PB98-964308
EPA 541-R98-171
March 1999
EPA Superfund
Record of Decision:
Bruno Co-Op Association/
Associated Properties
Bruno, NE
9/30/1998
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RECORD OF DECISION
Bruno Cooperative Association/Associated Properties Site
Bruno, Nebraska
U.S. Environmental Protection Agency
Region VII
Kansas City, Kansas
September, 1998
Bruno Co-op Site ' Record of Decision
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RECORD OF DECISION
Bruno Cooperative Association/Associated Properties Site
Bruno, Nebraska
U.S. Environmental Protection Agency
Region VII
Kansas City, Kansas
September, 1998
Biuno Co-op Site Record of Decision
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Contents
I. Declaration 2
I). Decision Summary 5
1.0 Site Name, Location, and Description 5
2.0 Site History and Enforcement Activities 5
3.0 Community Participation 6
4.0 Site Characteristics 7
4.1 Soil Contamination 8
4.2 Groundwater Contamination 8
5.0 Current and Potential Future Site and Resource Uses 9
6.0 Summary of Site Risks 9
6.1 Human Health Risk Assessment 10
• 6.2 Ecological Risk Assessment 11
7.0 Remediation Objectives 12
8.0 Description of Alternatives 13
8.1 Alternative 1: No Action 14
8.2 Alternative 2: Containment/Air Stripping with Tray Aeration .... 14
8.3 Alternative 3: Active Restoration/Air Stripping with Tray Aeration 17
8.4 Alternative 4: Active Restoration/ln-situ Vapor Extraction 19
9.0 Comparative Analysis of Alternatives 20
9.1 Overall Protection of Human Health and the Environment 20
9.2 Compliance with Applicable or Relevant and Appropriate Requirements
(ARARs) 21
9.3 Long-Term Effectiveness and Permanence 21
9.4 Reduction of Toxicity, Mobility, and Volume Through Treatment . . 22
9.5 Short-Term Effectiveness 23
9.6 Implementability 23
9.7 Cost 24
9.8 State Acceptance 24
9.9 Community Acceptance 24
10.0 Selected Remedy 25
10.1 Description of Selected Remedy 25
10.2 Summary of Estimated Costs 27
10.3 Cleanup Levels 27
10.4 Expected Outcomes of the Selected Remedy 27
11.0 Statutory Determinations 28
11.1 Protection of Human Health and the Environment 28
11.2 Compliance with ARARs 28
11.3 Cost Effectiveness 32
Bnjao Co-op Site , Record of Decision
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Contents (continued)
11.4 Utilization of Permanent Solutions and Innovative Treatment
Technologies to the Maximum Extent Practicable 32
11.5 Preference for Treatment which Reduces Toxicity, Mobility,
or Volume 32
12.0 Documentation of Significant Changes . 32
III. Responsiveness Summary 34
Figure 1 Site Location
Figure 2 Site Map
Figure 3 Sampling Locations
Figure 4 Soil Sample Results: Carbon Tetrachloride
Figure 5 Areal Extent of Carbon Tetrachloride in the Upper Sand Unit
Figure 6 Areal Extent of Carbon Tetrachloride in the Middle Sand Unit
Figure 7 Areal Extent of Carbon Tetrachloride in the Lower Sand Unit
Figure 8 Areal Extent of Chloroform in the Upper Sand Unit
Figure 9 Areal Extent of Chloroform in the Middle Sand Unit
Figure 10 Areal Extent of Chloroform in the Lower Sand Unit
Figure 11 Areal Extent of CT, CF, or 1,2-DCA Above Remediation Goals
Table 1 Present Worth Cost Analysis: Selected Alternative
Table 2 Cost for Well Abandonment of Well 36-1 and Treatment of Well 65-1
Bruno Co-op Site
Record of Decision
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Abbreviations and Acronyms
1,2-DCA
ARARs
Argonne
AWQC
bgs
BVSPC
CCC/USDA
cfs
COC
CERCLA
CF
CFR
CT
E&E/FIT
EPA
ESC
fll- Sfifl-
FS
GAC
gpm
MCL
MSL
MW
N/A
NCP
NDEQ
NDOH
NESHAPS
NRD
ng/L
NPL
NPDES
O&M
OSHA
OSWER
PA
POTW
1,2-dichloroethane
Applicable or Relevant and Appropriate Requirements
Argonne National Laboratory
Ambient Water Quality Criteria
below ground surface
Black & Veatch Special Projects Corporation, an EPA contractor
Commodity Credit Corporation/United States Department of
Agriculture
cubic feet per second
Chemical of Concern
Comprehensive Environmental Response, Compensation, and
Liability Act
chloroform
Code of Federal Regulations
carbon tetrachloride
Ecology and Environment/Field Investigation Team
United States Environmental Protection Agency
Expedited Site Characterization
(et sequential and succeeding sections
Feasibility Study
granular activated carbon
gallons per minute
Maximum Contaminant Level
mean sea level
Monitoring well
not available, or not applicable
National Oil and Hazardous Substances Pollution Contingency Plan
Nebraska Department of Environmental Quality
Nebraska Department of Health
National Emission Standards for Hazardous Air Pollutants
Natural Resources District
nanograms per liter
National Priorities List
National Pollution Discharge Elimination System
Operation and Maintenance
Occupational Safety and Health Act
Office of Solid Waste and Emergency Response
Preliminary Assessment
Publicly Owned Treatment Works
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ppb
PRP
PWS
RAO
RCRA
Rl
ROD
SARA
SDWA
SI
use
USDA
USEPA
VOCs
parts per billion
Potentially Responsible Party
Public Water Supply
Remedial Action Objective
Resource Conservation and Recovery Act
Remedial Investigation
Record of Decision
Superfund Amendments and Reauthorization Act
Safe Drinking Water Act
Site Investigation
micrograms per kilogram
micrograms per liter
United States Code
United States Department of Agriculture
United States Environmental Protection Agency
Volatile Organic Compounds
Bruno Co-op Site
Record of Decision
IV
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I. DECLARATION
Bruno Co-op She Record of Decision
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Declaration for the Record of Decision
Bruno Cooperative Association/
Associated Properties Site
Bruno, Nebraska
Site Name and Location
The Bruno Cooperative Association/Associated Properties Site ("Bruno Co-op
Site"), CERCLIS identification number NED981713829, is located in Bruno,
Nebraska. Bruno is an agricultural community in the northeast section of Butler
County, about 60 miles west of Omaha, Nebraska.
Statement of Basis and Purpose
This decision document presents the selected remedial action for the Bruno
Co-op Site, in Bruno, Nebraska, which was chosen in accordance with the
Comprehensive Environmental Response, Compensation and Liability Act of 198O
(CERCLA), as amended by the Superf und Amendments and Reauthorization Act of
1986 (SARA) and other amendments, and, to the extent practicable, the remedy
also follows the National Oil and Hazardous Substances Pollution Contingency Plan
(NCP). This decision is based on the administrative record for this site.
Assessment of the Site
Actual or threatened releases of hazardous substances from this site, if not
addressed by implementing the response action selected in this Record of Decision
(ROD), may present an imminent and substantial endangerment to public health,
welfare, or the environment.
Description of Selected Remedy
This ROD addresses groundwater and soil. The principal threat at this site is
volatile organic compounds (VOCs) in the groundwater at the site. The specific
VOCs which have been identified as contaminants of concern (COCs) are carbon
tetrachloride. 1,2-dichloroethane, chloroform (abbreviated CT, 1,2-DCA, and CF
respectively) in this document. The presence of these contaminants in the
groundwater at the site presents a threat to an adult or child resident of Bruno
consuming water from the affected aquifer.
Bruno Co-op Silt Record of Occam
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The major components of the selected remedy include the following:
• Active restoration of the aquifer by pumping out and treating the
contaminated groundwater.
• Groundwater monitoring and a periodic analysis of the results.
• Treatment of contaminated groundwater by air stripping using tray aeration
techniques.
• Discharge of treated groundwater to the nearby tributary of Skull Creek. At
the option of state and local authorities, some of the water may be
beneficially reused rather than discharged.
Statutory Determinations
The selected remedy is protective of human health and the environment,
complies with federal and state requirements that are legally applicable or relevant
and appropriate to the remedial action, is cost-effective, and utilizes permanent
solutions and alternative treatment (or resource recovery) technologies to the
maximum extent practicable. This remedy also satisfies the statutory preference
for remedies that employ treatment as a principal element (i.e., reduce toxicity,
mobility, or volume of contaminants through treatment). Because hazardous
substances above health-based levels are expected to still be on site in 5 years, a
review will be conducted within 5 years after commencement of remedial action to
ensure that the remedy continues to provide adequate protection of human health
and the environment.
Dennis Grams, P.E. CJ Date
Regional Administrator
United States Environmental Protection Agency
Region VII
Bruno Co-op Site Record of Decision
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II. DECISION SUMMARY
Bruno Co-op Sit* . taeort «* Decuwi
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Decision Summary
1.0 Site Name, Location, and Description
This Record of Decision (ROD) was developed by the U.S. Environmental
Protection Agency (EPA), as lead agency, with support from the Nebraska
Department of Environmental Quality (NDEQ).
The Bruno Cooperative Association/Associated Properties Site ("Bruno Co-op
Site"), CERCLIS identification number NED981713829, is located in Bruno,
Nebraska. Bruno is an agricultural community in the northeast section of Butler
County, about 60 miles west of Omaha, Nebraska, as shown on Figure 1. The
population of the community is approximately 150. The village is largely residential
except for the Bruno Co-op (a farmers' grain cooperative), a post office, a school, a
community center, a sanitary sewer treatment facility, and a variety of small stores.
The Bruno Co-op site is a former U.S. Department of Agriculture grain storage
site where carbon tetrachloride
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VOCs, but the source of contamination was undocumented. The report suggested
that the most likely source of contamination was the former Commodity Credit
Corporation/United States Department of Agriculture (CCC/USOA) grain storage site
(now owned by the Co-op) and other local grain storage facilities where CT may
have been used as a grain fumigant. Additional sampling by the EPA in February
1988 confirmed the presence of VOC contamination of the groundwater. The VOC
analysis detected 38 ^g/l of CT, 4.6 ^g/I of CF and 16 /ig/l of 1,2-DCA in Well
36-1; and 13 ng/\ of CT, 93 M9/I of CF, and 5,3 M9/I of 1,2-DCA in Well 65-1.
In May 1988, E&E/FIT carried out a potentially responsible party (PRP) search
for the area now occupied by the Bruno Co-op. After evaluating the evidence
presented in this report, EPA sent out notice letters identifying CCC/USOA and the
Chicago and Northwestern Railway as PRPs. CCC, the Commodity Credit
Corporation, is part of the federal government, an agency of the U.S. Department
of Agriculture. (The same parties were again notified of their potential liability in
1993.)
In October and December 1988, E&E/FIT performed a site investigation (SI),
submitting a final report to the EPA on May 8, 1989. As its primary task, E&E/FIT
was directed by the EPA to conduct a soil gas survey to define the approximate
geographic extent of the subsurface plume associated with the CT identified in the
two PWS wells. E&E/FIT collected 27 soil gas samples to create a map of the CT
plume and identify the source or sources of the VOCs found in the PWS wells. The
survey failed to identify a contaminant plume, but two isolated soil gas samples
collected on the Bruno Co-op property had CT levels of 144 and 370 nanograms
per liter (ng/L). The remaining samples were less than the soil gas confidence limit
(40 ng/L).
In May 1989, the EPA began to supply bottled water to the 150 residents of
Bruno as a temporary measure until an alternate water supply could be provided.
The PWS wells (Wells 36-1 and 65-1) were disconnected, and two replacement
PWS wells (Wells 90-1 and 90-2) were completed about 1 mile west of the village
and connected to the village's water system in October 1990.
In June 1996, the Bruno Co-op site was placed on the EPA National Priorities
List (NPL).
3.0 Community Participation
The Human Health Baseline Risk Assessment prepared by the Nebraska
Department of Health, the Phase II Expedited Site Characterization report prepared
by USDA. EPA's July 1998 Finel Feasibility Study (FS), USDA's April 1998 report
on its contractor's groundwater modeling efforts (Argonne Final Report, April
1998), and other site-related documents, were made available to the public for a
public comment period which began on July 16, 1998, and which concluded on
August 22, 1998. EPA's Proposed Plan for the Site was made available at a public
meeting on July 23, 1998. The Proposed Plan was placed, along with the other
site documents discussed above, in a local repository at the Bruno Post Office.
Bruno Co-op Site fi Retort of Decision
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Notice of the availability of these documents and the time and location of the public
meeting was published in a local newspaper, the David City, NE Banner-Press. A
fact sheet summarizing the Proposed Plan and EPA's preferred alternative was
mailed to residents and local and state elected officials and federal elected
representatives.
As noted above, a public meeting was held during the public comment period at
Bruno Village Hall, Bruno, Nebraska, on July 23, 1998. EPA presented the results
of the site studies, to highlight the reasons why it was recommending its preferred
remedial alternative, and listened to questions and comments from the public.
Comments received at the public meeting, as well as written comments
submitted during the comment period, are addressed in the Responsiveness
Summary Section of this ROD.
4.0 Site Characteristic*
The equivalent of EPA's required Remedial Investigation (Rl) was conducted to
determine the nature and extent of contamination at the site and potential fate and
transport scenarios. In 1994-1995, Argonne National Laboratory (Argonne) of
Argonne, Illinois, performed two phases of Rl-like work for the USDA, an identified
PRP. USDA's Phase I "Expedited Site Characterization" (ESC) investigation was
completed and reported in November 1994. The USDA Phase II ESC investigation,
which EPA considered the equivalent of its required Remedial Investigation to
gather the data needed to decide on a remedy for this site, was completed and
reported in 1995. The investigations included monitoring well installation,
subsurface soil sampling and analysis, surface water sampling and analysis,
groundwater sampling and analysis, and characterization of the site physical
properties. Continued monitoring of the site by Argonne was conducted to
establish a database which would later be used to produce a hydrogeologic model
of the site. The fate and transport of contamination at the site was avaluated using
groundwater and contaminant transport hydrogeologic computer models. Further
results of its modeling efforts were reported by Argonne in April 1998.
Efforts to characterize tha nature and extent of soil and groundwater
contamination at the Bruno site were performed by Argonne during field programs
conducted since April 1994. Tha results of the site characterization investigations
were presented in Argonne's reports. Figure 3 is a map of all sampling locations,
as well as tha locations of temporary wells, public wells, municipal test wells, and
domestic walls.
The investigation efforts ware focused on CT and CF, both of which were
identified in both soil and groundwater. Investigation efforts to determine the
extent of 1,2-DCA contamination were not performed, but 1,2-DCA behaves
similarly in the environment to CT and CF.
Bruno Co-op Site Record of Decision
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4.1 Soil Contamination
Soil contamination was found in the vadose zone (the soil zone above the water
table) at the site. The highest concentration of CT, 2.700 micrograms per kilogram
(2,700 Mg/kfl, or ppb) occurred in the surface soil sample taken in the immediate
vicinity of the location where grain storage bins once existed on the former site. No
CF contamination was detected in the surface soils at these locations. CF was
detected in one surface soil sample taken from soil boring SB15, just to the north
of the former grain storage bins. Figure 4 illustrates results of the CT soil sampling
investigations. CT and CF contamination was also detected in subsurface soil
samples collected in the vicinity of the former CCC/USDA grain storage bins, which
were removed in the 1960's. Soil contamination was detected on the site in
samples taken from soil borings SB 16 and SB20 from depths of approximately 7
feet below ground surface (bgs) to approximately 40 feet bgs. At the sampled
locations, CT concentrations ranged from 8 to 87 Mg/kg. Maximum values were 87
^g/kg at a depth of approximately 29 feet bgs in soil boring SB20 and 30 ^g/kg at
a depth of 23 feet bgs in soil boring SB16. Detected CF concentrations ranged
from 6 to 110 Mg/kg in subsurface soil samples taken at SB16. No CF was
detected at SB20. In subsurface soil samples collected at SB 15 (north of the
location of the former grain storage bins), only CF was detected in minor
concentrations (approximately 5 Atg/kg). CT was also detected (approximately 4
^g/kg) in a single soil sample taken from an approximate depth of 23 feet bgs at
SB19, located to the southwest of the former CCC/USOA site.
4.2 Groundwater Contamination
Bruno lies over a shallow Pleistocene aquifer. The shallow aquifer consists of
four distinct stratigraphic units. The uppermost layer is a clay silt layer which is
approximately 40 feet thick. This layer is believed to be a windblown loess
deposit. Underlying the loess is the upper sand unit which ranges in thickness from
5 to 25 feet. Underlying the upper sand unit is a complex sequence of fine silt with
stringers of clay and fine grained sand. This sequence was termed the middle silty
unit and it ranges in thickness from 10 to 35 feet. Underlying the middle silty unit
is the lower sand unit which is approximately 20 to 30 feet thick. Underlying the
lower sand unit is a clay unit approximately 10 feet thick. Underlying this clay unit
is a Cretaceous shale bedrock unit. The clay and the Cretaceous shale are an
aquiclude which hydraulically isolates the surficial aquifer from any underlying
water bearing units.
Groundwater elevations in wells indicate the regional direction of groundwater
flow is primarily north. The depth to the groundwater piezometric surface is
approximately 15 to 20 faet bgs at the site. Recharge to the aquifer is believed to
be primarily through infiltration of precipitation and has been estimated to range
from 2 inches to 5 inches per year.
Bruno Co-op Site _ Record of Deeijion
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The surface water stream which runs from southwest to northeast along the
north side of the site is believed to only impact groundwater during periods of high
rainfall. The base of the stream is above the elevation of the water table; therefore,
the stream is not a point of discharge for the aquifer.
Bruno's first PWS well was completed in the shallow aquifer in 1936 on a site
now occupied by the Bruno Co-op and was identified as Well 36-1. A second well,
Well 65-1, was installed in 1965 near the center of the village, at the intersection
of Pine and Third Streets, These wells were taken off-line in 1990 because of the
contamination discussed in Section 2.0. Two new wells were drilled to the west of
the village and put on-line in 1990. These wells are identified as Wells 90-1 and
90-2.
A groundwater contaminant plume is present in the aquifer in the vicinity of the
former CCC/USDA grain storage site at Bruno. The contaminated aquifer has been
broadly divided into three layers: the upper sandy layer, the middle silty layer, and
the lower sandy layer. The contamination is migrating both vertically and laterally
across all three aquifer layers. The highest concentrations of CT (1,300 ^g/U were
found in the middle layer of the aquifer directly beneath the former CCC/USDA
site. CF concentrations were generally much lower, ranging from below the
detection limit (5 ^g/L) to 63 ,ug/L Figures 5 through 10 show the area! extent of
the CT and CF plumes in the upper, middle, and lower portions of the aquifer at
Bruno.
5.0 Current and Potential Future Site and Resource Uses
The site is currently an active farmers' grain cooperative surrounded by
residential and agricultural areas. There are no restrictions at present on the future
use of the site.
The aquifer below the site is used as a potable water resource for the town and
individual farmsteads. Public water supply wells have been contaminated and have
been taken out of service because of the contamination. The community has
expressed a strong interest in being able to return at least one of their former wells
to service in the near future.
6.0 Summary of Site Risks
The baseline risk assessment estimates what risks the site poses if no action
were taken. It provides the basis for taking action and identifies the contaminants
and exposure pathways that need to be addressed by the remedial action. This
section of the ROD summarizes the results of the baseline risk assessment for this
site.
Bnino Co-op Site n Record of Decision
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6.1 Human Health Risk Assessment
A human health baseline risk assessment for the site was prepared by the
NDOH.
The risk* assessment is an analysis of the potential adverse health effects that
may result from human exposure to chemical contaminants present at the site.
Exposure to contaminated groundwater from ingestion, dermal contact while
bathing, and inhalation of chemicals that volatilize while bathing were evaluated.
Several potential pathways of exposure to contaminated soil were also evaluated.
To ensure protection of human health, the risk assessment assumes that no
action has been taken at the site to remove the contamination, and the highest
exposure that may reasonably be expected to occur at the site is evaluated.
For example, in the Bruno risk assessment it was assumed that a future Bruno
resident drills a new well within the area of the groundwater contamination and is
concurrently exposed to contaminated soil. The individual is assumed to be
drinking and bathing with contaminated groundwater and working or playing in
contaminated soil on a daily basis.
The COCs at the Bruno site include CT and CF. Both of these chemicals may
pose adverse health effects end both ere considered to be probable human
carcinogens. To evaluate the potential for adverse health effects, excluding cancer,
a hazard index is used. The evaluation of non-carcinogenic risks for future adult
and child through the groundwater exposure pathway resulted in hazard indices of
36.5 and 85.2 respectively. A hazard index calculated for a site in excess of 1.0
indicates that potential adverse health effects may occur from exposure to the site
contaminants. In Bruno, hazard indices exceeded 1.0 for future adult and child
residents, who were assumed to drink and bathe in the groundwater contaminated
with CT and CF. In other words, there is a potential for adverse health effects to
occur if the contaminated water is ingested, comes in contact with the skin, or if
the volatilized chemicals are inhaled while bathing.
With one exception, no adverse health effects were determined, in NOOH's
baseline risk assessment, for exposure to contaminated soil. The one exception
was that for a future child resident exposed to CT in the soil at the location of
highest soil contamination, adverse health effects may occur from exposure to
chemicals evaporating from the soil. This calculation assumes the child is playing
and digging in the soil at this location on e daily basis, and it also assumes that the
highest level in soils, 2,700 A/g/kg, is spread uniformly over an area 45 meters on
one side. However, nearby samples as close as 25 feet away showed non-detect
values, as was pointed out by a comment made during the public comment period,
causing EPA to reevaluate this calculation.
Although EPA initially believed there could be adverse health effects for a
hypothetical future cMd resident from levels observed in soil on-site at or near the
former bin storage location, any potential health hazard to workers at the site from
soil exposure to CT, CF, and 1,2-DCA was calculated to be at an acceptable level.
Bmno Co-op Site - _ Record of Decision
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The cancer risk associated with exposure to a chemical is evaluated differently
than the risk from exposure to noncarcinogens. The cancer risk is presented as the
probability that an individual exposed to a carcinogen will develop cancer in his/her
lifetime (70 years). The cancer risk associated with exposure to chemical
contamination, presented in the Bruno risk assessment, is the excess cancer risk or
risk in excess of the national background cancer risk in the United States of roughly
1 in 3. In Bruno, the highest excess cancer risk associated with the site was
calculated for a future adult resident ingesting CT in groundwater. An excess
cancer risk of 1.4 in 1,000 was calculated this future adutt resident. In other
words, a future Bruno resident assumed to consume contaminated groundwater has
a background probability of developing cancer in his/her lifetime of about 1 in 3
plus an additional risk 1.4 in 1,000. Cancer risks associated with dermal contact
and inhalation of volatilized chemicals are also added to this risk but were estimated
to be 1 to 2 magnitudes lower than the risk from ingestion.
Based on the information discussed above, EPA finds that actual or threatened
releases of hazardous substances from this site, if not addressed by implementing a
response action such as the one selected in this ROD, may present an imminent
and substantial endangerment to public health, welfare, or the environment.
The above summary presents an overview of the Bruno risk assessment report
prepared by the NOOH in 1995. The full September 1995 risk assessment report
may be consulted in the Administrative Record File for a more detailed evaluation of
the site risks.
6.2 Ecological Risk Assessment
A four-step process was utilized for assessing site-related ecological risks for a
reasonable maximum exposure scenario:
1) Problem Formulation- a qualitative evaluation of contaminant release,
migration, and fate; identification of COCs, receptors, exposure pathways, and
known ecological effects of the contaminants; and selection of endpoints for
further study. 2) Exposure Assessment- a quantitative evaluation of contaminant
release, migration, and fate; characterization of exposure pathways and receptors;
and measurement or estimation of exposure point concentrations. 3) Ecological
Effects Assessment- literature reviews, field studies, and toxicity tests, linking
contaminant concentrations to effects on ecological receptors. 4) Risk Character-
ization- measurement or estimation of both current and future adverse effects.
The ecological risk assessment was conducted by NDOH and showed no
danger to sensitive animal populations, vegetation near streams, ponds, or rivers
since contaminant levels appear to be below established ecological benchmark
values for surface water and sediment. Currently, there are no generally accepted
values available for soil.
Bruno Co-op Site Record of Decision
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7.0 Remediation Objectives
The unacceptable risks at the Bruno site are attributable to ingestion, inhalation,
and dermal contact with contaminants of concern in groundwater. Risks associated
with inhalation and direct contact with soils in potential source areas were
determined by EPA to be below levels of concern. As discussed in Section 6.1
above, one calculation that led to EPA finding an unacceptable risk from soil to a
possible future child resident on-site was recalculated based on a comment received
during the public comment period, and corrected.
Remedial Action Objectives (RAO) provide a general description of how the
unacceptable risks at the site will be addressed. The RAO for the Bruno Co-op site
is to prevent human exposure to contaminated groundwater. This will be
accomplished at the Bruno site by restoring the groundwater to drinking water
quality in the contaminated area (Figure 11) so that future generations of residents
may use the aquifer. This objective is based on available information and relies the
baseline risk assessment and on standards such as applicable or relevant and
appropriate requirements (ARARs) of other environmental laws.
The following final cleanup levels were established for the Bruno site
contaminants of concern for restoring groundwater to drinking water quality. Each
of the cleanup levels are based on the drinking water maximum contaminant levels
(MCLs) for these contaminants.
CT - 5 x/g/L (MCL)
CF — 100 fjgIL (MCL for total trihalomethanes)
1,2-DCA - 5//g/UMCU
RAOs were not developed to address soil contamination at the site because it
was ultimately determined, based on additional information received after the
preparation of the Proposed Plan, that soil contamination did not pose an
unacceptable risk through inhalation, ingestion, and dermal contact and, in addition,
that the soil did not represent a significant continuing source of contaminants of
concern to site groundwater. Therefore, no additional active measures to address
soil contamination are expected to be needed to protect human health and the
environment.
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8.0 Description of Alternatives
CERCLA requires that the selected site alternative be protective of human
health and the environment, be cost effective, comply with other environmental
laws, and utilize permanent solutions, alternative treatment technologies, and
resource recovery alternatives to the maximum extent practicable. In addition, the
statute includes a preference for the use of treatment as a principal element for the
reduction of toxicity, mobility, or volume of the hazardous substances.
EPA's July 1998 Feasibility Study (FS) Report evaluated remedial alternatives
(including the no action alternative, which EPA is required to consider by law) for
addressing the contamination associated with the ground water plume at the site.
The Feasibility Study considered four alternatives in detail: 1) no action (required to
be considered under the NCP); 2) pumping and treating the groundwater to contain
the plume; 3} pumping and treating the groundwater more aggressively in order to
achieve the cleanup standards throughout the aquifer in a reasonable time; and 4)
an innovative approach, in-situ vapor extraction.
The goals of the remedial action for the Bruno site are to prevent exposure by
ingestion, inhalation, or direct contact to the contaminants of concern (CT, CF, and
1,2-DCA) found in the site's groundwater. As part of the process of choosing a
remedy, the above remedial alternatives from the FS are compared and evaluated
using nine criteria that appear in the NCP. (These are discussed in Section 9
below.)
For the purpose of analyzing and comparing the remedial alternatives, EPA
assigned specific costs to the alternatives by making certain assumptions to allow
costs to be estimated, such as estimating the relative gallonage of water to be
pumped out of the ground in Alternatives 2 and 3 (containment pump-and-treat and
pump-and-treat to clean the aquifer to MCLs), for example. EPA Superfund policy
is to try to assign costs with " + 50/-30" accuracy. The accuracy is only
approximate. The estimates are acceptable if the costs estimated are in a range as
much as 50% greater or 30% less than the estimates.
In the discussion below, numerical features (such as gallons per minute, number
of wells estimated to be required, or dollar estimates) are highlighted, but what is
really being compared are the four broad remedial alternatives focused on in the FS,
which are no action, containment pump-and-treat to prevent the plume from
spreading or migrating, aggressive pump-and-treat to clean up the aquifer more
quickly, and in-situ vapor extraction, an innovative technique for cleaning the
groundwater without having to pump it out of the ground.
The analysis of remedial alternatives within the FS report, and the conceptual
design cost estimates, were assembled by Black & Veatch Special Projects
Corporation (BVSPC, the EPA contractor that prepared EPA's July 1998 Feasibility
Study Report).
Bruno Co-op Site Record of Decision
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The present worth of each alternative, a summary measure of cost that, for
comparison purposes, turns a stream of payments or costs over a future period of
years into the equivalent of single lump sum in the present, was calculated by
BVSPC for'all alternatives assuming a 5 percent discount rate for up to 30 years.
The cost estimates, as discussed above, are conceptual, with an estimated + 50
percent to-30 percent level of accuracy. The alternatives from the FS report are
described below, in the remainder of Section 8. Section 9 compares the
alternatives. Section 10 discusses the selected alternative, which is Alternative 3.
cleanup of the aquifer to MCLs. Section 10 also discusses several additional
measures that will be taken as part of the selected remedy, including measures
added in response to comments which were received during the public comment
period.
8.1 Alternative 1: No Action
Capital Cost: $0.
Present Worth of Annual O&M Cost: $0.
Total Present Worth Cost: $41,700.
Construction time: 0.
Cleanup time: Indefinite, unknown.
Pump rate: N/A.
Groundwater treatment technology: N/A.
Disposal: N/A.
Alternative 1 would not involve any remedial actions, and the site would remain
in its present condition. This alternative, required by the NCP and CERCLA, is a
baseline alternative against which the effectiveness of the other alternatives can be
compared. Under the no action alternative, the site is left "as is" and no funds
would be expended for monitoring, control, or cleanup of the contaminated
groundwater. However, a 5-year review of the site would be required under
CERCLA, and so the computed "total present worth" cost was estimated to include
funds that would be expended to conduct the review.
8.2 Alternative 2: Containment/Air Stripping with Tray Aeration
Capital Cost: $215,000.
Present Worth of Annual O&M Costs: $647,400.
Total Present Worth Cost: $862,400.
Construction time: 1-2 years.
Estimated cleanup time: +100 years.
Pump rate: 40 gallons per minute total.
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o Estimated number of extraction wells: 4.
• Grdundwater treatment technology: Tray aeration.
• Disposal: Discharge to tributary of Skull Creek.
Alternative 2 would entail the extraction of contaminated groundwater through
extraction wells to establish a hydraulic barrier and prevent migration of the
contaminated plume. The hydraulic barrier would be created by placing the
extraction wells at locations and pumping them at rates sufficient to modify the
groundwater flow gradient, preventing further contaminant migration. Although
contaminated groundwater would be removed, the well locations and pumping rates
would not be adequate for active restoration of the plume. The groundwater would
be treated by air stripping with tray aeration to meet discharge standards and
discharged to a tributary of Skull Creek.
The proposed location, pumping rate, depth and size for the extraction wells
were determined using groundwater modeling conducted by Black & Veatch. The'
wells would be located so that the radii of influence overlap the extent of the
contaminant plume. The groundwater modeling conducted during the FS suggested
that two well nests consisting of two wells each could create the required hydraulic
barrier, each well nest consisting of one well screened in the upper sand aquifer
zone at an approximate depth of 50 feet and a second screened in the lower sand
aquifer zone at an approximate depth of 105 feet. The wells would pump at
approximately 10 gallons per minute (gpm) each for a total of 40 gpm. The actual
location, pumping rate, depth and size of the extraction wells needed for
containment of the plume of contaminated groundwater would need to be
determined during the remedial design.
It was assumed that the groundwater would be pumped to an on-site treatment
system through double contained underground piping equipped with a leak
detection system. The exact location of the piping treatment system and discharge
point would need to be determined during remedial design.
The groundwater treatment system could be a packaged system that would be
delivered to the site. It was assumed that the treatment system would be housed
in a prefabricated structure to reduce noise, improve appearance, insulate the
treatment process, and protect equipment. The prefabricated structure would be
placed on a concrete foundation. A chain link security fence would be constructed
around the treatment facility to limit general accessibility to the facility and the
potential for public exposure. Piping, controls, valves, and pumps would be housed
within the building for year-round operation. Power lines would be connected, and
wiring would be installed to operate pumps, fans, lighting, and other equipment.
Signs would be posted to prevent unknowing entry into the building, and security
measures, such as alarms, would be implemented.
The treatment system would remove and transfer the contaminants from the
groundwater to the air using a shallow tray aeration process. Contaminated
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groundwater enters at the top of the treatment system and flows across a series of
aeration trays. Air passes upward through openings in the trays and bubbles
through the water forming a foamy/frothy surface which provides high turbulence
and excellent volatilization. Size of the trays and treatment system components
would be determined during treatability study and remedial design. The system
could be readily expanded to accommodate an increase in influent flow or
contaminant concentrations by addition of another series of trays, which are
stacked vertically onto existing trays.
The treated groundwater would be discharged to the tributary of Skull Creek at
the site, and sampled to insure compliance with the substantive requirements of the
Clean Water Act and the parallel state regulations. Treatment plant influent and
effluent would be monitored. It was assumed the influent and effluent would be
analyzed for CT, CF, and 1,2-DCA.
Although a surface discharge route will need to be designed and established,
EPA would also be willing to try to make some or all of the pumped and treated
water available for beneficial reuse, provided it is understood that EPA is not in a
position to arrange for the removal of other possible contaminants (such as nitrates
or other common groundwater contaminants not within the scope of this cleanup),
or to guarantee that the treated water is safe for any particular use.
For example, despite removal of the contaminants of concern (CT, CF, and 1,2-
DCA) to the surface water discharge limits or to the MCLs, the water may not be
potable because of other impurities.
If the water is to be used rather than discharged (at the expense of the State,
regional, or local authorities and/or local water users), EPA would consult with the
State, the Lower Platte North Natural Resource District, and the Village of Bruno
concerning the possible recipients of the water and concerning what state or local
governmental entity would plan to take responsibility for the water's further
treatment and distribution.
A concrete plan or design for the beneficial use of the discharge water would
need to be developed by one or more of the above identified parties and provided to
EPA for its review prior to the due date for the preliminary design documents (i.e.
the date the initial design deliverable is due to EPA) in order to allow adequate time
for any beneficial reuse plans to be incorporated into design. (The project scheaule.
once it is established, can be obtained by a request to the EPA project manager.)
Regardless of the above limitations, the pump-and-treat piping system will be
designed with a point of hookup built in, to accommodate any beneficial reuse
plans that may later be established.
Treatment of off-gases is not expected to be needed. The expected emission
rate of the chemicals of concern is 0.11 ton/year of CT, 8.1x103 ton/year of CF
and 1.4x10'3 ton/year of 1,2-DCA. According to the Nebraska Air Pollution Control
Rules and Regulations, Title 129, Chapter 27, Section 002; the allowable emission
rate is 2.5 ton/year of any hazardous air pollutant or an aggregate of 10 ton/year of
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hazardous air pollutants. If these limits are exceeded, off-gases would need to be
treated by Granular Activated Carbon (GAC). The GAC canisters would then need
to be disposed of off-site. For the purpose of costing out this alternative, it was
assumed that off-gas treatment would not be needed. Even if regulatory standards
would not be exceeded, modeling, and if necessary (based on the modeling),
monitoring, of the air emissions from the treatment unit would be required to
ensure that air emissions do not pose a hazard to nearby persons or residences.
Groundwater monitoring would be included under this alternative. New and
existing monitoring wells would be used to verify the hydraulic performance and
containment of the contaminant plume. The new and existing monitoring wells
would be sampled for VOCs including CT, CF, and 1,2-DCA. A detailed sampling
and quality assurance plan would be prepared to specify the sample location,
sample frequency (quarterly unless EPA determines otherwise), laboratory analysis,
and sampling procedures. Monitoring wells would need to be maintained and
replaced as needed to assure their continued effectiveness.
After eight quarters of monitoring results have been accumulated, a report will
be prepared to evaluate the effectiveness of the ongoing remedy, which shall
evaluate what adjustments or improvements or other changes to the system might
be beneficial to further the cleanup. Such a report will be prepared every two years
until the remedy is complete.
Based on modeling conducted by Black & Veatch, this alternative would take in
excess of 100 years to reach the cleanup standards.
8..3 Alternative 3: Active Restoration/Air Stripping with Tray Aeration
Capital Cost: $417,400.
Present Worth of Annual O&M Costs: $639,600.
Total Present Worth Cost: $1,057,000.
Construction time: 1-2 years.
Estimated cleanup time: 18 years.
Pump rate: 200 gallons per minute total.
Estimated number of extraction wells: 4.
Groundwater treatment technology: Tray aeration.
Disposal: Discharge to tributary to Skull Creek.
Alternative 3 is a more aggressive pump and treat aimed at restoring the
aquifer, by lowering the COCs to below MCLs throughout the aquifer. This
alternative includes the use of extraction wells, treatment of contaminated water by
air stripping using tray aeration technology, and discharge of the treated
groundwater to a tributary of Skull Creek, and/or beneficial reuse of the pumped
and treated water. Many of the features of Alternative 2, as discussed above,
would be included, but the key difference is achievement of MCLs throughout the
aquifer in as fast a time frame as feasible for the Site.
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The proposed locations, pumping rate, and screened intervals for the extraction
wells used for conceptual and cost estimation purposes in this alternative were
estimated using existing data and groundwater modeling. Modeling results
indicated that using four groundwater extraction wells screened throughout both
lower and .upper sand and middle silty units and pumping at approximately 50 gpm
each for a total rate of 200 gpm could remediate the aquifer in approximately 18
years. The actual location, pumping rate, and screened intervals of the extraction
wells would need to be determined during remedial design, using additional site
specific data acquired during remedial design investigations-.
Contaminated groundwater would be pumped to an on-site treatment system
consisting of air stripping with tray aeration. The treatment system, associated
double-contained piping with leak detection, the fence and security measures,
utilities and wiring, the along with the building housing the treatment system,
would be as described in Alternative 2; however, the flow rates through the system
would be higher than for Alternative 2, with the rate of pumping and number of
wells end their locations chosen to ensure that the aquifer is cleaned up to the
levels given in Section 7 in as fast a time frame as is feasible for the Site.
Even at the higher flow rate, treatment of the off-gases is not expected to be
required, since the anticipated emissions were estimated as 0.57 tons/year of CT,
4.1 x10'2 tons/year of CF and 7.0x103 tons/year of 1,2-DCA. These rates are
below the Nebraska Air Pollution Controls and Regulations emission limits.
However, even if regulatory standards would not be exceeded, modeling, and if
necessary (based on the modeling), monitoring, of the air emissions from the
treetment unit would be required to ensure that air emissions do not pose a hazard
to nearby persons or residences.
Treated groundwater would be discharged to the tributary of Skull Creek and
sampled to insure compliance with the substantive requirements of the Clean Water
Act and the parallel state regulations. EPA is also willing to try to accommodate
possible beneficial reuse of the water, subject to the limitations set forth in the
detailed discussion that appears above under Alternative 2. Regardless of the
limitations covered in detail above under alternative 2, the pump and treat system
would be designed with a point of hookup built in, to accommodate any beneficial
reuse plans that might later be established.
The final location of the components for this alternative will need to be
determined during remedial design.
New and existing monitoring wells would be used to verify the hydraulic
performance and to verify the active restoration of the contaminant plume. The
new and existing monitoring wells would be sampled for VOCs including CT, CF,
end 1,2-DCA. A detailed sampling and quality assurance plan would be prepared to
specify the sample location, sample frequency (quarterly unless EPA determines
otherwise), laboratory analysis, and sampling procedures. It was assumed for the
purpose of developing thits eltemative that two new nests of monitoring wells
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would be installed. Monitoring wells would need to be maintained and replaced as
needed to-assure their continued effectiveness.
After.eight quarters of monitoring results have been accumulated, a report will
be prepared to evaluate the effectiveness of the ongoing remedy, which shall
evaluate what adjustments or improvements or other changes to the system might
be beneficial to further the cleanup. Such a report will be prepared every two years
until the remedy is complete.
8.4 Alternative 4: Active Restoration/ln-situ Vapor Extraction
Capital Cost: $518,400.
Present Worth of Annual O&M Costs: $476,500.
Total Present Worth Cost: $994,900.
Construction time: 1-2 years.
Cleanup time: Unknown.
In-situ pump rate: 20 gallons per minute.
Estimated number of vapor extraction wells: 4.
Groundwater treatment technology: In-situ air stripping.
Disposal: N/A.
Alternative 4 would entail in-situ treatment of contaminated groundwater
through the use of in-situ vapor extraction wells. The in-situ vapor extraction wells
would be screened in both the upper sand aquifer zone and in the lower sand
aquifer zone. Air would be injected below the water table into the well by use of a
blower. The injected air causes a pressure gradient that draws groundwater from
the lower screen which becomes aerated. The aerated water is allowed to rise until
it meets a packer where the volatile organics are released. A vacuum blower is
used to apply a vacuum on the upper well casing to remove the organic vapors
from the well.
It was estimated that four in-situ vapor extraction wells would be placed in a
staggered line within the plume to capture and treat the groundwater. The wells
would be placed approximately 425 feet apart and would yield a treatment zone
approximately 1,600 feet long and 500 feet wide. The final locations and depths
of the wells would need to be established during a treatability study and remedial
design.
No treatment of the off-gas is expected. It was determined that the emissions
would be approximately 0.23 tons/year for CT, 1.6x102 tons/year for CF and
2.8x10'a tons/year for 1,2-DCA. These emission rates are within the Nebraska Air
Pollution Controls and Regulations emission limits. However, even if regulatory
standards would not be exceeded, modeling, and if necessary (based on the
modeling), monitoring, of the air emissions from the treatment unit would be
required to ensure that air emissions do not pose a hazard to nearby persons or
residences.
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Groundwater monitoring, as discussed in Alternatives 2 and 3 above, would be
performed under this alternative to verify hydraulic performance and to verify the
active restoration of the aquifer. Groundwater monitoring wells would be sampled
and maintained as described in Alternative 2 and 3, and reporting and evaluation of
the groundwater results would be subject to similar requirements.
Because, under this alternative, the water is not removed from the ground for
treatment, the discharge issues discussed in Alternatives 2 and 3 above do not
arise under this alternative.
Under each alternative except Alternative 1, access restrictions would be
implemented at the site during remediation efforts to prevent exposure to humans.
9.0 Comparative Analysis of Alternatives
During the comparative analysis of the alternatives, each alternative is assessed
against nine evaluation criteria. These criteria are: overall protection of human
health and the environment; compliance with applicable or relevant and appropriate
requirements; long-term effectiveness and permanence; reduction of toxicity,
mobility, or volume; short-term effectiveness; implementability; cost; and state and
community acceptance.
The following comparative analysis presents the strengths and weaknesses of
the alternatives relative to one another with respect to each of the nine criteria, and
how reasonable variations of key uncertainties could change the expectations, of
their relative performance.
9.1 Overall Protection of Human Health and the Environment
Overall protection of human health and the environment addresses whether or
not a remedy provides adequate protection and describes how risks posed through
each pathway are eliminated, reduced, or controlled through treatment, engineering
controls, or institutional controls.
Alternative 3 would be most protective of human health and the environment
because all groundwater with contaminant concentrations greater than cleanup
levels would be actively remediated. The technology used in Alternative 3
(extraction and treatment with air stripping) is proven effective for the removal of
volatiles from groundwater and has been used at numerous sites. Alternative 4
may also be protective of human health and the environment, and the technology
used in Alternative 4 (in-situ vapor extraction) is also effective in removing volatiles
from groundweter. However, the in-situ extraction technology is an innovative
technology and some concern has been expressed that it could result in
groundwater mounding at the site that could cause the contamination to spread.
Alternatives 1 and 2 would not meet cleanup goals at the site within a reasonable
time frame and would require long-term institutional controls and monitoring to
prevent consumption of groundwater to maintain protectiveness.
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The containment and treatment system in Alternative 2 would be effective in
ensuring that further migration of contaminants does not occur and the
contaminants would not migrate further towards uncontaminated residential wells.
However, only some protection of the environment would occur because although
groundwater would be extracted and treated, it would not be actively remediated.
Thus, contaminated groundwater would remain for an extended period.
Alternative 1 would not protect human health and the environment from the
contaminants in the groundwater in the vicinity of the site. Because no actions
would occur under Alternative 1, the groundwater contaminants may continue to
migrate in the aquifer, endanger the public supply wells and down-gradient
residential wells, and produce a larger contaminant plume.
Other than the contamination that remains until cleanup goals are met, no
short-term risks due to the operation of the treatment systems are expected in each
of the alternatives. Although contaminants are released into the air during
treatment operations in Alternatives 2, 3, and 4; the emission concentrations are
not expected to be significant and would have to conform with allowable emission
rates set forth in the applicable regulations.
9.2 Compliance with Applicable or Relevant and Appropriate Requirements (ARARs)
Compliance with ARARs addresses whether or not a remedy would meet all of
the applicable or relevant and appropriate requirements of other federal and state
environmental statutes and requirements.
Alternatives 2, 3, and 4 would comply with all location- and action-specific
ARARs and are anticipated to comply with all chemical-specific ARARs. However,
Alternative 2 may require an unreasonably long time period to attain site
remediation goals and also require the associated institutional controls and
monitoring for this same period; and Alternative 4 would require additional
investigation to determine whether the migration of the plume would be accelerated
due to its implementation. Alternative 1 would not comply with ARARs.
9.3 Long-Term Effectiveness and Permanence
Long-term effectiveness and permanence refers to the ability of a remedy to
maintain reliable protection of human health and the environment over time, once
cleanup goals have been met.
Alternatives 3 and 4 would provide active removal of the contaminants.
Alternative 3 is expected to reach cleanup levels in approximately 18 years and is
the shortest predicted cleanup time frame of any of the alternatives. It is the best
alternative in meeting long-term effectiveness and permanence. The time for
Alternative 4 to reach cleanup goals is unknown. A long-term risk would not be
associated with the treated groundwater in Alternatives 2, 3, and 4; however, a
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long-term risk would remain within the untreated aquifer until cleanup levels are
met. The amount of time to reach cleanup levels if Alternative 2 is implemented is
estimated to be greater than 100 years.
Because _no remedial actions would occur, a long-term risk would be associated
with Alternative 1 as long as cleanup goals would not be met. The possibility
exists for greater volumes of contaminated groundwater to be generated with no
active intervention. With Alternative 1, no mechanism would exist as part of that
alternative to determine if concentrations are increasing or decreasing. Thus, the
long-term risk would be greater with Alternative 1.
Five-year reviews would be required for all alternatives. Alternative 1 would
require the largest number 5-year reviews because restoration (if reached) would
take the longest. Fewer reviews would be required for Alternatives 3 and 4 than
for Alternative 2.
The proposed monitoring/treatment technologies in Alternatives 2, 3, and 4
should adequately and permanently achieve the performance specifications
established in the cleanup goals eventually, although the time to achieve them with
Alternative 2 is excessively lengthy. No action and no monitoring would occur in
Alternative 1, however, there would be no mechanism to determine if cleanup
goals are being met.
Long-term management is required for all the alternatives with the exception of
Alternative 1. A long-term monitoring program would be needed to determine if
groundwater contaminant concentrations are decreasing. Maintenance, along with
a long-term monitoring program, would need to be performed on a regular basis for
Alternatives 2, 3, and 4. Maintenance would be more involved in Alternatives 3
and 4, because more wells or more equipment would be required. The monitoring
program and maintenance for Alternatives 2, 3, and 4 would be extensive but
easily implemented. Components of the treatment system such as pumps and
valves in Alternatives 2, 3, and 4 may require replacement during the time of
operation. However, proper maintenance of the equipment should be conducted in
order to minimize the need for costly repairs and replacement. Monitoring wells will
be maintained in good working order and repaired or replaced as needed for
Alternatives 2, 3, and 4.
9.4 Reduction of Toxicity, Mobility, and Volume Through Treatment
Reduction of toxicity, mobility, or volume through treatment is the anticipated
performance of the treatment technologies a remedy may employ.
A reduction in toxicity, mobility or volume would occur in Alternatives 2, 3, and
4. The reduction would take much longer under Alternative 2 than Alternatives 3
and 4. However, Alternative 4 is an innovative technology that has not been
proven effective for this site. Alternative 4 has the potential of spreading the
contamination due to mounding. Thus, it would potentially not reduce mobility of
the contamination. Therefore, Alternative 3 appears to be the best choice in
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reducing toxicity, mobility, and volume of the contamination. The groundwater
treatment would be irreversible. No residuals would be produced from any of the
alternatives, Beyond the small rate of discharge by the treatment systems to
ambient air, and the discharge of the treated water in Alternatives 2 and 3. All the
alternatives except Alternative 1 would meet the statutory preference for treatment
as a principal element. Alternative 1 provides no mechanisms to determine if
reduction is occurring; moreover at the present time there is no basis for asserting a
reduction in toxicity, mobility, or volume under Alternative 1.
9.5 Short-Term Effectiveness
Short-term effectiveness addresses the period of time needed to achieve
protection and any adverse impacts on human health and the environment that may
be posed during the construction and implementation period until cleanup goals are
achieved.
The risk to the community and workers would be minimal for all alternatives.
None of the risks would be uncontrollable. Nearby residents may be exposed to
contaminated dusts during installation of monitoring and extraction wells. These
risks would be controlled by the use of dust suppressants. The risk to workers
would be controlled by proper use of personal protection equipment and monitoring
during site activities.
Based on groundwater monitoring and contaminant fate and transport modeling,
it is estimated that the time to achieve cleanup goals for Alternative 3 would be 18
years. Alternative 3 involves extracting the groundwater at approximately 200
gpm. Alternative 2 involves extracting the groundwater at a rate of only 40 gpm.
Based on information received from vendors, the time to achieve cleanup levels for
Alternative 4 may be shorter if this technology is proven to be applicable for this
site. (The application of groundwater models for evaluating the effectiveness of
Alternative 4 is still being researched.) The time to achieve cleanup levels would be
greatest for Alternatives 1 and 2. Alternatives 1 and 2 would take a much longer
time than Alternatives 3 and 4. Because no monitoring would be performed in
Alternative 1, it would not be known if cleanup levels are ever met. In particular,
though, it is estimated that they would not be met within the 30-year planning
period typically used by EPA, as is also the case for Alternative 2.
9.6 Implementability
Implementability is the technical and administrative feasibility of a remedy,
including the availability of materials and services needed to implement a particular
option.
Alternatives 2, 3, and 4 include installation of two monitoring wells nests and a
groundwater sampling program, and also require the installation of extraction or
treatment wells and treatment system components. Alternative 2 would be easier
to implement than Alternatives 3 because the extraction wells are screened only in
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the upper and lower sand aquifer zones. In Alternative 3, each of the four
extraction wells would be screened throughout all three aquifer zones. The
groundwate/ treatment system components (pumps, piping, trays, etc.) in
Alternative 3 would also be larger and may require more maintenance than in
Alternative 2. Alternative 4 is an innovative technology whose reliability and
effectiveness is less well-known in comparison to the more conventional
pump-and-treat technologies of Alternatives 2 and 3. In addition, groundwater
modeling performed by Argonne for the USDA suggests that Alternative 4 would
potentially cause mounding of groundwater during the attempt to return water to
the aquifer, and might cause possible spreading of the plume of contamination and
potential for flooding because of the low transmissivity of the silty layer at this site.
With the exception of Alternative A, all the alternatives are proven and reliable.
9.7 Cott
Cost includes estimated capital and operation and maintenance costs, and net
present worth costs. The cost comparisons for the alternatives include the detailed
cost estimates for each alternative.
Only O&M costs converted to a total present worth would be associated with
Alternative 1. The total present worth of Alternative 1 would be the lowest at a
cost of $41,700. The total present worth costs of Alternatives 2 and 4 are,
$862,400 and $994,900 respectively. The total present worth cost of Alternative
3 would be the greatest at a cost of $1,057,000. It should be noted that the
vendors shorter cleanup time frame for Alternative 4 is an estimate which would be
dependent on the proof of the effectiveness of this technology for this site.
9.8 State Acceptance
State acceptance indicates whether, based on its review of the RI/FS reports
and Proposed Plan, the state concurs, opposes, or has no comment on the
preferred alternative.
The State of Nebraska has been involved with this site since the beginning of
site activities and has reviewed the FS and ROD. The State of Nebraska prefers
that a permanent solution be selected.
9.9 Community Acceptance
Community acceptance of the selected remedy is further discussed in the
responsiveness summary of this ROD. In general, the community supports a
remedy that restores groundwater.
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10.0 Selected Remedy
Alternative 3, a pump and treat cleanup of the groundwater as more fully
described below, is the selected remedy for the Bruno Co-op site. Alternative 3 will
provide the best balance of trade-offs among alternatives with respect to the
evaluating criteria. EPA believes Alternative 3 will be protective of human health
and the environment will comply with ARARs, will be cost effective, and will utilize
permanent solutions and alternative treatment technologies or resource recovery
technologies to the maximum extent practicable. The remedy also will meet the
statutory preference for the use of treatment as a principal element.
10.1 Description of Selected Remedy
The selected remedy is an active pump and treat remedy to restore the aquifer,
lowering the COCs to below MCLs throughout the aquifer as in the fastest time
frame feasible for the Site. This alternative includes the use of extraction wells,
treatment of contaminated water by air stripping using tray aeration, and discharge
of the treated groundwater to a tributary of Skull Creek, and/or beneficial reuse of
the pumped and treated water.
The pumping well locations, pumping rate, and screened intervals for the
extraction wells will be determined during remedial design to provide coverage
(overlapping cones of depression) over the entire contaminated area (Figure 11) and
to clean up the aquifer in the fastest reasonable time frame.
Additional site specific data will be collected during remedial design
investigations to determine the exact well locations, pumping rate, and screened
interval. However, modeling results summarized in EPA's July 1998 FS suggested
the possibility that using four groundwater extraction wells screened throughout
both lower and upper sand units and pumping at approximately 50 gpm each for a
total rate of 200 gpm could remediate the aquifer in approximately 18 years.
Contaminated groundwater will be pumped to an on-site treatment system
consisting of air stripping with tray aeration. The treatment process and any on-
site discharges of residuals will comply with the ARARs established in this ROD.
The treatment system will be housed in a structure to reduce noise, improve
appearance, insulate the treatment process, and protect equipment. The structure
will be placed on a concrete foundation. A chain link security fence will be
constructed around the treatment facility to limit general accessibility to the facility
and the potential for public exposure. Piping, controls, valves, and pumps will be
housed within the building for year round operation, and sufficient additional
soundproofing will be provided, if needed, to ensure that neighbors of the operation
(nearby residences and businesses) are not disturbed. Power lines will be
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connected, and wiring installed to operate pumps, fans, lighting, and other
equipment. Signs will be posted to prevent unknowing entry into the building, and
security measures, such as alarms, will be implemented.
The treatment system will remove and transfer the COCs from the groundwater
to the air using shallow tray aeration. Contaminated groundwater enters at the top
of the treatment system and flows across a series of aeration trays in a process
which volatilizes the contamination. Size and number of trays would be established
during design, and may need to be revised from time to time. Based on the
estimated rate of treatment, the treatment of off-gases is not expected to be
required to comply with the applicable air regulations, since the anticipated
emissions were estimated as 0.57 tons/year of CT, 4.1x10* tons/year of CF and
7.0x10'3 tons/year of 1,2-DCA, less than the 2.5 ton/year of a single contaminant
or 10 ton/year of combined contaminants that would trigger Nebraska regulations.
However, even if regulatory standards would not be exceeded, modeling, and if
necessary (based on the modeling), monitoring, of the air emissions from the
treatment unit will be required to ensure that air emissions do not pose a hazard to
nearby persons or residences.
Treated groundwater will be discharged to the tributary of Skull Creek and
sampled to ensure compliance with the substantive requirements of the Clean
Water Act and the parallel state regulations. EPA is also willing to try to
accommodate possible beneficial reuse of the water, but this is subject to the
limitations set forth in Section 8.2 above. In any event, the pump and treat system
will be designed and built with a point of hookup to accommodate any beneficial
reuse plans, whether those plans are established now or later, to avoid the need to
retrofit such a hookup later.
The location of the treatment system and other components of the remedy will
be established as part of remedial design.
Groundwater monitoring using new and existing monitoring wells will be
required in order to verify the hydraulic performance and to verify the active
restoration of the contaminant plume, and the number and locations of wells will be
sufficient to accomplish this goal. New and existing monitoring wells will be
sampled for VOCs including CT, CF, and 1,2-DCA. A detailed sampling and quality
assurance plan would be prepared to specify the sample location, sample frequency
(quarterly unless EPA determines otherwise), laboratory analysis, and sampling
procedures. Monitoring wells would need to be maintained and replaced as needed
to assure their continued effectiveness.
After eight quarters of monitoring results have been accumulated, a report will
be prepared to evaluate the effectiveness of the ongoing remedy, which shall
evaluate what adjustments or improvements or other changes to the system might
be beneficial to further the cleanup. Such a report will be prepared every two years
until the remedy is complete.
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The selected remedy also includes the abandonment of Bruno Supply Well #36-
1 following State guidelines, and returning Bruno Supply Well #65-1 to use as a
source of drinking water for the Village by placing treatment1 of on this well in
times of high demand. During use, the raw and treated water from this well will
need to be monitored for the COCs.
During remedial design, a study will be conducted, called a "value engineering
study" to ensure that, at the time of implementation of the remedy, opportunities
are explored for achieving any possible economies utilizing technological
improvements and alternative approaches to carrying out the preferred remedy and
achieving the cleanup goals. Five-year reviews will also be required for this
remedy, which will allow an opportunity for examination of more effective new
technologies that may later arise. If a change in remedy is needed at a later date,
EPA would follow the procedures required by the NCP to amend the ROD, if a
fundamentally different remedy is selected, or, alternatively, would publish an
"explanation of significant differences" for any significant changes to the remedy.
10.2 Summary of Estimated Costs
The estimated capital cost for the remedy is $417,400. The estimated present
worth of annual O&M costs is $639,600. The estimated total present worth cost
is $1,057,000 assuming a 5 percent discount rate. A detailed breakout of the
costs are presented in Table 1. .
10.3 Cleanup Levels
This remedy shall address groundwater contaminated above the following
action levels:
• 5 ^g/L carbon tetrachloride,
• 5 A
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contaminant recovery from the middle silt unit. This uncertainty however, could be
resolved during the value engineering study included as part of the remedy.
The site aquifer is expected to be available as a drinking water resource as a result
of successful completion of the remedy.
11.0 Statutory Determinations
CERCLA Section 121(d) requires that the selected remedy comply with all
federal and state environmental laws that are applicable or relevant and appropriate
to the hazardous substances, pollutants, or contaminants at the site or to the
activities to be performed at the site. Therefore, to be selected as the remedy, an
alternative must meet all ARARs or a waiver must b« obtained. A discussion of
how each ARAR applies to the selected remedy is provided in the following
paragraphs.
11.1 Protection of Human Health and the Environment
The selected remedial action will protect human health and the environment
through hydraulic extraction of contaminated groundwater, and subsequent
treatment and disposal of the extracted groundwater. This will eliminate the
groundwater pathways through which contaminants pose risks. "-
11.2 Compliance with ARARs
Section 121(d)(2) of CERCLA, 42 U.S.C. §9621 (d)(2), requires that cleanup
actions conducted under CERCLA achieve a degree or level of cleanup which, at a
minimum, attains "any standard, requirement, criteria or limitation under any
Federal environmental law...or any promulgated standard, requirement, criteria, or
limitation under a State environmental or facility siting law that is more stringent
than any Federal standard...(which) is legally applicable to the hazardous substance
or pollutant or contaminant concerned or is relevant and appropriate under the
circumstances of the release or threatened release of such hazardous substance or
pollutant of contaminant...." The identified standards, requirements, criteria, or
limitations thus adopted from other environmental laws, which govern on-site
cleanup activities at this site, are referred to as "applicable or relevant and
appropriate requirements", or "ARARs."
For on-site cleanup activities, under Section 121(e)(1) 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.
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This section identifies the ARARs which will apply to the on-site cleanup
activities for this site. (The many laws and regulations which apply to off-site
cleanup or disposal activities are not called "ARARs" and are not enumerated here.)
FEDERAL ARARt
Clean Air Act of 1963, as amended (42 U.S. C. § § 7401-7671 q)
40 Code of Federal Regulations (CFRl Part SO
Part 50 (containing national ambient air quality standards) is pertinent to
excavation and materials handling activities.
Emissions from air strippers or from in-situ treatment of VOC-contaminated
groundwater on site under CERCLA, resulting in air emissions of CT, CF, and
1,2-DCA under 10 tons per year, are not now regulated under the Clean Air Act.
Clean Water Act of 1977. as amended (33 U.S.C. § § 7257- 7376V
40 CFR Parts 122- 125
The National Pollutant Discharge Elimination System (NPDES) was established
to control discharge of pollutants from any point source into waters of the United
States. A permit will not be required since the site is being remediated as part of
the Superfund program and the discharge point is on-site; however, the substantive
requirements of the regulation must be met. This regulation applies to the
discharge of treated groundwater and process water to surface water.
Discharge limits for the CT, CF, and 1,2-DCA will be established during
remedial design and will be consistent with the requirements of the NPDES
program. If established surface water discharge limits are not met, provisions for
alternate effluent limits can be found in this part.
Under the Clean Water Act, states must establish ambient water quality criteria
for the protection of surface water based on use classifications and the criteria
stated under Section 304(a) of the Clean Water Act. These criteria are applicable
(see the discussion under "State ARARs," below) and will be used to establish
discharge limits for treated groundwater and process water.
Safe Drinking Water Act of 1986. as amended (4O U.S.C. i 1300)
40 CFR Part 144-168
The substantive requirements of the underground injection regulations apply to
any treated groundwater that is reinjected.
40 CFR Part 141
Primary Drinking Water Standards are established by this part. The Safe
Drinking Water Act's MCLs are health-based standards for chemicals that may be
found in public water supplies. The MCLs for CT, trihalomethanes, and 1,2-DCA
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would be applicable or relevant and appropriate if the treated water is beneficially
reused for human consumption.
The discharge of treated groundwater or process water will otherwise not
impact drinking water in a public water supply directly. However, the potential for
residual contaminants percolating to groundwater exists, The NCP requires
consideration of MCLs, where they exist, as relevant and appropriate to
groundwater cleanup standards when the aquifer is a current or potential source of
drinking water. MCLs for the COCs, CT, CF(the MCL for trihalomethanes), and
1,2-DCA, are relevant and appropriate for establishing cleanup standards to be met
during implementation of the remedy.
Resource Conservation and Recovery Act (RCRA) of 7976", as amended (42 U.S. C.
§56907-69577
40 CFR Part 261
The criteria set forth in this part will be used to determine if solid wastes
excavated, created through treatment, or otherwise generated during the
implementation of the remedy are hazardous or non-hazardous.
40 CFR Part 262.11
The methods for determining whether a solid waste is hazardous are set forth in
this part. All generators of solid wastes are required to determine if a waste is
hazardous. Wastes determined to be hazardous will be managed in accordance
with the rules applicable to hazardous wastes.
40 CFR Part 262.34
The accumulation of hazardous waste on-site is addressed by this part. In the
event any of the solid wastes excavated, created through treatment, or otherwise
generated during the implementation of the remedy are hazardous, these
regulations will apply.
RCRA regulations that apply to facilities for the treatment, storage or disposal
of hazardous waste were determined not to be applicable or relevant and
appropriate at this site.
STATEARARs
Information supplied to Department of Water Resources to Facilitate the Listing of
Wells. The substantive requirements of R.S. Neb. 46-602(1) are applicable or
relevant and appropriate. EPA would like the location of its wells to be listed by the
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
EPA wells.
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Water We// Standards and Contractor Licensing Act. The substantive standards of
Title 178 aimed at 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 121(e) of CERCLA, EPA
does not require permits from the Natural Resources District (NRO) or from a state
agency for placement or operation of monitoring or pump-and-treat wells on-site.
However, EPA will cooperate with state agencies and the Lower Plane North
Natural Resources District in carrying out cleanup activities and in making readily
available to state agencies and the NRD groundwater information collected during
the cleanup.
Air Quality. Title 129 would require carbon adsorption treatment if more that 2.5
tons per year of one of the COCs (CT, CF, or 1,2-DCA) would be discharged to
ambient air, or if more than 10 tons per year would be discharged of all three COCs
combined. Based on concentrations in the groundwater and the rates of treatment,
it is unlikely those levels would be reached, however.
NDEQ will have an opportunity to review the remedial design and so will be
able to review compliance with this requirement.
Hazardous Waste. If discharge gases are treated with GAC the spent carbon
adsorption units will be shipped off-site and disposed of properly. While on-site,
they would be governed by the applicable Title 128 requirements, which are
hazardous waste determination and a limitation on-site accumulation times.
Groundwater Quality Standards and Use Classification. Title 118, Chapter 4,
establishes numerical standards for contaminants introduced to groundwater by
human activity: Title 118, Appendix A, Step 8, establishes a method for
determining preliminary cleanup levels for the different classifications of protected
groundwater.
Discharge of Treated Water. Any discharge to surface water on-site must meet the
substantive requirements of the state NPDES program (Title 119 and 121), and
must be consistent with the creek's use requirements and the accompanying
numerical standards, as given in Title 117, Nebraska Surface Water Quality
Standards.
If treated groundwater is reinjected Title 122 governing underground injection is
applicable.
If treated groundwater is to be beneficially reused for human consumption, the
MCLs for CT, total trihalomethanes, and 1,2-DCA would be applicable or relevant
and appropriate.
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Flood Plain Management. The Flood Plain Management Act, Neb^ Rev. Stat.
§31-1001 et seo.. and Title 258- Rules Governing Flood Plain Management govern
certain activities occurring in flood plains (Department of Natural Resources).
Endangered or Threatened Species. The Nebraska Nongame and Endangered
Species Act, Neb. Rev. Stat. §37-430 to §37-438, and Title 163, Chapter 6,
requires consultation with the Nebrar a Game and Parks Commission regarding
actions which may affect threatened r endangered species and their critical habitat
in the State of Nebraska. These species are listed in Title 163 (Game and Parks
Commission).
11.3 Cost Effectiveness
The selected remedial action is cost-effective, providing overall effectiveness
proportional to its costs. The selected remedy will be effective in the long-term,
providing a significant and permanent reduction of the toxicity, mobility, and
volume of contaminated groundwater.
11.4 Utilization of Permanent Solutions and Innovative Treatment Technologies
to the Maximum Extent Practicable
SARA specifies a preference for use of permanent solutions and innovative
treatment or resource recovery technologies to the maximum extent practicable.
The selected remedial action utilizes a permanent solution but not an innovative
treatment technology. Of those alternatives that comply with the threshold criteria
EPA, has determined that the selected alternative provides the best balance in
terms of long-term effectiveness and permanence, reduction of toxicity, mobility,
and volume through treatment, short-term effectiveness, and cost.
11.5 Preference for Treatment which Reduces Toxicity, Mobility, or Volume
By hydraulically containing and extracting groundwater containing COCs greater
than the final cleanup goals, the selected remedial action addresses the principal
threat posed by the site. The selected remedy also satisfies the statutory
preference for remedial actions that employ treatment to significantly reduce
toxicity, mobility, or volume of contaminants.
12.0 Documentation of Significant Changes
The selected remedy has not been significantly changed from the preferred
alternative presented in the Proposed Plan.
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HI. RESPONSIVENESS SUMMARY
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III. Responsiveness Summary For The Record of Decision
Bruno Cooperative Association/
Associated Properties Site
Bruno, Butler County, Nebraska
Overview
Public participation activities required under the Comprehensive Environmental
Response, Compensation and Liability Act (CERCLA) took place during the summer
of 1998. An Administrative Record File was made available to the public at the
Bruno Post Office beginning on July 16, 1998. A public meeting was held at 7:00
p.m. on July 23, 1998, at the Bruno Village Hall. EPA's Proposed Plan was
distributed at that meeting, and placed at the Post Office the next day. A period of
public comment period on the Proposed Plan and other documents in the
Administrative Record File concluded on August 22, 1998.
During the public meeting, community members expressed concerns about and
asked questions concerning the size of the treatment system, the location of the
system, noise associated with cleanup activities, the length of time for the cleanup,
the other alternatives considered, the effect of cleanup on nearby wells, and the
potential for the old municipal water supply wells to be used again. The transcript
from the public meeting will be included in the Administrative Record File.
During the public comment period, EPA received a letter from the Village of Bruno's
Board of Trustees, signed by its Chairman, supporting EPA's preferred alternative.
The Village Board's letter expressed hope that the preferred alternative would allow
the Village to again use wells that were taken out of service because of the carbon
tetrachloride contamination.
The Nebraska Department of Environmental Quality (NDEQ) stated at the public
meeting that they were generally very positive about the alternative proposed by
EPA. NDEQ also submitted a letter during the public comment period expressing
their desire to work with EPA to ensure that community concerns are met.
The United States Department of Agriculture (USDA), a potentially responsible
party (PRP) at the site, sent in detailed comments to EPA during the public
comment period. In their comments, USDA put forth a number of technical
arguments. EPA responses to those comments appear below, in a separate section
devoted to USDA's comments.
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Community and State Comments and EPA's Responses
This section provides a summary of major issues and concerns raised by community
members and the state during the public comment period. Each comment is
followed-by EPA's response.
1) Comment: One citizen at the public meeting expressed the desire to see the
groundwater cleaned up in order to have it be usable for the community in years to
come. Another citizen commented in a letter that, in view of the cost of the
cleanup and the time it would take, Alternative 1 (the no action alternative) should
be implemented over Alternative 3 (pump and treat cleanup of the aquifer). This
commenter suggested pumping water from a neighboring town (such as Abie,
Nebraska, 4 miles from Bruno) if another municipal well is needed. (A similar
question was also raised at the public meeting, asking who would be hurt if the
contamination were left alone to disappear on its own.)
Response; Without some active measure, such as the selected alternative, the
contamination in the aquifer in the area formerly used by the Village of Bruno as a
source of drinking water is likely to remain in the aquifer, posing a threat to the
health of any future users of that aquifer for drinking water purposes. The fact that
the Village has used one of the affected wells, Supply Well #65-1, in the recent
past as a backup source of water during a time of increased demand illustrates that
current conditions at the site are not adequately controlled, and there is a need for
action to permanently remove the threat presented by the contamination. EPA's
goal for the cleanup action at the Bruno site is to restore the contaminated
groundwater to Safe Drinking Water Act levels.
2) Comment: A commentor asked how much noise the remedial treatment
system would generate.
Response; The type of air stripper used for the selected alternative (Alternative 3) is
relatively quiet. The ROD calls for the aeration unit to be housed in a building and
for sound insulation or other measures to be taken as needed to make sure that
nearby residents or businesses are not disturbed.
3) Comment: A commentor asked if the treatment system pumping would have
any effect on neighboring wells by taking water from them or lowering the water
table.
Response; The extraction system will be designed to cover the horizontal extent of
the contaminated area as shown on Figure 11 in the ROD and should have little or
no impact on any wells beyond the contaminated area. Wells inside the
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contaminated area will experience some drawdown, but most current uses would
be unaffected. The effects on nearby wells in the contaminated area will be looked
at during remedial design.
4) Comment: A commentor asked if anyone living close to the remedial treatment
system would be adversely affected by it.
Responte: In addition to considering the potential for noise disturbance (discussed
above, Comment #2), and possible effects on neighboring wells (discussed above,
Comment #3), EPA has considered impacts that the selected action might have via
the discharge of treated water and by emissions to air.
The treated water will be discharged to an on-site creek (unless beneficial reuse of
some or all of the water is arranged by state or local authorities - see Section 8.2
of the ROD for more discussion about beneficial reuse). This treated discharge
water should not present a threat to human health or the environment from the
concentration of the contaminants of concern (CT, CF, or 1 ,2-DCA), since the
water will have been treated to discharge standards; and the discharge rate of
about 200 gpm (less than O.Scfs) would not create any potential for flooding in the
area.
Contaminants of concern (CT, CF, or 1,2-DCA), stripped from the contaminated
groundwater, will be off-gassed to the atmosphere from the treatment unit. Initial
calculations, discussed in the ROD, which are based on the highest concentrations
of contaminants of concern in extracted groundwater and using expected pumping
rates, indicate that air emissions from the treatment unit will fall far below
allowable discharge limits established by Nebraska's Title 129 regulations. Air
modeling of the discharge from the treatment unit will be performed during design,
and air monitoring will be performed if the modeling shows that levels of concern
could be generated by the treatment unit. If air monitoring detects levels of
concern to human health or the environment, the air emissions can be treated using
granulated activated carbon (GAC).
5) Comment: One commentor asked whether provisions had been made to allow
for beneficial reuse of the water that is pumped out of the ground.
: The EPA's preferred remedy calls for the discharge of treated water to a
tributary of Skull Creek with the water being monitored to ensure compliance with
the substantive requirements of the Clean Water Act and the parallel State
regulations. Alternatively, EPA would be willing to make the water available for
beneficial reuse, provided it is understood that any such arrangements would
necessarily be the responsibility of the appropriate state and local authorities, and
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that EPA is not in a position to arrange for the removal of other possible
contaminants (e.g., nitrates, or other common groundwater contaminants not
within the scope of this cleanup), or to guarantee that the water is safe for any
particular use. For example, despite removal of the contaminants of concern (CT,
CF, and 1,2-DCA) to concentrations below ARARs, the water may not be potable if
other common contaminants are present. The ROD provides that if local, regional
or state authorities can come up with a concrete beneficial reuse plan in a timely
way (i.e. by the due date for the preliminary design), the remedial design for the
remedy could take account of such a plan, If not, the piping for the remedy will
still include a hookup point to accommodate plans for beneficial reuse that may be
generated later, to avoid the need to retrofit such a link.
6) Comment; Other more effective technologies could become more promising in
the future. The remedy should be reviewed two years after the site cleanup begins
so that new, cheaper technologies could be considered as they become available.
Response: After the remedy is put in place, periodic groundwater monitoring will
assess the remedy's continued effectiveness. After eight quarters of groundwater
monitoring results have been accumulated, a report will be prepared to evaluate the
effectiveness of the ongoing remedy which will evaluate what adjustments or
improvements or other changes might be beneficial to further the cleanup. Such a
report is to be prepared every two years thereafter until the remedy is complete.
The following comments were submitted bv USDA. a Potentially Responsible Party
at the site. Each comment IB follpwed bv EPA'a response.
7) Comment: The Proposed Plan for the Bruno site does not include new
information such as more recent and more accurate models of groundwater flow
and solute transport from Argonne National Laboratory that were provided to EPA
before the Proposed Plan was issued. This new information should have been used
in calculating cleanup scenarios rather than the 1995 Argonne models that were
used.
Response: The data collected during the extended monitoring program conducted
by Argonne which is presented in the USOA's April 1998 Final Study (Argonne,
April 1998) has been reviewed by EPA. USOA's April 1998 study is also included
in the Administrative Record File. EPA's review of this report concluded that the
new data and the modeling runs reported in the April 1998 study do not
significantly change the previous understanding of the subsurface of the Bruno site.
Two examples of modeling uncertainties are USDA's grain size analysis of the
middle silty layer which shows considerable large grain material (sand) indicating
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that contaminants could be induced to move from the middle silty layer at a higher
rate than indicated by USDA's modeling runs. Moreover, USDA did not calibrate its
model using their own pump test data generated as part of their investigation of the
site, which could have illustrated how well their modeling predicts aquifer
conditions.
8) Comment: The Proposed Plan does not address how the most contaminated
section of the aquifer at the Bruno site, the middle silty aquifer unit, will be
remediated to levels that meet the Preliminary Remediation Goals {PRGs) the EPA
has established in its plan. As the NCP stipulates, the revised Proposed Plan should
include alternatives that address both the technical feasibility of remediation of this
section of the aquifer to the PRGs and the screening of the alternatives. If the EPA
cannot provide technically feasible alternatives for cleaning up the middle silt unit to
levels that meet the established PRGs, then the revised plan should include
modified remediation goals that are protective of human health and the environment
and take into account the technical impracticality of remediation of the middle silty
zone to maximum contaminant level (MCL) cleanup levels.
Response: EPA and USDA (in its April 1998 study) agree that aquifer restoration
should be pursued by using pump-and-treat methods. Additionally, the number,
location, and pumping rates of extraction wells proposed by EPA.in the FS and the
Proposed Plan is not significantly different than the USDA proposal as presented in
USDA's April 1998 submission. Groundwater sampling to monitor the
progress/effectiveness of the system is included as part of the selected remedy. If
future data indicates that the extraction system is having little impact on the middle
silty layer, adjustments can be considered. If it can be shown that achievement of
the cleanup goals for the middle silty layer is impracticable then the EPA can
consider amending the remedy or granting a technical impracticability waiver under
CERCLA. The conceptual design used for comparison purposes in the FS may be
different from the remedial design. However, the EPA believes that it is possible to
remediate all portions of the aquifer and that the final number, pumping rate, and
placement of extraction wells should be designed to maximize the success of the
system in the middle silty layer as well as the upper and lower sand layers. If
USDA's grain size data is representative of the middle silty layer then it is
reasonable to anticipate that the selected alternative will achieve the cleanup goals.
9) Comment: Please indicate how the EPA has determined that USDA's proposed
alternative is not consistent with EPA's Natural Attenuation Policy.
Response: Presently there has been no evaluation to determine if the rate of
natural attenuation at the site is sufficient to accomplish remedial action objectives.
The efficiency of the natural attenuation rate for the contaminants of concern is
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accomplished by evaluating the biogeochemical system at the site. EPA suggested
to USDA (correspondence dated April 11, 1997) to include biogeochemical
parameters in their monitoring program to allow evaluation of the efficiency of the
site's natural attenuation rate. USDA declined the suggestion (correspondence
dated June 17, 1997). Until the site's natural attenuation rate can be
substantiated, natural attenuation cannot be included as part of the selected
remedy.
10) Comment; The baseline risk assessment used by the EPA is based on incorrect
assumptions and inappropriate models (citing examples discussed below), and it
exaggerates the potential risk at the site.
Response: The fact that the Village of Bruno still uses Supply Well #65-1 as a
backup supply during times of scarcity and that it has shown detectable levels of
site contaminants illustrates that risks continue to exist at the site from
groundwater. The local ordinance on new well construction only requires that a
permit be obtained to install a new well inside the Village of Bruno and does not
prohibit the installation of new wells, es suggested elsewhere in USOA's
comments, even in the most contaminated areas of the Site.
When evaluating the human health risks posed by groundwater contamination, it is
appropriate to use the concentration at the highest point of contamination in the
plume as the exposure point concentration. This is consistent with the Risk
Assessment Guidance for Superfund (RAGS V1 A Section 6.5.2, page 6-27) which
states "...it generally should be assumed that water could be drawn from anywhere
in the aquifer, regardless of the location of existing wells relative to the
contaminant plume." The NCR Preamble (55 FR 8713) states "For groundwater,
remediation levels should generally be attained throughout the contaminated plume,
or at and beyond the edge of the waste management area when waste is left in
place."
One USOA comment on soil risk was addressed by a modification to the
recommended remedy: According to Nebraska Department of Health's (NDOH)
1995 risk analysis, a possible future child resident of the grain bin site, exposed to
CT in the soil at the location of highest soil contamination, might experience
adverse health effects from exposure to chemicals evaporating from the soil. This
calculation, however, assumed (in addition to the assumption that a child is playing
and digging in the soil at this location on a daily basis) that the highest level in
soils, 2,700 |/g/kg, is spread uniformly over an area 45 meters on one side.
However, USDA pointed out that nearby samples as close as 25 feet away showed
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non-detect values, causing EPA to reevaluate the calculation. EPA has determined
as a result of this revaluation that institutional controls to restrict residences from
being built'on the former USDA grain bin site are not needed as part of the remedy.
11) Comment: USDA commented that there is no risk evaluation for residual
contamination that would remain in the aquifer if the EPA's preferred alternative is
implemented.
Response: It is EPA's intention to remediate the aquifer to the remediation goals for
the cleanup which are the drinking water standard for the contaminants of concern.
If cleanup goals can be reached in the aquifer, then residual risk analysis will not be
necessary. Groundwater sampling to monitor the progress/effectiveness of the
system is included as part of the remedy. If future data indicates that the
extraction system is having little impact on the middle silt unit, remedy adjustments
can be considered. If it can be shown, after pumping the aquifer aggressively for
the purpose of remediating all layers of the aquifer, that achievement of the cleanup
goals for the middle silty layer is impracticable, then the EPA can consider
amending the remedy or granting a technical impracticability waiver under CERCLA.
12) Comment: The location chosen by the NDOH for its risk assessment is not a
realistic home site because it lies substantially below base flood level in a flood
plain across the street from a National Priorities List site.
Response: Several homes already exist in the area referred to by USDA as a flood
plain. Also, no institutional controls or other restrictions prevent the drilling of new
wells even in the most contaminated parts of the aquifer. Therefore the exposure
scenario used for groundwater is realistic for this site. The contaminated portion of
this groundwater aquifer was used as a source of drinking water for the Village and
could be used again in the future.
13) Comment; USDA's September 1995 interim study for Bruno, Nebraska,
prepared for the CCC/USDA by Argonne2, has been omitted from the administrative
record provided by the EPA. Preliminary hydrogeologic models developed by
Argonne in the September 1995 study demonstrated the complex nature of the
Bruno groundwater flow and contaminant transport system. Argonne concluded
that these preliminary hydrogeologic models could not be used to perform a
quantitative evaluation of remedial needs or alternatives for the Bruno site, due to
uncertain impact of (1) inferred variations in the hydraulic characteristics of the
3USDA comments reference an August 1996 "interim Feasibility Study" prepared for
CCC/USDA by Argonne. EPA has a September 1995 study by the same name, but does not have
one dated August 1996. EPA assumes the reference in USDA comments is to the 1995 study.
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middle silt aquifer unit and (2) periodic recharge events on groundwater flow and
contaminant transport within the aquifer system. On the basis of these findings
Argonne instituted a program of extended monitoring and hydraulic testing of the
Bruno aquifer system to address these uncertainties with the EPA's approval.
The results of the extended monitoring and hydraulic testing program were reported
by Argonne in the their April 1998 study, prepared for the CCC/USDA. These
studies documented that the hydrogeologic properties of the middle silt aquifer unit
vary both vertically and laterally across the Bruno contamination site, and that
these variations strongly control the movement of contaminated groundwater
within and through the aquifer system in the vicinity of the Bruno Co-op.
Response: The data collected during the extended monitoring program conducted
by USDA and the models presented in USDA's September 1995 and April 1998
studies have been reviewed by EPA. The new study does not significantly change
the previous understanding of the subsurface of the Bruno site. EPA will add
USDA's September 1995 study to the Administrative Record File. (The April 1998
study is already included in the Administrative Record File.)
<
14) Comment: Revised groundwater flow and contaminant transport models
incorporating these data (USOA's April 1998 study) were devaloped for the site by
Argonna. These models demonstrate that the contaminated groundwater within
the middle silt unit is relatively immobile and will be impossible to effectively
remediate by using conventional or innovative technologies such as horizontal
extraction wells or in-well vapor stripping technologies.
Response: Even though significant efforts have been exerted in preparation of the
models, we feel that the revised model has not significantly decreased the
uncertainties which existed in the initial model. EPA believes that USDA's model
has not been sufficiently tested and calibrated to be used as proof that remediation
of the middle silty layer is impossible (For instance the model has not been
calibrated to USDA's own pump test data). The most significant factors causing
uncertainty include: 1) the hydraulic interaction between the upper sand and middle
silt units and between the middle silt and lower sand units, 2) the variability of
hydraulic conductivity in the middle silt. The model parameter with the most
uncertainty which has the most significant impact on remediation simulations
effectiveness in the middle silt unit are the hydraulic interaction values assigned to
the top and bottom of layers representing the middle silty layer. Sufficient testing
has not been performed to prove that the middle silty layer is hydraulically isolated
from the upper and lower sand layers. In fact, the most reliable pump test
Bruno Co-op Site ._ Record of Decision
42
-------
performed-at the site, pump test #3 (USDA's interim study, Argonne, September
1995) indicates that there is good hydraulic connection between the upper and
lower sand layers.
Based on current data, it is not sufficiently demonstrated that remediation of the
middle silty layer is "impossible". Review of the grain size analysis data presented
in USOA's April 1998 study prepared by Argonne indicates that, in general, the
middle silty layer contains more silt than the upper sand and the lower sand layers;
however, the middle silty layer is actually fairly sandy with many samples from this
layer containing greater than 50 percent sand. Additionally, samples collected from
this layer generally contain only a very small percentage of clay. The grain size
data indicates that, in general, the middle silty layer can be expected to be fairly
permeable with only small portions of this unit being clay rich and impermeable. If
the grain size data is representative of the middle silt unit then it is reasonable to
anticipate that the preferred alternative presented in the Proposed Plan will achieve
PRGs.
15) Comment: In reviewing the EPA's Superfund Proposed Plan, Argonne can find
no technical justification for the EPA's assertion that proposed Remedial Alternative
3, employing four fully penetrating groundwater extraction wells pumping at a
combined flow of 200 gpm, will be capable of reducing carbon tetrachloride
concentrations within the aquifer system to the specified PRG of 5 ppb within 18
years of operations.
Response: As discussed above, it is premature to accept the model results as proof
that the middle silty layer is impossible to be remediated as was concluded in
USDA's April 1998 study (Argonne 1998). In fact, data presented in USDA's
September 1995 interim study suggests that the middle silt should be capable of
remediation. Data suggesting this includes, the grain size data collected from the
middle silty layer indicates that a good deal of the middle silty layer contains
significant percentages of sand. Additionally, pump test f 3 (Argonne 1995) proves
that (at least in some locations) there is good hydraulic connection between the
upper and lower sand units suggesting that the middle silt unit is not a hydraulic
barrier between the upper and lower sand units. Because remediation of the middle
silty layer may be possible, an alternative was selected that included remediation of
this layer as a goal. The EPA proposes to evaluate the .progress of the system and
take a look at the effectiveness of the remedy every two years after system
operation begins.
16) Comment: The EPA states in its Proposed Plan that "the modeling of
groundwater contamination described within the FS report was performed by
Argonne, and by Black & Veatch, an EPA contractor," and that "the analysis of
Bruno Co-op Silt Record of Decision
. 43
-------
remedial alternatives within the FS report, and their conceptual design cost
estimates were performed by Black & Veatch." These statements imply that only
one Feasibility Study report, that generated by BVSPC (July 1998), was considered
directly by the EPA in its analysis of remedial alternatives.
Response: EPA considers the Feasibility Study report it issued in July 1998 as the
Feasibility Study for the Site under the NCR. However, EPA considered each report
prepared by USDA carefully and has placed or will place the pertinent documents in
the Administrative Record File.
17) Comment: Appendix A of the EPA Feasibility Study (July 1998) prepared by
BVSPC states that the preliminary groundwater flow and solute transport models
presented by Argonne in the USDA's interim study (September 1995) were
recreated by Black & Veatch and used without modification for Black & Veatch's
evaluation of remedial options. Argonne specifically concluded that these
preliminary hydrogeologic models could not be used to perform a quantitative
evaluation of remedial needs or alternatives for the Bruno site. Argonne can find no
evidence that BVSPC or the EPA incorporated any of the data obtained from
Argonne's extended monitoring program or USDA's/Argonne's April 1998 study in
their modeling of the remedial alternatives.
Response: Black & Veatch recreated the earlier modeling effort and reviewed the
later ones. Based on this work, EPA concluded that data and models presented in
USDA's April 1998 study did not significantly alter the previous understanding of
the subsurface conditions. Review showed that sufficient hydraulic testing
combined with extensive calibration of the updated model has not been performed
that would adequately support Argonne's view, which is that the model results
show that the middle silty layer will not respond to a pump-and-treat remedial
system. EPA believes that Argonne's preliminary model and their updated model,
as applied, have significant uncertainties regarding the analysis of the effectiveness
of remedial pump and treat.
18) Comment: BVSPC provided no documentation supporting their modeling of
remedial options in EPA's Feasibility Study (July 1998) that would permit a critical
enalysis by Argonne and the CCC/USDA of this activity and the resulting
conclusions. BVSPC cited the supporting document titled Draft Data Evaluation
and Environmental Fate and Transport Modeling, Technical Memorandum (March
1997); this report has not been made available to Argonne or the CCC/USDA for
review and was not placed in the administrative record by the EPA.
Response: The March 1997 document mentioned in the comment will be placed in
the Administrative Record File.
Bruno Co-op Site . . Record of Decision
44
-------
19) Comment: Argonne employed two distinctly different, alternative
hydrogeologic models of the middle silt aquifer unit in considering each
groundwater flow and contaminant transport scenario addressed for the Bruno
aquifer system in USDA's interim study (September 1995), reflecting Argonne's
uncertainty (at that time) about the detailed character of the middle silt unit.
BVSPC provided no indication of which (if in fact either) of these aquifer system
models was adopted by BVSPC for its analysis of remedial options, or the
justification for this model selection.
Response: the 4 leyer model in USDA's September 1995 study was reproduced by
Black & Veatch. USDA in this and subsequent reports, developed three
groundwater models of the Bruno site. In EPA's evaluation of those modeling runs,
we found that they provide a somewhat more detailed picture of the aquifer, but no
significant additional knowledge was gained regarding groundwater behavior. In
particular, no significant additional information was gained concerning the
practicability of remediating the middle silty layer.
20) Comment: The EPA indicated that their preferred remedial alternative should
employ four wells that are "fully screened from the top of the upper sand unit to
the base of the lower sand unit." This scenario cannot be simulated by using the
groundwater modeling software indicated (MODFLOW), without a prior assigning of
a specific groundwater extraction rate to each aquifer zone (model layer) at the
location of each well. BVSPC provided no information on how modeled
groundwater extraction rates were apportioned to the individual aquifer units in
their simulations. To achieve predetermined flow rates from the individual aquifer
units in the actual aquifer system, a cluster of multiple wells, screened at different
depths, would be required at each location in lieu of the single fully screened well
called for in the Proposed Plan, increasing both the complexity and costs of the
proposed extraction system.
Response: The BVSPC model simulated pumping 50 percent of the volume from the
upper sand layer and 50 percent of the volume from the lower sand layer at each
well location. The number of wells, their design, and pumping rates presented in
the Feasibility Study is e conceptual design for use in the Feasibility Study phase of
this project. The Remedial Design will need to include performance of a pump test
and reevaluation of the number of extraction wells, extraction rates, and their
design.
21) Comment: Appendix A of EPA's July 1998 Feasibility Study states that
modeling of the preferred four-well extraction system "predicts that this pumping
scenario will decrease the concentration of contaminants within the upper and
lower sand units to the cleanup goal of 5 ppb in 18 years." Elsewhere within this
Bruno Co-op Site . _ Record of Decision
45
-------
report and the Proposed Plan, rt is stated that this alternative would achieve
remediation of the aquifer within 18 years. Argonne has modeled the four-well
extraction scenario proposed by EPA, requiring eight wells to achieve a flow rate of
25 gpm each from the upper and lower sands at the proposed well locations and
using the-updated aquifer system models presented in Argonne's April 1998 study.
The results of this simulation indicate that the EPA's preferred Alternative 3 will not
achieve the stated cleanup goal of 5 ppb within the upper sand unit after 60 years
of continuous pumping or within the middle silt unit after 100 years of continuous
pumping.
Response: It is EPA's cleanup goal to contain the spread of the contaminant plume
and to actively restore the contaminated aquifer to its use as a source of drinking
water. Multiple model runs were performed to determine the number of wells, their
locations and pump rates to restore all layers of the aquifer to drinking water
standards. It is understood that different values assigned to model parameters will
significantly impact model predictions. The four-well and 200-gallon per minute
pump rate are a result of modeling and could be modified as more information on
the aquifer is gathered during design investigations. EPA acknowledges that
achievement of MCL concentrations in the groundwater is not a certainty using the
modeled recommended alternative. Furthermore, during active restoration,
groundwater sampling and treatment system monitoring is to be performed to
evaluate the performance and effectiveness of the extraction system in each aquifer
layer. Decisions regarding the effectiveness of the extraction system will be based
on actual data accumulated over time, and not just on model predictions. System
performance reports will be prepared every two years and system adjustments or
improvements or other changes will be considered on a regular basis to improve
system effectiveness and efficiency.
22) Comment: The NCP specifies that the EPA is expected to return groundwater
to their beneficial uses wherever practicable within a time frame that is reasonable
given the particular circumstances of the site. When restoration of groundwater to
beneficial uses is not practicable, the EPA is expected to prevent further migration
of the plume, prevent exposure to the contaminated groundwater, and evaluate
further risk reduction.
The NCP states that during the Feasibility Study the EPA is to establish PRGs, or
acceptable exposure levels that are protective of human health and the
environment. In establishing PRGs, the EPA is to consider applicable or relevant
and appropriate requirements and other factors to determine acceptable exposure
levels. These preliminary goals are to be modified "as more information becomes
available during the Remedial Investigation/Feasibility Study (RI/FS)." Therefore,
Bmno Coop Site Record of Decision
-------
we request that the EPA Proposed Plan specifically address how these goals will be
met or modify them on the basis of the additional significant information not used
in setting the PRGs.
Response: The EPA does not view the data collected as part of USDA's extended
monitoring program or the additional modeling results as "significant" information
which proves that remediation of the middle silty layer is impossible. The grain size
data indicates that a good percentage of the middle unit should be fairly amenable
to pump-and-treat remediation and pump test #3 (referenced above) indicates that
the middle silt unit is not hydraulically isolated from the upper and lower sand units
(at least in some locations). Therefore, it is premature to assume that it is
impossible to remediate the middle silty layer.
23) Comment: The NCP requires the EPA to evaluate each alternative to
determine such factors as effectiveness, technical feasibility, and cost in achieving
the PRGs. Neither the EPA's Proposed Plan nor its Feasibility Study indicates how
any of identified alternatives will effectively address remediation of the middle silt
unit.
Response: EPA acknowledges that there is uncertainty about whether hydraulic
properties of the middle silty layer could inhibit the success of the proposed
alternative; however, EPA is not convinced that it is impossible to remediate the
middle silty layer. The final design should take into account all data currently
known regarding the subsurface. During operation of the system, groundwater
sampling will be performed to evaluate the performance and effectiveness of the
extraction system in each aquifer layer. Decisions regarding the effectiveness of
the extraction system will be based on field data from active remediation pumping
and not on model predictions alone.
24) Comment: The NCP provides that alternatives determined to be technically or
administratively infeasible may be eliminated from further consideration. It states
that "the alternatives shall be assessed to determine whether they attain applicable
or relevant and appropriate requirements under federal environmental laws and
state environmental or facility siting laws or provide grounds for invoking one of the
waivers under paragraph (f)(1)(ii)(C) of the section." One of the grounds under
which the EPA may invoke a waiver is that "compliance with the requirement is
technically impracticable from an engineering perspective."
USDA requested that the EPA issue modified PRGs that are protective of human
health and the environment and are technically feasible, as specified in CERCLA
Section 121 and the NCP. In addition, the NCP provides EPA with additional
authority in selecting an alternative when other circumstances besides technical
Bruno Co-op Site Record of Decision
47
-------
impracticability apply, as in cases where "compliance with such requirement at the
facility will result in greater risk to human health and the environment than
alternative options." This provision may apply to the Bruno site because as is
indicated on page 5-17 of USOA's April 1998 study, the modeling of direct
extraction of the middle silt unit demonstrated that increased contamination of the
upper sand unit would result. The NCP also states that the EPA is expected to use
treatment wherever practicable and where contaminants are highly mobile. As has
been stated in this document and the April 1998 USOA study, the contamination in
the middle silt unit is not highly mobile.
Response: It has not been demonstrated that it is technically impracticable to
remediate the middle silty layer, and therefore modification of the PRGs is not
warranted. The observations discussed on page 5-17 of USOA's April 1998 study
regarding the predicted increase in contamination in the upper sand caused by
pumping of the middle silty layar is not sufficient to show pumping in the middle
silty layer causes greater risk. This observation is unexplained in USDA's April
1998 study and seems infeasible. It may also show that pumping in the middle silt
will mobilize contaminants into the more conductive zones of the aquifer where the
contaminants can be more readily removed from the aquifer. EPA's preferred
alternative pumps from all three aquifer layers and not just form the middle silty
layer. Contaminants drawn into the upper and lower sands by pumping would be
extracted by the wells pumping in those layers.
25) Comment: The cost comparisons provided in the EPA's Feasibility Study do
not specifically provide the detailed breakdown needed to determine their accuracy.
Therefore, please provide a more detailed itemized accounting of these costs
particularly for Alternative 3. -On the basis of previous experience with the
Waverly, Nebraska, site we believe that the estimated costs of implementation are
underestimated.
Response: A detailed breakdown of the costs for the alternatives presented in the
Feasibility Study (BVSPC 1998) are provided in Appendix C of the report. The cost
estimates provided are within the + 50/-30 range dictated by RI/FS guidance, and
are fairly detailed.
26) Comment: We find that the Remedial Action Objectives (RAOs) in the
Proposed Plan are not consistent with the PRGs cited in the EPA's Feasibility Study.
The PRGs in the Proposed Plan indicate that the EPA considers a cleanup that
would restore the ground water to drinking water quality. The RAOs in the EPA's
Feasibility Study state an objective of preventing ingestion of groundwater that
exceeds MCLs. The EPA needs to explain the inconsistencies between these two
very different objectives.
Brnno Coop She Record of Decision
-------
Response: There is no inconsistency between the RAOs described in the Feasibility
Study and .the Proposed Plan. The RAOs in the FS are to prevent ingestion,
inhalation, or direct contact with groundwater having concentrations of the
chemicals of concern above current regulatory drinking water standards. MCLs are
specifically identified in the FS as regulatory standards which were carried forward
as PRGs in the Proposed Plan. Also, the Village's continued use of Supply Well
#65-1 during times of scarcity indicates that the use of the aquifer as a drinking
water source continues and the lack of institutional controls that would prevent the
drilling of new wells both make MCLs appropriate standards for the aquifer.
27) Comment: The EPA stated in the Proposed Plan that it evaluated USDA's April
1998 submitted on behalf of CCC/USOA. The Proposed Plan briefly describes the
CCC/USDA's proposed alternative and says that it would include six extraction
wells pumping the aquifer for two years at a rate of 150 gpm. After two years of
treating the hot spots of the aquifer this alternative would provide for natural
attenuation of the lower concentrations remaining in the aquifer. The EPA then
stated in its Proposed Plan that itsj>olicy on natural attenuation is that "it should
normally be used in conjunction with or to supplement active remediation
measures. For example, natural attenuation could be employed in lower
concentration areas of the dissolved plume and as a follow-up to active remediation
in areas of higher concentration." This example is a totally accurate description of
the CCC/USDA proposed alternative. Please indicate how the EPA has determined
that our proposed alternative is not consistent with this EPA policy.
Response; Presently, although USDA has done much work at the Site, there has
been no evaluation to determine if the rate of natural attenuation at the site is
sufficient to accomplish remedial action objectives. The efficiency of the natural
attenuation rate of the contaminants of concern is accomplished by evaluating the
biogeochemical system of the site. EPA suggested to USDA (correspondence dated
April 11,1997) to include biogeochemical parameters to their monitoring program
to allow evaluation of the efficiency of the site's natural attenuation rate. USDA
declined the suggestion (correspondence dated June 17, 1997). Until the site's
natural attenuation rate can be substantiated, natural attenuation can not be
included as part of the selected remedy.
28) Comment: The EPA Feasibility Study provides no risk evaluation for the
different remedial alternatives. This is not consistent with the EPA's guidance in
RAGS, Volume I, Parts A and C. The Proposed Plan does not indicate how the
middle silt unit will be cleaned of contaminant to a level below the MCL, but the
middle silt unit was used in the baseline risk assessment as a potential source of
Bruno Coop She _ Record of Decision
-------
contaminated water. As a result, if the middle silt is not actually to be cleaned a
risk assessment of the residual contamination should be performed. Please provide
this risk analysis for the alternatives.
Response: As described previously, it has not been demonstrated that remediation
of the middle silty layer is unlikely. Therefore, part of the remediation goal is
restoration of the middle silty layer. As part of the Nine-Criteria analysis in the FS,
EPA has examined possible risks posed by any of the evaluated alternatives, EPA
normally develops remediation goals based on existing site risks and has followed
the guidance cited in this comment. Under the NCR, MCLs promulgated under the
Safe Drinking Water Act are to be relevant and appropriate in most instances as
cleanup levels for drinking water aquifers.
29) Comment: Calculated models for pumping of public well 65-1 to supplement
the water supply of the community demonstrate that this activity can be
undertaken now in a safe manner. Please detail why EPA chose to ignore this
possibility.
Response: Well 65-1 has been shown to be contaminated in the past. It is
unreasonable to believe that the model can sufficiently demonstrate that no
contaminants will enter public well 65-1 in the future. The ROD includes treatment
to allow utilization of Well 65-1 as a backup supply for the Village of Bruno.
Bruno Co-op Site _ _ R*eori or Decision
5O
-------
4
a
f.
OMM
5!
t i SOURCEl MM
rn cr««« e
FIGURE 1
-------
FORMER MUNICIPAL HELL
TO OAVIO CITY
TOMN
BOUNDARY
TRIBUTARY TO
SKULL CREEK
/
TO ABIE
BRUNO CO-OP SITE/FORMER
ORAIN STORACE ^^
FORMER MUNICIPAL NELL 65-1
5
i
i
I
I"
h
SOURCEi ATSOR
Principal residential area
1200'
1200'
FIGURE 2
SITE MAP
BRUNO CO-OP sir
-------
FIGURE 3
SAMPLING LOCATK
rn-np <;ITF
-------
*•»•••• 1 i •> MWMBi «•»•• CBVM< Milt
IHM I.I •!•*•«. «•*•!• *.t. II
.it'll it.M.H c<« tut W. MMWM
HAOI
sail
SOURCEi MRCONNE
160
BRUNO
FIGURE 4
SOIL SAMPLE RESULTS
CARBON TETRACHLORIOC
BRUNO CO-OP SITC
-------
I
5
HSi
O CRT
PUKJCWEU.
* TISTWEa
SOU BORING
• pOMESTCWCU
• CPT/PIE2DMETER
SB30
(M-290)
Cartoon Tttrachtoridc
in tfi« Upf^r Sand Un*
BRUNO
CONCENTRATIONS
FIGURE 5
ARCAL EXTENT Of CARBON
TETRACHLORIDE IN THE
UPPER SANO UNIT
BRUNO CO-OP SITE
-------
9
I
I:
!o
PUBUCWEU.
* TESTWELL
• DOMESTIC WEU.
• CnVPlQOMETER
Carton T0trachlorid«
in the Middle Sift Unit
BRUNO
CONCDrHRATIONS
f ! SOURCE i MOOMC
FIGURE 6
AREAL EXTENT OF CARBON
TETRACHLORIOE IN THE
MIDDLE SILT UNIT
BRUNO CO-OP SITE
-------
9
I
i
Carbon Tetrachloride
in the Lower Sand Unit eil_ •
5814 ,
A
A 90ILIOANQ
• OOMESneWELL
• CPT/PIEZOMETEM
BRUNO
!H
3
Jl?
12
CONCOTTRATIONS
^^w^»%pf» I
AREAL EXTENT OF CARBO
TETRACHLORIOE IN THE
LONER SAND UNIT
-------
O CPT
• PUBUCWELL
* TESTWELL
A aOILIOMNQ
• OOMESTtCWILL
• CPT/PIEZOMETCR
SBU
Chloroform in tht
Upper Sand Unit
,15
xs
it
CONCENTRATIONS
SOURCES ARCOMC
FIGURE 8
AREAL EXTENT OF CHLOROFORM
IN THE UPPER SAND UNIT
BRUNO CO-OP SITE
-------
O CPT
PUIUCWEU.
fcTEITWEU.
AKX.KMNO
• cxsuemcwtu.
• CPT/PlEZOUETm
Chloroform in tht
Middle Silt Unit
BRUNO
& on
CONCENTRATIONS
h
m
FIGURE 9
AREAL EXTENT OF CHLOROFORM
IN THE MIDDLE SILT UNIT
-------
9
I:
;;|
In
O CPT
• PUBLIC WELL
* TEITWEU.
• OOUitncWBI
CPTWEZDMETDI
(NO)
S890
«P"Sb
Chloroform in tn« 881
Lower Sand Unit (
SB»
(NO-M)
SBO»
llJ
;!•'
ilfi
FtCURC 10
AREAL EXTENT OF CHLOROFORM
IN THE LONER SAND UNIT
BRUNO CO-OP SITE
-------
i:
,1
it
Lrerun
* CXICTINB HUNIT«lHB
PUBLIC MA1CA
HfS-KI. CXTCHI or CMtMN
IE1HACH.ORIK. CM.OKOFCMM CM
1.2-OCA IN OmuMMftlOl »T
CtMCCHtMTIONS MOVC
•PCOMIIOH OOM.fi
300* ISO1
300'
it
-------
Table 1
Present Worth Cost Analysis
Selected Alternative (Alternative 3)
Bruno Co-op Site
lost Estimate Component
CAPITAL COSTS
Extraction Wells (4, 8* PVC wells instilled to
a drain of 105 ft)
3 HP Submersible Pump (wire flow ad
control devices)
Groundwitcr Collection Double Cnntimmnit
Piping (2' inside 4* PVC installed, includes
bedding and trenching)
Jroundwiier Collection Double Containment
Piping (4* inside 6* PVC installed, includes
tedding and trenching)
Chain-Link Fencing (6 ft high)
Swing Gate (6 ft high. 12 ft opening)
Concrete Well Vaults
Prefabricated Structure
Purchased Packaged (Air Stripper)
Other Direct Costs for Packaged System
ftscharge Piping to Drainage Ditc i (6* PVC
installed, includes bedding and trenching)
Monitoring Wells (2 sets of 3, 2' PVC wells
installed to depths of 45. 75. and 105 ft)
Treatabiliry Study
DIRECT CAPITAL COST SUBTOTAL
Bid Contingency (15%)
Scope Contingency ( 1 5 %)
TOTAL DIRECT CAPITAL COST
Permitting and Legal (5%)
Construction Services (10%)
CONSTRUCTION COSTS TOTAL
Engineering Design (8%)
"OTAL CAPITAL COST
ANNUAL OAM (,U»ia
Electrical Costs (483 KWh/day)
Groundwater Monitoring (Analysis only)
Year!
Monthly sampling of 19 monitoring wells
for CC14, CHC13 and U-DCA (standard
turnaround)
Years 2 through 6
Quarterly sampling of 1 9 monitoring
wells for CC14. CHC13 and U-DCA
(stdufd tunufouod)
Years 7 through 18
Semi-annual sampling of 19 monitoring
wells for CC14, CHC13 and 1 ,2-DCA
(standard turnaround)
Quantity
420
4
380
990
L_ 6°
1
4
1
1
1
200
450
1
176300
228
76
38
Units
VLK
EA
LF
LF
LF
EA
EA
EA
IS
LS
u
VLF
LS
KWh
EA
EA
EA
Unit Cost
$60
$3,500
$21.84
S33.43
$13.53
$400
$1,100
$2,000
$36.600
$90,036
$12
S25
$30,000
$0.08
$100
$100
$100
Capital Cost
$25.200
$14,000
$8,300
$33,100
$800
$400
$4,400
$2,000
$36,600
$90.000
K400
$11300
$30,000
$258.500
$38,800
$38.800
$336.100
$16.800
$33.600
$386,500
$30.900
$417,400
Annual Cost
$14.100
$22.800
$7,600
$3.800
-------
Table 1 (Continued)
Present Worth Cost Analysis
Selected Alternative (Alternative 3)
Bruno Co-op Site
Cost Estimate Component
Quantity
Units
Unit Cost Cipilal Cost Annual Cost i
Groundwater Monitoring (Labor only) i
Year I
2 Level PI penons for 2-8 hour days per
sampling event
Yean 2 through 6
2 Level PI persons for 2-8 hour dayi per
sampling event
Yean 7 through 18
2 Level PI persons for 2-8 hour days per
sampliDB event
Treatment Plant Effluent Monitoring (Monthly
monitoring for CC13. CHC14, and 1 ,2-DCA,
standard turnaround)
Preparation of Health and Safety Plan (Year 1
onrv)
Preparation of 0AM Manual (Year 1 only)
Preparation of Q A/Sampling Plan (Year 1
only)
Five- Year Review @ 5, 10, and 1 5 yn
Maintenance Allowance ( 1 2% of purchased
eauipmenl delivered)
Operator Requirement (2 hour/day)
384
128
64
12
40
80
60
1
1
730
HR
HR
HR
EA
HR
HR
HR
IS
LS
HR
$60
$60
$60
$100
$60
$60
$60
$15,000
$4.392
$25
TOTAL PRESENT WORTH O&M COST
TOTAL PRESENT WORTH
$639,600
$1.057,000
$23.000
$7.700
$3.800
$uoo
$2.400
$4.8001
$3.600
$15.000
$4.400
$18.3001
I
5 percent discount rate used to calculate present worth.
-------
Table 1 (Continued)
Present Worth Cost Analysis
Selected Alternative (Alternative 3)
Bruno Co-op Site
Year
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
Yearly O&M
Cost*
$38,000
$38,000
$38,000
$38,000
$38,000
$38.000
$38,000
$38,000
$38,000
$38,000
$38,000
$38,000
$38,000
$38,000
$38,000
$38,000
$38,000
$38,000
Intermittent
O&M Costs
$56.600
$15,300
$15,300
$15.300
$30.300
$1 5.300
$7,600
$7,600
$7,600
$22,600
$7,600
$7,600
$7,600
$7,600
$22,600
$7,600
$7,600
$7,600
Present Worth of Annual O&M
Total Annual
O&M Costs
$94,600
$53,300
$53.300
$53,300
$68,300
$53.300
$45,600
$45,600
$45,600
$60,600
$45,600
$45.600
$45.600
$45.600
$60,600
$45,600
$45,600
$45.600
$639,638
Intermittent O&M Costs Include:
Year 1 (plans and monitoring)
Years 2-6
Yean 2-6
Years 2-6
Yean 2-6 and 5 yr review
Yean 2-6
Yean 7-18
Yean 7-1 8
Yean 7-1 8
Years 7-18 and 5 yr review
Yean 7-1 8
Yean 7-1 8
Yean 7-1 8
Yean 7-1 8
Yean 7-18 and 5 yr review
Yean 7-1 8
Yean 7-1 8
Yean 7-1 8
* Yearly O&M costs include: electricity, treatment plant effluent monitoring,
maintenance, and operator.
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Table 2
Cost for well abandonment of well 36-1 and the Treatment of well 65-1
Bruno Co-op Site
Bruno, Nebraska
Capital Coats
TWO 2,000 to Cartoon Vessels
20X20 Ft Bunding
Wafl Abandonment
ShlDDtao
Total Capital coats
$42,000
$33,000
$5,000
$2,000
182,000
Oparatlon & Malnt
Monthly Sampling
Annual Regeneration of Carton
Biannual backwashino of carbon unto
150
12
Annual O&M CO
$1,800
$0,000
Assumptions:
1) Well will need to be used In winter months. Thus, a heated building la necessary.
Building is on concrete slab, heated, and Is a wood frame construction.
2) Monthly aempflng end analytical work will be necessary to Insure breakthrough Is not
Occurring.
3) Regeneration end disposal of old carbon will be performed annually.
4) City employees will perform general operation and maintenance of system including
sampling end backwashlng.
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