United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5502G)
EPA520-F-93-015
Summer 1993
« EPA Su perf u nd At Work
Hazardous Waste Cleanup Efforts Nationwide
Site Description:
A former sand and gravel quarry
located two miles southwest of
New Castle, Delaware
Site Size: 47 acres
Primary Contaminants:
Volatile organic compounds (VOCs),
and heavy metals including chro-
mium, iron, mercury, and zinc
Potential Range of Health Risks:
Long-term consumption of contami-
nants could lead to gastrointestinal
disorders, liver and kidney damage
Nearby Population Affected:
130,000 people within three miles
Ecological Concerns:
High-quality wetlands, aquatic
creatures and other wildlife
Year Listed on NPL: 1983
EPA Region: 3
State: Delaware
Congressional District: 1
High quality wetlands surrounding Army Creek Landfill were contaminated with
hazardous substances.
Success In Brief
Environmental Victory
At Army Creek Landfill
Through the efforts of the Superfund enforcement program, the U.S.
Environmental Protection Agency (EPA) successfully negotiated with
waste contributors to clean up the Army Creek Landfill site. Both
public water supplies and fragile wetlands were at risk from hazard-
ous waste dumping in the 1960s. With the cooperation of New Castle
County, EPA:
• Negotiated a $25 million cleanup of the landfill, ground water,
and surface water; ,
• Employed the latest technologies to reduce the risk of contamina-
tion of local drinking water;
• Facilitated negotiations for an $800,000 settlement for restoration
of wetlands affected by dumping in nearby Army Creek and
Army Creek Pond; and
• Settled with 18 parties to recover $1 million in past cleanup costs.
The Army Creek settlement conserves Superfund dollars for hazard-
ous waste sites where viable parties cannot be found to compensate for
environmental damage. The use of private resources for cleanup
demonstrates EPA's commitment to the environment through fair and
equitable enforcement.
The Site Today
Early installation of ground water
recovery wells substantially reduced
the immediate threat of contamina-
tion to public water supply wells. To
permanently control the source of
contamination, waste contributors
began building a multi-layer cap'
over Army Creek landfill in the
spring of 1992.
In addition, workers started
construction of a water treatment
plant to decontaminate discharge
from the recovery wells. EPA super-
vises all work performed at the site.
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Superfund At Work
Army Creek Landfill, New Castle, DE • Summer 1993
The Army Creek Landfill,
a former sand and gravel
quarry, lies approximately
two miles southwest of New
Castle, Delaware. The aban-
doned landfill is bordered by
Army Creek, which discharges
into the Delaware River
approximately one mile east
of the site.
The residential community
of Llangollen Estates, and a
public supply well field
operated by the Artesian
Water Company, are located
less than a mile south of the
site. An estimated 130,000
people live within three miles
of the site and rely on ground
water for household use.
A Site Snapshot
Fortunately, drinking water
supplies have not been contami-
nated.
Next to the landfill is the Dela-
ware Sand and Gravel Landfill,
another Superfund site. New
Volatile organic
compounds
and heavy metals
have contaminated
the ground water
Castle County owned and oper-
ated the 47-acre Army Creek
Landfill between 1960 and 1968,
when it was filled to capacity with
two million cubic yards of indus-
trial and municipal wastes. A
variety of chemicals also were
haphazardly discarded in the
landfill.
Volatile organic compounds
(VOCs) and heavy metals such
as chromium, mercury, and
zinc have contaminated the
ground water.
The surface water is also
degraded. High levels of these
contaminants were detected in
Army Creek and Army Creek
Pond, a small body of water
located southeast of the landfill.
Mercury and chromium
have detrimental effects on
aquatic creatures inhabiting the
creek and wildlife frequenting
the high-quality wetlands near
the pond.
Army Creek Landfill
Timeline
• Superfund legislation enacted
• County installs wells to protect public drinking water
County and state sample ground water
1 Contamination detected in
nearby residential well
1 Landfill closed
1
Municipal and industrial waste disposal
1
1960
1968
1971 1972 1973
Page 2
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Superfund At Work • Army Creek Landfill, New Castle, DE • Summer 1993
Hazardous Substances Leak into Ground Water
County Attempts
To Curtail Pollution
Ground water contamination
first became apparent in 1971
when a local resident reported
that his well water had gone bad.
In response, the State of Delaware
and New Castle County began
sampling the ground water in
Contamination from
two neighboring landfills
was seeping into
local aquifers
1972. The County's studies sought
to identify and define the extent
of the contamination.
Investigations revealed that
leakage originating from the two
neighboring landfills was seeping
underground and contaminating
local aquifers, potentially affect-
ing 5,000 residents. In response,
the County installed a series of
ground water recovery wells in
1973. This prevented the contami-
nants from reaching public sup-
ply wells belonging to the Arte-
sian Water Company.
The recovery wells created an
underground water divide be-
tween the landfills and the Arte-
sian well fields. Contaminated
ground water was pumped and
brought to the surface for dis-
charge into Army Creek and
Army Creek Pond.
Army Creek
Becomes Superfund Site
The Superfund program was
created by Congress in 1980. This
program gave EPA the authority
to allocate federal funds to clean
Army Creek Landfill
New Castle, Delaware
up hazardous
waste sites across
the nation. In 1983,
the Army Creek
Landfill site was
included on the
first National
Priorities List (NPL), EPA's roster
of sites eligible for cleanup.
At this time, EPA reviewed the
County's studies, and determined
their investigations were complete
enough to serve as the first step in
a Superfund cleanup: an official
evaluation of the nature and
extent of contamination at a site.
New Castle County agreed to
go one step further by performing
\ • Site listed on NPL
/ • EPArevi
EPA reviews county studies
County submits cleanup alternatives, proposes corrective measures
r
Protective cap design completed
r
EPA studies Army Creek and Army Creek Pond
EPA selects surface water cleanup approach
Settling parties agree to conduct cleanup
/ • Construction of cap and water treatment plant begins
Construction complete (planned)
Five-year evaluation of
selected cleanup activities
(planned)
1983
1986 1989 1990
1992
1995
1999
Page 3
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Superfund At Work
Army Creek Landfill, New Castle, DE
Summer 1993
an analysis of potential cleanup
alternatives, including corrective
measures for the site. Their analysis
was completed in September 1986.
That summer, EPA identified
over 20 corporate entities as
Twenty corporate entities
were identified as
potentially responsible
parties
potentially responsible parties
and requested that they partici-
pate in carrying out the remedy
selected for the site. The identified
parties failed to reach an accept-
able agreement: therefore, EPA
continued with the cleanup.
EPA Chooses Remedy
to Protect Ground Water
In 1986, on the basis of the
county's analysis, EPA chose a
remedy to control the source of
ground water contamination.
Phase one of the cleanup involved
installing a protective cap to cover
the landfill to prevent rainfall
from infiltrating the hazardous
waste. The cap would minimize
any further migration of the
ground water contaminants.
The recovery well network
installed by the county to capture
contaminated ground water
would continue operations. In
addition, the recovery wells also
would be used to monitor the
effectiveness of the cap over a
five-year period.
A worker smooths newly delivered soil for the protective cap, part of phase one of
the cleanup.
During phase two of the
cleanup, EPA will use the results
of this five-year evaluation to
determine whether additional
pollution controls will be neces-
sary. Monitoring and evaluation
of the recovery well system will
accompany its long-term opera-
tion and maintenance.
EPA Protects
Natural Resources
Once the landfill cap was
designed, EPA shifted its attention
to the contamination of Army
Creek and Army Creek Pond.
Surface water samples indi-
cated that the creek and pond had
been partially degraded by dis-
charge from the recovery wells.
In January 1989, EPA asked the
waste contributors to cooperate in
conducting a focused study of
surface water contamination.
Once again, the notified parties
refused to perform the study, and
so EPA evaluated Army Creek
and Army Creek Pond in Febru-
ary 1990.
Resulting data indicated el-
evated concentrations of chro-
mium, cadmium, iron, mercury
and zinc exceeding surface water
quality standards, but only iron
could be directly linked to the
recovery well discharge. The
other contaminants were believed
to originate from Army Creek
leachate or off-site surface runoff.
continued on page 5
Page 4
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Superfund At Work
Army Creek Landfill, New Castle, DE
Summer 1993
Environmental Trustees to
Restore Damaged Habitat
Federal and state natural resource trustees played a prominent
role in the cleanup of the environment surrounding Army Creek
Landfill. Settling parties agreed to pay an additional $800,000 to
environmental trustees at the National Oceanic and Atmospheric
Administration, the Department of the Interior, and the State of
Delaware. The natural resource trustees will use this money to
improve wetlands in the vicinity of the site.
This part of the settlement was intended to offset injury to wet-
lands and aquatic life resulting from the release of hazardous
substances from the landfill and contaminated ground water
discharged into Army Creek and Army Creek Pond.
Funds for improving nearby wetlands were part of the settlement
Hazards Leak into Ground Water
continued from page 4
In June 1990, EPA selected a
cleanup remedy for the surface
water, which involved construc-
tion of a water treatment plant.
The treatment plant purifies the
ground water brought up by the
recovery wells prior to its dis-
charge into Army Creek.
To track the level of contami-
nants, EPA will undertake a long-
term monitoring program of
ground water, surface water,
sediments, and associated wet-
lands affected by the site.
Following extensive negotia-
tions with EPA, the waste con-
tributors began construction of
the selected remedies in the
spring of 1992.
EPA's
Pursuit of
Waste
Contributors
Pays Off
In September 1990, EPA
reached a formal cleanup
agreement with 18 waste
contributors who were
willing to enter into a mixed-
funding agreement.
Under mixed funding,
EPA settles with fewer than
all of the responsible parties
at a site for a substantial
portion of the cleanup. The
remainder of the costs can be
contributed by EPA, or
obtained from other finan-
cially viable waste contribu-
tors. In the settlement with
EPA, 18 parties agreed:
• To conduct a $25 million
cleanup that involves
building the cap, monitor-
ing the pumping systems,
and constructing and
operating the wastewater
treatment plant according
to EPA specifications;
• To compensate EPA's
Superfund program for $1
million in past costs; and
• To fund future EPA
oversight costs, estimated
at another $1 million.
This settlement provides
recovery of approximately
71% of past response costs.
In addition, the settling
parties will undertake the
remedies selected to address
soil, ground water, and
surface water contamination.
Page 5
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Superfund At Work
Army Creek Landfill, New Castle, DE • Summer 1993
Success at Army Creek Landfill
By promptly addressing the immediate risk of design and conduct a $25 million cleanup, and
ground water contamination, the Superfund reimburse EPA for $1 million of previously
program reduced the threat to drinking water incurred response costs.
supplies posed by the Army Creek Landfill. EPA In addition, federal and state natural resource
also responded to immediate
environmental concerns by
orchestrating comprehensive
cleanup'actions for the site.
EPA Successfully con-
cluded negotiations with 18
parties Responsible for con-
taminants at the site. Under
the terms of the settlement,
the waste contributors will
The safety of the
drinking water
supply was greatly
enhanced by prompt
actions at the Army
Creek Landfill site
trustees have received
$800,000 to help them
counteract damages to
wetlands and aquatic life.
Although construction
activities are scheduled to
be completed in the spring
of 1995, the potential for
exposure to contaminants at
this site has been eliminated.
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or to comment on this bulletin's content, length or format,
please call (703) 603-8984 or send a letter to
Superfund At Work(5502G),
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For additional copies of this or other Superfund At Work updates,
contact the National Technical Information Service,
U.S. Department of Commerce,
5285 Port Royal Road, Springfield, VA 22161,
telephone (703) 487-4650.
EPA
United States Environmental Protection Agency
5502G
Washington, D.C. 20460
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