop building would remain in place. It has been assumed that deed restrictions proposed
for Buildings/Soil Alternatives 2, 3, 4, and 5 would prevent exposure to contaminated
soil. Removal of the contaminated soil could not be performed without jeopardizing the
structural integrity of the building.
9.2.1 Overall Protection of Human Health and the Environment
Buildings/Soil Alternative 4 would be most protective of human health and the
environment because contaminants would be removed during cleaning and remaining
contaminants within the building materials would also be removed. Deed restrictions
would prohibit residential and certain commercial uses of the site.
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Buildings/Soil Alternative 1 would not protect human health and the environment
from the contamination in the buildings and exterior soils of the site. Since no action
would be conducted with Buildings/Soil Alternative 1, the potential for exposure to the
contaminants left on-site would exist if further development, or re-zoning of the property
occurred. Uses that include more exposure to the building interior than a few hours a
week could result in harmful exposure to the contaminants.
Although no remediation would occur with Buildings/Soil Alternative 2, this
alternative would be more protective than Alternative 1. Buildings/Soil Alternative 2
would restrict the use of the property to certain commercial uses and prohibit the
removal of the concrete floor without the prior modification of the deed restrictions by
EPA. The protectiveness of this alternative would be limited due to the presence of the
contaminants on site, although, the exposure would be limited only to workers.
Buildings/Soil Alternatives 3 and 5 would be more protective of human health and
the environment than the previous alternatives, since they would actually clean and/or
remove contaminated dust and debris from the buildings. However, the contaminated
soil and materials within the concrete floor would remain on site. The deed restriction,to
maintain the encapsulation and a dust control procedure would provide some additional
protection to any worker in the buildings. Proper maintenance of the encapsulation
would prevent exposure to the workers.
9.2.2 Compliance with ARARs
Buildings/Soil Alternatives 1 and 2 do not comply with chemical-specific ARARs.
Only Buildings/Soil Alternatives 3,4, and 5 would comply with chemical-specific
ARARs. There would be no location-specific ARARs associated with Buildings/Soil
Alternatives 2 through 5. There would be several action-specific ARARs which require
compliance for Buildings/Soil Alternatives 3 through 5.
9.2.3 Long-Term Effectiveness and Permanence
Buildings/Soil Alternative 4 would remove contaminants from within the buildings
and would likely be the most effective and permanent remedial action for the buildings
and remaining contaminated soils. A long-term risk would be associated with
Buildings/Soil Alternative 1 because no remedial actions would occur. Buildings/Soil
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Alternatives 2 through 5 would provide deed restrictions to assist in the protectiveness of
the specific alternative. The long-term effectiveness of the deed restriction would be
dependent on the state and community acceptance of the restriction and assistance in
enforcement. Alternative 3 would clean all of the surfaces and minimize the dust levels.
Alternative 4 would remove some of the contaminants from the site and reduce the dust
levels. Alternative 5 would immobilize the contaminants, however, use of the buildings
with Alternative 5 would be more restricted than with the other alternatives due to the
continuous maintenance requirements and the inspection and protection procedures for
the encapsulation coating. The estimated life expectancy of the coatings would be 30
years.
9.2.4 Reduction ofToxicity, Mobility, and Volume
Buildings/Soil Alternative 4 would be the most effective at removing contaminants
from the buildings. The contaminants would remain at the current levels for Alternatives
1 and 2. Buildings/Soil Alternative 3 would remove some of the contaminants from the
site. Alternative 5 would immobilize the contaminants, provided the maintenance
procedures would be correctly implemented.
9.2.5 Short-Term Effectiveness
There is no short-term risk to community and the environment for Buildings/Soil
Alternatives 1 and 2 during remediation, since no action is taken at the site. Of course,
exposures would occur if the buildings were to be used. All other alternatives would
have some worker exposure to the dust during implementation of the remedial actions.
Buildings/Soil Alternatives 3, 4, and 5 would reduce the exposure to the contaminated
dust and debris with the implementation of proper personal protection, Level C or B,
depending on the dust levels monitored. During implementation for these alternatives,
site access would be restricted only to the workers, thereby minimizing the exposure to
community and the environment.
9.2.6 Implementability
Buildings/Soil Alternative 1 is not evaluated for implementability. All other
alternatives would be considered to be technically feasible with varying degrees of
administrative oversight required for implementation due to the deed restrictions. The
deed restrictions may need to undergo a review by the community and the state to ensure
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acceptance and assist in the enforcement of the restrictions. The necessary equipment
and personnel required to implement Buildings/Soil Alternatives 3, 4, and 5 would be
readily available. The effort required to implement Buildings/Soil Alternatives 3 and 4
would be approximately the same since the surface cleaning would need to be conducted
on the walls and ceiling for both alternatives. Implementation of Buildings/Soil
Alternative 5 would require some additional effort based on the surface preparation
requirements for each of the encapsulation coatings required for concrete and metal.
9.2.7 Cost
A cost comparison for the buildings/soil alternatives includes the detailed cost
estimates for each alternative.
The O&M costs for the periodic reviews converted to a total present worth are the
only cost for Buildings/Soil Alternative 1. No capital costs would be associated with
Buildings/Soil Alternative 1. The total present worth cost for Alternative 1 would be the
lowest at a cost of $41,700. The total present worth cost for Buildings/S6il Alternative 5
would be the greatest at a cost of $304,800. The total present worth costs for
Buildings/Soil Alternatives 2, 3, and 4, would be $51,400, $247,000, and $269,900,
respectively.
9.2.8 State Acceptance
State acceptance indicates whether, based on its review of the RI and FS reports and
Proposed Plan, the state concurs, opposes, or has no comment on the preferred
alternative.
The state of Kansas has been involved with this site since the beginning of closure
activities and has reviewed the RI Report, the FS Report, and the Proposed Plan. The
state of Kansas prefers that a permanent solution, with low O&M costs, be selected. The
State has indicated its support of the selected remedy.
9.2.9 Community Acceptance
Community acceptance of the selected remedy is discussed in detail in the
Responsiveness Summary of this ROD. In general, the community has supported the
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conclusions of the FS and the preferred alternative presented in the Proposed Plan.
Public comment centered on reuse of the buildings.
10.0 Selected Remedy
The selected remedy for the Ace Services Site will consist of Groundwater
Alternative 6 (Active Restoration/Reduction/Precipitation/Coagulation-Flocculation/
In-situ Bioremediation) and Buildings/Soil Alternative 4 (Surface Layer Removal (Grit
Blasting)/Disposal). These alternatives will provide the best balance of trade-offs among
alternatives with respect to the evaluating criteria. The EPA believes Groundwater
Alternative 6 and Buildings/Soil Alternative 4 will be protective of human health and the
environment, will comply with ARARs, will be cost effective, and will utilize permanent
solutions and alternative treatment technologies or resource recovery technologies to the
maximum extent practicable. The remedy also will meet the statutory preference for the
use of treatment as a principal element.
10.1 Description of Selected Remedy
10.1.1 Groundwater
The preferred remedy for groundwater entails extraction of contaminated
groundwater at the active restoration rate, treatment of contaminated groundwater by
electrochemical reduction/precipitation/coagulation-flocculation, discharge of treated
groundwater, and in-situ bioremediation.
Extraction
Two extraction well nests will be installed and used in conjunction with Public
Water Supply (PWS) Well #8 to achieve remediation goals. The turbine pump in PWS
Well #8 will be removed and replaced with a submersible pump capable of pumping 70
gallons per minute (gpm). Each extraction well nest will be pumped at an approximate
rate of 70 gpm for a total flow of 210 gpm. Each extraction well nest would consist of
three wells at various depths to respectively address shallow, intermediate, and deep
groundwater. The shallow extraction well would be screened from the water table
(approximately 100 feet below ground surface (bgs)) to 20 feet below the water table, the
second (intermediate) well would be screened from approximately 150 to 170 feet bgs,
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and the third (deep) well would be screened from the bedrock surface up 20 feet
(approximately 200 to 220 feet bgs). Pumping rates from each individual extraction well
and well nest will be optimized to capture the maximum amount of contaminants. One
extraction well nest (EX-2) will be located as part of Well MW-2. This well nest will
include the installation of shallow and intermediate-depth extraction wells to complete
the extraction well nest. The other extraction well nest (EX-1) will be located at the
downgradient edge of the 100 /^g/L chromium contamination plume contour.
Four observation well nests will be installed as described in Groundwater Alternative
2, with the addition of two more observation well nests installed in the same manner to
evaluate the capture zone of the upgradient extraction well nest EX-2. The additional
observation well nests will be located approximately 120 feet north and 150 feet
southeast of extraction well EX-2, respectively. If shallow sampling well SSW-1 is
found to be contaminated above 100 /ug/L total Cr, the contaminated groundwater would
be periodically recovered from this well also. Groundwater would be collected with a
submersible pump and placed in a portable tank. The collected groundwater from well
SSW-1 is estimated to be less than 200 gallons and would be discharged into the
treatment system for treatment. Proposed well locations are shown on Figure 6.
Treatment
An electrochemical reduction process will be used to treat the contaminated
groundwater in the preferred alternative. This process option was selected for the
following reasons. -
• Process is not pH sensitive.
• Requires less operator interaction.
• Flocculation and sedimentation steps are more easily completed.
• Treats a wider concentration range of Cr(VI) in the influent.
A packaged treatment system using electrochemical reduction will chemically
change (reduce) the hexavalent chromium to trivalent chromium and coprecipitate the
trivalent chromium as chromium hydroxide along with iron oxide. A treatability study
will be performed as part of remedial design efforts.
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The packaged electrochemical reduction/precipitation/coagulation-flocculation
system that will be used to treat the groundwater will be delivered to the site. The
packaged system will consist of the following process units.
• Influent holding tank.
• Electrochemical precipitation unit.
• Flash/Floe tank.
• Degas tank.
• Polymer feed system.
• Inclined plate settler.
• Sand filter.
Effluent holding tank.
• Sludge holding tank.
• Filter press.
• Mix tanks and surge tanks.
• Filtrate tank.
• Pumps.
Extracted groundwater will be pumped from the extraction well system to the
influent holding tank for flow equalization. Groundwater will then be pumped to the
electrochemical precipitation (ECP) unit. In the ECP unit, iron is put into solution using
charged carbon steel electrodes. As the hexavalent chromium is passed through the
charged electrodes, it is chemically changed to trivalent chromium. Hydrogen gas and
hydroxide ions are also produced as water passes by the charged electrodes. The trivalent
chromium and iron subsequently coprecipitate as solid chromium hydroxide and iron
hydroxide. Following the ECP unit, the groundwater is passed through a degas tank to
vent off the hydrogen and then through a flash/floe tank where a polymer is added to aid
flocculation. Any chromium and iron hydroxide solid that settles in the flash/floe tank
are pumped directly to the sludge storage tank. The groundwater is then passed through
an inclined plate settler to remove the chromium and iron hydroxide solids and then
through a continuous backwash type sand filter to remove any remaining fine solids. The
treated groundwater is pumped to the effluent holding tank prior to being discharged.
The water backwash stream will be routed to the flash/floe tank. Chromium hydroxide
precipitate from the inclined plate settler will be pumped to the sludge holding tank.
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Periodically, sludge in the sludge holding tank will be dewatered using a filter press
before off-site disposal. Liquid generated during the sludge dewatering process will be
pumped back to the influent holding tank.
Treated groundwater will be discharged on-site to the unnamed tributary to Prairie
Dog Creek. Alternatively and as appropriate, treated and untreated groundwater will be
discharged to the local Colby POTW, and at the option of the state and local authorities,
the treated groundwater may be beneficially reused rather than discharged. However, the
cost estimate for the alternative was based on discharge of the treated groundwater to the
on-site unnamed tributary to Prairie Dog Creek; a more detailed cost estimate will be
prepared during remedial design. Other discharge options may require additional efforts
and equipment not included in the cost estimate for the alternative. Discharged water will
meet NPDES requirements. The discharge will occur on-site so a NPDES permit will not
be required, but limitations for contaminant discharge will be met.
Residual wastes (solids) generated by the chemical reduction/precipitation/
coagulation-flocculation process will be analyzed using EPA's Toxicity Characteristic
Leaching Procedure (TCLP). Residual wastes will then be disposed of as either a
hazardous or nonhazardous waste depending on the results of the TCLP analysis.
Monitoring
Groundwater will be monitored to detect changes in the migration and reduction of
contamination and to assess the effectiveness of the remedial action. A detailed sampling
and quality assurance plan will be prepared. The sampling and quality assurance plans
will include the sampling locations, frequency, procedures, analysis methods, and
documentation. New monitoring wells will be added to the existing network if the
contaminant plume migrates or if further definition of the plume is required. Additional
wells will be installed using conventional techniques.
Five additional multiport sampling wells and one shallow sampling well will be
installed. The multiport sampling wells will be constructed of 4-inch PVC casing, the
observation wells will be constructed using 2-inch PVC, and the extraction wells will be
constructed using 6-inch PVC casing.
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The multiport sampling wells will be located near MW-2, PWS-8, north of PWS-8,
south of PWS-8, and between residential well RW-1 and PWS-8. Each multiport
sampling well will be screened at three different intervals. The first screen will be set
from the static water level (approximately 100 feet bgs) to 20 feet below the water table.
The next screen will be installed from 150 to 170 feet bgs with the final screen installed
from the bedrock surface (approximately 220 feet bgs) and up 20 feet.
A shallow sampling well (SSW-1) will be installed in the area of the perched aquifer
identified by KDHE during their September 1980 site investigation and will allow for
monitoring of the perched aquifer. This well will be installed to approximately 30 feet
bgs with the screen interval from 20 to 30 feet bgs. The proposed locations of the new
monitoring wells are shown on Figure 5. The locations were selected to monitor the
effectiveness of the remedial efforts.
The new and previously sampled monitoring and residential wells will be sampled
quarterly for the first year and semi-annually thereafter until remedial action objectives
are attained. Frequency of the monitoring will be reevaluated and modified based upon
the effectiveness of the alternative. Analytical parameters include:
- Total chromium
- Hexavalent chromium
- Dissolved oxygen
- pH
- Temperature
- Oxidation/Reduction potential (Eh)
- Total organic carbon
- Total dissolved solids
The shallow sampling well will also be analyzed for lead.
Institutional controls
Institutional controls as allowed by law will be implemented to ensure that exposure
pathways are not completed where the contaminant concentrations are above cleanup
goals. Access restrictions will consist of deed restrictions, permits, and public education.
Deed restrictions will be placed on properties within or near the contaminant plume to
prevent use of the contaminated groundwater as a potable water supply. This will be
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done in association with the local authorities. Installation of new wells will be monitored
to ensure that they are for nonpotable uses only and will be allowed by permit only, via
restrictions by local authorities. Public education will be performed to inform the public
of the potential hazards associated with the contaminated groundwater and discourage the
use of it for drinking or bathing. Public education will be conducted through
informational meetings and flyers.
In-Situ Bioremediation
Included in this alternative is in-situ bioremediation which will be implemented to
enhance remediation efforts provided successful implementation of the process is
demonstrated during the Remedial Design treatability studies. One criteria for
determining successful implementation would be an evaluation as to whether the
groundwater remaining in the remediated aquifer zone would be acceptable for possible
beneficial reuse after bioremediation was completed. In-situ bioremediation will be used
to complement the extraction of contaminated groundwater. In-situ bioremediation will
be implemented provided that treatability studies during remedial design show the
reduction process to be successful. In-situ bioremediation will'help improve the
consistency of the remedy over that of standard pump-and-treat remedial actions. The
volume of extracted groundwater will be reduced because the estimated number of
pore-space flushings needed to remove the chromium is reduced.
In-situ bioremediation will consist of two primary components: the process system
and the distribution system. The process system will include a carbon source storage
tank, mixing tank, potable water supply, and circulation pump. The carbon source will be
diluted with water to the desired concentration in the mixing tank and the mixture will be
recirculated until injection. The process system will be housed in the treatment building.
The five multiport monitoring wells will be used as the injection wells unless the
treatability study indicates that separate wells in a well nest will be needed. Discharge
lines will be connected from the treatment building to the injection wells. A separate line
will be used for three separate depths of injection into the screens of the multi-port well.
A programmable logic controller (PLC) will be used to monitor and control the
system. The PLC will control the feed rate and frequency of the carbon-source feed and
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solution feed pumps, as well as timing of the solenoid valve network that will control the
metered flow to the injection wells.
During remedial design, a field scale groundwater treatability study will be
performed to confirm microbial reduction of Cr(VI) by the carbon source, determine the
optimum concentration of the carbon source, and evaluate potential biofouling affects.
The injection rate of the carbon source will initially be estimated through groundwater
modeling efforts and will ultimately be determined during the field scale treatability
study.
The EPA will periodically revisit the remedy in order to evaluate its ongoing
effectiveness and to allow an examination of any new technologies that may arise and
which may be appropriate in substitution of the original remedy that has been selected.
Five-year reviews are required for this remedy. There is some uncertainty regarding the
impact of contaminated subsurface soils in the former lagoon area on the chromium
concentrations in the groundwater. The EPA will conduct additional groundwater
monitoring and soil analysis near the impoundment area during remedial design and
remedial action to address this question. The question of the impact of the contaminated
soils will be addressed before or during the initial 5-year review.
If a change in remedy is needed at a later date, EPA would follow the procedures
required by the NCP to amend the ROD, if a fundamentally different remedy or
alternative is selected. The EPA would publish an "explanation of significant
differences" for any significant changes to the remedy that do not amount to a
fundamental change to the remedy.
The EPA believes at the present time that the Preferred Alternative will provide the
best balance of trade-offs among alternatives with respect to the evaluation criteria. The
EPA believes that the preferred alternative will be protective of human health and the
environment, will comply with ARARs, will be cost effective, and will utilize permanent
solutions and alternative treatment technologies or resource recovery technologies to the
maximum extent practicable. The remedy meets the statutory preference for the use of
treatment as a principal element.
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The proposed locations, pumping rates, depth, and size for the extraction wells will
be selected during early phases of the remedial design efforts. The initial phase of the
remedial design will include the installation and sampling of the proposed and existing
monitoring wells (multiport or nested) to confirm plume extent and groundwater flow
direction. To confirm pumping rate estimates, a 72-hour pump test will be performed
following installation of extraction well EX-1 and associated observation wells.
Contaminated groundwater extracted during the pump test will be discharged to the
POTW or treated and discharged to the unnamed tributary to Prairie Dog Creek.
Treatability studies will also be performed during the initial phases of remedial
design efforts. A treatability study will be performed to determine specific design criteria
for removal of hexavalent chromium from contaminated groundwater. A pilot scale
treatability study will be performed to determine specific design criteria for inducing
anaerobic conditions in the subsurface for in-situ bioremediation. The pilot scale
treatability study will determine required carbon concentration of the injection source,
biofouling effects, injection rate, and reductive zone of the injection wells.
Contaminated groundwater will be pumped to an on-site electrochemical reduction
treatment system. The groundwater treatment system will be a packaged system that will
be delivered to the site. The treatment system will be housed in a prefabricated structure
to reduce noise, improve appearance, insulate the treatment process, and protect
equipment. The prefabricated structure will be placed on a concrete foundation. A chain
link security fence will be constructed around the treatment facility to limit general
accessibility to the facility and the potential for public exposure. Piping, controls, valves,
and pumps will be housed within the building for year-round operation. Power lines will
be connected, and wiring will be installed to operate pumps, fans, lighting, and other
equipment. Signs will be posted to prevent unknowing entry into the building, and
security measures, such as alarms, will be implemented.
The treatment building will also house the process system for the injection system
for the in-situ bioremediation efforts. The process system includes the carbon source
storage tank, mixing tank, potable water supply, and circulation pump. Discharge lines
will be connected from the treatment buildings to the multiport monitoring wells or
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monitoring well nests which will serve as injection wells. A separate line will be used for
up to three separate injection depths.
10.1.2 Buildings/Soil
The EPA's preferred remedy for the buildings/soil is Buildings/Soil Alternative 4.
This alternative involves decontamination of both the plating shop and machine shop
buildings by removal of the concrete floor surfaces and dusting/vacuuming/wiping of all
other interior surfaces. The decontamination debris will be disposed of at an off-site
RCRA hazardous waste landfill or a RCRA solid waste landfill, depending on sampling
results. Buildings/Soil Alternative 4 will permanently remove contamination within the
buildings, thereby significantly reducing O&M efforts as compared to the other
alternatives.
After removing all obstructions, the contaminated areas of the concrete floors of both
buildings will be grit-blasted where testing shows it is necessary. The contaminated
surface will be spray-blasted with an abrasive material using a combined grit-
blasting/vacuum head. The grit used to blast will be reused, when possible, throughout
the decontamination process. Approximately 1,600 square feet of surface area will be
grit-blasted per day. Approximately 2 weeks will be needed to grit-blast the floors. Each
worker will wear self-contained breathing apparatus (Level B personal protection)
throughout the process. Decontamination debris will be collected in roll-off containers.
It is estimated that approximately 45 cubic yards of grit and floor dust will be
accumulated and have to be disposed of. The concrete debris will be analyzed to
determine if it should be classified as a RCRA hazardous waste. If the debris is classified
as a RCRA hazardous waste, it will be disposed of in an off-site RCRA hazardous waste
landfill. The landfill will be selected during the remedial action design after
determination that the landfill is in compliance with regulatory requirements. If the
debris is not classified as a RCRA hazardous waste, it will be disposed of in a RCRA
solid waste landfill as a special waste.
After grit-blasting is completed, the interior surfaces will be dusted/vacuumed/wiped.
Confirmation samples will then be collected from the concrete surfaces to determine
whether the action levels had been achieved. Surface samples will be used to assess the
effectiveness of the concrete decontamination. Surface samples will be collected by
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grinding off a portion of the concrete surface and analyzing it for the contaminants of
concern. If analytical results show that contamination above the established remedial
action levels is still present in the concrete, grit-blasting will be continued. If the
remedial action levels cannot be obtained, then the area where contamination of concern
remains will be encapsulated with a durable coating. However, it has been assumed that
all areas can be remediated to remedial action levels.
Deed restrictions, as permitted by law, limiting the use of the site will also be
implemented. The deed restrictions will be implemented to restrict the buildings to
industrial and commercial use. The soils around the foundation of the plating shop
building will remain in place. The deed restrictions, if properly followed and enforced,
will prevent exposure to the soil. Removal of the contaminated soil could not be
performed without jeopardizing the structural integrity of the buildings.
The deed restrictions necessary under this alternative will be less restrictive than the
other alternatives because a majority of the contaminants will be removed. It is
anticipated that a wider range of industries would be allowed to occupy the buildings
because of the contaminant removal. The Preferred Alternative will not allow for
unlimited use and unrestricted exposure; therefore, CERCLA Section 121(c) periodic
reviews conducted by the EPA will need to be conducted.
10.2 Summary of Estimated Costs
The estimated present worth cost for the remedy is $4,759,400 assuming a 5 percent
discount rate. The estimated present worth cost for the groundwater alternative is
$4,489,500 and for the buildings/soil alternative $269,900. The estimated capital cost for
the remedy is $2,780,700. The estimated present worth cost of annual O&M costs is
$1,978,700. Detailed breakouts of the costs are presented in Tables 1 and 2.
10.3 Cleanup Levels
Final cleanup levels were established for both groundwater and soils at the site. The
final cleanup levels are presented in Table 3. The cleanup level for groundwater will
restore the groundwater to drinking water quality, with respect to chromium
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contamination, and will restore the use of the building for industrial and commercial
purposes, with respect to specific contaminants.
10.4 Expected Outcomes of the Selected Remedy
The site aquifer is expected to be available as a drinking water resource and the on-
site buildings are expected to be available for industrial or commercial use as a result of
successful completion of the remedy. Contaminant fate and transport modeling has
predicted attainment of the groundwater cleanup levels in approximately 13 years using
the extraction scenario described for the alternative. A primary factor that may increase
remediation time includes poor contaminant recovery from the aquifer. This uncertainty,
however, could be minimized using data obtained during the treatability study which will
be conducted as part of the remedy design.
Remediation efforts for the on-site buildings and soils will allow the buildings and
site to be used for industrial or commercial purposes. The remediation efforts will
require approximately 2 weeks. Deed restrictions limiting use of the buildings and site to
industrial and commercial purposes will be in place for an indefinite period of time.
11.0 Statutory Determinations
Under CERCLA Section 121, EPA must select remedies that are protective of human
health and the environment, comply with applicable or relevant and appropriate
requirements (unless a statutory waiver is justified), are cost-effective, and utilize
permanent solutions and alternative treatment technologies or resource recovery
technologies to the maximum extent practicable. In addition, CERCLA includes a
preference for remedies that employ treatment that permanently and significantly reduces
the volume, toxicity, or mobility of hazardous wastes as a principal element. The
following sections discuss how the selected remedy meets these statutory requirements.
11.1 Protection of Human Health and the Environment
The selected remedial action will protect human health and the environment.
Hydraulic extraction of contaminated groundwater, and subsequent treatment and
Ace Services Site DS-44
Record of Decision
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disposal of the extracted groundwater and treatment residue will eliminate the
groundwater pathways through which contaminants pose risks. Removal of contaminated
surface concrete and contaminated dusts to established cleanup levels from on-site
buildings will allow industrial and commercial use of the buildings within accepted
health-based exposure standards. Restricting future use of the site to industrial and
commercial purposes by deed restriction will provide written notice of the remaining
contamination to protect against inadvertent use of the site for residential purposes.
11.2 Compliance with ARARs
Section 121(d)(2) of CERCLA, 42 U.S.C. §9621(d)(2), requires that cleanup actions
conducted under CERCLA achieve a degree or level of cleanup which, at a minimum,
attains "any standard, requirement, criteria or limitation under any federal environmental
law...or any promulgated standard, requirement, criteria, or limitation under a state
environmental or facility siting law that is more stringent than any federal
standard...[which] is legally applicable to the hazardous substance or pollutant or
contaminant concerned or is relevant and appropriate under the circumstances of the
release or threatened release of such hazardous substance or pollutant of contaminant...."
The identified standards, requirements, criteria, or limitations thus adopted from other
environmental laws , which govern on-site cleanup activities at this site, are referred to as
"applicable or relevant and appropriate requirements", or "ARARs."
For on-site cleanup activities, under Section 121(e)(l) of CERCLA, EPA is not
required to obtain any federal, state or local permits for actions conducted on site, but
must comply with the substantive (non-administrative) requirements of the identified
federal and state laws. For cleanup activities that will occur off site, both the substantive
as well as the administrative requirements of such laws will apply to cleanup activities.
This section identifies the ARARs which will apply to the on-site cleanup activities
for this site. (The many laws and regulations which apply to off-site cleanup or disposal
activities are not called "ARARs" and are not enumerated here.)
Ace Services Site Do-45 Record of Decision
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FEDERAL ARARs
Clean Air Act of 1963, as amended (42 U.S.C. §§7401-7671q)
40 Code of Federal Regulations (CFR) Part 50
Part 50 (containing national ambient air quality standards) is pertinent to excavation
and materials handling activities. These standards would be applicable for controlling
fugitive emissions.
Clean Water Act of 1977, as amended (33 U.S.C. §§1251-1376)
40 CFR Parts 122-125
The National Pollutant Discharge Elimination System (NPDES) was established to
control discharge of pollutants from any point source into waters of the United States. A
permit will not be required since the site is being remediated as part of the Superfund
program and the discharge point is on site; however, the substantive requirements of the
regulation must be met. This regulation applies to the discharge of treated groundwater
and process water to surface water.
Discharge limits for chromium will be established during remedial, design and will be
consistent with the requirements of the NPDES program. If established surface water
discharge limits are not met, provisions for alternate effluent limits can be found in this
part.
Under the Clean Water Act, states must establish ambient water quality criteria for
the protection of surface water based on use classifications and the criteria stated under
Section 304(a) of the Clean Water Act. These criteria are applicable (see the discussion
under "State ARARs," below) and will be used to establish discharge limits for treated
groundwater and process water.
Safe Drinking Water Act of 1986, as amended (40 U.S. C.§§300)
40 CFR Part 141
Ace Services Site DS-46
Record of Decision
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Primary Drinking Water Standards are established by this part. The Safe Drinking
Water Act's Maximum Contaminant Levels (MCLs) ate health-based standards for
chemicals that may be found in public water supplies. The MCL for chromium would be
applicable or relevant and appropriate if the treated water is beneficially reused for human
consumption.
The discharge of treated groundwater or process water will otherwise not impact
drinking water in a public water supply directly. However, the potential for residual
contaminants percolating to groundwater exists. The NCP requires consideration of
MCLs, where they exist, as relevant and appropriate to groundwater cleanup standards
when the aquifer is a current or potential source of drinking water. The MCL for
chromium is relevant and appropriate for establishing cleanup standards to be met during
implementation of the remedy because the aquifer beneath the site is a drinking water
source.
40 CFR Part 144-148
The substantive requirements of the underground injection regulations apply to any
injected water or material, including any injection for bioremediation purposes.
Resource Conservation and Recovery Act (RCRA) of 1976, as amended (42 U.S.C.
§§6901-6987)
40 CFR Part 261
The criteria set forth in this part will be used to determine if solid wastes excavated,
created through treatment, or otherwise generated during the implementation of the
remedy are hazardous or non-hazardous.
40 CFR Part 262.11
The methods for determining whether a solid waste is hazardous are set forth in this
part. All generators of solid wastes are required to determine if a waste is hazardous.
Wastes determined to be hazardous will be managed in accordance with the rules
applicable to hazardous wastes.
Ace Services Site Db-47 Record of Decision
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40 CFR Part 262.34
The accumulation of hazardous waste on site is addressed by this part. In the event
any of the solid wastes excavated, created through treatment, or otherwise generated
during the implementation of the remedy are hazardous, these regulations will apply.
The RCRA regulations that apply to facilities for the treatment, storage or disposal of
hazardous waste were determined not to be applicable or relevant and appropriate at this
site.
STATEARARs
Kansas Public Quality Standards (KAR 28-15-13). This regulation establishes state
MCLs.
Kansas Surface Water Quality Standards (KAR 28-16-28). This regulation provides
surface water quality standards to protect water resources of the state.
Hazardous Waste Management Regulations (KAR 28-31). This regulation specifies
requirements for managing hazardous waste within the state of Kansas.
Solid Waste Management (KAR 28-29 Part II). This regulation specifies requirements
for managing solid waste within the state of Kansas.
Injection Well Regulations (KAR 28-46, Parts 1-44). This regulation specifies
requirements for injection wells within the state of Kansas.
Kansas Ambient Air Quality Standards and Air Pollution Control Regulations (KAR
28-19). This regulation specifies requirements for managing discharges to the air within
the state of Kansas.
TO BE CONSIDERED
To be considered (TBC) are non-promulgated advisories or guidance documents
issued by federal or state governments. The TBC were used at the Ace Services site as
Ace Services Site DS-48 Record of Decision
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part of the risk assessment to set protective cleanup levels for soil and for indoor air and
dust The TBC used at the site are listed below.
Permissible Exposure Level: Occupational Safety and Health Act (OSHA) (29CFR
1910.1000).
EPA Removal Cleanup Levels: EPA Action Memorandum, Ace Services Site, March
29,1994.
EPA Region HI Risk-Based Concentration: EPA Integrated Risk Information System
(IRIS) Reference Dose and Slope Factors.
EPA OSWER Directive 9355.4-02,1989, Interim Guidance on Establishing Soil Lead
Cleanup Levels at Superfund Sites.
11.3 Cost Effectiveness
The selected remedial action is cost-effective, providing overall effectiveness
proportional to its costs. The selected remedy will be effective in the long-term,
providing a significant and permanent reduction of the toxicity, mobility, and volume of
contaminated groundwater and interior building contaminants.
11.4 Utilization of Permanent Solutions and Innovative Treatment Technologies
to the Maximum Extent Practicable
The EPA has determined and the state of Kansas has concurred with EPA's
determination that the selected remedy represents the maximum extent to which
permanent solutions and treatment technologies can be utilized in a practicable manner
for the Ace Services Site. Of those alternatives that are protective of human health and
the environment and comply with ARARs, EPA and the state have determined that this
selected remedy provides the best balance of trade-offs in terms of the five balancing
criteria, while also considering the statutory preference for treatment as a principal
element and considering state and community acceptance. The selected remedy treats the
Ace Services Site
DS-49 Record of Decision
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principal threat posed by the buildings and the major threat posed by the groundwater,
achieving significant chromium and lead reductions.
Although EPA emphasizes treatment to reduce the "toxicity, mobility or volume"
and "long term effectiveness" criteria (as provided in the NCP), the most significant
difference among groundwater actions was with regard to the long-term effectiveness and
implementability. The most significant difference among the buildings/soil actions was
with regard to the long-term effectiveness and the reduction of contaminants. The
preferred alternatives reduce the risk within a more reasonable time frame and at a lesser
cost than any of the other alternatives. In addition, the selected remedy does not present
any substantive or uncontrollable short-term risks to the community or on-site workers.
11.5 Preference for Treatment which Reduces Toxicity, Mobility, or Volume
By hydraulically containing and extracting groundwater and removing contaminated
materials from the buildings containing COCs greater than the final cleanup goals, the
selected remedial action addresses one of the principal threats posed by the site. The
selected remedy also satisfies the statutory preference for remedial actions that employ
treatment to significantly reduce toxicity, mobility, or volume of contaminants.
12.0 Documentation of Significant Changes
The selected remedy has not been significantly changed from the preferred
alternative presented in the Proposed Plan.
Ace Services Site DS-50 Record of Decision
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III. RESPONSIVENESS SUMMARY
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ACE SERVICES SITE, COLBY, KANSAS
RESPONSIVENESS SUMMARY
TO
COMMENTS FROM PUBLIC MEETING AND WRITTEN COMMENTS
Comment 1: The Colby City Manager expressed concern about the loss of the public water
supply well shut down in 1980. She projected that the city water supply would
be limited in the near future because the water rights have been effectively
reduced by the shutdown of the well. She asked for (1) help on obtaining
additional water rights or (2) consideration of reuse of the treated water from the
U.S. Environmental Protection Agency's (EPA) remedial action for city drinking
water purposes versus disposal of the treated water. Several other commenters
also expressed a desire for EPA to incorporate reuse of the treated groundwater
for city drinking water supply and to consider the value of the water in our
determination. Consideration of blending of treated and other water supplies was
recommended by one person.
Response 1: The EPA's preferred remedy called for the discharge of treated water to a tributary
of Prairie Dog Creek or to the Colby Publicly Owned Treatment Works (POTW)
with the water being monitored to ensure compliance with the substantive
requirements of the Clean Water Act and the parallel State regulations. The EPA is
willing to make the water available for beneficial reuse, provided it is understood
that any such arrangements would necessarily be the responsibility of the
appropriate state and local authorities, and that EPA is not in a position to treat the
water to remove other possible contaminants (e.g., nitrates, or other common
groundwater contaminants not within the scope of this cleanup), or to guarantee that
the water is safe for any particular use. For example, despite removal of the
contaminant of concern (chromium) to concentrations below drinking water
standards, the water may not be potable if other common contaminants are present.
The Record of Decision (ROD) provides that if local, regional or state authorities
can come up with a beneficial reuse plan hi a timely way (i.e.) by the due date for
the preliminary design), the remedial design for the remedy could take account of
such a plan. In any event, the piping for the remedy will include a hookup point to
accommodate beneficial reuse, to avoid the need to retrofit such a link. The ability
to blend treated water with city drinking water would be dependent on the city's
water distribution system capabilities and would be handled by the local authorities.
The effluent water from the on-site treatment plant is expected to have elevated
concentrations of total dissolved solids (TDS) and iron (Fe) as residuals from the
treatment process. If the elevated TDS and Fe are undesirable, an ion exchange
treatment option (evaluated in the feasibility study (FS) report) will provide effluent
that would be more suitable for reuse as drinking water. However, at influent
concentrations above 1 milligram per liter (mg/L) total chromium, the treatment
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cost for ion exchange is considerably higher than the proposed electrochemical
precipitation method. The most appropriate treatment option will be resolved
during the design phase.
The EPA has contacted the Kansas Department of Health and Environment (KDHE)
about the issue of Colby's water rights, and EPA will continue to pursue this issue
during the design. According to the Kansas Department of Agriculture (KDA),
there will need to be an application for a term permit for water rights before
remediation commences. At this point, KDA believes the water rights for Colby
have not been reduced because Public Water Supply Well 8 was shut down. Every
reasonable effort will be made by EPA to accommodate the city's use of the treated
water effluent from the site if such use is pursued by the local authorities.
Comment 2: One commenter asked if the proposed pumping wells would be pumped
continuously, 24 hours per day.
Response 2: The answer is yes, the wells will be continuously pumped, except for periods of
maintenance, until the cleanup is completed.
Comment 3: The same commenter asked if the withdrawal of groundwater in the remedial
action would affect the city's water rights.
Response 3: The EPA expects that a permit for remediation withdrawal rights will be granted.
Remediation water rights should not impact the city's water rights.
Comment 4: The Colby City Mayor asked whether use of the buildings has to be postponed
until the completion of the groundwater cleanup.
Response 4: As soon as the buildings have been cleaned and declared suitable for use, they
may be used. Use of the buildings does not have to await the end of the
groundwater treatment period. Anticipated uses for the buildings are for
commercial and industrial purposes.
Comment 5: Another commenter asked about the boundaries of the site, as defined in the
proposed plan. He specifically mentioned the gas station area, and reported his
belief that the gas station tanks remain buried at the site.
Response 5: The site is defined by EPA to include the two buildings, surrounding soils, and the
contaminated groundwater plume area where the amount of chromium in the
groundwater is greater than 100 micrograms per liter (ug/1) chromium. It does not
include the gas station area. The KDHE representative at the meeting agreed to
report the information to the State Underground Tank Program concerning the
alleged underground storage tanks. The KDHE's Storage Tank Section, Bureau
of Remediation, will conduct an investigation of the site when access to the
property is granted.
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Comment 6: One person asked if there was a further need to clean up under the buildings.
Response 6: The EPA and KDHE plan some further investigation of the subsurface soils
beneath both the buildings and the old lagoon area. This investigation will begin
during remedial design work, and will continue after the groundwater extraction
program has begun, so that EPA may judge the effectiveness of the extraction,
and then determine if the soils have a continuing source impact on the
groundwater quality. A decision will be made before or during the 5-year review,
which occurs five years after the implementation of the remedy at the site. The
ROD also provides that deed restrictions will be implemented to prevent
excavation of the contaminated soil remaining beneath the buildings and to
prevent removal of the concrete floors of the buildings.
Comment 7: A commenter who leases the machine shop asked about the plans for this
building, and wondered about the impact on his lease and business activities.
Response 7: This building should be currently suitable for the limited industrial/commercial
uses described by this commenter. The EPA plans to sample the buildings first, to
better delineate the areas in each that may need cleaning. If the samples in the
machine shop show no need for cleaning, no disruption of the current use as a
storage building will be necessary. If the samples demonstrate the need for
cleaning, it should be possible to schedule this work so as not to disrupt the
lessee's business operations.
Comment 8: A commenter asked about the legal owner of the property, and how a clear deed
would be given. She also asked about any lien on the property, any release of that
lien, and if there was a time frame on the lien. Another commenter followed up
with questions about procedures if there are more than one lien on a site, what is
the hierarchy?
Response 8: Under CERCLA the EPA is allowed to recover its costs from responsible parties.
Responsible parties may include both persons and corporations responsible for the
release of contamination and the owner or owners of the property where the
contamination was released. The EPA is allowed to file a CERCLA lien against a
property under appropriate circumstances as a means of encumbering property
with respect to which the EPA has incurred response costs. The EPA to date has
not filed a lien against the Ace Services property. The EPA will seek to recover
the costs it has incurred at the Ace Services Site from a responsible party or
parties if possible. The EPA generally does not comment on the status of specific
ongoing enforcement actions; accordingly, with respect to EPA's specific
enforcement actions to be taken in connection with the Ace Services Site, EPA
has no further comment.
Comment 9: A commenter stated that the state of Kansas Maximum Contaminant Level (MCL)
for protection of drinking water is 50 ug/1 for chromium instead of the 100 ug/1
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ug/1 level utilised in the proposed plan. The KDHE sent EPA a similar comment
on December 24,1998. Subsequently, in a letter dated January 13, 1999, KDHE
informed EPA that the 100 ug/1 standard was correct, reversing the incorrect
information in the December 24, 1998 letter.
Response 9: The EPA will continue to use the 100 ug/1 standard as a cleanup level for
groundwater.
Comment 10: One commenter encouraged EPA to use Public Water Supply Well 8 if it could
effectively aid in the extraction program.
Response 10: The EPA intends to utilize this well if during the remedy design, it is determined
that the well can be effectively used in the groundwater remediation process.
Comment 11: A commenter asked if additional problems had been caused at the site by the
requirement to install lagoons and other treatment measures in the 1970s and
1980s.
Response 11: The EPA believes there would have been worse problems at the site had these
measures not been installed. In the days before the lagoon and treatment system,
wastes were discharged directly to the ground or into the tributary to Prairie Dog
Creek. At least some of the contaminants were removed in the treatment system,
and the lagoon probably retarded the migration of contaminants into the
groundwater and/or prevented the contamination from being more widespread in
nature.
Comment 12: The KDHE commented that the acceptable level of contamination that could be
discharged to the receiving stream would be lower than referenced in the proposed
plan, and that this fact will result in higher treatment costs should this discharge
option be chosen.
Response 12: The EPA acknowledges the Kansas limits. The remedy design will meet the
Kansas discharge limits if the final design calls for discharge to the receiving
stream. More detailed cost estimates will be developed during remedial design.
Comment 13: The KDHE recommended that the in-situ bioremediation system not be installed
unless assurances can be provided that (1) the reduced conditions would not
persist past the remediation phase, (2) all reduced groundwater would be captured
by the extraction system, and (3) approval is received for the injection of the
carbon (carbohydrate) source. Regarding the public comments favoring reuse of
the treated groundwater, KDHE also questioned the in-situ bioremediation
system's impact on drinking water quality.
Response 13: Application of in-situ bioremediation at the site will depend on results of
treatability studies which will be performed as part of the initial remedial design.
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Unless the treatability studies indicate the technique will be appropriate, helpful and
worth the added expense, it will not be implemented. In addition, if EPA
determines during remedial design that reuse of the treated groundwater will occur,
we will strongly consider deletion of the bioremediation technology unless it is
demonstrated that reuse of the water will not be limited.
If bioremediation is implemented, the following comments apply:
1) The current concept for the in-situ bioremediation system includes containment
of the reduced groundwater within the capture zone of the extraction wells.
However, once the cleanup level for chromium is achieved, the groundwater pumps
will be turned off, thus leaving the remediated portion of the aquifer in a chemically
reduced condition. It will require an unknown period of time for the aquifer to
return to its original state of unreduced conditions.
2) The artificial, chemically reduced condition of the aquifer will most likely
remain for a period of tune once injection of the carbohydrate source is terminated.
The process for the aquifer to restore itself is complex and depends on dispersional
flow properties and geochemical properties of the aquifer. The amount of time it
will take for the aquifer to return to equilibrium has currently not been evaluated
and could not be made with much certainty.
3) Injection of the carbohydrate source will be performed in accordance to Kansas
regulations KAR 28-16 (Underground Injection Control Regulations), Federal
regulations 40 CFR Parts 144-147 concerning underground injection wells, and
EPA's Water Division and KDHE/Bureau of Water.
In summary, if in-situ bioremediation is implemented at the site the remediated
portion of the aquifer will be in a chemically reduced condition. It will require a
period of time for the aquifer to return to its original state of equilibrium. The
reduced water will be lacking in oxygen and may have unpleasant odors and
discoloration. Hydrogen sulfide and methane may be released from the reduced
portion of the aquifer. However, the quality of the chemically reduced
groundwater extracted and treated as part of the remedial action should improve
during the treatment process.
Comment 14: The KDHE requested a more detailed explanation of the Operation and
Maintenance Costs, as well as a clarification of the funding of these costs, the
time periods of that funding, and a description of any other circumstances
regarding the funding source of the project..
Response 14: Operation and Maintenance (O&M) costs for the preferred remedy were prepared in
accordance with EPA guidance criteria (EPA/540/G-89/004). The estimate was
prepared based on the current understanding of site conditions using engineering
experience and judgement. During ROD preparation, electrical costs for the O&M
of each groundwater remedy were revised to include plant treatment costs. All total
present worth costs in this ROD reflect electrical cost revisions. The present worth
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for the capital and O&M costs was provided in detail in Table B-6 (groundwater
alternative component) and Table C-4 (building/soil alternative component) of the
Final Feasibility Study Report (November 1998) and will also be provided in the
Record of Decision for the site. A more detailed cost estimate will be prepared
during remedial design.
Under the Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA), EPA funds the cost of O&M on groundwater remedies for up to
10 years after the remedy becomes operational and functional. Any O&M costs
after the 10-year period would be the responsibility of the state.
Comment 15: The KDHE recommended that if the city of Colby agrees to reuse the treated
• groundwater, EPA should consider entering into an arrangement to train city
personnel to operate the treatment system and to operate the system for the
remainder of the project.
Response 15: The EPA would consider this approach and other options to involve city
personnel in future work at the site.
Comment 16: The KDHE recommended that continued monitoring of the downgradient
residential wells be included in the remedial action.
Response 16: The EPA will include such monitoring in the project.
Comment 17: The KDHE requested additional groundwater monitoring downgradient of the site
to determine the horizontal and vertical limits of chromium contamination.
Response 17: The selected remedy includes the additional groundwater monitoring requested by
KDHE. Five additional multiport wells and one shallow well will be installed and
monitored at the site. These wells will be near MW-2, PWS-8, north of PWS-8,
south of PWS-8, between RW-1 and PWS-8, and just downgradient of the site.
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Table 1
Preferred Groundwater Alternative Present Worth Cost Estimate
Active Restoration/Reduc/Precip/Coag-Flocc/In-situBioremediation
Ace Services Site
CAPITAL COSTS
1 Extraction Wells (2 sets ot 3, 6" PVC wells 1020 1 VLF
intalled to depths of 1 20 ft. 1 70 ft, and 220 ft) j
1 3 HP Submersible Pump (wire, 2" galvanized 2 EA
Tdrop pipe, flow, and control devices)
,5 I IP Submersible Pump (wire, 2" galvanized 4 EA
^drop pipe, flow, and control devices) j
•7-1/2 HP Submersible Pump (wire, 2"
.galvanized drop pipe, flow, and control devices)
;Groundwater Collection Double Containment
(Piping (4" inside 6" HOPE installed, includes
' bedding and trenching)
I 1 EA
1950 LF
Chain-Link Fencing (6 ft high w/ 3 strand 1 20 LF
i barbed wire)
Swing Gate (6 ft high, 1 2 ft opening w/ 3 strand 1 EA
barbed wire)
'(Concrete Well Vaults (Extraction wells only) 2 EA
, Pre-engineered Building 1 EA
Purchased Packaged 210 gpm Electrochemical
Reduction System delivered to site (includes
influent holding tank, electrochemical cell and
acid wash system, and degas tank/effluent
jholding tank)
Other Direct Costs for Packaged Svstem
(Discharge Piping to Creek (3" PVC installed,
includes bedding and trenching)
i Multiport Sampling Wells, 5 - 4" PVC wells
installed to depth 220 ft (screen intervals
! 120-130 ft, 170-180 ft, and 210-220 ft)
' Observation Wells, 6 sets ot 2" PVC wells
installed to depths of 120 ft, 170 ft, and 220 ft)
1 LS
1 LS
750 LF
1100 VLF
i
3060 ! VLF
, Shallow Sampling Well , 1 - 4" PVC well 30 ! VLF
j installed to depth of 30 ft ; i
jln-situ Bioremediation System: System includes
source storage tank, mixing tank, solenoid
valves, pumps, PLC, and distribution lines to 5
wells
Other Direct Costs for In-situ Bioremediation
Packaged Svstem
Treatability Studies (treatment and in-situ bio)
1 LS
i
2 LS
2 LS
DIRECT CAPITAL COST SUBTOTAL
i Unit Cost i Capita Cost Annual Cost |
* ;: ^
$45
$4,000
$5,500
$6,000
$45,900
$8,000 1 ;
$22,000 :
$6,000
$33.43 $65,200
' $13.53 ; $1,600'
;
: $400! $400
.. $1,100
$2,200 .
$18,000 $18,000.
$300,000
$738,000
$8
$30
$300,000 :
$738,000 i
$6,000
$33,000
$22 $67,300 ;
$30 ! , $900 i
i !
$106,400
$50,000
$30,000
Bid Contingency (1 5%)
Scope Contingency ( 1 5%)
TOTAL DIRECT CAPITAL COST
Permitting and Legal (5%)
Construction Services (10%)
CONSTRUCTION COSTS TOTAL
Engineering Design (8%)
TOTAL CAPITAL COST
$106,4001 .
$100,0001
$60,000 1
$1,580,900
$237,1001
$237,1001 1
$2,055,100! I
$102,800
$205,500
$2,363,400
$189,1001
$2,552,500 i
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Table 1 (Continued)
Preferred Groundwater Alternative Present Worth Cost Estimate
Active Restoration/Reduc/Precip/Coag-Flocc/In-situBioremediation
Ace Services Site
[Cost Estimate Component Quantity i Units Unit Cost Capital Cost i Annual Cost
ANNUAL O&M COSTS |
, Electrical Costs: Pumps (826 KWh/dav) ; 301,500
• Electrical Costs: Plant (3000 KWh/dav) ,1 ,095,000
KWh i $0.08!
$24,100
KWh . $0.08 $87,600
ijGroundwater Monitoring (Analysis, equipment, shipping)
Year 1
Monthly sampling of 5 monitoring wells
( 1 5 samples) lor total and hexavalent
chromium (standard turnaround)
180
i
Years 2 through 6 \ 60
Quarterly sampling of 5 monitoring wells ;
, (15 samples) for total and hexavalent
1 chromium (standard turnaround)
: Years 7 through 13
Semi-annual sampling of 5 monitoring
wells ( 1 5 samples) for total and hexavalent
; chromium (standard turnaround)
EA
$200
EA $200 !
{
40 EA
$200
$36,000
'
$12,000
$8,000
Groundwater Monitoring (Labor onlv)
Yearl
2 Level PI persons for 2-8 hour days per
sampling event
'. Drilling subcontractor (pump installation)
.. Years 2 through 6
ji 2 Level P 1 persons for 2-8 hour days per
• sampling event
384
12
128
•1 Drilling subcontractor (pump installation) 4
Years? through 13
2 Level PI persons for 2-8 hour days per
' sampling^event
Drilling subcontractor (pump installation)
64
2
; RCRA Sludge Disposal (Assume 1 .3 times by 1020
'weight dewatered sludge)
i Electrode Replacement 2800
'' Treatment Plant Effluent Monitoring (Monthly
.monitoring for total and hexavalent chromium,
' standard turnaround)
Preparation of Health and Safety Plan (Year 1
only)
Preparation of O&M Manual (Year 1 only)
preparation of QA/Sampling Plan (Year 1 only)
12
40
80
60
(Five- Year Review fa). 5, 10, and 1 3 yrs ; 1
Maintenance Allowance ( 1 2% of purchased 1
equipment delivered)
Operator Requirement (2 hour/day)
730
HR
EA
HR
EA
HR
EA
LBS
LBS
EA
HR
HR
HR
LS
LS
$60 j
i
$3,000
$60
$3,000
$60
$3,000
$0.45
$0.50
$200
$60
$60
$60
$15,000
$36,000
HR $25
'
TOTAL PRESENT WORTH O&M COST , $1,937,000
•TOTAL PRESENT WORTH $4,489 500
$23,000
$36,000
$7,700
$12,000
$3,800
$6,000 1
$500
$1,400
$2,400
$2,400
$4,800
$3,600
$15,000
$36,000
$18.300)
5 percent discount rate used to calculate present worth.
-------
Table 1 (Continued)
Preferred Groundwater Alternative Present Worth Cost Estimate
Active Restoration/Reduc/Precip/Coag-Flocc/In-situBioremediation
Ace Services Site
Year
1
Yearly O&M
Cost*
Intermittent
! O&M Costs
$170,3001 $105,800
j 2 . $170,3001 $31,700
1 3
4
' 5
; 6
7
8
9
10
11
12
13
(Total Annual
O&M Costs
$276,100
$202,000
$170,300 $31,700 $202,000
$170,300
$170,300
$170,300
$170,300
$170,300
$170,300
$170,300
$170,300
$170,300
$170,300
$31,700
$46,700
$31,700
$17,800
$17,800
$202,000
$217,000
$202,000
$188,100
$188,100
$17,800) $188,100
$32,800
$17,800
$17,800
$32,800
$203,100
$188,100
$188,100
$203,100
Present Worth of Annual O&M : $1,936,971
l
Intermittent O&M Costs Include
Year 1 (plans, monitoring)
Years 2-6
Years 2-6
Years 2-6
Years 2-6 and 5 yr review
Years 2-6
Years 7- 13
Years 7- 13
Years 7- 13
Years 7-13 and 5 yr review
Years 7- 13
Years 7- 13 ;
Years 7-1 3 and 5 yr review
* Yearly O&M costs include: electricity, treatment plant effluent monitoring,
maintenance, and operator.
-------
Table 2
Preferred Building/Soil Alternative Present Worth Cost Estimate
Grit-Blasting
Ace Services Site
Cost Estimate Component
Quantity
Units
i Unit Cost Capital Cost Annual Cost
CAPITAL COSTS
Legal Personnel to j 60
Implement Deed Restrictions 1
Mobilization/Demobilization i 1
Predecontaminatin/Confirma
iition Sampling and Analysis
J/Wipfi)
••Prepare Quality Assurance
JProiect Plan
[Grit Blasting
Cleaning w/ HEPA vacuum
and wet wipe
^Load Debris into Roll-Off
Containers
Transport Debris to Offsite
•Facility
i Disposal Cost
f Personnel Decontamination
Chamber
; Labor During
Decontamination
Other Direct Costs for PPE
DIRECT CAPITAL COST
'SUBTOTAL
Bid Contingency (15%)
24
[
, 40
17695
72230
45
250
48
400
40
1
HR
. LS
i EA
HR
SF
SF
CY
MI
Ton
SF
HR
LS
$140 1 $8,400
; $500
, $105.00
$60.00
$4.38
$0.54
$3.48
$3
$500
$2,500
$2,400
$77,500
$39,000
$200
$900
$103 $4,900
$5.30 $2,100
$22
$2,024
: Scope Contingency
TOTAL DIRECT CAPITAL
COST
Permitting and Legal
(5%)
Construction Services
no%\
CONSTRUCTION COSTS
TOTAL
Engineering Design
(8%)
TOTAL CAPITAL COST
ANNUAL O&M COSTS
Five- Year Review @ 5, 10,
15.20r25r30vrs
1
LS
$900
$2,000
$141,300
$21,200
$21,200
$183,700
$9,200
$18,400
$211,300
$16,900
$228,200
-
$15,000
TOTAL PRESENT WORTH O&M COST
TOTAL PRESENT WORTH
$41,700
$269,900
$15,000
5 percent discount rate used to calculate present worth.
-------
Table 2 (Continued)
Preferred Building/Soil Alternative Present Worth Cost Estimate
Grit-Blasting
Ace Services Site
! Year
Yearly O&M
i Cost*
i 1 $0
I 2
$0
Intermittent
O&M Costs
$.0
SO
Total Annual)
O&M Costs i Intermittent O&M Costs Include:
$01
$oi
3
i 4
5
i $0
$0
$0
; 6 ; $o
' 7 i $0
8 $0
9 $0
! 10
i .
11
$0
$0
; 12 $o
13 $0
14 $0
15 $0
16
17
18
19
; 20
21
$0
$0
$0
$0
$0
$0
22 i $0
23 $0
24
25
26
L27
28
29
30
$0
$0
$0
$0
$0
$0
$0
$0
$0
$15,000
$0
$0
$15,000
$01 $0
$0
$0
$01 $0
$0
$15,000
$0
$0
$0
$0
$15,000
$0
$0
$0
$0
$15,000
$0
$0
$0
$0
$15,000
$0
$0
$0
$0
$15,000
Present Worth of Annual O&M
$0
$15,000
$0
$0
$0
$0
$15,000
$0
$0
so
$0
$15,000
$0
$0
$0
$0
$15,000
$0
$0
$0
$0
$15,000
$41,730
5 yr review
5 yr review
5 yr review
5 yr review
5 yr review
5 yr review
* Yearly O&M costs include monthly cleaning of the builiding.
-------
Table 3
Final Cleanup Levels:
Groundwater, Interior Air, Interior Dust/Concrete, and Exterior Soil
Ace Services Site
Media
Groundwater
Interior Air
•
Interior Dust/
Concrete
Exterior Soils
Contaminant
Chromium (VI)
Arsenic
Cadmium
Total
Chromium
Chromium (VI)
Lead
Manganese
Nickel
Total
Chromium
Chromium (VI)
Lead
Total
Chromium
Lead
Maximum
Onsite
Detection
2.998
0.243
0.720
80.8
10.8
15.1
6.38
2.68
9,290
213
2,580
690
418
Units
Mg/L
Mg/cum
jug/cum
Mg/cum
ug/cum
^g/cum
Mg/cum
Mg/cum
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
Final
Cleanup
Level
100
10
5
100
1004
30
5,000
1,000
10,000s
10,000
1,000
1500
500
Reference
MCL1
PEL2
PEL1
EPA3
t>
PEL2
EPA3
PEL2
PEL2
RBC*
RBC6
EPA7
EPA3
EPA3
Notes:
1) The MCL for total Cr was used because there is no MCI for Cr( VI).
2) PEL - Permissible Exposure Level, OSHA (USHSS 1994).
3) EPA = USEPA Removal Cleanup Levels (EPA 1994).
4) The OSHA PEL of 100 ufjai mis expressed as GO, which is equivalent to 50 ng/cu m expressed as Cr.
5) The RBC for CrfVT) was used because there is no RBC for total Cr.
6) RBC -USEPA Region HI Risk-Based Concentration (EPA 1997).
7) EPA = USEPA OSWER Directive 9353.4-02, 1989.
Ace Services Site
Record of Decuion
-------
SCALE:
SOURCE:
0 1000 2000
I I 1
FEET
USCS 7.5' SERIES. COLBY QUAE
"j^
TE LOCATION
KANSAS J
QUADRANGLE LOCATION
JRANQLE. THOMAS COUNTY. KANSAS,
1967
\\\
•l|
-j*?
liii
SOURCE: KDHE 1991
FIGURE 1
SITE LOCATION
ACE SERVICES SITE
-------
-------
I:
PHS HELL NO. 8 -
2SSOJ I2B10JI
LI TV Of COLB'T, KANSflS
HELL LOCATION
MITH IDENTIFICATION AND 10IAL
HEXHVN.CNT CHROMIUH
CONCCHTAMION lu»/tl
HEWVNXHt CHROMIUK
ISQCONaHtRATION CONTOUR lua/LI
IOMHED MCRE WPROX1MATEI
FICURE 3
HEXflVALENT CHROHIUH
ISOCONCENTRATION CONTOUR MRP
ACE SERVICES SITE
-------
ELEVATION (ft. ••!)
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W.TERNATIVES 214
CONTAINMENT
SITE PLAN
ACE SERVICES SME
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National Technical Information Service
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