United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R04-93/136
May 1993
v°/EPA Superfund
Record of Decision:
T. H. Agriculture & Nutrition
(Albany Plant), GA
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50272-101
REPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA/ROD/R04-93/136
3. Recipient's Accession No.
4. Title and Subtitle
SUPERFUND RECORD OF DECISION
T.H. Agriculture & Nutrition (Albany Plant), GA
First Remedial Action
5. Report Oat*
05/21/93
7. Authors)
8. Performing Organization Rapt. No.
9. Performing Organization Nam* and Address
10 Project Task/Work Unit No.
11. Contract(C) or Grant(G) No.
(C)
(G)
12. Sponsoring Organization Nam* and Address
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report & Period Covered
800/800
14.
IS. Supplementary Notes
PB94-964017
16. Abstract (UmH: 200 words)
The T.H. Agriculture & Nutrition (Albany Plant) site consists of two former pesticide
formulation facilities in Albany, Georgia. Land use in the area is predominantly
commercial and light residential. Since the 1950s, the site has been used as a
formulation and packaging plant for agricultural chemicals. In 1967, the site was
purchased by T.H. Agriculture & Nutrition (THAN). A small warehouse that formerly
existed on the western portion of the site was used for chemical storage and
distribution of agricultural chemicals; and a dry formulations building was used in the
1960s and 1970s to combine technical materials in specified proportions for products.
A contiguous storage area to the west of the dry formulations was used to house
technical materials. The liquid formulation area was used to blend and transfer the
material to containers for distribution. Wettable powders replaced liquid formulations
in 1976, and little pesticide formulating occurred after 1978. The blendings tank in
the liquid formulation area was rinsed with xylenes between batches of different
products, and the rinsate was discharged into the drainage site, which ran east to west
of the site across the THAN parcel. Onsite operations at the site ceased in 1982. In
1984, the State required THAN to conduct extensive site actions, which included
(See Attached Page)
17. Document Analysis a. Descriptors
Record of Decision - T.H. Agriculture & Nutrition (Albany Plant), GA
First Remedial Action
Contaminated Media: soil, gw
Key Contaminants: VOCs (benzene, PCE, TCE, toluene, xylenes), other organics
(pesticides)
b. Identifiers/Open-Ended Terms
c. COSATI Field/Group
18. Availability Statement
19. Security Class (This Report)
None
20. Security Class (This Page)
None .
21. No. of Pages
56
22. Price
(SeeANSI-Z39.18)
SM Instructions on Rtvtrse
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-35)
Department of Commerce
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EPA/ROD/R04-93/136
T.H. Agriculture & Nutrition (Albany Plant), GA
First Remedial Action
Abstract (Continued)
demolition of buildings, excavation and offsite disposal of site surface and subsurface
soil, and establishment of a vegetative cover. During the RI, an onsite pit was
discovered, which contained plastic vials, of pure pesticide product and contaminated soil.
As a result, in 1992, EPA conducted a second removal, which included demolition and
removal of approximately 20,000 tons of contaminated onsite soil and debris from the
western portion of the site; and onsite treatment of approximately 3,000 tons of soil
containing greater than 100 mg/kg total pesticides using thermal desorption.
Additionally, NAPLs were detected floating on the surficial aquifer in the eastern portion
of the site. This ROD addresses remediation of contaminated soil in the western portion
of the site and contaminated ground water in the residuum and upper aquifers, as OU1. A
future ROD will address the contaminated soil on the eastern portion of the site, as OU2.
The primary contaminants of concern affecting the soil and ground water include VOCs,
including benzene, PCE, TCE, toluene, and xylenes; and other organics, including
pesticides.
The selected remedial action for the site includes inspecting and maintaining the
vegetative cover from the previous removal action; pumping and treating contaminated
ground water onsite using UV/oxidation, based on the results of treatability studies,
followed by treatment with granular activated carbon as a polishing step; discharging the
treated water onsite to either an infiltration gallery or offsite to a POTW, based on the
result of a treatability study; pumping ground water in the eastern portion of the site to
extract NAPLs from the surficial aquifer, with subsequent offsite incineration of the
recovered free product; monitoring ground water and surface water; and implementing
institutional controls, including deed and land use restrictions. The estimated present
worth cost for this remedial action is $4,100,000.
PERFORMANCE STANDARDS OR GOALS:
Chemical-specific ground water cleanup goals are based on SDWA MCLs and MCLGs or
health-based levels, and include aldrin 0.000054 mg/1; alpha-BHC 0.0014 mg/1; beta-BHC
0.0051 mg/1; DDT 0.027 mg/1; dieldrin 0.00057 mg/1; EDB 0.00005 mg/1; and toxaphene 0.003
mg/1.
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RECORD OF DECISION
SUMMARY OF REMEDIAL ALTERNATIVE SELECTION
T H AGRICULTURE A NUTRITION SITE
OPERABLE UNIT ONE
ALBANY, DOUGHERTY COUNTY, GEORGIA
PREPARED BY
U. S. ENVIRONMENTAL PROTECTION AGENCY
REGION IV
ATLANTA, GEORGIA
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DECLARATION
of the
RECORD OF DECISION
OPERABLE UNIT ONE
SITE NAME AND LOCATION
T H Agriculture & Nutrition Site
Albany, Dougherty County, Georgia
STATEMENT OF BASIS AND PURPOSE
This decision document (Record of Decision), presents the selected
remedial action for Operable Unit One for the T H Agriculture &
Nutrition (THAN) Site, Albany, Georgia, developed in accordance
with the Comprehensive Environmental Response, Compensation and
Liability Act of 1980 (CERCLA) , as amended by the Superfund
Amendments and Reauthorization Act of 1986 (SARA) 42 U.S.C. Section
9601 et sea., and to the extent practicable, the National
Contingency Plan (NCP) 40 CFR Part 300. This decision is based on
the administrative record for the THAN site.
The State of Georgia, as represented by the Georgia Environmental
Protection Division (GaEPD), has been the support agency during the
Remedial Investigation and Feasibility Study process for the T H
Agriculture & Nutrition site. In accordance with 40 CFR 300.430,
as the support agency, GaEPD has provided input during this
process. The State of Georgia, as represented by GaEPD, has
concurred with the selected remedy.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from the THAN
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 SELECTED REMEDY
This operable unit is the first of two that are planned for the
Site. This alternative calls for the design and implementation of
response measures which will protect human health and the
environment. The first operable unit addresses the source of the
contamination on the western parcel of the Site as well as the
principle threat of groundwater contamination across the entire
Site. While this remedy does address the principal threats at the
Site, the second operable unit will involve continued study and
remediation of a second source of contamination on the eastern
parcel of the Site.
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The major components of the selected remedy for operable unit one
include:
• Extraction of the free product Non-Aqueous Phase Liquid (NAPL)
lens accumulating on top of the groundwater with off-site
incineration;
Extraction of the groundwater with subsequent onsite treatment by
ultraviolet/oxidation treatment with granulated carbon adsorption
as a polishing step if needed, with the treated water being
discharged to an onsite infiltration gallery or to the local
Publicly-Owned Treatment Works (POTW) with a permit from the City
of Albany or to a local surface water body via an NPDES permit;
• Quarterly monitoring and maintenance of the vegetative cover that
will be established as part of the removal order;
• Monitoring to determine the effectiveness of the dewatering in
reducing the contaminant migration; and
• Institutional controls for land use and groundwater use
restrictions.
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, and is cost-effective. This
remedy satisfies the preference for treatment that reduces toxicity,
mobility, or volume as a principal element. Finally, it is determined
that this remedy utilizes a permanent solution and alternative
treatment technology to the maximum extent practicable.
Because this remedy will result in hazardous substances remaining
onsite above health-based levels, a review will be conducted within
five years after commencement of the remedial action to ensure that
the remedy continues to provide adequate protection of human health
and the environment.
TOBIN, ACTING REGIONAL ADMINISTRATOR DATE
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TABLE OF CONTENTS
1. 0 Site Location and Description 1
2.0 Site History and Enforcement Activities 1
3 . C Highlights of Community Relations 6
4 . 0 Scope of Operable Unit 7
5 . 0 Summary of Site Characteristics 7
5 .1 Geology/Soils 7
5.2 Surface Water and Sediments 9
5.3 Hydrogeology 10
5.4 NAPL Contamination 16
6.0 Summary of Site Risk 16
6.1 Contaminants of Concern 18
6.2 Exposure Assessment 20
6.3 Toxicity Assessment 21
6.4 Risk Characterization 24
6 . 5 Environmental Risk 27
6 . 6 Cleanup Goals 28
7 . 0 Description of Alternatives 31
7 .1 Alternative No. 1 - No Action 31
7.2 Alternative No. 2 - Pump and Treat 32
8.0 Summary of the Comparative Analysis of Alternatives 34
8.1 Overall Protection of Human Health and the Environment... 35
8 .2 Compliance With ARARS 35
8 .3 Long-Term Effectiveness and Permanence 36
8.4 Reduction of Toxicity, Mobility or Volume By Treatment... 36
8 .5 Short-Term Effectiveness 36
8 . 6 Implement ability 36
8.7 Cost 41
8.8 State Acceptance 41
8 .9 Community Acceptance 41
9 .0 Summary of Selected Remedy 41
10.0 Statutory Determination 46
10 .1 Protective of Human Health and the Environment 46
10 .2 Attainment of ARARs 47
10.3 Cost Effectiveness - 47
10.4 Utilization of Permanent Solutions to the Maximum
Extent Practicable 47
10.5 Preference for Treatment as a Principal Element 47
11.0 S igni f icant Changes 47
Appendix A - Responsiveness Summary 49
Appendix B - Concurrence Letters 67
-i-
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LIST OF TABLES
Table 1 Geologic and Hydrogeologic Equivalents, Albany Area 8
Table 2 Contaminants Of Concern 18
Table 3 Table of Critical Toxicity Values 22
Table 4 Uncertainties Associated With Risk Assessment 23
Table 5 Cancer Risks Associated With Groundwater Ingestion 25
Table 6 Non-Carcinogenic Hazard Quotients Associated with
Groundwater Ingestion 26
Table 7 Summary of Cumulative Potential Cancer Risk and Non-
Carcinogenic Hazard Indices 27
Table 8 Summary of Remedial Action Objectives 29
Table 9 Operable Unit #1 Alternatives 31
Table 10 Potential Contaminant-Specific ARARs 37
Table 11 Preliminary ARARs for Contaminants found in Groundwater..38
Table 12 Potential Action-Specific ARARs 39
-11-
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LIST OF FIGURES
Figure 1 Area Map for Albany, Georgia 2
Figure 2 Site Map for the T H Agriculture & Nutrition Site 3
Figure 3 Map Showing Extent of the 1992 Removal Action 5
Figure 4 Isopleths of 1, 2-Dibromoethane (EDB) in Groundwater 12
Figure 5 Isopleths of DDT in Groundwater 13
Figure 6 Isopleths of a-BHC in Groundwater 14
Figure 7 Isopleths of S-BHC in Groundwater 3 ^
Figure 8 Location and Thickness of NAPL on January 28, 1991 17
Figure 9 Diagram of Ultraviolet/Oxidation Treatment Train 33
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Decision Suxrmary
Record of Decision
Operable Unit One
T H Agriculture & Nutrition Site
Albany, Georgia
1.0 SITE LOCATION AND DESCRIPTION
The T H Agriculture & Nutrition (THAN) Site (hereinafter, "the Site")
is located at 1401 and 1359 Schley Avenue in Albany, Georgia. For an
area location map and general Site map, see Figures 1 and 2,
respectively. The Site consists .of two former pesticide formulation
facilities where various liquids and dry formulations of pesticides
and other chemical compounds were handled for a period of
approximately thirty years. The Site is made up of property currently
owned by T H Agriculture & Nutrition Company, Incorporated ("the
western parcel"), and property currently owned by Mr. Larry Jones
which contains an active welding supply store ("the eastern parcel").
The western parcel (1401 Schley Avenue) consists of approximately
seven acres. Buildings were located in the southeastern portion of
the THAN property; however, only one permanent structure remains
onsite. This structure, commonly called the east warehouse, is
located along the southeastern border of THAN parcel. The eastern
parcel (1351 Schley Avenue) consists of approximately five acres, with
several structures remaining in the central portion of the property.
The Site is bordered on the east by residences, on the south by Schley
Avenue, on the west by a Seaboard Coastline Railway line, and on the
north by a construction company. To the west and southwest are
lightly populated residential areas. Several motels are within a one
mile radius of the Site, with the closest being located northeast of
the Site. Located approximately 300 feet south of the Site is an
elevated expressway and further south, a large commercial section of
Albany.
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
The western parcel has been used as a formulation and packaging plant
for agricultural chemicals since the 1950's. Thompson-Hayward
Chemical Company (renamed THAN) purchased the property from Planters
Chemical Company in 1967. Year end inventory records for the
Thompson-Hayward Chemical Company are available beginning in 1973.
Included on the list of products previously stored at the western
parcel are the insecticides lindane, 4,4'-dichlorodiphenyl
1,1,1-trichloroethane (DDT), toxaphene, methyl parathion, malathion,
and parathion. Herbicides included on the lists are the compounds
2,4-dichlorophenoxy butyric acid amine and dinitrobutylphenol (DNBP).
The small warehouse that formerly existed on the western parcel was
used for the storage and distribution of agricultural chemicals. The
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dry formulations building was used in the 1960's and 1970's to combine
technical materials in the proportions specified for a particular
product. The contiguous storage area to the west of the dry
formulations building was used to warehouse technical materials prior
to use in dry formulations. The liquid formulating area was used from
approximately 1973 until approximately 1978 and contained a blending
tank, a weigh scale, and a can filling apparatus. The correct amounts
of liquid technical materials were combined in the blending tank,
transferred to the holding tank, and the product was subsequently
transferred via the can filling apparatus to containers for
distribution. Wettable powders began replacing liquid formulations in
approximately 1976. Very little, if any, pesticide formulating
occurred at the THAN parcel after 1978. Housekeeping in the former
dry formulations building on the western parcel included sweeping
technical materials and dust from the floor. These sweepings were
routinely bagged for' disposal. Trucks used to carry technical
materials or products were also swept clean as necessary. Typically,
trucks were swept out in the eastern portion of the Site in the yard
adjacent to the large warehouse. A drainage ditch ran east to west
across the THAN parcel behind the liquid formulations building to the
low-lying area in the southwestern portion of the property. The
blending tank in the liquid formulating area was rinsed between
batches of different products with xylene and was then discharged to
the drainage ditch.
Business operations ceased in 1982. THAN conducted removal activities
at the Site in 1984 to remove surficial soils in accordance with a
cleanup plan approved by the Georgia Environmental Protection Division
(GaEPD). The cleanup plan identified areas of soil exceeding cleanup
criteria established by GaEPD based on leachable organochlorine
insecticide concentrations as measured using the Extraction Procedure
(EP) Toxicity test method. Extensive remedial activities were
conducted on the THAN parcel in cooperation with GaEPD from July
through September 1984. Major remedial activities included demolition
of several buildings, excavation of selected surface soils and
subsurface disposal areas, installation of a perimeter fence, and
establishment of vegetative cover. Excavated soils and debris were
removed and disposed off-site in a permitted hazardous waste landfill.
During removal, soil excavation continued until the GaEPD-specified
cleanup criteria were met. Soil samples were collected and analyzed
during and after excavation activities to confirm satisfaction of the
GaEPD cleanup criteria.
A second removal at the THAN parcel was initiated under a Unilateral
Administrative Order (UAO) from EPA in March 1992. This removal
action is currently ongoing. Figure 3 portrays the extent of the
current removal on the western parcel. During the Remedial
Investigation (RI) conducted at the Site, a pit containing pure
product and high levels of contamination under the former wet mix
building were found to exist. This pit contained plastic vials
containing product with approximately 12,500 mg/kg. This pit was
located in a former burial area on the western portion of the THAN
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property. Due to the levels of soil contamination found across the
western parcel, the second removal action was deemed necessary at this
Site to protect human health and the environment. The removal
included demolition and removal from the western parcel of several
onsite structures and for the excavation and removal of soil and
debris. According to the UAO, excavated areas are to be backfilled
and a uniform engineered clay cover will be placed over the facility
grounds. Due to the inability to find an off-site incinerator
currently in compliance or capable of handling the volume of soil
removed, onsite low-temperature thermal desorption of those soils
which contain greater than 1000 ppm total pesticides is expected to be
completed during 1993. Instead of completely incinerating the
contaminated material, low-temperature thermal desorption separates
the water vapor and organics from the contaminated media. The
contaminated off-gases can then be treated by filtering through a bed
of carbon. Post-removal confirmation samples show that levels of
contamination in the in-situ soils on the western parcel have been
decreased from greater than 1000 ppm of total pesticides to levels of
less than 20 ppm total pesticides. The top foot of soil has been
removed at approximately six of the seven acres on the THAN parcel,
with specific areas being excavated to seven feet below land surface.
Over 20,000 tons of soil have been removed from the western parcel of
the Site. Excavated areas will be backfilled with common fill and
revegetated pursuant to the removal order.
The eastern parcel has historically been owned by several agricultural
chemical companies, beginning in 1964. The production of fertilizers
and the formulation of pesticides has occurred on the eastern parcel.
Although some soil samples have been collected on the eastern parcel
as part of the RI for operable unit one, a second RI is planned for
the eastern parcel to more fully characterize that parcel (operable
unit two), However, the groundwater contamination that exists
underneath the eastern parcel is addressed in this ROD.
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION
An availability session at a local library and community interviews
with local officials was held at^ the start of field work for the RI
for operable unit one on December 12, 1990. The main branch of the
Dougherty Public Library at 300 Pine Street was chosen as the local
information repository for the Site. On March 12, 1992, THAN held a
public meeting to discuss the second removal action at the Site. In
addition, a fact sheet concerning the RI for operable unit one was
sent to the mailing list in May, 1992.
The public comment period on this ROD was September 14, 1992 through
November 14, 1992. A public meeting was held on Thursday, September
24, 1992 where representatives for EPA answered questions regarding
the Site and the proposed plan under consideration. The
administrative record was available to the public at both the
information repository maintained at the Dougherty Public Library and
at the EPA Region IV Library at 345 Courtland Street in Atlanta,
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Georgia. The notice of availability of these two documents was
published in the Albany News-Herald on September 10, 1992. Responses
to the significant comments received during the public comment period
and at the public meeting are included in the Responsiveness Summary,
which is part of this ROD in Appendix A.
This decision document presents the selected remedial action for
operable unit one of the THAN site, chosen in accordance with CERCLA,
as amended by SARA, and the NCP. The decision for this Site is based
on the administrative record. The requirements under Section 117 of
CERCLA/SARA for public and state participation have been met for this
operable unit.
4.0 SCOPE AND ROLE OF OPERABLE UNIT
EPA has organized the work at this Superfund Site into two operable
units (OUs). These units are:
• OU one: Contamination in the residuum and the upper Ocala
aquifers underneath the entire Site and contamination of
soils on the western portion (THAN property) of the
Site.
• OU two: Contamination of the soils on the eastern portion (Jones
property) of the Site.
OU #1 addresses both the source of groundwater contamination in the
soils on the western parcel as well as the groundwater contamination
underneath the entire Site. The NAPL plume is also being addressed in
OU #1. The purpose of this operable unit is to initiate groundwater
restoration, collect data on aquifer response to remediation, prevent
current or future exposure to the contaminated soils, and reduce
contaminant migration into the groundwater. Operable unit one will be
consistent with any planned future actions.
The planned operable unit two will address the source of contamination
on the eastern parcel of the property. This Site was divided into two
operable units after the RI report showed that continuous groundwater
contamination is present under both properties, and that source areas
exist on the eastern parcel which need to be investigated further.
Additional PRP's are involved on the eastern parcel since that
property was owned and operated separately from the western parcel.
5.0 SUMMARY OF SITE CHARACTERISTICS
5.1 GEOLOGY/SOILS
The sedimentary units outcropping in Dougherty County range from
Quaternary to Cretaceous in age. Only the uppermost geologic units
consisting of the Residuum, the Ocala Limestone, the Claiborne Group,
and the Wilcox Group are pertinent to this study. The Residuum is
typically a silty clay with minor varying amounts of sand, limestone
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fragments, and lignite. It has an average thickness onsite of
approximately 26 feet and thickens to the northwest. The lithology
and structure of the deposit is influenced primarily by the amount of
weathering and the effect of precipitation on the highly soluble
limestone. The Residuum overlies the Ocala Limestone. The Ocala
consists of medium to fine-grained highly weathered, fossiliferous
limestone with some silt and sand. The surface of the limestone
gently undulates and contains depressions, typical of karst terrains.
The limestone grades from a highly weathered material at the top of
the formation to a more brittle rock approximately 30 feet (about 60
feet below ground surface) into the formation. The following table
provides information concerning the generalized stratigraphy.
Table 1
Geologic and Hydrogeologic Equivalents, Albany Area
Approximate
Thickness
(Feet)
15-50
175
230
120
180
80
300
Geologic Sequence
Group
Formation
Residuum
Ocala
Claiborne
Wilcox
Midway
Lisbon
Tallahatta
Hatchetigbee
Tuscahoma
Clayton
Providence Sand
Rip ley
Hydro-geologic
Sequence
Upper water-
bearing
Floridan
Aquifer
Clayton
Aquifer
Providence
Sand Aquifer
Confining Unit
The primary organochlorine (OC) pesticides detected in soil on the
western parcel include: toxaphene, 4,4'-DDT and its metabolites,
beta-BHC, alpha-BHC, and dieldrin. The analytical results for the
surface and subsurface soil samples indicated that the surface soils
have the highest concentrations of the OC pesticides and that the
concentrations decrease significantly with depth. However, some
subsurface soil borings reflect an increase in OC pesticide
concentration between the 10-foot and 15-foot intervals. The
physical/chemical nature of the OC pesticides suggests that they are
not readily biodegraded in the surface environment. The OC pesticides
are generally not soluble in water. However, they are significantly
more soluble in organic solvents, such as xylene. The OC pesticides
8
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also have more affinity for organic matter in soils, which is
generally highest in concentration in the upper limits of the vadose
zone. The higher concentrations of OC pesticides observed in
subsurface soils also had detectable xylenes which suggests that the
mobility of the OC pesticides in soil is probably related to the
presence of the solvent. The presence of the OC pesticides and their
relatively high concentrations in the surface soils attest to their
relative immobility and non-biodegradability.
Organophosphorus (OP) pesticides are essentially absent from surface
and subsurface soil samples. The OP pesticides were detected in
subsurface soil samples collected underneath the former liquid
formulation pad, an area that is not exposed to the atmosphere and
does not receive direct surface infiltration.
The two major herbicides detected on the western parcel are dinoseb
and MCPA. The highest concentrations of these compounds were detected
in surface soil samples and, like the OC pesticides, decreased in
concentration with depth. The frequency of detection of these
compounds, however, was low and somewhat localized. The herbicides
are also similar to the OC pesticides in their stability and
immobility in soil. They are, however, more mobile in the presence of
organic solvents.
Volatile and semivolatile organic compounds were generally found in
subsurface soil samples, albeit infrequently and at low
concentrations. Most of the surface soil samples were not analyzed
for volatile organic compounds based on the knowledge that they are
readily volatilized or biodegraded. Thus, since operations at the
western parcel ceased several years ago and a removal of the surface
soils took place in the early eighties, volatile organic compounds
(VOCs) were assumed to not be present in the surface soil.
Surface Water and Sediments
The area surrounding the Site is drained by the Flint River and
Kinchafoonee Creek systems. Kinchafoonee Creek, located approximately
0.4 miles to the east of the THAN site is the nearest natural body of
surface water. However, there are no swales, drainage ditches, or
intermittent streams that drain from the Site directly to surface
waters.
The natural drainage patterns at the Site were altered during
development of the Site and during the two removal actions that have
occurred. Prior to the removal action that is currently ongoing, most
of the runoff water from the western parcel flowed to a depression in
the southwest portion of the property. This depression drains through
a culvert beneath the Georgia-Great Southern tracks and into the storm
sewer beneath Schley Avenue. This storm Sewer Connects to the storm
sewer system beneath Palmyra Road.
Some drainage from the southeast portion of the western parcel enters
9
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a curb inlet on Schley Avenue and flows into a ditch south of Schley
Avenue. Storm water flows south through the ditch to a point south of
the Liberty Expressway where it joins a ditch draining the west side
of the eastern parcel. From this point the storm water flows west
through a culvert beneath the Georgia-Great Southern railroad tracks
and into a depression south of the Liberty Expressway. Runoff from
the Interstate Truck Leasing facility which is south of the depression
also flows into this depression. The depression drains into the storm
sewer system beneath Palmyra Road through an inlet.
OC pesticides such as DDT were detected in the sediment samples both
on- and off-site. However, the concentrations of the pesticides
dropped significantly in the off-site collection locations as compared
to the onsite collections. As expected, the pesticides are bound to
the sediments rather than to the surface water, since the water
samples collected in the depression south of the Liberty Expressway
did not detect any contamination.
Hvdrogeolocfv
The shallow groundwater system is contained in the residuum soils and
the upper portion of the Ocala Limestone. Infiltration of rainfall
runoff through the surface sands and residuum materials is the major
source of recharge to the aquifers. Typically, the groundwater
reservoirs are recharged most during the winter and spring months when
precipitation is high and evapotranspiration is low. Conversely,
little recharge is added to the groundwater system during the dry
summer months in which heavy agricultural pumpage causes regional
drawdowns in the water level elevations. Recharge rates are directly
affected by the transmissivity and thickness of the overburden
residuum.
Shallow water levels have been observed to rise more than 10 feet
within hours of any intense rainfall event. The magnitude of the rise
in water levels are unexpected since the Site is overlain by a low
permeability clay layer similar to a "cap." The magnitude of the
response is also unexpected since the volume of water infiltrating
through this layer (cap) is very low. The increase in water levels
are due to a hydraulic pressure increase transmitted laterally
throughout the residuum and weathered Ocala from runoff infiltrating
more permeable sediments in a topographically low areas where ponding
of surface water temporarily occurs.
This Site has several unique hydrogeologic features. First, it is
unusual for a very low permeability clay which effectively inhibits
surface recharge to exist at land surface in the Dougherty Plains.
Nevertheless, recharge occurs through numerous depressions which
transmit water rapidly to a lower more transmissive unit (lower
Floridan). Secondly, although the total porosity of the Residuum and
upper Floridan Aquifer is high (30-50 percent), very little "drainage"
of water (probably less than 5 percent) of these units takes place
during drought periods.
10
-------
A comparison of piezometric maps before and after a heavy rainfall
event may suggest as though the storage in the aquifer "has been
filled," which causes an increase in the gradient and that water is
freely flowing. However, this is not the case. Based on the number
of laboratory permeability tests and slug tests conducted within the
upper 30 feet of Residuum and limestone, the actual physical movement
of water (vertically or horizontally) is not significant. Except for
the existence of some paths of preferential groundwater flow in the
more brittle and permeable sections of the limestone, the volume of
water moving laterally through the Site is relatively small.
Solution features such as joints, fractures, and solution channels are
generally not present in the shallow aquifer. Based on the slug tests
and aquifer pumping tests conducted onsite, there appears to be
"channels" of preferred groundwater flow in the weathered upper
Floridan aquifer. These channels are formed by unequal weathering of
the limestone and are relatively narrow and few in number. Most of
the upper Floridan is very fine grained and appears in large "islands"
of low permeability separated by the more permeable channels. Most
wells are screened into the islands; however, wells located near or in
the channels will often have a much greater ability to produce water.
The most direct path of the contaminants to the groundwater was by the
slow infiltration through the surficial sediments to the water table.
Once the percolating water reached the water table, the horizontal
rate of flow is toward the northeast at a very slow rate. Since most
of the mobile contaminants were less dense than water, a NAPL lens
accumulated on top of the groundwater. The lens has migrated only
slightly east and northeast over the history of the Site.
The shallow groundwater monitoring wells reported the highest
concentrations of the chemicals of concern. The major compounds
detected were the OC pesticides and VOCs. The predominant OC
pesticides in the groundwater are the BHC isomers and DDT (not
toxaphene which was the predominant OC pesticide found in the soil).
The presence of these OC pesticides in the westernmost wells was not
always associated with the presence of a detectable concentration of
an organic solvent or a significant concentration of the specific OC
pesticides in the subsurface soil that was close to having contact
with groundwater. However, the presence of 4,4'-DDT in the monitoring
wells along the west edge of the eastern parcel was associated with
the presence of an organic solvent, primarily xylene. The vertical
and horizontal movement of the non-aqueous phase liquid (NAPL) and the
interaction of the groundwater may influence the solubility of
isolated pockets of NAPL left in the soil as the pressure from the
groundwater movement vertically forces the NAPL upward.
The compound 1,2-dibromoethane (EDB) , was detected primarily in the
western portion of the eastern parcel. EDB is water soluble,
biodegradable, and volatile. When released to a surface soil
environment, it generally undergoes rapid biodegradation. However, a
large release would result in infiltration of EDB and its rapid
11
-------
Figure 4
Map of Isopleths of 1,2-Dibromoethane (EDB) in Groundwater
12
-------
Figure 5
Map of Isopleths of DDT in Groundwater
13
-------
Figure 6
Map of Isopleths of a-BHC in Groundwater
14
-------
Figure 7
Map of Isopleths of S-BHC in Groundwater
15
-------
movement due to its low adsorption potential towards most soils.
Figures 4 through 7 portray the extent of groundwater contamination
across the Site of several prevalent contaminants such as EDB, DDT,
alpha-BHC, and beta-BHC, respectively.
NAPL Contamination
One of the major contamination problems at the Site is a lens of a
floating NAPL that was observed in the eastern portion of the site in
grab samples from soil borings, development water, purge water, and in
groundwater samples. The NAPL lens, also known as free product,
consists of xylene and other solvents with various types of pesticides
dissolved in it. The NAPL has been observed in monitoring wells
located on the east-central portion of the western parcel. The
locations in which NAPL has been reported include MW-8, MW-14, MW-15,
MW-16, GB-2, GB-5, GB-6, GB-8I, GB-9I, GB-12, GB-14, GB-15, and OW-3.
The approximate lateral extent of the NAPL is shown on Figure 4-8.
Ethylbenzene and xylene are the most prevalent volatiles, with
toxaphene and alpha-BHC being the most common organochlorine
pesticides. Organophosphorus (OP) pesticides are also found in the
NAPL. The NAPL has been measured to be over four feet in thickness at
some locations on the THAN parcel. A dense (non-floating) NAPL (which
would sink below the water table) has not been detected at the Site.
The extent of the NAPL is shown in Figure 8.
In general, groundwater contamination is highest in central and
eastern portions of the western parcel in the areas around the
facility buildings. Highest concentrations are also found in the
vicinity of the NAPL plume with concentrations generally decreasing
markedly away from the NAPL.
6.0 SUMMARY OF SITE RISKS
CERCLA directs EPA to conduct a baseline risk assessment to determine
whether a Superfund Site poses a current or potential threat to human
health and the environment in the absence of any remedial action. The
baseline risk assessment provides the basis for determining whether or
not remedial action is necessary and the justification for performing
remedial action.
Ingestion of groundwater could result in exposure to various
contaminants if the water was obtained onsite from the contaminated
water-bearing unit. Exposure to contaminated groundwater may result
if an off-site drinking water or domestic use water well is installed
in a water bearing zone which is known to be contaminated. However,
evidence suggests that this situation does not exist since perimeter
wells have not shown any contamination. Monitoring will continue to
assess the potential for off-site migration of contaminants via
groundwater. It is not believed that contaminants in Site groundwater
are discharging to surface water bodies since the closest water body
is 0.4 miles from the Site. Current evidence shows that the zone of
contamination beneath the Site does not extend far enough to impact
16
-------
f
o
n
0)
rt
H-
O
3
0)
a
a
o
CD
w
W
00
O
3
3
C
0)
to
00
-------
local rivers or streams.
The major risk that is currently associated with the THAN site is a
floating lens of NAPL that is located in the surficial aquifer.
At this time, the contamination has not been detected in the off-site,
downgradient monitoring wells located to the east. However, if the
contaminants are allowed to remain, the potential for migration and
human exposure exists. As a potential source of pesticides and
solvents, the NAPL provides a mechanism for the release of
contaminants to groundwater. Most of the pesticides at the Site are
not readily soluble in water. The NAPL, which can act as a solvent
for pesticides, may increase the solubility of these compounds and,
thus, the potential for their release to the groundwater.
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 eminent and substantial endangerment to public
health, welfare, or the environment.
6.1 CONTAMINANTS OF CONCERN
The majority of the wastes and residues generated by production
operations at the facility have been managed, treated, and disposed of
onsite throughout the Site's history. The chemicals measured in the
various environmental media during the RI were evaluated for inclusion
as chemicals of potential concern in the risk assessment by
application of screening criteria. The criteria which resulted in
elimination of chemicals included: Site contaminant concentrations
below background concentrations; measurements below quantification
limits; a combination of low toxicity and low concentration or low
persistence and low concentration and low frequency of detection.
Table 2
Contaminants of Concern
Compound
2,4,5-T
Dicamba
Dinoseb
MCPA
4,4' -ODD
4,4' -DDE
4,4' -DDT
Aldrin
Average Concentration*
Soil
(Ua/ka)
ND
ND
28
11,700
47,038
4,356
100,868
515
Groundwater
(ua/L)
4
4
93
ND
11
1
19
1
NAPL
(mcr/L)
ND
ND
ND
ND
ND
ND
8,700
ND
18
-------
Dieldrin
Endosulfan I
Endosulfan II
Endrin
Endrin aldehyde
Endrin ketone
Toxaphene
a-BHC
a-Chlordane
S-BHC
8-BHC
Lindane
F-Chlordane
DBF
Ethyl parathion
Malathion
Methyl parathion
1,2, 4-Trichlorobenzene
1, 4-Dichlorobenzene
2-Methylnapthalene
4 -Ni t rophenol
Isophorone
Naphthalene
1 , 2 -Dibromoethane ( EDB)
1 , 2 -Dichloropropane
Benzene
Chlorobenzene
Chloroform
Ethylbenzene
Tetrachloroethene
Trichloroethene
Xylene
Cyanide total
3,479
38,134
31,217
14,057
669
6,319
341,149
4,582
3,250
4,741
514
321
3,126
2,106
10,664
4,066
34,379
805
ND
6,806
ND
2,677
3,258
ND
ND
ND
ND
ND
ND
ND
ND
ND
270
1
3
ND
4
2
2
80
5
1
11
3
3
ND
ND
1
1
1
43
41
127
ND
40
71
112
52
36
37
32
1.419
35
35
4,922
10
ND
1,600
ND
ND
ND
ND
48,000
420
ND
ND
ND
ND
ND
ND
25
ND
25
ND
ND
5,800
ND
ND
1,800
ND
ND
ND
ND
ND
60,000
_ ND
ND
30,000
ND
* = Average concentration developed from Phase 1
ND = Not detected at laboratory reporting limits
data
19
-------
6.2 EXPOSURE ASSESSMENT
Whether a chemical is actually a concern to human health and the
environment depends upon the likelihood of exposure, i.e. whether the
exposure pathway is currently complete or could be complete in the
future. A complete exposure pathway (a sequence of events leading to
contact with a chemical) is defined by the following four elements:
• A source and mechanism of release from the source,
A transport medium (e.g., surface water, air) and mechanisms
of migration through the medium,
• The presence or potential presence of a receptor at the
exposure point, and
• A route of exposure (ingestion, inhalation, dermal
absorption).
If all four elements are present, the pathway is considered complete.
An evaluation was undertaken of all potential exposure pathways which
could connect chemical sources at the Site with potential receptors.
All possible pathways were first hypothesized and evaluated for
completeness using EPA's criteria. Three current potentially complete
exposure pathways and four future exposure pathways remained after
screening. The current pathways represent exposure pathways which
could exist under current Site conditions while the future pathways
represent exposure pathways which could exist, in the future, if the
current exposure conditions change. Exposure by each of these
pathways was mathematically modeled using generally conservative
assumptions.
The current pathways are:
• potential oral exposure by a trespasser to surface soils
• potential dermal exposure by a trespasser to surface water,
and
• potential dermal exposure by a trespasser to surface soils.
The future pathways are:
potential dermal exposure by Site workers to surface soil,
• potential oral exposure by Site workers to surface soil,
• ingestion of contaminated groundwater by near-site or onsite
residents and,
• ingestion of soil by potential onsite residents.
20
-------
The exposure point concentrations for each of the chemicals of concern
and the exposure assumptions for each pathway were used to estimate
the chronic daily intakes for the potentially complete pathways, with
the exception of the groundwater pathway. The chronic daily intakes
were then used in conjunction with cancer potency factors and
noncarcinogenic reference doses to evaluate risk.
The major assumptions about exposure frequency and duration that were
included in the exposure assessment were:
• Onsite residents were assumed to have an exposure frequency
of 351 days per year. The hypothetical industrial worker is
assumed to spend 250 days per year onsite for 30 years, based
on a 5 day working week for 50 weeks per year. A 10-15 year-
old juvenile trespasser who would enter the Site is assumed
to have an exposure frequency of 24 days per year for 5
years.
• Soil ingestion rates for onsite residents include a rate of
200 mg/day for children aged 0-13 years and 100 mg/day for
residents aged 14 to adult. Soil ingestion rates for a
future industrial worker is 50 mg/day and 100 mg/day for a
juvenile trespasser. Groundwater ingestion rates for an
onsite resident adult is 2 liters/day, with 1 liter/day being
assumed for a resident child or a hypothetical industrial
worker.
• Dermal contact exposure parameters for surface water for a
juvenile trespasser include contact for 12 days/year for 2
hours/day for 5 years.
• In all scenarios a standard body weight of 70 kg was used for
adults.
The groundwater at the THAN site currently contains concentrations of
the Site contaminants at levels which would pose an unacceptable risk
to human health if the water was being used for human consumption.
However, the extent of groundwater contamination has been delineated,
and this contamination does not extend beyond the Site boundaries. As
a result, this is not a current complete exposure pathway, since there
are no wells onsite. The former pesticide formulation areas are the
major contributors to the contaminated groundwater.
6.3 TOXICITY ASSESSMENT
Toxicity values are used in conjunction with the results of the
exposure assessment to characterize site risk. EPA has developed
critical toxicity values for carcinogens and noncarcinogens. These
critical toxicity values are listed in Table 3. Cancer potency
factors (CPFs) have been developed for estimating excess lifetime
cancer risks associated with exposure to potentially carcinogenic
chemicals. CPFs, which are expressed in units of (mg/kg/day) ~l, are
21
-------
CB1TICAL TU11UII VALUB*
SLOP! FACTORS <8Ti> AND RKTIUNCt DOOXS (Bffl.)
(W.)
i.Ttia1
frBHC
T-BHC
OfD>
(UD*
talV*
telO*
NC
taio-
8.U104
uio*
Cpuafa
2UO*
4.V-DOD
14*10"
4.V-DDE
4.4--ODT
a.4110*
bier*
ti.101
1^10*
blO*
1X10*
blO*
blO*
too1
U10*
EUut
blO*
4.1110'
too'.
2X10*
bio*
UflO4
NC
C.U10*
1JUO*
Z.4.1-T
IxUC
1.1
1.U104
ND
NC
ND
22
-------
multiplied by the estimated intake of a potential carcinogen, in
mg/kg/day, to provide an upper-bound estimate of the excess lifetime
cancer risk associated with exposure at that intake level. The term
"upper bound" reflects the conservative estimate of the risks
calculated from the CPF. Use of this conservative approach makes
underestimation of the actual cancer risk highly unlikely. Cancer
potency factors are derived from the results of human epidemiological
studies or chronic animal bioassays to which animal-to-human
extrapolation and uncertainty factors have been applied.
Reference doses (RfDs) have been developed by EPA for indicating the
potential for adverse health effects from exposure to chemicals
exhibiting noncarcinogenic effects. RfDs, which are expressed in
units of mg/kg/day, are estimates of lifetime daily exposure levels
for humans, including sensitive individuals. Estimated intakes of
chemicals from environmental media can be compared to the RfD. RfDs
are derived from human epidemiological studies or animal studies to
which uncertainty factors have been applied (e.g., to account for the
use of animal data to predict effects on humans). These uncertainty
factors help ensure that the RfDs will not underestimate the potential
for adverse noncarcinogenic effects to occur.
TABLE 4
SUMMARY Of UNCERTAXNTIBS ASSOCIATED
WITH RISK ASSESSMENT
Assumption
Estimated
Magnitude of
Effect on
Risk
Direction of Effeet
on Risk Estimate
Environmental Sampling and Analysis
Errors in chemical analysis
The majority of sampling wells are
installed in the region of the
suspected contaminant plume
Low
Low-Moderate
Over or
underestimate risk
Overestimate risk
Fat* and Transport Modeling
Chemical concentrations reported as
•below method detection limit* are
used at one-half detection limit
when calculating mean chemical
concentrations
Low
Over or
underestimate risk
Toxieologieal Data
Hazard indices (His) were developed
assuming all toxic effects were
additive
Low-Moderate
Overestimate risk
Exposure Parameter*
Conservative values were used for
exposure duration, frequency,
ingestion, and soil adherence factor
Low-Moderate
Overestimate risk
23
-------
6.4 RISK CHARACTERIZATION
Human health risks are characterized for potential carcinogenic and
noncarcinogenic effects by combining exposure and toxicity
information. Excessive lifetime cancer risks are determined by
multiplying the estimated daily intake level with the cancer potency
factor. These risks are probabilities that are generally expressed in
scientific notation (e.g., IxlO"6). An excess lifetime cancer risk of
IxlO"6 indicates that, as a plausible upper boundary , an individual
has a one. in one million additional (above their normal risk) chance
of developing cancer as a result of site-related exposure to a
carcinogen over a 70-year lifetime under the assumed specific exposure
conditions at a site.
Throughout the risk assessment process, uncertainties associated with
evaluation of chemical toxicity and potential exposures arise. For
example uncertainties arise in derivation of toxicity values for
reference does (RfDs) and carcinogenic slope factors (CSFs),
estimation of exposure point concentrations, fate and transport
modeling, exposure assumptions and ecological toxicity data. Because
of the conservative nature of the risk assessment process, risk
estimated in this assessment are likely to be overestimates of the
true risk associated with potential exposure at OU #1 of the THAN
Site. Uncertainties for the OU#1 at the THAN Site are enumerated in
Table 4.
EPA considers individual excess cancer risks in the range of IxlO"4 to
IxlO"6 as protective; however the IxlO"6 risk level is generally used
as the point of departure for setting cleanup levels at Superfund
sites. The point of departure risk level of IxlO"6 expresses EPA's
preference for remedial actions that result in risks at the more
protective end of the risk range. The health-based risk levels for OU
#1 are shown in Tables 5, 6, and 7.
Potential concern for noncarcinogenic effects of a single contaminant
in a single medium is expressed as the hazard quotient (HQ) (or the
ratio of the estimated intake derived from the contaminant
concentration in a given medium to the contaminants's reference dose).
A HQ which exceeds one (1) indicates that the daily intake from a
scenario exceeds the chemical's reference dose. By adding the HQs for
all contaminants within a medium or across all media to which a given
population may reasonably be exposed, the Hazard Index (HI) can be
generated. The HI provides a useful reference point for gauging the
potential significance of multiple contaminant exposures within a
single medium or across media. An HI which exceeds unity indicates
that there may be a concern for potential health effects resulting
from the cumulative exposure to multiple contaminants within a single
medium or across media. The His for OU #1 are shown in Tables 6 and
7.
24
-------
TABLE 5
POTENTIAL CANCER RISKS
ASSOCIATED WITH ORO0NDWATBR INOBSTION
BASED ON REASONABLE MAXIMUM EXPOSURE (RMB)
Compound1
Toxaphene
DDT
0-BHC
Dieldrin
P-BHC
ODD
DDE
Aldrin
Y-BHC
o-Chlordane
Isophorone
Benzene
Chloroform
Dibromethane (iiDB)
Dichloropropane
Tetrachloroethene
Trichloroethene
r
Bxponur* Scenario
Industrial
Worker
8.9E-5
1.4E-6
4.5E-4
6.4E-5
1.6E-4
0
0
0
5.5E-5
0
1.4E-7
2.0E-5
4.2E-6
9.6E-2
5.3E-5
3.5E-5
0
9.7E-2
On- Sit* R*«id*nt
0-2a
5.0E-5
7.9E-7
2.5E-4
3.6E-5
9.1E-5
0
0
0
3.1E-5
0
7.9E-8
1.1E-5
2.4E-6
5.4E-2
3.0E-B
2.0E-5
0
5.5E-2
2-5'
5.6E-5
8.9E-7
2.9E-4
4.1E-5
l.OE-4
0
0
0
3.5E-5
0
8.9E-8
1.3E-5
2.6E-6
6.1E-2
3.4E-5
2.2E-5
0
6.1E-2
5-13'
7.4E-5
1.2E-6
3.8E-4
5.4E-5
1.3E-4
0
0
0
4.6E-5
0
1.2E-7
1.7E-5
3.5E-6
8.0E-2
4.5E-5
2.9E-5
0
8.1E-2
13-18'
3.8E-5
6.0E-7
1.9E-4
2.8E-5
6.9E-5
0
0
0
2.4E-5
0
6.0E-8
8.6E-6
1.8E-6
4.1E-2
2.3E-5
1.5E-5
0
4.2E-2
Adult
2.5E-4
3.9E-6
1.3E-3
1.8E-4
4.5E-4
0
0
0
1.5E-4
0
3.9E-7
5.6E-5
1.2E-5
2.7E-1
1.5E-4
9.8E-5
0
2.7E-1
Not««i
The subset of contaminants of concern found in groundwater which are carcinogens and for which slope factors are
available.
Denotes years of age.
Cumulative cancer risk for all compounds.
25
-------
TABLE 6
NON-CARCINOOBHXC HAZARD QUOTIENTS
ASSOCIATED WITH OROONDWATBR XHOBSTION
BASED OK REASONABLE MAXIMUM EXPOSURE (RHB)
Compound1
DDT
Dieldrin
Aldrin
Y-BHC
a-Chlordane
Isophorone
Ethyl Parathion
Endosulfan I
Methyl Parathion
Endrin
Trichlorobenzene
Naphthalene
Malathion
Dinoseb
Cyanide
Chloroform
Tetrachloroethene
Chlorobenzene
Ethylbenzene
2,4.5-T
Xylene
I5
Bxpocur* Scenario
Industrial
worker
2.1E-2
2.0E-1
0
3.5E-2
0
4.3E-4
0
0
0
1.7E-2
1.1E-1
3.0E-1
0
7.8E-2
0
1.7E-1
1.7E-2
8.8E-2
5.0E-1
0
8.4E-2
1.6
On-Sit* R«*id«nt
0-2'
1.7E-1
1.7
0
3.0E-1
0
3.6E-3
0
0
0
1.4E-1
9.0E-1
2.5
0
6.6E-1
0
1.5
1.5E-1
7.5E-1
4.2
0
7.1E-1
13.7
2-5'
1.3E-1
1.3
0
2.2E-1
0
2.7E-3
0
0
0
1.1E-1
6.8E-1
1.9
0
4.9E-1
0
1.1
1.1E-1
5.6E-1
3.2
0
5.3E-1
10.2
5-13'
6.4E-2
6.3E-1
0
1.1E-1
0
1.3E-3
0
0
0
5.2E-2
3.3E-1
9.3E-1
0
2.4E-1
0
5.4E-1
5.4E-2
2.8E-1
1.6
0
2.6E-1
5.1
13-18'
5.3E-2
5.2E-1
0
9.1E-2
0 .
1.1E-3
0
0
0
4.3E-2
2.8E-1
7.7E-1
0
2.0E-1
0
4.4E-1
4.4E-2
2.3E-1
1.3
0
2.2E-1
4.2
Adult,
5.8E-2
5.7E-1
0
9.9E-2
0
1.2E-3
0
0
0
4.7E-2
3.0E-1
8.3E-1
0
2.2E-1
0
4.8E-1
4.8E-2
2.5E-1
1.4
0
2.4E-1
4.5
Not«»»
1 The subset of groundwater contaminants of concern for which RfD values are available.
2 Denotes years of age.
J The summation of the Hazard Quotients is termed the Hazard Index.
26
-------
Table 7
Summary of Cumulative Potential Cancer Risks
and Non-Carcinogenic Hazard Indices
Exposure Scenario
Reasonable Maximum Exposure (RME)
Potential Cancer Risk
Non-Carcinogenic
Hazard Index
Ons ite
Juvenile Trespasser
Industrial Worker
0-2 Resident3
2-5 Resident3
5-13 Resident3
13-18 Resident9
Adult Resident
Child Resident13
Off-Site
0-2 Resident3
2-5 Resident3
5-13 Resident3
13-18 Resident3
Adult Resident
Child Resident15
3.2xl(r5
9.8xlO'2
5.6xlO-2
6.2xl(T2
8.2xl(T2
4.2xlO'2
2.7X10'1
2.4X1CT1
S.OxlCT6
9.0xlO'6
1.2xl(T5
e.ixicr6
4.0xlO'5
3.5xlO'5
1.1
4.8
81.0
62.7
35.2
17.1
15.0
NA
3.5X10'1
2.6X10'1
1.3X10'1
l.lxlO'1
1.2X10'1
NA
a = Denotes years of age
b = The total cancer risk for a child resident (0-18 years of age)
is the summation of the cancer risk for each age group.
NA = Not applicable.
6.5 ENVIRONMENTAL RISK
Due to the removal action initiated in 1992, each of the source areas
will be covered with fill; therefore, the contaminated areas on
western parcel are not easily accessible to wildlife. Currently all
of the contaminated surface material on the western parcel has been
removed. The western parcel will be brought back to the original
grade and will be revegetated. For this reason the source areas are
not expected to have toxic effects on those terrestrial animals at
this time. The selected remedy based on human health will eliminate
the potential for toxic effects since the environmental exposure
27
-------
pathways will not exist. There are no known critical habitats or
endangered species affected by Site contaminants.
6.6 CLEANUP GOALS
The establishment of health-based cleanup goals serves as an important
means of guiding remedial activities. A health-based approach is
warranted when cleanup standards promulgated by state or federal
agencies are not available for contaminants in soil, as well as for
certain groundwater contaminants. The approach to developing health-
based goals is derived from the risk assessment process. The risk
assessment is essentially a process by which the magnitude of
potential cancer risks and other health effects at a site can be
evaluated quantitatively. A cleanup goal is established by back-
calculating a health protective contaminant concentration, given a
target cancer risk or hazard index which is deemed acceptable and
realistic. The concept of the cleanup goal inherently incorporates
the concept of exposure reduction which allows remedial alternatives
to be flexible.
The groundwater at the THAN site currently contains concentrations of
Site-related contaminants at levels which would pose an unacceptable
risk (cumulative risk in excess of IxlO"4) to human health if the
water was being used for human, consumption. 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.
The cleanup levels for groundwater are contained in Table 8. The
groundwater cleanup levels have been generated to ensure localized
isolation and treatment of contaminated groundwater which exceeds the
health-based groundwater cleanup levels established at the IxlO"4 risk
level. The IxlO"4 risk level is protective in light of the current
surface removal which remediated the surface soils to the IxlO"6 risk
level and in light of the deed restrictions that are planned for this
operable unit. Furthermore, no current ingestion of contaminated
groundwater exists, and the deed restrictions are designed to prevent
wells from being installed onsite. The extended time period that any
pump and treat option is expected to be in operation and the
prevention of migration of contamination off-site by a pump and treat
system justify the IxlO"4 level. Cleanup levels for groundwater
protection are based on a IxlO"4 risk level for carcinogens and a
hazard quotient of 1 for noncarcinogens. Setting the cleanup levels
for the groundwater contamination at the IxlO"4 risk leyel is
consistent with the NCP's requirement for establishing cleanup levels
within the IxlO"4 to IxlO"6 range. This cleanup level provides an
acceptable exposure level that is protective of human health and the
environment in a residential setting. Cleanup levels for contaminated
surface soil are based on a child exposure scenario and assume a
residential land use. These levels are based on the ingestion and
inhalation exposure routes and represent a IxlO"6 risk level for
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carcinogens and a hazard quotient of 1 for noncarcinogens. The
cleanup levels for groundwater and are listed in Table 8. The cleanup
levels for IxlO"6 for surface soils has already been met by the
current removal action at the Site.
TABLE 8
Summary of Remedial Action Objectives
Compound
DDT
Toxaphene
a-BHC
S-BHC
Aldrin
Dieldrin
EDB
Medium
Groundwater (^g/L)
0.027
0.003
0.0041
0.0051
0.00054
0.00057
0.00005
The groundwater cleanup levels will be applied at the Site to ensure
that any future groundwater consumers will not be exposed to
unacceptable concentrations of Site-related chemicals in the
groundwater. The concentrations presented represent either the
regulated Maximum Contaminant Level (MCL) or the health-based cleanup
goal which was developed for those chemicals of concern which do not
have MCLs.
Although the contaminants of concern are not the only contaminants at
the Site, they were chosen based on toxicity, mobility and frequency
of detection throughout the Site. It is anticipated that contaminants
at the Site which do not have cleanup levels presented in this ROD
will be reduced to acceptable levels when cleanup levels are met for
the most toxic and most mobile contaminants for which cleanup levels
have been established.
The remedial action objectives for the contaminated surface soil on
the western parcel have been met by the currently ongoing removal
action at the Site. All of the soil has been excavated, with
approximately 20,000 tons of soil being landfilled off-site.
Approximately 3000 tons of excavated material remain onsite in
stockpiles. This excavated material could not be landfilled since the
total pesticide concentration was greater than 1000 ppm. Currently,
the excavated material is being treated onsite by a low-temperature
thermal desorption technique.
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Transport modeling was used to evaluate the contribution of
contaminated subsurface soil to groundwater contamination. The PESTAN
computer transport model was used to determine the levels of
contamination which can exist in the subsurface soil and not create a
condition in the groundwater whereby groundwater protection standards
are exceeded.
PESTAN was developed by the EPA Robert S. Kerr Environmental Research
Laboratory in Ada, Oklahoma for estimating the vertical migration of
pesticides through soil to groundwater. The model presents an
analytical solution to a solute transport equation, considering
sorption, dispersion, and degradation. The model output consists of
chemical concentrations at varying depths in the unsaturated soil
profile for specified times. The model presents one-dimensional
concentration profiles, assuming steady state flow conditions in a
single layer soil with constant sorption and mass sink parameters.
PESTAN is most applicable in the portions of vadose zone located
between the bottom of the root zone and the water table.
The PESTAN model was found to be most appropriate for the evaluation
of the subsurface soils at the western parcel since it considers many
fate/transport properties, such as dispersion, sorption, and
degradation. The model also allows for evaluation of a contaminant
"front" as it passes through previously uncontaminated soil. In
addition, the timing of the subsurface soil's contribution to
groundwater contamination can be estimated from a transport model.
The PESTAN modeling indicates that, because of the low recharge and
relatively low solubilities of the compounds found on the western
parcel, most of the contaminants can exist in the subsurface soils at
very high concentrations and not contribute to groundwater so that the
groundwater protection standards are exceeded. In many instances, the
model indicates that leachate produced from the volume of subsurface
soil being modeled will reach a limiting concentration, which is a
function of the constituent's solubility in water, its rate of
degradation, and the depth of observation in the soil profile. At
this limiting leachate concentration, higher levels of contaminant in
the subsurface soil do not result in higher concentrations in the
resulting leachate, but rather result in a longer slug of contaminant
passing through a particular depth in the soil profile.
The PESTAN modeling, coupled with the results of the subsurface soil
investigation performed during the RI, indicate that the subsurface
soils on the western parcel would not contribute to groundwater
contamination at concentrations exceeding the groundwater protection
standards. Therefore, no remediation is deemed necessary for the
subsurface soils and no alternatives or cleanup goals are proposed for
the remediation of subsurface soil. Furthermore, since the
groundwater cleanup is expected to last for several decades and the
facility on the western parcel is inactive, further excavation on the
western parcel would not add significantly to the protectiveness of
the remedy.
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7.0 DESCRIPTION OF ALTERNATIVES
Two alternatives for the remediation of contaminated groundwater in
OU#1 at the THAN site were evaluated in the Feasibility Study Report
and listed in the Proposed Plan for the Site. These alternatives are
complete and address the remediation of all the media.
Table 9
Operable Unit #1 Alternatives
Alternative
Number
1
2
Medium
All Media
Soil
Groundwater
NAPL
Remedial Action
No Action
Vegetative Cover and
Institutional
Controls
Pump & Treatb
Pump & Incinerate0
Present-
Worth9
0
4.1
In $Millions
Pump & Treat of Groundwater would include Onsite
Treatment
Pump & Incineration of NAPL would include Off-site
Incineration
The assembled site-specific alternatives represent a range of distinct
waste-management strategies addressing the human health and
environmental concerns. Although the selected remedial alternative
will be further refined as necessary during the predesign phase, the
analysis presented below reflects the fundamental components of the
various alternatives considered feasible for this Site.
7.1 ALTERNATIVE No. 1 - No Action
The no action alternative is carried through the screening process as
required by the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP). This alternative is used as a baseline for
comparison with other alternatives that are developed. Under this
alternative, EPA would take no further action to minimize the impact
groundwater contamination has on the area. Groundwater contamination
would remain and possibly migrate. There is no cost associated with
this alternative since no additional activities would be conducted.
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7.2 ALTERNATIVE No. 2 - Pump and Treat
This alternative consists of a vegetative cover and associated
drainage controls for the soils. Institutional controls such as
fencing and deed restrictions would be implemented. Groundwater would
be extracted by pumping, treated onsite, and disposed of onsite by a
shallow infiltration gallery if a treatability study indicates this
method of disposal to be practical. If an onsite infiltration gallery
is not practical, the water will be disposed of off-site by the use of
an existing discharge permit to the local publicly-owned treatment
works (POTW) or an NPDES permit to discharge to the Flint River. The
NAPL would be extracted by pumping and incinerated off-site. The
present worth cost of this alternative is estimated at $4,100,000.
This alternative includes:
• Extraction and onsite treatment of groundwater
Extraction and off-site incineration of NAPL; and
• Vegetative cover over the contaminated area with institutional
controls.
Considering the hydrogeological characteristics of the Site (i.e.,
hydraulic conductivity of 10"7 cm/sec, heterogeneity of soils), it is
expected to take several pore volumes of groundwater before the
cleanup goals are met. It may be necessary to pump groundwater only
intermittently to achieve effective extraction. This will be
determined during the design phase based on the pump tests. The
extracted groundwater will be stored in an equalization tank from
which it would be pumped to a treatment system. The objective of
using the equalization tank is to dampen flow and loading variations
and to provide storage during times when the downstream treatment
system may be shut down.
Preliminary process flow diagrams for ultraviolet/oxidation treatment
is shown in Figure 9. The spent carbon which would be generated
during the polishing treatment step would either be regenerated or
disposed in an authorized facility. The treated water would be
reinjected onsite and/or discharged off-site with an NPDES permit or
to the City of Albany municipal sewers through a City permit. The
relative volumes of treated water that would be reinjected onsite or
discharged off-site would be determined during the Remedial Design
(RD) phase. The details of the reinjection system would also be
investigated during the RD phase.
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'_IQL!(J H'UIL-t
flAC
Acsorplion
Figure 9
Diagram of Ultraviolet/Oxidation Treatment Train
33
,
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The NAPL would be extracted and then treated in an off-site
incinerator. The remedial action objective for the NAPL.lens is its
removal. The"number of NAPL extraction wells that would be used is
not known at this time. It is likely that some extraction wells would
be used for extraction of both NAPL and groundwater. Preliminary
indications are that the total NAPL extraction rates would be very
small, ranging between 5 to 10 gallons per day. It is anticipated
that the pumping of NAPL would take place on an intermittent basis.
After the NAPL is extracted, it would be stored in a tank until ready
for final disposal. The NAPL may have to be shipped a long distance,
since a permitted incinerator does not currently exist near the Site.
Pursuant to the removal, the remaining total organochlorine pesticide
levels are less than 30 parts per million. A vegetative cover will be
placed on the western parcel. The cover would include clean,
compacted soil materials with natural vegetation on the top. Drainage
controls would be installed, so that the runoff would be diverted from
the Site. The permeability of the existing soil at the THAN property
is approximately 10"7 cm/sec, which would allow little infiltration.
The vegetative cover will be compacted so that the permeability of the
cover will be equivalent to the native Site soils. The vegetative
cover _will be inspected quarterly, at a minimum, and be maintained in
good condition.
8.0 SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES
This section of the ROD provides the basis for determining which
alternative provides the best balance with respect to the statutory
balancing criteria in Section 121 of CERCLA and in Section 300.430 of
the NCP. The major objective of the FS was to develop, screen, and
evaluate alternatives for the remediation of Operable Unit One at the
THAN site. The remedial alternatives selected from the screening
process were evaluated using the following nine evaluation criteria:
• Overall protection of human health and the environment.
• Compliance with applicable and/or relevant Federal or State
public health or environmental standards.
• Long-term effectiveness and permanence.
• Reduction of toxicity, mobility, or volume of hazardous
substances or contaminants.
• Short-term effectiveness, or the impacts a remedy might have on
the community, workers, or the environment during the course of
implementing it.
• Implementability, that is, the administrative or technical
capacity to carry out the alternative.
• Cost-effectiveness considering costs for construction, operation,
and maintenance of the alternative over the life of the project,
including additional costs should it fail.
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• Acceptance by the State.
• Acceptance by the Community.
The NCP categorizes the nine criteria into three groups:
(1) Threshold Criteria - overall protection of human health and
the environment and compliance with ARARs (or invoking a
waiver) are threshold criteria that must be satisfied in order
for an alternative to be eligible for selection;
(2) Primary Balancing Criteria - long-term effectiveness and
permanence; reduction of toxicity, mobility, or volume;
short-term effectiveness; implementability, and cost are
primary balancing factors used to weigh major trade-offs
among alternative hazardous waste management strategies; and
(3) Modifying Criteria - state and community acceptance are
modifying criteria that are formally taken into account after
public comment is received on the proposed plan and
incorporated in the ROD.
The selected alternative must meet the threshold criteria and comply
with all ARARs or be granted a waiver for compliance with ARARs. Any
alternative that does not satisfy both of these requirements is not
eligible for selection. The Primary Balancing Criteria are the
technical criteria upon which the detailed analysis is primarily
based. The final two criteria, known as Modifying Criteria, assess
the public's and the state agency's acceptance of the alternative.
Based on these final two criteria, EPA may modify aspects of a
specific alternative.
The following analysis is a summary of the evaluation of alternatives
for remediating the THAN Superfund Site under each of the criteria. A
comparison is made between each of the alternatives for achievement of
a specific criterion.
Threshold Criteria
8.1 Overall Protection of Human Health and the Environment
Alternative #1 would not contain or remediate the groundwater
contamination. Cleanup levels for groundwater would not be achieved
with Alternative #1, and Alternative #1 therefore would not provide
adequate protection of human health and the environment. Alternative
#2 would isolate the contamination from the surrounding uncontaminated
area and would prevent human and ecological contact. Alternative #2
would provide adequate overall protection of human health and the
environment.
8.2 Compliance with ARARs
The potential ARARs for this Site are listed in Table 10, 11, and 12.
Alternative #1 would not meet all ARARs because it would not meet
35
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MCLs. Alternative #2 would comply with all Federal or State ARARs.
Chemical specific ARARs would be met through compliance with the
groundwater protection standards (i.e., MCLs). During treatment, air
emissions from the Site would be monitored to ensure compliance with
the Clean Air Act. Fence-line air monitoring will be conducted to
ensure that contaminant concentrations do not exceed levels considered
to be safe for human health. If levels are exceeded, mitigative
procedures will be employed to prevent harmful levels of air emissions
from leaving the Site. RCRA design standards will be incorporated
into the remedial design of all remedial activities.
Primary Balancing Criteria
8.3 Long-Term Effectiveness and Permanence
Both Alternative #1 and #2 would provide long-term effectiveness and
permanence with respect to the contaminated soils at the Site, which
have already been addressed to a IxlO"6 risk level in the removal
action. Alternative #1 would not provide long-term effectiveness with
respect to groundwater contamination, however, because groundwater
contamination exceeds MCLs and would be unaddressed. Contaminated
groundwater could migrate off-site and be used as drinking water.
Alternative #2 would provide long-term effectiveness through limiting
the migration of contaminated groundwater through treatment of the
contaminated groundwater at the Site.
8.4 Reduction of Toxicitv. Mobility or Volume Through Treatment
Alternative #1 would not reduce mobility, toxicity or volume at the
source of the contamination. Alternative #2 would reduce mobility,
toxicity, and volume of groundwater contamination through withdrawal
and treatment. Toxicity and volume have been reduced by the current
removal action.
8.5 Short-Term Effectiveness
Alternative #1 would not require construction or excavation that would
cause a health risk to workers. However, Alternative #1 would be the
least effective in achieving the overall groundwater cleanup levels in
the shortest time period. Alternative #2 will require approximately
12 months to implement. No threshold toxicity criteria would be
exceeded by implementing Alternative #2 and the health risks to
remedial workers is unlikely, particularly when appropriate monitoring
and engineering controls are applied.
8.6 Implementability
The No Action alternative would require no action to implement.
Technological expertise, services, equipment and materials are
adequately available for the implementation of Alternative #2.
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TABLE 10
POTENTIAL CONTAMINANT-SPECIFIC ARARS
Standard, Requirement, Criteria, or Limitation
Citation
Description
Federal
Safe Drinking Water Act
National Primary Drinking Water Standards
National Secondary Drinking Water Standards
Maximum Contaminant Level Goals (MCLGs)
Clean Water Act
Ambient Water Quality Criteria
National Pollutant Discharge Elimination System
Permit Regulations
Underground Injection Control Regulations
National Pretreatment Standards
Clean Air Act
National Primary and Secondary Ambient Air Quality
Standards
40 USC Section 300
40 CFR Part 141
40 CFR Part 143
PL No. 99-339
100 Stat. 642 (1986)
33 USC Section 1261-1376
40 CFR Part 131 Quality
Criteria for Water, 1976, 1980,
1986
40 CFR Parts 122, 126
40 CFR Parts 144-147
40 CFR Part 403
42 USC Section 7401-7642
40 CFR Part 60
Establishes maximum contaminant levels (MCLs) which are health-based
standards for public water systems.
Establishes secondary maximum contaminant levels (SMCLs) which are
non-enforceable guidelines for public water systems to ensure the aesthetic
quality of the water.
Establishes drinking water quality goals set at levels of no known or
anticipated adverse health effects with an adequate margin of safety.
Requires the states to set ambient water quality criterin (AWQC) for water
quality based on use classifications and the criteria developed under
.Section 304(a) of the Clean Water Act.
Requires permits for the discharge of pollutants from any point source into
waters of the United States.
Provides for protection of underground sources of drinking water.
Sets standards to control pollutants which pass through or interfere with
treatment processes in publicly-owned treatment works or which may
contaminate sewage sludge.
Establishes standards for ambient air quality to protect public health and
welfare.
State
Georgia Department of Natural Resources
Environmental Protection Division; Water Quality
Control
Georgia Hazardous Site Response Act (HSRA)
Georgia Department of Natural Resources
Environmental Protection Division; Air Quality
Control
Chapter 391-3-6
Section 03
Chapter 391-3-1
Section 02
Establishes water quality standards and includes instream concentrations
for toxic priority pollutants.
Establishes State Super fund activities
Establishes air quality standards.
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TABLE II
PBELIMDURT ARABS FOB
CONTAMINANTS OP CONCERN POUND IN GKCUNDWATTO
Note*
Media
Gnniodvitcr
Ce«tJtiM*
AUrin
BUMM
*BHC
S-BHC
S-BHC
T^BHC
ChkmtKQHU
o-CUoidui
Chkmtfara (THM)
Cyanide
4.4--DDD
4.4--DDE
4.4'-DDT
1.2-DBinaMthuM (EDB)
Dkamba
1.4-DichlorobeoMne
lJ2-Didilon>propuie
DUdrin
DinoMb
EndMiil&oI
Eadrin
Ea*inAJd«h7mipunju>
Makthno
Mtthyl PmUiion
Z-lfaUi^iuphthiluK)
NtphtlulMM
4-Nitnjph«ool
2.«^-T
TMracfaJoratlHiM
!«3>4BTflcUorocHBl0DO
TrtcolOfWthfliM
Taxpton
Xykn, total
M
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TABLE IX
POTENTIAL ACTION-SPECIFIC ARABS
Standard, Requirement, Criteria, or
Limitation
Citation
Federal
Solid Waste Disposal Act (SWDA)
Criteria for Classification of Solid Waste Disposal
Facilities and Practices
Hazardous Waste Management Systems General
Identification and Listing of Hazardous Wastes
Standards Applicable to Generators of Hazardous
Waste
Standards Applicable to Transporters of
Hazardous Waste
Standards Applicable to Owners and Operators of
Hazardous Waste Treatment, Storage, and
Disposal Facilities
Occupational Safety and Health Act
Clean Air Act
National Ambient Air Quality Standards
Hazardous Material* Transportation Act
Hazardous Materials Transportation Regulations
Land Disposal Restrictions
Hazardous Waste Permit Program
42 USC Section 6901-6987
40 CFR Part 257
40 CFR Part 260
40 CFR Part 261
40 CFR Part 262
40 CF.R Part 263
40 CFR Part 264
20 USC Section 651-678
42 USC Section 7401-7642
40 CFR Part 50
49 USC Section 1801-1813
49 CFR Parts 107, 171-177
40 CFR 268
40 CFR Part 270
Description
Establishes criteria for use in determining which
solid waste disposal facilities and practices pose a
reasonable probability of advene effects on
health, and thereby constitute prohibited open
dumps.
Establishes procedure and criteria for modification
or revocation of any provision L> *0 CFR Parts
260-265.
Defines those solid wastes which are subject to
regulation as hazardous wastes under 40 CFR
Parts 263-266 and Parts 124, 270, and 271.
Establishes standards for generators of hazardous
waste.
Establishes standards which apply to persona
transporting hazardous waste within the VS. if
the transportation requires a manifest under 40
CFR part 262.
Entahlinhen standards which apply to the ntoragr
and handling of hazardous wastes.
Regulates worker health and safety.
Treatment technology standard for emission* to
air
•incinerators
•surface impoundments
•waste piles
•landfills
•fugitive emissions
Regulates transportation of hazardous materials.
Establishes a timetable for restriction of land
disposal of wastes and other hazardous materials.
Establishes provisions covering basic EPA
permitting requirements.
State
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Standard, Requirement, Criteria, or
Limitation
Georgia Department of Natural Boaoarcea
Environmental Protection Division; Water
Quality Control
Georgia Department of Natural Beaourcea
Environmental Protection Diviaion; Water
Quality Control (Continued)
Georgia Hazardoua Waate Management Act
Georgia Hazardous Site Response Act
Georgia Hazardous Waste Management Rules
Citation
Chapter 391-3-6
Section 06
Section 08
Section 10
Section 11
Code of Georgia, Title 12 •
Chapter 8, Article 3
Section 62
Section 66
Section 67
Section 69
Rules and Regulations of
the State of Georgia,
Title 391, Article 3,
Chapter 11
Description
Established tire filiform procedures and practices
to be followed relating to tike application for
issuance, modification, revocation, and reiasnance
and termination of permit* for the discharge of
any pollutant into the water* of the State.
Establishes the degree of waste water
pretreatment required and the uniform
procedures and practices to be followed relating to
the application for, and the issuance or revocation
of, any pollutant into a publicly-owned treatment
works and then into the waters of the State.
followed for the determination or categorization of
industrial users and requests for variances for
fundamentally different factors.
Establishes the degree of pollutant treatment
required and the uniform procedures and
practices to be followed relating to the application
for, and the issuance or revocation of, permits for
the discharge of pollutants into land disposal or
land treatment systems and then into the waters
of the State.
Defines the mining designated hazardous waste
based on the federal act; 40 CFR Section 261.
Establishes the need for a hazardous waste
facility permit.
Establishes standards for Hazardous Waste in
iy«n«it to be (iccompanjpd by * manifefft
Establishes that variances may be granted from
the requirements of this law unless such
variances are prohibited by the federal act or
standards.
Establishes State Superfund Activities.
Establishes the policies, procedures, requirements,
and standards to implement the Georgia
Hazardous Waste Management Act. •
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8.7 Cost
Alternative #-1 would not require any additional cost. The present
worth cost of Alternative #2 is estimated to be $4,100,000. These
costs include operation and maintenance during the implementation of
the alternative as well as post remediation monitoring. While
Alternative #2 is more costly, the added effectiveness justifies the
additional cost.
Modifying Criteria
8.8 STATE ACCEPTANCE
The State of Georgia, as represented by the Georgia Environmental
Protection Division (GaEPD), has been the support agency during the
Remedial Investigation and Feasibility Study process for the T H
Agriculture & Nutrition site. In accordance with 40 CFR 300.430, as
the support agency/ GaEPD has provided input during this process. The
State of Georgia, as represented by GaEPD, has concurred with the
selected remedy.
8.9 COMMUNITY ACCEPTANCE
The majority of the community concern raised with respect to this Site
are related to the removal action in which low-temperature thermal
desorption is planned. Most d'f the community concerns expressed over
the proposed groundwater remedy (alternative #2} relate to the length
of time the remediation is expected to take (30+ years). Based on the
comments expressed at the September 24, 1992 public meeting and the
written comments received during the comment period; however, it
appears that the Albany community generally agrees that a pump and
treat system is necessary at this Site and supports Alternative #2.
9.0 SUMMARY OF SELECTED REMEDY
Based upon consideration of the requirements of CERCLA, the NCP,
the detailed analysis of alternatives and public and state
comments, EPA has selected a remedy for Operable Unit #1 of the Site.
The selected remedy provides for the following:
1. No action with respect to soils because the removal action has
fully addressed the threat posed by the contaminated soils;
2. Pumping and onsite treatment by ultraviolet/oxidation with
granular activated carbon as a polishing step for groundwater if
needed;
3. Pumping and off-site incineration of NAPL;
4. Institutional controls.
5. The vegetative cover stalled by the removal action will be
inspected quarterly, at a minimum, and be maintained in good
condition.
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At the completion of this remedy, the risk associated with this Site
has been calculated at 10-[4] which is determined to be protective of
human health-and the environment. The total present worth cost of the
selected remedy, Alternative #[2], is estimated at $[4,100,000].
A. GROUNDWATER REMEDIATION
Groundwater remediation will address the contaminated groundwater in
the residuum and the upper Ocala aquifers at the Site. Groundwater
remediation will include extraction of contaminated groundwater,
treatment, and discharge to an onsite infiltration gallery.
A.I. The manor components of qroundwater remediation to be
implemented include:
• Fencing of the Site and treatment facility;
• Extraction and onsite treatment of groundwater by
ultraviolet/oxidation treatment with granulated carbon adsorption
as a polishing step if needed;
• Extraction and off-site incineration of NAPL;
• Drainage controls to divert runoff from Site;
• Maintenance of the vegetative cover installed by the removal
action; and,
• Institutional controls, such as deed and land-use restrictions.
Air emissions during the cleanup will be monitored to ensure safety
of workers and residents near the Site.
A.2. Extraction, Treatment, and Discharge of Contaminated
Groundwater
Contaminated groundwater will be pumped from the surficial aquifer
for on-site treatment. A treatability study will be conducted
during the Remedial Design phase of this project to determine if an
infiltration gallery is feasible at the Site. If an infiltration
gallery is feasible, the treated water will be discharged to the
infiltration gallery. If the infiltration gallery is not feasible,
the treated water will be discharged to a local publicly-owned
treatment works (POTW). If a POTW permit is unattainable, a
National Pollutant Discharge Elimination System (NPDES) permit to
discharge the treated groundwater to a nearby surface water body
would be pursued. Pumping operations may need to be done only
intermittently to achieve maximum withdrawal. The withdrawn
groundwater will be stored in an equalization tank from which it
would be pumped to a treatment system. The equalization tank will
provide storage during times when a downstream treatment system may
be shut down.
During the remedial design for this project, treatability studies
would be conducted to determine the effectiveness of
ultraviolet/oxidation treatment on the extracted groundwater. Such
treatability studies will concentrate on determining if the site
42
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soil, which has a low permeability, will inhibit surface recharge.
Additional piezometers may be necessary during Remedial Design to
determine if the infiltration gallery could cause any groundwater
flow down to the lower aquifers instead of increasing flow across
the Site. Ultraviolet/oxidation treatment would be utilized
(possibly in combination with granular activated carbon adsorption
treatment as a polishing step) for groundwater treatment if it is
proven effective by these treatability studies in reducing the
contamination in the extracted water. Other treatment technologies
for groundwater such as granular activated carbon by itself may be
found to be effective and may be implemented if the time frame for
remediation can by retained. Final methods would be determined
during the remedial design of the cleanup remedy. The spent carbon
would be disposed of at a regulated facility or regenerated.
The number of NAPL extraction wells that would be used is not known
at this time. It is likely that some extraction wells would be used
for extraction of both NAPL and groundwater. Preliminary
indications are that the total NAPL extraction rates would be very
small, anticipated to be less than five-to-ten gallons per day. It
is anticipated that the pumping of NAPL could take place on an
intermittent basis. After the NAPL is extracted, it would be stored
in a tank until ready for final disposal. The NAPL may be shipped a
long distance, since a permitted incineration facility does not
currently exist near the THAN Property.
A.3. Performance Standards
a. Treatment Standards
Groundwater shall be treated until the following
maximum concentration levels are attained at the
wells designated by EPA as compliance points.
DDT 0.027 mg/L
Toxaphene 0.003 mg/L
alpha-BHC 0.0014 mg/L
beta-BHC 0.0051 mg/L
Aldrin 0.00054 mg/L
Dieldrin 0.00057 mg/L
EDB 0.00005 mg/L
b. Discharge Standards
Discharges from the groundwater treatment system
shall comply with all ARARs, including, but not
limited to, substantive requirements of the NPDES
permitting program under the Clean Water Act, 33
U.S.C. { 1251 et seq., and all effluent limits
established by EPA.
c. Design Standards
The design, construction and operation of the
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groundwater treatment system shall "be conducted
in accordance with all ARARs, including but not
limited to the RCRA requirements set forth in 40
- C.F.R. Part 264 (Subpart F).]
B. Compliance Monitoring
Groundwater and surface water monitoring shall be conducted at
this site. After demonstration of compliance with Performance
Standards, the Site including soil and groundwater shall be
monitored for five years. If monitoring indicates that the
Performance Standards set forth in Paragraph A.3(a) are being
exceeded at any time after pumping has been discontinued,
extraction and treatment of the groundwater will recommence
until the Performance Standards are once again achieved. If
monitoring of the treated soil indicates Performance Standards
• have been exceeded, the effectiveness of the source control
component will be re-evaluated.
Alternative #2 will achieve substantial risk reduction through
treatment of the principal threat at Operable Unit #1 of the THAN
Superfund Site. The principal threat is the NAPL lens and the
groundwater contamination since the soils have been removed from the
western parcel in the ongoing removal action.
Pursuant to the removal, the remaining total organochlorine pesticide
levels are less than 30 parts -per million. The area excavated during
the removal action will be backfilled with clean fill and revegetated.
Quarterly monitoring and maintenance of this cover will occur. The
vegetative cover will be compacted so that the permeability of the
cover will be equivalent to the native Site soils. The vegetative
cover will be inspected quarterly, at a minimum, and be maintained in
good condition. Institutional controls, such as deed restrictions,
will be established to preclude usage of groundwater and minimize land
use.
Air emissions from the Site will be monitored to ensure compliance
with the Clean Air Act. Air monitoring will be conducted to ensure
that gontaminant concentrations do not exceed levels considered to be
safe for human health. If levels are exceeded, mitigative procedures
such as dust suppression or vapor capture will be employed to prevent
harmful levels of air emissions from leaving the Site.
The selected alternative for Operable Unit #1 of the THAN site is
consistent with the requirements of Section 121 of CERCLA and the
National Contingency Plan. The selected alternative will reduce the
mobility, toxicity, and volume of contaminated groundwater at the
Site. In addition, the selected alternative is protective of human
health and the environment, will attain all Federal and State
applicable or relevant and appropriate requirements, is cost-effective
and utilizes permanent solutions to the maximum extent practicable.
The selected alternative for OU #1 is consistent with previous and
projected remedial actions at the Site.
Based on the information available at this time, the selected
alternative represents the best balance among the criteria used to
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evaluate remedies, especially in light of the ongoing removal action.
Alternative #2 is believed to be protective of human health and the
environment,-will attain ARARs, would be cost effective, and would
utilize permanent solutions and alternative treatment technologies or
resource recovery technologies to the maximum extent practicable.
The goal of this remedial action is to restore the groundwater in the
residuum and upper Ocala aquifers to its beneficial use (as drinking
water) at this Site. The cleanup goals for this remedial action are
listed in Table 8 in this ROD. Based on information obtained during
the remedial investigation, and the analysis of all remedial
alternatives, the selected remedy should be able to achieve this goal.
Groundwater contamination may be especially persistent in the
immediate vicinity of the contaminants' source, where concentrations
are relatively high. The ability to achieve cleanup goals at all
points throughout the area of attainment, or plume, cannot be
determined until the extraction system has been implemented, modified
as necessary, and plume response monitored over time. If the selected
remedy cannot meet the specified remediation goals, at any or all of
the monitoring points during implementation, the contingency measures
and goals described in this section may replace the selected remedy
and goals for these portions of the plume. Such contingency measures
will, at a minimum, prevent further migration of the plume and include
a combination of containment technologies, typically, groundwater
extraction and treatment and institutional controls. These measures
are considered to be protective of human health and the environment,
and are technically practicable under the corresponding circumstances.
The selected remedy will include groundwater extraction and
monitoring, during which the system's performance will be carefully
monitored on a regular basis and adjusted as warranted by the
performance data collected during operation. Modifications may
include any or all of the following:
• at individual wells where cleanup goals have been attained,
pumping may be discontinued;
• alternating pumping at wells to eliminate stagnation points;
• pulse pumping to allow aquifer equilibration and encourage
adsorbed contaminants to partition into groundwater; and
• installation of additional extraction wells to facilitate or
accelerate cleanup of the contaminant plume.
To ensure that cleanup goals continue to be maintained, the aquifer
will be monitored at least annually for five years following
discontinuation of groundwater extraction for those wells where
pumping has ceased.
The decision to invoke any or all of these measures may be made during
a periodic review of the remedial action, which will occur at least
every five years in accordance with CERCLA section 121 (c) and the
NCP.
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10.0 STATUTORY DETERMINATION
Under its legal authorities, EPA's primary responsibility at Superfund
sites is to undertake remedial actions that achieve adequate
protection of human health and the environment. In addition, Section
121 of CERCLA establishes several other statutory requirements and
preferences. These specify that, when complete, the selected remedial
action for this Site must comply with applicable or relevant and
appropriate environmental standards established under Federal and
State environmental laws. The selected remedy also must be
cost-effective and utilize permanent solutions and alternative
treatment technologies or resource recovery technologies to the
maximum extent practicable. Finally, the statute includes a
preference for remedies that employ treatment that permanently and
significantly reduce the volume, toxicity, or mobility of hazardous
wastes as their principal element. The following sections discuss how
the selected remedy meets these statutory requirements.
10.1 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
The selected remedy protects human health and the environment through
isolating and treating a principal threat remaining at Operable Unit
#1 of the Site, the contaminated groundwater and NAPL plume. The
selected remedy provides protection of human health and the
environment by eliminating, reducing, and controlling risk through
treatment, engineering controls and/or institutional controls. The
surface and subsurface soils at Operable Unit #1 of the Site are not
deemed to be a threat, since the surface soils have been removed
previously and site-specific PESTAN modeling indicates that the
subsurface soils are not considered a source of contamination to
groundwater.
10.2 ATTAINMENT OF THE APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENTS (ARARs)
Remedial actions performed under CERCLA must comply with all
applicable or relevant and appropriate requirements (ARARs). All
alternatives considered for the THAN site were evaluated on the basis
of the degree to which they complied with these requirements. The
selected remedy was found to meet or exceed all ARARs, including those
listed in Tables 10, 11, and 12, and the following:.
Clean Air Act
Air emissions from the remedial activities at the Site, including
thermal treatment, would be monitored to ensure compliance with the
substantive requirements of the Clean Air Act. Air monitoring will be
conducted to ensure that contaminant concentrations do not exceed
levels considered to be safe for human health. If levels are
exceeded, mitigative procedures such as dust suppression or vapor
capture will be employed to prevent harmful levels of air emissions
from leaving the Site.
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Chemical-Specific ARARs
Maximum Contaminant Levels (MCLs) and non-zero MCLGs (where each is
available) are the Groundwater Protection Standards set out in Table 8
of this ROD as the remedial action goals.
Waivers
Section 121 (d)(4)(C) of CERCLA provides that an ARAR may be waived
when compliance with an ARAR is technically impracticable from an
engineering perspective. No waivers are necessary with respect to the
selected remedy.
Other Guidance To Be Considered
Other Guidance To Be Considered (TBCs) include health based advisories
and guidance. TBCs have been utilized in estimating incremental
cancer risk numbers for remedial activities at the sites. The risk
numbers are evaluated relative to the normally accepted point of
departure risk range of IxlO'4 to IxlO"6.
10.3 COST EFFECTIVENESS
The estimated cost of EPA's selected remedy is $4,100,000. Cost
effectiveness is determined by comparing the cost of all alternatives
being considered with their overall effectiveness to determine whether
the costs are proportional to the effectiveness achieved. EPA
evaluates the incremental cost of each alternative as compared to the
increased effectiveness of the remedy. The selected remedy,
Alternative #2, does cost more than the no action alternative;
however, effectiveness achieved by Alternative #2 justifies the higher
cost. The remedy is considered cost effective.
10.4 UTILIZATION OF PERMANENT SOLUTIONS TO THE MAXIMUM
EXTENT PRACTICABLE
EPA believes the selected remedy is the most appropriate cleanup
solution for the THAN site and provides the best balance among the
evaluation criteria for the remedial alternatives evaluated. This
remedy provides effective protection in both the short-term and
long-term to potential human and environmental receptors, is
implementable, and is cost-effective.
10.5 PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT
The statutory preference for treatment will be met because the
selected remedy treats the highly contaminated NAPL and groundwater
which are the principal threats posed by che Site.
11.0 DOCUMENTATION OF SIGNIFICANT CHANGES
The Proposed Plan was released for public comment in September 1992.
The plan identified alternative #2, pump and treat through
ultraviolet/oxidation with discharge to a POTW, as the preferred
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alternative for groundwater remediation. The selected remedy calls
for onsite reinjection of the treated groundwater instead of discharge
to a POTW. Onsite reinjection was described as an alternative in the
Feasibility Study. During the public comment period, new information
indicated that the State of Georgia would allow a shallow,
infiltration gallery onsite for disposal of the treated groundwater.
Therefore, EPA and the State decided to select discharge of the
treated groundwater onsite to an infiltration gallery onsite if a
treatability study deems such a process to be practical. If an onsite
infiltration gallery is not practical, treated groundwater will be
discharged to a POTW or discharged to a local surface water body
through and NPDES permit, as originally provided in the Proposed Plan.
Additionally, in consultation with the Georgia Environmental
Protection Division, the vegetative cover for the Site which is
described in the Proposed Plan will be compacted so that the
permeability of the cover will be equivalent to the native Site soils.
The vegetative cover will be inspected quarterly, at a minimum, and be
maintained in good condition.
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VICI.
II I
1C
C4.I I
205 Butler Street, S.E., Suite 1252, Atlanta, Georgia 30334
Joe 0. Tanner, Commissioner
Harold F. Reheis, Director
Environmental Protection Division
May 17, 1993
Mr. Richard D. Green
Associate Director
Superfund and Emergency Response
U.S. Environmental Protection Agency
Region IV
345 Courtland Street, N.E.
Atlanta, Georgia 30365
Dear Mr. Green:
RE: Revised Draft Record of Decision
TH Agriculture & Nutrition Site
Operable Unit One
Albany, Dougherty County, Georgia
May 12, 1993
The Georgia Environmental Protection Division has reviewed the above referenced
document and concurs with the Record of Decision and the Environmental Protection Agency's
selected remedial action for the TH Agriculture & Nutrition Site.
If we can be of further assistance to you, please contact Bill Mundy at (404) 656-7802.
Sincerely,
Harora F. Reheis
Director
HFR/sse
f:\usertoe\OuiiVgrtca. Itr
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APPENDIX B
CONCURRENCE LETTERS
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