PB99-964301
EPA541-R99-029
1999
EPA Superfund
Record of Decision:
Ogallala Ground Water
Contamination Site OU 1
Ogallala, NE
4/23/1999
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RECORD OF DECISION
DECLARATION
SITE NAME AND LOCATION
Ogallala Ground Water Contamination Site
Operable Unit #01
Keith County Nebraska
Ogallala, Nebraska
CERCLIS Identification Number NED986369247
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedy for Operable Unit #01 of the Ogallala
Ground Water Contamination Site located in Ogallala, Nebraska. 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 Re-authorization Act of
1986 (SARA), 42 U.S.C. § 9601 et seq.. and. to the extent practicable, the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP), 40 C.F.R. Part 300. This decision is
based on the Administrative Record for this site.
The state of Nebraska concurs with the selected remedy for this site.
ASSESSMENT OF THE SITE
The response action selected in this Record of Decision (ROD) is necessary to protect the public
health or welfare or the environment from actual or threatened releases of hazardous substances
into the environment.
DESCRIPTION OF THE SELECTED REMEDY
This ROD addresses Operable Unit #01 (OU1) which involves several separate areas of ground
water contamination in the city of Ogallala. OU1 includes a plume of tetrachloroethylene (PCE)
and trichloroethylene (TCE), located in the western portion of the site, in the Alluvial formation
of the Ogallala aquifer and a second plume characterized by carbon tetrachloride (CT) and TCE
contamination, located in the center of the site and present in the upper Ogallala formation. A
third plume, located in the northeastern portion of the site, characterized by PCE contamination
in the Alluvial formation will not be considered part of OU1. This PCE plume (known as the
east-PCE plume) is undergoing a treatability study for which the United States Environmental
Protection Agency (EPA) will issue a separate ROD, based upon the results of this study.
The OU1 ground water remedy was developed to protect public health, welfare and the
environment by controlling the migration and reducing the volume and mass of contaminants
present in the ground water beneath and downgradient from each source area. These actions will
be consistent with any future remedial activities.
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The major components of the selected remedy for OU1 include:
• The continued operation of the ground water extraction and air treatment system,
including the associated ground water monitoring, located at and near the
American Shizuki Corporation (ASC) facility, until verified contaminant levels
have been attained consistent with this ROD, or until contaminant levels have
been reduced to maximum contaminant levels (MCLs) and EPA, in consultation
with Nebraska Department of Environmental Quality (NDEQ), has determined
that this response action is complete.
• Restoration of the Ogallala aquifer through natural attenuation.
• Implementation of an institutional control in the form of a city of Ogallala
ordinance and deed notices/restrictions on selected property which will control the
use of the ground water for human consumption in areas where contamination is
present above the (MCLs).
• An inventory of all existing ground water wells to identify all domestic, irrigation,
industrial and monitoring wells in the city of Ogallala and east of Ogallala
impacted or potentially impacted by the contaminated ground water. The
inventory will identify users of existing wells who are potentially at risk and
identify wells that may be used in developing the ground water monitoring
program.
• Providing an alternate source of water for domestic use to any residences
currently relying on private wells impacted or potentially impacted by the
presence of contamination within OU1. These activities may include offering
hook-up to the city's public water supply system, bottled water and/or an in-house
treatment system for the well water.
• A ground water monitoring program which will include periodic ground water
sampling of selected wells identified in the areas of contamination and
downgradient from the contamination zones. The installation of additional
monitoring wells may be required as part of the ground water monitoring system.
The monitoring program will be designed to identify potential source areas and
the extent of the plumes, and to collect sufficient data to confirm that natural
attenuation processes are occurring at a rate which is sufficient to restore the
ground water to all beneficial uses within a reasonable time frame.
• Preparation of a report for OU1, based on eight quarters of ground water
monitoring data that will evaluate whether natural attenuation is occurring at a
rate sufficient to restore the aquifer for beneficial use within an acceptable time
frame, not to exceed 20 years. This 20 year time frame is supported by the state
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of Nebraska Title 118, Appendix A. If EPA determines natural attenuation will
not restore the aquifer within 20 years, additional response activities will be
required that would achieve restoration of the aquifer in the 20 year time frame.
In addition to the above response actions, additional actions may be necessary to address
significant contaminant source areas if any are identified during implementation of the ground
water monitoring program. Such actions will be required to address soil source areas and reduce
levels of contaminants in ground water to levels that will allow natural attenuation to succeed.
Generally, these action levels will equal a risk of one cancer occurrence in 10,000 or 10"4
carcinogenic risk.
The operation of the remediation system at the ASC facility provides containment and mass
removal of the contamination present in the western portion of the site. An effective city of
Ogallala ordinance and deed notices/restrictions on selected property will control the use of
ground water for human consumption in areas where contamination is present above MCLs An
inventory of all wells within the city of Ogallala and downgradient from the plume areas will
enable EPA to determine the potential threat. Quarterly sampling of selected residential and
monitoring wells will enable EPA to determine if any additional source areas are present and
whether there is ongoing exposure to the contamination in the ground water. Based upon current
information, EPA and NDEQ believe a principal threat is currently being addressed by the
ongoing action at the ASC facility. Sampling data will be collected and evaluated to determine
the remediation rate of the existing natural attenuation processes. Areas of significant
contamination discovered during the ground water monitoring activities will be addressed in an
appropriate manner.
STATUTORY DETERMINATIONS
The selected remedy for OU1 is protective of public health, welfare and the environment
complies with federal and state of Nebraska requirements that are applicable or relevant and
appropriate to the selected remedy, is cost-effective and utilizes permanent solutions and
alternate treatment (or resource recovery) to the maximum extent practicable for this operable
unit.
Based upon the ongoing response action being conducted at the site, the past response actions
that have limited exposure to the contaminants at the site, the presence of natural attenuation
processes, and the current levels of contamination at the site, EPA has concluded that it is
unnecessary to remove and treat all of the contaminated ground water. The remedy selected for
OU1 partially satisfies the statutory preference for treatment as a principal element of the remedy
via the continuation of the ASC system. If additional response actions are determined to be
necessary for OU1, the statutory preference for treatment will again be considered and may lead
to additional response action.
Because the selected remedy for OU1 will result in hazardous substances remaining on-site
above health-based levels that allow for unlimited use and unrestricted exposure, a review will be
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conducted within five years after commencement of the remedial action, and at a minimum of
every five years thereafter as long as contamination is present above levels which prevent
unrestricted use of this operable unit, to ensure that the remedy continues to provide adequate
protection of human health and the environment. Review of the effectiveness of the response
actions is part of the selected remedy.
ROD DATA CERTIFICATION CHECKLIST
The following information is included in the Decision Summary Section of this ROD.
Additional information can be found in the Administrative Record file for this site:
• Chemicals of Concern: CT, maximum detection of 50 micrograms per liter (ug/1); PCE,
maximum detection of 1,400 ug/1; TCE maximum detection of 1,164 ug/1; vinyl chloride
(VC), maximum detection of 1.3 ug/1; and 1,1-dichloroethylene (1,1-DCE), maximum
detection of 6.5 ug/1.
• Baseline risk represented by the chemicals of concern at the Ogallala site are based upon
the concentrations of contaminants in two monitoring wells. For monitoring well NW-
1 A, TCE was present in monitoring well NW-IA and the adult reasonable maximum
exposure (RME) risk was calculated to be 1.2 X 10 '4. For monitoring well NW-2B, TCE
and CT were both present. The risk associated with the use of.ground water from this
well exceeds the RME for both the child at 1.5 X10"4 and the adult at 3.1 X 10 "4.
• Cleanup levels established for the chemicals of concern are the MCLs. They are: CT,
5 ug/1; PCE, 5 ug/1; TCE, 5 ug/1; VC, 2 ug/1; and 1,1-DCE, 7 ug/1.
• Current and future land and ground water use assumptions used in the baseline risk
assessment include the use of the ground water as drinking water.
• This remedy allows for an inventory of ground water wells within Ogallala, identifies
usage of this water and seeks to prevent the consumption of this water until the ground
water is restored to MCLs for each chemical of concern. The ultimate goal for this
remedy is to restore the ground water to drinking water quality which allows for its
unrestricted use.
• The estimated costs for selected remedy are as follows: capital costs, $313,607; and
operation and maintenance costs, $1,491,953 for a period of up to 28 years, which equals
a total present worth cost of $1,805,623 calculated with a five percent discount rate.
• The selected remedy for OU1 provides for institutional controls in the form of an
Ogallala city ordinance and deed notices/restrictions on selected property which will
control the use of ground water for human consumption in areas where contamination is
present above MCLs. Quarterly ground water sampling will monitor remediation
progress. The EPA believes the selected remedy provides the best balance of trade offs
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Date
with respect to the balancing and modifying criteria. The selected remedy will develop
information necessary to confirm that existing natural attenuation processes will
remediate the contaminated ground water within an acceptable time frame. The
contaminated ground water is not currently being used by the city for distribution to the
public. The city has installed a new water supply well field. This remedy includes
provisions for evaluating any changes in the contaminant concentrations or movement,
including any reductions in toxicity, mobility or volume due to natural processes.
' / ~7 . -by Deprils Grams, P.E.
'/ Regional Administrator
Region VII
Attachments: Decision Summary
Responsiveness Summary - Attachment
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RECORD OF DECISION
DECISION SUMMARY
OGALLALA GROUND WATER CONTAMINATION SITE
OGALLALA, NEBRASKA
Prepared by:
U.S. Environmental Protection Agency
Region VII
Kansas City, Kansas
April 23,1999
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Record of Decision
Decision Summary
Contents
Section Page
I. Site Name, Location and Brief Description 1
II. Site History and Enforcement Activities 2
III. Community Participation 5
IV. Scope and Role of Operable Unit 5
V. Site Characteristics 7
VI. Current and Potential Future Site and Resource Uses 9
VII. Summary of Site Risks 10
VIII. Remediation Objectives 15
IX. Description of Alternatives ... . 16
X. Comparative Analysis of Alternatives 23
XL Selected Remedy 35
XII. Statutory Determinations 39
XIII. Documentation of Significant Changes 43
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Record of Decision
Decision Summary
Contents
List of Tables:
1. Municipal well data, 1989-1995, 2 pages
2. Chemicals of concern from municipal wells
3. Monitoring well data, October 1991 -November 1993, 2 pages
4. Monitoring well data, October 1995
5. ASC and OE data, October 1991 -November 1993
6. ASC and OE data, October 1995, 2 pages
7. Subsurface soil data, October 1995, 2 pages
8. Subsurface soils chemicals of concern, 2 pages
9. Chemicals of concern for sediment
10. Chemicals of concern for Nebraska monitoring wells
11. Chemicals of concern for EPA monitoring wells
12. Chemicals of concern for PRPs monitoring wells
13. Chemicals of concern for Nebraska monitoring wells, October 1991-November 1993
14. Chemicals of concern for PRP installed wells, October 1991-November 1993
15. Chemicals of concern for surface water, October 1995
16. Concentrations of Ogallala site contaminants, 3 pages
17. Carcinogenic risks
18. Noncarcinogenic hazard indices
19. Ground water remedial action objectives
20. Appendix E, Ogallala well inventory, 7 pages
21. OEMI's 1998 data
22. Feasibility Study's Tables, 12 pages
23. Tables for Evaluating Natural Attenuation of Chlorinated Solvents, 2 pages
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Record of Decision
Decision Summary
Contents
List of Figures:
1. Area location map
2. Topographic map
3. Location of former municipal supply wells
4. Location of new municipal supply well field
5. Potential source areas
6. Location of Nebraska's monitoring wells
7. Locations investigated by soil-gas, 1990
8. TCE Plume, 10'depth
9. PCE Plume, 10'depth
10. Monitoring well locations prior to EPA's RI
11. Ground water levels in Alluvial formation, 1996
12. Ground water levels in upper Ogallala formation, 1996
13. Ground water levels in lower Ogallala formation, 1996
14. TCE in Alluvial formation, 2 pages
15. TCE in Ogallala formation, 2 pages
16. PCE in Alluvial formation, 2 pages
17. CT in Ogallala formation, 2 pages
18. ASC's remediation efforts
19. OEMFs site plan and 1998 data
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DECISION SUMMARY
OGALLALA GROUND WATER CONTAMINATION SITE
I- SITE NAME. LOCATION AND DESCRIPTION
The Ogallala Ground Water Contamination Site (CERCLIS # NED986369247) is located
in western Nebraska (Figure 1) within and east of the city of Ogallala. Nebraska. The city of
Ogallala has an estimated population of 5,100. Ground water flow is to the southeast (see
Figures 11,12 and 13). Ogallala lies just to the north of the South Platte River (Figure 2).
The Ogallala Ground Water Contamination Site consists of an aquifer contaminated with
industrial chemicals, primarily chlorinated volatile organics. Contamination was discovered in
1989 when the Nebraska Department of Health (NDOH) sampled the Ogallala public water
supply system during routine sampling. Subsequent sampling of the municipal water supply
detected contamination exceeding maximum contaminant levels (MCLs) in seven of the town's
nine water supply wells (data in Table 1, Figure 3, municipal supply wells 64-4 and 64-5 did not
exceed MCLs). Due to the detection of contamination within the municipal supply wells, all
wells within city limits were put on emergency status (use is restricted to fire protection and
natural or manmade disasters). In 1990, ground water samples were collected from 16 private
wells and volatile organic compounds (VOCs) were detected in four of these wells. The uses
reported for these 16 private wells included drinking, irrigation and heating/cooling purposes.
Three of the wells (Gayle, Ruzanic and Welsh) are used for irrigation only. The Peterson well
was a drinking water well. None of the contamination present exceeded MCLs when tested. The
resident with a contaminated drinking water well was offered hookup to an uncontaminated city
water supply. The far right column of Table 2 lists the chemicals of concern which were present
in the municipal wells (benzene, chloromethane, 1,1-dichloroethylene, tetrachloroethylene and
trichloroethylene). Under a state of Nebraska Administrative Order, the city of Ogallala installed
a new well field in 1993, located to the northeast of the City (Figure 4). Depth to ground water at
the site ranges from the surface to 30 feet deep. Depths to ground water in the municipal supply
wells prior to decommissioning ranged from 10-35 feet below land surface (bis).
The site geology is generally characterized by formation outcrops of Tertiary age and
younger. Sediments underlying surficial soils generally consist of Quaternary alluvial and eolian
deposits. The alluvial deposits consist of a heterogeneous mixture of unconsolidated gravel, sand,
silt and clay confined to the North Platte and South Platte River valleys and tributaries. The
thickness of the alluvial deposits in the South Platte River Valley ranges from 27 to 70 feet.
Ground water primarily flows in one aquifer, the High Plains aquifer, which can generally be
divided into three units: the Alluvial formation, the upper Ogallala formation and the lower
Ogallala formation. The flow of ground water in these units is interrelated because major
geologic barriers to flow do not exist between the units. The direction of flow appears to be the
same in all units and generally there are only small vertical differences in water levels between
them, as shown in Figures 11,12 and 13.
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II. SITE HISTORY AND ENFORCEMENT ACTIVITIES
In 1990, NDEQ conducted a soil-gas investigation to determine sources for the ground
water contamination. Based upon current or past usage of cleaning solvents and/or proximity to
known areas of ground water contamination, samples were collected and analyzed from the
facilities identified in Figure 5. Based upon this analytical data, it was determined that the
sources of the ground water contamination were located at or near the following facilities:
American Shizuki Corporation (ASC), Helmuth Cleaners, Ogallala Electronics and
Manufacturing Inc. (OEMI), the former TRW/Goodall Facility and Tip Top Cleaners. The
contamination present at the Tip Top Cleaners is referred to as the "east-PCE" plume and will be
addressed in a separate operable unit ROD. The soil-gas sampling locations are shown in Figure
7. Figure 8 shows the potential source areas for trichloroethylene (TCE) and Figure 9 shows
potential source areas for tetrachloroethylene (PCE). The soil-gas investigation also identified
several areas which were contaminated with petroleum hydrocarbons. These areas are being
addressed under the Nebraska Leaking Underground Storage Tanks (LUST) program. The soil-
gas samples were not analyzed for carbon tetrachloride, therefore the source(s) of the carbon
tetrachloride in the upper Ogallala formation is undetermined.
In 1991, NDEQ installed six monitoring wells in four locations to characterize the
contamination plumes (Table 3 data from October 1991-1993, Figure 6- locations). The NDEQ
requested that three facilities participate in ground water investigations for the site. These three
facilities were ASC (prior to the purchase of the facility by ASC , the owner was TRW), OEMI
and Good-All Electric. The ASC facility is located at 301 West Street in the western part of
Ogallala. The OEMI facility is located at 601 West 1st Street in western Ogallala. The Good-All
Electric facility was located in the south central part of Ogallala at 201 South Spruce Street.
In 1991, ASC submitted an investigation plan developed by their contractor to NDEQ. In
February 1993, ACS installed three additional monitoring wells into the shallow aquifer and one
additional monitoring well into the deep aquifer (Figure 10, wells shown on left, identified with
"ASC"-prefix). The newly installed wells initially showed concentrations of TCE, 1,1,1-
trichloroethane (TCA), PCE, l,2-dichloroethene(l,2-DCE), and l,l-dichloroethane(l,l-DCA).
ASC implemented a voluntary cleanup action in 1994 with the installation and operation of a
ground water extraction and treatment system (Figure 18). Based upon current information, this
system appears to be containing the contaminants released from the ASC site. A summary of the
ASC site data is presented in Tables 5 and 6 under the ASC heading. This data was collected by
ASC and presented to NDEQ and was used by Nebraska Health and Human Services System
(NHHSS), formerly known as the Nebraska Department of Health, in evaluating site risks.
The OEMI investigation was conducted by their contractor and consisted of the drilling
and installation of 10 alluvial monitoring wells on and around the property (Figure 19). Several
VOCs have been identified in the ground water adjacent to and downgradient from the site.
OEMI formerly used TCE as a degreaser solvent. OEMI currently uses 1,1,1 -TCA. OEMI
installed additional monitoring wells and submitted information during the public comment
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period on the Proposed Plan from the sampling conducted at their facility. This data showed
elevated levels of TCE in monitoring well MW-7B, located downgradient from their facility.
Table 21 contains 1998 data collected by OEMI from the monitoring wells adjacent to and
downgradient from their facility and shows that .monitoring well MW-7B contained TCE at 2100
ug/1. This well is an alluvial well with a depth of approximately 30 feet bis. (below land
surface).
The Good-All Electric investigation conducted by their contractor included the
installation of four monitoring wells into the alluvial aquifer and the drilling of six soil borings
on the facility property. This investigation was conducted in March 1991. Water samples
collected in 1991 did not contain VOCs above MCLs. PCE, TCE and 1,1,1-TCA were detected
in the soil samples.
In 1993, the NDEQ initiated site-wide discussions with ASC and OEMI to get them to
conduct a site-wide Remedial Investigation/Feasibility Study (RI/FS). These negotiations were
unsuccessful and the site was referred to EPA in June 1994. The site was finalized on the
National Priorities List on December 16, 1994.
Through EPA's ground water investigations in 1995-96, EPA identified VOCs, CT, PCE,
TCE, 1,2-DCE, VC, and the semi-volatile organic compound bis (2-ethyIhexyl) phthalate as
contaminants of concern in the ground water. The RI describes the CT, PCE and TCE as the
only non-fuel organic contaminants that exceeded the MCLs in the ground water samples and
describes the site-wide distribution of these plumes. Contamination was detected in both the
Alluvial and the Ogallala formations. Contamination in the Alluvial formation was detected in
wells with screening intervals between 4 and 30 feet. Contamination in the Ogallala formation
was detected in wells with screening intervals between 70 and 118 feet. The highest
concentration of TCE was 290 ug/1 in 1995 and 220 ug/1 in 1996 and was present in monitoring
well NW-2B, a monitoring well installed by NDEQ in the Ogallala formation. TCE was present
above MCLs in both the Alluvial and Ogallala formations. PCE was detected only in the
Alluvial formation at a maximum concentration of 470 ug/1 in 1995 and 1400 ug/1 in 1996.
These values were found in monitoring well NW-4, a monitoring well installed by NDEQ in the
Alluvial formation. These maximum levels were present in the area of the east-PCE plume.
PCE, at concentrations which are less than those found at monitoring well NW-4, is commingled
with TCE in the west-PCE plume. CT was detected in the Ogallala formation with a maximum
concentration of 50 ug/1 in 1995 in monitoring well EPA-9B, installed by EPA, and 30 ug/1 in
1996 in monitoring well NW-2B, a monitoring well installed by NDEQ. The area of theVcE
and PCE contaminant plumes is large, covering the southern portion of the city of Ogallala.
Plume maps for the contaminants were developed during the RI and are attached as Figures 14,
15, 16 and 17. The MCL for TCE, PCE and CT are 5 ug/1 for each contaminant. The MCL for
1,2-DCA is 7 ug/1. The MCL for VC is 2 ug/1.
The EPA has determined that response actions are needed to address the contamination at
the Ogallala Ground Water Contamination Site where the contaminants exceed the MCLs. The
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selected remedy for OU1 will control the use of the ground water, preventing the ingestion or
inhalation of vapors during its usage. Ground water monitoring will enable EPA, in consultation
with NDEQ, to determine if natural attenuation processes are present at a rate sufficient to
prevent the further expansion of these plumes. An evaluation of the ground water data will
enable EPA to determine if these actions are protective of human health and the environment and
will result in the restoration of this ground water for beneficial use within an acceptable time
frame.
The ground water data indicates that site contamination has migrated and may continue to
migrate to the ground water beneath and downgradient of the site. Data results are presented in
the RI Report which was released on October 1, 1996. The FS reports, based on the RI Report,
were released on February 28, 1997. A Proposed Plan for Remedial Action (Proposed Plan),
explaining the preferred alternative to mitigate the contamination at the site, was released in May
1998. The EPA held a public comment period held from May 9 to August 23, 1998, to receive
comments from any interested party on the Proposed Plan and other site documents contained in
the Administrative Record. The EPA has prepared a responsiveness summary which addresses
the significant comments received during the public comment period (Attachment A).
Potentially Responsible Parties (PRPs) are those individuals or corporations liable under
CERCLA for the costs incurred by the EPA in responding to a release or threat of release of a
hazardous substance from a facility.1 The EPA conducted an investigation for the purpose of
identifying parties who may be liable under CERCLA/SARA for the Ogallala contaminated
ground water. The EPA identified several businesses that used chlorinated solvents as degreasers
and for dry cleaning. The EPA also identified the Tip Top Cleaners facility as the probable
source of PCE contamination in the Alluvial formation; referred to as the east-PCE plume. This
determination was based upon site information which indicated that no PCE was found
upgradient of the facility, and that soil samples as well as the ground water downgradient of the
Tip Top facility contained PCE. The NDEQ is currently conducting a treatability study using an
innovative technology (reductive dechlorination) at the Tip Top facility. The EPA, in
consultation with NDEQ, will address the actions required to remediate this plume in a separate
ROD based upon the outcome of this treatability study.
For the TCE/PCE in the Alluvial formation east of the ASC facility, EPA has identified
several PRPs. Those include ASC, TRW as a former owner, and OEMI. Monitoring of the
ground water plumes adjacent to and downgradient of these facilities during implementation of
the remedial action will enable EPA and NDEQ to determine if this limited action is effectively
remediating the residual plume. For the TCE/CT in the upper Ogallala formation, EPA has not
identified a source of the CT contamination. The EPA believes that the TCE source may be the
upgradient facilities which already have been identified.
1 The contaminants of concern, CT, TCE, PCE and DCE are hazardous substances
within the meaning of CERCLA.
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Ground water monitoring data to be developed during the implementation of the
remedial action, will enable EPA to determine if this TCE/CT plume is migrating downgradient,
has stabilized or is shrinking through existing natural attenuation processes, and whether future
active ground water response actions are needed. Whenever ground water monitoring data
indicates that levels exceed the 10"1 carcinogenic risk range for any of the contaminants further
contingency response actions will be required. These contingency actions could include
investigations) to identify the source(s) of the contamination, the installation of a pump and treat
system, or utilization of a more innovative technology which would contain and remove the mass
or contaminant and prevent further migration.
HI. COMMUNITY PARTICIPATION
Community relations activities for the Ogallala Ground Water Contamination Site were
initiated by EPA in 1995. Early community relations activities included meeting with city and
state officials to discuss the site (December 1995), conducting interviews with local officials and
interested residents (February 1995), establishing an information repository (May 1998) and
prepanng a Community Relations Plan (May 1995). Since December 1994, EPA has conducted
periodic meetings with Ogallala city officials and concerned citizens to update them regarding
site work and investigation findings.
Information on the Qgallala Site, in the form of fact sheets, has been mailed to public
officials, Ogallala businesses and numerous citizens on a periodic basis. The RI/FS Reports and
the Proposed Plan for the Ogallala Site were made available to the public in May 1998 All
information relevant to EPA's selection of this remedy for OU1 can be found in the
Administrative Record file and the information repository maintained at the EPA Docket Room
m Region VII and at the Ogallala Public Library. The notice of the availability of these
documents was published in the Keith County News on May 4, 1998. A public comment period
was held from May 9, 1998 to August 23, 1998, following the release of the Proposed Plan The
Proposed Plan identified the preferred alternative to mitigate three separate ground water
contamination plumes at the Ogallala Site. On May 21, 1998, EPA held a public meeting to
discuss the preferred alternative for the site and to receive citizens' comments and questions At
this meeting, representatives from EPA and NDEQ answered questions about problems at the site
and the remedial alternatives. The EPA also used this meeting to solicit a wider cross-section of
community input. Agency responses to these comments are included in the Responsiveness
Summary attached to this ROD.
IV- SCOPE AND ROLE OF OPERABLE ITNTT am
The east-PCE plume in the Alluvial formation will be considered a separate operable unit
and will not be addressed by this ROD. The EPA and NDEQ are performing a treatability study
using reductive dechlorination on this plume. If data from the treatability study indicates that the
plume can be successfully addressed using this innovative technology, EPA will evaluate this
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technology under the processes required by CERCLA and the NCP to determine the appropriate
future action.
Operable Unit #01 consists of the remaining areas of ground water contamination and is
the subject of this ROD. This response action will consist of the following:
• Continuation of the ASC remediation system until EPA, in consultation with
NDEQ, determine that the remediation goals have been attained and verified;
• Restoration of the aquifer through natural attenuation;
• Implementation of institutional controls in the form of city ordinances and deed
restrictions (easements or covenants) to control the use of any contaminated
ground water for drinking in areas where contamination is present above MCLs
or in areas of known or suspected source areas;
• Completing an inventory of all wells within the city of Ogallala and
downgradient to the source areas to determine location and use of the ground
water;
• Providing an alternate source of water to any residences currently relying on
private wells impacted or potentially impacted by the presence of contamination
within OU1:
• Monitoring of the ground water and preparing a report which summarizes the
ground water information once eight quarters of data are available. This report
will evaluate whether natural attenuation will restore the aquifer within 20 years
and whether additional source areas are present.
• Quarterly monitoring of the ground water.
These actions will control the use of contaminated ground water and will allow for an evaluation
of the current status of the plumes. The EPA will evaluate the quarterly ground water sampling
data to determine if the plume is being remediated by natural biological and physical forces at an
acceptable rate. If the ground water sampling data indicates that there are source areas or "hot
spots" which show unacceptable elevated levels of VOCs, additional source investigations will
be undertaken. If these areas are determined to be contributing significant levels of
contamination to the ground water, additional contingency response actions will be considered.
These contingency actions could include EPA's prior preferred remedy (pump and treat with air
stripping) to accelerate the recovery of the aquifer or utilization of a more innovative
contingency technology which would contain and/or remove the mass of contamination and
prevent further migration.
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The actions to be conducted at the Ogallala Ground Water Contamination Site will have a
common goal: to control the exposure to contaminated ground water, to achieve ground water
plume containment, to reduce the contaminant mass in the ground water and to restore the
aquifer to MCLs. The NCP sets forth an expectation that at sites with viable aquifers, remedial
action will return the aquifer to drinking water quality within an reasonable time frame. The
EPA's goal at the Ogallala Site is to reduce contaminant levels to their target concentrations
within 20 years. The EPA will ensure that any future remedial actions will minimize the potential
for human exposure to ground water exceeding health-based standards.
Steps have been taken to prevent human exposure to contaminated ground water.
However, unrestricted water use, though it is not known to be occurring, would pose an
immediate threat to human health. If future sampling indicates the chemicals have migrated or
may potentially migrate to other public water supply wells, the Nebraska Department of Health
and Human Social Services (NDHHSS) formerly known as the Nebraska Department of Health
(NDOH), which has been delegated authority under the Safe Drinking Water Act (SDWA), 42
U.S.C. § 300f et sgfly can require the public water supplier to provide water which meets the
requirements of the SDWA.
V. SITE CHARACTERISTICS
Ground Water Characteristics
The geologic profile in the Ogallala area, from shallowest to deepest deposits of interest,
is Tertiary age and younger. Sediments underlying surficial soils generally consist of Quaternary
alluvial eolian deposits in the South Platte River Valley and in the tributaries. The thickness of
the alluvial deposits in the South Platte River Valley ranges from 27 to 70 feet. The eolian
deposits consist of dune sand and loess mantling the north and middle uplands, respectively. The
maximum thickness of the eolian deposits are 100 feet for the dune sand and 50 feet for the loess.
Quaternary alluvial and eolian deposits are underlain unconformably by the Miocene
Ogallala group. This contact is easily recognized in the Ogallala area by the transition from
massive, fine-to-coarse-grained, unconsolidated sands and gravels to unconsolidated and
partially lithified silty, sandy calcarious clays of the uppermost Ash Hollow formation. The
Ogallala group consists of hard and soft layers of sandstone interbedded with poorly sorted clay,
silt, sand and gravel. Coarse gravels and conglomerates occur throughout the unit but are mainly
confined to the lower-middle part of the formation. The maximum thickness of the Ogallala
group in Keith County is about 500 feet.
Water-bearing sediments in the Ogallala area are characterized as the High Plains aquifer.
It consists of one or more hydraulically connected units of late Tertiary or Quaternary age. The
Quaternary Alluvium represents the uppermost interval of the High Plains aquifer. Much of the
alluvium in the South Platte River Valley is a source of water for windmills, irrigation wells and
private-drinking water wells. Yields of as much as 1,000 gallons per minute have been reported
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for a few irrigation wells. Recharge of the alluvial system occurs from precipitation, underflow
down the South Platte River Valley and the Ogallala group.
The regional direction of ground water flow through the South Platte River Valley is
from west to east and is shown in Figures 11, 12 and 13. The regional hydraulic gradient
throughout the South Platte River Valley is approximately 0.0017 feet per foot. Depth to ground
water ranges from zero near surface water bodies to approximately 30 feet. Hydraulic
conductivity of the High Plains aquifer in the area ranges from approximately 25 to 100 feet per
day. Transmissivity ranges from approximately 10,000 to 400,000 square feet per day. Ground
water velocity is estimated to be from 2.3 to 13.6 feet per day.
The results of the RI have indicated there are sources of contamination in the vadose zone
(the soils beneath the land surface but above the ground water) and in the ground water within
the Ogallala Site and downgradient from potential source areas. The soil data is shown in Tables
7, 8 and 9 which were taken from NDOH's Final Baseline Risk Assessment, July 1996. Figure 5
shows the location of several businesses which were investigated as potential source areas of the
contamination present in the ground water.
The ground water data generated during the RI indicated that TCE and PCE have
migrated vertically through the vadose zone and have entered the Alluvial formation. CT and
TCE have migrated deeper within the aquifer and reside in the upper Ogallala formation. The
data further indicated that once these VOCs entered the aquifer, they migrated downgradient
primarily in the dominant direction of ground water flow.
Precise ground water plume characterization is made difficult by the fact that the High
Plains aquifer is highly transmissive and is heavily used. Seasonal stress on the aquifer alters the
hydraulic flow patterns in the region substantially; consequently, contaminant concentrations
vary seasonally. The present monitoring network may be insufficient to fully characterize the
extent of the plume but is adequate to establish primary contaminant plume features. The
selected response action does provide for the installation of up to 20 additional monitoring wells
which would be installed to further characterize the site and provide information concerning the
migration of the plume and extent of contamination.
Ground water data from all the monitoring and municipal wells depicted in Figures 11,12
and 13 were used to characterize and evaluate the contamination at the Ogallala Site. Analyses
of samples collected from the monitoring wells indicate elevated levels of CT, TCE, TCA, DCE
and PCE in the ground water. Tables 4 and 6, taken from the NDOH's Final Baseline Risk
Assessment, show a summary of the ground water data collected from all site monitoring wells
in 1995. Figures 14, 15, 16 and 17 show the estimated areas of the separate ground water
contamination plumes.
Pursuant to the authority of the SDWA, EPA has established MCLs for CT, TCE, VC,
TCA, DCE and PCE. MCL refers to the maximum permissible level of a contaminant in water
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which is delivered to any user of a public water system. MCLs are based on health risk,
treatment technology, cost and analytical methods and are used in developing ground water
cleanup levels. The MCL established for CT. TCE and PCE is 5 parts per billion (ppb or ug/1);
the MCL for TCA is 200 ppb; the MCL for VC is 2 ppb; and the MCL for DCE is 7 ppb.
Figures 14, 15, 16 and 17 show the estimated areas of contamination which exceed the MCLs for
both PCE, CT and TCE. Tables 10, 11, 12, 13, 14 and 15 show the chemicals of concern at this
site collected during the RI and used in evaluating the health risk which this contamination poses
to the Ogallala residents.
As indicated by the data presented in this ROD, the MCLs for CT, TCE, DCE and PCE
have been exceeded. All these compounds are VOCs which readily volatilize because they have
high vapor pressures. In addition, these vapors have a tendency to move through soil pore spaces
driven by diffusive and dispersive processes. Further, gravitational forces tend to drive vapors
and liquids in a downward vertical direction until they meet ground water. VOCs may then
become dissolved in ground water or may be transported separately if concentrations are great
enough.
VI- CURRENT AND POTENTIAL FUTURE SITE AND RESOURCE USES
Current land use is for businesses, manufacturing facilities and residential use. The South
Platte River is adjacent to the site as shown in Figure 2.
Land Use:
The site is used for commercial, residential and agriculture. The land use surrounding the
site is also composed of commercial, residential and agriculture. These uses are not expected to
change within the next 20 years.
Ground Water Use:
Ground water use currently is limited due to the presence of contamination within the
aquifer. Current use of the ground water are for irrigation and industrial use. Surface water is
not currently being used. Table 20 contains the current inventory of all supply wells and
monitoring wells known to exist in Ogallala.
The city of Ogallala installed a new well field north of the city and currently uses
approximately 3,000,000 gallons of water each day. Based upon information provided by the
city of Ogallala, it is estimated that the new well field has a capacity of producing approximately
9,000,000 gallons of water per day.
Future ground water use would be for consumption, as well as for industry and
agriculture. It is the goal of EPA's response actions to control exposure to the contamination
and prevent the spread of the contamination. Quarterly ground water monitoring would be used
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to ensure that the remedy is effective in addressing the contamination in the ground water. The
state of Nebraska considers site ground water to be a Remedial Action Classification (RAC-1)
aquifer, which means that it is designated as a drinking water source and deserves the highest
level of protection. The goal of the remedy is to restore the ground water for all beneficial uses
within 20 years of implementation.
VII. SUMMARY OF SITE RTSTCS
CERCLA requires EPA to seek permanent solutions to protect human health and the
environment from hazardous substances to the extent practicable. These solutions provide for
removal, treatment or containment of dangerous chemicals so that any remaining contamination
does not pose an unacceptable health risk to anyone who might come into contact with the
contaminants. The risks associated with the site were based upon the presence of CT, TCE,
DCE and PCE and other chemicals that have been found in the ground water at the site and those
shown on Table 16. Actual or threatened releases of hazardous substances from this site, if not
addressed by implementing the response action selected in the ROD, may present a current or
potential threat to public health, welfare or the environment. The risks associated with the site
indicate that these response actions are needed to prevent exposure to the contaminants in the
ground water while collecting the information needed to determine if the ongoing natural
processes are occurring at a rate which is sufficient to prevent the migration of the plume and
allow for restoration of the ground water within a 20 year period.
The baseline risk assessment estimates what risks the site poses if no actions were taken.
It provides the basis for taking action and identifies the contaminants and exposure pathways that
need to be addressed by the remedial action. This section of the ROD summarizes the results of
the baseline risk assessment for this site. The Baseline Risk Assessment, prepared by NHHSS
and included in the Administrative Record, is based on the results of the contamination studies
and evaluates potential carcinogenic and non-carcinogenic risks. The results presented here
incorporate the 1996 RI Report and prior studies conducted in connection with the Ogallala Site.2
Identification of Chemicals of Concern.
Soils and Sediment: A total of 56 soil samples were collected from 10 potential source sites and
14 sediment samples were collected from area ponds and the South Platte River. The results
were compared to risk-based concentrations for residential soil ingestion to determine if the
contaminant is of potential concern. Contaminants detected at this site were detected at
concentrations consistent with naturally-occurring levels in this area and/or at levels far below
any reference risk-based concentration. Therefore, pathways for exposure to contaminated soil
- Risk studies conducted at the Ogallala site are contained in the Administrative Record
which is available in the Docket Room at EPA Region VII Offices and at the Ogallala Public
Library.
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or sediment were not evaluated. The maximum concentrations detected and the frequency of
detection for these samples are presented in Tables 7, 8 and 9.
Indoor Air: Questionnaires were sent to Ogallala residents regarding indoor air quality in their
homes and EPA monitored basement air in several homes. It was determined that the levels of
chemicals detected in household basement air in Ogallala homes did not appear to be different
from levels found in other homes across the country. Therefore, the indoor air exposure pathway
was not evaluated.
Surface Water: Surface water samples were collected from several ponds and from the South
Platte River. Vinyl chloride, at 2 ug/1 was detected in the sample collected from pond #1 This
route of exposure was retained for further evaluation. The maximum concentrations detected and
the frequency of detection for these samples are presented in Table 15.
Ground Water: Extensive sampling of the ground water in the Ogallala area provided a
detailed characterization of the contamination. Municipal, monitoring and private domestic well
data were evaluated to determine the chemicals of concern for this media. The following
chemicals were identified and retained: chloroform, 1,1-dichloroethylene, methylene chloride
vinyl chloride, bis(2-ethylhexyl) phthalate, chloromethane, cis 1,2-dichloroethylene
tetrachloroethylene, carbon tetrachloride, 1,2-dichloroethane and trichloroethylene (Table 16
page 1). The maximum value and frequency of detection for the municipal supply wells are '
presented in Tables 1 and 2. The maximum value and frequency of detection for monitoring
wells are presented in Tables 3,4, 5, 6, 10, 11, 12, 13 and 14.
To assess the risk of exposure to contaminated ground water in Ogallala, several potential
exposure scenarios were evaluated to ensure protection of human health. These include:
• Exposure to municipal water: the risk associated with exposure to municipal well
water was evaluated by determining a 95% upper confidence limit of the mean
concentrations of a contaminant from samples collected in 1989-1995, positive
detections only. If less than 15 positive detections of a chemical were noted, then
the highest concentration of a chemical was used to determine the risk.
• Exposure to ground water in monitoring wells: several chemicals of concern were
not found m the municipal water; therefore, EPA chose two monitoring wells,
NW-1A and NW-2B, in order to evaluate all potential ground water exposure'
risks using the levels present in 1995 data. A future resident could be exposed if
using the ground water containing these chemicals.
Table 16 shows the chemicals of concern and the concentrations of these chemicals used in the
nsk assessment.
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Exposure Assessment:
In preparing the Baseline Risk Assessment, EPA first determined the most likely ways in
which community members might come into contact with site-related chemicals. The EPA
determined that residents living near the Ogallala Site might be exposed to contaminants in
ground water if they ingest ground water, use the ground water for bathing or inhale ground
water vapors while cooking, showering, washing dishes, etc. Figure 3 from the baseline risk
assessment identifies the potential routes of human exposure. Current Ogallala residents
utilizing the public water system are being supplied water in compliance with the Safe Drinking
Water Act. Residents that obtain their water from private wells may be at risk of exposure. The
routes of exposure include ingestion, dermal exposure while showering and bathing, and
inhalation of volatiles during domestic use (cooking, showering, washing clothes, etc.).
Exposure routes would be the same for future residents. In addition to the above uses, the
trespasser scenario was used to evaluate the risk associated with swimming in the contaminated
surface water. Page 26 of the baseline risk assessment presents a summary of exposure pathways
retained for quantitative evaluation.
Toxicity Assessment:
Pursuant to 40 C.F.R. Section 300.430(d)(4) and (e)(2) of the NCP, EPA determines
whether Superfund remedial actions are required for a site based upon the human health risk for a
reasonable maximum exposed individual (RME). RME exposures generally include not only
current exposures given existing land uses, but also exposures which might reasonably be
predicted based upon expected or logical future land uses. The RME for this site assumes certain
exposures which may not currently exist. The EPA believes such exposures are reasonable and
may occur unless preventive measures are taken.
A. Carcinogenic Risks
The EPA considers the cumulative carcinogenic risk at a Superfund site to be
unacceptable if an RME for the site results in an increase in cancer risk over background risk of
one-m-ten thousand (1 X 1Q-4). The term "cancer risk" sometimes is referred to as "excess cancer
risk" because it is the number of additional cases above the average number of cases that are
expected to occur in the general population if the chemicals are not present. The risk assessment
also evaluated the Central Tendency Exposure (CTE) scenarios to evaluate the risk associated
with exposure to the site contamination. The CTE is defined as the arithmetic mean risk or the
median risk expected to occur at a site. According to EPA's guidance, Risk Assessment
Guidance for Superfund Volume 1 Human Health Evaluation Manual. (Part A) Final. December
1998, Section 6.4.1, EPA only uses the RME to evaluate human health risks at Superfund sites.
For the Ogallala Site, EPA calculated the increased cancer risk of the RME using
exposure to drinking water from the following wells in accordance with the Agency's risk
assessment guidance:
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Municipal Supply Well: The risk associated with exposure to municipal well water was
evaluated by determining a 95% Upper Confidence Limit (UCL) of the mean concentration of a
contaminant from samples collected in 1988-1995 (positive detections only, Table 16). If less
than 15 positive detections of a chemical were noted during this ground water monitoring period,
the highest concentration of a chemical was used to determine the risk. For all exposure
pathways evaluated, for both the adult's and the child's RME, cumulative carcinogenic risk was
less than 1 X 10"4. The EPA recognizes that the installation of the new well field eliminated this
risk for all residents hooked up to the municipal supply. Residents, downgradient from the
former municipal supply well locations, obtaining drinking water directly from the aquifer may
still be exposed to this risk.
Monitoring Wells NW-1A and NW-2B: Since several of the chemicals of concern for the
Ogallala Site were not found in municipal water, these wells were chosen for risk evaluation in
order that all potential ground water exposure risks could be addressed. A future Ogallala
resident may choose to have a private domestic well, and an evaluation of the risk associated
with this potential scenario would be addressed by considering the contaminants detected in
these monitoring wells. The risks associated with exposure to the highest concentration of each
contaminant in these monitoring wells was evaluated utilizing data from a 1995 sampling event
and presented in Table 16. Total excess cancer risks associated with exposure to ground water
from monitoring well NW-1 A was less than 1Q-4 for all exposure pathways evaluated except the
adult RME, which was equal to 1.2 X 10 '4 . Total excess cancer risks associated with exposure
to ground^water at monitoring well NW-2B exceeded the 1 X 10 -4 for the adult RME which was
3.1 X 10 "4. Table 17 is a summary of site carcinogenic risks.
The carcinogenic risk calculated using the chemical results from the Nebraska monitoring
well locations NW-1 A and NW-2B can be attributed for the most part to four chemicals:
1,1-DCE, CT, TCE and VC. These chemicals were detected in both monitoring wells, and VC
and 1,1-DCE were also detected in the former municipal supply wells. The other volatile organic
chemicals were measured in lower concentration but also contributed to the site risk. It is
important to note that these four chemicals have related mechanisms of toxic action in regards to
liver damage.
B. Non-carcinogenic Risks
Exposure to chemicals can cause adverse health effects which include birth defects, organ
damage, central nervous system effects and many other non-carcinogenic health impacts. Non-
carcinogenic health effects are based upon contaminant concentrations and are given a Hazard
Index Rating (HI). Compounds with HI ratings greater than or equal to one would pose an
unacceptable health risk, whereas those having a rating of less than one would not pose an
unacceptable health risk. For the Ogallala Site, EPA evaluated the increased non-carcinogenic
nsk of ground water using exposure to drinking water from the same locations, the municipal
supply wells and monitoring wells NW-1A and MW-2B.
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No non-carcinogenic risks were identified for adults or children exposed to municipal
well water (all HI <1.0). Monitoring well NW-1A showed a non-carcinogenic risk (HI = 1.29)
for a child RME associated with ingestion of contaminated drinking water primarily due to TCE.
Non-carcinogenic risks were demonstrated for both adult (RME) and child (RME) exposed
through ingestion to contaminated water from monitoring well NW-2B and ranged from 1.98 to
12.2. The non-cancer risk calculated in this assessment with the available data is mainly
attributed to CT in monitoring well NW-2B and to a lesser degree also due to TCE found in NW-
2B and NW-1 A. Table 18 is a summary of the noncarcinogenic hazard indices. These
calculations were based upon EPA's 1995 data. The 1996 data indicated that levels of PCE
exceeded their former levels, therefore, this increase would cause an increase in site risks. The
EPA also believes that additional exposures to the water from monitoring well NW-1 A and NW-
2B, related to showering, bathing and household uses of water, may create additional non-
carcinogenic risks which have not been calculated.
C. Classification and Associated Risks of Contaminants Found in Ogallala
CT is classified by EPA as B2, a probable human carcinogen. CT is well
absorbed by all dosage pathways: ingestion, inhalation and dermal. Many other
toxic chemicals interact with CT to increase the toxicity of these toxicants. CT
has been found at the site above the target concentration of 31 ug/1 which is the
10'4 cancer risk level.
Non-carcinogenic effects of CT include central nervous system depression and
gastrointestinal tract irritation. Repeated doses cause severe liver and kidney
lesions, including liver tumors in many species of animals. The HI for CT equal
to 1 is 14 ug/1; CT has been found at levels above 14 ug/1. Therefore, EPA has
determined the presence of CT at the site may pose an unacceptable non-
carcinogenic risk.
TCE is classified by EPA as B2, a probable human carcinogen. TCE has been
found at the site above the target concentration of 290 ug/1 which is the 1Q-4
cancer risk level.
Non-carcinogenic effects of TCE include headaches, vertigo, visual disturbance,
tremors, nausea, vomiting, eye irritation, dermatitis, cardiac arrhythmias and
paresthesia. Chronic exposure may irreversibly damage the respiratory system,
heart, liver, kidneys and central nervous system. The HI for TCE equal to 1 is
140 ug/1; TCE has been'found at levels above 140 ug/1. Therefore, EPA has
determined that the presence of TCE at the site may pose an unacceptable non-
carcinogenic risk.
• TCA is not classified by EPA as to human carcinogenicity due to the insufficient
amount of data available.
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Non-carcinogenic effects of TCA include headaches, lassitude, central nervous
system depression, poor equilibrium, eye irritation, dermatitis and cardiac
arrhythmias. Chronic exposure may cause irreversible damage to the central
nervous system, cardiovascular system and eyes. The HI for TCA equal to 1 is
2,516 ug/1; TCA has not been found at levels above 2,516 ug/1. Therefore, EPA
has determined that TCA does not pose a non-carcinogenic risk.
The classification of PCE is under review by EPA. PCE has been found at the
site above the target concentration of 150 ug/1 which is the 10'4 cancer risk level.
Non-carcinogenic effects of PCE include irritation to the eyes, nose and throat,
finger tremors, flushed face and neck, vertigo, dizziness, skin erythema, liver
damage and mental confusion. Chronic exposure may lead to irreversible damage
of the liver, kidneys, eyes, upper respiratory system and central nervous system.
The HI for PCE equal to 1 is 198 ug/1; PCE has been found at levels above 198
ug/1. Therefore, EPA has determined that PCE does pose a non-carcinogenic risk.
DCE is classified by EPA as C, a possible human carcinogen. DCE has been
found at the site above the target concentration of 5 ug/1 which is the 10"* cancer
risk level.
Non-carcinogenic effects of DCE include irritation to the skin and mucous
membranes, headaches, and liver and kidney damage. Chronic exposure may
lead to irreversible damage of the liver and kidneys. DCE is considered an
experimental mutagen. The HI for DCE equal to 1 is 161 ug/1; DCE has not been
found at levels above 161 ug/1. Therefore, EPA has determined that DCE does
not pose an unacceptable non-carcinogenic risk.
No ecological risk assessment was performed as there appears to be no danger to
sensitive animal populations near streams, ponds or the South Platte River since contaminant
levels appear to be below established ecological benchmark values for surface water and
sediment and most significant threats presented by this site are subsurface and in the ground
water..
Actual or threatened releases of hazardous substances from this site, if not addressed by
implementing the response action selected in the ROD, may present a current or potential threat
to public health, welfare or the environment.
VIII. REMEDIATION OBJECTIVES
The remedial action objectives established for the Ogallala Ground Water Contamination
Site are:
• Prevent exposure to contaminated ground water above acceptable risk levels.
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• Prevent installation of drinking water wells in contaminated areas.
• Prevent or minimize further migration of the contaminant plumes.
• Identify any potential source areas which are contributing to the contamination in
the ground water.
• Restore the ground water to its beneficial use as drinking water source within
approximately 20 years.
The EPA will monitor the levels of TCE, PCE and CT to verify that natural attenuation processes
are occurring at a rate which is sufficient to achieve these goals, including the goal of aquifer
restoration. The EPA will evaluate the ground water monitoring data to determine if additional
sources are present which need to be addressed. In addition, EPA will also evaluate the
information to determine if the contamination in the aquifer is being reduced as predicted in the
modeling effort contained in Appendix A of the FS Reports. If processes are occurring at a rate
sufficient for restoration, then no further response actions will be needed. If the processes are not
sufficient to restore the aquifer within 20 years, then EPA will select a contingency remedy
needed to achieve this objective. The MCLs for TCE, PCE and CT are 5 ug/1. These objectives
are shown in Table 19.
IX. DESCRIPTION OF ALTERNATIVES
The EPA has evaluated ground water remediation alternatives for the remediation of the
ground water contamination within OU1 of the Ogallala Site. As presented in the FS Reports,
the retained remedial alternatives fall into three (3) general categories. These are: 1) the No
Action alternative; 2) the Institutional Controls and Limited Action alternative; and 3) Ground
Water Containment and Treatment alternatives. Section 3 of each FS Report provides a detailed
description of each alternative, the cost of each alternative and an evaluation of each containment
alternative. The Tables supporting these alternatives are also included in each FS Report. The
cost estimates were based on what the remedies would cost today to build (Capital Cost) and
what they would cost to operate and maintain until the remedial actions are completed (Annual
4 Operation and Maintenance). The EPA has combined the costs for the west-PCE plume in the
Alluvial formation, the TCE plume in the Alluvial formation and the TCE/CT plume in the upper
Ogallala formation, including the capital and Operation and Maintenance (O&M) costs, to obtain
a single present worth value for purposes of comparing the various alternatives. Present worth is
the amount of money that, if invested today at the present interest rate, would pay for the capital
and operating and maintenance costs for the life of the project. The alternatives are briefly
described below.
A. No Action
Under the No Action alternative, restrictions on the use of contaminated ground water
would not be implemented, the inventory of ground water wells would not be accomplished, data
would not be evaluated for potential source areas, and the ground water plumes would not be
monitored. The potential for significant ground water contamination to reach areas where the
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ground water is uncontaminated would be unknown. Limited action has already taken place at
the site as a new well field has been installed by the city of Ogallala providing an alternate public
water supply. The potential for community exposure to contaminant levels exceeding health
standards still would exist. The EPA's policy requires consideration of a No Action alternative
to serve as a basis against which the other remedial alternatives can be compared.
The cost for this alternative is zero; implementation time is zero.
Chemical-specific applicable or relevant and appropriate requirements (ARARs) would
be met as the concentrations of the contaminants would achieve MCLs within some period of
time. Action-specific ARARs under Nebraska Title 118, Appendix A for physical site controls
and/or monitoring of existing and future conditions would not be met. Other action-specific and
location-specific ARARs do not apply. For additional ARARs, see Table 4-1 of the FS Reports
and Section X.A.2 of this ROD.
The expected outcome of the No Action alternative is that the exposure to plumes would
potentially continue as residents relying on private wells downgradient from the source areas
may be exposed or potentially exposed and, if source areas are present, they would continue to
contribute to the contamination present in the aquifer and would not be identified for further
response action.
B. Institutional Controls and Limited Action
Institutional Controls and Limited Action alternative consists of actions which lower the
risk of exposure to contamination through physical and/or legal means. Institutional Controls
would include a city ordinance to limit future domestic use of the ground water. Institutional
Controls would also include deed notices/restrictions on selected property which will control the
use of the ground water in the known source areas. Limited action includes ground water
monitoring within the boundaries of the site and downgradient from the site The EPA will use
the ground water monitoring results to evaluate the presence and rate of existing natural
attenuation processes. Natural attenuation is the reduction in concentration of contaminants
through a variety of biological, chemical or physical processes. Biological processes include
aerobic and anaerobic biodegradation and plant and animal uptake. Chemical processes include
ion exchange, complexation and abiotic transformation. Physical processes that aid the natural
attenuation processes include advection, dispersion, dilution, diffusion, volatilization, sorption
and desorption. Natural attenuation processes affect the fate and transport of chlorinated solvents
in all hydrologic systems. This alternative does not attempt to clean up the contaminated ground
water by active means or restrict the flow of the contaminated ground water. Ground water
monitoring is applicable to both the Alluvial and the Ogallala formation. Sampling and analysis
of ground water throughout the area of contamination and potential contamination would be used
to evaluate migration of contaminants, as well as the potential for contamination of on-site and
nearby residential, industrial and commercial wells. Monitoring alone is considered a viable
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limited action alternative. An alternate private water supply would provide a safe drinking water
source for each private well user who does not rely on the municipal system.
The estimated present worth for this action, which would address the west-PCE plume
and the TCE plume in the Alluvial formation and the TCE/CT plume in the Ogallala formation,
is $1,805,623 which includes 5313,670 for capital costs and $95,784 per year for operation and
maintenance costs for a period of 16-28 years (FS Reports estimate). Costs associated with this
alternative would increase if the time needed to attain MCLs is beyond 28 years. These costs
include $60,000 for the cost of deed restrictions as well as the costs for the installation of an
additional 20 ground water monitoring wells. Five (5) year reviews would be needed until the
plume had achieved MCLs throughout the area, and the costs for the five year review are
estimated to be $45,000 per five year review. The cost estimate includes sampling quarterly for
the first 2 years and then twice a year for the next 16 years. For costing purposes, a total of 40
ground water well samples per sampling event were estimated.
Chemical-specific ARARs would be met when MCLs are attained for the plume. EPA's
modeling estimate predicted that a period of at least 33 years would be needed if sources were
continuing to contribute contaminants to the aquifer. Action-specific ARARs would be attained
using this Institutional Control and Limited Action alternative at the Ogallala Site provided
natural attenuation processes effectively contain and reduce the contamination within the aquifer.
There were no location-specific ARARs identified for this work. For additional ARARs, see
Table 4-1 of the FS Reports and Section X.A.2 of this ROD.
The expected outcomes of the Institutional Controls and Limited Action alternative are
that: exposure to contaminated ground water would be restricted by an effective city ordinance,
source areas (if present) would be identified by the information collected during the ground water
monitoring effort, monitoring of private wells downgradient to the areas of contamination would
be conducted, residents using contaminated ground water would be provided a source of clean
water, the rate of ongoing natural attenuation processes would be evaluated and the aquifer
would be restored within a reasonable time frame of less than 20 years.
C. Action - Ground Water Containment and Treatment
1. Extraction Wells/Deep-Well Injection
This plume management alternative involves the installation of ground water extraction
wells pumping at a rate determined during the remedial design phase of the project which should
remediate the site in 10-21 years. The recovered ground water would be reinjected into the
ground below the lowermost aquifer containing an underground source of drinking water. This
remedy was evaluated for all three plumes (TCE in the Alluvial formation, TCE/CT in the upper
Ogallala formation, and west-PCE in the Alluvial formation). The EPA's preliminary analyses
for these plumes indicated that 7 wells pumping for 10 plus years at a combined flow rate of 210
gallons per minute would be sufficient to reach the target MCL concentrations for the
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contaminants of concern. Capital costs for this alternative were estimated to be 53,577,949. The
present worth of the operation and maintenance costs were estimated to be 54,031,697 with a
total present net worth of 57,609,646.
Action-specific ARARs for this alternative, such as level of control for the contaminated
ground water to meet MCLs, would be achieved. Location-specific ARARs are not applicable.
Chemical-specific ARARs (MCLs) would be met as the ground water is reinjected deeper into
the earth. For additional ARARs, see Table 4-1 of the FS Reports and Section X A 2 of this
ROD.
This alternative includes the remedial action components of the Institutional Control and
Limited Action alternative. The expected outcome of this alternative is to reduce the
contamination in the aquifer within a shorter period of time as compared to the Institutional
Control and Limited Action alternative by transferring the contamination to the deeper portion of
the aquifer into a Class III aquifer unsuitable for use as a drinking water supply.
2. Ex-situ Air Stripping/Surface Water Discharge
This plume management alternative involves pumping contaminated ground water at a
rate sufficient to hydraulically contain the contaminated ground water with extraction wells,
treating the water by air stripping and releasing the treated water under a National Pollution
Discharge Elimination System (NPDES) permit. The EPA's preliminary analyses for the
TCE/CT plume indicated that two wells pumping for 10 plus years at a flow rate of 100 gallons
per minute would be sufficient to reach the target MCL concentrations for the contaminants of
concern. For the west-PCE plume, no additional wells would be added but the current system
would be operational for the next six years. For the TCE plume in the Alluvial formation, four
additional extraction wells would be added and pumped for a combined rate of 100 gallons per
minute (gpm) for at least 15 years. The final pumping rates would be determined as part of the
Remedial Design. A higher pumping rate would remove contaminants in a shorter period of time
but could be more costly.
The pumping rate selected would contain the contaminated ground water at health-based
target levels identified in this ROD. A ground water monitoring program would be established
to determine the effectiveness of the extraction and treatment system and to chart the progress
made in achieving remediation goals. In addition, all extracted water would be treated to a level
meeting MCLs prior to discharge.
The air stripping system for each plume would consist of piping, minimal instrumentation
and possibly a chemical feed system to prevent scale formation. The system would be enclosed
in a building for weather protection and security, Contaminated ground water would flow to the
top of a packed column stripper. The removal efficiency of such a stripper is estimated to be
99.8%. A blower would be used to force air through the tower, counter current to the flow of
water. Treated water would collect in a sump at the base of the stripper and from there pumped
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to a release point at the surface. Contaminants removed from the water in the air stripper would
be released to the atmosphere. NDEQ requires a permit for air toxic emissions above 74 pounds
per day. The air stripping system would emit air toxics at a rate of approximately 0.3 pounds per
day based upon an extraction of 100 gpm and an average VOC concentration of 65 ug/1. Capital
costs for this remedy for all three plume areas were estimated to be 53,158,691. The present
worth estimate for operation and maintenance costs were estimated to be $5,484,193. Present net
worth costs for this alternative were estimated to be $8,642,884 for an estimated 10 years.
Action-specific ARARs for this alternative, such as level of treatment for ground water to
meet MCLs, would be achieved. Location-specific ARARs are not applicable. Chemical-
specific ARARs (MCLs) would be applicable and would be met for treated ground water
(NPDES). This alternative would provide for the cleanup of the ground water to MCLs. For
additional ARARs, see Table 4-1 of the FS Reports and Section X.A.2 of this ROD.
This alternative includes the remedial action components of the Institutional Control and
Limited Action alternative. The expected outcome of this alternative is to reduce the
contamination in the aquifer within a shorter period of time as compared to the Institutional
Control and Limited Action alternative by transferring the contamination from the ground water
to the atmosphere. This would allow for the restoration of the aquifer in a shorter amount of time
than the Institutional Control and Limited Action alternative but would allow the release of the
contaminants to the air. Restoration time frames were estimated to be approximately 10 years.
3. Ex-situ Carbon Adsorption/Surface Water Discharge
This plume management alternative was only evaluated for the TCE/CT plume and
involves the installation of two extraction wells to extract contaminated ground water and the
same number of years for operation as the Ex-site Air Stripping/Surface Water Discharge
alternative (10 plus years). The difference is that this alternative uses liquid phase carbon
adsorption for treatment of the ground water prior to its discharge. Once the water is treated, the
decontaminated ground water will be discharged to an appropriate discharge point under an
NPDES permit. Liquid phase carbon adsorption involves passing the contaminated ground water
through beds containing granular activated carbon (GAC). The GAC system would consist of a
piping manifold and minimal instrumentation. The system would be enclosed in a building for
weather protection and security. Contaminated water from extraction wells would be pumped to
a surge tank and from there pumped through the GAC system. Two modular GAC adsorbers per
system would be used and would be arranged in series so that "breakthrough" (passage of the
contaminants from the first adsorber to the second adsorber) would be prevented. Until
"breakthrough" occurs, GAC would remove nearly 100% of the VOCs. The piping manifold
would allow either of the two adsorbers to be the first in series. Treated water would be
discharged at the surface. A pump test would be conducted at the site to determine the
appropriate extraction rate of ground water for containment and mass removal system. For the
remediation of the TCE/CT plume only, capital costs were estimated to be $1,892,353. The
present worth estimate of the operation and maintenance costs were estimated to be $1, 992,625.
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The total present net worth estimate was estimated to be 53,884,978 and an estimated time for
completion to be a minimum of 10 years.
Action-specific ARARs for this alternative, such as level of treatment for ground water
to meet MCLs, would be achieved. Location-specific ARARs are not applicable. Chemical-
specific ARARs (MCLs) would be met for treated ground water. This alternative would provide
for the cleanup of the ground water to MCLs. For additional ARARs, see Table 4-1 of the FS
Reports and Section X.A.2 of this ROD.
This alternative includes the remedial components of the Institutional Control and
Limited Action alternative. The expected outcome of this alternative is to reduce the
contamination in the aquifer within a shorter period of time as compared to the Institutional
Control and Limited Action alternative by extracting the contaminated ground water, removing
the contamination from the ground water by liquid phase GAC and then discharging the treated
ground water under an NPDES permit. Restoration of the aquifer was estimated to last
approximately 10 years. This alternative was evaluated for only the TCE/CT plume.
4. In-situ Oxidation/Vapor Extraction
This alternative involves the installation and operation of a series of injection wells to
inject ozone into the contaminant plume to degrade contaminants, installation and operation of a
vapor extraction system to collect volatilized contaminants resulting from the oxidation system
and implementation of the institutional actions. With ozone enhanced sparging, the principal
remediation mechanism is direct oxidation of contaminants located in the ground water. The
primary component of contaminant removal will be through direct oxidation. Volatilization of
the contaminants is also anticipated and vapor extraction will capture the released contaminants.
The cost estimate includes a thermal oxidizer/scrubber unit as the off-gas treatment to destroy the
vapors captured. For the purpose of estimating costs, restoration time was estimated to last six to
eight years using this alternative. Capital costs were calculated for all three areas of
contamination and are estimated to be $18,761,773. The present worth estimate of the operation
and maintenance costs are estimated to be $4,933,541. The total present net worth was estimated
to be $23,695,114. A treatability study would be needed to determine the number of wells and
the extraction rate.
Action-specific ARARs for this alternative, such as level of treatment for ground water to
meet MCLs, would be achieved. Location-specific ARARs are not applicable. Chemical-
specific ARARs (MCLs) would be met for treated ground water. This alternative would provide
for the cleanup of the ground water to MCLs. For additional ARARs, see Table 4-1 of the FS
Reports and Section X.A.2 of this ROD.
This alternative includes the remedial action components of the Institutional Control and
Limited Action alternative. The expected outcome of this alternative is to reduce the
contamination in the aquifer within a shorter period of time as compared to the Institutional
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Control and Limited Action alternative by destroying the contaminants present in the aquifer and
removing any residual by vacuum extraction. Aquifer restoration was estimated to take
approximately six to eight years using this alternative.
5. In-situ Air Sparging/Vapor Extraction
This alternative involves the installation and operation of a series of injection wells to
inject air into the Ogallala and Alluvial formations, installation and operation of a vapor
extraction system to capture the air bubbles. Sparging and vapor extraction will combine to
remove any volatilized contaminants. Off-gas treatment of the vapors will be treated with a
thermal oxidizer/scrubber. For the purpose of estimating costs, it was estimated to take between
six to eight years to restore the aquifer using this alternative. Capital costs for remediation of all
three plume areas are estimated to be SI 8,883,423. The present worth estimate for the operation
and maintenance costs are estimated to be $4,898,362. The total present net worth was estimated
to be $23,781,785. Bench scale testing would be needed to evaluate the number of extraction
wells and the size of the vapor extraction system.
Action-specific ARARs for this alternative, such as level of treatment for ground water to
meet MCLs, would be achieved. Location-specific ARARs are not applicable. Chemical-
specific ARARs (MCLs) would be met for treated ground water. This alternative would provide
for the cleanup of the ground water to MCLs. For additional ARARs, see Table 4-1 of the FS
Reports and Section X.A.2 of this ROD.
This alternative includes the remedial action components of the Institutional Control and
Limited Action alternative. The expected outcome of this alternative is to reduce the
contamination in the aquifer within a shorter period of time as compared to the Institutional
Control and Limited Action alternative by removing the contaminants present in the aquifer by
vacuum extraction. Aquifer restoration was estimated to take approximately six to eight years.
6. Containment by Air Injection Wells
This alternative involves the installation and operation of air injection wells to contain the
contaminated ground water by altering the hydraulic gradient. This would be an effective
treatment for the Alluvial formation. This alternative was not evaluated for the TCE/CT plume
in the upper Ogallala formation. Air sparging would cause the ground water to mound which, in
turn, would stop ground water flow, thus preventing any further migration of the contamination.
A restoration time of 30 years was assumed for the life of this alternative. A full scale pilot test
would be required to determine the efficiency of air sparging to contain the plume. Capital costs
were estimated to be S1,331,263. The present worth operation and maintenance costs were
estimated to be $2,445,420 and were anticipated to last from 10 years to 30 years. The total
present net worth was estimated to be $3,756,953. Number of wells and the air injection rate
would be determined based upon a pilot test.
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Action-specific ARARs for this alternative, such as level of treatment for ground water to
meet MCLs, would be achieved. Location-specific ARARs are not applicable. Chemical-
specific ARARs (MCLs) would be met for treated ground water. This alternative would provide
for the cleanup of the ground water to MCLs. For additional ARARs, see Table 4-1 of the FS
Reports and Section X.A.2 of this ROD.
This alternative includes the remedial action components of the Institutional Control and
Limited Action alternative. The expected outcome of this alternative is to reduce the migration
of the contamination in the aquifer. This alternative has a longer estimated cleanup time than the
Institutional Control and Limited Action alternative as the mounding of the contaminants would
prevent the dilution of the contaminants. This alternative would only be applied to the
contamination present in the Upper Ogallala formation.
x- COMPARATIVE ANALYSIS OF ALTERNATIVES
The NCP sets forth nine evaluation criteria which serve as a basis for comparing the
remedial alternatives for final actions. These nine criteria are divided into three categories:
Threshold Criteria, Primary Balancing Criteria and Modifying Criteria. If any remedial
alternative identified during the FS process does 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, degree of difficulty involved 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 the community have reviewed and
commented on the Proposed Plan and the other alternatives considered by EPA.
Tables 4-8 from the plume specific FS Reports, attached to this ROD as Table 22, present
the remedial alternatives and describe how each alternative satisfies the threshold and primary
balancing criteria. Evaluation of compliance with the remaining Modifying Criteria is included
in the following discussion. 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
Overall protection of human health and the environment addresses whether each
alternative provides adequate protection of health or the environment and
describes how risks posed through each exposure pathway are eliminated,
reduced or controlled through treatment, engineering controls and/or institutional
controls. An alternative is normally considered to be protective of human health
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if the excess cancer risk is reduced to less than I in 1,000,000 (10'6) and risks do
not pose non-carcinogenic health risks (HI <1 ).-
The No Action alternative would not be effective for protection from the human
or environmental risks associated with the site. Private well users exist who may
be exposed to the contaminant plume. Institutional Controls and Limited Action
alternative would provide overall protection of human health and the environment
by preventing exposure, controlling ground water use and monitoring. However,
Institutional Controls and Limited Action alternative may not prevent further
degradation of the aquifer or reduce risks by removing contaminants from the
aquifer unless natural attenuation processes are occurring at a rate which is
sufficient to prevent the migration of and reduce the amount of the contamination.
With extensive monitoring, EPA would evaluate the extent of migration of the
plumes and could determine if the Institutional Controls and Limited Action
alternative meets this criteria. Evaluation of the quarterly sampling results will
allow for EPA to determine if there are additional sources present and migrating
to the ground water. A review of the data will also allow EPA to identify the
ongoing natural attenuation processes and establish the rate at which they are
occurring. This information will allow EPA to determine if these existing natural
processes are sufficient to restore the aquifer in an acceptable time frame as
predicted in the modeling efforts presented in the FS Reports as Appendix A.
Monitoring of all private wells used to withdraw drinking water would enable
EPA to evaluate potential exposure affecting human health. Institutional
controls, in the form of deed restrictions or notices, would be filed on selected
property to notify future land owners of the hazards associated with the
contaminated ground water in the area. A city ordinance requiring all residents
living within the contaminated plume areas to be connected to the municipal
water supply will aid in preventing the ingestion of the contaminated ground
water. All the alternatives which involve ground water extraction and treatment
would comply with this criteria and would be the most protective, as they remove
contamination from the aquifer and treat the ground water prior to release or
reuse. The Institutional Control and Limited Action alternatives includes response
actions that may not restore the plumes to drinking water standards as quickly as
more active remedial actions. However, the alternative would prevent the further
degradation of the aquifer if natural attenuation is effectively working.
For the alternatives using ground water extraction and treatment, GAC would be
more protective than air stripping as a treatment process since no air emissions
The Hazardous Index rating, as discussed in Section VII. B., herein, does not exceed 1.
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would be generated with GAC. Air stripping would allow the contaminants to be
transferred from the ground water into the atmosphere.
2. Compliance with Applicable or Relevant and Appropriate
Requirements
Section 121 (d) of CERCLA requires that remedial actions at CERCLA sites at
least attain legally applicable or relevant and appropriate federal and state
requirements, standards, criteria and limitations, collectively referred to as
"ARARs", unless such ARARs are waived under CERCLA Section 121 (d)(4).
Applicable requirements are substantive environmental protection requirements,
criteria or limitations promulgated under federal or state law that specifically
address hazardous substances, the remedial action to be implemented at the site,
the location of the site or the circumstances present at the site.
Relevant and Appropriate requirements are substantive environmental protection
requirements, criteria or limitations promulgated under federal or state law,
which, while not applicable to the hazardous materials found at the site, the
remedial action itself, the site location or other circumstances at the site,
nevertheless address problems or situations sufficiently similar to those
encountered at the site that their use is well-suited to the site.
There are three (3) types of ARARs to be addressed for the contaminated ground water at
the site; chemical-specific, action-specific and location-specific.4
Chemical-specific ARARs are requirements that set final concentrations of
chemicals of concern in the contaminated material (e.g., ground water)
which must be achieved by the remedial action. Chemical-specific
ARARs for this site are the MCLs. These actions would attain chemical-
specific ARARs set forth in the Nebraska Administrative Rules and
Regulations (Neb. Adm. Rules and Regs.), Title 118 - Ground Water
Quality Standards and Use Classification, and the Safe Drinking Water
Act (SDWA), 42 U.S.C. § 300 et seo^, although the No Action and the
Institutional Controls and Limited Action alternatives may not attain these
ARARs as quickly as other alternatives. For the alternatives that use
extraction and treatment, all extracted ground water, prior to discharge,
would meet the requirements of Title 118 and the SDWA as the extracted
4 The ARARs for this site are contained in the FS Reports, Table 4-1, and they include the
state ARARs which were identified by the state of Nebraska for the remedial alternatives.
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water would be treated to a level that would achieve MCLs. If the treated
ground water is discharged into surface water, the requirements of the
Clean Water Act, 33 U.S.C. § 1251 et seq.. and the Nebraska
Environmental Protection Act Title 117, 119 and 121 would have to be
met.
Action-specific ARARs are those requirements that set standards on the
treatment and discharge components of the remedial action. Action-
specific ARARs for this site are listed in Table 4-1 in the FS Reports for
each contaminated plume area. For on-site cleanup activities under
Section 121(e)(l) of CERCLA, EPA is not required to obtain any federal,
state, or local permits for actions conducted on-site, complying only with
the substantive (non-administrative) requirements of the identified federal
and state laws. Ground water monitoring must comply with the
Department of Water Resources pursuant to Neb. Rev. Stat. S46-602 et
seq.. and Title 456-rules for Groundwater (Department of Water
Resources). If the ground water monitoring well is to be located in a
ground water management or control area, a permit is required from the
local Natural Resources District prior to construction. Title 178 regulates
monitoring well drillers and well construction. Well spacing requirements
are found at Neb. Rev. Stat. S46-651-S46-655. The following ground
water monitoring requirements are found at 40 C.F.R. Part 264 Subpart F
and incorporated in Title 128 (Rules and Regulations Governing
Hazardous Waste Management in Nebraska) and are relevant and
appropriate: 40 C.F.R. §264.93 identifying hazardous constituents, also
Title 128, Appendix I; 40 C.F.R. §264.94 establishing concentration
limits in the ground water for hazardous constituents; and 40 C.F.R.
§264.97 specifying general ground water monitoring requirements,
including but not limited to, well installation, sampling and analysis, and
statistical methods. The Occupational Safety & Health Act (OSHA), 42
U.S.C. §§ 651-678, and SDWA apply to all alternatives except the No
Action alternative. Specifically, all remediation would be performed by
workers acting in compliance with OSHA regulations. The Extraction
Wells/Deep Well Injection alternative must comply with Title 122, Rules
and Regulations for Underground Injection Control which requires state
review and permitting prior to injection well construction and
implementation. Alternatives which discharge water to surface water must
comply with Title 119 - Rules and Regulations Pertaining to the Issuance
of Permits Under the NPDES and Title 121 - Effluent Guidelines and
Standards. NPDES discharge limits would be based on either Title 117-
Nebraska Surface Water Quality Standards or Title 118 - Ground Water
Quality Standards and Use Classification. Additionally, if the treated
ground water is provided as a beneficial use to the public drinking water
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supply, with the state's approval, the MCLs would have to be met in
compliance with SDWA. Also, treated ground water would have to
comply with SDWA prior to reinjection. The GAC adsorption alternative
would meet action-specific ARARs in that hazardous waste generated
through the GAC adsorption would be disposed in compliance with RCRA
and the Neb. Adm. Rules and Regs., Title 128 - Rules and Regulations
Governing Hazardous Waste Management in Nebraska. The use of air
stripping with no emission controls would also meet action-specific
ARARs even though this alternative would result in the discharge of very
low levels of VOCs into the atmosphere. The limitation'on discharge of
VOCs without a permit, set by Neb. Adm. Rules and Regs., Title 129 - Air
Pollution Control Rules and Regulations, would not be exceeded. Air
emissions would comply with the Clean Air Act, 33 U.S.C. § 1251 et.
seg., as well as Title 129 - Air Pollution Control Rules and Regulations.
The In-situ Oxidation/Vapor Extraction alternative would have to comply
with Title 123 - Rules and Regulations for Design, Operation and
Maintenance of Wastewater Treatment Works and the sludge generated
from this process would be a solid waste under Title 128, Chapter 2.
• Location-specific ARARs are requirements that might apply to a remedial
action due to the site's unique cultural, archaeological, historical or
physical setting (e.g., wetlands). There are no location-specific ARARs
for the Ogallala Site because such features have not been identified as
existing in the site area.
B. Primary Balancing Criteria:
1. Long-Term Effectiveness and Permanence
Long-term effectiveness and permanence refers to expected residual risk and the
ability of a remedy to maintain reliable protection of human health and the
environment over time, once clean-up levels have been met. This criterion
includes the consideration of residual risk and the adequacy and reliability of
controls. The adequacy and reliability of controls is an assessment of the
engineered systems or institutional controls used to manage the contaminant
plumes. This evaluation will include an assessment of the potential need to
strengthen controls to ensure that any exposure is within protective levels. Each
alternative, except for the No Action alternative, provides for some degree of
long-term protectiveness and permanence.
The Institutional Controls and Limited Action alternative is effective in the long-
term and is permanent provided all sources are identified and removed and the
ongoing natural attenuation processes are actively remediating the plumes. As
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part of this alternative, an extensive survey of all private wells impacted or
potentially impacted by the contaminated plumes would be performed. Identified
wells would be monitored and alternate drinking water sources would be
provided, all in an effort to prevent exposure to unacceptable levels of
contaminated ground water. Effective institutional controls, including city
ordinance and deed notices on selected property considered as source areas of
contamination, would serve to notify future landowners of the restrictions placed
on ground water usage.
All the other alternatives involve some degree of ground water extraction and
treatment. The ground water extraction and treatment remedies achieve final
cleanup levels for the ground water and are also effective in the short-term in
preventing further degradation of the ground water.
Also, as mandated by Section 121(c) ofCERCLA, EPA will conduct five-year
reviews at the site as long as hazardous substances remain above health-based
criteria.
2. Reduction of Toxicity, Mobility, or Volume Through Treatment
Reduction of toxicity, mobility or volume through treatment refers to the
anticipated performance of the treatment technologies that may be included as
part of a remedy. Remedial actions which include treatment are favored by the
NCP. The EPA evaluates each alternative based on how its treatment methods
reduce the harmful nature of the contaminants, limit the ability of the
contaminants to migrate and minimize the amount of contamination remaining
after the remedial action is completed.
The No Action alternative will provide intrinsic reduction of toxicity, mobility or
volume, but no data would be generated to verify that this alternative is working.
The Institutional Controls and Limited Action alternative will provide intrinsic
reduction of toxicity, mobility or volume through physical chemical and/or
biological natural attenuation processes. The data validating and quantifying the
existing natural attenuation processes will be collected during the first two years
of ground water monitoring implementation. The Institutional Controls portion
of the remedy will restrict access to the contaminated plume areas. For any
private well user impacted or potentially impacted by contaminated ground water,
a source of uncontaminated water will be provided. The other plume
management alternatives that employ treatment to reduce the toxicity, mobility or
volume of the contaminated ground water plume would meet with this criteria.
The alternative utilizing deep well injection would reduce the mass of
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contaminants in the Alluvial formation, resulting in the reduction in mobility for
the contaminant mass in this formation. However, the contaminated ground
water would be injected into a different ground water aquifer. For the alternatives
that discharge the treated ground water at the surface, a reduction of contaminant
toxicity, mobility and volume will be achieved. GAC treatment removes the
contaminants from the ground water and regeneration of the GAC for reuse will
ultimately result in the destruction of the contaminants. Air stripping removes the
contaminants from the ground water and releases them into the atmosphere in
compliance with state and federal standards.
3. Short-Term Effectiveness
Short-Term effectiveness addresses the length of time needed to implement the
remedy and any adverse impacts that may be posed to workers and the
community during construction and operation of the remedy until cleanup goals
are achieved.
Except for continued adverse impacts to the community, the No Action
alternative is effective in the short-term since no time is required to implement
this alternative and there would be no short-term impacts to construction workers.
Adverse impacts to the community may include the further migration of
contamination in the ground water and continued risk of exposure to site
contaminants to private water well users.
The short-term affect of the Institutional Controls and Limited Action alternative
would be minimal as EPA estimates that it will take approximately one year to
install monitoring wells and to place the deed restrictions and city ordinance in
effect. Adverse impacts to the community would be reduced as the information
from the ground water monitoring would identify areas of contamination and
effective institutional and administrative controls should restrict the ingestion of
contaminated ground water. Migration of contamination in the ground water
would be monitored and, if sources of contamination are noted, further response
actions may be warranted.
The other plume management alternatives would meet the short-term
effectiveness criteria once the systems are installed and operational. Time
estimates for the installation of these treatment systems range from six months to
two years. The EPA considers the risks that conducting a particular activity may
pose to site workers, nearby residents, or the local environment. The Extraction
Wells/Deep-Well Injection alternative is comparable to the Institutional Controls
and Limited Action alternative as it would be implemented within six months and
site risks would be addressed in a Health and Safety Plan. For the remedies that
use treatment of the extracted ground water prior to discharge, EPA estimates the
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time to install the full scale system would be approximately 12 months to
implement.
A Health and Safety Plan will be prepared for the implementation of all response
actions. This plan will provide the procedures for all site workers to follow
during the field testing, installation of the monitoring wells, collection of ground
water samples and installation of any equipment needed for the ground water
treatment system. Health and safety issues will be addressed at each phase of
these response actions.
Implementation of either GAC or Air Stripping would present a minimal risk to
workers, the community and the environment. The potential worker exposure
during construction and operations would be minimized by following a site
Health and Safety Plan addressing issues such as air monitoring and personnel
protective equipment. The release of contaminants to the atmosphere is expected
to be minimal during construction. Contaminated soils or fluids would be
properly handled and disposed.
4. Implementability
Implementability addresses the technical and administrative feasibility of a
remedy from design through construction and operation. Factors to be considered
are 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.
For the No Action alternative, there are no implementabiliry concerns as no
actions would be implemented.
The Institutional Controls and Limited Action alternative is technically and
administratively implementable. The city of Ogallala has installed a new well
field that supplies the public with drinking water. Users of the ground water
where contamination is present who rely on their private wells for drinking
purposes will be offered one of several options under this alternative including a
home treatment system, supplies of bottled water, or hookup to the city water
system. It is anticipated that a city ordinance would be passed that restricts the
installation of ground water wells in contaminated areas located within the city's
jurisdiction. Construction of ground water monitoring wells and their operation
and maintenance are standard practices in the industry and are readily performed.
Generally, ground water extraction and treatment technologies are well
established for ground water containment and contaminant mass removal and
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could be easily implemented at the Ogallala Site. Many such technologies have
been implemented at other Superfund sites and have been proven effective in
removing significant levels of contaminants. Surface water discharge is easily
implemented if the system is located at the old city dump area. Although ground
water extraction and treatment alternatives are technically implementable, certain
site-specific characteristics could present obstacles during the construction and
installation of the extraction wells and trenching of the subsurface utilities.
Significant obstacles such as existing buildings and subsurface utilities can
prohibit the desired locations of the injection wells and lower the system
performance due to the restrictions of well placement. Access to property could
effect system design for the most economical and feasible means of remediating
the contaminated areas. Access could restrict the location and installation of the
recovery wells and the subsurface trenching. System design would reflect a
system which would cause the least interference with normal business operations
in the affected area. The In-situ Oxidation/Vapor Extraction or the In-situ Air
Sparging/Vapor Extraction alternatives would be the most burdensome to
implement as they require numerous wells to be installed and subsurface
trenching in areas which are dedicated to business.
5. Cost
The estimated total net present worth costs for all alternatives, not including the
No Action alternative range, from $1,805,623 to $23,781,785. Present worth
costs include capital costs and operation and maintenance costs for the estimated
length of the remedial action. Capital costs apply to activities such as
construction, land and site development and disposal of waste materials.
Operation and maintenance costs are spent on activities such as on-going
operation of equipment, insurance and periodic site reviews.
The estimated costs of the Institutional Control and Limited Action alternative
for the TCE in the Alluvial formation, the TCE/CT in the Ogallala formation and
the west-PCE plume are as follows:
Capital Costs $ 313,670
O&M Costs $ 1,491,953
Present Worth $1,805,623
Capital costs include design and installation of 20 additional monitoring wells, as
well as costs for implementation of institutional controls. The estimated O&M
costs include the costs of monitoring and maintenance for 16-28 years, the costs
of providing bottled water and 5-year reviews throughout the life of the project.
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The estimated costs of the Extraction Wells/Deep-Well Injection alternative for
the TCE in the Alluvial formation, the TCE/CT in the Ogallala formation and the
west-PCE plume are as follows:
Capital Costs $ 3,577,949
O&M Costs $ 4,031,697
Present Worth $ 7,609,646
Capital costs include design and installation of one or more ground water
recovery wells and pumping systems, installation of re-injection wells and
pumping system and implementation of an operation, monitoring and
maintenance program. Institutional controls and monitoring would also be
implemented. Six ground water extraction wells and three extraction and deep-
well injection systems were included in the capital costs for 10-21 years of
operation.
The estimated costs of the Ex-situ Air Stripping/Surface Water Discharge
alternative for the TCE in the Alluvial formation, the TCE/CT in the Ogallala
formation and the west-PCE plume are as follows:
Capital Costs 53,158,691
O&M Costs $5,484,193
Present Worth $ 8,642,884
Capital costs include design and installation of ground water recovery wells and
pumping systems, installation of the treatment systems, installation of both
influent and effluent piping networks and implementation of an operation,
monitoring and maintenance program. Institutional controls would also be
implemented. Six ground water extraction wells would be installed under this
alternative for 6-15 years of operation.
For the Ex-situ Carbon Adsorption/Surface Water Discharge alternative the
estimated costs for TCE/CT in the Ogallala formation only are as follows:
Capital Costs $1,892,353
O&M Costs $ 1,992,625
Present Worth $ 3,884,978
Capital costs include design and installation of ground water recovery wells and
pumping system, installation of the fixed-bed carbon adsorption system,
installation of influent and effluent piping networks, and implementation of an
operation, monitoring and maintenance program. Two ground water recovery
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wells would operate for 15 years and extract ground water at a combined rate of
100 gallons per minute. Institutional controls would also be implemented.
The estimated costs of the In-situ Oxidation /Vapor Extraction alternative the
for the TCE in the Alluvial formation, the TCE/CT in the Ogallala formation and
the west-PCE plume are as follows:
Capital Costs $18,761,773
O&M Costs $ 4,933,541
Present Worth S 23,695,314
Capital costs include design and installation of air sparging wells, installation of
the ozone generator and compressed air delivery system, installation of the
compressed air/ozone piping system, installation of vapor extraction wells,
installation of vapor extraction equipment, installation of the vapor extraction
piping network and implementation of an operation, monitoring and maintenance
program. A thermal oxidizer/scrubber unit as the off-gas treatment is included in
these costs. Three systems (one for each plume) are also included. Cleanup time
was estimated to last approximately eight years. Institutional controls would also
be implemented.
The estimated costs of the In-situ Air Sparging/ Vapor Extraction alternative
for the TCE in the Alluvial formation, the TCE/CT in the Ogallala formation and
the west-PCE plume are as follows:
Capital Costs $18,883,423
O&M Costs $ 4,898,362
Present Worth $23,781,785
Capital costs include design and installation of air sparging wells, installation of
the ozone generator and compressed air delivery system, installation of the
compressed air/ozone piping system, installation of vapor extraction wells,
installation of vapor extraction equipment, installation of the vapor extraction
piping network and implementation of an operation, monitoring and maintenance
program. A thermal oxidizer/scrubber unit as the off-gas treatment is included in
these costs. Three systems (one for each plume area) are also included. Cleanup
time was estimated to last approximately eight years. Institutional controls would
also be implemented.
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The estimated costs of the Containment by Air Injection Wells alternative for
the TCE in the Alluvial formation and the west-PCE plume only are as follows:
Capital Costs 51,331,263
O&M Costs $ 2,445,420
Present Worth $ 3,756,953
Capital costs include design and installation of air sparge wells, installation of the
compressed air delivery system, installation of the compressed air piping
networks, and implementation of an operation, monitoring and maintenance
program. This technology is considered innovative and would require a
treatability study to determine the location and number of sparge wells and the
length of time for remediation. For cost estimating purposes, 10 years of
operation was calculated including equipment for two sparging systems.
Institutional controls would also be implemented.
C. Modifying Criteria:
1. State Acceptance
The state of Nebraska has expressed its support for the Institutional Controls and
Limited Action, Ex-situ Air Stripping/Surface Water Discharge and Ex-situ
Carbon Adsorption/Surface Water Discharge alternatives. The state does not
believe the No Action alternative provides adequate protection of human health
and the environment. The state does not support Containment by Air Injection
Wells as it does not address the Upper Ogallala formation. The state believes that
the In-situ Oxidation/Vapor Extraction and the In-site Air Sparging/Vapor
Extraction alternative are too costly.
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 on the other
alternatives considered. Virtually all the comments received stated that EPA's
preferred alternative was too costly and unnecessary as no one was currently
being exposed to the contamination in the ground water since the city of Ogallala
established a new well field north of the city. The EPA considered all the public
comments and has selected the Institutional Controls and Limited Action
alternative with monitoring as the remedy. The monitoring will confirm whether
or not the ground water can be restored within a reasonable length of time under
existing conditions. The EPA's responses to the public comments are included in
the Responsiveness Summary section of this document.
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XL SELECTED REMEDY
The EPA has selected the following actions to address the ground water at OU1 of the
Ogallala Site.
A. Description of the Selected Remedy
EPA has selected Institutional Controls and Limited Action to address the contamination
within OU1. The major components of the selected remedy include:
• The continued operation of the ground water extraction and air treatment system,
including the associated ground water monitoring, located at and near the American
Shizuki Corporation facility, until either verified contaminant levels have been attained
consistent with this ROD, or until contaminant levels have been reduced to MCLs and
EPA, in consultation with NDEQ, has determined that this response action is complete.
Once the system is no longer operational, quarterly sampling at this facility will be
required for at least two years to verify attainment. Operation of ASC's purnp & treat
system could be resumed if contaminant levels increase. Quarterly ground water
monitoring of this monitoring well network will verify completion and monitor the levels
of contamination present in the extraction wells. Monitoring of the ground water levels
to determine the capture zone for each extraction well will also be conducted and
reported. The purpose of this component of the remedy is to ensure removal of a
potential ground water contamination source.
• Implementation of an institutional control in the form of a city of Ogallala ordinance and
deed notices/restrictions on selected property which will control the use of the ground
water for human consumption in areas where contamination is present above the MCLs.
This ordinance will prevent the future installation of ground water supply wells within the
areas of contamination and will be enforced by the city of Ogallala. The purpose of this
component is to reduce potential exposure to contaminated ground water.
• An inventory of all existing ground water wells within or near the area of contamination
to identify all domestic, irrigation, industrial and monitoring wells in the city of Ogallala
and east of Ogallala impacted or potentially impacted by the contaminated ground water.
This survey will include the existing well logs, location, depth, use and existing analytical
results from each well present in the city of Ogallala and downgradient in the migration
path. Every newly identified well will be sampled for the full suite of volatile organics.
If the analytical results indicate that the ground water is contaminated, the well owner
will be notified. If the well is used for consumption, the property owner will be notified
and offered an alternate water supply. This supply could be one of several options that
could include: 1) connection to the municipal water supply; or 2) a whole treatment
system which is effective in removing the contaminants. The property owner will be
provided bottled water until the hookup or system installation is complete. This
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component of the remedy serves to identify all wells located in areas where ground water
contamination exists or potentially impacts the quality of ground water, provides a source
of ground water for drinking to any impacted parties and prevents exposure during the
remediation of these plumes.
The development and implementation of a ground water monitoring and maintenance
plan to ensure that public use of the contaminated ground water does not occur prior to
attainment of MCLs. This plan would include the ground water sampling and analysis
and inspection of selected wells identified in the areas of contamination and
downgradient from the contaminated zones. Additional monitoring wells may need to be
installed for the purpose of identifying the extent of the contaminated plumes. There are
several existing ground water monitoring wells that have been installed in Ogallala. The
EPA, in consultation with NDEQ, will evaluate the location, depth and the chemical
information from each of these wells to determine which wells will be included in the
ground water sampling program. This component will allow EPA to determine if the
remedy is be protective of human health and the environment.
An evaluation of the ground water monitoring data will be conducted to determine if
source areas or zones of unacceptable high levels of contaminated ground water exist and
whether additional contingency response actions are necessary to insure that ongoing
natural attenuation processes will restore the aquifer within 20 years. This evaluation will
focus on the ground water monitoring results and will assess changes in the plumes due to
natural biological and physicochemical processes that may effect the levels of
contaminants in ground water. Sampling data which indicates contamination is present in
the ground water above the lO^or one excess cancer in 10,000) cancer risk range may
trigger additional response actions. Once eight quarters of ground water data are
available, EPA will review and determine the rate at which the contamination plumes are
being attenuated. If it is determined that natural attenuation is occurring at a rate
sufficient to control the migration of this plume then no contingency response actions will
be needed. If this evaluation determines that additional sources are present or that the
intrinsic attenuation process is inadequate to address the levels of contamination, then
further contingency response actions will be needed. The source area for the vadose zone
CT contamination has not been identified. The source area for the PCE/TCE plume in
the Alluvial formation may have been addressed by ASC. There may be additional
source areas which could be identified during ground water monitoring that will be
implemented under this ROD.
The selected remedy will provide for better understanding of the vertical and horizontal
extent of the ground water contamination and provide EPA with data necessary for
determining, on a periodic basis, whether natural attenuation is occurring at a rate that is
sufficient to control the migration of the plume and provide for remediation of the plume
within 20 years. If the data demonstrates that the plume is continuing to migrate and that
natural attenuation processes are not occurring at an acceptable rate, additional
#
36
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contingency work would be required. Ground water monitoring will continue during the
first evaluation period.
According to information obtained from EPA's Technical Protocol for Evaluating Natural
Attenuation of Chlorinated Solvents in Ground Water. EPA/600/R-98/128, September
1998, the EPA will consider natural attenuation to be occurring at this site in an
acceptable manner and rate if:
1. An examination of ground water chemistry identifies conditions that are favorable
for the occurrence of biodegradation (Table 2.3).
2. An examination of ground water chemistry identifies the presence of microbially
produced daughter products for TCE and PCE.
3. A reduction in concentration of PCE and TCE along the flow path downgradient
from the suspected source areas occurs.
4. There is an increase in concentration of cis-1,2-DCE and VC and the appearance
of ethene along the flow path downgradient from the suspected source areas.
5. There is a decrease in the amount of oxygen, nitrate and sulfate in the source
areas and downgradient from the suspected source areas (according to Interstate
Technology and Regulatory Cooperation's document Natural Attenuation of
Chlorinated Solvents in Ground Water Training Course Notebook attached as
Table 23).
6. There is an increase in the amount of iron"2, methane, acetate and the presence of
high organic carbon downgradient from the suspected source areas.
The EPA will evaluate the overall protectiveness of the remedy based upon additional
monitoring data. A detailed sampling and quality assurance plan to perform the ground
water monitoring will be prepared and will include sample locations, frequency,
procedures, analytical methods and documentation. New monitoring wells may be added
to the existing network as the contaminated plume migrates or if further definition of the
plume is required. Sampling modifications, including modifications in the sampling
location and frequency, may be made during the implementation of the selected remedy.
The ground water monitoring data will include the following:
1. Monitoring of ground water elevations and piezometers from all the monitoring
locations within and near the Ogallala Ground Water Contamination Site, which
would include the evaluation of ground water flow and solute transport conditions
so that directions and rates of ground water flow are identified.
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2. Defining the distance between the source of contamination and any
environmentally sensitive receptors located down gradient.
3. A comparison of contaminant transport rates to the rates of natural attenuation.
4. For ground water samples in zones where biodegradation is suspected, the
following parameters will be monitored: pH, specific conductance, temperature,
VOCs (including, but not limited to TCE, PCE, CT, and daughter products),
sulfate, sulfide, chloride, redox potential, metabolic gases including methane,
ethane and ethene, dissolved oxygen, nitrate, nitrite, total organic carbon and
iron(II). For the outer areas of the plume, a reduced list will be sufficient.
5. Determining the rates of biodegradation of contaminants estimated using water
chemistry or approved EPA laboratory methods.
The analytical results would be used with aquifer mathematical models to evaluate the
rate of natural attenuation and the migration of contaminants. If monitoring results
indicate that natural attenuation is not occurring at a rate sufficient to prevent the spread
of the contaminant plumes, additional contingency work will be required.
If monitoring determines that additional sources of contamination are present, source
characterization will be required. EPA's limited soil investigation and NDEQ's soil gas
investigation (August 17, 1990) suggest that potential sources may exist.
• The Remedial Action Objectives will be attained through control of exposure to the
contaminated ground water and through the existing natural degradation processes. The
EPA, in consultation with NDEQ, will evaluate the ground water data to determine that
the concentrations of the contaminants within these plumes are decreasing to acceptable
levels, that the plumes are not migrating and that no additional sources are contributing to
the aquifer. In addition, EPA would also verify that institutional controls are effective in
preventing exposure to these contaminants while these plumes attenuate.
B. Summary of the Estimated Remedy Costs
For the Institutional Control and Limited Action alternative the estimated costs for the
TCE in the Alluvial formation (FS Report for Plume 1), the TCE/CT in the Ogallala formation
(FS Report for Plume 4) and the west-PCE in the Alluvial formation (FS Report for Plume 3) are
as follows:
Capital Costs $ 313,670
O&M Costs $ 1,491,953
Present Worth 51,805,623
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The capital cost estimate includes design, oversight (combined engineering and oversight
costs estimated at $109,861), the installation of 20 additional monitoring wells (5143,809 for
installation costs) and institutional controls (estimated at 560,000).
. The O&M cost estimate includes the cost for analysis of ground water samples (510,981
per year), sampling and well maintenance expenses (590,654 per year), cost for bottled water
(511,926 per year) and the cost for five-year reviews (545,000 cost per review). The time
required to achieve cleanup standards was estimated to last from 16 years for Plume I and Plume
3 and 28 years for Plume 4.
A 5% discount rate was used for calculating total present worth costs. All costs reported
in the ROD are estimates, with an accuracy expectation of+50 to -30%. These estimates will be
further refined as the remedy is designed and implemented. The EPA anticipates that the
selected remedy will not exceed these costs as the cost estimates were developed independent of
one another, and EPA believes that some savings on costs will be achieved through the
development of one design for all three plumes. The cost estimate also includes the installation
of 20 monitoring wells which may all not be required. The cost estimate limits analytical costs
to 510,981 per year. The EPA believes that these costs could be exceeded, but that the overall
O&M costs are within the accuracy range of+50 to -30%.
C. Expected Outcomes of the Selected Remedy
The MCLs are the cleanup goals for these three plumes which define OU1 and will meet
ARARs. The time frame for attaining MCLs is expected to be less than 20 years, with the goal
of 10-20 years for the west-PCE plume in the Alluvial formation and the TCE/CT plume in the
Ogallala formation. The goal for attaining MCLs for TCE in the Alluvial formation is 20 years.
Five-year reviews will be completed during the lifetime of the project. The achievement of
cleanup levels is expected and, if attained and verified, all restrictions will be removed allowing
for unrestricted use of the ground water.
XII STATUTORY DETERMINATIONS
Pursuant to CERCLA Section 121, as adopted in the NCP at 40 C.F.R.
§ 300.430(f)(5)(ii), EPA must select remedies that are protective of human health and the
environment, comply with applicable or relevant and appropriate requirements (unless a statutory
waiver is justified), are cost effective and utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maximum extent practicable. In addition,
CERCLA includes a preference for remedies that employ treatment that permanently and
significantly reduces the volume, toxicity or mobility of hazardous wastes as a principal element.
The following sections discuss how the selected remedy meets these statutory requirements.
39
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Protection of Human Health and the Environment
The selected remedy, Institutional Controls and Limited Action, will protect human health and
the environment by: 1) using institutional controls to limit exposure to the contaminated ground
water at the site; 2) identifying all users of the ground water which are impacted or potentially
impacted by the ground water contamination; 3) testing of the quality of such users' ground
water, and by providing a source of clean drinking water to a user, if necessary. In addition
evaluation of quarterly ground water data will enable EPA to determine if natural attenuation
processes are occurring at a rate which is sufficient to restore the ground water to all beneficial
uses within a reasonable time frame. If the natural processes are not effectively eliminating the
contaminants in a timely manner or if the plume is found to be migrating, additional response
actions will be required. If, EPA determines at any time that a source area exists, additional field
work to investigate, characterize and remove the source of contamination to the ground water
will be undertaken under appropriate CERCLA authorities. Implementation of the selected
remedy will not pose unacceptable short-term risks or cross-media impacts. The EPA anticipates
that exposure levels will be reduced to protective ARARs within EPA's generally acceptable
cancer risk range of 1Q-4 to 10 -6 and a Hazard Index of less than 1.0.
Compliance with Applicable or Relevant and Appropriate Requirements
Section 121(d)(2) of CERCLA, 42 U.S.C. § 9621(d)(2), requires that cleanup actions conducted
under CERCLA achieve a degree or level of cleanup which, at a minimum, attains "any standard,
requirement, criteria or limitation under any federal environmental law...or any promulgated
standard, requirement, criteria or limitation under a state environmental or facility siting law that
is more stringent than any federal standard...[which] is legally applicable to the hazardous
substance or pollutant or contaminant concerned or is relevant and appropriate under the
circumstances of the release or threatened release of such hazardous substance or pollutant or
contaminant..." The identified standards, requirements, criteria or limitations thus adopted from
other environmental laws, which govern on-site cleanup activities at this site, are referred to as
"applicable or relevant and appropriate requirements" or "ARARs."
For on-site cleanup activities under Section 121(e)(l) of CERCLA, EPA is not required to obtain
any federal, state or local permits for actions conducted on-site, complying only with the
substantive (non-administrative) requirements of the identified federal and state laws On the
other hand, for cleanup activities that will occur off-site, both the substantive as well as the
administrative requirements of such laws will apply to cleanup activities. This section identifies
the ARARs which will apply to the on-site cleanup activities.
The selected remedy of Institutional Controls and Limited Action will comply with all ARARs
Potential ARARs are presented below:
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Chemical, Location and Action-Specific ARARs include the following:
• Safe Drinking Water Act of 1986, as amended (42 U.S.C. § 300 et seq.). Primary
Drinking Water Standards are established in 40 CFR Part 141. The Safe Drinking Water
Act's MCLs are health-based standards for chemicals that may be found in public water
supplies. The NCP requires consideration of MCLs, where they exist, as relevant and
appropriate requirements for ground water cleanups when the aquifer is a current or
potential source of drinking water. MCLs for the chemicals of concern are relevant and
appropriate for establishing cleanup standards to be met during implementation of the
remedy.
• Resource Conservation and Recovery Act (RCRA) of 1976, as amended (42 U.S.C.
§ 6901 et sea,). The criteria set forth in 40 CFR Part 261 will be used to determine if solid
wastes excavated, created through treatment or otherwise generated during the
implementation of the remedy are hazardous or non-hazardous. The methods for
determining whether a solid waste is hazardous are set forth in 40 CFR § 262.11. All
generators of solid waste are required to determine if a waste is hazardous. Wastes
determined to be hazardous will be managed in accordance with the rules applicable to
hazardous wastes. The accumulation of hazardous waste on-site is addressed by 40 CFR
§ 262.34. RCRA regulations that apply to facilities for the treatment, storage or disposal
of hazardous waste were determined not to be applicable or relevant and appropriate at
this site.
• R.S. Nebraska 46-602(1): The substantive requirements are applicable or relevant and
appropriate as EPA would like the location of any of the monitoring wells or remediation
system to be listed by the Nebraska Department of Water Resources to ensure, for the
duration of the project, that other wells which might interfere with cleanup or monitoring
are not drilled near remedial action wells.
• Water Well Standards and Contractor Licensing Act: The substantive standards of
Title 178 relevant to ensuring that those engaged in well drilling and well construction
are qualified to do so are applicable.
• Permits to Withdraw Water: As discussed above, under Section 121 (e) of CERCLA,
EPA does not require permits from the Natural Resources District (NRD) or from a state
or local agency for placement or operation of monitoring or pump-and-treat wells on-site
However, substantive requirements will be followed to the extent practicable in carrying
out cleanup activities. Ground water information collected during the cleanup will be
made readily available to state agencies and the NRD.
> Ground Water Quality Standards and Use Classification: Title 118, chapter 4,
establishes numerical standards for contaminants introduced to ground water by human
41
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activity. Title 118, Appendix A, Step 8, establishes a method for determining preliminary
cleanup levels for the different classifications of protected ground water.
Cost-Effectiveness
The EPA believes that the selected remedy is cost-effective in that it is designed to control direct
contact by inhalation and ingestion of ground water contaminants from the site. The NCP at 40
C.F.R. § 300.430(f)(ii)(D) requires EPA to determine cost-effectiveness by evaluating the cost of
an alternative relative to its overall effectiveness. Effectiveness is defined by three of the five
balancing criteria: long-term effectiveness, short-term effectiveness and reduction of toxicity,
mobility and volume of the waste through treatment. The overall effectiveness is then compared
to cost to ensure that the selected remedy is cost-effective.
The estimated present worth cost of the remedy is $1,805,623. Of the alternatives evaluated by
EPA, only the No Action alternative was less expensive. The most expensive alternative
evaluated was In-situ Air Sparging/Vapor Extraction which was estimated to cost 523,781,785.
The Extraction Wells/Deep-well Injection alternative was estimated to cost $5,770,742. The
EPA realizes that the cost for the selected remedy will increase if additional monitoring wells are
needed or if the ground water fails to meet MCLs within the anticipated time frame and
additional remedial actions are required. The EPA believes that the selected remedy,
Institutional Controls and Limited Action, is the most cost-effective alternative at the present
time and will be protective of human health and the environment.
Utilization of Permanent Solutions and Alternative Treatment (or Resource Recovery)
Technologies to the Maximum Extent Practicable
The EPA has determined that the selected remedy represents the maximum extent to which
permanent solutions and treatment technologies can be utilized in a practicable manner at the
site. Of those alternatives that are protective of human health and the environment and comply
with ARARs, EPA has determined that the selected remedy provides the best balance of trade-
offs in terms of the five balancing criteria, while also considering the statutory preference for
treatment as a principal element and considering state and community acceptance.
The selected remedy includes treatment of principal threats in a portion of the site where the
ASC system is in operation. It is the goal of the selected remedy to reduce the levels of VOCs
present in the ground water to MCLs by allowing natural attenuation processes to address the
residual contamination and thus remove the principle threats present at the site. The selected
remedy satisfies the criteria for long-term effectiveness by allowing for the removal of TCE,
PCE and CT contamination in ground water by natural attenuation processes, if found to be
occurring at a rate sufficient to restore the plume. Monitoring the location of the plumes within
the aquifer and evaluating the progress of the remediation on a quarterly basis will verify the
long-term effectiveness of this remedy. This remedy is easily implementable as compared to the
other alternatives evaluated, is the least costly and is acceptable to the state and the community.
42
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The time frame to achieve the MCLs using this remedy was estimated to be 20 years. The time
frame to achieve MCLs using an extraction and treatment remedy was between 10-15 years.
Based upon current information, EPA has determined that the cost for an extraction remedy that
utilized treatment to the "maximum extent practicable" were excessive for this site, and believes
the selected remedy will achieve site cleanup, utilizing existing natural attenuation processes.
Preference for Treatment as a Principal Element
The principal threats posed by the site are TCE, PCE and CT in the ground water. For the west-
PCE plume, there is an ongoing response action currently addressing the suspected source area.
For the TCE in the Alluvial formation and the TCE/CT in the Ogallala formation, the source
areas have not been definitively identified. An evaluation of the ground water monitoring
information will allow EPA to determine if the residual contamination in the aquifer is being
address by natural attenuation processes. The institutional controls will help prevent exposure to
ground water contamination. If it is determined that the natural attenuation processes are not
halting the migration of the plume or if the natural attenuation rate is determined to be too slow,
then additional response actions(s) will be required. These additional actions could include
source investigation and removal, or innovative technologies to address unacceptable levels of
contamination.
Five-Year Review Requirements
Because this remedy will result in hazardous substances remaining on-site above levels that
allow for unlimited use and unrestricted exposure, a review will be conducted at least every five
years after initiation of remedial action to ensure that the remedy continues to provide adequate
protection of human health and the environment.
XIII- DOCUMENTATION OF SIGNIFICANT CHANGES
The Proposed Plan was released for public comment in May 1998. It set the Preferred
Alternative as:
• Soil source area characterization
• Continued operation of ASC's air stripping treatment system for the west-PCE
plume in the Alluvial Aquifer
• Treatability Study Reductive Dechlorination by the state of Nebraska for the east-
PCE Plume in the Alluvial Aquifer
• Ex-situ air-stripping with surface water discharge for the TCE & CT plume in the
Ogallala formation and the TCE plume in the Alluvial formation
The EPA reviewed all written and verbal comments submitted during the public comment period
and has determined that a significant change in the remedy is warranted. The EPA believes the
43
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significant change as outlined in this ROD could have been reasonably anticipated based upon
information originally presented in the Proposed Plan and the RI/FS Reports.
Operable Unit #01 (OU1) remedy will consist of the following components:
• Sampling and monitoring will be conducted to verify the effectiveness of and refine the
duration estimates for natural attenuation for the TCE and CT Plume in the Ogallala
formation, and the TCE Plume in the Alluvial formation.
• Institutional Controls in the form of a city of Ogallala ordinance and deed
notices/restrictions on selected property which will control the use of the ground water
for human consumption in areas where contamination is present above MCLs.
• A survey of wells installed in Ogallala including all private, irrigation, monitoring and
industrial wells will be conducted. The ground water well locations identified in the
water well survey will be evaluated to determine the sampling locations to be included in
the ground water monitoring program.
• Restoration of the aquifer through natural attenuation.
• The continued operation of the ASC/TRW treatment system until EPA, in consultation
with NDEQ, agrees that the target levels, i.e., levels at which natural attenuation will
achieve MCLs within acceptable time frames, is complete. Once the target levels have
been attained, ground water monitoring will continue quarterly for at least two years to
determine if the levels have been achieved. Operation of the system will resume if levels
of VOCs increase during this two year period.
44
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Decision Summary
Contents
List of Tables:
1. Municipal well data, 1989-1995, 2 pages
2. Chemicals of concern from Municipal wells.
3. Monitoring well data, October 1991-November 1993, 2 pages
4. Monitoring well data, October 1995
5. ASC and OE data, October 1991 -November 1993
6. ASC and OE data, October 1995, 2 pages
7. Subsurface soil data, October 1995, 2 pages
8. Subsurface soils chemicals of concern, 2 pages
9. Chemicals of concern for sediment
10. Chemicals of concern for Nebraska monitoring wells
11. Chemicals of concern for EPA monitoring wells
12. Chemicals of concern for PRPs monitoring wells
13. Chemicals of concern Nebraska monitoring wells, October 1991-November 1993
14. Chemicals of concern PRPs wells, October 1991 -November 1993
15. Chemicals of concern for surface water, October 1995
16. Concentrations of Ogallala site contaminants, 3 pages
17. Carcinogenic Risks
18. Noncarcinogenic hazard indices
19. Ground water remedial action objectives
20. Appendix E, Ogallala well inventory, 7 pages
21. OEMI's 1998 data
22. Feasibility Study's Tables, 12 pages
23. Tables for Evaluating Natural Attenuation of Chlorinated Solvents, 2 pages
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n.!fi9
7 of 19
Odl 19
I7o( 19
1 of 19
OoM9
1 nl |9
2 nl 19
1 ol l<)
(,(l I
('uiurnlnlinn
("R/I»
Nl)
2K
Nl)
Nl)
Nl)
Nl)
Nl)
Nl)
NO
0 2 JO 4
Nil
KJ! t
Nil
Nl)
'• .I.
^^•WBW^BV
60- 1
*i>fiftii
Oof 1')
1 nl (9
Oof 19
lot 19
II .,* in
Oof 19
Oof 19
1 of 19
Onf |9
(Mif 19
Oofl9
OnC IV
Ouf 19
"
(J 1
(°on(cnlr»linn
("Kl)
NM
Nl)
Nl)
Nl)
NO
Of,
Nl)
Nl)
Nl)
Nl)
Nl)
0.4-21.7
Nl)
Nl)
Nl)
Nl)
NO
-*••»— ••••—••^
r.j I
*l)rltcl
Onf II
Oof ||
1) ol 1 1
0 of 1 1
0 (if 1 1
lorn
0 oil 1
Oof II
0 of 1 1
Onf II
f) Ikf 1 1
1 of 1 1
0 of 1 1
(1 of 1 1
0 nl 1 1
I) «'l 1 1
Ool II
<•<••««•«»>••
11
(4 1
Conctnlfillon
<.UR/I)
Nl)
NO "
O.J-O.M
0.20.J
0.7-2.$
OJ3.»
0.4
Nl)
NO
Nl)
0.3-2.1
IO.L2IO
Nl)
I.J
1
Nl)
'• ' " 1
•V^MHWHM^
44 1
fin.f».i
Oof 19
OoflT
6 of 19
2 of 19
6 of 119
16 or 19
lor 19
OoM9^
Oof 19
Oori9
10 or 19
19 or 19
Oof 19
ur 19
lot 19
Oof 19
Oof 19
^MMHM^M
1
64-2
Contcnlrtllon
(U8/1)
Nl)
NO
NO
NO
0.4
-------
N • . .
Nebraska l,,,,,H,,,en, of Kn
Municipal Well I)a(a
1989-1995
Oqallnla, Nebraska
^
' hrmlcil
Urn/me
( lilnmnielhane
I.I Dkliliin.elh.ine
1.2 Dicliliiicicttiine
' • ---...
U-Dichlmoeihylene
«••» 1,2-Dichloroelhylene
1 Iliylben/ene
Slj-icne
jltlritchlnroelhyleiie
If uliirne
1.1.1-liichloiocih.inc
triililouwlhylene
I .?.« liimelhylbrnKne
v'i')M hlmiile
"i-Xvlcne
•> X \lnir
p-Xylene
1 '
(.'onctn(r«lliin | Ht)tltrl\
("R'lJ
NO
- -
Ml 1
Nl)
Nl )
NO
NO
NO ~
Nl) "
NJ)
Nl)
NO
NO
Nl)
Nl)
NO
i n i
NO
Nl)
—^^VMMM^
NO • Not .feteele.l
-i
"
0 i.l 2
() nf 2
(1 «'( 2
(1 of 2
II i.l 2
0 i.f }
l> nf 2
Onf2
0 i.l ;
(1 nl 2
II nf 2
0 ii| J
Ool2
- 1 .
64 S
Cnncrnliiiion
OlRll
NO
NO
NJ)
NO
NO
NO
NO
NO
NJ)
Nl)
NO
•llrlrtl,
Oof 1
ooi; I
Ouf2
Oof 2
n ni 2
n»n
n,,(2
Ool2
Oof I
Oof 2
NO j Oof 2
NO 0,,I2
Nl) Oof2
Nl)
Nl)
Nl)
— - 1
Oof 2
1
Oof 2 1
(.ft I
('onrriiiriilon
6TJ
*l)fltcli
74-1
ND
NO
Oof
-------
Table 2
Chemicals of Concern
Municipal Well Data
1989-1995
Ogallala, Nebraska
Monlclpil Wttli
19X9 1995
Chtmlctl
llenicne
Chlomintlhine
I.l-Dlchloroelhine
l,M)ichlotiKlti«ne
l.t DIchloKKlhytcnc
cli-I.MXchlnroclhylcnc
rihytbcnrrne
Myitne
Icliiclilnnxlliylene
1 olucnc
I.l.l-Iilchloioelhine
lilclilomtlhytene
1.2,4-rrlmtlhylbtnifnt
Vinyl CMmide
ni-Xylcnc
,i X)lcnc
p-Xyltne
HlghMl
Delected
Concenfrillnn
(ue/l)
04
21
094
0)
25
19
04
0)
24
1 )
21
210
OS
1 1
1
04
05
Frequency
of Detection
]•
• 1
5'
2'
7*
2')
•1
j
MCL - Mwlmum Conltmlnin. lx,«l« w.« ohl^lntd from CFR Titk 40. P«t 141. Subp«t II. « .«d I, MY I, 1994.
RI$k.B««d ConwntTiilon. foi T.p W.ter weie obulned f.om (he U.S. EB»l«mmenUl Pmleelwn A|tncy. Re|lon III, Ml
Phllldelphli, PA 19107 (I99S)
th«»« St.
-------
Nebraska Departmem environmental Quality
Monitoring Well Data
October 1991. November 1993
ORallala, Nebraska
o
NDKQ
NW-1B
CMttNlrtlln
uhon TeUKhlorlde
IMchlomcUtylene
il-1.2 Oichlontclhylene
iwu.1.1 Dichloioclhylene
I.I liichlornclhitM
richloiorlhylene
inyl ( hli'iide
>ltnei, (mof p)
-------
ML . ~
Nebraska Department of finvironmenlal Qualify
Monitoring Well Data
October 1991 - November 1993
Ogallala, Nebraska
•--———_—«-_»»__»_«___,____
.
MHIII_«MMM_M_»___WM~_~»1»__M_B
C htmlril
IcnKne
I iibon Tttmhlofide
l.l-l)ichloruelh_ne
I.l-Dichlorortfiylene
ili-l,7 Dichlorocihylene
i>*ni-l,2-f)ichlorocthylene
IdiKhlomclhylenc
toluene
M.l-llichlimxlhint
iiihlmotlhyleix
Vinyl ( hloiidt
Xylcnri,(mnrp)
i..
NW-JA
( oner nlrilloii
1 1 n
NO
Nl)
Nl)
Nl)
Nl)
Nl)
M.4-414.9
Nl)
Nl)
1010
Nl)
Nl)
NO- NnldctoclCd
----_>____.,,.
NW-JA
Oofl
Oofl
oo"fi~"
Oofl
Oof II
~"ioii'
Uiill
Ooll
5of«
flit(H
Oold
••«-*-•-------,____«•
NDEQ
NW.Jli
C'ontmlrxl.m
KID
i»«f
Nl)
Nl)
Nl)
Nl)
Nl)
1M
Nl)
Nli
4.0-7
Nl)
KID
1 1
NDEQ
NW.Ji
tDflrtfi
"'" —
Ooft
Oofl
Onfl
Oofl
Oofl
Oofl
InfS
Oofl
Oofl
2ofl
Oofl
Oofii
1 in
NDEQ
NW-4
CMttitmifoa
1 ' »— ^^».
NO
ND
Nl)
ND
ND
ND
IIJH17J
1
Nl)
TJii
Nl)
O.i
NDEQ
NVf-4
tOtttttt
>M^^M«m^M
Oofl
Oofl
Oofl
Oofl
Oofl~
Oofl
lofl
lofl
Oofl
lofl~
Oofl
1 of 1
MVW«i««nM^M^
-------
M . . „ .
Nebraska Department «F Environmental Quality
Monitoring Well Data
October 1995
Ogallala, Nebraska
iiMt-I.MMcMmnrlhylnie
NMirl
IttrKhkwtKihylcnc
l.l.l-hiiMoroclhjvtt
I ikhlocuelhyltnt
Vinyl Chlmide
ND - Not dc*t*i!
-------
American Suziici and Ogallala Electronics
Monitoring Well Data
October 1991 - November 1993
Ogallala, Nebraska
1,
Cktmlcil
~""<**'~^^~- • ii I. .
lenrene
( hloroform
I.i-Dichlnmclhtnc
1.7-Dichlortxihylcnc, bint
1.2-Dichloroclhylcne, Inul
lichlomdifluiiinnirihunr
1 (hylbcnrti*
MelhylcneChlmidc
ItlitchlDiixlhylriif
1 nlucne
l.l.l-lrichldtoelhine
Tfichtoroethxknr
Vinyl Chlmiilc
Xylcncj. (o A/ni p|
Xylt fKJ, (tn A/oi p)
Amrrltix Sirukl
AS( IA/B,
o.s-i.t
0.21-40
O.M-I
O.J4-IO.»
0.441.4
102
Nl)
OJO.J
Nl) - NrH dcltcltd
OtilUli Elrtlronlti
MW-i. J\m .JA/B.44. TA/i" "
CnntfNlrtlloil
(«^>
J.240
2.1-J.I
i-io.»
N»
2.«2-2I.JJ/T
Nl)
Nl)
I.O-ll
Nl)
2.1 «J
107
2-IO.M
O.M 1.164
Nil
I0.4H
- -
1
-------
o
s
"m
^ •*
•^ w. g
O 6£ §^ *•
^Jl
a
i
i
u
ll'po*!) 1
3 '
"i
• i
^ •
C
«
*
• *
: "
e
• -
w •
1 "
1 V
j •
\\
* *
S|
1 TOW
1 CoBctilr»fl»i
i'«
.!J
lit
HI
if
I,|
i
If
* i
' £Z -£-_]_ .;_:_ £
•5 | o -5 "5 'SI'S •» 'S -SI-Sl-S i -S -S -SI'S -5
1 i i
| - j
f li ii§ili ij§ tit ii§ g|ji
i ' i
i ;
Si'ci^'Si^Ki^Ki^j^.^ ^ i o ' ' '
•c!«:~"£'= =• e,i o- sfs:* •Sr-5"s"5:'s;'s'^
. e'~J-,e'-e o.-.oie.^.eie.^i^ie ~,«^c
^•£>3ir.l'»-'»ii~'» — ~ ^ — . *, • ' * , ' *"'
¥ ; z . Ji' 53y ! -r ' £ -Civ
!_:. Jv J^'I !| ! J- | S
« ' ^ i 1 ! 1 | 1 •' 1 J '' 1 : 1 g : I • I -l.fi
a
|
i
7
-------
Monitoring Welt Data
October 1995
Ogaliala, Nebraska
n HiMilliclr
I liloiiiuirlliaiir
upper, lolnl
1 4 Dktilorobenrcne
1,1 |)iihloii*lh«nt
UN 1.2 hiMfn/rne
Mrlli)lrnr ( Mmiilr
MM Id, Mill
rlrmlilniiiflhylriic
otiifne
1 I.I liKliliuiKlhniic
hiilil.nKlliylfnr
\ylcnn. tol.il
JAK
Sfivitr
Centtntrailnn
(•e/i)
5 J-5 4
NO
It*
Nl»
0.7K
Nl>
Nl)
Nl)
0.47
9. Ill 0.55
71
Nl)
NU
0.7K 1.5
17
Nil
O.»l J.»
450
.1 A K
Sri »n r
*IMrl 2
Mill 2
Hnl 2
Oi.f 2
1 nl 2
/nl 2
I«I2
H.il2
Nl)
0.51-540
Nl»
Nl)
I54M
Nfbruk.
Dcpt. Roadi
«0(lt(tl
1 nf 2
6 of 2
JiifJ "
Jof2
!o!2
Oo(2~~
Oof2
Oof 2
Oof2~
0«f2
2of2
Oo(2
Oof 2
Oof 2
2of2
Out 2
Oof2
2of2
Tow* A
( aiilry
CoitfilnllMi
I"8"'
7-IM
jii
UM9~
j.iw
e.si-t.w""
«.«
Nl)
~*ii
N» ~ "
Nil
MI-JoT
Nl)
10.2
Nl)
«.*~4«
NO
».J
i.M-iiiM
Town A
CoHiiiry
»Dflftli
2 lit 5
Inf 5
4ol5
Jof5
2 ul$
ioi$
Oof 5
Iof5
Oof 5
Ool 5
3 of 5
Ool 5
lot 5
OoM,
2 of 5
0 nl 1
liif 5
JoM
-------
f - I '-'- f 1 I I i
1 =" 5 5 | £
.
2. S,;2,l8.!2.;2,i2.!2'e;
»•••» i •.•».*,,*., j*. .^i;;;
z r z S'z 2: 2; J •
-- S=-"
- - =..i,= 3. = . = =
S b.SIZ'Z'Z'Z Z,Z;
- « » i «. ; C : S = S ' 5 '
* . =• .. =,.=,,=. 2. 2. ' '
-.. — -« -.-..«,^ 2.^. • 3 3 r1
: : ' i -5
-
i
sr
.
§•3
31
2
3
>
n
=1
P
-------
~
*€ "S s 2
-± a £ t
z
t -
f
«
i
*
t :
i
i
ti
|j
^ i *
T
^i
lii
as •
^ *
O i
;!j
J'«
1 *
i =
"S g
J|S
4
! ;
»
a
:;r
&• 5
g1
••Ptl|IMM3
•Jll duM!
e a
: I
E fi
* »
•
El tl
: -
t: t
'IS
t (•<
e
• • £
•
• i?
i • «
. •;
•
• ,0
• *i
I S
"3
M
W
>
i
; • :
O 6 C . = Z C'OiS'C
i i !
918 * 3 513 !
|j?||2i::j i til
Y"|" -^ i
i i - *
leloto o i c : o o elo
o oioioie.o oioie
! - ! , • . :
' 1
*'z:2 2.2:22.2.22
o eio •••O'Oiotote
, !-, J . : j .
^ Z Z i Z ; J 2 2 2.2.2
* o
-35- r..7. ,?
- - £' | ;-'S • !*
i . ; ' ;
, • i (
. j=
; • S ' *
•—•.£' S
1 • I V — .S! "*.
|;|;J.| |,-s 2: j:3-l
-------
Chemicals of Concern
Surface Soils (0-18")
October 1995
ORallala, Nebraska
lUilum, toUl
i 'mlinlum. lolil
t 'hiumlum, Inltl
Copper, Inlal
1 cad. tnlil
Nickel, lulfil
HlRhfM
Surfitf Soil (IMS")
Cnncfnlrillon
2M1
156
182
IM
96 »
1X6
0074
R III: link-Kurd
Conctnlnllon
Rtililenllil Soil
-------
Table 8
Chemicals of Concern
Subsurface Soils (3-20')
October 1995
Ogallala, Nebraska
Cfeemltil
Hnlum, lull)
( 'hromliim, Inlil
(.II|I|KI. lOllI
l:lhylb«n«ne
l<»d. fulfil
Mklirl, Inlil
Icirtchlorneihylenc
lilchloioethylene
HlRfieil
Siihinll ne^g)
5,500
J90 (VI A cmpih)
2,700
7,«on
400*
1,6110
12
58
Nilurilly-
Occurrlnt
('onctnlrilloni
(n'R'ltl)
700
JO
15-20
NA
15 20
15
NA
NA
C«rtlno|«nlt
CUulflMtlnn
NA
A (Cr Vl>
NA
D
m
A (ttf dust)
R2
R2
Chemical of
Concern
no
no
no
no
no
no
no
1 •«
-------
Table?
Chemicals of Concern
Sediment Data
September - October 1995
la, Nebraska
Chemical
M
Acetone
larimn, tnlal
.'h'Dmiiim, (nut
'opper, inlal
"yanlik
-
-------
Table
Chemicals of Concern
Nebraska Department of Environmental Quality
Monitoring Well Data (NW-1 to NW-4)
October 1995
Oga Main, Nebraska
M Ofl 95
Chemical
llaiimn, total
llentene
lliM2niiylhex)l)Plnhalale
Caibon Ditulfide
Cnibon Telrachlnrlde
< Itlnrofiirm
Chlnuimclhane
.1 nkliliimtthflne
l,2-f)klil
no
no
no
ye$
•
no
yes
yes
CarclnoRenic Clanllicalinn obtained f.nn, the l( s FnviNmmcnM P,0|ecilon Agency's. ln,fgn,,
-------
Table
Chemicals of Concern
Environmental Protection Agency
Monitoring Well Data (EPA-I to EPA-N, EPA-16)
October 1995
Ognllala, Nebraska
IJ-Otl-45
Chemical
Aceliine
llatium, Inlnl
llenrene
lli<(2 1 (l.yllicxyl) riilhilne
(aibon Phulliilc
Cailxm reltnclilnilde
("htorofotm
( 'hlommelhane
1,1-Dlchloroethane
t.}-l)icliliir
-------
Table 11
Chemical* of Concern
Ogallala Monitoring Well Data (ASC, OE, GA, JK, BOS, NDR, TC)
Oclobci 1995
Ogaliala, Nebraska
16 Orl 95
Chemical
Acclonc
Dnrinm, Inlnl
Hen re lie
Mhiliinnne
' aifrin niitilOde
( lilommtlli/ine
Cupper, loul
l,4-l>iclihnolien7ene
I.I Mlrhlmocllinne
n 1,2 •Dichlmotihylenc
riliylbenrriir
ilcltiyleiie ( liloiiilr
lluktl, loial
lelinthlnioelliylerie
illume
.1,1 liicliloiotlhane
ii(lilo!oelh)lrne
Xylenej, lolal
MlRhMl
llrlrrltd
Cnncrnlralinn
(i'tt/1)
I'M)
321
660
24
12
OM
If
0 Id
nn
7 5
V0.»
0^2
202
71
.VIII .
OR7
f,7
5.400
1 nliiitMnry
CniKimlnnnl
y«
no
no
ye<
no
no
no
no
nil
no
no
>"
nn
no
V"
no
no
nn
Carcinogenic
ClMilllrillnn'
1)
NA
A
NA
MA
c:
NA
112
<:
i>
I)
112
A (ief diiM)
1)2
1)
1)
112
D
MCI.
(UK/I)
NA
2.000
J
NA
NA
NA
1,500 (At.)
NA
NA
70
700
, NA
too
J
l.ono
200
5
10.000
Cnnrtnlrallon
for Tap Wttcr
3.700
2.600
OJ6
1.900
1,000
14
1.500
044
810
At
1.100
4 1
7.10
1 1
750
1.100
IA
12.000
Chemical or
Concern
Illl
no
ye»
no
no
no
nn
nn
nn
nn
yei
no
nn
yes
no
nn
yei
no
NA • Ntil ivniliblc ot not upplicihle
('•iclnogrnic ("lauHtcilimt nlil,iincd liom Ihc II S rnvlinmiicnUl I'mlecllim Aptncy'i, Inlefrnted ffltK Information Syiltm (IRIS 1996).
Common Uboutory conlamininii cnniidetcd by ihc U S l:nvi(onmrnl.il I'niicciiim Agency Incliiile: icelnne, 2-hulinnne, methylene
clllniiilt, Inliicne mil Itic (ililhlUlc cslcn (I-'I'A I9R9)
MCI. • Maximum Cnnlmiiinnnl Itvcli were nliuincil finiii CI-'R lillc 40, Pm( 141, Suhpirt H. (} tnd I. Inly I, 1904.
Al. • Aclinn I cvclt were <>hl.iineil fn»n Cl II lillc 411, I'nil 141, Suhpjil II, (I mil I, Inly I, 1994
HKk-M,veil CiincrnlrMliHM for Fnp Wakr were olil.iiiieil linm Hie tl S I nvIinnmcnMl 1'iolecilon ARtncy, Rcplon III. R4t CbeMnul Si..
;i. I'A I'H07(I')OJ)
-------
Table t
Chemicals of Concern
American Suzuki (ASC) and OgaHala Electronics (OEMI)
Monitoring Well Data
October .1991 - November 1993
OgaHala, Nebraska
Of 1-91 toNov-93
Chemical
llcnjeiie
( lilimifonn
1:1 Diihloruelhane
I.I Diclilonielhylene
I.MHrhloroelhylene. Irani
1.1 Hicltloioclliylene, total
1 liclilimiclidiiniomrlhene
1 Ihylhenrene
Mcihylene Chloride
etraclilnioelhylene
Inliiene
I.I.I -liiclilonielhine
1 riihlmnelliylene
Vinyl ( lilntide
V) If lie*, (o A/or p)
Xylenes. (m A/orp)
ND-N
ASC
Illghctt
Concentration
Nl)
Nl)
866
033
921
4
278
ND
29
40
i
109
61
2
Nl)
03-0.5
91 detected lieu lh>
OKMI
lllRheM
Concentration
(MR/I)
(.0
i I
10')
Nl)
2 1.33 (average)
Nl)
Nit
12
NO
63
Ifl flfi
I.IM
Nl)
104*.
04
Laboratory
Contaminant
no
no
nu
no
nn
nn
no
yes
no
yes
nn
MO
mi
Carcinogenic
Classification
A
1)2
C
NA
NA
NA
t)
02
m
i)
i)
112
A
1)
1)
MCL
•,
NA
NA
100
70(cis) - KHHIrans)
NA
700
NA
5
1,000
200
5
2
10.000 (total)
10,000 (total)
Rlsk-Based
Concentration
for Tap Water
n IA
015
820.
0.044
120
55
390
1300
1 1
I i
750
1.300
i £
0019
12,000 (mined)
12,000 (mixed)
ASC
Chemical of
Concern
no
yes
no
no
yes
yei
t>
yej
no
no
OEMI
Chemical of
Concern
yes
yes
no
no
no
no
yes
no
yes
no
no
no
NA • Not available or not applicalile
raiclnogenle ClaHlficalion nMained Horn (lie tl S environmental r.olecllnn Agency's, /^jrafcrf K,,k Information System (IRIS 1996)
( ommnn laborao.y contaminant, consiU'rd by the U. S i:nvirnnmenlil Protection Agency Include: acetone. Mulanon.. nxthylene
chloride, toluene and the pliihalati esters (HPA 1989)
MCI. - Maximum Conlimlnant Uvels >verr obtained from CFR Title 40. Part 141. .Suhpwi!). 0 and I luly I 1994
Rish-Rased Concentrations for Tap Water were obtained from the U. S. HnvironmenUl Protection Apency. Region III S4I Chulnul SI
Philadelphia, PA 19107 |I'W) ''
-------
Table /V
Chemicals of Concern
Nebraska Department of Environmental Quality (NW-I to NW-4)
October 1991 - November 1993
Ognllala, Nebraska
__ __ — •— — «^— .
Otll99lloN«ivHM
Chtrnlcil
»—«———— — ~—
llen/ene
CmbonTeliichlnilde
I.l-Dichlnioelhane
1,1 DichloMKlhylene
cij-1,2 Dichloioelhylene
inns-1.2 I'ichlniotlliylcne
IcIoclilnriKlhylfne
Toluene
l.l.l-lildiloriKthitie
Ilicliliiinflhylrnc
Vinvl ( hlniidc
Xylcnes. (m or p)
Highest
DtttcUd
Contenlr«(lnn
(U|>/1)
inn
2)
26
702
64
4949
34
4*49
3
04
(•'rtqutnty
of l)f iff lion
i,*
\i •
III"
211
m
"
A'.
R"
4\
OH
IK
;x
29
tibnriloiy
Conliffllmnl
tin
no
no
no
no
nn
no
vtt
'
no
no
nn
mi
,———•—
Cirtlnofjenlt
CUuineitlon
A
112
C
c
o
NA
112
I)
1)
112
A
D
MCL
5
5
NA
7
70
ion
5
1,000
200
5
2
NA
Rlik-Biitd
Coneenlrtllon
forTipWder
0.36
0 16
110
0044
61
120
I.I
750
1.300
1 ft
0019
520(m)indl,400(p»
Chtmlcil of
Content
•^••^^•••tfNMM*
ye»
y«»
no
yes
y«
no
ye»
no
no
y«
y«
no
PWIwtelphli, TA 19107 (1905)
-------
Table 15
Chemicals of Concern
Surface Water Data
October 1995
Ogallala, Nebraska
rhcmltil
A eel mi c
Illriiim, lolil
ci«-l.2-l)lchlnroelhylene
1 eid. total
I'richlnrnethylene
Vinyl < 'Monde
r
ft 1
<>1\
22
SOI
071
2
••^•••w— i—.^—.
l.tlinrilory
Conlimlninl
yes
no
no
no
no
nn
Ciiclnugrnlc
riiiiirUillon
1)
NA
l>
1)2
112
A
•MM^MMMM
MCI,
("El)
NA
2,0110
70
15 (Al.)
5
2
Nlik-Biird
Concentration
forTipWittr
<"E/1)
3.700
2,600
At
NA
1 6
0019
^— — »««M^
f-henilril of
ronfern
y«
(IRIS 1996).
"'"" "'C " " li"vi"inmtnl" . .* e«
cont.-nm,,,,, Co,,,,,.c,cd hy ,hc U S Envlnrnmo.l.1 P^tec.i,,,, ABcncy lnch.de: .cc,o,>e. 2-buule. mc.hy.ene
chloiide. toluene ind the (ihlhnbie esicit (I:PA 1989)
Al. - Action levels were iihltiined don. fl K lillc 40. IM.J Ml. Snhpirt II. O lud I, Inly I. 1994.
MCI. - Mi.immn Conlaininanl I «vcl% wuc ol.iained from (TR Title 40. Ptrl 141. SulipMl'll. (I «nd I July I 1994
KnUhued Coneenlritions fi.i r.p Waici we.c ohijintd f.nm (he II S linvironn.enlal Pfdeclion Agency. Reiion III 141 Cheilnul Si
Philadelphia, PA 19107 (CMS)
-------
Table
Concentrations of Groundwater Contaminants
Ogallala, Nebraska
Chemical
Concentration (mg/L)
Municipal
WeUs
Ogallala, NE
1989 - 1995
NDEQ
NW-1A
Oct. 1995
NDEQ
NW-2B
Oct. 1995
Chloromethane (Highest) 0.0028
1,2-Dichloroethane (Highest) 0.0003
1,1-DichIoroethylene (Highest) 0.0025
eis-1,2-DichloroethyIene (95% UCL) 0.0013
TetrachJoroethylene (95% UCL) 0.0013
Trichloroethylene (95% UCL) 0.0616
Vinyl Chloride (Highest) 0.0013
Bis(2-ethyihexyl) Phthalate (Highest) 0.0490
Chloromethane (Highest) 0.00071
1,2-Dichloroethane (Highest) 0.00078
1,1-Dichloroethylene (Highest) 0.0065
cis-l,2-Dichloroethylene (Highest) 0.0140
TetrachJoroethylene (Highest) 0.0006
Trichloroethylene (Highest) 0.0960
Vinyl Chloride (Highest) 0.00086
Carbon Tetrachloride (Highest) 0.0330
Chloroform (Highest) 0.0016
Chloromethane (Highest) 0.00058
1,2-Dichloroethane (Highest) 0.0022
1,1-Dichloroethylene (Highest) 0.0048
cis-l,2-Dichloroethylene (Highest) 0.0500
Trichloroethylene (Highest) 0.2900
Vinyl Chloride (Highest) 0.00081
-------
3
2 3
* is 2 ;
5, = a. =• !
i* a rt •
* sr *» ;
[I1 ;
L S *
r ±» a
? R
r 3
r» « — S s Si =
a
3
f ! !
•• X r«
Fl i
•
[ ^
r
r ? 5=^
s» •» " =
Is
7
5
O
c
**»
n
PI
CO
f
ca
c/i
a
•
a a
T S
g =
i s
*
n -
a a
•t s
s
3 Si
*
"
I
i
2
••5
e
i
2
o
s
a
I
o
cn
? 3*
I 1
— a
nn n"1 rh
?^" 33- ?^s
2 |-
o
a f £
n
I-
" as* =.
a ™ JT
^Ȥ
a S" S*
J-al
e
-------
Chemicals of Concern
Ogailala. Nebraska
Soil
None
Sediment
None
Groundwater
Benzene Bis(2-Ethylhexyl) Phthalate Carbon Tetrachloride
Chloroform Chloromeihane 1,2-Dichloroethane
1,1-Dichloroethylene cis-l,2-Dichloroethylene Ethylbenzene
Methylene Chloride Tetrachloroethylene Trichloroethylene
Vinyl Chloride
Surface Water
Vinyl Chloride
Indoor Air
None
Note: Chemicals shown in italics will not be quantitatively evaluated in this risk
assessment. These contaminants will be addressed by the Nebraska Department
of Environmental Quality's Leaking Underground Storage Tank Section.
-------
Ttbfc
>« Gronodwiter Contuninition She
Infaabttoa Risk Dtrmml Rfck Total Risk
Mnrjfopiil Wffa
Monitoring yyt||
NDEO. N^y.jA
• Monftoriny Wy[|
NDEO. NW.fTf
•
Note:
•RME-
AdaitRME*
AdaJtCTZ**
CbOdRME
Chad CTE
AdaitRME
Adult CTE
ChfldRME
Child CTE
•
Adult RME
AdnltCTE
ChUdRME
Child CTE
JKantdial action i
Reasonable Meat
5-ffe-5 2.0e-5 Ue^
7-9«-« 2.0C.6 iJe.?
2-6e-5 Uc_5 56e.7
i-Se-f 5.8e4 3.0^.7
«7- t , _ ,
•/B-J 3Jc-5 * 2Je-^
J^e.5 3Je4 2.3e-7
4-»*-5 1.8e.5 9.9e-7
2-7e-5 9.5e-6 5J«-7
2J«-« 8.7e-5 6.9*4
3-Oe-S 8.8e-6 6.9e-7
I.O»-« 4_____
wnExpasur*, defined as tti*ht+h~*~~~- .
~
7.7e-5
l-Oe-5
3.8e.5
2.4e-5
13*4
1.60.5
ti.Oe-f
3.7
-------
Table 18
Noncarcinogenic Hazard Indices
Ogajlaia Groundwater Contarmnation Site
Ogatlaia. Nebraska
.Vote:
-CTE
IngestiooHI Inhalation HI Dermal HI
TotaJHl
Monitoring \V»M
NDEO.VW.n
Monitorinpxv.n
NDEO. \\V.?p
nutui j\j>Lt"
Adult CTE**
Child RME
Child CTE
Adult RME
Adult CTE
Child RME
Child CTE
Adult RME
Adult CTE
Child RME
Child CTE
" —
U.30
0.14
0.70
0.50
0.53
0.25
1.23
0.82
2.62
1.23
6.11
4.10
_
0.01
0.01
0.01
0.0 1
0.0 1
0.01
0.03
0.02
2.20
0.72
5.92
3.20
— — _
0.01
0.01
0.02
0.0 1
0.02
• o.oi
0.03
0.02
0.10
0.03
0.21
O.II
— — —
0.32
0.16
0.73
-0.52
0.56
0.27
1.29
0.86
4.92
1.98
12.2
7.41
'Tendency Exposure, defined as the arithmetic
expected to occur at a site.
•e, defined as the highest exposure that is reasonably
'ic mean risk or the median risk
-------
TABLE 11: GROUNDWATER REMEDIAL ACTION
OBJECTIVES
Constituent
Remedial Action
Objective
Concentration (ppb)
Carbon tetrachloride
1,1-DCE
PCE
TCE
Vinyi chloride
_
5"
"5"
2
-------
APPENDIX C
IfAW
rilv •IrT'Veido'ction WcllV
Adkins, Meredeih
Adkinson. Bula
Atco (Jeparlmenl Store
'Injection Well
'Supply Well
ASC A
ASC fl
A",r. c
"ASC O" Well
"A!!(; 1." Wrll
Assembly at Ood rhtifrii
Hall/ell Clinic
3 nil? ell, C W
iarnhill. Tpd
JpkiU',. Clinyl
VMis. Groigp
)|
-------
APPENDIX E
• • ....
NAME
Ilimiphiirs Auio
Humphrey, lia
.lensen, Call
Keehan, ilatoid
Kpnlieid. Dob
Kianmi Mikn
Kians, Mrs Aridiph
Ktihttndti Don
1 akesiriV trailer Cnurt
McQueen. Vivian
Major. John
Mlllpl. llplirj
Most, Mis find
tJcili, Pniiy
Nipison
< Jpnll.iia Rpady Mtx
(Hleraiirtpr. Roy
Pclcisoii. F.nrl
Pionpw 1 rails
Hpilz, Mm old
'uzanic. John
Sparle.
Shiolils. laylor
Skiimrr. Rocknry
Smith, Rotjpi
Swanson. Wayne
nphnj. tlwin
Vaccnl MOIISP
Welsh. Mike
West. Omdon
Wi's'in. 1 Ptm;wi
-—-____„_..__
ADDRESS
soo w i$i ' " "
G 19 SJudent Drive
819 Highland drive
601 E "G"
305 W "Q"
RR2
714 E. 4ih
E Highway 30
W 5lh
i?iow" sih
RR1, W P Siieet
708 E 3rd
2107 W Sih
1' O. Box 599 (East of Tow
W 5th
Soiitii of Popiiii b7
2001 W 5iti
1504W Slh
55 6 River Road
RR2
203 E §ih
RR2
1901 W Slh
2109 W 51h
424 Piatieview
405 W "0"
2004 W 5lh
RR 2
1025 § "G"
W 5th
1401 W T'-Strppi
WVJMLUMUM «»MICH
USE
Iriigation
Unknown
Iriigation
Irrigation
Iriigation
Drinking
irrigation
Drinking
blinking
Irrigation
blinking
prinking
blinking
Irrigation
Drinking & litigation
blinking
irrigation
blinking
Drinking
lirigaiion
Di inking
blinking
Disposal of Rain water
Drinking & litigation
irrigation
Unknown
Drinking & irrigation
Drinking
Drinking
None
Unknown
Dunking
drinking & Irrigation
ileat pump
Unknown
rYCUL INVtNTORY
CASINO SCREENED
DEPTH DIAMETER INTERVAL FILTER PACK
|feet| llnchetl (fetl) irwn
90 50.90
2BO - ... - 230.280 ~ ""
Unknown "" "' ....
80
Unknown ~ '
Unknown ~ "'" " ~
250 " •" —
Unknown " '
21 "
Unknown
Unknnwn ""
90
Unknown ~ ' ~
Unknown " '
300 "
48
Unknown
Unknown
.72 320-72.6" 0-720
Unknown
85 ' - . . .
190 ---.-.
Unknown "" '..'
Unknown "
Unknown " "
Unknown
Unknown '"" ~"
Unknown
Unknown ' •
240 '
ieo ;
Unknown
770
60
Unknown
700 45
nr,AWri I Wl'.d
-7
-------
APPENDIX E
NAME
Wilson. .Irihii Druci?
Municipal PrnrtirHlon Weiit
M 1
CO-1
63 1
r.4 1
R4 7
6-1 4
R4 5
(>n 1
7-1 i
Monliorlng Wrrllj
Arneiirnn Rn<7uki
ASC; (MA
ASC DID
ASC 02 A j
ASC 02A7
ASC-OJA
ASC 0311
ASC 04
ASC 0411
ASC 05
A5H" (Hi
ADDRESS
721 E 4lli
Lot 25 80. Bairns sub
City Hah
High School
W 9ih 8 W "§"
W isl & W "C"
Faiigroiinds
No(iRMwy26
Noilhllwyje
SorthHwy6»
P. i iih « E "6'
noi w "o"si
UVJHI. UHU« VY« 1 tK V
USE
Irngation (not usnd)
slock watering
Municipal water supply
Municipal water supply
Municipal water supply
Municipal water supply
Municipal water supply
Municipal water supply
Municipal water supply
Municipal water supply
Municipal water supply
Monitoring
Monitoring
Monitoring
Monitoring
Monitoring
Monitoring
Monitoring
Monitoring
Monitoring
Mrmilminn,
YELL INVENTORY
DEPTH
(reel)
30
120
205
215
1BS
270
209
203
229
715
30
206
20
30
525
195
77
mo
2?
37
CASIN'S™
DIAMETER
(Inches)
IB
is
' is
\4
"' ' W "~
12
ij
14
Unknown
4
4
4 '
. .._
4
4
2
i
2
2
SCREENED
INTERVAL
BO 6."i20
i84-205
190-215
"isf.ier"' •
" 170-185
107-127
178-192
205-210
215-220
i89loT~ " ""
187-702
105-112
135-145
1BO520" """
220-229
~"13P45~ "" "'
"_~ i58-if33
95^9.5
186-206
77-19.8
""22-30
'225-525 "
175-'1§5
7-27
"ieo-ieo
"17-27
27.37
FILTER PACK
... . ,
7-120 ~~
"10-205
7-215
" "60-185
7^2T"" "
' 7-209
ii-202
" 6-229
6 295
177-206
6-20
70-30 ' '
19-58
"1(33.196
4-27
isi-iso
i527
25-37
nn/vwt it WM
•3
-------
APPENDIX E
NAME
OgniialS t-lpcironics
MW-01
MW 02A
MW-02B
MW03A
MW-03F1
MW-05
MVV06
MW-O/A
MW o/n
finnri All PJpririr
MW-01
MW o-i
MW H5A
NW-02B
HW 03A
MUU n ill
nw IM
Jossrlman's Pump & Pantry
1MWO?
MW03
MW05
MW07
MW 1?
Knlti ('inifily Mnint Ynnj
ADDRESS USE
§bi w isi
Monitoring
Moniioring
Moniioring
Moniioring
Monitoring
Monitoring
Monitoring
Monitoring
Moniioring
Moniioring
Monitoring
Monitoring
_ A _ft Railroad Slreet Monitoring
E A ft Railroad Street Moniioring
E "A" S Raiiroad Street Monitoring
E "B5 R 4th " Moniioring
. B a 4IM Monitoring
Alley W"A" Jo Spruce. Nort Moniioring
730E Isisirest
Monitoring
Moniioring
Monitoring
Moniioring
Monitoring
Moniioring
Wmt-Stii Ri
DEPTH
155
18
31
IB
27
18
19
17
17
28
168
162
156
15 7
30
30
118 5
275
1175
292
200
200
200
200
200
200
CASINO
DIAMETER
(Ineheil
2
2
2
2
2
• j - -
2
2
2
2
_
2
2
2
2
2
4
....
4
2
2
2
2 "
2
-._..
•
SCREENED
INTERVAL
22-32 __" '
4BT152
741-17.67
21.79.30.56 " "
7.17-17.43
22".84-25 61
8-18
842-1842
682-16.76"
6 5-16.52
•--2-?7-
"~ 69-164 ~
64-15.8
58-15.2
5(J-^S,3
'19.B-29T
19.B-29 8
Qfl.llfl
97-117
14:29
~ "73-17.3
" ~8 4-186
"66-168
7.3-17.5 "
63-166
6.2-18.5 ~
FILTER PACK
Je-321^:1— ~
"-4i-t52~"
6 3-JB " "
"5.5MB
19 5-27
5 62-18
6 1-19
" 4 5-17 "
41-17
22-28
"5-168 "
46-162
46-157
4.7:153
15-30
" 16^30"""
13-275 "
93-1175
11-292
35-266
7 9-20
6 B-20 6
" 7 6-20 6
3 7-20 0
36-200
OC.AWl II. WK-1
-------
APPENDIX E
NAME ADDRESS
MW2
MW-3
Nebraska D«p! of Roads S Hwy 61
MW-1 - --. - . .... ..
MW 3
MW-4 ~
MW 5 . -
MW 6 -.
MW-7
MW8
MW 9
MW 10
MW-12 - — - •
MW-13
MW 14
MW-15
SM 1 " '"
fU* 1
linonai AuioOtuck S'itip i flO 1 US6 inteiciiatige
MW N
MW S - - .
MW 1W
MW-2W
MW-2H
MW 3N
MW 4N
MW 5N
MW 6N '
MW-7N • - —
MW HM
USE
Monitoring
Monitoring
Monitoring
Monitoring Weil
Moniioring Well
"Monitoring Well
Monitoring Well
MoniioringWeli
MoniioringWeli
MoniioringWeli
Moniioring Well
Moniioring Well
Monitoring Well
Moniioring Well
Monitoring Well
Monitoring Well
Moniioring Well
Moniioring Weil
Sparge Moniioring
Sparge insi
Moniioring Weil
MoniioringWeli
Monitoring Weil
Monitoring Weil
Moniioring Weil
Moniioring Well
Monitoring Well
Monitoring Well
Monitoring Well
Moniioring Well
Monitoring Well
DEPTH
Ifeetl
310
180
ISO
150
154
ISO
150
150
150
IS 4
ISO
150
ISO
150
152
150
300
302
210
210
199
197
201
194
174
175
193
198
1B9
CASINO
DIAMETER
2 -
2
2
2
2
2
2
... ....
2
. ...
2
2
2
2
2
2
2 '
. .-._
2
2
2
2
2 .' ""
2
2
2
2
SCREENED
INTERVAL
— - -
76-17.6
36-136
40-140
50-15.0
48-148
48-148
46-146 " "
4 1-14.1
5.0-116 "" "' "
4.7-14.7
4.0-14 0
47-147
46-14.0
4.8-14.8"
4.6^14.6
4.8-29.8
28 0-30 0
10.8-21.0
ii.6-2i.o
" "9M99
"97-20.1
99-20.1
" ~" 9 3^19 4
73-17.4
7._4_-17.5_ _
98^9.8
8.7-189"
FILTER PACK
_. . .
'
5.7-18.0
28-15.0
35-150
30-15.4
27-150
30-150
30-150
30-150
3.1-154
3i-i50
3.0-150
3.7-150
'30-150 "
38-152
4.4-30.0
280-298
94-21 0
95-710
74-199
73-197
7 6-20 1
62-194
53^74
40-175 " .
;f 9-19 3~~
6 5-18 §
OnAWn.lWK4
-5-
-------
PENDIX E
OdALLALA WATER WELL INVENTORY
Amoco Oas SlaliilT
MW t
MW2
MW3
MW4
MW-5
MW6
MW7
MW-B
Ciiy Sirenl* Water
MW 1
MW 1
MW-3
MW-4
MW5
MWG
MW f
n
('My I ilunry
(ODSP nl
MW-1
MW 2
MW3
MW4
MW5
MW6
MW 7
.IRK Srrvirp Sl.ilion
MW 1
MW-?
IMW j
IMW 2
tMW 3
|IMW 4
503 F. 2nd StreH
W 2nd R W "§="
1044 N Spiuce
iE ist»E
Monitoring Weil
Moniloiing Well
Monitoring Well
Monitoting Well
Monitoring Well
Moniioring Well
Monitoring Well
Moniioring Well
Moniioring Wcli
Monijpring Well
Moniioring Well
Monitoring Well
Monitoring Well
Moniioring Well
Moniloiing Well
Monitoring Well
Moniloiing Weil
Monitoring Well
Moniioring Well
Moniioring Well
Moniioring Well
Sparging
Monitoring Weil
Sparging
Mnniioring Well
Moniioring WP!J
Moniioiiny Well
Moniioring Well
Monitoring Well
Moniioring VVHI
DEPTH
_ Ifeetl
22 5
230
220
25 5
250
220
on n
200
175
17 5
175
175
175
170 '
164
175
186
740
71B
750
740
710
0
722
30
30
20 6
200
200
200
CASINO
DIAMETER
llncheaJ
2
2
2
2
2
2 ; ;•
2
2
- ....
2
. _...
2
2
2 ' ~
"4
- __
2
2
2
2
2
2
2
? " "
2
2
Z
SCREENED
INTERVAL
(fed)
68-218 " '
"~'68-2iB~~" —
66-21 6
68-21.8
86-236""
ion-200
90-i§6
9.0-190
•J^J.o:i7.o
7.0-17.0
7.0-170"
""7.0-170
10-17.0 ~
'65-l8"5
"~ 80-180 "~
"~7.s:i7.5
636-736
631-731 """ '
637-737
626-726"
60 1-701
58.0-S8 0
..._"6ie.7j.§
" 20-30
20-30
80-130
""80-130
8 0-13 0
80-130
FILTER PACK
lietll
50-225
~ 60-230 "~
5 6-22 5 "
" 50-220"
"""70-256-
8 6-22 0
70-200 "
70-200
~"5.i"-i75"~"
52-17.5
52~-i75
<8-175~"
4 6-17 5 ~
"55-170
"4.9-164 '
"•§5-17.5
6i6-74"o '
58 8-73 6
58 8-75 6
595-746"
51 5-710 "
55 2-68 4
58 7-72 2
60-130
60-130 ""
66-136
60-130
-R.
-------
-TftQLK dJO
APPENDIX E
OOALLALA WATER WELL INVENTORY
NAME
IMW fi
IMW 7
JMWfl
KW 1
f &C Service Cfniftr
MW-2
MW 4
MW-6 .
MW-9
MW 10
MW II
MW-12
MW. 13
MW 14
MW-IS
MW-17
MW IB
MW 19
MW 20
MW 21
MW T)
ADDRESS USE
Monitoring Well
Monitoring Well
Monitoring Well
Recovery Well
410W 1st Sireot
Monitoring Well
Monitoring Well
Monitoring Well
Monitoring Well
Monitoiing Well
Moniioring Well
Monitoring Well
Monitoring Well
Monitoring Well
Monitoring Well
Monitoring Well
Monitoring Well
Monitoring Well
Monitoring Well
Moniioring Well
Moniioring Well
DEPTH
. (feed
150
20
Job
200
200
200
200
200
200
200
150
150
150
150
150
150
150
150
CASINO
DIAME1CR
(Inched
2
- •--
6
__. .._
2
_
2
.
2
2
2
2
2
2
2
2
2
2
SCREENED
INTERVAL
(feet!
50-tao
'~T(M5i.O
5 0-15 0
so-is;o
5 0-15 0
5 0-15.0
"5.0-150"""
50-150
S.fyiSiO ~
50-150
5.o-i5o
50-150
50-15.0
5.0-15.0
50-150
50-150
5.0-10.6
FILTER PA«K
(feed
40-150
- - -
"T6-~i5.o~
30-150
3 6-iS.o
3.0-15.0
"30^150
3.6-150"
3 0-150
so^iso"
30-150
Is-iso"
45-150
4.0-150
3.0-150
30-150
30-150
~" 30-150
WM
-------
Tabl»2l
Grouna\>ater \nalyticaJResuitsiai
Ogailala Ensineerina and >ranufacturins, Osallala. Nebraska
June and Juiv 1998
.
Methyiens chloride
'..2-Dichloroethene
Trichloroethene
Teirachloroethene
Toluene
Other VOCs
Field Parameters
Temperature < degrees O
Conductivity
pH
*
VOCs (ng/1)
Methylene chloride
1 ,2-Dichloroethenc
Trichloroethene
Tetrachloroeihene
Toluene
Other VOCs
Field Parameters
Temperature (degrees O
Conductivity
oH
P"
VOCs (ng/1)
Meihylene chloride
1 ,2-Dichloroethene
Trichloroethene
Teirachloroeihene
Toluene
Olher VOCs
\T\V-1 A
5 JB
5 U
5 U
5 U
5U
ND
1.4SO
6.S
M\V-5
2 JB
5U
2 J
2 J
5 U
ND
15
1.700
6.8
A
2J
5U
49
5 J
5 U
ND
M\V-iB
5 U
2 J
4 J
5 U
5 U
ND
i <
:.500
6.9
Vf\V-6
2 JB
5U
5 U
5 U
5 U
ND
15
1.700
6.6
B
2 J
4 J
61
4 J
5 U
ND
\I\V-2A
2 JB
5 U
5 U
3 J
5 U
ND
15
1.470
6.8
MVV.7A
36 B
5 U
5U
5U
5 U
ND
15
1.500
6.8
c
5 U
2 J
59
2 J
5 U
ND
MW-2B
3 JB
5 U
22
3 J
5 U
ND
15
1.090
7.0
\t\V-7B
2
5
2.100
3
5 U
ND
15
1.360
6.9
D
2 J
5 U
5 U
5U
5U
ND
M\V-3A
2 JB
5 U
20 U
5 U
5 U
ND
14
1 .400 .
6.7
\iW-17B
5 U
5 U
1.700 J
3 J
40 DJ
ND
EB=2
5 U '
5U
5 U
5 U
5 U
ND
MNV-3B
2 JB
5 U
20
• T T
3 U
5U
ND
14
1.39
6*7
./
EB=1
36
5
5
ND
Trip
Blank 2
• f
15
5U
5T T
U
5r T
U
5T •
L
vrr^
ND
VA = not anali
M" -4
5 U
5 U
« r
j j
-j i
j j
5 f
ND
1.740
Trip
Blankl
51 B
5.U
5U
5T •
U
ff t '
J L.
ND
^?ed:
XD - not detected (detection iinut m parentheses i.
bl Duplicate of MW-TB.
-------
Table 4-2A
=!ume " Alternative i iL'.rrmea Action) Cost Summary
CAPITAL CCSTS
direct Ccsts:
tem
2eed Notification "•
Monitoring Well Installation
Subtotal Direct Costs
'ndirect Costs:
Item
Engmeenng Plans & Specs
Monuonng Well Installation Oversight
22
Subtotal Indirect Costs
Total Capital Costs (approximate)
Jmt 'Jnit cost Quantity
:ump sum 320.000 1
iumo sum 517.553 1
!ump sum 525.415 1
lump sum S4.352 1
Approximate
tem Cost
520.000
SI 7.553
Approximate
item Cost
S25.415
S4.352
Approximate
Cost
S37353
Approximate
Cost
•---•-• --•-•-. S29.767
$67.420
ANNUAL COSTS
Item
Analysis for VOCs
Five Year Reviews
Sampling and Well Maintenance
Bottled Water Supply
Total Annual Costs Present Net Worth
Average Annual
. Cost
S2.693 "
S3.214
S30.788
S4.050
Duration @ Total
Discount Rate C?st_
28 years @ 5% S75.400
28 years @ 5% 590.000
28 years @ 5% 5862.056
28 years© 5% S113.400
TOTAL FOR ALTERNATIVE (APPROXIMATE)
TOTAL PRESENT NET WORTH (APPROXIMATE)
$1,208,276
Present
Net Worth"
S40.119
547,387
S458.679
S60.337
S607.022
$674.442
3asea on estimated hours to file a aeed notification (250 hrs @ S75/hr)
' Present value calculated based on a senes of equal payments for the duration of the penod at an interest rate of z percent.
Present value was calculated using the following equation: PV = PMT/N X (1 * INT)*-N
Where: PV = present value
PMT = annual payment
INT = interest rate
N = term of payments
ait2tab.wk4
-------
Tabl«4*2A
s'ume 3 Alternative 2 (Limited Action*
CAPITAL COSTS
Direct Costs:
Item
Deed Notification"
Monitoring Well Installation
Subtotal Direct Costs
indirect Costs:
Item
Engmeenog Plans & Specs
Monitonng Well Installation Oversight
Subtotal Indirect Costs
Totat Capital Costs (approximate)
ANNUAL COSTS
Item
Analysis for VOCs
Five Year Reviews
System Operations And Maintenance
Bottied Water Supply
Total Annual Costs Present Ntt Worth
Unit
lump sum
lump sum
lump sum
tump sum
Average Annual
Cost
S2.763
S2.813
$29.933
$3.938
,— — ~ p--— ^
Unit cost
S20.000
$17.653
$25.415
$4.352
Duration©
Discount Rate
16 years @ 5%
16 years @ 5%
16 years @ 5%
16 years @ 5%
Approximate
Quantity Item Cost
1 S20.000
1 517,653
Approximate
Item Cost
1 $25.415
1 $4.352
Total Present
Cost Net Worth"
$44,200 $29,939
$45.000 $30.481
$478,920 $324.402
$63.000 S42.674
^
Approximate
Cost
$37,653
Approximate
Cost
$29,767
$67.420
4
$427.496
TOTAL FOR ALTCRNATOrE (APPROXIMATE)
VI .5698.540
!';>'«. j.':..*j,r
Based on estimated hours to file a deed notification (250 hrs @ 575/hr)
Present value calculated based on a series of equal payments for the duration of tne period at an interest rate of 5 percent.
Present value was calculated using the following equation: PV = PMT/N X (1.+ INT)*-N
Where: PV = present value
PMT = annual payment
INT = interest rate
N = term of payments
all2tab.wK4
-------
i.rr*mz. £.-•£--.
Tabla 4-2A
=lume 4 Alternative 2 (Limited Acjtoni Cost Summary ..... _
CAPITAL COSTS
Direct Costs:
item
Deed Notification *
Monitonng Well Installation
Subtotal Direct Costs
indirect Costs:
Item
Engineering Plans & Specs
Monitoring Well Installation Oversight
Unit Unit cost
lump sum $20.000
lump sum S108.503
lump sum $25.415
lump sum $24.912
prry- ~ „..-_-,,.-
Approximate
Ouamitv Item Cost
1 S20.000
1 $108.503
Approximate
Item Cost
1 $25.415
1 $24.912
Approximate
Cost
Approximate
Cost
Subtotal Indirect Costs
Total Capital Costs (approximata)
5178.830
Item
Analysis for VOCs
Five Year Reviews
Sampling and Well Maintenance
Bottled Water Supply
Total Annual Cost* Pre*«nt Nat Worth
TOTAUJpRALTERNATB^iteEECMMATE)
Average Annual
Cost
$5,525
$2.813
$29,933
S3.933
.-f '
Duration @
Discount Rate
16 years @ 5%
16 years® 5%
16 years @ 5%
16 years @ 5%
Total
Cost
S88.400
S45.000
$478,920
S63.000
$854.150
Present
M«* Worth -
$59.879
S30.481
$324.402
$42.674
$457.438
• Based on estimated hours to file a deed notification (250 hrs @ $75/hr)
" Present value calculated based on a series of equal payments for the duration of the period at an interest rate of 5 percent
Present value was calculated using the following equation: PV = PMT/N X (1 + INT)*-N
Where: PV = present value
PMT = annual payment
INT = interest rate
N = term of payments
alt2tab.wk4
-------
Table 4-9
Ogaliala Feasibility Study, Plume 1: TCE Plume in the Alluvial Formation
Comparative Analysis of Alternatives
CRITERIA
I ii.., -i ,n r,,,|,., t,,,M,,| 1 lumnii HcMllli and Fnviionmenl
r1 1 ..in|.li iiirn ivilh AIIAIt',
I ll>"lu, him in imn ity inntiiliiy. nnd volumo through treatment
'• '.li"M 1 irllri livi'Mi",';
'• t'i'i'i. • ii.iiniiiv "1 .ilicinniivp
' •-.! ,.i,il|i-iii,iiivt> il'ii'sonl WoilhCost)
'( '•) !)>• .1, t rpMni o
MOIM
nil- i -i ,-rii,..,,...,,. i
t 2 4
No Action limited Aelkjn Containment by
Air Injection
mine nind nixil
"«' yes sonic
low mod mod
»»ne none none
low very high lm)li
••wy easy inodcrnlo
$0 $674.000 $2.495.000
HID TOD KID
mi) IBD IBD
6
Extraction/
Deep Well
livjccliun
liillh
yes
mcd/high
none
high
moderate
$2.5.13.UOO
100
1BO
12
Ex-Silu Ak
Stripping/
Dischaiao
high
yes
mod/high
mod
mcd
nK,de,a,e
$3.067.000
HID
TBD
nkt (.nnmirc
2S
In-Situ Vnpnr
Exlinclwii/
high
yes
high
very high
mcd
nrad/dillicul!
S7.323.000
101)
IBD
niicnnniivc
26
In Situ Vniwr
Lxliaclioi
-------
Table 4-9
Ogallala Feasibility Study, Plume 3: West PCE Plume in the Alluvial Formation
Comparative Analysis of Alternatives
CRITERIA ALTERNATIVE
No Action
' "•' ' 'II I'Mi'i In I Miim.iiiH(>,ilHi and Environment cinno
II-|IIHII< v.illi AHAMs lln
' 1 1 i'1'»iiliriipr,'s anrlporrnaneriee l,,w
t 1 if. lin ti"ii in IH. n iiy. iiinhility, and volume through treatment nnno
'. ''.In ill llMIII |.||(>( llvi'MlClS |ow
I. lni|'li'inonl;i|nMy i.l :illfMltalivft ensy
.' !'•• I I'l.-illi'iii.ilivi'd'iMcnl WorthCosl) JO
" '-"I". i- •'••(•MM"- IBO
" IViniuiiii.lv ,-irc (>|i|.inro JQQ
• . .
ALTERNATIVE
2
mod
yes
mod
none
very high
easy
$495.000
TOD
TBD
ALTERNATIVE
4
•nod
sonio
nicd
noun
high
modci.ile
$1.262.000
i no
TBD
ALTERNATIVE ALTERNATIVE
6 12
Extraction/ Ex-Silu Aif
Deep Wed Strippino/
Injec ion DiBrha.rm
high
yos
mod/high
none
high
modoralo
high
yos
mcd/liigh
mr>d
med
easy
$1,351.000 $9)3,000
,nt>
TBD
TBD
TOD
21
In-Silu Vapor
Extraction/
high
yes
high
voiy high
med
mod/dtlficufl
$1,464.000
TBD
TBD
ALTERNATIVE
22
In-Silu VafKir
Extraction/ Air
hk|h
ynr,
hiijh
hii|h
• mod
mod/dillicull
$1.441.000
TOO
TBD
H
05
r
*\
Sb
fv
'!• • ' MM | '|.|r r-\
-------
Table 4-9
Ogallala Feasibility Study, Plume 4: TCE and Carbon Tetrachloride Plume In the Ogallala Formation
Comparative Analyst of Alternative*
cm i I.MIA
I C'vr.i.ili iv.im imiHil tliiinan llonllh and Environment
r f'linncp. with AHARs
'I I mm IIMIII Rllrrliunness nnd pennnnencg
•I ripitiiriwn in iiiorrty. mobility, and volume through trealmenl
'• f'lunl IPIIII nllc'i livrnnss
r. iMii'li'inpiil.ibilily ol nlleinnlivo
' < "-,i ,.| aiiPiiiniivr* (1'iosnnt Worth Cost)
C 'Stale .irrrplnncc
') Cm
IIOtM
rri> i
ihicnriAllVB
1
No Action
ii
none
no
low
none
low
easy
$0
TBD
TOD
ALTERNATIVE
2
Llmilid Action
- •
mod
yea
mad
norm
very high
easy
$636.000
1BD
TBD
Extraction/
Deep Woll
Injection
high
yea
mad/high
none
high
moderate
$3.724,000
TBD
TBD
ALTERNATIVE
9
Ex-SituAir
Stripping/
Disc haras
high
yes
mod/high
med
med
moderate
$4.662,000
TBD
TBD
ALTERNATIVE
11
Ex-Situ Carbon
Adsorption/
DicchartM
high
yes
med/high
med
mad
moderate
$3,885,000
TBD
TBD
•M«MM«_HM_H.H^
ALTERNATIVE
{ M
1^
In-Situ Vapor
Extraction/
Oxidation
high
yes
high
very high
med
mod/dlllicull
$14,907,000
TBD
TBD
ALTERNATIVE
IS
In-Situ Vapor
Exit action/ Air
Sparoinn
hiyli
yos
high
high
mod
mod/dillicuH
$14.670,000
TBD
TOD
SL3
||VWU|MVV
-------
TaW«4-8
Qgaltala Feasibility Study, Plum* 4: TCE and Cartoon Tetrachtonde Plume tn tht Ogaliala Formation
indrvfdual AnityiM of Att«mit*v*t
Criteria
1
No Action
2
^itmtod Action
3
Extraction/ Oeeo WeM
infection
9
Extraction/ Air Slrroptno/
Oiaenai g« to Surface Water
AJternaove I Alternative
11 j -4
Extraction/ Carbon • In-Silu Oxidation/ Vapor
Adaorpoorv Oiacnarge to 1 Extraction
aurfaw Water I
Alternative
15
livSitu Air Soefftng/ Vapor
Extraction
REDUCTION OF TOXICtTY. MOBILITY. OR VOLUME THROUGH TREATMENT (Confdl
types and Quantify of Resduats P^mawng After Treatment
Statutory Protavnce lor Treatment
SHORT-TERM EFFECTIVgNg^fl
Communry Protection
Environmental impacts
rime UnM Acoon o Complete
IMPLEMENTABILITY
A&tbly to Cortsluct and Operate
Ease 01 Ocmq more Action rf Needed
Ability to Monitor ertecOvtmess
Ability to Obtain Approvals and Coordinate with OffXM
AvanaWify ot Services and Capaaoes
Availably ot Equpment. Speaaws, and Materials
No ftwxtrt remain
Goes not sattsty.
fVsk to oommuMy not
" twmensstJon. but
£DrtartwiHed water may sQl
No sqnti --ant nek to worker*.
Con*ftuBd«flpactttomen»*ng
No oonsiucDon or operaaon.
May ne*d to 90 trough fSI
Nomoritonnj. Failure to
potantil wtgesion ot
conumfiiiBd groutdMttr.
No aopt oval necessary.
!^;iw"xcw:"m
Noneroqwred
No ttsouais remain.
Does not sattsty
tfVTaMeoby remedy
mpternentalon.
No sjgnrfcant nsk to wonters.
Conenued «npeet from ensang
Risk tram tte gromd waear
reduced •nmedaMy due n
booted water and raMuboml
S*npte to operate and construct
ft moniionng mcacates more
acton • neoeeury. may need
to go Woogh FS/ROO prooeM
agam, Ooud implement *
Proposed moritonng will give
noaee ol unexpected nacwsed
Shown be easy to obtatn deed
noeaea and neovssarv permits
SMAIMt.ft.1.
or speoaiatt requred.
.Noies«Juaisrema«.
Does not saostv
toM»».a
tvpical nrt to workers
anoaaiad wttt comkucvon
Po«s*Je aqmfar draw-iown
dung ojroundwanr •iracoon.
acreavedn tS years.
rteneimj utthtiea or s * tace
&mpte to extend grou«fmt«r
va acton system.
r**opooed montorng w ul gve
nonce ol failure betoK
s>gnrttant expocue oxurs.
See AttemaBve 2. Ao>os
.Kpaemenls may be rujmerom
SeeAitemairvei.
Stfniar taAttemairve; Need
tig tor oeep-weit tnstafAtani;
^noxrid be reaaity avMacla from
petoteum maustry
No aeteciaQe teswuiS teman
««.
SM*wnttM2
ProMcnon reourad agarat
dermal corwct or vaoor
mheiabon ouing construcDon
and operaaon of « stnppng
system
PoscAte aqudar draMMJown
(twmg oroundwaier extacton
construct *A* slipper requves
someopecaoon
See Alter naive 3
£»e Anerrtaave 3
See Altwnatrve 3 NPOES
permitDnq mav be arduous
See After nah« i
SmtartoAitomairve^ Need
reaoty avaaabte spee*«ts to
instaH and aparata ax stepng
system
Mo oetectacte res
-------
I
AJtanmv
14
OxitfMxm
Extnclw
III
f-32
U
if!
o ™
51
is
3* s
• 8 - t :
Ufii-5
•B S
i ^
-•»
3
Sf
s a 8
r* jf *
I
i
s « a
3 i
I i
S
§
x
.
I s
5 •» a
a
S
s a a
-------
22.
Tabt«4-8
Ogatlala Faaattulity Study, Plum 3: Wta PCE Plurrw m th* AUmrul Formation
Individual An*
' 2 4
Cntaria Na Action UIIMM Action Contwnmli
REDUCTION OF TOXICITY. MOBILITY. OB VOLUME THROUGH TREATMENT (Contdl
lyM. of Afttmatives
6 U 21
y Air tnjaetwn £zMcbon/ OMD Wtl! cxtractwtf Air Stttppin^ f n-SHu Oxitft-ttorV Vapor
Types and Quantity ol Reaouau ftonuvwig Anor rrftavnwH No raoxjtuto reman No rawouo* reman No (Manual* ramtn No lesuuats reman No Detectable residuals rtman No detecuoiarabauib reman
Carbon rew*e«. regecwaton Catton reoura legmration.
Staiuuxv Pie(«fence for Trwiroent Oow no( saltslv Oownasauslv DoesnoJMteiv
SHORT-TERM EFFECTIVENESS
Commonly Prolectton Rick 10 community not Hiek tocommunrlvM Se* Altarialv* 2
•npleinenaion. but irnplemeflttlMn.
conttmttaM water nay cut
Does not saiaiv SaWfies Sabsies
Sve Artemaive 2 Sao Attornatve 2 Sea AJtxnitve 2
Worker Piowcoon No significant run B woritan NoiignlKamnuiBoorMn Type* ratio mum Typeal r» » WO.MH ProleaonreguredaguBl ProMcftn wind agant
aeenriaietl «tf* tomitytrm aesotulflo *f» ccnHue&on dvmil conoct or vaoor darmtl contact or vapor
mrMUbondmngconKnoon Mialaionovingconituclnn
anaoDar»onoiar5«.t>png andorjerascnotoadaianand
5V*oTi vapotaudradnrtsyxMit
Env«onrmni»llm(»<« Cortnwd miptct Irom (nung Conmuedinipacllromeiiitna ContnuMmpictliniienslng Pouclt aquifer dn».rm>wJ. RAOkx SwAlumalwfi SMAJMMM: RAObr SeeAJ»mM21
rmlirnrlfTiirwfilityrlin^i n«lir«itiTiTWkalayilii«l~i P(Tart»«**tB!0¥B»n ?ZI\.J«™J !. ^^ «wnai\« zi.
boaMMMrmiraauon^ botMnwrmimMaoul "^ "^^
contoa RAO k> PCE conn*.
atfHOMd n approamaMf tS
VOM3.
IMPLEMEIHTAHILITY
tokVloConsmiandOpsiai. No coraiucnon or operMotl. Smpn to oscraH an) onttuct SmAtamamZ
Wwnwe SeeAhemaivM System alreaw conunxied Fawiv tt.w.httorw.vd to •^-Aiw™m-,3i
mormonng syiwn «Mrt«nngiittce At oippw raqures some comtucT V«p(»tnicK>l
condiaoft£
op***1"^ faourai*om»oper.rtDri
Trending may be hndored by
surtacvoondtent.
EaseolDo^moraActon.lNeeoad Wavne«l tocpf-roo^FS/ tt r«on,tonrn ««.* more Sarnp-atoertendM^jacoon Smote to ertend grouxJ-at* SeeAnamatrvee Simpie to eirtend oxdabor. a«J S-n^te to extand vapor
^ ^^ T^EZZSgLS?* **** Sy*"im «»»c»on system vap0f art^oan ^.ams enracte and spaing
to go Wougn Fa^ROO process «v«i*.m*
ag*n Coutd tmotamant .
ground water MMrrwnt t
AUl.ry lu Mumiot LIlwittVM..^ Nu n w bting F.)4u.« lo Piopuk«J ttM»iot*-)q wm yv» Piop«wJfnoniK*««J M yw* S«i A!twnd»vw -i S*M Altwmw* 4 S«, AllHr«we i S-- Att«-naitve 4
datoctcxxitanvramrr.i.ins not»olu«rP«led«w«se<{ no** o( ftdura b-to. ^«'«™We b« Afl*nairve «.
pottntia. mgnKn ol conoenvaaorts s*gftfKafK «post.
conunn-ated groundwvter.
Atxlitv to Obum Approvals and Coordanato Mth Oftet A^oncNK No approval naoK&ary ShouU be «sv 10 oota*n deed Sa* Aftttnaftve £
noaoec and neonury permiis
AwartWiry ol Scrvcw and Capacnws No urvKxn or capaotes Sea Attematv* • See Attar novt 7
requred.
Avaiiatoutv ot Eqwpment. Speoairsts. and Materials None tequred No spectat equionvm rmtecui. See Ajtematve i
or spDcmina leq jtreo
»r*')ccurt
Seo Alwnwrve 2 ACOKS Soa Artamairve 6 Petmrts See Arternaov*6
aojeemens m»y be rwnerous have prevKwVy bean ootamed
tor fits system.
See Aifamagve 6.
SM AJWnatv* i See AHemawe : See Afternaive \ See Artemaftve 1.
Simptar to Aftorruttve 2 Need Stmtlar to Alternative 2 Nmd S»mlar to Artemuve 2 N*e-l S*mi(ar to Atlemakw 3 Need
ttg to OMO-wt* msuttboni roacHy tvoj.
-------
"1
it
3*1
II!
'H
ill
I
I
§, § 5
S « 5.
S£ 1 s
s
§ § s
I § I
1 s ^
III
o » !*
2 a- ;/
a 5 !'
S 8 S
JS
-------
TaM*44
OgilliU Fuiibility Study, Pluim t : TCE Plum* n tlw Alluviil Ffxmition
Mlviduil Anilyu* of AltKiutivM
Criteria
1
No Action
MINIMUM
2
LHniM Ae&on
4
Cafllainflwnt by Aw Inaction
Alternative
6
Extraction/ OMP Wall
Injection
Alternative
12
Extraelton/ Air Strioomg/
Diecftaree to Surface Watar
AlUnum*
25
In-Situ OndaboiV Vapor
Extraction
Alternative
21
In-Sim Air Soar jtng/ Vepoi
Extraction .
REDUCTION OF TOXICtTY. MOBIUTY. OR VOLUME THROUGH TREATMENT (ConTdJ
Types and Quantity at Resduats ftema.n.ng, At** TrtNumant Mo nwduitt r«mun No ms.duats mma-n.
MO l*Bduatl (MltM..
rcquiM i og»rmuor\
Sututoiv Pi«hrt»nm tor Tiuaununi
SHORT-TERM EFFECTIVENESS
Co4T*TK*iry Protection
Worker Protectton
Time Untf Acooo a Con-plete
IMPLEMENTABTL1TY
Atxlity lo ConMuct and Oparato
Ease o* Dan} moro Acton rf ftoed»d
Ooefi not «tofts.
Riik Infn tie) ground mior
reduced MTvnad.iMy oX* b
Dotted twMT and raMMoAal
Dante.*.
See AHemairv* 2.
Type... rufc to *or ksrs
amaitod ««i consoucion.
POaWbte «quriir draw-down
during groundwater ertacoon.
S« AftwrnOvc 2 RAO for
TCE «cnwv*d m lOyMnx
SaaAnamaivcZ.
ProMdon requtad agnmt
dermal contact or vapor
mhala Bon owno, Cor»wucoori
and opanion ot « mppng
Aging grauncrwaMr •xiacoon
SMAMorraivoG.
SmAftom»v«2.
ProMcj>onr.KM1*d*9arti
d«rma( contact or vjpor
and opwaDon o* ONKlMon and
Vapor BKbeK&oi'i niey vnpect aw
t^Mfee/ and odom «ttiough it
Ml meet •rntMton ttandudt.
SMAiMn..uM2. RAOftlf
TOE adievexj in 5 ymn.
SeoAtlQmaiv«2.
vapor mattton dunng
oonMnjCDon and opatetton of
wpor extracaon «yia.ni.
SMA.1afna.Mi2S.
Ability to Obtain Approvals and Cowdralc wih Crer Agenaes
Avaiatntitv of Sarvoes and GafMdM*
Avauabiiilv ol Equonart. Speculate, and hUtoniM
May need » go trough FSf
ROD process again.
No moMonng PjMtureto
poMnui ngaskon of
oix.tan.irMMdgroundH.iMr,
Mo approval necessary,
No MfVices or capacities
Nonerflgured
S.mptobOP..rat«ar4(x>ratnxt S**AJtarnaM2 Ittyhavn
cond*^
If monrtjmg ndnates more Smp* to ««end «* *T»ct«n
actnn » naonsw. may need syslam.
(090 fvougn F&ROD proom
agiMt. Coutd impwrntnt
ground MM- treatfn.jn( 4 -
Pn^no.tt.^ave ftopc^d ™,^-,,c
conoenraioos. stgrancant exposure oo.v«.
Shodd b* •*« to oot*o oead Sa* Alrarnatva 2.
noaoas and n«o*ss«ry pamva.
S*M Anamatvft i S«« AHei mtiv« l
No spacaal •auorfMnt. mBMn.... Sav Anamilfva 2
S«* AAemaM 4. Fawtir straitjntbrwaf d to
oonwuct A» stnpper Foquru
*o*r«* ypewatcn
Stfnpltt b «>*no Qfoundwaler Sea Anarnatva 6
exMrton sytiam.
Soc Attematva 4 y^« AHernatve 4
Seo Allamaav*; 2 Access Sea Altflmanv* 6 NPOES
agreamenB may be nunvwous permttng may be arduous.
Sea Atiarnilve 1 Saa Altarrune 1
S*n>.tM to Altamative 2- Naad Simlar b Anwruiivt 2. Need
ng !^x d.wp-vM.1 tnuattabons re.xMy -wanaf* specmtsts ID
snoi d be reaortv avaMaaatrom mst*flindooar«t«*w sacpng
pvioeum ITOUS.TY system.
comwuct Vapor MtadWH
rfl^iawei sornvoparatCML
Trancn.r.9 m*y b* hndaradby
^rte-cacoodrtioni.
S-T^*to«rt.jndo.rri.*Dri«rd
vapor eiracton lyftMim.
SnAimaM^'
S*« Attemaev* 6
S-.AlN.-ratve,
$**** Wl At)0mi*vQ Z Need
read*y avaMbb spaDMttt h/
in*al and oparai* oadsion
and vapor exiacaon systems
Simpto to *KMnd vapor
system*
See Aitemawe *
SeaAfMtniwoO.
SwAHatnatvcl.
Snv^toAtiHTUBve2. Naad
msul and oo^ato w w.u^.^
and v«por onacson vysMms.
-------
8 S S
s. t a
'
)3 2 a
S 3
S 5 5
» -o »
4 !*• *°
8 * S
J5 8 (8
S | 1
S £ a
i*
S »
Lf
I1
If! S
— a *• *» 3
f!
!S"i
If '
M
]p
15
* °
ill
Si
Air
Ext
ab(t4-<
* 1: TCE PI
of A
-------
BB£ia
800
FLUOR DANIEL 3
X tfoo-:2' -j we ' AIIUVC "o"»-c::ic--
V Moni:or.ng Ws'i m Ouolla:o -ormotioi
•fir Proc-jctio- A?" ir Alijvic' ^o'natio"
iF ?r;cjc- ?" v.e ' Ooolic'? rcrr->.-. c •
•'•e. s scmpiei i- 1995 cri srowr Fewer
. »ells were sompiea ir. 1996 Monitoring
i»«ii clusters ore circled one identifies
M^VS riot so^^'es c'fi net '^ciuded.
Figure 2-13
Locations of Existing Wells
Ogallalo Water Supply Rl
-------
-------
4QC 800
FLUOR DANIEL
Well
•Voter .sve'S -"• tee1. ~;c-. e ','S,
Grounowcrer Leveis in the
Uooe' Cgallalc "ormaiion
June 1996
Ogcilaic Water Suopiy Rl
-------
iKv-t.ow.owe
SIM itM
0 400 8QC
f££T
FLUOR DANIEL
LEGEND
Monitoring Well
Water leve:s >r 'tf. ;3ove '.'£;.
Figure 13
Groundwoter Levels i- the
Lower Ogailola "ormation
June 1996
Ogarala Wafer Supply Rl
-------
5661
UCIJOUJJOJ {O|An||V 3ljl Ul
33]. jo |usjx3
-------
-------
QGAUALA
otcr-rcc
SEPT
SH3
I ^£1 \'\ . .}—•• \_l\_l__ • '•
i^ip.£&£^^ i"^ s= I^^S^
1,tLJ5^.r?C-P,P:u ;i-^nr^b^-X-
C 400 800
—c •
FEET
Concentrations in ug/L
FLUOR DANIEL
Contamination
Formation
Ogaitalc Water Supply hi
-------
-------
5MJU.-PCE.DWC
Concentre: :ns m
FLUOR DANIEL
xrent of PCE Coruaminatior
in the Alluvial Fui motion
1995
Ogoilalo Water Suopiy Rl
-------
tor
,-«*«•
isaae- .^^ _
— C
3QE=i ffiSLl^@t^^ j.,|fe
S3BSggBR^=fe^ke7!
s^
A
N
A
Extent of PCE Contamination
in the Alluvial Formation
June 1996
Ogailaic Water Suopiy
-------
G»±?PHH
'%sc 3=^ cm v • U—• i—i
FEET
Concentrations in ug/L
FLUOR DANIEL
c.xtexi of Carbon :etrachlonae
ijj Contamination in the Ogailala Formation
1995
0-:a!lcia Water Suopiy Rl
-------
II-O-C-'0*C
St»4 1151
txtem of Carbon ietrachloride .
Contamination in the Cgsllala Formation
uno 1995
Ogoilaia Water ;gup.y R|
F££T
Concntrations in uq/L
FLUOR DANIEL
-------
ASC-01A
x==: is
LEGEND
ASC-013
«- 3E£= MONI7CHING WELL
uOCATION
ASC-OU
9 SHALLOW MONITORING WELL
LOCATION
64-2
• MUNICIPAL .v£LL LOCATION
JT' APPROXIMATE RECOVERY WELL
LOCATION
AMERICAN SHIZUKI
CORPORATION
OGALLALA. NEBRASKA
REMEDIATION SYSTEM
SITE PLAN
-------
Vet I G Street
f Street
i s
fi-
• «••!>*
81 z z z
£ E i §
rr "— I'NVIUONMrNIAI SlIIAirCIFS CORPORATION
II'JH rieciliim Drive Suite 900
Return. Virginia 20190
703-70S-6500
Fiturc I <)
Sample I'uinl l.
Oftllili Elcclinnics Minuftcluiini, Inc.
Oftllili. Nebidka
-------
\
DESCRIPTION OF ANALYTICAL PARAMETERS
USED TO ASSESS INTRLNSIC BIOREMEDIATION
Parameter
Alkalinity
PH
Temperature
Dissolved oxygen
Redox potential
Sulfate
Sulfide
Methane
Ethane/ethene
Total organic carbon
(TOC)
Chloride
VOC/daughter products
Iron (total, dissolved)
Nitrogen
Nitrate
Nitrite
Phosphorus
Description
Provides an indication of the buffering capacity of the
water and the amount of carbon dioxide dissolved in
the water. Increases due to biodegradation of organic
compounds.
Microbial activity tends to be reduced outside of a pH
range of 5 to 9, and many anaerobic bacteria are
particularly sensitive to pH extremes.
Affects rates of microbial metabolism. . Slower
biodeeradation occurs at lower temperatures.
Highest energy-yielding electron acceptor for
biodegradation of organic constituents, < lOppm.
A measure of the oxidation-reduction potential of the
environment. Ranges from +500 mV for aerobic
conditions to -300 mV for methanogenic conditions.
Used as an electron acceptor in biodegradation of
organic constituents. Reduced to form sulfide.
Microbially reduced form of sulfate. Indicates reduced
conditions
Indicator of anaerobic conditions and of methanogenic
bacteria. Produced by the microbial reduction of carbon
dioxide. Solubility limit 25 to 40 ppm.
Metabolic end product of reductive dehalogenation of
halogenated ethenes and ethanes.
A measure of the total concentration of organic material
in water that may be available for biological
degradation.
May be useful as an indication of biological
dechlorination and as a conservative tracer.
Provides a measure of the type and quantity of parent
and bioeenic daughter products.
A product of bacterial iron reduction. Only the reduced
form (ferrous) is soluble. The oxidized form (ferric) is
used as an electron acceptor.
An essential nutrient of microbial growth and
biodegradation.
Used as an electron acceptor. Consumed next after
oxygen.
Product of nitrate reduction. Produced only under
anaerobic conditions. Rarely observed.
Essential nutrient for microbial growth and
biodegradation.
-------
Table 2.3 Analytical Parameters and Weighting for Preliminary Screening for Anaerobic
Biodegradation Processes-
Analysis
Oxygen*
Oxygen*
Nitrate*
Iron II*
Sulfate*
Sulfide*
Methane*
Oxidation Reduction
Potential* (ORP)
against Ag/AgCI
electrode
3H*
roc
Temperature"
Carbon Dioxide
Alkalinity
Chloride*
Hydroqen
Hydrogen
Volatile Fatty Acids
8TEX*
retrachloroethene
rrichloroethane*
DCE*
VG*
1,1,1 -Trichloroethane*
DCA
Carbon Tetrachlonde
Chloroethane*
Ethane/Ethane
Chloroform
Oichloromethane
Concentration in
Most Contaminated
Zone
<0.5 mg/L
>5mq/L
<1 mq/L
>1 mg/L
<20 mq/L
>1 mq/L
<0.5 mg/L
>0.5 mq/L
<50 millivolts (mV)
<-100mV
5 < pH < 9
5 > pH >9
> 20 mg/L
>20"C
>2x background
>2x background
>2x background
>1 nM
<1 nM
> 0.1 mg/L
>0.1 mq/L
>0.01mq/L
>0.1 mg/L
Interpretation
Tolerated, suppresses the reductive pathway at higher
concentrations
'tot tolerated; however, VC may be oxidized aerobicaJly
At higher concentrations may compete with reductive pathway
Reductive pathway possible; VC may be oxidized under Fe(lll)
reducing conditions
At higher concentrations may compete with reductive pathway
Reductive pathway possible
VC oxidizes
Ultimate reductive daughter product. VC Accumulates
Reductive pathway possible
Reductive pathway likely
Optimal range for reductive pathway
Outside optimal range for reductive pathway
Carbon and energy source; drives dechlonnation; can be
natural or anthropogenic
At T >20°C biochemical process is accelerated
Jltimate oxidative daughter product
Results from interaction between CO? and aguifer minerals
Daughter product of organic chlorine
Reductive pathway possible. VC may accumulate
VC oxidized
ntermediates resulting from biodegradation of more complex
ompounds; carbon and energy source
Carbon and energy source: drives dechlonnation
Material released
Material released
Daughter product of PCE
Material released
Daughter product of TCE
cis is > 80% of total DCE it is likely a daughter product
,1-DCE can be chemical reaction product of TCA
Material released
Daughter product of DCE
laterial released
aughter product of TCA under reducing conditions
faterial released
aughter product of DCA or VC under reducing conditions
Daughter product of VC/ethene
Material released
aughter product of Carbon Tetrachloride
Material released
Value
3
-3
2
3
2
3
0
3
1
2
0
-2
2
1
1
1
2
3
0
2
2
0
0
2"
0
2*
0
2"
0
2
0
2
2
3
0
2
0
2
Mquirea analysis, a/ Points awarded only it it can oe shown that the compound is a daughter product (i.e., not a constituent of the source
-------
List of Figures:
1. Area location map
2. Topographic map
3. Location of former municipal supply wells
4. Location of new municipal supply well field
5. Potential source areas
6. Location of Nebraska's monitoring wells
7. Locations investigated by soil-gas, 1990
8. TCE Plume. 10* depth'
9. PCE Plume, 10'depth
10. Monitoring well locations prior to EPA's RI
11. Ground water levels in Alluvial formation. 1996
12. Ground water levels in upper Ogallala formation, 1996
13. Ground water levels in lower Ogallala formation, 1996
14. TCE in Alluvial formation
15. TCE in Ogallala formation. 2 pages
16. PCE in Alluvial formation. 2 pages
17. CT in Ogallala formation. 2 pages
18. ASC's remediation efforts
19. OEMI's site plan and 1998 data
-------
-------
""fprcncc: State of Nebraska, llypcr Atlas, USA
FIGURE 1
AREA LOCATION
MAP
-------
I CSI
vr-1 \
\ i
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^^— «-' — ''~~'- i — ~r-'-=l _ £££!?_£. ?r'>lf; -V\ '•^••i
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-------
:1
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.! fit
~
O GALL ALA
64-4.
£.4-5
i
i
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figure 2 Mumcicai weiis
Per State \.Z. 'iorcers
9 we i" i ocat i on
-------
Municipal Wells
Osailaia. .\ehr2SK3
New Cgailala Well Field
(Approximate.Location)
OGALLALA
\ii-~m ••«
-------
O GALL ALA
Leoeng
Shizuki Corporation
Quick Electric and Manufacturing
Keith County Maintenance Yard
Helmuth's Cleaners
Goal lala Electronics
Former TRW/Good-All Facility
Good-All Electric
Tio-Too Cleaners
JSK Service Station
Bosselman's Purp and Pantry
Former City Duro
Potential
Source Areas
-------
-------
UUVi\r"!
..^rt2£l-
SCHS. M 101
(« l»)
FF^^f^l
0 ! ! J « J
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\
2
3
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5
6
AMI HICAN SIIJZUKL
OUII:K FilciRie & MANUFACTURING
Klim" COUNIY MA!NtENANCE_YARp .
Wll M-2~~
CLEANERS
FIEC1RONICS . .
Ill)
7
8
9
io
11
i?
NERRASKA POWER PLAN
IIP 1OP CLEANFRS__
Uf)SSriMAN'S PUMP,& PAN!Bt
AIco'DEPARTMENT SIORE
J «c K" SERVICE STATION
PLAINS ENVIKONMrNIAL 55ERVICE
533 Gail Driyo Salinp, j
-------
J I
loll H IUI
( I IOU )
I I ill I
0113(5
IP
i
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ii
r,
in:.rmi'iii)N
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UIIH:K .iii
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wiii. iU 2
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f IK: monies
NO
r
o
'ow IMAH
J'lL tPJi CLEANt US
boSSflMAN'S i'UMf A i'AHIJ?r
Al CO DEPARlMENf
j i K SERVICE SIA1JON
I'lAIN'J LNVIRONMI NIAL SI
_ 5:1} Goil_D(ive SpHna. Kansas _?Z101_
Clif: UGALLAlA NebrasUal JPA'Ei7/26/9U
ISOCONCENIRAIIONS (p.pby)j flO. g TCE
-------
VJIL H IUI
( < 100 )
rr 1'?^ i
0)1143
HP
I
2
3
4
5
6
IHSCKII'IION
..ECTR|C & MANUFACTUmN(
KEI1II COUNIY MAINIENANCE
^-'i. ?4 2 J
' QIEANLRS
"
tin
7
fl
1)1
' AN
_
1'3 IPP.CLEAMERS^
U(?ssti_MA^s fUM|'_&
AICO DEPARTMENT SIOJ^E
J * K SERVICE STATION
(MAINS [.NVIRONMI NIAI SIUVICI-.
Goil_Drivo '.luliiin, Konsuu 7-l()|
'
_
UGALLALA NebFasUu '. AE: 7/25/96
iSQCONCENTRATIONS (p.pby) | " MG. " 7" PCE "
-------
-------
ATTACHMENT A
-------
-------
OGALLALA GROUND WATER CONTAMINATION SITE
OGALLALA, NEBRASKA
RESPONSIVENESS SUMMARY
OGALLALA PUBLIC MEETING QUESTIONS/COMMENTS:
Question/Comment 1. Describe what EPA means by the alluvial aquifer.
Response 1. The EPA refers to the top 30 feet of ground water as the alluvial aquifer.
Question/Comment 2. You describe the plume as being static and yet the ground water is
growing like 3.5 feet per day. How do you figure it and what's happening to the plume?
Response 2. The ground water modeling effort conducted by EPA's Laboratory in Ada,
Oklahoma, indicated that the contamination within the aquifer has reached a stage of "dynamic
equilibrium" which means the contamination is changing but is not significantly moving or
spreading from contaminant sources. The ground water flows at approximately 3.5 feet per day
and some of the contamination will move with the ground water flow, but the plumes do not
appear to be significantly spreading. The EPA will further evaluate whether the plumes have
reached "dynamic equilibrium" during its evaluation of the ground water monitoring data to be
collected during implementation of the Institutional Controls and Limited Action alternative.
Question/Comment 3. Has reductive dechlorination been used successfully at other places?
Response 3. Yes, at Edwards Air Force Base and at another east coast site. DuPont has a full
scale system using reductive dechlorination at one of these sites.
Question/Comment 4. Why would EPA only want to use reductive dechlorination on part of
the plume and not on all the plumes?
Response 4. The EPA wanted to test this innovative procedure on a contaminant (PCE) on
which it is believed the procedure has not been tested before.
Question/Comment 5. Can you compare the costs for using reductive dechlorination to the
costs for the other options? Can you use reductive dechlorination on TCE?
Response 5. The EPA estimates that reductive dechlorination will be approximately half the
costs of the pump and treat remedy. You can use reductive dechlorination on TCE The EPA
wanted to test it on the PCE plume to determine how effective it is in addressing the PCE
contamination in the site ground water.
-------
Question/Comment 6. Why not use reductive dechlorination to remediate the TCE? Was
reductive dechlorination evaluated as one of the options at the Ogallala site? Can the EPA
provide a reason that reductive dechlorination was not evaluated as an option?
Response 6. At this time, EPA does not recommend using reductive dechlorination to address
all site contaminants, including TCE, as the effectiveness of the procedure in the ground water at
the Ogallala site is still unknown. The treatability study will mainly focus on PCE, the primary
contaminant present in the plume near the Tip Top Cleaners, as EPA believes that reductive
dechlorination will achieve the best results on PCE. The EPA and NDEQ will also evaluate
degradation of the TCE in the east-PCE plume and evaluate its potential effectiveness in
addressing the TCE on a site-wide basis. Reductive dechlorination was not evaluated as one of
the remediation options because the reductive dechlorination technology is a new, innovative
process which has only recently been implemented at other Superfund sites. At the time the FS
was completed in 1996, sufficient data on the use of reductive dechlorination at other Superfund
sites was not available to allow consideration of its use over the entire Ogallala Site. The EPA
and NDEQ are only proposing to use reductive dechlorination as part of a treatability study to
determine if the process will work in the geophysical setting in Ogallala. It is possible that
reductive dechlorination may not work as sufficient microorganisms may not be present in the
soils to break down the contaminants. Since this technology hasn't been tested on an extensive
number of sites and locations, EPA believed that the fund-lead portion of the plume which
contained PCE would serve as a good location to test this technology to its maximum capacity.
Question/Comment 7. Is the city of Ogallala in violation of any of the state of Nebraska's
regulations?
Response 7. Neither EPA nor NDEQ is aware of any violation of Nebraska's environmental
regulations by the city of Ogallala since the new municipal supply well field was installed.
Question/Comment 8. If no regulations are in violation, then why remediate the plume?
Response 8. Based upon EPA's modeling, if no actions were undertaken it could take in excess
of 33 years to restore the aquifer to beneficial use as a drinking water source. The EPA believes
leaving this contamination in the aquifer for longer than 33 years is an unreasonable length of
time and is not protective of human health and the environment. The plume needs to be restored
for use by future residents of Nebraska and remediation of this plume would allow for this use
within an acceptable time frame. Under Nebraska's law, the Ogallala ground water is a RAC-1
aquifer, which means that it is of highest importance to the state. The EPA believes that there are
natural attenuation processes which are reducing the levels of contamination present in the
plume. The remedy selected in the ROD will allow for the evaluation of these processes to
determine the rate of degradation and the extent of migration of the plumes of contamination.
The EPA will evaluate the ground water monitoring data to determine if additional sources are
present or if additional work is necessary to restore the ground water. If additional work is
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needed, EPA will propose appropriate response actions and seek public input prior to making a
final response action decision.
In part, the selected remedy in the ROD is to address the contamination in the Operable Unit #01
(OU1) plumes by determining if the existing natural attenuation processes are sufficient to
contain the contamination and remediate the site within an acceptable time frame. The
information gathered during the quarterly ground water monitoring will enable EPA to determine
if these processes are preventing the migration of the plumes while reducing the contamination in
the aquifer. Generally, if the ground water data indicates that there are zones of contamination
above 50 ug/1 for each volatile organic contaminant, EPA will determine if additional response
actions are needed to address these zones of contamination. If the ground water data indicates
levels of contamination exists above the 1 X 10 -< carcinogenic risk level, further work will be
required. This work may address any zones where the levels of volatile organic contamination in
ID AS1i?Und ^^ ^ ab°Ve 15°~30° Ug/1 l6Vels' dePendi"g on *e contaminant of concern. The
EPA believes that volatile organic contaminants present in the ground water above the 150-300
ug/1 levels serve as a good indicator of a source area. Future work could include investigative
work, installation of a pump and treat remedy or use of innovative technologies to address the
zones of contamination which may be contributing to the contamination in the aquifer.
Question/Comment 9. How can you say that it will take over 10 years to remediate the plume
when EPA's information shows that the plume has been reduced dramatically over a period of a
year on the PCE?
Response 9. The levels of PCE increased from approximately 400 ug/1 in 1995 to 1400 ug/1 in
1996 in monitoring well NW-4. This increase could have been from fluctuations in the ground
water table which caused a release of a "slug" of PCE into the aquifer or from movement of the
plume. The EPA selected remedy will require quarterly sampling of the ground water
monitoring wells and selected private drinking wells to determine the levels of contamination in
the aquifer. If the data indicates the existence of contamination sources or zones of significant
contamination in the ground water, additional work may be necessary.
Question/Comment 10. How mobile are the contaminants in the aquifer?
Response 10. The mobility of the contaminants varies in the aquifer. Ground water does not
flow m a straight line in the aquifer. Flow lines will fluctuate based upon the soil's physical
properties. Each contaminant will also vary in its flow path based upon physical and chemical
characteristics. These flow characteristics are referred to as retardation factors which cause the
contaminants to not flow as fast as the ground water flows. The concentration of contamination
is also effected by dilution and dispersion which lessens the levels of contamination Higher
amounts of contamination generally exist closer to source areas. The quarterly ground water
monitoring information that will be developed during the implementation of the selected
remedial action will allow EPA to determine more precisely the mobility of the contamination
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Question/Comment 11. Do you think that the contamination is connected to the surface water
in the river?
Response 11. The contamination could be connected to the river. Neither EPA nor NDEQ has
performed hydrologic testing to see if there is direct communication between the alluvial aquifer
and the Platte River. The EPA believes that any contaminated ground water flowing into the
South Platte River would be diluted by the flow rate of the river.
Question/Comment 12. Do you think the contamination is going to stay put?
Response 12. The amount of contamination present in soils will effect the migration of the
contamination in the plumes. If there is a continuing source of contamination contributing to the
levels of contamination in the ground water, the ground water plume may continue to grow and
travel downgradient from the site. If the sources of soil contamination are removed or are no
longer contributing to the aquifer, the plume will continue to migrate but will become diluted as
it migrates from the original source area(s).
Question/Comment 13. Has EPA tested the quality of the ground water downgradient of the
source areas?
Response 13. There are several wells downgradient from the known or suspected source
locations. The EPA sampled some wells by Humphrey's pond, and they were shown to be free
of contamination. It is uncertain whether there may be other downgradient wells which could be
impacted but which have not yet been tested.
Question/Comment 14. How old is the plume?
Response 14. The EPA estimates that some of the contamination in the ground water has been
there for at least 30 years for the plumes present in OU1.
Question/Comment 15. Why spend S4 million or more to do what? We already have clean
water. What does the Ogallala community get for the $6 million effort, as we already have clean
water since we installed a new well field?
Response 15. The money will be spent to protect the health and the environment of those living
near to and downgradient of the contaminated ground water. The EPA will continually look at
ways to reduce costs and increase the benefits for the dollars spent addressing the contamination.
The selected remedy for the Ogallala Ground Water Contamination Site is based upon a thorough
evaluation of alternatives, which considered health risks as well as costs. Two primary threshold
criteria EPA is required to consider by the National Contingency Plan are: 1) protection of
human health and the environment; and 2) compliance with all state and federal requirements.
The EPA is willing to work with the community in order to implement a cost effective, efficient
way to implement EPA's selected remedy. In the ROD, EPA has selected the Institutional
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Control and Limited Action alternative as the remedy for a portion of the Ogallala Ground
Water Contamination Site. The EPA considered the comments provided by the community and
others and determined that the Institutional Controls and Limited Action alternative would be the
best remediation alternative for this site. The EPA will evaluate the information collected to
determine if additional work is necessary. An initial goal of the response action is to restrict
ingestion of contaminated ground water. The ultimate goal of this response action is the
restoration of the aquifer for all beneficial uses.
Question/Comment 16. Who will address the problem at Tip Top where there is no Potentially
Responsible Party?
Response 16. Where EPA does not find a viable responsible party at sites on the National
Priority List, EPA has the option to address these locations using the Federal Superfund with a
share of the funds provided by the state.
Question/Comment 17. What if the Potentially Responsible Parties can't handle this problem;
won't it drive them out of Ogallala?
Response 17. The Superfund law provides that, whenever possible, Potentially Responsible
Parties pay for remedial action at a Superfund site. Potentially Responsible Parties can conduct
the remedial action or EPA can perform the cleanup and then recover the costs it incurs from the
Potentially Responsible Parties. The EPA has worked with and will continue to work with area
businesses and civic leaders and will consider ability to pay. Many small communities
throughout the country have hazardous waste issues. The EPA's experience has been that the
long-term effects of the remediation activities on these communities have been positive and
generally does not drive businesses out of a community. The EPA anticipates that the long-term
effects on the city of Ogallala also will be positive. A business responsible for the contamination
problem does not escape Superfund liability by moving out of its community.
Question/Comment 18. What's the future risk?
Response 18. The future risk is the risk associated with the use of the contaminated ground
water for drinking, the risk of not having a water supply for future residents and the risks to
downgradient receptors needing the water in areas where the contamination has not yet migrated.
There is the current risk of not knowing the full extent of the contamination as well as possible
nsk to all homeowners who may currently be using the contaminated ground water for drinking.
Question/Comment 19. Does not the city ordinance prohibiting the installation and use of
private wells for drinking protect the citizens?
Response 19. The current city ordinance addresses the future installation of private wells for
drinking water use. The ordinance does not restrict use of any private well which may already be
installed. As part of the comments provided to EPA from ASC/TRW, several maps identifying
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locations of private wells located near or close to the ground water plumes were presented to
EPA along with a letter from NDEQ verifying the information presented on the maps. During
the implementation of the selected remedy, EPA will request that this information be verified by
on-site investigations and that any newly identified private drinking water wells downgradient
from .the plumes be tested to determine if the contamination has impacted the quality of drinkine
water from these wells.
Question/Comment 20. Why is EPA recommending an extensive and costly remediation
program when the Proposed Plan states that the source areas have not been identified?
Response 20. The EPA believes that the potential exists for unidentified source areas. The
remedy selected in the ROD will require the evaluation of the ground water monitoring data to
determine if unidentified source areas exist, or potentially exist, at the site. If a source area is
identified, EPA will require that the sources be investigated and responded to appropriately.
Such source areas will be addressed in accordance with appropriate CERCLA authorities.
Question/Comment 21. In the RI, EPA had identified alternatives that were identified as the
quickest and fastest way to address the problem, i.e., air sparging, yet it was not retained. Was
this because of the cost?
Response 21. Cost was a major factor for not retaining the air sparging and similar alternatives.
For the east-PCE plume, the air sparging alternative was carried through the detailed evaluation.
The cost for air sparging this plume only was estimated to be $6,522,641. The EPA has
estimated that utilization of air sparging to address the other Ogallala plumes would increase the
total air sparging costs by a factor of three to four making this alternative prohibitively
expensive.
Question/Comment 22. Is not the air stripping system releasing contamination into the air?
And if this continues for a period of 10 years, is this not a health hazard to those who live
nearby? Would EPA consider air emission treatment for any air stripping system since the
citizens of Ogallala will be exposed for at least 10 years? Are the levels of air emissions which
will be permitted based upon the long-term exposure levels?
Response 22. The air stripping system does release contamination to the air, but at levels below
the state of Nebraska's air emission standards. For any active remediation system, EPA and
NDEQ will evaluate the need for air emission controls during the remedial design phase based
upon long-term exposure.
Question/Comment 23. Is there any tylene (toluene) or xylene pollution coming out of ASC?
Response 23. Typically, toluene and xylene are contaminants from petroleum products
Generally, any contamination resulting from the release of petroleum products must be handled
by the Underground Storage Tank (UST) program. The investigations conducted by the
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Superfund program have not tracked possible xylene or toluene releases from the ASC facilitv
ASC has provided information indicating that toluene and xylene are not migrating from its "
facility. oo
Question/Comment 24. How did that ground water model show natural attenuation occurring
in 33 years? &
Response 24. The ground water model was not calibrated utilizing factors that exist at the
Ogallala site. Standard assumptions were used in the model and were obtained from scientific
reference literature. Since the public meeting, EPA has received additional technical information
regarding the ground water plume and agrees that the model may have used assumptions more
conservative than necessary for the Ogallala site. Consequently, EPA has determined that the
Institutional Control and Limited Action alternative would be the most appropriate remedy to
address the ground water contamination. The EPA will collect sufficient ground water
mformation as part of the remedy to evaluate the rate of the existing natural attenuation processes
and to evaluate if the degradation rates will restore the aquifer as predicted by EPA's modeling
effort as presented in Appendix A of the FS Reports. The EPA will also evaluate the ground
water monitoring data to determine if additional source areas are present within the aquifer
Based upon this information, EPA will then determine if additional responses are needed to
address potential source areas or other localized portions of the aquifer.
Question/Comment 25. Isn't the problem in Ogallala only when you drink the water?
Response 25. The primary human health issue (the risk issue) is the ingestion of contaminated
water. The larger issue is how to protect the uncontaminated ground water by preventing any
farther migration of the contamination and how to reduce the levels of contamination present in
the aquifer The aquifer is a natural resource for which EPA and the State have laws to protect
and, when damaged, cleanup and restore to beneficial reuse.
Question/Comment 26. Has EPA ever collected a tap sample from the Ogallala water system?
Response 26. The EPA reviewed the files and found two tap samples were collected from the
SSllal!,]Water system by the state in Goober 1989. These samples contained TCE above the
MCL. These samples were collected from the Armstrong tap and a tap in city hall The
Armstrong residence contained TCE at 14 ug/1 and the city hall's tap had levels of TCE at 10
ug/1. The MCL for TCE is 5 ug/1. In 1990, the state tested 16 private wells and three were found
to contain volatile organics but below MCLs. These wells have not been retested by EPA.
Question/Comment 27. Is EPA addressing the contamination problem at Offut Air Force base
in Umana:
Response 27. The EPA and NDEQ are both evaluating the problems at the Offut Air Force base
.in Omaha under both the Superfund and Resource Conservation and Recovery Act programs.
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Question/Comment 28. Did EPA do any risk analysis on non-human receptors?
Response 28. No. The contamination levels in the ponds and lakes were determined to be very
low and EPA believes, due to these low levels, significant ecological risks do not exist.
Question/Comment 29. Is EPA's $ 4,000,000 costs only for the pump and treat system for the
western plume?
Response 29. The EPA estimated costs do not consider the cost for the remediation of the east-
PCE plume. The costs for EPA's proposed remedy, as presented in the Feasibility Study
Reports, not including the east-PCE plume, are as follows: estimated Operation and Maintenance
(O&M), 5543,234 per year; capital costs of $3,158,691; total present net worth estimate for the
pump and treat remedy is $8,642,884. The time to achieve cleanup for each plume varied and
the costs were based upon the following remediation times: the west PCE plume, 10 years; the
CT/TCE plume in the upper Ogallala formation, 16 years; and the TCE in the Alluvial formation,
19 years.
For the remedy selected in the ROD, the costs were based on the Feasibility Study Reports,
excluding the east-PCE plume. The costs are as follows: total capital costs of $313,670,
including the installation of 20 additional monitoring wells and institutional controls; annual
O&M costs of $129,180 for ground water monitoring and well maintenance for an estimated
present net worth cost of $1,805,623. The time frames for the selected remedy in the FS Reports
range from 16 years for the TCE/CT in the Ogallala formation and the west-PCE plume to 28
years for the TCE in the Alluvial formation.
Question/Comment 30. If reductive dechlorination doesn't work to clean up the east-PCE
plume, will it cost an additional $2,000,000?
Response 30. It could cost an additional $2,000,000 or more using standard pump and treat
technology. The cost for pump and treat as presented in the FS for the east-PCE plume has a
present net worth of $2,979,011, with capital costs of $1,057,048 and annual O&M costs of
$166,539.
Question/Comment 31. Is the total cost of the EPA's preferred alternative $6,000,000?
Response 31. Based on the cost estimates in the FS Reports, the total present worth cost of
EPA's preferred remedy as presented in the Proposed Plan, for all the plumes, using the pump
and treat technology, was calculated to be $11,621,895.
Question/Comment 32. Is there a schedule for the treatability study using reductive
dechlorination?
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Response 32. Limited field work began in December 1998. The treatability study is scheduled
to begin in the Spring 1999 and will last approximately two years.
Question/Comment 33. If reductive dechlorination is proven successful at the PCE site, would
EPA consider it as the preferred remedy instead of pump and treat?
Response 33. If necessary, the EPA would consider utilizing reductive dechlorination or any
other innovative technology which is effective in addressing the contamination within the
Ogallala Ground Water Contamination Site.
Question/Comment 34. Did I hear EPA say that there is some amount of natural attenuation
attributable to organisms within the PCE plume? Are you sure that there is no natural
attenuation occurring in the plumes?
Response 34. The EPA reevaluated the ground water data collected during our 1995
investigation and has determined that there is sufficient evidence that natural attenuation is
occurring in some areas of the plumes. The EPA basis for this determination is the presence of
cis 1,2-dichloroethene (cis 1.2-DCE) which is a biological degradation product of both PCE and
TCE. The ground water monitoring component of EPA's selected remedy will allow for a more
thorough evaluation of the location of areas where natural attenuation is occurring, the rate at
which it is occurring and to determine if the rate is sufficient to restore the ground water to all
beneficial uses within a reasonable time frame. The presence of the petroleum products from the
nearby Underground Storage Tank (UST) sites may be contributing to and promoting the
biodegradation of the TCE and PCE plumes.
Cis 1,2- DCE is present in several areas of OU1 and is a degradation nroduct of TCE and PCE.
The remedy selected in the ROD includes ground water sampling. Ground water samples will be
collected and analyzed for organic and inorganic chemicals to determine the rate and location
where natural attenuation processes are occurring. This information should also help EPA
determine more accurately how fast the plume is migrating and the length of time needed to
restore the ground water. If natural attenuation is occurring at a rate which is sufficient to restore
the aquifer, no further response action will be necessary. If natural attenuation is not occurring at
a rate which is sufficient to restore the aquifer, EPA will evaluate the ground water information
to determine the appropriate future response actions necessary for plume restoration.
Question/Comment 35. Does EPA believe that the soil contamination in the vadose zone is
adding to the levels of contamination in the plume?
Response 35. The EPA does not have sufficient current information to determine if
contamination is present in the soils in the vadose zone and is migrating to the aquifer. The
EPA believes that the information collected during the ground water monitoring program will
allow EPA to evaluate the presence or absence of potential soil source contamination areas.
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Question/Comment 36. Will source characterization be a part of the remedy?
Response 36. The remedy selected in the ROD requires that ground water sampling and analysis
be performed. The EPA will evaluate that information to determine if potential soil source areas
are present and determine if such sources are contributing to the contamination present in the
aquifer. If additional sources are present, EPA will request that source characterization be
performed.
Question/Comment 37. Why did EPA drop the ex-situ oxidation method from the FS?
Response 37. Cost was one major factor for not further evaluating the ex-situ oxidation method.
A second factor was that the technology was not as proven as the pump and treat remedy.
Question/Comment 38. Are you are planning on starting the reductive dechlorination work in
June, before you have answers on the things that are going on and your answers back to us on
some of the questions that have been raised? '
Response 38. The reductive dechlorination work on the east-PCE plume operable unit is being
conducted initially as a treatability study. The EPA is supporting the state in conducting this
treatability study to evaluate the technology and determine if it is effective in this aquifer and
whether it can be used in other areas of the Ogallala site, if necessary. This study is going to take
approximately 24 months. The ground water monitoring effort will coincide with this treatability
study.
Question/Comments 39. Have you prepared an environmental impact statement on how the
study is going to affect the T-ball schedule?
Response 39. The study will not effect the T-ball schedule. The system was designed and the
wells located so it should not affect the use of the park.
Question/Comment 40. Does EPA decide that this is what they are going to do and then get the
EPAs out there in their hardhats or let a contract to somebody that comes out there and does
whatever you decide?
Response 40. The Superfund process is a multi-step process that includes field investigation and
sampling, an assessment of risks associated with a site to determine if a threat exists to human
health and the environment, and a feasibility study (FS Report) to analyze technologies which
could be used to address site contamination. In the FS process, EPA uses nine criteria to
evaluate the alternative technologies and to compare the technologies to one another during the
decision making process. One of the criteria which EPA is required to consider by the NCP is
state and community acceptance. The EPA considers all significant comments received during
the public comment period, and then makes the decision regarding how to cleanup a site
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following evaluation of all nine criteria. The EPA presents that decision in a document that is
referred to as a Record of Decision.
At all NPL sites, after EPA issues a Record of Decision, EPA begins negotiation with those
parties liable under CERCLA Section 107(a) for implementation of the selected remedy. If
agreement is reached with the responsible parties, a Consent Decree is filed in the local Federal
District Court. The Consent Decree contains a statement of work which identifies the work to be
undertaken to address the contamination at the site in accordance with the ROD. This statement
of work would also have a schedule which would identify the time table to perform this work.
For the Ogallala site east-PCE plume, EPA will consider performing the work if no viable
responsible party is identified. For the remainder of the work, EPA has identified severaf parties
who are potentially liable for the contamination, with whom EPA will seek to negotiate a
Consent Decree for implementation of the remedy selected in the ROD.
Question/Comment 41. Does EPA grant the contract for this work?
Response 41. For work performed by EPA, EPA would use a contractor to do the work under
EPA's direction. For work performed by the state, the state makes the decision regarding use of
a contractor to perform the work. For work performed by the responsible parties, the responsible
parties would make the decision regarding use of a contractor and obtain EPA's approval of such
contractors under the Consent Decree. The EPA does provide oversight of the work that is
performed at the site.
Question/Comment 42. Who's funding the treatability study?
Response 42. The EPA has issued a grant to NDEQ, using Superfund monies for the
performance of the treatability study. The EPA will be involved in the evaluation of the study
results.
Question/Comment 43. Will the treatability study continue to be funded by Superfund?
Response 43. The EPA has agreed to fund the entire treatability study with Superfund monies.
Question/Comment 44. Where can I get health effects information concerning the air stripping
alternative?
Response 44. The EPA will provide that information to any one who requests it. If it is
determined at a later date that a pump and treat remedy with air stripping is necessary for the site,
an evaluation of the health effects for the air emissions will be part of the Remedial Design. The
EPA would announce the completion of the design in the newspaper and a copy will be part of
the Administrative Record which is located in the Ogallala City Library.
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Question/Comment 45. Will EPA extend the public comment period for the Proposed Plan?
Response 45. The public comment period was extended an additional 45 days.
SUMMARY OF WRITTEN COMMENTS RECEIVED FROM THE COMMUNITY
DURING EPA's PUBLIC COMMENT PERIOD.
Question/Comment 1. If the businesses in Ogallala have to pay the large amount of money to
fix the wells that may or may not someday be used, these businesses would not make it. Our
drinking water is safe now. If Ogallala would lose these businesses, people would move out of
town and even more businesses would close. I enjoy living in Ogallala and hope the EPA would
choose a less costly alternative.
Response 1. The EPA has selected the Institutional Control and Limited Action alternative in
the ROD for remediation of site contamination. The EPA will evaluate the analytical results
from the quarterly ground water sampling effort to ensure that the remedy is protective of human
health and the environment. An inventory of private wells within Ogallala will be conducted to
determine if anyone is using the contaminated ground water. Any newly identified private wells
downgradient of the plumes and potentially impacted by the contaminated ground water will be
tested. Compliance with the city ordinance will be evaluated to determine its effectiveness in the
controlling ingestion of contaminated ground water. The EPA will work with those businesses
potentially liable under CERCLA for the contamination to address the ground water in a manner
that is protective of human health and the environment and is cost effective. The EPA believes
that the Institutional Control and Limited Action alternative will provide such a remedy.
Question/Comment 2. A comment letter was received supporting ASC's efforts to clean up the
ground water in Ogallala.
Response 2. The EPA is aware of ASC's efforts to restore the quality of the ground water
beneath and downgradient of the facility and has incorporated ASC's actions into the selected
remedy.
Question/Comment 3. Why fix something that is not broken? The Ogallala water supply has
been corrected. It is out of line to charge Ogallala's businesses and drive them out of business
for something unnecessary. Please take a serious look before this happens. I have lived in
Ogallala next to one of the businesses for 30 years and if I am not concerned, why is EPA? We
want to keep our small community, not destroy it.
Response 3. The EPA is concerned about what the residents of the community think of any
proposed action. This is why EPA holds public meetings and provides an opportunity for the
pubhc to comment on actions EPA proposes prior to the remedy selection decision. As stated in
the ROD, the EPA modified the proposed remedy and has selected the Institutional Control and
Limited Action alternative. The EPA was given the responsibility to address contaminated
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ground water and to identify the alternative that would be protective of human health and the
environment. One criteria that EPA considers in-selecting a remedial action is community
acceptance. Based upon community input and other factors, EPA has selected the Institutional
Control and Limited Action alternative.
Question/Comment 4. Several comments were received which supported the following: 1)
ASC/TRW has been doing their share to clean up the contaminated ground water by operating
the air stripper remediation system for the last 4 years. This system has significantly reduced the
contamination in the aquifer and encourages ASC/TRW to continue this effort Many of the
writers work at the ASC facility and would hate to loose their jobs for something that isn't
necessary. 2) The city of Ogallala has installed a hew well field away from the contamination
and also passed an ordinance prohibiting construction or use of private wells for domestic
consumption. The citizens of Ogallala are paying for a new well field. The commentors are life-
long residents of Ogallala, drink the water and have no health problems related to drinking the
water from the municipal water supply system. 3) If the citizens of Ogallala are required to pay
more taxes to support EPA's proposal, it would increase our taxes and force more people out
Businesses have been closing in Ogallala and our downtown has a lot of empty spaces For these
reasons, the writers ask that EPA use the least expensive method possible to further clean the
ground water in this site and not impact the economy in this community in a bad way.
Response 4. The EPA has considered the comments of concerned residents and other factors
and has decided that the Institutional Control and Limited Action alternative will provide for '
protection of human health and the environment while restoring the ground water for unlimited
use. The ASC/TRW's system has been effective in restoring the ground water downgradient
from its facility. The work associated with the restoration of the ground water will be paid for by
those that are potentially liable under the Superfund law. For those areas requiring work where
EPA does not identify a viable responsible party, money from the Superfund program will be
used to pay for the appropriate action.
As part of the remedy selected in the ROD, EPA will require ground water monitoring to
determine whether or not the contamination plumes are migrating. The EPA will also determine
whether all residents in the areas of the contamination are provided water from the city system
The EPA believes that these actions will allow for the evaluation of the existing natural
attenuation processes and to determine if these processes are occurring at a rate which is
sufficient to restore the aquifer to all beneficial uses within a reasonable time frame If zones of
unacceptable high levels of contaminated ground water are present, the EPA will also look for
innovative ways to restore these areas, if necessary.
Question/Comment 5. The writer wanted to express his opinion as a citizen of the city of
Ogallala regarding EPA's proposed cleanup. First, the contamination as it exists today is not a
threat to the citizens of Ogallala or those in the surrounding community. The EPA estimate is
the contamination would disappear naturally within 30 years. The EPA wants to spend millions
of dollars to prevent contamination which could only affect someone drilling an illegal well and
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consuming the ground water. The economic impact of EPA's proposal will cause far more
damage to this area than the contamination. If local businesses such as ASC and Ogallala
Electronics are forced to pay for the proposed cleanup, the writer doubts they will remain in
business. At any rate it seems ridiculous that anyone should have to pay for such overkill. It
seems that the steps which have already been taken are more than sufficient to protect the
environment and citizens of this area. It is also the writer's opinion that the vast majority of
citizens in this area share his opinion.
Response 5. The EPA and NDEQ have considered these concerns. The EPA has selected the
Institutional Control and Limited Action alternative in the ROD as the remedial action based on
community input and other factors. The EPA believes this action is protective and effective and
that the ground water monitoring data to be collected during the implementation of the remedial
action also will support that belief. The EPA will also verify the information presented during
the public comment period which indicates that no existing private wells are located within the
contaminated ground water use areas. The EPA will require that a survey be performed to locate
any existing wells and that, for any newly identified private well, ground water sampling be
performed. The EPA and NDEQ will ensure that all residents of Ogallala and the future
residents of Ogallala are protected from the ground water contamination.
Questions/Comment 6. Other business have also caused the contamination. What are they
doing? The ordinance for the city of Ogallala on personal water wells shows, that no one can
drill a water well in the city limits without a permit. It is also very hard to drill illegally and try
to hide a drilling rig boom. Also, personal water wells in the city limits can not be used for a
domestic well, only for using on lawns or gardens. Most domestic wells or other wells in the city
limits are drilled down past the shallow and are in the Ogallala aquifer. It really isn't necessary
for the EPA to take the "preferred alternatives."
Response 6. The remedy selected in the ROD includes measures that will allow for continued
evaluation of the effectiveness and protectiveness of the Institutional Control and Limited Action
alternative by monitoring the quality of the ground water. Additional work may be required of
parties responsible under the Superfund law. Such work may include additional source
investigation work if new sources are found or the use of innovative technologies for treatment
of zones of unacceptable high levels of contamination in the aquifer. The EPA and NDEQ will
conduct a treatability study on the east-PCE plume using reductive dechlorination to determine if
this alternative is effective in treating the PCE contaminated Ogallala ground water and is
protective of human health and the environment. The EPA expects all viable parties potentially
responsible for the contamination to participate in restoring the ground water.
Question/Comment 7. Additional systems, if needed, should be as inexpensive as possible so
that the economy of the community not be impacted in a negative way.
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Response 7. In the Superfund process, EPA evaluates cleanup alternatives using nine criteria as
set forth in the National Contingency Plan. Two threshold criteria each alternative must meet is
that the alternative must be protective of human health and the environment and comply with all
state and federal regulations. Once it is determined that a remediation alternative complies with
these .two threshold criteria, EPA evaluates the alternative against the seven modifying criteria.
Cost is one of the modifying criteria. The EPA's FS evaluated several different alternatives. The
EPA's preferred remedy, as set forth in the Proposed Plan, included a pump and treat component
which would have required additional systems to be installed. The EPA considered the
comments submitted by members of community and other information and has selected the
Institutional Controls and Limited Action alternative in the ROD to address the contamination in
the aquifer. The remedy selected in the ROD is considerably less expensive than the Proposed
Plan preferred remedy.
Question/Comment 8. The writer wanted to register their disagreement with the EPA's plans
for remedying the water situation in Ogallala. It appears that Ogallala has been singled out for
punitive action. The writer does not deny the argument that a water problem existed. It has been
remedied with the new well field north of town. The point was made at the public meeting that
you want to be sure that if an illegal well is drilled that water will not be contaminated. How
could you allow that illegal well to be drilled? Is that not also under your regulation? ASC and
TRW have taken action to clean up the problem in their area. If they are asked to come up with
more money the writer fears the city of Ogallala will lose it's top employer. The economic
impact could be devastating for Ogallala. Are you perhaps looking at TRW because of their
national reputation, thinking they are the only ones with the ability to pay? You go after TRW
and none of the others, who's to say they (TRW) will not turn around and sue these small
businesses that have no resources, forcing them out of business. How many cities could pass
your standards if you were to go in and test their water supplies? Any city on the aquifer with a
manufacturing facility, a commercial dry cleaner, automobile repair shops, is likely to have
contamination. We must find a way to take steps with a reasonable price tag.
Response 8. Ogallala has not been singled out for punitive action. The state of Nebraska held
discussions with potentially responsible parties in Ogallala to have them address all
contaminated plumes. Those discussions failed to produce an agreement for the necessary work
and the site was referred to EPA by the state of Nebraska. The site was placed on the National
Priorities List (NPL) in 1994. The installation of the well field north of town provides clean
water to the residents of Ogallala. The new well field does not address the contamination in the
aquifer. The EPA is concerned about the potential of anyone within and/or downgradient from
these plumes using this contaminated ground water. The well field supplies water to residents of
Ogallala that are hooked up to the system. There are several domestic wells in the aquifer that
could be effected by the contamination in the ground water. The EPA's concern is not for just
new illegal wells but for current wells which are being used which receive contaminated ground
water. The EPA commends the remediation efforts that ASC/TRW have undertaken. These are
excellent first steps. Additional work efforts will include ground water monitoring, institutional
controls and may include other source control efforts if necessary. The EPA will look for the
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city of Ogallala to monitor the city ordinance, the effect which will be to restrict access to
contaminated ground water within the city's jurisdiction. The EPA and NDEQ will also work
closely with the city of Ogallala to identify all wells currently installed within the area of concern
and will closely monitor any future well installation. The EPA will look for all responsible
parties to participate in remediating the site, not just ASC/TRW. The EPA and the states within
Region VII do test the water supplies. Several cities within the state of Nebraska are in the
process of remediating the contamination within their aquifer which was caused by
manufacturing, gas stations, dry cleaning or other business operations. The EPA does seek
reasonable, effective and protective solutions to these problems.
Question/Comment 9. The commentor favors natural remediation of contaminated ground
water in Ogallala, Alternative 1 with a minimum amount of monitoring, and opposes requiring
investments in the expedited remediation projects. NDEQ did a good job in discovering the
chlorinated hydrocarbons in Ogallala's public water supply. That contaminated drinking water
problem has been solved through installation of a new well field by the city of Ogallala. Without
the efforts of our state and national environmental agencies, however, this serious problem would
not have been discovered as quickly nor would it have been rectified as promptly. For this we
owe you and our Nebraska environmental agency our thanks. The issue now is how quickly
should contaminated ground water in an area that is less than five percent of the total area of
Ogallala be restored to human drinking water quality? Contamination poses no harm to non-
drinking water uses. The EPA has not made any statement that the contaminated ground water in
Ogallala is a hazard in non-drinking water applications. Moreover, all expedited remediation
alternatives would bring the chlorinated hydrocarbon contaminants to the land surface in the city
of Ogallala, whereas natural remediation would not bring any of the chlorinated hydrocarbons to
the surface of the ground in the city. No cost/benefit justification of expedited remediation has
been performed. Natural remediation of the contaminated ground water in situ solves the ground
water contamination problem in a reasonable time without surface exposure risk. The marginal
benefit of using expedited remediation to solve the problem in 15 years rather than 33 years is
not useful to our community. The lack of benefit cannot justify $7 million burden on Ogallala
businesses with no return for the business or for the community is completely unwarranted and
would have a strong negative economic impact on the city of Ogallala. In a context of billion
dollar budgets, $7 million is not much money. In an Ogallala context, however, S7 million is a
very large amount of money. This amount would run our entire Ogallala school system for a
year. This amount is twice as much as was spent for the new Ogallala well field, the city's real
damage from the ground water contamination. This amount is seven times the total value of all
1997 commercial construction in Ogallala. Since there is no significant benefit from expedited
remediation proposed by EPA and since private payments for expedited remediation place an
unwarranted burden on Ogallala businesses, the commentor respectfully requests that the EPA
choose in situ natural remediation, Alternative 1 on page five of the public hearing document
modified with limited monitoring to solve the Ogallala ground water contamination problem.
Response 9. The EPA considered these and other similar comments submitted by the members
of the Ogallala community and other information and has selected the Institutional Controls and
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Limited Action alternative in the ROD as the remedy for this site. This remedy includes a
ground water monitoring component which will enable EPA to confirm that the site is being
remedied by natural attenuation processes at a rate which will restore the ground water within a
reasonable time frame. Ground water monitoring will also enable EPA to determine if source
areas .or zones of unacceptable high levels of contamination exist which would unreasonably
extend the length of time for the natural hydrogeological and biochemical forces to remove the
contamination from the ground water. The EPA has not evaluated the use of the contaminated
ground water for non-drinking purposes. The EPA would not restrict the use of this water for
irrigation of crops or gardens. The water could be used for livestock or industrial uses. The EPA
would limit the domestic use of this water for bathing and showering due to inhalation exposure.
The EPA recognizes that contamination varies in portions of aquifer and would want to evaluate
the uses of the ground water based upon the concentrations of contaminants as well as the
specific volatile organic compounds that are in a particular area.
Questions/Comments 10. The following comments were offered: the city of Ogallala does not
allow private wells to be installed within 300 feet of a municipal well. The city of Ogallala is
bordered by the South Platte River. Since the cause of concern was removed by the installation
of a new well field, why is EPA insistent in handling this problem with no flexibility? All the
alternatives fall within the same time frame, whether it takes 10 years with pumping or 33 years
with natural attenuation, it all will take time. Alternative two (limited action) is the most cost
effective. Was Alternative three preferred as it will perpetuate EPA's activities at the expense to
the city of Ogallala? The writer is supportive of NDEQ's innovative work but believes that the
limited action alternative makes the most sense to resolve the problem. Why not name more
Potentially Responsible Parties? Is there a prejudice on the part of EPA concerning which
parties were singled out as possible sources of the ground water contamination? What is the
source of the carbon tetrachloride?
Response 10. The city's ordinance only effects the installation of new wells. Existing ground
water supply wells within the city could be used for drinking purposes. The new well field
provides a clean source of water to residents that get their water from the city. All others that
rely on private wells for drinking or other purposes could be effected by this contamination.
Based upon community response and other factors, EPA has selected the Institutional Controls
and Limited Action alternative in the ROD as a substitution for the preferred remedy identified in
the Proposed Plan. The EPA will evaluate the information once eight quarters of data are
available to determine if this action is protective of human health and the environment. In all
situations such as the Ogallala ground water contamination, it is EPA's policy to identify all
PRPs under the law based upon available information. The EPA has done so in this case to the
extent provided by available information. The EPA has not yet been able to identify the source
of the carbon tetrachloride. The EPA will be in the Ogallala community until aquifer restoration
is complete. The EPA proposed the pump and treat as its preferred remedy because the agency
believed that pump and treat was the best alternative based upon the information EPA had at the
time the Proposed Plan was issued. During the public comment period, EPA received additional
information concerning the ground water contamination. The EPA has also evaluated its
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guidance on natural attenuation, published after the release of the Feasibility Studies, which
encourages monitored natural attenuation remedies at sites where the sources have been
addressed and the threats or potential threats to human health are low. The EPA believes natural
attenuation is an appropriate remedy for this site. The ground water monitoring effort will
provide EPA with sufficient information to confirm the levels of contamination and the
migration patterns of these plumes and identify the existence of potential source areas. Based
upon existing information, EPA believes that the Institutional Controls and Limited Action
alternative will be a cost efficient, effective remedy.
Questions/Comments 11. Several comments were received from Nebraska Health and Human
Social Services regarding consistency between the Proposed Plan and the risk assessment They
were: 1) 1,1-dichloroethylene rather than 1,2-dichloroethylene should be listed as a chemical of
concern. 1,2-dichloroethylene is present but did not contribute significantly to the site risk. 1,1-
dichloroethylene was the main contributor to the excess cancer risk quantified for this site from
mgestion of ground water; this change is needed in several places in the proposed plan; 2) bis(2-
ethylhexyl)phthalate was retained as a chemical of concern in the risk assessment. The
quantified health risk, however, was not significant in relation to the other site chemicals of
concern; 3) concentrations of 1,1-dichloroethylene and vinyl chloride did exceed maximum
contaminant levels in both municipal water supply wells and monitoring wells (1,1-
dichloroethylene had a high concentration of 26 micrograms per liter (ug/1), compared to the
maximum contaminant level of 7 ug/l)(vinyl chloride had a concentration of 3 ug/1 in a NDEQ
well, compared to its maximum contaminant level of 2 ug/1); 4) the baseline risk assessment
indicated a maximum detection of TCE at 485 ug/1 rather that the 290 ug/1 stated in the Proposed
Plan and the baseline risk assessment indicated a detection of PCE at 495 ug/1 rather than the
1400 ug/1 as stated in the Proposed Plan; 5) the baseline risk assessment indicated a maximum
detection of carbon tetrachloride at 100 ug/1 rather than the 50 ug/1 as stated in the Proposed Plan
Regarding the lack of an ecological risk assessment, Nebraska Department of Health and Human
Social Services is not comfortable in stating that "no danger to any sensitive animal population-
exists.
Response 11 to Nebraska Department of Health and Human Social Services: The EPA agreed
with the above comments regarding the baseline risk assessment and has incorporated them in
the ROD.
WRITTEN COMMENTS RECEIVED FROM THE RESPONSIBLE PARTIES:
Question/Comments TRW/ASC's:
General - Question/Comments:
General- Question/Comment 1. TRW/ASC disagree with EPA's proposed remedy and believe
that the limited action remedy is a more appropriate remedy for the site. The EPA investigation is
inadequate, failed to evaluate key alternative remedies which likely will prove to satisfy all
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ARARs and has based its decisions on outdated, simplistic data. A remedy using natural
attenuation and a phased approach is appropriate for several portions of the plume, in particular
the west PCE and TCE plume in the alluvial aquifer. This approach should be used as the
contaminated ground water is not being used for drinking and should not be used for drinking
water in the future due to high concentrations of nitrate.
Response 1. The EPA has selected the Institutional Controls and Limited Action alternative
remedy in the Record of Decision. The EPA will evaluate the ground water information as it is
collected to confirm that natural attenuation processes are effective in reducing the contamination
in the ground water in an acceptable time frame and to determine if potential sources of
contamination and zones of unacceptable levels of ground water contamination exist. The EPA's
policy on natural attenuation provides that natural attenuation is more acceptable and best
achieved in conjunction with implementation of source control response actions Outside of the
action which is currently underway at the ASC/TRW facility, no other ground water actions have
been instituted at the Ogallala site. High levels of nitrates are becoming more common in ground
water beneath agriculture lands and do not prohibit the use of the water for drinking. The ground
water can be treated using reverse osmosis to remove the nitrates. Nitrate contamination has
been found m many of the communities within Nebraska and other farming communities in the
mid-west.
Remedial Investigation - Questions/Comments:
Remedial Investigation - Question/Comment 1. The data is not current. The FS is based upon
data from 1995-96. The more recent data presented to EPA via reports indicate that the levels of
contamination present at the ASC facility have greatly diminished. ASC/TRW believes EPA
should use a phased approach to ground water cleanup. Additional data is needed before a
remedy is selected to accurately reflect site conditions. Additional information is needed to
determine if natural attenuation is present and if so, at what rate the compounds are being
reduced. 6
Remedial Investigation - Response 1. The EPA agrees that the data used in the FS was not the
most current. Data presented to EPA during the public comment period indicates that a
contaminate plume is still present downgradient from the ASC/TRW facility. The monitoring
wells at the ASC facility may indicate that the remediation efforts are near completion, but the
levels in the effluent from the extraction wells indicate that the contamination is still present and
needs to be removed. The EPA agrees that additional data is needed and has selected the
Institutional Controls and Limited Action alternative in the ROD. This alternative includes a
ground water monitoring component for the collection of data to confirm that natural attenuation
processes are sufficient to reduce the contamination in the ground water within an acceptable
time frame.
Remedial Investigation - Question/Comment 2. Plume maps fail to recognize two separate
hydrostratigraphic units, exaggerating the plume and rendering the maps useless. The EPA
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describes the plumes as "large, covering the majority of the area of the city of Ogallala". At the
ASC/TRW facility, there exists a confining clay layer at approximately 100 feet deep which
separates the hydrostratigraphic units into upper and lower units. The upper unit is composed of
the Alluvial formation and the upper Ogallala formation. The lower hydrostatrigraphic unit is
composed of the lower Ogallala formation. Monitoring wells EPA-01 and ASC-03A are in the
upper Ogallala, not in the lower Ogallala as depicted in the RI Report. The location of
monitoring well EPA-01 is wrong. This well is within the capture zone of the ASC remediation
system. The TCE present in EPA-01 should not be connected to wells downgradient and, again,
should be reflective of the contaminant levels within the upper hydrostratigraphic unit.
Remedial Investigation - Response 2. Plume maps will be revised based upon the monitoring
data that will be generated during the implementation of the remedy. Locations of all monitoring
wells will be surveyed and entered into a Geographical Information System (CIS) system. The
newly acquired data will be compared with the information in the remedial investigation report.
The screened interval of EPA-01 is at a depth of 70-90 feet below land surface and therefore the
data was interpreted to represent the upper portion of the Ogallala formation. Field measurement
data from the 1996 sampling effort is now included in EPA's Administrative Record for the site.
Remedial Investigation - Question/Comment 3. ASC/TRW could not reconstruct the plume
maps presented in the RI as the field measurement data was not presented. Based upon
geochemical information obtained from the ASC/TRW facility, the nitrate concentrations
detected in the ground water from monitoring wells screened in the upper hydrostratigraphic unit
exceed the drinking water standards such that the upper hydrostratigraphic unit is not considered
suitable for use as a potable water source.
It should be concluded that the increasing levels of TCE reflected in the plume maps (5-1 for
1995 and 5-2 for 1996) for the alluvial formation are necessarily caused by an impact from some
other source than the ASC facility. These higher 1996 TCE concentrations are due to increased
TCE concentrations detected in monitoring wells completed around the OEMI property.
Remedial Investigation - Response 3. Ground water monitoring data that will be generated
during implementation of the response action will enable EPA to determine if additional sources
of TCE are present in the soil and migrating to the aquifer. Ground water monitoring data should
also allow EPA and others to construct plume maps to determine the locations of these source
areas.
Remedial Investigation - Question/Comment 4. The RI failed to investigate and obtain the
necessary and appropriate data required to evaluate the effectiveness and feasibility of natural
attenuation, and thus the RI cannot be used to compare competing alternative remedies.
According the EPA's guidance on natural attenuation, the following information should be
collected to determine if natural attenuation is a remedial alternative; historical ground water
and/or soil chemistry data to demonstrate whether there is a clear and meaningful trend of
decreasing contaminant mass and /or concentrations over time at appropriate monitoring or
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sampling points; and the data needed to determine the types of natural attenuation processes
which are active at the site and the rate such processes are occurring at the site and microcosm
studies. Ground water samples should be analyzed for parameters such as dissolved oxygen,
total organic carbon, biological oxygen demand, ammonia, nitrate, soluble iron, sulfate, ferric
iron oxides, carbon dioxide and sulfide. Using actual site data rather than hypothetical
information is the only technically supportive approach.
Remedial Investigation - Response 4. The EPA monitored natural attenuation policy was
released after the release of EPA's RI. Therefore, the RI was not designed to obtain the specific
data that was necessary to adequately evaluate monitored natural attenuation as a remedial
alternative in the FS Reports. However, based on information currently available, EPA believes
natural attenuation is the appropriate remedy for the site. Information will be collected during
the ground water monitoring portion of the selected remedy to confirm the rate and effect of
natural attenuation on the contamination present in the aquifer at the Ogallala site.
Baseline Risk Assessment - Question/Comments:
Baseline Risk Assessment - Question/Comment 1. Detailed comments were submitted in
letters dated December 9, 1997, and March 3, 1998, which state that the risk assessment is
significantly flawed resulting in inaccurate, greatly exaggerated risks and cannot reliably be used
to formulate the appropriate criteria for remedy selection at this site. The following is a
summary of the flaws: the assessment exaggerates the potential risk by assuming that there is a
completed ground water exposure pathway via the old municipal well system; fails to consider
the city ordinance; relies on the maximum detected concentrations; assumes the maximum to
extend over a period of 30-years; uses linear low dose extrapolation methods instead of threshold
assumptions; exaggerates the surface water pathway by using the maximum value of vinyl
chloride found in one of five ponds; and exaggerates the risk of dermal contact. The PRPs
calculated the site risks using EPA's methods for a RME for adults and children who might be
exposed to the contaminants from garden sprinklers in the summer months and incidental water
mgestion. The site risks were 1.4 x 10 '7 for adults and 3.4 x 10 - for children. The hazard index
for adults and children were 0.0026 and 0.0032 respectively.
Baseline Risk Assessment - Response 1. The baseline risk assessment was performed in
accordance with EPA's established protocol. The EPA uses procedures which provide a
conservative estimate of the site risks. The risk assessment also identifies these conservative
assumptions and notes that these estimates are very protective. The city's ordinance was not
considered because it does not prevent the use of the ground water from a ground water well
which is currently in place, no matter the level of contamination present in the well. In addition,
the city's ordinance would not protect downgradient wells located outside the city's jurisdiction!
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Feasibility Study - Question/Comments:
Feasibility Study - Question/Comments 1. The ground water modeling is invalid and does not
support the preferred pump and treat remedy. The EPA model indicates that the plume reaches
dynamic equilibrium after 12 years; therefore., the plume has stabilized and is no longer
migrating. The model does not support the selection of an active ground water pumping
remediation over natural attenuation. The time difference between pumping and non-pumping is
smaller than the uncertainty in the model predictive accuracy. There is no documentation to
support a natural attenuation cleanup time of 33 years and EPA's estimate of 10 years for
cleanup under a pump and treat scenario. The model is overly simplistic of the conditions at
Ogallala.
The solute transport modes are completely unacceptable for the following reasons: 1) the
transport models were not calibrated using observed data; 2) transport parameters were not
selected to generate concentration gradients that match the observed plumes; 3) mass loadings
were assigned without any basis; 4) if the loadings were accurate then the observed
concentrations of contaminants at the ASC facility should be approximately 6,000 ppb; 5) the
number of operational years are also exaggerated; and 6) there are several errors which show that
the levels of TCE increase with the start of remediation.
Feasibility Study - Response 1. The EPA modeled the site in an attempt to determine what
steps were needed to restore the ground water. The position of EPA is that all existing
simulations are preliminary, but are, nevertheless, valuable as conceptual tools to aid in
understanding the aquifer system. As stated in the model documentation, EPA believes that
there is insufficient field data to generate a definitive model or select a treatment alternative
without further ground water contaminant information. It is EPA's position that further field
data is necessary and possibly additional supplemental modeling. This additional information is
also needed to verify whether a steady state has been achieved in the aquifer and that the plume
is not continuing to migrate and that dynamic equilibrium has been attained. Further field study
is needed to provide proper model input for flow and mass transport to verify natural attenuation
processes and to estimate kinetic rates of source and solute decay.
None of the simulations presented in the model include an estimated 33-year clean-up time for
natural attenuation. There are three different model scenarios:!) Do-nothing with a 22 year
cleanup time; 2) low ground water extraction rate with a 15-year cleanup time; and 3) moderate
ground water extraction rate with a 10 year cleanup time. Continued contaminant recharge from
an active source was not considered in any simulation. Essentially, a contaminant source was
introduced into the domain to generate a pulse of contaminant and the model was allowed to
equilibrate to the concentrations observed in 1995. The contaminant source was then turned off
for all following time steps. The scenarios presented in the model merely estimate the potential
time to capture the plume as it was estimated to exist and do not address the possibility of
continued contaminant contribution. The low pumping rates used in the simulations were
insufficient to induce a significant ground water gradient and conceptually serve only to capture
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the contaminant plume as it migrates past the extraction well at fairly normal advective
velocities. In fact, an active contaminant source may conceivably extend cleanup time for either
pump-and-treat or natural attenuation well beyond the predicted period. Therefore, an
understanding of source behavior is a critical criteria in evaluating the environmental threat
posed by this site and can only be determined from additional field sampling and monitoring.
Regarding the concern that the flow model is overly simplistic, EPA believes that the flow model
was reasonably calibrated with the steady state as well as time varying potentiometric data. The
steady state flow model shows good correlation to the water level map from Bjorklund and
Brown (1957). The background hydraulic conductivity values were varied and the bed
elevations and stages from the South Platte River were reasonably adjusted to assume good
calibration. As discussed in the model documentation, the transient model was calibrated against
the available potentiometric surface and a reasonable water balance was achieved. Supplemental
lithologic and hydrogeologic field data are required to augment the limited data available for this
site.
Regarding the solute transport models, EPA agrees that additional data is necessary to confirm
solute and source distribution and concentration. This information should be collected prior to
installation of an active remediation system. The transport model was qualitatively calibrated by
comparing the spreading of the plume not by comparing the well specific data because of the
scarcity of data. The initial values of the half-lives for TCE, PCE and CT were increased by a
factor of two and the initial values of distribution co-efficients were decreased by factors ranging
from two to four in order to develop simulated plumes similar to those observed. Limited plume
concentrations data (both spatial and temporal) were available for comparison. A portion of the
1995-observed TCE plume in the overlying layer (alluvium) appeared to be missing in the west
when compared to that of the upper Ogallala. Because TCE was found in the upper Ogallala in
the west and the simulation results showed that TCE diffused toward the west of the sources,
TCE sources used for the upper Ogallala were also assumed to be partially contributing to the
alluvium. The results indicated that the concentration data collected in 1995 may be incomplete
and inadequate to represent the field condition accurately. Though not definitive, the present
transport simulations are therefore useful in directing the potential areas where contaminants are
predicted to migrate and highlighting areas where additional field drilling and sampling might be
efficacious. Transport parameters were selected from the literature and a.sensitivity analysis was
performed to investigate their relative effectiveness.
The rational for the model mass loading rates are: a concentration for the chemical less that the
maximum solubility was selected (typically half) and a flow rate was calculated for the assumed
concentration to enter the desired mass at each source. The mass loading rate was adjusted along
with other parameters in several model runs so that the simulated concentrations of contaminants
in the ground water match the observed concentrations. It is also not true that the mass loading
was assigned to the ASC facility without any basis for their estimates. Any observed
concentrations at the site probably do not represent historically high values. Rather, they were
the concentrations first found a number of years after contamination ensued and presumably
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some years after mass addition to the source ceased. If one assumes that the source is decaying,
as would be suggested in a natural attenuation scenario, then past contaminant loading should
logically be much higher than observed values. Such assumptions are logical and often
necessary to calibrate mass transport simulations to observed plumes.
Feasibility Study - Question/Comment 2. The FS fails to accurately characterize the status of
the current ground water usage, relevant controls and the status of the ground water as a drinking
water source. The FS assumes that residents are drinking the contaminated ground water either
through the municipal supply system or through private wells and that the ground water within
the impacted plume will be used as a drinking water source in the future. A new well field has
been installed. The capacity of the new well field is approximately 9,600,000 gallons per day.
To date, the highest peak month of water usage was at 3,049,928 gallons of water per day. In
1992, the population of Ogallala was less than 6,000 people. Current demographics indicate that
Ogallala is holding steady or declining.
Feasibility Study - Response 2. The EPA believes that there could be residents within Ogallala
and downgradient from these plumes that are not receiving water from the city. As long as these
supply wells are able to deliver water to those private residents, the risk remains. Ground water
monitoring and a well survey, as components of the selected remedial action, will enable EPA
and NDEQ to determine if private residents are being exposed. Monitoring will also enable EPA
and the state to determine if the plumes are migrating to areas where additional persons could be
exposed to this contamination.
Feasibility Study - Question/Comment 3. The ground water in the Ogallala region and within
the Ogallala city limits has been impacted by nitrate at levels above MCLs and may not be
suitable for drinking. The EPA did not assess the other constituents in the water. In 1991, the
data collected by ASC/TRW indicate that nitrate levels of 13-14 mg/1 were present and levels of
sulfate exceeded 250 mg/1. In January 1996, the state of Nebraska collected a split and found
nitrate at 16 mg/1 and indicated that levels of nitrate exceeded 50 mg/1 in areas close to Ogallala.
Other state officials indicated that levels of 8 to 9 mg/1 of nitrate are common west of the city of
Ogallala. The EPA cited Meyer Camper Court and the Village of Paxton for nitrate violations
recently. In 1991, the city of Ogallala, using the supply from the old system, was also cited for
fecal bacteria contamination. Chronic coliform violations also occurred near Ogallala. The
ground water in the alluvial formation contains high levels of fecal bacteria, chronic coliform and
nitrates making the ground water unsuitable as a drinking water source. To resolve this issue,
historic and current information from municipal and private wells needs to be evaluated.
This is significant as under Nebraska law, if ground water is not otherwise suitable for drinking
resources should not be allocated for remediation of the VOCs in the plume. Title 118, of the
Nebraska Code states: " Pollution occurrences will be of lowest importance, RAC-3, if the
ground water involved is not used, or likely to be used, as drinking water." Nebraska Ad Code
Title 118, Appendix A, Part II, Step 7. The FS needed to evaluate and accurately characterize the
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suitability of the plume area as a drinking water source absent the VOCs. It is very important to
determine if these plumes can be considered a viable source of drinking water.
Feasibility Study - Response 3. According to NDEQ, the Ogallala ground water is a RAC-1
aquifer and is of highest importance to the state. The inorganic chemicals present in the aquifer
have not prompted NDEQ to change its classification from a RAC-1 to a RAC-3 There are
many reasons for which ground water samples exhibit exceedances in nitrates, coliform and
bacteria. Not all reasons relate to the quality of the ground water. Some relate to the way the
samples were collected and the care in the handling of the sample from the time of collection to
he time of analysis. Nitrate contamination is of concern in the agriculture community and as
Uie ground water is only 1 0 feet from the surface, nitrates will be present in the Ogallala aquifer
During the implementation of the remedial action, nitrates in drinking water wells and selected '
monitoring wells will be evaluated to determine the extent of this problem.
Feasibility Study - Question/Comment 4. There are no private drinking water wells within the
plume areas. Attachments 2-1 through 2-5 show that there are very few private wells in the
downtown area of Ogallala and most of these wells are outside of the plume areas. Six wells
(nos 3, 4, 16, 19, 20 and 24) are within the plume areas with none of these wells being used as a
drinking water source. The RI lists well No. 20 as a drinking water source. According to Jim
Brueggerrnan from the Emergency Communication Department for the city of Ogallala, this well
is no used as a dnnkmg water source but is only used as a standby water source in the event of a
faster involving complete failure of the municipal water system, including depletion of stand
pipe water storage^ Attachment 6 is from Mr. Gaiy Gibbons, Nebraska Department of Human
Health and Social Services, who visited Ogallala and conducted a survey of the wells and
determined that only one well (belonging to Mr. Ted Barnhill) is near the plume. A review of the
^ y Sh°WS that Ml"" BamhiH'S wel1 lies significantly south and outside any of the
Feasibility Study - Response 4. As part of the Institutional Controls and Limited Action
remedy selected in the ROD, the information presented to EPA will be verified to determine the
location of all private wells and the uses of these wells, whether all individuals with private wells
™
DnlHn ***? ' Q™*™^™™"* 5 Several of these wells do require decommissioning.
Dnlling of private wells m the future is regulated by city ordinance. Ogallala Municipal code 3-
1 19 through 3-123 pertains to city water utilities and section 3-120 specifically states that "all
persons within 300 feet of a water main shall be required, upon notice by the dty Manager to
hook up wrtfa the city water system." The city requires a permit to install a well and the?e is an
wakens " ' * ^ *" ** tO *°** *" inStaUati°n °f "* ™ *****
25
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Feasibility Study - Response 5. Decommissioning of wells no longer in use is regulated under
Nebraska state law. The EPA will evaluate the existing city ordinance restricting the placement
of ground water wells to determine if this regulation is protective. In addition, ground water
monitoring will be performed to determine all areas and potential areas of contaminated ground
water impact in relation to the areas under the city ordinance jurisdiction.
Feasibility Study - Question/Comment 6. The FS fails to fully and accurately evaluate the
potential effectiveness of institutional controls as part of the remedy. The remedial action
objectives identified in the FS are to prevent the ingestion of contaminated ground water. The
only role that institutional controls serve at this site are to prevent ingestion of contaminated
ground water no matter which alternative is selected. At Ogallala, the role of institutional
controls is limited by the fact that the ground water is not currently being ingested and there is a
legal infrastructure in place to insure that the ground water is not ingested until the ground water
is cleaned up. There are no private wells in the plume areas and no evidence that any private
wells are impacted by the plumes at Ogallala. The fear of a resident drilling a new well into the
plume is also unfounded in that a resident would be required by the city to obtain a permit before
installing the well. There have never been levels of TCE nor PCE detected above MCLs in any
private drinking water well or at the tap. Monitoring of any private well which could be
impacted by the plumes should be implemented.
Feasibility Study - Response 6. Institutional controls will be enforced to restrict the installation
of wells in areas impacted or potentially impacted by ground water contamination. A well
inventory will be conducted to identify all wells in and near Ogallala which are potentially
impacted by these plumes. Ground water samples will be collected and analyzed for the
chemicals of concern. This information will be retained in a data base which will show location
as well as contaminant level. Drinking water wells which are located downgradient to these
plumes will be sampled to determine and verify the quality of the ground water. If the ground
water monitoring data indicates that the plumes are continuing to migrate, additional steps will
be initiated to prevent further migration. The EPA and NDEQ will also determine if additional
private wells are being impacted and should be added to the monitoring program. The purpose
of institutional controls is to restrict the ingestion of any water which exceeds MCLs while
allowing for the natural attenuation processes to reduce the contamination in the plumes.
Feasibility Study - Question/Comment 7. The EPA failed to undertake the necessary
evaluation of the feasibility and effectiveness of institutional controls as a complement to the
limited action alternative. The FS reports mention only three types of institutional controls and
fail to accurately analyze the ones they do identify. The Proposed Plan incorporates different
types of institutional controls which are either not addressed and/or not supported by the FS
without any analysis or support. The FS reports referenced three access restrictions including
deed notice, local ordinance and fencing. Also the FS reports do not reflect or support the
institutional controls included in the Proposed Plan. Table 2-3 for Plume 4 FS states that deed
notices are "not effective since users would already be notified of ground water contamination
26
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when permitting a private well". However, the same table for plume 1 states the opposite- "Deed
notices may be effective in reducing likelihood of contaminated water use".
In the Proposed Plan, EPA states that institutional controls will be required for each alternative
and suggests that deed notifications, after procuring a local ordinance, are the preferred type of
institutional controls. The limited analysis provided for the few institutional controls is wrong.
Feasibility Study - Response 7. The following institutional controls have been selected in the
ROD: for those areas identified as source areas, deed notices which will identify the property as
contaminated will be sought which will restrict the use of the underlying ground water to non-
human uses; the EPA will request that the city pass an ordinance which will restrict the
installation of ground water wells within the city of Ogallala; a survey of wells will be
undertaken to identify the location of all wells within the city of Ogallala and downgradient from
the source areas. The results of this survey will be an inventory of all wells within Ogallala
which will identify the location, the well characteristics (depth, diameter, installation date etc )
use and levels of contaminants present. Wells used for consumption may be monitored to verify
the quality of ground water. The EPA recommends that any private drinking wells exceeding
MCLs be taken out of use as drinking water wells with the property owner being notified and
given the option to receive municipal service, full house treatment or bottled water.
Feasibility Study - Question/Comment 8. The FS and the Proposed Plan state that an
ordinance from the city is required to record deed notices. TRW/ASC has found no legal
authority for this conclusion. Deed notices can be implemented without a city ordinance The FS
states that the city could not pass an ordinance restricting ground water use and the Proposed
Plan rehes on the city ordinance being adopted. Cities have authority to implement and enforce
ordinances for the protection and preservation of health within the city. TRW/ASC believes that
the city of Ogallala would implement and enforce an ordinance which would be effective in
preventing the ingestion of contaminated ground water. The EPA needs to fully evaluate the use
of a variety of governmental controls, such as easements and restrictive covenants which could
be used to complement the limited action alternative.
Feasibility Study - Response 8. The EPA and NDEQ will work closely with the city of
Ogallala regarding the use of city ordinances to restrict the installation of ground water wells and
the use of the ground water for consumption in the locations where contamination is present. The
EPA agrees that effective ordinances can address future installation of private wells The EPA is
concerned about the use of ground water from private wells which this ordinance will not address
(i.e., non-consumption uses, wells outside city jurisdiction). The EPA believes that identifying
all wells within Ogallala and downgradient of the Ogallala plumes and sampling the quality of
ground water will allow for EPA to evaluate the effectiveness of institutional controls in
preventing exposure to the contamination.
Feasibility Study - Question/Comment 9. The FS reports fails to adequately and accurately
evaluate the effectiveness and overall feasibility of the Institutional Controls and Limited Action
27
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remedy. Natural attenuation was not evaluated. Ogallala fits the criteria for a monitored natural
attenuation site as the ground water is not currently being used for drinking and an alternative
water source is readily available, relatively low VOCs and the contaminant plumes are in a state
of equilibrium. The EPA has developed nine criteria to determine if monitored natural
attenuation is appropriate. They are:
1) Whether the contaminant present in soil or ground water can be effectively remediated
by natural attenuation processes: the main contaminants of concern are PCE and TCE and
EPA has identified several sites where anaerobic biotransformation processes actively
remediate these sites and these processes are determined to be more effective in
remediating these sites than the use of pump and treat remedial technologies;
2) Whether the resulting transformation products present a greater risk than the parent
contaminants do: again, PCE and TCE will breakdown to DCE and VC which is further
degraded to ethene and carbon dioxide. While this is occurring, there is no use of the
ground water and, therefore, no exposure;
3) The nature and distribution of sources of contamination and whether these sources
have been or can be adequately controlled. Extensive soil investigations have been
conducted at the site and have not identified any further sources. The EPA recommends
that a removal action will follow for any source identified in the future so they will be
addressed;
4) Whether the plume is relatively stable or is still migrating and has the potential for
environmental conditions to change over time. The EPA has determined that the plume is
stable with no evidence that it is migrating;
5) The impact of existing and proposed active remediation measures upon the monitored
natural attenuation component of the remedy. This is not relevant to the Ogallala site;
6) Whether drinking water supplies, other ground waters, surface waters, ecosystems,
sediments, air or other environmental resources could be adversely impacted as a
consequence of selecting monitored natural attenuation as the remediation option. For
Ogallala, these have been addressed by prior actions;
7) Whether the estimated time frame of remediation is reasonable compared to the time
frames required for other more active methods. Reasonableness should be evaluated on a
site specific basis; ASC/TRW believe that EPA's estimate of 10 years, as presented in the
Proposed Plan, for remediation by pump and treat, is a gross underestimate. The FS's
state that pump and treat could take 16 years or 28 years; none of them support 10 years.
ASC/TRW contend that pump and treat usually takes at least twice as long as estimated.
Also unsupported in any document is EPA's 33+ years for natural attenuation to achieve
MCLs. The FS supports much lower estimates for natural attenuation to achieve MCLs
28
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when the assumption of a continuing source is eliminated. ASC/TRW believe the natural
attenuation time period for cleanup is comparable to a pump and treat remedy. This data
needs to be collected before a remedy is selected for this site;
8) Current and projected demand for the affected aquifer over the time period that the
remedy will remain in effect (including the availability of other water supplies and the
loss of .availability of other ground water resources due to contamination from other
sources). The affected ground water is not being used and an ample supply of potable
water is available for future use during the projected cleanup time using natural
attenuation; and
9) Whether reliable site-specific vehicles for implementing institutional controls (i.e.
zoning ordinances) are available, and if an institution responsible for their monitoring and
enforcement can be identified. The city of Ogallala's municipal code regulating the use
of potable drinking water wells and additional institutional controls which could prove
effective can also be included.
Feasibility Study - Response 9. The EPA is familiar with the nine criteria for natural
attenuation which is elaborated in the above Question/Comment. The EPA clarifies its position
regarding the Ogallala Ground Water Contamination Site: 1) TCE, PCE and CT are the
contaminants of concern at the site and they have been shown to be degraded anaerobically at
other Superfund sites; 2) EPA's 1995 data indicated the presence of cis 1,2-dichloroethene which
is a degradation product of PCE and TCE; 3) the EPA believes that the ground water monitoring
will identify any unknown sources which may need to be addressed; 4) evaluation of the ground
water monitoring data will allow EPA to determine if the plume is stable or is continuing to
migrate; 5) the ASC/TRW active remediation system will not negatively impact the natural
attenuation processes; 6) the EPA will need to assess the status of any ongoing remediation
which is underway in any of the other environmental programs, i.e., LUST or RCRA; 7) the EPA
believes that there may be private wells which could be currently impacted or have the potential
to be impacted by this contamination; 8) the well survey and the subsequent monitoring will
enable EPA to evaluate this criteria; 9) the EPA will evaluate the ground water monitoring
information to determine the actual rate of degradation which the plumes are undergoing using
only natural processes; 10) again, EPA will evaluate the use of the ground water and the
migration of any of the Ogallala plumes; and 11) the EPA will evaluate the effectiveness of all
city codes which are currently in place and will evaluate if they need to be modified to protect
human health and the environment during the estimated remediation time frame.
The EPA and NDEQ listened to the concerns expressed by the community, the potentially
responsible parties and the information presented to EPA during the public comment period. The
EPA has reevaluated its preferred alternative and has selected in the ROD the Institutional
Controls and Limited Action alternative with effective institutional controls for the remedy. This
remedy will allow for the evaluation of the ongoing natural attenuation process to determine if
29
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the rate of reduction is sufficient in controlling the migration of these plumes from their source
areas.
Feasibility Study - Question/Comment 10. The Institutional Controls and Limited Action
alternative is effective in meeting the identified RAO; it adequately satisfies the applicable
evaluation criteria for comparing alternative remedies as presented in the FS reports and includes
elements of natural attenuation including effective institutional controls and performance
monitoring, contingency remedy, five-year reviews and limited source removals. The EPA
recommends that ground water remedies be implemented in phases to increase system
performance and cost effectiveness. Early phase system performance information can be used to
implement the design of the later phases. The Institutional Controls and Limited Action
alternative is consistent with state regulations as a cleanup strategy. The FS reports failed to
even consider numerous alternative remedies which satisfy ARARs and failed to evaluate natural
attenuation with a contingency remedy.
Feasibility Study - Response 10. The EPA has reevaluated the Proposed Plan preferred
alternative and has selected the Institutional Controls and Limited Action alternative in the ROD
as the remedy. The EPA recognizes that the information collected during the ground water
monitoring phase will be evaluated to determine if the selected remedy will be effective in
preventing the exposure to the contaminants of concern as well as to determine if the plumes are
migrating or the rate they are being reduced due to the natural attenuation processes which are
occurring. The ground water sampling information will allow EPA to evaluate the effectiveness
of these processes and to determine if additional actions are needed to mitigate the effects of
these contaminants on the Ogallala aquifer.
Feasibility Study - Question/Comment 11. Since the treatability study is being performed on
reductive dechlorination for the east PCE plume, it should also be performed for the other
plumes.
Feasibility Study - Response 11. The EPA will evaluate the information collected during this
study to determine if it can be applied to the other plumes. If further actions are needed to reduce
unreasonably high levels of contaminants in other Ogallala plumes, then reductive dechlorination
may be applied to such areas if the process is proven to be a viable alternative.
Feasibility Study - Comment 12. The FS reports significantly underestimate the time required
to attain cleanup for the pump and treat remedies and provides conflicting estimates. ASC/TRW
disagree with EPA's 10-year time frame for pump and treat to attain MCLs. ASC/TRW believes
A frfl? timS framC f°r cleanup usinS natural attenuation will be the same as pump and treat
ASC/TRW also believe that the 33+ year time frame for natural attenuation is overestimated and
is not supported by the ground water model.
Feasibility Study - Response 12. The EPA recognizes that it is very difficult to cleanup
aquifers to MCLs using pump and treat technologies. The EPA's modeling efforts indicated that
30
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the sue could be remediated using pump and treat, with no additional source adding
con ammants to the aquifer, within 10 years with limited pumping. The 33+ year time frame for
aauiS TeheUFP°An ""t fimate, WUh H S°UrCe COminUmg t0 release -ntammants to J
b^etLied tfdte5 1 ""^ ^ ^ ** ^^ infoimat'°n to be collecteLd to
leveh If .ot T1^ nX** MtUre ^ rate °f the "*»"* a«enuation processes and the
EPA wmnfT r ^ " ^ ^ migrati°n fr°m P°tential individual source a-as. The
EPA will use this information to determine if additional response actions are needed These
contaminant sources. " ' -—5^u lO reduce
^ ; Q,UeStr/Comment ». The FS reports significantly overestimate the costs
controls and monitoring associated with the Institutional Controls and Limited
Action alternative. Bottled water would not be supplied, residents would be hooked up to
municipal water supply system for 52,000-4,000 per resident. Installation of additional
M ^ °V™li™^ ™"* « -vera. ex.sting monitonng
*
ach M
ground w^ter * * informatlon relative to «» characteristics of the
C FS rep0m may inClude overestimates of the costs. Each
^
plume. For private drinking wells, ground water monitoring will be quarterly for the first vear of
monitonng. If any of the private wells exceed MCLs, the private we?l owne^ w 1 be nodfieLf
0'
e o Water "*>• eding MCLs,
remove^ , T ^"P81 ^^ SUPPly °r be pr°vided a ful1 house ^tment system to
1" ring data from the monitorinS ^ will be
adJ"UStments in the -onitoring frequency and
cm™-
locations ThJ± f 2djUStment C°Uld indude the insta"ation of additional sampling
locations, the removing of monitonng wells from the monitoring well network or no changes
ma underestimated the
wl s w H bee^, T remeuIeS' ^ remedieS *" under-d^igned: More than two recovery
wells will be needed and more than 100 gpm would be extracted; therefore a larger remediation
system would be required and the system would operate for more than 10 years Thl^CE
* «^««^ ^ ^ also incr^hlcS co"
reports estimated the costs °f pump
31
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significantly to the overall remediation effort. The remedies outlined in the FS reports were
designed based upon known site conditions.
Feasibility Study - Question/Comment 15. The FS reports inaccurately conclude that
additional source characterization is necessary. Additional source characterization is not
supported by the FS Reports. Merely assuming the existence of additional sources for the site
without any evaluation to verify or confirm such a conclusion constitutes an abuse of procedure.
Source area characterization of the ASC facility is not required since the evidence concludes that
no sources exist. This information was previously presented to EPA in 1993. The
concentrations of contaminants in the alluvial formation confirm that no sources are contributing
to the ground water from the ASC facility.
Feasibility Study - Response 15. The EPA does not necessarily agree with the commentor that
additional source area characterization of the ASC facility is not required. The EPA will
evaluate the need for additional source investigation based upon the ground water monitoring
information. The EPA believes that there are sufficient ground water monitoring locations
currently installed close to the suspected source areas in Ogallala which can be used to collect
ground water samples and to monitor the levels of contamination present. If additional source
areas are identified based upon EPA review of the ground water information, EPA will require
that additional field work be performed to determine the location of these source areas and may
require additional response actions.
Feasibility Study - Question/Comment 16. How can the remedial alternatives be adequately
and fully evaluated if the source area investigation has not been completed? Any additional study
required must be completed before the remedy is selected at this site. CT was identified near
Railroad and East A and never detected at the ASC facility. If source characterization is needed
for CT, this location should be tested.
Feasibility Study - Response 16. The Institutional Controls and Limited Action alternative,
which includes ground water monitoring and institutional controls, can be implemented without
full and complete knowledge of all source areas. The EPA believes there are sufficient
monitoring wells in Ogallala which can be monitored in order to determine the presence of
source areas. It is anticipated that monitoring of the ground water from monitoring wells and
private wells will allow EPA to determine the extent of each plume, the rate the plume is moving
from the potential source areas and the nature and rate of natural attenuation processes which is
believed to be reducing the levels of contamination in the aquifer. The source area for the CT
plume has not been identified, but the levels of CT in the aquifer are low in comparison to the
other chlorinated solvents. If these levels are found to be increasing, or if it is determined that
natural attenuation will not adequately address the CT contamination in a timely manner,
additional field work will be required.
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Proposed Plan - Questions/Comments
Proposed Plan - Question/Comment 1. The preferred remedy must be supported by the RI/FS.
ASC/TRW believe that EPA's preferred remedy is flawed and should be amended to'select a
limited action alternative as the preferred remedy. The Proposed Plan contains additional and
different errors than the RI/FS and even directly conflicts with the conclusions set forth in the FS
reports. The EPA's preferred remedy is flawed and should be amended to identify a limited
action alternative as the preferred remedy. The RI/FS cannot support a pump and treat remedy at
the Ogallala site. A limited action alternative is supported by the evidence.
Proposed Plan - Response 1. The EPA has selected the Institutional Controls and Limited
Action alternative as the remedy for this site. The information gained from the ground water
monitoring program will allow EPA to determine if additional work is needed at the site. Future
work could include the installation of additional monitoring wells, installation of innovative
treatment technologies or the installation of the pump and treat system. Future work efforts will
be conducted under the Superfund process which encourages input from the community.
Proposed Plan - Question/Comment 2. The ASC remediation system has reduced the levels of
TCE and PCE to near or below MCLs since February 1996. Continued operation of the system
is unnecessary to achieve RAOs and should not be required as part of the selected remedy at the
site. Soil source characterization is not needed at the locations which were evaluated. The
ground water data indicate that the ASC facility is not a current source. If source area
investigations are needed, look for the CT source or additional sources east of the ASC facility.
Proposed Plan - Response 2. The EPA and NDEQ will evaluate the information presented to
them regarding the operation of the ASC system and determine whether the operation of the
system should continue. The EPA did review the most recent data provided and determined that
the system is continuing to remove chlorinated solvents from the aquifer. Not all sampling
points have been reduced to below MCLs. A review of the data also indicates that ground water
exceeding MCLs is currently being extracted by the system. Ground water monitoring data will
be evaluated to determine if additional sources of soil contamination are present in Ogallala.
This evaluation will include the ground water monitoring information near the ASC facility. If
the levels of chlorinated solvents exceed the 150-300 ug/1 level, the EPA would suspect a
potential source area which could be contributing significant amounts of contaminants to the
aquifer and soil source characterization of the facility would be required.
Proposed Plan - Question/Comment 3. The Proposed Plan should identify each source as a
separate operable unit as they have distinct sources and characteristics and therefore will have
separate cleanup times.
Proposed Plan - Response 3. The EPA named the east-PCE plume as a separate operable unit
The EPA will continue to refer to the TCE, PCE and CT as Operable Unit #01 which can be
addressed using the Institutional Controls and Limited Action remedy. If additional work is
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needed to address discreet source areas, EPA will seek performance of any necessary work from
parties deemed responsible under the Superfund law.
Proposed Plan - Question/Comment 4. The Proposed Plan contains numerous discrepancies
and contradictions from the FS reports which must be reconciled and modified before a remedy
is selected. The Proposed Plan misstates the Remedial Action Objective (RAO). The Proposed
Plan states that the RAO is to cleanup the ground water to MCLs. The RAO identified in the
RJ/FS is to prevent the ingestion of the contaminated ground water above the MCLs.
Proposed Plan - Response 4. The RAO for this site has two goals; the first goal is to prevent
the ingestion of the contaminants and the second goal is to restore the aquifer to MCLs.
Proposed Plan -Question/Comment 5. An Alternate Contaminant Level (ACL) would be
appropriate for this site as the ground water will not be used as a drinking water source.
Proposed Plan - Response 5. This aquifer is classified as a ground water source. There are
numerous private and industrial wells located in Ogallala and downgradient from Ogallala which
use the ground water as a drinking water source. An ACL would be appropriate for this site if
the contamination present in the aquifer failed to respond to appropriate remediation efforts.
Proposed Plan - Question/Comment 6. The Proposed Plan wrongly concludes that the limited
action alternative will not attain ARARs. This conclusion is not supported in the FS reports.
The Proposed Plan does qualify the non-attainment of ARARs with the following caveat:
"Alternatives one and two may meet chemical specific ARARs (MCLs) but the time frame
would not be reasonable (33+ years) as long as potential sources have not been evaluated and
remediated." Section 4.2.2.2 in each of the FS reports contradicts that statement by stating "that
compliance with ARARs is expected to be obtained under the limited action alternative for each
area of contamination."
Proposed Plan - Response 6. The EPA recognizes that the Institutional Controls and Limited
Action alternative will meet the ARARs, although the time period for restoration of the aquifer
may be greater using natural attenuation than the time required under a pump and treatment
remedy. The EPA believes that the time required using monitored natural attenuation can be
estimated based upon the quarterly ground water monitoring data. If the time period for aquifer
restoration is found to be unreasonably lengthy, then further response action may be required.
Proposed Plan - Question/Comment 7. The EPA's exaggerated cleanup time for natural
attenuation is based upon the assumption of a continuous source and that the source would not be
remediated. The Proposed Plan does not acknowledge that natural attenuation will reduce
toxicity via natural biological and physiochemical processes. The Proposed Plan incorrectly
states that the FS reports assume the sources are eliminated in evaluating the remedies. This is
directly contrary to the ground water modeling which calculated the cleanup time for natural
attenuation based on an extremely conservative assumption that there was a continuing and large
34
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source. This assumption skews the cleanup time, cost and overall effectiveness of the pump and
treat remedy as compared to natural attenuation.
Proposed Plan - Response 7. The EPA's modeling efforts used a continuous source for the
evaluation of all the alternatives. The EPA did not evaluate natural attenuation as a specific
alternative for this site. The EPA did evaluate the Institutional Controls and Limited Action
remedy, ground water monitoring and institutional controls as an alternative. The EPA has
selected the Institutional Controls and Limited Action alternative as the remedy as it will be
protective of human health and the environment as EPA believes, based upon current
information, that natural attenuation is the appropriate remedy for the site.
Proposed Plan - Question/Comment 8. The Proposed Plan diminishes the cleanup time frame
for the pump and treat alternatives and escalates the cleanup time frame for natural attenuation
without explanation. The Proposed Plan assumes the cleanup time for the selected remedy
would be 10+ years where the FS reports state that it would be 15+ years. The EPA's conclusion
that ground water cleanup under a natural attenuation scenario is 33+ years is without support in
the FS reports. The FS reports provide an estimate of 10 to 30 years for natural attenuation. The
FS reports do not support pump and treat over the limited action alternative based upon time
frame for cleanup. The EPA increases the costs for the limited action alternative and decrease
the cost of the pump and treat alternative in the Proposed Plan without explanation. It is unclear
how the capital costs, annual operation and maintenance costs and the operation and maintenance
present worth costs presented in the Proposed Plan are derived from the costs presented in the FS
reports. The EPA assigns a much lower cost estimate for its preferred remedy in the Proposed
Plan than was assigned in the FS reports.
Proposed Plan - Response 8. The EPA recognizes that there are differences in the information
presented in the FS and that presented in the Proposed Plan. The alternatives evaluated for each
plume need to be added together to determine the overall cost for the remedy. The EPA
recognizes that there are several ground water monitoring locations which are currently installed
in Ogallala and can be used to monitor the contaminant plumes. The EPA will work to reduce
duplicative efforts. The Institutional Controls and Limited Action alternative will allow EPA to
fully evaluate the natural attenuation processes to determine how quickly the aquifer is being
restored. If the rate of aquifer restoration is within a reasonable time frame, then no further
action will be needed. If sources of contamination or zones of ground water with unacceptable
levels of contamination are found to be present, additional work efforts may be needed to
enhance the natural processes for aquifer restoration.
Proposed Plan - Question/Comment 9. There is no cost estimate for the soil source
characterization or source removal even though those efforts were identified as elements of the
selected remedy.
Proposed Plan - Response 9. Appendix B of the FS reports contained a two page cost estimate
and assumptions for soil source characterization. The cost was estimated to be 560,000. The
35
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assumption is that four areas would be investigated with five borings at each area. A report
would be generated for the work. No source removal cost estimates have been made.
Proposed Plan - Question/Comment 10. The west-PCE plume costs need to be included and
would consist of $44,592 in capital costs plus an additional 539,130 for additional capital and
average annual O&M costs of $110,940. For the east-PCE plume the FS costs are $1,057,048
while the Proposed Plan costs are presented as $971,887. The annual O&M costs in the
Proposed Plan are 5131,601 where they were $158,450 in the FS with a present worth of
51,016,223 in the Proposed Plan and 51,921,963 in the FS. For the TCE/CT plume the capital
costs presented in the Proposed Plan were 52,020,702 but were $3,114.099 in the FS. The O&M
present worth costs in the Proposed Plan were $2,043,206 but were $4,615,657 in the FS. For
the preferred remedy, the Proposed Plan indicated that the pump and treat alternative would be
52,992,590 in capital costs; the FS capital costs were $4,215,739. The O&M present worth cost
presented in the FS were $7,406,156 compared to $3,059,429 in the Proposed Plan. In summary,
the Proposed Plan appears to significantly underestimate the cost of the preferred remedy as
compared to the cost estimate presented in the FS reports. CERCLA requires that the remedy be
cost effective and ASC/TRW believes that the limited action alternative would be substantially
more cost effective that EPA preferred alternative.
Proposed Plan - Response 10. The EPA did modify some of the costs which were presented
within the FS reports to those presented in the Proposed Plan. At the time the Proposed Plan was
published, EPA believed that some of the FS's estimates should be modified. Generally, EPA
recognizes that the estimates presented in the Proposed Plan should reflect the information
presented within the FS. The EPA believes that the estimates for the Institutional Controls and
Limited Action alternative are also higher than what EPA anticipates that the actual costs will be,
but evaluated this remedy using the costs as presented in the FS reports.
Proposed Plan - Question/Comment 11. Summary: a limited action remedy should be
implemented, eliminate source characterization and the operation of the ASC remediation
system. A number of issues need to be addressed: an additional round of ground water sampling
on select monitoring wells to evaluate natural attenuation, site conditions should be reevaluated
and accurate plume maps drawn, a correct site risk assessment completed, ground water
modeling flaws corrected, current and future ground water usage, regulation and status as a
drinking water source evaluated, effective institutional controls evaluated, criteria for natural
attenuation evaluated, viable alternatives involving innovative spot removal treatment evaluated,
additional source characterization evaluated before remedy selection, cost estimates revised,
inconsistencies between the FS reports and the proposed plan be rectified and explained and the
use of reductive dechlorination for TCE evaluated.
Proposed Plan - Response 11. The EPA believes that the above-referenced substantive issues
will be addressed during the implementation of the remedy selected in the ROD. Evaluation of
the ongoing operation of the ASC remediation system will take place within the scope of this
ROD.
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Ogallala Electronic Manufacturing Inc. - Questions/Comments.
OEMI-ESC - Question/Comment 1. OEMI-ESC is convinced that the recommended
alternative for the TCE in the alluvial aquifer is founded on ground water modeling effort that
failed to consider important information regarding the fate and transport of TCE in the aquifer.
Review of the modeling effort. Retardation effects on pump and treat are not considered in
modeling efforts. The ground water modeling effort predicts that pump and treat will cleanup the
aquifer in 15 years and natural attenuation is estimated to take more than 33 years. Pump and
treat could last as long as 33 years. If the PCE and TCE retardation factors as presented to EPA
were applied, then pump and treat would last from 22.5 to 88.5 years.
OEMI-ESC - Response 1. Retardation effects were considered in the modeling effort for each
alternative. The EPA believes that during the implementation of the Institutional Controls and
Limited Action remedy more accurate aquifer remediation time frame estimates will be possible
following evaluation of the ground water data obtained
OEMI-ESC Question/Comment 2. The time differential in the Proposed Plan between the
limited action and the pump and treat is significantly overstated and the cost for the pump and
treat is understated.
OEMI-ESC Response 2. The ground water monitoring data to be obtained during
implementation of the remedial action selected in the ROD will enable EPA to evaluate the
effectiveness and time required by natural attenuation processes which are believed to be present
at the site. Based on the ground water data, EPA will perform an evaluation of the aquifer and
determine the plume degradation rates, the flow path and extent of migration of each plume.
This information will allow EPA to determine the effectiveness of the Institutional Controls and
Limited Action remedy in addressing the ground water contamination.
OEMI-ESC - Question/Comment 3. OEMI is not a significant source of TCE. Ground water
modeling effort was based upon the assumption that 825 kg/year of TCE and 3,100 kg/year of
PCE were released from the OEMI facility. OEMI never used PCE and there are sources of TCE
upgradient from their facility. Other sources of TCE not investigated to date: 20 leaking
underground storage tank sites within one mile of the OEMI facility. There are several facilities
which could have released solvents and two which may have used chlorinated solvents, one a
closed dry cleaner 0.25 miles east of the OEMI facility and a closed TRW facility 0 25 miles
north east of the OEMI facility.
OEMI-ESC - Response 3. The EPA believes that there is a significant source of TCE present
near the OEMI facility as indicated by the presence of TCE in monitoring well MW-7B and by
information presented to EPA by OEMI during the public comment period. If the levels of TCE
remain high, that is above 150-300 ug/1, EPA believes that a source area for TCE would be at
37
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OEMI or a facility upgradient to MW-7B. The EPA has investigated a number of potential
source areas and will continue to look for source areas as part of the selected remedy.
OEMI-ESC - Question/Comment 4. Schmidt Motors property (location of MW-7B) was used
for commercial operations for at least 50 years. The former ASC facility, 0.64 miles upgradient
of OEMI has stated that it released 32,180 pounds of TCE.
OEMI-ESC - Response 4. The former ASC facility has an ongoing remediation system in place
to address the contamination present at its site. As the ground water data indicates, the
concentrations of TCE upgradient of the OEMI facility is approximately 50 ug/1. The level of
TCE present in MW-7B is in excess of 1000 ug/1. This fact leads EPA to believe that a second
source of TCE exists at or near the OEMI facility.
OEMI-ESC - Question/Comment 5. It is not cost effective to remedy ground water without
identifying the source and removing it.
OEMI-ESC - Response 5. The EPA agrees that if a source or zone of ground water with
elevated levels of contamination is identified, it would be best to remove it in order to effectively
remediate the contamination within the aquifer. For those areas where the contamination has
spread, the Institutional Controls and Limited Action remedy will be effective in remediating the
aquifer.
OEMI-ESC - Question/Comment 6. OEMI-ESC believe that limited action alternative, with
monitoring, is as protective as EPA's pump and treat remedy.
OEMI-ESC - Response 6. The EPA agrees that the Institutional Controls and Limited Action
alternative can be as protective as pump and treat at this site. The EPA will ensure
protectiveness of the remedy by the identification of all wells located within Ogallala and
downgradient to the source areas. The EPA also believes that an evaluation of the ground water
monitoring data will enable EPA to determine the rate of degradation, the extent of migration of
the plumes and the overall impacts of the contamination in the aquifer.
38
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