PB96-963111
EPA/AMD/R07-96/085
November 1996
EPA Superfund
Record of Decision Amendment:
Mid-America Tanning Company,
Superfund Site, Woodbury County, IA
7/29/1996
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AMENDMENT TO THE
RECORD OF DECISION FOR THE
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MID-AMERICA TANNING COMPANY SUPERFUND SITE
WOODBURY COUNTY, IOWA
Prepared by:
U.S. Environmental Protection Agency
Region VH
Kansas City, Kansas
July 1996
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DECLARATION
RECORD OF DECISION AMENDMENT FOR THE
MID-AMERICA TANNING COMPANY SUPERFUND SITE
WOODBURY COUNTY, IOWA
JULY 1996
SITE NAME AND LOCATION
Mid-America Tanning Company Superfund Site
Woodbury County, Iowa
INTRODUCTION
The United States Environmental Protection Agency (EPA) is amending the Record of
Decision (ROD) for the Mid-America Tanning Company Superfund Site. On September 24,
1991, a ROD was issued for the Mid-America Tanning Company Site located in Woodbury
County, Iowa. The ROD presented the remedy selected by the EPA for this site, which called
for in-situ immobilization of the densely-contaminated sediments in the east and west aeration
lagoons and the northeast field in conjunction with the placement of soil-clay caps over the less
densely-contaminated source areas. Impoundment waters were to be treated as necessary and
either discharged to the nearby oxbow lake or transported off site to a Publicly Owned
Treatment Works (POTW). As a result of information which has been developed subsequent
to the issuance of the ROD, the EPA has determined that fundamental changes to the remedy
were necessary. The amendment to. the ROD describes and summarizes the basis for these
changes as well as documenting changes in the remedy at the site.
The EPA is the lead agency for the site, and the Iowa Department of Natural Resources
(IDNR) has been designated the support agency. The amendment to the ROD is being issued
by the EPA with concurrence by the state of Iowa.
The ROD amendment together with the original ROD presents the selected remedial
action for the site. This action was chosen in accordance with the Comprehensive
Environmental Response, Compensation and Liability Act of 1980 (CERCLA), as amended by
the Superfund Amendments and Reauthorization Act of 1986 (SARA), and the National
Contingency Plan (NCP). Section 117(c) of CERCLA provides that after the adoption of a
final remedial action plan, if any remedial action is taken, or if any enforcement action under
section 106 or 122 is entered into, and such action, settlement or decree differs in any
fundamental respect from such final plans, the lead agency shall publish an amendment to the
ROD with the reasons such changes were made. The ROD amendment will explain these
changes to the remedy. In accordance with the NCP, 40 C.F.R. 300.825 (a)(c)(21), this
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amendment and the information supporting these decisions are part of the administrative record
file and are available for public review and comment. The administrative record file is
available for review at the the Sergeant Bluff City Hall, Sergeant Bluff, Iowa and the EPA
Region Vn Office, Kansas City, Kansas.
DESCRIPTION OF THE AMENDED SELECTED REMEDY
The major components of the selected remedy, as amended, include:
• Contaminated soils in the northeast field will be consolidated and/or excavated
and consolidated with the Polishing Basin sediments and covered with a
soil/clay cap or geosynthetic cap such as high-density polyethylene (HDPE) that
achieves the same level of performance;
• Sediments in the polishing basin and east and west aeration lagoons will be
dewatered. The dewatered sediments will then be covered with a clay/soil
cover or comparable geosynthetic cap;
• On-site treatment and discharge of impoundment water to the nearby oxbow
lake;
• Excavation of the burial trench material followed by on-site stabilization and
consob'dation with the northeast field soils prior to capping;
• Excavation of the contaminated soil areas, other than the northeast field, and
consolidation of this material with the aeration lagoon sediments and/or
polishing basin sediments prior to capping;
• Removal of the sediments in the wet well, aeration basin, and final clarifier and
consolidation of this material with the sediments in the aeration lagoons prior to
capping. The emptied basins will be decontaminated with high-pressure steam
and backfilled with clean soil;
• The filter press building along with other miscellaneous contaminated debris
will be decontaminated by washing these items with a high-pressure steam
cleaner. Wash water will be treated on-site and discharged to the oxbow lake.
Floor scrapings and building residue will be disposed of in accordance with the
Resource Conservation and Recovery Act (RCRA); and
• Land use restrictions in the form of deed restrictions will be instituted to limit
future use of the property.
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STATUTORY DETERMINATIONS
The selected remedy as amended remains protective of human health and the
environment, complies with federal and state requirements that were identified in the ROD as
applicable or relevant and appropriate to this remedial action and is cost effective. In addition,
the remedy, as revised, utilizes permanent solutions and alternative treatment technologies to
the maximum extent practicable for this site. These changes to the remedy will increase
projecjtiveness of human health and environment, both short term and long term.
7-39 -
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Dennis Grams, P.E. \Date
Regional Administrator
Environmental Protection Agency
Region VH
Attachment:
Decision Summary
Responsiveness Summary-Attachment A
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Amended Record of Decision
Decision Summary
Contents
I. Introduction 1
n. Community Relations 2
m. Reasons for Issuing the ROD Amendment 2
IV. Description of the New Alternatives 3
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V. Evaluation of Alternatives 5
VI. Statutory Determinations 13
Responsiveness Summary Attachment A
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DECISION SUMMARY
RECORD OF DECISION AMENDMENT for the
MID-AMERICA TANNING COMPANY SUPERFUND SITE
WOODBURY COUNTY, IOWA
I. INTRODUCTION
The Mid-America Tanning (MAT) Company Superfund Site is located in Woodbury
County, Iowa, approximately seven miles south of Sioux City and four miles south of the town
of Sergeant Bluff. The MAT site occupies 98.7 acres of land in an industrial area known as
the Port Neal Industrial District. The site is bordered on the north by Kind & Knox, a gelatin
manufacturer, on the east by a Chicago and Northwestern railroad right-of-way, and on the
west and south by agricultural land and public-use hunting grounds. The nearest stretch of the
Missouri River is approximately 1.5 miles to the southwest.
The MAT Site operated as a hide tanning processor under several different ownerships
from 1970 until 1989. The tanning process included fleshing, brine curing and trimming of
hides as well as brine and chrome tanning. The tanning operations generated a wastewater
stream that contained dirt, brine, flesh, detergents, hair, sulfides, ammonia, lime, grease and
chromium. During a period of the operation, contaminated sludges were buried in trenches
and land farmed on the site. The Environmental Protection Agency (EPA) completed an
Remedial Investigation/Feasibility Study (RI/FS) in July 1991 and issued a Record of Decision
(ROD) in September 1991. The selected remedy in the ROD consisted of in-situ
immobilization of the densely-contaminated sediments in the east and west aeration lagoons
and the northeast field, placement of a soil-clay cap over the less densely-contaminated source
areas, and treatment and discharge of contaminated impoundment waters. The EPA completed
a Remedial Design (RD) in 1993, and in 1994 the Foxley Cattle Company was ordered to
conduct a removal action at the site. Foxley complied with the Order and completed the
removal action in May 1995. While conducting the RD and subsequent removal action, EPA
determined that the sediments found in the clay-lined impoundment areas were generating
hydrogen sulfide gas at concentrations posing significant health risks. Air sampling and
modeling indicated that unacceptable levels of hydrogen sulfide gas would be released during
the solidification process. In response to this concern, EPA is amending the remediation to
minimize disruption of the waste and the. release of hydrogen sulfide gas. The ROD
amendment recommends dewatering the impoundment areas using a system of wick drains and
then applying an improved cap to the area. In addition, the ROD amendment addresses the
need to remediate the sediments in the wet well area, aeration basin and final clarifier. These
sediments will be consolidated with the aeration lagoon sludges and/or polishing basin
sediments and capped. The ROD amendment also provides for decontamination of the filter
press building and other debris on site.
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H. COMMUNITY RELATIONS
The EPA is issuing this ROD Amendment to meet the public participation provisions
mandated under Section 117(a) of the Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA), as amended by the Superfund Amendments and
Reauthorization Act (SARA) of 1986, and Section 300.435 (c)(2)(U) of the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP).
The proposed plan for this ROD amendment was made available to the public in the
administrative record file located at the Sioux City Public Library, 529 Pierce Street, Sioux
City, Iowa and the EPA Region vn Office, Kansas City, Kansas. A public notice was
published in the Sioux City Journal announcing the commencement and length of the public
comment period and the availability of the administrative record file. The EPA offered to hold
a public meeting to discuss the ROD Amendment if requested; however, no requests were
received. Comments received during the public comment period are addressed in the
Responsiveness Summary. The EPA received no comments to the proposed plan for this ROD
Amendment. '
i
m. REASON FOR ISSUING THE ROD AMENDMENT
During the Remedial Design and subsequent Removal Actions at the site, the EPA
determined that the sediments found in the clay-lined impoundments were generating hydrogen
sulfide gas at concentrations posing significant health risks. Air sampling indicated that the
levels of hydrogen sulfide gas released would significantly increase when the impoundment
sediments were disturbed.
The selected remedy in the ROD for the impoundment sediments is in-situ stabilization
followed by a 2-foot soil cap. In-situ solidification requires disturbing the impoundment
sediments with a large-scale auger. Based on air sampling and modeling, the levels of
hydrogen sulfide released during the mixing of impoundment sediments with solidification
agents are projected to exceed worker permissible exposure limits as defined by the National
Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health
Administration (OSHA). Air dispersion modeling also indicates a reasonable likelihood that
hydrogen sulfide emissions at the site perimeter would exceed the permissible exposure levels
for hydrogen sulfide established by the Agency for Toxic Substances and Disease Registry
(ATSDR).
An alternate remedy of dewatering the sediments would substantially reduce the
disturbance of the impoundment sediments. Therefore, significantly less hydrogen sulfide gas
emissions would be generated as compared to implementation of the in-situ solidification. A
geosynthetic cap or an improved clay cap would be placed over the dewatered sediments
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forming an infiltration barrier that can resist leaching from deformations caused by settling and
drying, thereby, potentially reducing long-term cap maintenance costs.
IV. DESCRIPTION OF THE NEW ALTERNATIVES
The original remedy for remediation of the contaminated soil, sediment and
impoundment water included the following major components:
• Treatment followed by discharge or off-site disposal of impoundment waters;
• In-situ stabilization/solidification of contaminated sediments and soils in the east
aeration lagoon, west aeration lagoon, and northeast field, followed by a 2-foot
soil cap;
• Soil/clay capping of the polishing basin sediments and miscellaneous
contaminated surface soils; \
• Stabilization/solidification of contaminated sludges removed from burial
trenches followed by either onsite or off-site disposal;
• Semi-annual monitoring and maintenance of soil/clay caps and immobilized
materials; and
• Annual long-term ground water monitoring.
The amended remedy will be as protective of human health and the environment, be
more implementable and decrease the cost of the remedial action. The changes include the
replacement of the in-situ solidification of impoundment sediments and northeast field soils
with innovative dewatering technology followed by an improved cover design; inclusion of
additional site contaminated areas at the site into the remedy; and documentation of the final
decisions on waste disposal options identified in the original ROD. The amended remedy will
fully meet the remedial action objectives identified in the Feasibility Study identified as
prevention of direct contact and contaminant migration to the ground water.
The major changes in the amended remedy include:
• Contaminated northeast field soils would not undergo in-situ stabilization, but
rather would be consolidated and/or excavated and consolidated with the
Polishing Basin sediments and covered with an improved soil/clay cap meeting
specified performance criteria or geosynthetic cap such as high-density
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polyethylene (HDPE) that would achieve similar performance criteria. Depth of
the contamination in the northeast field ranges from 1 to 1.5 feet, and a
redesigned cap will continue to provide an implementable, cost-effective, and
equally protective
remedy. Contamination from this area may also be excavated and consolidation
with the Polishing Basin sediments. This would be equally protective and may
be even more cost-effective.
• Sediments in the east and west aeration lagoons would not undergo
stabilization/solidification. Instead, the impoundment areas would be dewatered
and capped. The impoundment covers would be redesigned to incorporate an
improved soil/clay cap meeting the performance criteria or comparable
geosynthetic cap such as high-density polyethylene. Post-ROD sampling
indicated the presence of hydrogen sulfide gas production from the
impoundment sediments. Air sampling and modeling indicates that dangerous
levels of hydrogen sulfide gas would be emitted should the impoundment
sediments be disturbed which would occur under the original remedy. This
change will provide a more cost effective remedy that greatly reduces the
potential for releases of hydrogen sulfide gas, thereby reducing the. health risk to
on-site workers and the nearby public. The amended remedy is also protective
due to the improved cover design.
• Contaminated soil areas, other than the northeast field, will be excavated and
consolidated with the aeration lagoon sediments and/or polishing basin
sediments prior to capping. The original remedy had these areas capped in
place; however, by consolidating these soils, the costs associated with cap
construction will be significantly reduced while maintaining equal protection to
the public health and the environment.
The following are the areas where the original remedy contained options:
• The original remedy indicated that impoundment waters were to be treated as
necessary and either discharged to the nearby oxbow lake or transported off site
to a POTW. All impoundment water will be treated on-site if necessary and
discharged to the nearby oxbow take. The EPA has determined that on-site
treatment would be most cost-effective due to the quantity of water potentially
needing to be treated. This is not a change from the original remedy and just
serves to document EPA's preference for treating the water on-site.
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• The original remedy indicated that contaminated sludges excavated from the
burial trenches were to be stabilized and disposed of either on-site or off-site.
Based on preliminary calculations, on-site stabilization and consolidation with
the northeast field soils followed by capping will be the most cost-effective way
to remedy this area of the site. This is not a change from the original remedy
and just serves to document EPA's preference for treating the burial trench
material on-site.
The following are the areas that the original remedy did not address.
• The original remedy did not address the sediments remaining in the wet well,
aeration basin, and final clarifier. This ROD amendment addresses the removal
of the contaminated material and consolidation of it with the sediments in the
aeration lagoons and/or polishing basin. These sediments would then be
capped. The emptied basins will be decontaminated with high-pressure steam
and backfilled with clean soil. These actions will further reduce the risk of
direct contact to site contaminants and the potential threat of contaminant
releases to the environment.
• The original remedy did not address the decontamination of the filter press
building and miscellaneous contaminated debris. This ROD amendment
addresses decontamination of these areas by washing with a high-pressure steam
cleaner. Wash water will be treated oil-site and discharged to the oxbow lake.
Floor scrapings and building residue will be disposed of in accordance with the
Resource Conservation and Recovery Act (RCRA). These actions will provide
additional protection of human health and the environment.
V. EVALUATION OF ALTERNATIVES
The NCP sets forth nine evaluation criteria which serve as a basis for comparing the
remedial alternatives.for final actions. The nine criteria are divided into three categories:
Threshold Criteria, Primary Balancing Criteria, and Modifying Criteria. If any remedial
alternatives identified during the Feasibility Study do not meet the Threshold Criteria (Criteria
1 and 2), EPA will not consider them as possible final remedies. If the alternatives satisfy the
Threshold Criteria, they then are evaluated against the next five criteria, called the Primary
Balancing Criteria. These criteria are used to compare the remedial alternatives against each
other in terms of effectiveness, implementability, and cost. The final two criteria, state
acceptance and community acceptance, are called Modifying Criteria. The alternatives are
compared against the Modifying Criteria after the state and community have reviewed and
commented on the Proposed Plan and the other alternatives considered by EPA.
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The following is a discussion of the nine criteria used by EPA for remedy selection.
A. Threshold Criteria:
1. Overall Protection of Human Health and the Environment
The EPA assesses the degree to which the alternatives would eliminate,
reduce, or control threats to public health and the environment through
removal, containment, and/or institutional controls. An alternative is
normally considered to be protective of human health if the excess
cancer risk is reduced to less than 1 in 1,000,000 (10"6) and risks do not
pose non-carcinogenic health risks {Hazardous Index (HI) < 1}.
Based on the results of the risk assessment performed at MAT, current
and/or future contact to sediment in the east and west aeration lagoons,
the polishing basin, and the soils in the northeast field, pose a potential
human health risk. The original remedy reduced the threat of exposure
of the contaminants by in-situ stabilization and capping of the soils and
sediments and the removal and discharge of contaminated impoundment
waters. The amended remedy would adequately protect human health
because it addresses the principal threat of exposure by treating and
discharging impoundment waters and by capping the associated
contaminants and preventing direct contact. The amended remedy would
also reduce the likelihood of all exposure of ecological receptors to the
contaminated areas. The amended remedy also provides greater
protection as compared to the original remedy by reducing the likelihood
of hydrogen sulfide gas emissions at levels above worker threshold
standards during the remedial action. In this case, the amended remedy
is more protective. The amended remedy also includes an improved
capping system which will help ensure and minimize contaminant
migration into the groundwater in the future. Institutional controls in the
form of deed restrictions limiting building of structures on site will
supplement the containment measures and help to ensure that exposures
in these areas will not increase to the extent that the carcinogenic risks
would be unacceptable.
2. Compliance with all Applicable or Relevant and Appropriate State
And Federal Environmental Regulations
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The amended remedy will comply with all federal and state applicable or
relevant and appropriate requirements (ARARs). Applicable
requirements are those state or federal requirements legally applicable to
the release or remedial action contemplated that specifically address a
hazardous substance, pollutant, contaminant, remedial action, location,
or other circumstance found at the site. If it is determined that a
requirement is not applicable, it may still be relevant and appropriate to
the circumstances of the release. Requirements are relevant and
appropriate if they address problems or situations sufficiently similar to
the circumstances of the release or remedial action contemplated, and are
well-suited to the site.
The majority of the ARARs which applied for the originally selected
alternative also apply to the amended alternative. The chemical-specific
ARARs that are relevant and appropriate at the site include Ambient
Water Quality Criteria (AWQC) and National Pollution Discharge
Elimination System (NPDES) standards. As with the original remedy,
the amended remedy involves removal of surface water in the polishing
basin and east and west aeration lagoons followed by treatment and
discharge to an on-site surface water (oxbow lake). Soils and sediments
will be capped in place. Capping includes provisions for drainage and
runoff control. The substantive requirements include AWQC, effluent
limitations and monitoring requirements and will be met by the amended
remedy.
The state of Iowa promulgated regulations pursuant to Iowa Code
Section 455E.5 will apply to cleanup actions at the site where significant
amounts of soil contamination are present and groundwater
contamination is occurring. These regulations, set forth in 567 LAC
133, are applicable since groundwater contamination has been observed
at the site. As with the original ROD, groundwater contamination and
long term monitoring will be addressed in a separate action.
The federal and state action-specific ARARs include all OSHA, all
Hazardous Materials Transportation Act (HMTA) regulations, and the
Clean Water Act (CWA) regulations applicable to discharge to POTWs.
The RCRA regulations would only be considered applicable for the
trench material because of the TCLP test results. Trench materials will
be treated through in-situ stabilization prior to consolidation and
capping. The RCRA regulations are not relevant and appropriate to the
chromium contaminated soils and sediments since they do not fail TCLP.
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In addition, RCRA regulations may be considered as relevant and
appropriate for materials which may be generated such as floor
scrapings. Floor scrapings which might be generated as part of the
decontamination process will be tested. Based on the results of these
tests, the materials will either be consolidated with the soils and
sediments and capped or consolidated with the trench materials prior to
in-situ stabilization and capping.
B. Primary Balancing Criteria
1. 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 clean up goals have been met. Institutional controls, including
local zoning regulations which limit the uses of the property and deed
restrictions prohibiting the construction of buildings or other structures
on the capped areas of the site, would prevent damage or deterioration of
the capped areas and exposure of the contaminants present at the site.
These restrictions will apply to this property regardless of any
subsequent change in ownership, thereby offering long-term
effectiveness and permanence of the selected amended remedy.
Evidence indicates that the levels of contamination in several areas of the
site potentially pose a current and/or future risk to human health or the
environment. The implementation of the amended remedy will result in
a reduction in the risk in all areas where contamination was found to
pose a risk through direct contact or inhalation. The amended remedy
provides more protection by including additional areas in the
remediation.
The amended alternative includes treatment of contaminants and
engineering controls. Surface waters will be treated if necessary prior to
discharge. Although contaminated soils and sediments will be left in
place and capped, potential for direct exposure will significantly be
reduced. Mobility of the contaminants will be reduced through
dewatering and an improved capping system. The improved cap will
limit the ability of surface water runoff to cause contaminants to migrate
into the groundwater. Both the original remedy and the amended
remedy rely on groundwater monitoring to ensure that the remedy
continues to provide effective long-term protection of human health and
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the environment. The improved cap contained in the amended remedy
will be constructed and maintained in a manner that provides long term
effectiveness and permanence. Groundwater will be monitored to ensure
that the remedy is operating as designed.
2. Reduction of Toxicity, Mobility, or Volume Through Treatment
Section 121(b) of CERCLA states that remedial actions involving
treatment which permanently and significantly reduce the volume,
mobility or toxicity of the hazardous materials, are to be preferred over
those not involving such treatment. This evaluation criteria relates to the
ability of a remedial alternative to control or eliminate risks caused by
the mobility, toxicity or volume of hazardous wastes.
The amended alternative will reduce the toxicity of the surface waters of
the polishing basin and east and west aeration lagoons by treating these
waters prior to discharge. Neither the original nor the amended remedy
reduce the toxicity of the hazardous constituents in the contaminated
soils and sediments.
The original remedy employed in-situ stabilization to reduce the mobility
of the contaminants. The amended alternative will employ capping and
engineering controls to reduce the mobility of the hazardous constituents.
The amended remedy will reduce mobility of the contaminants through
the use of the clay-lined impoundment system. An improved cap will
further reduce the likelihood of infiltration of surface water causing the
contaminants to migrate.
The original remedy's use of in-situ stabilization would have increased
the volume of material significantly. The amended alternative is an
improvement in that the volume of contamination will actually be
decreased through the dewatering of the polishing basin and
impoundment areas.
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3. Short-Term Effectiveness
Short-term effectiveness evaluates the length of time needed to
implement each segment of the alternatives. The EPA considers the
risks that a particular activity may pose to site workers, nearby residents,
or the local environment. Short-term effectiveness involves the period
of time needed to achieve protection and considers any adverse impacts
on human health and the environment that may be posed during the
construction and implementation period until clean up goals are
achieved.
The amended remedy requires less disturbance of the contaminated
sediments in the impoundment areas, thereby, reducing their agitation
and potential for release of emissions of hydrogen sulfide gas which may
affect on-site workers and nearby residents. The previously selected
remedy anticipated the use of a large-scale auger which would have
significantly disturbed the sediments and resulted in releases of high
levels of hydrogen sulfide gas into the air. Based on air sampling and
modeling, the levels of hydrogen sulfide released during the action of
mixing impoundment sediments with solidification agents as. specified in
the original ROD would exceed worker permissible exposure limits as
defined by NIOSH and OSHA. In addition, air dispersion modeling
indicates that when conducting the original ROD there would be
a reasonable likelihood that hydrogen sulfide emissions at the site
perimeter would exceed the permissible exposure levels for hydrogen
sulfide established by ATSDR.
4. Implementability
The EPA considers how difficult the alternative is to construct and
operate, how other government agencies and EPA will coordinate
monitoring programs and the availability of goods and services and
personnel needed to implement and manage the alternative.
Implementability addresses the technical and administrative feasibility of
a remedy, including the availability of materials and services needed to
implement the chosen solution.
Given the potential for releases of high levels of hydrogen sulfide gas
into the atmosphere, the original remedy is no longer as readily
implementable. Higher levels of worker protection would be necessary.
This would increase the time necessary to implement the remedy and add
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an additional risk factor which must be accounted for in completing the
effort. The amended remedy is readily implementable in that dewatering
the impoundment areas can be implemented more easily than dewatering
followed by solidification. In addition, the amended remedy minimizes
the disturbance of the areas lowering the threat of hydrogen sulfide gas
releases. Therefore, special provisions for dealing with these releases
can be eliminated. Because of the increased concern over the releases of
hydrogen sulfide gas, the original remedy would have taken longer to
complete; however, the amended remedy should be able to be completed
in the original time frame (44 weeks).
5. Cost
The EPA considers capital costs, operation and maintenance costs, and
present worth, which is the cost of the activities that will take place until
the remedial action is completed. Capital costs apply to activities such
as construction, land and site development, and disposal of waste
materials. Annual operation and maintenance costs are spent on
activities such as on-going operation of equipment, insurance and
periodic site reviews.
The CERCLA requires that the EPA select a cost-effective alternative
that protects human health and the environment and meets other
requirements of the law. The EPA has determined that the selected
remedy is as protective and in some cases more protective of human
health and is more
cost effective to implement. The estimated capital cost for the original
remedy was $4,621,300 and Operation & Maintenance cost for 30 years
of $21,000 per year. Costs are estimated to have increased through
inflation to approximately $5,574,000 using today's pricing data for the
same remedy. The original remedy's cost estimate did not include the
cost for remediating the wet well, aeration basin, final clarifier, filter
press building or miscellaneous contaminated soils nor did it include
dewatering and treatment of the total volume of water now contained in
the impoundment areas. The potential for hydrogen sulfide emission
would also increase the cost of implementing the original remedy in that
a higher level of worker protection would be needed during construction
activities. This higher level of protection would cause work to proceed
at a slower pace increasing the overall time needed to complete the
remediation. The increased time on-site would increase the labor costs
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associated with the construction causing the overall costs to be even
higher than the estimate above.
The preliminary cost estimate to implement the amended remedy is
$2,661,593 depending on the amount of consolidation of the
contamination that is possible. This estimate also includes remediation of
all areas identified in the original remedy plus the wet well, aeration
basin, final clarifier, filter press building and miscellaneous
contaminated soils. This estimate prices out the remediation of the
northeast field as a separate containment cell, but does assume that a
moderate amount of consolidation of the contaminated areas is possible.
When these factors are taken into consideration, the cost to implement
the amended remedy is significantly less than the cost to implement the
original remedy. In addition, if a geosynthetic cap is utilized, Operation
& Maintenance (O&M) costs could be reduced since there are minimal
costs associated with long term maintenance of synthetic caps. Overall,
the amended remedy is seen'to be a more cost effective remedy
providing equivalent or greater protection to human health and the
environment.
C. Modifying Criteria:
1. State Acceptance
The state of Iowa, through the Iowa Department of Natural Resources
(IDNR), is supportive of the amended remedy for this site and prefers
this remedy to the originally selected remedy.
2. Community Acceptance
The EPA held a public comment period to allow the community to
comment on the preferred alternative as set forth in the proposed plan
and supported by the administrative record. In addition, the EPA
notified the public regarding its willingness to conduct a public
availability session on the proposed plan. The EPA did not receive any
comments regarding the proposed ROD Amendment at the site nor
requests to conduct a public meeting.
In comparing the original remedy with the amended remedy, the EPA has determined
that the original and amended remedy meet the threshold criteria, overall protection of human
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health and the environment, and compliance with state and federal requirements.
The amended remedy presents the better balance of tradeoffs, with respect to the
primary balancing criteria, in particular with respect to implementability and cost. In addition,
the amended remedy continues to be protective of human health and reduces mobility of the
contamination by providing an improved capping system. For the modifying criteria of state
and community acceptance, the amended alternative is preferred. In the tradeoff and balancing
of all nine criteria, the amended remedy is EPA's preferred remedy.
VI. STATUTORY DETERMINATIONS
The EPA has determined, and the state of Iowa concurs, that the selected amended
remedy herein satisfies the statutory requirements specified in CERCLA Section 121 which
state that the selected remedy must protect human health and the environment and comply with
applicable or relevant and appropriate federal and state requirements. In addition, the
remedy, as amended, utilizes permanent solutions and alternative treatment technologies to the
maximum extent practicable for this site. These changes to the remedy will increase
protectiveness of human health and environment, both short term and long term.
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ATTACHMENT A
RESPONSIVENESS SUMMARY
RECORD OF DECISION AMENDMENT
MID-AMERICA TANNING COMPANY SUPERFUND SITE
In accordance with CERCLA Section 117, a public comment period was held from May
13, 1996 to June 11, 1996, to receive comments from interested patties on the EPA's proposed
plan for the Record of Decision Amendment for the Mid America Tanning Company Superfund
Site, Sergeant Bluff, Iowa. The EPA received no written comments on the proposed plan.
The EPA offered to hold a public meeting if requested. No requests for a public meeting
were received.
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