PB98-963137
EPA 541-R98-149
March 1999
EPA Superfund
Record of Decision Amendment:
Hercules 009 Landfill
Brunswick, GA
8/14/1998
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S>*v-^ \ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
*" *^ \ REGION 4
9 ATLANTA FEDERAL CENTER
61 FORSYTH STREET
ATLANTA. GEORGIA 30303-8960
4WD-SSMB
MEMORANDUM
SUBJECT: Explanation of Significant Difference
Hercules 009 Landfill Superfund Site
Brunswick, Glynn Courjfey^ Georgia
FROM: Curt Fehn, Chief
South Site Management Branch
TO: Richard D. Green, Director
Waste Management Division
*
This memorandum serves to present the Hercules 009 Landfill
Superfund Site Explanation of Significant Difference (ESD) for
concurrence. The Record of Decision (ROD) was signed on March
25, 1993. The attached-ESD amends the ROD by changing the type
of cover to be placed on the treated landfill soils and sludges.
The ESD also explains EPA's justification for determining the
appropriate treatment depth in the landfill cells.
The remedy selected in the ROD includes in-situ
stabilization of subsurface and consolidated surface soils,
construction of a cover over the treated soils to reduce
rainwater infiltration and direct contact, and long-term
monitoring of groundwater.
Although the fundamental aspects of the remedy selected in
the ROD are unchanged, the ESD is necessary to change the type of
cover to be placed on the landfill. The State of Georgia, as
represented by the Environmental Protection Division (EPD), has
been provided an opportunity to comment on and concurs with this
ESD. All other aspects of the selected remedy remain unchanged
at the time of issuance of this ESD. I recommend concurrence
with this ESD.
Attached is a copy of the ESD Fact Sheet which will be
distributed to the public. The fact sheet explains the changes
to the remedy and the Agency's rationale for the change.
Internet Address (URL) • http://www.epa.gov
Recycled/FUcyclabl* • Printed with Vegetable Oil Based Inks on Recycled Paper (Minimum 25% Poslconsumer)
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Following concurrence with this ESD, the Agency will place the
fact sheet and supporting documentation in the Administrative
Record. EPA will provide notice of the availability of the BSD
and supporting documentation to the public by notice in the local
paper and mailing the fact sheet to the site mailing list.
NONCONCURRENCE
DATE
Attachment
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U.S. ENVIRONMENTAL PROTECTION AGENCY-REGION IV
Superfund Fact Sheet
August 1998
Hercules 009 Landfill Site
Brunswick, Glynn County, Georgia
Introduction
The U.S. Environmental Protection
Agency (EPA) is issuing this
Explanation of Significant
Difference (BSD) to clarify the
cleanup decision document for the
Hercules 009 Landfill (Hercules)
Superfund Site. EPA, in
consultation with the Georgia
Environmental Protection Division
(GAEPD), signed the Record of
Decision (ROD) selecting the remedy
for the Site in March 1993.
Although the clarifications provided
in this ESD to the ROD represent
a significant change to the
construction of the landfill cover,
they do not fundamentally change the
remedy. The remedy remains fully
protective of human health and the
environment.
EPA is issuing this ESD in
accordance with Section 117(c) of
the Comprehensive Environmental
Response, Compensation and Liability
Act of 1980 (CERCLA), as amended,
and Section 300.435(c)(2)(i) of the
National Contingency Plan (NCP).
CERCLA is the Superfund law, and the
NCP contains the regulations setting
forth how EPA will carry out its
responsibilities under the law.
Terms in bold italics are defined in
a glossary on page 3.
This ESD will become part of the
Administrative Record for the
cleanup decision for the Hercules
Site. The record is available for
review at the Information Repository
located at:
Brunswick-Glynn Regional Library
208 Gloucester Avenue
Brunswick, Georgia.
Background
The Hercules 009 Landfill Site
consists of land originally used as
a borrow pit during the construction
of Highway Spur 25. Hercules was
issued a permit in 1975 to use the
property as a waste landfill for
wastewater sludge generated during
the manufacturing process for
toxaphene. The permit was cancelled
after discovering toxaphene in the
drainage ditch adjacent to the site.
The landfill was closed in 1983 in
accordance with existing GA EPD
regulations.
Hercules, Incorporated, as a
Potentially Responsible Party (PRP)
at the Site completed a Remedial
Investigation (RI) and Feasibility
Study CFS; in 1992 under EPA
oversight pursuant to an
Administrative Order on Consent
(AOC). The RI was designed to
gather enough information regarding
the nature and extent of
contamination in order for EPA to
make a remedy selection. The RI
found toxaphene contamination in
soils, sludges, and groundwater. The
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PS analyzed alternative remedies for
ensuring protection of human health
and the environment at the Site.
EPA selected the cleanup remedy
described below for the site with a
Record of Decision dated March 1993.
The Agency then entered into a
Consent Decree with Hercules to
design and implement the remedy for
the site.
Selected Remedy
The major components of the selected
remedy for the Site include:
Conducting a treatability
study to evaluate in-situ
stabilization of site soils
and sludges,
Implementation of in-situ
stabilization of subsurface
soils and sludges and
consolidated surface soils.
Construction of a cover over
the treated soils to minimize
rainwater infiltration and
direct contact with the
treated soil,
Long-term monitoring of
groundwater, as well as
surface water and sediment in
the on-site pond and adjacent
drainage ditch.
Implementation of a
groundwater pump and treat
system, if EPA believes that
groundwater contaminants will
not naturally attenuate below
performance standards over
time.
Operation and maintenance of
the cover for a minimum of
thirty years, and
Institutional controls to
restrict land use and
groundwater use.
Explanation of Significant
Differences
The scope of this BSD involves a
change in the cover for the treated
soil in the landfill and in the
treatment of the soils excavated
from outside the landfill. This ESD
also describes technical concerns
and additional groundwater
information, which arose or became
available during the remedial
design.
The ROD specified that surface soils
from outside the landfill cells
would be placed in the landfill for
treatment. A multi-media or clay
cover was to be constructed over the
treated soils. The change described
in this ESD is to treat the surface
soils from outside the landfill in
an on-site treatment unit and use
the treated soil as the landfill
cover. These surface soils
originated in the site areas
adjacent to the landfill and contain
greater than 0.25 ppm toxaphene.
The soils are currently stockpiled
in the southern portion of the
Hercules property.
The landfill cover will use soils
from the stockpile which contain
toxaphene at a concentration
consistent with the treatment
standards for hazardous wastes
contained in Subpart D of RCRA Land
Disposal Restrictions at 40 CFR Part
268. Previous testing results
indicate that all stockpiled soil
meets these standards. The soil will
be screened to remove material
greater than 3 inches, such as
stumps and roots. Rejected material
will be disposed of on-site or
buried within the soil-cement
material. The screened soil will be
blended with dry Portland cement and
water in an on-site pug mill. A
mixture of at least 3% Portland
cement and 97% soil by weight will
be used for the cover. The blended
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material will be placed and graded
to form a cover over the entire
landfill. The cover will be between
one and three feet in thickness. The
cover will be tested for compliance
with construction standards. An
additional multi-media or clay cover
will not be constructed.
Technical and safety concerns have
arisen during the Remedial Design
phase of the project. Specifically,
concerns exist for slope instability
(which could cause equipment or
personnel to fall into the treatment
area), hydrostatic inflow (the
"blow-in" of groundwater caused by
different groundwater levels between
the landfill and the regional
groundwater), and admixture dilution
(the mixing of excess groundwater
with the soil/cement mixture). These
situations could cause unsafe.
working conditions or unfavorable
construction conditions, which could
make the remedy less effective.
Groundwater monitoring data
collected in 1994 and 1998 have
shown that toxaphene has not
migrated into the groundwater
beneath the site. Treatment of
subsurface soils and sludges above
the regional groundwater table will
add an additional level of safety to
ensure that toxaphene will not
migrate into the groundwater. The
need for groundwater monitoring to
determine whether the remedial
action is effective is not modified
by this BSD. Given current knowledge
of site circumstances, EPA does not
expect the groundwater pump and
treat contingency to be needed at
the site.
As a consequence of the groundwater
data and the technical and safety
concerns, EPA has determined that
contaminated sludge and soil will be
treated until the performance
standard is met or the regional
groundwater table is reached,
whichever comes first. Treatment in
this manner will reduce the
possibility of "blow-in" and of side
sloping. Dilution will be controlled
by limited groundwater pumping, as
necessary. This action is
consistent with the groundwater
modeling used to determine the
subsurface soil performance standard
of 76 ppm. The groundwater model
and its results apply to the soil
located above the regional
groundwater table, i.e., the
unsaturated soil. If treatment does
not proceed to the regional
groundwater table, confirmatory
samples will be taken to establish
the concentration of toxaphene
remaining in the soil at that level.
Data gathered by measuring
groundwater levels tend to indicate
that complete solidification of
toxaphene sludge can be achieved
notwithstanding the technical
concerns expressed in this ESD.
Toxaphene remaining in the soil will
not pose an unacceptable risk to
human health and the environment.
Statutory Determination
The selected remedy for the Hercules
Superfund Site remains fully
protective of human health and the
environment, in compliance with
Federal and State standards
applicable or relevant and
appropriate to the cleanup, and
cost-effective.
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Glossary
Administrative .Record:
Documentation of basis for EPA
selection of a Superfund cleanup
remedy, placed with Information
Repoaitory.
Information Repository: Documents
located near a Superfund site for
public review.
PRP: Potentially Responsible Party -
a company or individual who owned or
operated or trans-ported or disposed
waste at a Superfund site.
Record of Decision (ROD) -. Document
stating EPA's rationale for cleanup
remedy selection at a Superfund
site.
Remedial .Investigation (RI) /
Feasibility Study (FS): Superfund
long-term cleanup study to collect
necessary data to determine the type
and extent of contamination at NPL
sites and to evaluate possible risk
reduction measures.
Superfund: Common name for the
Comprehensive Environmental
Response, Compensation, and
Liability Act (CERCLA) established
to address uncontrolled or abandoned
hazardous waste sites.
EPA Contacts
Annie Godfrey, Project Manager
or
Angela Leach, Community Relations
South Site Management Branch/EPA - Region 4
61 Forsyth Street, SW
Atlanta, Georgia 30303
1-800-435-9234
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