United States Office of
Environmental Protection Emergency and
Agency Remedial Response
03&>
EPA/ROD/R07-90/«4+
September 1990
Superfund
Record of Decision:
Lindsay Manufacturing, NE
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REPORT DOCUMENTATION
PAGE
1. IWOHTMQ.
EPA/ROD/R07-90/041
1 Rod«tenr« AccMttan No.
t. fbportOMi
SUPERFUND RECORD OF DECISION
Lindsay Manufacturing, NE
First Remedial Action - Final
9/28/90
*. fertomting OrginiBtfon Rtpl. No.
I. riitnnnlno ~rj»inlii
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EPA/ROD/R07-90/041
Lindsay Manufacturing, NE
First Remedial Action - Final
Abstract (Continued)
already underway as a result of the interim action. The primary contaminants of concern
affecting the soil and ground water are VOCs, including PCE; and metals including
chromium and lead.
The selected remedial action'for the site includes vacuum extraction of volatile organic
compounds from soil, followed by a carbon adsorption filter system before vapor
emission, with full-scale implementation based on the results of a pilot study; onsite
pumping and treatment of ground water using precipitation and flocculation, followed by
sedimentation of the flocculant, with onsite discharge to surface water, and disposing
of dewatered solid residuals offsite at a local landfill. The estimated present worth
cost for this remedial action is $3,006,600, which includes an annual O&M cost of
$636,000 for 5 years.
PERFORMANCE STANDARDS OR GOALS'; cleanup levels are based on the more stringent of
either SOWA MCLs or State regulations. These levels will reduce lifetime cancer risks
to between 10 4 and 10 6 for carcinogenic compounds, and the hazard index (HI) to less
.than 1 for non-carcinogens. Chemical-specific ground water cleanup goals include PCE 5
ug/1 (proposed MCL), chromium 0.05 mg/1 (MCL), and lead 0.05 mg/1 (MCL). Specific
cleanup levels for soil were not provided.
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RECORD OF DECISION
LINDSAY MANUFACTURING COMPANY
LINDSAY, NEBRASKA
SEPTEMBER 1990
Prepared by
THE U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION VII
KANSAS CITY, KANSAS
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LINDSAY MANUFACTURING COMPANY SUPERFUND SITE
RECORD OF DECISION DECLARATION
SITE NAME AND LOCATION
Lindsay Manufacturing Company Site
Lindsay, Nebraska (Platte County)
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action
for the Lindsay Manufacturing Company site, in Lindsay, Nebraska,
chosen in accordance with the Comprehensive Environmental
Response, Compensation and Liability Act of 1980 (CERCLA), as
amended by the Superfund Amendments and Reauthorization Act of
1986 (SARA), 42 U.S.C. § 9601 e£ sea.. and, to the extent
practicable, the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP), 40 CFR Part 300.
This decision is based on the administrative record for the
Lindsay Manufacturing Company site.
The United States Environmental Protection Agency (EPA) and
the State of Nebraska (Department of Environmental Control -
NDEC) agree on the selected remedy.
ASSESSMENT OF THE SITE
The actual or threatened release of hazardous substances at
or from this site, if not addressed through the implementation of
the response action selected in this Record of Decision (ROD),
present an imminent and substantial endangerment to public
health, welfare, or the environment.
DESCRIPTION OF THE SELECTED REMEDY
The .Remedial Investigation/Feasibility study (RI/FS),
conducted by the Lindsay Manufacturing Company from January 1989
to August 1990 at the Lindsay Manufacturing Company site,
identified ingestion of contaminated ground water and/or
inhalation of contaminants released during use as a principal
threat to residents living near the site.
In addition, available data shows elevated concentrations
("hot spots") of volatile organic compounds in soils as a
principal threat to the ongoing contamination of ground water.
Detectable levels of zinc, cadmium, lead, iron and sulfate
have been identified in the ground water. Organic contaminants,
including dichloroethylene, tetrachloroethylene and
trichloroethane have bean detected in the ground watar. These
organics have been detected on-site in the soils in the central
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drainage ditch, near the northeast corner of the main plant
building, and in the central northern portion of the site.
This remedy will address the principal threat posed by the
contaminants in the ground water by restoring the ground water to
acceptable quality (Safe Drinking Water Act Maximum Contaminant
Levels-MCLs and State of Nebraska cleanup levels established
under Title 118, Ground Water Quality Standards and Use
Classification) by the extraction and enhanced treatment of
contaminated ground water. In addition, the remedy may reduce
the threat of continued contamination of the ground water from
the soil source areas if vapor extraction of volatile organic
compounds from the soils proves practicable.
The major components of the selected remedy for the affected
ground water and soil include the following:
o A pilot study to evaluate the practicability of vacuum
extraction of organic compounds from contaminated soil.
o If determined to be practicable by EPA and/or NDEC,
design and implementation of full scale soil vapor
extraction system based on pilot study data.
o Enhancement of the existing ground water extraction and
treatment system by either increasing the volume of on-
site pumping from the existing extraction wells or by the
installation of an additional interceptor (extraction) well.
o • Utilization of the existing ground water treatment
facility to remove contaminants from the collected
ground water.
o Installation of additional ground water monitoring
wells near irrigation well #54278 to further delineate
the ground water contaminant plume.
o The monitoring of the ground water collection/treatment
system and the ground water contaminant plume during
, ground water remediation activities.
o If appropriate to protect human health, EPA and NDEC
will evaluate options, as part of implementation of the
ROD, to ensure that drinking water wells are not
installed in areas of the contaminant plume on and off
site.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the
environment, complies with Federal and State requirements that
are legally applicable or relevant and appropriate to the
remedial action, and is cost-effective. This remedy utilizes
permanent solutions and alternative treatment (or resource
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recovery) technologies to the maximum extent practicable, and
satisfies the statutory preference for remedies that employ
treatment that permanently and significantly reduces toxicity,
mobility, or volume as a principal element. Because this remedy
nay result in hazardous substances remaining on-site above levels
that allow for unlimited use and unrestricted exposure, a review
will be conducted no less often than every five years after
commencement of remedial action to ensure that the remedy
continues to provide adequate protection of human health and the
environment.
Subject to the outcome of the pilot study, the agency will
consider reopening the ROD or amending the ROD if warranted,
otherwise the agency will proceed with the selected remedy. If
soil vapor extraction is determined not to be practicable, the
Agency will consider an additional study to evaluate other
treatment or source control technologies to reduce or eliminate
the source(s) of contaaination to ground water.
Mortis Kay Date
Regional Administrator
U.S. EPA - Region VII
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- • -'
ATE OF NEBRASKA
DEPARTMENT OF ENVIRONMENTAL CONTROL
KAY A. ORR
GOVERNOR
September 21. 1990
DENNIS CRAMS
DIRECTOR
•>
r
SE° ,? ' 1990
ADMINISTRATOR
CC -
Mr. Morris Kay
Regional Administrator
EPA Region VII
726 Minnesota Avenue
Kansas City. Kansas 66101
Dear Mr. Kay:
Upon consideration of the Administrative Record and the draft Record of
Decision (ROD), the Nebraska Department of Environmental Control (NOEC) concurs
with the Environmental Protection Agency's remedy selection for the Lindsay
Manufacturing Company Superfund site.
NOEC understands that the selected remedy will provide enhancement of the
current pump and treat system to remove organic and inorganic contamination in
the groundwater which poses a threat to human health and the environment. In
addition, the selected remedy will include a pilot study to determine the
practicability of soil vapor extraction to treat soils contaminated with
volatile organic compounds. The selected remedy will meet all state
requirements.
NOEC appreciates the opportunity for oversight of the RI/FS and input
during the remedy selection process. NOEC also appreciates the support of EPA
during the oversight activities.
Dennis Grams. P-E.
DG/RJ/ls
RECEIVED
SEP 1 ? 1990
SECTION
P.O. BOX 99922, LINCOLN, NEBRASKA 69509-8922. PHONE (402)471.2186
AN EQL'AL OPPORTUNITY'AFFIRMVTIVF ACTION FMPIOVFR
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TABLE OF CONTENTS
SECTION TITLE PAGE
DECLARATION i
I. SITE NAME, LOCATION, AND DESCRIPTION 1
A. Location and Address 1
B. Area and Topography of Site 1
C. Adjacient Land Uses 1
D. Surface and Subsurface Water Resources 2
E. Surface and Subsurface Features 3
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES 3
A. Site History 3
B. Interim Remedial Acitons 4
C. NPL Listing 5
D. Remedial Investigations 5
III. HIGHLIGHTS OF COMMUNITY PARTICIPATION 6
IV. SCOPE AND ROLE OF RESPONSE ACTION 7
A. Role of Remedial Acton in Site Clean Up Strategy 7
B. Scope of Problem Addressed 8
V. SUMMARY OF SITE CHARACTERISTICS 9
A. Soil* 9
B. Ground Water 11
C. Contaminant Fate and Transport 13
VI. SUMMARY OF SITE RISKS 13
A. Human Health Risks 13
B. Environmental Risks 18
VII. DESCRIPTION OF ALTERNATIVES 19
VIII. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 26
IX. SELECTED REMEDY 30
X. STATUTORY DETERMINATIONS 33
XI. RESPONSIVENESS SUMMARY 36
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I. SITE NAME, LOCATION AND DESCRIPTION
A. Location and Address
The Lindsay Manufacturing Company facility (the "site") is
located in the village of Lindsay, Nebraska, in Platte County.
The site is located in the southeast quarter of the southwest
quarter of Section 17, Township 20 North, Range 3 West, Platte
County, Nebraska (Figure l-l). The Village of Lindsay lies on
the east boundary of the Nebraska sandhills and the local region
is characterized by rolling and dissected loess plains. The site
is surrounded on the north and east by farmland and on the south
and west by the village of Lindsay.
B. Area and Topography of Site
The site occupies approximately 42 acres and has been
selectively leveled and stabilized. Drainage swales have been
filled and some surfaces paved for transportation and equipment
storage. A loessal slope on the east half of the site has been
locally incised for construction of the maintenance and final
production buildings (Figure 1-2).
The site is approximately 1,300 feet long (north to south)
and the width ranges from approximately 1,570 feet at the north
end of the property to 1,100 feet at the south end. The surface
gradient across the property drains to the vest and ranges
from .023 ft/ft in the central drainage channel to .053 ft/ft
across the south property boundary. The site is situated in a
relative topographic low created by Shell Creek and its tributary
drainages. The average elevation of the site is approximately
1,670 feet above mean sea level, and local relief ranges from
1,650 to 1,800 feet above mean sea level.
C. Adjacent Land Uses
The site is bounded on the north by farmland, on the east by
Lindsay town limits and farmland, on the south by State Highway
91 and a residential area of Lindsay, and on the west by a
tributary to Shell Creek, its greenbelt and a residential area of
Lindsay. The drainage channel is dry, except during storm runoff
and when receiving plant vastevater discharge.
Total population of Lindsay, Nebraska in 1980 was 383
people. Results from the Natural Resources Commission in
conjunction with the Census board state an average population of
392 for the years 1908 through 1986. The population center is
located within 0.3 miles vest and south of the Lindsay
Manufacturing western property boundary. Three schools serve the
Lindsay area. One public elementary school has an average
enrollment of 35 students. A second public elementary school has
an average enrollment of 151 students. The high school is
private and has an average enrollment of 109 students. The high
school and elementary schools are located approximately 0.25
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miles west of the site boundary. No hospitals, clinics or
retirement centers are known to exist within a two mile radius of
the site.
Land use within the city limits is primarily residential
with the exception of the Lindsay Manufacturing site and a
community business and general commerce area located southwest of
the site. A public recreational and utilities area is located
approximately 0.2 miles southwest of the site. The utilities
area consists of the town public sewage treatment plant and
ponds. Use of the area located within a two mile radius of the
Lindsay town limits is primarily agricultural with an average of
three farmsteads per square mile.
The following federally listed threatened and endangered
species may occur within 3 miles of the site:
Listed Species Expected Occurrence
Bald Eagle (Haliaeetus leucocephalus) Migration
Peregrine Falcon (Falco peregrinus) Migration
Western Prairie Fringed Orchid Tall-grass prairie or
(Platanthera praeclara) meadow with high water
table
There is no critical habitat within 3 miles of the site.
Both Shell Creek and Dry Creek are considered to be wetlands by
the USDA Soil Conservation Service.
D. Surface and Subsurface water Resources
The site is in the upland drainage area of Shell Creek. The
western boundary of the site is a tributary drainage to Shell
Creek (Dry Creek) which historically has had intermittent flow
only during precipitation runoff events and permitted plant
discharges. Since June 1987 this tributary has received nearly
continuous discharge from the interim ground water remediation
operation. The treated waters are monitored by the facility's
NPDES permit.
X
Groundwater at the site can be generally characterized as
occurring in a sand and gravel aquifer bounded on the top and
bottom by lower permeability units, which include the upper
loessal soils and the lover Niobrara Formation. SOB* ground
water also occurs in these upper and lower units, but water
movement in than is retarded by the fine-grained nature of these
units.
Groundwater flow in the vicinity of Lindsay, Nebraska is
generally to the south. Localized influences of Shall Creek and
high capacity irrigation vails affect ground water flov in this
area. The aquifer thickness ranges from 35 to 50 fast. The
average ground water flov velocity is about 3 feat par day. In
addition, the shape of the vater table indicates that the ground
water contributes to flov in Shell Creek in th* vicinity of
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I
I
Lindsay
Manufacturing Sitt j
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teal* In F««t
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USGS
2/n/«o
FIGURE I - •
Vicinity Map
Dames & Mocx?
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!
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too
Seata in F««t
FIGURE 1-2
Sit» Layout
Lindsay Manufacturing Site
Dames & Moore
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I w* dap*, minor cataaroui araat. SeaoarM mnor ffwi An* tand ianaa«
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s
Predominantly Silt Loam
nd Pint)
MOiyi: IQM ID dM BTOM. gray. o»«. tow B
toftiA« Mttnd MQ ind rv ArinlnQ,
tand grakv. quire and Md*ar. rounded:
pnr)fiH«Bly quartt. mnor t»ttpar and mate
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Fine Sands
Sand* and Qravrta
a rawdad. peorty B Ml tomd. danM
5-15%,
MK.granaeang|n. UrttgnMnittaaierniii upwaroiand
tan Hay caw
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Sand and
Chalk and Umaaton*
OM* to rnadlum gray B wMft
orangt, or
dark yctaMh orangt. v«y pal*
many toaaU da/m. srtBn
and •oramMfcra. and aM HgtM
and yvlOMMi gray
• lorn gray B medium gray
and thai kigma
FIGURE I- 3
Lindsay Site Stratigraphic Column
Lindsay Manufacturing Site
Dames & Mocre
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Lindsay, Nebraska. Ground water flow direction at the site is
complex because of the influence of several high capacity wells.
E. Surface and Subsurface Features
Currently, the facility contains five buildings including
the main manufacturing plant and offices, the maintenance
building, the galvanizing building, the final production building
and sludge presses. Two settling ponds located on the north end
of the property are part of a wastewater treatment system. The
treatment system also includes a neutralization tank, piping and
appurtenances. This system serves as a wastewater treatment
facility to assist in interim remedial action.
Interim remediation is provided by a ground water control
and recovery operation which includes two high capacity
interceptor wells, the Original Interceptor Well and the Add-on
Interceptor Well (OIW and AOIW), and above-ground pipelines
connecting the interceptor wells to the on-site wastewater
treatment facility. The plant is supplied by the Lindsay public
water supply system and is serviced by the Lindsay public
sanitary sewer. Storm drains at the plant discharge to the
intermittent drainage (Dry Creek) along the west property
boundary pursuant to NPDES permit No. NE0113905.
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES
A. site History
The Lindsay Manufacturing Company site was originally
operated as a gasoline service station until the late 1950's. In
1958, Paul Zimmerer began a sprinkler manufacturing line. In
1961, a manufacturing plant was constructed on the site, and in
1965 a partnership was formed under the name of Lindsay
Manufacturing Co. The "Zimmatic" center pivot system was
marketed in 1969 and the plant was expanded. In 1970 the
operation was incorporated, followed by additional expansions in
plant and office space in 1971 and 1972. The present galvanizing
building was constructed in 1972 and in 1973 a warehouse and gear
box manufacturing facility were added to the sit*. DeKalb
Agrasearch Inc. acquired Lindsay Manufacturing Co. in January
1974, a business relationship that lasted until September 1988,
at which time Lindsay became a publicly-owned corporation.
Disposal of materials from plant operations historically
included discharge of spent acid from the galvanizing building.
From the early 1970's to 1982, a spent acid stream was piped to
an earthen disposal pit ("pit") located north of the company's
galvanizing building. In 1982 Lindsay Manufacturing company
replaced the pit with a new wastewater treatment facility
designed to neutralize the spent acid. The pit was 50 feet in
width, 100 feet in length and approximately 8 to 10 feet deep.
The bottom and steep side slopes (1:1 or less) were apparently
unlined. It had a capacity of 270,000 gallons, and typically
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received "slugs" of io,000 to 15,000 gallons approximately
monthly. The last slug of spent acid was received in December
1982. Since that time, only two discharges to the pit have
occurred. A one-time discharge of neutralized spent acid
occurred on January 28 to 31, 1983. As Lindsay informed NDEC at
the time, the discharge was necessary due to a leak detected in
the acid storage tanks. The liquid was later pumped from the
facility and shipped to an off-site disposal facility. On March
29, 1983, approximately 107,000 gallons of ground water were
pumped to the pit during a well test conducted for remedial
action data collection. This liquid was also reclaimed by pumping
from the pit and shipped to an off-site disposal facility.
Adjacent to the pit was a burn area used to dispose of
cardboard boxes, pallets and paper. This burn area replaced a
previously used burn area which was located north of the plant in
the area of the drainage ditch. Use of the older burn pit ended
when that area was paved in 1971. Discussions with company
personnel have indicated the possibility that small quantities of
solvents, degreasers and aerosol cans of degreasing compounds may
have been disposed of at the back door of the main plant. Small
quantities of solvents and degreasers also may have been burned
in both of the burn areas and disposed of in the pit along with
the spent acid.
Lindsay Manufacturing Company had four wells and a deep test
hole drilled for a proposed wastewater treatment facility. The
wells were installed in December 1982 and sampled in January
1983. The samples revealed that the ground water had abnormal
acidity and temperatures. At this time, Lindsay found that
disposal of spent acid from the galvanizing process was
contributing to ground water contamination.
Three of the wells were found to contain water with low pH
and two of the wells had elevated water temperatures. Lindsay
reported those findings to NDEC. As a result of this discovery,
Lindsay Manufacturing Company began investigations of the soils
and ground water.
B. Interim Remedial Actions
Lindsay Manufacturing Company and NDEC agreed that an
interceptor well would be installed to intercept and remove
ground water for treatment. An on-site interceptor (original
interceptor well - OIW) veil was installed by Lindsay in March
1983 to intercept and recover acidic ground water from the
aquifer b«neath the site. The OIW was located east of cells II
and 12 (see Figure 1-2). The extracted ground water is
neutralized and treated in the wastewater treatment facility,
which was constructed over the area of the former disposal pit.
The neutralization facility and cell fl were completed in May
1983. Cell 12 was completed in January 1984. The filter presses
were installed in May 1984. The interim pumping system began
operating in the spring of 1984. Treated wastewater from the
treatment facility is handled according to NPDES Permit No.
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NE0113905. A Stipulation (Case No. 692) by NDEC and Lindsay
dated April 19, 1933 and amended August 10, 1983 and March 7,
1984 directed the subsequent site investigation and remediation.
Annual status reports were submitted to NDEC.
By the end of 1988, the pump and treat interim action
resulted in the production of 550 million gallons (1680 acre ft)
of treated water, and approximately 7,500 tons of dewatered
sludge. In early 1989, as a result of the recommendation in the
1988 Extended Subsurface Remedial Investigation, the Add-On
Interceptor Well (AOIW). was installed and connected by above-
ground pipeline to the vastevater treatment facility. This AOIW
was designed to intercept and recover inorganic and organic
contaminants at the bottom of the aquifer which had been
identified in the 1988 study. The AOIW is located at southeast
corner of the Lindsay Manufacturing Company property.
C. NPL Site Listing
On August 22, 1988 NDEC notified Lindsay Manufacturing
Company that it was the potentially responsible party (PRP) for
the site as proposed (October 1984) and reproposed (June 1988)
for the Superfund National Priorities List (NPL). Lindsay
Manufacturing Company was invited to participate in formal
negotiations to conduct a Remedial Investigation/Feasibility
Study (RI/FS) for the site.
The State of Nebraska, through a cooperative agreement with
the United states Environmental Protection Agency (EPA), was
authorized to enter into a Stipulation and Agreement with Lindsay
Manufacturing Company whereby Lindsay Manufacturing Company
agreed to conduct a Remedial Investigation/Feasibility Study
(RI/FS) for the site. The Stipulation and Agreement became
effective on January 5, 1989. The site was subsequently added to
the NPL on October 4, 1989.
A proposed RI Work Plan was prepared in accordance with the
agreement and submitted to NDEC in February 1989. NDEC granted
partial approvals for the work plan on April 13, 1989, July 19,
1989, and August 7, 1989. Final approval for the work plan was
granted on November 17, 1989. Field work was initiated on or
about May of 1989 pursuant to approved portions of the work plan.
D. Remedial Investigations
In 1M3, Lindsay Manufacturing initiated a hydrogeologic
investigation and remedial action which involved installation of
an interceptor veil to recover ground water.. During the
hydrogeologic investigation, 21 soil borings were completed and
sampled. In 1987, a shallow boring program consisting of fifteen
soil borings was conducted to reassess the quantity of acid
leachate contamination in site soils.
In 1988, an extended remedial subsurface investigation
initiated installation of 38 borings and five test holes to
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characterize the nature and extent of contamination in both
ground water and soils. In 1989, a Remedial Investigation was
initiated which involved field sampling and testing of surface
soils and sediments. Ground water monitoring wells were
installed to collect ground water samples on-site and off-site.
This new data was collected to supplement the data that had been
collected in the previous investigations.
III. HIGHLIGHTS OF COMMUNITY PARTICIPATION
Community participation was provided in accordance with
CERCLA, as amended by SARA and, to the extent practical, the
National Contingency Plan. Community participation highlights
include the availability of several key documents in the
administrative record, a public comment period and a public hearing.
A community relations plan for the site was completed by
NDEC and approved by EPA in June 1989. This document lists
contacts and interested parties throughout government and the
local community. It also establishes communication pathways to
ensure timely dissemination of pertinent information.
The administrative record for Lindsay Manufacturing Company
was released in the draft form on November 7, 1989. The record was
made available to the public at the following addresses:
U.S. EPA, Region VII
726 Minnesota Avenue
Kansas City, KS 913/551-7000
Columbus Public Library
2504 14th Street
Columbus, NE 68601
402/564-7116
NDEC
301 Centennial Mall South
Lincoln, NE 68509
402/471-3388
\
A press release was issued on November 11, 1989 announcing
the availability of the record. Key documents were added to the
record on February 20, March 28, June 25, July 6, July 9, July
16, and August 28, 1990. Note that for the August 28, 1990
update, documents were added only to the EPA and NDEC
administrative records.
The; Draft Remedial Investigation (RI) Report was included in
the administrative record on March 28, 1990. The Final RI and
draft Feasibility Study (FS) Report were added to the record on
June 25, 1990. The final FS was added to the NDEC and EPA record
on August 28, 1990.
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The Proposed Plan for Lindsay Manufacturing was released to
the public on July ie, 1990 by placement in each of the
administrative records. The notice of availability for the
Proposed Plan was published in the Columbus Telegram and the
Omaha World Herald on July 10, 1990. A public comment period on
the Proposed Plan was held from July 16 to August 15, 1990. At
the request of Lindsay Manufacturing, the public comment period
was extended to August 31, 1990.
A public notice appeared in the Columbus Telegram and the
Omaha World Herald on July 10, 1990 announcing the Public
Hearing. In addition, a press release was issued on July 13,
1990. The Public Hearing was held August 9, 1990 at the Town
Hall in Lindsay, Nebraska to present the Proposed Plan. At this
meeting, representatives from EPA and NDEC answered questions
about problems at the site and the remedial alternatives under
consideration.
All significant comments received by NDEC prior to the end
of the comment period, including those expressed orally at the
public meeting, are addressed in the Responsiveness Summary, in
Section XI of this Record of Decision.
This decision document presents the selected remedy for
Lindsay Manufacturing Company in Lindsay, Nebraska. The decision
for this site is based on the administrative record.
IV. SCOPE AND ROLE OF RESPONSE ACTION WITHIN SITE STRATEGY
A. Role of Remedial Action in Site Clean Up Strategy
The remediation goal for the site is to restore the aquifer
to acceptable water quality levels that are protective of human
health and the environment. The acceptable water quality levels
that have been established under the Safe Drinking Water Act are
Maximum Contaminant Levels (MCLs) or State of Nebraska final
ground water cleanup levels under Title 118, Ground Water Quality
Standards and Use Classification.
The enhanced existing ground water extraction and treatment
.system will restore ground water to acceptable water quality
levels as shown in Table IV-1.
The two existing extraction and treatment walls currently
being optrattd to extract ground water are the Original
Interceptor Wall "OIW" and the Add-on Interceptor Wall "AOIW".
The AOIW is presently designed to pump 1,000 gpm. The current
pumping system would b« enhanced either by increasing the rate of
the AOIW to 1,400 gpm or by installing a third extraction vail,
identified as TIW, to supplement the present AOIW.
The current treatment method employs alkaline precipitation
of zinc salts with the addition of flocculating polymers in a mix
tank followed by sedimentation of the flocculent. The dewatered
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solid residuals are disposed at a local landfill. Supernatant is
recycled to the treataent system.
Current data indicates that the system removes approximately
700 pounds/day of zinc metal from the influent. Because
treatment takes place in open tanks, and because organic
compounds in the ground water are readily stripped during
agitation, the concentration of the organics are reduced during
the treatment process. The treated water is discharged to Dry
Creek under an NPDES permit issued by the State of Nebraska.
If the pilot study demonstrates that soil vapor extraction
is practicable, the design of the system using actual data
derived during the study will determine the actual number of
extraction wells that would be required to effectively remove the
organic compounds from the soil. Removing the contaminants from
the soil would remove a source of organics that would have
eventually entered the aquifer. Using both treatment
technologies, the estimated time for ground water remediation is
five years.
If appropriate to protect human health, as part of the
implementation of this ROD, EPA and NDEC will evaluate options to
ensure that drinking water wells are not installed in areas of
the contaminant plume on and off site.
B. Scope of Problem Addressed
The ground water was determined to be a principal threat in
the surrounding community for three reasons:
1. Ingestion of chlorinated organic compounds in drinking water;
2. Inhalation of volatilized chlorinated organic compounds
during showering or bathing; and
3. Exposure by several pathways to inorganic contaminants
(metals) , placing the potential chronic non-carcinogenic
risk at the present and future higher then the acceptable
level (HI » 1.0).
s
Available data shows elevated concentrations ("hot spots")
of volatile organic compounds in on-site soils as being a
principal threat to ground water.
In If §3, the Lindsay Manufacturing Company identified the
Old LindMy Public Supply Well to be a risk for ground water
contamination. At that tine a new public water supply well was
installed upgradient of the site and is currently the sole source
of drinking water.
The purpose of the selected remedy in this ROD is to prevent
current or future exposure to the contaminated ground water, to
determine the practicability of reducing contaminant migration
from the soil into the ground water, to implement soil vapor
-------
TABLE 17-1
MAXIMUM GROUNDWATER CONTAMINATION AND
ESTABLISHED CLEANUP LEVELS (MCLS)
ORGANIC COMPOUNDS
COMPOUND
1 , 1-Dichloroethane
1,2-Dichloroethane
1 , l-Dichloroethene
1 , 2-Dichloroethene
(total)
Tetrachloroethene
1,1,1-
Trichloroethane
MAXIMUM
CONCENTRATION
SINCE 1987
(ug/1)
230
15
1600
29
1200
6500
MCLS
(ug/1)
NE
5
7
***
5*
200
INORGANIC COMPOUNDS (»g/l)
COMPOUND
PH
Zinc
Sulfate
Cadmium
Chromium
L«ad
MAXIMUM
CONCENTRATION
SINCE 1986
(ng/D
2.8
1530
10,000
0.6
0.79
0.68
MCLS .
(mg/1)
6.5-8.5**
5**
250**
0.005*
0.05
0.05
MCL -
NE
* -
** -
***
Maximum Contaminant Level (Established cl«an-up level]
Not established
Proposed MCL
Secondary MCL
Proposed MCL for cis - 1,2-dichloroethene is 70 ug/1
Proposed MCL for trans - l.2-dichloroethane is 100 ug.
*rc«\lindi*y.906
-------
extraction if practicable, and to restore the ground water
aquifer to MCL quality.
V. SUMMARY OF SITE CHARACTERISTICS
The spent acid disposal pit has been identified as a source
of both inorganic and organic contamination of the aquifer at the
site. Spent acid was piped into the earthen pit from the early
1970s to 1982. Grease, oil, and 1,1,1-trichloroethane (TCA) were
also disposed of and burned in the burn pit located adjacent to
the spent acid disposal pit as well as in the disposal pit
itself.
In addition to disposal of solvents and degreasers in the
spent acid disposal pit and burn pit, solvents and degreasers are
also reported to have been disposed of at the rear of the site
and at the main plant prior to paving. Lindsay investigated
areas of potential soil contamination in 1988, prior to the
Remedial Investigation (RI).
A. Soils
A more detailed summary of the affected soil and ground
water at the site is presented below in sections A and B.
The nature and extent of the presence of contaminants in
soil at the site is based on analytical results of subsurface
soil samples collected between June and August 1988. The soils
with elevated volatile organic contaminants (VOC) that may be
contributing to the ground water contamination are located in the
central drainage ditch, near the northeast corner of the main
plant building, and in the central northern portion of the site.
Laboratory results show that the highest concentrations of VOCs
are at depths of approximately 22 to 40 feet. During the 1988
investigation, Lindsay identified a buried sand channel which
trends N-NW to S-SE through the site and was mapped for over 1100
feet. The sand channel was found to extend at least 300 feet
laterally north of the northern Lindsay property line. The sand
channel was determined to reach a maximum thickness of 25 to 30
feet near the south east corner of cell 12 of the wastewater
treatment facility. The maximum width is 150 feet near the
center part of cell 12. The depth of the sand channel ranges
from approximately 15 to 45 feet.
Inorganic Soil Contaminants
Sixteen subsurface soil samples from the area in the sand
channel were analyzed by EPA methods for total arsenic, cadmium,
barium, chromium, lead, mercury, selenium, silver, iron, and
zinc. Metal concentrations reported above the detection limit
are summarized in Table V-l. A concentration range for elemental
naturally occurring concentrations in soils, i.e. background, is
also provided in Table V-l for comparative purposes. Metal
results from the soil samples listed in Table V-l are all within
-------
their respective naturally occurring concentration ranges.
Five subsurface soil samples were analyzed for EP toxicity
metal analysis. Table V-l lists EP toxicity results and EP
toxicity limits. All results from the soil samples were below EP
toxicity limits.
Upon discontinuance of the use of the acid disposal pit, the
source of metal contamination to site soils ended.
Organic Soil Contaminants
Subsurface soil samples collected in 1988 were analyzed for
volatile organic compounds using a combination of soil gas field
screening and laboratory analysis of soils. The results have
been used to determine the occurrence and trends of organic
compounds.
The purpose of field screening was to provide immediate
results to qualitatively determine if select organic chemicals
were present and to evaluate data trends. The purpose of the
laboratory analysis was to confirm field screening results and
provide additional data. The laboratory sample detection limit
for all compounds in soil was 0.3 mg/kg as specified in the EPA
method. The field screening detection limit was about 5 ug/1
(air). Soil sample laboratory results are listed in Table V-2.
Tetrachloroethylene (PCE) was the most frequent of the
organic compound* found in subsurface soils (Figure V-l). PCE
was detected in silty clay material in the area of the central
drainage ditch throughout the soil column (from approximately 3
feet to 48 feet below surface grade), and generally was found at
higher levels between 33 feet and 48 feet. PCE levels were
higher at the center of the site, with the highest PCE
concentration at 6.8 ng/kg.
PCE was also detected by field screening throughout the soil
column near the northeast corner of the main plant building, from
approximately 3 feet to 43 feet below surface grade.
\
PCE was found above, within, below, and in the vicinity of
the sand channel. PCE levels decreased in concentration to the
north.
Th» approximate horizontal extent of 1,1,1-trichloroethane
(TCA) was not found in as vide an area as PCE (Figure V-2). TCA
was found at levels higher than other organic compounds found on
site. TCA was found in the following areas on site: near the
central drainage ditch; the northeast corner of the Bain plant
building; and north of Call 12 of the wastewater treatment
facility. The highest TCA concentration was 14.1 ag/kg naar the
northeast corner of the vain building.
TCA occurrence and trends in subsurface soils are similar to
the PCE trends. TCA was found in silty clays in the central
10
-------
drainage area primarily between 18 feet and 43 feet below surface
grade. The TCA field screening maxima was found near the
northeast corner of the main plant building, it was detected
from approximately 8 feet to 42 feet below surface grade. TCA
also was detected in the area north of Cell 12 of the wastewater
treatment facility.
The extent of 1,1-dichloroethene (DCE) (Figure V-3) was
found over a broad area and, like PCE and TCA, was centered
around the central drainage ditch and the northeast corner of the
main plant building. DCE was also found north of the central
drainage area near Cell 12 of the wastewater treatment facility
where PCE and TCA were found. The highest DCE concentration on-
site was 1.9 mg/kg near the northeast corner of the main plant
building.
PCE and DCE occur most widely at the site. TCA is more
limited in extent but appears at the highest individual
concentration of the organic compounds. PCE, DCE and TCA areas
of contamination are shown in Figure V-4.
B. Ground Water
The discussion of the nature and extent of inorganic and
organic ground water contamination is based on ground water
monitoring data collected from 1983 through January 1990. Ground
water quality has improved in some areas during this tine due to
the interim remedial measures discussed in Section II B. The
remaining organic and inorganic contamination has been defined by
the 1989/1990 RI. Inorganic and organic contaminants in the
aquifer occur from near Monitoring Well 87-6 southeast to
irrigation well 154278 as shown in Figure V-5. The occurrence is
along the bottom of the aquifer except for the area beneath the
old spent acid pit and the northeast corner of the main plant
building.
Sand Channel
A buried sand channel was identified by Lindsay in the RI.
Two monitoring veils, MW89-13 and MW89-14, are screened in the
sand channel only. Samples from these wells were analyzed for a
range of inorganic and organic constituents. Detectable levels
of zinc, iron, sulfates and organics were found in the ground
water.
Zinc, iron, and sulfate levels were above the secondary
drinking water regulations for these elements in all samples.
These secondary standards were developed to protect the public
welfare by preserving the quality of the ground water as e
drinking water source based on odor, aesthetics and appearance.
Nebraska and EPA secondary standards for zinc, iron end sulfate
are 5, 0.3, and 250 ag/1, respectively.
Levels of DCE and TCA in some ground water samples froa the
sand channel were found to exceed Nebraska or EPA Maximum
11
-------
Contaminant Levels (MCLs)• MCLs have been developed as public
health standards for drinking water. The Nebraska and EPA MCLs
for DCE and TCA are 0.007 and 0.20 mg/1 respectively. The DCE
MCL was exceeded in MW89-13 and MW89-14. The TCA MCL was
exceeded in MW89-14.
There is currently no Nebraska or EPA MCL established for
PCE. EPA has proposed an MCL for PCE of 0.005 mg/1 but has not
promulgated MCL regulations. PCE concentrations in MW89-13 and
MW89-14 were 0.19 and 0.015 mg/1 respectively.
Aquifer
As discussed above, some aquifer monitoring wells were
completed in the upper portion only, some in the lower portion
only, and some were screened throughout the aquifer. Samples
collected from these wells were analyzed for a variety of
inorganic and organic constituents. Detectable levels of zinc,
iron, sulfates and some organics were observed in both the upper
and lower sections of the aquifer. The generalized area of
ground water contamination is presented in Figure V-5.
Zinc has occurred above the secondary drinking water
regulation of 5 mg/1 in the upper and lower portions of the
aquifer. Only a small area of occurrence is indicated in the
upper aquifer compared to that found in the lower aquifer. As a
result of the density of zinc, concentrations in the lower
aquifer are generally higher than in the upper and entire aquifer
samples.
Sulfate has occurred above the secondary drinking water
regulation of 250 ppm in aquifer. Only a small area of
occurrence is indicated in the upper aquifer compared to that
found in the lower aquifer. As a result of the density of
sulfates, concentrations in the lower aquifer are generally
higher than in the upper aquifer samples.
Iron concentrations have occurred above the secondary
drinking water regulation of 0.3 ppm in both the upper aquifer
and the .lover aquifer. As with the zinc and sulfate, the extent
of iron occurrence in the lower portion of the aquifer is greater
than in the upper portion.
Cadmium and lead occur sporadically and only in some wells.
Cadmium was found above the MCL of 0.01 mg/1 only in TMW 88-5,
TMW 88-6, and TMW 88-9 more than once. These three veils are at
the bottom of the aquifer near the AOIW where their transport is
controlled by interim remediation. All other occurrences are
either a single detection or short term followed by non-
detection. Lead was found above the MCL of 0.05 mg/1 once in
well P-6 and repeatedly at diminishing concentrations to below
the MCL in P-9. Both wells are at the bottom of the aquifer and
close to interceptor wells which control the lead transport and
recovery by remedial pumping.
12
-------
TABLE V-1
Summary of Laboratory Soil Sample Results
Total Metal and EPToxIcity Metal
Total Metal (mg/kg)
§1 M •!•• *•
uonnQ
SB-3
SB-5
SB-6
SB-13
SB-14
SB-32
SB-35
SB-36
SB-37
Depth
(to*))
37
41
27
32
43
37
44
33
38
38
33
43
43
33
33
38
• M aalajl 'Vial
Concentration Ranoa (1)
fatal
AiMafe
1J3
0.96
NO
0.44
029
6.09
0.69
0.79
0.31
11.10
12.30
9.92
2.70
0.90
030
0.19
Wl ^
97
Total
BartuM
216
159
131
116
173
220
745
233
218
294
258
236
220
259
193
see
W.
50.000
Total
Chromium
926
14.6
9.54
11.9
20.4
15.3
9.19
203
15.9
16.6
17.9
18.0
149
20.1
18.1
4.19
1.
•
2.000
Total
toon
10.146
13.073
10.047
10.766
15.005
16.394
10^38
21.534
19.779
19.995
21.215
19.148
16.450
21.591
15.709
4.118
inn.
•w
>100.000
Total
Zinc
596
832
168
274
1.633
51.5
190
1.071
1.059
68.1
63.6
48.7
453
523
26.7
2.79
g-
29.000
EP Toxlclty Metal (mg/l)
(1) USQS. Elemental Concentrations in
Sob and Other Surfical Materials Of
me Conterminous United Slates 1984.
NO- Not Defected
§1 a,-aW •
Donng
SB-2
SB-*
S85
SB-6
EPToKicily
Limits
(feel)
38.5
40
43
44.5
A-**
0.002
NO
NO
NO
50
**"
0.1
NO
NO
NO
100
Ghroariua.
NO
NO
NO
NO
5.0
Uad
NO
NO
NO
NO
5.0
Mercury
0.2
NO
NO
NO
0.2
SOMffMffli
NO
NO
NO
NO
1.0
SMwer
NO
0.14
NO
021
5.0
Cadmium
NO
NO
NO
NO
1.0
Job number 16657-002-005
Dames & Moore
-------
TABLE V-2
Summary of Laboratory Soil Sample Results
Organic* Compounds (mg/kg)
ATM el
SHt
Central
Drainage
Otteft
Northaaat
Corner of
Main Plant
Coll«2
Boring
SB-23
SB-22
SB-24
SB-27
SB-2S
SB-32
SB-11
SB-33
SB- 12
SB-16
SB-3
SB-4
S8-14
Depth
Jleet)
I^HMMIM^^M^M^^MMi
18
38
28
43
33
38
38
38
48
38
48
8
22
32
40
44
23
33
20
3
43
45
42
43
46
PCS
••••••MMpiB^BB^BBMPHHM
1.2
NO
2.7
2.4
3.1
6.8
0.3
0.4
0.4
NO
NO-
NO
NO
1.7
0.4
NO
NO
1.6
NO
NO
0.6
NO
1.2
0.4
NO
TCA
1.0
0.3
2.1
1.2
U
1.1
NO
0.7
0.6
1.1
0.7
0.5
6.4
14.1
2.7
0.4
0.5
7.4
3.4
0.73
1.2
0.7
NO
1.5
1.0
OCE
^^^^^•^^•••^•^••••MBI
0.3
NO
NO
NO
NO
NO
NO
NO
NO
0.4
NO
NO
0.7
1.9
0.6
NO
NO
1.5
0.8
NO
0.5
NO
NO
0.3
NO
NOU»:
NO- NMDftMStd
Job numb«r 16657-002-005
Dames & Moore
-------
ClisIM* PloduclkM We«i
t il<1U( Pi€
f acMty MoAirwIog MMIf !»•/
Slu*N> Augei Bofingi !»••
Occwmc*
ol
FIGURE V- 1
Approximate Horizontal Boundary of PCEOccurrence
June-August 1988
Lindsay Manufacturing Site
Dames & Moore
-------
ea^
— "3CL
%'V
t-M*J IC**V
;
-*-l4»-
~^l|
1 '
I !
fT
IV\fl—I—I
V *c M If *t
I «i»lmg Pf
f -
IM7
I»»l Hot** t *M
ApfxoilriuM HwllOfllcl Bound*! , I
f C A Occvranc*
FIGURE V .
Approximate Horizontal Boundary ol TCAOccurrence
•Mine-August 1988
Lindsay Manufacturing Site
. Dames A Moore
-------
Eiltling PioducIlM WHIt
r MoflllMhig We*» IM7
SlMlov Augw Bwingt I9M
hit Mo*.. >•>«•
Appio.lm.l. Hoclionl*! Bou»<«»y ,
DCC OCCOICHC*
FIGURE V -
Approximate Horizontal Boundary of DCEOccurrenc.
June-August I98b
Lindsay Manufacturing Site
Dames A Moor*
-------
AppfoihMI* BoundMy el
OCC Occuf
Appioilmat* Boundwy ol
TCA OccutfMtc*
FIGURE V-4
Approximate Horizontal Boundary,
ol PCE, TCA and OCEOccurrence
June-August 198
Lindsay Manufacturing Sn
Dames A Moor.
-------
• Fitting r..
I .C*.!, Mo^KMMg *.I. IMI
O 1«mpe
-------
Available data shows elevated concentrations ("hot spot") of
volatile organic compounds (VOCs) in on-site soils as being a
principal threat to ground water. Ground water data from MW89-
12, located near a VOC hot spot area northeast of the main plant
building, from November 1989 to May 1990 has shown increasing
concentrations of l,i-DCA from 49 ug/1 to 520 ug/1. TCA and PCE
have also shown high concentrations. The data shows that this
hot spot area is a principal threat contributing to the ground
water VOC contamination.
NDEC has assigned the aquifer at the site to Remedial Action
Class One (RAC-1) pursuant to Title 118 - Ground Water Quality
and Use Classification. RAC-1 aquifers receive the most
extensive remedial action measures. This relates to the SOWA
Class I and Class II aquifers which are characterized as
irreplaceable, current or potential drinking water sources.
C. Contaminant Fate and Transport
According to the RI, the fate of the acidic metal-laden
water (with its dissolved organic components) has been subject to
several dynamic conditions. These conditions include density
differences between the acidic metal laden waters and aquifer
waters, chemical gradients, variable hydraulic gradients
resulting from high capacity well operations and the influences
of dilution and neutralization. Forces that are of little or no
influence in the aquifer are solute chemical reaction and
adsorption-desorption. These forces are generally weak because
of the relatively inert nature of the aquifer matrix. Because of
the relatively low reactive potential of the chemical compounds
within the aquifer, the compounds are transported by and can be
intercepted or recovered in the ground water. This fluid
transport, the gradual dispersion and the recovery of the
chemical compounds have been traced through time in the
monitoring well water samples results.
VI.SUMMARY OF SITE RISKS
A. Human Health Risks
X
The baseline risk assessment addresses potential human
health and ecological risk associated with currently existing
(i.e. baseline) as veil as potential future conditions at the
site. The) baseline risk assessment consists of the following
steps: hazard identification, exposure assessment, toxicity
assessment and risk characterization.
Hazard identification involves gathering and analyzing the
site data relevant to the human health evaluation and identifying
the substances present at the site that are the focus of the risk
assessment process.
Exposure assessment is conducted to estimate the magnitude
of actual and/or potential human exposures, the frequency and
13
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duration of these exposures, and the pathways by which humans are
potentially exposed.
The toxicity assessment component of the risk assessment is
accomplished in two steps. Hazard identification is the first
step in the process; it will determine whether exposure to an
agent can cause an increase in the incidence of an adverse health
effect (e.g. cancer, birth defects....) and also involves
characterizing the nature and strength of the evidence of
causation. In the second step, dose-response evaluation,
toxicity information is quantitatively evaluated and the
relationship between the dose of the contaminant received and the
incidence of adverse health effects in the exposed population is
characterized. From this quantitative dose-response
relationship, toxicity values are derived that can be used to
estimate the incidence of adverse effects occurring in humans at
different exposure levels.
The final step of the baseline risk assessment process is
risk characterization. Risk characterization summarizes and
combines outputs of the exposure and toxicity assessments to
characterize baseline risk, both in quantitative expressions and
qualitative statements.
Hazard Identification
Groundwater data used for evaluation of potential exposure
pathways to off-site human receptors is based on the 1989
sampling results froa both on-site and off-site monitoring and
drinking water wells and soil concentrations obtained in 1989.
The contaminants used in the risk assessment are listed in
Table VI-l for ground water and Table VI-2 for soils and grass.
Exposure Assessment
The baseline risk assessment of the Lindsay NPL site is
based on 1989 data from on-site and off-site ground water, on-
site and off-site soils and sediment for drainage pathways, and
modeled,airborne particulate concentrations.
A fundamental component of the baseline risk assessment is
the exposure assessment, which estimates the potential human
exposure to chemical compounds that are present at or have
migrated ftom the site. Exposure assessment consists of
characterisation of the local setting, identification of
potential exposure pathways, and quantification of potential
exposure expressed in toxicological terms as dose per unit time.
The characterization of the local potential exposure setting
is based on site information used in part to identify the
potentially exposed population. The subsequent identification of
potential exposure pathways describes in qualitative terms the
course a target chemical could, under the Reasonable Maximum
Exposure (RME) scenario, take from the site to potential receptcr
14
-------
populations. The intent of the RME scenario is to estimate a
conservative exposure case that is within the range of possible
exposure under current and future land use conditions.
The closest residential community to the Lindsay site is the
village of Lindsay, located immediately to the west. To the east
and south of the facility are a number of large farms. Both
existing and projected land use within the immediate area is
rural and agricultural, with predominantly single-family
residences.
Based on the fact that the current water supply for both the
site and village of Lindsay is located hydraulically upgradient
of the facility, the village of Lindsay was not included in the
exposure assessment. The prevailing ground water flow is toward
the area southeast of the site. The rural population on the land
southeast of the site thus constitutes the primary potential
receptor population. Because no hospitals, day-care centers, or
other potentially sensitive land use activities are located in
the path of ground water flow from the site, it was not necessary
to assume that any unusually sensitive receptor populations
occupied this off-site area.
Since contaminants have been detected above MCLs in
irrigation well 154278 located southeast of the site, EPA and
NDEC will evaluate options to ensure that drinking water wells
are not installed in areas of the contaminant plume on and off
site as part of the implementation of the ROD if necessary to
protect public health.
The land us* surrounding the site consists largely of
farming operations, although there is limited habitat for a
variety of wildlife. The potential for effects on wildlife is
further discussed in Section VI-B. In the future scenario,
potential receptor populations include: the present population at
risk, the population of Lindsay, and on-site workers. For the
off-site rural population adjacent to the site, all age groups
may potentially be exposed to compounds released from the site,
and their exposure represents a composite release from the site.
Six exposure pathways were evaluated in the risk assessment.
These pathways arc potential exposure via soil ingestion, dermal
contact with soil, drinking water ingestion, inhalation of vapors
from water*, ingestion of homegrown fruits and vegetable*, and
inhalation of wind-driven particulate dust from off-sit*.
Calculation of Dose:
The general considerations used in conducting the exposure
assessment involve the chemical dose (concentration per unit
time), the exposure duration and frequency, the rat* of contact,
and other specific parameters.
For each contaminant of concern a chemical intake or dose
was calculated for each route of exposure.
15
-------
For the ingestion of chemicals in drinking water the
following equation was used:
Intake (mg/kg/day) = CW x IR x EF x ED
BW x AT
where,
CW: chemical concentration in water (mg/liter)
IR: ingestion rate (liters/day)
EF: exposure frequency (days/year)
ED: exposure duration (years)
BW: body weight (kg)
AT: averaging time; period over which exposure is averaged
(days)
For an adult a body weight of 70 kg was used to represent an
average adult. An ingestion rate of 2 liters of water per day was
assumed. The exposure frequency of 365 days per year was used to
represent lifetime exposure. For concentrations in drinking
water the upper 95th percentile of the averaged concentrations
was used to represent a Reasonable Maximum Exposure (RME).
Other intake equations are outlined in the Remedial
Investigation in Section 6.0. See Table VI-3 for a summary of
potential dose or intake to off-site receptors.
Toxicity Assessment
Under current EPA guidelines the likelihood of carcinogenic
and non-carcinogenic effects due to exposure to site chemicals
are considered separately. Criteria for evaluating the potential
of site chemicals to cause these two types of adverse effects are
described below.
Carcinogenic and non-carcinogenic risks posed by
contaminants were evaluated for the potentially exposed
population with regard to each exposure pathway for current and
projected uses of the site and its surroundings.
Criteria .for Non-carcinogenic Effects
\
A reference dose (RfD) is the toxicity value used most often
in evaluating non-carcinogenic effects resulting from exposures
from the sit*. Additionally, one-day or ten-day Health
Advisories (HAs) nay be used to evaluate short-term oral
exposures.
Various types of RfDs are available depending on the
exposure rout* (oral, inhalation, dermal), the critical effect
(developmental or other) and the length of exposure being
evaluated (chronic, subchronic or single event). A chronic RfD
is an estimate of a daily exposure level for the human
population, including sensitive populations, that is likely to be-
without an appreciable risk of deleterious effects during a
lifetime. Chronic RfDs are developed to be protective for long-
16
-------
term exposure to a compound. Chronic RfDs are generally used to
evaluate the potential non-carcinogenic effects associated with
exposure periods between 7 years and lifetime. Subchronic RfDs
are generally used for exposure periods between 2 weeks and 7
years. Developmental RfDs are used to evaluate the potential
effects on a developing organism following a single exposure
event. A summary of the Chronic RfDs used in the risk assessment
are presented in Table Vl-4.
For non-carcinogens, the projected dose or intake developed
in the exposure assessment is divided by the RfD value to compute
the Hazard Index (HI). This approach reflects the assumption
that a toxicity threshold generally exists for non-carcinogens,
and that the risk can be represented by the quotient of the dose
and the allowable RfD. The HI was developed by EPA to assess the
overall potential for non-carcinogenic effects posed by multiple
chemical exposures although each individual toxicant is evaluated
individually. The HI is not designed as a mathematical
prediction of the severity of the non-carcinogenic effects,
rather it is an indication of potential adverse effects in view
of established RfD criteria for specific chemical compounds.
The potential chronic non-carcinogenic risk at the present and in
the future is higher than the acceptable level (HI - 1.0) for
several exposure pathways.
The values ranged from less than 1 to 95. The inorganic
contaminants of concern are cadmium, lead and zinc. See Table
Vl-5 for the hazard index calculation results.
Criteria for Carcinogenic Effects
The EPA uses a weight-of-evidence system to convey how
likely a chemical is to be a human carcinogen, based on
epidemiological studies, animal studies, and other supportive
data. The classification system for characterization of the
overall weight of evidence for carcinogenicity includes: Group
A: Human Carcinogen; Group B: Probable Human Carcinogen; Group C:
Possible Human Carcinogen; Group D: Not Classifiable as to Human
Carcinogenicity; and Group E: Evidence of Non-Carcinogenicity for
Humans. . Group B is subdivided into two groups: Group Bl:
limited human evidence for carcinogenicity and Group B2:
sufficient data in animals but inadequate or no evidence in.
humans. See Table VT-6 for the classifications of the chemicals
of concern.
For chemicals with carcinogenic effects, EPA calculates the
cancer riek associated with a given doee by multiplying the dose
from a given route of exposure by a cancer slope factor. Slope
factors are derived from the upper 95% confidence limit of the
slope of the extrapolated dose-response curve, which shows the
relationship between a given dose and the associated tumor
incidence. This conservative model assumes no toxicity threshold
and unlike the non-carcinogens evaluated using the Hazard Index
(HI), these risks are assumed to be additive in nature (i.e.,
cancer is assumed to be systemic rather than target organ-
17
-------
specific). Slope factors used in the risk assessment are listed
in Table VI-6.
A cancer risk is expressed as the likelihood for an
individual to contract cancer over a lifetime as a result of
exposure to a specific chemical compound. The cancer risk for
each compound is added together to produce the total risk from
exposure to multiple compounds.
Risk Characterization.
The general target for lifetime cancer risk under the
Reasonable Maximum Exposure (RME) scenario is between 1 x 10*4
and 1 xlO-6, or l.in 10,000 to 1,000,000 This was determined to
be the most appropriate target for the purposes of the Lindsay RI
and the FS.
Under current and future conditions nearly all the potential
cumulative excess cancer (1.6 x 10-2) is due to the exposure to
chlorinated organic compounds based on ingestion of drinking
water and inhalation of volatilized chlorinated organic*
compounds during showering or bathing. The organic contaminants
of concern are 1,1-dichloroethane, 1,2-dichloroethane, 1,1-
dichloroethylene, tetrachloroethylene, and trichloroethylene that
are possible human carcinogens. Cadmium was the only metal
characterized as a possible human carcinogen. None of the other
metals are deemed to be possible carcinogens and therefore they
were not included. See Table VI-7 for a summary of potential
cancer risks to off-site receptors.
The National Oil and Hazardous Substances Pollution
Contingency Plan (NCP) advises an acceptable excess cancer risk
is in the range of 1 x 10-4 to 1 x 10-6, depending upon
individual site conditions. This means the excess risk for a
person to contract cancer is between 1 in 10,000 and 1 in
1,000,000. Remediation attempts to reach a 1 in 1,000,000 risk
level where possible. The remedial goal for ground water will be
the Maximum Contaminant Level (MCL) or established clean up level
for each contaminant.
•s
Actual or threatened releases of hazardous substances at or
from this site, if not addressed by implementing the response
action selected in this Record of Decision, may present an
imminent and substantial endangerment to the public health,
welfare, or the environment.
B. Environmental Risks
The potential that on-site soils would pose a threat to
wildlife coming on to the site was evaluated. The compound most
likely to impact wildlife is believed to be zinc. It is assumed
that the primary means by which the compounds are brought to the
surface off-site is through pumping of irrigation wells. Organic
solvents present in the ground water are generally volatile and
are expected to dissipate quickly into the atmosphere when
18
-------
Table vi-i
Summary of 1989 Groundwater Data Used for Baseline Assessment
Lindsay Mfg. Co.
I 1
n Compound
Cadmfcjm
Ctvomhjm
Lead
r«
Traoe Organic*
.1«*cNofoe*ane
.2-dkttONMtftana
.1-dMauiuamylant
,2-o%t»oroethylene
. 1.1 -tricMoroetfian*
TeliatMmuNhylano
Tlt*too-*l~
Fraojueiicyof
Oatadloji
32f160
13/159
77/160
150/161
35^73
9/173
69/173
11/173
82/173
71/173
9/173
Average
844
8.88
20.23
44.734.47
5.31
3.46
28.65
4.04
107.94
3209
280
Ground
Standard
Deviation
25.15
29.97
127.99
115.920.36
9.08
2.81
67.84
3.48
395.50
68.44
1.57
Water Concentratl
Upper 95lh
percent He
4982
56.18
230.78
235.423.49
20.24
809
140.28
9.77
758.54
144.67
5.39
on ftifll)
Maximum
180
277
1.600
532.000
72
25
510
25
2.900
430
5
Sample
Size
160
159
160
161
173
173
173
173
173
173
173
oo?oos
Dames & Moore
-------
Table vi-2
Summary of Off-Site Soil and Grass Metals Concentrations
Lindsay Mfg. Co.
Compound
SOUS
Cednfcm
jiefeiMice MM)
lead
[reference MM)
Zinc
[reference eraa)
GRASS
Cadmium
(reference MM)
lead
(roterenoe MM)
Zinc
[reference MM)
^QQIIOlHLiBBBpHi
AMMi
NO
NO
NO
NO
57.2S
49
NO
NO
NO
NO
IS
53
»,
a)
(b)
•)
(b)
(b)
(b)
(b)
(b)
moftQdrywt
'
MnkMMi
NO
NO
11
NO
61
~
NO
NO
NO
NO
65
53
(•)
(b)
(b)
(b)
(b)
(b)
(b)
Sample sin
(n)
4
1
4
1
4
1
Detection
Urn*
10
1.0
10.0
10.0
1.0
1.0
1.0
1.0
10.0
10.0
1.0
1.0
NOTES:
<•» Not drtwfed. but tfc •» Mmpto quanttaion ftrt was Inowporaled into the quanllalivaanaVsb.
(b) Not detertirt «l tie InJceled toxul.
NO --- fat Detected
to 16657^02^05
Dames A MOOTQ
-------
Table vi-3
Summary of Potential Total Exposure (I.e., dose) to Off-Site Receptors By Age Class
Lindsay Mfg. Co.
AGE 8 lo It
ORAL (rrayfcg day)
Average | RME
INHAL (moAg<
-------
Table VI-A
Summary of Non-cardnogtnlc Chronic RID Values (a)
Lindsay Mfg. Site
mACt METALS
•.MM
•.a
ft
ft
ft
dMTral
UF.IOtor
MF-I
UF.IOOto
MF-H)
UF. 900 tar
MF-I
H
H.A
H.AS
1MACC
17
I.I
1.2
I.I.I
f*
•.I
•M
M
ft
A
ft
ft
UF.IOOO
UF.IOOO
UF.IOOO tar
MF-I
UF.IOOO tar
MF-I
UF-1000 tar
MF-I
UF.IOOO tar
MF.t
HAS
HAS
HAL
to \btAlOOJOM
-------
Table-vi-4 (continued)
Summary of Non-cardnogtnlc Chronic RID Values (a)
Lindsay Mfg. Silo
pkoJrilbilVM.UBfc
ConM*nc*
CiMcri
Eltert
(UF/MFltel
IVIACCMCfAIA
••Ml
eoaoa
••t
w
M
01
••*
0.11
UF.IOOO
UF-IOOO
UF.IOOOto
fcF-l
H.A.S
*• BMIW WMk OMH>|ErA.ltMk); MpvM M
IMM not tmn
*OM IOAEL to NOAEL S - •ikapotafcM kom tubchtonlc to dwonfc NOAEL;
IMflb).
lab Nil I66S20O20M
-------
Table "i-s
Summary of Potential Hazard Characterization for Non-Carcinogenic Compounds
RME Scenario. Off-Site ITMiptnri
Lindsay Mfg. Co.
„„,,.„.,«,
TRACE METALS
Cadmium
ClwonNuni
L«ad
Zinc
TRACE OROAMCS
ft « »^« ^** — — —
, i "UitniuiO6>ian>
1.24tal*>roettiafw
«« ^AlMA^^^fk^dAM^^a^A
, l -OlCraONManpanB
1,2
-------
Table vi-6
Summary of Carcinogenic Slope Factors
Lindsay Mfg. Site
COMPOUND
TRACE METALS
Cumum (and Compound*)
Cftromun HI (and Cempeundi)
Ovomfn VI (and Compouna)
Laari (inorganic and Compouid*)
23ne (and CameonOB)
THACt OMOAMICS
1.1.0*MOnM«MM
U.0kmt«n.
> 1 1 *OI^N0^0fl^^n0O9
l,i,i-ticr)toroiWiin«
T M ^ia ^^i^k*^
Twaoniofoaciytana
ORAL SLOPE
'ACTON (•)
(maliQ-terVi
NO (0
NO (C)
NO (C)
NO (C)
NO (0
OM\
0.001
O.I
/. A
I*. I)
(C)
0.011
W*ioni
-------
Table vi-6 (continued)
Summary of Carcinogenic Slop* Factors
Lindsay Mfg. Site
MMALATON Wrtgnt-
•LC*I PACTON (a) CtoM*
COMPOUND (moAoHtovVi On»i
THaCE U£T*i_S
CMrrvum (and fnwuuuna) ^ ,
CtvemUn III (and CampujHE) NO
Chjomfam VI (and Compound*) 41
Laad (taoroanc and Compound*) NO
Zne (and Compound*) NO
onailai»ia» tar ajianrmiNt m» i
luamga
I No 16ft57-00240S
-------
brought to the surface in irrigation water, it is expected that
dilution and dispersion of this organic compound will reduce
their concentration below potential significant exposure levels.
There is a wide variety of animals that could live in and around
the fields impacted by irrigation well 154278 located southeast
of the Lindsay facility. Few species would find all of their
habitat requirements met entirely within the fields, because
crops and field borders would probably only be used for a portion
of their lifetime and of their home range.
The amount of exposure will vary depending on the habits of
an individual species. Species that live primarily within the
field are most susceptible to exposure, while those that live on
the field borders or only occasionally use the areas would be
less susceptible. The ecological assessment, based on on-site
surface soil and irrigation ground water indicated no significant
potential exposure of wildlife inhabiting the vicinity of Lindsay
to site-related chemical compounds.
VII. DESCRIPTION OF ALTERNATIVES
The alternatives analyzed for the Lindsay Manufacturing
Company site are presented below. These are numbered to
correspond with the numbers in the FS report.
Alternative 1:
Alternative 2:
Alternative 3:
Alternative 4:
* Alternative 4A:
Alternative 5:
Alternative 5A:
No action
Cessation of ground water extraction
and treatment with installation of
a new irrigation well.
Cessation of ground water extraction and
treatment with vacuum extraction of soils
containing organic compounds.
Continuation of existing ground water
extraction and treatment.
Enhancement of ground water extraction
and treatment by either increasing
on-site pumping or by the installation
of additional interceptor veil.
Continuation of existing ground water
extraction and treatment with additional
control of ground water containing
organic compounds.
Enhancement of ground water extract :=r.
and treatment by either increasing
on-site pumping or by the installat::-
of additional interceptor well, and
additional control of ground water
containing organic compounds.
19
-------
Alternative 6:
* Alternative 6A:
* Alternative 7:
* Alternative 7A:
Alternative 7B:
Continuation of existing ground wate~
extraction and treatment with in sit
flushing of the sand channel.
Enhancement of ground water extraction
and treatment by increasing on-site
pumping or by the installation of
additional interceptor well, with
in-situ flushing of the sand channel.
Continuation of existing ground water
extraction and treatment with vacuum
extraction of soil containing organic
compounds.
Enhancement of ground water
extraction and treatment by either
increasing on-site pumping or by the
installation of additional interceptor
well with vacuum extraction of soil
containing organic compounds.
Enhancement of ground water extraction
and treatment by either increasing
on-site pumping or by the installation
of additional interceptor well. Conduct
a pilot study to determine the
practicability of full scale vacuum
extraction of soil containing organic
compounds.
Alternative 3 was not retained after the screening process
(which is detailed in the FS report) since it did not reduce the
quantity of toxicity of contaminants in the aquifer. Alternatives
6 and 6A were not retained for further analysis due to technical
problems. These problems included the potential for mobilization
of metals and organic compounds which may subsequently prove
difficult to control. The potential existed that these
constituents could migrate to the aquifer.
COMMON ELEMENTS
Except for the "No Action1* alternative, all of the
alternatives b«ing considered for the site would include a number
of common domponents. Alternatives 4, 4A, 5, 5A 7, 7A and 7B
include either the operation of the existing pump and treat
system that is currently being operated at the site or the
enhancement of this system. All of the above stated alternatives
also include ground water monitoring to gauge the effectiveness
of the selected remedy. In addition, the installation of
additional ground water monitoring wells will be necessary
downgradient of irrigation veil 154278 to determine if the
contaminated ground water plume extends past this veil. This is
due to contamination detected in this well during the 1989
20
-------
irrigation season, it is not known if these contaminants are
moving further downgradient.
Listed below is a brief description of each alternative. A
10 percent interest rate value was used to calculate present
worth. Alternatives 5, 5A, 6, 6A, 7, 7A, and 7B are all
modifications of Alternative 4 or 4A.
* Alternative 2:
Estimated Capital Cost: $195,200
Estimated Annual Operation and Maintenance (04M)
Costs: $89,600
Estimated Implementation Time Frame: 10 years*
Estimated Present Worth of Capital and Operating
Costs: $746,000
Under this alternative, the existing ground water pump and
treat system would no longer be operated. However, a
new irrigation well would be installed to replace
irrigation well number 54278 (this well shows
contamination during operation in the irrigation season).
This new well would be designed to draw from ground
water which is not hydraulically downgradient of the
site. A 16-inch diameter well would be constructed at
an approximate depth between 120 and 170 feet. In addition,
deed restrictions affecting future ground water use
would be established for portions of both the Lindsay
and neighboring property southeast of the site until
natural dispersion and advection reduces metal and organic
contaminants in the ground water at the relevant areas of
the site. Ground water monitoring would continue for
ten years in order to gauge the potential impact of the
cessation of the existing extraction and treatment
operation. This alternative is considered a limited action.
* Alternative 4:
Estimated Capital Cost: $0.00
Estimated Annual Operation and Maintenance (O&M)
Costs: $431,300
Estimated Implementation Time Frame: 10 years*
Estimated Present Worth of Capital and Operating
Costa: $2,650,000
UndMr this alternative the two existing extraction and
treatment veils (Original Interceptor Well "OIW" and Add-on
Interceptor Well "AOIW) currently being operated would
continue to be used to extract ground water. The AOIW would
continue to pump at its current design rats of 1000 gpm and
the OIW would continue to pump periodically at approximately
500 gpm. The current treatment method employs alkaline
precipitation of zinc salts with the addition of
flocculating polymers in a mix tank, followed by
sedimentation of the flocculant. The existing system is
21
-------
described by the flow diagram in Figure vii-i. It is
currently designed to handle up to 1,000 gallons per minute
(gpm). The devatered solid residuals are disposed of at a
local landfill, supernatant is recycled to the treatment
system, current data indicates that the system removes
approximately 700 pounds/day of zinc metal from the
influent. Because treatment takes place in open tanks and
because organic compounds in the ground water are readily
stripped during agitation, the concentration of the organics
are reduced during the treatment process. The treated water
is discharged to Dry Creek under an NPDES permit issued by
the State of Nebraska.
Alternative 4A:
Estimated Capital Cost: $173,400
Estimated Annual Operation and Maintenance (OtM)
Costs: $521,000
Estimated Implementation Time Frame: 5 years*
Estimated Present Worth of Capital and Operating
Costs: $2,148,000
Alternative 4A is a modified version of Alternative 4. In
Alternative 4A, either the AOIW would be modified to
increase its pumping rate or an additional interceptor well
identified as TIW (for third interceptor well) would be
installed. Either of two pumping methods arc applicable:
(1) modification of the AOIW to increase its pumping rate or
(2) the addition of a supplemental interceptor well between
the AOIW and the irrigation well southeast of the site.
Under method 1, the replacement wells would be designed to
produce approximately 1,400 gpm, which is the maximum yield
of the aquifer at this location. Under method 2, the TIW
would be sited near the location shown on Figure 6 and would
be designed to produce 600 gpm. This new well would
supplement the existing AOIW. Under either method the Oiw
would continue to be pumped at an average rate of 600 gpm.
Treatment of ground water and discharge of treated water
would be conducted as described. The current treatment
method employs alkaline precipitation of zinc salts with the
addition of flocculating polymers in a mix tank, followed by
sedimentation of the flocculant. The existing system
is described by the flow diagram in Figure VII-1. It is
currently designed to handle up to 1,000 gallons per minute
(gp»), but will increase as stated for this alternative.
The devatered solid residuals are disposed of by a
local landfill. Supernatant is recycled to the treatment
system, current data indicates that the system removes
approximately 700 pounds/day of zinc metal from the
influent. Because treatment takes place in open tanks, and
because organic compounds in the ground water are readily
stripped during agitation, the concentration of the organics
is reduced during the treatment process. The treated water
22
-------
is discharged to Dry Creek under an NPDES permit issued by
the State of Nebraska.
Alternative 5:
Estimated Capital Cost: $59,600
Estimated Annual Operation and Maintenance (O&M)
Costs: $431,300 (years 1-5)
$436,300 (years 6-10)
Estimated Implementation Time Frame: (10 years with future action)
Estimated Present Worth of Capital and Operating
Costs: $2,709,000
This alternative im the same as Alternative 4 vith the
addition of future controls to that system. The additional
system would include ground water extraction and treatment
equipment designed specifically for the removal of organic
compounds. Under this alternative, an evaluation of the
effectiveness of Alternative 4 extraction and treatment
system would be performed at the end of five years of
operation to determine if remedial action objectives have
been met at that time. The evaluation would be specific to
organic compounds and would estimate the rate of removal of
these compounds from the affected areas, the mass remaining
in the soils and ground water, and the time until remedial
action objectives would be achieved. If future action were
determined to be necessary, ground water containing organic
compounds would be extracted from the area near the north
side of the main production building (current data shows
this to be the area with the highest concentrations of
organics in the soil). The extracted water would be routed
to a treatment system specifically designed to remove
organic compounds. Either activated carbon or aeration
treatment would be used. The organic compounds detected in
ground water are readily absorbed onto activated carbon or
removed from water through aeration. The type of extraction
system, treatment, system size, and flow rates would be
designed to provide sufficient contact time between the
water containing organic compounds and the treatment medium
(air or carbon).
Alternative 5A:
Estimated capital Cost: $173,400
Estimated Annual Operation and Maintenance (OtM)
Co«t«s $521,000
Estiaated Implementation Time Frame: 5 years
Estimated Present Worth of Capital and Operating
Costs: $2,367,000
This alternative is the same as Alternative 4A vith the
addition of future controls to that system. The additional
system would include ground water extraction and treatment
equipment designed specifically for the removal or organic
compounds. Under this alternative, an evaluation of
23
-------
the effectiveness of Alternative 4A enhanced extraction and
treatment system would be performed at the end of five years
of operation if remedial objectives have not been met at
that time. The evaluation would be specific to organic
compounds and would estimate the rate of removal of these
compounds from the affected areas, the mass remaining in the
soils and ground water, and the time until remedial
objectives would be achieved. If future action were
determined to be necessary, ground water containing organic
compounds would be extracted from the area near the north
side of the main product building (current data shows this
to be the area with the highest concentrations of organics
in the soil). The extracted water would be routed to a
treatment system specifically designed to remove organic
compounds. Either activated carbon or aeration treatment
would be used. The organic compounds detected in ground
water are readily absorbed onto activated carbon or removed
from water through aeration. The type of extraction system,
treatment, system size, and flow rates would be designed
to provide sufficient contact time between the water
containing organic compounds and the treatment medium (air
or carbon).
Alternative 7:
Estimated Capital Cost: $1,366,400
Estimated Annual Operation and Maintenance (O&M)
Costs: $546,900 (years 1-5)
$431,300 (years 6-10)
Estimated Implementation Time Frame: 10 years
Estimated Present Worth of Capital and Operating
Costs: $4,346,000
This alternative would add vacuum extraction of organic
compounds in the soil to the existing ground water
extraction and treatment system described in Alternative 4.
Soil vapor extraction in areas of the Lindsay site where
organic compound* have been detected would be designed to
remove organic compounds at a higher rate than is offered by
well-induced gravity drainage and ground water extraction
alone. Each soil vapor extraction well would have a 2 inch
diameter casing in a 4 inch boring extending down to
near the water table. It is anticipated that the easing
would be screened at least 10 feet below ground surface to
minimise short circuiting (extraction of surface air rather
than organic vapors in the soil). The PVC casing end screen
would be suitably sand-packed and sealed. It would
terminate in e vacuum header. The network of header
attachments would be grouped into the north and south
systems with the plant ditch being the dividing line. The
vacuum sources would include four positive displacement
blowers, each rated et 250 cfm and equipped with 25 HP
motor. Extracted vapors would flow through a carbon
adsorption filter prior to release to the environment. Air
emissions will meet all applicable ambient air quality
24
-------
standards established for the state of Nebraska. It is
estimated that approximately 250 extraction wells would be
needed to fully cover all soil areas contaminated with
organics. This estimation is based on the radius of
influence of each extraction well being 25 feet.
Alternative 7A:
Estimated Capital Cost: $1,539,800
Estimated Annual Operation and Maintenance (O&M)
Costs: $636,600
Estimated Implementation Time Frame: 5 years
Estimated Present Worth of Capital and Operating
Costs: $3,800,000
Alternative 7A would add vacuum extraction of organic
compounds to the enhanced aquifer ground water extraction
and treatment described for Alternative 4A. Soil vapor
extraction in areas of the Lindsay site where organic
compounds have been detected would be designed to remove
organic compounds at a higher rate than is offered by well-
induced gravity drainage and ground water extraction alone.
Each soil vapor extraction well would have a 2 inch diameter
casing in a 4 inch boring extending down to near the
water table. It is anticipated that the casing would be
screened at least 10 feet below ground surface to minimize
short circuiting (extraction of surface air rather than
organic vapors in the soil). The PVC casing and screen
would be suitably sand-packed and sealed. It would
terminate in a vacuum header. The network of header
attachments would be grouped into the north and south
systems with the plant ditch being the dividing line. The
vacuum sources would include four positive displacement
blowers, each rated at 250 cfm and equipped with 25 HP
motor. Extracted vapors would flow through a carbon
adsorption filter prior to release to the environment.
Air emissions will meet all applicable ambient air quality
standards established for the state of Nebraska. It is
estimated that approximately 250 extraction veils would be
needed to fully cover all soil areas contaminated with
organics. This estimation is based on the radius of
influence of each extraction well being 25 feet.
Alternative 7B:
Estimated capital Cost:
$544,857 + $48,630 (Pilot Study) - $593,500
Estimated Annual Operation and Maintenance (O&M)
Costs: $636,600
Estimated Implementation Time Flame: 5 years
Estimated Present Worth of Capital and Operating
Costs: $3,006,600
Alternative 7B would add vacuum extraction of organic
compounds from soils (if determined to be practicable as a
25
-------
FIGURE VII- 1
ALTERNATIVE 4
Process Flow Diagram
Existing Groundwaler Treatment System
Lindsay Manufacturing Co.
Lindsay . Nebraska
Dames * Moore.
-------
FIGURE VII-2
Pro;jor*d Location ol New Interceptor Wei
Lindsay Manufacturing Slta
Oames & Moore.
-------
result of the pilot study) to the enhanced aquifer ground
water extraction and treatment described for Alternative 4A.
Alternative 78 would employ a soil vapor extraction pilot
study to determine the practicability of vacuum extraction
technology on removing volatile organic compounds from the
soils at the Lindsay site. Soil vapor extraction in areas
of the Lindsay site where organic compounds have been
detected would be designed to remove organic compounds at a
higher rate than is offered by well-induced gravity drainage
and ground water extraction alone. Each soil vapor
extraction well would have a 2 inch diameter casing in a 4
inch boring extending down to near the water table. It is
anticipated that the casing would be screened at least 10
feet below ground surface to minimize short circuiting
(extraction of surface air rather than organic vapors in the
soil). The PVC casing and screen would be suitably sand-
packed and sealed. It would terminate in a vacuum header.
The network of header attachments would be grouped into the
north and south systems with the plant ditch being the
dividing line. The vacuum sources would include four
positive displacement blowers, each rated at 250 cfm and
equipped with 25 HP motor. Extracted vapors would flow
through a carbon adsorption filter prior to release to the
environment. Air emissions will meet all applicable ambient
air quality standards established for the state of Nebraska.
A re-estimation of the number of extraction wells outlined
in Alternative 7A was completed. It was estimated that a
total of 100 soil vapor extraction wells would be sufficient
to cover the area of organic contamination in the soil. The
same assumptions utilized in Alternative 7A were utilized.
In summary, an estimate of 20 extraction wells would be
installed in the sand channel and 80 extraction veils would
be installed in the clay/silt soils underlying the main
plant building. Note that if the outcome of the pilot study
proves that soil vapor extraction is practicable, the design
of the system using actual data derived during the study
will determine the actual number of extraction wells that
would be required to effectively remove the organic
compounds from the soil.
VIII. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
EPA uses nine criteria to evaluate the identified remedial
alternatives in order to selective a preferred
alternative/alternatives. The nine evaluation criteria are
summarised.
Threshold Criteria
1. OVERALL PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
addresses whether or not a remedy provides adequate protection
and describes how risks posed through each pathway are
eliminated, reduced or controlled through treatment, engineering
controls, or institutional controls.
26
-------
2. COMPLIANCE WITH ARARs addresses whether or not a remedy will
meet all of the applicable or relevant and appropriate
requirements of other Federal and State environmental statutes
and/or provides grounds for invoking a waiver.
Primary Balancing Criteria
3. LONG-TERM EFFECTIVENESS AND PERMANENCE refers to the ability
of a remedy to maintain reliable protection of human health and
environment over time once cleanup goals have been met.
4. REDUCTION OF TOXICITY, MOBILITY, OR VOLUME is the
anticipated performance of the treatment technologies a remedy
may employ.
5. SHORT-TERM EFFECTIVENESS addresses the period of time needed
to achieve protection, and any adverse impacts on human health
and the environment that may be posed during the construction and
implementation period until cleanup goals are achieved.
6. IMPLEMENTABILITY is the technical and administrative
feasibility of a remedy, including the availability of materials
and services needed to implement a particular option.
7. COST includes estimated capital and operation and
maintenance costs, and net present worth costs.
Modifying Criteria
8. STATE ACCEPTANCE indicates whether, based on its review of
the RI/FS and Proposed Plan, the State concurs in, opposes, or
has no comment on the preferred alternative at the present time.
9. COMMUNITY ACCEPTANCE is assessed in the Record of Decision
following a review of the public comments received on the RI and
FS reports, the administrative record, and the Proposed Plan.
This section profiles the performance of the. alternatives
against the nine criteria.
OVERALL PROTECTION. All of the alternatives, with the exception
of the "no action" alternative, would provide adequate protection
of human health and the environment by eliminating, reducing, or
controlling risk through treatment, engineering controls, or
institutional controls. Alternatives 4/4A, 5/5A, and 7/7A/7B
provide extraction and treatment of ground water, and ara
therefore equivalent in overall protection of human health and
the environment. The soil vacuum extraction technique of
Alternativas 7/7A/7B offers additional protection because the
volatile organics may ba removed from the soils, if this
technology proves to be practicable during the pilot study to be
conducted as part of Alternative 7B. Application of Alternative
2 provides protection of human health, but would result in
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restrictions of future development of the ground water resource.
Because the "no action" alternative is not protective of human
health and the environment, it is not considered further in this
analysis as an option for this site.
COMPLIANCE WITH ARARS. All alternatives would meet their
respective applicable or relevant and appropriate requirements of
Federal and State Regulations. Application of Alternative 2
(natural attenuation of ground water) would require the longest
time frame to reach compliance.
LONG TERM EFFECTIVENESS AND PERMANENCE. Alternatives 7/7A/7B
would reduce the inherent hazards posed by the volatile organic
compounds in the soils. By removing the volatiles from the soils
through soil vapor extraction this would prevent the further
migration of contaminants to ground water and other soils. The
enhanced extraction and treatment system would contain the
contaminant plume and also remove the contaminants. Under
Alternatives 4, 4A, 5, 5A, and 7/7A/7B the remedial action
objectives for ground water would be met. The remedial action
objectives for the Lindsay site are the state and EPA primary and
secondary Maximum Contaminant Levels (MCLs) for drinking water
for potential future use of the ground water as a public health
and aesthetically protected drinking water source.
Alternative 2 would eliminate potential pathways of exposure
associated with potential future use of ground water, but does
not offer long-term controls comparable of those of other
alternatives.
REDUCTION OF TOXICITY, MOBILITY, OR VOLUME. The only alternative
which does not immediately treat the contaminants to reduce the
toxicity, mobility, or volume of the organics and metals is
Alternative 2. For this alternative it is assumed that
contaminants would eventually be removed through natural
attenuation, but the tin* required for natural processes to
reduce the toxicity, nobility, or volume of contaminants is
likely to be much longer than the time required using engineered
extraction techniques employed by the other alternatives.
Alternatives 4/4A and 5/5A offer extraction and treatment of
ground water and are equivalent in reduction of contaminant
mobility, toxicity, and volume in the ground water but not in
site soils. Alternatives 7/7A/7B would permanently remove
contaminants from the soil (if this technology proves to be
practicable) in Alternative 7B) and ground water thereby raducing
the voluM of contaminants, raducing the toxicity and raducing
the mobility.
SHORT TERN EFFECTIVENESS. Alternatives 4A, 5A, 7A, 7B, offer the
greatest potential for rapid achievement of remedial objectives.
Installing and operating a naw extraction wall in an appropriate
location would dacraaaa the time required to raduca
concentrations in ground water of metals and organic compounds.
Alternatives 4, 5, and 7, ara likely to be longer than
Alternatives 4A/5A/7A/7B in achieving remedial objectives because
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they do not include enhanced extraction of ground water.
Alternatives 7A and 7B may offer advantages of time over
Alternatives 5A and 4A because of the proposed vacuum extraction
techniques. Alternative 2 relies on natural processes rather
than engineered systems and therefore is the longest-term alternative
IMPLEMZNTABILITY. Few associated administrative difficulties
that could delay implementation are associated with any
alternative. Since Alternatives 4, 4A, 5, 5A, 7, and 7A require
the use of the currently operating extraction and treatment
system, no problems are anticipated with the continued operation
of this system. Note that Alternatives 4A, 5A, and 7A call for
the enhancement of the current system but no problems with
implementation are anticipated since this technology has been
used extensively. Skilled workers needed to construct the
enhanced ground water treatment system are available in the area.
Lindsay personnel are familiar with this system since it has been
in operation for six years. The activated carbon canisters that
are part of the soil vapor extraction system in alternatives 7A
and 7B should be available in the area. Since soil vapor
extraction for the treatment of soils has not been done in the
area a pilot study should be completed to determine the
effectiveness of this process on site soils. The practicability of
this method for soil treatment would be assessed during the pilot
study. The technology has been used to address similar
contaminants at other Superfund sites.
COST. Because Lindsay would cease operation of the extraction
system under Alternative 2, and because the alternative involves
the smallest capital equipment expenditure, it is the lowest cost
alternative. Continued operation and maintenance costs of the
treatment system incurred under Alternatives 4 and 5 make these
systems moderately costly. For Alternatives 4A and 5A,
additional treatment capacity and additional piping systems would
be required to enhance the effectiveness of remediation.
However, because these additional measures may reduce the time
required to meet remedial objectives, cost savings nay result.
Alternatives 7/7A/7B would involve installation of vapor
extraction wells and are estimated to cost nearly twice as much
as Alternative 4A, however they may provide enhanced protection
of human health and the environment. Costs are shown in Table
Viil-i. Alternative 7A is determined infeasible for tvo reasons:
(1) 250 extraction wells are excessive for an active site; and
(2) no pilot study has been recommended.
Alternative 7B is the preferred alternative for the Lindsay
site basad en how it compares to all the other options under
consideration. The strongest elements of Alternative 7B are the
following:
(1) the alternative provides long-term effectiveness and
permanence; and
(2) the alternative reduces toxicity, mobility, and volume. The
alternatives are evaluated based on the nine EPA criteria.
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STATE AND SUPPORT AGENCY ACCEPTANCE. Both the State of Nebraska
and U.S. EPA support the preferred alternative.
COMMUNITY ACCEPTANCE. Comments received during the public
comment period shows that the community supports remediation at
the site. There were no comments from community members against
the preferred alternative except for Linday's comments on the
pilot study.
IX. SELECTED REMEDY
* Alternative 7B:
Estimated Capital Cost:
$544,857 * $48,630 (Pilot Study) - $539,500
Estimated Annual Operation and Maintenance (O&M)
Costs: $636,600
Estimated Implementation Time Frame: 5 years*
Estimated Present Worth of Capital and Operating
Costs: $3,006,600
The preferred alternative for cleanup of the Lindsay site is
Alternative 7B. For the treatment of ground water, the preferred
alternative would utilize an enhanced version of the ground water
extraction and treatment system currently being operated.
Simultaneously a soil vapor extraction pilot study would be run
to determine the practicability of this technology on removing
volatile organic compounds (VOC) from the soils at the Lindsay
site. If determined to be practicable, this remedy will include
the extraction of VOCs from the soils that are a source of
contamination to the aquifer.
Alternative 7B is considered to be preferable to all other
alternatives including 7A because it should reduce contaminant
volume, toxicity, and mobility to the greatest extent, and the
soil vapor extraction pilot study will determine the
practicability of soil treatment. Alternative 7B addresses two
contaminated media, ground water and soils.
1) Contaminated Ground Water
The existing ground water extraction and treatment system
would b« enhanced either by increasing on-site pumping or by
the installation of an additional interceptor wall aa
described below. Either the AOIW would be modified to
increase ita pumping rate or an additional intarcaptor wall
identified aa TIW (for third interceptor wall) would ba
installed. Either of two pumping methods are applicable:
a) modification of the AOIW to increase ita pumping rate or
b) the addition of a supplemental interceptor well between
the AOIW and the irrigation well 154278 southeast of the
site.
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The current pumping system would be enhanced either by
increasing the rate of the AOIW *o 1,400 gpm or by
installing a third extraction well, identified as TIW, to
supplement the present AOIW. The AOIW is presently designed
to pump 1,000 gpm. To enhance ground water extraction this
well must be either replaced by a larger well at the same
location or adjacent to the existing location. Under method
a., the replacement wells would be designed to produce
approximately 1,400 gpm, which is the maximum yield of the
aquifer at this location. Under method b., the TIW would be
sited near the location shown on Figure VII-2 and would be
designed to produce 600 gpm. This new well would supplement
the existing AOIW. Under either method the OIW would
continue to be pumped at an average rate of 600 gpm.
Treatment of ground water and discharge of treated water
would be conducted as described. The currently treatment
method employs alkaline precipitation of zinc salts with the
addition of flocculating polymers in a mix tanX, followed by
sedimentation of the flocculant. The existing system is
described by the flow diagram in Figure VIl-l. It is
currently designed to handle up to 1,000 gallons per minute
(gpm), but will increase as stated for this alternative.
The dewatered solid residuals are disposed of at a local
landfill. Supernatant is recycled to the treatment system.
Current data indicates that the system removes approximately
700 pounds/day of zinc metal from the influent. Because
treatment takes place in open tanks, and because organic
compounds in the ground water are readily stripped during
agitation, the concentration of the organics are reduced
during the treatment process. The treated water is
discharged to Dry Creek under an NPDES permit issued by the
State of Nebraska.
2) Contaminated Soil
This portion of the remedy includes a pilot study to
determine the practicability of removing volatile organic
compounds from the soils using soil vapor extraction, and if
practicable, the extraction of VOCs from soils. Outlined
below are the assumptions that will be used during the pilot
study:
Duration of pilot study - four (4) weeks
Two 2 inch Schedule 80 PVC extraction veils to be
Installed at a depth of at least 35 feet (in the areas
of highest contamination)
Extraction veils screens will be 15 feet long with
Schedule 80 PVC 50 slot screen
Use 1/4 inch pea gravel for the veil screen pack
One blower per veil venting to the atmosphere
(two blowers total)
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Soil vacuum will *>e measured to assess radius of influence
A total of 22 soil vapor samples will b« collected and
analyzed for tetrachloroethene, 1,1,1,-trichloroethane,
dichloroethane, and dichloroethene using U.S. EPA
Method 8010.
A re-estimation of the number of the 250 extraction
wells outlined in Alternative 7A was completed. Alternative
7A is considered to not be feasible because 250 soil vapor
extraction wells would be excessive for an operating
facility. It was estimated that a total of 100 soil vapor
extraction wells would be sufficient to cover the area of
organic contamination in the soil, for the selected
Alternative 7B. The same assumptions utilized in
Alternative 7A were utilized. In summary, an estimate of 20
extraction wells would be installed in the sand channel and
80 extraction wells would be installed in the clay/silt
soils underlying the main plant building. Note that if the
outcome of the pilot study proves that soil vapor extraction
is feasible, the design of the system using actual data
derived during the study will determine the actual number of
extraction wells that would be required to effectively
remove the organic compounds from the soil.
U.S. EPA and NDEC will evaluate other treatment or
source control measures in the event that the pilot shows
that this technology is not practicable. Subject to the
outcome of the pilot study, EPA will consider reopening or
amending the ROD if warranted, otherwise the agency will
proceed with the selected remedy. If soil vapor extraction
is determined not to be practicable, the Agency will
consider an additional study to evaluate other treatment
technologies or source control measures to reduce or
eliminate the source(s) of contamination to ground water.
If no technologies are shown to be practicable, the VOCs in
the soil will be eliminated through the continued operation
of the enhanced extraction and treatment system. As the
vocs are released from on-site soils to ground water the
ground water will be extracted and treated.
In addition, the selected remedy will require installation
of additional monitoring wells to monitor ground water quality
down gradient of irrigation well 154278. The cost of the .
additions*: veils is not included in the present worth of the
selected vsmedy, since additional monitoring veils would have
been needed regardless of the remedy selected. This cost was not
included in the cost estimate of any of the Alternatives.
If appropriate to protect human health, as part of the
implementation of this ROD, EPA and NDEC will evaluate options to
ensure that drinking water wells are not installed in areas of
the contaminant plume on and off site.
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Some changes may be made to the selected remedy as a result
of the remedial design and construction process. Such changes in
general will reflect modifications resulting from the engineering
design process.
X. STATUTORY DETERMINATIONS
Under its legal authorities, the Environmental Protection
Agency's primary responsibility at Superfund sites is to
undertake remedial actions that achieve protection of human
health and the environment. In addition, sections 121 of CERCLA
establishes several other statutory requirements and preferences.
These specify that when complete, the selected remedial action
for this site must comply with applicable or relevant and
appropriate environmental lavs unless a statutory waiver is
justified. The selected remedy also must be cost effective and
utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maximum
extent practicable. Finally, the statute includes a preference
for remedies that employ treatment that permanently and
significantly reduce the volume, toxicity, or mobility of
hazardous wastes as their principal element. The following
sections discuss how the selected remedy meets these statutory
requirements.
1. Protection of Human Health and the Environment
The selected remedy protects human health and the
environment through extraction and treatment of contaminated
ground water and soil vapor, if soil vapor extraction is
determined practicable during the pilot study. The contaminants
will be permanently removed from the ground water and from the
soil through volatilization of active soil vapor extraction.
Extraction of the contaminated ground water will also
eliminate the threat of exposure due to the spread of
contamination to a larger area by checking the migration of the
plume. If soil vapor extraction is determined to be practicable
during the pilot study, volatilization of contaminants from site
soils will eliminate the source of continued contamination of the
ground water thus reducing the time needed for remediation.
2. Compliance with Applicable or Relevant and Appropriate.Requirements
The selected remedy, enhanced ground water extraction and
treatment end a pilot study to determine the practicability of
soil vapor extraction on removing volatile organic* from site
soils will comply with all applicable or relevant and appropriate
chemical-, action-, and location-specific requirements (ARARs).
The ARARs are presented below.
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Action-SDecifi,^ ARARs;
Clean Water Act requirements under 40 CFR 122-125 for point
source direct discharge. Under the National Pollutant Discharge
Elimination System (NPDE5) effluent standards, monitoring
requirements, and standard conditions for discharge are set.
NPDES discharge limits for metals and pH will be met using
alkaline precipitation with the addition of flocculating polymers
in a mix tank, followed by sedimentation of the flocculant.
Discharge limits for VOCs will be met through treatment in open
tanks and agitation to promote volatilization during the above
stated process. NPDES requirements will be met through
compliance with State regulation Title 119, Rules and Regulations
Pertaining to the Issuance of Permits Under the National
Pollutant Discharge Elimination System.
Title 129, Nebraska Air Pollution Control Rules and
Regulations establishes a maximum limit for total volatile
organic compound emissions at 2.5 tons/year. This emission level
applies to all processing machines, equipment or devices having
the potential to emit a regulated amount of toxics. It is not
believed that Lindsay's manufacturing process emits VOCs.
Therefore, the limit applies to VOCs emitted during cleanup of
the site from the soil vapor extraction system and the ground
water treatment facility. The soil vapor extraction system will
be designed so that the combination of air emissions will not
exceed regulated quantities.
RCRA requirements, 40 C.F.R. Part 261 i£ seq. or Nebraska
Title 128, Rules and Regulations Governing Hazardous Waste
Management. Under current RCRA requirements, the sludge produced
during the ground water treatment process is tested for EP
toxicity to determine whether waste sludge is hazardous and
therefore subject to RCRA requirements. To date, sludge has not
been determined to be EP toxic. Beginning September 25, 1990,
large quantity generators, and March 29, 1991 small quantity
generators (as defined in 40 C.F.R. Part 260.10), must test
wastes produced in accordance with the Toxicity Characteristic
Leaching Procedure (TCLP) 55 £tli Eta- 11798 i£ ug. (March 29,
1990) in determining whether such waste is a hazardous waste and
therefore subject to RCRA requirements. Beginning on the
appropriate date, the sludge will be tested under the new TCLP
requirements and handled appropriately in accordance with RCRA
and State of Nebraska Title 128 including, Land Disposal
Restrictions of 40 C.F.R. Part 268, and EPA's Off-Site Disposal
Policy.
ChenieaJ-aaaeifte ARARst
Safe Drinking Water Act (SDWA) Maximum Contaminant Levels
(MCLs) for aquifers with Class I and Class II characteristics
(i>*> irreplaceable, current or potential drinking water
sources).
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SDWA MCL for:
1,2-dichloroethane is 5 ug/1
1,1-dichloroethene is 7 ug/1
cis-l,2-dichloroethene is 70 ug/1 (proposed MCL)
trans-l,2-dichloro«thene is 100 ug/1 (proposed MCL)
1,1,1-trichloroethane is 200 us/1
pH range 6.5-8.5 (secondary MCL)
zinc is 5,000 ug/1 (secondary MCL)
sulfate is 250,000 ug/1 (secondary MCL)
cadmium is 10 ug/1
chromium is 50 ug/1
lead is 50 ug/1
State of Nebraska Rules and Regulations under Title 118
Ground Hater Quality Standards and Use Classification (State of
Nebraska Ground Water Clean-up Levels). The above stated MCLs
are standards adopted for the State of Nebraska except for the
following:
chromium 100 ug/1
cadmium 5 ug/1 (proposed MCL)
The more stringent of the ground water standards will be
applied to this site in determining when aquifer restoration
has been completed. This will be assured through ground water
monitoring of the aquifer.
Location-Specific ARARs;
A portion of the Lindsay facility is on the 100 year flood
plain. However, the ground water treatment facility is located
outside the 100 year flood plain. Therefore, there are no
location-specific ARARs that apply.
Other Criteria. Advisories fir. Guidance £a fee. Considered for this
Remedial Action (TBCslt
For compounds without an MCL, proposed MCL or state ground
water standard, a risk based cleanup level corresponding to an
excess lifetime cancer risk of 1 x 10(-6) will be calculated
using slope factors for carcinogens. In cases where these levels
are below a laboratory quantification limit the lowest attainable
detection linit will be used as the cleanup goal.
3. Cost-Effectiveness
The selected reMdy is cost-effective because it provides
the best balance among the evaluation criteria. It provides a
higher degree of overall protection then the less costly
alternative by treating source areas and remediating ground
water.
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4. Utilization of Permanent Solutions and Alternative Treatment
Technologies or Resource Recovery Technologies to the Maximum
Extent Practicable.
EPA has determined that the selected remedy represents the
maximum extent to which permanent solutions and treatment
technologies can be utilized in a cost-effective manner for the
site. Of those alternatives that are protective of human health
and the environment and comply with applicable standards, EPA has
determined that this selected remedy provides the best balance of
trade-offs in terms of long-term effectiveness and permanence,
reduction in toxicity, mobility, or volume achieved through
treatment, short-term effectiveness, implementability, cost,
while also considering the statutory preference for treatment as a
principal element and considering State and community input.
Best available data informed EPA and NDEC that elevated soil
concentrations ("hot spots") are contributing to ground water
contamination northeast of the main plant building and in the
north central portion of the site.
5. Preference for Treatment as a Principal Element
• The selected remedy uses technology for ground water
treatment and active soil vapor extraction, if proven practicable
during the pilot study, for source control and thus satisfies the
statutory preference for remedies that employ treatment of the
principal threat which permanently and significantly reduces the
toxicity, mobility, or volume,of hazardous substances as a
principal element.
XI. RESPONSIVENESS SUMMARY
A. Overview
In the proposed plan released for public comment, EPA and
NDEC presented a preferred alternative which addressed the soil
and ground water contamination at the Lindsay Manufacturing
Companyxsite.
After receiving public comment or the preferred alternative,
EPA selected this alternative in the Record of Decision (ROD).
The selected remedy includes enhancing the current ground water
pumping sjysjts* either by modifying the AOIW to increase the
pumping rate or installing an addition interceptor veil southeast
of the site. Also included in the selected remedy is a pilot
study to determine the effectiveness of soil vapor extraction of
volatile organic contaminants. If determined to be practicable,
soil vapor extraction will be performed to aid in the elimination
of the source of ground water contamination.
During the comment period, one community member expressed
concern that the site be cleaned up and that they be protected
"in all ways". No other comments by community members on the
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preferred alternatives were submitted during the public comment
period. The State Senator representing the district in which the
town of Lindsay is located stated that the preferred alternative
"was conceived after much research and forethought". Lindsay
Manufacturing Company, the potentially responsible party (PRP)
for the site did not support the pilot study for soil vapor
extraction. In their comment the PRP proposed a new alternative
if a soil treatment remedy was selected.
B. Background on Community Involvement
A community relations plan (CRP) for the site was developed
in June 1989. Objective* of the CRP were to identify primary
issues and provide information to news media, on November 17,
1989, a news release was issued which announced the availability
of the administrative record at the Columbus, Nebraska Library.
A public notice was published in the Omaha World Herald and the
Columbus Telegram on July 10, 1990 announcing the Public Hearing
and availability of the Proposed Plan and the administrative
record. Prior to the public comment period for the Proposed
Plan, no significant public issues or concerns were communicated
to EPA or NDEC.
C. Summary of Comments Received During Public Comment Period
Significant comments presented during the public comment
period on the administrative record and the Proposed Plan are
summarized below. The comment period was scheduled from July 16,
1990, to August 15, 1990. At the request of Lindsay, the comment
period was extended to August 31, 1990. The comments arc
categorized as general comments and comments specific to the
Proposed Plan.
General Comments
1. One community member commented that the site be cleaned up
and they be protected.
EPA Response: EPA has selected a remedy which will cleanup the
site to levels that are protective of human health and the
environment.
V
2. State Senator Jennie Robak commented that the preferred
alternative was conceived after much research and forethought and
that the cleanup bagin soon with the work don* expeditious in
nature.
EPA Responaa: In addition to the abova response, EPA will begin
remedial dasign and remedial action activities aftar the ROD is
issued.
3. Rimkus consulting Group (RCG), a consultant for The Hartford,
commented on the Remedial Investigation that volatile organic
contaminants have migrated from a sourca area other than the
former acid disposal pit deep into the soil at the sita.
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EPA Response: EPA's selected remedy will address the soil
contamination, if the pilot study proves that soil vapor
extraction is practicable.
4. Lindsay commented that the selection of soil vapor extraction
as the remedy to cleanup VOC contamination in the soils at the
site is not consistent with the National Contingency Plan (NCP)
as required by the Superfund law.
EPA Response: EPA has selected soil vapor extraction as the
remedy for the treatment of VOC contaminants at the site. This
treatment technology will address the principal threat of VOC
contamination to the aquifer. In order to assure this treatment
technology is practicable, EPA has selected to use a pilot study.
If soil vapor extraction is shown to be impracticable, EPA will
evaluate other treatment technologies or controls for VOC
contamination source areas. This is consistent with 40 CFR
§ 300.430(a)(iii)(A) and.(B) of the NCP.
Specific Comments to the Proposed Plan
1. Lindsay submitted several comments opposing soil vapor
extraction due to possible technical problems and questioned the
cost effectiveness.
EPA Response: As stated in the response to General Comment 14,
EPA selected a pilot study to determine if this technology is
practicable and believes that soil vapor extraction, if
practicable, is necessary to address the source(s) of volatile
organic compound contamination to the aquifer.
2. Lindsay submitted comments opposing EPA's and NDEC's
evaluation of risk associated with the site.
EPA Response: EPA and NDEC have determined the site poses
substantial risk to human health and the environment and that the
remedial action identified in the Proposed Plan is necessary and
appropriate.
X
3. Lindsay commented that dates for submittal of RI/FS reports
were not included in the proposed plan and that the Proposed Plan
did not include the volume of ground water treated to date..'
EPA Response: This information is included in the administrative
record and does not affect the remedy identified in the Proposed
Plan.
4. Lindsay commented that Appendix B of the proposed plan
(Maximum concentrations of Contaminants and Maximum Contaminants
Levels (MCLS)) does not reflect current concentrations of
contaminants at the site and that some of the listed contaminants
did not have analytical validation.
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EPA Response: As explained in the Proposed Plan, Appendix B
presents maximum concentrations of contaminants detected either
on-site or off-site. Current concentrations of contaminants are
provided in quarterly reports submitted by Lindsay. These
reports are included in the administrative record. EPA and NDEC
acknowledge that some of these contaminants have not been found
in recent sampling.
5. Lindsay commented that the Proposed Plan incorrectly
indicates the need for additional ground water monitoring wells.
EPA Response: As stated in the Proposed Plan, irrigation well
#54278 detected contamination during the 1989 irrigation season.
This has been verified with 1990 sampling results. Sampling
conducted in August 1990 by NDEC showed VOC contamination at
levels greater than MCLs. Additional ground water monitoring
wells will need to be installed to determine if contamination is
migrating further downgradient.
6. Lindsay proposed a new alternative in the event a soil
treatment remedy is selected. This alternative consisted of
additional shallow ground water interceptor wells to de-water
site soils above the aquifer.
EPA Response: EPA has selected soil vapor extraction as the
remedy to remove VOC contamination from the site soils. It the
pilot study shows this technology to be impracticable, EPA will
consider the above stated alternative when evaluating other
technologies or controls to address VOC source areas.
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