PB95-964039
EPA/ROD/R04-95/256
March 1996
EPA Superfund
Record of Decision:
Velsicol Chemical Corporation,
Hardeman County (O.U. 2), TN
9/26//1995
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VELSICOIAHARDEMAN COUNTY LANDFILL
SUPERFUND SITE
OPERABLE UNIT #2
RECORD OF DECISION
t _ I - - - * _ *
U.S. Environmental Protection Agency
Region IV
September 26, 1995
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RECORD OF DECISION
TABLE OF CONTENTS
1.0 DECLARATION
V
2.0 DECISION SUMMARY 1
2.1 SITE NAME, LOCATION, AND DESCRIPTION 1
2.2 SITE HISTORY AND ENFORCEMENT ACTIVITIES 1
2.2.1 Site History 1
2.2.2 Enforcement Activities 5
2.3 HIGHLIGHTS OF COMMUNITY PARTICIPATION 7
2.4 SCOPE AND ROLE OF OPERABLE UNIT 8
2.5 SITE CHARACTERISTICS 9
2.5.1 Demography 9
2.5.2 Land Use 10
2.5.3 Natural Resources 10
2.5.4 Climatology 12
2.5.5 Site Stratigraphy 12
2.5.6 Site Hydrogeology 13
2.5.7 Waste Characterization 14
2.5.7.1 Characterization by Waste Inventory Records 14
2.5.7.2 Characterization by Landfill Waste Sampling 15
2.5.8 Contaminant Migration 18
2.5.9 Results of Supplementary Field Investigations 22
2.5.9.1 Landfill Waste Sampling and Data Evaluation Report . 22
2.5.10 Contaminant Distribution and Migration 24
2.5.11 Treatability Study 25
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RECORD OF DECISION
TABLE OF CONTENTS
2.6 SUMMARY OF SITE RISKS 26
2.6.1 Environmental Evaluation Report 26
2.6.2 Human Health Evaluation 38
2.6.3 Soil Action Levels for Groundwater Protection 39
2.6.4 Soil Action Levels for Direct Contact 41
2.7 DESCRIPTION OF ALTERNATIVES 41
2.7.1 Alternative A-l - No Further Action 41
2.7.1.1 Description 41
2.7.1.2 Assessment 46
2.7.2 Alternative A-2 - In Situ Soil Vapor Extraction 47
2.7.2.1 Description 47
2.7.2.2 Assessment 48
2.7.3 Alternative A-3 - RCRA Composite Cap 51
2.7.3.1 Description 51
2.7.3.2 Assessment 51
2.7.4 Alternative A-4 - RCRA Composite Cap; In Situ Soil Vapor
Extraction 53
2.7.4.1 Description 53
2.7.4.2 Assessment 53
2.7.5 Alternative A-5 - Excavate Waste and Contaminated Soil; On-Site
Thermal Treatment; Replace Existing Clay Cap 56
2.7.5.1 Description ' 56
2.7.5.2 Assessment 56
2.7.6 Alternative A6 - Excavate Waste and Place in On-Site RCRA Landfill;
RCRA Cap for Soil 58
2.7.6.1 Description 58
ii
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RECORD OF DECISION
TABLE OF CONTENTS
2.7.6.2 Assessment 59
2.7.7 Alternative A-7 - Excavate Waste and Place in On-Site RCRA Landfill;
Replace Existing Clay Cap; In Situ Soil Vapor Extraction .... 61
2.7.7.1 Description 61
2.7.7.2 Assessment 61
2.8 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES . . 64
2.8.1 Overall Protection of Human Health And The Environment . . 64
2.8.2 Compliance with ARARs 68
2.8.3 Long-Term Effectiveness and Permanence 68
2.8.4 Reduction of Toxicity, Mobility and Volume 69
2.8.5 Short-Term Effectiveness 70
2.8.6 Implementability 72
2.8.7 Cost 73
2.8.8 State Acceptance 73
2.8.9 Community Acceptance 75
2.9 SELECTED REMEDY 75
2.10 STATUTORY DETERMINATIONS . 75
2.10.1 Overall Protection of Human Health and the 75
2.10.2 Compliance with Applicable or Relevant and Appropriate
Requirements (ARARs) 78
2.10.3 Cost-Effectiveness 79
2.10.4 Utilization of Permanent Solutions and Alternative Treatment (or
Resource Recovery) Technologies to the Maximum Extent
Practicable 79
2.10.5 Preference for Treatment as a Principal Element 79
3.0 RESPONSIVENESS SUMMARY OVERVIEW 80
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RECORD OF DECISION
TABLE OF CONTENTS
LIST OF FIGURES
FIGURE 2.1 SITE LOCATION - VELSICOL/HARDEMAN COUNTY LANDFILL . 2
FIGURE 2.2 SITE LOCATION - VELSICOL/HARDEMAN COUNTY LANDFILL . 3
LIST OF TABLES
TABLE 2.1 SUMMARY OF WASTE DISPOSAL AT HARDEMAN COUNTY
LANDFILL . 4
TABLE 2.2 SUMMARY OF ANALYTICAL DATA - ANGLED BORING
SAMPLES 16
TABLE 2.3 SUMMARY OF DETECTED COMPOUNDS - SOIL BORING
PROGRAM 19
TABLE 2.4 SUMMARY OF BIOASSAY RESULTS 28
TABLE 2.5 SUMMARY OF PUGH CREEK WATER ANALYTICAL DATA 29
TABLE 2.6 SUMMARY OF DETECTED ORGANIC COMPOUNDS IN SEEP SOIL
SAMPLES 33
TABLE 2.7 SUMMARY OF DETECTED METAL COMPOUNDS IN SEEP SODL
SAMPLES 34
TABLE 2.8 CHEMICAL-SPECIFIC TARGET LEVELS 42
TABLE 2.9 POTENTIAL CHEMICAL-SPECIFIC GUIDELINES (TBCs) 43
TABLE 2.10 DETAHJSD ANALYSIS OF CRITERIA AND FACTORS 65
TABLE 2.11 COMPARISON OF ALTERNATIVES 67
TABLE 2.12 SUMMARY OF ALTERNATIVE COSTS 74
TABLE 2.13 ALTERNATIVE A-3 COST ESTIMATE "RCRA CAP" 76
iv
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Draft Record of Decision
Velsicol/Hardeman County OU#2
Page v
1.0 DECLARATION
SITE NAME AND LOCATION
Velsicol/Hardeman County Landfill, Operable Unit #2
Toone-Teague Road
Toone, Tennessee
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for the Velsicol Hardeman County
Landfill, Operable Unit #2, in Toone, Hardeman County, Tennessee. This action is chosen in
accordance with CERCLA, as amended by SARA, and, to the extent practicable, the National
Contingency Plan. This decision is based on the Administrative Record for this Site.
The State of Tennessee concurs with the selected remedy.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this Site, if not addressed by
implementing the response action selected in this ROD, may present an imminent and substantial
endangerment to public health, welfare, or the environment.
DESCRIPTION OF THE RFMFT)Y
This operable unit is the final action of two operable units for the Site. The first operable unit
at this Site involved groundwater remediation. This action addresses the source of groundwater
contamination.
The remedy includes capping the 27-acre landfill with a RCRA composite cap to reduce
infiltration of surface water through the waste and contaminated soil. The RCRA composite cap
consists of:
scarifying existing vegetative cover and recompacting;
a 40-mil high density polyethylene (HDPE) synthetic liner or equivalent, placed over the
recompacted clay surface;
a sand drainage blanket with a minimum hydraulic conductivity of 1 x 10~3 cm/sec placed
over the liner to provide lateral drainage;
the sand will be covered with a filter fabric and a layer of common fill and topsoil;
a vegetative cover will be established to prevent erosion of the fill and topsoil materials;
and
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Draft Record of Decision
Velsicol/Hardeman County OU#2
Page vi
routine monitoring of the RCRA cap in order to maintain the integrity of the cap.
The current network of monitoring wells established by OU #1 will provide the long-term means
of monitoring the effectiveness of this remedy.
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 the Site. However, because treatment of
the principal threats of the Site was not found to be practicable, this remedy does not satisfy the
statutory preference for treatment as a principal element.
Because this remedy will result in hazardous substances remaining on-site 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.
Date Richard D. Green, Associate Director
Office of Superfimd and Emergency Response
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Draft Record of Decision
Velsicol/Hardeman County OUiP2
Page 1
2.0 DECISION SUMMARY
2.1 SITE NAME, LOCATION, AND DESCRIPTION
The Velsicol/Hardeman County Landfill is located on Toone-Teague Road, Hardeman County,
Tennessee. The property is located approximately one mile north of Tennessee State Highway
100 (see Figure 2.1) and approximately one mile south of Clover Creek. The property, shown
on Figure 2.2, is bound by Old Toone road to the west and railroad right-of-way to the east.
Approximately 27 acres of the 242-acre property were operated as a landfill between 1964 and
1973 for the disposal of pesticide waste generated at the Velsicol Memphis, Tennessee Plant.
2.2 SITE HISTORY AND ENFORCEMENT ACTIVITIES
2.2.1 Site History
In July 1964, Velsicol Chemical Corporation purchased 242 acres of land in Hardeman County,
Tennessee, specifically for use as a landfill to dispose of waste from Velsicol's Memphis,
Tennessee Plant Site. At the time Velsicol purchased the property, and prior to commencing
landfilling operations, Velsicol consulted with the United States Geological Survey (USGS) about
the location of aquifers in the area and their relationship to the Memphis Sand Aquifer. In an
attempt to address this issue, Velsicol installed a well in the immediate vicinity of the proposed
disposal area. The purpose of the well was to establish a water supply well in an aquifer that
would supply a sufficient potable water supply and to provide a means of sampling the
groundwater beneath the Site for evidence of contamination. The borehole was completed to a
depth of approximately 224 feet below the ground surface at which point an artisan groundwater
condition was encountered. A well was installed in this borehole.
Immediately upon purchasing the property, Velsicol erected a fence around a portion of the
property where the landfilling was to commence. The landfilling operation commenced in
October 1964 and continued until June 1973. At the time of closure, waste had been disposed
of in three specific areas which covered a total area of approximately 27 acres. During the
development of the Remedial Investigation (RI), Velsicol completed a detailed estimate of waste
volumes based on plant production rates. A detailed and accurate estimate of waste quantity and
type, based on this review by Velsicol, is summarized in Table 2.1.
Development of the landfill began in October 1964 with the northern disposal area, since it was
the only area on the property which was cleared of trees. Waste disposal commenced along the
east side of the north disposal area and was continued longitudinally in the direction of the Site
ridges. The middle and south disposal areas were developed sometime in the late 1960s or early
1970s. Subsequent to a public meeting held in Jackson, Tennessee in March 1971, the
Tennessee Department of Health and Environment (TDHE) evaluated the landfilling operation
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CHICKASAW
STAfC PARK AND FOREST
WILDLIFE MANAGEMENT
AREA
JOOO
FIGURE 2.2 SITE LOCATION - VELSICOUHARDEMAN COUNTY LANDFILL
Page 3
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TABLE 2.1
SUMMARY OF WASTE DISPOSAL AT HARDEMAN COUNTY LANDHLL
HARDEMAN COUNTY LANDHLL, OPERABLE UNIT #2
HARDEMAN COUNTY, TENNESSEE
Waste
Heptachlor Catalyst
Heptane Residue
Fiber Drums
IPA Still D-30 Bottoms
AN2K
Acetic Add Bottoms
R-2 Bottoms
Chlorendic Anhydride
Still Bottoms
PCL Bottoms J-ll
Carbon Beds
Bandane Filter Cake
Notes:
H
I
B
S
Weight
Density
(Ibslgal)
10.1
6.3
--
12.0
--
19.9
7.1
10.8
14.1
9.4
15.6
Total
Weight
(Ibs)
2,539,000
14,539,000
--
16,128,000
19,351,000
13,854,940
10,125,000
13,988,000
1,515,000
3,122,000
Total
Volume
(Gal)
251,386
2,307,778
--
1,344,000
994,605
972,412
1,951,400
937,500
992,057
161,170
200,128
Equivalent
It of Drums
4,571
41,960
45/117
24,436
18,084
17,680
35,480
17,045
18,037
2,930
3,639
Method
of Disposal
H
1/B
H
»I/H
I/B
I/H
I/H/S
M/H
I/H
H
H
Equivalent #
of Drums
landfilled
4,571
--
45,417
15,883
11,492
23,062
11,079
11,724
2,930
3,639
95,161,940
10,112,436
229,279
Disposal by landfilling at Hardeman County Landfill
Disposal by incineration at Memphis Plant Site
Disposed as fuel in plant boiler
Disposal by discharging to the local sanitary sewer
Waste disposed of by incineration. However, when incinerator was not operating (65 percent of time),
waste disposed of by landfilling at Hardeman County Landfill.
129,797
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Draft Record of Decision
Velsicol/Hardeman County OU#2
PageS
at the Hardeman County Site. On the basis of this evaluation, a Commissioner's Order was
issued to Velsicol which required Velsicol to cease disposal operations in the south disposal area
in August 1972, but allowed limited waste disposal in the middle and north disposal areas until
June 1973. Therefore, after closure of the south disposal area, selected wastes continued to be
disposed of in the north and middle disposal areas until the Site was permanently closed in June
1973.
Plant waste was disposed of in trenches which were excavated longitudinally along the top of
Site ridges, it has been reported that each trench was excavated to a depth of 12 to 15 feet; to
a width of 10 to 12 feet; and to a length of 200 to 500 feet. Approximately four to eight feet
were maintained between each trench when excavated.
As each transport vehicle arrived at the landfill the containerized waste was dumped off of the
truck into one of the excavated disposal trenches. On occasion, drums were set upright in the
trenches upon disposal. In most cases however, the containerized waste was left in the trench
in the random order and orientation of which it had been dumped. Disposed waste was covered
daily with soil excavated from the trenches. Upon filling each trench, the trench of
containerized waste was covered with a minimum of three feet of soil which had also been
excavated from the trenches. The cover material was placed and compacted with a bulldozer
and was mounded over the backfilled trenches to allow for future settlement. Periodically, as
the backfilled areas settled, repairs were made by backfilling with additional soil. The repair
of settled areas was carried out on a regular basis and in most cases the settling over the disposal
areas had subsided within five years of initial backfilling. All backfilled areas were seeded,
fertilized and limed to prevent erosion.
2.2.2 Enforcement Activities
The Velsicol/Hardeman County Landfill was included on the National Priorities List in
December 1982. The studies completed to date have shown that contamination of the local
groundwater has occurred. The extent of contaminant migration from the Site is such that the
use of groundwater as a domestic water supply by residences within the immediate vicinity of
the Site was halted in 1979.
In order to minimize the impact caused by the disposed waste, the Site was remediated in the
fall of 1980 by constructing a low permeability clay cap over the disposal areas. The scope of
the remedial work was outlined in a letter dated July 10, 1980 from Velsicol to the TDHE. The
TDHE approved the Scope of Work in a July 10, 1980 letter to Velsicol.
Subsequent to completing the Site cap, a three-year monitoring program was implemented to
assess the effectiveness of the cap. The results of this monitoring program were presented in
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Draft Record of Decision
Velsicol/Hardeman County OU#2
Page 6
a final report entitled "Environmental Evaluation and Assessment of Control Measures at the
Velsicol Disposal Site-Hardeman County Tennessee" ERM Southeast Inc. (ERM) February
1985. The results of ERM's study and modeling confirmed that the cap was effective in
reducing contaminant migration from the Site.
Upon completion of the monitoring program, TDHE issued a notice letter to Velsicol on
November 5,1985 which required Velsicol to conduct a Remedial Investigation/Feasibility Study
(RI/FS) at the Site. The RI/FS was designed and implemented to meet the requirements of the
State Superfund procedures, the National Contingency Plan, Federal Superfund procedures as
presented in the Comprehensive Environmental Response Compensation and Liability Act
(CERCLA) as amended by the Superfund Amendment and Reauthorization Act (SARA), and the
eventual agreement between TDHE and USEPA Region IV.
During the progress of the RI/FS work, TDHE relinquished oversight responsibilities for the
RI/FS to USEPA. Based on this change in responsibility, USEPA negotiated an Administrative
Order on Consent (AOC) with Velsicol. The AOC was signed by Velsicol on January 26, 1989
and became effective on February 17, 1989.
Velsicol subsequently completed the RI/FS for the Site in April 1991 an USEPA prepared a
Record of Decision (ROD), dated June 27, 1991, for the Site. The outline of proposed remedial
activities, as selected by USEPA, is embodied in the ROD for the Site.
From July to September 1991, negotiations were conducted with the Velsicol Chemical
Corporation to perform and pay for the Remedial Design/Remedial Action (RD/RA). An
agreement could not be reached with Velsicol to perform the work by the end of the negotiation
period. Subsequently, USEPA issued a Unilateral Administrative Order (UAO) that requires
. Velsicol to conduct the RD/RA for the contaminated groundwater, hereinafter referred to as
Operable Unit #1 (OU #1). The Order also includes USEPA's Statement of Work (SOW) for
the RD/RA. The Order was signed by USEPA on October 17, 1991 and became effective
November 29, 1991.
In addition to conducting the RD/RA for OU #1, Velsicol is required to conduct an FS for the
landfill area operable unit (OU #2). Velsicol and USEPA negotiated a First Amendment to the
February 17, 1989 RI/FS Consent Order (First Amendment) to address OU #2 FS. The First
Amendment was signed by Velsicol on October 21, 1991 and became effective on November
4, 1991. The First Amendment includes an FS SOW.
The purpose of the OU #2 FS is to develop and evaluate additional potential remedial action
alternatives for remediating the source of the contamination (the wastes in the disposal areas) at
the Site.
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Draft Record of Decision
Velsicol/Hardeman County OU#2
Page?
The OU #2 FS Work Plan includes provisions for an environmental risk evaluation for purposes
of assessing current and potential future risks to the environment caused by the disposed waste.
The requirements of the environmental risk evaluation include ecological studies, and additional
soil sampling to supplement the existing ecological database at the Site. Velsicol completed the
required supplementary field investigations during the summer of 1992. This has been
completed and approved by USEPA (Environmental Evaluation Report, April 1993) and showed
that the Site posed no risk to the environment. Additionally, in support of the remedial action
alternatives evaluation, Velsicol conducted, at USEPA's request, landfill waste and soil sampling
analysis, and technology-specific treatability studies on samples of landfill soil and waste. These
USEPA-approved studies are presented hi the Landfill Waste Sampling and Data Evaluation
Report (March 1993) and the Landfill Waste Treatability Study Evaluation Report (February
1994).
The OU #2 FS augmented the evaluation of corrective action alternatives developed within the
original FS. This OU #2 FS evaluated additional remedial alternatives which were not
considered in the original FS and included the results of the treatability studies. In all cases
where remedial action alternatives were evaluated, the evaluations consider the selected
groundwater containment remedy (OU #1) as an integral component of each landfill source
control alternative.
2.3 HIGHLIGHTS OF COMMUNITY PARTICIPATION
In April of 1991, EPA issued a Fact Sheet which summarized the proposed alternatives for
remediating the groundwater. Following a public comment period, EPA signed a Record of
Decision (ROD) in June 1991 which presented the selected remedy. A Superfund Fact Sheet
Update was mailed to interested citizens hi April 1992.
The OU #2 additional investigations, FS and Proposed Plan were released to the public in July
1995. These documents were made available to the public hi the Administrative Record and the
information repository maintained at the EPA Docket Room in Region 4 and at the Bolivar-
Hardeman County Public Library. The notice of the availability of these two documents was
published in the Bulletin-Times and the Jackson Sun on July 5, 1995.
A public comment period was held from July 13, 1995 to August 12, 1995. No written public
comments were received during this period. No request for an extension to the public comment
was made. In addition, a public meeting was held on July 13, 1995. At this meeting,
representatives from EPA and the Tennessee Department of Environment and Conservation
(TDEC) answered questions relating to the Site and the remedial alternatives under
consideration. A Bulletin-Times reporter and a local Jackson TV news-station, WBBJ, attended
the public meeting. A transcript of the public meeting is included in the Responsiveness
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Draft Record of Decision
Velsicol/Hardeman County OU#2
PageS
Summary, which is part of this ROD.
This decision document presents the selected remedial action for the Velsicol/Hardeman County
Landfill Superfiind Site, OU #2, in Hardeman County Tennessee. The remedial action chosen,
is in accordance with CERCLA, as amended by SARA, and, to the extent practicable, the
National Contingency Plan. The decision for this Site is based on the Administrative Record.
2.4 SCOPE AND ROLE OF OPERABLE UNIT
As with many Superfiind sites, the problems at the Velsicol/Hardeman County Landfill OU #2
are complex. As a result, EPA organized the work into two operable units (OUs). These are:
OU #1: Contamination in the aquifer.
OU #2: Contamination in the soils.
Remedial action objectives for both the waste disposal areas and off-Site groundwater were
developed and presented in the original FS. Since the selected groundwater extraction and
treatment system for OU #1 (which now forms part of the final Site remedy under OU #2) has
been designed to meet off-Site groundwater remedial action objectives, only the remedial action
objectives specifically for the waste disposal areas remain to be addressed. Construction for OU
#1 will be completed by December 1995.
Waste contained within the three waste disposal areas and soils directly beneath the wastes have
been characterized through a detailed review of historic plant production records from Velsicol's
Memphis Tennessee plant and analysis of soil samples collected from beneath the wastes during
the RI. Additional waste and soil samples were collected during 1992 from boreholes drill
through the landfilled waste and underlying soil.
Concentrations of chemical constituents identified in the soils beneath the waste materials exceed
the potential health-based chemical-specific target levels for soils. These target level
concentrations are based upon contact and associated ingestion hazards as a result of direct
exposure to the wastes and contaminated soil.
The construction of a low permeability clay cap over the waste disposal areas in 1980 by
Velsicol has eliminated the potential health risk for direct contact or ingestion of waste materials
and contaminated soil.
In addition to direct contact and ingestion being potential routes of exposure to contaminants in
the disposed waste, the disposed waste could be a continuing source of contaminants to the
groundwater beneath the Site. Monitoring through the use of lysimeters and groundwater
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Draft Record of Decision
Velsicol/Hardeman County OU#2
Page 9
monitoring has demonstrated that the clay cap has been effective in reducing infiltration and
percolation of precipitation through the wastes into the groundwater. Therefore, although it has
been demonstrated that the clay cap has substantially reduced the potential for the disposed waste
to be a source of groundwater contamination, the presence of the wastes and contaminated soil
beneath the wastes still remains as a potential source of contamination to the groundwater.
Specific remedial action objectives for the waste disposal areas including soils directly beneath
the landfill wastes include:
i) prevent human exposure through direct contact or ingestion of landfill wastes or soils
directly beneath the wastes which have chemical constituent concentrations in excess of
the criteria levels identified in Table 2.8 (see Section 2.6.4); and
ii) prevent further degradation of the groundwater beneath and downgradient of the waste
disposal areas by chemical constituents found within the waste.
This second operable unit will be the final response action for this Site.
2.5 SITE CHARACTERISTICS
2.5.1 Demography
The Site is located in the sparsely populated northeast comer of Hardeman County, Tennessee.
According to 1990 census data, the total population of Hardeman County is 23,377 persons with
a density of 35.0 persons per square mile, as compared to the overall density of 118.3 for the
state. Approximately 74 percent of the residents in Hardeman County live outside of urban
areas, leaving 26.3 per square mile on a rural basis.
There are three small towns close to the Site with the following populations:
Toone (3 miles south): 279 (1990 Census)
Cloverport (5 miles west): 100 (approximately)
Teague (2 miles north): 15 (approximately)
There are approximately 60 persons within a one-mile radius of the Site. Historically, there
have been 26 residences supplied with an alternative water source from the town of Toone, as
a result of their private wells being contaminated.
According to the 1990 Census, employment in Hardeman County is distributed between a variety
of urban and rural occupations with the principal industries as follows:
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Draft Record of Decision
Velsicol/Hardeman County OU#2
Page 10
Manufacturing
Retail Trades
Health Services
Construction
Educational Services
Transportation and Communication
Public Administration
Finance
Agriculture and Forestry
Professional Services
Other
29.5%
16.1%
10.9%
6.7%
5.7%
5.5%
3.8%
3.3%
3.3%
3.2%
12%
The total number of employed persons within Hardeman County is 8,962 or 38.3 percent of the
county population.
Residents in the vicinity of the Site are either self-employed farmers, or commute to surrounding
rural towns such as Toone or cities such as Bolivar (10 miles south) or Jackson (20 miles north).
Based on growth rates from 1980 to 1990, the Toone division of Hardeman County experienced
an 11 percent population decline, compared with 2 percent decline for the County and 21 percent
decline for the Town of Toone itself.
2.5.2 Land Use
Although there is some agriculture and forestry in the Toone region, the rough topography of
the area in the vicinity of the Site generally limits land use to recreational activities. The three
disposal areas are situated on maturely eroded upland fluvial terraces encompassed by fairly
steepsided gullies and ravines. These uplands are approximately 80 to 100 feet above the
marshy plains of the surrounding creeks and wetlands.
Recreational use is primarily hunting, with some fishing on Clover Creek. The area is well
known for its wilderness characteristics as a good hunting ground for deer.
There is a local commercial catfish hatchery on Clover Creek downstream of the Site and in the
groundwater discharge area for the Site.
2.5.3 Natural Resources
The region of the county near the Site is sparsely populated with people and may be regarded
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Draft Record of Decision
Velsicol/Hardeman County OU#2
Page 11
as wilderness, farmland and wetlands, with dense forests supporting many indigenous species
of wildlife.
The terrestrial ecosystem has been described as consisting mainly of deer, rabbits, opossum,
raccoons, squirrels and snakes. Previous studies have shown contaminants above detection levels
with heptachlor epoxide in the muscle, liver, kidney and fat tissues of several collected species,
and hex vinyl chloride and endrin also detected in snake tissues. According to the 1981 study
results [Environmental Evaluation and Assessment of Control Measures at Velsicol Disposal Site
(ERM)], the levels of contamination in deer were reported to be well below the existing (1992)
USDA action levels and indicated no health hazard for consumption of game; however, certain
tissue and fat levels of heptachlor epoxide detected at that time were half the USDA action limit
of 300 ppb for rabbits. One of the three raccoons had heptachlor epoxide in its fat exceeding
300 ppb. Of all the opossums captured, only one had heptachlor epoxide in its tissue (liver)
exceeding 300 ppb. This concentration, 1,160 ppb is the highest level detected at the Site. The
results of these studies represent Site conditions prior to securement of the Site with the clay
cap.
The aquatic ecosystem of Clover and Pugh Creeks has been described as consisting mainly of
typical benthic organisms such as crayfish, snails and clams. Although contamination levels in
benthic organisms were reported in a 1980 study, these results were questioned with a study in
1981 that found detection of organic compounds in benthic organisms occurred in only 3 percent
of the analyses. Sporadic concentrations of heptachlor and endrin were reported in subsequent
surveys; however, no organic compounds were reported during 1983 sampling. It was
concluded that no significant bioaccumulation was occurring in the aquatic macroinvertebrates
based on the contaminant transport mechanisms at that time.
The surface water resource has been used for fishing. Bioassays of bluegill fish were conducted
in 1981 at five locations on Pugh Creek indicating no acute toxicity in the 96-hour study period.
There have been no warnings of health risk issued or banning of consumption, since there was
very little contamination apparent at that time of these previous studies. The studies recently
completed as part of the OU #2 environmental evaluation verify the previous studies showing
that there has been no adverse effects to the surface water bodies immediately adjacent to the
Site.
The groundwater resource is used by residents in the region as a drinking water source.'
Following the detection of organic chemical contamination in private wells immediately
downgradient of the Site, an alternate potable water supply from the town of Toone was
constructed in 1979 for 26 residences in a on-mile radius of the Site. Subsequent to 1979 all
future residents within the defined contaminant plume have been serviced by the Town of Toone
water supply. Deed restrictions are in effect as part of the Ou#l remedy to ensure that future
residents of property with contaminated groundwater will be serviced by the Town of Toone
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water supply.
2.5.4 Climatology
Although the Site is approximately 70 miles east of Memphis, Tennessee, the climate is
generally similar with the exception of being a few degrees cooler than Memphis with some
variation in monthly precipitation. The closest weather observation station is located 10 miles
south of the Site at the Bolivar Public Works Department. The prevailing winds are from the
south. Wind data were selected from the Jackson station 20 miles north of the Site.
The annual 30-year normal temperature for the area is 59.6°F with January being the coldest
month (mean temperature 38.0°F) and July being the warmest month (mean temperature of
79.4°F). The average annual precipitation is 51.3 inches with the greatest monthly precipitation
generally occurring in the winter and early spring (approximately 30 percent each season
compared with 20 percent for each of the summer and fall seasons).
2.5.5 Site Stratigraphy
The sediments underlying the Site are dominated by sand. The Claibome Formation outcrops
in areas of Hardeman County and is underlain by die Wilcox Formation. The two formations
are not differentiated in western Tennessee and combine to form a fairly thick sequence of sand
and silty sand with subordinate clay and silt. The Claibome Formation is mantled by a thin
discontinuous deposit of Quaternary alluvium and loess.
The Quaternary deposits are present across most of the study area. The alluvium is similar to
the underlying Claibome sediments and could not be differentiated from the Claibome Formation
in the study area. The alluvium is usually capped by loess which is glacially derived wind
blown silt. The thickness of the loess deposits ranges from 0 to approximately 12 feet.
The stratigraphy generally encountered in the first 20 feet is consistent across the Site. Clay or
silt is almost always present from the ground surface to three or five feet below ground surface
(BGS). The silt usually grades downward to silty sand which, in turn, grades to clean or slightly
silty sand. Low permeability soils were encountered (below the surface sediments) in eight
boreholes. They were usually very thin clay or silt layers interbedded with sand. Total
thickness of the low permeability layers was generally less than 1 foot.
The Claiborne/Wilcox sand consists of fine to medium grained quartz. Coarse-grained sand and
gravel is rare. It is usually well to medium-well sorted. Slightly silty to silty fine sand is
common. Colors range from light gray, pinkish gray, beige, orange-brown to dark reddish
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brown. It is sparsely to very micaceous. Limonite concretions and limonite cemented sand is
present but uncommon. Kaolin is often present as thinly interbedded lamination.
The clay layers in the Claibome and Wilcox Formations are usually less than 2 feet thick.
Thicker layers are often interbedded with clayey or silty sand. The clay is typically silty and
slightly sandy and has a low to medium plasticity. Colors range from white and pinkish white
(kaolin) to dark gray and brown.
The total thickness of the Claibome and Wilcox Formations was not determined during the
investigation. The Wilcox Formation rests unconformably on the Porter's Creek Clay. The top
of the Porter's Creek Clay is estimated to occur at an elevation of 220 to 240 feet above mean
sea level (AMSL) beneath the landfill. Previous studies have indicated that the Porter's Creek
Clay is approximately 120 feet thick.
2.5.6 Site Hydrogeology
The geologic conditions beneath the Site were found to be much different that previously
presented in Rima et al., 1964. The hydrogeology of the study area is consistent with that of
the northern Hardeman County region. The water bearing sands of the Claibome and Wilcox
Formations are essentially unconfined and therefore comprise a single water table aquifer. The
water table elevations range from 425 feet to 370 feet AMSL from south to north across the
study area. The Porter's Creek Clay is believed to form the north lower boundary of the Water
Table Aquifer. Also, this area is in the recharge zone of the Memphis Sand Aquifer.
The Claiborne-Wilcox hydrostratigraphic unit is the only unit which was investigated during the
RI. The Porter's Creek Clay is an aquitard and is believed to be the base of the groundwater
flow system at the Site.
The hydraulic conductivity of the Claibome-Wilcox unit, as determined from the grain-size
curves, ranges from 2 x 10"3 to 9 x 10~2 cm/sec with a geometric mean of 2 x 10~2 cm/sec. The
in situ hydraulic conductivity, as determined by the slug-injection tests, ranges from 4.4 x 10"5
cm/sec to 1.1 x 10~2 cm/sec, with a geometric mean of 1.0 x 10~3 cm/sec. For most of the
monitoring wells tested the hydraulic conductivity is in the range of 9 x 10~3 to 1.6 x 10~*
cm/sec. Pump tests conducted in 1993 during the remedial design for OU #1 indicated hydraulic
conductivities of 3.4 x 10~3 to 3.5 x 10~3 cm/sec. Subsequent calibration of a numeric model
indicated that use of an aquifer hydraulic conductivity of 2.5 x 10"3 cm/sec would be appropriate
for design purposes. The variation of hydraulic conductivity between monitoring wells reflects
the silt and clay beds that are found within the unconfined sand aquifer.
Water level elevations were collected from a total of 35 monitoring wells in August 1989,
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November 1991, May 1993, and October 1993. The data indicate that there is little seasonal
variation in the water level elevations in the Water Table Aquifer and that the water level
elevations are generally consistent with the elevation presented in ERM's February 1985
document.
Groundwater in the study area flows from south to north, with an average horizontal gradient
of 0.004 ft/ft. The water table contours also indicate that the unsaturated zone beneath the
disposal areas is 75 to 95 feet thick.
The actual water table elevations in the vicinity of Pugh and Clover Creeks indicate that they
are in fact discharge boundaries and groundwater originating from the Site does not flow beneath
these streams. Elevations at the supplemental wells west of the Site show that the unnamed
tributary southwest of the Site is also a discharge boundary. The major discharge area is Clover
Creek and the lower reaches of Pugh Creek. In its upper reaches upgradient of the Site, Pugh
Creek is intermittent indicating a poor hydraulic connection with the groundwater.
Using a horizontal hydraulic gradient of 0.004, a hydraulic conductivity of 3 x 10*3 cm/sec and
an assumed porosity of 0.25, a velocity of 4.8 x 10'3 cm/sec or 50 feet per year was estimated
in the RI. A maximum value for groundwater velocity was calculated using a hydraulic
conductivity of 1.11 x 10"2 cm/sec (highest value from the single well response tests), a
horizontal gradient of 0.004 and an assumed porosity of 0.2. These values yielded a velocity
of 2.2 x 10"4 cm/sec or 230 feet per year.
The presence of the numerous clay beds and lenses within the Water Table Aquifer would have
the effect of reducing the effective porosity. In addition, gravel seams have been identified in
some boreholes noted above. This, in fact, is the case at the Site because if the maximum flow
rates stated above were used, it would take approximately 26 years for groundwater beneath the
Site to reach Clover Creek. However, Site-related contaminants have already been detected in
the groundwater adjacent to the Clover Creek. Therefore, it is believed, based on the historical
data, that the groundwater velocity is on the order of double the calculated velocity.
2.5.7 Waste Characterization
2.5.7.1 Characterization by Waste Inventory Records
Characterization of the landfill waste was completed in order to verify the volume estimates
which were previously developed, identify indicator parameters which best represented the waste
at the Site as wells as to identify specific waste constituents which may not have been identified
to date. Special emphasis was placed on relatively mobile contaminants having the potential to
migrate from the Site. The characterization of landfill waste was primarily accomplished by
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Page 15
conducting a detailed analysis of historic waste generation records from Velsicol's Memphis,
Tennessee Plant Site and by the collection and analyses of angled boring samples taken from
directly beneath the waste disposal areas.
Table 2.1 presents a summary of the waste volume estimate. The wastes summarized in the
table contained specific hazardous constituents which may or may not potentially migrate from
the Site. The relative mobility of each of these constituents was evaluated along with their
toxicity to determine the potential impact each may have in the long term on the groundwater.
2.5.7.2 Characterization by Landfill Waste Sampling
Angled Boring Program. 1988-1989
In order to confirm the results of the waste characterization by inventory records, angled borings
were completed to sample soil immediately beneath the waste disposal areas. The angled
borings were completed as an alternative to drilling directly through the waste on the basis of
safety and environmental concerns.
In total, 13 angled borings were installed beneath the waste disposal areas. During the
installation of the borings, shelby tube samples were collected at 5-foot intervals along the axis
of the borehole for chemical analyses. Each 5-foot interval was analyzed for TCL VOCs, BNAs
and Pesticides/Herbicides including PCBs. In addition, samples were analyzed for TAL metals
and cyanide. Two rounds of soil boring samples were collected during the RI field program.
Due to problems identified through the associated QA/QC data review, the data from the first
round of angled boring samples (August 1988) were used for qualitative purposes only. In order
.to generate data which could be used for quantitative purposes, a second round of angled boring
samples was collected during November/December 1989. Not all of the angled borings
completed in the first round were duplicated during the second round of sampling. A total of
six sample borings were completed. The six sample locations were selected based upon their
relatively easy access to the sampling site and because they were found to have the highest
concentrations of Site-specific constituents in the soil samples collected during the first round
of sampling. In addition, sample sites were selected to be representative of all three disposal
areas. The QA/QC review for the second round of data confirmed that the data could be used
for both quantitative and qualitative evaluation of the landfill waste.
Table 2.2 presents a summary of the analytical data for the second round of angled boring
sampling. The analytical data summary presents the range of positive detections for the second
sampling round. A detailed summary and discussion of all of the angled boring analytical data
is presented in the RI.
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TABLE 2.2
SUMMARY OF ANALYTICAL DATA
ANGLED BORING SAMPLES - ROUND 2
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT 92
HARDEMAN COUNTY, TENNESSEE
Compounds
VOCs
Acetone
Benzene
Carbon tetrachloride
Chlorobenzene
Chloroform
CMoromethane
Ethyl benzene
1,1^2-Tetrachloroethane
Tetrachloroethene
Toluene
"denes
BNAs
Acenaphthene
Benzoic acid
Bis(2-ethylhexyl)phthalate
Di-n-butyl phthalate
Di-n-octyl phthalate
Dibenzohuan
Fluorene
Hexachlorobenzene
Hexachlorobutadiene
Hexachlorocydopentadiene
Hexachloroethane
2-Methylnaphthalene
Naphthalene
Pesticides /PCBs
Aldrin
Dieldrin
Endrin
Endrin aldehyde
Heptachlor
Number of
Positive
Detections
11
1
8
4
8
1
6
1
13
17
12
Number of
Samples
Analyzed
45
45
45
45
45
45
45
45
45
45
45
Range of
Positive
Detections
(mgfkg)
157 - 103
N/A
0.805 - 342
1.67 - 6.06
0.765 - 86.7
N/A
0.850 - 10.6
N/A
137 - 16.6
124 - 943
1.45 - 67.8
Arithmetic
Average of
Positive
Detections
(mgfkg)
6.12
0.660
135
352
19D
235
330
0.654
628
19.7
10
1
8
1
3
1
11
16
16
16
5
18
16
45
45
45
45
45
45
45
45
45
45
45
45
45
0520 - 250
N/A
0390 - 13.0
N/A
0.400 - 130
N/A
0.430 - 19.0
130 - 61.0
0390 40.0
0.430 - 1200
150 - 11.0
0.490 - 270
1.40 - 210
1.49
250
233
5.40
0760
US)
475
16.1
10.6
298.
634
104
633
18
19
19
17
12
45
45
45
45
45
150
1.70
1.80
3.60
35.00
- 98.0
- 280
- 640
- 540
. 3000
233
60.9
126
98.8
1050
Page 16
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TABLE 2.2
SUMMARY OF ANALYTICAL DATA
ANGLED BORING SAMPLES ROUND 2
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT 12
HARDEMAN COUNTY, TENNESSEE
Compounds
METALS
Aluminum
Arsenic
Barium
Calcium
Chromium
Iron
Lead
Magnesium
Manganese
Mercury
3tassium
Selenium
Silver
Sodium
Vanadium
Zinc
Number of
Positive
Detections
44
33
36
26
42
44
7
41
41
11
29
1
5
39
37
41
Number of
Samples
Analyzed
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45
Range of
Positive
Detections
(mgfkg)
660 - 9770
1.00 . 112
5.60 - 573
52.7 - 556
2.60 - 173
1580 - 71100
5.10 - 11.2
253 - 825
3.20 - 291
0.120 - 0220
33.7 - 223
N/A
1.10 - 230
50.0 351
5.10 - 36.8
3.10 - .574
Arithmetic
Average of
Positive
Detections
(mglkg)
4530
3.70
20.1
179
777
9850.
7.88
2%.
43.1
0.152
105.
0.650
1.40
136.
14.4
34.1
Note:
N/A - Presentation of a range of detection not applicable because only detected once.
Page 17
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Soil Sampling
sis Program. 1992
A soil sampling and analyses program at the Site was conducted in July/August 1992. The
Landfill Waste Sampling and Data Evaluation Report detailed within Section 2.9.5.1 presents
the results of the 1992 sampling and analysis program. Table 2.3 presents a summary of the
analytical data for this sampling and analyses program.
2.5.8 Contaminant Migration
Migration Pathways
Three potential contaminant migration pathways exist at the Hardeman County Landfill Site.
These are: air, surface water runoff and groundwater migration. Each of these potential
pathways is discussed below.
Migration in Air
Contaminants may be released to the atmosphere from the surface and near-surface soil material
by volatilization or by entrainment of soil-bound contaminants. In addition, some contaminants
may be released to the atmosphere by volatilization at seeps and along Pugh and Clover Creeks
where they discharge. Once released the contaminants may be transported by the wind.
The remedial activities completed by Velsicol in October 1980 which included the construction
of a clay cap over the disposal areas has minimized the volatilization of contaminants from waste
as well as paniculate transport. Therefore, the air migration pathway is not considered a
significant pathway in this area of disposed waste. This conclusion was accepted by TDHE and
USEPA and consequently, air monitoring was not included in the Scope of Work as presented
in the RI Work Plan which was reviewed and approved by TDHE and USEPA. Air migration
could be a potential pathway at the seeps and in Pugh and Clover Creeks due to volatilization.
The air route of exposure was considered as part of the RI and public health evaluation and
found not to represent a significant route of exposure.
Surface Water Runoff
Surface water runoff or overland flow may carry paniculate or dissolved contaminants from
surface soil and/or at surface groundwater discharges. Surface water from the Site drains into
ditches and streams which eventually flow into Pugh Creek. The placement of the cap has
prevented surface water contact with the waste and therefore eliminated any sediment transport
from the Site. While some Site-related contaminants were detected in some surface water and
sediment samples, it is believed that these compounds are the result of past surface water
-------
TABLE 2.3
SUMMARY OF DETECTED COMPOUNDS - SOIL BORING PROGRAM -1992
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT «
HARDEMAN COUNTY, TENNESSEE
Range Average Number of Number of
of Positive Detections of Positive Detections Positive Detections Samples Analyzed
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TABLE 2.3
SUMMARY OF DETECTED COMPOUNDS - SOIL BORING PROGRAM -1992
FEASIBILITY STUDY
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT 92
HARDEMAN COUNTY, TENNESSEE
Range Average Number of Number of
of Pastime Detections o Positive Detections Psitive Detections Samles Analted
Mrtals
, *« V
Heptachlor epcodde
f>0£M£'r""
«X ws**^ 'rfvw*.vC%X
pDDA4'-__ _ _ _ 0.103 ^3.06
flTWJfr^fcj*i'^f*:*^ AHTrfp"fcl-f*' ^ ''^SF^^'yy^y^^ ^ tf'-sf^.sS 4CC!' JCff 4
Endosulfarvbeta "" ' "251-59.7
Page 20
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discharges during the active landfilling operation, the discharge of contaminated groundwater
into Pugh and Clover Creeks, background contamination caused by local agricultural use of
pesticides and herbicides and/or local residential use of pesticides and herbicides and
miscellaneous commercial products.
Therefore, based on the data collected during the RI, and on the specific constituents detected
in the surface water, surface water runoff from the Site has been demonstrated not to be a
significant contaminant pathway for the Hardeman County Landfill. The significance of the
seeps are discussed under the groundwater migration section.
Groundwater Migration
Contaminants have been released to the groundwater beneath the Site by the percolation of
precipitation through the waste disposal areas. Soluble contaminants were dissolved by the
infiltrating waters and have migrated through the unsaturated zone to the water table.
These contaminants have migrated with the groundwater from the source areas (former waste
disposal areas) to the north, east and west. The contaminated groundwater has been shown to
be discharging at isolated seeps at surface water locations and into Pugh and Clover Creeks.
Some Site-related contaminants have been detected in Pugh Creek as a result of this direct
groundwater discharge to the surface (and from seeps/springs).
Therefore, based on the Site characterization completed to date and the extent of groundwater
contamination defined at the Site, groundwater is considered to be the most significant
contaminant pathway, a pathway to be addressed by the groundwater containment solution for
OU#1.
Physical and Chemical Properties of Contaminants
Contaminant mobility depends upon the physical and chemical properties of the contaminants
and the properties of the media in which they are found. Such properties include water
solubility, liquid density, vapor pressure and affinity for organic matter. Partitioning of
contaminants between media is controlled by such mechanisms as sorption, volatilization,
dissolution and bioaccumulation. During the RI, it was determined that VOC contaminants in
the groundwater and soil samples from beneath the Site are relatively soluble, moderately to
highly volatile and moderately to highly mobile. Contaminants detected in the groundwater and
in soil samples from beneath the waste (mainly BNAs and pesticides) have low solubilities and
are relatively immobile.
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2.5.9 Results of Supplementary Field Investigations
2.5.9.1 Landfill Waste Sampling and Data Evaluation Report
A soil sampling and analyses program at the Site was conducted in July/August 1992. The
Landfill Waste Sampling and Data Evaluation Report presents the results of the program
conducted at the Site and describes the tasks required to complete the bench-scale treatability
study for selected technologies for OU #2 at the Site.
Site Investigation
A total of ten boreholes were completed in the landfill area at the Site. Each borehole was
located by means of an electromagnetic survey. At each borehole location one soil sample was
collected for chemical analyses from each of the following depth intervals as measured from the
base of the landfill cap:
1. 0-5 feet;
2. 5-10 feet;
3. 10-20 feet;
4. 20-30 feet;
5. 30-40 feet;
6. 40-50 feet;
7. 50-70 feet;
8. 70-90 feet.
All samples were described and classified according to the Unified Soil Classification
System (USGS) and described in terms of moisture, texture, color, and staining.
Subsurface Conditions
Based on the field observations made during the landfill waste sampling, the landfill mass
consists largely of soil with discrete placements of individual drums, groups of empty
drums, earthen waste products and packaging materials. Where drums were encountered
they were typically empty, and only fragments and solid residues remain.
Summary of Analytical Data
The soil boring program included the collection of 86 investigative samples which were
analyzed for TCL VOCs, TCL BNAs, TCL Pesticides, and TAL metals. Table 2.3
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summarizes data in terms of range, average, and frequency of detection.
The compounds detected and their relative frequency of detection are similar to those
detected in the Round 2 angled boring program summarized previously in Table 2.2.
Non-detect results with elevated detection limits were reported in many of the volatile
organic analyses completed due to the high concentration of compounds in the samples.
Given the large number of non-detects with elevated detection limits, the identification
of a clearly defined pattern of concentrations versus depth was not possible. However,
the data were sufficiently detailed to generally characterize the nature of the disposed
waste and to develop an assessment of the occurrence of the more highly concentrated
organic analytes significant to remediation of the waste.
The data indicate that concentrations were generally highest in the upper 20 feet of each
borehole, corresponding to the waste trenches. BNAs were typically found at the highest
total concentrations at this depth with total concentrations ranging between
400,000 mg/kg (2,4-dichlorophenol) and 100 mg/kg, followed by pesticides with
concentrations ranging between 5,000 mg/kg and 1 mg/kg and VOCs with concentrations
ranging between 1,000 mg/kg and 10 mg/kg. Below the base of the trenches, the
contaminants typically decreased in concentration although remained relatively high from
20 feet to 40 feet below the base of the trenches.
In general, the VOCs that were identified during the waste sampling program are
consistent with those compounds identified to be present in the RI angle borings
(April 1991) and the waste inventory characterization.
The BNAs identified in the soil boring program consisted of polynuclear aromatic
hydrocarbons (PAHs), phthalates, nitrotoluenes, and phenolic compounds. As well,
hexachlorocyclopentadiene, hexachlorobenzene, hexachlorobutadiene and
hexachloroethane which are intermediate products used by Velsicol were also present.
The presence of pesticides in the soil borings was identified to be wide spread with all
but five TCL pesticides being detected in at least one sample. The seven most detected
pesticides included heptachlor, endrin, alpha endosulfan, dieldrin, aldrin, endrin ketone,
and endrin aldehyde.
The metals analyses indicated that metals were present at concentrations consistent with
background levels at the Site.
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2.5.10 Contaminant Distribution and Migration
The visual observations and the analytical data generated from the sampling through the
landfill largely verified the historical and geologic data available for the landfill.
Specifically, the soil boring program shows that the waste is concentrated in discrete
trenches covered by approximately three feet of clayey fill and overlying approximately
50 feet to 70 feet of fine to medium sand of the Claiborne and Wilcox Formations.
Groundwater was encountered approximately 70 feet to 90 feet beneath the ground
surface.
The soil boring program verified that a significant proportion of the wastes were
delivered to the Site in boxes and that their contents are now intimately mixed with the
filled soil. Drums in which some of the waste was contained have largely deteriorated
and their contents have migrated from the drums and containers into the surrounding soil
matrix and the subsurface soil below. The deterioration of the drums is not unexpected,
based on the combined effects of the methods used to dispose of the drums and 20 years
to 30 years of weathering and the corrosive nature of many of the wastes disposed of at
the Site.
The analytical data shows that the concentration of analytes is high within the soil matrix
of the trenches. Below the trenches, the concentration of VOCs, BNAs and pesticides
remain relatively high to approximately 20 feet to 40 feet below the base of the trenches,
below which the concentrations decrease.
Although the waste trenches and underlying soils were found to be contaminated with
relatively high concentrations of VOCs, BNAs and pesticides, the BNAs and pesticides
are not as frequently detected as VOCs.
VOCs are two to three orders of magnitude more soluble in water than most BNAs and
all of the pesticides listed. The partitioning coefficients of VOCs are similarly one to
two orders of magnitude lower than the BNAs and pesticides which indicate that the
VOCs are more mobile than the BNAs or pesticides. However, due to the low organic
carbon content of the sandy Site soils, the partitioning coefficient is probably not as
major a factor in the selective migration of the Site contaminants as is aqueous solubility.
With the exception of 2,4-dichlorophenol and 2,6-dinitrotoluene, BNAs and pesticides,
relative to VOCs, are much less soluble in water. Any migration which has occurred,
has likely been assisted by the presence of the VOCs. For example, acetone, which is
present in the waste at relatively high concentrations can dissolve phthalates and other
polar compounds. Acetone is totally miscible in water; therefore, in the presence of
water, acetone would provide a mechanism for the movement of polar molecules. The
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Page 25
fact that phthalates are the most frequently detected non-VOC in the groundwater,
although at very low concentrations, reinforces this mechanism. The relative significance
of acetone in assisting in the migration of contaminants at the Site was limited by the fact
that the majority of the contaminants, particularly the more frequently detected
contaminants, were not soluble in acetone.
In fact, the majority of commonly detected non-VOC compounds in the waste and
underlying soil are halogenated (e.g., pesticides, hexachlorocyclopentadiene,
hexachlorobenzene). These halogenated non-VOC compounds are themselves more
soluble in halogenated VOCs such as chloroform, carbon tetrachloride, tetrachloroethene
and methylene chloride. However, the lower aqueous solubility of the halogenated VOCs
(0.1 to 0.005 percent) relative to acetone has rendered this mechanism (i.e., dissolution
of the halogenated non-VOC in a halogenated VOC itself dissolved in infiltrating water)
a limited mechanism for the movement of halogenated non-VOCs to the groundwater
table. Therefore, the infrequent detection of pesticides in the groundwater table is likely
due to the relatively lower aqueous solubility of the halogenated VOCs, in comparison
to acetone.
Prior to the cap being placed over the landfill, the mechanism for the movement of the
pesticides and BNAs likely involved their dissolution in the VOCs and the subsequent
dissolution of the VOCs in water percolating through the contaminated soil. Following
the capping of the landfill and the reduction of infiltration of rainwater, the movement
of BNAs and pesticides was further reduced.
2.5.11 Treatability Study
In support of the remedial alternatives evaluation process, treatability studies were
performed on samples of soil and waste collected from below the landfill waste disposal
areas. A total of four treatment technologies were examined in accordance with the FS
Work Plan and included:
i) biotreatability study on soil and waste;
ii) solidification/fixation study on soil and waste;
iii) thermal desorption study on waste; and
iv) incineration study on waste.
In summary, treatability study results clearly indicated that bioremediation is not an effective
treatment option for landfill wastes and soils and that the thermal process options would likely
meet performance goals and objectives. Solidification/fixation was not demonstrated to be
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Page 26
effective, although it was concluded that solidifying/stabilizing agents other than those used in
the study potentially could be effective. Treatability study results are documented in the
Treatability Study Evaluation Report, dated February 1994.
2.6 SUMMARY OF SITE RISKS
2.6.1 Environmental Evaluation Report
General
The Environmental Evaluation Report presents the results of an environmental evaluation study
completed by CRA on behalf of Velsicol in the summer and fall of 1992 at the Site in Hardeman
County, Tennessee. The environmental evaluation study was undertaken as part of the data
collection activities for the OU #2 FS.
Scope of Work
The environmental evaluation included four principal activities as follows:
1. review of existing data and historic studies;
2. bioassay study;
3. gray bat study; and
4. soil sampling at seeps.
The purpose of the above activities was to characterize and evaluate the potential impact of Site
contaminants on the ecology of the area.
Previous Ecological Studies
Numerous habitat assessments and community surveys have been completed historically around
the Site to monitor and identify any environmental impact posed by chemical releases from the
Site. These investigative studies, completed by ERM-Southeast and Dr. Raymond Harbison, are
summarized as follows:
1) July 1980 - June 1983 Comprehensive three-year Monitoring
Program, ERM-Southeast
Stream Water Quality
Stream Sediment
Stream Biology
Terrestrial Survey
-------
Draft Record of Decision
Velsicol/Hardeman County OU#2
Page 27
2) September 1984 Stream Assessment Report, ERM-Southeast
3) February 1985 Environmental Evaluation and Assessment
of Control Measures at the Velsicol Disposal
Site, ERM-Southeast
4) October 1985 Preliminary Hazard Assessment for the
Velsicol Disposal Site at Hardeman County,
Tennessee, Dr. Raymond Harbison
Conclusions from these investigative studies indicated that contaminai ts are reaching the
nearby surface waters of Pugh Creek and Clover Creek, but levels reported do not pose
any environmental impact on the aquatic habitats and communities in Pugh Creek and
Clover Creek or, on resident mammalian communities in the vicinity of the Site.
Bioassay Study
Chronic bioassays were conducted in October 1992 to evaluate the potential impact on
growth and reproduction of aquatic life at and around the Site caused by contaminants
in Pugh Creek which may have migrated from the Site. A total of three water samples
were collected from each of four locations along Pugh Creek (three locations
downgradient of the landfill and one location upgradient of the landfill). Fathead
minnow (Pimephales promelas^ larvae and Ceriodaphnia dubia were introduced to
samples of the Pugh Creek surface water at various dilution factors to determine the
impact of the creek water on survival and on growth/reproduction.
The results of the acute and chronic bioassay tests are summarized in Table 2.4. The
result of the TCL and TAL analyses are summarized in Table 2.5.
Gray Bat Study
The purpose of the gray bat study conducted in July 1992 was to determine if the gray
bat, an endangered species, habitats the area of the landfill. In the event that gray bats
were found to be present, a field study and laboratory program would then be performed
to determine if invertebrate (i.e., may flies, stone flies, mosquitoes, etc.) in Pugh Creek
had been impacted by the contaminant migration from the landfill. The invertebrate
study, if required, would determine if the gray bats have been or could be affected by
the contaminants detected in the surface water, since the invertebrates are the primary
food supply of the gray bat. Based on the findings of this study and a literature review
-------
TABLE 2.4
SUMMARY OF BIOASSAY RESULTS
ENVIRONMENTAL EVALUATION REPORT SUMMARY
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT f 2
HARDEMAN COUNTY, TENNESSEE
CERIOD APHNIA DUBIA
Parameter
Acute
48-Hour LCsod)
Chronic
BIO-1
>100%
BIO-2
>100%
B/O-3
>100%
BIO-4
>100%
NOEC (Survivial) (2)
NOEC (Reproduction)
PTMEPHALES PROMELAS
Parameter
Acute
48-Hour LCso
100%
25%
100% 100% 100%
75% 100% 100%
BJO-1
>100%
BJO-2
>100%
B/O-3
>100%
BIO-4
>100%
Chronic
NOEC (Survivial)
NOEC (Growth)
100%
75%
100%
75%
75%
100%
100%
50%
Notes:
(1) LCgo - Lethal Concentration for 50 percent of the samples.
(2) NOEC-No observable effect concentration.
Page 28
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\BLE2.5
3EK WATER ANALYTICAL DATA
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT *2
HARDEMAN COUNTY, TENNESSEE
Sample Location:
Sample JD:
Laboratory ID:
Date Sampled:
VOCt
carbon tetrachloride
chloroform
melhylene chloride
BNAs
2,4-dInitrophenol
phenol
2,4-dichIorophenol
Metals
.Aluminum
Cadmium
Chromium
Iron
Manganese
Potassium
Zinc
Notes:
BIO-1
W-921020-JO-2000
9206737
October 20,1992
ND(5)
ND(5)
ND(5)
ND(10)
ND(10)
ND(10)
NO (200)
ND(5)
ND(10)
540
52
ND(IOOO)
ND(20)
BIO-2
W-921020-JO-2001
920S738
October 20,1992
350
79.3
ND(50)
ND(10)
ND(10)
82.3
ND(200)
Nt>(5)
ND(10)
1580
680
ND(IOOO)
28
BIO-2
W-921020-JO-2003
9206740
DUP 0/2001
388
90
ND(50)
ND(10)
ND(10)
86.3
NO (200)
ND(5)
ND(10)
1620
681
ND(IOOO)
NO (20)
BlO-3
W-921020-JO-2002
9206739
October 20,1992
83.1
245
NO (5)
ND(10)
NO (10)
295
NO (200)
12
ND(10)
1400
401
ND(IOOO)
NO (20)
BlO-4
W-921020-JO-2004
9206741
October 20,1992
163
40.1
ND(5)
ND(10)
NO (10)
ND(10)
ND(200)
ND(5)
ND(10)
1200
411
ND(IOOO)
ND(20)
(1) All results reported in ng/L.
(2) Pesticides were not detected in any samples at a detection limit of 0.05 mg/L. The detection limit for chlordane was 1.0 mg/L.
ND - Not detected at specified practical quantitation limit (PQL). PQL Is shown In parentheses.
Page 29
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TABLE 2.5
SUMMARY OF PUGH CREEK WATER ANALYTICAL,DATA
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT «2
HARDEMAN COUNTY, TENNESSEE
Sample Location:
Sample ID:
Laboratory ID:
Date Sampled:
VOd
carbon tetrachloride
chloroform
methylene chloride
BNAs
2,4-dinitrophenol
phenol
2,4-dichlorophenol
Metals
Aluminum
Cadmium
Chromium
Iron
Manganese
Potassium
Zinc
Notes:
BIO-1
W-921022-JO-2006
9206794
October 22,1992
ND(5)
ND(5)
ND(5)
NO (10)
103
NO (10)
ND(200)
ND(5)
ND(10)
490
54
ND(IOOO)
NO (20)
BJO-2
W-921022-JO-2007
9206793
October12,1991
386
923
ND(50)
ND(10)
ND(10)
87.9
ND(200)
ND(5)
ND(10)
1580
675
ND(IOOO)
ND(20)
BJO-2
W-921022-JO-2008
9206792
DUP 0/2007
337
80
ND(50)
ND(10)
ND(10)
86.3
ND(200)
ND(5)
ND(10)
1520
616
ND(IOOO)
ND(20)
B/0-3
W-92I022-/O-2009
9206791
October 22,1992
87.5
27.7
ND(5)
ND(10)
ND(10)
26.8
ND(200)
ND(5)
ND(10)
1460
462
ND(IOOO)
NO (20)
BIO-4
W-921022-JO-2010
9206798
October 22,1992
167
623
6.0
ND(10)
11.2
ND(10)
NO (200)
ND(5)
163
2560J
498
ND (1000)
ND(20)
(1) All results reported in ug/L.
(2) Pesticides were not detected in any samples at a detection limit of 0.05 mg/L. The detection limit for chlordane was 1.0 mg/L.
ND Not detected at specified practical quantitation limit (PQL). PQL is shown in parentheses.
;-Estimated Value.
-------
TABLE 2.5
SUMMARY OF PUGH CREEK WATER ANALYTICAL DATA
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT f 2
HARDEMAN COUNTY, TENNESSEE
Sample Locations
Sample ID:
Laboratory ID:
Date Sampled:
VOCs
carbon tetrachloride
chloroform
tnethylene chloride
2,4-dinitrophenol
phenol
2,4-dlchlorophenol
Metals
Aluminum
Cadmium
Chromium
Iron
Manganese
Potassium
Zinc
Notes:
B10-1
W-921023-JO-2013
9206803
October 23,1992
ND(5)
ND(5)
ND(5)
ND(10)
ND(10)
NO (10)
250
ND(5)
ND(10)
570
62
ND (1000)
ND(20)
BJO-2
W-921023-JO-2014
9206802
October 23f 1992
376
107
ND(50)
44.8
ND(10)
ND(10)
ND(200)
ND(5)
10
1900
712
1030
ND(20)
B/O-3
W-921023-JO-2015
9206801
October 23,1992
98.6
32.1
ND(50)
22.1
ND(10)
ND(10)
ND(200)
ND(5)
ND(10)
1880
542
ND(IOOO)
ND(20)
BJO-3
W-921023-JO-2016
9206800
DUP 0/2015
972
33.0
ND(5)
27.0
ND(10)
ND(10)
ND(200)
11
100
2160
502
ND(IOOO)
ND(20)
BIO-4
W-921023-JO-2017
9206805
October 23,1992
157
48.1
6.2
ND(10)
ND(10)
ND(10)
370
8
109
1960
345
ND(IOOO)
ND(20)
(1) All results reported in ug/L.
(2) Pesticides were not detected in any samples at a detection limit of 0.05 mg/L. The detection limit for chlordane was 1.0 mg/L.
ND Not detected at specified practical quantitation limit (PQL). PQL is shown in parentheses.
Page 31
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Draft Record of Decision
Velsicol/Hardeman County OU#2
Page 32
it was concluded that the Site does not present a suitable habitat for the gray bat and
therefore does not pose any ecological impact to the gray bat. Based on this conclusion
it was not necessary to perform the previously mentioned study on the invertebrate food
sources for the gray bat.
Soil Sampling at Seeps
The purpose of soil sampling at the seeps in August 1992 was to determine if the
Site-specific constituents were present within soil at the seeps and to evaluate the
environmental risk, if any, at the seep locations caused by the soil contamination. Based
on the detected organic constituents in the soil samples there is no discernible correlation
between the water quality in the groundwater and seeps, and the detected constituents in
the soil. Table 2.6 presents a summary of the detected organic compounds within seep
soil samples. Table 2.7 presents a summary of the detected metal compounds within
seep samples. An ecological evaluation of seep data concludes that seeps would not
significantly impact the surface water quality of Pugh Creek and Clover Creek.
Environmental Evaluation Report Conclusions
The information collected as part of the Environmental Evaluation Report has
supplemented existing information and verified the conclusions presented in previous
ERM reports, the RI Report and the original FS Report concerning the impact of the
landfill on the local ecology. The following conclusions were presented:
Stream Water Quality
Organic compounds detected in the streams are present at levels which do not
pose any risk to aquatic or terrestrial life.
Stream Sediment
Levels of organic compounds detected in the sediment have attenuated since the
monitoring program conducted by ERM; indicating that placement of the cap had
improved stream sediment quality. Further, samples for which there were
detections of organic compounds were few and similar in proportion to samples
collected in upstream locations. The latter suggested that some detection were
artifacts of sampling or analysis, or were from other sources.
Stream Biology
Presence of organic compounds in benthic organisms has indicated that there are
no consistent trends in concentration and that the most recent data are showing
no detectable levels. Bioassays with bluegill fish indicated no acute toxicity.
-------
TABEE 2.6
SUMMARY OF DETECTED ORGANIC COMPOUNDS IN SEEP SOIL SAMPLES
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT tt
HARDEMAN COUNTY, TENNESSEE
Borehole #:
Sample ID:
Laboratory ID:
Sample Depth (ft):
VOC«
carbon tetrachloride
toluene
Seep 3
S-920819-CA-09A
9205095
0-2
ND (0.625)
ND (0.625)
Seep 3
S-920819-CA-09B
9205096
4.5-5.5
ND (0.625)
ND (0.625)
Seep 5
S-920818-CA-01A
9205069
0-2
1.15
4.12
Seep?
S-920818-CA-03A
9205073
0-1.5
ND (0.625)
ND (0.625)
Seep 8
S-920818-CA-04A
9205075
0-2
ND (0.625)
ND (0.625)
Seep 9
S-920819-CA-07A
9205091
0-2
ND (0.625)
ND (0.625)
bls(2-chlorolsopropyl)ether ND(033)
bis(2-ethylhexyl)phthalate ND(033)
dinitrotoluene, 2,6- 0.908
Peatiddes
DDT,4,4'- ND(0.05)
Endrin ND(0.05)
ND(033)
ND(033)
0.880
ND(0.05)
ND(0.05)
ND(033)
ND(033)
ND (033)
6.65
1.15
ND(033)
ND(033)
ND(0.05)
ND(0.05)
ND(033)
2.08
ND(033)
ND(0.05)
ND(0.05)
ND(033)
ND(033)
ND(033)
ND(0.05)
724
Note:
All concentrations are reported In mg/kg.
ND - Not detected at specified practical quantitation limit shown in parentheses.
Page 33
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TABLE 2.7
SUMMARY OF DETECTED METAL COMPOUNDS IN SEEP SOIL SAMPLES
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT #2
HARDEMAN COUNTY, TENNESSEE
Borehole i:
Sample ID:
Laboratory ID:
Sample Depth (ft):
Background Samples (1)
Range of Average of
Positive Positive
Detections Detections
Aluminum
Arsenic
Barium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Nickel
Potassium
Vanadium
Zinc
2750-21900
3.8-14.0
46-102
1690-2100
3-17
6-7
3-16
4190-28000
6-19
1780-2010
96-188
4-19
162-1360
7-36
8.7-59
15308
9.4
73
1895
13
6
12
20948
15
1918
161
14
281
28
38
Step I
S-920819-CA-08A
9205093
0-2
Seepl
S-920819-CA-08B
9205094
35-4
Seep 3
S-920819-CA-09A
9205095
0-2
Seep 3
S'920819-CA-IOA
9205097
DUPof09A
Seep 3
S-920819-CA-09B
9205096
4.5-5.5
SeepS
S-920818-CA-01A
9205069
0-2
634
ND(15)
ND(29)
ND(730)
2.7
ND(7.3)
ND(2.9)
539J
ND(7.3)
ND(730)
13.8
ND(5.9)
ND(ISOUJ)
ND(7J)
ND(2.9)
10500
1.5
70.2
880
15.8
ND(6.5)
6
7540J
6
1030
20.6
7
7.85J
19
29.6
7670
ND(1J)
105
ND(730)
8.4
ND(7.3)
ND(2.9)
5700J
11
ND(730)
95.9
ND(5.9)
407J
10
18.8
7910
22
79.1
ND (560)
7.8
ND(5.6)
ND(22)
6480J
10
506
79.9
ND(4.5)
373J
11
18.8
10800
1.5
159
ND(750)
12.9
ND(7.5)
ND(3.0)
3950J
6
ND(750)
27.8
ND(5.9)
473J
15
18.5
9850
8.8
133
ND(660)
11.6
8
ND(2.6)
15300J
ND(6.6)
889
1860
7
619J
16
26.2
Note:
All concentrations are reported in mg/kg.
(1) Background soil sample results as reported in RI (April 1991).
ND - Not detected at specified practical quantitation limit shown in parentheses.
J - Estimated value.
-------
Borehole f:
Sample ID:
Laboratory ID:
Sample Depth (ft):
TABLE 2.7
SUMMARY OF DETECTED METAL COMPOUNDS IN SEEP SOIL SAMPLES
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT f2
HARDEMAN COUNTY, TENNESSEE
Seep 5
S-920818-CA-01B
9205070
4-5
Seep 6
S-9208J8-CA-02A
9205071
0-2
Seep 6
S-920818-CA-02B
9205072
43-53
Seep?
S-920B18-CA-03A
9205073
0-13
Seep 7
S-920818-CA-03B
9205074
5-6
Note:
All concentrations are reported in mg/kg.
(1) Background soil sample results as reported in RI (April 1991).
ND - Not detected at specified practical quantitation limit shown in parentheses.
) - Estimated value.
Seep 8
S-920818-CA-04A
9205075
0-2
Aluminum
Arsenic
Barium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Nickel
Potassium
Vanadium
Zinc
2750-21900
3.8-14.0
46-102
1690-2100
3-17
6-7
3-16
4190-28000
6-19
1780-2010
96-188
4-19
162-1360
7-36
8.7-59
15308
9.4
73
1895
13
6
12
20948
15
1918
161
14
281
28
38
2640
ND(U)
253
ND(620)
16.8
ND (62)
ND(25)
8610)
ND(6J2)
ND(620)
107
ND(5.0)
168)
9
8.0
1880
ND(1.5)
ND(30)
ND(750)
4.7
ND(7.5)
ND(3.0)
1070)
8
ND(750)
35.7
ND(5.9)
362)
ND(7.5)
9.4
7050
13
69.4
ND(620)
11.2
ND(6.2)
ND(2J)
5960)
ND(6.2)
513
104
5
513)
18
23.8
7580
5.9
44.2
ND(550)
11.8
ND(5.5)
ND(2.2)
10300)
7
601
139
ND(4.4)
711)
14
18.0
12100
6.6
41.4
ND(590)
23.6
ND(5.9)
5
21100)
10
551
171
8
504)
21
22.8
5740
1.7
59.0
ND(690)
7.3
ND(6.9)
ND(2.8)
6610)
ND(6.9)
562
398
ND(5.6)
352)
9
16.6
Page 35
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TABLE 2.7
SUMMARY OF DETECTED METAL COMPOUNDS IN SEEP SOIL SAMPLES
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT #2
HARDEMAN COUNTY, TENNESSEE
Borehole it
Sample ID:
Laboratory ID:
Sample Depth (ft):
Aluminum
Arsenic
Barium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Potassium
Vanadium
Zinc
Background Sample* (1)
Range of
Positive
Detection*
2750-21900
3.8-14.0
46-102
1690-2100
3-17
6-7
3-16
4190-28000
6-19
1780-2010
96-188
0.11-0.12
4-19
162-1360
7-36
8.7-59
Average of
Positive
Detections
15308
9.4
73
1895
13
6
12
20948
15
1918
161
0.12
14
281
28
38
Seep 8
S-920818-CA-04B
9205076
5-6
4270
13
26.4
ND(630)
6.4
ND(63)
ND(25)
5590)
ND(630)
112
034
ND(5.0)
276)
8
9.5
Seep 9
S-920819-CA-07A
9205091
0-2
10900
4.3
67.0
ND(550)
11.5
ND(5.5)
ND(2.2)
11840)
8
1080
324
ND(0.11)
7
1040)
18
33.6
Seep 9
S-920819-CA-07B
9205092
5-6
12800
6.4
74.0
ND(570)
15.8
6
19600)
11
1280
1270
ND(O.ll)
10
807)
27
30.7
Note:
All concentrations are reported in mg/kg.
(1) Background soil sample results as reported in RI (April 1991).
ND Not detected at specified practical quantitation limit shown in parentheses.
) - Estimated value.
36
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Draft Record of Decision
Velsicol/Hardeman County OU#2
Page 37
Chronic toxicity was not monitored.
Terrestrial Survey
The terrestrial survey has indicated that animals whose habitat included the
exposed landfill (i.e., prior to capping) may have accumulated chemicals in their
vital organs, although levels were well below action levels set by the USEPA.
Direct contact with the buried waste has been eliminated by capping the Site;
therefore, current conditions should be improved.
Stream Assessment
An assessment which compared overall stream habitat for fish and invertebrates,
population characteristics, water quality and organic compounds in fish tissues to
two control streams showed that Pugh Creek had not been detrimentally impacted
by the landfill.
Preliminary Hazard Assessment
A preliminary hazard assessment based on detected limits of carbon tetrachloride
in Pugh Creek indicated that concentrations were below acute aquatic criteria.
Due to the low level of bioaccumulation of carbon tetrachloride, it was also
concluded that it did not pose a chronic risk.
Seep Water Quality
Analysis of seep water indicated that it had no detrimental impact on any aquatic
life or terrestrial life.
Bioassay Study
The bioassay has indicated that the NOEC for survival (acute toxicity) of the test
species exposed to creek water was 100 percent. Chronic toxicity, as measured
by reproduction or growth, was found to be marginally impacted; however, a
bioassay test with a sample upstream of the Site showed a more severe to similar
effect on comparison to downstream samples. Concentrations of organic
compounds were below USEPA aquatic criteria and are not contributing to the
toxic impact. Natural hardness and alkalinity in combination with high heavy
metal (cadmium, chromium) concentrations were identified as potential
contributors to the chronic toxicities. Data collected to date have not associated
the metals (cadmium and chromium) with the Site. Identification of cadmium at
background well locations (GM-4) and the sporadic detections of both chromium
and cadmium during the RI sampling program support this conclusion.
Gray Bats
No endangered gray bats were found in the area. This was expected in light of
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Draft Record of Decision
Velsicol/Hardeman County OU#2
Page 38
the distance of the Site from the nearest known cave available for the gray bat
habitat.
Soil Sampling at Seeps
Sampling indicated no discernible correlation in previous seep sampling and
sporadic low levels of some organic compounds, which were sufficiently low to
be of no concern. The risk to burrowing animals which could potentially be most
impacted is not considered significant due to the high water table.
In summary, the Environmental Evaluation Report concluded that the Site is presently
not detrimentally impacting the local ecology and that any potential impact has been
limited by the placement of the cap. In the future, the environmental impact will be
further reduced by the implementation of the groundwater remediation program.
2.6.2 Human Health Evaluation
This section summarizes the findings of the Human Health Evaluation as presented in the
RI Report.
Because of the tune elapsed since the chemicals first migrated from the Site, the
comparatively high permeability of the soils, the high affinity of many of the constituents
found in the waste to soil (i.e., limited mobility), the past remedial activities by Velsicol
including placement of a low permeability clay cap, as well as the pattern of groundwater
flow over time, chemicals which have not migrated to off-Site wells (particularly GM-5)
at this time are not expected to migrate significant distances in the future or possibly not
at all.
The following potentially complete human exposure pathways were evaluated for
potential exposure point concentrations, estimated daily intake and potential risk and/or
hazard:
the use of contaminated groundwater for household use;
recreational fishing and fish consumption from Clover Creek;
hunting in the area and consumption of meat from game which have drunk from
Pugh or Clover Creeks; and
occasional skin contact while fishing or wading.
Calculations based upon residential use of current Site-contaminated groundwater at
several locations revealed total additional lifetime cancer risk levels in exceedence of the
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Draft Record of Decision
Velsicol/Hardeman County OU#2
Page 39
risk levels deemed acceptable by USEPA.
Future groundwater concentrations of carbon tetrachloride and chloroform were predicted
based upon groundwater flow models. Values predicted for the years 1995, 2000, and
2010 in wells GM-5, 13, 7 and GMP-5 were evaluated for potential total incremental
lifetime cancer risk and non-carcinogenic hazard using the same household exposure or
recreation scenarios as were used for evaluation of present conditions. The estimated
risks and hazards resulting from such exposure were in excess of acceptable levels, even
after an additional 20 years of plume migration in the absence of further remediation.
Calculations assuming recreational exposure (recreational fishing and fish consumption)
to Site-related contaminants present in surface water demonstrate that the reported
concentrations do not present a concern for fish consumption or for occasional skin
contact.
Future concentrations of carbon tetrachloride and chloroform in Clover Creek are
predicted to peak in the year 1994. At the estimated peak flux to the creek, estimated
potential risks are well below the target range of 1E-04 to 1E-06 estimated total
incremental lifetime risk of cancer. The estimated total hazard level is also well below
a level of concern when applying the more conservative conditions of 3Q20 creek flow
where the estimated groundwater flux from the plume area makes up approximately
one-half of the total creek flow.
Game animals could potentially be exposed to Site-related compounds through the
consumption of contaminated downgradient surface water. However, these would be
metabolized and/or excreted from animals or birds. There would be no bioconcentration,
and in fact, there would be no tissue retention expected from ingestion by mammals or
birds of the trace levels of these chemicals reported in the creeks. The exposure via this
exposure pathway would be de minimis and the potential cancer risk or non-carcinogenic
hazard index was not evaluated.
2.6.3 Soil Action Levels for Groundwater Protection
The Summers Model in conjunction with the Hydrologic Evaluation of Landfill
Performance (HELP) Model were utilized to determine whether the existing clay cap
could meet the specific remedial action objective of preventing further degradation of the
groundwater beneath and downgradient of the waste disposal areas. This evaluation was
completed using Site-specific chemical constituents found within the waste.
The Summers Model was used to calculate maximum allowable Site-specific contaminant
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concentrations within leachate which would not result in exceedances of groundwater
concentrations of the same Site-specific contaminants above water quality goals, in this
case the Maximum Contaminant Level (MCL). For constituents where MCLs are not
established, Drinking Water Equivalent Levels (DWEL) were selected/calculated utilizing
known Reference Dose (RfD) values for the respective constituents.
Once the maximum allowable contaminant concentration in the leachate was determined,
the maximum allowable contaminant concentration in the waste and soil was calculated.
This calculated value represents the waste and soil cleanup level which must be obtained
in order to be protective of the groundwater as specified within the remedial action
objective.
The following table demonstrates that under the existing clay cap infiltration scenario
average, contaminant concentrations within the waste and impacted soil beneath the waste
exceed Soil Action Levels which must be met to be protective of groundwater.
Contaminant
Average Contaminant Concentrations
Waste (1) Soil (2)
(mg/kg) (mgfkg)
Soil Action Levels
Waste (1) Soil (2)
(mg/kg) (mg/kg)
Acetone
Carbon Tetrachloride
Chloroform
Methylene Chloride
Tetrachloroethene
0.0
"216.1
"78.7
'100.4
*9.6
"15.5
*1.8
"0.2
*1.6
NA
1.1205
0.8031
0.8031
5.9389
0.5428
1.0543
0.1919
0.0391
0.6676
2,4-Dichlorophenol
Hexachlorobenzene
"18,302.8
"193.9
"68.5
11.6
99.5202
113.1280
29.1442
NA
Endrin
Endrin Aldehyde
Endrin Ketone
55.1
2.9
83.2
*23.5
"18.6
*6.4
NA 18.5302
NA 0.3151
NA 2.0968
Note:
Exceedance of Soil Action Levels
Values taken from FS-Appendix C, Table C.8.
Values taken from FS-Appendix C, Table C.5.
Not Applicable, no exceedance of soil action levels.
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2.6.4 Soil Action Levels for Direct Contact
All three disposal areas were covered with a 3-foot low permeability (hydraulic
conductivity of 1.0 x 10~7) clay cover in 1980 which effectively eliminated any potential
for human exposure via direct contact with the landfilled waste or soils impacted by the
waste disposal. Chemical specific target concentrations were developed based on
reference doses and cancer slope factors, Tables 2.8 and 2.9. Human exposure via direct
contact or ingestion of waste and soils would be a pathway of concern for any remedial
action requiring excavation through the clay cap or through any maintenance of the clay
cap in problem areas cause by major erosion.
2.7 DESCRIPTION OF ALTERNATIVES
2.7.1 Alternative A-l - No Further Action
2.7.1.1 Description
Under this alternative no further remedial action beyond what has already been
implemented (i.e., the clay cap constructed in 1980 and the selected OU #1 remedy)
would take place.
This alternative employs the processes of natural attenuation for the reduction of
contaminants in the unsaturated soil. Natural attenuation is the tendency of contaminant
concentrations to decrease through physical, chemical and biological processes in the
natural environment. Surface water leaching through the waste material would be
minimal due to the presence of the existing clay cap. Contaminated groundwater would
be contained and treated on Site as part of the OU #1 remedy. A long-term monitoring
and maintenance program would be implemented as part of this alternative to maintain
the integrity of the existing clay cap over the waste disposal areas and to monitor the
performance of the OU #1 groundwater treatment system and groundwater beneath the
Site. Specific features of the OU #1 remedy include the following:
i) Five extraction wells and pumping systems will be installed to achieve an
effective hydraulic capture of contaminants in on-Site groundwater at the north
end of the landfill. These wells must collectively recover approximately
160 gpm to achieve hydraulic containment. Piezometers may be installed
within the projected containment area to demonstrate capture.
ii) Four extraction wells and pumping systems will be installed to restore the
contaminated off-Site groundwater beyond the landfill to within acceptable
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TABLE 2.8
CHEMICAL-SPEdHC TARGET LEVELS
Target concentrations presented within Table A.1 are based on chemical-
specific reference doses/ and are calculated as follows:
RfDoral * BW * AT
Target Cone
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TABLE 2.9
POTENTIAL CHEMICAL-SPECIFIC GUIDELINES (TO BE CONSIDERED)
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT #2
HARDEMAN COUNTY, TENNESSEE
Compound
Oral
Reference Dose
(mg/kg-day)
Oral Cancer
Slope Factor
(l/(mg/kg~day))
Target Concentration
Dermal Based on
Abs. Reference Dosem
(%/100) (mg/kg)
Target Concentration Based
on Cancer Slope factor
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TABLE 2.9
POTENTIAL CHEMICAL-SPECIFIC GUIDELINES fTO BE CONSIDERED)
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT #2
HARDEMAN COUNTY, TENNESSEE
Compound
aldrin
4,4'-DDT
4,4'-DDE
4,4;-DDD
dieldrin
methoxychlor
endosulfan sulfate
endosulfan I
endrin aldehyde -
endrin ketonec)
heptachlor
heptachlor epoxide
Oral
Reference Dose
(mg/kg-day)
5.00xl(H
NA
NA
5.00 x 10-5
5.00 xlO"3
NA
0.006
3.00 xHH
3.00 xl(H
5.00x10-*
130xlO-5
Oral Cancer
Slope Factor
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drinking water standards by removing groundwater from the areas of peak
contaminant concentration. It is estimated that these extraction wells will collectively
have a pumping rate of 310 gpm.
iii) Groundwater from all extraction wells will be pumped via a forcemain system
to the treatment plant.
iv) Contaminated groundwater will be treated in the treatment plant using a system
designed to consist of air stripping and final carbon adsorption treatment for
off gas treatment and final groundwater carbon polishing prior to discharge.
v) Treated water will be discharged to Pugh Creek in compliance with NPDES
requirements via a forcemain piping system.
vi) Groundwater monitoring will be conducted to determine the effectiveness of
the groundwater extraction and verify that groundwater remediation goals of
Record of Decision are reached for the off-Site groundwater.
vii) Deed restrictions, signs and institutional controls will be established to identify
the presence, quantity and nature of wastes in the disposal area and
groundwater and limit uses of both until remediations are complete.
viii) The groundwater treatment system and the disposal areas' cover will be
maintained. Maintenance of the disposal areas will include:
a) periodic inspection of the disposal areas' surface including
slopes;
b) periodic inspection of the monitoring well network and property
fence;
c) periodic mowing of the vegetation over the disposal areas'
cover;
d) the application of fertilizer at a specified frequency;
e) re-establishment of vegetation over distressed areas;
f) periodic repair of areas eroded by surface water runoff;
g) maintenance of the property fence and signs; and
h) control of burrowing animals.
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2.7.1.2 Assessment
Overall Protection of Human Health and the Environment
The primary threat to human health according to the reports detailed within Section 2.6.2 is
the ingestion of contaminated groundwater by the residents of the area. All residents are
supplied potable water by the Town of Toone there is no risk to the local residents. Contact
with surficial soils (clay cap) and surface water within the area of the landfill pose no threat
to human health since the Site has been effectively capped. Groundwater contained on Site
and downgradient of Site will be treated to regulatory levels under the OU #1 remedy and
then discharged to the environment. Therefore, the "No Further Action" alternative is
protective of human health. The groundwater beneath the waste disposal areas will still be
degraded, therefore this alternative is not completely protective of the environment.
Compliance with ARARs
The aquifer below the site is potentially a drinking water supply, therefore Federal Drinking
Water regulations may be relevant or appropriate. However, installation of the OU #1
remedy in conjunction with alternate water supply provided to local residents nullifies the
impact. However, in the context of OU #2, farther degradation of the groundwater will
continue under this alternative in that the relevant and appropriate MCLs will be exceeded at
the water table below the Site and at the downgradient Site boundary. As a result, this
alternative is not in compliance with ARARs.
Long-Term Effectiveness and Permanence
Implementation of this alternative would result in no further remedial action being taken,
hence, the magnitude of contaminated waste and soil would remain the same within the
landfill. Contaminant concentrations are expected to decrease over time due to natural
attenuation and dispersion processes.
Reduction of Toxicity. Mobility and Volume
The existing landfill cap by itself provides no further reduction in toxicity or volume of
waste and contaminated soil as demonstrated by the Summers Model results presented within
Appendix C. The existing clay cap reduces the surface water infiltration by up to 98 percent
resulting in a decrease of contaminant mobility. This reduction in infiltration is not sufficient
to reduce the mobility of contaminants migrating to the groundwater to limit concentrations
below MCLs (Section 2.6.3). The remaining waste and contaminated soil will still remain in
a volume and toxicity to pose a threat to human health if exposed at surface.
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Short-Term Effectiveness
There would be no additional risks to the community or the environment as a result of the
implementation of this alternative in the short term.
Implementability
Since no further action beyond the OU #1 remedy would be undertaken, this alternative is
considered readily implementable.
Cost
There are no construction costs associated with this alternative. Total present worth
Operation and Maintenance (O & M) costs amount to $529,100.
2.7.2 Alternative A-2 - In Situ Soil Vapor Extraction
2.7.2.1 Description
In situ soil vapor extraction (ISVE) is a technique used to remove volatile organic
compounds (VOCs) from the vadose zone. Removal of semi-volatiles is very limited.
This technology includes the installation of withdrawal wells within areas of soil
contamination and air injection wells at the periphery of the contaminated soil zone.
Withdrawing air from the withdrawal wells and injecting air at the injection wells establishes
an airflow from the periphery to contaminated areas. The air which moves through the soil,
entrains vapors evolved from liquid or aqueous phase VOCs and is brought above ground
level through the withdrawal wells. The VOC vapors are then treated prior to releasing to
the atmosphere. Over 100 extraction/ injection wells, several distribution centers and a
vapor treatment unit would be required for a period of 1 - 7 years to substantially decrease
the levels of VOCs within the vadose zone. To monitor progress, soil gas probes would be
installed throughout the Site and sampling points would be established throughout the
treatment train. Maintenance of the existing cap would consist of minor repairs to correct
damage due to vehicular traffic, erosion, settling or animal damage.
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2.7.2.2 Assessment
Overall Protection of Human Health and the Environment
The health threat from contaminated groundwater would be mitigated by the OU #1 remedy.
Potential exposure to Site soils that pose a potential health risk is eliminated by the presence
of the existing cap. ISVE would further aid the OU #1 remedy by removing several VOCs
from the vadose zone before those VOCs have the opportunity of reaching the water table.
ISVE would not remove SVOCs and pesticides from the waste and contaminated soil as
outlined within the paragraph "Long-Term Effectiveness and Permanence". Contaminant
concentrations unaffected by ISVE would (according to the Summers Model), continue to
contribute to further degradation of the groundwater. Therefore, this alternative fails to
prevent further degradation of the groundwater below the Site and therefore is not completely
protective of the environment.
Compliance with
The results of vadose zone modeling has indicated that the present clay cap does not
sufficiently reduce surface water infiltration to prevent degradation of the groundwater
beneath the Site. ISVE would not remove those SVOCs and pesticides identified in the
paragraph "Long-Term Effectiveness and Permanence" within this Section. SVOCs and
pesticides would continue to be a source of contamination to the groundwater based on the
results presented within Section 2.6.3. As such, the results of implementing this alternative
would contravene the relevant and appropriate requirements of the Safe Drinking Water Act
regulations and as such, is not in compliance with ARARs.
Long-Term Effectiveness and Permanence
The high efficiency of ISVE to remove VOCs is well documented within the USEPA
Engineering Bulletin "In Situ Soil Vapor Extraction Treatment", EPA/540/2-91/006 dated
May 1991.
The efficiency of ISVE to remove VOCs based on this Engineering Bulletin could be greater
than 99 percent (dependent on Site conditions). VOC removal at the Hardeman County
Landfill Site utilizing ISVE is therefore not anticipated to pose a problem.
The efficiency of ISVE to remove SVOCs and pesticides is very low, if not non-existent.
The Engineering Bulletin states "It would be difficult to remove soil contaminants with low
vapor pressures and/or high solubilities from a site. The lower limit of vapor pressure for
effective removal of a compound is 1 mm Hg." Based on the previous statements, the
following Site compounds are not expected to be influenced by ISVE as their vapor pressures
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are below 1 mm Hg:
2,4-dichlorophenol - 4,4-DDT
di-n-butyl phthalate - dieldrin
fluorene - endosulfan, alpha
hexachlorobenzene - endrin
hexachlorocyclopentadiene - endrin aldehyde
2-methylnaphthalene - endrin ketone
naphthalene - heptachlor
aldrin
Lack of ISVE efficiency for SVOC and pesticide removal can also be presented in terms of
Henry's coefficients. A contaminant mass removal rate equation based upon Henry's
coefficients is presented within an article entitled "Appropriate Criteria for Soil Vapor
Extraction System Design" by Walter Weinig presented within the 1994 Federal
Environmental Restoration HI Conference Proceedings, Hazardous Materials Control
Research Institute, Rockville, Maryland (pages 1247-1256). In this article, the maximum
rate of contaminant mass removal from a unit volume of soil can be calculated. Using this
equation indicates that removal of SVOCs and pesticides from the vadose zone to soil action
levels (determined through vadose zone modeling presented in Section 2.6.3) would not take
place utilizing ISVE.
Reduction of Toxicity. Mobility and Volume
ISVE may reduce the toxicity, mobility and volume of some of the VOCs that are within the
vadose zone although over a potentially long time-frame. Installation of the extraction and
injection wells may also increase mobility by permitting greater surface water infiltration
through the punctures in the existing cap and by providing a high permeability conduit in
gravel surrounding the wells from the waste to the lower levels of the vadose zone. The
toxicity, mobility and volume of SVOCs and pesticides would not be influenced by ISVE.
The SVOCs and pesticides within the waste and contaminated soil would still pose a potential
threat to human health if exposed.
Short-Term Effectiveness
Short-term impacts to human health and the environment due to air emissions from the
incineration of extracted soil gas and due to ground invasive activities (during drilling) are
expected as a result of the implementation of this alternative. Installation of ISVE
extraction/injection wells would likely require workers to don respiratory protective gear.
Air emissions that come about as a result of these ground invasive activities would need to be
controlled and monitored for throughout the duration of construction activities. Short-term
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effectiveness of the existing cap as a barrier to infiltration would be reduced by the many
well holes that are required. Pilot scale tests would need to be conducted to determine the
in situ effectiveness of the ISVE system.
Generally treatment of this recovered vapor falls into two classes: recovery of vapors on
Site with disposal of condensed vapors off Site or destruction of vapors on Site. In the case
of recovering the vapors in a liquid form for off-Site disposal the nearest facility that could
accept halogenated solvents for destruction is located approximately 150 miles away.
On-Site destruction of halogenated solvents without the production of residuals requiring
further treatment can only be accomplished through incineration.
The potential for accidents when transporting/handling treatment residuals (i.e., concentrated
organics) off Site and when transporting/handling caustic chemicals (for incinerator scrubber)
required for treatment on Site is further amplified by the length of time required for any
ISVE alternative.
The length of time (greater than 40,000 years) required to remove SVOCs and pesticides
indicates that utilization of ISVE for their removal is not an effective course of action.
Based on the article presented in Long-Tenn Effectiveness and Permanence, removal of
chloroform, carbon tetrachloride, methylene chloride and tetrachloroethane to soil action
levels is anticipated to take at least 1 to 7 years. The remaining VOCs would require up to
26 years to reach soil action levels. The length of time required to remove these remaining
VOCs indicates that ISVE is not an effective course of action.
Other studies have demonstrated that removal times for VOCs may in fact be much longer,
by factors of two to five or more. These studies indicate that whereas the above equation
assumes equilibrium transfer of contaminants to the vapor phase, hi fact the transfer is
non-equilibrium, and that there is a long tailing behavior which hampers removal. Where
the soil is heterogeneous (such as the landfilled waste) removal from non-permeable zones
may never occur.
Implementability
Removing VOCs from the vadose zone utilizing ISVE is technically feasible based upon the
existing sandy stratigraphy of the area and successful past performances of the ISVE system
at other Sites. However ISVE has never been implemented previously to the depths
proposed for this Site and may pose a significant obstacle to successful removal of the VOCs
even in the vadose zone. The remediation of the waste utilizing ISVE would be technically
difficult if not impossible due to the presence of containerized waste and debris and frequent
zones of silty materials. It is expected that some removal of VOCs from within the waste
may occur, but only in permeable zones directly connecting with an extraction well. There
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is also a risk to human health inherent with installing the required ISVE injection/extraction
wells. Additional remedial actions such as upgrading the existing cap or removing waste
soils would be difficult due to the expanse of injection/extraction wells and distribution
centers over the landfill. The provision of roadways to access each well would also hinder
future additional remedial actions.
Soil vapor probes and sampling ports would provide a means to monitor the effectiveness of
this remedy. The decision to select the appropriate treatment for recovered vapor would be
based upon the results of the pilot studies. Securing a portable incinerator for vapor
destruction is contingent upon the availability of the necessary equipment and specialists,
both of which are not readily available within Hardeman County. For a project of this
duration, building a dedicated incineration system on Site would be the most effective course
of action. Large amounts of water produced by the ISVE process would require treatment
subsequent to discharge off Site.
Cost
The construction cost associated with this alternative is $17,268,600. O & M present worth
costs amount to $13,339,000. Total present worth is $30,607,600.
2.7.3 Alternative A-3 - RCRA Composite Cap
2.7.3.1 Description
This alternative utilizes a RCRA composite cap to reduce infiltration of surface water
through the waste and contaminated soils (demonstrated by HELP Model). A reduction in
infiltration would result in decreased leachate production and subsequent contamination of
groundwater.
2.7.3.2 Assessment
Overall Protection of Human Health and the Environment
Potential human exposure to Site soils and wastes that pose a health risk is virtually
eliminated by the presence of the existing cap. The additional soil and synthetic membrane
cover provided by a RCRA composite cap would further distance any potential receptors
from contact with the waste and contaminated soil. This alternative provides protection to
human health and virtually eliminates the effects of wastes and underlying contaminated soil
on the environment. This alternative satisfies the specific remedial.action objectives.
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Compliance with ARARs
By preventing further degradation of the groundwater from occurring this alternative
conforms to the relevant and appropriate requirements of the SDWA. This alternative is in
compliance with all other ARARs.
Long-Term Effectiveness and Permanence
This alternative is effective over the long term at reducing contact with waste material and
reducing surface water infiltration. Long-term effectiveness of this alternative would be
guaranteed contingent upon the continued maintenance of the cap and presence of institutional
controls.
Reduction of Toxicity. Mobility and Volume
The Summers Model demonstrates that the addition of a RCRA composite cap would greatly
reduce the mobility of contaminants within the waste and contaminated soil. The reduction
in the mobility of the contaminants is achieved by the virtual elimination of surface water
infiltrating through the waste (only 0.0001 inches/year for a RCRA cap compared to 0.8733
inches/year for the existing clay cap). HELP Model results indicate that a RCRA cap would
have a reduction in infiltration effectiveness of 99.9998 percent. This alternative would
favorably impact the OU #1 remedy as contaminant concentrations and volume of water
migrating to the saturated zone would be decreased. The waste and contaminated soil would
still remain in a volume and toxicity to pose a threat to human health if exposed.
Short-Term Effectiveness
Short-term impacts to human health and the environment due to dust emissions are expected
as a result of the implementation of this alternative. Noise and construction traffic would
also negatively affect local residents. Implementing this alternative would take between 6 to
12 months.
Implementability
Construction of a RCRA composite cap is technically feasible. There are no concerns
regarding the reliability of this alternative provided that maintenance of the cap is continued.
With the exception of those future alternatives requiring waste to be excavated it would be
relatively easy to undertake additional remedial actions. The current network of monitoring
wells to be utilized under the OU #1 remedy will provide the long-term means to monitor the
effectiveness of this alternative at reducing the volume and toxicity of contaminants being
introduced to groundwater. There are no concerns regarding the availability of the necessary
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materials, equipment or personnel to implement this alternative.
Cost
The construction cost associated with this alternative is $3,530,000. O & M present worth
costs amount to $529,100. Total present worth is $4,059,100.
2.7.4 Alternative A-4 - RCRA Composite Cap;
In Situ Soil Vapor Extraction
2.7.4.1 Description
This alternative is a combination of Alternatives A-2 and A-3. In overview, soil vapor
withdrawal wells are placed at the points of soil contamination and air injection wells are
placed at the periphery of the contaminated soil zone and then an airflow is established from
edge to center. The air during passage through the soil contains vapors evolved from liquid
or aqueous phase VOCs and is brought above the ground by the withdrawal wells where the
VOC vapors are thermally desorbed or destroyed on Site. Over 100 extraction/injection
wells, several distribution centers and a vapor treatment unit would be required. The
existing cap would be upgraded to RCRA composite cap to virtually eliminate surface water
infiltration through the waste and contaminated soil. The soil vapor withdrawal wells would
be installed through the cap.
2.7.4.2 Assessment
Overall Protection of Human Health and the Environment
Potential human exposure to Site soils and wastes that pose a health risk is virtually
eliminated by the presence of the existing cap. The additional soil cover and synthetic
membrane cover provided by a RCRA cap would further distance any potential receptors
from the contaminated soil. ISVE will further aid the OU #1 remedy by removing VOCs
from the vadose zone before these VOCs have the opportunity to reach the water table.
However, in light of the effectiveness of the RCRA cap to reduce the generation of leachate
consistent with the requirements of the specific remedial action objectives, ISVE would
provide little additional improvement. SVOCs and pesticides are expected to remain as
contaminants as they are not directly influenced by ISVE. The mobility of these
contaminants is virtually eliminated due to the presence of the RCRA cap. This alternative,
in conjunction with the OU #1 remedy, provides protection to safeguard human health and
virtually eliminates the effects of the wastes on the environment, hence satisfying the specific
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remedial action objectives.
Compliance with ARARs
Alternative A-4 like Alternative A-3 complies with ARARs provided all air emission
standards and transportation regulations are satisfied.
Long-Term Effectiveness and Permanence
The RCRA cap would virtually eliminate the infiltration of surface water through the waste
and soil, hence limiting the migration of contaminants. The likelihood of leaks as a result of
the ISVE extraction/injection wells piercing the cap is anticipated to become a long-term
problem which may result in a decrease in effectiveness and a resultant decrease in
contaminant containment. ISVE is a technology which would likely be effective in
permanently reducing the volume of VOCs within the unsaturated zone underlying the waste
disposal areas although the time frame of removal may be lengthy and it would in no way
impact the SVOCs and pesticides. In fact, the high effectiveness of the RCRA cap would
render the ISVE system redundant for the remediation process.
Reduction of Toxicity, Mobility and Volume
Virtually eliminating surface water infiltration through the waste and soil by the addition of a
RCRA cap would remove the primary transport mechanism for the contaminants. This
alternative would reduce the toxicity, mobility and volume of VOCs that are within the
vadose zone and would prevent further degradation of the groundwater due to VOCs. The
SVOCs and pesticides within the waste and contaminated soil would still remain in a volume
and toxicity to pose a threat to human health if exposed. Mobility of SVOCs and pesticides
is eliminated due to the virtual elimination of surface water infiltration. However installation
of the extraction/injection wells may also improve mobility by permitting greater surface
water infiltration through the punctures in the existing cap and by providing a high
permeability conduit in gravel surrounding the wells from the waste to the lower levels of the
vadose zone.
Short-Term Effectiveness
Short-term impacts to human health and the environment due to air emissions are expected as
a result of the implementation of this alternative. Air and dust emissions would be generated
by the construction activities required for this alternative. Installation of ISVE
extraction/injection wells would require workers to wear respiratory protective gear.
Residents downwind of activities may be affected if engineering controls fail to control
emissions. Short-term effectiveness of the RCRA cap as a horizontal barrier to surface water
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infiltration would be reduced by the many well holes that are required to pierce the cap.
Reduction of VOCs from the vadose zone is forecast to take between 1 to 7 years but
perhaps much longer. Pilot scale tests would need to be conducted to determine the in situ
effectiveness of the ISVE system.
The potential for accidents when transporting/handling treatment residuals off Site and when
transporting/handling caustic chemicals required for treatment on Site is further amplified by
the length of time required for any ISVE alternative.
Implementability
Removing VOCs from the vadose zone utilizing ISVE is technically feasible based upon the
existing sandy stratigraphy of the area and successful past performances of the ISVE system
at other similar sites. However ISVE has never previously been implemented to the depths
proposed for this Site and may pose a significant obstacle to successful removal of the VOCs
from the vadose zone. The remediation of contaminated soil directly below the waste
disposal areas utilizing ISVE would be technically difficult, if not impossible, due to the
presence of containerized waste and debris and frequent silty zones. It is expected that some
removal of VOCs from within the waste may occur, but only in permeable zones directly
connecting with an extraction well. The ability of ISVE to remediate difficult areas and the
extent of risk to human health inherent with installing the required extraction/injection wells
would need to be determined through pilot scale studies. Additional remedial actions would
be difficult due to the expanse of extraction/injection wells and distribution centers placed
over the landfill. The provision of roadways to access each well would also hinder further
additional remedial actions. Soil vapor probes, sampling ports and lysimeters would provide
a means to monitor the effectiveness of this remedy. The decision to select the appropriate
treatment of recovered vapor would be based upon the results of pilot studies and cost
analyses. Treatment of the recovered vapor would likely be by incineration (or equivalent
destruction method) due to the relatively high volume and concentration of contaminants
expected to be produced from the Site. Utilizing a carbon adsorption or thermal desorption
treatment technology would result in large volume of residuals requiring off-Site treatment
subject to RCRA LDRs.
For a project of this duration building an on-Site incinerator would be an effective course of
action. The availability of equipment and specialists to build such a system is not anticipated
to be a problem.
Cost
The construction cost associated with this alternative is $20,572,200. O & M present worth
costs amount to $13,505,100. Total present worth is $34,077,300.
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2.7.5 Alternative A-5 - Excavate Waste and Contaminated
Soil; On-Site Thermal Treatment; Replace
Existing Clay Cap
2.7.5.1 Description
Actions under this alternative would completely remove the waste and contaminated soil
using conventional excavation methods. Excavation, treatment and ash placement would deal
with 3,668,700 c.y. of waste and contaminated soil. The volume of soil to be treated
includes waste and contaminated soil within the associated vadose zone for 27 acres. Once
excavated, waste and contaminated soil would be thermally treated on Site. A description of
thermal treatment can be found in Section 4.2.5.2. In overview, thermal treatment utilizes
heating to increase the relative volatilities between the contaminants and waste/soil matrix
enough to cause vaporization of the organics and moisture into a gas stream. Organics and
moisture are either oxidized in a secondary chamber or are condensed out of the gas stream
and subsequently separated for further treatment. In order to complete remediation the
organics must be destroyed either on the Site or off the Site. To ensure LDRs are satisfied
thermal treatment would ensure that there are no residual concentrations of contaminants
exceeding regulatory criteria (40 CFR 268) within the ash. Treated ash and soil would then
be placed into the excavated landfill. Once backfilled and compacted the treated ash and soil
would be capped by utilizing the existing clay cap.
2.7.5.2 Assessment
Overall Protection of Human Health and the Environment
Removing the contaminants from Site soils would eliminate the original health risk associated
with exposed contaminated soils. Emplacing the existing clay cap would virtually eliminate
any exposure to the treated ash and soil. The health threat from contaminated water would
be significantly reduced by the implementation of this alternative and that of the OU #1
remedy. This alternative, in conjunction with the OU #1 remedy provides protection to
human health and eliminates the effects of the waste and contaminated soil on the
environment.
Compliance with ARARs
This alternative complies with ARARs provided all air emission and residual contaminant
levels within the waste and contaminated soil are within regulatory levels.
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Long-Term Effectiveness and Permanence
This alternative would eliminate the health risk previously associated with exposed
contaminated waste and soils.
This alternative is a highly effective and permanent solution to the present situation on Site.
Reduction of Toxicity. Mobility and Volume
Thermally treating 3,668,700 c.y. of waste and soil would permanently eliminate the
toxicity, mobility and volume of all contaminants. No contaminant residuals above
regulatory levels would exist after treatment. The vadose zone directly influenced by the
waste and contaminated soil would be treated and hence would cease to be a source of
contamination to the groundwater.
The presence of the existing clay cap would reduce surface water infiltration through the
vadose zone. Migration of residual contaminants (existing at below regulatory levels) to the
groundwater would be mitigated due to the presence of the existing clay cap. Human
exposure to low risk treated waste and soil would be virtually eliminated by the presence of
the existing clay cap.
Short-Term Effectiveness
This alternative would involve the excavation of a large volume of waste (653,400 c.y.) and
contaminated soil (3,015,300 c.y.). Based on the contaminant characteristics and
concentrations within the waste and soil observed during the waste sampling program in 1992
any alternative involving excavation would produce air and dust emissions which would
impact the workers and local residents. In order to determine the impacts on workers and
local residents, air emission modeling was conducted for the excavation of waste only
(653,400 c.y.). Paniculate emissions are considered to be a potential problem, however,
only VOC emissions were modeled as it was determined that VOC emissions would be the
more dangerous and hence would govern the conduct of the remedial alternative. These
results clearly indicate that day-sized excavation areas result in air emission magnitudes
above regulatory levels. A day-sized excavation area assumes an excavation rate of 810 c.y.
of clean soil and 1,620 c.y. of contaminated soils each 10-hour day. Modeling also does not
add the cumulative effects of air emissions over a period of days. For these reasons,
modeled air emission are considered to be minimum values and may, on implementation of
this alternative, be magnitudes higher, in turn presenting an even greater health risk.
Engineering controls would need to be implemented in order to limit air emissions to
acceptable levels. Air emissions in the excavation and stockpile areas would require workers
to wear respiratory protection. Air emissions from the thermal treatment may pose
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additional health risks. Excavation and thermal treatment of Site waste and soils would take
5 to 7 years. Dust, construction traffic and noise would negatively impact local residents
throughout the implementation of this alternative. The excavation associated with this
alternative would potentially become a source of contaminated runoff which may, if not
managed through engineering controls, affect both human health and the environment around
and "down-stream" of the Site.
Implementability
This alternative involves excavating 27 acres of waste and contaminated soil to a depth of
approximately 70 feet. The nature of Site soils (i.e., sand) would preclude the use of
vertical-walled excavations. Excavations with sloping sides angled at 2:1 or 1:1 would result
in substantially more soil being excavated. This soil would need to be managed in order to
ensure that cross contamination with Site waste would not take place. The limiting
topography and vegetation of the Site would make management of any excavated soil
difficult. Excavation to a depth of 70 feet is technically difficult given the nature of Site
soils and contamination. Excavated areas would need to be securely covered in order to
control air emissions and eliminate the infiltration of surface water through the waste and
contaminated soil during construction. Additional remedial actions would, dependent on the
action, be relatively easy to implement following the completion of this alternative. Testing
of treated soil and ash would provide a means to monitor the effectiveness of this alternative.
Groundwater monitoring wells as part of the OU #1 remedy would monitor the long-term
resultant decrease in contaminant concentrations within the groundwater as a result of
implementing this alternative.
The construction of an on-Site thermal treatment unit would be required for project of this
size and duration. The availability of equipment and specialists to build such a system is not
anticipated to be a problem.
Cost
The construction cost associated with this alternative is $1,836,035,700. O & M present
worth costs amount to $529,100. Total present worth is $1,836,564,800.
2.7.6 Alternative A6 - Excavate Waste and Place in On-Site
RCRA Landfill; RCRA Cap for Soil
2.7.6.1 Description
This alternative would completely remove the waste from the disposal areas using
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conventional excavation methods. Excavation would deal with 653,400 c.y. of waste. Once
excavated, waste would be pkced in an on-Site RCRA Landfill away from the existing
disposal area. The excavated area would be capped with a RCRA composite cap.
2.7.6.2 Assessment
Overall Protection of Human Health and the Environment
Removing the waste and placing it within an on-Site RCRA landfill would eliminate the
health risk associated with potential human exposure to said waste and significantly reduce
the volume of contaminated leachate generated. The additional RCRA cap placed over the
remaining contaminated soil would further distance any potential receptors from contact with
the waste and contaminated soil. This alternative eliminates the effects of the waste and
underlying contaminated soil on the environment. This alternative satisfies the remedial
action objectives.
Compliance with ARARs
Excavation and redeposition of a waste constitutes a disposal/placement action under RCRA
as defined by 40 CFR 268. Disposal/placement actions are subject to LDRs. This
alternative does not comply with LDRs, in that organic compounds with a chloride
concentration equal to or greater than 1,000 ppm are being disposed of within the on-Site
RCRA landfill without first being treated. The vadose zone modeling demonstrates that
contaminants within the waste when covered by a RCRA cap do not contribute to further
degradation of the groundwater. This alternative, therefore, complies with ARARs if the
on-Site RCRA landfill is designated as a CAMU. Capping of the remaining underlying
contaminated soil with a RCRA cap also was demonstrated not to contribute to further
degradation of the groundwater.
Long-Term Effectiveness and Permanence
This alternative is a permanent solution that would eliminate the health risk previously
associated with exposed waste. Long-term effectiveness and permanence of this alternative
would be guaranteed by continued maintenance of the cap and continued institutional
controls.
Reduction of Toxicity. Mobility and Volume
The Summers Model demonstrates that the addition of a RCRA composite cap would greatly
reduce the mobility of contaminants within the soil and prevent further degradation of the
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groundwater. Disposal/placement of the waste within an on-Site RCRA landfill would
further enhance this reduction in mobility. The volume and toxicity of waste would not
change, however due to the waste being contained and construction of a RCRA cap over the
soil, there would be no further degradation of the groundwater.
Short-Term Effectiveness
This alternative would involve the excavation of a large volume of waste (653,400 c.y.) and
exposure to a large volume of contaminated soil. Based on the contaminant characteristics
and concentrations within the waste and soil observed during the waste sampling program of
1992 any alternative involving excavation would produce air emissions which would impact
the workers and local residents. In order to determine the impacts on workers and local
residents, air emission modeling was conducted for the excavation of the waste. Paniculate
emissions are considered to be a potential problem; however, only VOC emissions were
modeled as it was determined that VOC emissions would be the more dangerous and hence
would govern the conduct of the remedial alternative. These results clearly indicate that
day-sized excavation areas result in contaminant air emissions magnitudes above the
regulatory level. A day-sized excavation area assumes an excavation rate of 810 c.y. of
clean soil and 1,610 c.y. of contaminated soils each 10-hour day. Air emissions in the
excavation and stockpile areas would require workers to wear respiratory protection.
Engineering controls would need to be implemented in order to limit air emissions to
acceptable levels. Dust, construction traffic and noise would negatively impact local
residents throughout the implementation of this alternative. The excavation associated with
this alternative would potentially become a source of contaminated runoff, which may, if not
managed through engineering controls, affect both human health and the environment around
and "down-stream" of the Site.
Implementability
This alternative involves excavating 27 acres of waste to a depth of 15 feet. The nature of
Site soils would preclude the use of vertical-walled excavations. Sloping excavations with
sides angled at 2:1 or 1:1 would result in additional soil being excavated. This additional
soil would likely be contaminated and hence would have to be managed accordingly. The
limiting topography and vegetation of the Site would make management of any excavated soil
difficult. Excavating 15 feet of soil is not technically difficult. Excavated areas would need
to be covered in order to control emissions and eliminate the infiltration of surface water
through the waste and contaminated soil.
Cost
The construction cost associated with this alternative is $57,150,100. O & M present worth
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costs amount to $695,300. Total present worth is $57,845,400.
2.7.7 Alternative A-7 - Excavate Waste and Place in On-Site
RCRA Landfill; Replace Existing Clay Cap;
In Situ Soil Vapor Extraction
2.7.7.1 Description
This alternative would completely remove the waste from the waste disposal areas using
conventional excavation methods. Excavation and subsequent deposition of waste into an
on-Site RCRA landfill would contend with 653,400 c.y. of waste. Once excavated the area
would be capped utilizing the existing clay cap. Excavated waste would be deposited into a
RCRA landfill located on Site away from the existing waste disposal areas. Following
capping over 100 soil vapor extraction/injection wells and several distribution centers would
be constructed to treat the 3,015,300 c.y. of contaminated soil within the vadose zone.
Off-gas produced by ISVE would need to be destroyed on Site by means of incineration (or
equivalent destruction method) or collected by condensation or granular activated carbon and
subsequently destroyed off Site.
2.7.7.2 Assessment
Overall Protection of Human Health and the Environment
Removing the waste and placing it within an on-Site RCRA landfill would eliminate the
health risk associated with potential human exposure to said waste and significantly reduce
the volume of contaminated leachate generated. ISVE would, with time, remove the VOCs
from the vadose zone before these contaminants have the opportunity to reach the water
table. SVOCs and pesticides are expected to remain as contaminants as they are not directly
influenced by ISVE. Emplacing the existing clay cap would virtually eliminate any human
exposure to the remaining contaminated soils of the vadose zone.
This alternative provides on-Site protection to human health, eliminates the potential effects
of the waste and reduces VOC concentrations within the vadose zone.
This alternative does not remove SVOCs and pesticides within the vadose zone. The surface
water infiltration associated with the existing clay cap to be utilized within this alternative
results in continued degradation of the groundwater (as demonstrated by the Summers Model
which in turn demonstrates that this alternative does not comply with the specific remedial
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action objectives.
Compliance with ARARs
Excavation and redeposition of a waste constitutes a disposal/placement action under RCRA
as defined by 40 CFR 268. Disposal/placement actions are subject to LDRs. This
alternative does not comply with LDRs, in that organic compounds with chloride
concentrations equal or greater than 1,000 ppm are being disposed of without being first
treated. Vadose zone modeling demonstrates that contaminants within the soil when covered
by a RCRA cap do not contribute to further degradation of the groundwater. Disposing of
untreated waste into a secure landfill would further ensure that degradation of the
groundwater due to the landfilled waste would not occur. This phase of the alternative
would comply with ARARs if the on-Site RCRA landfill was designated a CAMU.
SVOCs and pesticides remaining in the vadose zone are subject to the surface water
infiltration associated with the existing clay cap. Vadose zone modeling has demonstrated
that these conditions would result in further degradation of the groundwater, contrary to the
relevant and appropriate requirements of the Safe Drinking Water Act MCLs. Therefore,
this alternative does not comply with ARARs.
Long-Term Effectiveness and Permanence
This alternative is a permanent solution that would eliminate the health risk previously
associated with potential human exposure to waste. This alternative greatly reduces the
magnitude of VOCs within the vadose zone although the time frame for removal may be
lengthy. This alternative would not remove the SVOCs and pesticides within the vadose
zone which would continue to contribute to the degradation of the groundwater.
Reduction of Toxicity. Mobility and Volume
Placement of the waste within a secure landfill effectively limits the mobility of hazardous
contaminants. The volume and toxicity of waste would not change, however due to the
contaminants being contained these parameters would not contribute to the further
degradation of conditions at the Site. The volume, toxicity, and mobility of the SVOCs and
pesticides within the vadose zone would not be affected by the ISVE component of this
alternative. However, the presence of the ISVE extraction wells may increase mobility by
permitting greater surface water infiltration through the punctures in the cap and by
providing a high permeability conduit for movement of contaminants to the lower levels of
the vadose zone.
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Short-Term Effectiveness
This alternative would involve the excavation of a large volume of waste (653,400 c.y.) and
worker exposure to a large volume of contaminated soil. Based on the contaminant
characteristics and concentrations within the waste and soil observed during the waste
sampling program of 1992 any alternative involving excavation would produce air emissions
which would impact the workers and local residents. In order to determine the impacts on
workers and local residents air emission modeling was conducted for the excavation of the
waste (653,400 c.y.). Paniculate emissions are considered to be a potential problem,
however only VOC emissions were modeled as it was determined (hat VOC emissions would
be the more dangerous and hence would govern the conduct of the remedial alternative.
These results clearly indicate that day-sized excavation areas result in contaminant air
emissions magnitudes above typical regulatory levels. A day-sized excavation area assumes
an excavation rate of 810 c.y. of clean soil and 1,610 c.y. of contaminated soil each 10-hour
day. Engineering controls would need to be implemented in order to limit air emissions to
acceptable levels. Air emissions in the excavation and stockpile areas would require workers
to wear respiratory protection.
Incinerator emissions associated with vapor destruction may also pose a health risk. In situ
soil vapor extraction of vadose zone soils would take at least 1 to 7 years but perhaps much
longer. Installation of ISVE extraction/injection wells would also require workers to wear
respiratory protection. Dust, construction traffic and noise would negatively impact local
residents throughout the implementation of this alternative. The excavation associated with
this alternative would potentially become a source of contaminated runoff, which may, if not
managed through engineering controls, affect both human health and the environment around
and "down-stream" of the Site.
Implementability
This alternative involves excavating 27 acres of waste to a depth of 15 feet. The nature of
Site soils would preclude the use of vertical-walled excavations. Sloping excavations with
sides angled at 2:1 or 1:1 would likely result in additional soil being excavated. The limiting
topography and vegetation of the Site would make management of any excavated soil
difficult. Excavating 15 feet of soil is not technically difficult. Excavated areas would need
to be covered in order to control emissions and eliminate the infiltration of surface water
through the waste and contaminated soil. Removing VOCs from the vadose zone utilizing
ISVE is technically feasible although the time frame may be excessive.
Additional remedial action would be difficult due to the expanse of injection/extraction wells
and distribution centers placed over the landfill. The provision of roadways to access each
well would also hinder future additional remedial actions. Future additional remedial actions
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would have to contend with SVOCs and pesticides within the vadose zone.
The construction of an on-Site incinerator (or equivalent destruction method) would be
required for vapor destruction for a project of this size and duration. The availability of
equipment and specialized personnel to build the incinerator and ISVE systems is not
anticipated to be a problem.
Cost
The construction cost associated with this alternative is $78,389,300. O & M present worth
costs amount to $13,575,900. Total present worth is $91,965,200.
2.8 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
General
This section provides a comparison between alternatives for all seven evaluation criteria.
Table 2.10 provides the evaluation criteria and factors. Table 2.11 provides a ranking of
alternatives.
2.8.1 Overall Protection of Human Health And The Environment
Specific remedial action objectives presented within Section 2.2.2 detail the required goals
that must be attained to ensure overall protection of human health and the environment. The
following alternatives do not satisfy the specific remedial action objectives:
Alternative A-l
Alternative A-2
Alternative A-7
No Further Action
In Situ Soil Vapor Extraction
Excavate Waste and Place in On-Site
RCRA Landfill; Replace Existing
Cap; In Site Soil Vapor Extraction
Prevents
Direct
Contact
Yes
Yes
Yes
Prevents Further
Degradation of
Groundwater
No
No
No
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TABLE 2.10
DETAILED ANALYSIS CRITERIA AND FACTORS
OPERABLE UNIT #2
HARDEMAN COUNTY LANDFILL RI/FS
HARDEMAN COUNTY, TENNESSEE
Evaluation Criteria
Overall Protection of
Human Health and Environment
Compliance with ARARs
Evaluation Factors
How alternative provides
human health and environmental
protection
Compliance with Chemical-specific ARARs
Compliance with Action-specific ARARs
Compliance with Location-specific ARARs
Compliance with other criteria, advisories and guidelines
Long-Term Effectiveness
and Permanence
Magnitude of residual risk
Adequacy of controls
Reliability of controls
Reduction of Toxicity, Mobility and Treatment process used and materials treated
Volume through Treatment
Amount of hazardous materials destroyed or treated
Degree of Expected Reductions in
Toxiciry, Mobility and Volume
Degree to which treatment is irreversible
Type and quantity of residuals
remaining after treatment
Page 65
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TABLE 2.10
DETAILED ANALYSIS CRITERIA AND FACTORS
OPERABLE UNIT #2
HARDEMAN COUNTY LANDFILL RI/FS
HARDEMAN COUNTY, TENNESSEE
Short-Term Effectiveness Protection of community during remedial actions
Protection of workers during remedial actions
Environmental impacts
Time until objectives and
protection are achieved
Implementability Ability to construct and
operate the technology
Reliability of the technology
Ease for undertaking additional
remedial actions, if necessary
Ability to monitor effectiveness of remedy
Ability to obtain approvals from other agencies
Coordination with other agencies
Availability of off site treatment,
storage and disposal services and capacity
Availability of necessary equipment and specialists
Availability of prospective technologies
Cost Capital costs
Operating and Maintenance Costs
Present Worth Cost
Page 66
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TABLE 2.11
COMPARISON OP ALTERNATIVES
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT #2
HARDEMAN COUNTY, TENNESSEE
Alternative Description
Number
A-1
A-2
A-3
A-4
A-5
A-6
A-7
Description
Jo Further Action
ji Situ Soil Vapor Extraction
RCRA Composite Cap
RCRA Composite Cap
in Situ Soil Vapor Extraction
Excavate Waste and Contaminated Soils
On-Sile Thermal Treatment
Replace Existing Clay Cap
Excavate Waste
Place in On-Sile RCRA Landfill
RCRA Composite Cap Over Soil
Excavate Waste
Place in On-Site RCRA Landfill
Replace Existing Clay Cap
In Situ Soil Vapor Extraction
Achieves
RAOs
(3)
NO
NO
YES
YES
YES
YES
NO
Overall
Protection of
Human Health
and
Environment
NO
NO
YES
YES
YES
YES
NO
Compliance
withARARs
NO
NO
YES
YES
YES
YES
NO
Long-Term
Effectiveness
and
Permanence
7
6
3
2
1
4
5
Reduction of
Toxicity,
Mobility and
Volume
7
6
4
2
1
3
5
Shon-Term
Effectiveness
5
6
1
2
4
3
7
Implementability
1
3
2
4
6
5
7
Cost
1
3
2
4
7
5
6
Total
0)
21 (20)
24 (21)
12(10)
14 (10)
19(12)
20 (15)
30(24)
Ranked
Preferable
Alternative
(2)
5(4)
6(5)
KD
2(1)
3(2)
4(3)
7(6)
Notes:
(I) Totals reflect sum of rankings, therefore a lower total indicates a more preferable alternative. Number in bracket is total, not including cost.
(2) Number in bracket is ranking, not including cost.
(3) RAO - Remedial Action Objective.
Page 67
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The following alternatives do satisfy the specific remedial action objectives:
Alternative A-3 RCRA Composite Cap;
Alternative A-4 RCRA Composite Cap, In Situ Soil Vapor Extraction;
Alternative A-5 Excavate Waste and Contaminated Soils, On-Site Thermal Treatment,
Replace Existing Clay Cap; and
Alternative A-6 Excavate Waste and Place in On Site RCRA Landfill, RCRA
Composite Cap For Soil
2.8.2 Compliance with ARARs
Alternatives A-l, A-2 and A-7 do not comply with ARARs in that further degradation of the
groundwater will take place in contravention of the relevant and appropriate requirements of
the SDWA.
2.8.3 Long-Term Effectiveness and Permanence
Utilizing the evaluation factors as yields the following alternatives ranked in order of long-
term effectiveness and permanence:
The alternatives that are effective in the long term and provide a permanent solution are:
Alternative A-5 Excavate Waste and Contaminated Soil, On-Site Thermal
Treatment
no contaminants, no treatment residuals on Site
The alternatives that are effective in the long-term and provide a permanent solution provided
O & M is maintained are:
Alternative A-4 RCRA Composite Cap, In Situ Soil Vapor Extraction
SVOCs and pesticides on Site, high maintenance
requirement
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Alternative A-3 RCRA Composite Cap
all contaminants on Site, minimum maintenance
requirement
Alternative A-6 Excavate Waste and Place in On-Site RCRA Landfill, RCRA
Composite Cap Over Soil
The following alternatives are non-effective:
Alternative A-7 Excavate Waste and Place in On-Site RCRA Landfill, Replace
Existing Clay Cap, In Situ Soil Vapor Extraction
Alternative A-2 In Situ Soil Vapor Extraction
Alternative A-l No Further Action
2.8.4 Reduction of Toxicity, Mobility and Volume
Utilizing the evaluation factors yields the following alternatives in order of their ability to
reduce toxicity, mobility, and/or volume.
The alternatives that would eliminate the toxicity, mobility and volume of contaminants are:
Alternative A-5 Excavate Waste and Contaminated Soil, On-Site Thermal
Treatment
virtually no toxicity, no mobility and no volume of
contaminants remain
The alternatives that would substantially affect toxicity, mobility and/or volume of
contaminants enough to attain the specific remedial action objectives are:
Alternative A-4 RCRA Composite Cap, In Situ Soil Vapor Extraction
toxicity and volume due to VOCs is eliminated
toxicity and volume due to SVOCs and pesticides remain
unchanged
mobility of all contaminants virtually eliminated
Alternative A-6 Excavate Waste and Place in On-Site RCRA Landfill,
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Alternative A-3
RCRA Composite Cap Over Soil
mobility of all contaminants is virtually eliminated
toxicity and volume remain unchanged
RCRA Composite Cap
toxicity and volume of all contaminants remain
unchanged
mobility of all contaminants virtually eliminated
The alternatives that would not substantially affect toxicity, mobility and/or volume of
contaminants such that attainment of the specific remedial action objectives is not possible
are:
Alternative A-7
Alternative A-2
Alternative A-l
Excavate Waste and Place in On-Site RCRA Landfill, Replace
Existing Clay Cap, In Situ Soil Vapor Extraction
toxicity and volume of contaminants within waste
remains
mobility of contaminants within waste virtually
eliminated
toxicity, mobility and volume of VOCs within vadose
zone virtually eliminated
toxicity, mobility and volume of SVOCs and pesticides
within vadose zone remains unchanged
In Situ Soil Vapor Extraction
toxicity, mobility and volume of VOCs virtually
eliminated
toxicity, mobility and volume of SVOCs and pesticides
remains unchanged
No Further Action
toxicity, mobility and volume of all contaminants remains
unchanged
2.8.5 Short-Term Effectiveness
Utilization of the evaluation factors yields the following alternatives ranked in order of their
short-term effectiveness:
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Alternatives in which specific remedial action objectives are achieved and workers and the
community are protected during remedial actions are:
Alternative A-3 RCRA Composite Cap
6 to 12 months duration
The alternative in which specific remedial action objectives are achieved and workers and the
community are potentially impacted by the remedial action is:
Alternative A-4 RCRA Composite Cap, In Situ Soil Vapor Extraction
years duration
6 to 12 months for RCRA cap, 1 to 7 years for ISVE to
remove VOCs
potential air impacts
Alternative A-6 Excavate Waste and Place in On-Site RCRA Landfill, RCRA
Composite Cap Over Soil
one year duration
air emissions from excavation
contaminated runoff from excavation
Alternative A-5 Excavate Waste and Contaminated Soil, On-Site Thermal
Treatment
5 to 7 years duration
air emissions from excavation and thermal treatment
contaminated runoff from excavation
The following alternatives do not satisfy the specific remedial action objectives or they pose
an unacceptable risk to humans or the environment and hence, are not effective in the short
term:
Alternative A-l No Further Action
potential threat to community through ingestion of
contaminated water
Alternative A-2 In Situ Soil Vapor Extraction
1 to 7 years duration, or perhaps much longer
potential threat to community from air emissions
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Alternative A-7
Excavate Waste and Place in On-Site RCRA Landfill, Replace
Existing Clay Cap, In Situ Soil Vapor Extraction
1 to 7 years duration, or perhaps much longer
air emissions from excavation require engineering
controls
contaminated runoff from excavation
2.8.6 Implementability
Utilizing the evaluation factors yields the following alternatives in order of their ability to be
implemented:
Alternative A-l
Alternative A-3
Alternative A-2
Alternative A-4
Alternative A-6
Alternative A-5
Alternative A-7
No Further Action
RCRA Composite Cap
no concerns regarding this alternative
In Situ Soil Vapor Extraction
implementable, moderately complex technically
RCRA Composite Cap, In Situ Soil Vapor Extraction
potential short- and long-term problems associated with
In Situ Soil Vapor Extraction
complex to implement In Situ Soil Vapor Extraction
complex logistically
Excavate Waste and Place in On-Site RCRA Landfill, RCRA
Composite Cap Over Soil
excavation difficult
Excavate Waste and Contaminated Soil, On-Site Thermal
Treatment
excavation difficult
technically difficult
Excavate Waste and Place in On-Site RCRA Landfill, Replace
Existing Clay Cap, In Situ Soil Vapor Extraction
implementable
complex technically
complex logistically
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2.8.7 Cost
A summary of costs associated with each alternative is presented within Table 2.12. Ranking
of total present worth from least to most expensive yields.
Alternative A-l
Alternative A-3
Alternative A-2
Alternative A-4
Alternative A-6
Alternative A-7
Alternative A-5
No Further Action
$529,100
RCRA Composite Cap
$4,059,100
In Situ Soil Vapor Extraction
$30,607,600
RCRA Composite Cap, In Situ Soil Vapor Extraction
$34,077,300
Excavate Waste and Place in On-Site RCRA Landfill, RCRA
Composite Cap Over Soil
$57,845,400
Excavate Waste and Place in On-Site RCRA Landfill, Replace
Existing Clay Cap, In Situ Soil Vapor Extraction
$91,965,000
Excavate Waste and Contaminated Soils, On-Site Thermal
Treatment, Replace Existing Clay Cap
$1,836,564,800
2.8.8 State Acceptance
EPA and the TDEC have cooperated throughout the RI/FS process. The State has
participated in the development of the RI/FS - reviewing and commenting on planning and
decision documents relating to the Site; and through frequent contact between EPA and
TDEC. EPA and TDEC are in agreement on the selected alternative. Please refer to the
Responsiveness Summary which contains a letter of concurrence from TDEC.
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TABLE 2.12
SUMMARY OF ALTERNATIVE COSTS
HAROEMAN COUNTY LANDFILL, OPERABLE UNIT 92
HARDEMAN COUNTY, TENNESSEE
Alternative*
Alternative
Description
Construction
Costs
O&M
Costs
Total Present Worth
Costa)
A-l
No Further Action
$0
$529,100
$100
A-2
A.4
A-5
A-8
A-9
$13,505,100
In Situ Soil Vapor Extnction
$30,773,700
$4,059,100
-RCRA Composite Cap
-In Situ Soil Vapor Extnction
Excavate Waste and Contaminated Soil
-On-Site Thermal Treatment
ilace Existing day (
i-SS&KSSi
Excavate Waste
-Place in On-Site RCRA Landfill
RCRA Composite Cap Over Soil
._J^M
-Excavate Waste
-Place in On-Site RCRA Landfill
Replace Existing day Cap
-In Situ Soil Vapor Extnction
$20,572200
$1,836,035,700
$57,150,100
$78,389,300
$13,505,100
$529,100
$695^00
$57,845/400
$13^75^00
$91,965^00
Note
(1) 30-year present worth cost in 1995 is based on a discount factor of 5 percent.
Page 74
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Draft Record of Decision
Velsicol/Hardeman County OU#2
Page 75
2.8.9 Community Acceptance
During the public meeting held on July 13, 1995, town residents and local officials expressed
interest and support for the selected remedy presented by EPA. Please see the
Responsiveness Summary which contains a transcript of the public meeting.
2.9 SELECTED REMEDY
Based upon consideration of the requirements of CERCLA, the detailed analysis of the
alternatives using the nine criteria, and public comments, both EPA and the State have
determined that Alternative 3 - RCRA cap is the most appropriate remedy for the
Velsicol/Hardeman County Operable Unit #2.
The RCRA composite cap will reduce surface water infiltration through the waste and
contaminated soils. The existing vegetative cover will be scarified to a depth of
approximately 6 inches and recompacted. A 40-mil high density polyethylene (HDPE)
synthetic liner will be place over the recompacted clay surface. A sand drainage blanket
with a minimum hydraulic conductivity of 1 x 10~3 cm/sec will be placed over the liner to
provide lateral drainage. The sand will be covered with a filter fabric and a layer of
common fill and topsoil. A vegetative cover will be established to prevent erosion of the fill
and topsoil materials.
The RCRA cap will be routinely monitored in order to maintain the integrity of the cap. The
current network of monitoring wells established by Operable Unit #1 will provide the long-
terms means of monitoring the effectiveness of this alternative.
The construction costs associated with this alternative is $3,530,000 (Table 2.13). The
Operation and Maintenance present worth costs are $529,000. The total present worth is
$4,059,100.
2.10 STATUTORY DETERMINATIONS
2.10.1 Overall Protection of Human Health and the Environment
The selected remedy will provide the best overall protection to human health and the
environment by:
Containing the landfill mass by capping and immobilizing hazardous constituents,
minimizing leachate generation.
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TABLE 2.13
ALTERNATIVE A - 3 COST ESTIMATE
"RCRACAP"
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT f 2
HARDEMAN COUNTY, TENNESSEE
Item Description Unit
CONSTRUCTION COSTS
A. General Requirements
A-l Bonds LS .
A-2 Insurance LS
A-3 Permitting & Legal LS
B. Mobilization
B-l Mobilization, Setup and Project Startup LS
C. Health and Safety
C-l Provision of Health and Safety Plan LS
C-2 Provision of Health and Safety Officer Manday
C-3 Provision of Custodian Manday
D. Construction Facilities and Temporary Controls
D-l Soil Erosion and Sediment Control LS
D-2 Site Security Manday
E Project Closeout
E-l Demobilization and Project Closeout LS
F. RCRA Cap
F-l Scarify, Remove Existing Vegetation and Proof Roll
F-2 40-mil HOPE Flexible Membrane Liner
F-3 Sand Drainage Layer (12")
F-4 Filter Fabric
F-5 Common Fill fcTopsoil (12")
F-6 Seed & Mulch Top Cap
F-7 Sod Slopes
OPERATION & MAINTENANCE COSTS
G- Administration and Site Management
G-l Project Management Year
G-2 Site Evaluation (at 5 year intervals) Each
Quantity Unit Cost
180
180
180
$350
5200
$100
Present
Worth
Cost
(1)
$56,000
$42,000
$14,000
$28,000
$20,000
$63,000
$36,000
$10,000
$18,000
$14,000
Acre
SY
CY
SY
CY
Acre
Acre
35
169,400
55,900
169,400
55.900
25
10
$500
$4.50
$6
$1.50
$9
$1,400
$14,500
$17,500
$762,300
$335,400
$254,100
$503,100
$35,000
$145,000
30
6
$10,000
$30,000
$153,700
$83,500
Page 76
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TABLE 2.13
ALTERNATIVE A - 3 COST ESTIMATE
"RCRACAP"
FEASIBILITY STUDY
HARDEMAN COUNTY LANDFILL, OPERABLE UNIT f 2
HARDEMAN COUNTY, TENNESSEE
Item
Description
H. General Site Care
H-l Maintain Access Road
H-2 Maintain Grass Cover
I. RCRA Cap Maintenance
1-1 Erosion Repair
1-2 Fertilizing, Seeding & Mulching
Unit Quantity Unit Cost
Present
Worth
Cost
(1)
Year
Year
Year
Year
30
30
30
30
$3,100
$2,000
$8,100
$1,300
$47700
$30700
$124,500
$20,000
Note:
(1) See Table 6.10 for discussion of Present Worth Costs.
Subtotal Construction Costs: $2,353,400
Construction Supervision (10%) $235,300
Bid Contingency (10%) $235,300
Scope Contingency (15%) $353,000
Engineering Design & Management $353,000
Total Construction Cost: $3,530,000
Subtotal O&M Costs: $460,100
Contingency (15%) $69,000
Total O&M Cost: $529,100
TOTAL PRESENT WORTH: $4,059,100
Page 77
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Draft Record of Decision
Velsicol/Hardeman County OU#2
Page 78
Preventing/eliminating direct exposure to the landfill wastes and contaminated soils by
human and ecological receptors.
Implementation of the selected remedy will reduction in surface water infiltration
effectiveness of 99.9998 percent. This alternative will favorably impact the OU #1 remedy
as contaminant concentrations and volume of water migrating to the saturated zone will be
decreased to the point that no further degradation of groundwater will take place.
2.10.2 Compliance with Applicable or Relevant and Appropriate Requirements
(ARARs)
The selected remedy will meet the Federal ARARS identified below. No state ARARs were
identified for the selected remedy.
Chemical Specific:
1. Safe Drinking Water Act (SDWA) (Maximum Contaminant Levels (MCLs))(40 CFR Part
141) requirements are used as a goal for remediation of groundwater and as such are
relevant and appropriate. Site-specific soil action levels were developed based upon
MCLs. The RCRA cap will meet the soil action levels.
Action-Specific;
1. RCRA Subtitle C (Hazardous Waste Management) (40 CFR 264.310) requirements for
landfill closure and post-closure care are considered applicable to the selected remedy.
Other Criteria. Advisories, or Guidance To Be Considered (TBCs);
1. Covers for Uncontrolled Hazardous Waste Sites, EPA/540/2-85/002, September 1985
Guidance Document
2. Technical Guidance Document: Quality Assurance and Quality Control for Waste
Containment Facilities, USEPA Office of Research and Development, EPA/600/R-
93/182, September 1993
3. Technical Guidance Document: Construction Quality Management for Remedial Action
and Remedial Design Waste Containment Systems, USEPA Office of Research and
Development, EPA/540/R-92/073, October 1992
4. Technical Guidance Document: Final Covers on Hazardous Waste Landfills and Surface
Impoundments, USEPA Office of Solid Waste and Emergency Response, EPA/530-SW-
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Draft Record of Decision
Velsicol/Hardeman County OU#2
Page 79
89-047, July 1989.
5. Seminar Publication: Design and Construction of RCRA/CERCLA Final Covers,
USEPA Office of Research and Development, EPA/625/4-91/025, May 1991.
2.10.3 Cost-Effectiveness
EPA believes this remedy will virtually eliminate the effects of wastes and underlying
contaminated soil on the environment at an estimated cost of $4,059,100. The selected
remedy provides an overall effectiveness proportionate to its costs, such that it represents a
reasonable value for the money that will be spent. A cost estimate is provided in 2.13.
2.10.4 Utilization of Permanent Solutions and Alternative Treatment (or Resource
Recovery) Technologies to the Maximum Extent Practicable
EPA and TDEC have determined that the selected remedy utilizes permanent solutions and
treatment technologies to the maximum extent practicable. However, because treatment of
the principal threats of the Site was not found to be practicable, this remedy does not satisfy
the statutory preference for treatment as a principal element.
EPA and TDEC have determined that this selected remedy provides the best balance of trade-
offs in terms of long-term effectiveness and permanence, reduction of toxicity, mobility, or
volume achieved through containment, short-term effectiveness, implementability, and cost.
The selected remedy treats the principal threat posed to groundwater by soils, achieving
significant reduction in contaminant mobility.
2.10.5 Preference for Treatment as a Principal Element
The selected remedy does not satisfy the statutory preference for treatment due to the
impracticability of treating large volumes of contaminated waste.
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Draft Record of Decision
Velsicol/Hardeman County OU#2
Page 80
3.0 RESPONSIVENESS SUMMARY OVERVffiW
In April of 1991, EPA issued a Fact Sheet which summarized the proposed alternatives for
remediating the groundwater. Following a public comment period, EPA signed a Record of
Decision (ROD) in June 1991 which presented the selected remedy. A Superfund Fact Sheet
Update was mailed to interested citizens in April 1992.
The OU #2 additional investigations, FS and Proposed Plan were released to the public in July
1995. These documents were made available to the public in the Administrative Record and the
information repository maintained at the EPA Docket Room in Region 4 and at the Bolivar-
Hardeman County Public Library. The notice of the availability of these two documents was
published in the Bulletin-Times and the Jackson Sun on July 5, 1995.
A public comment period was held from July 13, 1995 to August 12, 1995. No written public
comments were received during this period. No request for an extension to the public comment
was made. In addition, a public meeting was held on July 13, 1995. At this meeting,
representatives from EPA and the Tennessee Department of Environment and Conservation
(TDEC) answered questions relating to the Site and the remedial alternatives under
consideration. A Bulletin-Times reporter and a local Jackson TV news-station, WBBJ, attended
the public meeting.
This decision document presents the selected remedial action for the Velsicol/Hardeman County
Landfill Superfund Site, OU #2, in Hardeman County Tennessee. The remedial action chosen,
is in accordance with CERCLA, as amended by SARA, and, to the extent practicable, the
National Contingency Plan. The decision for this Site is based on the Administrative Record.
The Proposed Plan, official transcript of the Public Hearing, and the State of Tennessee's
concurrence letter are provided as Attachments A, B, and C.
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