United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R07-91/045
March 1991
Superfund
Record of Decision
Lee Chemical, MO
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50272-101
REPORT DOCUMENTATION 11. REPORT NO. 1 ~ 3. ReclpIent'a AcC88810n No.
PAGE EPA/ROD/R07-91/045 -
4. TlUe and StmtlUe S. Report D818
SUPERFUND RECORD OF DECISION 03/21/91
Lee Chemical, MO 6.
First Remedial Action - Final
7. Author(a) 8. F8rlonnlng Organization RapC. No.
8. F8rlonnlng Orgalnlzatlon Name and Add",.. 10. ProjactlTaakiWoril Unit No.
11. ContraC1(C) or Grant(G) No.
(C)
(G)
12. Sponaorlng Organization Name and Addnt88 13. Type o' Report . Period Covered
U.S. Environmental Protection Agency 800/000
401 M Street, S.W.
Washington, D.C. 20460 14.
15. Supplementary Notea
16. Ab81ract (Umlt: 200 woJda)
The 2.5-acre Lee Chemical site is a former water treatment plant and chemical
repacking and distributing facility in Liberty, Clay County, Missouri. Land use in
the area is commercial and rural. The estimated 17,000 people who reside in Liberty
obtain drinking water from municipal water wells located approximately 2,000 feet
southeast of the site. These wells draw water from the alluvial aquifer underlying
the site. From 1920 to 1962, the city of Liberty used the site as the city's water
treatment plant. From 1965 until 1975, when the city repossessed the property, the
site was leased to Lee Chemical Company for packaging and distributing commercial and
industrial cleaning solvents and other chemicals, some of which were reprocessed
onsite in 55-gallon drums. In 1977, as required by EPA, the city removed and
disposed of approximately three hundred 55-gallon drums of waste off site. In 1979,
low levels of TCE were detected in the public water supply wells. Subsequent EPA and
State investigations revealed contaminated ground water and soil, and deteriorated
drums and chemical containers, and in 1982 the city and State identified the site as
a source of TCE contamination in the public water supply. In 1983, the onsite water
plant building and its contents were demolished and disposed of offsite. In 1984, in
(See Attached Page)
17. Documant Analyaia L DaacrlpI018
Record of Decision - Lee Chemical, MO
First Remedial Action - Final
Contaminated Media: soil, gw
Key Contaminants: VOCs (TCE)
b. Identifier8l0pen-EncIecI Terma
c. COSA 11 ReIdIGroup
18. AVllilability Statement 18. Sac:urlty Cia.. (ThIa Report) 21. No. o' Pagea
None 52
20. Securtty Cia.. (Thla Page) 22. PrIce
NonA
See ". ~(4.n)
(See AI6-l38.18)
m.1rucII- 0" -
(Formerly NT1S-35)
~lo'Comme'ce
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EPA/ROD/R07-9l/045
Lee Chemical, MO
First Remedial Action - Final
Abstract (Continued)
an effort to contain the contaminated ground water plume and reduce TCE levels in the
water supply, the city discharged water from the most highly contaminated of its
municipal water wells through an abandoned sewer line to the Missouri River and Shoal
Creek. Later that year, an abandoned municipal well onsite was added to the plume
control measure and the discharge was diverted to an abandoned water main to nearby
Town Branch Creek. Currently, no detectable levels of TCE are found in wells connected
to the water supply system. This Record of Decision (ROD) addresses soil and ground
water contamination, and provides a final remedy for the site. The primary
contaminants of concern affecting the soil and ground water are VOCs including TCE.
The selected remedial action for this site includes installing an in-situ aqueous soil
washing system consisting of infiltration trenches to enhance the flushing of .
contaminants from onsite soil to the underlying aquifer; pumping ground water to flush
contaminants from the underlying aquifer to the extraction system and to control ground
water movement away from the site, followed by onsite discharge to surface water;
implementing a contingency phase ground water treatment project consisting of air
stripping or other treatment methods, if additional treatment of discharge water
becomes necessary to meet health based risk levels, existing NPDES permit limits, or
other ARARs; and monitoring ground water and air. The estimated present worth cost for
this remedial action is $550,000, which includes an annual O&M cost of $52,000 for 5
years. If treatment is deemed necessary, the revised present worth cost for this
remedial action is $670,000, which includes an annual O&M cost of $67,000 for 5 years.
PERFORMANCE STANDARDS OR
Chemical-specific ground
l,l,2-TCE 5 ug/l (MCL).
GOALS: Chemical-specific goals for soil were not provided.
water clean-up goals are based on SDWA MCLs and include
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RECORD OF DECISION
DECLARATION
LEE CHEMICAL SITE
LIBERTY, MISSOURI
Prepared by:
Missouri Department of Natural Resources
Waste Management Program
Jefferson City, Missouri
And
u.S. Environmental Protection Agency
Region VII
Kansas City, Kansas
March 1991
-------
DECLARATION FOR THE RECORD OF DECISION
SITE NAME AND LOCATION
Lee Chemical Site
Liberty, Missouri
STATEMENT OF PURPOSE AND BASIS
This decision document presents the selected remedial action
for the Lee Chemical Site in Liberty, Missouri, 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) and,
to the extent practicable, the National oil and Hazardous
Substances Pollution Contingency Plan (NCP); 40 CFR Part 300
(1990). The Regional Administrator has been delegated the
authority to approve this Record of Decision.
This decision is based upon the contents of the Administrative
Record for the Lee Chemical Site which was developed in
accordance with Section 113(k) of CERCLA, 42 U.S.C. 9613(k). The
A~ministrative Record is available for public review at the Mid-
continent Library, 1000 South Kent, Lib~rty, Missouri and at the
Environmental Protection Agency (EPA) Regional Office, 726
Minnesota Avenue, Kansas City, Kansas. .
The State of Missouri has concurred with the selected remedy
and determined that the selected remedy is consistent with
Missouri laws and regulations.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from
this Site, if not addressed by implem~nting the response action
selected in this Record of Decision (ROD), may present an
imminent and substantial endangerment to public health, welfare,
or the environment.
DESCRIPTION OF THE REMEDY
This final remedy addresses the principal threat at the site
through the remediation of soil contamination and mobile
contaminants released into the groundwater thus reducing the
risks posed by the site.
The major components of the selected 'remedy include:
- Extraction of contaminated groundwater to remove .
contaminants from the aquifer of concern and to control
groundwater movement away from the site;
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- Installation of an in-situ aqueous soil washing system
consisting of infiltration trenches to enhance the flushing
of contaminants from site soils;
- Discharge of the extracted groundwater to Town Branch Creek
under the terms of an NPDES permit; and
- In the event that additional treatment of the discharge
water becomes necessary to meet health based risk levels,
existing NPDES permit limits, or other applicable or
relevant and appropriate requirements; a contingency phase
project consisting of air stripping or other treatment
methods will be implemented to bring the discharge into
compliance.
These response actions would prevent future exposures to
hazardous substances from this site in the City of Liberty's
drinking water supply by containing the contaminated groundwater
plume. These actions will also remove the contaminants from the
soil and groundwater and restore the aquifer to acceptable levels
for unrestricted use.
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 technologies to the
maximum extent practicable for this Site, and satisfies the
statutory preference for remedies that employ treatment that
reduces toxicity, mobility, or volume a~ a principal element.
Because this remedy will result in hazardous substances
remaining onsite above health-based levels, a review will be
conducted within five years after commencement of remedial action
to ensure that the remedy continues to provide adequate
protection of human health and the environment.
~../1ff
Morris Kay
Regional Administrator
U.S. Environmental Protection
Region VII
3- 2/--?'/
Date
Agency
-------
JOHN ASHCROfT
GcMmor
G. TRACY MEHAN III
Diftctor
STATE OF MISSOURI
DEPARTMENT OF NA11JRAL RESOURCES
OFFICE OF THE DIRECTOR
P.O. Box 176
Jefferson Oty, MO 65102
314-7514422
February 21, 1991
Mr. Morris Kay
Regional Administrator
u.s. Environmental Protection
Agency, Region VII
726 Minnesota Avenue
Kahsas City, KS 66101
Dear Mr. Kay:
-
. Division of Encrgy
Division of Environmcntal QUalit}'
Division of Geology and ~nd Su~
Division of Managcmcnt Serviccs
Division of Paries. Recreation.
and Hisroric Prcsctv.ltion
The Missouri Department of Natural Resources has reviewed the Record of
Decision (ROD) for the Lee Chemical site in Liberty, Missouri. The
Department concurs with the selected remedy for the site detailed in the
ROD.
If you have any questions regarding this matter, please do not hesitate
to contact me.
Very truly yours,
L-~~~as
~' G. Tracy Mehan, III
/ Director
GTM:jkh
c:
Mr. Robert Morby, USEPA
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RECORD OF DECISION
DECISION SUMMARY
LEE CHEMICAL SITE
LIBERTY, MISSOURI
Prepared by:
Missouri Department of Natural Resources
Waste Management Program
Jefferson City, Missouri
And
U.S. Environmental Protection Agency
Region VII
Kansas City, Kansas
March 1991
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1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
TABLE OF CONTENTS
SECTION
PAGE
SITE NAME, LOCATION,
AND DESCRIPTION....................... 1
SITE HISTORY AND ENFORCEMENT ACTIVITIES....................1
HIGHLIGHTS OF COMMUNITY PARTICIPATION......................6
SCOPE OF RESPONSE ACTION...................................7
SUMMARY OF SITE
CHARACTERISTICS. . . . . . . . . . . . . . . . . . . . . . . . . . . .7
SUMMARY
OF SITE RISKS..................................... 11
DESCRIPTION OF
ALTERNATIVES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES.......26
10.0 STATUTORY DETERMINATIONS.................................. 36
THE SELECTED REMEDY................................. '. . . . . . 33
11.0 DOCUMENTATION OF SIGNIFICANT CHANGES......................39
i
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FIGURE 1.
FIGURE 2.
FIGURE 3.
LIST OF FIGURES
PAGE
LOCATION OF THE LEE CHEMICAL SITE...................2
REGIONAL LOCATION OF LIBERTY, MISSOURI..............3
LOCATION OF THE LEE CHEMICAL SITE IN
RELATION TO THE CITY OF LIBERTY'S
WELL SUPPLY FIELD................................... 4
ii
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TABLE 1.
TABLE 2.
TABLE 3.
TABLE 4.
TABLE 5.
TABLE 6.
TABLE 7.
LIST OF TABLES
PAGE
SUMMARY OF EXPOSURE PATHWAYS AND
EXPOSED POPULATIONS................................. 14
SUMMARY OF PARAMETER VALUES USED
TO ESTIMATE EXPOSURE................................ 15
SUMMARY OF EXPOSURE DOSES VIA GROUNDWATER
INGESTION AND HEALTH RISK CALCULATIONS..............17
SUMMARY OF EXPOSURE DOSES VIA INHALATION
OF VOLATILIZED VOCs FROM GROUNDWATER AND
HEALTH RISK CALCULATIONS............................18
SLOPE FACTORS FOR CARCINOGENIC EFFECTS
OF CHEMICAL CONTAMINANTS AT
THE LEE CHEMI CAL SITE.................................. 19
CHRONIC REFERENCE DOSES (RFDs) FOR
NONCARCINOGENIC EFFECTS OF CHEMICAL
CONTAMINANTS AT THE LEE CHEMICAL SITE...............20
NUMERICAL VALUES FOR CONTAMINANT-SPECIFIC
ARARS FOR THE LEE CHEMICAL SUPERFUND SITE...........21
TABLE 8a. SCREENING OF ALLUVIAL AQUIFER ALTERNATIVES
(PAGE 1 OF 2)....................................... 28
TABLE 8b. SCREENING OF ALLUVIAL AQUIFER ALTERNATIVES
(PAGE 2 OF 2)....................................... 29
iii
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SECTION 1.0
SITE NAME, LOCATION, AND DESCRIPTION
The Lee Chemical Site (Site) is located along .Missouri Highway
210, approximately 0.7 mile east of Missouri Highway 291 in the
City of Liberty, Clay County, Missouri, approximately 15 miles
east of Kansas City, Missouri as shown on Figure 1. Liberty's
population is approximately 17,000. The City is accessible by
Interstate 35 and Missouri State Highway 291 as illustrated in
Figure 2.
Currently, the site is a lot of approximately 2.5 acres enclosed
within a chain link fence. There are no permanent buildings
currently located on the site. An old water plant building
located on the site was demolished in 1983 and its foundation and
a concrete tank that originally was used as storage while the
water treatment facility was in operation remain. Six abandoned
municipal water supply wells known as Existing Wells 0 through 5
(EW-O through EW-5) developed in the alluvial aquifer also remain
onsite.
The surrounding land use is commercial/rural. A single family
dwelling exists to the northeast, cropland to the south, and
commercial properties to the north and west. The general. slope
of the area is to the southwest toward Shoal Creek. The City of
Liberty obtains its drinking water from seven municipal wells,
Water Supply Wells Number 1 through 7 (WSW1 through WSW7) ,
drawing from the alluvial aquifer underlying the entire area.
The municipal wells are located approximately 2,000 feet east-
southeast of the site. Municipal Water Supply Well Number 2
(WSW2) has been taken off the water supply system because of
1,1,2-trichloroethene (TCE) contamination and is being discharged
to surface waters as part of an interim response action
implemented by the City. The location of the Site in relation to
the municipal well supply field is shown on Figure 3.
SECTION 2.0
SITE HISTORY AND ENFORCEMENT ACTIVITIES
2.1
site Historv
The Lee Chemical site is located on property owned by the City of
Liberty that was utilized from about 1920 until 1962 as the
City's water treatment plant. In 1965, the City of Liberty
leased the property to the Lee Chemical Company. The Lee
Chemical Company packaged and distribut~d commercial and
industrial cleaning solvents and other chemicals. In addition,
Lee Chemical accepted for disposal chemicals from various
commercial companies. Some of these chemicals were reprocessed
onsite but many were stored onsite in 55 gallon drums. In 1975,
the City of Liberty .fiied suit against the Lee Chemical Company
for nonpayment of rent. Upon settlement of the suit, the City of
Liberty was able to retake possession of its property and gain
access to the Site.
1
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FIGURE 1
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,
LEE OiEMICAL SITE
CITY
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2.2 Removal Historv
In 1976, the U.S. Environmental Protection Agency (EPA) notified
. the City of Liberty that the chemicals stored on the property had
to be properly disposed of. Approximately three hundred 55
gallon drums of wastes were removed from the abandoned site and
properly disposed of in July 1977. In 1979, low levels of TCE
were detected in the raw water from the 'city of Liberty's public
water supply wells.' .
In the years following 1979, groundwater and soil samples
collected by the EPA and the Missouri Department of Natural
Resources (MDNR) were found to be contaminated. MDNR inspected
the site in September 1982, and found deteriorated drums and
chemical containers plus an empty 55-gallon drum labeled
1, 1, 1-trichloroethane. Subsequently the City of Liberty and MDNR
identified the abandoned Site as a source of TCE contamination in
the City's water supply wells. In April 1983, the old water
plant building on the site was demolished and only its foundation
and adjacent concrete storage tank remain. Hazardous materials
found in the structure were disposed of offsite. Clean soil was
used to restore the surface of the site.
In May 1983, MDNR recommended that the City of Liberty implement
specific actions to reduce the TCE levels in the drinking water
supply. In January 1984, the City of Liberty began discharging
water from a municipal water supply well, WSW2, to the Missouri
River through an abandoned sewer line. In July 1984, the City
began discharging water from an onsite abandoned municipal supply
well, EW-3, and the water from WSW2 to Town Branch of Shoal Creek
through a segment of abandoned water line. Both of these actions
were taken to contain the plume of groundwater contamination and
reduce the levels of TCE in the water supply. This discharge was
authorized by a National Pollutant Discharge Elimination System
(NPDES) permit issued by MDNR on August 3, 1984.
Monitoring' of the TCE levels in the city of Liberty's water
supply wells indicated that contamination was present in all
wells as late as June 1986. Levels in WSW1, WSW4, WSW5, and
were approximately 5 parts per billion (ppb) while levels in
and WSW3 were as high as 330 ppb and 75 ppb, respectively.
WSW6
WSW2
Since March 1987, the concentration of TCE in the finished supply
water has been at or below the drinking water standard of 5 ppb.
By June 1987, levels of TCE had decreased to below detection
limits in WSW1, WSW4, WSW5, and WSW6; to 3 ppb in WSW3; and 97
ppb in WSW2. Since 1987, only WSW2 and WSW3 have shown
detectable levels of TCE. In early 1988, a new, uncontaminated
well, WSW7, was placed in service to compensate for the loss of
WSW2 as a source of drinking water. Currently, no detectable
levels of TCE are found in wells connected to the City of
Liberty's water supply system.
5
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From 1989 to 1990, the City of Liberty conducted Remedial Inves-
tigation and Feasibility study (RIjFS) activities to identify the
types, quantities, and locations of contaminants. The RI identi-
fied the following:
- TCE contamination is present in the soil at depths ranging
from 1 to 20 feet below ground level, the highest
concentration was 11,000 micrograms per kilogram (ugjkg) at
a depth of 20 feet, east of the old water plant building
foundation;
-
- A plume of TCE contamination suspended in and moving with
groundwater in the aquifer underlying the Site;
- TCE contamination in the now out-of-production WSW2 and
abandoned onsite well EW-3; and
- No present contamination in WSW1, WSW3, WSW4, WSW5,
WSW6, and WSW?
currently, the City of Liberty is continuing the implementation
of the interim response action of discharging WSW2 and EW-3 to
Town Branch Creek and the remaining municipal wells (WSW1, WSW3,
W?W4, WSW5, WSW6, and WSW?) do not show detectable levels of TCE.
However, should the interim response action cease, it is
estimated that the plume of contamination in the alluvial aquifer
will reach the remaining municipal wells in a relatively short
period of time.
2.3
Enforcement History
The City of Liberty was initially notified by MDNR on August 26,
1983 of its intent to propose the Lee Chemical Site for inclusion
on the Reqistry of Confirmed Abandoned or Un=ontrolled Hazardous
Waste Disposal Sites in Missouri. On January 1, 1984, the
property was place, on the Reqistry pursuant to Section 260.440,
RSMo. The EPA added this site to the National Priorities List
(NPL) on May 20, 1986. On August 5, 1988, the State of Missouri
and the City of Li~erty entered into an Agreement which provided
for the City to c 'uct an RIjFS. This agreement was
subsequently modi~~ed on October 20, 1989, and the City completed
the RIjFS in August 1990.
In May 1988, EPA and the City' of' Liberty entered into an
administrative consent order which required the City to continue
the interim response action described in the previous section.
SECTION 3.0
HIGHLIGHTS OF COMMUNITY PARTICIPATION
The RIjFS and Proposed Plan for the Lee Chemical site were
released to the public on December 24, 1990. These two documents
were included in the administrative record file maintained at the
MDNR, in Jefferson City, Missouri, the EPA Region VII Docket
Room, in Kansas City, Kansas, and the Mid-Continent Library in
6
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the City of Liberty, Missouri. The notice of availability for
these two documents was published in the KANSAS CITY STAR on
December 24 and 31, 1990 and the LIBERTY TRIBUNE on January 2 and
9, 1991. A public comment period was held from December 24, 1990
through January 23, 1991. In addition, a public hearing was held
on January 9, 1991. At this meeting, representatives from the
MDNR and EPA answered questions about problems at the Site and
the remedial alternatives under consideration. A response to the
comments received during this period is included in the
Responsiveness Summary, which is part of this Record of Decision.
This decision document presents the selected remedial action for
the Lee Chemical Site, in Liberty, Missouri, 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) and, to the
extent practicable, the National oil and Hazardous Substances
Pollution Contingency Plan of 1990 (NCP). The decision for this
Site is based on the Administrative Record.
SECTION 4.0
SCOPE OF RESPONSE ACTION
The selected remedial actions represent the final remedy for the
site. The principal threat at the site is the highly mobile
Volatile organic Compounds (VOC) contamination that moves from
the source of contamination in the site soils to the groundwater
and the mobile VOCs within the groundwater migrating toward the
city of Liberty's water supply. To address potential risks from
such exposure, the following remedial objectives were identified:
* Prevent potential exposure to contaminated groundwater;
* Protect uncontaminated groundwater for future use by
preventing further migration of the contaminated groundwater
plume;
* Restore the contaminated aquifer for future use as a
drinking water source by reducing the contaminant
concentrations to regulated or health based levels (for
example 5 ppb or less for TCE); and
* Remediate contaminated soils onsite such that no further
groundwater contamination can occur.
SECTION 5.0
SUMMARY OF SITE CHARACTERISTICS
As a result of prior removal actions at the Site, all drums and
containers have been removed and the buildings have been
demolished. Clean soil was used to restore the Site surface and
the Site is fenced.
A groundwater extraction system to confine the spread of the
plume of contaminants and protect the remaining City supply wells
has been in operation since 1984. The extracted water is
currently being discharged under an NPDES permit through an
7
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abandoned water main to Town Branch of Shoal Creek. TCE
concentrations had been as high as 330 ppb and 851 ppb in WSW2
and EW-3, respectively; and all of the rest of the city wells
have shown TCE concentrations, but at lower levels.
As a result of this interim response action, the levels of TCE
have dropped below detection limits in all of the City's supply
wells and the concentrations of TCE in the extraction wells has
dropped to 45.30 ppb in WSW2 and 116.3 ppb in EW-3, in 1990.
The remedial investigation (RI) field work, conducted by the City
of Liberty under MDNR oversight from early 1989 to mid 1990,
included activities to define the bedrock surface, groundwater
flow regime, potential groundwater contaminant migration
pathways, and the extent of soil and groundwater contamination.
The discovery of containers, barrels, and visible contamination
in and around the Lee Chemical site was the initial indication of
potential contamination. Further investigation in the immediate
area provided additional information to delineate the source of
contamination. The predominant data that confirms that the Lee
Chemical site and immediate surrounding area as the source of
contamination is the analytical results from soil and soil gas
samples collected around the site. Groundwater sampling
conducted at monitoring wells installed during the RI, at EW-3,
and at Liberty supply wells also provides evidence that the Lee
Chemical Site area is the origination of contamination. Greater
detail as to the extent of contamination in the soil and
groundwater is provided below.
Soil contamination was found at the highest levels immediately
adjacent to the demolished water plant building foundation, with
decreasing levels away from the foundation. Soil contamination
extends from approximately 1 foot below ground level to the water
table (approximately 20 feet). The shallow depths of
contamination detected indicates that surface disposal or
spillage of contaminants occurred. TCE,. the most common
constituent, was reported at consistently greater values than
other volatile organic compounds (VOCs).
The highest subsurface soil TCE concentration, 11,000 micrograms
per kilogram (ug/kg)" was found 20 feet below ground level in the
area east of the demolished water plant building foundation.
soil gas data obtained during the RI generally corresponds to the
areal extent of soil contamination detected which is summarized
as follows:
soil contamination is present in samples collected in the
immediate area of the Lee Chemical Site at depths from
1 to 20 feet.
Soil contamination at shallow depths (1 to 10 feet below
ground level) is greatest surrounding the demolished building
foundation with levels decreasing away from the foundation.
8
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Soil contamination at depths up to 20 feet below ground level
are greatest around the demolished building foundation and
just east of that location with decreasinq levels further
east.
Groundwater samples and corresponding analytical data obtained
from monitoring wells, extraction well EW-3 located on the Lee
Chemical Site, and Liberty supply wells were evaluated to
determine the source and extent of contamination.
Groundwater contamination is currently restricted to the area
immediately surrounding the Lee Chemical Site with a pathway
extending east to Liberty supply well WSW2. Sampling conducted
at the monitoring wells located south of the adjacent Norfolk and
Western railroad showed no contamination above detection limits
following the initiation of the interim response action.
When the analytical data were evaluated in conjunction with the
hydrogeologic data, the following conclusions. were drawn:
Pumping of EW-3 is controlling the migration of groundwater
contamination at the identified source.
Pumping of WSW2 has effectively decreased the contamination
originally present in the other Liberty supply wells.
5.1 TODOqraDhv and Drainaqe
The City of Liberty's municipal well field is located in extreme
south central Clay County, Missouri. Physiographically, it lies
in the flood plain of the Missouri River. The uplands, north of
the area, consist of highly dissected glacial fill plains covered
by loess of varying thicknesses. The flood plain includes
extensive coarse grained outwash materials. The general slope of
the area is to the southwest toward Shoal Creek. There are
meander scars locally that include oxbow lakes or depressions
that collect local runoff. Shoal Creek traverses the flood plain
through an oxbow meander of the Missouri River, discharging into
the Missouri River approximately 1.5 miles south of the well
field.
5.2 Geoloqy
The geology consists of Pennsylvanian aged bedrock strata
overlain by unconformed Pleistocene and Recent unconsolidated
alluvial deposits. The topographic relief of the outcropping
bedrock upland area can be as high as 200 feet. The topographic
relief of the flood plain is approximately 30 feet. The site
lies entirely on the Missouri River flood plain. Portions of
upland area are covered by various thicknesses of loess and
glacial drift. Boulder zones have been encountered at the base
of the valley fill that are believed to be glacially derived and
may be Pleistocene in age.
9
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The bedrock formations that outcrop and subcrop in the vicinity
of the site are, in ascending order, the Pleasanton Group and
Kansas City Group. Except for possible minor local structural
features, the formations dip gently to the west. The Kansas City
and Pleasanton Groups are composed of interbedded layers of
limestone, sandstone and shale. The unconformed surface that
separates the bedrock from the alluvium dips sharply to the east
from the Lee Chemical Site to the well field.
,
The Missouri River Valley is a partially filled trough incised
into the bedrock formations. The grain size generally becomes
finer upward through the sequence. The thickness of the alluvium
is controlled by irregularities in the bedrock surface. Regional
studies indicate that the maximum thickness encountered east of
Kansas City is 143 feet. The average thickness is approximately
85 feet. The alluvium in the site area .is composed of fine to
coarse sand, gravel, silt and clay. The distribution of these
sediment types generally conforms to a three-fold classification
system. The "boulder zone" is composed of coarse gravel and
rocks and lies at the base of the alluvium. The "bottom stratum"
is composed of gravel and sand and lies at intermediate depths.
The "top stratum" is composed of fine sand, silt and clay and is
at shallow depths.
5.3 soils and Surface Water Hydroloav
Surface soil in the area consists primarily of the Haynie,
Mondale, and Gillam silt loams. These soils are moderately well
drained, moderately permeable soils. They formed in calcareous,
silty, or loamy alluvium. Slopes range from 0 to 2 percent.
They have a Unified Soil Classification of CL-ML, CL, and a clay
content of 15 to 35 percent~ permeabilitY3ranges from 0.6 to 2.0
inches per hour (4.23 X 10- to 1.41 X 10- centimeters per
second). The loess is thickest on the highly dissected hills
close to the flood plain. It gradually thins to the northeast,
where the ridge-tops are loess covered and glacial till is on the
side slopes.
Surficial water within the site area flows to the south and
empties into Shoal Creek as evidenced by the local topography.
The ground elevation at the Site area is approximately 730 feet
above sea level while the approximate elevation of Shoal Creek in
the vicinity of the .Site is 720 feet. Town Branch empties into
Shoal Creek on the western edge of the area.
5.4 Hydroaeoloav
The principle aquifer in the area is the Missouri River alluvium.
The regional flow of the aquifer within the Site area is to the
east. The groundwater flow in the site area is heavily
influenced by the pumping of the City of Liberty's water supply
well field. The depth of groundwater in the Site area is
approximately twenty feet.
10
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Hydraulic conductivity.of the .aquifer material has bee~ estimated
to range from 2,000 to 5,000 gallons per day per square foot.
This is based on constant head permeameter tests from samples of
the aquifer material. Estimates of the aquifer transmissivity
ba~ed on pumping test data range from 95,000 to 250,000 gallons
per day per foot. The values are typical for alluvial aquifers.
The storage coefficient (specific yield) of the aquifer is
estimated to range from 0.10 to 0.20 for the sediments
encountered. .
Yields from wells completed in the Missouri River Alluvium have
been reported to be as high as 1,250 gallons per minute. Yields
from the City of Liberty's wells range approximately 500 to 1,000
gallons per minute when pumping at full capacity. Specific
capacity of these wells average approximately 110 gallons per
minute per foot.
Recharge to the alluvial aquifer comes primarily from
infiltration of rainfall and, to a lesser extent, from the
bedrock. Discharge from the aquifer can be attributed to seepage
into the Missouri River, pumping wells, and evaportranspiration.
Pumping wells may cause infiltration of water from the river to
the aquifer by reversing the hydr~ulic gradient.
SECTION 6.0
SUMMARY OF SITE RISKS
As part of the RI/FS process, a risk evaluation was conducted to
estimate the human health and environmental risks associated with
possible exposures to contaminants detected at the Lee Chemical
site. Both carcinogenic and noncarcinogenic adverse health
effects were analyzed using a reasonable maximum exposure
estimate. This risk analysis shows that an unacceptable excess
cancer risk for a reasonably maximum exposed (RME) individual
would result if the City of Liberty discontinued the current
interim response action to control the plume of contamination
coming from the Site and returned the wells currently pumping as
part of this action to use as supply wells for the community.
The noncarcinogenic risks analyzed were below levels of concern.
The risk evaluation also analyzed the p~tential short-term
adverse health effects associated with air emissions from the
discharge of contaminated groundwater. This discharge is part of
an interim response action which began in 1984 to remove
contaminated groundwater from the aquifer and to capture the
plume of groundwater contamination thus protecting the City of
Liberty's remaining water supply wells. The interim action,
described as Alternative II, utilizes WSW2 and EW-3 as extraction
wells and discharges the extracted water through an old water
main to Town Branch Creek. As a result of this action,
contaminants are no longer detected in the remaining City supply
'wells. This part of the risk analysis assumed a worst case
exposure and found that the risks from the air emissions at the
outfall were insignificant.
11
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The excess lifetime carcinogenic r~sk level is expressed in
scientific nota~ion, e.g., 1 X 10-. An excess. lifetime cancer
risk of 1 X 10- indicates that as a plausible upper bound the
risk of developing cancer as a result of site related exposure to
a carcinogen over a 70-year lifetime under specific exposure
conditions at a site is approxima~elY one in ine million.
CUmulative risk levels of 1 X 10- to 1 X 10- can be used to
determine the environmental significance of the risk incurred and
is a target range fOi remedial actions. A cumulative risk
greater than 1 ~ 10- is confidered to be unacceptable. Risks
between 1 X 10- and 1 X 10- are consideied to be potentially
unacceptable, and risks less than 1 X 10- are considered to be
insignificant.
Noncarcinogenic effects were analyzed using hazard indices and
hazard quotients. The hazard index is the comparison of
estimated exposure (chronic dose) with reference doses (i.e.
acceptable daily intake). The hazard quotient is the sum of the
hazard indexes for a specific pathway. If the hazard index is
less than one for an exposure pathway, no adverse health effects
would be expected. .
The contaminated media considered in the risk evaluation were
soil and groundwater onsite and groundwater offsite. Soil
sampling data in the ~I indicates that no quantifiable
concentrations of hazardous substances exist in the near surface
(0 to 1 foot) site soils. However, deeper (5 to 20 feet) soil
samples did contain concentrations of contaminants which could
lead to potential exposures during construction activities at
those depths. Both the depth to significant levels of soil
contamination and the Site fencing limit public access to
contaminated soil. As a result, this pathway of exposure was not
included in the calculation of the overall site risks. However,
the migration of contaminants from the deeper soils to the
groundwater is expected to be a continuing source of groundwater
contamination.
The principal threat at the site is the highly mobile VOC
contamination that moves from the source of contamination in the
Site soils to the groundwater and the mobile VOCs within the
groundwater migrating toward the City of Liberty's water supply.
Before the interim response action was taken, samples from all of
the existing Water Supply Wells (WSW numbers 1 through 6) showed
1,1,2-trichloroethena (TCE) cont~mination~ Samples from WSW2 .
contained concentrations as high as 330 parts per billion (ppb),
and sampling of an abandoned City supply well (EW-3) on the Lee
Chemical Site showed concentrations of TCE as high as 851 'ppb.
A review of the data in the RI lead to the identification of five
indicator chemicals to be considered in the risk evaluation.
12
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The five contaminants of concern are as follows:
a)
b)
c)
d)
e)
1,1,2-trichloroethene (TCE),
l,l-dichloroethane,
l,l-dichloroethene,
trans-l,2-dichloroethene, and
l,l,l-trichloroethane (TCA).
TCE was the indicator chemical detected most frequently and in
the highest concentrations. TCE is a probable human carcinogen,
and two other indicator chemicals (l,l-dichloroethane and
l,l-dichloroethene) are potential human carcinogens. All of the
indicator chemicals are capable of causing acute and chronic
noncarcinogenic health effects in humans. Vinyl chloride has not
been detected in any of the samples taken at the site.
Concern over the potential impacts of hazardous substances
released from the Lee Chemical site focuses on the residential
populations served by the City of Liberty's water system. The
City of Liberty's water system serves 6,280 households or places
of business, which is approximately 20,000 people. The exposure
pathways considered in the risk evaluation were ingestion and
inhalation of VOCs from contaminated groundwater. Table.l
summarizes the exposure pathways and exposed populations used in
the risk calculations, and Table 2 summarizes the exposure
parameter values. .
Another exposure scenario considered in the risk evaluation is
related to VOC emissions from the interim pump and discharge
action which is ongoing at the site. The selected alternative
uses this same discharge method. Potential risk to industrial
workers and residential populations near the discharge point on
Town Branch were evaluated. Risks, based on air modeling,
associated with the extraction well discharge point on Town
Branch were found to be insignificant.
Exposure due to direct contact with or ingestion of contaminantE
from site soils were not considered in the risk evaluation, .
because the lack of contaminants in shallow site soils and the
Site fencing combined to make the likelihood of these routes of
exposure remote. Exposures from the ingestion of surface water
from Town Branch or Shoal Creek were also very unlikely and not
included in the computation of site risks due to the limited
access the public has to these creeks, their low flow rates, and
the low concentrations of contaminants that enter these streams.
The carcinogenic risk based on a reasonable maximum exposure
(RME) associated with the use of contaminated groundwater from
the Lee Chemical Site as a source of drinking water for the City
of Liberty is 2 X 10-4. This estimate combines the exposures
from ingestion and inhalation of site contaminants and indicates
that as a probable upper bound there would be two additional
cancers in a population of 10,000. Therefore, the carcinogenic
risk from this exposure scenario is unacceptable pursuant to the
risk levels identified in the NCP. The carcinogenic risk
13
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TABU! 1
,
SUMMARY OP EXPOSURI! PATHWAYS AND P.XPOSI!D POPULA110NS
, .
, .
EVALUAmD IN THE RISK eVALUA110N OP'I'HB LEI! amMICAL srm
...
I!XI'OSUItB N8DIUN I!XI'05UIIJ lOINI' IIX'I'OSURI! Itoum fCJ'IDrI1AIJ. Y mttu:.t!D mMMl!Hn
OnNlldwller Lee aemkal Sill '"&atlon 1t,.Ide"tI.t. Chlldml.1I4I AanIIII. .... .... a, 0I1Jbe,., ...
WeD Area Idull. vain. potable ",'er "'''D . ....., wen .1 .tIe ...i, III .tIe .rea
luppllcd 'rom well EW.'. . of conce... or win ........ 8M 01 we.
EW-' II . .1IpIIIJ wen. For,.fPC*I 01
'he .... __III ""I .Ie. IlIdudes weill
EW.1. 1-8J, 2-81. ).81. -.-8]. MW.2-86.
MW-3-a ew.1a8., dIb 10 ...111 0tIIJ.
OnNlldwl.er Lee OeIftkal She l"hala'lon lteslde"tI.1: Chlldml.1Id A8nIIIfna .... die a, eI ..",will
wen Area Idulll beinl elpolCct '0 _.n . ....., we. .. .tIe lIIe, .. .he .1'18
.... ~,ne. while Ihowe"n. of conce... or win ........ lie of we'
J:o- wllh ",'er '101ft well EW-1 EW.) II . ..,.,., wen. For,.".... eI
'he rIat IIICIImCIII this .rea Indllctel weill
EW.1. 1-8], 2-81. )-8], 4.." NW.2-86.
MW.].86. 1!v81881" risks to ""11 on".
OnNlldwller . 1Ae,., Wel '2 '"&atlotl lte.IdeIlII'I: Chlldlell.nd AD""'" .... die 0, elLh,., ..
ldul" ulill' _Ier IVpptiect .....n 8 ....., we' It tile aile Ie tile 8Ie8
'101ft Well ,,2. of conce.. or will ..... - cI Wet '2
. 8 ....,., -I. lMI...ee dIb 10 ......
on".
OnNlldwller lh,., wen '2 '"hal..1a8 Itnlde,,'I.t. ChDctIe8"" ~ .... ... CItJ 01"""'''
8dulll bein. elpolCct '0 .....n 8 ......, -. It 1M alt. Ie the IIta
I, wI"I'" while .howertlll of COIIt'8n1 or wi' ...... - 01 Wel '2
...h _Ier 'l'OIII Well ,2. . 8 ..."., --. hi........ to _I"
on".
58rf'," W..er TII8a .... '"halallon lteslde,,"It: ChIMIe8.nd....... AttJJI"1II .... ... ....... --...-
Contlllll_ect '" Dladl8rp 'ohl. lellctinl II the """. . -lehouu II .... .... . 1M 08td00r IewL
O-IIctW8I.r D.....,. 'trill', ctowIIwI8d of ,... ..,...1a8 e..l8le8 ..... 10 ...... 08".
weill ctisdllrp: potnt.
58rf'," WI'" TOWII Unadl '"hala'lon 'nd8S,rfll/Q,mmem.t. A8I8MIaI"" the .... .--ntIoe
Con"IIIillllect ., Disdllrp: '01.., WOlken II bUlille.. dowftwInd II the .... . .... 08td00r IeftL
Ol'08nctw1ler DlKhlrae of.he e.,...ion wen
dlsdulrac poIlI',
.
-------
TAntn
2
SUMMARY or PARAMIJI1!A VALlmS USI!IJ TO I!SI1MAm I!XI'OSUIUl
VAIUAIIUl VAI.t.m USI!D
0IanIca1 CanmllnU. Pleue ..Ier 10 Table. 2.110 2.2
I!apan.. P,...., ("flur)
Raldentl" 3M
Ind1IItriel/ContIMIdeI Jro
. e.pa.... o.nllOll (Jar)
Raldentl8l (AwnF I!apahte) 9
Raldentl" (RNe) (a) ]I)
Indullriel/Contmetdll 40
ConI.. It8te
Ol'OlltMtwller IftFlllOIIlll.,) 2
'""" Air Inhalltion Rale (m /0,)
U1 Raidentlll 2fI
Industrill/CDmmeldel U
IJocfr Wef&fd Cil) 70
Awnaln.111M (yelr)
for Catdqenic Meetl
Reliclentilll/lnd.ariel/CDmIM1de1 . 10
for Non_mqenic I!rreetl
RaIde"tlll (AwnFe.po....) ,
Reliclentilll (RNe) ]I)
Industriel/ComlMrdaI .eo
TIllIe eo..e... P..or 'or Awnalna1'ltM
CdaJ'rear) 3M
nlUl!P 1U\110NAI.ft
Dan, (by mawllilon)
AIIumlna S wort ..,./.... tar n ..blJeat
Nltlonal median Ihne (SOtIt petfttlt.) .. GIll ...we.. (b)
Nltlonal "fIPCr-bouncl, II.. (9Ot1t pelftllille)
Upper-b08nd .orten elpOl." d...11on .., ., ACOIM/OSHA
AII.II, 90Ih percalile (bL
Allull, Iftn. ~) .
AuumlnlU m ""'or I '-",,.,
Alluh, IftnF (b) PRC'" tttII """18 ..... 10 cMIhu.
Urelhne (by maw..I"')
NatloullMdla.. II.... (SOtIt percat.) .. 8M ......... (b)
Nltlonal "fIPCr-bCMlncl I'" (90th perce...lIe)
Upper-:bounll .orten' elpCll." dunl'" ... ".AC'OIM/OSHA
Dan,
..
CI'
C'o'
... . ....................
u.s. UA C""). ....... r-......... UA .,...,..1. 1-
,
-------
calculations for the ingestion and inhalation of VOCs from
contaminated groundwater are summarized in Tabl~s 3 and 4. The
basic toxicity information used in these calculations is listed
in Table 5. This risk level represents the baseline risk which
would r2main if no action was ~aken at the Site. The value of
2 X 10- is based on the data in the RI which was collected after
the interim action was taken at the site. The risk level would
be approximately an order of magnitude higher if data from before
the interim action was used 'in the risk calculations.
Groundwater from the Lee Chemical site is not currently used to '
supply drinking water, to the City. Under current Site
conditions, with the interim response action operating, no
detectable levels of contaminants were found in samples taken
from the Liberty supply wells, and risks associated with the
extraction well discharge point on Town Branch are insignificant.
The noncarcinogenic risks associated with all of the indicator
chemicals in all the exposure scenarios considered do not
represent any significant concern for adverse health effects.
The noncarcinogenic risk calculations are also summarized in
Tables 3 and 4 and the basic toxicity information used in the
calculations is listed in Table 6. .
Cleanup goals for the groundwater will be based on Applicable or
Relevant and Appropriate Requirements (ARARs), in particular,
state and federal drinking water standards and state water
quality standards for groundwater (Table 7).
No rare, threatened, or endangered wildlife species were
identified in the vicinity of the site during the RI. There have
been no samples taken of sediments or organisms from Town Branch
or Shoal Creek to assess the environmental impact of the
discharge. There have been in-stream water quality samples
collected at the confluence of Town Branch and Shoal Creek, but
none of these samples has shown significant concentrations of
VOCs. The concentration of TCE entering Town Branch at the
outfall has consistently been below 90 ppb since the beginning of
the RI. Based on that data, it would appear that almost complete
volatilization of the TCE occurs between the point of discharge
and the confluence. However, further investigation of the need
to sample the creek sediments and organisms will be considered as
part of the design of the remedial action.
Actual or threatened releases of hazardous substances'from
Site, if not addressed by the preferred alternative or one
other alternatives besides Alternative I (the no-action
alternative), may present an imminent and substantial
endangerment to public health, welfare, or the environment.
the
of the
16
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ILII ClEIlICAL "1' YlLL' CfU'URII
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!'ABLB 7
NUMERICAL VALUES FOR CONTAMINANT-SPECIFIC ARARS
FOR THE LEE CHEKICAL SITE' .
. SAFE DRINKING WA'l'ER AC'l'
IICL MCLG
CONTAMINANT ug/l ug/l'
1,1-Dichloroethane -- --
1,1-Dichloroethene 7 7
t-l,2-Dichloroethene 100 100
1, 1, 1-Trichloroethane 200 200
(TCA)
1,1,2-Trichloroethene 5 0
(TCE)
EPA 304(a) WATER QU~TY CRITERIA
Acute
ug/l
Chronic
ug/l
10-6 Risk for
Carcinogens from
Consumption of: .
Water', Organisms
Organisms Only
ug/l ug/l
CONTAMINANT
Freshwater
Criterion
Concentrations
1,l-Dichloroethane
1,1-Dichloroethene
--
--
0.057
3.2
t-1,2-Dichloroethene
1,1,1-Trichloroethane
(TCA) .
--
3094
173077
1,1,2-Trichloroethene
(TCE)
2.7
80.7
21
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SECTION 7.0
DESCRIPTION Q[ ALTERNATIVES
Alternative I:
Alternative I is a no action alternative. required by the National
Contingency Plan (NCP) and SARA. It is the baseline against
which the effectiveness of other alternatives are judged. Under
this alternative, monitoring, control, or remediation of
contamination will not take 'place. Site perimeter fencing is
required and is already in place. Groundwater contamination will
spread throughout the area making new water wells at a distant
location a requirement for the City of Liberty's water supply.
Currently uncontaminated supply wells will, in time, become
contaminated at levels above Maximum Contaminant Levels (MCLs).
Alternative II:
The remediation that has been taking place at the Lee Chemical
Site and the Liberty well field is pumping EW-3 and WSW2 to Town
Branch Creek. Under this alternative, the site perimeter needs
to be fenced and it is already in place. .The City of Liberty
will need to restrict any new well construction in close
proximity to the Lee Chemical Site. If this alternative is
chosen, groundwater monitoring will be required. Air and surface
water monitoring at the Town Branch outfall is also a requirement
to meet the ARARs.
Groundwater quality data from the RI showed that between 1982 and
1989, TCE concentration generally decreased at WSW2 from 330 ppb
to approximately 65 ppb with a temporary low of 20 ppb. EW-3
also showed a declining trend of TCE between 1984 and 1989. The
TCE concentration in 1984 was over 851 ppb and reduced to
81.6 ppb in 1989.
The level of groundwater contamination suggests that both of
these wells will continue to produce groundwater above the MCL
for TCE and other constituents for an extended period of time.
Although the decline of contamination is fairly slow, the
contaminant plume within the aquifer is contained within
approximate limits described in Section 1. All other supply
wells in the Liberty well field are producing groundwater below
MCL levels. This alternative is estimated to require 25 years
for site restoration at a present worth cost of $814,000.
Alternative III:
Alternative III follows all basic requirements of Alternative II.
In this alternative, well EW-3 will be replaced by a high
capacity well, a more efficient well penetrating the full
saturated thickness of the aquifer and located near the center of
the contamination source. By constructing an extraction well to
Missouri public water supply standards, the following goals will
be achieved:
22
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a) Radius of influence within the Lee Chemical site will be
further increased so that the entire contaminant plume can be
captured and limited to the site boundaries.
b) Water withdrawal from all depth levels will enhance clean
up of the aquifer.
c) Groundwater produced by Liberty well No.2 will decrease
below MCL levels and .all'other wells in the Liberty well field
will remain free of contamination.
Liberty well No.2 will be pumped continuously until the MCL
concentration of 5 ppb of TCE and 200 ppb of TCA is reached at
this location.
In this alternative, the transport of contaminants through soil
will be inducted by local precipitation. Although the
contaminant plume will be contained within the radius of
influence of this high capacity well, an extended period of time
will be required to meet groundwater health based standards
within the aquifer at the Lee Chemical Site.
Groundwater monitoring will be required for monitoring wells at
or in the vicinity of the Lee Chemical site. More stringent
monitoring programs .for air and water samples will be required at
Town Branch outfall. locations. This alternative is estimated to
require 25 years for site restoration at a present worth cost of
$767,000.
Alternative IV:
Alternative IV is the addition of a soil flushing system to
Alternative II. All monitoring requirements explained in
Alternatives II and III will be applicable to this alternative.
Fencing the perimeter of the site.is a requirement and is already
fulfilled.
The soil flushing system will cover an area of approximately 800
feet in length (east to west) and 200 feet in width (north to
south). Two foot wide trenches dug to a depth of approximately 3
feet below ground level will be constructed at approximately 10
foot centers throughout the area described above. At the bottom
of the trenches, flexible perforated tUbing will be emplaced and
the excavation will be backfilled with permeable material. The
system will be connected to a clean water supply from the Liberty
well field.
The RI identified the vadose zone, the soils above the water
table, within the Lee Chemical Site area as the principal source
of contamination. This alternative will enhance the flushing of
contaminants through the vadose zone, thereby reducing the level
of contamination at the source. Contamination flushed from the
vadose zone and escaping the influence of EW-3 will travel to
Liberty well No.2.
23
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A relatively extended period of time will be required to bring
groundwater within the Lee Chemical Site within acceptaple
levels. .
Withdrawal from Liberty well No.2 will continue to contain the
contaminated groundwater plume offsite. This alternative is
estimated to require 15 years for site restoration at a present
worth cost of $860,000.
Alternative V:
This alternative is a combination of gravity induced soil
flushing and Alternative III. The alternative will follow all
monitoring requirements and restrictions as explained in
Alternative IV. Due to the elimination of limiting conditions
stated in Alternative IV, the cleanup of the Lee Chemical Site
contamination will be expedited. The extraction well constructed
to Missouri public water supply standards will be strategically
located at the center of the zone of contamination so the radius
of influence of the well will extend fully over the contaminated
area. Full control will be exerted by the new extraction well so
that the City of Liberty well field will be protected. After the
new extraction well is operational, the contaminant level at WSW2
w~ll decline to below MCLs and can be retired from the extraction
operation and return to its normal water supply status.
The groundwater aquifer is expected to meet MCL water quality
standard within five (5) years after initiating this process at a
present worth cost of $550,000.
Alternative VI:
This alternative is the addition of bioremediation to Alternative
IV once the residual concentration level of Alternative IV is
reached. Bioremediation is the enhancement of the activity of
naturally occurring microorganisms. The introduction of proper
nutrients to the system will increase their consumption of
contaminants and will allow an increased population growth of
microorganisms. Bioremediation will be implemented using the
same infrastructure of Alternative IV. This alternative is
estimated to require 15 years for site restoration at a present
worth cost of $950,000.
Alternative VII:
This alternative is the addition of bioremediation to Alternative
V once the residual concentration level of Alternative V is
reached. Bioremediation will be implemented using the same
infrastructure of Alternative V. This alternative is estimated
to require 5 years for site restoration at a present worth cost
of $640,000.
24
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7.1 Applicable or Relevant and ADDropriate ReQUirements lARARs)
The selected remedy will comply with all federal and state
applicable or relevant and appropriate requirements (ARARs).
Applicable requirements are those state or federal requirements
legally applicable to the release or remedial action contemplated
that specifically address a hazardous substance, pollutant,
contaminant, remedial action, location or other circumstance
found at the Site. If it is determined that a requirement is not
applicable, it may still be relevant and appropriate to the
circumstances of the release. Requirements are relevant and
appropriate if they address problems or situations sufficiently
similar to the circumstances of the release or remedial action
contemplated and are well-suited to the site.
Numerical values for the chemical-specific ARARs identified for
the Site are listed .in.Table 7. No federal or state location-
specific ARARs were identified for the Site. The major chemical-
specific and action-specific ARARs for the Lee Chemical Site are
listed below:
Chemical-specific ARARs
Federal Maximum Contaminant Levels for volatile organics in
drinking water supplies (40 CFR Part 141).
- Establishes health-based standards, maximum contaminant
levels (MCLs), for public water systems.
- MCLs for organic contaminants are applicable to
groundwater.
State Maximum Volatile Organic Chemical contaminant Levels for
public water systems (10 CSR 60-4.100).
- Establishes maximum chemical cQntaminant levels for
volatile organic chemicals in public water systems.
- Maximum contaminant levels may be applicable to
groundwater at the Site.
Federal Water Quality Criteria (40 CFR Part 131) Quality
Criteria for water.
- Establishes criteria for water quality based on
toxicity to aquatic organisms and human health.
- Ambient water quality criteria may be relevant
and appropriate for the discharge to Town Branch.
State Water Quality Standards for volatile organics in
groundwater (10 CSR 20-7.031).
- Establishes maximum contaminant levels and monitoring
requirements.
- Requirements may be applicable if more stringent than
federal requirements.
25
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Action-specific ARARs
National Primary and Secondary Ambient Air Quality Standards
(40 CFR Part 50).
- Establishes primary (health based) and secondary
(welfare based) standards for air quality.
- Standards may be relevant and appropriate to emissions
from discharge to Town Branch.
National Pollution Discharge Elimination System (NPDES)
(40 CFR Part 125)
- Requires permits for the discharge of pollutants
into the waters of the united States.
- NPDES permit is in effect for qischarge to
Town Branch.
State Air Quality DeMinimis Emission Levels 10 CSR
6.060(7) (A).
- Establishes requirements for new source emission
permits.
- Requirements may be relevant and appropriate to
emissions fr~m discharge to Town Branch.
State Water Quality Standards for Aquatic Life Protection
(10 CSR 20-7.031).
- Promulgates standards and rules to protect the quality
of lakes and streams.
- Standards and rules may be relevant and appropriate to
the discharge to Town Branch.
SECTION 8.0
SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES
Alternatives were developed to respond to the groundwater
contamination in the aquifer. The alternatives described in the
preceding :ection were evaluated using evaluation criteria
presented in OSWER Directive 9355.3-02, "Interim Final Guidance
on Preparing Superfund Decision Documents: The Proposed Plan,
the Record of Decision; Explanation of Significant Differences,
and the Record of-Decision Amendment, June 1989" and the National
oil and Hazardous Substances Pollution Contingency Plan (NCP), 40
C.F.R. Part 300. These criteria relate to factors mandated in
Section 121 of CERCLA/SARA and consideration of the overall
feasibility and acceptability of the remedy. The nine criteria
are as follows:
Threshold criteria
Overall Protection of Human Health and Environment
addresses whether or not a remedy provides adequate protection
and describes how risks through each pathway are eliminated,
26
-------
reduced or controlled through treatment, engineering controls,
or institutional controls:
Compliance with Applicable or Relevant and Appropriate
Requirements (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 provide grounds for invoking a waiver:
Primary Balancing criteria
Long-Term Effectiveness and Permanence refers to the
magnitude of residual risk and the ability of a remedy to
maintain reliable protection of human health ,and the
environment over time once cleanup goals have been met:
Reduction of Toxicity, MObility, or Volume through
Treatment is the anticipated performance of the treatment
technologies that may be employed in a remedy:
Short-Term Effectiveness refers to the speed with which
the remedy achieves protection, as well as the remedy's
potential to create adverse impacts ~n human health and the
environment that may result during the construction and
implementation period:
Implementability is the technical and administrative
feasibility of a 'remedy, including the availability of
materials and services needed to implement the chosen
solution:
Cost includes capital and operation and maintenance costs:
Modifying criteria
state Acceptance indicates whether, based on its review of
.the RI/FS and Proposed Plan, the State concurs with, opposes,
or has no comment on the preferred alternative:
community Acceptance which is assessed in the
Responsiveness Summary which is attached to this Record of
Decision (ROD), and which reviews the public comments received
during the public comment period.
Each alternative was evaluated against
described above to assess the relative
alternative. The comparative analysis
Tables Sa and Sb:
the specific criteria
performance of each
is summarized below and in
THRESHOLD CRITERIA'
-Overall Protection of Human Health and the Environment:
Alternative I, the no action alternative, will not be protective
of human health and the environment. The contaminant plume will
27
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migrate toward the currently uncontaminated municipal wells and
present future health risks to groundwater users. The .existing
contamination in the groundwater already exceeds state and
federal drinking water standards and state water quality
standards for groundwater.
Alternatives II, III, IV, V, VI and VII will all be equally
protective of human health and the environment by extracting the
contaminated groundwater. The contaminants will be permanently
removed from the groundwater. At the completion of the
remediation, the TCE concentration in the aquifer will be reduced
to 5 ppb or less, thereby bringing the exposure levels within an
acceptable risk range.
- ComDliance with ARARs:
Alternative I will not meet ARARs since the contaminant
concentrations will not be reduced. Alternatives II, III, IV, V,
VI and VII will meet their respective Applicable or Relevant and
Appropriate Requirements (ARARs) of federal and state
environmental laws. Specifically, they will reduce the
groundwater contamination to meet Maximum contaminant Levels for
drinking water supplies and Missouri water quality standards for
groundwater. No waiver from ARARs is required to implement any
of the active cleanup options. Since Alternative I does not meet
the threshold criteria, it will not be discussed in depth in the
following discussion of the. other selection criteria.
PRIMARY BALANCING CRITERIA
- Lonq-term Effectiveness and Permanence:
For Alternative I, the no action alternative, the plume will
continue to migrate and could eventually contaminate the rest of
the City of Liberty's water supply wells.
All other Alternatives will involve long term pump and permitted
discharge remedies requiring from 5 to 25 years to complete.
Reviews no less than every five years will be required because
the remedies will result in hazardous substances remaining onsite
above health-based levels during the remediation. At the
completion of the remediation, the groundwater in the aquifer
will be restored for future unrestricted. use by reducing the Site
contaminants to their respective ARAR levels.
All Alternatives, except Alternative I, use discharge under the
terms and conditions. of an NPDES permit as their means of
ultimate removal of the contaminated groundwater. This method is
currently being used at the site under the remediation plan now
in effect. None of the Alternatives will produce residuals such
as a sludge. stringent monitoring to insure the NPDES limits are
met will be required.
30
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- Reduction of Toxicitv. MObility. and Volume:
Alternative I will not reduce the toxicity or-mobility of the
contaminants, and the volume of contaminated groundwater will
increase as the plume migrates.
All of the other Alternatives equally reduce the mobility and
volume of the contaminants" All other Alternatives will
irreversibly reduce contaminant levels in the soil and
groundwater to levels which satisfy ARARs. Future use of onsite
and offsite groundwater from the aquifer could pose unacceptable
health risks at present contaminant levels. Dermal
contact/ingestion of onsite groundwater poses the greatest health
threat. The permitted discharge processes employed by all of the
Alternatives will reduce the inherent hazards posed by the
principal threats, at the site.
-Short-term Effectiveness:
Alternatives I and II will not increase short-term risks to the
community, environment, or workers since no construction
activities are planned.
All other Alternatives provide adequate and approximately equal
protection to the community and workers during construction and
implementation. Alternatives III, V and VII will require
construction of an onsite extraction well and Alternatives IV
through VII will require construction of an in-situ aqueous soil
washing system consisting of infiltration trenches. Any release
of VOCs during well construction or the construction of the soil
washing system will rapidly disperse and are not likely to pose a
public health risk. The Site perimeter fence and backfill
covering the Site will minimize risks to the community posed by
onsite construction of the new extraction well required for
Alternatives III, V and VII. The vegetation already covering the
Site will minimize dust emissions. Construction of the
extraction well will pose normal risks associated with the
construction of any well.
Drawdown of the aquifer, which is normal during groundwater
extraction, will not create any significant environmental impacts
from Alternatives II through VII. The increased flow in Town
Branch from all Alternatives will not create any significant
environmental impacts. -
- Implementabilitv:
Alternative I does not use any controls or technologies which
will require coordination with other agencies.
All other Alternatives will involve long term pump and permitted
discharge remedies requiring from 5 to 25 years to complete and
are approximately equal in terms of technical feasibility,
administrative feasibility, and availability of services and
31
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materials. All of the implementation time frames are based on
contaminant concentration trends as a result of the interim
response action or sound engineering jUdgment. . Alternative II is
slightly more feasible technically and administratively, since it
is currently being implemented. None of the remaining
Alternatives should .be.difficult to implement. The services and
required materials are readily available. The technologies used
in all Alternatives involve tested and widely used processes
which have proven very effective in removing VOCs from
groundwater. For all Alternatives except Alternative I, air
toxic regulations may necessitate new air permits for the
volatile organics being volatilized as a result of the NPDES
discharge. Alternative II will require the least coordination
with MDNR, EPA, and the City of Liberty since no additional
construction is planned.
Alternatives III, IV, V, VI and VII will all require additional
construction. A NPDES permit will also need to be retained for
the discharge to Town Branch. No permits will be required for
soils remediation under Alternatives IV, V, VI or VII.
Costs:
Alternative I will have $0 cost.
Alternative II will .have an estimated capital cost of $25,000, an
estimated annual operation and maintenance (O&M) cost of $56,000,
and an estimated implementation time frame of 25 years. Assuming
a 10 percent discount rate, the present worth is $814,000.
Alternative III will have an estimated capital cost of $175,000,
an estimated annual O&M cost of $42,000, and an implementation
time frame of 25 years. Assuming a 10 percent discount rate, the
present worth is $767,000.
Alternative IV will have an estimated capital cost of $175,000,
an estimated annual O&M cost of $66,000, and an estimated
implementation time frame of 15 years. Assuming a 10 percent
discount rate, the present worth is $860,000.
Alternative V will have an estimated capital cost of $325,000, an
estimated annual O&M cost of $52,000, and an estimated
implementation time frame of 5 years. Assuming a 10 percent
discount rate, the present worth is $550,000.
Alternative VI will have an estimated c~ital co~t of $265,000,
an estimated annual O&M cost of $66,000, and an estimated
implementation time frame of 15 years. Assuming a 10 percent
discount rate, the present worth is $950,000.
Alternative VII wili have an estimated capital cost of $415,000,
an estimated annual O&M cost of $52,000, and an estimated
implementation time frame of 5 years. Assuming a 10 percent
discount rate, the present worth is $640,000.
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MODIFYING CRITERIA
-
- state AcceDtance:
Representing the state of Missouri, the MDNR selected Alternative
V in the Proposed Plan as its preferred alternative. The state
is the lead agency for this Site. However, under the Superfund
law, it is the EPA which must make the decision, in consultation
with the State, on what the 'final remedy will be. MDNR has
concurred with EPA's final remedy selec~ion.
- Community Acceptance:
The reservations, concerns, and supporting or opposing comments
of the community on .the RIfFS, the Proposed Plan, and other
information in the Administrative Record were made known to the
MDNR and EPA during the thirty day comment period and the public
hearing with the community on January 9, 1991. The pUblic's
comments are addressed in the Responsiveness Summary, which is a
component of this Record of Decision for the site.
8.1 Conclusion on the ComDarative Analvsis
All Alternatives, except Alternatlve I, the no-action
Alternative, meet the threshold criteria. All of these other
Alternatives are substantially equivalent under the balancing
criteria of the long-term effectiveness and permanence, the
reduction of toxicity, mobility and volume, and the short-term
effectiveness. with respect to the balancing criteria of
implementability, all of these Alternatives are substantially
equivalent, except that the estimated implementation time frame
for Alternatives V and VII are sUbstantially shorter, estimated
at 5 years. Also, with respect to the balancing criteria of
costs, Alternatives V and VII are the two lowest cost
alternatives that also meet the threshold criteria. Alternative
V, the lowest cost alternative, which is also one of the two
alternatives with the lowest implementation time frames, is
therefore the most cost effective alternative. Additionally,
Alternative V has been accepted by the State of Missouri as its
preferred alternative and the responsiveness summary shows
community acceptance of Alternative V.
SECTION 9.0
THE SELECTED REMEDY
Based upon consideration of the requirements of CERCLA, the
detailed analysis of the alternatives, and public comments, both
the EPA and the State of Missouri have determined that
Alternative V, installation of an extraction well and an in-situ
aqueous soil washing system, discharge under the terms and
conditions of a NPDES permit to Town Branch Creek; is the most
appropriate remedy for the Lee Chemical Site in Liberty,
Missouri. This remedy is an enhancement of the ongoing interim
response action (Alternative II) at the site as described in
sections 2.2 and 5.0. In the event that additional treatment of
33
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the discharge water becomes necessary to meet either the NPDES
permit limits or other applicable or relevant a~d appropriate
requirements, a contingency phase project consisting of air
stripping or other treatment methods will be implemented to bring
the discharge into compliance.
The selected remedy will transfer the VOCs from the subsurface
soils and groundwater to surface water as well as to the air as
volatiles are off-gassed during the discharge process. Air
modeling predicts that the potential cancer risk and the hazard
index ratios of airborne VOCs from the discharge are acceptable.
However, continued ambient air monitoring will be required as a
part of this Site remediation.
The extraction system for Alternative V consists of using one
existing and one new well for the remediation. These extraction
wells, WSW2 and the .new onsite well, will be used for collection
of contaminated groundwater from the aquifer. Several other
wells, both on and offsite, are available for use as extraction
wells, should they be needed.
However, it is not anticipated that any other wells will be
needed unless the plume of contamination spreads beyond the
existing known areas of contamination. The new onsite extraction
well will be constructed in the southeast corner of the property.
The exact well design. and location will be determined during
remedial design. A well design similar to a normal water supply
well would accomplish the remedial objectives and could be
utilized as a future supply well for the City of Liberty once
remediation is complete.
The current site conditions indicate that a pumping rate of 1,000
to 1,300 gallons per minute is controlling groundwater flow and
is limiting contamination in the well field to only WSW2. The
remedial pumping rate may need to be moqified as other factors
influencing the aquifer are identified. The actual pumping rate
required will be based on the evaluation of conditions as the
remediation gets underway. It is anticipated that the new onsite
extraction well will effectively produce a hydraulic barrier that
will prevent further contaminant migration from the Site.
contaminated groundwater from both extraction wells will be piped
through the existing discharge system to Town Branch Creek. If
the TCE level in the groundwater extracted from these wells is
found to exceed the discharge limitations set forth iri the NPDES
permit or if ambient air monitoring indicates an unacceptable
health risk resulting from air emissions at the point of
discharge, then it will be necessary to invoke the contingency
phase of this project consisting of further treatment prior to
discharge. Periodic monitoring of ambient air quality along with
water quality monitoring, in accordance with the NPDES permit,
will be performed. If needed, the additional treatment will
remove the volatile organic contaminants from the groundwater.
34
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«
An existing pipeline will carry the extracted groundwater from
the Site to Town Branch Creek, where additional aeration and
mixing occurs as the water flows down over riprap to the creek
proper. The discharge operates under a state NPDES permit which
stipulates a TCE monthly average discharge limit of 1,000 ug/l.
Subsurface soil contamination at the Site, further contributing
to the groundwater contamination, is to be addressed by the
installation of a series of ,parallel trenches to be located above
the contaminated soil on the Lee Chemical Site. Uncontaminated
raw water from the City's well field will be utilized to flood
these trenches, allowing water to saturate the contaminated soils
below and thereby flushing contaminants. 'to the groundwater to
subsequently be picked up by the groundwater extraction system.
The number and depth of the trenches and the operational
parameters will be determined during the remedial design and
modified as site conditions warrant once actual remediation
begins.
The estimated capital cost of the remedy is $325,000, with annual
O&M costs estimated to be $52,000. Assuming a 5 year operation
and a 10% discount rate, the present worth is $550,000. Some
changes may be made to the remedy as a result of the remedial
design and construction processes, thereby affecting the
estimated costs. Such changes, in general, reflect modifications
resulting from the engineering design process or the use of the
contingency phase air stripper. For the air stripper, an
additional capital cost of $50,000 has been estimated, with
annual O&M costs estimated at $15,000. Assuming a 5 year
operation and a 10% discount rate, the present worth is
approximately $120,000 for this contingency phase.
. 9.1 Remediation Goals
The purpose of this response action is to prevent potential
exposure to contaminated groundwater; protect uncontaminated
groundwater for future use by preventing further migration of the
contaminated groundwater plume; restore the contaminated aquifer
for future use as a .drinking water source by reducing the
contaminant concentrations to regulated or health-based levels,
for example, 5 ppb or less for TCE, and remediate contaminated
soils onsite such that no further groundwater contamination with
VOCs above action levels can occur. Existing conditions at the
site have been detirmined to pose an excess lifetime cancer risk
as high as 2 X 10-. The lifetime non-carcinogenic risk from
exposure to site contaminants is insignificant. These risks
relate to the VOC concentrations in groundwater which were found
to be as high as 130 ug/l during the RI. U
The acceptable exposure levels at this site that are protective
of human health and the environment were developed by considering
the ARARs identified in Section 10.2. Attainment of the chemical
specific ARARs will result in cumulative cgrcinogenic risks at
the Site within the acceptable 10- to 10- risk range for
carcinogens, considering all contaminants and exposure pathways
at the Site.
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SECTION 10.0
STATUTORY DETERMINATIONS
Under its legal authorities, EPA's primary responsibility at
Superfund sites is to undertake remedial actions that achieve
adequate protection of human health and the environment. In
addition, section 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
standards established under Federal and State environmental laws
unless a statutory waiver is justified. The selected remedy also
must be cost effective and utilize permanent solutions and
alternative treatment technologies or resource recovery
technologies to the maximum extent practicable. Finally, the
statute includes a preference for remedies that employ treatment
that permanently and significantly reduce the volume, toxicity,
or mobility of hazardous substances as their principal element.
The following subsections discuss how the selected remedy meets
these statutory requirements.
10.1 Protection of Human Health and the Environment
The selected remedy protects human health and the environment
through extraction of the VOC-contaminated groundwater. The
contaminants will be permanently removed from onsite soils and
the groundwater. Extraction of the VOC-contaminated groundwater
and remediation of contaminated site soils will eliminate the
threat of exposure to the most mobile contaminants at the Site.
The current carcinogenic risks associated with the exposure
pathwaYf identified in the risk assessment are as high as
2 X 10-. The selected remedy will riduce th~ cancer risks at
the site to within the acceptable 10- to 10- risk range for
carcinogens, and the Hazard Index for non-carcinogens will be
less than one. There are no unacceptable short-term threats
associated with the selected remedy that cannot be readily
controlled. In addition, no adverse cross-media impacts are
expected from the remedy.
10.2 Compliance Applicable or Relevant and Appropriate
Reauirements CARARs)
The selected remedy wiil comply with all federal and state
applicable or relevant and appropriate requirements (ARARs).
Applicable requirements are those state or federal requirements
legally applicable to the release or remedial action contemplated
that specifically address a hazardous substance, pollutant,
con~aminant, remedial action, location or other circumstance
found at the Site. If it is determined that a requirement is not
applicable, it may still be relevant and appropriate to the
circumstances of the release. Requirements are relevant and
appropriate if they address problems or situations sUfficiently
similar to the circumstances of the release or remedial action
contemplated and are well-suited to the Site.
36
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Numerical values for the chemical-specific ARARs identified for
the site are listed in Table 7. No federal or state location-
specific ARARs were identified for the site. . The major chemical-
specific and action-specific ARARs for the Lee Chemical site are
listed below:
Chemical-specific ARARs
Federal Maximum Contaminant Levels for volatile organics in
drinking water supplies (40 CFR Part 141).
Establishes health-based standards, maximum contaminant
levels (MCLs), for pUblic water systems.
- MCLs for organic contaminants are applicable to
groundwater.
state Maximum Volatile Organic Chemical contaminant Levels for
public water systems (10 CSR 60-4.100).
- Establishes maximum chemical contaminant levels for
volatile organic chemicals in public water systems.
- Maximum contaminant levels may be applicable to
groundwater at the Site.
Federal Water Quality criteria (40 CFR Part 131) Quality
Criteria for water.
- Establishes criteria for water quality based on
toxicity to aquatic organisms and human health.
- Ambient water quality criteria may be relevant
and appropriate for the discharge to Town Branch.
state Water Quality Standards for volatile organics in
groundwater (10 CSR 20-7.031).
- Establishes maximum contaminant
requirements.
- Requirements may be applicable
federal requirements.
Action-specific ARARs
levels and monitoring
if more stringent than
National Primary and Secondary Ambient Air Quality Standards
(40 CFR Part 50).
- Establishes primary (health based) and secondary
(welfare based) standards for air quality.
- Standards may be relevant and appropriate to emissions
from discharge to Town Branch.
National Pollution Discharge Elimination System (NPDES)
(40 CFR Part 125)
- Requires permits for the discharge of pollutants
into the waters of the United states.
37
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- NPDES permit is in effect for discharge to
Town Branch.
state Air Quality DeMinimis Emission Levels 10 CSR
6.060 (7) (A) .
- Establishes requirements for new source emission
permits.
- Requirements may be relevant and appropriate to
emissions from discharge to Town Branch.
state Water Quality Standards for Aquatic Life Protection
(10 CSR 20-7.031).
- Promulgates standards and rules to protect the quality
of lakes and streams.
- Standards and rules may be relevant and appropriate to
the discharge to Town Branch.
10.3 Cost Effectiveness
The selected remedy is cost effective because it has been
determined to provide overall effectiveness proportional to its
costs, the net present worth value-being $550,000.
10.4 Utilization of Permanent Solutions and Alternative Treatment
Technoloqies to the Maximum Extent Practicable
The state of Missouri and EPA have determined that the selected
remedy represents the maximum extent to which permanent solutions
and treatment technologies can be utilized in a cost effective
manner for the Lee Chemical site. Of those Alternatives that are
protective of human health and the environment and comply with
ARARs, the state of Missouri and EPA have 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, also considering the
statutory preference for treatment as a principal element and
considering state and community input. .
Alternative V reduces the toxicity, mobility, and volume of the
contaminants in the groundwater and soil; complies with ARARs;
provides short-term effectiveness; and protects human health and
the environment equally as well as all other Alternatives. In
terms of implementability, Alternative V is more reliable than
other Alternatives because the combination of a new extraction
well and soil washing system should result in a much quicker
removal of the contamination thus helping to prevent further
migration of the contaminants. Alternative V will be easy to
implement technically because it requires only normal
construction activities and administratively because it will
require little additional coordination with relevant agencies.
The major trade-offs that provide the basis for this selection
decision are implementability and cost effectiveness. The
38
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selected remedy is an enhancement of the interim response action
currently operating at the Site and thus is known to .be reliable.
The basic improvements to the existing process provided for in
Alternative V can be implemented quickly and with more confidence
that they will protect the City's remaining water supply wells
from contamination. Therefore, Alternative Vis the most
appropriate permanent solution for the contaminated soil and
groundwater at the Lee'Chem~cal site.
10.5 Preference for Treatment as a Principal Element
The selected remedy removes the VOC contamination from the soils
at the site as well as capturing and removing contaminated
groundwater. Thus, the selected remedy addresses the principal
threats posed by the Site through the use of proven treatment
methods. Therefore, the statutory preference for remedies that
employ treatment as a principal element is satisfied. The
contingency phase project for additional treatment of the
extracted groundwater also incorporates treatment as a principal
element.
SECTION 11.0
DOCUMENTATION OF SIGNIFICANT DIFFERENCES
No significant changes were made to the recommended alternative
in the Proposed Plan.
39
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RECORD OF DECISION
THE RESPONSIVENESS SUMMARY
LEE CHEMICAL SITE
LIBERTY, MISSOURI
Prepared By:
Missouri Department of Natural Resources
Waste Management Program
Jefferson City, Missouri
And
u.S. Environmental Protection Agency
Region VII
Kansas City, Kansas
March 1991
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1.0
2.0
3.0
RESPONSIVENESS SUMMARY
TABLE OF CONTENTS
SECTION
PAGE
OVERVI EW. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
BACKGROUND ON COMMUNITY INVOLVEMENT.....................1
SUMMARY OF COMMENTS RECEIVED DURING
PUBLI C COMMENT PERIOD................................... 2
i
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LEE CHEMICAL SITE
LIBERTY, MISSOURI
RESPONSIVENESS SUMMARY
SECTION 1.0
OVERVIEW
In the Proposed Plan released to the public, the Missouri
Department of Natural Resources (MDNR), with U.S. Environmental
Protection Agency concurrence, made a preliminary selection for
the preferred Alternative. MDNR's recommended Alternative
addressed the groundwater and soil contamination problem at the
Site. The preferred alternative involved extraction and
containment of the contaminant plume using existing and new
wells, implementing an in-situ aqueous soil washing system
consisting of infiltration trenches to enhance the flushing of
contaminants from site soils, and discharge of the purged
groundwater to Town Branch Creek under the terms and conditions
of a NPDES permit.
In the event that additional treatment of the discharge water
becomes necessary to meet either the NPDES permit limits or other
applicable or relevant and appropriate requirements, a
contingency phase project consisting of air stripping or other
treatment methods will be implemented to bring the discharge into
compliance.
No comments were received during the public comment period
opposing the preferred alternative as presented. One Liberty
resident asked for an analysis of the effects of
1,1,2-trichloroethene (TCE) on Town Branch and Shoal Creeks and
the possibility of bioaccumulation occurring. This resident also
asked what the impacts resulting from the release of TCE into the
air, either through the outfall from the wells or through an air
stripper if required, will have on the people who work down in
the bottoms near the site.
The Potentially Responsible Party supported the preferred
Alternative as described in the Proposed Plan.
SECTION 2.0
BACKGROUND ON COMMUNITY INVOLVEMENT
Community interest in the Site dates back to 1979 when
contamination of .the public water supply wells in Liberty was
first discovered. The major issues expressed at that time were
concerned with providing the community with a safe drinking water
supply. This issue was addressed by the interim response action
taken by the City of Liberty which effectively returned levels of
TCE in the publi~ water supply to below levels of concern. The
RI/FS process was performed with regular. reports to the City
Council on its progress and findings.
1
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The public comment period on the preferred Alternative as
outlined in the Proposed Plan began on December 24, 1990 and
ended January 23, 1991. A public hearing was held in Liberty on
January 9, 1991. The responsiveness summary addresses comments
received during this period.
SECTION 3.0
SUMMARY OF COMMENTS RECEIVED DURING PUBLIC COMMENT
PERIOD
Comments received during the public comment period on the
Remedial Investigation, Feasibility Study, and Proposed Plan for
the Lee Chemical Site are briefly summarized below. Only two
comments were received.
Ouestion ~
Considering that purged groundwater has been discharged into
Town Branch Creek for several years, has anyone looked at the
effects of the TCE on the creek itself, i.e., buildup in the
sediment or the benthic organisms (the organisms living on the
creek bottoms) or anything of that nature? .
MDNR/EPA Response:
There have been no samples of sediments or of the organisms
living on the creek bottoms collected/analyzed from Town Branch
or Shoal Creek to date. There have been in-stream water quality
samples collected at the confluence of Town Branch and Shoal
Creek none of which showed significant concentrations of TCE.
Laboratory studies have demonstrated that TCE volatilizes
rapidly from water. Although volatilization is rapid, actual
volatilization rates are dependent upon temperature, water
movement and depth, associated air movement, and other factors.
Because neither biodegradation nor other fate processes occur at
a rapid rate, most TCE present in surface waters can be expected
to volatilize into the .atmosphere.
The biological process of bioaccumulation is generally
reported in terms of a bioconcentration factor (BCF), the ratio
of the concentration of a substance in a living organism to the
equilibrium concentration in the medium in which the organism
lives. Bioconcentration factors reported in the literature
generally range from one to one million. Experimental BCF data
measuring TCE concentrations in fish, seawater, and associated
aquatic organisms supports a low bioaccumulation potential for
benthic organisms (i.e. BCF of 17 in fish). Although evidence of
bioaccumulation potential exists, the process for TCE is probably
not important in comparison to other removal mechanisms, such as
volatilization.
2
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The level of TCE concentrations entering Town Branch at the
outfall has consistently been below 90 parts pe~ billion (ppb)
since the RI commenced. Based on that data, it would appear
there is an almost complete volatilization of the TCE in the
water between the point of discharge and the confluence of Sh~~l
Creek (approximately 1600 feet).
However, in response to this concern, MDNR will further
inv~stigate the need to sample and analyze the creek sediments
and benthic organisms for TCE bioaccumulation.
Ouestion ~
What are the air impacts of TCE being released, either through
the outfall from the wells or an air stripper if implemented, on
people who work in the bottoms near the site?
MDNR/EPA RESPONSE:
As part of the Risk Evaluation prepared for the Lee Chemical
Site, inhalation of VOCs by residents and industrial workers
downwind of the extraction well discharge point on Town Branch
was examined.
The purged water flows through a discharge line to Town Branch
where it continues over a dispersion plate and then cascades down
the embankment approximately 20 to 30 feet over riprap and enters
the Town Branch. Although the VOCs in this water will partially
volatilize and potentially expose those downwind of the discharge
point, we studied the exposure of workers and residents closest
to the Site and found negligible risks. The extent of exposure
was calculated based on employees working at the closest facility
to the discharge point (100 yards) and on the closest permanent
residents (200 yards), because they would have the potential for
the highest exposure duration.
Should discharge concentrations increase to levels that would
represent a significant risk to resident and worker populations,
monitoring of ambient air quality will be performed to verify
these risks. If this monitoring indicates that an unacceptable
health risk is resulting from air emissions at the point of
discharge, it will then be necessary to invoke the contingency
. phase of this project consisting of further treatment prior to
discharge.
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