United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R06-92/075
September 1992
PB93-964206
SEPA Superfund
Record of Decision:
Gulf Coast Vacuum Services
(Operable Unit 2), 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 appicabie information to
the content of the document All supplemental material is, however, contained in the administrative record
for this site.
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50272-101
REPORT DOCUMENTATION
PAGE
* ^^^^^^^•^^••MM
41. Title and S
SUPER!
Gulf C
First
7. Author(«)
1. REPORT NO.
EPA/ROD/R06-92/075
3. Recipient1* Accession No.
4. Title and Subtitle
SUPERFUND RECORD OF DECISION
Gulf Coast Vacuum Services (Operable Unit 2),
First Remedial Action - Interim
LA
5. Report Date
09/30/92
s.
8. Performing Organization Rept No.
9. Performing Organization Name and Address
10. Project/Task/Work Unit No.
11. Contract(C) or Grant(G) No.
(C)
(G)
12. Sponsoring Organization Name and Address
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report & Period Covered
800/000
14.
15. Supplementary Notes
PB93-964206
16. Abstract (Limit 200 words)
The 12.8-acre Gulf Coast Vacuum Services site is a former vacuum truck and oil field
drilling mud plant in Vermilion Parish, Louisiana. Land use in the surrounding area is
predominantly agricultural, and the site is situated in the low-lying flatland of the
Atlantic Gulf Coastal Plain. Ten residences, located within a half mile, use the
ground water below the site, the Chicot Aquifer, for drinking water as well as
irrigation. The site is bounded to the ease and south by the D.L. Mud Superfund site,
which is being evaluated separately. From 1969 to 1984, several owners used the site
as a trucking terminal for transporting various materials, primarily waste generated
from oil exploration and production. The site contains two open waste pits,
specifically, the Washout Pit and the West Pit, as well as two areas covered with
vegetation, known as the Former West Pit. The Former West Pit, located south of the
West Pit, was used for disposal. Additionally, there are four vertical storage tanks,
horizontal tanks, and three underground storage tanks. Unpermitted disposal of
contaminated materials, primarily oil industry-related waste, occurred in the unlined
pits, ditches, and soil at the site. In 1980, a citizen's complaint through the
Vermilion Association for Protection of the Environment prompted several site
(See Attached Page)
17. Document Analysis a. Descriptors
Record of Decision - Gulf Coast Vacuum Services (Operable Unit 2), LA
First Remedial Action - Interim
Contaminated Media: soil, sludge, sw
Key Contaminants: VOCs (benzene, PCE, TCE, toluene, xylenes), other organics
(dioxins, PAHs, PCBs, pesticides, phenols), metals (arsenic,
chromium, lead)
b. Identifiers/Open-Ended Terms
c. COSAT1 RekVGroup
18. Availability Statement
19. Security Class (This Report)
None
20, Security Class (This Page)
None
21. No. of Pages
76
22. Price
(SeeANSI-Z39.18)
See Inttructiont on Rmorte
OPTIONAL FORM 272 (4-77)
(Formerly NTtS-35)
Department of Commerce
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EPA/ROD/R06-92/075
Gulf Coast Vacuum Services (Operable Unit 2) , LA
First Remedial Action - Interim
stract (Continued)
investigations by EPA. EPA has conducted three removal actions at the site, addressing
contaminated overflow from the Washout and West pits in 1990, overflow from the West pit
into a previously constructed secondary containment area in 1991, and critical rainwater
accumulation in the Washout Pit and the West Pit in 1992. All three removals involved
pumping, treating, and discharging the wastewaters to prevent offsite migration and human
exposure. This ROD provides an interim remedy for OU2, the rainfall accumulation,
contaminated overflow, and offsite migration from the Washout and West Pits. The primary
contaminants of concern affecting the soil, sludge, and surface water (rainwater) are
VOCs, including benzene, PCE, TCE, toluene, and xylenes; other organics, including
dioxins, PAHs, PCBs, pesticides, and phenols; and metals, including arsenic, chromium,
and lead.
The selected remedial action for this site includes excavating 2,700 cubic yards of
contaminated sludge and 550 cubic yards of associated soil from the Washout Pit to 2 feet
below where contaminant levels exceed the remedial action goals, and consolidating these
materials into the West Pit to achieve positive drainage; backfilling the excavated areas
with clean soil, and covering the West Pit with an impermeable synthetic membrane cover;
pumping and onsite treatment of 1,700,000 gallons of contaminated rainwater, with onsite
discharge; abandoning three onsite water supply wells; and monitoring air during the
excavation. The estimated present worth cost for this remedial action is $525,200, which
includes an annual O&M cost of $5,000.
PERFORMANCE STANDARDS OR GOALS; Chemical-specific remedial action goals were developed
or the accumulated rainwater based on state effluent pollution concentration limits, and
'for the soil and sludge based on health-risk values. Soil and sludge excavation levels
include arsenic 16 ug/kg; barium 5,400 mg/kg; benzene 0.66 mg/kg; and carcinogenic PAHs
3 mg/kg.
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RECORD OF DECISION
GULF COAST VACUUM SERVICES
VERMILION PARISH, LOUISIANA
INTERIM SOURCE ACTION
OPERABLE UNIT 2
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
SEPTEMBER 1992
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RECORD OF DECISION
CONCURRENCE DOCUMENTATION
FOR THE
GULF COAST VACUUM SERVICES SUPERFUND SITE
INTERIM ACTION OPERABLE UNIT 2
Kathleen Lbhry
Site Remedial Project Manager
Nelly
Office of Regional Counsel
Site Attorney
Stephen Gilrein, Chief
ALNM Section 6H-SA
Carl E^dlund, Chief
Superfund Program*. Branch 6H-S
>x- Barbara Greenfield
Associate Regional counsel
Waste Branch, 6C-W
George Alexander, Jr. ^r
Office of r
Regional Counsel 6C
/ Allyn M. Davis
Hazardous Waste Management
Division 6H
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DECLARATION
GULF COAST VACUUM SERVICES
RECORD OF DECISION
INTERIM SOURCE ACTION, OU2
SEPTEMBER 1992
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. 2, Interim 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
(ROD) for Operable Unit No. 2, Interim Source Action, provides for
a limited action to control rainfall accumulation, contaminated
overflow, and off-site migration from the two on-site, open pits;
the Washout Pit and the West Pit. The interim action will be
implemented prior to the Final Source Action described in a
separate Record of Decision. The ROD for Operable Unit No. 1,
Final Source Action, addresses the long-term remedial action for
all of the sources of contamination at the site. The areas
addressed in the Final Source Action include the pit sludges and
associated soils, buried pits, tank contents, site soils, sediments
and the ground water.
The interim remedy will address the short term risk due to overflow
of contaminated water from the two open site pits. It will also
minimize the potential for human exposure and direct contact with
the contaminants in the overflow. The remedy is designed to
address these areas until the Final Source Action is implemented.
The accumulated rainwater will be treated to below established
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discharge standards set by the Louisiana Department of
Environmental Quality.
The Interim Action will be accomplished by eliminating the threat
of overflow from the Washout Pit, clean closing it and
consolidating this material into the West Pit. The West Pit will
then be covered with a synthetic impermeable membrane. Soil/sludge
from the Washout pit will be excavated to below the final remedial
objectives which are 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. (If during the course of the Interim Action
additional soils are needed to provide material stability within
the West Pit prior to cover placement, one or both buried
contaminated waste pits will be excavated for this purpose).
Added benefits of this interim action are that an "attractive
nuisance" from the ponding of rainwater will be removed, the
potential for ground water contamination will be reduced since the
driving force, the hydraulic head, will be removed, and EPA will be
able to more accurately estimate the volume of soil to be treated
in the Final Source Action. The buried material in the Washout Pit
represents an unknown quantity of material to be excavated and
subsequently treated in the Final Source Action. Knowledge of the
volume of this material will enable EPA to accurately prepare the
design for the implementation of the Final Source Remedial Action.
The major components of the selected remedy include:
- On-site pumping, treatment of the accumulated rainwater
in the Washout Pit and West Pit;
- Segregation of the paraffin layer in the West Pit;
- Excavation of the sludge/soil from the Washout Pit and
consolidation into the West Pit;
- Placement of an impermeable synthetic membrane over the
consolidated material in the West Pit;
- Backfilling of the Washout Pit with clean soil.
The estimated total cost of this remedy (present worth) is
$525,200.
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STATUTORY DETERMINATIONS
This interim action is protective of human health and the
environment, complies with Federal and State applicable or relevant
and appropriate requirements for this limited-scope action to the
extent practicable and is cost-effective. Because this action does
not constitute the final remedy for the site, the statutory
preference for remedies that employ treatment that reduces
toxicity, mobility, or volume as a principal element is not
necessary; although waste mobility will be reduced on a temporary
basis. Threats posed by the conditions at this site will be fully
addressed by the Final Response Action. This interim action is
protective of human health and the environment and it is fully
consistent with the Final Source Action, Operable Unit No. 1.
B "J. Wynne 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 - 9
B. Area Soils 9
C. Regional Hydrogeology 9
D. Site Hydrogeology 12
E. Exploratory Drilling and Water 14
Level Observation
F. Nature and Extent of Contamination 15
VI. Summary of Site Risks 17
A. Risk Assessment Description 17
B. Human Health Risks 18
C. Identification of Chemical of Concern 19
D. Exposure Assessment 19
1. Current Land Use and Exposure Pathways 19
2. Future Land Use and Onsite Conditions 23
E. Toxicity Assessment 25
F. Human Health Risk Characterization 28
1. Current Risk Characterization 33
2. Future Risk Characterization 33
3. Risks from Dioxins 33
4. Evaluation of Lead 34
G. Uncertainties Associated with Human Health 34
Risk Calculations
H. Central Tendencies 34
I. Ecological Risks 43
VII. Remedial Action Goals 45
VIII. Description of Alternatives 45
IX. Summary of Comparative Analysis of Alternatives 57
A. Threshold Criteria 57
B. Balancing Criteria 58
C. Modifying Criteria 58
D. Comparative Analysis 59
X. The Statutory Determinations 63
A. Protection of Human Health and 63
the Environment
B. Compliance with ARARs 64
C. Cost-Effectiveness 64
D. Utilization of Permanent Solutions and 65
Treatment or Resource Recovery Technologies
to the Maximum Extent Practicable
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E. Preference for Treatment as a Principal 65
Element
F. Compliance with Long-Term Remedial Actions 65
XI. Documentation of Significant Changes 66
Appendix I Responsiveness Summary
Appendix II Revised Cost Estimates
Appendix III Risk Assessment Background
Appendix IV Administrative Record Index
Louisiana Concurrence Letter
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I. LOCATION AND DESCRIPTION
The Gulf Coast Vacuum Site (GCV) 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 1). The site occupies 12.8 acres in an agricultural
area.
The site is situated in the low-lying flatland 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 Super fund
site and the LeBoeuf Canal (Figure 2).
The most outstanding physical features of the site are the 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 with vegetative cover.
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 is bermed
so it does not drain into the river. 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 another Superfund site, the D.L. Mud 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 is drinking water
purposes, as well as irrigation. A study of the residential wells
in the site vicinity indicate 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.
A survey of the well construction records indicate that residential
wells depths typically range from 80 to 230 feet below ground
surface.
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES
The Gulf Coast Vacuum site, also known as the Galveston Houston
Yard and the LeBoeuf Yard, was part of a 25.562 acre parcel owned
and operated by Lafayette Highway Equipment Sales and Services,
Inc. from September 1969 until May 1975 when the parcel was sold to
Gulf Coast Pre-Mix Mud Services, Inc.
Gulf Coast Pre-Mix Service, Inc. owned and operated the site until
January 1979 when it merged with Gulf Coast Pre-Mix Trucking, Inc.,
resulting in G.H. Drilling Fluid, Inc. G.H. Drilling Fluids, Inc.
was renamed G.H. Fluid Services, Inc. in August 1979 and the site
was owned and operated by G.H. Fluid Services, Inc. until October
1980 when it conveyed 12.780 acres (the Gulf Coast Vacuum site) of
its 25.562 acre parcel to Gulf Coast Vacuum Services, which
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operated the site until 1984, when it declared bankruptcy in 1984.
The remaining parcel, is now known as the D.L. Mud Superfund site.
Gulf Coast Vacuum Services, Inc. and its predecessors were using
the property 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.
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 was 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 and was finalized on the NPL in March 1989,
pursuant to Section 105 of the Comprehensive Environmental
Response, Compensation, and Liability Act, as amended, (CERCLA) , 42
U.S.C. 9605, qualifying the site for investigation and remediation
under CERCLA.
In 1988, EPA identified over 400 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 the 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
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levee.
On February 8, 1991, an Action Memorandum for a second Removal
Action, which was 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 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
representatives of the 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. Due to time constraints rising
from the emergency situation, on March 30, 1992, twenty-eight (28)
representatives of the 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 interim 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.
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A series of community interviews were conducted in May of 1990.
During the community interviews, EPA representatives had face-to-
face meetings with citizens and gained information about the site
history and past practices. Fact Sheets on the site's progress
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
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.
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 and
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. 2, Interim Source Action, which provides for a
limited action to address rainfall accumulation and resulting
contaminated overflow and off-site migration from the open pits on-
site. The areas addressed' include contaminated rainwater in the
Washout Pit and the West Pit. The interim action will be
implemented prior to the Final Source Action.
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A separate ROD was developed for Operable Unit No. 1, Final Source
Action, which addresses the long-term remedial action for all of
the sources of contamination at the site. The areas addressed in
the Final Source Action include the pit sludges and associated
soils, buried pits, tank contents, site soils and sediments and
ground water.
Source material is defined as material that includes or contains
hazardous substances, pollutants or contaminants that acts as
reservoir for migration of contamination to the 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 that generally cannot be reliably
contained or would 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 compounds.
The accumulated rainwater that is in contact with the contaminated
pit sludges (contaminated with organic and inorganic constituents)
is identified as a principal threat material, due to the nature of
this waste. This material is considered to be both highly mobile
and toxic.
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 rainwater
accumulation on the pits, 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.
8
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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, Patoutville Silt Loam (0-1%
slopes), and the Patoutville 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
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 groundwater 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
groundwater 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, generally 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.
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-------
1 I
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n
, 2
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j s
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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 pumpage 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 groundwater
users was also obtained through interviews with residents in the
immediate site vicinity. The survey of the well construction
records indicate 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 groundwater pumpage.
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
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 groundwater monitoring wells were drilled and installed,
and 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). Groundwater level
observations from eight monitoring wells (designated D-l through
D-8) on the D.L. Mud Superfund site located to the east and south
of the site, were also incorporated into this investigation.
12
-------
SI
' S3
a i!
•Aot*'i*"i»>*t«t*.ooae»heeove*octQQOtr»o
ssSgisfilrtartfcHSBsaSSiiJiRssidssclssiiss
tiSje-f
Z6<*1
-------
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
groundwater 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 ft. below ground surface. Thin, sandy silt lenses
saturated with water were noted interbedded with the clay during
the drilling and installation of monitoring wells G-8A, G-11P, and
G-llS. 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 ft MSL which is
approximately eight ft higher than the nearby deeper wells. This
unit was observed only in the West Pasture and northeast corner of
the site. At monitoring well G-18 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
underlying the site, and most likely corresponds to the "water
table" layer of the Chicot Aquifer System. Thirteen monitoring
wells are completed in this unit with their screen intervals
intersecting the groundwater 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 groundwater flow and
hydraulic gradients within that unit. Groundwater 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 being more or less 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
14
-------
Aquifer System. Discontinuous olive gray clay lenses partially
separate this lower unit from the Upper Aquifer Unit. 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, a gradient of 0.0001 ft/ft
is calculated by triangulation, 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
groundwater 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 groundwater (and contaminants) exists.
See Figure 7 for groundwater impacts.
F. Nature and Extent of Contamination - Accumulated Rainwater and
Pit Sludges
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.
15
-------
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-------
Pit sludges and soil samples were found to contain a number of
volatile and semivolatile compounds. 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. The inorganic
contaminants of concern included 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.
Various surface water samples were taken of the accumulated
rainwater in the West Pit and the Washout Pits between 1980 and
1991. Sample results indicated that the many of the organic and
inorganic contaminants found in the pits were also present in the
accumulated rainwater on the tops of the pits.
The estimated size of the pits, volumes of contaminated pit
material, and volume of accumulated rainwater are:
o West Pit - Size - 28,000 square feet
- Sludge Volume - 5,000 cubic yards
- Accumulated Rainwater - 1,300,000 gallons
o Washout Pit - Size - 12,000 square feet
- Sludge Volume - 2,700 cubic yards
- Accumulated Rainwater - 400,000 gallons
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, groundwater and surface water at
the Gulf Coast Vacuum Super fund site near Abbeville, Louisiana. 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
17
-------
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
of concern range of 1 X 10"* to 1 X 1CT6 for hazardous waste site
remediation. The NCP 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.
18
-------
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. For the purposes of this interim action, only data from
soil, sludge and surface water sampling of the Washout Pit and the
West Pit is of concern. Any chemical detected in any sample from
these areas was 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 jonly 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 another Superfund site, 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 Chicot Aquifer
does not have an official classification, the groundwater 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.
Under current site conditions, there are no people who live or work
onsite. Therefore, a trespasser scenario was selected as
representative of the population most likely to be exposed on the
site under current conditions. The trespasser was assumed to be an
area resident who began exposure at age seven and continued until
19
-------
SUMMARY OF CHEMICALS DETECTED ON-SITE AT GULF COAST
Chemical Name
Surface Subsurface Surface
e-j i - - -
Volatiles:
Acetone
Benzene
Butanone , 2-
Carbon disulfide
Chlorobenzene
Chloroform
Chloromethane
Dichlorosthane , 1,1-
EthyUbenzene
Methylene chloride
Tetrachloroethene
Toluene
Trichloroethene
Vinyl acetate
Xylene (total)
Semi -Volatiles:
Benzole acid
Oibenzofuran
Dichlorobenzene , 1,4-
Dinitrotoluene , 2,4-
N-Ni trosodipheny lamina
Fentachlorophenol
Phenol
Acenapbthene
Anthracene
Benzo(a) anthracene
Benzo(a)pyrene
Benzo (b ) fluor anthene
Benzo(8,h, Dperylene
Benzo (k ) fluor anthene
Chrysene
Fluoranthene
Fluorene
Methy Inaphthalene , 2-
Maphthalene
Fhenanthrene
Pyrene
Bi* (2-«thylhexyl Jphthalate
Butylbenzylphthalate
Di -n-butylphthalate
Di -n-octylphthalate
Piethylphthalate
Ciocthylphthalate
Pesticidei/PCBs:
A1 Jw J •>
Axarin
•Ipha-Chlordane
Arocblor-1248
beti-BBC
ODD, 4,4-
ftfti* t, f.
PDTj 4,**-
delta-EHC
Di eldrin
Endosulfan I
Endosulfan II
»OIJL son. Sediment Sludxe Watt
13/45
1/45
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
0/34
0/34
1/34
0/34
0/34
0/34
0/34
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
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 1/18
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
2/5
1/5
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
6/211
3/211
4/211
2/211
3/211
3/211
11/211
6/211
22/211
45/212
36/212
45/211
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 Kane
?tsticidea/FCB« - continued
Endoiulfan aulfate
Endcln
8amna-Chlordane
lannt-BHC
Heptaehlor
flaptaehlor apoxide
Inorganic*:
Aluninum
Antlneny
Arienic
Barium
Beryllium
Cadmium
Calcium
Chloride
Chromium
Cobalt
Coppar
Cymid*
Iron
Lead
Ha»n«»iUffl
Maticaaaae
Mercury
Siekei
Fota»*ium
Selenium
SUrer
Sodium
Thallium
Vanadium
Zinc
Dloxins/Furtnt
Surface Subsuxface Surlac*
Soil Soil Seditaetit Sludge Hater Breundwater Tet«l
0/34
0/34
0/3*
0/34
0/14
0/3n
43/45
1/1*
44/iS
4£/i>5
40/45
2i/«5
45/45
41/~-
45/43 -•
43/45
43/45
11/37
4S/«5
41/<1
45/45
43/45
29/45
43/4$
41/45
18/45
10/45
40/43
10/4!
45/43
43/43
1/77
0/77
0/77
0/77
0/77
0/77
117/117
0/30
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
Ill/Ill
24/117
114/117
114/117
25/113
12/117
105/117
24/117
117/117
115/115
0/4
0/4
0/4
0/4
0/4
0/4
4/4
0/4
4/4
4/4
2/4
8/4
4/4
2/4
4/4
3/4
4/4
0/4
4/4
4/4
4/4
4/4
3/4
4/4
4/4
O/*
0/4
1/4
0/4
4/4
4/4
0/19
0/16
0/19
1/19
0/19
0/19
20/20
0/9
20/20
20/20
9/20
19/20
20/20
18/20
20/20
17/20
20/20
0/11
20/20
20/20
20/20
17/17
19/20
20/20
13/20
7/20
16/20
18/20
3/20
20/20
20/20
0/5
0/5
0/5
0/5
0/5
0/3
4/4
0/4
0/6
4/4
0/4
0/4
*/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
S/21
10/21
21/21
21/21
12/21
1V21
14/21
0/9
21/21
13/21
21/21
21/21
«/21
11/21
20/21
0/21
0/15
21/21
1/21
15/21
It/21
1/1*0
1/157
3/1*0
2/160
1/1(0
2/160
201/211
5/102
l»e/221
211/211
1O/211
86/211
211/211
183/208
ZOO/211
U4/211
197/211
17/1*4
210/211
1*4/200
211/211
202/202
•1/211
1*4/211
196/211
50/204
38/203
1M/X11
40/210
201/211
202/207
11/11
8/4
6/6
9/9
0/0
0/1
29/31
FIGURE 8 (cont.)'
-------
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-Nitrosodiphenylamine
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)fluoranthene
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
-------
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.
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 uses with possible onsite
residence of farmers was considered the most likely, since the
surrounding land is primarily used for pasture land and for
residences. Therefore, the resident-farmer scenario was selected
as the most representative of the population most 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 done was 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 reasonable, 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
23
-------
exposed to soil contamination via the ingestion of meat and
milk from animals raised in contaminated areas. Therefore,
considering the future agricultural land use of the site, this
pathway was also evaluated.
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
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. In addition, future
onsite exposure to residents, through both oral ingestion and
dermal contact, is also a reasonable exposure pathway and was
24
-------
evaluated as part of the risk assessment.
A summary of the exposure pathways used for quantitative evaluation
are summarized in 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
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, subchfonic, 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 (both cancer and noncancer), 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 epidemiclogical
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
25
-------
SUMMARY OF EXPOSURE SCENARIOS SELECTED FOR QUANTIFICATION
Exposed
Land Use Population
Current Trespasserc
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(b>
(Pit Area,
Northeast
Area)
On-site(c)
(Pit Area)
Exposure Media
Soil
Sludge
Sediment
Surface Water
Groundwater
Soil
Groundwater
Garden Vegetables
Beef
Hi Ik
Sludge
Garden Vegetables
Beef
Milk
Exposure Scutes.
Oral/Dermal
Oral/Dental
Oral/Dermal
Dermal
Oral/Derma]
Oral/Dermal
Oral/Dermal/"
Oral
Oral
Oral
Oral/Deriral
Oral
Oral
Oral
:-.al (VOCs)
(a) Scenarios in which a trespasser is exposed at various sources on-si:-:: msy also
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.
FIGURE 10
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risk assessment (current trespassers, current off-site residents,
and future on-site residents) and for three age groups (children
ages 1-13 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.)
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:
28
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SUMMARY OF HIF CALCULATIONS
Exposed Population
Current Trespasser
Current Off-site
Resident
Exposure Medium
Soil
Sludge
Sediment
Surface Water
Groundwater
Exposure
Route
Oral
Dermal
Oral
Dermal
Oral
Dermal
Oral
Dermal
Oral
Dermal
HIFc
6.4E-02
9.2E-02
3.8E-07
1.9E-05
3.8E-07
3.8E-05
3.8E-07
1.9E-05
2.7E-02
5.5E-02
HI Ft
5.5E-08
2.7E-06
5.5E-08
5.5E-08
5.5E-08
2.7E-06
5.0E-02 7.1E-03
1.2E-02
2.3E-02
Future On-site
Resident
Groundwater
Soil or Sludge
Garden Vegetables
Beef
Milk
Oral
Inhalation
Dermal
Oral
Dermal
Oral
Oral
Oral
6.4E-02
1.2E+00
9.2E-02
1.3E-05
1.2E-04
2.6E-03
2.3E-03
2.6E-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
.2E-02
.8E-02
.3E-02
.6E-06
,9E-05
4.8E-04
4.4E-04
1.8E-03
FIGURE 12 (Cent.)
-------
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 IK*). An excess lifetime
cancer risk of 1 x 10"* 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
involving exposure to the pit sludges, the Northwest site fields,
32
-------
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 1x10"*. 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^ to 9X10"4 which is greater than EPA's risk range of concern
of 1x10"* to IxlO"6. This risk is driven by the possible ingest ion
of arsenic in the groundwater. 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
groundwater. 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 1x10^
to IxlO'6. Arsenic exposure through groundwater 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"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.
Hypothetical 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.
3. Risk from Dioxins: The risk investigation shows the
dioxin/furan analyses to be less than 1 ppm 2,3,7,8-
tetachlorodibenzodioxin (TCDD) equivalents in sludges, surface
33
-------
soils and sediment. It has been determined by EPA and the Agency
for Toxic Substances and Disease Registry (ATSDR) that levels
between l 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 to clean-up standards
and treated through incineration as part of the Final Source
Action. 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 site being regraded (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.
The uncertainty and the potential bias in the risk estimates are
summarized in 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
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
34
-------
SUMMARY OF RISKS TO HYPOTHETICAL FUTURE RESIDENTS(a)
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
174 ppm
8.6
580 ppm
1.8 Mg/L
Mean
PbB
Cug/dL)
1.9
3.3
6.3
% 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
-------
CENTRAL TENDENCY VS REASONABLE MAXIMUM EXPOSURE ASSUMPTIONS
Average or
Central Tendency
Contact Rates fCR)
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. in/day
Adults 20 cu.in/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)
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
Total Surface Area (SA)
Children 7,200 cm2/event
Adults 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 (CR)
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 (Cont.)
-------
Soil Ingestion Rates
Children (1-6 yrs)
Adults
Workers
Fish Ingestion Rates
Adults
200 mg/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
US EPA,
1989a;
US EPA
1989b
Adults
20,000 cm2/event
Body Weights (BW)
Children (1-6 yrs) 16 kg
Adult 70 kg
Workers
70 kg
US EPA, 1992b
US EPA, 1989b
US EPA, 1989b; US
EPA, 1991
US EPA, 1991
Figure 15 (Cont.)
-------
Exposure Duration (ED)
Residential 9 years
Industrial 9 years
US EPA, 1989b
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
Contact Rates (CR)
Water Ingestion Rates
Children (1-6 yrs) 1 L/day
Adults 2 L/day
US EPA, 1992a
US EPA, 1989a
Workers
Soil Ingestion Rates
Children (1-6 yrs)
1 L/day
US EPA, 1989b;
US EPA,
1991
US EPA, 1991
200 mg/day
Average value,
US EPA,
1989C
Figure 15 (Cent.)
-------
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
Dermal Exposure
Adherence factor (AF)
Absorption factor (ABS)
Basis/Reference
1 mg/cm2 US EPA, I992b
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)
Adult
Workers
16 kg
70 kg
70 kg
Exposure Duration (ED)
Residential 30 years
Industrial 25 years
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, 1989b
Average value, US
EPA, 1989b; US EPA,
1991
Average value, US
EPA, 1991
US EPA, 1989b; US EPA
1991
US EPA 1991
Average value, US
EPA, 1991
Average value, US
EPA, 1991
US EPA, 1989b
US EPA, 1989b
Figure 15 (Cent.)
-------
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.)
-------
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 a 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 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
43
-------
of vegetation growing in contaminated soil. 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 was 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
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.
44
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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 exceeded 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 as part of the final source action for source
material at the site including pit sludges and associated soils
buried pits, tank contents, and site soils and sediments. Remedial
action goals were also developed for the accumulated rainwater to
address the following pathways of potential exposure 1) ingestion
by humans; 2) dermal contact by humans; 3) ground water and soil
contamination due to overflow.
A summary of remedial action goals for the accumulated rainwater
on-site and for the excavated pits is shown in Figure 16 and
in Figure 17. The goals are based on site-specific LDEQ standards
for the accumulated rainwater and health-based risk values for the
soil clean-up levels.
In addition to these objectives the following remedial action goals
also apply:
Excavated Pit Clean-up Levels; For other previously
unidentified carcinogenic compounds, maximum
concentrations left untreated must be those which produce
a risk of 10"6 or less, with RMEs. For non-carcinogenic
compounds maximum concentration left untreated will be
those with an HI less than or equal to 1.
Accumulated Rainwater; For other previously unidentified
carcinogenic compounds, those which produce a risk of 10"6 or
less assuming it is consistent with the RMEs. For non-
carcinogenic compounds, the maximum concentration left
untreated must have an HI less than or equal to 1.
VIII. DESCRIPTION OF ALTERNATIVES
A feasibility study was conducted to develop and evaluate remedial
alternatives for the GCV site. Interim remedial alternatives were
assembled to address the potential problem of the accumulated
rainwater. Each of the five alternatives are developed
independently, although it is recognized that some interaction does
occur.
45
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FIGURE 16
Page 1 of 3
Louisiana Department of Environmental Quality
Effluent Pollutant Concentration Limits
A. CONVENTIONAL POLLUTANTS
Parameter
(mo/1)
Flow (6PM)
COD
TOC
BOD5
TSS
Oil & Grease
pH (S.U.)
B. METALS
Parameter
Total
Total
Total
Total
Total
Total
Total
Total
Total
Total
Total
Total
Total
Total
Stiver
Arsenic
Beryllium
Cadmium
Chromium
Copper
Mercury
Nickel
Lead
Antimony
Selenium
Thallium
Zinc
Cyani de
Total Barium
Daily Maximum
Report
100
50
30
30
15
Range of 6-9
Daily Maximum
(UQ/1)
110
137
275
275
343
824
93
549
275
549
110
549
686
1200
2 rag/1
Sample
Frequency
Dally
I/week
I/week
I/week
I/week
I/week
I/ week
Sample
Frequency
I/week
I/ week
I/week
I/week
I/week
I/week
I/week
I/week
I/week
I/week
I/week
I/week
I/week
I/week
I/week
Sample
Type
Estimate
24-hr Coiposite
24-hr Ccnposite
24-hr Coiposlte
24-hr Coiposlte
Grab
Grab
Sample
Type
24-hr Ccnposite
24-hr Ccnposite
24-hr Ccnposite
24-hr Ccnposite
24-hr Ccnposite
24-hr Ccnposite
24-hr Coiposite
24-hr Ccnposite
24-hr Conposite
24-hr Ccnposite
24-hr Coiposite
24-hr Ccnposite
24-hr Ccnposite
24-hr Ccnposite
24-hr Ccnposite
-------
Page 2 of 3
C. VOLATILE ORGANICS
Parameter
Acrylonitrile
Benzene
Carbon tetrachloride
Chlorobenzene
1,2-Dichl oroethane
1,1,1-Trichloroethane
1,1-Dichloroethane
1,1,2-Tri chloroethane
Chloroethane
Chloroform
1,1-Di chloroethylene
1,2-trans-Di chloroethylene
1,2-Di chloropropane
Methylene Chloride
Methyl Chloride
Tetrachloroethyl ene
Toluene
Tri chloroethylene
Vinyl Chloride
D. OTHER ORGANICS
Parameter
Acenaphthene
1,2,4-Tri chlorobenzene
Hexachlorobenzene
Hexachloroethane
1,2-Dichlorobenzene
1,3-Dichlorobenzene
1,4-Dichlorobenzene
1,3-Di choloropropylene
2,4-Dimethylphenol
Ethyl benzene
Flouranthene
Bi s(2-chloroi sopropyl)
Hexachlorobutadi ene
Naphthalene
Nitrobenzene
2-Nitrophenol
4-Nitrophenol
2,4-Dinitrophenol
4,6-Di ni tro-o-cresol
Dailv Maximum
(ua/1)
100
100
100
100
100
59
59
100
100
100
60
le 66
100
100
100
100
74
69
100
Dailv Maximum
(UQ/1)
47
100
100
100
100
TOO
A WU
100
100
47
100
54
J*T
ether 100
100
47
100
100
100
100
100
Sample
Freauencv
3/week
3/week
3/week
3/week
3/week
3/week
3/week
3/week
3/week
3/week
3/week
3/week
3/week
3/week
3/week
3/week
3/week
3/week
3/week
Sample
Freauencv
I/week
I/week
I/week
I/week
I/ week
I/ week
I/week
I/ Week
I/Week
I/week
I/week
I/ week
11 week
I/week
I/week
I/week
I/week
I/week
I/week
Sample
Tvoe
Grab
Grab
Grab
Grab
Grab
Grab
Grab
Grab
Grab
Grab
Grab
Grab
Grab
Grab
Grab
Grab
Grab
Grab
Grab
Sample
Tvoe
24-hr Ccnposite
24-hr Composite
24-hr Composite
24-hr Ccnposite
24-hr Composite
24-hr Composite
24-hr Composite
24-hr Composite
24-hr Composite
24-hr Composite
24-hr Composite
24-hr Composite
24-hr Composite
24-hr Composite
24-hr Composite
24-hr Composite
24-hr Ccnposite
24-hr Composite
24-hr Composite
-------
Page 3 of 3
D.
E.
IHtK UKUHIMlUi VL.UIIUIIIUCU/
Parameter Dai
Phpnol
Bis (2-ethyhexyl) phthalate
Di-n-butyl phthalate
Di ethyl phthalate
Dimethyl phthalate
Benzo (a) anthracene
Benzo(a)pyrene
3,4-Benzofluoranthene
Benzo ( k) f 1 ouranthene
Chrysene
Acenaphthylene
Anthracene
Fludrene
Phenanthrene
P* 1 V*f\V\ f\
ryrene
Polychlorinated biphenyls
Xyl ene
PESTICIDES
Iv Maximum
(ua/1)
47
100
43
100
47
47
48
48
47
47
47
47
47
47
48
10
100
Parameter Daily Maximum
Pentachlorophenol
a-BHC-Alpha
b-BHC-Beta
g-BHC-Gamma
a-ENDOSULFAN-Alpha
b-ENDOSULFAN-Beta
Endrin
Heptachlor
Toxaphene
2,4-Dichlorophenol
(ua/1)
250
90
90
90
90
90
180
90
5
47
Sample
Freauencv
I/week
I/week .
I/week
I/week
I/week
I/week
I/week
I/week
I/week
11 week
I/week
I/week
I/week
I/week
I/week
I/week
I/week
Sample
Freauencv
I/week
I/week
11 week
I/week
I/week
I/week
I/week
I/week
I/week
I/week
Sample
Tvoe
24-hr Ccnposite
24-hr Caiposite
24-hr Ccnposite
24-hr Ccnposite
24-hr Ccnposite
24-hr Carposite
24-hr Caiposite
24-hr Ccnposite
24-hr Caiposite
24-hr Caiposite
24-hr Ccnposite
24-hr Caiposite
24-hr Ccnposite
24-hr Caiposite
24-hr Ccnposite
24-hr Caiposite
24-hr Ccnposite
Sample
Type
24-hr Ccnposite
24-hr Caiposite
24-hr Caiposite
24-hr Gaiposite
24-hr Ccnposite
24-hr Caiposite
24-hr Caiposite
24-hr Ccnposite
24-hr Caiposite
24-hr Caiposite
-------
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The remedial action alternatives for Operable Unit Number 2 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 including public comments and
minor changes in the description of the alternatives. These
include a recalculation of excavation and engineering costs and the
elimination of the capping of any excavated pits under this action
since the pits will be excavated to clean-up levels.
This section addresses the rainwater that has accumulated on the
sludge in the Washout Pit and the West Pit. The primary
contaminants of concern driving the risk from exposure to the pit
sludges and the contaminated rainwater are PAHs along with several
inorganic constituents, including barium and arsenic. (Figure 17) .
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 TCLP limit for benzene. The contaminants
of concern, therefore include both organic and inorganic (metal)
constituents.
Several of the alternatives for treating the accumulated rainwater
additionally include the excavation of the Washout Pit or West Pit
or both to further protect human health and the environment and to
facilitate implementation of the both the interim and final remedy.
The volumes of material to be addressed under these alternatives
are listed below. These volumes assume excavation of the upper one
foot of soil below the sludge. The actual volume of soils
excavated could change during the construction phase of the remedy
based on the depth of contamination above remediation levels.
o West Pit - Size - 28,000 square feet
- Sludge Volume - 5,000 cubic yards
- Accumulated Rainwater - 1,300,000
gallons
o Washout Pit - Size - 12,000 square feet
- Sludge Volume - 2,700 cubic yards
- Accumulated Rainwater - 400,000 gallons
A brief description of the five alternatives evaluated to address
the accumulated rainwater follows:
o Alternative 1 Pump and Treat Accumulated Rainwater
o Alternative 2 Cover Washout Pit and West Pit with
Impermeable Membranes
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o Alternative 3 Consolidate Washout Pit Into West Pit and
Cover West Pit with an Impermeable
Membrane
o Alternative 4 Consolidate Washout Pit and West Pit into a
Lined Holding Area
o Alternative 5 Consolidate Washout Pit and West Pit into a
Temporary Holding Tank
A. Common Elements
Each of the alternatives listed above to address the accumulated
rainwater 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), construction of additional fences if
necessary, evaluation of alternate access routes, abandonment of
the 3 on-site water supply wells and air monitoring during
excavation. The monitoring will be on-site and at the site
boundary during excavation in this interim action.
All of the alternatives would involve pumping and treating a total
of about 1,700,000 gallons of accumulated rainwater. The volume of
water treated, assuming that each pit is full, is 1,300,000 gallons
from the West Pit and 400,000 gallons from the Washout Pit. The
rainwater has been found in the past to be contaminated with
organic and inorganic constituents such as zinc, aluminum,
chromium, barium, pentachlorophenol, lead, copper, ethylbenzene,
naphthalene, and phenanthrene. It is expected that this water
could have elevated levels of any of the above chemicals or any
other chemicals found in the pit sludges. Treatment of this
rainwater in the past has been successful in reducing the
contaminant concentration to below remedial action goals.
In each of the alternatives, the rainwater would be allowed to
accumulate to a pre-determined level in the waste pits. The
inorganic and organic-contaminated water would flow through a
treatment unit. The effluent water would be monitored during the
treatment process with a Chemical Oxygen Demand (COD) analyzer.
Composite samples of the effluent would be collected and analyzed
for volatile organic and semivolatile organic compounds, water
quality parameters, and metals as established by the Louisiana
Department of Environmental Quality (LDEQ). The water would be
discharged in accordance with the limits established by LDEQ. (See
Figure 16.) Treatment would be monitored to assure that
remediation goals are achieved.
For all of the alternatives except Alternative 1, accumulated
rainwater would no longer come into contact with contaminated pit
sludges.
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All of the alternatives that involve excavation involve
consolidating sludges and soils that have contaminant
concentrations that exceed remedial action goals. For the
excavation alternatives, all excavated areas will be excavated to
2 feet below contaminants that exceed remedial action goals. The
areas will be backfilled with clean soil. The emptied Washout Pit
would be closed by backfilling with soil. A two foot compacted
clay cap would be installed on the filled Washout Pit, covered with
topsoil and seeded. In addition all of the alternatives that
involve covering the sludge will use an impermeable synthetic
membrane that will be at least 60 mil thick.
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.
Note that costs for the three alternatives involving excavation
have been revised since the proposed plan. The revised costs
reflect the public comments and more precise estimates of
excavation and engineering costs. (See Appendix II.)
Alternative 1 Pump and Treat Accumulated Rainwater
Capital Cost: $115,650
Operation and Maintenance (annual): $86,050
Total Cost (present worth): $566,850
Time of Implementation:
Set-up: 7 weeks each operation
The major feature of this alternative is pumping and treating
1,700,000 gallons of accumulated rainwater. The water, which may
be contaminated with several organic and inorganic (metal)
contaminants, would be treated to the applicable discharge limits
before being released to the environment.
Treatment Components: The accumulated rainwater would flow through
a treatment unit and be discharged. The water would be discharged
in accordance with the limits established by LDEQ. Treatment will
be monitored to assure that remediation goals are achieved.
Containment Components: The alternative does not have a true
containment component. However, rainwater will be allowed to
accumulate in the pits approximately 6 months, until the pits are
full, before the remedy would be implemented.
General Components: The estimated time to implement this remedy
and meet the cleanup levels is 7 weeks for each pump and treat
operation. It is expected that this alternative would have to be
implemented 6 times prior to the final remedy being implemented.
This alternative allows the rainwater to accumulate for 6 months at
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a time and therefore, is not completely protective of human health
and the environment. Because this alternative does not completely
eliminate the risk of contact with the rainwater, it is not favored
by EPA.
The estimated costs for the rainwater treatment part of the remedy
are Capital costs: $115,650; O&M Costs: $86,050; Present worth:
$566,850.
Alternative 2 Cover Washout Pit and West Pit with Synthetic
Membranes
Alternative 2 is essentially the same as Alternative 1 except that
an impermeable synthetic membrane would be installed over the West
Pit and Washout Pit. The major feature of this alternative is
pumping and treating the 1,700,000 gallons of accumulated
rainwater. The water, which may be contaminated with the several
organic and inorganic (metal) contaminants would be treated to the
applicable discharge limits before being released to the
environment.
Capital Cost: $382,800
Operation and Maintenance (annual): $5,000
Total Cost (present worth): $395,700
Time of Implementation:
Set-up: 14 weeks each operation
Treatment Components: The accumulated rainwater would flow through
a treatment unit and be discharged. The water would be discharged
in accordance with the limits established by LDEQ. Treatment will
be monitored to assure that remediation goals are achieved.
Containment Components: The containment portion of this remedy
would be the installation of a impermeable synthetic membrane over
the sludge in the West Pit.
General Components: This alternative would allow ponding to occur
on top of the two liners. Ponding is a attractive nuisance which
means that it could attract trespassers, especially children. In
addition, the ponded water would have to be addressed in some
manner. The covering of two sludge pits also leaves the
possibility of squeezing of the waste speeding up ground water
contamination. Because it not fully protective of human health and
the environment for the above reasons, this alternative is not
favored by EPA.
The estimated time to implement this remedy and meet the cleanup
levels 14 weeks. The estimated costs for the remedy are Capital
costs: $382,800; O&M Costs: $5,000; Present worth: $395,700.
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D. Alternative 3 Consolidate Washout Pit Into West Pit and Cover
West Pit with an Synthetic Membrane
Capital Cost: $512,300
Operation and Maintenance (annual): $5,000
Total Cost (present worth): $525,200
Time of Implementation:
Set-up: 14 weeks
Alternative 3 contains the same treatment and containment
components as Alternative 2 and an additional element of
consolidation of the Washout Pit into the West Pit. In addition to
the water treatment, about 2700 cubic yards of sludge and 550 cubic
yards of contaminated soil (including a 40% bulking factor) will be
moved from the Washout Pit to the West Pit.
Treatment Components: The accumulated rainwater would flow through
a treatment unit and be discharged. The water would be discharged
in accordance with the limits established by LDEQ. Treatment will
be monitored to assure that remediation goals are achieved.
Containment Components: The containment portion of this remedy
would be the consolidation of soils and sludges into the West Pit
and the installation of impermeable synthetic membrane covers over
the West Pit and the newly closed Washout Pit.
The following steps will be taken: The sludge and soil from the
Washout Pit will be excavated and placed in the West Pit. Soils
from the buried waste pits may also be excavated in order to
achieve positive drainage and to give the sludge more structural
stability. If this does not achieve positive drainage, the free
board positions of the dike could also be used. An impermeable
membrane cover (described under Common Elements) will be installed
over the West Pit. The West Pit effluent will be analyzed
initially, but continued monitoring of run-off is not anticipated
since the rainwater will not come into contact with the waste
material.
In the event that the material excavated from the Washout Pit
exceeds the holding capacity of the West Pit, excess waste material
will be mounded on and around the West Pit and covered.
General Components: Implementation of this alternate would
eliminate the ponding that would be experienced if Alternative 2
were implemented because the volume of the soils and sludges would
stabilize and fill in the West Pit. During excavation, exact
volumes of contaminated material could be determined. This would
aid in implementation of the final action. It would be further
protective of human health and the environment because the Washout
Pit and possibly the buried pits would be excavated eliminating
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their threat to the groundwater. Because this alternative would be
fully protective in regard to the treatment of the rainwater and
would be further protective due to the excavation of one pit and
possibly the buried pits in a cost effective manner, this
alternative is favored by EPA.
The estimated time to implement this remedy and meet the cleanup
levels is 14 weeks. The estimated costs for the remedy are Capital
costs: $512,300; O&M Costs: $5,000; Present worth: $525,200.
Accumulated rainwater would no longer come into contact with
contaminated pit sludges under this alternative and the Washout Pit
will no longer be a possible source of groundwater contamination.
E. Alternative 4 Consolidate Washout Pit and West Pit into a Lined
Holding Area
Capital Cost: $821,250
Operation and Maintenance (annual): $5,000
Total Cost (present worth): $834,150
Time of Implementation:
Set-up: 17 weeks
Alternative 4 contains the same treatment and containment
components as Alternative 3 except that and instead of
consolidating the Washout Pit into the West Pit, the waste from
both pits would be placed in a lined holding area. In addition to
the water treatment, about 7700 cubic yards of sludge and 1820
cubic yards of contaminated soil (including a 40% bulking factor)
will be moved from the Washout Pit and the West Pit into a lined
impoundment constructed in the northeast Area of the site.
Treatment Components: The accumulated rainwater would flow through
a treatment unit and be discharged. The water would be discharged
in accordance with the limits established by LDEQ. Treatment will
be monitored to assure that remediation goals are achieved.
Containment Components: The containment portion of this remedy
would be the consolidation of soils and sludges from the Washout
Pit and the West Pit into a holding area and the installation of an
impermeable synthetic membrane cover over the holding area.
The following steps would be taken: The sludge and soil from the
Washout Pit and the West Pit would be excavated and placed in a
lined pit. An impermeable membrane cover (described under Common
Elements) would be installed over this new pit.
General Components: Implementation of this alternate would
eliminate the ponding that would be experienced if Alternative 2
were implemented because the volume of the soils and sludges placed
in a new lined pit would create a mound that would allow positive
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drainage. This alternative would be further protective of human
health and the environment because the West Pit and Washout Pit
would be excavated to clean-up levels, eliminating their threat to
the groundwater. Alternative 4 would be fully protective in regard
to the treatment of the rainwater and would also be fully
protective of the groundwater, providing that liner integrity was
maintained. The costs involved with this interim alternative,
however, are not proportional to the amount of risk that they will
reduce, since the cost of this alternative is 1.6 times more than
the cost of Alternative 3.
The estimated time to implement this remedy and meet the cleanup
levels is 17 weeks. The estimated costs for the remedy are Capital
costs: $821,250; O&M Costs: $5,000; Present worth: $834,150.
F. Alternative 5 consolidate Washout Pit and West Pit into a
Temporary Holding Tank
Capital Cost: $845,800
Operation and Maintenance (annual): $5,000
Total Cost (present worth): $858,700
Time of Implementation:
Set-up: 19 weeks
Alternative 5 contains the same treatment and containment
components as Alternative 4 except that excavated materials from
the West Pit and the Washout Pit would be placed into a temporary
holding tank instead of into another pit. In addition to the water
treatment, about 7700 cubic yards of sludge and 1820 cubic yards of
contaminated soil (including a 40% bulking factor) will be moved
from the Washout Pit and the West Pit into a temporary holding tank
will be constructed on the Northeast Area of the site.
Treatment Components: The accumulated rainwater would flow through
a treatment unit and be discharged. The water would be discharged
in accordance with the limits established by LDEQ. Treatment will
be monitored to assure that remediation goals are achieved.
Containment Components: The containment portion of this remedy
would be the consolidation of soils and sludges from the Washout
Pit and the West Pit into a temporary holding tank. The tank would
be constructed to be compatible with the contaminated materials
being stored in it and would have a projected life of the project
of three (3) years. The dimensions of the tank would be
approximately 260 feet on a side with a holding capacity of 2
million gallons. The tank would be covered with an impermeable
synthetic membrane.
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General Components: Implementation of this alternative would
eliminate the ponding that would be experienced if Alternative 2
were implemented because the volume of the soils and sludges would
be placed in a tank. This alternative would be further protective
of human health and the environment because the West Pit and
Washout Pit would be excavated to clean-up levels eliminating their
threat to the groundwater. Alternative 5 would be fully protective
in regard to the treatment of the rainwater and would also be the
most protective of the groundwater, providing that the tank
integrity were maintained. The costs involved with this interim
alternative, however, are not proportional to the amount of risk
that they will reduce, since the cost of this alternative is 1.6
times the cost of Alternative 3.
The estimated time to implement this remedy and meet the cleanup
levels is 19 weeks. The estimated costs for the remedy are Capital
costs: $845,800; O&M Costs: $5,000; Present worth: $858,700.
Accumulated rainwater would no longer come into contact with
contaminated pit sludges under this alternative and the Washout and
West Pits would no longer be a possible source of groundwater
contamination.
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 comment is 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.
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Compliance with ARARs. or "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
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.
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D. Comparative Analysis of Alternatives
1. Overall Protection of Human Health and the Environment
All of the alternatives 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.
All of the alternatives are protective of human health and the
environment by eliminating, reducing, or controlling risk through
treatment of accumulated rainwater contamination, engineering
controls and/or institutional controls.
Alternatives 3 is more protective of huma'n health and the
environment than Alternatives 1 and 2 because the risk of the
Washout Pit leaching contaminants that can infiltrate through the
underlying soils into the ground water will be eliminated. By the
Washout Pit soils and sludges being consolidated into the West Pit,
the West Pit Sludge will be more stable. Positive drainage will
also be achieved either through consolidation or by lowering the
dikes so that a mound is formed.
Alternative 4 is slightly more protective of human health and the
environment than Alternative 3 because both pits will be excavated
and placed in a lined pit and covered, eliminating risks from the
sludges, providing that the integrity of the liner is maintained.
Alternative 5 is the most protective alternative because tank
integrity is more easily maintained than liner integrity so the
risk from the pit sludges and buried pits to the environment will
be eliminated and the risks to human health will also be entirely
eliminated.
Compliance with ARARs
ARARs are federal and state requirements that the selected final
remedy must meet. All the interim action alternatives at the GCV
site will meet the standards set by LDEQ for the treatment and
discharge of the accumulated rainwater. In addition, those
involving excavation will meet the appropriate National Emission
Standards for Hazardous Air Pollutants, relevant and appropriate
portions of the Standards for Owners and Operators of Hazardous
Waste Management, Storage and Disposal Facilities and the
applicable Occupational Safety and Health Administration
regulations.
3. Long Term Effectiveness and Permanence
This criterion is not applicable to interim actions.
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4. Reduction of Toxicity, Nobility or Volume Through Treatment
The treatment of the contaminated rainwater in Alternatives 2-5 has
been implemented in the past and has been effective in bringing the
contaminant concentrations of the rainwater to below the water
quality limits set by LDEQ. For Alternative 1, the toxicity of
collected rainwater are periodically reduced through the pump and
treat procedures. The mobility of the contaminated rainwater is
also reduced by the pump and treat procedure. However, in the
event of a heavy rainfall, there exists a potential for the pits to
overflow without treatment which would not be monitored.
Therefore, the effective reduction in mobility for this alternative
is not as great as in Alternatives 2-5.
Like Alternative 1, Alternatives 2-5 will reduce the toxicity of
collected rainwater through treatment. Alternatives 2-5 will
equally eliminate the mobility of the contaminated rainwater by
preventing contact of the rainwater with the contaminated sludge.
Alternatives 4 and 5 further reduce the pit sludge mobility by
containing them in a lined excavation and in a tank respectively.
5. Short-Term Effectiveness
Alternative 1 will be effective in the short-term by pumping and
treating the contaminated rainwater thereby minimizing contaminated
overflow, however, even with strict monitoring of the level in the
pits, the possibility of contaminated rainwater overflowing still
exists. Since this alternative allows rainfall to accumulate in
between pump and treat episodes, its effectiveness is lessened
because people are exposed for approximately 6 month periods at a
time.
Alternatives 2-5 would also be effective in the short term because
the rainwater would be treated and discharged, but these
alternatives would involve some site worker risk. Alternative 2
would expose site workers to minimal physical and chemical hazards
during installation of the pit covers. Alternative 3-5 would
involve the same hazards as Alternative 2, and would further
involve evacuation of sludge and soil from the pits, which would
pose a more direct risk to the workers, both physical in using
earthmoving equipment, and chemical in moving the sludges and soil.
Alternative 3 involves the evacuation of only one pit, so it
involves less risk to workers than Alternatives 4 and 5 where two
pits are excavated. Risks to the community would be controlled by
air monitoring during excavation.
Alternative 1 would take the least time of all the alternative at
7 weeks, however it would periodically need to be re-implemented.
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The other alternatives would all take between 14 and 19 weeks to
implement which gives no alternative a clear benefit over the
other.
Of the three alternatives most protective of human health and the
environment and most capable of reducing toxicity mobility and
volume, Alternative 3, the preferred alternative, is the shortest
to implement at 14 weeks and would pose the least direct threat to
workers since only one pit would be excavated.
6. implementability
All of the alternatives evaluated present no technical or
administrative difficulties in implementation. -Implementability of
an alternative refers to the ease with which an alternative can be
accomplished, including such factors as availability of materials
and service. All of the alternatives evaluated present no
technical or administrative difficulties.
Alternative 1 is the most easily implemented because it is an
activity that has been conducted at the site, so labor and
equipment requirements are known and readily available. Likewise,
Alternative 2 can be quickly and easily implemented with labor and
materials available within the region surrounding the site.
Alternatives 3 through 5 require a significant amount of waste
handling however, the resources are readily available in the area
to effectively implement them. Alternative 3 involves the
evacuation of only one pit, so it involves less risk to workers
than Alternatives 4 and 5 where two pits are excavated.
7. COSt
The most expensive alternative to implement would be Alternative 5,
which has a present worth of $858,700. The least expensive
alternative is Alternative 2, with a present worth of $395,700.
The alternatives range in cost from $525,200 to $858,700.
Alternative 3, the selected remedy costs $525,200 which is the
middle of the price range of alternatives.
8. State Acceptance
Under the Super fund 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, 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 is
requesting the views of the State of Louisiana regarding cleanup
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options before selection of a remedy in the ROD. The commitment of
matching State funds is not required before actual on-site
construction 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 for
this Interim Action. The State of Louisiana is in agreement with
the selection of Alternative 3 to address the accumulated rainwater
and to begin the consolidation of the waste pits.
9. Community Acceptance
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 accumulated rainwater. The comments from the
residential community indicated that the community is in support of
the pumping and treating of this rainwater, but would like both the
West Pit and the Washout Pit to be excavated in this interim
action.
The Selected Remedy
Based on considerations of the requirements of CERCLA, the detailed
analysis of the alternatives using the nine criteria, public
comments, EPA has determined that Alternative 3, Consolidate
Washout Pit into West Pit and Cover West Pit with an Synthetic
Membrane is the mos-t appropriate interim action for the Gulf Coast
Vacuum Site in Vermilion Parish, Louisiana.
The major components of this alternative include:
- Pumping and treating of approximately 1,700,000 gallons of
inorganic (metals) and organic-contaminated accumulated
rainwater
- Discharge of the treated rainwater on-site
- Excavation of approximately 2,700 cubic yards of the
contaminated sludge and 550 cubic yards of associated soils
from the Washout pit (excavated to clean-up levels)
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- Consolidation of the excavated material into the West Pit to
achieve positive drainage in the West Pit
- Covering West Pit with an impermeable synthetic membrane
The principal threat associated with the accumulated rainwater at
the GCV site is the potential for overflow of the rainwater The
purpose of this response action is to control risks posed by direct
contact with accumulated rainwater and to minimize migration of the
contaminated rainwater to adjacent soils and into the groundwater.
The goal of the remedial action is to treat the accumulated
rainwater to the standards established by the Louisiana Department
of Environmental Quality. Treatment will be monitored to ensure
that these clean-up levels are achieved. An additional goal of the
response action is to excavate the Washout Pit to clean-up levels
which are 16 ppm for arsenic, 5400 ppm for barium, .66 ppm for
benzene, 3 ppm as benzo(A)pyrene equivalents for the carcinogenic
PAHs and an HI less than or equal to 1 for non-carcinogenic PAHs.
Clean-up levels for contaminants discovered during remedy
implementation and those contaminants above clean-up levels are
detailed in the Remedial Actions Goals Section.
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 also be cost-effective and for final source actions,
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 remedy for accumulated
rainwater at the Gulf Coast sites meet the statutory requirements.
A. Protection of Human Health and the Environment
In order to protect human health and the environment, the
accumulated rainwater that exceeds remedial action objectives will
be pumped and treated to the site-specific standards determined by
LDEQ. Material in the Washout Pit will be excavated to clean-up
standards and consolidated into the West Pit. These performance
standards will also assure that direct contact risks associated
with the accumulated rainwater will be eliminated and that this
material cease to act as an overflow threat.
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The selected remedy protects human health and the environment by
reducing the concentration of contaminants through treatment. Of
all the alternatives evaluated for the accumulated rainwater that
included a component of excavation of pits, the selected
alternative provides the best overall protection to human health
and the environment. No unacceptable short-term risks will be
caused by implementing this remedy.
B. Compliance With ARARs
Although it is not necessary that an interim action comply with
ARARs the selected remedy will meet the applicable LDEQ site-
specific discharge standards. These are applicable during
rainwater treatment and discharge. In addition, the excavation of
the Washout Pit will meet the following ARARs: ~
Chemical-Specific ARARs for Sludges, Tank Contents. Soils and
Sediments
1. National Emission Standards for Hazardous Air Pollutants (40
CFR Part 61) (NESHAPS). Relevant and appropriate during excavation
and consolidation processes.
2. Louisiana Department of Environmental Quality Discharge
Requirements. Site-specific discharge requirements.
Action-Specific ARARs for Sludges and Associated Soils
1. Standards for Owners and Operators of Hazardous Waste
Treatment/ Storage/ and Disposal Facilities (40 CFR Part 264).
May be relevant and appropriate during excavation
consolidation.
2. OSHA 1910.120 Occupational Safety and Health Regulations
Applicable because site workers may be exposed to
hazardous waste.
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 groundwater 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
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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 $10,015,000. 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 mobility for inorganics.
The selected alternative eliminates the hazards posed by the
organic constituents and greatly reduces those posed by the
inorganic contaminants at 37% of the cost of the alternative
involving off-site incineration.
D. Utilization of Permanent Solutions and Treatment or Resource
Recovery Technologies to the Maximum Extent Practicable
Although it is not required by statue for an interim remedy, EPA
believes the selected remedy represents the maximum extent to which
permanent solutions and treatment/resource recovery technologies
can be utilized in a cost-effective manner for the interim measures
at the GCV site.
E. Preference for Treatment as a Principal Element:
The statutory preference for remedies that employ treatment as a
principal element need not be met for an interim action, however,
the preference will be satisfied through implementation of
Alternative 3 for the treatment of the accumulated rainwater.
Though not required by statute, the selected interim remedy
utilizes permanent solutions and treatment technologies to the
maximum extent practicable.
F. Compliance with Long-Term Remedial Actions
Alternative 3 would be consistent with the final source action
proposed for the site. It treats the inorganic and organic-
contaminated rainwater and additionally implements part of the
final action by excavating the Washout Pit to clean-up levels
consistent with the final action. This will eliminate the need to
close the Washout Pit during the final action. In addition, an
accurate determination of the volume of sludge and associated soil
in the Washout Pit will be made which will assist in implementing
the final remedy.
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XI. DOCUMENTATION OF SIGNIFICANT CHANGES:
The proposed plan for the interim action at the GCV site was
released for public comment in July 1992. The proposed plan
identified Alternative 3, Consolidate Washout Pit into West Pit and
Cover Wets Pit with a Synthetic Impermeable Membrane as the
preferred alternative to address the accumulated rainwater. 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. A clay cover will not be placed on
the excavated Washout Pit since this area will be cleaned up to
clean-up levels. These differences did not affect selection of the
interim action alternative.
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State of Louisiana
Department of Environmental Quality
Edwin W. Edwards
Governor
Kai David Midboe
Secretary
September 30, 1992
Steve Gilrein (6H-SA)
US EPA Region VI
1445 Ross Avenue
Dallas, Texas 75202-2733
GULF COAST VACUUM SITE
Dear Mr.
The Inactive & Abandoned Sites Division concurs with you on your
conceptual remedy of on-site incineration and stabilization of
incinerator ash as well as contaminated site soils.
We also concur with your proposed plan for your interim source
action of operable unit #2, for controlling rain fall accumulation
and contaminated overflow from the pits on site.
If you need more information concerning this, please call me at
(504) 765-0487.
Sincerely,
Harold F. Ethridge, Jr.
Administrator
HFEJr/de
OFFICE OF LEGAL AFFAIRS AND ENFORCEMENT
o
recycled paper
INACTIVE AND ABANDONED SITES DIVISION P 0 BOX 82282
TELEPHONE (504) 765-0487 FAX (504) 765-0484
AN EQUAL OPPORTUNITY EMPLOYER
BATON ROUGE, LOUISIANA 70884-2282
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