EPA Superfund
Record of Decision:
PB95-964302
EPA/ROD/R07-95/078
March 1995
Tenth Street Site
Columbus, NE
2/23/1995
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RECORD OF DECISION (ROD)
1.
DECLARATION
SITE NAME AND LOCATION
Tenth Street site
Columbus, Nebraska
STATEMENT OF BASIS AND PURPOSE
This decision document (ROD) presents the remedial action
selected for the Tenth Street Site in Columbus, Nebraska. The
remedial action was selected in accordance with the comprehensive
Environmental Response, Compensation and Liability Act of 1980
(GERCLA), as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), 42 U.S.C. 99601 et'sea. and
to the extent practicable, with the National oil and Hazardous
Substances Pollution contingency Plan (NCP), 40 C.F.R. Part 300.
This decision was based upon the documents and information
contained in the Administrative Record for the site. A copy of
the Administrative Record is available for public review at the
Columbus Public Library and at the u.S. Environmental Protection
Agency (EPA) Regional Office located at 726 Minnesota Avenue in
Kansas City, Kansas.
. .
. . .
The S~ate of Nebraska has been consulted with and concurs on
the alternative selected as the remedial action for this site.
ASSESSMENT OF THE SITE
The EPA conducted a baseline risk assessment of the site
which is contained in the Remedial Investigation Report. This
assessment concluded that actual or threatened. releases of
hazardous substances from this site, if not addressed by the
implementation of the response action selected in this ROD, may
present a current or potential threat to human health, welfare or
the environment.
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2
DESCRIPTION OF THE SELECTED REMEDY
The selected remedy is ground water monitoring and
institutional controls with a contingency for extraction of
contaminated ground water and discharge to the Loup River. The
contingency portion of this remedy was included in the Proposed
Plan as a separate remedial alternative (G-3). EPA's
implementation of the contingency will be depend upon the results
of EPA's reassessment of its baseline risk assessment. At a
minimum, EPA will evaluate whether or not the risks calculated in
the baseline risk assessment may have changed, warranting the
implementation of the contingency, first after one year of ground
water monitoring and again after five years of monitoring. The
institutional controls. include:
-advisories from EPA to users of private wells in areas of
contaminated ground water which would be likely to produce
contaminated ground water, recommending that such ground water
not be used for human consumption; and
-requesting that the City of Columbus pass an ordinance
prohibiting the drilling of any new private water supply wells in
the area of ground water contamination.
The implementation of the contingency will depend upon the
results of an EPA reassessment of its baseline risk assessment,
which is contained in the remedial investigation found. in the
administrative record for this site.
Both G-2 (Institutional Controls and Ground Water
Monitoring) and G-3 (Ground Water Extraction for Discharge) were
among the six remedial alternatives evaluated by EPA in the
Feasibility Study (FS) and presented to the public in the
Proposed Plan EPA issued. However, neither G-2 nor G-3 were the.
remedial alternative recommended by EPA in the Proposed Plan.
New data and information received since the release of the
Proposed Plan prompted EPA to select an alternative other than.
the alternative (G-5: New Municipal Drinking Water supply and the
Collection of Contaminated Ground Water for Treatment or
Discharge) recommended in the Proposed Plan. Nevertheless, both
G-2 and G-3 were elements of G-5.
DECLARATION
The selected remedial action is protective of human health,
welfare and the environment, attains Federal and State applicable
or relevant and appropriate requirements (ARARs) for the remedial
action selected, and provides for a cost-effective response.
This remedy utilizes permanent solutions and alternative
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3
treatment technologies to the maximum extent practicable for this
site. However, treatment of the contaminated ground water is not
necessary at this time to provide protection of human health,
welfare and the environment, to comply with ARARs or to achieve
long-term protectiveness or permanence. Therefore, treatment is
not a principal element of the remedy selected. However,
treatment might be used pursuant to the contingency, if it were
determined that treatment is necessary to meet the requirements
for discharges to the Loup River.
Since this remedial action will result in hazardous
substances remaining onsite above levels that allow for unlimit~d
use and unrestricted exposure, pursuant to section 121(c) of
SARA, EPA will review the continued protectiveness no less than
once every five years after the selection of this remedial
action. At five years EPA will also reassess whether the
contingency for ground water extraction should be triggered if
such extraction has not already begun.
&J~3('7S
Date
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Attachments:
Glossary of Remedial Alternative Evaluation criteria
Decision Summary
Responsiveness Summary
Transcripts of the Two Public Meetings
Index to Administrative Record
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RECORD OF DECISION (ROD)
Tenth Street Site
Columbus, Nebraska
Prepared by:
u.s. Environmental Protection Agency (EPA)/Region VII
Kansas city, Kansas
February 1995
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I.
II.
5
DECLARATION
ROD TABLE OF CONTENTS
DECISION SUMMARY
1.0 SITE BACKGROUND
1.1 Site Location and Description
1.2 Site History and Enforcement Activities
1.3 History of Community Participation
2.0
3.0
SCOPE AND ROLE OF THE REMEDIAL RESPONSE AND SUMMARY OF
SITE CHARACTERISTICS
2.1 Contaminants of Concern and ExPosure Pathways
2.2 Site' Setting and Hydrogeology
SUMMARY OF SITE RISKS
3.1 Definition of the Reasonable Maximum Exposure (RME)
3.2 Noncarcinogenic Risks for the RME
3.3 Carcinogenic Risks for the RME
3.4 Environmental Risk
3,5 Risk-Related Need for Remedial Actions
3.6 Preliminary Remedial Goals or Cleanup Levels
4.0,
SU~Y OF REMEDIAL ALTERNATIVES
4.1 No-Action, G-1 ' ,
4.2 Monitoring and Institutional Controls, G-2
4.3 Extract Contaminated Ground Water and Discharge to
the Loup River, G-3
4.4 Extract Contaminated Ground Water, Treat Water to
Remove Contaminants,' and Send Treated Water for Use
to Municipal Drinking Water Supply, G-4
4.5 Relocation of Municipal Well Field with Collection
of Contaminated Ground Water, with Institutional
Controls, G-5 '
4.6 Relocation of Municipal Well Field with
Institutional Controls, G-6
5.0
EVALUATION OF ALTERNATIVES
5.1 Overall Protection of Human Health and Environment
5.2 Compliance with ARARs
5.3 Long-Term Effectiveness and Permanence
5.4 Reduction of Toxicity, Mobility and Volume through
Treatment
5.5 Short-Term Effectiveness
5.6 Implementability
5.7 Cost
5.8 State Acceptance
5.9 Community Acceptance
6.0 SUMMARY OF THE SELECTED ALTERNATIVE
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6
7.0
STATUTORY DETERMINATIONS
7.1 Protection of Human Health and the Environment
7.2 Compliance with Applicable or Relevant and
Appropriate Requirements (ARARs)
7.3 Cost-Effectiveness
7.4 Utilization of Permanent Solutions and Alternative
Treatment (or Resource Recovery) Technologies to
the Maximum Extent Practicable
7.5 Preference for Treatment as a Principal Element
8.0
DOCUMENTATION OF SIGNIFIC~T CHANGES
III. RESPONSIVENESS SUMMARY
Figures
Figure 1,
Figure 2A,
Figure 2B,
Figure 2C,
Municipal
Figure 3A,
Figure 3B,
Figure 3C,
Site Location Map
TCE/PCE Concentrations in A
TCE/PCE Concentrations in B
TCE/PCE Concentrations in C
Wells
TCE/PCE
TCE/PCE
TCE/PCE
(Monitoring) Wells
(Monitoring) Wells
(Monitoring) and
Ground Water Contamination, "A" Wells
Ground Water Contamination, "B" Wells
Ground Water Contamination, "C" Wells
Tables
Table I, Maximum Concentrations of Soil Contamination
Table II, Maximum Levels of Contamination in city Drinking
Water Wells and in Monitoring Wells .
Table III, Ground Water Contaminant Data (rounds of samples,
2 during RI/FS, 2 rounds after RI/FS)
Table IV, 1994 Analytical Data on Municipal Drinking
Water Wells
Table V, Hazard Indices Calculated (Noncarcinogenic Risk)
Table VI, Population .Total ~xcess Cancer Risks
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7
II.
DECISION SUMMARY
.1.0 SITE BACKGROUND
1.1 Site Locati.on and Description
The Tenth Street Site is located in the south-central
portion of the City of Columbus, Nebraska. Columbus is located
in east-central Nebraska. The site is defined as those municipal
drinking water wells which contain, or have contained, volatile
organic contaminants (VQCs), mainly trichloroethylene (TCE) and
tetrachloroethylene (PCE), and certain areas containing VQC- .
contaminated soil, which might be a source of the ground water
contamination. (See Figure 1.) Current land uses at the site
include mostly occupied, single~family residences, although some
commercial facilities (retail stores and businesses) and some
light industry are also found at the site, as well as schools,
parks, a cemetery and churches.
1.2 Site History and Enforcement Activities
The Tenth Street Site was proposed for the National
Priorities List (NPL) in 1989 after VQCs, including PCE and TCE,
were found in the water from some of the municipal drinking water
wells and in water from the municipal drinking water distribution
system.. The site was known as the .IIColumbus Water Supply" site
when it was proposed for the NPL and when EPA officially listed
the site on the NPL in August 1990. EPA now refers to the site
as the "Tenth Street Site." Some documents in the Administrative
Record use the earlier site name.
A site investigation was performed for EPA by a contractor
beginning in 1988. As part of this investigation, soil gas
samples were collected and analyz~d to define the extent of
ground water contamination and locate potential contaminant
sources. The soil gas samples were collected by drilling.
temporary borings from which borehole air samples were collected
for analysis. A cone penetrometer investigation was performed as
part of the RI, during which temporary borings were drilled from
which water samples were collected for chemical analysis.
Data from the soil gas samples and the cone penetrometer
samples were used as a guide for locating monitoring wells in the
remedial investigation (RI) to identify potential contaminant
sources to be investigated. A copy of the site investigation
report, including the soil gas work, is included in the
Administrative Record. The cone penetrometer data is included in
the RI Report.
A remedial investigation/feasibility study (RI/FS) was
conducted by a separate EPA contractor from 1990 through 1992.
In a RI/FS, the extent of contamination is determined in the RI,
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8
and options for site cleanup are evaluated in the FS. During tpe
RI, a series of fifteen shallow, fifteen intermediate and four
deep monitoring wells were installed. The shallow monitoring
wells, which are designated "A" wells in the RI, were screened
(the part of a well through which ground water enters the well)
from 23.5 to 28.5 feet below ground surface. The intermediate
wells, which were designated "B" wells in the RI, were screened
from 64 to 76.5 feet below ground surface. The deep wells, which
were designated "C" wells in the RI, were screened from 105 to
128 feet below ground surface.
Two' sets of ground water samples were collected and analyzed
from each monitoring well during the RI. Some soil samples were
collected for chemical analysis as the monitoring wells were
being drilled. ..
As part of the RI, water samples from the municipal drinking
water supply wells and from the municipal drinking water
distribution system were collected for chemical analysis. A
preliminary ground water pump test was conducted to gather
additional hydrogeologic data on the site. Surface water and
sediment samples were collected for chemical analysis from the
Loup River, at both up and downstream locations from where
surface water runoff from the site enters the river. Finally,
surface and near. surface soil samples were collected for chemical
analysis from potential contaminant source areas. .
The RI includes a baseline risk assessment, in which
potential threats to human health, posed by the release and
threat of release of hazardous substances from the site, are
assessed. Environmental threats are addressed in the ecological
assessment, which is. part of the baseline risk assessment.
EPA has not conclusively identified the source of the
contamination during its investigations of the site. Therefore,
no potentially responsible parties (PRPs) have been identified,
.and the RI/FS was financed by EPA using the Hazardous Substances
Trust Fund as a "fund-lead" activity. EFA continues its efforts
to identify the source{s)of the contamination.
1.3 History of Community Participation
The RI/FS and the Proposed Plan were released to the public
in April 1993. These documents were made available for comment
in the Administrative Record, which is located at both the EPA
Region VII Office in Kansas City, Kansas and at the Columbus
Public Library. A notice on the availability of those documents
was published in the Columbus Teleqram which also opened a public
comment period on April 26, 1993. Originally the comment period
was to close on May 26, 1993, but EPA extended the public comment
period until July 2, 1993 at the request of the public.
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Tenth Street Site, Columbus, Nebraska
Record of Decision, October 1994
Fi gu re 1.
10th
STREET SITE
COLUMBUS. NEBRASKA
rup
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CORPO"AfION
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9
A public meeting was held on the Proposed Plan on May 18,
1993 in Columbus. At the request or the public, a second public
meeting was held on June 16, 1993 in columbus. Representatives
of EPA provided an overview of the site and' an explanation of the
remedial alternative recommended in the Proposed Plan during the
public meetings. Representatives or EPA, the Nebraska Department
of Environmental Quality (NDEQ) , the Nebraska Department of
Health (NDOH), and the City of Columbus were available at the
public meetings to answer questions from the public. An
availability session was held in Columbus on December 7, 1993 to
allow members of the public to .ask EPA questions about the site.
A response to the written comments received during the
extended public comment period and the comments provided during
the public meetings is included in the Responsiveness Summary,
which is Section III of this ROD.
2.0 SCOPE AND ROLE OF THE REMEDIAL RESPONSE ACTION AND SUMMARY OF
SITE CHARACTERISTICS
2.1 Contaminants of Concern and' Exposure Pathways
The alternative selected as the remedial action for this
site addresses the risks associated with the consumption of, and
exposure to, the VOC-contaminated water. If necessary, such
. contaminated ground water shall be collected under the
contingency identified in this ROD, thereby preventing further
environmental contamination and the associated risk to human
health and the environment.
The nature and the extent of contamination at this site are
more completely described in the RI report. In summary, some
surface and near surface soils are contaminated with VOCs and
with polynuclear aromatic hydrocarbons (PARs). PARs result from
the combus~ion or burning of hydrocarbons including those from
automobile engines, power plan~s and many other $ources. .Table I
summarizes the maximum levels of soil contamination at the site.
The ground water samples did not contain detectable
concentrations of PARs. Some of the VOC ground water
contamination may have resulted from the leaching of contaminants
in the soil contamination above.
The most significant problem at the site is VOC
contamination of the ground water and the municipal drinking
water wells. The extent of TCE and PCE ground water
contamination found during the RI is shown in Figures 2A, 2B and
2C. Table II summarizes the contamination found during the RI in
the city drinking water supply wells and in the monitoring wells.
Table III shows contaminants concentrations in monitoring wells
before and after the Proposed Plan was released. Table IV
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Tenth Street Site, Columbus, Nebraska
Table I, MaximUm Concentrations of
Soil Contamination
(1 of 3 pages)
CHEMICALS OF POTENTIAL CONCERN
SOn..s UNITS: ug/kg
Sample Area Libeny Cleaners Jackson Services
Sample Medium Soil Soil
Detected Detected
Chemical Concentration Sample Concentration Sample
1 , 1 , I-Trichloroethane 10 SB-l1 u -
1 ,2-Dichloroethane u - u -
1 ,2-Dichloroethene u - u -
AcetOne u - u -
Bromodichloromethane I u - I u I -
Bromoform I u - u -
Carbon disulfide u - I u -
Chloroform u - u -
Dibromochloromethane u - u " -
Tetrachloroethene 181-24,000 SB-l1 13-90 SB-S
Trichloroethene 27 SB-11 u -
Xylene. tOtal 10 SB-13 u -
Benzo(a)anthracene 750-930 SB-17 u -
Benzo(a)pyrene 820-930 SB-17 u -
Benzo(b )fl\,loranthene 910 SB-17 ,u -
Benzo(k)fluoranthene 820-1800 SB-l1 u -
Chrysene 880-11 00 . SB-ll u -
Fluoranthene 890-1900 SB-1S u -
Phenanthrene 1000-1300 SB-15 u -
Pyrene 980-1500 SB.-15 u -
Bis(2-ethylhexyl)phthalate 3100 SB-19 u -
Di-N-octyl phthalate 620 SB-ll u -
Diethylphthalate 700-780 SB-14 520 SB-S
1~'I/I'I1,I.I.£I]
Tenth Street Site, Columbus, Nebraska
Record of Decision, October 1994
Table .z Page 1
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(2 of 3 pages)
CHEMICALS OF POTENTIAL CONCERN
SOILS UNITS: ug/kg
Aluminum 190-20.000 5B-16 11 QO-4800 SB-4
Arsenic 2.4J-2oo SB-8 3.0-4.9J SB-S
Barium 81-430 SB-13 89-210 SB-S
Cadmium 1.6-5.4 SB-18 u -
Lead 5.85-810 SB-18 7.5J-190 SB-5
Nickel 9.4-34 SB-15 9.3 SB-S
Silver u - u I -
Vanadium 9.8-31 SB-15 11-19 SB-4
Tenth Street Site, Columbus, Nebraska
Table I, MaximUm Concentrations of
Soil Contamination
Sample Area Village Wash House Former Grain EevatOr
Sample Medium Soil Soil
. Detected Detected
Chemical Concentration Sample Concentration Sample
1,1,1-1rrichlo~dtane u - u -
1,2 - Dichlo~thane u - u -
1,2 - Dichloroethene u - u -
Aceume 14J SB-2 u -
Bromodichloromethane u - . u -
Bromoform u - 90 SB-6
Carbon Disulfide u - u -
Chloroform u - u -
Dibromochloromethane u - u -
Tetrachloroethene u - u -
.trichloroethene u - u -
Xylene. total u - u -
Benzo(a)anthracene u - u -
Benzo(b )fluoranthene u - u -
ICIIUo2l111R1,,1oI .£13
Tenth Street Site, Columbus, Nebraska
Record of Decision, October 1994
Table .z. Page 2
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(3 of 3 pages)
CHEMICALS OF POTENTIAL CONCERN
SOILS UNITS: ugikg
Benzo(k)fluoranthene u I .. u I -
Chrysene u I - 1100 SB-6-
Fluoranthene u I - 2100 I SB-6
Phenanthrene u - 1500 SB-6
Pyrene u - 1900 SB-6
Bis(2 -ethy lhexyl )phthalate u I - u -
Di-N-ocryl phthalate u - u I -
Diethylphthalate 480-790 I SB-2 u I -
Aluminum 390-4600 SB-3 3800-8500 I SB-7
Arsenic 2.8 I SB-2 3.3-9.3 SB-7
Barium 110-120 SB-2 120-210 SB-7
Cadmium u - u -
Lead 0.63J-461 SB-2 6.41-3801 SB-7'
Nickel u - u -
Silver u - u -
Vanadium u .. 11-18 SB-7
Tenth Street Site, Columbus, Nebraska
Table I, Maxi.nnJm Concent~ations of
Soil Contaminat10n
- No sample
u Not detected
, JEstimated concentration
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Tenth Street ~i~e, Columbus, Nebra~l~
Record of DeC1s10n, October 1994 ~.
Table X Page 3
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Record of Decision. October 19911
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Tenth Street Site, Columbus, Nebraska
Record of Decision, October 1994
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ater Wells & Monitoring Well~
(1 of 2 pages)
CHEMICALS OF POTENTIAL CONCERN
GROUNDW ATER UNITS: ugil
Sampie Area City Wells Monitoring Wells
Sampie Medium Groundwater Groundwater
I Detected Detected
Chemical Concentration Sample Concentration Sam1'le
1 , 1 , I-Trichloroethane u - u .
1,2- Dichloroethane 1.5] W-4 1.7 MW.12B
1,2-Dichloroethcne 1.5-2.7 W-4 1.5-7.7 MW.9A
AcetOne I 13] I W.12A I u -
Bromodichloromethane I 191-20 I W-12A 4.1 I MW-3A
Bromofonn u I - 3.9 MW.3A
Carbon disulfide I u - u -
Chlorofonn 18-220 W.12A 19 MW.3A
Dibromochloromethane 121 W.12A 7.1 MW.3A
TetraChioroethcne 1.6-61 W~8 1.4-130 MW.9A
Trichloroethene 1.6-15 W.l 1.2-120 MW.9A
Xylene. total u - u .
Benzo( a)anthracene u - u -
Benzo(a)pyrene u - u -
Benzo(b )f1uoranthene u - u -
Benzo(k)f1uoranthene u - u .
Chrysene u - u -
Fluoranthene u - u .
Phenanthrene u - u -
Pyrene u - u .
Bis(2 -ethylhexyi)phthaiate u - u -
Di-N-octyl phthalate u - u .
Diethylphthalate u - u -
Tenth Street Site, Columbus, Nebraska
Table II, Maximum Concentrations of
Contamination in City Drinkin~
W
II8tWII.1R1.oo1.z.EU
Tenth Street Site, Columbus, Nebraska
Record of Decision, October 1994
Table ~
Page 1
-------
ater e 5 . om. tonng e E
(2 of 2 Dages)
CHEMICALS OF POTENTIAL CONCERN
GROUNDW A TER UNITS: ugll
Aluminum I 11-450 I MW-6C
Arsenic 11-12 I W-4 10-200 I MW-6A
Barium I 220-410 W-l 240-710 MW-13C
Cadmium u - 18 MW-llB
Lead 4.2 W-l 3.0-30 MW-3B
Nickel u - u -
Silver u - u -
Vanadium I u I - u I -
Tenth Street Site, Columbus, Nebraska
Table II, Maximum Concentrations of
Contamination in City Drinkin~
W Wll &M' . Wll
- No sample
u Not detected
J Estimated concentration
U8621IIIftL,I.W3
Tenth Street Site, Columbus Nebraska
Record of Decision, October'1994
Table zr. Page 2
. J
-------
10TH STREET SITE
Data Summary, 1st 4 Rounds of Samples
(TCE) Round (PCE) Round
1 2 3 4 1 . 2 3 4
1A NO NO 2.7 3.0 27 72 7.8 6.0
18 NO NO NO :0\: NO NO NO *
2A NO NO NO NO/NO NO NO 1.5 6.0/6.0
28 NO NO 1.2 2.0 NO NO 5.2 18
3A NO NO NO NO NO NO ND NO
38 NO NO NO NO NO NO ND NO
3C 6 '5.9 * * NO NO * *
4A NO 1':0 NO NO NO NO NO no
48 NO NO NO NO :10 NO ND NO
5A NO NO NO NO no NO 2.9 10
58 NO NO NO NO/NO NO NO NO 3.0/3.0
6A 8 9.2 2.7 2.0 12 15 NO 5.0
68 NO 22 1.7 NO/NO rID 45 3.2 rID/NO
6C NO NO NO NO NO NO NO NO
7A' NO rm NO, NO NO NO NO NO
. .
78 NO NO NO NO NO NO NO NO
SA 5 1.6 1.3 1.0/1.0 10 3.3 1.2 1.0/1.0
S8 NO 2.0 NO NO NO 1.4 NO NO
9A 24 120 12 16 38 130 5.9 6.0
98 44 55 1.3 1.0/2.0 3S 64 NO NO/NO
( 43') ,( 54 . ) 36') (63'
lOA NO 57 NO NO NO 72 NO NO
10B .S 1.2 8.5 5.0 NO NO NO 2.0
l1A 7 4.2 NO 1.0 12 9.3 1.5 ';.0
IlB NO 2.7 1.6 2.0 NO NO NO NO
12A NO NO NO NO NO NO NO NO
12B NO NO NO NO NO NO NO NO
13A NO NO NO NO/NO NO NO NO NO/NO
13B NO NO NO * NO NO NO *
13C 5' 9.9 NO NO 5 NO NO NO
14A NO NO 1.2 2.0 NO NO NO NO
14B NO 1.9 4.0 8.0 NO NO NO 3.0
14C NO NO NO * 1m NO NO *
-Continued on page 2-
Tenth Street Site, Columbus, Nebraska
Record of Decision, October 1994
Table £Zr.J ~J -e /
-------
-2nd of 2 pages-
TCE
PCE
15A
15B
NO
NO
2.6
NO
ND
NO
NO
*
NO
NO
NO
.NO
NO
NO
NO
*
Monitoring well data only.
All data in micrograms/liter (ug/l).
ND- 'not detected. (Detection limits and
provided in this summary table.)
*- no sample.
A- Duplicate sample analytical data.
data qualifying codes not
Tenth Street Site, Columbus, Nebraska
Record of Decision, October 1994
Table l1Z.1 riSe .2.
-------
10
summarizes contaminant concentrations in the municipal drinking
water wells from the most recent data available to EPA.
Neither surface water nor sediments in the Loup River had
higher levels of contamination downstream from the site compared
to upstream. Therefore, no significant surface water
contamination is attributed to the site. No air samples have
been collected at the site. EPA determined that such air
sampling was not necessary because there are no suspected sources
of significant air contamination at the site.
There is a great deal of uncertainty associated with the
levels of arsenic found in some of the surface soil and some
shallow ground.water. There are no suspected sources of arsenic
releases at or near the site. Although certain soil and shallow
ground water samples had higher levels of arsenic than other
samples at the site, EPA suspects that even the highest levels of
arsenic are within the range of naturally-occurring background.
Arsenic was not found above the MCL in any of the wells which
continue to be used for municipal drinking water. The maximum
levels of arsenic found in the soil and ground and drinking water
at the site are shown in the above Tables I and II.
If EPA determines that ground water extraction is warranted,
EPA will reevaluate whether arsenic. is present above background
. concentrations, thus constituting a release from the site.
2.2 Site Setting and Hydrogeology
The primary problem at this site is the VQC contamination of
the municipal drinking water wells. Therefore, the focus of the
RIfFS was on ground water contamination and on addressing the
safety of the water supply.
The site is underlain by unconsolidated sand, silt and
gravel (alluvium), which were deposited above. bedrock by the
river and glacial activities. These deposits comprise the
aquifer or aquifers which provide drinking water for the City of
Columbus. A sandy shale bedrock underlies the alluvium, but the
alluvium contains the usable aquifers at and near the site.
The site and most of Columbus is very flat. Surface water
runoff from the site flows toward the Loup River, which is about
1.2 miles south of the site and flows to the east. In the RI,
ground water depth varied from 15 to 20 feet below the surface at
the site. There appear to be three significant water-bearing
(hydrogeologic) units in the alluvium. The deepest of these
units has the greatest yield or water-bearing capacity from which
most of the municipal drinking water in Columbus is obtained.
Based upon the information and data gathered during the RI,
the three hydrogeologic units may have some hydraulic connection
-------
Jack Daniel of NDOH called on 7/7/94 and proVided the folloWing analytical
results from ,water samples collected at Columbus on 6/23/94:
Well # 1 TCE 1.8 ~g/l
PCE < detection limit
Well # 2 TCE 6.8 ~g/l
PeE 2.2 ~g/l
Well # 4 TCE 5.2 J,Lg/1
PeE 0.8 ~g/l
Well # 8 TCE no detect
. PCE no detect
Well # 12 (pOint of entry) TCE no detect
PCE 0.7 ~g/l
Well # 13 TCE no detect
PCE no detect
Treatment plant (point of entry) TCE 3.0 ~g/l
PCE < . detection liri11t
Jacks summary was that water in the dlstlibution system 15 meeting the
drinking water standards for TeE and PCE.
"f?~4/ '
Ralph Langemeier X 7367
Tenth Street Site, Columbus, Nebraska
. Record of Decision, October 1994
Table I V .
-------
11
.
and may act as a single aquifer. However, these units are to
some degree separated by low permeability soils, such as silts
and clays. It is possible that, at least for portions of the
site, .these units may not be hydraulically .connected and may be
separate aquifers. The hydrogeology described is shown in
Figures 3A and 3B, which are excerpted from the RI report.
Alluvial aquifers beneath the site are not under. artesian
(greater than atmospheric) pressure, and any vertical ground
water flow appears to be downward from the upper units. The
regional horizontal direction of ground water flow in the
columbus area would normally (if not altered by the pumping.of
the municipal wells near the site described below) be toward the
southeast, toward. the Loup River. Alluvial ground water usually
discharges into the Loup River., except during flooding or periods
of high river water, when ground water will temporarily flow from
the river back into the alluvial aquifer(s) .
The pumping of the existing municipal drinking water wells
has altered this pattern within their area of hydraulic
influence. Because these wells withdraw large v.olumes of water,
ground water within a certain radius flows in their direction.
Therefore, ground water flow direction in portions of the site is
toward the southwest. The direction of ground water flow would
revert to the regional direction if pumping of the existing water
supp~y wells was discontinued. . .
3.0 SUMMARY OF SITE RISKS
EPA prepared a baseline risk assessment and an ecological
assessment, using the data collected during the RI, as well as
the other data and information available on this site. The
baseline risk assessment and the ecological assessment were
prepared as part of the RI and a~e found in the RI report.
Superfund remedial actions can be undertaken. to address any.
of three types of risk: carcinogenic risk to human health,
noncarcinogenic risk to human health, and environmental risk.
In general, Region VII requires or undertakes remedial
actions for Superfund sites when the cumulative lifetime risk of
getting cancer as a result of reasonable maximum exposures (RME)
to the contamination released from the site exceeds 1E-4 (an
increase of one in ten thousand, or 1/10,000).
Remedial actions may .also be undertaken or required under
superfund when a hazard index (HI) of 1.0 or greater is
calculated for a RME. The HI is a numeric expression of the
noncarcinogenic risk to human health calculated for a RME to the
releases from the site. An HI of less than 1.0 indicates that
adverse, noncarcinogenic effects on human health, including
sensitive subpopulations, are not expected.
-------
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Tenth Street Site, Co~umbus, Nebraska
Record of Decision, February 1995
Figure 3A
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Tenth Street Site, Columbus, Nebraska
Record of Decision. February 1995
Figure 3B
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Record of Decision. February 1995 .
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-------
12
Finally, Superfund remedial actions may be undertaken or
required if there is potentially significant ecological or
environmental risk from the releases at the site.
3.1 Definition of the Reasonable Maximum Exposure (RNE)
The baseline risk assessment concluded that, based upon
current information and data, the site does not pose a
potentially significant threat to the environment. The baseline
risk assessment therefore focused on the carcinogenic and
noncarcinogenic risk to human health, which could result from
both current and future land uses and exposures at the site.
Pursuant to the National Contingency Plan (NCP) [40 C.F.R.
Section 300.430(d) (4), Section 300.430(e) (2) and the preamble],'
EPA determines whether or not Superfund remedial actions are
required for a site based upon the human health risk for a
reasonable maximum exposure (RME). Reasonable maximum exposures
generally include not only current exposures given existing land
uses, but also exposures which might reasonably be predicted
based upon expected or logical future land uses. The RME for
this site includes certain exposures which may not currently
exist. EPA believes such exposures are reasonable and may occur.
EPA assumes that the RME will include the 'consumption and
use, (i.e. showering and other household uses) of shallow ground
water containing VOC concentrations equivalent to those in
monitoring well MW9A, which had the highest levels of '
contamination among the wells sampled. Only the data available
before the Proposed Plan was released to calculate intakes. Data
from two samples from MW9C after the RI, which had lower levels
of contamination than during the RIfFS, were not used in
calculating these intakes, because EPA was not sure that the drop
in ground water contaminant levels was permanent. Therefore, the
baseline risk assessment may overstate the risk associated with
the consumption of ground water, if the data collected by the two
samples after the release of the Proposed Plan is representative
of current ground water quality at the site.
EPA has no information that anyone in Columbus drinks ground
water solely from the most shallow unit, from which MW9A draws
water. However, it is reasonable to assume that such exposures
could occur in the future, since if not contaminated, the ground
water is drinkable in quality. By assuming the consumption of
water with the contaminant concentrations of MW9A, the RME would
include exposures to VOCs and to arsenic via the oral route. The
RME also includes additional exposures to household water,
primarily to VOCs in the water, through the dermal route when
showering or bathing or other uses, and through inhalation, again
mainly when showering. For the carcinogenic risk, all exposures
in all potentially complete routes of exposure are added to
calculate the cumulative carcinogenic risk for the RME. .
-------
13
3.2 Noncarcinogenic Risks for the RME
Were it not for the arsenic HQs (hazard quotients, which are
calculated for individual chemicals and then added to calculate
the HI), no HIs would exceed 1.0. When the noncarcinogenic risk
of arsenic is included, HIs for both adult RME and child
exposures exceed 1.0 (7.0 and 10.0 respectively). Table V is
excerpted from the baseline risk assessment and shows the HIs.
3.3 Carcinogenic Risk for the RME
When EPA released the Proposed Plan in April 1993, the
cumulative carcinogenic risk for the RME was 1E-3 (an increase of
one in one-thousand, or 1/1000, for a RME lifetime risk of
. cancer). Excess cancer risks for an RME were presented in Table
5-2 in the Baseline Risk Assessment and are. included as Table VI
in this ROD. Although the risk calculated was related to future
uses, it is nonetheless sufficient to warrant remedial actions to
address such risk. It should also be noted that this risk
included exposures to arsenic, and arsenic may actually not be
present above background concentrations.
Certain developments since EPA released its Proposed Plan in
April 1993 need to be noted. First, on July 7, 1993, a
determination was made by the Nebraska Department. of Health
(NDOH) that the City of Columbus' drinking water supply was in.'
compliance with the Safe Drinking Water Act (SDWA). Previous to
that, the City of Columbus was subject to an administrative order
signed by the NDOH ordering the city to comply with the Nebraska
and federal Safe Drinking Water Acts. The city's system has
remained in compliance since July 1993.
Further, two sets of samples collected by EPA in July and
December of 1993 after the Proposed Plan was issued show that the
levels of groundwater contamination are not as high as they were
in the samples collected by EPA in the RI/FS before release of
the Proposed Plan. Maximum TCE/PCE concentrations in the ground
water in the two rounds of samples collected in the RI/FS before
the Proposed Plan were 88 and 130 ug/l. The maximum
concentrations of TCE and PCE in the two sets of samples
collected in 1993 after the release of the Proposed Plan were 16
and 10 ug/l and are shown in the previously referenced Table III.
As a contingency in the remedial action selected in this
ROD, EPA will reassess its baseline risk assessment after one
year and again after five years of ground water monitoring, using
future levels of ground water contamination and other relevant
factors to determine whether or not ground water extraction may
be required at some point in the future. EPA will seek to
implement this contingency as part of this remedial action if the
carcinogenic risk for a reasonable maximum exposure (RME) to
releases from the site cause an increase in background of 1E-4
-------
Tenth Street Site, Columbus, Nebraska
Table V, Hazard Indices Calculated
Noncarcinogenic Risk SUHHARY OF HOHCANCER IIAZARD QUOT I EHTS FOR ADULTS
(l of 2 pages)
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Tenth Street Site, Columbus. Nebraska
Record of Decision, October 1994
Table ~ v; Page 1
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Tenth [;treet [;ite, Collunb1ls, Nehraskfl
Table V, lIazardJndices Calculated
Noncarcinogenic Risk . SUMMARY OF NONCANCER IIAZARD QUOTI ENTS FOR CHILDREN
(2 of 2 pages)
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'oneoCo."rono 01.00 01'00 01.00 01'00 OUOO 0[.00 n-n ... ",
'eneaCbl'luor.nthen. ol,ao OltOO OltOO 01.00 01'00 01.00 n-n ",, ",
'eneoC."luar.n.hon. 01.00 Olt DO 01.00 OltOO 01'00 0[.00 n-OJ "" '"
Che,..n. 01.00 OE.OO OltOO 01.00 OltOO 01'00 JI-n ", "'
UI Fluoranthono OltOO OltOO 01:.00 01.00 OUOO OlJ DO U-n "A "'
I 'hononthe.n. OE.OO OltOO 01:.00 U'OO OEIOO 01,00 JI-n IIA IIA
"
'rea..o 01'00 01'00 01:'00 01'00 ouoo Oft 00 n-os IIA II"
.IIC2-oth,lho.rl.phthola.. 21-02 41;-0. 2£-OZ 11-01 2£,02 4[-04 U-u IE-04 "'
DI-n-oct,. phthalot. 2[-02 'I-n 21-02 'I-OS 2£-02 IE-OS )E-OI SI-U IIA
Dle.h,lphthalat. 4I;-n 11-0' II-OS '1-04 41-0) 1£-01 'E-OJ II-OJ IIA
AI-In... "" "" III IIA NA IIA II,. IIA
"r e.nlc ,~r.;." lE-OJ !f'I\' 2[-02 1(.00 41-01 2[.OU IIA
.ul~ Jt-Ol IE-o) '11-01 II-OJ II-ul 2£-0) I£-u;' IIA
C.d",l..... "' IIA "" "" IIA "' IIA IIA
lud IIA IIA IIA N" NA IIA IIA IIA
II I clla I 61-02 ZE-OI 6£-02 2£-OJ 6[-Oi n-OJ IE-U ",
51"'ae 11-01 JI-U 11-01 '1-06 11-01 '1-04 SE-OJ IIA
IIo..adl- U-OI' 11;-0' n-ol 11-02 U-OI 11-01 JI-Ol H"
PATII"'. TO'Al HI. 4tt~O . 2E-OZ IE-OJ IJ;tOI 4[-.02 21-01 . 4[,0'0 2[-0' IE-OI ntOO ~E-04 6E-OJ
(',d'. To, 0"'"
CU, W8.01f1 II.GO
110" ., litO'
110" ., 'ItOO
loll. IEtOO
Tenth Street Site, Columbus, Nebraska
Recbrd~bf:Decision. October 1994
I.' iii . 1101 ..aluat.d duo 10 lack o. ..0 oe I.ck o' conc.nte.tlon ..,I..to.
(., ..t calcula,.d -
Ie, Iu. e' oeol, d.rmol. and Inhaletlon pothva,a
Table' V
)
Page 2
~
~
~
~
!ii
~
~
-------
£jfr Sgs/cIHs'lnc.
POPU~;TION TOTAL EXCESS CANCE,R RISKS
Lifetime
PODulation EXDosure Medi'.:.:n Excess Risk
Current City City water 1£-04
Residenc
Current Resident at City wacer U:-04
Liberty Cleaners Soil 1£-04
Total 2£-04
Future Resident at ''':ell water ($1 9A) 1£-03
Monitoring well 9
Future Resident at \.:ell water (MW lA) 3£-04
Liberty Cleaners Soil 1E-04
Total 4E-04
Future Resident at o":ell water (MW 9A) 1E-03
Liberty Cleaners Soil ~
Total 1£-03
Tenth Street Site, Columbus, Nebraska
Record of Decision, October 1994
Table v J
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14
(one in ten thousand or more) or if a hazard index of 1.0 is
calculated for a RME to releases from the site.
3.4 Environmental Risk
The environmental impact of the releases of hazardous
substances from the Tenth Street Site were assessed in the
ecological assessment, which is part of the baseline risk
assessment. These releases do not appear to present a
significant threat to the environment.
3.5 Risk-Related Need for Remedial Actions
When the Proposed Plan was released, the cumulative lifetime
carcinogenic risk calculated for the RME in the baseline risk
assessment was 1E-3 (one in one-thousand, or 1/1000) which is
sUfficiently high to warrant remedial actions to address such
risk at this site. It should be noted that the calculation of
this risk included some future exposure scenarios, which do not
currently exist and as well as exposures to arsenic. Arsenic may
not be present in soil or ground water at the site at
concentrations above natural background for the area. Also, the
contaminant concentrations in ground water in the two rounds of
samples collected by EPA in 1993 were lower than the two rounds
of ground water samples collected during the RI/FS. Nonetheless
EPA' does not feel that the trend of contaminant concentrations 'in
ground water was sufficiently clear to warrant revising the
baseline risk assessment conducted in the RIfFS at this time.
Table V is excerpted from the RI/FS and shows the excess cancer
risk for various exposure scenarios including the RME.
The actual or threatened releases of hazardous substances'
from this site, if not addressed by the preferred alternative, or
other remedial alternatives, may present a potential threat to
public health, welfare and the environment. It should be noted
that the risk calculated for reasonable maximum exposures assumes
certain exposures may occur in the future which do not currently.
exist. Furthermore, the remedial action selected in this .ROD
(institutional controls and monitoring with a contingency for
ground water collection, effectively reduces this risk and
protects human health, even in the future use scenarios.
since the release of the Proposed Plan, it has been
determined that the municipal water supply is in compliance with
the Safe Drinking Water Act (SDWA). This means that water from
this supply has not exceeded the SDWA's maximum contaminant
levels (MCLs) for the chemicals of concern (TCE and PCE) at this
site. The municipal water supplies continues to be in compliance
with the SDWA.
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15
3.6 Preliminary Remedial Goals or Cleanup Levels
Pursuant to the NCP and Part B of Volume I of the Human
Health Evaluation Manual (OSWER Directive 9285-7-01B, December
13, 1991), EPA established preliminary remedial (cleanup) goals.
EPA's maximum contaminant levels (MCLs) from the Safe Drinking
Water Act (SDWA) for public water supplies and the state of
Nebraska's Title 118 Standards for ground water protection are
identified as applicable or relevant and appropriate requirements
(ARARs). For the contaminants at this site, these standards are
identical, except that the State of Nebraska has not yet
identified a Title 118 Standard for 1,1,2-trichloroethane.
MCLs and state Title 118 Ground Water Qual~ty Standards and
Use Classification are ARARs in the manner described below. The
ground water monitoring and institutional controls selected as
the remedial action for this site shall be continued so long as
an average of the contaminant concentrations from the monitoring
wells sampled show consistent contamination above the concentra-
tions listed below. Also, if ground water is extracted under the
contingency identified in this remedial action, such extraction
would continue so long as the average contaminant level from the
wells pumped or sampled exceeds the levels identified below.
Safe Drinking Water Act MCLs and Title 118 Concentrations
70
100
5.0
5.0
1000
200
5.0
5.0
2.0
50
ug/l
ug/l
ug/l
ug/l
ug/l
ug/l
ug/l
ug/l
ug/l
ug/l
ciS-1,2-dichloroethylene
trans-1,2-dichloroethylene
1,2-dichloroethane
tetrachloroethylene
toluene .
1, 1, I-trichloroethane
l,l,2-trichloroethane (not a Title 118 Standard)
trichloroethylene.
vinyl chloride
arsenic
The compliance of public water supplies with the Safe
Drinking. Water Act when monitoring is conducted more frequently
than annually is determined by a running annual average of all
samples taken at each sampling point. If the annual average of
any sampling point is greater than the MCL, then the system is
out of compliance. In the calculation of such averages, samples
in which contaminants with MCLs are not detected are assumed to
have a value of zero (as opposed to one half the detection limit,
which is the general rule .for a Superfund risk assessment). '.
4 . 0 SUMMARY OF REMEDIAL ALTERNATIVES
The remedial action alternatives evaluated in detail in the
FS are described below. The engineering and treatment
components, estimated costs, and ARARs for each alternative are
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16
discussed. A more detailed description of each alternative is
presented in the FS. For the purposes of comparing costs, a
30-year period of operation was assumed for all of the
alternatives, although for some alternatives the operation may be
more or less than 30 years. Cost estimates are considered
accurate within a range of ~30% to +50%.
4.1 No Action, G-l
The NCP requires EPA to consider a no action alternative as
a benchmark against which other alternatives can be compared.
Under this option, no remedial actions, including no additional
monitoring or institutional controls, would be implemented to
reduce risks from exposures to releases from the site. The only
monitoring conducted would be that already being provided by the
city and the state for the municipal drinking water supply in
compliance with the Safe Drinking Water Act.
Since some of the water used by the city for municipal
drinking water has had levels of contamination above the MCLs,
alternative G-1 is not considered protective of human health and
is retained only ,to serve as a basis for comparison purposes.
There would be no monetary costs associated with this
alternative. 'However, EPA'would conduct 5-year reviews pursuant
to Section' 121(c) of CERCLA, as it would for all of the other
alternatives evaluated. '
4.2 Monitoring and Institutional Controls, G-2
Under this alternative, no construction activities would be
undertaken unless EPA determined that additional monitoring wells
were required. Institutional controls would be used to limit
human exposure to contaminants in the ground water.
Institutional controls would include:
~advisories from EPA to users of private wells producing
contaminated ground water recommending that such ground water not
be used for human consumption, and
-requesting the city of Columbus to pass an ordinance
prohibiting the drilling any new private wells in the area of
contamination.
The extent and migration of ground water contamination would
be monitored by collecting and analyzing water samples from
existing monitoring wells at the site. Some samples might also
be collected from the municipal water supply wells, although that
system is regularly monitored by the city and the state.
The identity of the wells to be used for monitoring and the
sampling frequency would be determined after consulting with the
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17
city to obtain a more complete understanding of the city's
current and projected pumping of these wells. Additional
monitoring wells might also be recommended as a result of .
remedial design and are included in the cost estimate for this
alternative. EPA estimates the present worth value of this
remedy to be approximately $465,505.
4.3 Extract contaminated Ground Water and Discharge Water to the
Loup River, G-3
Under this alternative, contaminated ground water would be
extracted from several extraction wells which would be installed
as part of the remedial action. Currently unused municipal
drinking water supply wells could also be used for extraction.
Up to ten extraction wells could be necessary. However, the
specific number, location and size of such extraction wells would
not be determined until remedial design and would depend upon the
extent of ground water contamination which triggers EPA's
implementation of the ground water extraction contingency
identified in this ROD.
The ground water ~xtracted would be discharged, via a ditch
or a storm sewer, to the Loup River. No ground water collection
or discharge would take place under low or no-flow conditions for
the Loup River. Available data indicate that the collected
ground water requires no pretreatment prior to discharge.
However, EPA would have confirmed that water quality standards
for the Loup River would not have been violated as a result of
the discharge of contaminated ground water as part of this
remedial action during remedial design before discharging water
on a continuing basis.
Long-term ground water mon{toring would be required to
monitor the effectiveness of this alternative. Some existing
monitoring wells, some e~isting municipal drinking water supply
. wells and some of the new extraction wells might have been used
for such monitoring. Samples of water from the municipal water
supply well water and from the distribution system would also be
required to monitor contaminant levels in the water supply.
The present worth value of this alternative is estimated to
be $1,131,155.
4.4 Extract Contaminated Ground Water, T~eat Water to Remove the
contaminants and Send Treated Water for Use to the Municipal
Drinking Water supply, G-4
Under
MCLs would
remove the
would have
this alternative, ground water contaminated above the
have been extracted and treated in an air stripper to
contaminants from the water. No new extraction wells
been required under G-4. .
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18
Contaminants would have been removed from the ground water
in an air stripper, which transfers contaminants from the water
into the air by mixing the water and air. Available data
indicate that the off-gas from the air stripper would not require
any further treatment. However, EPA would have confirmed this
during remedial design before implementing air stripping on a
continuing basis.. .
Treated water would have been piped from the air stripper
via a water transfer line to the municipal drinking water plant
for distribution and consumption or use. A new water transfer
line from the. air stripper to the municipal drinking water plant
would have been required.
The objectives of this alternative would have been to ensure
a safe municipal drinking water supply and to contain the ground
water contamination. A safe water supply would have been ensured
by continuously monitoring the discharge of water from the air
stripper. Also, the discharge from the drinking water
treatment/distribution plant would have been continuously
monitored with automatic shut-offs if contaminant concentrations
in the water exceeded MCLs.
Ground water contamination would have been contained by
inducing a hydraulic gradient back toward the pumping/withdrawal
.wells. . Contaminants would thus have been pulled back toward such
wells unless the contaminant plume were already beyond the
hydraulic influence of the extraction wells. In that case, EPA
would have considered the need for additional pumping wells to
achieve adequate containment. In order to minimize the waste of
water under this alternative, the water extracted and treated
would have been used as drinking water.
The institutional controls contained in alternative G-2 were
recommended for alternative G-4 as well. The institutional
controls would have remained in effect until ground water
contamiriation was reduced to health-based levels. The present
worth value of this alternative, including operation, maintenance
and monitoring is estimated to be about $1,697,859.
4.5, Relocation of Municipal Well Field with Collection of
Existing Ground Water contamination, and with Institutional
Controls, G-S
Under this alternative, a new well field would have been
installed to provide municipal drinking water. ~hose existing
municipal drinking water wells which consistently had
contamination above the MCLs would have been taken out of.use and
abandoned, unless it was determined to use them for monitoring or
as a source of fire-fighting water. Abandoned wells would have
been plugged in accordance with state requirements.
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19
Water from the new well field would have been piped to a
central treatment facility for chlorination and fluoridation and
stored in the existing 3,000,000 gallon storage tank at the new
well field. Finished water would then have been piped via a new
transmission line to the existing water distribution system at
Third Avenue and Highway 30. Water from the new well field would
have been blended with water from those wells in the existing
well field which would continue to supply drinking water. The
blended water would then have been distributed for domestic and
other uses to residences and other water users in Columbus.
For the purpose of estimating the cost of this alternative,
EPA assumed that existing drinking water supply wells Wl, W4,
W10, and W1l would be taken out of service, and that wells W2,'
wa, W12, W13, Wl4, and W15 would continue to be used. However,
the issue of which wells would have been used to continue to
supply drinking water would have been reevaluated during remedial
design using the most current data and would also have been
reevaluated periodically during operation.
As with G-3, contaminated ground water would have been
extracted and discharged to the Loup River under G-5 to expedite
the removal of contaminants from the ground water and to restore
the ground water to its highest potential beneficial uses. This
would also have reduced the risk to users of ground water other
.than through the municipal water supply (i. e. private wells).
As with G-3, pretreatment of the extracted ground water
prior to discharge to the Loup River appears unnecessary, since
state Water Quality Standards for the Loup River should not be
exceeded, based upon existing data. As with G-3, ground water
collected under this alternative would not have been discharged
to the Loup River during low or no-flow conditions. The
discharge to the river would have been monitored to ensure that
these standards were not exceeded. If such standards were
exceeded, then .pretreatment of the water would have been.
considered. Ground water quality would have been monitored by
sampling. existing monitoring wells, although some additional
monitoring wells might also have been necessary.
The institutional controls used under alternative G-2 to
control or limit human exposures would also have been used for
G-5. The present worth value of this alternative is estimated to
be $5,230,392.
4.6, Relocation of Municipal Drinking Water Well Field and
Institutional Controls, G-6
This alternative was identical to G-5, except that
contaminated ground water would not have been extracted or
discharged. Institutional controls, alone, would have been used
to reduce or control human exposure to contaminated ground water,
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20
which might occur from the use of private wells for drinking in
. the area of contamination.
Those existing municipal water supply ~ells with levels of
contamination consistently above the MCLs would have been taken
out of service and plugged, unless such wells were to be used for
monitoring or as a source of fire-fighting water.
Water from the new well field would have been piped to a
central treatment facility for chlorination and fluoridation and
stored in the 3,000,000 gallon storage tank at the new well
field. Finished water would then have been piped via a new
transmission line to the existing water distribution system at
Third Avenue and Highway 30. Water from the new well field would
have been blended with water from those wells in the existing
well field which were still used to supply drinking water.
Institutional controls, identical to those for
G-2, would have been used to prevent the use of the
ground water for drinking. The present worth value
alternative is estimated to be $4,687,192.
alternative
contaminated
of this
5.0 EVALUATION OF ALTERNATIVES
Nine evaluation criteria have been developed by EPA to
address' CERCLA statutory requirements and technical, cost, and
institutional considerations which the Agency has determined are
appropriate. The evaluation criteria serve as the basis for
conducting detailed analysis of the remedial alternatives during
the FS and for subsequently selecting an appropriate remedial
action in a Record of Decision. Attachment A provides a glossary
of the evaluation criteria which are also found in section
300.430(e) (9) (iii) of the NCP'. '
5.1 Overall Protection of Human Health and the Environment
G-l, no-action, is not protective. Without some action,
contaminated ground water may be consumed in the future, thereby
exposing human populations to unacceptable levels of risk.
without monitoring, no data would be available to assess
continued protectiveness.
G-2, institutional controls and monitoring, is protective of
human health. The municipal water supply has complied with the
SDWA for over two years. Although some of the ground water at
the site s~illhas contamination greater than the MCLs, such
exceedences were very slight in the two rounds of samples
collected by EPA in 1993 and were found in only a few of the more
than 30 monitoring wells sampled. Also, EPA has not found any
private wells in the area of contamination which are used for
drinking. Such uses (of currently unused ground water) remain a
possibility in the future if ,additional private wells are
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21
installed in the area of contamination and used for drinking.
G-2 is also protective of the environment. If ground water
is collected as part of this remedial action, pursuant to the
contingency identified in this ROD, and discharged to the Loup
River, any discharge must meet the state Water Quality standards,
using treatment if necessary. Also, no water would be discharged
to the river during low~flow conditions.
G-3 (ground water extraction for discharge to the Loup
River), G-4 (ground water extraction and treatment for use as
drinking water), G-5 (relocation of municipal well field with
collection of contaminated ground water for discharge), and G-6
(relocation of new' well field) would also all be protective for
the reasons outlined above for G-2, including the municipal water
supply's compliance with the SDWA.
5.2 Compliance with ARARs
Not applicable; G-l (no action) has no ARARs.
G-2 (institutional controls and monitoring) complies with
ARARs. EPA's MCLs under the Safe Drinking Water Act and the
state Title 118 Standards are ARARs and will be used to determine
the continued need for institutional controls and mon~toririg.
G-3 (ground water collection for discharge) would also meet
ARARs. If the contingency is triggered and ground water is
collected, the MCLs would also be considered relevant for
determining how long such extraction needed to be continued. .
state Water Quality standards for the Loup River would be met for
discharges to the Loup River pursuant to the contingency.
G-4 (ground water extraction and treatment for use as
drinking), G-5 (municipal. well field relocation with ground water
extraction for discharge) and G-6 (relocation of municipal well
field) all'meet ARARs, although the identity of the ARARs varies
with each alternative.
5.3 Lonq-term Effectiveness and Permanence
G-l (no action) appears unlikely to have been effective in
the long term: nor would it ensure a permanent solution.
contaminants continue to be found in ground water above levels
determined by EPA to be acceptable for drinking (the MCLs).
G-2 (institutional controls and monitoring) should be .
effective in the long term. There is some question regarding the
permanence of this alternative. It is possible, although
unlikely, that contaminant concentrations in the ground water
will increase, or that additional shallow private water supply
wells will be installed in areas of contamination and used for
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22
drinking. For this reason, EPA has identified a contingency for
the collection of contaminated ground water as part of this
remedial action on this site.
G-3 (ground water collection for discharge) is identified as
a contingency for implementation. EPA will reassess its baseline
risk assessment to determine the need for implementing this
contingency after one year and again after five years of ground
water monitoring. If this contingency is implemented, the long
term effectiveness could be less than optimal. As long as the
existing municipal well field continues to be pumped, it may be
difficult to obtain hydraulic control via extraction wells
because of the large volume of ground water withdrawn by the
existing well field" In part, this is why EPA did not select
alternative G-3 as the remedial action, except as a contingericy.
G-4 (ground water collection, treatment and use as drinking
water) would be more effective in the long term than G-3.
G-S (relocation of municipal well field and ground water
collection for discharge) would be slightly better than G-3 or G-
4. Since a new water supply would be used, contaminant removal
from the aquifer would take longer than G-3 or G-4, although
containment could still be effective under G-S.
. The long-term effectiveness of G-6(relocation of municipal
well field) would have been the same as for G-S, except that
aquifer cleanup would take longer because G-6 does not provide
for the extraction of contaminated ground water.
5.4 Reduction of Toxicity, Mobility and Volume Through Treatment
Neither G-l (no action) nor G-2 (institutional controls and
monitoring) would achieve a reduction in contaminant toxicity,
mobility or volume through treatment. .
. .
G~3 (ground water extraction for discharge) would not
achieve any such reduction unless it was determined that the
discharge could not meet state water quality standards for the
Loup River and treatment therefore had to be added. Even then,
any "treatment", such as air stripping, may be more of a transfer
of contaminants from one medium (water) to another (air).
G-4 (ground water collection for treatment and use as
drinking water) would also not achieve any reduction through
treatment unless air stripping is considered to be treatment.
However, as noted above, air stripping is more of a transfer of
contaminants from one medium (water) to another (air) than
treatment of the contaminant.
Neither G-S (relocation of municipal well field and ground
water collection for discharge) nor G~6 (relocation of municipal
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23
well field) Nould achieve any reduction through treatment.
5.5 Short Term Effectiveness
This criterion assesses short-term impacts of alternatives
considering the following: short-term risks to the community
during implementation: potential impacts on workers during the
remedial action: the effectiveness and reliability of protective
measures: the potential environmental impacts of the remedy: the
protectiveness and reliability of mitigative measures: and the
time until protection is achieved. 'This criterion is
inapplicable to no action (G-l). There is no short-term risk
associated with the implementation of the remedial action
selected, G-2, unless the contingency for G-3 is ~mplemented.
G-3 (ground water collection for discharge) poses minimal if
any short-term risk to workers or the community during
implementation. No significant risk to the environment would
result since any discharge to the Loup River would meet state
water quality standards.
G-4 (ground water collection for treatment and use as
drinking water) would also pose no significant risk to workers,
the community or the environment during implementation.
G-5 (relocation of municipal well field and ground water
collection for discharge) would have posed no significant short
term risk during implementation to workers, the community or the
environment.
G-6 (relocation of municipal well field) would have about
the same short-term effectiveness as G-5, except that there would
be no discharge under G-6 to the Loup River.
5.6 Implementability
Implementability is not applicable to the no action
alternative, G-l.
The ground water monitoring components of G-2 are readily
implementable. The institutional control component of G-2 has
two elements: advisories from EPA: and possibly a city ordinance.
EPA will issue its advisories itself but will be dependent upon.
the city of Columbus to. pass any local ordinance.
.G-3, ground water collection for discharge to the Loup
River, is readily implementable. Some additional extraction
wells could be required, but these pose no significant impediment
in terms of implementability.
G-4 (ground water collection for treatment and use as
drinking water) is readily implementable .from a technical
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24
standpoint. Air stripping, or other methods of ground water
contaminant removal, would be required before the ground water
could be used for drinking. Air stripping is a commonly used
technology. Additional piping of treated water to the municipal
drinking water distribution system would be required, which would
not have been difficult. The principal impediment to the
implementability of this alternative would have been that
stripping the water and sending such water to the municipal
drinking water supply might have caused excessive scaling in the
municipal supply distribution piping, to the point where the city
might no longer have been able to effectively deliver drinking
water to all of the city. '
G-5 (relocation of municipal well field with ground water
collection for discharge) would probably have been somewhat more
difficult to implement than G-3 or G-4. Drinking water would
have to have been pumped a long distance to the existing
distribution system. Ground water would have to be collected and'
piped to the Loup River (or a sewer leading to the River). Land
access for the piping, extraction wells and especially for a new
well field would have been particularly difficult given the
opposition of many of the citizens and property owners living
near Lake Babcock (the site. of the proposed well field) who
attended the pUblic meetings or who wrote letters to EPA
objecting to the preferred. alternative (G-5). '
The implementability of G-6 (relocation of municipal well
field) would have been similar to G-5 for the same reasons.
5.7 Cost
The following costs were estimated for the remedial
alternatives evaluated in the RI/FS for 30 years worth of
operation within an accuracy of -30% to +50%:
G-l, no action: ,(by definition)
G-2, institutional controls and monitoring:
G-3, ground water collection for discharge:
G-4, ground water collection for treatment
and use as drinking water:
G-5, relocation of municipal well field and
ground water collection for discharge:
G-6, relocation of municipal well field:
$0
$465,505.
$1,131,155.
$1,697,859
$5,230,392
$4,687,192
5.8' state 'Acceptance
The Governor of Nebraska has designated NDEQ as EPA's
contact for consultations on Superfund remedy selections.
has expressed a concern that contaminant concentrations in
municipal drinking water wells could increase, thereby
potentially exposing the people who drink this water to
NDEQ
the
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25
unacceptable levels of risk. Further, NDEQ questioned whether
EPA could respond to such an occurrence in a timely manner. EPA
believes this is unlikely to occur, but if it does, EPA has
several options available, including amending this ROD and
exercising its removal authority under section 104(a) of CERCLA.
Decisions on the need for a removal are made using the eight
criteria for removals found in Section 300.415(b) (2) of the NCP.
The NDEQ has sent a letter regarding concurrence to EPA, which
expresses support for EPA's plan to monitor the ground water to
assure protection of public health and the environment
5.9 community Acceptance
EPA's assessment of this criterium is based upon the oral
and written comments received on the Proposed Plan. EPA
responses to comments are included in the Responsiveness Summary
which is included as part of this ROD.
A number of commenters near the location that was considered
to assess the implementability of alternatives G-5 and G-6, which
included a well field, questioned whether a new well field was
required and expressed a preference for alternatives which did
not include a new well field (G-l, G-2, G-3 and G-4) because they
were concerned a new weil field would c~use existing water wells
to go dry, might limit the use of agricultural and industrial
chemicals, or might somehow depress property values.
Only a few commenters from the community
for the need for alternatives including a new
G-6) or alternatives requiring the collection
either treatment or discharge (G-3 and G-4).
expressed support
well field (G-S and
of ground water for
The city of Columbus strongly favored the alternatives
including a new' well field (G-5 and G-6) and continues to .
maintain that one of these alternatives should be selected. The
city had plans to build a new well field prior to EPA's release
of its proposed Plan for this site.
6.0 SUMMARY OF THE SELECTED ALTERNATIVE
The alternative selected as the remedial action for this
site is G-2, institutional controls and monitoring. However, a
contingency is included for ground water extraction, which may be
conducted as part of this remedial action, if determined to be
necessary in an EPA reassessment of its baseline risk assessment
after one year and again after five years of ground water
monitoring. EPA may seek to implement this contingency if the
carcinogenic risk for a reasonable maximum exposure (RME) to
releases from the site exceeds lE-4, or if a hazard index of more
than 1.0 is calculated for an RME for releases from the site.
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The following institutional controls will be implemented
until ground water cleanup goals are met:
-EPA advisories issued to users of private wells producing
contaminated ground water recommending that such ground water not
be used for human consumption; and
-The City will be ask to pass an ordinance prohibiting the
drilling of new private wells in the area of contamination.
EPA has not found any private wells in the area of ground
water contamination which. are used for drinking. Most of the
private wells found by EPA in Columbus are used for lawn and
garden watering. However, it is possible that some private wells
in the area of contamination could be used for drinking without
EPA knowledge. In addition, there is the potential for
additional private wells to be drilled and used for drinking if
such activities are not prevented or discouraged.
Monitoring of some of the existing monitoring wells
installed by EPA during the RI/FS, and possibly of some abandoned
drinking water wells, will be conducted in order to determine
when ground water has been restored to drinkable quality (below
the MCLs) and when the institutional controls can be lifted.
Specifics on the collection of ground water for discharge as
a contingency under this remedial action will depend upon the
levels and the extent of the contamination found triggering the
contingency. EPA will review the ground .water flow conditions,
the actual and potential uses of the ground water contaminated or
at risk of contamination, the ground water contaminant
concentrations and will reassess the risk in its baseline risk.
assessment in determining whether or not the contingency is
triggered. It is unlikely that the extent of ground water
contamination will be as great as it once was during the RIfFS.
Therefore, the number of extraction wells required may not be as
large as originally described in the RI/FS for alternative G-3.
Implementation of this contingency would require the
installation of extraction wells, unless existing (monitoring or
abandoned drinking water) wells are used for the extraction,
which would be assessed during remedial design. At a minimum,
this contingency would also require some piping from the
extraction wells to the point of discharge (either the Loup River
or a storm sewer leading to the Loup River). Existing data
including data collected during and after the RI/FS, indicate
that the contaminated ground water collected could be discharged
without treatment and meet the state's water quality standards
for the Loup River. However, EPA would reassess the need for
treatment during remedial design before ruling it out completely.
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7.0 STATUTORY DETERMINATIONS
Under its legal authority, EPA's primary responsibility at
Superfund sites is to undertake remedial actions that achieve
effective protection of human health and the environment. Also,
Section 121 of CERCLA establishes several other statutory
requirements and preferences. These specify that when completed,
the selected remedial action must comply with federal and state
ARARs unless a statutory waiver is justified and obtained.
,The selected remedial action must also be cost-effective and
utilize permanent solutions and alternative treatment
technologies to the maximum extent practicable. Finally, CERCLA
includes a prefere~ce for remedies that use treatment as a .
. principal element to permanently and significantly reduce the
toxicity, mobility or volume ~f hazardous substances. The
following discussion addresses how the remedial action selected
in this ROD meets these statutory requirements.
7.1 Protection of Human Hea1th and the Environment
The selected remedy is protective of human health and the
environment. The municipal drinking water supply has been in
compliance with the SDWA for over two years. Further, the levels
of ground wat'er contamination were much lower in the two rounds
of samplescollectect in 1993 than in 1990. and 1991. The selected
remedy's institutional controls will ensure that owners and users
of private wells in the area of ground water contamination are
informed that the ground water should not be used for drinking.
EPA is requesting that the City of. Columbus prohibit the drilling
of any new private wells in the area of ground water
contamination which might be used for drinking.
If.the contingency in this ROD for collecting contaminated
ground water is triggered, any discharge of such water to the
Loup River would be protective of health and the environment
because any discharge would comply with the state's water quality
standards for the river. No discharges to the river will occur
during low or no-flow river conditions.
7.2 compliance with Applicable or Relevant and Appropriate
Requirements (ARARs)
a. The MCLs for TCE and PCE under the Safe Drinking Water
Act and the State Title 118 Standards are ARARs. Ground water
monitoring will be conducted, and institutional controls will
remain in place, as long as ground water contaminant
concentrations exceed the MCLs and the Title 118 Standards.
b. If additional monitoring wells are installed in order to
conduct ground water monitoring, or if the contingency is
triggered and extraction wells are installed, such wells must be
----.---. .
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registered with the Nebraska Department of Water Resources
pursuant to Neb. Rev. stat. 946-602 et seq. In addition, if such
wells are not on the Tenth street site and are located in a
designated Ground Water Management or Control Area, permits may
be required from the Natural Resources District.
c. If additional monitoring wells are installed in order to
conduct ground water monitoring or if the contingency is
triggered and extraction or collection wells are installed, then
the Water Well Standards and Contractor's Licensing Act, Neb.
Rev. Stat. 946-1201 to 46-1241 and accompanying regulations found
in Title 178 would be satisfied. .
d. Any new monitoring wells installed must satisfy the
spacing requirements of Neb. Rev. Stat. 946-651 to 46-655.
e. If new monitoring wells are installed, or if the
contingency is triggered and extraction wells are installed, and
if either type of well is located in a flood plain, then the
Flood Plain Management Act, Neb. Rev. stat. 931-1001, Titles 455
and 258. Any new monitoring or extraction wells must protect
against the introduction of flood water contamination.
f. Title 119 (National Pollution Discharge Elimination
System, "NPDES" regulations)~ Title 121 (general NPDES .
regulations), Title 117 (surface water quality standards) and
Title 127 (Publicly-owned Treatment Works, "POTW" regulations)
would regulate the discharge of any ground water collected if the
contingency is triggered and implemented.
7.3 Cost-Effectiveness
The selected remedy is cost-effective because it is the
least expensive alternative which is also protective of health
and the environment. (G-1, no. action, is not protective.) EPA
'estimat~s the present worth. value of the alternative selected as
'the remedial action in this ROD to be $465,505. The estimated.
present worth value of the contingency identified in this ROD is
$1,697,859. .
7~4 utilization of Permanent Solutions and Alternative Treatment
(or Resource Recovery) Technologies to the Maximum Extent
practicable'
Treatment of the contaminated ground water is not necessary
to protect human health and the environment, to comply with
ARARs, or to achieve long-term protectiveness or permanence.
Treatment would be utilized pursuant to the contingency
identified in this ROD, if it was determined to be necessary in
order to comply with State .Water Quality Standards for a
discharge to the Loup River.
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EPA has determined that the selected remedy provides for a
permanent solution and utilizes treatment to maximum extent
practicable in a cost effective manner. The selected remedy
provides the best balance of tradeoffs in terms of the nine
remedial alternative evaluation criteria identified in the NCP.
7.5 Preference for Treatment as a principal Element
As noted above, based upon the existing data, treatment of
the contaminated ground water does not appear to be required to
protect human health and the environment, to comply with ARARs,
or to achieve long-term protectiveness or permanence. For these
reasons, treatment is not a principal element of the remedy
selected. However, as noted above; treatment would be utilized
pursuant to the contingency if .it were determined necessary in
order to comply with the State Water Quality Standards for a
discharge to the Loup River.
8.0 DOCUMENTATION OF SIGNIFICANT CHANGE
The Proposed Plan for the Tenth Street site was released for
public cqmment on April 26, 1993. It identified EPA's preferred
remedial alternative as G-5, which included the relocation of the
existing municipal well field to a location north of Columbus, .
the extraction of contaminated ground water for' discharge to the
Loup River, and institutional controls to prevent the consumption
of shallow contaminated ground water.
G-5 was not selected as the remedial action for this site
because recent data has demonstrated that the municipal drinkinq
water supply is in continued compliance with the Safe Drinkinq
Water Act. G-5 and G-6, the alternatives including a new water
supply, thus became substantially' less cost effective than G-2
and G-3, because alternatives G~2 and G-3 are now protective. G-
2 and G-3 were not considered protective when EPA released the
Proposed Plan, but are now because of new data received since the
release of the Proposed Plan.
In addition, the levels of ground water contamination found
in monitoring wells were much lower in 1993 than the levels found
before EPA released its Proposed Plan. It is possible that the
levels could increase again, but this is unlikely in EPA's
opinion. EPA has retained the ground water extraction component
of the previously preferred alternative (G-5), which was also
identified as G-3, as a contingency for the remedial action
selected in this Record of Decision. EPA will reassess the
levels of ground water contamination after additional data has
been collected, alonq with the hydrogeology, ground water uses
and other relevant factors to determine if ground water
extraction is warranted.
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III. RESPONSIVENESS SUMMARY
This Responsiveness Summary (RS) presents the responses of
the Environmental Protection Agency (EPA) to public comments
received regarding the Proposed Plan for the Tenth Street Site in
Columbus, Nebraska. The RS addresses all of the substantive
comments received by EPA during the public comment period,
including both oral comments made during the two public meetings
and written comments received by or sent to the EPA.
Readers are referred to a list of acronyms or abbreviations
used in both the Responsiveness Summary (RS) and the Record of
Decision (ROD) which is found at the end of the RS.
. Similar comments have been combined and stated and responded
to only once in the RS. EPA's response follows. each comment.
The following are the comments and EPA's responses on the
remedial alternatives identified in the Proposed Plan EPA
released on April 26, 1993 on the Tenth Street Site.
1. Comment A commenter asked if the legal rights of area
homeowners near the well field proposed in the preferred
alternative were determined and presented at the hearings?
are these rights?
What
EPA Response EPA was very sensitive to the concerns expressed by
the homeowners objecting to a new well field~ The degree of this
opposition was a factor in EPA's selection of the remedial
action. Community acceptance is one of the nine criteria
identified in theNCP for EPA's evaluation of remedial
alternatives on Superfund sites. As EPA stated at the public
meetings, EPA could not legally have replaced wells that went dry
as a result of ground water withdrawals from a new well field
because doing so would not have been a response to a release of a
hazardous substance pursuant to CERCLA.
2. Comment Many comments were received on whether or not pumping
water from a new well field would lower the water table and cause
existing irrigation or private water supply wells to go dry.
These comments were made with respect to irrigation wells,
private drinking water wells and wells serving schools.
Some commenters were particularly concerned that the effects
of increased pumping during dry weather, coincident with little
or no recharge of the aquifer, could. combine to lower the water
table to the point that existing wells might go dry.
A commenter asked if a drop in the water table could lower
water pressure in homes served by private wells near a proposed
well field. Another commenter asked if the costs of lowering
existing wells because of a drop in the water table had been
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factored into EPA's preferred alternative. Another commenter
stated that pumps could only be lowered to the bottom of the well
and to lower a pump any more would require a new well to be
drilled. Also, a commenter noted that the occurrence of bedrock
would prevent wells from being drilled any deeper unless drilling
methods were used which can drill through rock.
Many commenters opposed the preferred alternative because of
one or more of these concerns.
EPA ResDonse The points raised are moot since the remedial
alternative selected by EPA does not include a new well field.
However, EPA believes that there is enough water in the aquifer
near Lake Babcock (the site of the well field proposed under.
alternatives G-S and G-6) so that the water table would' not have
been significantly lowered very far beyond the well field.
Within the influence of the wells there would have been some
lowering of the water table, but not, in EPA's opinion, enough to
cause any existing wells to go dry. Nonetheless, the degree of
community opposition on the part of land and well owners near the
proposed well field was a factor EPA considered in selecting a
remedial action which did not include a new well field.
3. Comment A commenter pointed out that the cost of G-4 was less
than G-S, and G-4 was also protective of human health. Why did
. EPA recommend G-S rather than G-4? . Another commenter agreed and
pointed out that Congress provided a statutory preference for
alternatives which use treatment in the Comprehensive
Environmental Response, Compensation and Liability Act (CERCLA).
EPA ReSDonse EPA did not recommend G-4 because the available data
indicated that air stripping of the contaminated water from some
of the existing municipal water supply wells would oxidize the
water. The ground water from the existing well field contains
concentrations of iron and manganese which could cause scaling if
the water were oxidized. Sign~ficant scaling in .the municipal
water supply does not currently occur because the water is not
sufficiently oxidized. Scaling would pose a significant
limitation to the City's ability to effectively deliver drinking
water to homes and other buildings in Columbus, since the scaling
could plug or clog the distribution lines. Scaling is also
aesthetically unattractive for drinking water, although this was
not as important.
In order to treat the contaminated water from the existing
well field and avoid scaling, water treatment other than air
stripping would have to have been used. EPA did not find any
such alternative treatment technologies that were sufficiently
reliable and cost effective to use for municipal drinking water.
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4. Comment A commenter stated that contamination of the Tenth
Street sit~ came from businesses in Columbus and that they should
pay for the site cleanup. Jther cc~menters asked if the sources
of contamination had been identified, and agreed that the parties
responsible should be requi~ed to f~nd the remedial action. Some
commenters thought that the city as the owner of the property
containing the highest levels of ground water contamination
should be responsible for funding the remedial action.
EPA Response EPA agrees that responsible parties should pay for
remedial actions, as well as investigations, at Superfund sites. .
However, the available data are not sufficiently clear as to the
source(s) of the contamination. If at some point the data does
allow sources of contamination to be identified with sufficient
certainty, EPA would seek to require that the parties responsible
perform the remedial action selected in the ROD, or EPA would
then .attempt to recover its costs en the site from such parties.
5. Comment Several commenters stated that very little concern
was given by EPA to the rights of the residents near the proposed
well field near Lake Babcock. In particular, several commenters
asked who would compensate chern or repair their existing well, if
it were to go dry because or pumping at a new well field. Some
commenters felt that. EPA, if it installs new drinking water
wells, or the city, as the operator of the municipal water supply
should De obligated to. fund the repair or replacement of any
wells which go dry from pumping a new well field. Some of the
commenters stated that if EPA or the city would not or could not
make this commitment, then property owners would retain. a
hydrologic consultant and an attorney in order to obtain
compensation from EPA or the city if their wells go dry.
EPA Response As stated in the response to comment no. 2, EPA
does not believe that any existing wells would have gone dry from
pumping at a new well field. However, if a new well field h~d
been installed by EPA as a remedial action, EPA could not legally.
have replaced wells which might have gone dry. because doing so
would not have been a response to ~,release of a hazardous
substance. EPA does not know who would have been responsible for
the restitution for such damages. The point is now moot in view
of the fact that the remedial action selected by EPA does not
include a new well field. The concerns raised in these comments,
and the community.opposition reflected, were factors in the
remedial alternative selected by EPA for this site.
6. Comment Several commenters stated that there was not enough
time given to the community to comment on the Proposed Plan, or
that EPA's notices announcing the public meetings were inadequate
or not known to a sufficient number of people in the community.
Several commenters asked EPA to extend the public comment period.
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EPA Response Although EPA's initial comment period met the
requirements of the National Contingency Plan (NCP), EPA extended
the comment period to allow a greater opportunity for public
comments. The original 30-day comment period was extended to 70
days, ending July 6, 1993. .Notice of both public meetings was
provided in the Columbus Telegram.
7. Comment A commenter asked if a new well field would withdraw
enough water so that Lake Babcock would contain less water and
whether this could adversely affect the lake as a habitat for
aquatic vegetation and wildlife, including waterfowl. The
commenter stated that each spring and fall more and more pelicans
stop at the lake. In recent years, there have also been more
herons and egrets~ Two winters ago about 35 bald eagles were
seen at the lake. The Game and Park commission released some
Canadian Geese at the lake several years ago. For the past two
years seven geese, including some chicks, were seen at the lake.
EPA Response EPA does not believe that pumping at a new well
field near Lake Babcock would have withdrawn enough water to
cause any of the above adverse environmental impacts. However,
the point is now moot since the alternative selected by EPA as
the remedial action does not include a new well field.
.8. Comment A commenter asked if a well field. near Lake Babcock
would jeopardize the existence of any endangered or threatened
species, including the White Lady Slipper Orchid, which depends
upon a high water table or the Regal Fritallary, a moth which has
been proposed by the Federal government as a threatened species.
EPA Response As noted in the response to comment no. 7, EPA does
not believe that pumping at a new well field near lake Babcock
would have withdrawn enough water to cause any of the above
adverse environmental impacts. EPA consulted with federal and
state officials who are responsible for the management and
preservation of threatened or endangered species and determined
that no threatened or endangered species are at risk from this
site. The Large White Lady Slipper Orchid is neither an
endangered nor a threatened species. It has been proposed by the
State of Nebraska as a threatened species, but not yet listed as
such. The point is now moot in view of the fact that remedial
alternative selected by EPA does not include a new well field.
9. Comment A commenter stated that the EPA did not keep the
public informed about the activities at the Tenth Street Site.
EPA Response EPA has conducted all of the activities required in
our community relations plan on this site, as well as a second
public meeting and an availability session after the close of the
comment period, which were not originally identified in the
Community Relations Plan. EPA held an availability session on
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August 15, 1990 before beginning the RI/FS field work. EPA held
public meetings on this site in May and again in June of 1993.
Further, EPA held a second availability session .in December 1993.
Notices of the public meetings and availability sessions were
published in the Columbus Teleqram.
10. Comment A commenter expressed concern about a 1000 acre
buffer zone described for alternatives G-5 and G-6, which would
have included a new well field. The commenter asked where the
buffer zone would be located? Several commenters asked about any
restrictions on the use and handling of pesticides, fertilizers,
or industrial chemicals in the buffer zone?
EPA Response The point is now moot
well field as the remedial action.
comment EPA provides the following
wellhead protection and the siting
since EPA did not select ~ new'
Nonetheless, to address the'
information, which relates to
of public water supply wells.
There was some confusion in the first public meeting as to
the size of a buffer zone, 1000 feet. or 1000 acres around public
water supply wells. NDOH must approve the location of any public
water supply wells and generally requires at least. 1000 feet
separation from any existing registered water supply well and at
least 500 feet separation from any point source of contamination,
such as an animal feed lot. Exemptions can be considered if site
hydrogeology provides' sufficient protection to well water from
contamination.
If a new well field would have been installed as part of the
superfund remedial action, the City, the State and EPA would have
worked together on a well head protection plan to ensure that
well water remained free of contamination. site specific factors
such as hydrogeology and pumping rates would have been reviewed
to determine what buffer zone would have been required for this
well field. Certain high risk activities such as fertilizer or
pesticide formul~t~on or blending might have posed an.
unacceptable risk of well water contamination.
11. Comment Several commenters asked how many wells would have
been installed under alternatives G-5 or G-6. Different numbers
of wells were discussed during the public meetings and in some of
the reports. Another commenter asked why the number of wells
proposed for alternatives G-5 and G-6 were required.
EPA Response Alternatives G-5 and G-6 proposed three or four new
water supply wells to replace the city wells which currently not
used because of contamination. The exact number of wells would
not have been determined until remedial design was completed and
would have depended upon the productivity (amount of ground water
extracted in the wells) of the aquifer. A city report used by
EPA for hydrogeologic information discussed a larger number of
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wells for the city's future needs. However, the number of wells
installed by EPA under alternatives G-S or G-6 would have been
either three or four. Any additional wells installed would have
been by city to meet their water capacity needs. The remedial
action selected by EPA now includes no drinking water wells.
12. Comment A commenter asked how a new well field under the
preferred alternative, G-S, would affect septic systems. On a
related issue, another commenter asked if existing septic systems
could be repaired and if new septic systems could be installed if
a new well field was provided as the remedial action. Another
commenter asked if new regulations on septic systems could be
affected if a new well field were installed.
EPA Response A new well field would not have adversely affected
the operation of septic systems. Septic systems are among the
potential contaminant sourceS from which drinking water wells
should be protected or separated. (See response to Comment no.
10). The point is now moot since the alterna~ive selected by EPA
as a remedial action does not include a new well field.
13. Comment A commenter asked how a well field would have
impacted the livelihoods of area farmers.
EPA Response EPA did not select a remedial action including anew
well field. However, 'the following information is provided to
respond to the question. It is possible that the use of
agricultural chemicals on farmland in the immediate vicinity of a
well field could have been restricted. However, EPA believes
that the impact would , have been minimal. If agricultural
chemical use on fields would have been restricted to protect
drinking water wells, this would be a well head protection
activity by the operator of the drinking water supply, which
would be the City of Columbus.
14. Comment Several commenters asked if, ag~icult~ral chemicals
' (fertilizers, pesticides and herbicides) could continue to be
used on nearby properties if a well field were to be installed.
Similar questions were received with respect to the use of lawn
chemicals near a well field.
EPA Response The use of such chemicals very near drinking water
wells is discouraged. Had a new well field been installed by EPA
under Superfund, EPA would have encouraged or required the City
to protect the wells from such potential,contamination. This
wouldprobaply have involved negotiations between the city, as
the operator of the drinking water supply, and the affected
property owners. The point is now moot since the remedial action
selected by EPA does not include a new well field.
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15. Comment Several commenters asked if existing agricultural
practices such as hog confinement and feeding operations near the
proposed well field would have been allowed to continue to
operate. Another commenter asked whether they could continue to
remove the sediment from the bottom of a nearby hog confinement
lagoon and to spread it out on the adjacent land surface.
EPA Response Hog confinement areas of sufficient size and close
enough to the well field would be a potential source of
contamination. Therefore, an attempt would have been made to
locate the wells far enough away from such operations to minimize
potential contamination. If it were not possible to locate the
wells far enough from all potential contaminant sources,
consideration would have been given to relocating or removing the
contaminant sources. The point is .now moot since the remedial
action selected by EPA does not include a new well field.
16. Comment A commenter asked who would have paid for a new
well field under the preferred alternative.
EPA Response Had a well field been installed as a Superfund
remedial action, 90% of the funding would have come from EPA,
using the Hazardous Substances Response Trust Fund, which obtains
funds from a.tax on the manufacture of chemicals. The remaining
10% of the funding would have come from the State of Nebraska or
a political subdivision, ~such as the City of Columbus. .
17. Comment A commenter asked if row crops could still have been
grown on the property near a new well field.
EPA Response The point is now moot since the remedial action
selected by EPA does not include a new well field, but no crops
could have been grown on the property on which the well field
would have been located. As a practical matter, if crops were
planted and a new well field installed, the crops would probably
be damaged by vehicle traffic for the installation, development,
construction and repair of the. wells and the associated piping.
18. Comment A commenter asked if discharging contaminated water
into the Loup River would contaminate the river.
EPA Response The river would not have been contaminated to any
significant degree. The analytical data on the two rounds of
ground water samples EPA collected in 1993 showed that the
highest levels of ground water contamination for the chemicals of
concern at the site were lower than the State's Water Quality
Standards for the Loup River. Based upon existing data, EPA
believes that collected ground water could be discharged directly
to the river without treatment and still meet state water quality
standards. Because the Loup River has little or no flow during
certain dry months, no water would have been discharged during
such periods.
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19. Comment One commenter made the statement that Superfund
money is not available to clean up contaminated drinking water
wells, only contaminated dump sites.
EPA Response The EPA is authorized to expend Superfund money
responding to releases of hazardous substances. There are a few
releases which are excluded from EPA jurisdiction for which the
Fund could not be used, such as petroleum products, asbestos in
indoor building air, and releases which occur from the treatment
or conveyance of drinking water. None of these exceptions are
applicable to the Tenth Street Site. The releases from the Tenth
Street Site are eligible for Superfund response actions.
20. Comment A commenter stated
to address the contamination at
and neutralize all contaminants
the wells to the river.
that the only practical solution.
this site would be to filter out
in the water being pumped from
EPA Response This would have been similar to the alternative
evaluated as G-4. EPA did not recommend this alternative because
the existing iron and manganese in the ground water at. the
existing well field could result in excessive and unacceptable
scaling if the water were treated by air stripping. Measures
which might control or prevent scaling were much more costly than
any of the six alternatives identified in the Proposed Plan. .
This point is now moot, since the municipal supply has been in
compliance with the SDWA for the last two years and in view of
the alternative selected by EPA as the remedial action.
21. Comment A commenter asked who would pay for any depreciation
of drop in home or property values resulting from the
installation of a new well field.
EPA Response EPA does not believe that any negative impact from a
new well field on home or property values in the area would have
resulted from the installation and operation of a new well field.
However, if property values decreased because of the installation
or operation of a new well field, EPA could not reimb~rse for
such losses because this would be outside the scope of a
superfund remedial action. The point is now moot since the
remedial action selected by EPA does not include a new well
field.
22. Comment A commenter asked if all requirements of EPA and the
state had been considered and complied with?
EPA Response Yes. Most matters of regulatory compliance (i.e.
obtaining permits for offsite work) do not become relevant until
later in the process, after the remedial action is selected,
after remedial design is complete and when construction is being
planned or implemented. Also, the alternative selected as the
remedial action, G-2, does not include ~ny construction.
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23. Comment A commenter asked whether federal and state local
requirements mesh, or are there points of conflict?
EPA Response In general, at this site, they mesh.
24. . Comment A ccmmenter asked whether NDEQ's proposed change in
standards for private wells and septic systems would be a problem
if a new well field were provided as part of the remedial action.
EPA Response. As far as EPA can determine, this would not likely
.have posed a problem. New septic systems would have had to have
sufficient separation from the well field and be properly
designed and operated to protect the well field water from
contamination. The point is moot since a well field is not
included in the remedial action.
25. Commenc A commenter asked if the capacity for ground water
recharge or rate of recharge was determined? ,If not, why not?
Should it be determined?
EPA Response EPA believes that the city's pump test showed that
the aquifer south of Lake Babcock has enough water to serve a new
well field. Even if the remedial action had included a new well
field, additional study would not have been necessary before
signing the. ROD, because the ROD would only select the remedial
action, and would not select a well field location. If the
remedial action had included a new well field, additional
hydrogeologic studies would have been conducted as part of
remedial design after the ROD.
26. Comment A commenter asked if the anticipated drop in the
water table from. the pumping at a new well field would cause a
change in the levels of nitrates or other minerals or
contaminants in existing private wells, including radon? If so,
how? If not, why not?
EPA Response The point is now moot since the remedial action does
not include a new well field. However, EPA foresaw no impact
upon the concentrations of nitrates in existing wells had a new
well field been installed and pumped.
27. Comment A commenter asked if water conservation measures had
been considered by the City of Columbus. What measures is the
city willing to adopt? If there are no conservation measures
adopted, why not? Another commenter asked w~ether municipal
water conservation measures would cause inconveniences or burdens
upon water users and area residents.
EPA Response EPA has no direct knowledge of any specific water
conservation measures considered or implemented by the city.
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39
28. Comment A commenter asked why drilling new drinking water
wells was preferred over the other alternatives in the Proposed
Plan, and who made that decision?
EPA Response EPA evaluated all six remedial alternatives
identified in the Proposed Plan based upon the nine evaluation
criteria identified in Section 300.425 of the NCP, 40 C.F.R. Part
300. These criteria were explained in the Proposed Plan released
by EPA for public comment. A decision selecting a remedial
action had not been made when the Proposed Plan was released for
public review and comment. The Proposed Plan was only a
recommendation. The decision selecting the remedial action for
this site was not made until the ROD was signed by EPA's Regional
Administrator, who made this decision. EPA's rationale for'
recommending the new well field as the preferred alternative in
the Proposed Plan is contained in the Proposed Plan.
29. Comment A commenter stated that EPA appeared to have
already made the decision to install a new municipal well field
near Lake Babcock.
EPA Response EPA had not selected a remedial action at the time
the Proposed Plan was released to the public. EPA's
recommendation for a remedial action in its Proposed Plan was
based upon all of the, information that was available at that
time., Based upon new information, after ,the Proposed Plan was'
made public, EPA then selected a remedial action which did not
include a new well field, in part based upon the degree of
opposition on the part of land and well owners near Lake Babcock.
30. Comment A commenter stated that not enough data (relating to
a drop in the water table from a new well field and the impact on
existing wells in the area) had been collected and that not all
of the necessary hydrological studies had been completed to allow
EPA to propose a remedial action for this site at this time.
EPA Response EPA feels the that. the hydrogeologic data available
when the Proposed Plan was released for public review and comment
in April 1993 was sufficient to make a recommendation for a
remedial action. In the event that the remedial action selected
would have included a new well field, the additional data
referenced by the commenter would normally be collected during
remedial design after the ROD was signed.
31. Comment A commenter asked how soon the scaling might develop
in the city's water distribution lines if the alternative (G-4)
for treating the city drinking water by air stripping were
implemented. Another commenter asked whether scaling would be
more likely to occur in homes with metal plumbing versus plastic
plumbing, and whether flushing water through fire hydrants would
help control scaling?
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40
EPA Response The point is now moot since the remedial action does
not include treatment of wacer to be distributed for drinking
which could cause .scaling. It is difficult to know when scaling
might occur. It would probably occur at different times in
different homes served by public water. EPA believes that it is
possible some scaling problems in some parts of the distribution
system could start to occur within several years or even earlier,
although initially the scaling might not be sufficient to
completely shut off the wat~r to any individual home.
The type of household plumbing, metal versus plastic, should
have no impact on how soon scaling would .occur. Flushing water
through fire hydrants would not have controlled scaling.
32. Comment A commenter asked what additional components of a
muriicipal drinking water treatment and distribution system were
included for the two alternatives including a new well field, G-S
and G-6, such as water storage tanks and water transfer mains.
EPA Response If EPA had selected a remedial action which il'lcluded
a new well field, we would have replaced only what would have
been lost by the City from the abandonment of their contaminated
drinking water wells. This would have included the new water
supply wells and a distribution line from the new wells to the
municipal drinking water treatment plant. It would not have
included additional wells or any significant increase in the
capacity of the municipal water supply system.
33. Comment A commenter asked what costs were included in EPA's
cost estimate of $5,200,000 for alternative G-S.
EPA Response EPA's estimate of the costs of the remedial
alternatives in the Proposed Plan included equipment and
material, labor, contract management and interest ("cost of
money") for each alternative evaluated. Design cost.s were not
. included in the estimate.' .
34. Comment A commenter asked if the water at the proposed well
field was of acceptable quality for drinking and whether that
water contained radon in excess of EPA's proposed maximum
contaminant level (MCL) for public water supplies. Another
commenter asked if the radon levels in the ground water at the
proposed well field would require treatment to remove the radon.
The commenter asked if the treatment were air stripping, why not
just implement alternative G-4 and air strip the contaminated
water from the existing well field? .
EPA Response EPA believes that the ground water near Lake Babcock
where the well field was proposed is acceptable in quality as
drinking water. We base this opinion upon samples collected and
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41
analyzed by EPA and upon samples collected and analyzed for the.
city. At this time EPA has not established a maximum contaminant
revel (MCL) under theSDWA for radon. Therefore, if EPA had
selected a new well field as the remedial action, we would not
have included treatment to address the radon unless the MCL were
established as a final rule before we began construction.
35. Commen~ Several commenters stated that the wate~ at the
community college near the proposed well field has levels of
sulfur and iron which are too high to drink.
EPA Response The point is moot since the remedial action
selected by EPA does not include a new well field. However,
based upon samples collected and analyzed by EPA and upon samples
collected and analyzed for the. City, EPA believes that the water
quality at the proposed well field was acceptable for drinking.
36. Commenc A commenter asked how long it would take for the
contaminated ground water at the site to be cleaned up if an
alternative collecting contaminated ground water were
implemented?
EPA Response The migration of ground water contamination from
the site would have been stopped as soon as effective pumping
were started, assuming the zone of influence of the extraction.
wells was sufficient to capture contaminants throughout all areas
of the contaminant plume. This could have been made more
complicated if the city continued to pump the drinking water
wells located near Tenth Street, because of the large quantities
of.water those wells withdraw. It could easily take at least 20
years of pumping until contaminant concentrations had been
reduced to concentrations that would be safe for drinking, and
quite possibly longer than that.
37. Comment A commenter asked why the EPA decided to address the
10th Street Site as a Superfund site and consider funding the
remedial action under Superfund.
EPA Response The site was addressed by EPA as a Superfund site
and placed on the NPL because its score under the Hazard Ranking
System (HRS) was sufficiently high. Furthermore, EPA determined
that the releases of hazardous substances at the site were
eligible for response actions using the Fund, because these
releases did not fit into any of the exemptions under CERCLA,
exempting releases from Fund-financed response actions. To date,
EPA has not been able to identify any parties responsible for the
releases. Therefore, EPA utilized the Hazardous Substances
Response Trust Fund ("Superfund") to fund the RI/FS and will also
use this fund for the remedial action selected for this site.
38. Comment A commenter asked if the water quality in Lake
Babcock had been determined.
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42
EPA Response Programs in EPA and the State other than Superfund
are responsible for water quality in Lake Babcock. No water.
samples were collected from the lake under Superfund. However,
EPA determined that the ground water near the lake where a well
field was proposed was suitable in quality for drinking.
39. Comment A commenter asked whether Lake Babcock recharges the
aquifer beneath it. .
EPA Response The bottom of the lake is lined. There may be some
leakage ~hrough the liner recharging the aquifer underneath.
However, the leakage and the recharge are probably minimal.
40. Comment A commenter asked whether the discharge of
contaminated ground water into the river would increase the risk
of cancer in the huma~ population.
EPA Response If EPA extracts contaminated ground water under the
contingency identified in the ROD, any additional risk in human
cancer resulting from the discharge of the low levels would be
very small for several reasons. First, there are no nearby
downriver drinking water intakes. Second, the levels of
contamination in the ground water are very low and might not be
detectable in the water by the time it got to the river. Third,
. the contaminants .in the ground water tend to degrade ",?hen exposed.
to sunlight and air. Finally, the contaminants of concern do not
persist or accumulate in fish even if the contaminants would have
been present in the discharge water as it reaches the river, and
even if the fish were eaten.
41. Comment A commenter asked if EPA)s two public meetings on
this site were held because of a new state law: "Municipal and
Rural Water Transfer and Permit Act", 46-640. The commenter also
asked whether this new state law required the city to hold
another public meeting if it proposes to use ground water from
near Lake Babcock as a source of municipal water and stated that
this law appeared to have additional and specific public.
involvement requirements which have not been satisfied by EPA's
public meetings or public notices.
BPA Response No, the meetings were held pursuant to the National
Contingency plan and as community relations for the lOth Street
Site under the EPA Superfund program.
42. Comment Several commenters asked what would have happened if
nearby property owners did not consent to the restrictions on
chemical use if a new well field were installed.
EPA Response The point is moot because EPA will not be installing
a new well field as part of the remedial action. That is a
matter that would have had to have been resolved by the city and
the property owners.
~- - .'_"'N -- .
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43
43. Comment A commenter asked when the negotiations with
prope~ty owners would have been conducted with respect to
chemical use near the wells.
EPA Response Had the remedial action included a new well field,
these negotiations would likely have occurred after EPA signed
the ROD while EPA was completing the remedial design.
44. Comment A commenter asked whether well head protection could
effect more property than just within 1000 feet of the wells.
EPA Response The 'point is now moot since EPA will not be
installing a new well field. However, in some hydrogeologic
settings the minimum distances might not be sufficient to protect
drinking water wells and larger distances might be considered.
45. Comment A commenter inquired as to whether there is a
"grandfather clause" to allow preexisting wells to continue
used within the prescribed distance of the municipal wells,
new well field were installed.
to be
if a
EPA Response This is now a moot point since no well field will be
installed by EPA for this site, but this would have been a matter
to be resolved between the property owners and the operator of
the municipal drinking water supply, which is the city.
46. Comment Acommenter asked if interested persons would
receive a copy of EPA's responses to the comments and questions
raised by the public.
BPA Response EPA will send a copy of this Responsiveness Summary,
as well as the ROD, to everyone on the mailing list for this
site, which included everyone who wrote EPA a comment letter or
who signed an attendance sheet at either of the public meetings
or the availability sessions on this site. EPA could not send
our the Responsiveness Summary before the ROD was signed because
the Responsiveness Summary could not be finished until EPA .
determined what alternative would be selected in the ROD as the
remedial action.
47. Comment A commenter asked if, in view of the concerns
expressed by property owners near the proposed well field, would
EPA reevaluate the financial impact upon their properties if the
preferred remedial alternative were implemented.
EPA Response The point is moot since EPA will not be installing a
new well field for this site.
48. Comment A commenter asked if subsurface rocks would prevent
the installation of municipal wells for a new well field.
Another commenter asked how deep the wells for a new well field
would have been.
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44
EPA Response The point is moot since the remedial action selected
does not include a new well field. However, subsurface rocks
would not have been a significant problem with the installation
or completion of drinking water wells at the location proposed
near Lake Babcock. The wells would probably have been drilled
down to the top of the bedrock, about 100 feet.
49.. Comment A commenter asked whether the lake at 53rd Street
and 33rd Avenue would adversely effect a new well field south of
Lake Babcock. Would the pumping from the well field dry up the
lake at 53rd and 33rd? Who would be liable for damage resulting
from a drying of this lake?
EPA Response The point is now moot since EPA will not be
installing a new well field as a Superfund remedial action. EPA
does not believe that the pumping of a new well field would have
adversely affected the lake at 53rd Street or that the lake at
53rd Street would have adversely affected the pumping of a well
field near Lake Babcock.
50. Comment A commenter asked how expeditiously EPA would.
provide its responses to the comments and questions raised in
order that the commenters can respond to EPA's responses.
EPA Response EPA received several reqUests forresponses.to
. individual comments or all of the comments before EPA selected'
the remedial action for this site in a ROD. However, this was
not possible because the Responsiveness Summary could not be
completed, nor responses to individual comments made, until EPA
knew what alternative was finally selected as the remedial action
for this site. Responsiveness Summaries are necessarily released
simultaneously with RODs. .
51. Comment A commenter asked when EPA would select a remedial
action for this site and expressed concern that EPA would make
this decision when the property owners near the proposed well
field have not yet been presented all of the relevant facts and
information that EPA considered. .
EPA Response Because of some new data received after EPA released
the Proposed Plan in April 1993, EPA did not know with any
certainty when it would select a remedial action on this site.
As it turned out, EPA did not select a remedial action until more
than a year after it opened the public comment period. This
allowed additional sampling of the ground water and municipal
drinking. water supply. EPA believes that it is clear, from the
responses within this Responsiveness Summary and from the
alternative selected as a remedial action, that EPA gave full and
complete consideration to the concerns of the property owners
near the proposed well field.
- '.-----'
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45
52. Comment A commenter asked if city plans to extend its
municipal water distribution lines to the north were a
consideration in EPA's evaluation of the alternatives and EPA's
recommendation for a new well field to the north of Columbus.
Another commenter asked if the existing municipal wells had a
limited lifespan and whether or not this caused the city or EPA
to recommend a new well field.
EPA Response EPA was generally aware or some of the planning the
city had done with respect to its water supply. We felt it was
appropriate to consider this information when evaluating,
recommending and finally selecting a remedial action for this
site. Under the NCP, EPA is required to consider the cost
effectiveness o.f alternatives in its evaluation, and the city's
prior activities and plans were relevant to the cost- .
effectiveness criterion.
53. Comment A commenter asked if new regulations or policies
proposed by the State might effect farming operations near the
proposed well field if installe~.
EPA Response The point is now moot,
regulations could affect the use of
other farming practices which might
drinking water supply.
54. Comment A commenter asked if the city might have to condemn
land and reimburse the property owner, if a location for the well
field could not be found far enough from all contamination
sources and registered wells. Would or might the city use its
eminent domain authority? Other commenters asked what effect the
placement of a municipal well field near Lake Babcock might have
upon whether or not the city would annex this land.
but it is possible that new
agricultural chemicals and
contaminate the city's
EPA Response The point is now moot since a well field will not be
installed as part of the Superfund remedial'actio~. The c;i.ty
would have been responsible for obtaining the land for a new well
field. It could have used whatever legal authority it had
available to accomplish this.
55. Comment A commenter asked who will make the decision
selecting a remedial action for the 10th Street Site. If the
remedial action includes a new well field, who decides where such
wells will go?
EPA Response Except on certain matters of national significance
on which EPA Headquarters would become involved, remedial actions
on Superfund sites are selected by EPA's Regional Administrator,
for the region in which the site is located. The remedy for this
site was selected by the administrator of EPA Region VII.
Although this point is now moot since the remedial action
selected does not include a new well field, specific locations of
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46
water supply wells would not have been determined until remedial
,design wh~ch follows the Record of Decision.
56. Comment A commenter asked if land values are inflated
because the city acquires land for a well field as part of a
Superfund remedial action and thereby increases the local demand
for land, would EPA agree to provide additional funding for the
city to acquire the necessary property or access. If the costs
became large enough would EPA consider other remedial
alternatives?
EPA Response The point is now moot. It seems very unlikely to
EPA that such increases in the cost of a new well field could
have increased' enough to have allowed those alternatives (G-Sand
G-6) to be rejected based soley upon cost, although the land'
acquisition costs would probably have been an allowable cost
under the remedial action and reimbursed by EPA, if the remedial
action for this site had included a new well field.
57. Comment A commenter stated that the city had considered
another location for a new well field, known as the south
alternative. Has this been eliminated? If so, was landowner
opposition the reason?
EPA Response The point is now moot, since a well field is not
included as part o~ ,the Superfund remedial action. The north
location for a new well field (near Lake Babcock) seemed
preferable to EPA for technical reasons, including
hydrogeological. EPA was not aware of any more significant land
owner opposition at the south alternative, if, in fact,' any
existed. It did appear to EPA, that well head protection for the
south alternative would have been much more difficult, because it
appeared that more agricultural chemicals were being used near
the south alternative than near Lake Babcock.
58. Comment Acommenter stated that EPA did not conduct all of
the activities it said it would in its Community Relations Plan.
The commenter also stated that EP~'~ notices on the public
meetings held were inadequate. Finally, the commenter stated
that this project really is not progressing as quickly as earlier
indicated in the public meetings. Someone else also stated that
other political entities representing the interests of property
owners were left out of the public meetings and discussions with
EPA, including the Natural Resource Districts.
EPA Response EPA conducted all of the community relations
required by the NCP or indicated in the Community Relations Plan.
EPA work en this site has proceeded as quickly as circumstances
allowed, in view of some of the new information EPA received
after EPA released the Proposed Plan.
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47
59. Comment A commenter asked what ground water pump tests were
conducted, by whom and why.
EPA Response Pump tests of several types have been done. EPA did
a small pump test near the existing well field to better define
the potential for contamina~ed ground water to migrate. The pump
test for the well field proposed near Lake Babcock was done by a
contractor for the City of Columbus. EPA evaluated the results
of that pump test and felt that it was sufficient to conclude
that the area south of Lake Babcock would provide enough water to
serve properly installed, constructed and developed drinking
water supply wells. EPA did not believe, it would have been a
good use of money to replicate that pump test.
60. Comment Several commenters ,stated that there were
discrepancies or errors in the city's pump test report for a new
well field near Lake Babcock,' which was used by EPA.
EPA Response As with many reports of this 'size and complexity,
there are some minor errors. The principal deficiency, in EPA',s
opinion, is that the pump test was not run until the observation
monitoring wells "reached equilibrium" (e.g. until the depths to
ground water, which drop while the pumping well is pumped,
stabilized or stopped dropping). However, EPA felt that the
primary, purpose of the pump test, to determine whether or not the
area south of Lake Babcock would produce enough water to serve
drinking water supply wells, was accomplished, and that it would
have been an inefficient use of federal money to repeat the pump
test at that time.
61. Comment A
new well field
than the north
be better as a
commenter stated that the south alternative for a
evaluated by the city would produce more water
alternative, near Lake Babcock and would therefore
source of municipal water.
EPA Response The point is now moot since no well 'field will be
, installed at either location as part of the remedial action.
However, since no pump test was performed at the south
alternative, it cannot be stated with certainty whether or not
more ground water could have been withdrawn at that location than
from near Lake Babcock. Pump tests are expensive, and are
generally only done at the location which is believed to be the
best alternative for a water supply.
62. Comment In the second public meeting, a commenter stated
that new information and data was provided to EPA, but he doubted
that a third public meeting would be held and doubted that EPA
would give the new information and data due consideration.
Another commenter stated in the second public meeting that he
wanted to see EPA'sresponses to the comments and questions
raised before EPA makes a decision selecting a remedial action.
-. .-.-..---....,
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48
I
EPA Response Generally, EPA holds a single public meeting for a
Proposed Plan on a Superfund site. EPA did, in fact, hold
another availability session on this site on December 7, 1994,
but did not hold a third public meeting. EPA took all of the
information it received during the public comment period into
consideration in selecting the remedial action for this site.
63. Comment In the second public meeting, a commenter stated
that he wanted to see EPA's responses to the comments and
questions raised before EPA makes the decision selecting a
remedial action for this site.
EPA Response As explained in the responses to earlier comments,
EPA cannot complete the Responsiveness Summary until it selects
the remedial action in the ROD, and. therefore also cannot respond
to individual comments until the ROD has been signed.
64. Comment Some commenters expressed concern with what they
characterized as a poor quality proposal and EPA's answers to
some of their questions. One commenter questioned whether EPA
had properly completed the hydrological studies and the cost
analyses. One of these commenters thought that EPA should go
back to the drawing board to develop another plan. The commenter
stated that there are some large sand pits less than five miles
west of columbus which are recharged with high quality ground
. water. The sand pits are not located near any industrial or
agricultural activity or development. The commenter expressed
surprise that EPA did not consider these large water bodies as a
source of municipal water.
EPA Response EPA feels.that the reports and other documents it
used to develop the remedial alternatives for this site,
including those plans prepared by EPA contractors, as well as
those done for the city, were of good quality and sufficient to
evaluate the alternatives for this site and provide the basis for
the preferred remedial alternative identified in the Proposed
Plan. The' hydrological studies completed or used by EPA were
sufficient to evaluate the remedial alternatives for the site.
EPA's cost analyses of the alternative were acceptable for this
stage of a process. Cost estimates are more finely tuned later
in a project after remedial design is completed.
Ultimately, new information on the city's compliance with
the SDWA and a significant reduction in the ground water
contaminant concentrations at the site, led EPA to select an
alternative (G-2, Monitoring and Institutional Controls with a
contingency for ground water extraction) other than the
alternative (G-5) EPA originally recommended in its Proposed
Plan.
65. Comment A commenter stated that a hydrologist from the
University of Nebraska at Lincoln described the drilling and
.. ~ .~- . ~.....
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49
stratigraphy studies of the proposed north and south sites (for
the well field) as sketchy, inadequate and not up to professional
standards.
EPA ResDonse Same response as for Comment No. 64 above.
66. Comment A commenter stated that state agencies and the city
would not specify the applicable regulatory requirements for
agricultural enterprises and residences located near the proposed
well field near Lake Babcock. The commenter stated that the
State was indefinite about the radius within which agricultural
and residential land and water uses may be effected. Some of
these factors bear a cost, which have not been included in the
costs of the alternatives calculated.
EPA ResDonse The point is now moot since no well field will be
installed in the Superfund remedial action. However, EPA does
not feel that the city or the state were being nonresponsive.
Rather, we feel that their responses reflected the complexity
many of the issues associated with a new well field.
67. Comment A commenter stated that some of the numbers used in
determining sustainability and output of the well field seem
arguable. The commenter said that a project with the cost of the
proposed well field should not have so many ambiguities at the.
stage when a final decision is being made. Some of the data.
problems cited by the commenter include what the commenter
believes is a mismatch between the recharge area and the aqu~fer
depth; what the commenter believes to be inadequate estimates for
water irrigation use; issues associated with possible
infiltration by Lake Babcock; the stratigraphy of the area; and
issues associated with peak plumbing demands.
EPA ReSDonse The point is now moot since no well field will be
installed under Superfund. However, if the remedial action had
included a well field, data on the issues raised by the commenter
would typically not be collected until the remedial design phase,
which is after the remedial action is selected in the,ROD.
68. Comment A commenter stated that the second public meeting
brought out the fact that the obvious option of removing water
from the Loup Canal and treating it had received no study as an
alternative. Thecommenter said another option would be to use
ground water from the vicinity of the sand pits a source of
municipal water, with conventional treatment for surface water
supplies.
EPA ReSDonse The point is 'now moot since a well field will not be
installed under Superfund. However, EPA did not recommend the
Loup Canal as a source of drinking water because of State water
rights issues.
- - .--.- -.. ...
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50
69. Comment A commenter stated that since the primary purpose of
EPA's involvement in the 10th street Site is to remove
contaminants from the ground water, alternative G-3 (ground water
collection and discharge to the Loup River) appears to be the
fastest and most effective way of reducing ground water
contamination and costs less. Another commenter objected to the
preferred alternative G-5 because he contended that:
a. the figures given to the public are not accurate,
b. the government wants to spend a lot more money than
necessary,
c. the government does not really want to remove the
contamination,
d. a hidden agenda is at work, such as the desire of the
city to get EPA to provide them a replacement well field.
EPA Response EPA did, in fact, e~aluate ground water collection
, to contain the contamination, as alternative G-3. Although not
originally recommended as the preferred alternative in the
Proposed Plan, EPA included a contingency in the ROD for
extracting contaminated ground water as part of the remedial
action selected for this site in the ROD.
70. Comment A commenter s~ated that the accuracy of the
scientific portion of the administrative record was poor and that
it resulted'in an insufficient cost analysis of the alternatives..
EPA Response EPA believes that the information it presented in
the Proposed Plan and RIfFS are of good quality and sufficient to
evaluate the costs of the alternatives being evaluated. There is
necessarily some uncertainty in the cost estimates at the
Proposed Plan stage. Cost estimates are more finely tuned for
the remedial alternative being implemented during remedial
design, after the ROP is signed selecting the remedial action.
71. Comment A commenter stated that the Proposed Plan co-minqles
dat~ from the city and EPA. .The commenter stated that .since the
city has a large interest in the remedial alternative selected by
EPA, the interests of EPA and the city should be clearly shown
and kept separate.
EPA Response EPA acknowledges that it used data from studies
funded by the city. EPA carefully evaluated the City's studies
and found them to be applicable and appropriate for the
Administrative Record for this site. If the city had not
performed these studies it wave been necessary for EPA to perform
similar studies. It would have been a waste of federal money to
unnecessarily replicate work already performed by the city.
EPA's use of the city's studies did not result in an
inappropriate overlap of the interests of EPA and the city.
Further, the results of the city's study are contained in a
document separate from the RIfFS.
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51
72. Comment A commenter asked what kind of studies have been
done to show that pumping the contaminated water into the Loup
River will not cause problems for someone else or contaminate the
fish taken from the river for consumption? The commenter stated
that fish are attracted to discharges of water into the river.
Since contaminant concentrations in the discharge water will be
higher than in the river water, will not this cause the fish to
be contaminated and lead to the consumption of contaminated fish?
EPA Response Under CERCLA and the NCP, EPA must meet the
regulatory criteria or standards of other federal or state
environmental programs or statutes. .If EPA extracts contaminated
ground water as part of the contingency contained in the ROD for
this site and discharges such water to the Loup River, the
discharge must meet the State water quality standards for the
contaminants of concern for the Loup River.. No discharges will
occur during the months of lowest water flow in the river. There
are other programs, separate from Superfund, in EPA and the NDEQ
which establish these standards.
73. Comment A commenter stated that the water level in Columbus
seems to be in many basements or just below and asked if Lincoln
obtains drinking water from the Platte River, why can't Columbus?
EPA Response The point is now moot since the remedial action
under Superfund will not provide municipal drinking water.. .
However, information in the RIfFS indicates that ground water was
a more efficient and cost effective alternative than surface
water as a source of drinking water. The use of surface water as
a source of municipal drinking water was not sufficiently viable
to survive the screening process for the alternatives retained
for more detailed analysis in the RIfFS.
74. Comment A commenter suggested that EPA consider the
following as a remedial alternative: Installation of a new well
field south of the city. . Although the cost would.be high, treat
the. water to the extent it is practical and use it for purposes
other than drinking. Include a large storage tank for drinking
water at a central location. and thus implement a permanent
solution to the contamination at this site. The commenter stated
that such an alternative would not be as costly or controversial
as the alternatives discussed in the Proposed Plan.
EPA Response The point is now moot sin~e a new well field will
not be included at either location in the Superfund remedial
action. There were several factors that made the north
alternative (near Lake Babcock) preferable to the south
alternative, including the likely greater ability to implement
well head protection and the fact that one water supply well
already existed at the north alternative site.
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75. Comment A commenter stated that the estimated costs of
treating the contaminated drinking water from the existing well
field (alternative G-4) indicate that alternative would be better
than EPA's preferred alternative (G-5) , especially if air
stripping costs for radon had been included in G-5. In the June
1993 public meeting, EPA indicated that the cost estimate for G-4
did not include treatment to prevent scaling. The commenter
inquired why such costs were not included in G-4? Also, why was
the cost of air stripping for radon not included in G-5?
EPA Response All of these points are now moot since the Superfund
remedial action will not include a new well field. Alternative
G-4 was rejected because, as this alternative was developed, it
appeared that the treatment of drinking water from the
contaminated well field would result in scaling to the degree
that eventually water could not be effectively delivered to all
of the homes or users in the city. There are some technologies
to control scaling and to remove the contaminants without
scaling. However,the technologies known to EPA appeared to be
exorbitantly costly and much more costly than any of the
alternatives evaluated in the Proposed Plan.
The cost of air stripping for radon in drinking water was
not included in G-5 because this is not required at this time
under the SDWA. Air stripping might have been added later if
this requirement was mandated under the SDWA for radon.
76. Comment A commenter asked what alternative sources of
drinking water were looked at and what were their costs?
EPA Response The point is now moot since the Superfund remedial
action does not include a new source of municipal drinking water.
For the record, only one potential source of drinking water was
evaluated in detail in the FS: the "north alternative" near Lake
Babcock. If the Superfund remedial action selected had included
a new well field this area would have been conf~~med as a source
of water. The purpose of the ROD fs to select a remedial action,
not to decide the particulars of that specific action (e.g. the
location of the well field for alternatives G-S and G-6) .
77. Comment A commenter asked where wells for a new municipal
well field would be placed and when drilling would begin?
EPA Response The comment is now moot since a well field is not
included in the Superfund remedial action. However, had the
alternative recommended in the Proposed Plan been selected as the
remedial action, most likely the wells would have been installed
south of Lake Babcock, although additional testing would have
been necessary during remedial design to confirm this. The
drilling of the wells would have been dependent upon weather but
could have begun within four to six months after the ROD
signature.
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78. Comment A commenter suggested that the municipal wells be
spread out so no one area is drastically affected by the ground
water withdrawals from a new well field. Alternately, the
commenter asked why EPA did not simply clean up the existing well
field and avoid the need for a new well field.
EPA Response The first point is now moot since the Superfund
remedial action does not include new drinking water wells.
However, it would have been impractical to locate the wells in
the manner described. To do. so would have required significantly
more,piping to convey the water, could have required additional
hydrogeologic testing and could have involved even more property
owners, all of which could substantially increased costs above
that associated with G-S, the alternative recommended in the.
. Proposed Plan. This could also have made well head protection
more difficult than if the wells were located near each other.
Cleaning up the contaminated drinking water was evaluated as
alternative G-4.
79. Comment A commenter stated that EPA's selection of the Lake
Babcock area as a source of drinking water was ill-advised. The
commenter further states that both Lake Babcock and Lake North
nave notoriously poor water quality. Water is prought in from
tens of thousands of acres, which is not bad in i~self, but the
chemicals and waste. that run into the lakes has deposited silt ,on
the lake bottoms for a number of years. 'The commenter stated
that the lakes were not sealed with bentonite, which may allow
contaminants from the lake to leak into the underlying ground
water and contaminate well water, especially since a new well
field would remove more of the ground water from the aquifer.
The commenter went on to state that the lake water is caustic
enough to corrode irrigation equipment within a few years. The
commenter suggested that as an alternative to a well field south
of Lake Babcock, EPA consider a well field north of Lake Babcock,
because extracting ground water from that area could eliminate an
existing problem in this area of wet basements. Currently, some
residents in the area must now pump water out of their basements
and then treat this water prior to discharge.
EPA Response The point is moot since EPA will not be installing a
new well field under Superfund. However, the,ground water south
of Lake Babcock was tested and found, on a preliminary basis,
sufficient in ,quality as well as quantity for use by the city for
drinking.
80. Comment A commenter asked how much land would be purchased
from landowners for a new well field and inquired how the costs
of the different alternatives could be compared when the
potentially significant land acquisition costs have not been
considered? The commenter has 120 acres of cropland which he
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54
says would be negatively impacted and ruin their farming
operation if they can no longer operate their center pivot
irrigation system fed by an irrigation well. Another commenter
stated that land acquisition costs were not assessed for the
alternatives which included a new well field, G-5 and G-6.
EPA Response The point is moot since EPA will not be installing a
new well field under Superfund. However, if the alternative
recommended in the Proposed Plan had been implemented, . land
acquisition would probably have been the responsibility of the
City of Columbus under a contract with EPA or with EPA and the
State. The actual amount of land purchased would have been
relatively small, probably only a few acres. However, some
degree of control over.a larger amount of land would have been
sought in negotiations with those property owners as a well head
protection activity. The land actually purchased would only have
been enough to include the actual municipal water supply wells
and associated structures. Finally, land acquisition costs were
considered in the development of the alternatives involving a new
well field, G-5 and G-6.
81. Comment A commenter, who lives about a mile north of the
proposed 'well field, stated that although the Proposed Plan might
be acceptable to address the feasibility of a new well field near
Lake Babcock, it incompletely addresses other relevant factors.'
The commenter states that any municipality. has the right to' .
protect its source of drinking water and expects that some sort
of well head protection zone would be established if a new well
field were installed. The commenter said that EPA has identified
neither the dimensions of the exclusion zone, nor the
restrictions on the activities of nearby landowners.
EPA Response The point is now moot since a new well field will
not be installed by EPA under Superfund. However, the
uncertainties identified relate to matters which EPA.could not
have answered until later 'in the project after some of the
.remedial design had been completed. '
82. Comment A commenter suggests that EPA and the city look
south of town for municipal water and stated that they moved
north of the city to get away from city regulations.
EPA Response The point is now moot since a well field will not be
included in the Superfund remedial action. ,As stated previously
in response to earlier comments above, there were several
advantages for the north alternative, (near Lake Babcock) over the
south alternative. However, if the ROD had selected a new well
field as part of the remedial action, the final decision on
locating the wells would not have been made until additional
testing was done after the ROD.
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83. Comment A commenter states that t~e city should be
resPQnsible if the commenter's wells go dry from the pumping at a
new well field.
EPA Response The point is now moot since EPA will not be
installing a new well field under Super:und. If a new well field
had been selected this would have been a matter between the
landowners and the city, as the operator of the water supply.
84. Comment Several commencers asked why the landowners living
in the vicinity of the proposed well field were not given equal
consideration to the propercy owners served by the municipal'
water supply system?
EPA Response EPA did in fact consider the degree of landowner
opposition to a new well field. In fact community acceptance is
one of the nine criteria identified in the NCP for evaluating
remedial alternatives.
85. Comment A commenter asked if a new well field and
availability of municipal water causes homes in the area where
the well field was proposed to have to hook up to municipal water
who would pay these costs? Also, if it has been known for
several years that the existing municipal well field i~
contaminated, why did it take so long to resolve the problem?
The commenter,stated that it seems that time is now running out
and a quick ,solution is now required because of the past delays
and asked why cannot the city install a system to remove the
contaminants from their existing well field? The commenter also
wanted to know what alternatives were available to rectify the
contamination of the existing well field before this
contamination occurred?
EPA Response The point is now moot since a new well field was not
selected as the Superfund remedial action. However, th~ EPA
Superfund program would not have required anyone to hook up ~o
the municipal supply. EPA assumes that'anyone choosing to hook
UP to the municipal supply would pay the costs, but EPA would
have no role in such matters~ ' The original source of the
contaminants found in the drinking water has not been
conclusively identified.
86. Comment A commenter, who had read the summary report in
administrative record, concluded that G-4 appeared to be the
alternative since it met the following objectives:
a. overall protection of human health, welfare and the
environment,
b. complied with ARARs,
c. high long-term effectiveness,
d. only moderately difficult to implement, and
e. moderate present worth cost.
the
best
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56
Another commenter agreed and went on to state that the only
advantage of G-5 was that it could be readily implemented. This
commenter stated EPA claimed that the costs of G-4 were higher
because of 'additional treatment that would be required to control
scaling. However, he said that EPA did not quantify these costs.
EPA Response The point is now moot because a well field was not
selected as the Superfund remedial action. Moreover, based on
the information in the RIfFS, it is EPA's position that scaling
would have been a significant problem with alternative G-4 as
described in the Proposed Plan, and might ultimately prevent the
effective distribution of drinking water. As noted above, there
are technologies which might be used to control or prevent the
scaling. However, all such technologies known to EPA appeared to
be much more costly than any of the six alternatives 'identified
in the Proposed Plan.
87. Commenc The same commenter who made many of the same points
outlined in comment no. 35 about the levels of iron and sulfur in
the water at the nearby community college went on to state that
EPA said G-4 would be more expensive than G-5 , but thatEPA did
not take into consideration that the water may need to be air
stripped fer radon removal which would make G-S more expensive.
The.commenter stated that the pumping test was conducted without
consideration of the seasonal pattern'of water use. The. state
. reported that Lake North water is of a very high quality. The
commenter ask why was not Lake North as a source of municipal
water considered as a remedial alternative?
EPA Response The point is now moot in view of the alternative
selected as the remedial action. For the record, the qround
water south of Lake Babcock was tested and found sufficient in.
quality and quantity for use as municipal drinking water. EPA
did not do any specific testing of Lake North as a source of
municipal drinking water, because none of the lakes in the
Columbus area appear to contain enough water to meet the needs of
the city. It was the aquifer beneath Lake Babcock, not Lake
Babcock per se, that was proposed as a source of municipal,
drinking water. Finally, there is not yet a requirement under
the SDWA that public water supplies be treated for radon removal,
nor has an MCL for radon yet been established.
88. Comment A commenter stated that when quest{ons were brought
up during the public meeting concerning the "facts" in the
administrative record, the audience was told that these "factsll
were not. altogether true. He. said he found this confusing and
asked who had the facts?
EPA Response Possibly, EPA could have been more effective in
explaining some of the complex issues involved in this matter.
All of the facts or information upon which EPA based its decision'
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selecting a remedial action for this site are found or referenced
in the Administrative Record.
89. Comment A commenter asked if locating a well field near 38th
Street had been considered and stated that the water level in
that area was so high that it is a problem for area home owners.
The commenter suggested that water from this area be used for the
city's needs. The commenter stated that even if water treatment
was required, the costs could still be competitive over the long
term with a new well field, because there is no guarantee that
treatment may not also eventually be required for water from a
new well field.
EPA Response EPA did not specifically evaluate locating a well
field near 38th Street. The decision made in the ROD was to
select a remedial action for the site. Two of the remedial
alternatives evaluated in the Proposed plan included a new well
field. Had a new well field been selected as the remedial action
for this site, the actual loc.ation would not have been decided
until later in the project during remedial design, which comes
after the ROD is signed. .
90. Comment A commenter stated that the u.S. Department of
Agriculture told them that restrictions might be imposed on
activities at their property, which is 300 to 400 feet from the
. existing municipal well near Lake Babcock. Therefore, the.
commenter suggested that the additional municipal wells be
located ~-mile west of the existing well, east of .the community
college and west of 33rd Avenue. Wells located there could take
benefit of a buffer zone for wellhead protection of Lake Babcock
to the north, the college campus to the west, and grassland and
only a few homes to the south. The commenter also suggested that
the city consider a golf course be used for the land located
between the well field wells, since the existing golf course is
located on top of a dump site and in a floodplain.
EPA Response'The point is now moot since no new well field is
part of the remedial action selected. However, EPA agreed that
if a new well field were to be installed as part of the Superfund
remedial action, that it probably made sense to put the wells
near the city's single water supply well already located near
Lake Babcock. EPA also agrees that a golf course might be a land
use which would pose little risk of contaminating the drinking
water wells, as long as excessive or inappropriate use of lawn
. chemicals did not occur. Excessive chemicals use at golf courses
is believed to have contaminated ground water in other areas.
91. Comment A commenter asked if the ground water in the
existing well field is still being polluted and who is
responsible for that contamination. The commenter also inquired
of EPA plans to ensure that this pollution is stopped and to
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repair the damage (to the existing well field and municipal water
,supply) t~at has already occurred.
EPA Response No one can answer these questions with certainty.
It appeared unlikely to EPA that there was a continuing, or even
recent, release of hazardous substances which contaminated the
existing well field. In fact the more recent data on the ground
water from the monitoring wells show lower levels of
contamination than the samples collected during in the RIfFS.
92. Comment A commenter expressed doubts that the water table
would only drop four feet and that water levels in Lake Babcock
and Lake North would be unaffected if all 4 wells in a new well
field were pumped daily. '
EPA Response The point is now moot since no well field will be
installed by EPA as a Superfund remedial action. However, EPA's
review of the available data indicated that it was very unlikely
that any existing water supply (irrigation or domestic) would go
dry as a result from pumping at a new well field.
93. Comment A commenter suggested that the contamination of the
existing well field be addressed rather than installing a new
well field.
EPAResponse In fact, ,this was the alternative evaluated as G-3
in the Proposed Plan. When EPA released its Proposed Plan, it
was our understanding that the City of Columbus was in violation
of the SDWA. However, it has now been determined that the city
is in compliance with that act. This was one of the reasons why
EPA did not select a new well field as the Superfund remedial
action. EPA has identified a contingency for the extraction of
contaminated ground water in the remedial action selected for
this site.
94. Comment A commenter stated that if water supply wells could
be located closer to the existing drinking water treatment plant, ,
then the transmission line cost from Lake Babcock to the
municipal water treatment could be 'half the estimated $1,721,000.
The cornrnenter stated that additional costs could be eliminated by
not having to acquire land and or replace or repair dry wells.
If land were to be purchased in the implementation of the'
preferred alternative, the commenter's center pivot irrigation
system could be affected.
BPA Response The point is now moot' since the Superfund remedial
action will not include a new well field. However~ it did not
appear that areas closer to town than the area south of Lake
Babcock were as likely to produce as much water. Again, EPA
would not have made the final decision on where a well field
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.
would have gone in the ROD. The decision as to the location of
the wells would not have been made until during remedial design,
after the ROD.
95. Commen~ A commenter stated that it is hard to understand
EPA's estimate of G-4 costing $10,000,000 because of scaling,
instead of the $1,697,859 estimate in the Proposed Plan. The
commenter also noted that he was told that the city had already
spent about $300,000 on testing and study for a new well field
and concludes little of value was obtained.
EPA Response The costs of measures to control scaling in .
alternative G-4 were not quantified because the costs appeared so
great as to make that alternative substantially more costly than
any of the other alternatives.. EPA does not agree that the
City's pump test was a waste of money and that nothing was
learned. :~ EPA's opinion, the main purpose of the city's pump
test was accomplished, in that the data from that test show that
the area south of Lake Babcock appears to have enough ground
water to meet the needs of the municipal drinking water supply.
96. Comment A commenter who lives one mile southeast of the
proposed well field asked, since Superfund cannot pay for damages
to his well water quality, then should not the potential
replacement costs (of his and other existing private wells
affeGted) have been included in the alternatives including a new
well field? The commenter asked if complete studies of alternate
sites for a well field were completed, who completed such
studies, and questioned whether or not the conclusions of such
studies were truly objective.
EPA Response The point is now moot since a new well field is not
included i~ the Superfund remedial action. EPA determined that
it could nc~ replace wells which, might go dry, because .this would
not be a response to a release of a hazardous substance. As
noted before, the location of a new well field would not have
been selected until after. remedial design. The information in
the adminis~rative record is objective and unbiased.
97. Comment A commenter stated that G-3 appears to be the most
effective, fastest, and least costly of the alternatives
considered and suggested that a preference for G-5 reveals a
hidden agenda. The commenter asked whether or not there were any
other discussions among local, state and federal agencies with
respect to other potential benefits of locating a wellfield near
Lake Babcock. The commenter asked why EPA used city data without
identifying it as such. . .
EPA Response There were some advantages, as the commenter
suggests, to G-3. However, G-.3 was not recommended in the
Proposed Plan, because, based upon the information available when
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the proposed plan was released it appeared that it would take
much longer under G-3 for the contamination in the drinking water
supply to be reduced to safe levels than in G-5, the alternative
recommended.in the Proposed Plan. EPA met with the city, but the
purpose of such meetings was to learn more about the city's
operation of its water supply. The nature of these discussions
between -EPA and the city was not such that data or information
was made available to the city and not to the general community
in columbus.
EPA did, in fact, acknowledge that data generated by the
city was used in the development of the Proposed Plan. Finally,
EPA has identified a contingency for extracting contaminated
groundwater in the remedial action selected for this site. This.
contingency was presented as alternative G-3 in the Proposed
Plan. .
97. Comment A commenter asked why the community relations plan
only allowed one week for notifying the community of a public
meeting when the contamination was discovered over ten years ago.
EPA Response The contamination in the municipal water supply
wells has been a matter of public record for several years and
has no bearing upon EPA's notification policy for public
meetings. Public meetings and availability sessions ,are.
scheduleq throughout the Superfund process when required by
statute or when requested by the community. 'One week is more or
less standard for the amount of notice for public meetings. When
EPA found the interest in the community was sufficient, and that
some of the community concerns were not initially fully
addressed, we agreed to hold an additional public meeting and
availability sessions.
98. Comment A commenter stated that at a public meeting, EPA
said that a transcript of the meeting would be sent to the
attendees. The commenter, asked whether EPA can make a final.
recommendation on July 5, 1993 if the attendees have not received
the transcript and if they have not had their questions answered.
EPA Response EPA did not commit to send out the transcript to
everyone on the mailing list before it signed the ROD. EPA did
agree to send this Responsiveness Summary, with the transcripts
attached, to everyone on the mailing list. However, we could not
complete the Responsiveness Summary until after we selected the
remedial action in the ROD. Finally, a copy of the public
meeting transcripts was placed in the administrative record in
the information repository (the Columbus Public Library) along
with this ROD.
99. Comment A commenter states that in the past 5 years BPA has
placed many restrictions on American farmers. If BPA believes
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farmers are causing environmental pollution, then why does EPA
propose to locate municipal wells in an area currently used to
grow row crops? The commenter stated that Columbus, and other
cities do most of the environmental destruction, and they are the
ones who should be restricted, not farmers.
EPA Response The discussion of restrictions was a reference to
well head protection for a new well field, which is a voluntary
program in Nebraska. Since a new well field is not included in
the remedial action selected for this site, this is largely a
moot point. Some water suppliers have found it necessary to
protect their wells from contamination from agricultural
chemicals, agricultural practices, industrial chemicals and
manufacturing and other storage facilities. These factors must
be considered in well head protection.
100. Comment Some commenters who live near'the existing well
field state that they now understand that their municipal water
supply uses 5 contaminated wells. . Commenters state that safe
municipal drinking water should be a priority.
EPA Response EPA agrees that safe drinking water is a priority.
It has been determined that the city is in compliance with the
SDWA.
101. Comment A commehter stated that the State reported Lake
North water is of a very high quality, and yet this lake was not
considered as a source of municipal drinking water in the
Proposed Plan. Why was this option not considered?
BPA Response The point is now moot since a new well field is not
part of the remedial action selected. However, the primary
purpose or the ROD is to select the remedial action. Many of the
details relating to the implementation of the remedial action,
such as the location of a well field, are not finalized until
after'remedial design.. It appeared likely to EPA that a new well
field would have been located south of Lake Babcock because a
pump test had already been conducted showing that area had ground
water sufficient in quantity and quality to serve a municipal
well field. FUTthermore, since the city already had one water
supply at that location, it would probably have been more
efficient and less costly than other areas as a source of water.
102. Comment A commenter asked whether the aesthetic effects and
lowered property values had been considered if a lowered water
table causes a lake in a subdivision to'dry up.
BPA Response The comment is now moot since a well field is not
included in the Superfund remedial action. EPA believes it is
very unlikely that Lake North would have gone dry. Compensation
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.
for any wells that may have gone dry as a result of a new well
field would have been beyond the scope of this Superfund remedial
action.
103. Comment Several commenters stated that the Proposed Plan
contains only a summary of the costs of each remedial alternative
with no itemization or specific breakout of the costs included in
each alternative.
EPA Response Additional information on costs is contained in the
feasibility study which is found in the Administrative Record.
Additional cost information will be obtained after the Record of
Decision on the remedial alternative implemented as part of
remedial design.
104. Comment A commenter asked if property owners near the
proposed well field would be allowed to drill new wells for their
use after a well field is installed.
EPA Response The point is moot since the Superfund remedy does
not include a new well field, but EPA would not have attempted to
prevent any new domestic wells from being drilled in the area.
State regulations control the drilling of any new large capacity
(e.g. irrigation or industrial production) wells within a certain
distance from municipal drinking water supply wells.
105. Comment A commenter asked why well fields are generally
located near surface water bodies. Is it because the surface
water tends to recharge the underlying aquifer? If so, and if
Lake Babcock is sealed, would not this limit the amount of
recharge and the suitability of that area as a well field?
EPA Response Surface water bodies do tend to recharge aquifers.
Actually, the level of lake and river water represents a
potentiometric surface corresponding with the depth to ground
water (the water table). A sealed lake bottom tends to reduce
the aquifer recharge. Noneth~less, a pump test done south of
Lake Babcock showed that enough ground water could be withdrawn
to serve the needs of the municipal drinking water supply.
106. Comment The City of Columbus has expressed a desire for a
n~w municipal well field to be funded by EPA under Superfund.
EPA Response A new well field was included in the remedial
alternative originally recommended by EPA in the Proposed Plan.
However, significant developments have occurred since EPA's
release of the Proposed Plan. In particular, a "determination has
been made that the municipal water supply has been in compliance
with the SDWA. Therefore, Alternative G-2, Institutional
Controls and Monitoring, which was deemed not protective when the
Proposed Plan was released in April 1993, is now protective given
the municipal water supply's continued compliance with the SDWA.
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As a result, alternatives including a new well field. are no
longer appropriate as the remedial action for this site using the
nine criteria identified in Section 300.430(e) (9) of the NCP for
selecting remedial actions.
107. Comment The NDEQ has stated that the City of Columbus has
stopped using certain municipal water supply wells as a source of
public drinking water because of contamination by TCE and PCE.
NDEQ stated that the Superfund remedial action should replace the
water supply capacity lost by these wells.
EPA Response Over the years the city ha$ stopped using several of
their water supply wells for a variety.of reasons, including but
not limited to contamination by TCE and PCE. Nonetheless, the
city has still been able to comply with the SDWA for, the last two
years and to provide sufficient quantities of water to meet the
needs of homes and other users of municipal water in Columbus.
In addition, the concentrations of TCE and PCE in some of the
currently unused municipal wells may now De low enough that the
city could consider bringing some of those wells back on-line as
a supplemental source of drinking water.
108. Comment NDEQ and NDOH have both expressed concerns that the
levels of contamination in the municipal drinking water supply
might increase in the future, which could. lead to unacceptable
levels of risk for the people drinking and using the water from
that supply. ND~Q and NDOH were also concerned that such risks
could be addressed i~ a timely manner.
EPA Response Under the SDWA the City of Columbus continues to
have primary responsibility for safety of its public water
supply. In addition, were it to become necessary, EPA could
amend this ROD to address such risks and/or use its removal
authority under. Section 104 of CERCLA. EPA decisions to
undertake removal actions are based upon the eig~t removal
criteria found in Section 300.415(b) (2) of the NCP and upon
. information available at that time. ... .
also
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GLOSSARY OF TERMS ~~D ACRONYMS AND ABBREVIATIONS
FOR THE RECORD OF DECISION AND RESPONSIVENESS SUMMARY ON
TENTH STREET SITE, COLUMBUS, NEBRASKA
CERCLA- Comprehensive Environmental Response, Compensation and
Liability Act, commonly referred to as the "Superfund Law".
EPA- Environmental Protection Agency: the federal agency charged
with implementing most parts of Superfund.
HRS- Hazard Ranking Score: a numeric ranking assigned to sites
based upon information. available about .the site, used to
determine whether or not the site will be placed on the NPL.
MCL- maximum contaminant level: the highest level of a
contaminant acceptable in a public drinking water supply.
that not all contaminants have an MCL.)
(Note
ug/l- Microgram per liter, a unit of measurement for liquids such
as water and equivalent to a part per billion (ppb).
ug/kg- Microgram per kilogram, a unit of measurement for solids
. such as soil and equivalent to a part per billion (ppb).
mg/kg- Milligram per kilogram, a unit of measurement for solids
such as soil and equivalent to a part per million (ppm).
NCP- National Contingency Plan: the Superfund regulations.
NDEQ- Nebraska Department of Environmental Quality: EPA's state
counterpart under Superfund.
NDOH- Nebraska Department of Health: EPA's state counterpart
under the SDWA, also does risk assessments for EPA under
Superfund. .
NPL- National Priorities List: EPA's list
sites being addressed under Superfund and
high enough to make the site eligible for
remedial, actions.
of most significant
sites whose HRS was
long-term response, or
RI/FS- remedial investigation/feasibility study: the basic
investigation conducted by EPA or the state or by responsible
parties on a Superfund site. The nature and extent of
contamination is characterized in the RI. Potentially applicable
remedial alternatives for cleanup are developed and evaluated in
the FS.
ROD- Record of Decision: the document in which EPA selects the
remedial action for a Superfund site.
.. ... '-_u."
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65
RS- Responsiveness Summary: released as a portion of, or attached
to, the ROD. The RS addresses the verbal and written comments
received on the Proposed Plan for a Superfund site.
SDWA- Safe Drinking Water Act: the federal law regulating public
water supplies. Public supplies are defined as those supplies
with fifteen or more connections or which regularly serves
twenty-five or more people with drinking water.
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ATTACHMENT A
GLOSSARY OF EVALUATION CRITERXA
The following criteria were developed by EPA to address
CERCLA statutory requirements and technical, cost, and
institutional considerations. The evaluation criteria serve as
the basis for conducting detailed analyses during the FS and for
subsequently selecting an appropriate remedial action.
OVERALL PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
Alternatives are assessed to determine if they can provide
adequate protection' from risks above health-based levels posed by
contamination present at the Shaw Avenue Dump Site by
eliminating, reducing, or controlling exposures.
COMPLIANCE WITH ARARs
.
The alternatives are assessed to determine if they attain
applicable or relevant and appropriate requirements (ARARs) or
comply with other federal and state environmental and public
, health laws, or provide grounds for invoking a waiver.
LONG-TERM EFFECTIVENESS AND PERMANENCE
The magnitude of risk remaining after implementation of the
alternatives is evaluated. The adequacy and reliability of
controls used to manage treatment residuals or untreated wastes
that remain at the Shaw Avenue Dump site are also assessed. '
REDUCTION OF TOXICITY, MOBILITY, AND VOLUME THROUGH
TREATMENT
The degree to which the alternatives employ treatment that
reduces toxicity, mobility, or volume through treatment is
assessed.
SHORT-TERM EFFECTIVENESS
The alternatives are evaluated regarding their effects on
human health and the environment during implementation of the
alternative. The amount of time until protectiveness is achieved
is also an assessment factor. '
IMPLEMENTABILITY
The technical and administrative feasibility of implementing
an alternative and the availability of services and materials
required to implement an alternative are evaluated.
. ".--."':'--... ...' -. "...., ." .
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COST
Direct and indirect capital costs and operatiQn and
maintenance costs incurred over the life of the project are
identified.
STATE ACCEPTANCE
Technical and administrative issues and concerns the state
may have regarding the alternative are assessed.
COMMUNITY ACCEPTANCE
The issues and concerns of the public regarding the
alternatives are assessed.
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,ATE OF NEBRASKA
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