United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R07-92/059
September 1992
&EPA Superfund
Record of Decision:
Farmers Mutual Cooperative,
IA
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NOTICE
The appendices listed in the index that are not found in this document have been removed at the request of
the issuing agency. They contain material which supplement. but adds no further applicable information to
the content of the document. All supplemental material is, however, contained in the administrative record
for this site.
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50272.101
REPORT DOCUMENTATION 1" REPORT NO. I ~ 3. Recipient'e Accell8ion No.
PAGE EPA/ROD/R07-92/059
4. TItle 8nd SWIItIe S. Report Oate
SUPERFUND RECORD OF DECISION 09/29/92
Farmers Mutual Cooperative, IA
6.
First Remedial Action - Final
7. Autharte) 8. Perfonnlng Org...ization Rept. No.
II. Pitrfonnlng Orgelnlzation Name end AddnIaa 10. ProjectlTeaklWork Unit No.
11. ContreCl(C) or Grent{G) No.
(C)
(G)
1~ Sponeoring Org8nlz8llon Name end AdIh88 13. Type 01 Repon & Period Covered
U.S. Environmental Protection Agency 800/000
401 M Street, S.W.
Washington, D.C. 20460 14.
15. SupPement8ry No..
PB93-964303
16. Ab81r8ct (UmIt: 200 wonfe)
The 6-acre Farmers Mutual Cooperative site is an active grain storage facility in
Hospers, Sioux County, Iowa. Land use in the area is predominantly agricultural. The
643 residents of the City of Hospers obtain their drinking water from municipal water
supplies and private wells. From 1908 to the present, the Farmers Mutual Cooperative
Company (FMCC) used the site for the purchasing and storing of grain and agricultural
chemicals, including pesticides and fertilizers. In addition, grain fumigation had
been conducted onsite. In 1984, state investigations detected VOCs and herbicides in
the ground water of three shallow city wells adjacent to the FMCC facility. In 1989,
the state ordered FMCC to conduct an RI/FS, which showed ground water contamination
was limited to the shallow wells and did not impact the deeper aquifer. The City of
Hospers uses three deep aquifer wells and installed an additonal deep well to meet
their water supply needs. Prior actions, including removal of bulk pesticides and
further handling from FMCC, have been taken to prevent additional release of
contaminants. This ROD addresses ground water contamination as a final remedial
action for this site. The primary contaminants of concern affecting the ground water
(See Attached Page)
17. Document Ane/y8I8 L DescrI~o...
Record of Decision - Farmers Mutual Cooperative, IA
First Remedial Action - Final
Contaminated Medium: gw
Key Contaminants: VOCs (carbon tetrachloride), other organics (chloroform,
herbicides)
b. Identifier8/Open-Endeci Terms
c. COSAl1 FieIdIGroup
18. Availability Statement 19. Secl8ity Cless (This Report) 21. No. o' Peges
None 30
20. Security Class (Thie Pege) n Price
N(')n~
272 (4-77)
(See ANSl-Z38.18)
See InslrlN;fjone on Revetse
(Formerty NT15-3S)
Department 01 Commerce
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EPA/ROD/R07-92/059
Farmers Mutual Cooperative, IA
First Remedial Action - Final
Abstract (Continued)
are VOCs, including carbon tetrachlbridei and other organics, including chloroform and
herbicides.
The selected remedial action for this site includes natural attenuation of the ground
water contaminant levels and monitoring to determine the effectiveness of the remedy and
to ensure that the contaminant levels do not increase. The selected alternative provides
a contingency remedy in the event use of the impacted aquifer for water supply is sought.
The contingent remedy includes blending water from the upper and lower aquifers until
MCLs have been achieved, testing the upper aquifer prior to its use, treating
contaminated ground water for use as drinking water, or containing contaminants to enable
use of the impacted aquifer without treatment. The estimated present worth cost range
for this remedial action in $93,000 to $187,000, depending on the remedy used. O&M costs
are not associated with this remedy.
PERFORMANCE STANDARDS OR GOALS: Chemical-specific ground
on SDWA MCLs and include carbon tetrachloride 0.005 mg/l,
0.002 mg/l, atrazine 0.003 mg/l.
water clean-up goals are based
chloroform 0.1 mg/l, alachlor
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RECORD OF. DECISION
FOR
FARMERS MUTUAL COOPERATIVE COMPANY SITE
HOSPERS, IOWA
PREPARED BY:
IOWA DEPARTMENT OF NATURAL RESOURCES
September 24, 1992
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RECORD OF DECISION
FARMERS MUTUAL COOPERATIVE COMPANY
HOSPERS, IOWA
DEClARATION
1.0
Site Name and Location
Farmers Mutual Cooperative Company Site
Hospers, IOwa
1.1
Statement of Basis and Puqx>se
This decision document presents the selected remedial action for the Farmers Mutual Cooperative
Company site located in Hospers, Iowa. The remedial 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) 42 U.S.c. Section
9601 ~ and, to the extent practicable, the National Oil and. Hazardous Substances Pollution
Contingency. Plan (NCP) 40 C.F.R. Pan 300.
This decision is based on the documents and information contained in the Administrative Record for
the site. A copy of the Administrative Record is available for review in the Iowa Department of
Natural Resources (DNR) Records Center in Des Moines, Iowa and in the City Hall in Hospers,
Iowa.
The U.S. Environmental Protection Agency concurs with the selected remedy for this site.
1.2
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, may present a current or potential threat to
public health, welfare or the environment
1.3
Description of the Remedv
In consultation with the U.S. Environmental Protection Agency (EP A), DNR has determined that no
active remedial action, other than monitoring, is required unless the water from the impacted aquifer
is used for drinking water by the City of Hospers or others. Natural attenuation is believed to be
occurring and is a feasible and reasonable means of groundwater cleanup. Actions, including removal
of bulk pesticide and fenilizer handling from the Farmers Mutual Coop facility in Hospers, have
already been taken to prevent additional release of contaminants. Significant attenuation of some
contaminants has already occurred. The residual contamination does not pose a significant threat to
human health or the environment However, groundwater contamination in excess of drinking water
standards still exists. If a use of the impacted aquifer is sought prior to natural attenuation reducing
contaminant levels below MCLs, contingency measures will be implemented as follows:
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. Developing and implementing a blending program for the City of Hospers, including test
pumping and sampling of the shallow wells prior to their use;
. Conducting any additional monitoring required of the City of Hospers due to use of shallow
wells in the impacted aquifer; and
. Implementing measures to reduce contaminllnt levels, if necessary to meet MCLs,
including: .
. Treatment of water from the impacted aquifer for use as drinking water, or
. Containment of contllminants to enable use of the impacted aquifer without
treatment
The selected response action constitutes final action for this site.
1.4
Statutorv 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. and
is cost-effective. This remedy utilizes permanent solutions and alternative treatment technologies to the
maximum extent practicable for this site. However, because treatment of the principal threats of the
site was not found to be practicable, this remedy does not satisfy the statutory preference for treatment
as a principal element of the remedy.
Because this remedy will result in hazardous substances remaining on-site above health-based levels, a
review will be conducted within five years after commencement of remedial actions to ensure that the
remedy continues to provide adequate protection of human health and the environment.
9-29-77
DATE
Concurred:
----- --." ~ \ \ O. A
ALiANST~AD~~TOR A,:- /';-1(
IOWA DNR, ENVIRONMENTAL PROTECI'lON DMSION
?j7fi9:L
, D TE
3
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DECISION SUMMARY
2.0
Site Name. Location. and Description
The Farmers Mutual Cooperative Company (FMCC) site is located in the Northwest 1/4 of the
Southeast 1/4 of Section 3, Township 9S North, Range 43 West, Sioux County, in the Cty of Hospers
in northwestern Iowa (Figure 1). The 6-acre site is located on the northwest oorner of the city just
east of the Floyd River. The Cty of Hospers had a 1990 population of 643. The surrounding region
is primarily agricultural Water supplies in this region of the state are obtained largely from shallow
unconsolidated aquifers. Larger supplies are obtained from deposits of sand and gravel in current
sueam valleys and in buried channels from past sueams. Smaller supplies can be obtained from
shallow wells in glacial drift. Large quan~ities of groundwater are available from the Dakota bedrock
aquifer. The rural water district serving the area obtains water from shallow and deep sand-and-gravel
aquifers. .
2.1
Site History and Enforcement Activities
The FMCC facility began operation in 1908 and has undergone several expansions since then. The
FMCC facility was purchased by the Farmers Cooperative Elevator Association of Sheldon, Iowa (the
Coop) in 1989. The FMCC facility is typical of many such farm oooperatives throughout the state.
In addition to buying and storing of grain, agricultural chemicals, including fertilizers and pesticides,
have been sold at the FMCC facility and custom applied. Related to grain storage, grain fumigation
has been oonducted. The Coop recently removed all bulk chemicals from their Hospers facility.
The FMCC site has been investigated due to. the presence of herbicides and volatile organic
oompounds (VOCS) in groundwater at the site. Groundwater oontamination related to the FMCC
site was first identified in 1984 from samples collected by the State from three shallow wells which
were then used .for water supply by the Cty of Hospers, Iowa. These wells are located adjacent to
the FMCC facility. Subsequent sampling of soils and groundwater was conducted by the State, results
of which demonstrated that the FMCC facility was a source of these oontaminants. The Cty of
Hospers has since been prohibited from using the three shallow wells. The Cty had three deep
Dakota Aquifer wells which were not impacted by the site and installed an additional deep well to
meet their water supply needs. However, water from the deep"wells has high mineral contenL The
shallow well water was previously blended with the deep well water to provide a more palatable
drinking water.
The FMcc, in oooperation with the DNR and EP A, has been oonducting investigations of the site
since 1984. In August of 1986 the DNR ordered FMCC to conduct a remedial investigation/feasibility
study of the site. The site was proposed for the National Priorities Ust (NPL) in June of 1988 and
became a final NPL site in August of 1990. Phase 1 investigations were oompleted by FMCC in 1986
and" involved inStallation and sampling of four monitoring wells, surface water sampling. and soil
sampling at suspected oontaminant source areas. Phase 2 investigations were oompleted in 1989 and
oonsisted of installation of three additional monitoring wells, sampling of all monitoring wells and the
three shallow city wells, and an aquifer pumping tesL Phase 3 investigations were oompleted in 1990
and involved installation of ten additional monitoring wells and oomprehensive sampling of all
monitoring wells and the three shallow city wells. Phase 4 investigations were oompleted in 1992 and
involved installation and sampling of four monitoring wells and thirteen soil borings in an area
previously identified as having very high levels of herbicides in groundwater. Figure 2 is a site map
showing monitoring well and soil sampling locations. The DNR has also oonducted a related
investigation to identify potential oontaminant sources not located on Coop property and to determine
the extent and magnitude of carbon tetrachloride oontainination in groundwater.
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22
Hi2hli2hts of Communitv PaniciDation
A Proposed Plan for the FMCC site was released to the public in May 1991. A public comment
period was held from May 2, 1991, through July 15, 1991. A public meeting was held in Hospers on
May 21, 1991, which was attended by about 30 people. The 1991 Proposed Plan recommended a
groundwater pump-and-tteat action to enable the City of Hospers to regain use of their shallow weUs.
Additional work to pinpoint herbicide contamination for possible source conuel action and to
determine the extent of residual volatile organic contamination was also recommended. Due to
requests from the City of Hospers and the Coop, the public comment period was extended twice. The
City of Hospers commented that they preferred that the Coop help them obtain another water supply
instead of spending money to cleanup the shallow groundwater contamination. In response to this
comment, the Record of Decision (ROD) for the site was delayed pending completion of the
proposed additional investigations. This decision was made because no significant risks were identified
other than use of the shallow aquifer for water supply and, since immediate.use of the impacted
groundwater was no longer being contemplated, it was deemed prudent to deiay the final decision
until information from the additional investigations was available.
Another Proposed PJan, which incorporated data which was not available in the previous Proposed
Plan, was released to the public on August 25, 1992. Based on the additional data a different remedy,
natural attenuation, became a viable alternative. 'Ibis Proposed Plan and supporting information were
made available to the public in the administrative record, a copy of which was maintained at the
Hospers City Hall and the DNR Records Center in the Wallace Building, Des Moines, Iowa. The
notice of availability of these documents and time and location for the public meeting were published
in the Siouxland Press on August 25, 1992. Fact sheets which summarized she activities, indicated
the proposed remedy, gave the location of the Administrative Record, and indicated the. public
meeting time and location were mailed to 23 parties, including 6 media companies. A public meeting
was held on September 3, 1992, at the Hospers City Hall in which about 50 people attended. At this
meeting representatives from the DNR, the EP A, and the Iowa Department of Health described the
site and the proposed remedy and addressed comments and questions. A response to the comments
received at the public meetings and other comments received during the public comment period,
which ended on September 23, 1992, are included in the Responsiveness Summary, which is pan of
this Record of Decision.
23
Scone and Role of Resoonse Actions
The selected response action addresses the principal threat of groundwater contamination. The
contaminated groundwater is the principal threat at this site because of potential direct ingestion of
water containing contaminants above health-based levels. The purpose of this response action is to
allow natural attenuation to reduce contaminant levels in groundwater to below health-based levels
and. to ensure that people do not ingest water above health-based standards due to residual
contamination in the meantime. The response actions selected in this ROD address all principal
threats posed by this site and are intended to constitute final remedial action for the site.
2.4
Summat)' of Site Characteristics
The following is a summary of site characteristics based on the results from the remedial
investigations:
. The site is underlain by a shallow sand and gravel aquifer which is locally productive and was
previously used for water supply by the City of Hospers. The City now obtains water from the deeper
Dakota Aquifer. Glacial till and shale units separate the shallow sand and gravel aquifer from the
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Dakota aquifer. The till and shale retard movement of groundwater thus protecting the Dakota
Aquifer from contaminants in the shallow aquifer.
. Row in the shallow aquifer is to the southwest at approximately two feet per day with discharge to
the nearby F10yd River. Upgradient and downgradient sampling of the F10yd River have revealed no
significant impact due discharge of groundwater from the site.
. Groundwater contamination has been found in the shallow aquifer in a relatively small area between
the Coop and the Royd River (see Figure 3). Table 1 summarizes groundwater sampling information.
. Sampling to date has revealed no area with levels of soil contaminants which warrant soU remediation
(see Table 2).
.. All grain storage facilities where carbon tetrachloride was used as a grain fumigant are likely sources
of groundwater contamination. Carbon tetrachloride was used as a grain fumigant until it was banned
for this use in 1986. Carbon tetrachloride is the primary volatile organic contaminant associated with
the site.
. The levels of VOCs (carbon tetrachloride in particular) in groundwater samples have declined
substantially in recent years. The investigation by DNR has shown that residual levels of VOCs are
small and limited in extenL The diminished nature of VOC contamination is likely attn"buted to
natural attenuation. Figure 4 shows areas of carbon tetrachloride contamination in groundwater in
1985 and 1991.
. Elevated levels of herbicides have been found throughout most of the site. A groundwater sample
from a temporary well-point nonh of Warehouse #S (GW-l in Figure 2) revealed very high levels of
herbicides, indicative of a contaminant source area. However, follow-up soil sampling in this area
failed to identify any significant soU contamination. Another likely herbicide source area is the area
near the office and Warehouse #1 (see Figure 2). Otherwise, monitoring results suggest that
herbicide contamination is from diverse sources throughout the site.
. The Coop has recently taken action to prevent funher release of herbicides to groundwater at the site.
Bulk fenilizer and bulk pesticides are no longer available at the Hospers facility and no application
of these products will be conducted out of the Hospers facility.
25
Summary of Site Risks
Contaminants found in the groundwater include volatile organic compounds associated with grain
fumigation (carbon tetrachloride and chloroform) and common herbicides (Atrazine, Bladex. Dual,
Lasso, $encor, and Treflan). Carbon tetrachloride and Atrazine have frequently been found in
groundwater at concentrations in excess of federal Maximum Contaminant ~els (MCLs) for safe
drinking water. Carbon tetrachloride, chloroform, and Lasso are classified as B2 carcinogens; meaning
there is sufficient evidence of carcinogenicity in animals but inadequate evidence of carcinogenicity
in humans. All three have been found at concentrations associated with more than a one-in-a-million
cancer risk. Carbon tetrachloride was found to pose the greatest risk; not only from drinking water,
but also from inhalation of volatilized carbon tetrachloride during showering.
A Baseline Risk Assessment was prepared by the DNR and subsequently modified by EP A to
incorporate new information. Results from the Baseline Risk Assessment are summarized in Table
3. Various current and future exposure scenarios were evaluated and unacceptable non-cancer and
cancer risks were identified for exposure to groundwater from City Well #9, based on all data from
that well, and exposure to water from the three shallow City wells, based on data collected when the
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City wells were actively used. In both of these scenarios the risk was largely due to carbon
tetrachloride. Recent information has shown a substantial reduction in carbon tetrachloride levels
in groundwater. Carbon tetrachloride may no longer present a significant problem in the shallow City
wells; however, this will be confirmed by test pumping of the City wells prior to their use.
. Contaminated soils were found to potentially pose minimal risks.
The Iowa Department of Public Health has conducted a Health Assessment of the FMCC site under
a cooperative agreement with the U.S. Public Health Service, Agency for Toxic Substances and
Disease Regisuy. They concluded that the site is a public health concern because of the risk to health
from the exposure to hazardous substances via direct ingestion, inhalation from sea>ndaly household
use, and dermal contact of groundwater. They did not identify public health concerns from on-site
surface and sub-surface soils, off-site surface water, or the food chain.
It should be emphasized that currently there is no exposure to the contaminated groundwater and that
the DNR will continue to enforce the Safe Drinking Water Act MCLs to ensure that drinking water
of acceptable quality is provided by the city.
26
Description of Alternatives
Below is a description of the four remedial action alternatives (RAAs) which were considered for this
site.
RAA 1 . No (Additional) Action
This RAA would involve no additional action to clean up groundwater at the site. Previous actions
taken to mitigate contamination problems associated with the site, which are common components
of all the RAAs, include:
. Discontinued use of the three shallow city wells in 1988.
. Placement of the site on the state Registry of Hazardous Waste or Hazardous Substance Disposal
Sites (final placement pending). This action will prevent sale or significant change in use of the
property without approval by the DNR. Notice of this listing will be recorded on the property
deed.
. Elimination of bulk pesticide handling facilities to prevent further release of herbicides.
. Discontinued use of carbon tetrachloride as a grain fumigant in 1986.
. ~atural attenuation of contaminants (e.g., dilution and biological breakdown) resulting in reduced
contaminant concentrations.
There are essentially no costs associated with this alternative. These activities have all been
completed, except the State regisuy listing.
RAA 2 . Natural Attenuation and Monitoring with Drinking Water Contingency
In addition to actions included in RAA 1, this RAA would involve use of existing monitoring wells
to determine the effectiveness of natural attenuation in reducing contamin3nt levels in groundwater.
A monitoring program would be developed which defines the location, frequency, monitoring
parameters, and criteria for termination of the program. In addition, this alternative would have a
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contingency in the event the City of Hospers desires to regain use of the impacted aquifer for a
drinking water supply. For the City of Hospers, compliance with MCLs would have to be achieved
in the water distn"bution system with a blending program which is acceptable to the DNR and EP A
Additional contingency action (i.e., treatment or containment) may be required only if an acceptable
blending program cannot be developed. In any event, additional contingency action (beyond blending)
will not be required if blending equal portions of shallow and deep well water yields water in which
the site contaminants meet MCLs. The appropriate contingency measures would also apply to any
private water supply which utilized the impacted aquifer. Contingency measures would be:
. Developing and implementing Ii blending p~gram for the City of Hospers, including test
pumping and sampling of the shallow wells prior to their use;
. Conducting any additional monitoring required of the City of Hospers due to use of
shallow wells in the impacted aquifer; and
. linplementing measures to reduce contaminant levels, if necessary to meet MCLs,
including:
. Treatment of water from the impacted aquifer for use as drinking water, or
. Containment of contaminants to enable use of the impacted aquifer without
treatment
The estimated present worth cost of this alternative is $93,000 (without the contingency) and it would
take about 3 months to begin implementation. The estimated present worth cost is $187,000 if a
blending program for the City of Hospers is implemented and would take about 6 months to begin
implementation. If measures to reduce contaminant levels are necessary, the cost and implementation
time could be as much as for RAA 3.
RAA 3 - Natural Attenuation with Containment of Contaminants
This alternative would involve pumping contaminated groundwater and passing it through a granular
activated carbon (GAC) treatment unit The objective of this alternative would be to minimi7,e the
area of groundwater contamination and prevent untreated discharge of contaminants to the Floyd
River. It is also effective in removing volatile organic compounds such as carbon tetrachloride and
chloroform. Extraction wells would be located and sized to draw in contaminated groundwater from
primary contaminant source areas. This could include use of one or more of the three shallow dty
wells or installation of new wells. Treated water would be discharged directly to the river, used for
irrigation and/or used for subsurface infiltration to facilitate flushing of contaminants from the
groundwater system.
The present worth of this alternative is roughly estimated to be $600,000; including $103,000 initial
capital cost and S41,000/year for operation and maintenance over a 20 year period. It is estimated
that it would take about one year to begin implementation of this RAA
RAA 4 - In-Situ Bioremecliation
This RAA would involve enhancing natural biological degradation of contaminants. In-situ
bioremediation would involve providing nutrients to microbes which are used to digest the target
contaminants. Existing microbes may be available or microbes which are spedally acclimated to the
target contaminants may be injected into the ground. Nutrients (e.g., nitrogen, phosphorous, and
oxygen) would be injected into the ground via water. The system would be closely monitored.
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2.7
Treatability studies would have to be oonducted to determine the oost and effectiveness of
bioremediation.
The present worth oost of this alternative is estimated to range from $1,000,000 to $2,000,000. There
are many uncertainties regarding this alternative making the oost difficult to estimate and thus very
rough. It is estimated that it would take about two years to begin implementation of this RAA.
Summary of ComDarative Analvsis of Alternatives
A oomparative analysis of each alternative against the following nine criteria has been made. These
nine criteria are categorized into three groups: threshold criteria, primary balancing criteria, and
modifying criteria. The threshold criteria must be satisfied for an alternative to be eligible for
selection. The primary balancing criteria are used to weigh major tradeoffs among alternatives. The
modifying criteria are take into aemont the public oomment on the Proposed Plan and the suppon
agenq ooncurrence. A glossary of the nine criteria follows.
Glossa" or Evaluation Criteria
Threshold Criteria:
Overall Protection of Human Health and Environment addresses whether or not a remedy
provides adequate protection and describes how risks posed through each pathway are
eliminated, reduced, or oontrolled through treatment, engineering oontrols, or institutional
oonti'ols.
Compliance with AppliJ:able or Relevant and Approprillte Requirements (ARARs) addresses
whether or not a remedy will meet all of the ARARs of other Federal and State
environmental statutes and/or provide grounds for invoking a waiver.
Primary Balancing Criteria:
Long-Term Effectiveness and Permanence refers to the magnitude of residual risk and the
ability of a remedy to maintain reliable protection of human health and the environment over
time once cleanup goals have been met
Reduction of Toxicity, Mobility, or Volume through Treatment is the anticipated performance
of the treatment technologies that may be employed in a remedy.
Short-Term Effectiveness refers to the speed with which the remedy achieves protection, as
well as the remedy's potential to create adverse impacts on human health and the
environment that may result during the oonstruction and implementation period. .
Implemenl.ability is the technical and administrative feasibility of a remedy, including the
availability of materials and services needed to implement the chosen solution.
Cost includes capital and operation and maintenance 00515. Present worth 00515 are based
upon capital 00515 plus the present sum necessary for operation and maintenance over a given
period and a discount rate of 5% (before taxes and after infiation).
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Modifying Criteria:
Support Agency Acceptmu:e indicates whether the EP A concurs with the preferred alternative.
Community Acceptance will be addressed in the Record 01 Decision of the public comments
received on the Remedial Investigation/Feasibility Study and the Proposed Plim.
Overall Protection or Human Health and the Environment
All four alternatives provide adequate protection of human health and the environmenL RAAs 2,
3, and 4 would provide the highest level of protection because all provide for use of groundwater from
the impacted aquifer in the near future. RAAs I, 2, and 3 would rely on natural attenuation which
would result in contaminants remaining in groundwater for a longer period than RAA 4 (assuming
RAA 4 could be effectively implemented). RAAs 2 and 3 would ensure that unsafe human exposure
would not occur in the meantime. With RAA 1 unsafe human exposure to groundwater contaminants
could occur if the groundwater is used for water supply prior to natural attenuation significantly
reducing contaminant levels. With RAA 1 and 2 contaminants would discharge naturally to the river,
although no significant impact is anticipated.
Compllance with ARARs
The primary regulations which would be ARARs for this site are the federal Safe Drinking Water Act
which contains Maximum Contaminant Levels (MCLs) and proposed MCLs, state groundwater
cleanup rules, and federa1!state wastewater discharge requirements. All RAAs would ultimately
comply with state groundwater cleanup rules which require -use of best available technology and best
management practices (BATIBMP) as long as it is reasonable and practical to remove all
contaminants, and in any event until water contamination remains below the action level for any
contaminant-. Natural attenuation is considered to be BATIBMP for this site.
RAA 1 would likely not be able to attain the drinking water MCL in the near future for at least
Atrazine. RAAs 2 and 3 would ensure that MCLs are achieved for drinking water by blending,
treatment, or contaminant containment measures. Wastewater discharge requirements would be
applicable only to RAA 3 and possibly RAA 2. Treatment would be provided, if necessary to meet
wastewater discharge requirements. RAA 4 would comply with all ARARs if bioremediation proves
to provide effective treatment for attaining MCLs.
Long-Term Effectiveness and Permanence
All RAAs would provide the same degree of long-term effectiveness and permanence because natural
attenuation has been determined to be effective at this site.
Short-Term Effectiveness
RAA 1 would do nothing for short-term use of the impacted aquifer. Use of the shallow aquifer for
water supply by the City of Hospers would be most likely achieved in the short-term with RAA 2 or
3. RAA 4 would likely take an extended period of time to implement and thus would be unlikely to
provide significant short-term benefits. Construction activities for any of the RAAs are not expected
to result in any significant adverse impact to human health or the environmenL
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Implementability
RAAs 1 and 2 are the easiest to implement since they may not involve active cleanup. RAA 3 would
be relatively easy to implement since it involves proven technologies. RAA 4 would be the most
difficult to implement since the effectiveness of bioremediation is not proven for this site. RAA 4
would thus involve a considerable amount of testing prior to implementing the action. The nature
of this site with disperse occurrence of contaminants at only moderate to low concentrations would
likely make bioremediation difficult to implement effectively.
Cost
The estimated cost of each alternative is provided under the description of each alternative. It should
be noted that cost estimates have a low level of aocuracy at this stage and are intended primarily for
relative comparisons between alternatives.
Support Agency Concurrence
The EP A is support agency for this site and supports the choice of action.
Community Acceptance
The public comments are described in the Responsiveness SummaI}' which is Part 3 of this Record
of Decision.
28
The Selected Remedv
The selected remedy is Alternative 2, Natural Attenuation and Monitoring with Drinking Water
Contingency. This remedy recognizes that natural attenuation is a reasonable and feasible means of
groundwater cleanup. Recent data shows that natural attenuation is occurring at the site. A
substantial reduction in VOC contamination of groundwater by natural attenuation has already been
demonstrated. VOC contamination of groundwater is no longer believed to be a significant problem.
Herbicide contamination of groundwater persists above drinking water standards, especially for the
herbicide Atrazine. However, despite reasonable efforts to pinpoint the source of herbicide
contamination, no significant source has been identified which could be otherwise remediated.
Containment of contaminated groundwater is possible. However, without drinking water use,
containment would result in no significant benefiL Therefore, natural attenuation has been
determined to be an acceptable means of groundwater remediation.
A monitoring program will be established to determine the effectiveness of natural attenuation and
to e~ure that the magnitude and extent of contamination does not increase. The monitoring program
will utilize existing monitoring wells. A monitoring plan will be developed which identifies monitoring
locations, frequency, and parameters and criteria for modification and termination of the program.
The selected alternative provides a contingency in the event use of the impacted aquifer for water
supply is sought, particularly by the City of Hospers. The City of Hospers previously blended water
from its shallow and deep wells. The objective of the contingency with respect to the Hospers' Water
Supply would be to provide a water supply which is roughly comparable to their past water supply
when shallow and deep well waters were blended. The contingency will assure that compliance with
MCU for contaminal1ts associated with the site will be achieved in the Hospers' water distnDution
system. If blending program is developed which meets the approval of the DNR and EP A. no
additional contingency action will be required. If an acceptable blending program which meets MCU
. cannot be developed. then additional actions will be required (i.e., treatment or containment). In any
11
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event, if blending of equal ponions of shallow and deep well waters yields water which meets MCLs,
no additional contingency (beyond blending) will be required. Appropriate contingency measures
would also apply to any private water supply impacted by site contaminants. In suIDID3IY, contingency
measures would include the following.
. Developing and implementing a blending program for the City of Hospers, including test
pumping and sampling of the shallow wells prior to their use;
. Conducting any additional monitoring required of the City of Hospers due to use of
shallow wells in the impacted aquifer; and
. Implementing measures to reduce contaminant levels, if necessary to meet MCLs,
including:
. Treatment of water from the impacted aquifer for use as drinking water, or
. Containment of contaminants to enable use of the impacted aquifer without
treatmenL
2.9
StatutoIV Determinations
Under its legal authorities, EP A's primary responsibility at Superfund sites is to undertake remedial
actions that achieve adequate protection of human health and the environmenL In addition, section
121 of CERClA established several other statutory requirements and preferences. These specify that,
when complete, the selected remedial action for this site must comply with applicable or relevant and
appropriate (ARARs) environmental standards established under Federal and State environmental
laws unless a statutory waiver is justified. The selected remedy also must be cost-effective and utilize
permanent solutions and alternative treatment technologies or resource recovery technologies to the
maximum extent practical. Finally, the statute includes a preference for remedies that employ
treatment that permanently and significantly reduce the volume, toxicity, or mobility of hazardous
wastes as their principal elemenL The following sections discuss how the selected remedy meets these
statutory requirements.
Protection or Human Health and the Environment
The selected remedy protects human health and the environment by ensuring that water supplies will
not contain site contaminants above MCLs. Natural attenuation will eventually result in a reduction
of site contaminants below MCLs. In the meantime, measures (Le., blending, treatment, and/or
containment) will be taken, if necessary, to ensure that MCLs are not exceeded in drinking water
supplies due to site contaminants. The site not been shown to cause any significant adverse impact
on the environmenL
Compliance with Applicable or Relevant and Appropriate Requirements
The following ARARs apply to the selected remedy:
H groundwater which has been impacted by the site is used for water supply, drinking water must meet
the following Maximum Contaminant Levels (MCLs) under the Federal Safe Drinking Water Act
(SDW A):
12
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Carbon Tetrachloride
Chloroform
Alachlor
Atrazine
0.005 mgll
0.100 mgll
0.002 mgll
0.003 mgll
The selected alternative would comply with state groundwater cleanup rules which require .use of best
available technology and best management practices (BATIBMP) as long as it is reasonable and
practical to remove all contaminants, and in any event until water contamination remains below the
action level for any contaminant.. Action levels are Lifetime Health Advisory Levels for non-
carcinogens and the one-in-a-million cancer risk for carcinogens. Natural attenuation is considered
to be BATIBMP for this site for the following reasons.
. Investigations have shown that natural attenuation has already caused a majo~ reduction
in carbon tetrachloride contamination. Carbon tetrachloride may no longer exceed MCI...s
in the City wells, although this cannot be positively demonstrated without active pumping
of the City wells.
. Persistent levels of herbicides, particularly Atrazine (Aatrex) and Dual (Metalochlor), have
been found in site groundwater. This could be the result of continued releases of these
contaminants and/or a subsurface source (e.g., contaminated soils resulting from a past
spill(s». The Coop has taken measures to prevent releases in recent years which suggests
that much of the herbicide contamination found in groundwater is the result of past
releases. No significant source of herbicide contamination has been found in site soils,
despite reasonable efforts to identify such sources. Without knowledge of the source(s) of
contamination, natural attenuation is the most reasonable means of ultimate groundwater
remediation.
. Prevention of additional releases will be assured by the Coop's elimination of handling of
bulk chemicals at the site.
. Levels of herbicides in groundwater are relatively low. Only Atrazine is consistently found
above MCI...s. .
Wastewater discharge requirements in accordance with the National Pollutant Discharge Elimination
System (NPDES) program as administered by the DNR, may be applicable if the contingency involves
discharge of wastewater. If so, treatment will be provided as necessary to meet NPDES discharge
requirements.
Cost.EfI'ectiveness
The selected remedy is cost effective because it has been determined to provide overall effectiveness
proportional to its cost, with the net present value being approximately $93,000 (without the
contingency). The selected remedy is the least costly of remedies that were judged to provide equal
protection of human health.
Utilization of Permanent Solutions and Alternative Treatment Technologies to the Maximum Extent
Practicable
The DNR and the EP A have determined that the selected remedy represents the maximum extent to
which permanent solutions and treatment technologies can be utilized in a cost-effective manner for
the Farmers Mutual Coop Site. Of those alternatives that are protective of human health and the
environment and comply with ARARs, DNR and EP A have determined that this selected remedy
13
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provides the best balance in terms of long-term effectiveness and permanence, reduction in toxicity,
mobility or volume achieved through treatment, shon-term effectiveness, implementability, and COSL
DNR and EP A also considered the statutory preference for treatment as a principal element, and
considered input from the community.
All the alternatives evaluated would be protective of human health and the environment on a long-
term basis. Because no liquid wastes or highly toxic wastes have been identified at the site, the
additional benefit to be gained from RAA 3 and RAA 4 over RAA 2 in ensuring the protection of
human health and the environment are marginal.
The selected remedy, natural attenuation, does not reduce mobility of site contaminants unless the
contingenq action is triggered and containment methods are implemented. However, the selected
remedy does reduce toxicity and volume of site contamin~l'Its by allowing biodegradation to continue
to occur within the impacted aquifer. This reduction in site contaminants will be monitored until
health based levels in ground water are reached and sustained for a period of time. In addition, a
reduction of CODtaminallt volume would occur if the contingenq action is triggered and treatment
such as use of activated carbon is implemented.
All four alternatives have a high degree of long-term effectiveness because, with or without treatment,
natural attenuation will continue to occur as long as contaminants are present in the ground water.
RAA 1 provides no shon-term effectiveness because it does not allow for use or treatment of the
impacted aquifer. Use of the shallow aquifer as a water supply by the City of Hospers would be most
likely achieved in the shon-term with RAA 2 or 3. RAA 4 would likely take an extended period of
time to implement and thus would be unlikely to provide significant shon-term benefits. Construction
activities for any of the RAAs are not expected to result in any significant adverse impact to human
health or the environmenL
For these reasons, the selected alternative provides the best balance of trade-offs with respect to these
criteria. .
Preference for Treatment as a Principal Element
The selected remedy reduces toxicity and volume of contaminants in ground water, the principal threat
at the site, by allowing natural attenuation to occur. The contingenq action requires that the mobility
of site contaminants be reduced by containment methods or, alternately, requires that the volume of
contaminated media be reduced by treatment, such as use of activated carbon. The selected remedy
and contingenq utilize treatment as a principal elemenL
2.10
Documentation of Simificant Chan2es
The Proposed Plan for the Farmers Mutual Cooperative Company site was released for public
comment August 25, 1992. The Proposed Plan identified Remedial Action Alternative 2, Natural
Attenuation with a Drinking Water Contingenq as the preferred alternative. The Iowa DNR
reviewed all comments received during the public comment period. Upon review of these comments,
it was determined that no significant changes to the remedy, as it was identified in the Proposed Plan,
were necessary.
14
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Chemical
Carbon
Tetrachloride
Chloroform
Alachlor
(Lasso)
Atrazine
(Aatrex)
Cyanazine
(Bladex)
Metolacblor
(Dual)
Metribuzin
(Sencor)
TriOuralin
(TreOan)
TABLE 1
SUMMARY OF GROUNDWATER DATA
Hospers City Wells
Percent of
Percent of Samples
Samples Above
with Drinking
Number of Chemical Water
Samples Detected Standard
28 64% 54%
'1:i"".~'~~~.":::::'::':,:':'!:::':1:H'!"'i::.:;I:'1'.'::::::'!:':!:'::':.:":,:
(1)
Drinking
Water
Standard
(Ppb)
5
100
2
3
10
100
200
5
Average
Level in
Samples wI
Chemical
Detected
(Ppb)
22.0
Maximwn
Level
Detected
(Ppb)
66.0
':::::1:::19;9:'::.1.:::.::'.';:'::,:::::.::::::"::,,:::.:1!7fP:::::,::i:::::':::::i::::i::
1.4 4.0
NOTE: Unshaded Values: 1984 through Jan. 1988; City wells actively used.
Shaded Values: Nov. 1988 to present; City wells not in use.
(1) Drinking Water Standard refers to Federal MCL if one exists, or Ufetime Health Advisory if DOL
15
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Chemical
Carbon
Tetrachloride
Chlorororm
Alachlor
(Lasso)
Atrazine
(Aatrex)
Cyanazine
(Bladex)
Metolachlor
(Dual)
Metribuzin
(Senc:or)
Trif1uralin
(TreOan)
TABLE 1
SUMMARY OF GROUNDWATER DATA (ConL)
Monitoring weDs #1 . 4
Percent or
Percent or Samples
Samples Above
with Drinking
Number or Chemical Water
Samples Detected Standard
20 70% 55%
.::;::.:.::II.:::::.:.;.::;:;:;..:::.H::::.:.;::~li.i:::1.:::.::;:.:::::::.::.::.
60%
0%
(1)
Drinking
Water
Standard
(Ppb)
5
100
2
3
10
100
200
5
ppb = pans per billion
NOTE: Unsbaded vaJues: 1984 - Jan.I988; City wells actively used.
Shaded vaJues: Nov.l988 - 1990; City wells not in use.
:.::.:.$1I.::;.ii:::.:.;:;.:;:;i:.:il:::I::.:::::.::::QI:::1:..:1::.:..1;:..:::.;:.:::;;
Average
Level in
Samples wi
Chemical
Detected
(Ppb)
61.0
Maximum
Level
Detected
(Ppb)
250.0
11::.:;:::;~p:::::.:::::::I:::;.;:::::.::;:::
2.S 5.7
;:;::;:;:;:~?~9::;:.::.::::1.:::.:::!:.:.;;:;:::::;:1;g.\:::..!;:::::::.:.::;:::::;:;..
1.3 3.4
(1) Drinking Water Standard refers to Federal MCL if one exists or Ufetime HeaJth Advisory if nOL
16
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TABLE 1
SUMMARY OF GROUNDWATER DATA (Cont.)
Monitoring Wells #S - 31 and well-points #1 - 10
Percent oC Average
Percent oC Samples (1) Level in
Samples Above Drinking Samples wI Maximum
with Drinking Water Chemical Level
Number oC Chemical Water Standard Detected Detected
Chemical Samples Detected Standard (Ppb) (Ppb) (Ppb)
Carbon 37 19% 16% 5 120 25.0
Tetrachloride
ChIoroCorm 37 14% 0% 100 29.2 47.0
AIach10r 32 19% 3% 2 0.9 (2) 1.2 (2)
(Lasso)
Atrazine 32 75% 53% 3 5.8 (3) 17.0 (3)
(Aatrex)
Cyanazine 32 19% 3% 10 27 11.0
(Bladex)
Metolach1or 32 78% 9% 100 17.7 (3) 132 (3)
(Dual)
Metribuzin 32 19% 0% 200 26 11.0
(Sencor)
TriOuralin 16 0% 0% 5 - -
(TreOan)
NOTE: All data collected since Nov. 1988.
ppb = parts per billion
(1) Drinking Water Standard refers to Federal MCL if one exists, or Ufetime Health Advisory if noL
(2) Maximum level of Alachlor of 35 ppb in one sample excluded. (Sample believed to be in error.)
(3) Results from three samples collected in close proximity in the suspected herbicide hotspot area are not
included ~use results were significantly higher than other samples. Atrazine ranged from 25 ppb to 170
ppb and'DuaI ranged from 860 ppb to 18,000 ppb in these three samples.
17
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TABLE 2
SUMMARY OF SOIL DATA
NORMAL8 MAXIMUM 95% UCLb 95% UCLb
APPUCATION CONCENTRATION 0-2Ft. O-UFt.
COMPOUND RATE lMGIKG) lMGIKG) lMGIKG) lMGIKG)
Carbon
Tetrachloride - 0.013 0.0094 0.0082
Alachlor
(Lasso) 0.86 0.23 0.10 0.093
Atrazine
(Aauex) 0.60 10.0 1.04 0.67
CyanaZine
(Bladex) 0.96 2.6 0.29 0.23
Metolachlor
(Dual) 1.26 4.0 0.78 0.52
. Metn"buzin
(Sencor) 0.25 0.5 0.11 0.0096
Trifluralin
(Treflan) 0.90 56.0 3.55 2.17
a - Normal application rate calculated based on product label information, uniform mixing in a 6-inch soil
layer and a soil density of 114 Ib/ft3.
b - 95% UCL = the upper confidence limit of the average concentration which has a 95% degree of certainty.
18
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TABLE 3
SUMMARY OF SITE RISKS
NON- CAN-
EXPOSURE CANCER CER
POPULATION- MEDWM PATHWAY RISKb RISI{C
Off-Site Future Groundwater, Gty Well 3 Ingestion 0.2 5Xl()"5
Residents Dermal Contact-Shower 0.002 2X1O-1
Inhalation-Shower 5Xl«r'
Total Risk 0.2 5Xl()"5
Groundwater, Gty Well 9 Ingestion 2.0 lXl~
Dermal Contact-Shower 0.09 4Xlo-e
Inhalation-Shower lXl~
Total Risk 2.0 2Xl~
Groundwater, Gty Well 10 Ingestion 0.5 6Xl()"5
Dermal Contact-Shower 0.02 8XH)"1
Inhalation-Shower - 2XI0-5
-
Total Risk 0.5 8Xl()"5
Off-Site and Groundwater, During Pumping Ingestion 2.0 lXl~
On-Site Future (1984 - 1988) Dermal Contact-Shower 0.1 4Xlo-e
Residents Inhalation-Shower lXl~
Total Risk 2.0 2Xl~
Groundwater, During Ingestion 0.2 3Xl()"5
Non-Pumping (1988 - 1991) Dermal Contact-Shower 0.007 6X1()"1
Inhalation-Shower lXl()"5
Total Risk 0.2 4Xl()"5
On-Site Future Soil Incidental Ingestion 0.002 3X1()"1
Residents Dermal Contact 0.3 4Xl()"5
Total Risk 0.3 4XI0-5
On-Site Soil Incidental Ingestion 0.0004 5Xl«r'
Current Dermal Contact 0.2 2Xl()"5
Workers Total Risk 0.2 2Xl()"5
a - Current on-site populations are ronsidered to be adult employees working at or near the site. Future on-
site populations include potential residents living near the site. Future off-site populations include site
workers and other residents of the rommunity.
b - Non-cancer risks are shown as dimensionless values. Values less than 1 indicated that the risk on non-
carcinogenic injwy is lOW; above 1 indicates some degree of non-carcinogenic risk or roncem.
c - Cancer risk values represent an upper-bound estimate of additional cancers which rould result from lifetime
exposure of the population to site rontaminants by the medium shown. For example 2Xl~ means that
2 individuals in a population of 10,000 rould develop cancer as a result the assumed exposure. In the
Superfund evaluation of risk, a risk greater than lXl~ is considered to be unacceptable. A risk less than
lXlo-e (1 in a million) is preferred.
19
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FIGURE 1
LOCATION MAP
SOURCE: - U.S.G.S. TOPOGRAPHIC QUADRANGLE..
--- _.. - - - HOSPERS, SIOUX COUNTY, IOWA, .
SEC. 3,T. 95 N.. R. 43W.
°0
QUADRANGLE ~TlON
19
POOR QUALITY
ODII"IN" " i
r~a\.:iH J'\...
-------
SS.3 - Shallow Soli SAmple
S8.% - Soli Boriog
MW-4 - MODlwring Well
PW-9 - Public: Water Suppl)' WCU
GW-3 - GroUDdn&cr SAmple from
Temporat)' WCU Polut
f'W-IO 0
..aw..s
~
~
GW-2 .
:-~ $$-1
:;.-: S5-2
~: S5-~
\S-4
AREA D
orw-.
HOUSE --0
f'
MW.17 .
/j}{}
EXPLANATION
12;
. MW.7
I
------.lZ
I
. "/If,, lJaC,.,.rlOHS:
. .
rA.IiiA.A~- raTICIDE LOADING AREA
.ARE" .:- 8UJ1NNQ AREA
: "AU C:- $/'lIArER $TOllAGE AREA
:"AU 01- $/'ILL OR ltJHoFF AREA
:AAU f:- AAI~WAr LoA£W1II3 AREA
~...._4
0'
.
150'
.
20
F. ~
aD QUF\~\" <
pO~' .
...,~ \. ~
OD. \r:.,.....5'\;.>
,"h "" ~ II
r IbURE %
SI'IE MAP
-------
Gw-se(o.oou)
----------
G\\f-28 (0.0017)
. - ---..-- -..
Sampling Point. (Atrazine Concentration - mgJl)
Une or Equal Groundwater Elevation (arbitrary datum)
Area "ith AtnWne in Ground,,'3tu Above 0.003 mgJl
Which is the Drlnk..lnl; Wa~r Standard (MCL)
I
-'Z
I
0'
.
150'
,
FIGURE 3
MW-188 «0.001
ATRAZI~'E IN GROUNDWATER SEPTEMBER AND NOVEMBER 1990.
21
-------
...,
C5
~
,..
C)
~
~
tt1
o
tt1
~
o
...,
g
o
z
~
~
~ n
~
~
o
tt1
('")
o
~
Z
~
o
z .
...
!
~
~
~
~
')
.J
~
~
-------
RESPONSIVENESS SUMMARY
3.0
Comments from the Mav 1991 Public Meetinl!
A Proposed Plan for the Farmers Mutual Cooperative Company site was released for public comment on May
1, 1991. The Proposed Plan recommended a pump-and-treat groundwater alternative for containment of
groundwater contamination. A public meeting on the Proposed Plan was held on May 21, 1991, in Hospers,
Iowa. Questions from the May 21, 1991, public meeting are summarized below. .
1.
Question: Does the Record of Decision represent a point when no further input regarding the project
will be considered?
Response: No, the Record of Decision can be modified based on additional information.
2
Question: If allowed to rest would the aquifer ever dissipate the chemicals?
Response: Yes, assuming there are not additional releases of contaminants. In fact, evidence suggests
that significant dissipation of carbon tetrachloride has already occurred.
3.
Question: What is done with the carbon filter material when it is replaced and could this result in just
transferring the problem to someplace else?
4.
Response: The spent carbon can be incinerated or disposed of in an appropriate landfill. If
incinerated the contaminants would be destroyed. If landfilled, the landfill would be required to have
proper controls to prevent further problems.
Question: With more stringent c:lri.Dking water standards in the future, how long will the shallow wells
be useable and is the cost of the proposed remediation worth it?
Response: The proposed carbon treatment will remove many of the types of contaminants which will
likely be regulated in the future. Extensive testing of the groundwater from the shallow aquifer has
not revealed other contaminants other than those being addressed. Therefore, continued use of the
shallow aquifer in the future appears possible. In the Superfund evaluation of alternatives, costs are
only used for relative comparison of alternatives.
5.
Question: Does the aty have to use the shallow wells after the remedial action begun?
Response: No, the proposed action puts no requirements on the aty.
6.
Questio~: Who will pay for the cost of the proposed remedial action?
Response: The potentially responsible pany(ies) will be asked to conduct, and pay for; the proposed
action. If they refuse or are not able to, Superfund will finance 90% of the cost with the remaining
10% from the State in which case EP A can take cost recoveI)' action against the potentially
responsible party(ies) and recover up to three times the actual cost.
3.1 Written Comments on the 1991 Proposed Plan
Comment letters were received from the Farmers Cooperative Elevator Association (the Coop) and the City
of Hospers during the 1991 public comment period. The comment period was extended twice in response to
24
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requests from the City and the Coop. The comment letters received from the City and the Coop during the
1991 comment period are summarized below.
Comments from the Farmers Cooperative Elevator Association:
7.
Comment: Explain why RAA 2 (Continued Monitoring) does not comply with applicable or relevant
and appropriate requirements (ARARs). .
Response: At the time the 1991 Proposed Plan was released, the DNR considered the proposed pump-
and-treat action to be the best available technology for dealing with what was classified as a
.significant risk. under the state's rules (567 lAC 133). These rules call for use of best available
technology and best management practices to cleanup groundwater in cases of a significant risk. A
.significant risk. is defined as the presence of a contaminant in groundwater above an action level
which clearly existed at the site. It was also believed at that time that the proposed pump-and-treat
action was the best technology available to enable the City to regain use of their shallow wells and
was action which could reasonably be accomplished. In light of the fact that groundwater had
previously been used for a municipal water supply and would likely still be used for a water supply
if not for the site contamination, the federal drinking water Maximum Contaminant Levels (MCLs)
were deemed to be applicable. MCLs are federal health-based drinking water standards. RAA 2
simply would not meet MCLs in the near future to facilitate use of the impacted aquifer as a water
supply and therefore did not comply with ARARs.
8.
Comment: Explain how RAA 3 would have greater short-term and long-term effectiveness than RAA
2
Response: RAA 3 was considered to have greater short-term effectiveness because it enabled the City
to regain use of their shallow wells within a relatively short period of time while RAA 2 did nOL It
bas since been recognized that RAAs 2 and 3 have comparable long-term effectiveness.
9.
Comment: Explain how the costs of the various remedial action alternatives were weighed in the
process of proposing a remedy in light of a comment at the public meeting that a cost-benefit analysis
is not used to determine if a cleanup action is needed.
Response: Relative costs are used as a factor in selection of a remedy from those alternatives which
meet the threshold criteria of overall protection of human health and the environment and compliance
with ARARs.
Comment: The Coop agrees in principal with the City of Hospers to work with the City to locate
additional water supplies for the City if the pump-and-treat alternative is not selected.
Comments from the City of Hospers on the 1991 Proposed Plan are summarized below:
10. .
11.
Comment: The proposed pump-and-treat alternative would be expensive and would have an adverse
economic effect on the City as well as the Coop. .
12
Comment: The additional water supply the City would receive upon implementation of the pump-and-
treat alternative would satisfy only a minority of the City's needs with the City still relying on the high
iron and sulfate deep well water.
13.
Comment: The City is the only user of the impacted aquifer.
2S
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14.
Comment: The City agrees in principal with the Coop to work together to find an alternate, more
usable source of water for the City, if the Coop is not required to implement the proposed pump-and-
treat alternative.
3.2 Decision on the 1991 Proposed Plan
In response to the City of Hospers general lack of suppon for the proposed pump-and-treat alternative and
preference to work with the Coop to find another water supply, the decision was made to delay the Rea>rd
of Decision until after the additional investigations, which were also proposed in the 1991 Proposed Plan. were
completed. With the CitfOs apparent lack of interest in regaining use of the shallow aquifer. the immediacy
of site remediation no longer existed. It was deemed prudent to consider information from the proposed
additional investigations before making a final decision. Also. based on comments received, another
alternative involving an alternate water supply for the City appeared to be a possibility which needed further
study. .
3.3 Development of the AUlroSt 1992 Proposed Plan
Another Proposed Plan was released in August 1992. This Proposed Plan incorporated the results of the
additional investigations which had been recommended in the 1991 Proposed Plan. Major findings and
significant changes since the 1991 Proposed Plan was released are summarized below:
. Additional evidence of substantial declines of carbon tetrachloride levels in groundwater was obtained.
. A significant source of herbicide contamination of soils was not identified despite substantial efforts to
locate such a source for potential source control actions.
. The Coop removed all bulk chemical handling facilities from the Hospers facility in the summer of 1992-
. The City and the Coop were not able to find a mutually agreeable, alternate water supply for the City.
A new Proposed Plan was prepared incorporating the new information and was released in August of 1992-
The proposed remedy includes natural attenuation and monitoring of groundwater with a contingency should
the City of Hospers (or others) desire to use the impacted aquifer for water supply. This contingency would
provide a blending program for the City of Hospers similar to what the City previously had. Additional action
would be required if a satisfactory blending program is not possible.
3.4 Comments from the September 3. 1992. Public ~eetinl!
A public meeting on the August 1992 Proposed Plan was held on September 3. 1992, in Hospers with about
SO people attending. The following is a summary of the comments and questions which were received at the
September 3, 1992, public meeting:
15.
Question: Could the landfill affect the groundwater in the area? (Note: a former open dump is
located about a half mile north of the site and an operating sanitary landfill is located about three
miles north of the site.)
Response: It is highly unlikely that the landfill(s) could affect the site. Groundwater flow from the
landfills would typically be to the Floyd River. There are monitoring wells on the north side of the
site which do not show contamination.
16.
Question: Is the City tied to this Superfund decision?
26
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20.
21.
22.
Response: No, the Superfund decision makes no requirements of the City. The proposed aCtion does
provide the City with the option of regaining use of the shallow wells similar to before DNR
restrictions, if the City so chooses.
17.
Question: Have the City and the Coop cooperated with the DNR and EP A on this project and have
they spent a lot of money for which they will not be reimbursed?
Response: The City and the Coop have been very rooperative. The COOp has been the only
potentially responsible party involved in the project and bas incurred significant costs for
investigations and related work which will not be reimbursed.
18.
Question: Has action been required which wasn't necessary?
Response: In retrospect on a project of this magnitude some things certainly would have been done
differently. However, overall there bas been a logical progression of what bas been done and most
of the information which has been collected has been useful
19.
Question: Can Superfund aCtion include provisions for alternate water sources?
Response: Superfund response aCtions have at times included provisions for alternate water supplies.
The decision as to whether an alternate supply of water is provided or the contaminated aquifer is
restored for future use depends on a number of factors, including:
. the degree, extent and types of contaminants in the aquifer;
. the technical feasibility of treating those contaminants to health-based levels or of containing
those contaminants so as not to contaminate the water supply;
. the current availability of other water supply sources; and
. the relative costs of providing an alternate supply versus treating the contaminated water.
Contaminant levels at the site have declined in recent years and are expected to continue to do so due
to on-going natural processes and because activities at the Coop which likely contnDuted to
groundwater contamination have been discontinued. Agricultural chemicals such as the ones found
at the site are readily treated by proven methods. An alternate water supply which could be
developed less expensively than restoring the impacted aquifer has not been identified. For these
reasons, restoration of the impacted aquifer is the preferred remedial action.
Qu~tion: How long will it take for the aquifer to clean itself?
Response: Accurate prediCtion of the time for natural attenuation to reduce contaminant levels below
drinking water standards is not possible since the source(s) of contaminants has not been pinpointed.
Comment: The current deep well water may be considered safe and acceptable from a regulatory
standpoint, but it not considered to be a good quality water by the community.
Question: Is the site still contaminated and who makes that determination?
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24.
Response: Using the federal MCU as a criterion for rontamination, groundwater at the site likely
remains rontaminated. This determination will be made by DNR and EP A based on rompliance with
M~ .
23.
Question: If Superfund money is used, rould rerovery of these rosts place such a burden on a business
as to put it out-of-business?
Response: In rost recovel}' actions, EP A goes through a fairly rigorous process to determine how
much debt the PRP can assume and how payments rould be arranged.
Question: Is the City of Hospers or the Coop responsible for cleanup of the rontamination?
Response: Potentially responsible parties (pRPs) are responsible for Superfund site cleanups. For this
site, the Coop is the only PRP which has been named to date.
25.
Question: Why would you spend all of this money and decide not to do a cleanup?
Response: It was hoped that a source(s) of rontamination rould be identified which rould be directly
dealt with. However, after extensive investigations no such source has been identified and the decision
was made that enough investigation had been done and it was time to decide what to do with the site
based on available data. The proposed remedy involving natural attenuation was determined to be
the best overall means of remediation identified. Also, the proposed remedy may involve actions
which would more rommonly be perceived as .cleanup. as part of the rontingency.
26.
Question: Was DNR premature in shutting down the city's shallow wells, forcing the City to use high-
sulfate water?
Response: The DNR shut down the shallow wells because of rontamination in the wells which rould
have caused violations of drinking water MCLs. Sulfate, on the other hand, does not have a primary,
health-based MCL. Sulfate does have a serondary MCL, based on aesthetics, which is not enforceable.
27.
Question: Are there any sites romparable to this site which have cleaned themselves up?
Response: There are not any romparable sites in Iowa which have any more information than this site.
However, there is evidence of declining nitrate rontamination in groundwater, particularly when it has
be the result of a major spill of fertilizer.
28.
Question: Is there any reason to believe that the source of Atrazine rontamination is unknown? If
you can't find the source, can you determine wh9 is responsible for the rontamination?
ReSponse: The zone of Atrazine rontamination of groundwater has been well defined and the general
direction of groundwater flow has been established. With this information it is clear that the Coop
is a source of the rontamination, although the specific source areas on Coop property have not been
identified.
29.
Question: If carbon tetrachloride was easy to get rid of, why can't an inexpensive aeration process be
used?
Response: Aeration was ronsidered in the Feasibility Study, but aeration does not remove herbicides
whereas, carbon filtration would remove the herbicides and carbon tetrachloride and was thus deemed
more eronomical.
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30.
Question: Why weren't the wells tested for these chemicals when they were installed in 1981?
Response: That was not common practice at the time.
31.
Question: In general. do many shallow wells have acceptable quality water?
Response: Yes. most do have good quality water.
32.
Question: Why was Hospers selected for the initial well sampling which identified the problems?
Response: Hospers was one of S8 communities which were selected for sampling based on likelihood
of contamination. Proximity to the Coop and elevated nitrate levels were factors used in selection
of susceptible water supplies.
33.
Question: Why wasn't nitrate contamination evaluated as part of the Superfund effon?
Response: Nitrate in groundwater was considered to be a fairly common and naturally-occurring
contaminanL There was not the concern for nitrate that there was for the synthetic organic
compounds. This is not meant to suggest that nitrate is not importanL
34.
Question: Since Superfund is funded by a tax on the petrochemical industry and the contamination
is the result of the petrochemical industry's products. why can't Superfund money be used (without
cost recovery) or the manufacturer be made liable for the solution to the contamination?
Response: The Superfund program is not set up that way. Superfund law places liability on those who
are responsible for the release of contaminants.
3.6 Written Comments on the 1992 Proposed Plan
In addition to the comments received at the public meeting. comment letters were received the City of
Hospers. the Farmers Cooperative Elevator Association, and one private party. The City's comments are
summarized below.
35.
Comment: The City is concerned about the use of the shallow wells and wants to be sure that
adequate testing of the shallow wells is conducted prior to their return to service. and they want to
be sure that they are not responsible for the cost of this testing.
Response: The Proposed Plan calls for .development and implementation of a blending program for
the City of Haspers, including test pumping and sampling of shallow wells prior to their use.. The
in~e~t is to have a testing plan which addresses the types of concerns .expressed by the City. The
itemized provisions regarding .the testing which were submitted by the City will be considered in
development of this plan. However; if the City desires action beyond what is required by the DNR
and EP A, such action would be at the City's expense.
36.
Comment: The City commented that they opposed a Record of Decision before testing the shallow
wells.
Response: The outcome of the testing should have no bearing on the selected alternative. Therefore.
a delay of the Record of Decision is not necessary. The intent of the testing is not to show if use of
the shallow wells is feasible; rather. it is to show bow they can be effectively utilized at lowest COSL
The selected alternative has contingency measures built-in to cover any possible outcome of the
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testing with respect to site cx>ntamina11ts. The proposed cx>ntingency action is intended to enable the
City to regain use the shallow wells, cx>mparable to their use prior to restrictions by the State, until
such time as the levels of cx>ntaminants associated with the site are reduced to below drinking water'
standards by natural attenuation. H blending with half deep well water and half shallow well water
does not result in acceptable levels of the site cx>ntaminants, then additional action (e.g.treatment) .
will be taken to reduce levels of the site cx>ntaminants so that acceptable blending is . possible. Any
additional action will Dot place additional CX>St requirements on the City.
The following is a summary of cx>mments received from the Coop:
37.
38.
39.
40.
41.
Comment: The Coop generally supports the selection of RAA 2 calling for natural attenuation with
the drinking water cx>ntingency.
Comment: With respect to the cx>ntingency, the Coop does not feel that the Reex>rd of Decision
should: attempt to specify the elements of a blending program.
Response: There is no intent to specify the elements of the blending program other than to establish
a criterion for determining when additional action (beyond blending) may be required. In this respect,
the objective of a blending approach would be to provide a water supply to the City which is
cx>mparable to what the City had before the shallow wells were restricted by the DNR. H a blending
program is developed which is acceptable to the DNR and EP A, then no additional cx>ntingency action
(beyond blending) will be required. H not, then additional cx>ntingency action would be required (i.e.,
treatment or containment). In any event, if blending equal portions of shallow and deep well waters
yields water which meets MCLs for site contaminants, then no additional cx>ntingency action beyond
blending will be required.
Comment: The Coop does not believe that testing is necessary prior to issuance of the Reex>rd of .
Decision.
Comment: The Coop feels that cx>sts for certain actions suggested by City should not be the
responsibility of the Coop. .
Response: This is an issue which will be addressed after the ROD is issued. The DNR and EPA will
determine which CX>Sts are appropriate.
Comment: The Coop Should not be required to initiate a blending program until the City has
requested one.
Response: There will be no requirement for a blending program until the City formally requests one.
The following is' a summary of the pertinent comments from the letter received fro~ the private party.
42
43.
Comment: The least expensive alternative was endorsed.
al ~ .
Comment: Relatively high levels of nitrates are a natural and norm occurrence m shallow
groundwater in Northwest Iowa.
~
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