United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R06-92/076
September 1992
PB93-964207
SEPA Superfund
Record of Decision:
Gulf Coast Vacuum Services
(Operable Unit 1), LA
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NOTICE
The appendices listed in the index that are not found in this document have been removed at the request of
the issuing agency. They contain material which supplement but adds no further appticatte information to
the content of the document All supplemental material is, however, contained in the administrative record
for this site.
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•2-101
EPORT DOCUMENTATION 1. REPORT NO. a
PAGE EPA/ROD/R06-92/076
Title and SuMKIe
SUPERFUND RECORD OF DECISION
3ulf Coast Vacuum Services (Operable Unit 1) , LA
Second Remedial Action - Subsequent to follow
Author)*)
Performing Organization Name and Add new
Sponsoring Organization Name and Addims
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
3. Recipient's Accession No.
S. Report Date
09/30/92
6.
8. Performing Organization RepL No.
10. Project/Task/Work Unit No.
11. Contract(C) or Grant(G) No.
(C)
13. Type of Report & Period Covered
800/000
14.
, Supplementary Notes
PB93-964207
Abstract (UmH: 200 word*)
The 12.8-acre Gulf Coast Vacuum Services site is a former vacuum truck and oil field
plant in Vermilion Parish, Louisiana. Land use in the area is predominantly
agricultural. Ten residences within one-half mile of the site use the ground water
below the Chicot Aquifer for drinking water and irrigation. The site is bounded to
the north and west by pasture land, and to the east and south by another Superfund
site, the D. L. Mud Superfund site, and the LeBoeuf Canal. From 1969 to 1980, several
owners used the site as a trucking terminal to transport various metals, including
waste generated from oil exploration and production activities. The site includes two
open waste pits-specifically, the Washout Pit and West Pit-and two vegetated areas,
known as the Former West Pit. The Former West Pit adjoins the West Pit to the south
and was used for disposal. Other site features include vertical storage tanks,
horizontal tanks, and three underground storage tanks. During site operations,
unpermitted disposal of primarily oil industry-related waste occurred in the unlined
pits, ditches, and site soil. EPA investigations, which started in 1980, led to three
(See Attached Page)
LA
. Document Analysis a. Descriptors
Record of Decision - Gulf Coast Vacuum Services (Operable Unit 1),
Second Remedial Action - Subsequent to follow
Contaminated Media: soil, sediment, sludge, gw
Key Contaminants: VOCs (benzene), other organics (PCBs, naphthalene), metals
(arsenic, barium)
b. Identifiers/Open-Ended Terms
c. COSATI Reid/Group
. Availability Statement
19. Security Class (This Report)
None
20. Security Class (This Page)
None
21. No. of Page*
92
22. Price
>ANSI-Z39.18)
See Instructions on Reverse
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-35)
Department of Commerce
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A/ROD/R06-92/076
.If Coast Vacuum Services (Operable Unit 1) , LA
cond Remedial Action - Subsequent to follow
stract (Continued)
moval actions at the site from 1990 to 1992. These removal actions addressed
ntaminant overflow caused by critical rainfall, from both the West Pit and Washout Pit,
ovided for construction of a secondary containment levee west of the West Pit; pumping,
eatment, and discharge of wastewater from the two pits; and fencing the area. This ROD
dresses the final remedial action for all of the sources of contamination as OU1.
ture RODS will address the contaminated overflow and the migration from offsite pits,
OU2. The primary contaminants of concern'affecting the soil, sediment, pit sludge,
d ground water are VOCs, including benzene; other organics, including PCBs and
phthalene; and metals, including arsenic and barium.
e selected remedial action for this site includes consolidation and onsite incineration
approximately 12,000 cubic yards of organic- and inorganic-contaminated waste pit
udge and 7,950 cubic yards of associated soil, 12,000 gallons of tank contents, and
5 cubic yards of tank sludge, followed by stabilization/solidification of the residual
h, if necessary; stabilizing and solidifying onsite approximately 18,900 cubic yards of
te inorganic-contaminated soil, and 600 cubic yards of surface sediment; disposing of
1 of these residuals in an onsite excavation and covering the area with a clay cover;
lowing ground water to naturally attenuate; monitoring ground water in the upper and
wer aquifers; conducting onsite and offsite air monitoring; treating air emissions as
eded; and implementing institutional controls, including deed restrictions. The
timated present worth cost for this remedial action is $13,026,000, which includes an
nual O&M cost of $18,050 for 30 years.
RFORMANCE STANDARDS OR GOALS:
emical-specific soil, sediment, and pit sludge goals are based on SDWA MCLs, and
elude arsenic 16 ug/kg; barium 5,400 mg/kg; and benzene 0.66 mg/kg. Ground water is
pected to meet the National Primary Drinking Water and health-based standards.
emical-specific goals for ground water are based on SWDA MCLs and MCLGs, and include
senic 50 ug/1 (MCL); barium 2,000 ug/1 (MCL); cadmium 5 ug/1 (MCL); total chromium
0 ug/1 (MCL); total mercury 2 ug/1 (MCL); and benzene 5 ug/1 (MCL).
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RECORD OF DECISION
GULF COAST VACUUM SERVICES
VERMILION PARISH, LOUISIANA
FINAL SOURCE ACTION
OPERABLE UNIT 1
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
SEPTEMBER 1992
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RECORD OF DECISION
CONCURRENCE DOCUMENTATION
FOR THE
GULF COAST VACUUM SERVICES SDPERFUND SITE
FINAL SOURCE ACTION, OPERABLE UNIT NUMBER 1
Kathleen Lohry
site Remedial Project Manager'
Nelly Shiver"
Office of Regional counsel
Site Attorney
Stephen Gilrein, Chief
ALNM section 6H-SA
Carl Edlundj
Superfund
Chief
ranch 6H-S
Barbara Greenfield
Associate Regional Counsel
Waste Branch, 6C-W
George Alexander^ Jr.
Regional Counsel 6C
£
Allyn M. Davis
Hazardous Waste Management
Division 6H
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DECLARATION
GULF COAST VACUUM SERVICES
RECORD OF DECISION
FINAL SOURCE ACTION, OU1
SEPTEMBER 1992
Statutory Preference for Treatment as a
Principal Element is Met
and Five-Year Review is Required
SITE NAME AND LOCATION
Gulf Coast Vacuum Services
Vermilion Parish, Louisiana
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for
Operable Unit No. 1, Final Source Action, for the Gulf Coast Vacuum
Services site (the site) in Vermilion Parish, Louisiana, which was
chosen in accordance with the Comprehensive Environmental Response,
Compensation and Liability Act of 1980 (CERCLA), as amended by the
Superfund Amendments and Reauthorization Act of 1986 (SARA) and, to
the extent practicable, the National Oil and Hazardous Substances
Pollution Contingency Plan (NCP). This decision is based on the
administrative record file for this site.
The State of Louisiana concurs with the selected remedy.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this
site, if not addressed by implementing the response action selected
in this Record of Decision, may present an imminent and substantial
endangerment to public health, welfare, or the environment.
DESCRIPTION OF THE SELECTED REMEDY
There are two operable units for the site. This Record of Decision
is for Operable Unit No. 1, Final Source Action, which provides the
long-term remedial actions for all of the sources of contamination
at the site. The areas addressed include the pit sludges and
associated soils, buried pits, tank contents, site soils and
sediments and the ground water. A separate Record of Decision was
developed for Operable Unit No. 2, Interim Source Action, which is
a limited action alternative to address contaminated overflow and
off-site migration from two open pits on-site.
The remedies for the contaminated pit sludges and associated soils,
tank contents, buried pits, site soils and sediments address the
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minimizing potential exposure by way of ingestion, inhalation or
direct contact with contaminants and by reducing the potential for
the soil and sludge to act as a continued source of ground water
contamination. Contaminant levels above remedial action objectives
will be addressed: 16 ppm arsenic; 5400 ppm barium; .66 ppm
benzene; 3 ppm Total Carcinogenic PAHs (expressed as B(a)P
equivalents) ; and to a Hazard Index of 1 for the Total Non-
carcinogenic PAHs. Institutional controls and a long-term
monitoring program for ground water will prevent human exposure to
the contaminated ground water for as long as the ground water
contaminant concentrations exceed drinking water quality criteria.
The processes of natural attenuation and dilution will remediate
this contamination.
The major components of the selected remedy include:
- On-site incineration followed by on-site stabilization (if
necessary) and disposal of the ash of the organic and
inorganic-contaminated pit sludges, associated soils and tank
contents;
- On-site stabilization and disposal of the inorganic-
contaminated site soils and sediments;
- Institutional controls and long-term monitoring of ground
water.
The estimated total cost of this remedy (present worth) is
approximately $13,026,000.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the
environment, complies with Federal and State requirements that are
legally applicable or relevant and appropriate to the remedial
action, and is cost-effective. This remedy utilizes permanent
solutions and alternative treatment technologies, to the maximum
extent practicable, and satisfies the statutory preference for
remedies that employ treatment that reduces toxicity, mobility, or
volume as a principal element.
Because this remedy will leave hazardous substances remaining on-
site [i.e., stabilized material] a review will be conducted five
years after commencement of remedial action to ensure that the
remedy continues to provide adequate protection of public health
anefl welfare! and the environment.
B.CP. Wynne i Date
Regional Administrator
Region 6
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TABLE OF CONTENTS
RECORD OF DECISION
TABLE OF CONTENTS
PAGE NO
I. Site Name, Location, and Description 1
II. Site History and Enforcement Activities 4
III. Highlights of Community Participation 6
IV. Scope and Role of Response Action 7
V. Summary of Site Characteristics 8
A. Regional Geology " 8
B. Area Soils 8
C. Regional Hydrogeology 8
D. Site Hydrogeology 12
E. Exploratory Drilling and Water 12
Level Observation
F. Nature and Extent of Contamination 14
1. Pit Sludges and Associated Soil 15
2. Storage Tanks 16
3. Site Soils and Sediments 18
4. Ground water 19
VI. Summary of Site Risks 21
A. Risk Assessment Description 21
B. Human Health Risks 22
C. Identification of Chemical of Concern 22
D. Exposure Assessment 23
1. Current Land Use and Exposure Pathways 23
2. Future Land Use and Onsite Conditions 27
3. Exposure to Soil 27
4. Exposure to Homegrown Vegetables, 27
Beef and Milk
5. Exposure to Contaminants in Air 27
6. Exposure to Contaminants in Ground water 28
7. Exposure to Contaminants in Surface Water 2 8
and Sediments
8. Exposure to Contaminants in Sludge 31
E. Toxicity Assessment 35
F. Human Health Risk Characterization 37
1. Current Risk Characterization 37
2. Future Risk Characterization 38
3. Risks from Dioxins 38
4. Evaluation of Lead 38
G. Uncertainties Associated with Human Health
Risk Calculations 38
H. Central Tendencies 38
I. Ecological Risks 41
VII. Remedial Action Goals 50
VIII. Description of Alternatives 55
A. Sludges, Associated Soils and Tank Contents 56
Remedial Action Alternatives
1. Common Elements 58
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2. No Action 58
3. Excavation On-Site 59
Stabilization/Solidification
4. Excavation Onsite Incineration 61
5. Excavation Offsite Incineration 62
B. Site Soils and Sediments Remedial Action 63
Alternatives
1. Common Elements 64
2. No Action 65
3. Excavation, Stabilization, Onsite 65
Disposal
C. Ground water Remedial Action Alternatives 66
1. No Action 69
2. Ground Water Extraction ' 70
IX. Summary of Comparative Analysis of Alternatives 71
X. The Selected Remedy 81
XI. Statutory Determinations 82
A. Protection of Human Health and 82
the Environment
B. Compliance with ARARs 83
C. Cost-Effectiveness 84
D. Utilization of Permanent Solutions 85
and Treatment
E. Preferences for Treatment as a
Principal Element 86
XII. Documentation of Significant Changes
86
Appendix I
Appendix II
Appendix III
Appendix IV
Responsiveness Summary
Revised Cost Estimates
Risk Assessment Background
Administrative Record Index
Louisiana Concurrence Letter
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DECISION SUMMARY
I. LOCATION AND DESCRIPTION
The Gulf Coast Vacuum (GCV) Site was a vacuum truck and oilfield
drilling mud plant operation from approximately 1969 to 1980.
During the period that the facility was in operation, unpermitted
disposal of organic and inorganic-contaminated materials, primarily
oil industry-related waste, occurred in several open pits.
The Gulf Coast Vacuum site is located 3.5 miles southwest of the
town of Abbeville in Vermilion Parish, Louisiana, on Parish Road
P-7-31 (Figure l). The site occupies 12.8 acres in an agricultural
area.
The site is situated in the low-lying f latland of the Atlantic Gulf
Coastal Plain. The apparent natural relief across the site is
approximately six feet, trending from fourteen feet Mean Sea Level
(MSL) at the southeastern property to eight feet MSL at the
northwestern boundary. The site is bounded to the north and west
by pasture land and to the east and south by the D.L. Mud Superfund
site and the LeBoeuf Canal (Figure 2).
The most outstanding physical features of the site are two open
waste pits, designated the Washout Pit and the West Pit, and a
mounded area covered with vegetation designated the Former West Pit
(Figure 2). The Former West Pit adjoins the West Pit to the south
and apparently was used for disposal, but was subsequently filled
in and now supports a vegetative cover. This area is currently the
highest point on the site at approximately 18.5 feet MSL. To the
immediate west of the West Pit is a bermed area designated the
Secondary Containment pit. This pit was constructed in March 1990,
by the EPA Region 6, Emergency Response Branch, as part of a
removal action to collect overflow from the West Pit. There are
two other areas of concern that are covered by vegetative growth.
The areas appear to have been sludge pits which were subsequently
covered with soil. They can be seen on the 1974 aerial photos
included in the administrative record. One of these buried pits is
located to the east of the West Pit (under the aboveground storage
tank) . Another area is located southeast of the Washout Pit and is
designated the Southeast area.
Other site features, include four above ground vertical storage
tanks, one above ground horizontal tank and three underground
storage tanks. There are also three relatively open areas,
designated the East and West Site Fields and the Northeast Area,
located in the northern part of the site property that were also
used for disposal of oilfield-related wastes and possibly other
types of waste. In addition, there are several buildings still
present at the site that were constructed during the operation of
the facility and used as office buildings and as equipment
maintenance areas.
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Surface water drainage across the northern portion of the site is
generally to the north. Drainage across this area discharges to
local ditches that flow into the Coulee Galleque which eventually
flows into the Abbeville Canal. The canal along the southern
property boundary carries drainage from the southern portion of the
site eastward to the LeBouef Canal. The LeBouef Canal is to the
east of the site and trends in a northeast, southwest direction.
Nearest the site, this canal is segmented into three sections by
two eastern bridges. The LeBouef Canal was constructed for
irrigation purposes and previously drained into the Vermilion
River, located 1.5 miles east of the site. Currently, it only
contains water after a rain storm.
Areas adjacent to the site are currently used as pasture land for
grazing cattle and for other agricultural uses, predominantly rice
and soybean crop raising. A review of historical photographs also
indicates that past and current adjacent land use to be
predominantly agricultural. Immediately south and east of the site
is the D.L. Mud Superfund site, which is being evaluated
separately. Ten residences are located within 1/2 mile of the site
on Parish Road P-7-31 and Route 335.
The current potential use of the ground water are drinking water
and irrigation. A study of the residential wells in the site
vicinity indicates that residential well depths range from 80 to
230 feet below ground surface. The homes outside the corporate
limits of Abbeville and within the town of Perry get their drinking
water supply from private wells. Approximately 39 private wells
are located in the vicinity of the site. Of these 39 wells only 20
are listed as being used for domestic water supply.
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES
The Gulf Coast Vacuum site is part of a 25 acre parcel of land used
as a trucking terminal for the transportation of various materials,
including primarily wastes generated from oil exploration and
production. Unpermitted disposal occurred in the unlined pits,
ditches and site soils during operation. The original parcel was
divided in 1980 into what now is known as the Gulf Coast Vacuum
site and the D.L. Mud Superfund site.
The Gulf Coast Vacuum site operated from 1969 to 1984. From 1969
to 1975 it was owned and operated by Lafayette Highway. Gulf
Coast Pre-Mix Mud Services purchased the facility in 1975 and ran
the operation until 1979 when it merged with Gulf Coast Pre-Mix
trucking to form G.H. Drilling Fluid Inc. The company name was
changed to G.H. Fluids Services, which owned and operated the site
until 1980, when the parcel was divided. The trucking operation
and 12.78 acres were sold to Gulf Coast Vacuum Services which
operated the site until it declared bankruptcy in 1984. The
remaining part of the 25 acres parcel is now known as the D.L. Mud
Superfund site.
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A citizen's complaint through the Vermilion Association for
Protection of the Environment (VAPE) led to site identification by
EPA on June 27, 1980. As a result, an EPA Field Investigation Team
(FIT) conducted a preliminary assessment and preliminary sampling
inspection in July and September of 1980, respectively. A more
detailed sampling program was conducted by the EPA Technical
Assistance Team (TAT) in July 1985. An Expanded Site Inspection
(ESI) was performed in 1987 by the FIT. The site information and
sampling data collected in the ESI were used to determine if the
site posed a significant environmental and human health risk. The
site was proposed for inclusion on the National Priorities List
(NPL) in June 1988. In March 1989, pursuant to Section 105 of the
Comprehensive Environmental Response, Compensation, and Liability
Act, as amended, (CERCLA), 42 U.S.C. 9605, and became qualified for
investigation and remediation under CERCLA.
In 1988, EPA identified approximately 370 potentially responsible
parties (PRPs) for the site. In August of 1989, EPA Region 6
issued a General Notice letter to these PRPs regarding potential
liability and a request for information. Special Notice letters
were then issued to 153 PRPs in December of 1989. The Special
Notice letter requested that the PRPs voluntarily perform or
finance a Remedial Investigation/Feasibility Study (RI/FS). All of
the PRPs given notice either did not respond to the Special Notice
letter or declined the opportunity to conduct or finance the RI/FS
for the site.
EPA has conducted three removal actions at the site. Due to heavy
rainfall in the area, on March 20, 1990, the EPA, Region 6,
Emergency Response Branch (ERB) began a Removal Action to address
contaminated overflow from both the West Pit and the Washout Pit.
During the Removal, a secondary containment levee along the west
side of the West Pit was constructed to contain overflow and
prevent offsite migration of contaminated water onto an adjacent
pasture. The Washout Pit was pumped out and the waste water was
treated through a sand filter and subsequently through an activated
carbon filter. Discharge of treated wastewater was in accordance
with limits established by the Louisiana Department of
Environmental Quality (LDEQ), Water Quality Division. In addition,
fence repairs were made where needed and a new fence was
constructed along the west side of the West Pit to include the new
levee.
On February 8, 1991, an Action Memorandum for a second Removal
Action, designated as a classic emergency, was signed to again
address overflow from the West Pit into the secondary containment
area. Heavy rainfall during the month of January 1990 (in excess
of 13 inches) had placed a burden on the ability of the secondary
containment to hold runoff from the West Pit. This Removal Action
involved pumping, treating and discharging wastewaters from the
West Pit, the secondary containment area of the West Pit and the
Washout Pit. Treatment techniques for the wastewater were similar
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to the March 1990 Removal. A six-foot chain-link fence was
constructed around the Washout and West Pit to further restrict
site access and to replace the previous barbed wire fence which was
again in need of repair. Due to time constraints rising from the
emergency situation, five PRPs were notified by facsimile notice of
the proposed emergency action. The PRPs were given the opportunity
to conduct the removal action and were to contact EPA Region 6, ERB
by February 11, 1991. The PRPs either declined to undertake the
Removal Action or did not respond.
An Action Memorandum for a third Removal Action, which was
designated as a classic emergency, was signed on March 30, 1992 to
address critical rainwater accumulation in the Washout Pit and the
West Pit. This Removal Action, like the previous two removals,
employed pumping, treating and discharging wastewater from the West
Pit and the Washout Pit, to prevent off-site migration and human
exposure to contaminated overflow. On March 30, 1992, twenty-eight
(28) PRPs were notified by facsimile notice of the proposed
emergency action. The PRPs were given the opportunity to conduct
the removal action and were to contact EPA Region 6 ERB by
April 1, 1991. The PRPs either declined to undertake the Removal
Action or did not respond.
III. HIGHLIGHTS OF COMMUNITY PARTICIPATION
This decision document presents the selected remedial action for
the GCV Superfund site, in Abbeville, Louisiana, chosen in
accordance with CERCLA, as amended by the Superfund Amendments and
Reauthorization Act and, to the extent practicable, the National
Contingency Plan (NCP) . The decision for this site is based on the
administrative record.
The requirements of CERCLA Sections 113(k)(2)(B)(i-v) and 117,
42 U.S.C. §§9613(k)(2)(B)(i-v) and 9617, which require community
participation, were met during the remedy selection process, as
illustrated in the following discussion.
A series of community interviews were conducted in May of 1990
during which EPA representatives had face-to-face meetings with
citizens and gained information about the site history and past
practices. Fact Sheets verifying the community of significant
event were mailed out in May 1990, April 1991, January 1992, and
July 1992. These fact sheets were mailed out to all individuals on
the Site mailing list, which has been continually updated as Site
activities progressed. A Community Open House was held in
Abbeville on Wednesday, September 26, 1990, to discuss the planned
Remedial Investigation/Feasibility Study (RI/FS) activities. On
February 23, 1991, a "Superfund Citizens Workshop" was held at the
Vermilion Parish Hospital to inform citizens about the Superfund
program and the process EPA uses to remediate Superfund sites.
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An informal Open House was held on July 1, 1992 at the Hospital in
Kaplan, Louisiana to discuss the findings of the RI/FS. The RI and
FS Reports and the Proposed Plan for the Gulf Coast Vacuum site
were released to the public on July 13, 1992. These documents were
made available to the public through the Administrative Record
located in the information repositories maintained at the Vermilion
Parish Library, Abbeville, Louisiana, Louisiana Department of
Environmental Quality, Baton Rouge, Louisiana and EPA's Region 6
Library. A summary of the Proposed Plan and the notice of
availability of these documents and the Administrative Record was
published in the Abbeville Meridional on July 12, 1992. The public
comment period was from July 13, 1992 through August 11, 1992.
During this period, a request for an extension to the public
comment period was made. As a result, the public comment period
was extended to September 10, 1992.
Additionally, a public meeting was held on July 29, 1992.
Representatives from EPA and LDEQ participated in this meeting and
answered questions about development of the RI/FS for the site and
the remedial alternatives under consideration. A response to the
comments received during this public comment period, including
those expressed verbally at the public meeting, is included in the
Responsiveness Summary of the ROD.
IV. SCOPE AND ROLE OF RESPONSE ACTION
There are two operable units for the site. This ROD is for
Operable Unit No. 1, Final Source Action, which addresses all of
the sources of contamination at the site which will remain after
completion of the interim action and is the final remedial action
for the site. The interim action will include another pump and
treat of the accumulated rainwater, much like the 3 removal
actions. Sludge and soil underlying the Washout Pit will be
excavated to clean-up levels and consolidated in the West Pit. The
Washout Pit will be clean closed. The Interim Action will be
implemented prior to the Final Source Action described in this ROD.
A separate ROD was developed for Operable Unit No. 2, Interim
Source Action, which addresses the remedial action for the
accumulated rainwater in the Washout Pit and West Pit at the site.
Source material is defined as material that includes or contains
hazardous substances, pollutants or contaminants that acts as
reservoir for migration of contamination to ground water or a
surface water, or acts as a source for direct exposure. Ground
water is considered to be a non-source material.
Principal threat wastes are those source materials considered to be
highly toxic or highly mobile. These wastes that generally cannot
be reliably and present a significant risk to human health or the
environment should exposure occur. They include liquids, highly
mobile materials, or materials having high concentrations of toxic
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compounds.
The remedial action objectives for the accumulated rainwater are to
prevent oral and dermal human and environmental exposure, to
prevent contamination of adjacent soils due to overflow of the
Washout and West Pits, and to prevent migration of contamination to
the ground water.
V. SUMMARY OF SITE CHARACTERISTICS
During the Remedial Investigation (RI) all potential contaminant
sources were evaluated in two phases of field investigation. These
areas included the Washout Pit and the West Pit, the Former West
Pit, the two buried pits, all site soils, the Northeast area and
the West and East site fields. The aboveground and underground
storage tanks were also investigated. Contaminant migration
through surface water runoff was investigated through surface water
and sediment sampling. Migration to subsurface soils and the
ground water were also investigated through exploratory borings and
the installation of ground water monitoring wells. In addition,
exploratory trenches were constructed to visually evaluate the
extent of subsurface contamination. Trenches were located in areas
of suspected contamination.
A. Regional Geology
The site is located within unconsolidated sediments of the Atlantic
Coastal Plain physiographic province. These sediments are of
Pleistocene Age and were deposited by the ancestral Mississippi
River that derived sediment and flow from the central part of the
North American Continent. The sediments were deposited in a
complex series of alternating beds of sand, gravel, silt, and clay.
The beds dip toward the south and southeast and vary in thickness
from less than 100 feet in southwestern Louisiana to more than
7,000 feet beneath the Gulf of Mexico.
B. Area Soils
Two surface soil types have been identified at the Gulf Coast site,
which include the Frost Silt Loam and the Patoutville Silt Loam
(0-1% slopes and Silt Loam 1-3% Slopes). The Frost Silt Loam is
nearly level and has a slightly acid, dark gray silt loam surface
layer about seven inches thick. The Patoutville Silt Loam is a
nearly level, loamy soil which has a medium acid, dark grayish
brown silt loam surface layer about eight inches thick. This soil
is somewhat poorly drained, with slow to medium runoff.
C. Regional Hydrogeology
The major hydrogeologic unit in the site vicinity is the Chicot
Aquifer System. The system is divided into the Upper and Lower
Chicot Aquifers. The Chicot Aquifer System generally consists of
8
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a coarsening downward sequence of clays, silts, sands, and gravels.
The medium- to coarse-grained sand and gravel aquifer units dip and
thicken southward toward the Gulf of Mexico, (See Figure 3 and
Figure 4). The regional ground water gradient, shown by the arrow
in Figure 4, is toward the northwest with a hydraulic gradient of
0.0002 ft/ft. The gradient is being controlled mainly by the
ground water pumping at Eunice and Lake Charles, Louisiana.
Locally, the Upper Chicot Aquifer has been subdivided further into
the Abbeville Unit and the Upper Sand Unit. The Abbeville Unit has
been described as the shallow, saturated sand unit in the lower
Vermilion River basin consisting of fine to sandy silt at the top
that grades downward within a few tens of feet into sand and
gravel. The sand thickness is generally between 100 to 250 feet.
Since the contaminants at the site were limited vertically to the
upper 20-30 feet of the saturated zone under the site, no impacts
to the Upper Sand Unit were detected.
Recharge to the Chicot Aquifer System occurs primarily through the
direct infiltration of rainfall in the interstream, upland outcrop-
subcrop areas. Recharge also occurs through (1) the Atchafalaya
alluvium, (2) downward rainfall movement through the clays south of
the primary recharge area, and (3) limited recharge from the
Vermilion and Calcasieu rivers.
Prior to the extensive pumping of the Chicot Aquifer System (early
1900s), artesian wells could be found in the site vicinity. As
industrial and municipal water use increased, water levels declined
and the wells ceased flowing. Also, as a result of the increased
flow to pumping centers, movement of water through the surface
clays reversed (from south to north) and the coastal marsh areas
became recharge areas for the Chicot.
A brief study of residential wells in the site vicinity was
conducted by examining well construction records from the
Louisiana Department of Transportation and Development and the
U.S. Geological Survey. Information on some of the local ground
water users was also obtained through interviews with residents in
the immediate site vicinity. The survey of the well construction
records indicates that residential well depths typically range from
80 to 230 feet below ground surface. The wells are typically
constructed with two to four-inch diameter, schedule 40 PVC casing
and slotted PVC screen. Surface mounted, deep well jet pumps are
usually utilized for pumping the ground water.
Four residential wells were sampled during the RI field activities
Interviews with two of the well owners indicate that the well at
the J.J. Matthews residence (located approximately 3,000 ft north
of the site) is 80 feet deep and is constructed with 2-inch PVC
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casing. The well at the H.J. Boudreaux residence (located
approximately 2,000 ft northeast of the site) is 105 feet deep and
is constructed with 2-inch PVC casing. Two additional water supply
wells were sampled, the Richards' residence and the Fairview Farms
irrigation well. Information on the construction of these wells is
not known. No site-related contaminants were observed in the
residential wells.
D. Site Hydrogeology
Twenty-two ground water monitoring wells were installed.
Information from these wells coupled with information from the five
existing monitoring wells was utilized to investigate the
hydrogeologic regime of the site (See Figure 5). Ground water level
observations from eight monitoring wells (designated D-l through
D-8) on the D.L. Mud Superfund site were also incorporated into
this investigation.
Three hydrogeologic units, designated the Perched Unit, Upper
Aquifer Unit, and Lower Aquifer Unit were identified during the
field investigation. These units will be described within the
framework of the regional hydrogeologic system that was discussed
in the preceding section. Observations from the exploratory
drilling investigation were coupled with water level measurements
and chemical analyses to develop a conceptual model of the ground
water flow regime under the site.
E. Exploratory Drilling and Water Level Observations
The shallowest saturated unit that was observed during the
exploratory drilling is the Perched Unit. This unit is located
within the brown and gray mottled clay zone at depths ranging from
8.5 to 20 feet below ground surface. Thin, sandy silt lenses
saturated with water were noted interbedded with the clay during
the drilling and installation of three of the monitoring wells,
G-8A, G-11P, and G-11S. Water levels in this unit are relatively
high compared to other monitoring points. For example, on
December 6, 1991, water levels in those wells ranged from -3.98 to
-2.07 feet MSL which is approximately 8 feet higher than the nearby
deeper wells. This unit was observed only in the West Pasture and
northeast corner of the site. At one monitoring well in the
Northeast Area, no saturated silt lenses were observed during the
drilling phase. However, the water level in that well is
comparable to the other wells completed in the Perched Unit. The
Perched Unit is discontinuous across the site.
The next hydrogeologic unit encountered is the alternating brown
sand, silt and clay lens unit and is designated as the Upper
Aquifer Unit. It is the first continuous, saturated unit
12
-------
s-\ $i
*\ \ \ \
\ \ \ \ \
-------
underlying the site, and most likely corresponds to the "water
table" layer of the Chicot Aquifer System. Thirteen monitoring
wells are completed with their screen intervals intersecting the
ground water surface in the Upper Aquifer Unit. Three wells are
completed deeper in this same unit. As seen on the contour map in
Figure 5 a ridge in the potentiometric surface trends southwest to
northeast across the site. Locally, these features are affecting
the direction of ground water flow and the hydraulic gradients
within that unit. Ground water flow north of the ridge axis is
toward the northwest. Flow south of the ridge axis is generally to
the southeast. Recharge from the open waste pits appears to be
influencing the hydraulic gradient in that area-, with flow moving
nearly radially outward along that axis.
The deepest unit encountered at the site is the olive gray sand
designated the Lower Aquifer Unit in this report. On a regional
scale, this unit corresponds to the Abbeville Unit of the Chicot
Aquifer System. Discontinuous olive gray clay lenses partially
separate this lower unit from the Upper Aquifer Unit. Nineteen
deep monitoring wells are completed in the Lower Aquifer Unit,
with total well depths ranging from 88 to 114.5 feet below ground
surface. Based on these measurements, the gradient is
0.0001 ft/ft, with a flow direction generally toward the northwest.
This is consistent with the regional flow direction and gradient of
the Upper Chicot Aquifer System.
The potentiometric levels in the Perched Unit (and to some degree
the Upper Aquifer Unit) respond most dramatically to local
precipitation, while the Lower Aquifer Unit responds very little.
The Lower Aquifer Unit most likely receives a significant part of
its recharge from the primary recharge area of the Chicot Aquifer
system.
These observations do not preclude the vertical movement of ground
water downward toward deeper units. Downward vertical hydraulic
gradients exist between the hydrogeologic units under
the site, as indicated by the difference in water levels at the
monitoring well clusters. For example the vertical gradient
measured at G-l and G-2 is 0.005 ft/ft; G-7A and G-7B is
0.04 ft/ft; and G-8A and G-8B is 0.23 ft/ft. These downward
vertical hydraulic gradients, coupled with the discontinuous nature
of the clay lenses between the units, indicate that the potential
for downward movement of ground water (and contaminants) exists.
F. Nature and Extent of Contamination
A variety of hazardous substance as defined in CERCLA Section
100(14) were detected onsite, and are listed in Figure 8.
14
-------
l. Pit Sludges and Associated Soil
During the RI, borings were drilled in the West Pit, the Washout
Pit and the pits buried under vegetative cover. Discrete samples
of the sludge and underlying soils were collected. Both the
Washout Pit and the West Pit contain water which accumulates from
rainfall. The West Pit also supports an approximate 1 foot thick
layer of paraffin that floats on top of the water. A surface water
sample from each of these pits was taken.
The thickness of the sludge varies in each of the pits. The West
Pit has a sludge thickness of approximately 5 feet to 7 feet. The
Washout Pit has approximately 6 feet to 9 feet of sludge. The
Former West Pit has a sludge thickness of approximately 6 feet to
8.5 feet. The buried pit to the east of the West Pit contains some
sludge material, however, the full extent of this material could
not be defined due to the presence of the tank. The buried pit in
the Southeast area has a sludge layer approximately 1 foot thick at
a depth of 4 feet.
Pit sludges and soil samples were found to contain a number of
volatile and semivolatile compounds. A summary of the
concentrations of the organic compounds detected in the pits are
presented in Figure 10. In addition, the Total Petroleum
Hydrocarbon (TPH) analysis from the pit sludges ranged from 2900
parts per million (ppm) to 700,000 ppm. Benzene concentrations
ranged from 2.6 ppm to 529 ppm.
Inorganic contaminants of concern include arsenic with
concentrations ranging from 18.2 ppm to 73.7 ppm and barium with
concentrations ranging from 2,460 ppm to 47,800 ppm.
The area southeast of the Washout Pit and concrete slab was also
evaluated during the field investigation by constructing three
hand-auger borings. In one boring a black, oily clay (sludge) was
encountered from a depth of 3 feet and 7 inches to 4 feet and 6
inches. Two other borings were constructed to define the lateral
extent of the oily sludge layer.
Results of the investigation and sampling in the area southeast of
the Washout Pit indicated the presence of volatile organic
compounds such as ethyl benzene and xylene. Semi-volatile
compounds detected included compounds such as naphthalene,
2-methylnaphthalene, phenanthrene, acenaphthene, dibenzofuran,
fluorene, anthracene and pyrene. Inorganic compounds detected in
this area included barium, chromium, lead and mercury.
A series of trenches was constructed by a hydraulic excavator in
order to visually evaluate the extent of shallow contamination at
various locations across the site. Trench #1 was excavated in an
15
-------
area where a historical photograph (1974) indicated the location of
a previous pit. Excavations in this area indicated, visually, the
presence of an approximate 10 inch thick layer of sludge.
Volatile, semivolatile and inorganic compounds detected in Trench
#1 were similar to those detected in the pits.
The estimated volumes of contaminated pit material, suspected pit
material and associated soil are:
o West Pit - Sludge Volume - 5,000 cubic yards
- Associated Soil Volume - 750 cubic yards
o Washout Pit - Sludge Volume - 2,700 cubic yards
- Associated Soil Volume - 550 cubic
yards
o Former West Pit - Sludge Volume - 3,200 cubic yards
- Associated Soil Volume - 400 cubic
yards
o Suspected Areas - Sludge Volume - 1,100 cubic yards
- Associated Soil Volume - 1,300 cubic
yards
2. Storage Tanks
The site contains four vertical aboveground storage tanks
(designated Tanks #1 through #4), one small horizontal aboveground
tank, and three underground storage tanks (listed as UST #1 through
#3) , with UST #1 being the southern most tank and UST #3 being the
northernmost tank (See Figure 6).
Results of the tank sampling indicated similar volatile and semi-
volatile compounds detected for both liquids and sludges. Volatile
compounds detected included benzene, toluene, ethyl benzene, and
xylene. Semi-volatile compounds detected included napthalene,
2-methyl napthalene, phenanthrene, fluoranthene, and pyrene.
The following is a description of the physical characteristics of
each aboveground tank as well as the estimated volume of its
contents.
Tank #1 (South Tank between West and Washout Pits)
- Total calculated tank capacity = 33,874 gallons
- Volume of solids in tank = 291 ft3 or 2177 gallons
- Volume of liquids in tank = 233 ft3 or 1741 gallons
Tank #2 (West Tank of North Tank Farm)
- Total listed tank capacity = 400 bbl or 16,800 gallons
- Volume of solids in tank = 772 ft3 or 5,777 gallons
- Volume of liquids in tank = 9.4 ft3 or 70 gallons
16
-------
-------
Tank #3 (East Tank of North Tank Farm)
- Total calculated tank capacity = 43,500 gallons
- Volume of solids in tank = 2240 ft3 or 16,755 gallons
- Volume of liquids in tank = 1123 ft3 or 8,401 gallons
Tank #4 (Northeast Area Tank)
- Total listed tank capacity =220 bbls or 8820 gallons
- Volume of solids in tank = 825 ft3 or 6168 gallons
- Volume of liquids in tank = 153 ft3 or 1144 gallons
Horizontal Tank (Waste Oil Tanks)
- Total calculated tank capacity = 138 ft3 or 1033 gallons
- Volume of liquids (2 phases) in tank estimated at 83 ft3 or
620 gallons
UST #1 (South UST)
- Total calculated tank capacity = 1256 ft3 or 9399 gallons
UST #1 was dry
UST #2 (Middle UST)
Total calculated tank capacity = 1005 ft3 or 7519 gallons
Volume of liquid in tank = 40 ft3 or 299 gallons
UST #3 (North UST)
Total calculated tank capacity = 1005 ft3 or 7519 gallons
- Volume of liquid in tank = 81 ft3 or 608 gallons
As previously noted, the UST removal will be handled by LDEQ.
3. Site Soils and Sediments
Soil samples were collected from those areas of the site where
dumping of waste materials was suspected (Northeast Area and East
and West Site Fields), the West Pasture soils, the North Pasture
soils and the areas around the waste pits and storage tanks, where
impacted soils may be present.
A number of volatile and semivolatile compounds were detected in
the surface soil samples (0-2 foot) from these areas. The
concentration of these compounds was very low and therefore not
considered to pose significant health risks. The range of
inorganic concentrations was detected in the surface soils (0-2
foot) onsite. The primary contaminants of concern in these areas
are arsenic and barium, located in the upper 2 feet of soil.
Surface water and sediment samples were collected during the field
investigation. The areas targeted in the investigation were the
ditches and canals draining onto or off the site.
Results of the remedial investigation indicated that contaminants
are being transported offsite via the North Ditch during rainfall
events. Overflow from the North Ditch into the North Pasture has
18
-------
occurred in the past, depositing contaminated sediments onto the
North Pasture. Therefore, the primary contaminants of concern in
the surface sediments, like the site soils, are also arsenic and
barium.
Estimates of the volume of contaminated soil and sediment are
presented below.
o Northeast Area and Site Fields - 18,900 cubic yards
o Surface Sediments - 600 cubic yards
4. Ground water
Ground water at the site was evaluated through the installation of
monitoring wells screened at different depth intervals and the
collection of ground water samples for analysis. (See Figure 7).
Three monitoring wells G-9, G-13 and G-24, were considered to be
sufficiently removed from the site as to represent background
conditions. As previously mentioned, four private water supply
wells were sampled during the remedial investigation.
As discussed above (See site Hydrogeology Section), ground water
beneath the site was found within three water bearing units; a
Perched Unit (found to be isolated to two small areas at the
southwest and northeast portions of the site), an Upper Aquifer
Unit (less than approximately 50 feet in depth) , and a Lower
Aquifer Unit (found at a depth greater than approximately 80 feet) .
Ground water in the Upper Aquifer Unit was found to move radially
outward from the site (See Figure 5) . This flow pattern is
controlled by a ground water that trends northeast/southwest across
the site. Recharge of water percolating downward from the West Pit
and the Washout Pit also appears to be influencing this radial flow
pattern. Ground water flow within the Lower Aquifer Unit was found
generally to the northwest.
The Perched Unit in the southwest portion of the site has been
impacted by inorganic compounds (metals), however this unit was
found to have only a limited areal extent. Contaminants detected
above drinking water Maximum Contaminant Levels (MCLs) in the
Perched Unit include barium, cadmium and chromium. Figure 7 also
illustrates the limited areal extent of the Perched Unit and the
contamination detected in this unit.
The most wide spread site-related ground water contaminants are
metals, both in the dissolved phase and as a total concentration.
Metals (total) exhibiting elevated concentrations (above drinking
19
-------
WMnmc noi *M ocwico
wrot Mcroi (J;A>
. ami >«xn
U??E» AND PERCHED
UNITS
UU CCAST VACUUM SERVICE
VF?MS.i(M
FIGURE 7
-------
water MCLs) included arsenic, barium, cadmium, chromium, and
mercury. Lead was also found to exceed the promulgated "action
level" (MCL) in a few of the monitoring wells. Metals which also
exceeded MCLs, when analyzed in the dissolved phase, were barium
and cadmium.
The Lower Aquifer Unit does not appear to have been impacted by the
Gulf Coast site. Although some metal constituents were elevated
compared to the Upper Aquifer background samples, there is evidence
of a natural difference in water quality between the two
hydrogeologic units.
The four residential water supply wells sampled during the remedial
investigation do not appear to be impacted by the contamination at
the Gulf Coast Vacuum site. These wells were completed in the
Lower Aquifer Unit.
VI. SUMMARY OF SITE RISKS
A. Risk Assessment Description
An evaluation of the potential risks to human health and the
environment from site contaminants was conducted as part of the
baseline risk assessment. The risk assessment was conducted as
part of the RI. The baseline risk assessment is an analysis of the
potential adverse human health effects (both current and future)
resulting from exposures of humans to hazardous substances in
surface soil, sludge, sediment, ground water and surface water at
the site. By definition, a baseline risk assessment evaluates
risks that may exist under the no-action alternative (that is, in
the absence of any remedial actions to control or mitigate
releases). The baseline risk assessment provides the basis for
taking the remedial .action and indicates the exposure pathways that
need to be addressed by the remedial action.
The risk assessment presents a compilation and evaluation of data
collected in the site investigation in order to estimate the upper
limit of potential health risk which may be present at the site.
In the evaluation of potential human exposure scenarios, on-site
sampling and analysis results were used in conjunction with current
Federal and State guidance documents and professional judgement to
estimate the potential human health risk attributable to
contamination resulting from past site-related operations.
The "risk" values generated within this human health risk
assessment will reflect the plausible upper limit to the actual
risk of cancer posed by the site under the exposure scenarios
evaluated. These estimates were compared to the EPA's risk range
21
-------
of concern of 1 X 10"4 to 1 X ID'6 for hazardous waste site
remediation. The National Contingency Plan stipulates a 1 X 10"*
risk level as a point of departure in risk management. Such
estimates, however, do not necessarily represent an actual
prediction of the risk. Non-carcinogenic impacts are quantified by
the "Hazard Index" which is the ratio of site concentrations of a
contaminant of concern to a reference concentration that causes a
non-carcinogenic impact. EPA's remedial goal is to reduce the
"Hazard Index" at a site to less than 1.0. These risk values are
discussed more fully in the following sections.
The Summary of Site Risks section of the ROD summarizes the results
of the baseline risk assessment. Calculations and a more detailed
analysis may be found in the site risk assessment contained in the
administrative record.
B. Human Health Risks
The baseline risk assessment was divided into two parts: the human
health evaluation and the ecological evaluation. The baseline risk
assessment for the human health risks was based on Reasonable
Maximum Exposure (RME). The human health evaluation considered all
contaminated media, such as pit sludge, surface soils, subsurface
soils, sediments, surface water and ground water. The risk
assessment evaluated the potential risk to the following
populations which are most likely to be exposed to materials at the
Gulf Coast site:
o Current onsite trespassers
o Current offsite residents (adults and children) using
ground water as a drinking water source
o Future onsite resident farmers (adults and children)
The risk assessment conducted at the Gulf Coast Vacuum site was
done in accordance with EPA guidance, specifically the Risk
Assessment Guidance for Superfund; Volume I; Human Health
Evaluation Manual (Part A) (Interim Final. EPA/540/1-89/002.
December 1989). The major components of the baseline risk
assessment are: identification of contaminants of concern, exposure
assessment, toxicity assessment, and risk characterization.
Highlights of the findings for the major components of the risk
assessment for the site are summarized below.
C. Identification of Chemicals of Concern
Analytical data from the sludge, soil, surface water and sediments
were evaluated to identify contaminants of potential concern at the
site. Any chemical detected in any sample from these areas was
22
-------
considered to be a potential contaminant of concern. A summary of
the chemicals detected on site for each medium and their frequency
of detection is presented in Figure 8. Chemicals were eliminated
from consideration only if they are essential nutrients and are
nontoxic at the levels encountered on site. Seventy-seven (77)
chemicals were selected as contaminants of potential concern for
the entire site and are listed in Figure 9. However, only arsenic,
barium dioxins, and PAHs, carcinogenic and non-carcinogenic, were
found to significantly contribute to the risk.
D. Exposure Assessment
The potentially exposed populations and the pathways through which
they could be exposed for current site conditions and future onsite
conditions are discussed below.
1. Current Land Use and Exposure Pathways
Areas adjacent to the site are currently used as pasture land for
grazing cattle and for other agricultural uses. A review of
historical photographs also indicates the past and current adjacent
land use to be predominantly agricultural. Immediately south and
east of the site is the D.L. Mud site, which is being evaluated
separately.
The current potential use of the ground water is for drinking water
purposes as well as for irrigation. Although the upper units of
Chicot Aquifer identified at the site do not have an official
classification, the ground water is considered suitable for
drinking water purposes. A study of the residential wells in the
site vicinity indicates that residential well depths range from 80
to 230 feet below ground surface. The regional and site
hydrogeology is discussed in detail above in the Summary of Site
Characteristics section.
Currently there are no people who live or work onsite. Therefore,
a trespasser scenario was selected as representative of the
situation most likely to expose humans to the site under current
conditions. The trespasser was assumed to be an area resident who
began exposure at age seven and continued until age sixteen. It
was assumed that the trespasser moved about the site at random,
coming into contact with all accessible media.
There are 10 residences located within 1/2 mile of the site.
Nearby residents might be exposed to site contaminants by using
ground water from residential wells or they may be exposed while
trespassing onsite. The closest major population center is
Abbeville, located about 3.5 miles northeast of the site.
23
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SUMMARY OF CHEMICALS DETECTED ON-SITE AT GULF COAST
Chemical Name
Surface Subsurface
Surface
Volatile:;
Acetone
Benzene
Butanone , 2-
Carbon disulfide
Chlorobenzene
Chloroform
Chloromethane
Dichloroethane, 1,1-
Ethylbenzene
Methylene chloride
Tetrachloroethene
Toluene
Trichloroethene
"Vinyl acetate
Xylene (total)
Semi-Volatiles:
Benzole acid
Dibenzofuran
Di chlorobenzene, 1,4-
Dinitrotoluene, 2,4-
N-Nitrosodiphenylamine
Pentachlorophenol
Phenol
Acenaphthene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo (b )f luoranthene
Benzo(g,h,i)perylene
Benzo (k ) f luoranthene
Chrysene
Fluoranthcne
Fluorene
Methylnaphthalene, 2-
Haphthalene
Phenanthrene
Pyrene
Bis (2-ethylhexyl)phthalate
Butylbenzylphthalate
Di -n-buty lphth»late
Di-n-octylphthalate
DiethyLphthalate
Dinethylphthalate
Pesticides/PCBs:
Aldrin
alpha-Chlordane
Arochlor-1248
beta-BBC
DDD, 4,4-
DDT, 4,4-
delta-BHC
Dieldrin
Endosulfan I
Zndosulfan II
13/45
1 // C
I/O
2/43
0/45
1/45
0/45
1/45
0/45
4/45
9/45
2/45
8/45
1/45
0/34
6/45
0/34.
3/45
0/45
0/45
1/45
0/45
0/45
0/45
2/45
1/45
0/45
1/45
2/45
0/45
2/45
1/45
2/45
6/45
4/45
7/45
6/45
20/45
1/45
1/45
1/45
1/45
0/45
0/34
0/34
0/34
A /t r
0/34
0/34
1/34
ft ft/
U/34
ft /« /
0/34
n ii i
U/3s
(\ /it
U/34
Soil
45/117
3/117
28/112
5/117
0/117
1/117
0/117
0/117
12/117
13/117
4/117
13/117
2/117
0/72
20/117
0/73
8/118
0/118
1/118
0/118
0/118
1/118
5/118
2/118
0/118
0/118
0/118
0/118
0/118
3/118
3/118
10/118
18/118
15/118
20/118
8/118
42/118
1/118
3/118
0/118
2/118
1/118
1/77
0/77
2/77
0/77
0/77
0/77
2/77
0/77
0/77
0/77
Sediment S1,,H
2/4 6/19
0/4 14/19
1/1 3/19
0/4 3/19
0/4 2/19
0/4 0/19
1/4 0/19
0/4 1/19
0/4 16/19
0/4 0/19
0/4 2/19
0/4 16/19
0/4 1/19
0/3 0/14
0/4 17/19
1/4 0/14
0/4 2/19
1/4 0/19
0/4 0/19
0/4 3/18
1/4 0/18
0/4 0/19
0/4 2/19
0/4 3/18
0/4 2/18
1/4 3/18
0/4 1/ie
1/4 0/18
0/4 3/18
2/4 4/18
0/4 2/18
1/4 9/19
1/4 18/19
0/4 16/19
1/4 14/18
2/4 7/18
2/4 4/18
0/4 1/18
0/4 1/18
1/4 1/18
0/4 0/19
0/4 1/19
0/4 0/19
0/4 0/19
0/4 5/19
0/4 0/19
0/4 1/19
0/4 0/19
0/4 1/19
0/4 0/19
0/4 0/9
0/4 1/9
l&e Hati
2/5
1/S
0/5
1/5
1/5
0/5
0/6
0/5
1/5
0/5
0/5
1/5
0/5
1/4
1/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
1/5
1/5
1/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
0/5
1/5
0/5
0/5
0/5
0/5
0/21
2/21
0/21
0/21
0/21
0/21
0/21
0/21
1/21
1/29
1/21
0/21
0/29
0/8
0/21
0/2
2/20
0/20
0/20
0/21
0/21
0/20
0/20
1/21
0/21
0/21
0/21
0/21
0/21
0/21
0/21
0/20
1/21
0/21
2/21
0/21
20/29
0/21
0/21
0/21
0/20
0/20
0/21
1/21
1/21
3/21
0/21
1/21
0/21
3/21
1/21
0/21
68/211
21/211
34/201
9/211
4/211
1/211
2/212
1/211
34/211
23/219
9/211
38/211
4/219
1/135
44/211
1/132
15/211
1/211
1/211
4/211
1/211
1/211
7/211
8/211
3/211
4/211
2/211
3/211
3/211
11/211
6/211
22/211
45/212
36/212
4.5/211
23/211
88/219
3/211
5/211
3/211
3/211
2/211
1/160
1/160
8/160
3/160
1/160
3/160
3/160
3/160
1/150
1/150
FIGURE 8
-------
- continued
Chemical Name
Ptsticides/FCBa - continued
Endoeulfan culfate
Endrin
laima-Chlordant
Buna-BBC
Htptaehlor
fleptachlor epoxida
Inorganics:
Aluminum
Antimony
Araenic
Barium
Beryllium
Cadmium
Calcium
Chloride
Chromium
Cobalt
Copper
Cyanide
Iron
Lead
Htgnetiutn
Mancaneae
Mercury
Hiekel
Potaimium
Selenium
Silver
Sodium
Thallium
Vanadium
Zinc
Dioxinc/fuxanc
Surface Subsurface SurJace
Sell Sediaant Sludne Hater GroundKBter Total
0/34
0/34
0/34
0/34
0/34
0/34
45/45
1/14
44/45
45/45
40/45
25/45
45/45
41/46
45/45
43/45
43/45
11/37
45/45
41/41
4 5/4 5
43/45
29/45
43/45
41/45
18/45
10/45
40/45
10/42
45/45
43/43
1/77
0/77
0/77
0/77
0/77
0/77
117/117
0/50
110/117
117/117
113/117
29/117
117/117
96/112
117/117
107/117
115/117
6/99
117/117
Ill/Ill
117/117
111/111
24/117
114/117
114/117
25/113
12/117
105/117
24/117
117/117
115/115
0/4 0/19
0/4 0/16
0/4 0/19
0/4 1/19
0/4 0/19
0/4 0/19
4/4 20/20
0/4 0/9
4/4 20/20
4/4 20/20
2/4 9/20
3/4 19/20
4/4 20/20
2/4 18/20
4/4 20/20
3/4 17/20
4/4 20/20
0/4 0/11
4/4 20/20
4/4 20/20
4/4 20/20
4/4 17/17
3/4 19/20
4/4 20/20
4/4 15/20
0/4 7/20
0/4 16/20
1/4 18/20
0/4 3/20
4/4 20/20
4/4 20/20
0/5
0/5
0/5
0/5
0/5
0/5
4/4
0/4
0/6
4/4
^t ^
0/4
0/4
4/4
5/5
2/4
0/4
1/4
0/4
3/4
3/3
4/4
4/4
0/4
0/4
4/4
0/3
0/4
4/4
0/3
0/4
4/4
0/21
1/21
3/21
1/21
1/21
2/21
18/21
4/21
20/29
21/21
5/21
10/21
21/21
21/21
12/21
14/21
14/21
0/9
21/21
15/21
21/21
21/21
«/21
13/21
20/21
0/21
0/15
21/21
1/21
15/21
16/21
1/160
1/137
3/UO
2/160
1/160
2/160
206/211
3/102
198/221
211/211
l«/21l
86/211
211/211
183/208
200/211
184/211
197/211
17/1*4
210/211
1*4/200
211/211
202/202
81/211
194/211
198/211
£0/206
38/203
189/211
40/210
201/211
202/207
11/11
3/4
6/6
9/9
0/0
0/1
29/31
FIGURE 8 (cent.)'"
-------
Figure 9
Volatiles
Acetone
Benzene
Butanone, 2-
Carbon disulfide
Chlorobenzene
Chloroform
Chloromethane
Dichloroethane, 1,1-
Ethylbenzene
Methylene chloride
Tetrachloroethene
Toluene
Trichloroethene
Vinyl acetate
Xylene (total)
Semivolatiles
Benzole acid
Dibenzofuran
Dichlorobenzene, 1,4-
Dinitrotoluene, 2,4-
N-Nitrosodiphenylamihe
Pentachlorophenol
Phenol
Bis(2-ethylhexyl)phthalate
Butylbenzylphthalate
Di-n-butylphthalate
Di-n-octylphthalate
Diethylphthalate
Dimethylphthalate
PAHs
Acenaphthene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)ftuoranthene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Chrysene
Fluoranthene
Fluorene
Methylnaphthalene, 2-
Naphthalene
Phenanthrene
Pyrene
Pesticides/PCBs
Aldrin
Alpha chlordane
Arochlor-1248
Beta-BHC
ODD, 4,4'-
DDT, 4,4'-
Delta-BHC
Dieldrin
Endosulfan I
Endosulfan n '
Endosulfan sulfate
Endrin
Gamma chlordane
Gamma-BHC
Heptachlor
Heptachlor epoxide
Inorganics
Aluminum
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chloride
Chromium
Cobalt
Cyanide
Lead
Manganese
Mercury
Nickel
Silver
Sodium
Thallium
Vanadium
Dioxins/Furans
TCDD-equivalent
-------
2. Future Land Use and Onsite Conditions
In the future it is possible that the site might be developed for
residential, agricultural or industrial use. As the site currently
exists, development for agricultural use with possible onsite
residence of farmers was considered the most likely future land
use, since the surrounding land is primarily used for pasture land
and for residences. Therefore, the resident-farmer was selected as
the most representative of the population category likely to be
exposed in the future.
Reasonable exposure pathways affecting present and future
populations are discussed below.
a) Exposure to Soil - Since all humans ingest small amounts of
soil and other soil-like material each day through hand to
mouth activity both indoors (i.e. intake of house dust) and
outdoors (i.e. while playing or gardening), ingestion of
contaminated surface soil was selected as an exposure route
for both adults and children for quantitative assessment.
Likewise, dermal contact is a route of exposure. Exposure to
subsurface soil was not evaluated for any population since the
contaminant concentrations for this media were low.
Evaluation of soil was carried out in five subareas (exposure
points) , because the distribution of soil contamination is not
uniform across the site. Exposures of future residents were
evaluated in the Northeast Area and in an area located between
the West Pit and the Washout Pit (the "Pit Area"). Exposures
to current site trespassers were evaluated at the West Pit
Area, the Washout Pit Area and in the northwest portion of the
site ("the site Field Area").
b) Exposure to Homegrown Vegetables, Beef and Milk - Humans
can be indirectly exposed to soil contamination through the
ingestion of garden vegetables grown in contaminated soil.
Since future agricultural use of the site is likely, this
pathway was considered and may be a significant source of
exposure. Therefore, exposure for this pathway was quantified
for future residents. Likewise, humans may be indirectly
exposed to soil contamination via the ingestion of meat and
milk from animals raised in contaminated areas.
c) Exposure to Contaminants in Air - Air monitoring data
during an Air Emission Pilot Study conducted at the Gulf Coast
Vacuum site in August 1991 indicated that volatile compounds
are currently not released from undisturbed soil and that only
27
-------
low levels are released from disturbed soils. Therefore,
exposure to volatiles from soil or pit sludges was not
evaluated.
d) Exposure to Contaminants in Ground water - Ground water
monitoring data indicated the presence of inorganic and to a
lesser degree, organic contamination in the shallow aquifers
(i.e. Perched Unit and Upper Aquifer Unit). Under current
conditions, there are no known human populations who employ
the shallow aquifers near the site for drinking or other uses.
However, in the future, it is possible that onsite or offsite
residents might install shallow wells for drinking water and
other indoor uses. Therefore, the three'exposure pathways
which were evaluated in the risk assessment for the future
onsite resident included ingestion, dermal contact and
inhalation. In addition, because of the likelihood of
interconnection between the Upper Aquifer Unit and the Lower
Aquifer Unit, an exposure pathway for current offsite
residents was evaluated quantitatively using monitoring data
from the ground water monitoring wells in the Lower Aquifer
Unit.
e) Exposure to Contaminants in Surface Water and Sediments -
There are two primary channels for surface water runoff from
the site. One is the north ditch which drains runoff or
overflow from the pits and runs through the Site Fields and
into the North Pasture. The other is a canal which runs east
and west in between the Gulf Coast Vacuum site and the D.L.
Mud site and towards the LeBoeuf Canal. Under current
conditions humans may be exposed to the surface water or
sediments while trespassing on the site through oral ingestion
or dermal contact.
f) Exposure to Contaminants in Sludge - The pit sludges are
highly contaminated with inorganic and organic materials.
Under current conditions humans may be exposed to the Washout
Pit Area and/or the West Pit Area while trespassing this area
through oral ingestion or dermal contact. Future onsite
exposure to residents, through both oral ingestion and dermal
contact, is also a reasonable exposure pathway and was
evaluated as part of the risk assessment.
A summary of the exposure pathways used for quantitative evaluation
is shown in Figure 10.
Exposure in the risk assessment was quantified using standard
default values. Figure 11 summarizes the assumptions used in the
risk assessment for the Gulf Coast Vacuum site (See Appendix III
28
-------
SUMMARY OF EXPOSURE SCENARIOS SELECTED FOR QUANTIFICATION'
Exposed
Land Use Population
Current Trespasser'
Current Resident
Future Resident
Future Resident
Exposure
Point
On-site
(West Pit
Area, Washout
Pit Area,
Northwest
Site Field)
Off-site
Residential
Wells
On-site
(Pit Area,
Northeast
Area)
On-site(c)
(Pit Area)
Exposure Media
Soil
Sludge
Sediment
Surface Water
Groundwater
Exposure
Soil
Groundwater
Garden Vegetables
Beef
Milk
Sludge
Garden Vegetables
Beef
Milk
Routes
Oral/Dermal
Oral/Dermal
Oral/Dermal
Dermal
- Oral/Dermal
Oral/Dermal
Oral/Dermal /"
Oral
Oral
Oral
Oral/Deriral
Oral
Oral
Oral
'-.si (VOCs)
(a) Scenarios in which a trespasser is exposed at various sources on-si
apply to hypothetical future on-site residents.
(b) Assumes current site conditions (i.e., sludge is located in pits).
(c) Assumes pit sludge is excavated and spread on surrounding land.
also
FIGURE 10
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for Figure 11 references).
E. Toxicity Assessment
The toxic effects of a chemical generally depend on the level of
exposure (dose), the route of exposure (oral, inhalation, dermal),
and the duration of exposure (acute, subchronic, chronic or
lifetime). Thus, a full description of the toxic effects of a
chemical includes a listing of what adverse health effects the
chemical may cause (carcinogenic and noncarcinogenic), and how the
occurrence of these effects depends upon dose, route, and duration
of exposure.
Slope factors (SFs) have been developed by EPA's Carcinogenic
Assessment Group for estimating excess lifetime cancer risks
associated with exposure to potentially carcinogenic contaminant (s)
of concern. SFs, which are expressed in units of (mg/kg-day)"1, are
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 SF. Use of this approach makes
underestimation of the actual cancer risk highly unlikely. Slope
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 (e.g., to
account for the use of animal data to predict effects on humans).
Reference doses (RfDs) have been developed by EPA for indicating
the potential for adverse health effects from exposure to
contaminant(s) of concern 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 contaminant(s) of concern from
environmental media (e.g., the amount of a contaminant(s) of
concern ingested from contaminated drinking water) can be compared
to the RfD. RfDs are derived from human epidemiological studies or
animal studies to which uncertainly factors have been applied
(e.g., to account for the use of animal data to predict effects on
humans).
For the three major sets of exposure pathways utilized for this
risk assessment (current trespassers, current off-site residents,
and future on-site residents) and for three age groups (children
ages 7-13 years (s), teenagers (c), and 70 year-olds exposed their
entire lives (L)), Human Intake Factors (HIFs), also called Chronic
Daily Intake Factors (GDIs), were calculated. (See Figure 12).
31
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-------
SUMMARY OF HIF CALCULATIONS
Exposed Population
Current Trespasser
Current Off -site
Resident
Future On- site
Resident
Exposure Medium
Soil
Sludge
Sediment
Surface Water
Groundwater
Groundwater
Soil or Sludge
Garden Vegetables
Beef
Milk
Exposure
Route
Oral
Dermal
Oral
Dermal
Oral
Dermal
Oral
Dermal
Oral
Dermal
Oral
Inhalation
Dermal
Oral
Dermal
Oral
Oral
Oral
HIF5
--
--
6.4E-02
9.2E-02
6.4E-02
1 . 2E+00
9.2E-02
1.3E-05
1.2E-04
2.6E-03
2.3E-03
2.6E-02
HIFr
3.8E-07
1.9E.-05
3.8E-07
3.8E-05
3.8E-07
1.9E-05
5.0E-02
2.7E-02
5.5E-02
2.7E-02
2.1E-01
5.5E-02
3.7E-06
6.8E-05
1.1E-03
l.OE-03
4.1E-03
H1FL
5.5E-OS
2.7E-06
5.5E-OE
5.5E-OJ
5.5E-0£
2.7E-06
7.1E-02
1.2E-02
2.3E-Oi
1.2E-OJ
8.8E-OS
2.3E-0:
1.6E-0(
2.9E-0!
4.8E-0^
1.8E-0:
FIGURE 12 (Cont.)
-------
These HIFs were calculated using the exposure point concentration
factors for each medium.
EPA assigns a cancer weight-of-evidence category to each chemical
in order to reflect the overall confidence that the chemical is
likely to cause cancer in humans. These categories and their
meanings are summarized below.
Category Meaning Basis
A Known human Sufficient evidence of increased cancer
carcinogen incidence in exposed humans.
Bl Probable human Sufficient evidence of increased cancer
carcinogen incidence in animals, with suggestive
evidence from studies of exposed humans.
B2 Probable human Sufficient evidence of increased cancer
carcinogen incidence in animals, but lack of data or
insufficient data from humans.
C Possible human Suggestive evidence of carcinogenicity in
carcinogen animals.
D Cannot be No evidence or inadequate evidence of
evaluated cancer in animals or humans.
E Noncarcinogen Evidence of noncarcinogenicity
for humans.
Toxicity information used to calculate the risk including the slope
factor, the weight of the evidence, and the source of the toxicity
information is summarized in Figure 12.
F. Human Health Risk Characterization
The risk of cancer from exposure to a chemical is described in
terms of the probability that an individual exposed for his or her
entire lifetime will develop cancer by age 70. For carcinogens,
risks are estimated as the incremental probability of an individual
developing cancer over a life-time as a result of exposure to the
carcinogen. Excess life-time cancer risk is calculated from the
following equation:
35
-------
Risk = GDI x SF
where:
risk = a unit less probability (e.g., 2 X 10"5) of an individual
developing cancer;
GDI = chronic daily intake averaged over 70 years (mg/kg-day); and
SF = slope-factor, expressed as (mg/kg-day)"1
These risks are probabilities that are generally expressed in
scientific notation (e.g., 1 x 10"6 or IE"6) . An excess lifetime
cancer risk of 1 x 10"6 indicates that, as a reasonable maximum
estimate, an individual has a 1 in 1,000,000 chance of developing
cancer as a result of site-related exposure to a carcinogen over a
70-year lifetime under the specific exposure conditions at a site.
Again refer to Figure 12 which provides a brief summary of the
characteristic cancer effects of chemicals of potential concern at
the GCV site and lists available inhalation SFs and cancer weight
of evidence categories.
The potential for noncarcinogenic effects is evaluated by comparing
an exposure level over a specified time period (e.g., life-time)
with a reference dose derived for a similar exposure period. The
ratio of exposure to toxicity is called the hazard quotient. By
adding the hazard quotients for all contaminants of concern which
affect the same target organ (e.g., liver) within a medium or
across all media to which a given population may reasonably be
exposed, the Hazard Index (HI) can be generated.
The HQ is calculated as follows:
Non-cancer HQ = DI/RfD
where:
DI = Daily Intake (either chronic or sub-chronic)
RfD = reference dose; and
DI and RfD are expressed in the same units and represent the same
exposure period (e.g., chronic, subchronic, or short-term).
Using the average lifetime daily intake values and the slope
factors previously shown in Figure 12, cancer risks were calculated
for populations who may be chronically or sub-chronically exposed
at the Gulf Coast Site. Risk was calculated for several scenarios
36
-------
involving exposure to the pit sludges, the Northwest site fields,
the Northeast area and the ground water.
1. Current Risk Characterization
The estimated overall risk of carcinogenic effects of 4X10"* for a
current trespasser who visits the site 60 times per year and is
exposed to the pit sludges is greater than the EPA risk range of
concern of 1x10"* to IxlO"*. Contaminants having risk values outside
this range are flagged as those which may need to be remediated.
The main contaminants contributing to the risk for this current
trespasser were total carcinogenic PAHs (polynuclear aromatic
hydrocarbons), arsenic, and dioxins. For the current trespasser,
noncancer risks did not exceed an HI of 1. An HI of greater than
or equal to 1 is of concern to EPA and flags those chemicals that
may need to be remediated.
The estimated total risk of carcinogenic effects from exposure to
contaminants for a current off-site resident is in the range of
2X10"4 to 9x10"* which is greater than EPA's risk range of concern
of 1x10^* to 1x10"*. This risk is driven by the possible ingest ion
of arsenic in the ground water. The estimated overall HI of non-
carcinogenic effects for a current off-site resident ranges from 1
to 9, due almost entirely to the concentration of arsenic in the
ground water. This HI value is above EPA's value of concern of 1.
2. Future Risk Characterization
The estimated excess cancer risk to a hypothetical future resident
in both the West Pit area and the Northeast area of the site is
2xlO'3 which is greater than EPA's risk range of concern of ixlO"1
to 1x10"6. Arsenic exposure through ground water and total
carcinogenic PAH exposure through the food chain are the main
contributors to this risk. The estimated average risk of 1 x 10+1
to 4 x 10+1 from noncancer effects is well above EPA's value of
concern of an HI of 1 for both children and adults. The noncancer
risk is mainly driven by the presence of a number of inorganics in
drinking water, some of which are probably naturally occurring in
the ground water. Barium in excavated sludge could also contribute
to a an HI above 1 through the soil ingestion pathway.
Future residents would have very high risks in the scenario of the
West Pit being sludge excavated and spread on the Pit Area soils.
In this case, total cancer risk would be a total of 5E-01, due
mostly to food-chain exposures, but with substantial risks also
contributed from direct ingestion (3 x 10'2) and dermal contact
(2 x 10^) with the sludge.
37
-------
3. Risk from Dioxins: The risk investigation shows the
dioxin/furan analyses to be less than l ppm 2,3,7,8-
tetachlorodibenzodioxin (TCDD) equivalents in sludges, surface
soils and sediment. It has been determined by EPA and the Agency
for Toxic Substances and Disease Registry (ATSDR) that levels
between 1 and 10 ppb TCDD equivalents do not represent a
significant residential risk provided they are covered with at
least 12 inches of clean soil. At GCV, media containing the TCDD
equivalents above 10 ppb will be excavated and treated through
incineration. Remedial Action Goals for the incinerator ash will
assure that dioxins do not remain on site above remedial levels.
4. Evaluation of Lead: Since there are no EPA-approved RfD values
for lead, it is not possible to evaluate the noncancer risks of
lead by calculation of a Hazard Index. An alternative approach is
to estimate the likely effect of lead exposure on the concentration
of lead in the blood (PbB) . Summaries of the results using the
Uptake/Biokinetic (UBK) model are shown in Figure 13. All input
parameters for the GCV site evaluation were taken to be the
national average values suggested as defaults by EPA except the
concentrations of lead in the soil and water which were site-
specific values. Lead exposure for future residents exceeded the
EPA-recommended blood lead level (no more than 5% of the population
above 10 ug/dL) for the scenario of the sludge spread on-site.
G. Uncertainties Associated with Human Health Risk Calculations
Within the Superfund process, baseline quantitative risk
assessments are performed in order to provide risk managers with a
numerical representation of the severity of contamination present
at the site, as well as to provide an indication of the potential
for adverse public health effects. There are many inherent and
imposed uncertainties in the risk assessment methodologies.
This following chart summarizes the uncertainty and the potential
bias in the risk estimates. (Figure 14).
Note that the RMEs calculated are intended to represent the upper
end of the distribution curve. Therefore, most people are likely
to be exposed to lower doses than this calculated value.
H. central Tendency Exposure
Based on a February 26, 1992, memorandum from Deputy Administrator
F. Henry Habicht, EPA is required to evaluate both "reasonable
maximum exposure" (RME) and "central tendency" in the risk
assessment at Superfund sites. Exposure assumptions discussed to
this point in the ROD have been associated with the RME which was
38
-------
SUMMARY OF RISKS TO HYPOTHETICAL FUTURE RESIDENTS*85
FROM EXPOSURE TO LEAD
Exposure Point
Pit Area
(current
condition)
Northeast Area
Pit Area
(sludge spread
on surface)
Exposure
Medium
Soil
Groundwater
Soil
Groundwater
Sludge
Groundwater
Exposure
Concentration
56 ppm
1-8 Mg/L
174 ppm
8.6 Mg/L
580 ppm
1.8 Mg/L
Mean
PbB
1.9
3.3
6.3
X Population
Above
10 ue/dL
0.0
0.1
9.0
FIGURE 13
(a) Evaluated for children age 0 to 6 years.
-------
SUMMARY OF PRIMARY SOURCES OF
UNCERTAINTY IN THIS RISK ASSESSMENT
Factors that Tend to Underestimate Exposure or Risk
• Lack of RfDs or SFs for all chemicals and all routes
• Nonquantification of some exposure pathways
• Exclusion from consideration of some chemicals possibly present but
never detected
• Assumption that chemicals never detected in a medium are absent from
that medium
Factors that Tend to Overestimate Exposure or Risk
« Use of conservative human exposure assumptions and values
• Use of conservative RfDs or SFs
• Use of simple rule to predict air exposures to VOCs from water
• Assumption that chemicals detected in a medium are present in all
samples of that medium
Factors That Might Underestimate or Overestimate Exposure or Risk
• Use of concentration values that are constant over time
• Use of 1/2 the detection limit to evaluate nondetects
• Possible occurrence of "hot spots"
• Use of models to predict concentration of contaminants in vegetables,
beef and milk
FIGURE 14
-------
used to estimate the baseline risks and ultimately the remedial
action goals at sites. The "central tendency" scenario represents
the risk from more of an "average" exposure, compared to a
"reasonable maximum" exposure. See Figure 15 for the central
tendency risk assumption comparison with the RME.
I. Ecological Risks
The baseline ecological risk assessment provides a qualitative
evaluation of the environmental risks at the GCV site. The site
ecology was evaluated to determine if contamination from the site
was causing any significant adverse ecological impact. The
ecological risk assessment is summarized in the following section.
The assessment of environmental risks was limited to consideration
of ecological resources on-site and in the vicinity of the site
where organisms may become exposed to contaminated surface soil,
surface water and sediment. Potential exposures to contaminants in
air were not evaluated since air monitoring data indicate that
volatile releases are not presently occurring. In addition, the
site's vegetation and wet climate tend to minimize dust emissions.
No rare, threatened or endangered populations are likely to be
exposed to site contaminants. Rabbits, squirrels and deer are
wildlife species that may be exposed at the site. Migratory
waterfowl may be exposed to surface water and sediment on a
transient basis. Aquatic invertebrates and fish in canals near the
site may be exposed to site-related chemicals in water and sediment
and serve as food sources to higher trophic levels.
The following are potentially complete exposure pathways at this
site:
• Vegetation growing in contaminated soil, ditches or canals
• Aquatic organisms exposed to surface water and sediment
• Terrestrial wildlife coming in direct contact with
contaminated media
• Animals that consume organisms that have accumulated site-
related chemicals, i.e. a red-tailed hawk
Resident wildlife, which spend less than a lifetime on-site, are
likely to receive low to moderate exposures to site contaminants.
Small mammals whose home range is contained entirely on-site are
likely to receive a proportionately greater exposure than larger
mammals and birds that may spend a fraction of their time on-site
throughout the year or on a seasonal basis. Migratory waterfowl
are likely to receive the lowest exposure to contaminated media
41
-------
CENTRAL TENDENCY VS REASONABLE MAXIMUM EXPOSURE ASSUMPTIONS
Average or
Central Tendency
Contact Rates (CR)
Water Ingestion Rates
Children (1-6 yrs)
Adults
Workers
Soil Ingestion Rates
Children (1-6 yrs)
Adults
Workers
Fish Ingestion Rates
Adults 6.5 g/day
Air Inhalation Rates
Children (1-6 yrs) 5 cu. m/day
Adults 20 cu.m/day
Reasonable
Maximum Exposure
0.7 L/day
1.4 L/day
0.7
200 mg/day
100 mg/day
50 mg/day
Dermal Exposure
Adherence factor (AF)
Absorption factor (ABS)
Total Surface Area (SA)
1 L/day
2 L/day
1 L/day
200 mg/day
100 mg/day
50 mg/day
54 g/day
5 cu.m/day (50%)
20 cu.m/day (50%)
0.2 mg/cm2 1 mg/cm2
Chemical-specific
Chemical-
specific
Children
Adults
7,200 cm2/event
20,000 cm2/ event
7,200 cm2/event
20,000 cm2/event
Figure 15
-------
Body Weights (BW)
Children (1-6 yrs) 16 kg
Adult 70 kg
Workers 70 kg
Average or
Central Tendency
Exposure Duration (ED)
Residential 9 years
Industrial 9 years
Exposure Frequency (EF)
Residential 350 days/year
Industrial 250 days/year
Averaging Time (AT)
Carcinogenic effects 70 years
Noncarcinogenic effects ED
16 kg (50%)
70 kg (50%)
70 kg (50%)
Reasonable
Maximum Exposure
30 years
25 years
350 days/year
250 days/year
70 years
ED
C. References For Central Tendency Exposure Parameters
Central Tendency
Basis/Reference
Concentration Term (C)
Site-specific value 95% UCL US EPA, 1992a
Contact Rates CCR)
Water Ingestion Rates
Children (1-6 yrs) 0.7 L/day US EPA, 1989a
Adults 1.4 L/day US EPA, 1989b
Workers 0.7 50% Adults Ingestion
Rate
Figure 15 (Cent.)
-------
Soil Ingestion Rates
Children (1-6 yrs)
Adults
Workers
Fish Ingestion Rates
Adults
200 nig/day
100 mg/day
50 mg/day
6.5 g/day
Central Tendency
Air Inhalation Rates
Children (1-6 yrs) 5 cu. m/day
Adults 20 cu.m/day
US EPA, 1989C
US EPA, 1989C
US EPA, 1991
US EPA, 1989b
Basis/Reference
US EPA, 1989a
US EPA, 1989a; US
EPA, 1989b
Dermal Exposure
Adherence factor (AF)
Absorption factor (ABS)
Total Surface Area (SA)
Children (1-6 yrs)
0.2 mg/cm2 US EPA, 1992b
Chemical-specific
7,200 cm2/ event
Adults
20,000 cm2/event
Body Weights (BW)
Children (1-6 yrs) 16 kg
Adult 70 kg
Workers
70 kg
US EPA,
1989a;
US EPA
1989b
US EPA, 1992b
US EPA, 1989b
US EPA, 1989b; US
EPA, 1991
US EPA, 1991
Figure 15 (Cont.)
-------
Exposure Duration (ED)
Residential 9 years US EPA, 1989b
Industrial 9 years to residential
Exposure Frequency (EF)
Residential 350 days/year US EPA, 1991
Industrial 250 days/year US EPA, 1991
Averaging Time (AT)
Carcinogenic effects 70 years US EPA, 1989b
Noncarcinogenic effects ED US EPA, 1989b
D. References For Reasonable Maximum Exposure Parameters
Reasonable Maximum
Basis/Reference
Concentration Term (C)
Site-specific value 95% UCL US EPA, 1992a
Contact Rates (CR)
Water Ingestion Rates
Children (1-6 yrs) 1 L/day US EPA, 1989a
Adults 2 L/day US EPA, 1989b;
US EPA,
1991
Workers 1 L/day US EPA, 1991
Soil Ingestion Rates
Children (1-6 yrs) 200 ing/day Average value,
US EPA,
1989C
Figure 15 (Cont.)
-------
Adults
Average value,
Workers
Fish Ingestion Rates
Adults
Air Inhalation Rates
Children (1-6 yrs)
Adults
Adults
100 mg/day
50 mg/day
54 g/day
US
EPA,
1989C
Average value, US
EPA,
1991
US EPA, 1991
5 cu. m/day US EPA, 1989a
20 cu.m/day
30 cu.m/day
Average value, US
EPA,
1989a;
US EPA,
1989b
Upper bound
#, US
EPA,
1989a;
US EPA,
1989b
Reasonable Maximum Basis/Reference
Dermal Exposure
Adherence factor (AF) 1 mg/cm2 US EPA, 1992b
Absorption factor (ABS) Chemical-specific
Total Surface Area (SA)
Children (1-6 yrs)
Adults
7,200 cm2/event Average value, US
EPA,
1989a;
US EPA,
1989b
20,000 cm2/event Average value, US
EPA,
1992b
Figure 15 (Cont.)
-------
Body Weights (BW)
Children (1-6 yrs)
EPA, 1989b
Adult
Workers
Exposure Duration (ED)
Residential
16 kg
70 kg
70 kg
Industrial
30 years
25 years
Average value, US
Average value, US
EPA, 1989b; US EPA,
1991
Average value, US
EPA, 1991
US EPA, 1989b; US EPA
1991
US EPA 1991
Exposure Frequency (EF)
Residential 350 days/year
Industrial
250 days/year
Averaging Time (AT)
Carcinogenic effects 70 years
Noncarcinogenic effects ED
Average value, US
EPA, 1991
Average value, US
EPA, 1991
US EPA, 1989b
US EPA, 1989b
Figure 15 (Cont.)
-------
Central Tendency References
US EPA. 1989a. Exposure Factors Handbook. EPA/600/8-89/043.
US EPA. 1989b. Risk Assessment Guidance for Superfund, Volume I,
Human Health Evaluation Manual (Part A). EPA/540/1-89/002.
US EPA. 1989c. Interim Final Guidance for Soil Ingestion Rates.
OSWER Directive 9850.4.
US EPA. 1991. Risk Assessment Guidance for Superfund, Volume I,
Human Health Evaluation Manual, Supplemental Guidance, Standard
Default Exposure Factors. OSWER Directive 9285.6-03.
US EPA. I992a. Supplemental Guidance to RAGS: Calculating the
Concentration Term. Publication 9285.7-081.
US EPA. 1992b. Dermal Exposure Assessment: Principles and
Applications. EPA/600/8-91/011B.
Figure 15 (Cont.)
-------
on-site. It is assumed that organisms occurring near sample
locations are likely to be exposed to measured contaminant
concentrations.
A rabbit was selected as an indicator organism from this group for
the community of small mammals likely to inhabit the site. It is
herbivorous, so it is exposed by the oral route through consumption
of vegetation growing in contaminated soil. Since it may drink
water from site and nearby surface waters, so exposure by the
drinking water route was evaluated. A second indicator organism
selected for quantitative estimation of dose on the predator
trophic level was the red-tailed hawk.
Ten metals and 11 organic compounds with known toxic properties are
present in soil, sediment and surface water associated with the
site. Low levels of toxic metals are present in surface water and
sediment that may cause adverse impacts to exposed aquatic life on-
site in nearby surface water bodies (ditches and canals).
The toxic metals present in on-site and off-site soil and toxic
organic compounds present in on-site soils are at levels that may
pose a risk of adverse impacts to exposed organisms. Herbivorous
mammals, e.g., rabbits, may be at risk from consumption of
vegetation growing in soil contaminated with barium and cadmium, at
on-site locations and from consuming surface water
on-site. Higher level predators, e.g., red-tailed hawks, are
unlikely to be impacted by consuming herbivorous prey on-site.
A number of uncertainties are associated with the analysis of
potential adverse ecological effects at this site. The detection
limits achieved for numerous compounds were high enough to
introduce significant uncertainty in the evaluation of the
potential for adverse biological effects and selection of chemicals
of potential concern for those chemicals with detection limits
above effect levels.
Bioavailability is a major uncertainty in interpreting the
potential for adverse biological effects from exposure estimates
based on measurements of bulk chemical concentrations in
environmental media. Chemical and physical changes in
environmental media that increase or decrease the solubility of
metals also increase or decrease their bioavailability.
Synergisms among chemicals present at exposure points may increase
the risk of adverse effects occurring in exposed organisms.
Significant uncertainty also exists for (1) literature-to-field
extrapolations for toxicity criteria and exposure parameters for
49
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home range and dietary estimates, (2) calculation of vegetative and
rabbit tissue concentration and assumptions regarding dietary
habits of the receptors assessed and (3) representativeness of
species selected.
Actual or threatened releases of hazardous substances from the GCV
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.
VII. REMEDIAL ACTION GOALS
A Remedial Action Goal is a chemical-specific-concentration for
each chemical of concern that helps determine whether a
contaminated media may be left in place or must be addressed by
in-situ treatment or excavated. Media exhibiting contaminant
concentrations below the remedial action goals may be left in-place
without treatment. Those wastes that exceed the remedial action
goals at the site will be addressed to meet requirements set forth
in the performance standards for each media. Remedial action goals
were developed for source material at the site including pit
sludges and associated soils, buried pits, (above ground) tank
contents, and site soils and sediments.
Source material remedial action goals address the following for
pathways of potential exposure: l) ingestion by humans; 2) direct
contact by humans, 3) inhalation by humans, and 4) contaminated
ground water ingestion. Health-based risk values were calculated
so that human ingestion of these source materials would not pose a
cancer risk greater than one in one million (1 x 1CT6) or a
noncarcinogenic risk of HI greater than or equal to 1.
Remedial Action Goals were also developed for the ground water in
the event that contingency measures are utilized. The ground water
Remedial Action objectives are set at levels which would allow use
of the water as a primary drinking water source.
A summary of remedial action goals for the site is shown in
Figures 16, 17 and 18.
In addition to these objectives the following remedial action goals
also apply:
Source Material: For other previously unidentified carcinogenic
compounds, maximum concentrations left untreated will be those
which produce a risk of 10"6 or less, assuming a residential
exposure consistent with the site risk assessment. For non-
carcinogenic compounds maximum concentration left untreated will be
50
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those with an HI less than or equal to 1.
Ground water (if contingency measures are employed): Ground water
must meet MCLs. For identified compounds without promulgated MCLs,
maximum concentrations left untreated will be those which produce
a risk of 10"* or less, assuming a residential exposure consistent
with the site risk assessment. For non-carcinogenic compounds the
maximum concentration left untreated must have an HI less than or
equal to 1.
Residual Ash/Treated/Stabilized Sludges. Soils and Sediments:
Must pass TCLP requirements for all identified compounds. Must
also meet or exceed MCLs using a modified TCLP test (distilled
water substituted for the specified acid). A dilution correction
is not required for the modified test.
Air Emissions for the Incinerator; 99.99% removal efficiency must
be achieved.
Ash Standards; Must meet remedial action goals. Additionally, the
residual ash must not contain dioxin concentrations greater than
1 ppb TCDD equivalents. Although dioxin is not considered a
significant site contaminant, the EPA wants to ensure that if it is
created during incineration, it will be addressed.
VIII. DESCRIPTION OF ALTERNATIVES
A feasibility study was conducted to develop and evaluate remedial
alternatives for the GCV site. Remedial alternatives were
assembled to address potential problems in four (4) media or waste
types, namely, tank contents, sludges and associated soils,
contaminated site soils and sediments, and contaminated ground
water. The alternatives for each of the four are developed
independently, although it is recognized that some interaction does
occur.
The majority of technologies and process options presented are
directed toward on-site treatment and onsite disposal for the waste
sludges, soils, and ground water. Any off-site removal of
hazardous substances must be in compliance with the NCP and EPA's
Off-Site Policy, (CERCLA Section 121(d)(3) 42 U.S.C. Section
9621(d)(3)) along with all other applicable Federal, State and
local requirements. In general, the effectiveness of the
technologies would be equivalent whether performed on-site or off-
site. However, the cost and implementability factors could change
significantly if the contaminated materials are treated and
disposed of at an off-site permitted and compliant treatment-
55
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storage-disposal (TSD) facility.
The remedial action alternatives for Operable Unit Number l for
each medium are presented below with a description of the common
elements contained in each alternative. The costs of several of
the alternatives differ from those in the proposed plan because the
estimates have been refined based on several factors. These
include taking into account completion of the Interim Action which
implements a part of the final action and, therefore, has redundant
costs, refinements to the alternatives and the public comments.
The refined cost estimates are presented in the Appendix. Note
that ground water monitoring will be implemented for perpetuity,
however, for costing purposes, 30 years was used.
A. sludges, Associated Soils and Tank Contents Remedial Action
Alternatives
This section addresses the sludge accumulation in and around the
Washout Pit, the West Pit, and the Former West Pit; an estimated
one-foot thick soil layer under and around the pits; liquids and
sludge residues from the aboveground storage tanks; and the
materials from the buried pits that were identified in the
historical aerial photo survey. The total amount of sludge and
associated soils is approximately 15,150 cubic yards. The amount
of liquid material in the above ground storage tanks is estimated
to be 12,000 gallons.
The primary contaminants of concern driving the risk from exposure
to the pit sludges are carcinogenic and noncarcinogenic PAHs along
with several inorganic constituents, including barium and arsenic.
In addition to the health risks, the sludge is a probable source
for the contamination of the underlying vadose zone soils and
ground water. The sludge from the two open waste pits has also
been shown to exceed the Toxicity Characteristics Leaching
Procedure (TCLP) limit for benzene. The contaminants of concern,
therefore, include both organic and inorganic (metal) constituents.
The volumes of material to be addressed under these alternatives
are listed below. These volumes assume excavation of the upper one
foot of soil which was assumed for cost estimating purposes. The
actual volume of soils excavated will be determined during the
construction phase of the remedy based on the depth of
contamination above remediation levels.
56
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Pit
Designation
West Pit
Former West Pit
Washout Pit
Suspected Areas
of Sludge
(2 pits)
Sludge
Volume
(yd3)
5,000
3,200
2,700
1,100
Associated
Soils
Volume
(yd3)
750
400
550
1,300
The storage tank contents are considered with the sludge and
associated soils remedial alternatives because of the relatively
small volumes of materials in the tanks compared to the pits and
the similar characteristics of the materials. The liquid contents
of the storage tanks would be handled separately from the sludge
material except in the case of onsite incineration. Detailed
alternatives for treating this material are described under each
sludge alternative presented below.
Tank No.
#1
#2
#3
#4
Horizontal
Tank
Volumes
Liquid
(gal)
Sludge
(gal)
Sludge
(yd3)
1750
2005
11
70
80016
29
8400
800
83
1150
6200
31
620
130
1
A brief description of the four alternatives evaluated to address
the Waste Pit Sludges, Associated Soils and Tank Contents follows:
o WP-1; No Action/Institutional Controls
o WP-2; Excavation, Stabilization/Solidification, On-
Site Disposal, Clay Cover, Offsite
Incineration of Tank Liquids
o WP-3; Excavation, On-Site Incineration, On-Site
Disposal of Residue, Clay Cover over
stabilized Residue
o WP-4; Excavation, Off-Site Incineration, Off-Site
Disposal of Residue
57
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1. Common Elements: Each of the alternatives listed above to
address the organic and inorganic-contaminated sludges, associated
soils and tank contents have the following common elements: site
preparation, restoration of the site surface upon completion of the
remedial action, issuance of deed notices, (although non-
enforceable, to advise future owners about the risks of disturbing
the cover and/or the underlying material), and ground water
monitoring which would be implemented for perpetuity to assure that
contaminant levels in the ground water did not increase due to
materials left onsite and to ensure that individuals did not drink
contaminated ground water.
All of the alternatives, except Alternative WP-1, would involve
excavation of approximately 12,000 cubic yards of sludge and 7950
cubic yards of associated soils, and the removal of 11,990 cubic
yards of tank liquids and 155 cubic yards of tank sludges. The
interiors of the five tanks would be accessed, purged, and cleaned
prior to cutting the tanks for recovery as scrap iron or disposal.
All of the alternatives, with the exception of WP-1 involve the
handling of a RCRA characteristic hazardous waste. The pit sludges
have been found to be characteristic for TCLP (benzene) .
Therefore, the waste that is incinerated in Alternative WP-2
through WP-4 must meet the applicable Land Disposal Restrictions
(LDRs) criteria. LDRs are the restrictions placed on the land
disposal of RCRA hazardous wastes. Specifically, the waste must no
longer be characteristic prior to land disposal. These do not
apply to in-situ treatment.
All of the alternatives, with the exception of Alternative WP-1
involve treating and/or containing soils and sediments which have
contaminant concentrations that exceed remedial action goals.
Alternative WP-1 and WP-2 will not meet the remedial goals for the
site. Alternative WP-3 and WP-4 will meet the remedial goals for
the organics, and will meet the remedial action goals for the
arsenic and barium. Since the inorganics cannot be destroyed the
remedial action cleanup goals include a definition of effective
stabilization.
All of the alternatives with the exception of WP-1 include air
monitoring during excavation and incineration. The monitoring
would be on-site and at the site boundary during excavation and on-
site and in the community during incineration.
All costs and implementation times are estimates. The costs have
a degree of accuracy of +50% to -30% pursuant to the "Guidance for
Conducting Remedial Investigations and Feasibility Studies Under
CERCLA - Interim Final" OSWER Directive 9355.301, October 1988.
As noted previously, that costs for the sludges, associated soils
and tank contents alternatives have been revised since the proposed
plan. (See Appendix II).
58
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2. Alternative WP-l: No Action/Institutional Controls
Capital Cost: $99,000
Operation and Maintenance (annual): $38,400
Total Cost (present worth): $564,000
Time of Implementation:
Set-up: 2 months
Ground water Monitoring: 30 years (total)
Regardless of the effectiveness of the no action alternative in
meeting the remedial action goals for the GCV site, the NCP
reguires that, as appropriate, alternatives that involve little or
no treatment, but afford some level of protection be carried
through to the detailed analysis of alternatives. The no action
alternative will be carried through to provide a baseline of
comparison to the alternatives utilizing some form of treatment.
The above-mentioned costs are discussed below:
Major Components of the Remedial Alternative: The major feature of
this alternative is the use of institutional controls to keep the
public away from the contamination with the use of signs and a
fence. Under this alternative, there would be no remediation of
the waste pit sludges and associated soils, the contents of the
site storage tanks, and the materials in the buried pits.
Treatment Components: There is no treatment element in Alternative
WP-l, since it will involve institutional controls only.
Containment Components: There is no containment element in this
alternative since the contaminated material is left in place.
ARARs are discussed with relation to remedial actions. If no
action is taken, ARARs are irrelevant.
General Components: The estimated time to implement this remedy is
2 months. Institutional controls and ground water monitoring shall
be implemented. The estimated costs for this no action alternative
are: Capital costs: $99,000; O&M costs (annual): $38,400; Present
worth: $564,000. EPA does not favor this alternative because it
would not decrease the toxicity, mobility, or volume of
contaminants or address the public health or environmental risks.
3. Alternative WP-2: Excavation, On-site Stabilization/
Solidification, On-Site Disposal, Clay Cover, Off-site Incineration
of Tank Liquids
Capital Cost: $1,939,000
Operation and Maintenance (annual): $9,800
Total Cost (present worth): $1,939,000
Time of Implementation: 9-11 months
59
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Manor Components of the Remedial Alternative: The major feature of
this alternative is the excavation, stabilization, containment and
burial of about 12,000 cubic yards of waste sludges, 7950 cubic
yards of associated soils and 21,230 gallons of tank sludges from
the three pits, the buried pits and the tanks on the site. All
waste would be excavated to cleanup goals and then mixed with
additives in an attempt to stabilize/solidify the material. Once
completed this material would be buried on site and covered with a
clay cap.
This alternative also includes provisions for the off-site thermal
treatment and disposal of about 155 cubic yards of tank sludges.
Onsite and offsite air monitoring would be required.
Treatment Components: There is only a minimal treatment element in
Alternative WP-2, since studies have indicated the technical
inability to stabilize highly organic wastes similar to those found
at this site. The only treatment that may be effective would be
the chemical bonding of the inorganic contaminants. The
effectiveness of this is also suspect, however, due to the
complexity of the matrix and the possibility of interference from
the organics. Offsite thermal destruction of the tank sludges
would be considered treatment.
Containment Components: Batches of the combined wastes from the
pits and the tanks would be mixed with appropriate stabilization/
solidification agents, and placed in a new excavation located in
the Northeast Area onsite. Clean soil would be used to replace the
material excavated from the pits. After the treated wastes were
solidified, a compacted clay cover would be placed over the
excavation. Berms, drainageways, and general grading would be
constructed to divert surface water away from the covered area.
LDRs are not applicable, however, treatment goals would require
that the treated matrix not leach organic or inorganic contaminants
above applicable drinking water criteria using appropriate leaching
tests (solvent extraction for organics; acid wash for inorganics).
General Components: The estimated time to implement this remedy is
9-11 months. Institutional controls and ground water monitoring
would also be implemented for perpetuity. The estimate costs are
Capital Costs: $1,857,000; O&M Costs: $9,800 (annual); Present
Worth: $1,962,000.
This alternative would reduce, to some level, the rate of
contaminant release to the ground water. It would however, still
leave organic contaminated waste on site without effective
treatment. EPA does not favor this alternative because it would
not adequately decrease the public health or associated risks from
the organic contaminants.
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4. Alternative WP-3 Excavation, On-Site Incineration, Residue
Stabilization/Solidification, On-Site Disposal of Ash, Clay cover
Over Stabilized Residue
Capital Cost: $9,907,000
Operation and Maintenance (annual): $7,600
Total Cost (present worth): $9,907,000
Time of Implementation: 24-26 months
Major components of the Remedial Alternative: As with Alternative
WP-2 about 12,000 cubic yards of waste sludges and 7950 cubic yards
of associated soils and 21,230 gallons of tank sludges from the
three pits, the buried pits and the tanks on the site would be
excavated. However, in Alternative WP-3, this waste would be
combined with the 155 cubic yards of tank sludges and incinerated
onsite. The required destruction efficiency would be 99.99% as
required by 40 CFR, Supbart 0. Residual material (ash) would be
stabilized/solidified if inorganic contaminant concentrations in
the ash exceed the remedial action objectives. The material would
be stabilized as discussed in the Remedial Action Objectives
Section of this decision document. The stabilized/solidified
treatment residuals would be buried and capped on-site. Onsite and
offsite air monitoring would also be required.
Treatment Components: The organic and inorganic-contaminated site
sludges, associated soils and tank contents would be incinerated
on-site using a transportable incinerator. The facility would be
operated to meet the technical regulatory standards for incinerator
performance set by the State and Federal government. All air
emissions would be treated to remove particulates and gases. The
organic materials would be destroyed and their remedial goals met,
while the metals and other inorganic matter and soil constituents
would be recovered as ash. This material would then be stabilized
as necessary. The effectiveness of stabilization for inorganic
contaminants is well-documented.
Operating conditions for the incinerator would be based on
applicable regulations, the results of the treatability studies
conducted on the GCV waste (reference "Treatability Study Report
for the Remedial Investigation/Feasibility Study at the Gulf Coast
Vacuum Services, Inc. Superfund Site") and the results of trial
burns conducted once the incinerator was brought on-site. Site
treatability studies indicated that incineration was effective in
reducing the organic contaminants below the remedial action
objectives.
Containment Components: The residual ash would be placed in an
onsite excavation. This area would be capped with a clay cap.
The cap will be designed and constructed to promote drainage,
minimize erosion of the cover, and provide long-term minimization
of migration of liquids through the underlying soils. Long-term
61
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operation and maintenance (O&M) would be conducted to monitor the
ground water around the buried material and to ensure the integrity
of the cap consistent with 40 CFR 262.117.
General Components: The estimated time to implement this remedy is
24-26 months. Institutional controls and ground water monitoring
shall be implemented. The estimated costs are Capital Costs:
$9,932,000; O&M Costs: $7,600 (annual); Present Worth:
$10,015,000.
This alternative, unlike alternatives WP-1 and WP-2 does reduce the
volume, mobility and toxicity of the contaminated media through
treatment, and stabilizes the inorganic residual to mitigate the
risk of leaching into the ground water. The risk from air
emissions under this alternative during incineration, considering
strict controls of the resultant gases, should be minimal. This is
EPA's favored alternative because it will destroy organic
contaminants, stabilize the inorganics, and will be the most
protective to human health and the environment of all of the
alternatives except WP-4, at a much lower cost than WP-4.
5. Alternative WP-4: Excavation/ Off-Site Incineration, Off-Site
Disposal of Residue
Capital Cost: $26,522,000
Operation and Maintenance (annual): $7,600
Total Cost (present worth): $26,605,000
Time of Implementation: 7-9 months
Major Components of the Remedial Alternative: This alternative
would be similar to Alternative WP-3, with the exception that the
sludges and associated soils would be transported off-site to a
permitted facility for incineration and ash disposal. The disposal
facility would have to be in compliance with EPA's Offsite Policy.
Alternative 4 involves excavating the sludge and associated soils
from the three waste pits and buried pits, adding the storage tank
contents, conditioning the combined waste for truck transport, and
shipping the material to a permitted and EPA-approved TSD facility.
This alternative would also require onsite and offsite air
monitoring.
Treatment Components: The waste would be incinerated and the ash
would be disposed of in an approved manner by the TSD facility
operator. Ash generated during the incineration process would
possibly require stabilization to immobilize the metals prior to
disposal. This would be necessary to minimize leachate generation
potential. Over 1,000 truckloads of the conditioned sludge/soil
material would be removed from the site.
Containment Components: The residual ash would be disposed of in
62
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a manner consistent with the TSD facility's permit.
residuals would be stored or contained at the GCV site.
No ash
General Components: The estimated time to implement this remedy is
7-9 months. Institutional controls and ground water monitoring
shall be implemented for the existing ground water contamination.
The estimated costs are Capital Costs: $26,522,000; O&M Costs:
$7,600 (annual); Present Worth: $26,605,000.
Although this alternative is the most protective of human health
and the environment at the GCV site since it removes both the
organic and inorganic constituents, it is the most expensive remedy
by an order of magnitude. "Overall" environmental protectiveness
is the same for Alternatives WP-3 and WP-4. Whether the material
remains at the site or disposed of at a permitted TSD, the residual
wastes will present similar environmental risks. The additional
"site" protectiveness gained by the off-site treatment and disposal
of the sludges, associated soils and tank contents is not
proportional to the reduction in risk.
B. site Soils and Sediments Remedial Action Alternatives
This section addresses the site soils and sediments. The estimated
quantity of this contaminated media is 19,500 cubic yards.
Location
Site Field and Northeast
Area Surface Soils
Surface Sediments
Soil
Volume
Estimate
(yd3)
18,900
600
The primary contaminants of concern contributing to health risk
from exposure to site soils and surface sediments are arsenic and
barium. (See Figure 17) The site soils, particularly in the
Northeast Area and Site Fields, are potential sources for ground
water contamination of the Upper Aguifer Unit in those areas.
o Alternative S-l:
o Alternative S-2:
o Alternative S-3:
No Action/Institutional Controls
Excavation, stabilization, On-Site
Disposal, Clay Cover
Excavation, Stabilization, Off-Site
Disposal
1. Common Elements: Two alternatives involve excavation of
approximately 19,500 cubic yards of soils and sediments. This
volume is calculated with the assumption that only the top 2 feet
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of soil exceed remedial action levels. The actual volume of soils
and sediments could change during the construction phase of the
remedy.
Each of the alternatives listed address the inorganic-contaminated
site soils and sediments and have the following common elements,
site preparation, restoration of the site surface upon completion
of the remedial action, issuance of deed notices (although non-
enforceable, to advise future owners about the risks of disturbing
the cover and/or the underlying material), and ground water
monitoring which would be implemented for perpetuity to assure that
contaminant levels in the ground water do not rise due to leaching
from the material left onsite. (The site soils_ and sediments are
not contaminated with organic constituents above health based
levels).
Each of the alternatives, with the exception of Alternative S-l,
involves treating and containing soils and sediments which have
contaminant concentrations that exceed remedial action goals.
Alternative S-l will not meet the remedial objectives for the site.
Alternative S-2 will remediate the site field and Northeast area
surface soils and the surface sediments to clean-up levels, but the
area where these materials would be placed will require capping.
Alternatives S-2 and S-3 would meet the remedial goals.
Alternatives S-2 and S-3 would reduce the mobility (but not volume
and toxicity) of the inorganic contaminated media through
treatment. These alternatives would stabilize this material and
consolidate it, mitigating the risk of the metals leaching into the
ground water.
The potentially Applicable or Relevant and Appropriate Requirements
(ARARs) for these alternatives include RCRA Subpart F (releases
from solid waste management units) and G (closure and post-closure)
of 40 CFR 264. Alternative S-l would not meet these ARARs while
Alternatives S-2 and S-3 would. These are potentially relevant
standards since treated materials would be land disposed. Since no
LDR wastes will be managed under this alternative, the LDRs do not
apply.
All costs and implementation times are estimates. The costs have
a degree of accuracy of +50% to -30% pursuant to the "Guidance for
Conducting Remedial Investigations and Feasibility Studies Under
CERCLA - Interim Final" OSWER Directive 9955.3-01, October 1988.
Note that costs for the site soils and sediments alternatives have
been revised since the Proposed Plan. (See Appendix II).
64
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2. Alternative S-l: NO Action/Institutional Controls
Capital Cost: $99,000
Operation and Maintenance (annual): $38,400
Total Cost (present worth): $564,000
Time of Implementation:
Set-up: 2 months
Major Components of the Remedial Action: This alternative is
identical to Alternative WP-1. For this alternative, no action
would be taken with respect to the site soils and sediments. A
fence would be constructed around the site to restrict access to
the site by unauthorized people and wildlife. Warning signs would
be posted. Institutional controls such as deed notices would be
used to advise future owners of the potential health risks from
exposures to any of these wastes and associated soils, however deed
notices are not enforceable. The ground water would be monitored
for perpetuity.
There is no RCRA listed or characteristic hazardous waste being
handled. However, the post-closure ground water monitoring
requirements (40 CFR 264.117, Subpart F) may be relevant. Since
wastes would remain buried at the site without being treated or
contained, there are no ARARs that are applicable.
Treatment Components: There is no treatment element in Alternative
S-l, since it will involve institutional controls only.
Containment Components: There is no containment element in this
alternative since the contaminated material is left in place.
General Components: The estimated time to implement this remedy is
2 months for set up of the institutional controls and a 30 years
for installation of wells. The estimated costs are: Capital
Costs: $99,000; O&M Costs: $38,400 (annual); Present Worth:
$564,000.
EPA does not favor this alternative because it would not decrease
the toxicity, mobility, or volume of contaminants or reduce public
health or environmental risks.
3. Alternative 8-2: Excavation/ Stabilization/ On-Site Disposal,
Clay Cover
Capital Cost: $2,366,000
Operation and Maintenance (annual): $10,450
Total Cost (present worth): $2,477,000
Time of Implementation: 12-14 months
Major Components of the Remedial Alternative: The major features
of this alternative are the excavation, stabilization and
65
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containment of 19,500 cubic yards of site soils and sediments.
Identified areas of contamination would be excavated to remedial
cleanup levels (health-based standards) and then stabilized to meet
the criteria outlined in the Remedial Action objectives section of
this document. The excavated areas would be backfilled with clean
soil.
Treatment Components: There is a treatment element in Alternative
S-2, since it will involve excavation and effective on-site
stabilization soils and sediments. The inorganic material will be
chemically bonded, thus mitigating its leaching potential into the
ground water. Stabilization is an established and effective means
of treating inorganic contamination in soils.
Containment Components: The soils and sediments impacted by site-
specific contaminants would be excavated, mixed with an agent to
stabilize and solidify the inorganic (metal) constituents, disposed
of in an on-site excavation and covered with compacted clay. The
disposal cell would be unlined, with the bottom at least five feet
above the seasonal high ground water table. It would be necessary
to maintain the bottom of the excavation above the seasonal-high
water table to further reduce the potential for leaching of
contaminants from the waste material into the ground water. The
highest water level recorded in that area is approximately 17 ft
below ground surface.
The cap will be designed and constructed to promote drainage,
minimize erosion of the cover, and provide long-term minimization
of migration of liquids through the underlying soils. Long-term
operation and maintenance (O&M) would be conducted to monitor the
ground water around the landfill and to ensure the integrity of the
cap consistent with 40 CFR 262.117.
General Components: The estimated time to implement this remedy is
9-11 months. Institutional controls and ground water monitoring
shall be implemented. The estimate costs are: Capital Costs
$1,857,000; O&M Costs $9,800 (annual); Present Worth $1,962,000.
This alternative does reduce the mobility of the inorganic
contaminated media through treatment. Existing organic
constituents in the surface soils and sediments are below health-
based levels. This alternative would be significantly more
protective of human health and the environment than Alternative S-l
and comparable to Alternative S-3 for a greatly reduced cost over
Alternative S-3. For this reason is EPA's favored alternative.
4. Alternative S-3: Excavation, Stabilization, Off-Site
Disposal
Capital Cost: $17,825,000
Operation and Maintenance (annual): $0
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Total Cost (present worth): $17,825,000
Time of Implementation: 10-12 months
Major Components of the Remedial Alternative: This alternative
provides for the excavation and stabilization of the affected site
soils and sediments as described under Alternative S-2. However,
following the stabilization of the material, it would be
transported for disposal at a permitted TSD facility that was in
compliance with EPA's Off-Site policy.
Treatment Components: The treatment element in Alternative S-3, is
stabilization. The inorganic material would be much less likely to
leach into the ground water. Since this material would be sent
off-site for disposal, it would no longer pose a- risk at the site.
Containment Components: The stabilized soils and site sediments
would be disposed of in a manner consistent with the TSD facility's
permit. No stabilized contaminated material would be stored or
contained at the GCV site.
General Components: The estimated time to implement this remedy is
10-12 months. Institutional controls and ground water monitoring
shall be implemented. The estimated costs are Capital Costs
$17,825,000; O&M Costs $0; Present Worth $17,825,000.
Although this alternative is the most protective of human health
and the environment at the GCV site since it eliminates the
contaminated material from the site, it is the most expensive
remedy; 8 times as expensive as Alternative S-2. The added site
protectiveness gained by the off-site treatment and disposal of the
site soils and sediments is not proportional to the reduction in
risk. Additionally, from an overall environmental protectiveness
perspective, this alternative offers equivalent protection to that
for Alternative S-2; Alternative S-3 only relocates the treated
waste.
c. Ground Water Remedial Action Alternatives
The ground water contaminants that were detected above the
respective MCLs include barium, cadmium, chromium, and mercury.
(See Figure 18). These contaminants were identified in the Perched
and Upper Aquifer units. Benzene was detected in ground water
samples collected from one well, but is not pervasive
over the whole site. A free-phase hydrocarbon layer was also
identified in one well and several deep soil borings in the
localized area around the pits. It also is very limited in lateral
and vertical extent.
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The following two alternatives are evaluated for addressing the
ground water contamination:
o Alternative G-l: No Action/Institutional Controls
o Alternative G-2: Ground water Extraction, Treatment,
Discharge to Site Drainage Ditch
Common Elements: Each of the alternatives listed above to address
the contaminated ground water have the following common elements:
site preparation, restoration of the site surface upon completion
of the remedial action, installation of warning signs and fences,
issuance of deed notices, although non-enforceable, to advise
future owners about the risks of disturbing the cover and/or the
underlying material, and ground water monitoring which would be
implemented for 30 years to assure that contaminant levels in the
ground water do not rise due to leaching from the excavated areas
or on buried materials.
Safe Drinking Water Act (SDWA) Maximum Contaminant Levels (MCLs)
represent the maximum permissible level of a contaminant in water
that may be delivered to the free-flowing outlet of the ultimate
user of a public water system [40 CFR 141.2(c)]. Because ground
water has been identified as a potential source of drinking water,
MCLs are potential ARARs since they may be applicable, relevant and
appropriate.
All costs and implementation times are estimates. The costs have
a degree of accuracy of +50% to -30% pursuant to the "Guidance for
Conducting Remedial Investigations and Feasibility Studies Under
CERCLA - Interim Final" OSWER Directive 9955.3-01, October 1988.
Contingency measures:
If it is determined that contingency measures are needed to address
contamination in the ground water, EPA may require implementation
of further response actions consistent with the contingency
measures. Actions that might be required include, but are not
limited to, the following:
Submittal of a Remedial Action Plan describing a plan for
the extraction, treatment, or disposal of contaminated
ground water in order to achieve State and Federal
standards.
Installation of additional monitoring wells to confirm and
better define the changing conditions in contaminant
concentrations.
If contingency measurement criteria (exceedance of MCLs)
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are triggered, extraction of contaminated water (or
accelerate) to facilitate cleanup of the affected area
and/or its source.
1. Alternative 6-1: No Action/Institutional Controls
Capital Cost: $99,000
Operation and Maintenance (annual): $38,400
Total Cost (present worth): $564,000
Time of Implementation:
Set-up: 2 months
Major Components of Remedial Action: Under the no action portion
of this alternative, no active measures would be taken to correct
the existing ground water contamination. Under this alternative,
ground water monitoring wells would be sampled biannually to track
long-term changes in the contaminant concentrations. Both the
Upper Aquifer Unit and the Lower Aquifer Unit would be monitored.
Ground water monitoring may include modification of the existing
network of wells to identify changes in ground water quality. This
alternative, in and of itself, would not prevent continued ground
water contamination. However, as explained below, if site
conditions worsen over time, contingency measures for active
remediation would be implemented as necessary.
Since treatment is not a principal element of this alternative, the
alternative does not meet, by itself, the Superfund preference for
treatment of contaminants. EPA has determined, however, that
active treatment of the ground water is not warranted at this time.
This determination is conditioned upon implementation of Source
Control measures and is based on EPA's evaluation of site specific
data indicating that ground water contamination currently is very
limited in extent. Natural attenuation is believed to be able to
address the existing contamination so that it will not present an
environmental or human health threat.
Also, based on the pump test and analysis, future concentrations of
site contaminants are not expected to exceed any applicable State
or Federal standard beyond the property boundaries. Thus, active
remediation of the aquifer is not considered necessary at this
time. Since on-site sources of contaminants would be eliminated or
controlled, the contaminants present in the ground water would be
reduced gradually through natural attenuation and dilution.
The time period over which natural attenuation is expected to occur
is difficult to determine because of the nonhomogeneous nature of
the hydrogeologic units under the site. An approximation, based on
the aquifer properties and contaminants, would be on the order of
30 years, which is used in the costs for this alternative.
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General Components: The estimated time to implement this remedy is
2 months for set-up. The estimated costs are: Capital Costs
$99,000; O&M Costs $38,400 (annual); Present Worth $564,000.
NO ACTION
Due to the limited contamination of these aquifers, Alternative
G-l is EPA's preferred alternative to address the ground water
contamination. This alternative provides for natural attenuation
to reduce contaminant concentrations in the ground water. The
alternative also provides for ongoing monitoring of site wells
established as part of the ground water monitoring program during
remedy design to determine 1) whether natural attenuation of the
contamination is taking place, and 2) whether the extent of
contamination has spread or diminished. If concentrations
significantly rise or a risk of imminent exposure surfaces,
contingency measures will be implemented.
The selected remedy and contingency measures are protective of
human health and the environment, comply with Federal and State
requirements that are legally applicable or relevant and
appropriate to the remedial action, and are cost-effective.
Treatment of the contaminated ground water was not found to be
warranted at this time. If monitoring data indicates that the
contingency measures need to be implemented, treatment may take
place.
2. Alternative 6-2: Ground Water Extraction, Treatment,
Discharge to site Drainage
Capital Cost: $578,000
Operation and Maintenance (annual): $204,300
Total Cost (present worth): $1,917,000
Time of Implementation:
Set-up: 7-9 months
Pump and Treat: 10 years aquifer restoration
Major Components of Remedial Action: This alternative would employ
pumping of the ground water to the surface for treatment.
Physical/chemical treatment aimed primarily at the inorganics would
be used so that remedial goals for the ground water would be
achieved. (If organic contamination exists above discharge limits,
these too will be treated). The ground water would be collected
and treated primarily to remove the principal inorganic (metal)
contaminants. The treatment media (such as resins and carbon
particles) and removed residues would be treated or destroyed off-
site via approved off-site facilities. The treated ground water
would also be discharged to the site drainage system. Ground water
monitoring would be required.
General Components: The estimated time to implement this remedy is
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7-9 months set-up, 10 years for complete aquifer restoration. The
estimated costs are: Capital Costs $578,000; O&M Costs $204,300
(annual); Present Worth $1,917,000.
This alternative would be the primary contingency measure used if
implementation of Alternative G-l, EPA's preferred alternative is
not effective. The costs of this alternative compared to those of
Alternative G-l are very high and at the present time would not
result in a proportional decrease in risk since no one is currently
using the contaminated ground water and likely will not before the
concentrations achieve MCLs.
IX. SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
The EPA uses nine criteria to evaluate alternatives for addressing
a Superfund site. These nine criteria are categorized into three
groups: threshold, balancing, and modifying. The threshold
criteria must be met in order for an alternative to be eligible for
selection. The balancing criteria are used to weigh major
tradeoffs among alternatives. The modifying criteria are taken
into account after State and public comments are received on the
Proposed Plan of Action.
Nine Criteria
The nine criteria used in evaluating all of the alternatives are as
follows:
A. Threshold criteria
Overall Protection of Human Health and the Environment addresses
the way in which an alternative would reduce, eliminate, or control
the risks posed by the site to human health and the environment.
The methods used to achieve an adequate level of protection vary
but may include treatment and engineering controls. Total
elimination of risk is often impossible to achieve. However, a
remedy must minimize risks to assure that human health and the
environment are protected.
Compliance with ARARsf "applicable or relevant and appropriate
requirements," assures that an alternative will meet all related
Federal, State, and local requirements.
B. Balancing Criteria
Long-term Effectiveness and Permanence addresses the ability of an
alternative to reliably provide long-term protection for human
health and the environment after the remediation goals have been
accomplished.
Reduction of Toxicitv. Mobility, or Volume of Contaminants through
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Treatment assesses how effectively an alternative will address the
contamination on a site. Factors considered include the nature of
the treatment process; the amount of hazardous materials that will
be destroyed by the treatment process; how effectively the process
reduces the toxicity, mobility, or volume of waste; and the type
and quantity of contamination that will remain after treatment.
Short-term Effectiveness addresses the time it takes for remedy
implementation. Remedies often require several years for
implementation. A potential remedy is evaluated for the length of
time required for implementation and the potential impact on human
health and the environment during implementation.
Implementability addresses the ease with which -an alternative can
be accomplished. Factors such as availability or materials and
services are considered.
Cost (including capital costs and projected long-term operation and
maintenance costs) is considered and compared to the benefit that
will result from implementing the alternative.
C. Modifying Criteria
State Acceptance allows the State to review the proposed plan and
offer comments to the EPA. A State may agree with, oppose, or have
no comment on the proposed remedy.
Community Acceptance allows for a public comment period for
interested persons or organizations to comment on the proposed
remedy. EPA considers these comments in making its final remedy
selection. The comments are addressed in the responsiveness
summary which is a part of this ROD.
D. Comparative Analysis of Alternatives
1. Overall Protection of Human Health and the Environment
All of the alternatives, except No Action, will provide some degree
of overall protection of human health and the environment. The
degree to which each alternative provides this protection is
discussed below.
a. Sludges, Associated Soils and Tank Contents
The No Action alternative provides an insignificant increase in the
overall protection to human health and the environment. Under this
alternative, all of the potential risks to human health and the
environment associated with the Gulf Coast Vacuum site would
remain. Institutional controls, would only minimally address the
risk since these controls are unenforceable and temporary. The
long-term risk associated with potential exposure would not be
reduced, nor would this alternative address the potential risk to
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future onsite workers or residents.
Alternatives WP-2 would reduce to a limited degree the risk from
direct contact with the sludges and soils on-site by covering the
solidified material with a cap. The cap will also minimize the
potential for air emissions from the site as long as it is
undisturbed. Stabilization/Solidification would reduce the
mobility of the inorganic contaminants, however, the organic
contaminants would still pose a risk. Since stabilization would be
ineffective, some risk from direct contact and migration to the
ground water would remain.
Alternative WP-3 would be significantly more protective than
Alternative WP-2 since the organic contaminants wpuld be destroyed.
The inorganic contaminants would remain, but they would be
effectively stabilized and consolidated and would be capped.
Therefore, the potential risk of the metals migrating into the
ground water would be minimized.
The most protective alternative, specific to the site location, to
human health and the environment for the sludges, associated soils
and tank contents is Alternative WP-4 which would totally eliminate
the site specific risks by sending the waste off-site for Treatment
and disposal. Overall protectiveness is equivalent to WP-3 since
this alternative simply relocates the inorganic wastes.
b. site Soils and Sediments
The No Action alternative provides an insignificant increase in the
overall protection to human health and the environment. Under this
alternative, all of the potential risks to human health and the
environment associated with the site soils and sediments would
remain. This would address some risk since controls would make
more difficult direct human contact with this material.
Alternative S-2 would substantially reduce the risk from direct
contact by stabilizing the contaminated media and covering the
matrix with a clay cap. Stabilization would reduce the mobility of
the inorganic contaminants, the principal contaminants in the site
soils and sediments. Future risk from direct contact and migration
to the ground water would be mitigated using stabilization.
The most protective alternative for the actual site, to human
health and the environment for the site soils and sediments is
Alternative S-3 which would totally eliminate the risks posed by
the site by sending the waste off-site for treatment and disposal.
No contaminated material would remain, it would be relocated to a
separate location. Transportation of hazardous substances would
pose a temporary risk.
c. Ground water
I The No Action alternative provides some increase in the overall
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protection to human health and the environment. Under this
alternative, all of the potential risks to human health and the
environment associated with the contaminated ground water would
remain, however, the use of institutional controls would minimize
the ingestion risk since direct contact with this material would be
reduced and monitoring would assure that the quality of the ground
water was not further degrading. It is important to recognize the
limited scope of the contamination and unlikely exposure during the
monitoring period.
Alternative G-2 is more protective of human health and the
environment because it provides for the treatment of the
contaminated aquifer to MCLs. Ground water would not pose a risk
to human health at acceptable drinking water levels.
2. Compliance with Applicable or Relevant and Appropriate
Requirements (ARARS)
a. Sludges, Associated Soils and Tank Contents
ARARs are Federal and State substantive, promulgated, environmental
requirements that the selected remedial action must meet. The
sludges contaminated with benzene were found to be a characteristic
hazardous waste under RCRA, 40 CFR Subpart C, so certain ARARs
apply. Since the waste leached above 50 ppm of benzene when
analyzed using TCLP, it is considered hazardous and regulated under
RCRA if "managed". Furthermore, if a RCRA regulated waste is
treated, additional ARARs apply.
All of the alternatives evaluated had common ARARs which include
elements of Subparts F and G of the Standards for Owners and
Operators of Hazardous Waste Treatment, Storage and Disposal
Facilities (40 CFR § 264). Subpart F requires that any hazardous
waste releases be investigated and corrective action taken if
necessary. Subpart G requires the proper closure of hazardous
waste units.
Although waste is not managed under WP-1, this alternative does not
meet the spirit of the regulations since hazardous substances are
left onsite unaddressed. The RCRA LDRs are applicable to the
hazardous wastes that are actively managed in Alternatives WP-2
through WP-4.
Alternative WP-3 and WP-4, because they involve incineration would
be required to meet the standards set by the Federal government for
the operation of hazardous waste incinerators 40 CFR § 264,
Subpart O. Any ash generated in the incineration process would
also have to meet Federal hazardous waste regulations in their
stabilization and landfill process if characteristic. Alternative
WP-4 must additionally comply with EPA's Offsite Policy. WP-3
would exceed Federal requirements insofar as the ash would be
treated to remedial goal levels.
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Alternatives WP-3 and WP-4 are designed to assist indirectly in
meeting chemical-specific ARARs for other media such as ground
water since they effectively address source material. WP-2 is not
included since stabilization of highly organic material is
ineffective.
b. Site Soils and Sediments
The three alternatives evaluated had a common ARAR which includes
Subparts F and G of the Standards for Owners and Operators of
Hazardous Waste Treatment, Storage and Disposal Facilities (40 CFR
Part 264). Subpart F requires that any hazardous waste releases be
investigated and corrective action taken if necessary. Subpart G
requires the proper closure of hazardous waste units.
The RCRA LDRs are not applicable to the hazardous materials that
are actively managed in Alternatives S-l through S-3 because no
land disposal restricted hazardous waste will be managed. The LDRs
are considered relevant, however, and will be complied with to the
extent that all material will be stabilized to a level that would
be protective of human health and the environment.
Alternatives S-2 and S-3 are designed to assist indirectly in
meeting chemical-specific ARARs for other media such as ground
water since they address source material.
c. Ground water
Alternative G-l is expected to meet the National Primary Drinking
Water Standards and the Health Based Standards through natural
attenuation and dilution. Although no active treatment is
anticipated, proper monitoring and institutional controls are
believed to be effective for ensuring that individuals do not
ingest the contaminated ground water.
Alternative G-2 would utilize ground water remediation technology
to lower contaminant levels in the aquifer. The goal of this
alternative is to lower ground water contaminant concentration at
the GCV site to meet ARARs within ten years. As with G-l, however,
it is not known at this time if the remedial goals are technically
achievable due to the large amount of clays in the subsurface at
the GCV Site which contain contamination. It has been found at
many other Superfund sites with similar contaminants and geologic
situations that aquifer clean-up goals are often not achieved
because of the very slow desorption rate of contaminants from
soils.
Alternative G-2 will further be required to comply with National
Pollutant Discharge Elimination Standards established by the State.
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3. Long-term Effectiveness and Permanence
a. Sludges, Associated Soils and Tank Contents
Of the sludge, associated soils and tank content alternatives,
Alternatives WP-3 and WP-4 provide the highest degree of long-term
effectiveness and permanence because the organics in the
contaminated material would be ultimately destroyed through
treatment and the inorganics effectively stabilized (if necessary) .
Alternative WP-4 would require disposal of all stabilized material
at a TSD facility that complies with EPA's Off-site Policy and
because the material would be removed from the site, the potential
for site specific migration to ground water would be eliminated.
Preliminary results from the thermal treatability study conducted
on the GCV soils and sludges indicate that the organics are
destroyed and that ash resulting from the incineration of the
sludge passes the TCLP test by a large margin. Therefore, the ash
is not anticipated to contain inorganic concentrations that pose a
large risk. Although exposure to inorganics on the GCV property
will be significantly reduced by the stabilization and capping of
the metal-contaminated ash from the incinerator in Alternative
WP-3, management of the residual ash on site does not fully
eliminate the potential for exposure to barium or other inorganics
in the long term.
Alternative WP-2 is less effective in the long term than
Alternative WP-3 and WP-4 since the organic contaminants are not
adequately treated and would eventually be released to the
environment, although the stabilization of the inorganics may
provide for a measure of long term effectiveness. But, as
mentioned before, the organic matrix interference may impact the
integrity of the inorganic stabilization in this case. Alternative
WP-l is not effective in the long term since the contaminants are
not addressed through treatment.
b. Site Soils and Sediments
Unlike the sludges, soils and tank contents, the site soils and
sediments do not contain organic contaminants at levels of concern.
Since the same treatment technology is being employed, alternatives
S-2 and S-3 are equally permanent.
Alternative S-3 provides the highest degree of long term site-
specific effectiveness since the inorganic contaminated soil would
be excavated, treated and disposed of at a TSD facility that
complies with EPA's Off-site policy. Alternative S-2 is virtually
as effective in the long term as Alternative S-3 because the
mobility of the inorganic contaminants would be effectively treated
through stabilization and capping. Since the same treatment
technology is being employed, Alternatives S-2 and S-3 are equally
permanent. Alternative S-l is not effective in the long term since
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the contaminants are not addressed through treatment.
c. Ground water
Alternative G-l assumes deed and site restrictions are enforced.
This alternative would require monitoring of contaminant
concentrations to ensure protectiveness. If concentrations
significantly rise, and/or there exists the likelihood of imminent
exposure, contingency measures would be implemented. Alternate
G-2, is expected to achieve protection of human health and the
environment in the short term since active remediation of
contaminants to ground water standards would be attempted.
Permanence of these alternatives would depend upon the success of
the pump and treat procedure in decontaminating the ground water
and natural processes in these aquifers which may be difficult due
to the contaminant constituents being sorbed to particles.
Considering the limited amount of ground water contamination
present, and assuming the source materials are adequately
addressed, the long-term effectiveness and permanence of these
alternatives is considered equivalent.
4. Reduction of Toxicity, Mobility or Volume Through Treatment
a. Sludges, Associated Soils and Tank Contents
Alternative WP-1, No Action/Institutional Controls does not provide
any treatment to reduce the toxicity, mobility, or volume of the
contaminated material. Likewise, Alternative WP-2 does not
substantively reduce the toxicity, mobility or volume of the
organic and inorganic contaminated soils, through effective
treatment, however, some reduction in mobility may be gained in
the stabilization of the inorganic-contaminated portion of the
soils and sludges. Although it could be argued that organic
mobility is also reduced, all that is expected to occur with the
attempted stabilization of highly concentrated organics is
dilution. Dilution is not considered to be appropriate treatment
and only serves to increase waste volume. This alternative does
reduce the toxicity of the tank liquids which would be treated off-
site. Alternatives WP-3 and WP-4 would significantly reduce the
toxicity, mobility and volume of contaminated material through the
destruction of the organics. Following treatment of the organic
material, the mobility of the resultant inorganics would be reduced
through stabilization.
b. Site Soils and Sediments
Since these soils and sediments are primarily contaminated by
barium, a metal incineration as in Alternatives WP-3 and WP-4 would
not be effective in reducing the toxicity, mobility of volume of
these wastes.
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Alternative S-l, no action/Institutional Controls does not provide
any treatment to reduce the toxicity, mobility, or volume of the
inorganic-contaminated site soils and sediments. Alternatives S-2
and S-3 do significantly reduce the mobility of these materials
through treatment. Since the inorganics are elements and cannot be
destroyed, none of the alternatives truly reduce toxicity, although
alternatives S-2 and S-3 do put them in a stabilized/solidified
matrix which effectively isolates them from the environment.
Alternatives S-2 and S-3 are also expected to increase volumes due
to the addition of stabilizing agents. This is not considered a
significant concern since this is a necessary step to ensure proper
treatment.
c. Ground water
Alternative G-l, no action/Institutional Controls does not provide
any treatment to reduce the toxicity, mobility, or volume of the
contaminated material. Alternative G-2 reduces the toxicity of the
contaminated ground water through treatment. G-l attempts to
achieve the same goals but through natural attenuation and
dilution.
5. Short-Term Effectiveness
a. Sludges/ Associated Soils and Tank Contents
The short-term risk associated with the WP-l, no action alternative
is the continuation of the risk currently posed by the site. There
would be potential short-term risks to site workers during the
excavation of soils, sludges and sediments in Alternatives WP-2
through WP-4. Based on the air emissions study done at the site,
the risk from air emissions during excavation is low. However,
engineering controls and monitoring would reduce the potential for
any adverse impacts during implementation of these remedies.
There is also a potential risk to workers and the community from
transportation of excavated material to an offsite facility in
Alternative WP-4 and transportation of tank liquids in WP-2.
Air emissions from the incinerator discussed in WP-3 will be
addressed by engineered controls and no adverse onsite or offsite
impacts are anticipated.
The estimated times of implementation of these remedies vary from
2 months for institutional controls to about 9 months for
Alternatives WP-2 and WP-4 to 24-26 months for Alternative WP-3.
Although the preferred alternative, WP-3, would take the most time,
it will shorten the amount of time to implement the Final Remedy.
Safety and environmental controls would keep any risk to minimal
levels.
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b. Site Soils and Sediments
The No Action alternative provided the least effective results in
the short term. The short-term risk associated with the No Action
alternative is the continuation of the risk currently posed by the
site. There would be potential short-term risks to site workers
during the excavation of soils and site sediments in Alternatives
S-2 and S-3. Based on the air emissions study done at the site,
the risk from air emissions during excavation is very low. However,
engineering controls and monitoring would reduce the potential for
any adverse impacts during implementation of these remedies. There
is also a potential risk to workers and the community from
transportation of excavated material to an offsite facility in
Alternative S-3. The No Action alternative would take the least
amount of time, however, it would not be protective of human health
and the environment in the short term. The other two alternatives
would be equally protective since they would both take about one
year to implement.
c. Ground water
The short-term risk associated with the No Action alternative is
the continuation of the risk currently posed by the site.
Alternative G-2 is not expected to pose any unacceptable risks
to workers of the community, although some risks will be posed by
possible exposure of site workers to the contaminated ground water
during pumping and treating operations.
6. Imp 1 emen t ab i 1 i ty
a. sludges, Associated soils and Tank Contents
All of the alternatives evaluated present no technical or
administrative difficulties. Alternatives WP-2 through WP-4
involve excavation and a significant amount of waste handling,
however, they can be quickly and effectively implemented with labor
and materials easily available within the region. Alternative WP-2
and WP-4 involve transportation of contaminated material, which is
also easy to implement. Alternative WP-3 involves additional site
clearing for the incinerator, which does not pose any further
problem in implementation.
b. Site Soils and Sediments
All of the alternatives are easily implementable. No unusual or
difficult to obtain materials or technologies are proposed.
Alternate S-3 involves transport of material offsite, but this
would not be difficult.
c. Ground water
Alternative G-2 would be easily implemented. Well installation is
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a common activity and the onsite treatment plant would be typical
of ones employed elsewhere.
7. Cost
a. sludges, Associated Soils and Tank Contents
The present worth cost of the preferred alternative for the
Sludges, Associated Soils and Tank Contents, Alternatives WP-3, is
$10,015,000. This alternative has the lowest costs of the
alternatives that are most effective and protective of human health
and the environment. No Action and On-site Capping (Alternatives
WP-1 and WP-2) have lower present worth costs of $564,000 and
$1,939,000 respectively but are not as effective. Alternative WP-
4, offsite incineration, is only slightly more protective of human
health and the environment than Alternative
WP-3 at a greatly increased cost of $26,534,000.
b. Site Soils and sediment
The present worth cost of the preferred alternative for the site
soils and sediments, stabilization and on-site disposal,
Alternative S-2, is $2,447,000. Alternative S-l, No Action is the
least expensive and least effective alternative at $564,000.
Alternative S-3, off-site disposal is considerably more expensive,
while not significantly more protective at $17,838,000.
c. Ground water
The present worth cost of the preferred alternative for the
contaminated site ground water is $564,000. The other alternative,
Alternative S-2, Ground water Extraction and Treatment would cost
$1,917,000. Since there are many factors at the GCV site that
could change the expected effectiveness of this alternative, such
as the complex hydrogeology and the interaction of the aquifer
materials with the organic and inorganic contaminants, there is a
possibility that the cost of this alternative will change during
the design phase of the project.
8. State Acceptance
Under the Superfund law, EPA is required to ensure that States have
a meaningful and continuing role in remedy selection and execution.
While States are not required to formally concur with EPA-selected
remedies, if Federally funded they must contribute 10 percent of
the remedy's construction costs and formally concur with the
deletion of sites from the National Priorities List upon completion
of the remediation process. For these reasons, EPA has attempted
to keep State staff informed regarding the progress of studies and
requested the views of the State of Louisiana regarding cleanup
options before selection of a remedy in the ROD. The commitment of
matching State funds is required before actual on-site construction
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activities begin. The expenditure of Superfund monies for actual
remedy construction cannot occur prior to such commitment of
matching State funds.
The Louisiana Department of Environmental Quality has reviewed the
Remedial Investigation/Feasibility Study and the Proposed Plan.
The State of Louisiana is in agreement with the selection of WP-3
to address the contaminated sludges, associated soils and tank
contents; Alternative S-2 to address the contaminated site soils
and sediments, and Alternative G-l to address the contaminated
ground water, as set forth in a letter dated September 30, 1992,
included in the Administrative Record.
9. community Acceptance
a. Sludges, Associated Soils and Tank Contents
EPA recognizes that the community in which a Superfund site is
located is the principal beneficiary of all remedial actions
undertaken. EPA also recognizes that it is its responsibility to
inform interested citizens of the nature of Superfund environmental
problems and solutions, and to learn from the community what its
desires are regarding these sites.
EPA solicited input from the public on the remedial alternatives
proposed to address the sludge, associated soil and tank contents
at the site. The comments from the residents indicated that the
community is in support of the ultimate destruction of these
materials through incineration, but is concerned that incineration
on-site may pose risks to the community. EPA feels that their
concerns can be addressed through strict engineering controls and
has included this discussion in the responsiveness summary.
b. site Soils and Sediments
In general, the residential community is not opposed to
stabilization of these materials, however, they would prefer
offsite disposal. Specific comments are addressed in the
responsiveness summary.
c. Ground water
In general, the public favored the selected alternative, however,
they did have some concern about contingency measures if this
alternative did not prove to be effective. EPA has included
contingency provisions in this ROD and has addressed these concerns
in the responsiveness summary.
X. THE SELECTED REMEDY
The preferred alternative for addressing the contaminated
sludges,associated soils and tank contents contaminated with
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organics and metals at the Gulf Coast Vacuum site is Alternative
WP-3, Excavation, Onsite Incineration, Residue
Stabilization/Solidification, Onsite Disposal and a Clay Cover over
the stabilized material. The preferred alternative for addressing
the site soils and sediments contaminated with barium, is
Alternative S-2, Excavation, Stabilization, On-Site Disposal, and
a Clay Cover.
The preferred alternative for addressing the limited ground water
contamination at GCV is Alternative G-l Institutional Controls. In
recommending these alternatives, all of the alternatives developed
were evaluated using the nine criteria outlined in the Superfund
regulations. The following discussion presents the results of this
evaluation.
XI. THE STATUTORY DETERMINATIONS
EPA's primary responsibility at Superfund sites is to select
remedial actions that are protective of human health and the
environment. Section 121 of CERCLA also requires that the selected
remedial action for the site comply with applicable or relevant and
appropriate environmental standards established under Federal and
State environmental laws, unless a waiver is granted. The selected
remedy must be cost-effective and utilize treatment or resource
recovery technologies to the maximum extent practicable. The
statute also contains a preference for remedies that include
treatment as a principal element. The following sections discuss
how the selected remedies for contaminated sludges, associated
soils, tank contents, soils and sediments and contaminated ground
water at the Gulf Coast site meet the statutory requirements.
A. Protection of Human Health and the Environment
In order to protect human health and the environment, the
contaminated sludges, associated soils and tank contents and site
soils and sediments that exceed remedial action goals will undergo
a combination of excavation, treatment and containment. These
media will be treated and contained to meet the performance
standards set forth in this ROD. These performance standards will
assure that site risks fall within the target cancer risk range of
10"* to 10"6 and the non-carcinogenic hazard index will be reduced
to less than one (1). The performance standards will also assure
that direct contact risks associated with the contaminated sludges,
associated soils and tank contents and site soils and sediments
will be mitigated and that this material cease to act as a source
of ground water contamination.
The selection of the ground water remedy is protective of human
health since at this time the risk from ground water contamination
appears to be low and the source of aquifer contamination will be
eliminated by implementation of soil and sludge alternatives.
Contamination is expected to dissipate due to natural attenuation
in the aquifer. The aquifer will be monitored and if it is found
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that contaminant levels are not decreasing, and/or an imminent risk
of potential ingestion occurs, contingency measures will be
implemented.
The selected remedies protect human health and the environment by
reducing levels of contaminants through treatment and containment.
Of all the alternatives evaluated for the contaminated sludges,
soils, tanks, sediments, surface soils and contaminated ground
water, the selected alternatives provide the best overall
protection to human health and the environment. No unacceptable
short-term risks will be caused by implementing these remedies.
B. Compliance With ARARs
The portion of the selected remedy which addresses the sludges,
associated soils, buried pits, tank contents, since site soils and
sediments will meet all applicable or relevant and appropriate
requirements. The ARARs are presented as follows:
Chemical-Specific ARARs for Sludges. Tank Contents. Soils and
Sediments
1. Identification and Listing of Hazardous Waste (40 CFR Part
261), Subpart C - Characteristics of Hazardous Waste and Subpart D
- Listing of Hazardous Waste. Applicable because hazardous waste
will be managed.
2. Land Disposal Restrictions (40 CFR Part 268), Subpart A (268.4)
Subpart D - Treatment Standards. Applicable because LDR hazardous
waste in the West Pit and Washout Pit (benzene-characteristic)
hazardous waste will be treated and land disposed.
3. National Emission standards for Hazardous Air pollutants (40
CFR Part 61) (NESHAPS). Relevant and appropriate during excavation
stabilization and incineration processes.
Action-Specific ARARs for Sludges. Associated Soils Tank Contents.
Site Soils and Sediments
1. Standards for Owners and Operators of Hazardous Waste
Treatment, Storage, and Disposal Facilities (40 CFR Part 264).
Relevant and appropriate during storage, stabilization, and
incineration processes. In particular, Subparts B, C, D, G, I,
J, K, L, N, 0 may be relevant and appropriate during waste
treatment and related operations and long term monitoring.
2. OSHA 1910.120 Occupational Safety and Health Regulations
Applicable because site workers may be exposed to
hazardous waste.
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The Ground water ARARs are as follows:
Chemical-Specific ARARs for Ground Water
None for the institutional control option, however, if
contingency measures are implemented chemical-specific
ARARs may apply. These will be evaluated before contingency
selection.
Action-Specific ARARs for Ground Water
1. Standards for owners and Operators of Hazardous Waste
Treatment, Storage and Disposal Facilities Ground water Monitoring
(40 CFR 264.117(a)(1). Applicable post-closure and monitoring
requirements for 30 years or another period determined by the
Regional Administrator.
C. Cost-Effectiveness
EPA believes that the selected remedies are cost-effective in
mitigating the threat of direct contact and for reducing the
potential for ground water contamination from the site wastes and
for controlling the threat from the contaminated ground water.
Section 300.430 (f) (ii) (D) of the NCP requires EPA to determine
cost-effectiveness by evaluating the following three of the five
balancing criteria to determine overall effectiveness: long-term
effectiveness and permanence, reduction of toxicity, mobility or
volume through treatment, and short-term effectiveness. Overall
effectiveness is then compared to cost to ensure that the remedy is
cost effective. EPA believes the selected remedies meet these
criteria.
The estimated present worth cost for the selected remedy for the
sludge, associated soil and tank contents is $9,907,000. This
alternative costs 5 times more than the stabilization alternative,
yet the selected alternative is significantly more effective and
protective of human health and the environment due to the
significant reduction in volume, toxicity and mobility of the
organics achieved through incineration and stabilization for
inorganics. The selected alternative eliminates the hazards posed
by the organic constituents and greatly reduces those posed by the
inorganic contaminants at 34% of the cost of the alternative
involving off-site incineration.
The estimated present worth cost of the selected remedy for the
site soils and sediments is $2,477,000. This alternative
effectively stabilizes the inorganic constituents in these media
for 14% of the costs associated with the off-site disposal
alternative.
The estimated present worth cost for the ground water is $564,000.
Due to the low hazard associated with the ground water (due to its
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limited extent) and the removal of the source of the contamination
in the other remedies, the institutional control alternative was
chosen. It is protective of human health and the environment and
will cost 71% less than the punp and treat alternative. If
continued significant contamination is found, contingency measures
will be implemented.
The total estimated cost for this final action is $13,026,000.
D. Utilization of Permanent Solutions and Treatment or Resource
Recovery Technologies to the Maximum Extent Practicable
EPA believes the selected remedies represent the maximum extent to
which permanent solutions and treatment/resource recovery
technologies can be utilized in a cost-effective manner for the GCV
site.
Of those alternatives that are protective of human health and the
environment and comply with ARARs, EPA has determined that the
selected remedies provide the best balance of trade offs in terms
of long-term effectiveness and permanence, reduction in toxicity,
mobility, or volume achieved through treatment, short-term
effectiveness, implementability, costs, and taking into
consideration State and community concerns.
The selected remedy meets the statutory preference for treatment as
a principal element.
The selected ground water remedy satisfies the long-term
effectiveness and permanence criterion by preventing ingestion by
potential receptors and promoting restoration of ground water
quality. It is, however, less effective than the pump and treat
alternative with respect to meeting reduction in toxicity, mobility
and volume criteria. Again, the cost associated with implementing
the selected ground water remedy is less than the cost associated
with implementing the more aggressive extraction and discharge
alternatives. However, site specific data currently does not
indicate that active remediation is warranted. The limited nature
of contaminant detection combined with the fact that the sources of
contamination will be eliminated, suggest that under current
conditions, ground water pumping to remove contaminated ground
water may not be technically justifiable.
E. Preference for Treatment as a Principal Element:
The statutory preference for remedies that employ treatment as a
principal element will be satisfied through implementation of the
incineration of the contaminated pit sludges, associated soils and
tank contents and through the effective stabilization of the
inorganic-contaminated soils. The selected remedy complies with
the statutory requirement to utilize permanent solutions and
treatment technologies to the maximum extent practicable.
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XII. DOCUMENTATION OF SIGNIFICANT CHANGES:
The proposed plan for the GCV site was released for public comment
in July 1992. The proposed plan identified Alternative WP-3,
Excavation, On-site Incineration, Residue Stabilization/
Solidification, On-site disposal of Ash, Clay Cover, as the
preferred alternative to address the pit sludges, associated soils
and tank contents. The proposed plan identified Alternative S-2,
Excavation, Stabilization, On-site Disposal and Clay Cover, as the
preferred alternative to address the site soils and sediments. The
proposed plan identified Institutional Controls, Alternative G-l,
as the preferred alternative to address the ground water. EPA
reviewed all written and verbal comments submitted during the
public comment period. Upon review of these' comments, it was
determined that no significant changes to the remedy, as originally
identified in the Proposed Plan, were necessary.
Two minor differences between the ROD and the proposed plan are the
revision of costs (detailed in the Description of Alternatives
Section) and the deletion of the clay cover from the alternatives
involving pit excavation. The ROD costs are within +50% to -30% of
the costs in the proposed plan. Clay covers will not be placed on
the excavated Washout Pit, West Pit, Former West Pit or buried
pits since these areas will be cleaned up to clean-up levels.
These differences did not affect selection of the final
alternative.
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