PB94-963924
EPA/ROD/R03-93/170
December 1994
EPA Superfund
Record of Decision:
E.I. Du Pont,
Newport, DE
8/26/1993
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4.
50272.101
REPORT DOCUMENTA110N 1'. REPORT NO.
PAGE EPA/ROD/R03-93/170
TItle and Subtitle
SUPERFUND RECORD OF DECISION
E.I. Du Pont, Newport, DE
First Remedial Action - Final
Auttlor(a)
2.
3. Recipient'. Ace88.1on No.
5.
Report Oat.
08/26/93
6.
7.
8.
P8rtDrm1ng Organization Rapt. No.
II.
Performing Organization Nama and Addr-
10
Projact TaaklWork Unit No.
11. Coraract(C) or Orant(O) No.
(C)
(0)
12. ~ Organization Nama and Add-
U.S. Environmental Protection
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report & Period Covarad
Agency
800/800
14.
15. Supplamantary NoIa8
PB94-963924
16. Abstract (Umlt: 200 words)
The 120-acre E.I. Du Pont, Newport site is located in Newport, New Castle County,
Delaware. Land use in the area is predominantly industrial, with a paint pigment
production facility (Ciba-Geigy plant), a chromium dioxide production facility (Du Pont
Holly Run plant), two industrial landfills separated by the Christina River, a baseball
diamond, and the nearby Koppers Superfund site. The site also contains two wetland
areas designated as North and South, which encompass the floodplGin area, and overlie
the Columbia and Potomac aquifers. The pigment plant began manufacturing operations in
1902 to produce Lithopone, a white, zinc- and barium-based inorganic paint pigment. In
1929, Du Pont purchased the site. Du Pont ceased production of Lithopone in 1952, but
had begun producing other organic and inorganic pigments containing several metals.
From 1961 to 1966, drums of thorium waste were disposed of in the North Landfill.
These drums contained two to five percent thorium oxide bound to nickel as an off-
specification product. However, EPA has determined that no removal or remediation of
these drums is required since, due to the low solubility of thorium oxide, it is
unlikely that there would be any migration of contaminants at any significant levels
away from the landfill. In the 1970s, Du Pont constructed the Holly Run plant to
expand its production of chromium dioxide. In 1984, Du Pont sold the pigment
(See Attached Page)
17. Document AnalysIs L Dascrlptora
Record of Decision - E.I. Du Pont, Newport, DE
First Remedial Action - Final
Contaminated Media: soil, sediment, gw, sw
Key Contaminants: VOCs (PCE, TCE), metals (arsenic,
materials
chromium, lead), radioactive
b.
1cIant1fi8f'8lC)pe...enc Tanna
c.
COSATI FlalcllGroup
18. Availability Slat_I'll
111. Security CIea (this R.port)
None
20. Security CIa8 (ThIs Page)
None
21. No. of Pages
180
22. Prtca
(Sea ANSI-Z39.18)
SN/mtlUCti0n8 OIl ""...
OPTIONAL FORM 272 (4-77)
tFonnarty ~
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EPA/ROD/R03-93/170
E.I. Du Pont, Newport, DE
First Remedial Action - Final
Abstract (Continued)
manufacturing operations to Ciba-Geigy Corporation, but retained the chromium dioxide
production operations. These two plants were built on fill material placed over low-lying
farmland. The fill is contaminated with heavy metals, including cadmium, lead, barium,
and zinc. Pigment waste and off-specification products were disposed of in the North and
South Landfills. The North Landfill was used for Lithopone waste, other organic pigment
waste, chromium waste, and other miscellaneous waste from 1902 until 1974. The South
Landfill, located in the South Wetlands, also was used for the disposal of Lithopone waste
from 1902 until 1953. Neither of the landfills had a bottom liner. A small portion of the
Ballpark appears to have become contaminated when contaminated soil from the pigment plant
was used to groom the field. State investigations conducted in the late 19705 and 19805,
indicated elevated levels of heavy metals and VOCs in the onsite ground water. In 1993,
EPA required Du Pont to address the seepage of a heat transfer fluid into the Christina
River. During the RI/FS, Ciba-Geigy removed an underground storage tank used to store
diesel fuel and repaired discharge piping to the river because cracks in the piping were
allowing ground water infiltration, which led to discharge of zinc to the Christina River
in excess of the Ciba-Geigy NPDES permit. Sediment contamination has been attributed to
precipitation of contaminants from ground water as it discharges to the Christina River or
the wetlands, direct dumping, and erosion and surface water runoff from the landfills.
Surface water contamination has been attributed to the discharge of contaminated ground
water and/or contact with contaminated sediment and source discharges from the Ciba-Geigy
plant. This ROD addresses contamination at the Ballpark, North and South Landfills, North
and South Wetlands, Christina River, and the Ciba-Geigy and Du Pont Holly Run plants as a
final remedy. The primary contaminants of concern affecting the soil, sediment, ground
water, and surface water are VOCs, including PCE and TCE; metals, including arsenic,
chromium, and lead; and radioactive materials.
The selected remedial action for this site includes excavating approximately 1 yd3 of
lead-contaminated soil above 500 mg/kg from the Ballpark, the top one foot of contaminated
sediment from the North and South Wetlands, and the contaminated soil from the South
Landfill that is located on Delaware property; disposing of the excavated soil and/or
sediment from the Ballpark, North Wetlands, and Lithopone waste from piles near the North
Landfill onsite in the North Landfill; disposing of the excavated sediment from the South
Wetlands and the soil from the Delaware property portion of the South Landfill onsite in
the South Landfill; treating contaminated soil in the South Landfill onsite using in-situ
stabilization to reduce the ability of the metals to leach into the ground water, if
determined necessary by TCLP and modified TCLP testing; capping the North and South
Landfills to minimize continued ground water contamination; backfilling with clean fill
and revegetating all excavated areas; constructing a physical barrier wall along the
Christina River from the Ciba-Geigy plant to the North Landfill to limit migration of
ground water to the river; installing extraction wells on the chemical plant side of the
wall to recover and control mounding of ground water, followed by onsite treatment using
air stripping to remove VOCs and precipitation to remove metals; restoring and monitoring
the North and South Wetlands; dredging contaminated sediment from the Christina River,
followed by onsite treatment by dewatering and/or stabilization, and onsite disposal in
the North or South Landfills or offsite in an EPA-approved disposal facility; discharging
treated effluent onsite to surface water or offsite to a POTW; backfilling dredged areas
with clean fill; paving contaminated plant areas; developing and implementing erosion
control, operations and maintenance, and waste management plans; monitoring ground water,
surface water, and air; providing an alternate water supply to residences and businesses
near the site; and implementing institutional controls, including deed and land use
restrictions. The estimated present worth cost for this remedial action is $47,700,000,
which includes an estimated annual O&M cost of $18,607,000 for 30 years.
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EPA/ROD/R03-93/170
E.I. Du Pont, Newport, DE
First Remedial Action - Final
Abstract (Continued)
PERFORMANCE STANDARDS OR GOALS:
Chemical-specific sediment cleanup goals, based on toxicity tests and benthic studies, are
cadmium 60 mg/kg; lead 1,200 mg/kg; and zinc 5,600 mg/kg. The chemical-specific soil
excavation goal for the Ballpark is lead 500 mg/kg. ARAR waivers for technical
impracticability and greater risk to human health and the environment were issued for the
Columbia and Potomac aquifers, North and South Wetlands, and the Christina River because
attempts to mitigate these areas would cause additional contamination, would adversely
affect the wetlands around the South Landfill, or contamination from offsite sources would
prevent attainment of ARARs.
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,,1G'
ISz)
\':~:7
EPA REGION 3
AUGUST 1993
RECORD OF DECISION
E.I. DU PONT, NEWPORT SUPERFUND SITE
NEW CASTLE COUNTY, DELAWARE'
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RECORD OF DECISION
E.I. DU PONT, NEWPORT SITE
DECLARATION
SITE NAME AND LOCATION
E.I. Du Pont, Newport site
Newport, New Castle County, Delaware
.STATEMENT OF BASIS AND PURPOSE
. This decision document presents the selected remedial ,action'
for. the E.I. Du Pont, Newport site (Site), in' Newport, New Castle
County, Delaware, which was chosen in accordance with the'
requirements of the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA), as amended, 42
U.S.C. SS 9601 et seq., and, to the extent practicable, the
National Oil and Hazardous Substances Pollution Contingency Plan
(NCP), 40 C.F.R. Part 300.. This decision document explains' the
factual and legal basis for selecting the remedy for this site.
The information supporting this remedial action decision is
contained in the Administrat~ve Record file for this Site.
. ..
The.state of Delaware has elected not to concuroh the
selected remedy for the re~sons outlined in its August 17, 1993
letter (see Attachment A of this Record of Decision). However,
during the Record of Decision (ROD) development process, the
state expressed support for many of the major components of the
selected remedy.
ASSESSHENT OF THE SITE.
The site is hIghly contaminated and this contamination is
mainly the result of decades of industrial waste disposal and
plant operations. Pursuant to duly delegated authority,' I hereby
determine, pursuant to'Section 106 of CERCLA, 42 U.S.C. S 9606,
that actual or threatened releases of hazardous substances from
this Site, if not addressed by implementing the response action
selected in this Record of Decision (ROD), may present an
imminent and substantial endangerment to public health, welfare,
or the environment. .
DESCRIPTION OF THE SELECTED REMEDY
This remedy addresses soils, sediments, surface water, and
ground water contamination at the Site. This is a final Record
of Decision for the Site. The principal ~hreats at this Site. are
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contaminated soils containing: hazardous substances at the north
and south landfills and at the CIBA-GEIGY and the Du Pont Holly
Run plants, and contaminate~ sediments containing: hazardous
substances in the north drainage way. Treatment is a major
component- of the remedy at the south landfill while containment
is the major component at the other locations due to Site-
specific conditions. Below is a summary of the selected remedy:
. BallDark: Excavation of soils above 500 ppm lead with
disposal in-the north landfill.
. PurDose: Prevent human exposure to elevated
levels of lead. -
. - North landfill: - Capping;- wetland remediation,
restoration, and monitoring; vertical barrier wall
to base of the Columbia aquifer; and ground-water
recovery and treatment.
. PurDose: Prevent continued releases of
contaminants to the ground water which discharges
to the river and the north wetlands, clean up -
areas of unacceptable environmental impact in the
north wetlands, prevent exposure of plant and.
terrestrial life to_contaminated soils.
down-
. South-landfill: Excavation and consolidation-of.
contaminated soil underneath and to the east of Basin
Road or South James street onto the south landfill; in-
situ soil stabilization of the combined soil; capping
of the south landfill. -
. PurDose: Prevent continued releases of
contaminants to the ground water which discharges
to the river and the south wetlands, prevent
unacceptable human exposure to contaminated soils
_from the landfill. .
. South wetlands:
Excavation, restoration, monitoring.
. PurDose: Prevent unacceptable impacts to
environmental receptors.
. Christina River:
Dredging, monitoring.
. PurDose: Prevent unacceptable impacts to
- environmental re~eptors.
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. CIBA-GEIGY and Du Pont Hollv Run plants: Vertical
barrier wall along the Christina River at the CIBA-
GEIGY plant, pave the rest of the ground within the
contaminated plant areas, recoyer ~nd treat the ground
water up-gradient of the barrier wall, institute .
special health and safety plans for intrusive work.
. PurDose: Prevent continued releases of
contaminants to the ground water which discharges
to the river, prevent unacceptable human exposure
to contaminated soils.
. Ground water: Monitoring,' provide public water supply
along Old Airport Road, establish a ground water
manc~,gement . zone. ' . '
. PurDose: Prevent human exposure to Site-related
contaminated ground water, prevent further
contamination of the Columbia and the Potomac
aquifers, protect the south wetlands.
The remedy for the ground water also includes invoking the
"greater risk 'to human health and the environment" applicable or
relevant and appropriate requirements (ARAR) waiver. This waiver
applies to both the Columbia and Potomac aquifers. At~empts to
.remediatethe.Potomac aquifer will cause more contamination to
migrate into the Potomac aquifer directly underneath .the Site.
from the more highly contaminated Columbia'aquifer. Attempts to
remediate the Columbia aquifer will adversely affect the wetlands
around the south landfill. These adverse effects outweigh the.
benefits of installing pump. and treat systems in these aquifers.
There is currently no human exposure to this ground water, nor is
any expected to occur in the future. However, a long-term
monitoring program will be instituted as part of this .Record of
Decision to make sure that this waiver continues to be justified.
Appr9priate remedial measures shall be taken if the monitoring
:data indicates a .nece~sity to d~ .so. ,. '... .
State of Delaware Surface Water Quality .Standards (SwQSs)
are being waived in the north wetlands and the river using.the
"technicai impracticability" ARAR waiver because of off-site
sources. Federal ambient water quality criteria are hereby being
waived in the river for the same reason. SWQSs are also being
waived in the south wetlands using the "greater risk to human
health and the environment" waiver because compliance would
require destruction of far more wetlands than is estimated
necessary in order to protect the enyironment.
The total present worth cost of the selected remedy is
approximately $47,700,000.
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DBCLARATION 01' STATUTORY DETERMINATIONS
The selected remedy ,is protective of human health and the
environment, complies with Federal and state requirements that
are legally applicable or relevant and appropriate to the
remedial action (or a waiver can be justified for any federal and
state applicable or relevant and appropriate requirements that
will not be met) and is cost-effective. This remedy utilizes
permanent solutions and alternative treatment (or resource
recovery) technologies to the maximum extent practicable, and it
satisfies the statutory preference for remedies that'employ
treatment that reduce toxicity, mobility, or volume as their'
principal element~
, Because this remedy will result, in hazardous,substances',.
'remaining on site ,above health-based levels, a review will be
conducted within five years after commencement of remedial action'
to ensure that the remedy continues to provide adequate
protection of human health and the environment. Such reviews
will be conducted every five years thereafter until EPA
determines that the cleanup levels set forth in this ROD have,
been achieved, or that the hazardous substances remaining on the
site do not prevent unlimited use and unrestricted exposure at
the Site.
Laskowski
gional Administrator
~~~
Date
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DECISION SUMMARY
SITE DESCRIPTION AND BACKGROUND
The E.I. Du Pont, Newport Superfund Site (commonly known as
the Du Pont-Newport site and referred to throughout this document
as the "Site") is located partially in Newport, New Castle
County, Delaware and partially' in unincorporated New Castle
County, Delaware. It is an approximatel'y 120-acre site'located
at James and Water Streets in Newport, Delaware near the 1-95,
1-495, and Delaware State 141 interchange (see Figure 1). The
site inclUdes 'land currently occupied by a paint pigment
production facility (the CIBA-GEIGY plant), a chromium dioxide
production facility (the Du Pont Holly Run plant), two industrial
iandfills separated by the Christina Riverl (the site includes'
portions of the river in which Site-related contamination has
come to be located), and a baseball diamond (owned by Du Pont and
referred to as the ballpark) located just northwest of the CIBA-
GEIGY plant across the Amtrak railroad (see Figure 2).
The pigment plant, originally built during the period from
1900 to 1902, was owned and operated by Henrik J. Krebs and
manufactured Lithopone, a white, zinc- and barium-based inorganic
paint 'pigment. In 1929, E.I. du Pont de Nemours & Company"
':(Du Pont) purchased the plant and continued tp produceLithopo~e.
Due to a decline in popularity, Lithopone ,production, ceased in
1952. By this time, however, Du Pont had begun to produce
different organic and inorganic pigments, as well as other
miscellaneous products.' Some of these included purified titanium
dioxide (the titanium dioxide was produced elsewhere), titanium
metal, blue and green copper phthalocyanine pigments (CPC), red
quinacridone pigment (QA), high purity silicon, thoriated nickel,
and chromium dioxide. In order to expand the production of. .
chromium dioxide, Du Pont constructed the Holly Run plant during
the 1970's. In 1984, Du Pont sold the pigment manufacturing,
operations to CIBA-GEIGY corpo:ration, but retained the chromium
dioxide production operations.
The Holly Run plant and the CIBA-GEIGY plant were built on
fill material placed ,over low-lying farmland. Most of the fill
material underneath the CIBA-GEIGY plant and a small portion at
the Du Pont plant is contaminated with heavy metals such as
lKnown locally also as the Christiana River. Public water
supply; industrial watersupplYi primary contact recreation;.
fish, aquatic life and wildlifei and agricultural water supply
are the designated uses for this area of the river per Delaware's
Surface Water Quality Standards, as amended, February, 26, 1993.
Boating, water skiing, and fishing have been observed adjacent to
CIBA-GEIGY's plant.
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cadmium, lead, barium, and zinc. This is a result of disposal
operations and poor storage and handling practices of raw
materials. As part of the CIBA-GEIGY piqment plant operations
(although prior to CIBA-GEIGY's ownership), waste, and off-
specification products were disposed of in the north and south
landfills.
The north landfill was constructed by building a berm along
the Christina River on low-lying farmland'adjacent to the
Lithopone plant. Disposal activities involved backfilling behind'
the berm. Construction was such that waste and ~off,could have
flowed around the toe of the ~rm and into the river. ' There was
no bottom liner in the, landfill. It was used for the'disposal of
Lithopone wastes; other organic piqment wastes, chromium wastes,
and other miscellaneou$ wa$tes including off-spec thoriated ,
'nickel. wastes were 'disposed of in the north landfill from 1902 '" '
to 1974. ' '
The south landfill was used ,for the disposal of large
quantities of Lithopone wastes which were pumped through a hose
on the river bottom and discharged to diked area in a wetland.
There was no bottom liner, and some of the waste is currently in
the water table. The south landfill operated from approximately
1902 to 1953.2
, A' small portion of the'ballpark appears to have become
contaminated' when contaminated soil fro~ the piqmentplantwas
used to groom the field. It should be noted that this Site is
located downstream of Churchman's Marsh which the ' Water Resources
Agency of New Castle County is evaluating as a pot~ntial ~ocation
of a public water supply reservoir. EPA does not expect the
remedy outlined in the ROP to impact Churchman's Marsh but can
not state so definitively until the remedial design is completed.
In the late 1970's and early 1980's, the Delaware Department
of Natural Resources and Environmental Control (DNREC>' and
: Du Pont ,sampled and analyzed ground water from on-site monitoring
wells. The' results' indicated' elevated levels of heavy metals, ',"
(especially parium, cadmium, and zinc) and volatile organic
compounds (mainly tetrachloroethene and trichloroethene) in
ground water. During the mid 1980's, EPA and DNREC gathered and
2Sased on the information obtained during the remedial
investigation and feasibility study, on-Site disposal activities
stopped prior to the enactment of the Resource Conservation and
Recovery Act (RCRA, 42 V.S.C. 55 6901 et sea.). When necessary,
the determination of whether or not RCRA is an ARAR is discussed
for each area of the Site under the ftDescription of Alternatives
and Summary of the Comparative Analysis of Alternativesft section
and in the "Compliance With Applicable or Relevant and
Appropriate Requirementsft section of this Record of Deci&ion.
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reviewed information to determine whether or not the site was
eligible for the National Priorities List (NPL). The Site was
proposed for inclusion on the NPL in January 1987 and was
promulgated in February 1990. '
On August 22, 1988 Du Pont entered into an Administrative
Order by Consent with EP~ whereby Du Pont agreed to ,perform a
Remedial Investigation and Feasibility study (RIfFS) for the
Site. This study has included collection of ground water, soil,
sediment, and surface water (both river ,and wetlands) samples.
Although the Site was originally included on the NPL because of
ground-water contamination caused by the north landfill, the
RIfFS has found that the river and the adjacent wetlands are,
contaminated as well. Some,areas show s~gnificant impacts to tne
'ecqsystem, although 9ther areas have only minor impacts. ' The,
RIjFSalso determined that the south 'landfill and 'the soil
underneath the production plants are sources of ground-water
contamination.
HISTORY OF OTHER ENFORCEMENT ACTIVITIES
On June, 10, 1993, EPA and Du Pont entered into a removal,
consent order to address seepage of a heat transfer fluid'
(similar ,in comp9sition to Dowtherm) into the Christina River.
The 'seeps, along the north bank of the ~hristiria',River, ,are, "
'causing an oil sheen on the Christina River. CIBA-GEIGY has been
reporting these releases to the National Response Center
beginning in october 1992. oil sorbing booms are ,currently in
place to control the spread of the fluid. EPA has determined
that the levels of Dowtherm are potentially hazardous to aquatic
life and that the booms are not an adequate measure of control
until such a time as this ROD is implemented which will
permanently address this problem. compliance with the EPA
removal order will provide an interim remedy for the seeps.
. . '. .
. . . . . '.
Several oth~r,projectshave taken place during the ~IfFS'in
order to address environmental problems. CIBA-GEIGY removed an
underground storage tank that at one time was used to store
diesel fuel. CIBA-GEIGYalso performed repairs to discharge
piping to the Christina River. Cracks in the piping were
allowing ground water' infiltration which was causing discharges
of zinc in excess of CIBA~GEIGY's NPDES permit.
HIGHLIGHTS OF COMMtJ1fITY PARTICIPATION
Pursuant to Section 113(k) (2)(B)(i~v) of the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980
(CERCLA), as amended, the RIfFS reports and the Proposed Remedial
Action Plan (Proposed Plan) for this Site were released to the
public for comment on November 13, 1992. These documents were
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,-
made available to the public in the Administrative Record file
located at the EPA Docket Room in Region 3's Philadelphia office,
The Kirkwood Library in Wilmington, Delaware, and the Town Hall
of Newport in. Newport, Delaware. The notice of availability of
these documents was published in The wilminaton News Journal on .
November 13, 1992. A public comment period on the documents was
originally scheduled from November 13, 1992 to December 14, 1992.
However, due to a timely request for an extension, 45 days were
added to the comment period, extending it to January 28, 1993.
In addition, a public meeting was held on December 2, 1992, .at
the Town Hall of Newport. At this meeting, representatives from
EPA answered questions about conditions at the Site and th~
remedial alternatives under consideration. A response to the
comments received during the public comment period, including
those expressed verbally at. the public meeting, is included in
the Responsiveness 'Summary, wl1ich is part of this Record..of .
Decision (ROD). This ROD. presents the selected remedial act"ion
for the E.I. Du Pont, Newport site in New Castle County,
Delaware, chosen in accordance with CERCLA and the National Oil.
and Hazardous Substances Pollution Contingency Plan (NCP), 40 CFR
Part 300. The decision for this Site is based. on the
Administrative Record placed in the above-mentioned locations.
SUMMARY OP SZTB CHARACTERISTICS
Data collected during the'RlfFS determined that the .Site has
extensive contamination in soils, sediments, ground water,
surface water, and plant tissue. Some slightly elevated levels
. of contamination were also detected in one fish species.' The
following sections discuss the contaminants found in soils,
sediments, ground water, and surface water. Data collected
during the fish tissue studies, plant tissue studies, benthic
studies, and sediment toxicity tests will be discussed in the
"summary of site Risks" section.
. SOILS
The RI determined that high concentrations of certain metals
~xist in soils in the north. landfill, in the south. landfill, and
underneath the CIBA-GEIGY and the Du Pont Holly Run plants.
Elevated levels of metals. were also found in the ballpark.
Background metal concentrations for soils in the vicinity of the
Site were difficult to establish due to the generally disturbed
nature of the soils in the area. For this reason, metals
detected in the soils at the site were compared to reported
background.so~l concentrations in a northern Delaware site in the
u.S. Geological Survey's "Element Concentrations in Soil& and
Other Surficial Materials of the Conterminous United states" (see
Table 1) which EPA has determined are adequate for this RI.
Figure 3 shows the location of soil samples collected during the
RI and where metals levels exceeded background (i~e., where
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contamination is present). It also lists contaminant levels at
various locations. At many of these sampling locations, a number
of samples were collected at different depths.
Barium, zinc, cadmium, arsenic, lead, mercury, silver,
antimony, cobalt, copper, selenium, and vanadium were all
detected.above background levels. Of these metals barium, zinc,
cadmium, and lead w~re the most prevalent. Contaminant levels
underneath the CIBA-GEIGY plant are as high as 0.6% arsenic, 13%
lead, 9% barium, and 6% zinc. The north landfill has levels a~
high as 4% barium, 5% zinc, and 5% lead. The south landfill has
levels as high as 7% barium, 1.6% lead, and 1% zinc.3
, As indicated above, the north and south landfills are
heavily contaminated. ' See Table 2 for a list of estimated
quantities of materials that were disposed of in the north
landfill. One of the largest waste streams at the site came from
the Lithopone process where raw zinc and barium ores were refined
to make a paint pigment. This waste stream consisted of
insoluble residues from the zinc and barium refining process.
This residue also contained all of the heavy metal contaminants
present in the raw material ore as well as zinc and barium. Some
of this waste appears to have been disposed of in the north.
landfill although most of it was disposed to the south landfill.
~he Lithopone waste ~tream was pumped as a slUrry through a
pipeline to the'south side of the Christina River and discharged
into a wetland. Dikes had been built to control the movement of
the sludge (which ,hardened upon exposure to air, forming the
sout~ landfill), however aerial photographs show that at times,
the dikes were breached, and the sludge flowed into areas of
which some are the present day wetlands.' ,
The south landfill was covered in the early 1970's with soil
excavated from the area which is now part of the Delaware
. Route 141 Chrj.,stina River bridge approach ra~p.' This was ,done by'
the Delaware Department of Transportation (DeIDOT) as part of the'
bridge construction. In order to construct this bridge, Basin
Road (or South James Street) was moved west onto the south
landfill. Historical aerial photographs show the south landfill
extended to the edge of the original Basin Road. DelDOT soil
borings taken in the early 1970's confirmed this when one of the
stratigraphic units in several borings located between the new
and old Basin Road was characterized as "chemical fill" '(see
Figures 4 and 5).
310,000 parts per million (ppm) are equivalent to one
percent. Therefore, soil containing 5% lead is equivalent to
soil containing 50,000 ppm lead.
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_.~~..
At the contaminated plant areas, the highest metals
concentrations are predominantly in the former barium and zinc
ore storage areas associated with historic Lithopone production
and in the Lithopone production areas. at the central and eastern
end of the CIBA-GEIGY plant. construction of the original .
Lithopone plant began near James street. As the plant was
expanded, construction moved westward. Originally, the land was
low-lying farmland. The elevation was raised with fil~ material.
Photographs show that early. raw mat~rial handling .practices
included open piles of barium and zinc ores.. Some of these ores
were probably mixed into the fill material. Also, a' part of the
central to western portion of the CIBA-GEIGY plant was
constructed on top of a former industrial pond that most likely
contained wastes from the Lithopone process. Undoubtedly, much
of the contamination in the soils is a result of waste disposal
in this pond.' .'
Organic contaminants as well as metals were found in the
soil at the contaminated plan~ areas. The organic contamination
(mainly tetrachloroethene and trichloroethene, but also including
polynuclear aromatic hydrocarbons (PARs) such as .
'benzo(a) anthracene, phthalate esters such as bis(2-
ethylhexyl) phthalate, chlorobenzenes, dibenzofuran, and
chlorophenols) was not nearly as prevalent as the metal
contamination and was generally located in the central and
western portion of the ClBA-GEIGY plant area. Past. production of.
copper phthalocyanine (CPC), quinacridone (QA)'; and titanium .
metal are probable causes of the organic contamination. utility
operations which involved the burning of coal probably
contributed to the PAR contamination. QA continues to' be
produced at the CIBA-GEIGY plant today.
Elevated levels of metals in the ballpark are primarily in
the area adjacent to Ayre Street and the baseball diamond (see
Fiqure 6 for sampling locations and contaminant concentrations).
.~t is believed that the only source of these metals is from fill
for' the baseball field' (as opposed to transport of 'airborne'. .
. particulates). A review of aerial photography dating back to .
1937 for this area of the site suggests that ~he current location
of the ballpark coincides with the recreational area that existed
during much of the historical Lithopone operation era.
Conversion of the ballpark into a parking lot coincided
approximately with the termination of Lithopone operations in the
early 1950's. By 1968, the area was returned to use as a
ballpark. Fill material from the site was reportedly used to
manicure the baseball diamond over the history of its use (from
pre-1940's). Pedestrian tracking t~ the p~rking lot fr~m the
Site and the use of fill material at the baseball diamond are
believed to have been sufficient to create the concentrations of
metals found there. Lead is the only metal elevated to a level
of concern in the ballpark.
6
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!-.-
SEDIMENTS
Sediments at the Site have become contaminated in a variety
of ways including: precipitation of some' of the contaminants
from' ground water as it discharges to the Christina River or the
wetlands; direct dumping (as in the case of the breached dikes at
the south landfill); erosion/surface water runoff which in all
likelihood carried contamination from the north disposal area to
the river during the time the landfill was open; and the incoming
tide carrying contamination from the north drainage way to the
north wetlands. Sediments samples were collected in the north
wetlands (including the drainage way), the south wetlands
(including the south pond), and the river. Figure 7. shows the
sampling locations and some of. the 'actual chemistry analysis
results. ,As c.an be seen 'from this figure, the contaminant levels
. are relatively high. For comparison purposes, see Table 3 for a .
list of EPA Threshold Value Guidelines (TVGs).4 TvGs are not
promulgated criteria, but are levels at which toxicity is
expected to occur.
Since contaminant levels at a particular samplinq location
are very dependent on the physical characteristics of the
sediments, qrain size and total organic carbon (TOC) analyses
were also performed. This physical data of the sediments allowed
the chemistry data to be normalizeds so differences between
sampling 'stations could be .ascertained. 'By plotting the,
normalized sediment data of the Christina River, it d:in"be .
clearly seen that sediments adjacent to the north landfill and
the CIBA-GEIGY plant have sharply elevated levels of a number of
Site-related contaminants including lead, cadmium, chromium,
barium, copper, mercury, and zinc (See Figure 8).
4EPA Threshold Value Guidelines, National Perspective on
Sediment Quality (1985).
, .
, . '
Soue to the eXtreme ~ariability that can' occur in sedi~ent
contaminant leveis due to naturally occurrinq physical/chemical
conditions such as deposition rates, sediment. types, qrain size
and organic matter content, comparinq sediment chemistry from
different sampling stations and sampling events to determine
where anthropogenic (manmade) loadinq has occurred becomes
difficult. Normalizing the data allows a more direct comparison
of sediment chemistry between different stations to take place.
In this case it was determined that the grain size of the
sediments .was the qreatest. cause of natural variabi'lity (see
Environmental Evaluation, 8/7/92, paqe 4-6). By normalizing the
data to qrain size (dividinq the actual contaminant levels by the
percentaqe of sediments from that sample that pass through a 64
micron sieve) the effect of qrain size on the sediment chemistry
is removed.
7
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GROUND WATER
Data collected during the RI/FS showed that two major
aquifers are present beneath the Site: the Columbia (the upper
aquifer) and the Potomac (the lower aquifer). The Potomac
aquifer is subdivided into two water-bearing zones, the upper
. Potomac aquifer and the lower Potomac aquifer. All of the
filling operations (for construction "and waste disposal) have
created another localized aquifer referred to as the fill zone
(see Figure 9 for a simplified cross section). Low-permeability
soi1.s l:e.s"'t:rict gl:ound wate.r fl:om f'lowing between the different
water-bearing zones and aquifers, but do not prevent flow. . This
provides a pathway for contamination to migrate between the
water-bearing zones and/or aquifers. Five rounds of ground-water
samples were collected during the three phases of the RI." The'
chemical analyses performed on these samples are summarized in
Tables 4 and 5. Figures 10, 11, 12, and 13 show the well
locations in each of the water-bearing zones with examples of
ground-water sampling results. Table 6 shows the maximum
contaminant levels (HCLs) and the non-zero maximum contaminant
level goals (HCLGs) for various contaminants at the site.
Figure 14 shows the extent of ground-water contamination that
exceeds HCLs or non-zero HCLGs and is considered unsafe to drink.
The chemicals that were found at concentrations which exceed MCLS
or non-zero HCLGs include cadmium, PCE, TCE, lead, barium,
beryllium, carbon tetrachloride, 1,2-dichlorobenzene, 1;4-
dichlorobenzene, chlorobenzene,' vinyl chloride, benzene, and"
antimony. Also, zinc, arsenic, and cobalt have been detected at
levels at the site that are considered unsafe to drink.
Generally," ground water in the Columbia aquifer flows toward
the Christina River while ground water in the Potomac aquifer
flows south. Ground water from the Potomac .leaks upward into the
Columbia, although in portions of the Site it is the other way
around (see Figures 15 and 16 that show the direction of ground
wate~fl~w between the different water-bearing units).
" .
Data" collected during the RI and during the early 1980's
indicated that, although the ground water itself has been
migrating, the size of the organic or inorganic contaminant plume"
has not appreciably changed. The limited migration away from the
Site is probably caused bygro~d-water flow directions in the
Columbia aquifer mainly confining the contaminants to the Site.
For the Potomac aquifer, the fact that since the plant process
water wells have ceased operation, there is only a small
potential for contaminants to transfer from the Columbia aquifer
to the Potoma~ aquifer thereby limiting the spread of
contaminants. For the inorganic contaminants, this retardation
has also likely occurred because at the leading edge of the plume
where the contaminant levels are small, naturally-occurring
anions in the ground water cause the inorganic contaminants to
precipitate out of solution.
8
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To.date, EPA has not concluded that the nearby residential
wells located southeast of the Sit~ along Old Airport Road are
affected ~y Site-related contamination. .
SURFACE WATER
Surface water at the Site includes the Christina River, the
north wetland area and drainage way, and the south wetlands.
Surface water in these areas of the. Site is being contaminated by
discharging ground water and/or due to being in contact with
contaminated sediments. Surface water in the Christina River
also receives contamination from point-source discharges 'from the
CIBA-GEIGY plant. These discharges are monitored through a
National Pollution Discharge Elimination System (NPDES) permit.
During the RI, a number of unpermitted discharge pipes were
discovered that had. been installed over the years of plant
operation. These have since been plugged. Also, repairs have
been made to some of the remaining discharge pipes because of
cracks in the piping that were allowing contaminated ground water
to enter and flow to the river, at times causing NPDES permit
limits for zinc to be exceeded. .
Most of the samples collected were analyzed for Target
Analyte List (TAL) metals. A'small number of samples (mostly
leachate samples along the north. river bank) were also ana.lyzed.
for 'Target . Compound List (TCL) volatile organic compounds.' '. .
Several samples from this subset were also analyzed for TCL semi-
volatile organic compounds. Figure 17 shows the surface water
sampling locations and selected results. . contamination was found
in all of the samples. One of the leachate samples from the
north landfill was also analyzed for radioactivity. The results
of the sampling were compared to Ambient Water Quality Criteria
(AWQC) and the State of Delaware's Surface Water Quality
Standards (SWQSs). The following contaminants exceeded AWQC and
SWQSsat one or more locations (most were found over a vast
portion of the site): lead, copper, zinc, 'cac:Uni\im, aluminum,
iron, chromium, mercury, dichlorobenzenes, and tetrac;hloroetbene. '.
See Table 7 for a list of the actual SWQS values. .Note that
while iron and aluminum may be considered site-related
contaminants, they exist in naturally-occurring high levels in
soils and, therefore, in the ground water and surface water in
this area. Also note that the italicized compounds were detected
in leachate seeps along the north river bank in a localized area.
These seeps are toxic to aquatic life. The ground-water seeps
along the north bank of the river would require as high as a 600
to 1 dilution for zinc, as high as a 400 to 1 dilution for lead
and as high as a 140 to 1 dilution for cadmium in order to reach
their respective AWQC or SWQSs (see Figure 66, RI report,
8/26/92). These seeps are very likely to cause near-field AWQC
. 9
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1-
!
exceedances6 and must.be controlled in order to protect the
environment.
.Alth9ugh there are other known sources of contamination to
the christina River upstream of the Site, several sets of metal
loading calculations (see the Data Sufficiency Memorandum,
Remedial Investigation-Phase 2, 4/27/89, and the Remedial
Investigation Report, 8/26/92, in the Administrative Record)
performed during the ~I show that the Site potentially
contributes greatly to the AWQC exceedances in the river. For
example, one model showed the Site causing the zinc levels in the
river to increase by 61 ppb. The AWQC for zinc is 110 ppb with
exceedances occurring in the river at ~e Site. Controlling the
discharge of the ground water to the river and wetlands would
eliminate.the toxic effects on aquatio life caused by the
contamination in the ground water. .
OTHER:
RADIONUCLEIDE STUDIES
Because drums. of solid waste containing thorium-232, which
. is a radioactive material, w~re disposed of in the north landfill
from 1961 to 1966, data was 'collected before and during the RI to
evaluate the potential threat of a release to soils or ground
water. Most of these drums that were buried in the north
landfill contained an off-specification product of nickel
containing two to five percent th9rium oxide~' Plant records
indicate that the drUms'were'buried 10 feet below the sUrface.
Since their burial, another two feet of soil has been placed on
the north landfill. Du Pont reported in the RI that all thorium
buried in the north landfill was in the thorium oxide form.
Thorium oxide has a very low solubility, and under most natural
environmental conditions, leaching of thor.ium oxide would not
result in any significant ground-water contamination. Du Pont
was also licensed to dispose of small quantiti&s of soluble
thorium salts which if present in the north landfill pose a
greater potential threat of contaminati~n to the ground water.
'. . . .
.. . .
Thoririm-232 is a. commonly used metal in high' temperature
alloys such as those found in jet engines. It is also used in
gas lamp mantels. Thorium is a radioactive material that decays
spontaneously releasing radiation and producing various decay
products, which are also radioactive and which can cause
significant radiation exposure. The thorium oxide production and
disposal operation was licensed by the U.S.' Atomic Energy
Commission.
~adiation' emitted from the thorium and its.decay.products in
the north landfill was not observed above background radiation
6EPA interview of Rick Green, Water Resource~ Division,
DNREC, 5/27/93
10
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levels at the surface of the landfill. The cover of the landfill
and the other wastes present in the landfill attenuate the gamma
radiation from the thorium waste. One well, SM-4, had levels of
radium-228 at 5.6 picoCUries per liter (piC/I). Radium-228 is a.
daughter product from the decay of thorium-232. Well SM-4 has
also consistently exhibited gross alpha levels slightly above the
MCL of 15 piC/I. Since SM-4 is located at the toe (southwest
end) of the landfill, there was concern early in the RI that the
drums of thoriated nickel were causing a release. Further .
. sampling of ground water, leachate.from the landfill, and river
sediments provided no further evidence of a release. In fact,
the results indicate that the levels. detected in SM-4 are more
likely caused by background thorium7 since. SM-3, which is
between SM-4 and the suspe~ted burial area, did not show any
signs of a re1.ease~' . . '. .' .'
. The principle radiation hazard associated with the thorium
waste is from direct gamma radiation emitted from the thorium and
its decay products. If someone, who was not wearing proper
personnel protective equipment, exposed the thoriUm waste at the
surface by excavating through the cover, that'individual could
receive significant exposure from gamma radiation emitted by the
thorium waste." In addition, inhalation of dust containing the
thorium waste, ingestion of contaminated crops and ground water,
and inhala~ion of radioactive radon-220 gas formed as .a'decay .
.'prpduct of thorium-232 would cause radiation exposure. which cOUld
be significant depending upon the concentration of the thorium in
the waste and the. conditions of the exposure. .
EPA has determined that the most protective remedy for these
drums involves leaving them 'buried in the north landfill as long
as the only form of thorium that was disposed of is thorium
oxide. Due to the method of disposal and the high insolubility
of thorium oxide, it is highly unlikely that there would be any
migration of radioactive contaminants at any significant levels
away .from tQe north landfill. Ground water monitoring can verify
. whether or not there is' a release in the future. EPA has also,
determined that institutional controls can be, implemented which
are. adequate to protect the public from direct contact exposure
to the thorium. In the future, if potential changes ~n the land
use indicate that the institutional controls may not be adequate,
EPA'may require further response actions at that time beyond
those called for in this ROD.
. ,
Furthermore, if in the future, information becomes available
that indicates that soluble forms of thorium were or probably
were' disposed of at the site in l~rge. enough quantities to pose'a
7The background levels of radium-228 (a daughter product of
thorium) in public drinking water supplies averages in the 4 to 6
piC/l range in some states.
11
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significant threat to the public or the environment, EPA may at
that time require further response actions beyond those called
for in this ROD such as removing the drUms to an EPA-approved
off-site disposal facility. .
SCOPE AND ROLE OF REMEDIAL ACTION
As part of the RI/FS, a risk assessment was performed by
Du Pont to evaluate the actual and potential threats that the
contamination poses to human health (Human Health Evaluation:
3/18/92)8 and to the environment (Environmental Evaluation: .
8/7/92). For a discussion of the results of the risk assessment,
see the next section titled "Summary of site Risks."
Once. EPA determines from the risk assessment 'that remedial"
action is necessary at a' site, EPA characterizes waste on-site as .
either a principal threat waste or a ~ow level threat waste. The
concept of principal threat waste and low level threat waste as
developed by EPA in the National Oil and Hazardous Substances
Pollution contingency Plan (NCP) is applied on a site-specific
basis when characterizing source material. "Source material" is
defined as material that includes or contains hazardous
substances, pollutants, or contaminants that act as a reservoir
for migration of contamination to. ground water, to surface water,
to. .air, or that acts as a source for direct exposure.. SQurce '.
materials are. considered to be principal threat wasteS when they
contain high concentrations of toxic compounds (e.g., several
orders of magnitude above' levels tpat allow for unrestricted use
and unlimited exposure) or are highly mobile and generally cannot
be reliably contained.
From the results of the RI/FS, EPA has determined that'
contaminated soil or sediments in several areas ~f the site are
principal threats. The principle threats include the'
contaminated soil beneath the CIBA-GEIGY plant;. the contaminated
waste in the north and' south landfills, and the contaminated'
sediments in the north drainage 'way (adjac'ent to the north
landfill). The sediments in the north drainage way have
contaminant levels as high as 3% lead and 2% zinc.
section 300.430(a) (1) (iii) of the NCP states that "EPA
expects to use treatment to address the principal threats posed
by a site, wherever practicablje," that "EPA expects to use
engineering controls, such as containment, for waste that poses a
relatively low, long-term threat or where treatment is
.impracticable," and that "EPA expects to use a combination of .
methods, as appropriate, to achieve protection of human health
8EPA has ind~pendently reviewed Du Pont's human health risk
assessment and has determined that it is acceptable to EPA.
12
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and the environment." It also states that I1EPA expects to use
institutional controls...to supplement engineering controls as
appropriate...," and that'institutional controls may be used
"where necessary, as a component of the completed remedy."
However, the NCP also states that institutional controls "shall
not substitute for active response measures...as the sole remedy
unless such active measures are determined not to be
practicable..." After giving carefu3: consideration to the NCP,
to available technologies, and to the Site characteristics, EPA
has determined that treatment is practicable for one but not all
of the principal threats at the Site. "
EPA has determined that treatment of the contaminated soil
in the, so~th landfill is practicable. However, for contaminated
soil beneath the CIBA-GEIGY plaht, the contaminated. soil in th~
north landfill" and the contaminated sediments in the north' ,
drainage way, EPA has determined that, due to Site-specific
conditions, it is not feasible to meet the expectation that these
principal threats be treated. In-siru, stabilization9 is not
practicable and ex-situ stabilization is not feasible in the
north landfill arealO because of the debris that was buried'
there. For example, trash (glass, wood, paper, and cardboard),
steel drums, concrete rubble, steel work, and artificial marble
have been buried in the north landfill. It is also not very
feasible to treat the contaminated ,soils under the'CIBA-GEIGY
plant since this would require'~heshut down and removal Of the'
existing facility, and there is little vaiue in tearing down the
CIBA-GEIGY plant in order to stabilize the soil underneath the
plant since the north landfill and the CIBA-GEIGY plant are one
large contiguous area of'contamination. In light of these Site-
specific conditions, EPA has determined that for both current and
potential future conditions, engineering and institutional
controls at the north landfill and the CIBA~GEIGY plant will
provide the necessary protection of human health and the
environment.. ' ,
, '
. '. . .
, , '
, 'The remedial alternatives in this ROD address contaminated
soils, sediments, surface water, and ground water at the'Site.
The remedial action objectives are the following:
9stabilization (the use of a binding agent to reduce the
mobility of contaminants) is the best demonstrated available
technology (and the only available technology for a site of this
size) for the treatment of metals. It should be noted, however,
that even this technology will not destroy the waste (because,
much of the'waste consists of elemental metals) but only greatly
limit the ability for the contaminants to migrate.
l~e remediation of the north drainage way is included with
the remediation of the north landfill since the north drainage
way cuts through the landfill and then runs along the base of it.
13
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1.
Prevent exposure to the contaminated ground water (see
detailed discussion under "Ground Water" in the
"Alternatives Analyzed" section as to why EPA is not
proposing to return the ground wate~ to its beneficial
use). .
2.
Prevent further migration of the contaminated ground
water.
Prevent exposure to contaminated soils.
Prevent exposure to contaminat~d sediments.
3.
4.
5.
Prevent further degradation of the environment caused.
..by the d~schargeof contaminated ground water to the
Christina River and to the wetlands adjacent to the ..
north and south landfills.
As discussed further in the next section, "Summary of Site
Risks," preventing exposure to contaminated ground water is
required to protect human health, preventing exposure to
contaminated soils is required to protect human health and the
environment, preventing exposure to contaminated sediments is
required to protect the environment, and preventing exposure to
highly contami~ated surface water. is necessary to protect the
environment. . ..
This ROD addresses all of the threats currently .known that
are posed by the contamination at this Site and is, at present,
the final response action planned for this site. This ROD
includes the final remedy for the threats posed by the heat
transfer fluid seeping into the Christina River that is being
addressed on an interim basis by a June 1993 removal action
order. .
Among the factors considered by EPA in the ROD is the fact.
that~e Du Pont Holly ~un plant and.the CIBA~GEIGY plant ~re
currently active manufacturing plants. If one or both of the
plants were to change materially their present operations, then
EPA would assess any proposed change in operation at the Site and
consider whether or not to take further response actions at the
site based. upon the proposed change. EPA will review the effect
that any proposed change in. plant operations might have upon the
remedy selected in this ROD.
Although this is the final remedy planned for this site,
changes. in conditions may lead to further. response actions. .
Other possible response actions include removal of the thorium
drums if unacceptable levels of soluble thorium are discovered,
further remediation of the wetlands and the river if long-term
monitoring shows that the remedy selected in this ROD is no
longer protective, further actions at the north landfill and the
14.
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CIBA~GEIGY and Du Pont Holly Run plant areas if there are changes
in available treatment technologies or changes in the on-going
operation$ of the chemical plants.
SUMMARY OP SZTE RZSKS
Du Pont prepared a baseline risk assessment to assess the
potential human health and environmental. impacts that may result
from exposure to contaminants associated with the Site in the
absence of active remediation. To determine whether there is an
actual or. a potential impact at the site, a complete exposure
pathway must be established. A complete exposure pathway
consists of the following components:
1.
A source or. mechanism for 'contaminants to 'be released
to the environment.
2.
A medium through which contaminants may be transported
such as water, soil, sediment, or air.
3.
A point of actual or potential exposure or contact for
humans or environmental receptors.
. A ro:ute or mechanism such as ingestion., inhalation, or
dermal contact for exposure at. the contact. point. .
Current and potential future exposure scenarios were
evaluated for complete ~xposure pathways which met the above
criteria.
4.
The Risk Assessment is a two-volume set of documents
comprised of the Human Health Evaluation (HHE) and the
Environmental Evaluation (EE). The HHE assesses the risks
associated with the site to people.' The EE assesses risks
associated with. the site to plants and animals. EPA has
determined. that actual. or threatened releases of hazardous
substances from this Site, if not addressed by implementing the'
response action selected in this ROD, may present an imminent and
substantial endangerment to human health and the environment.
HUMAN HEALTH EVALUATION
The HHE is divided into two categories of impacts:
carcinogenic and non-carcinogeni~ or systemic. Many contaminants
c~~se.~oth types of impacts. Remedial action is generally
warranted" when the calculated carcinogenic' risk level exceeds
1X10-4 (meaning that one additional person out of 10,000 is at
risk of developing cancer caused by a lifetime of exposure to
contaminant~ at the Site) under current or future conditions for
any of the evaluated exposure scenarios. Remedial action is also
generally warranted if the calculated non-carcinogenic Hazard
15
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Indexll exceeds 1.0 under current or future conditions for any
of the evaluated exposure scenarios. .
The risks were calculated by first determining ~ll.the
various ways in which humans come in contact with contaminants at
the site currently or potentially in the future. At the
ballpark, children can come into contact with contaminated soils
during recreational activities. At the north landfill, a
maintenance worker can come into contact with surface soils while.
cutting grass. '
At the south landfill, there are several different possible
ways for humans to come into. contact with contaminants. First,
an owner-employed maintenance worker may accompany a .New Castle
County maintenance worker inspecting the sanitary sewer force.
. main that runs through the south landfill. This same oWner-
employed maintenance worker may have other, although infrequent
activities, at the south landfill. Although there are no
currently planned construction activities at the south landfill,
it was assumed that in the future some type of construction may
take place that would involve earth-moving activities. The south
landfill is also acces$ible to trespassers. who are assumed to be
adults and adolescents (ages 14-23 years, inclusive). It was
assumed that humans would not come into contact with the
sediments in the south wetlands.
. . .
In the .Christina River, exposure .to contaminated w~ter (both
the river water itself and leachate seeps along the river bank)
can and/or does take place during recreational activities
including fishing, boating, and swimming. In the.Du Pont Holly
Run and CIBA-GEIGY plant areas exposure to contaminated soils can
and/or does take place during maintenance activities such as
cutting grass and construction activities which involve soil
excavation. . .
. The ground water poses a potential future risk. No one is
. currently consuming ground water contaminated. by the Site to
levels above MCLs or non-zero MCLGs. However, in the future.the
plume of c~ntamination may migrate to nearby private drinking.
water wells or a land owner adjacent to the south landfill could
l1The potential for health effects resulting from exposure
to non-carcinogenic compounds is estimated by comparing an
estimated dose to an acceptable'level, or reference dose. If.
this ratio. exceeds 1.0, there is a .potential. health risk. .
associated with exposure to that chemical.. The ratios can be
added for exposures to multiple contaminants. The sum, known as
the Hazard Index, is not a mathematical prediction of the
severity of toxic effects, but rather a numerical indicator of
the transition from acceptable to unacceptable levels.
16
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drill a new well into the contaminated plume.
in either the Columbia or Potomac aquifers.
Since the site has been an operating industrial facility
since at least 1902; since it is surrounded by two major highways
(Interstate 95 and Delaware 141), a salvage yard, another
Superfund site (Koppers), and a light industrial area; since it
is separated from th~ nearest residential area by the northeast
corridor line of Amtrak; and since potentially responsible
parties currently own a vast majority of the contaminated areas;
there was no future residential land use assumed. Therefore, .
there is no exposure scenario involving residents being exposed
to soils at the landfills or the chemical plants or ground water
directly underneath these areas. .
This could happen
Different routes for contaminants to enter the body (i.e~,
ingestion, inhalation, or dermal contact) were taken into account
in the risk calculations as appropriate for each exposure
scenario (see Table 8). Table 9 contains the major assumptions
about exposure frequency and duration for each of the exposure
scenar ios . .
. The second step in the risk calculations involves .
determining which contaminants are contributing significantly to
the tota~ risk and should be labeled as contaminants of concern. .
. .Using p.rocedures outline<;l in EPA' s "Risk Assessment. Guida,nce .for.
Superfund" (EPA/540/1-89/002), a list of contaminants of concern
was developed for each media in each are.a related to an exposure
pathway. .
Another part of a risk calculation is the cancer potency
factors (CPFs)12 or reference doses (RfDs) 13. Used both in
12CPFS, also known as slope factors, have been developed by
EPA's carcinog~nic Assessment Group for estim~ting excess.
lifetime. cancer risks associated with exposure to potentially.
carcinogenic chemicals. CPFs, which are expressed in units of
(mg/kg/day)-l, are derived from the results of human
epidemiological studies or chronic animal bioassays to which
animal-to-human extrapolation and uncertainty factors have been
applied. .
13An RfD is a toxicity value used to estimate the potential
for adverse non-carcinogenic health effects. The model to
determine. RfDs from the. dose-response assessment assumes that
there is a concentration for non-carcinogens below which there is
little potential for adverse health effects over a lifetime of
exposure. The RfD is designed to represent this threshold level.
The RfD is calculated from the highest chronic exposure level
that did not cause adverse effects (the no-observed-adverse-
17
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the screening steps and the actual risk calculations, CPFs and
RfDs are estimates of the degree of a contaminant's toxicity.
The actual or potential risk is.c~lculated by multiplying.
the CPFs and the RfDs by an intake factor (calculated from all of
the exposure assumptions) and by the concentration of each
. contaminant of concern for each exposure pathway.14 .
Table 10 identifies both the carcinogenic and non-
carcinogenic risks associated with various ~reas of the Site.
Note in Table 10 that the.Hazard Index was calculated with and
without taking lead into account because, due to the biological
complexity of lead exposure and toxicity, EPA does not currently
have an approved reference 'dose for lead. The reference dose is
a major component .in the calculation of the Hazard Index. .
Therefore~ EPA determined at this. site a.clean-up criteria for
lead of 500 ppm in residential settings and 1000 ppm in
.industrial settings.1S See Figure 18 for surficial lead
effect.level, or NOAEL) in animals. The NOAEL. is divided by a
factor to account for any uncertainty such as using data on
animals to predict effects on humans and an allowance. for
sensitive individuals. Uncertainty factors range from 1 to
10,000, based on the confidence level associated with the data.
The resulting RfD (mg/kg-body weight/day) is used to. quantify the
risk. .. . . . . . . .
14The concentration value used here is the 95% upper
confidence limit (UCL) for the arithmetic mean of the levels of
each contaminant found in the samples taken from the appropriate
.media in each area. This particular concentration value is a
statistical estimate of the highest average concentration
predicted to occur in 95 out of 100 sets of samples. The use of
the 95% UCL produces an estimate of.risks for the "Reasonable
. Maximum Exposure" (RME) scenario. The 95% UCL is used to account
. for .the fact that the.actual'nWnber of samples is relatively.
. small to accurately.predict the average. . This method of .
calculating risks is designed to provide a.conservative estimate
and makes. the underestimation of actual risks highly unlikely.
. 1sEPA'S Office of Solid Wa~te and Emergency Response (OSWER)
Directive #9355.4-02 (dated 917/89) set forth an interim soil
clean-up level for total lead for direct contact in residential
settings at 500 ppm to 1000 ppm. site-specific conditions may
warrant the use of soil clean-up levels below the 500 ppm level
.or somewhat above the 1000 ppm.lev~l. EP~ ~egion 3. Superfund
Program practice is to use 500 ppm for residential settings
unless there is evidence that 500 ppm is not protective in which
case an uptake/biokinetic model that takes into account site-
specific conditions may be used to determine a lead .clean-up
level. Since at this Site there are no true residential exposure
18
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contamination levels. For many exposure scenarios, these
criteria can be used in place of a reference dose in calculating
the contribution of lead to the Hazard Index. For other
scen~rios, such as the recreational activity scenarios in the
Christina River, this method overstates lead's contribution to
the Hazard Index. The lead levels in the river are so low that
EPA has determined they do not pose any significant health risk
for someone undertaking recreational activities in the river and,
therefore, were not included in the. Hazard Index calculations for
the recreational exposure scenarios in the Christina River.
The contaminants which contribute most to the human health
risk at the site are lead, vinyl chloride, arsenic, .
tetrachloroethene, trichloroethene, cobalt, zinc, cadmium, and.
manganese. . .,.,. .
Receptors for which risks are unacceptable include the
future construction worker and the adolescent trespasser at the
south landfill area; the maintenance worker for the north
landfill area.and the Holly Run plant; the maintenance and future
construction worker at the CIBA-GEIGY plant; and the resident, in
the future, drinkin~ contaminated ground water just off the south
landfill property.1
. The RIfFS al!"o found no evidence that site-related
contaminants result in unacceptable health risks fr~m.eating fish
in the Christina River because there were no data that showed
elevated levels of metals in fish typically consumed by humans
caught near the Site relative to those caught upstream and out of
the influence of the Site.
ENVIRONMENTAL EVALUATION
The Environmental Evaluation (EE) focused on potential
impacts to aquatic life in the wetlands and the river. However,
it also examined potential impacts ~o terrest~ial animals and'
plantlife~ Sediment chemistry, benthic (mac+oinvertebrates
settings (recreation~l. activitie~ at the ball 'park and
trespassing at the south landfill have only minimal exposure
times to elevated levels of lead), EPA believes that 500 ppm is
protective. EPA Region 3 Superfund Program practice is to use
1000 ppm for an industrial exposure scenario unless there is
evidence that 1000 ppm is not protective. EPA has determined
that a soil clean-up level of 1000 ppm for lead based on a direct
contact industrial exposure scenario is appropriate' for this'
Site.
16Although not reflected in the risk calculation,.
remediation of a lead hotspot is required at the ballpark because
of lead levels above 500 ppm.
19
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living in and on the sediments) studies, and sediment toxicity
were the main indicators of aquatic impacts. Plant chemistry,
litera~ure research, and field observations were use~ to
determine impacts to plant life. ,Estimates of impacts' to .
terrestrial animals were calculated in a way similar to that used
to calculate the non-carcinogenic risks to humans.
Figures 19 and 20 show some of the results of the biological
tests and the ratio of the normalized metals concentrations at
each station to those at the reference sta~ion (the enrichment
factor). Figure 19 contains test results for the wetland areas,
and Figure 20 contains test results for the river. The figUres
also include results of the sediment elutriate toxicity tests
measuring percent survival of water fleas (Ceriodaphnia) and
fathead minnows (Pimephales'promelas); solid phase toxicity tests
measuring percent survival' of Chironomus tentans and Hyallela .
aztecai the density (number of organisms per unit area) and
diversity (number of different types of organisms and relative
abundance of each type) measurements of benthic organisms at
different sampling stations as well as the relative frequency of
pollution tolerant. benthic organisms to the total population.
Some of the other tests that are available in the RI include
Targ~t Analyte List (TAL) metals analyses data for the sedimentsf
results of the sedi~ent elutriate toxicity tests reproduction
rate of water flea~ (Ceriodaphnia) and ~he growth rate of fathead
minnows (Pimephales p~omelas), solid phase toxicity ~ests . .
measuring the growth' rate of'Chironomus tentans and Hyallela'
azteca.
Areas that were examined for potential environmental impacts
included tidal wetlands adjacent to the north landfill, wetlands
in a drainage way that cuts through the north landfill, non-tidal
wetlands adjacent to the south landfill, a pond adjacent to the
south landfill, upland areas (much of which. is on top of the two
landfills), and the Christina River (see Figure 21).
. 'rhe' tidal wetland area. adjacent to the west end. of the north .
landfill (excluding the lower part of the 'north drainage way) is
approximately seven acres in size. contamination was detected at .
the two sampling stations, with lead and zinc being detected as
high as 10 times (on a normalized-to-grain size basis) the Site
reference station (station RS15 located four to five miles
upstream in the Christina River). The location of these two
stations indicates that the contamination is present ~oughout
the north wetland area. Contamination is most likely widespread
due to the incoming tide carrying contaminated sediment and water
throughoutth~s area.. Sediment toxicity tests and benthic
studies were done to determine impacts caused by the
contamination. Slight impacts could be determined from one of
the toxicity tests and from the high abundance of pollution
tolerant benthos species. Most of the toxicity test results did
not indicate any significant levels of toxicity. EPA has
20
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determined that currently no remedial action in the north
wetlands is warranted because measured impacts are slight and
preserving. or enhancing the existing viable wetland habitat is
preferable to stripping the wetland sediments and creating a new
wetland.l7 .
The worst toxicity results at the site were for samples
collected from the drainage way that crosses the north landfill
and then wraps around the western base of.the landfill and
discharges to the Christina River. The mid- and. lower sections
of the drainage way (where it goes over the edge and potentially
cuts into the landfill itself) show signs of extreme impact.
Lead levels are extremely high (27,000 ppm maximum). Several of
the sediment toxicity tests had no survivors, and the ben~hic
. density (number of macroinvertebratesper unit area) was also
very depressed (one sampling station in the lower section had a
benthic density less than 0.5% of that found in the upper portion
of the drainage way). Remediation is required for the mid- and
lower sections of the north drainage way in order to protect the
environment. The upper end of the drainage way did not exhibit
any measurable environmental impacts but did have slightly. .
elevated levels of cadmium; copper,. lead, and zinc. EPA has
determined that remediation for the mid- and lower sections of
the drainage way is necessary 'because of extreme environmental
impact.
. . .
The no~~tidalwetlands area adjacent to the southlandfili
is 18 acres in size. This area is not a tidal wetland because a
tide gate prevents river water' from entering the wetland at high
tide. Very high levels of barium (34,700 ppm), lead (5,550 ppm),
and zinc (12,800 ppm) have been found in sediments. In one area,
the benthic density is depressed, there is a high abundance of
pollution tolerant species, and the survival rate of Hyallela
azteca was low. EPA has determined that remediation is necessary
in part of the south wetlands due to unacceptable impacts to
environmental receptors. T~e exact areal extent requiring
remediation " is unknown at this time.
. .
The pond adj.acent to the south landfill has barium levels as
high as 60 times the reference station (on a normalized basis)
and lead levels as high as 27 times the reference station (also
on a normalized basis) showing that the pond has been affected by
site-related activities. The toxicity tests and benthic studies
indicated only slight environmental impacts.. Field observations
17Although data collected to. date do not show a need for'
remediating the north wetlands, data collected during the
remedial design may show areas of the north wetland to be above
the clean-up criteria and, therefore, that require remediation.
See the discussion below in this section regarding the
determination of clean-up criteria.
.21
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show this area to be ,a viable habitat for turtles and muskrats.
Vegetation is abundant and representative of a relatively healthy
ecosystem. Plant tissue analysis does show chemical uptake and
there is concern about the potential impacts this may have to
terrestrial receptors. Risk assessment calculations similar to
that for determining the Hazard Index for humans show there is a
potential impact to animals who consume plants from this area.
Because the toxicity tests and the benthic studies did not
indicate severe environmental impacts, EPA believes that
remediation is not warranted for the south pond. However,
monitoring should take place to make sure that the metals do not
~come bioavailable to aquatic or terrestrial life.
About 30 acres of the Site is ,considered upland areas (such
as the north a~d south landfills) which provide habitat for
aniInals~. Signs of, or actual sightings of deer,' beaver, fox, and
mice have occurred. Estimates of risks were made due to
ingestion of contaminated soils using the deer mouse as a
representative species. EPA has determined that remediation of
the upland areas is not warranted due to impacts to terrestrial
. life except for several areas of potential concern. One is a
barren area at the southwest corner of the north landfill. High
levels of metals (arsenic, barium, cadmium, copper, lead, nickel,
and zinc) exist in the surface soil. , Levels of zinc are high
enough to likely produce toxic effects to the plant life thereby
preventing vegetation 'growth.. Although th~ lack of vegetation'
may not attract 'terrestrial life for feeding, bare spots are
known to be used for daily habits of many ecological receptors
(i.e., birds). EPA has determined that this barren area needs
covering to prevent potential exposure to ecological receptors.
Also, there are several small (less than one cubic yard) piles of
Lithopone waste in the upland area to the west of the north
landfill that EPA has determined require removal.
The Christina River flows through the site and between the
north and south landfills. Chemical analyses of the river
sediments show ,high levels of lleavy metals associated with the,
Lithopone process. . Elevated levels of metals have been detected
from the north drainage way to several miles ,downstream. All up-
gradient sampling appear.s to have been done far enough up-river
from the north landfill to'be out of any influence of the Site
(the Site is considered to be any place that Site-related
contamination has come to be located). However, since the
nearest up-river sampling location was over a mile and a half
from the north landfill, the potential exists for contamination
to have migrated up-river from the site due to tidal influences
and been deposited between the north landfill and the~p-river
sampling stations. Surficial sediments, which are contaminated
by ground water, do have high levels of contamination that tests
indicate are toxic in some areas (see data for RSll and RS12 in
Figure 20). EPA has determined that these contaminated sediments
need to be remediated. The areal extent of this impact is not
22
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known at this time. However, impacts appear to be highest near
the north river bank in the area of the landfills and the CIBA-
GEIGY .plant.
During the RI, the Site reference station for both the
wetlands and the river was RSlS which was about S miles upstream
on the Christina River from the north drainage way. While
apparently unaffecteq by the Site itself, data from station RS1S
suggest that RSlS is influenced by some other site and is .
therefore not representative of pristine background conditions in
the river. This fact should be taken into account when comparing
data from site sampling stations to the reference station to
evaluate the presence and extent of any degradation. Efforts
should be made during the remedial design and the remedial action
to. find a'reference station, preferably near the Site, which is
representative of'background conditions (preferably a separate.
station for wetlands and for the river). Also, through
examination of aquatic conditions at other areas of northern
Delaware, a list of conditions should be developed that would be
expected in a pristine environment (i.e., the ideal reference
station). . .
As described above, EPA has determined that review of all
available data (especially that of the toxicity tests, the
benthic ~tudies, and the chemistry tests) ~ndicates that several.
areas of the "'etlands and the river .warrant remediation..' Figure
22 generally outlines these areas. However, due to the broad
spacing of samples collected during the RI/FS, the exact areal
extent of remediation is currently unknown but will be determined
during the remedial design eRO) phase. Figure 23 shows the area
in which delineation of unacceptable impacts must be performed in
order to determine the exact areas requiring remediation.
In order to make the determination of the exact areal extent
of excavation practical, EPA has set site-specific clean-up
criteria. fOr thewetlan~s and the. river based on' all available
data with an emphasis'on the toxicity tests and the benthic
studies.1S The clean-up criteria correspond to the
concentration of contaminants found in areas which require.
remediation based on the results of the bioassessment.data.
During the remedial design, chemistry tests will have to be done
to delineate the exact areas which require remediation. Due to
the extreme variability that can. occur in sediment contaminant
levels due to grain size, it is best to normalize the contaminant
levels to grain size in order to compare different sampling
stations and sampling events. Therefore, the clean-up criteria
lSSee the "Memo To File" dated 7/9/93 titled "River &
Wetland Remediation Goals (Sediment Clean-up Criteria), Third and
Final Edition" attached to this ROD (see Attachment B).
23
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are stated as normalized (to grain size) .contaminant levels.
clean-up criteria are:
The
Lead
Cadmium
Zinc
1200 .
60
5600
ppm
ppm
ppm
Areas where anyone of the above normalized contaminant
criteria is exceeded will be remediated. However, one area where
EPA has determined that these criteria do not 'apply is the south
pond. Although the above criteria would trigger remediation of
the pond, the biological tests indicated no severe environmental
impacts in .the pond. For example, sampling station AS-01 in the
pond had the highest recorded benthic density recorded during the
RI and one of the most diverse benthic communi ties. . The . . .
'differe~ce in the enviropmental conditions .between the pond and
the marshy wetlands may be causing a difference in the
bioavailability of the contaminants. Due to the fact that 1) the
above criteria are not applicable to the south pond and 2) the
levels are relatively high compared to sediment contaminant
levels that generally have been found to be toxic at other
locations, a minimal amount of .further toxicity testing will be'
done during the remedial design to make sure that the levels are
protective. In each of the north wetlands, south wetlands, south
pond, and Christina River, a mini~al .number of Hyallela azteca
solid phase toxicity tests shall be performed in areas.wbere the
contaminant levels are below the Site-specific clean-up criteria
but above the "apparent effects.threshold" (AET) levels for
cadmium, lead, and zinc (9.6 ppm, 660 ppm, and 1600 ppm .
respectively on an absolute basis).19 EPA may' decide to reduce
the site-specific clean-up criteria based upon the results of the
toxicity tests although not to levels below the AET values
described above. Any reduction may be done across the Site 'as a
whole or independently for each area. The test in the south pond
would be evaluated to confirm whether or not the whole pond
should be remediated. No criteria will be setiorthe pond. It
should be noted that ariy sediment clean-up. criteria developed 'for
this Site are site-specific criteria to be used at this site
only. .
EPA has determined from the information collected during the
RI that actual or threatened releases of hazardous substances
from this site, if not addressed by implementing the response
action selected in this ROD, may present an imminent and
substantial endangerment to public health, welfare, or the
environment.
19The cost estimate for the ROD assumed four sampling
stations in each of the four areas with four replicates at each
sampling station. See the attached 7/9/93 "Memo to File" for a
detailed discussion (see Attachment B).
24
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SUMMARY OP AREAS RBQUIRING REMEDIATION
In summary, based on the potential impacts to human health
and the environment, EPA has determined that the 'following areas
of the Site warrant remediation:
1. Ballpark: The east entrance to the 'ballpark near the
end of Ayre Street has surface soils ,above EPA's clean-up
criteria of 500 ppm that create ,an unacceptable risk to hUman'
health. '
2. North landfill including the drainage way: This area
continually releases contaminants to the ground water in the fill
and/or Columbia aquifers which affects shallow ground water in,
the direction of migratic;m and ground-water discharge areas. ',One
of the areas affected by the discharge is the Christina River
which has AWQC or SWQS exceedances and some sediments which
exhibit unacceptable environmental impacts. Another area
affected by the discharge is the north drainage way, parts of
which exhibit extreme impacts to ecological receptors.
3. South landfill: This area continually releases
contaminants to the ground water in the fill zone and/or Columbia
aquifers which affects shallow ground water in the ,direction of
,migration and ground-water discharge areas. The twodi~c~arge
points are the river and the sout~wetlands which have AWQC or
SWQS exceedances and some sediments' which exhibit unacceptable
environmental impacts. Future subsurface maintenance or
construction activities would result in unacc~ptable risks to
humans.
4. South wetlands: 'Part of this area exhibits unacceptable
environmental impacts including low benthic, density and poor
benthic diversity (i.e., a high percentage of pollution tolerant
spe~ies). '
5.' Christ'ina River:' Some of
exhibit ~nacceptable environmental
severai site~related contaminants,
zinc, are exceeded in the vicinity
the sediments in the river
impacts. AWQC or SWQS for
including cadmium, lead, and
of the Site.
6. ClBA-GEIGY plant and a small portion of the Du Pont
Holly Run plant: Exposure to surface and subsurface soils cause
unacceptable risks to humans. This area continually releases
contaminants to the ground water in the fill zone and/or Columbia
aquifers which affects shallow ground water in the direction of
migration, groundwater in the Potomac aquifer where the ,
hydraulic gradient is downward, and ground-water discharge areas.
One of the discharge points that is affected is the river which
has AWQC or SWQS exceedances and some sediments which exhibit
unacceptable environmental impacts.
25
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7. Ground water: The ground water in the fill zone and
both the Columbia and the Potomac aquifers at the Site is not
safe to drink. Levels of contaminants such as tetrachloroQthene,
trichloroethene, cadmium, barium, and lead exceed their MCLs or
non-zero MCLGs in the Columbia 'aquifer. Arsenic, cobalt,
manganese, and zinc also contribute to unacceptable human health
risks in the Columbia aquifer. Levels of contaminants such as
tetrachloroethene, cadmium, lead, and trichloroethene exceed
their MCLs or non-zero MCLGs in the Potomac aquifers. Cobalt.
also contributes to unacceptable risks.to humans. No one is
currently consuming any ground water that has MCL or non-zero
MCLG exceedances caused by the Site.
DESCR:IPTXON OFALTBRNATXVES' AND SUKMARY OF THE COMPAItATXVE
. ANALYSIS OF' ALTERNATIVES
The following alternatives were evaluated in detail in the
feasibility study to determine which would be the most effective
in achieving the goals of CERCLA, and in par~icular, achieving
the remedial action objectives for the Site. The ,detailed
analysis of remedial alternatives for the areas of the site are
briefly described below. As required by the NCP, EPA used nine
criteria to evaluate alternatives. These criteria are summarized
in Table 11. The first two criteria (overall protection of. human
health. and the environment, compliance with applicable. or . . '.
relevant and appropriate requirements (ARARs) ) ,are threshold
criteria. The selected remedy must meet these threshold criteria
(except when an ARAR waiver is invoked). The next five criteria
(long-term effectiveness and permanence; reduction of toxicity,
mobility, or volume through treatmenti short-term effectiveness;
implementabilitYi and cost) are the primary balancing criteria.
The remaining two criteria (state and community acceptance) are
referred to as modifying criteria.' .
Alternative #1 in e~ch of the sections below is, the ."no
~ctiop" alternative which, although pot' listed in eachsec~ion,
was' evaluated for each area as required under section
JOO.4JO(e)(6) of the NCP. This section of the NCP requires EPA
to evaluate the "no action" alternative at every site to .
establish a baseline for comparison to other alternatives: Under
the "no action" alternative, no action would be taken to address
current or future exposure to contaminants remaining at the site.
No costs are associated with the "no action" alternative, and no
time is required for implementation. .
BALLPARK.
ALTERNATIVE #2: A small area, where Ayre street dead ends
at the ba~lpark (see Figures 2 and 24), with lead levels above
500 ppm would be excavated. Samples would be taken to delineate
the waste material and to determine if the soil to be excavated
26
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would be classified as a RCRA-hazardous waste. Soil would be
excavated to a depth and extent such that remaining lead levels
are below 500 ppm. Confirmatory samples will be taken before the
. area is backfilled and reseeded. The estimated amount of soil
requiring excavation is one cubic yard. Testing would be
performed to show whether or not the excavated soil is a RCRA-
hazardous waste (i.e., exceeds the Toxicity Characteristic
Leaching Procedure (TCLP) crit~ria). If the excavated soil is
not a RCRA-hazardous waste, then it would be disposed of in the
north landfill. If the excavated soil is a RCRA-hazardous waste,
it may be disposed of either in the north landfill or off-site at
an EPA-approved facility. in accordance with RCRA regulations. If
the excavated 'soil is a RCRA-hazardous waste and is disposed of
in the north landfill, .the soil would be treated by stabilization
until it is no. longer a RCRA-hazardous waste in order for the. .
disposal to be in compliance with RCRA land disposal regulations.
The present worth cost for this alternative is $10,000.
COMPARATIVE ANALYSIS OF ALTERNATIVES: Alternative #1 (no
action) does not protect human .health due to the unacceptable
levels of lead that would. be left in the ballpark. Alternative
#2 does provide overall protection to human health by preventing
exposure to soils containing high levels of lead. If TCLP tests
indicate that the soil is a RCRA-hazardous waste, RCRA land
,4isposalrequirements~ould be met through either on-site.
treatment (to 'achieve the 'requirements as ARARs) or off-site
treatment (to achieve the requirements asregulations)~
Alternative #2 provides excellent long-term effectiveness since
no soil will remain in the ballpark that could cause unacceptable
risks to humans. Reduction of mobility through treatment would
be met in Alternative #2 if the excavated soil is a RCRA- .
hazardous' waste. The short-term effectiveness and
implementability of Alternative #2 are also excellent since the
amount of soil to be excavated is very small.
. Alternative #2 has the support of the State. Written
comments r~ceived from the. public, including Du Pont, showed.
strong support to remove whatever contaminated soil is necessary
from the ballpark in an expeditious fashion. Upon evaluation of
the alternatives by the nine criteria, EPA has determined that
Alternative #2 is the selected remedy.
NORTH LANDI'ILL
ALTERNATIVE #2: A low-permeability. cover system (cap) would
be installed to reduce infiltration in order to minimize
continued ground water contamination from this area. For
example, the cover could be a geosynthetic clay liner. Figure 25
shows the approximate area to be covered and a potential cross
section of the cover system. The exact location of the thorium
drums would be determined, and a marker indicating their location
27
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would be installed on the surface of the landfill once the cap
was completed.
A low-permeability cover system would also be placed on the
river bank that extends from the crest of the bank down to the
river (referred to as the river bank cover system). An example
of a potential river bank cover system includes a,concrete
revetment mattress (a layer of ~oncrete c~st in place using
connected fabric bags as forms) placed on top of a geosynthetic
clay liner which is underlain by another geomembrane and
anchoring layers of concrete-filled fabric bags place~ on the
lower portion of the liner (see Figure 26). '
, ,
Several $mall (less than one cubic yard) piles of Lithopone
,waste in the upland area to the west' of 'the north landfill would"
be consolidated in the north 'landfill prior to capping. '
Part of the north drainage way would be covered by the cap.
The wetlands associated with the lower part of the north drainage
way would be remediated by removing the top one foot of
sediments. The excavated area would be backfilled with clean
fill and revegetated. The exact area requiring remediation would
be determined during remedial design by sampling sediments
throughout the north wetlands. The excavated sediments would be
stabilized and p~aced underneath the cap.20 The excavated
areaswbuld be restored as a wetland~ In order to compensate for
the wetlands lost due to capping (a small area on top of the'
landfill, the upper part of the drainage way" and any portions of
the covered river bank that are classified as wetlands),
approximately three quarters of an acre of upland area adjacent
to the north wetland (unless EPA determines during the remedial
design that the type of wetlands requires more than one-to-one
replacement) would be graded to ,establish wetla~d hydrology.
Then other measures would be taken to successfully establish the
wetland including planting a variety of grasses and hydrophytic
species common to the area.
, '
, ,
The lower section of the north drainage way and the north
wetlands will, undergo long-term monitoring to ensure that the
remedy is protective. Also as part of this alternative, long-
term monitoring of the north wetlands would take place to make
sure the remedy remains protective. The present worth cost of
this alternative is $3,500,000.
20RCRA land disposal regulations would be ARARs at this site
o'nly if placement (Le., disposal) occurs., For placement to '
occur, the sediments would have to fail the TCLP test and be
treated "ex-situ." LDRs would not be ARARs for any "in-situ"
treatment because no placement would occur since movement of
sediments from the north wetlands to the north landfill is
considered consolidation within an area of contamination.
28
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ALTERNATIVE #3: This alternative includes everything from
Alternative #2 plus the addition of a fill zone hydraulic barrier
system (a system of pumping we~ls that would prevent migration of
ground water past a line of recovery wells). The 'hydraulic .
barrier system would create a ground water divide that would
prevent ground water from the fill zone from discharging to the
river. The recovered ground water would be treated, with a
combination of air stripping to remove volatile organic compounds
(VOCs) and precipitation to remove heavy metals. If necessary to
comply with DNREC and EPA requirements and regulations, the off-
gas from the air stripper would be treated. The treated qround
water would be discharged to the Christina River in compliance
with the substantive requirements of a National Pollution
Discharge Elimination System (NPDES) permit. ,It is anticipated
'that the ground~water treatment sludges would be hazardous waste. .
. Since one of the 'original uses of the tetrachloroethylene in the
ground water was as a degreaser of magnesium in the production of
titanium metal, any treatment residues containing
tetrachloroethylene shall be considered F002 waste. Disposal of
any treatment sludges or other wastes would.be in accordance with
appropriate Federal and State regulations.. The present worth
cost of this alternative is $12,000,000.
,ALTERNATIVE #4: This alternative is the same as Alternative
#2 with ~he addition of a physical barrier wall (an actual wall
. that limits. mlgratic;m of ground water) .that would extend to the'
base of the Columbia aquifer (see Figure 27 for the' approximate'
wall location). If necessary, this wall would be part of a fully
circumscribing wall around the CIBA-GEIGY plant as discussed'
under the "CIBA-GEIGY and Du Pont Holly Run Plants" section
below. Different barrier wall technologies were evaluated in the
feasibility study, including deep soil mixing, sheet piles, and a
soil/bentonite slurry. Further evaluation will take place in the
remedial design. Use of geosynthetic membranes as a physical
barrier will also be evaluated in the remedial design. The wall
would limit to the maximum extent practicable contaminated ground'
water from the f~ll and ColUmbia .zonesfrom entering the'
Christina River. The wall will cause mounding of the ground
water to occur in the landfill. Extraction wells would be
installed to control the mounding effect. Ground-water treatment
would take place as described under Alternative #3. The present
worth cost of this alternative is $12,500,000.
ALTERNATIVE #5: This alternative is the. same as
Alternative #4 except this alternative leaves the natural
vegetation on the river bank instead of instal~ing the river
cover system. The present'worth cost. of this alternative is
$12,100,000.
COMPARATIVE ANALYSIS OF ALTERNATIVES: Alternative #1 (no
action) would not provide overall protection of the environment
since it would leave the area of worst environmental impact, the
bank
29
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north drainage way, unremediated. Each of the other alternatives
does remediate the north drainage way by replacing the top one
foot o~ sediments where biota (small aquatic organisms) live,
thereby contributing to the protection of the environment.
Alternatives #2, #3, #4, and #5 provide for capping the landfill
which will greatly decrease, but not eliminate, this area's
contribution to an overall site ground water problem in which
MCLs are exceeded.21 However, in order to provide overall
protection of human health and the 'environment and long-term
effectiveness, the discharge of ground water from the fill zone
and the Columbia aquifer must be limited to the maximum extent
practicable. Discharge of the ground water ,will continually
contaminate sediments and contribute to AWQC or SWQS exceedances
in both adjacent wetlands and the Christina River. This is
especially i~porta~t of the fill 'zo~e ground ,water that
discharges on the west side of the landfill into the drainage way'
where there is only very limited surface water to dilute the
leachate. Alternatives #4 and #5, which include a provision for
a physical barrier wall which extends to the base of the Columbia
aquifer, limits the migration of contaminated ground water from
this area to the maximum extent practicable and, therefore, meet
the threshold criteria of overall protection of human health and
the environment. Alternatives #2 and #3 do not adequately limit
the discharge of ground water to the adjacent wetlands and the
river (since they,do not control the discharge of the Columbia
aquifer) 'and therefore do not meet the overall prqtection of' '
human health and the environment threshold criteria. '
Although the river bank cover system in Alternatives #2, #3,
and #4 would decrease the ability of contaminants in the landfill
21RCRA subtitle C landfill closure regulations are not
considered ARARs for the north landfill. Since the north
landfill was closed prior to the enactment of RCRA, RCRA landfill'
, closurerequlations are not, applicable. The closure regulations
are relevant since in all likeliho,od s~me of the waste in this
, landfill would'fail the TCLP test. However~ the closure
regulations are not approp~iate. The main technical parts of the
closure regulations are that the cap must be less permeable than
the bottom liner to prevent a bathtub effect and that the ground
water must be monitored to determine if any contamination is
migrating from the landfill. Since the landfill has no bottom
liner, meeting the closure regulations would only require a
slightly impermeable cap. EPA has determined that this is not
protective enough of the environment.. As for the ground-water
monitoring; since'the north landfill is adjacent to a river,
since the Columbia aquifer is already co~taminated, and since
active ground-water remediation will not take place in this area,
the monitoring requirements as described in 40 CFR 264.98 are not
appropriate, and therefore, the closure regulations are not
appropriate.
30
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berm from leaching into the river, the natural river bank
vegetation (as part of Alternative #5) offers better slope
stability. The natural vegetation also provides feeding,
roosting, breeding, and cove~ habitat for birds; provides
spawning, nursery, feeding, and cover habitat for fish; and
provides benefits for the river such as cooling. The benefits to
the environment of the natural river bank vegetation are greater
than the benefits of the river bank cover system when combined
. with the physical ba~rier wall ,in Alternative #4. Therefore,
Alternative #5 offers a greater degree of overall protection of
human health and the environment as compared to Alternative #4~
The ground-water treatment system associated with the
installation of the physical barrier wall in Alternatives #4 and
#5 would meet all air, 'water, and RCRA ARARs. ,The estimated'
withdrawal rate ranges from 25,000 to 200,000 gallons per day
(from north landfill and the CIBA-GEIGY plant area cOmbined).
Unless the remedial design ascertains that the withdrawal rate
will not exceed 50,000 gallons per day, Delaware River Basin
Commission (DRBC) Ground Water Protection Area Regulations would,
be considered,ARARs (although they would no longer be applicable
if the' actual withdrawal rate was below 50,000 gallons per day).
None of th~ alternatives would bring the north wetlands into
compliance wit~ the state of Delaw~re's Surface Water Quality
, Standards (SWQSs)" which are ARARs fQr this are~, .due to upstream
'sources of zinc '(entering 'the wetland with the tide) and possible
background sources of iron and aluminum. Therefore, by issuing
this ROD, EPA is invoking the "technical impracticability" waiver
as outlined in section 300.430(f) (l)(ii) (C)(3) of the NCP because
it is not possible' for remedial actions in the north landfill
(wetlands area) to meet the SWQSs. '
Alternatives #4 and #5 offer the greatest degree of long-
term effectiveness since they limit to the maximum extent
practicable the discharge of contaminated ground water whic~
'couid reco~taminate the remediatedportions of ,the wetlands and
the river. Alternatives #2, #3, #4, and #5 have potential for
short-term impacts because they require locating the thorium ,
drums and drilling into the landfill. A health and safety plan
would be developed during the remedial design to protect the
workers (including from radiological hazards). Alternatives #4
and #5 would have moderate short-term impacts due to temporary
destruction of wetlands, potential construction worker exposure
to waste in the north landfill, and sediment transport to the
river due to erosion. Erosion controls would have to be
implementeq to reduce sediment transport. Each of the
alternatives would require on-going maintenance since the waste
is not being removed or treated to levels that allow unrestricted
use.
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The overall present worth costs of Alternatives 15 are less
than those of Alternative #4. The present worth costs for both
of these alternatives are significantly higher than the present
worth costs for Alternative #2, due ~argely to the costs
associated with treating the contaminated ground water prior to .
discharge. However, of the alternatives that meet the threshold
criteria of overall protection of human health and the
environment and achieves ARARs (AI ternati ves #4 and 15,) "
Alternative #5 is the most .cost-effective.
Overall, the state supports the select{on of Alternative #5
except that the state does not agree with determination of the
Site-specific clean-up criteria for the sediments. The state'
. strongly believes that a substantial amount of sediment toxicity
tests must be performed in the north wetlands to determine which
areas must be remediated' (see Att~chment 'A.for details on the
state's position).
At the public meeting there was general support of the
preferred alternative (which 'is practically the same as the
selected remedy without the river bank cover system). Written
comments from the public, including Du Pont, supported capping
the north landfill and remediating the north drainage way, but
did not support the potential remediation of the north wetlands
or the need to control the discharge of the ground water into the
river. . However, only areas of the north wetlands th~texceed the
Site-specific sediment' clean-up criteria will' be remediated. The
two sampling stations in the north wetlands in the RI did not.
show exceedances ~f the site-specific sediment clean-up criteria.
Also, as discussed above, EPA has determined that controlling the
discharge of the ground water into the river is necessary to
,protect the environment and that the physical barrier wall that
is discussed in Alternative #4 is the most effective means of
limiting continued migration of the contaminated ground water in
the fill zone and the Columbia aquifer to the Christina River and
, the north drainage way. Therefore, upon evaluation of the
'alternatives by the nine criteria; EPA has determined that
. Alternative #5 is the selected remedy~ .'
SOUTH LANDPILL
ALTERNATIVE 12: This alternative would involve
institutional controls, access road improvements on the berm in
the south wetlands, excavation and backfilling of the portion of
the landfill underneath and to the east of Basin Road (i.e., all
of the landfill currently on Delaware property) with
'consolidation in the. rest of the landfill, and installation of a
low-permeability cover over the portion of the landfill' on
Du Pont property (see Figure 28). Also, in order to provide
better Site security to control trespassing, additional fencing
and a barrier of plants (perhaps thorny plants) would be
installed around the entire south landfill area including the
32
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landfill and the adjacent wetland area. The institutional
controls would include a notification in the deed regarding past
land use, .and restrictions on future land use. Access road
improvements would involve regrading the southern berm,
installing erosion control matting, adding crushed stone on top
of the berm and installing a culvert through the existing breach.
The low-permeability cover would be of the same construction as
on the north landfill. The present worth cost of this
alternative is $7,000,000.
ALTERNATIVE #3: This alternative is the same as Alternative
#2 with the addition of a physical barrier wall that extends to
the base of the Columbia aquifer (technology to be chosen during
remedial design from deep soil mixing, soil/bentonite slurry,
sheet piles, or geosynthetic me1i1brane) along the river and" , .
ground-water recovery and treatment similar to that described. in
Alternative #2 for the north landfill. The present worth cost of
this alternative is $16,000,000.
ALTERNATIVE #4: This alternative is the same as Alternative
#2 except that the waste in the south landfill will be stabilized
in-situ prior to capping and the berm would be removed in order
to mitigate the impacts that ~he increased volume of the landfill
has on the floodplain. By stabilizing the waste, the ability of
the .metals to be leached bY the ground water will be greatly .
reduced.22 . ~rrently the water table is in the waste material.
and even 'after capping, about two feet of waste will still be in
the water table. Fo~ the purposes of the feasibility study,
Portland Cement Type I was used as the stabilization agent
although a design optimization study would have to be done to
determine the appropriate agent to be used during the remedial
action. Stabilization , would continue until the waste passed the
TCLP test and passed a TCLP-like test using background Site
ground water instead of acetic acid to ,leach the 'contaminants.
The criteria for passing this second test would be MCLs. The
present worth, cost. of this alternative is $15,300,000.
ALTERNATIVE #5: This alternative is the same. as Alternative
#4 except instead of a double layer low-permeability cap, a RCRA
Subtitle D cap (containing a minimum of 18" of 10-5 em/s
permeability soil on top or its equivalent) would be constructed
on top of the south landfill. The present worth cost of this
alternative is $14,300,000.
COMPARATIVE ANALYSIS OF ALTERNATIVES: The "no action"
alternative does not meet the threshold criteria of overall
protection of the environment because of continued contaminant
release to the ground water which discharges to the adjacent
22since no placement would occur, RCRA land disposal
regulations would not be triggered.
. 33
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wetlands and contaminates the sediments and the surface water.
Alternatives #2, #3, #4, and #5 call for capping the landfill
which would significantly reduce the release of contaminants to
'the ground water thereby protecting the wetlands and the river
and contributing to a reduction in ground-water contaminant
levels (which exceed MCLs) and to a reduction in surface water
contaminant levels (which exceed AWQCs in the south wetlands. and
the river). Also, by consolidating the landfill, all of the
landfill could be capped, and potential worker exposure during
any future subsurface work along Basin Road would be eliminated.
Currently, much of the waste in the south landfill is below
. the water table. Capping the landfill would reduce the ground-
water mound, but approximately two .feet of waste would still be
in the water table even after:the mound dissipates. By
stabilizing the waste before it is capped (as called for in
Alternatives #4 and #5), the amount the of contaminants that
could be leached out by natural ground-water flow would be
limited to the maximum extent practicable, thereby contributing
to the protection ~f the ground water and the surface water.23
Most of the major ARARs for this part of the site are
related to the protection of wetlands with the exception of RCRA
Subtitle D closure requirements and Delaware Regulations
Governing Solid. Waste (see Table 12). Alternatives #2, #3, #4,
and #5 all meet. their. respective. ~s. Care. would bet~en. . "
during the design and construction to prevent any adverse' affects
in the south wetlands and the Christina River. Any wetlands that
would be destroyed during remedial action would be replaced on a
one-to-one area ratio.
RCRA Subtitle C landfill regulations .(in particular those
related to closure) are not ARARs for the south landfill.
Although there is currently waste material in the south landfill
that could be classified as RCRA-hazardous waste, disposal
occurred before 1980 so these regulations are not applicable.
These regulations would. be relevant for .Alternati~es. #2 and. #3 .
23Although in wastes with a large number of metal
contaminants, stabilization has been shown in some studies to
cause the leachability of some contaminants to increase while
decreasing others, stabilization has been determined by EPA to be
the best demonstrated available technoloqy(BDAT) for soils and
sludges with heavy metal contamination. A design optimization
study would have to be done during remedial design to determine
the proper type and amount of stabilization agent." It. should.
also be noted that stabilization decreases mobility by not only
decreasing the leachability, but also greatly decreasing the
permeability of the waste and therefore reducing the ability of
the leaching agent (in this case ground water or infiltrating
rain water) from coming into contact with the waste.
34
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since the waste being capped would be a RCRA-hazardous waste.
However, for Alternatives #2 and #3, they are not appropriate
because they are not well suited for this area. One of the major
closure requirements is for a cap to be installed that is less,
permeable than the liner or natural subsoils underneath the waste
(to prevent a bathtub effect). This is an inadequate requirement
for this area because it would allow a cap that would not
adequately control infiltration. For Alternative #4 and #5,
, since the waste is being stabilized to the point of no longer
being a hazardous waste 'prior to capping, these regulations would
not be relevant.
Alternatives #4 and #5 offer the greatest degree of long-
term effectiveness although the difference from Alternative #3 is
small. By stabiiizing the waste material (as ,in Alternative #4
'and #5), the leachability of the metals would be greatly'
decreased thereby reducing the ability of the contaminants from
the south landfill to migrate to the wetlands and cause an impact
to environmental receptors. While in Alternative #3, any ground
water that comes into contact with waste material, would be
extracted before it enters the river (and by pumping, this ground
water could not enter the south wetlands), the extremely high
amount of operations and maintenance (that would probably be
required forever) greatly decreases (in comparison to Alternative
#4) the qbility to maintain reliable protection of the'
" environment. ' ,
stabilizing the waste would greatly reduce its mobility but
would increase its volume by about 25%. Alternatives #2 and #3
offer no reduction of toxicity, mobility, or volume through
treatment. Alternative #2 is the best in terms of 'short-term
effectiveness (with Alternatives #4 and #5 being the worst)
because it has the least number of major components. ,However, in
all the alternatives (except the "no action" alternative),
traffic along Basin Road, which is the only easy access to a
number of salvage yard$, would be greatly restricted'and possibly
ha~tedduring part ,of the construction. 'Alternatives '#2, #3 i '#4, '
and #5 are all implementable with Alternative #2 being the '
easiest and'Alternatives #4 and #5 being the most difficult. The
net present worth cost of Alternative #2 is significantly less
than the other three, with Alternative #5 being less than
Alternative #4 which is slightly less than Alternative #3.
EPA has determined that Alternative #5 (consolidation,
stabilization, and capping) is the preferred remedy because it
provides a high degree of overall protection of human health and
the environment (almost that of Alternative #4). Alternative' #5
significantly reduces the ability of the contaminants at the
south landfill to migrate where they contribute to ground-water
MCL exceedances and the surface-water SWQS exceedances. It also
meets EPA's preference for treatment and has the second highest
degree of permanence and long-term effectiveness among the
35
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.
compared alternatives. However, EPA has determined that the
extra protection afforded by Alternative #4 is not necessary
because the waste, once stabilized, would no longer fail the TCLP
test and has selected the least costly of the two alternatives
that offer overall protection to human health and the
environment.
The state does not support the selection of Alternative #5.
The state's position is that a low-permeability cap (such as that
described in Alternative #2) would be sufficient to protect the
environment (see Attachment A for details on the State's.
position). Written comments received from the public, including
Du Pont, support ~apping or possibly stabilizing the waste but
not both. Also, strong objections have been expressed to any
te~por~ry complete closing of Basin .Road or South. James street,
'To alleviate the concerns, the performance. standards state that
the excavation' must be conducted in' such a way as to allow some
traffic through this area during daily business hours.
SOUTH WETLANDS
ALTERNATIVE #2: This alternative involves determining the'
exact areal extent of unacceptable environmental impact (based on
the clean-up criteria for cadmium; lead, and zinc (Figure 29
shows the approximate area requiring remediation, the exact ar~al
extent will be determined during the . remedial design),. ..'. .
stabilization of the excavated sediments and then disposal in the
south landfill,24 backfilling the area of excavation to return
the area to original grade, re-veqetating and re-e~tablishing the
wetlands, long~term monitoring of the entire south wetland area,
and long-term maintenance of the tide gate to prevent the
Christina River from entering the wetlands. The present worth
cost of this alternative is $4,200,000.
ALTERNATIVE #3: This alternative is the same as Alternative
#2 except that instead of u~ing the .sediment clean-up criteria to
determine what~rea required remediation, .remediation would .take.
place wherever Delaware's SWQS exceedances occur in the wetlands.
Work would be done d~ring the remedial design to determine' .
sediment clean-up criteria that would allow the surface water in
the wetland to stay below the SWQSs. This is estimated to be a
much larger area than if the sediment clean-up criteria in
Alternative #2 are used. For the purposes of a cost estimate, it
is assumed that the whole south wetland area would require
remediation for this alternative. The present worth cost of this
alternative is $9,900,000.
24Since placement would not occur, RCRA land disposal
regulations would not be triggered.
36
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COMPARATIVE ANALYSIS OF ALTERNATIVES: Alternative #1 (no
action) does not meet the threshold criteria of overall
protection of the environment in that. it leaves portions of the
wetlands unremediated that have unacceptable environmental
impacts. Alternatives #2 and #3 would comply with ARARs which
prohibit the loss of wetland acreage and value.
Alternative #3 would comply with Delaware's Surface Water
Quality standards (SWQSs), 'especially' if the ground water in the
Columbia aquifer is remediated. . In Alternative #2, De,laware's
SWQSs may not be met in the south pond and in the 'southern
portion of the south wetlands. For example at ASOS, cadmium,
. chromium, copper, lead, anc:i zinc exceed Delaware'.s SWQSs
(aluminum, and iron also exhibit exceedances although EPA has not
concluded. at this time' that it is Site-related contamination) yet
data collected during the RI show that this station is not'
expected to trigger EPA's Site-specific sediment clean-up
criteria. EPA believes that it is mainly the contaminants in the
sediments that are causing the exceedances and not discharging
ground water (contaminant levels in the ground water at MW-SA are
lower than in the surface water at ASOS) although the ground
water does contribute to the contamination in the surface water.
Although Alternative #3 would comply with water quality
ARARs, EPA has determined relying on actual Site biological tests
'rather than the SWQSs to direct' ~emediation provides a more .
protective remedy since the surfade'watercontaminant levels are
not much above SWQSs25 and since compliance with sWQss would
25At AW01 (the same location as ASOI in the south pond, see
Figure 7), lead and zinc exhibited SWQs exceedances. However,
the total lead concentration was just above,the SWQS while the
dissolved concentration was below the SWQS. For zinc, during one
sampling total and dissolved levels were below the SWQS and
during the other sampling event"although. the .total. concentration.
. ~as 'above the acute SWQS" the. dissolved concentration was below
the chronic SWQS'. At AW02, (the same location as AS02 iri the
south pohd), the total lead concentration was above the chronic
SWQS, but the dissolved lead concentration was below the chronic
SWQS. At AS05, the total zinc concentration was above the acute
SWQS, but it is expected that the dissolved concentration would
be below the chronic SWQS (the dissolved zinc analysis was not
done but the levels are generally two to ten times lower than the
total concentration). For copper, the total concentration was
just above the chronic SWQS. For cadmium, the total
concentration was just above the chronic SWQS. For lead, the
total concentration was above the chronic SWQS yet way below the'
acute SWQS, and the dissolved concentration, although not
analyzed, is not expected to have been above the chronic SWQS.
For chromium, the total concentration exceeded the chronic SWQS,
but the dissolved concentration is not expected to.
37
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likely involve stripping more wetlands than is necessary to
protect the environment. Therefore, by issuing this ROD, EPA has
determined that complying with the SWQSs in the south wetlands
would create greater harm to the wetlands than relying mainly on
the biological test data collected during the RI to decide where
to remediate. EPA has also determined that Alternative #2
. provides a greater degree of protection to human health and the
environment, and EPA has decided to invoke the "greater risk to
human health and the environment" ARAR waiver as outlined in
Section 430(f) (ii) (C) (2) of the NCP. To make sure that there are
not areas of the south wetlands where SWQSs exceedances are so
extreme that the waiver is no longer considered protective, this
waiver only applies as long as the dissolved concentration of a
Site-related contaminant stays ,below its respective acute SWQS..
If the dissolved 'cpncerttrat~on of anyone Site-re!ated .. '
contaminant goesabov~ 'its respective. acute SWQS, the sediments
shall be removed regardless of whether or not there are
exceedances of EPA's Site-specific sediment clean-up
criteria. 26
Alternative #2 provides for overall protection of the
environment because it calls for removal of the portion of
sediments that are' creating unacceptable impacts to aquatic life~
Long-term monitoring will provide a measurement of the
effectiveness Qf the remedy and will help determine if the.' ,
contamination left. in the unremediated pp~tion$ of the.we~land
becomes more bioavailable creating unacceptable. environmental
impacts. . .
The long-term effectiveness of Alternative #2 is exPected to
be good. Although Alternative #2 will not remove all of the
contamination in the south wetlands and the remaining
contamination will cause some impact to environmental receptors,
EPA expects that the Site-specific sediment clean-up criteria
will remain protective (i.e., EPA expects that in the future the
impact of. removing the rest of the contamination would be. greater
than the impact. of the 90ntamination.itself).. A reduction. of
mobility through treatment' would occur if the waste material is
stabilized. The short-term impacts are severe as the function of
the wetlands will be lost during construction and, even after'
construction, re-establishing the wetland could take a .
significant period of time., Alternative #2 is implementable.
26since it is highly unlikely that the dissolved
concentration of. Site-related .contaminants would exceed the acute' ,
SWQS, surface water chemistry samples 'do 'not need to be taken at
every sampling station during the delineation of the areas that
require remediation. Only 20' of those stations where the Site-
specific clean-up criteria do not require remediation need
surface water chemistry samples performed.
3~
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I.
I
'EPA has determined that Alternative #2 is the selected
remedy for this area of the site. The 'State does not support
Alternative #2 because of its position that the Site-specific
sediment clean-up criteria were developed without an adequate
amount of data (see Attachment A for details on the State's
position). Written comments received from the public, including
Du Pont, supported the need for excavation; however, the public
believed that hotspot remediation would be adequate.
CHRISTINA RIVER
ALTERNATIVE #2: This alternative involves determining the
exact areal extent of unacceptable environmental impact (based on
the clean-up criteria27.for cadmium, lead, and zinc), hydraulic.
dredging. of the river in this area, .covering the .area with clean
fill, and dewatering and disposal of dredged sedimerits either on-
site or off-site.28 silt curtains would be used to minimize
transport of sediments away from the dredging area. Long-term
monitoring would be conducted to determine if the unremediated
areas develop unacceptable impacts and to confirm the long-term
effectiveness of the remedy. The present worth cost of this
alternative is $4,700,000 (based on disposal in the north
landfill).
ALT~ATIVE #3: .This alternative involves .the determination
of .the exact areal extent of unacceptable environmental impact.
and capping this area with a concrete revetment blanket (a
concrete revetment blanket is a series of connected fabric
pillows that once anchored to the river bottom, is pumped full of
concrete). Monitoring would occur to make sure the remedy
remains protective of the environment. The present worth cost of
this alternative is $2,700,000.
4
. 27Whereas delineation of contamination in the wetlands
involves only sampling the top six inches' of sediments,'
delineation of sediment contamination in the river for .
Alternative #2 (dredging) would be done in six-inch increments to
a depth of two feet. Any of these samples could trigger
remediation. In areas where remediation is required, further
vertical delineation of contamination would take place prior to
dredging to a depth of two feet. This would insure that any
sediments that would reasonably be expected to become mobile
during a major regional storm event would be remediated.
Dredging would continue until contaminant levels go. below the'
ciean~up criteria. 'The dredged area would be backfilled with
clean sediments.
28RCRA Land Disposal regulations would be. triggered only if
disposal occurs off-site and if the dredged sediments fail the
TCLP test.
39
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COMPARATIVE ANALYSIS OF ALTERNATIVES: Alternative #1 (no
action) is unacceptable because it does not provide for the
overall protection of the environment. ~lternatives #2 and #3 do
protect the environment by preventing exposure of a~atic life to
sediment 'contaminant levels that produce unacceptable impacts.
However, Alternative #3 (capping) potentially causes greater harm
to the environment because deposition is not expected to occur on
the blanket and therefore, the remediated area would not support
aquatic life (i.e, cappirig does prevent exposure to the ,
contaminated sediment but also permanently destroys the habitat).
The long-term monitoring in both alternatives would ensure the
implemented remedy is protective of the environment. "
Major ARARs include Federal AWQC, Delaware's SWQSs, the
Delaware Regu~ations, Governing the Use of Subaqueous La~ds, and,
'the Coastal Zone'Management Act. EPA cannot ensure that
Alternative #3 (capping) would be consistent with the state of
Delaware's Coastal Zone Management Plan and therefore capping
does not comply with the Coastal Zone Management Act.
Neither alternative would attain AWQC or SWQSs, which are
ARARs for this area, ip the 'river at the Site due to upstream
sources of zinc. Therefore, EPA is invoking the "technical
impracticability" waiver as outlined in Section,
300.430(f)(1) (ii) (C) (3) ofthe.NCP because it is not possible for
remedial'actions' at this Site to attain the SWQSs for any,
contaminant'where"upgradient sources. are causing the'exceedances
of sWQSs.
The long-term effectiveness of Alternative #2 is much
greater than Alternative #3 because the sediments are removed
from the area and, if necessary, treated before being properly
disposed of. The ability of either of these alternatives to
maintain reliable protectiveness depends on limiting the
discharge of ground water from the site into the river. The
site-specific sediment clean-up criteria are expected to remain
pr,o't:ective.,'" , " .,. . '
Dredging offers some opportunity for reduction of toxicity,
mobility, or volume through treatment in this area. Dredged
material would, in all lik~lihood, be disposed of on-site. At
the north landfill stabilization would likely be required to
improve structural stability of the sediments. If disposed of in
the south landfill, the dredged material would almost definitely
require stabilization. This stabilization would also reduce
mobility of the metal contaminants. However, dredging would also
cause an estimated 1. .to 2 percent of the sediments to migrate,
from the site with the river current. Alternative #3 offers the
best short-term effectiveness. However, by limiting the period
of dredging to times of low current .velocity and low aquatic life
activity, impacts can be kept to a minimum. Relative to
dredging, installation of the cap would not take very lon
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Alternatives #2 and #3 are implementable with Alt~rnative #3
being the easiest.
Capping is more cost effective, than dredging" especially if
the wastes are not disposed of in the north landfill since costs
would go up significantly (an estimated additional $8.5 million
for off-site disposal).
EPA has determined that Alternative #2 is the preferred
remedy. Although Alternative #3 does p~otect aquatic life by
preventing exposure to contaminated sediments, it also destroys a
substantial area of habitat and thereby does not meet the overall
protection of human health and the environment threshold
criteria. Alternative #2 would allow the habitat to be restored
,thus providing' greater overall protection to the environment. '
Careful implementation of Alternativa #2 should keep any sediment
transport to a minimum. The state does not support Alternative,
#2 because of its position that the Site-specific sediment clean-
up criteria were develop~d without an adequate amount of data
(see Attachment A for details on the state's position). Written
comments received from the public, including Du Pont, strongly
opposed dredging and stated that Alternative #3 should be
selected due to the risk of sediment transport during dredging
operC!-tions. '
CXBA-GEXGY AND DU PONT BOLLY RUB PLANTS
The remedies in this section address the areas shown 'in
Figure 30. This area includes the complete CIBA-GEIGY plant and,
a portion of the Du Pont Holly Run plant that has contaminated
soils (called "contaminated plant areas" below). Only about 3%
of the Holly Run plant area is included. '
ALTERNATIVE #2: This alternative involves institutional
controls, paving the remaining portions of the contaminated plant
. areas, installing ground-water recovery wells, ~n the fill' zone
near the river, ,treating 'recovered ground. water, and installing a
river bank c9ver'system (see Alternatives #2 and #3 in the "North
Landfill" section for the description of,the river bank cQver
system and the ground-water treatment system). Institutional
controls would involve deed restrictions, ground-water use
restrictions and a special health and safety plan to be used
during any subsurface work in the contaminated plant areas.
Paving the rest of the contaminated plant areas (the exact
portion of the Holly Run plant requiring paving to be determined
during the remedial design) would decrease infiltration of rain
water and prevent exposure to soil lead levels above 1000 ppm.
The combination of the river bank cover system and ground-water
recovery system would prevent the flow of fill zone ground water
to the river and prevent erosion of contaminated soil into the
river. The present worth cost of this alternative is $9,300,000.
41
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ALTERNATIVE #3: This alternative is the same as Alternative
#2 except that a physical barrier wall (technology to be chosen
during the remedial design from deep soil mixing, soil/bentonite
slurry, sheet' piles, or geosynthetic membrane) will be installed
to the base of the Columbia aquifer along the river (see Figure
37 for the approximate location). Ground water would continue to
be recovered on the plant side of the wall to control any ground-
water mounding that could affect building foundations and that
could force contaminated ground water downwa~d into the Potomac
aquifer. The present worth cost of this alternative is
$11,500,000.
ALTERNATIVE #4: This alternative is the same as Alternative
#3 except that the physical barrier wall would be placed
completely around ~he contaminated plant areas (this wall would
join 'both ends of the wall along the river side of the north'
landfill, completely surrounding all of the contaminated soil
associated with the north landfill and the contaminated plant
areas). A ground-water recovery system inside the wall would be'
needed to control any ground-water mounding as described in
Alternative #3 and another would be needed north of the Site in
Newport to control mounding that would occur up-gradient of the
wall. An interceptor trench or a series of recovery wells would
be installed on the site (if an interceptor trench could be used)
or on the north side of the railroad tracks, but very near the
site; to 'reduce the ground~water mounding. If no ,steps were' ' ,
taken to 'reduce the ground-water mounding effect, construction of
t~e barrier wall would likely result in an increase in ground-
water elevations over the approximately 50-acre area shown in
Figure 31. The present worth cost of this alternative is
$16,300,000.
ALTERNATIVE #5: This alternative is the same as '
Alternative #3 except that it does not include the river bank
cover system. The natural vegetation would be left on the river
,bank. The present worth cost of this alternative is $11,000,000.
, '
, ,
COMPARATIVE ANALYSIS OF ALTERNATIVES: Alternative #1 (no
action) does not meet the t~eshold criteria of overall
protection of human health and the environment in that nothing is
done to 'prevent worker exposure to soils or to control the
contaminated plant areas', contribution to impacts in the river
and to MCL exceedances in the ground water.
Alternatives #2, #3, #4, and #5 do provi~e overall
protection of human health by controlling worker exposure to
,contaminated soils., They al~o greatly decrease the plant areas'
contribution to environmental impacts in the river. However,
Alternative #2 does not address the Columbia ground-water
discharge to the river which'is contributing to AWQC exceedances
and thus, does not provide overall protection to the environment
and does not meet ARARs. Alternatives #3, #4, and #5 limit, to
42
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the maximum extent practicable, contaminated Columbia aquifer
ground water from entering the river. Although a circumscribing
barrier wall would make it easier to ensure that. in all areas of
the plant there is' an upward migration of the ground water'
between the Columbia and Potomac aquifers (which would prevent
additional contamination from entering the Potomac and thereby
provide a greater degree of overall protection to the
environment), a barr.ier wall just along the river
'(Alternatives #3 and #5) can also greatly limit any downward
migration because most'of the area where the Columbia aqUifer .
migrates to the Potomac aquifer is along the river where the
recovery wells would be placed.
. Although the river bank cover system in Alternative #2,. #3,
and #4 would decre~sethe ability of contaminants in the landfill.
berm from leaching into the river, the natural river bank .
vegetation (as part of Alternative #5) offers better slope
stability. The natural vegetation also provides habitat for
birds and provides benefits for the river such as cooling. The
benefits to the environment of the natural river bank vegetation
are greater than the benefits of the river bank cover system
(only if the physical barrier wall is installed at least along
the river). Therefore, Alternative #5 offers a greater degree of
overall protection of human health and the environment as
compared. to Alternative #3.
. . .
Aiternative' #3, #4,' and #5 would comply with ARARs for this
area including the Archeological and Historical Preservation Act
of 1974. Due to the digging along the river bank, inspection,
docum~ntat~on, and/or collection of artifacts would be done.
Alternatives #3, #4, and #5 offer the same degree of long-term
effectiveness. Alternative #2 has little long-term effectiveness
because by not capturing the Columbia aquifer ground water before
it discharges to the river, the area of remediation in the river
could become recontaminated over time. .
Alternative #2 would be the easiest to implement as well' as
have the greatest short-term effectiveness in that it would be
the fastest alternative to construct and have operational.
Installing a barrier wall, either along the river or completely
around the contaminated area, will be difficult alth~ugh judged
to be implementable (however, Alternatives #3 and, especially, #5
would be much easier to implement than Alternative #4). For
Alternatives #3, #4, and #5, plant utilities (sewer, nitrogen,
and power lines) would potentially have to be moved. There is a
strong possibility of production being interrupted in the CIBA-
GEIGY and the Du Pont Holly Run plants, especially in Alternative
#4. Also in Alternative #4, installation of recovery wells and
piping would cause temporary impacts. to lawn areas and could
disrupt traffic in the area immediately adjacent to the north
side of the railroad tracks. Of the alternatives that meet the
threshold criteria of overall protection of human health and the
~3
-------
environment (Alternatives #3, #4, and #5), the net present worth
cost of Alternative #5 is the least although it is only slightly
less expensive than Alternative #3. Alternative #4 is
significantly more expensive than the other alternatives.
EPA has determined that Alternative #5 is the selected
remedy for this area of the site in that it provides for overall
protection of human health and the environment. Also~ for the
alternatives that meet the. threshold criteria, Alternative #5 is
the easiest to implement and costs the least. The state supports
this determination. Comments (both verbal and written) opposed
the circumscribing physical barrier wall that was proposed
because of the need for a ground water recovery system in the
Town of Newport to prevent 'any basement flooding. EPA has
addressed these concerns by selecting a remedy which only'
specifies the physical barrier wall along the river. 'One
commentor objected to the proposed river bank cover system
because it destroyed valuable habitat along the river. The river
bank cover system is not part of the selected remedy. Comments
were also received which opposed any barrier wall since.
installation will cause disruptions for CIBA-G~!GY and since, in
the opinion of some of the commentors, there is no need for the
wall. However, EPA has determined that controlling the discharge
of the ground water into the river is necessary to protect the' .
environment and that the physical barrier wall that is.discussed
in Alternative #5 iathe most effective. means of limiting.
continued migration of the contaminated ground water' in ,the fill'
zone and the Columbia aquifer to the Christina River.
GROmm WATER
In the discussions of the alternatives in several of the
previous sections (north landfill, south landfill, and the
CIBA-GEIGY and Du Pont Holly Run plants), ground water has .been a
major factor. Preferred alternatives were proposed in these
. .areas which would prevent continued release of con~aminants to
'the ground ,water. This section discusses al~ernatives to .
, remediate the ground water in both the Columbia and Potomac'
aquifers that is already contaminated. .
Generally, ground water in the Columbia aquifer flows toward
the Christina River. (Le.., on the north side of the river, the
Columbia gr~und water flows south to the river and on the south
side of the river, the Columbia ground water flows north to the
river). Columbia ground water on the north side of the river
discharges into the river and the wetlands on the west side of
.the .north landfill. .'A small portiqn may flQw underneath the
river and discharge into the south wetlands. Columbia ground
water on the south side of the river discharges into the river
and the south wetlands. Ground water in the Potomac aquifer
flows south. On-site ground water from the Potomac leaks upward
44
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into the Columbia~ although in portions of the Site it is the
other way around.
. The ground water at the Site is a ClassIIA aquifer (i.e.,
the aquifer system, both the Columbia and the Potomac, is a
current source of drinking water). Therefore, the NCP states
that EPA's goal would be to return the ground water to its
beneficial use by considering MCLs or non-zero MCLGs as ARARs.
However, 'the NCP does provide certain instances where ARARs may
be waived. Sections 300.430(f) (1) (ii) (C) (1-6) of the NCP outline
six different ARAR waivers, including the interim measure waiver,
the equivalent standard of performance waiver; the greater risk
to human health and the environment.waiver, the technical
impracticability waiver, the inco~sistent application of state.
standard waiver, and the Fund-balancing waiv~r. The greater risk'
to hUman health and the environment waiver may be invoked when
compliance with an ARAR will cause greater risk to human health
and the environment than non-compliance.
Section 300.430(f) (5) (iii) (A) of the NCP states that
performance (for example,' attainment of ARARs) shall bem~asured
at appropriate locations in the ground water, surface water, etc.
The preamble to the NCP explains that for ground water, .
remediation levels should gener~lly be attained throughout the
contaminated plume or at and. beyond the edge of the waste.
m.anagement area when waste is . left in place (55 FR'S753h FigUre
32 shows the boundary of the "waste management area" for this
Site and also indicates the area where MCLs or non-zero MCLGs are
exceeded outside of the waste management area. The area outside
of the waste management area is where MCLs or non-zero MCLGs are
considered ARARs and is called the "area of attainment." The
following alternatives address this area of attainment.
ALTERNATIVE #2: This alternative would involve
institutional controls, ground-water monitoring, and placing
residences and ~usinesses along Old Airport Road on public water
supply.' .!nstitutional controls would include .de~drestrictions' .
. and establishing a ground-water management zone in the area of
the Site (see Figure 33 for the approximate ar~a) to limit the
future installation of .drinking water wells. Long-term
monitoring, including monitoring at the north landfill for
thorium, of the Columbia and the Potomac aquifers would provide
data to measure the rate of contaminant.attenuation in the
Columbia aquifer and the rate of contaminant migration in the
45
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Potomac aquifer to the south.29
alternative is $1,400,000.
The present worth cost of this
ALTERN~TIVE #3: This altern~tive includes everything from
Alternative #2 with the addition of a ground-water recovery
system installed along the south edge of the south landfill and
in the south wetlands to clean up the Columbia aquifer south of
the south landfill (see Fiqure 34 to see the area to be
remediated and approximate locations of the recovery wells) and a
ground-water recovery system that would create a hydraulic
barrier in the Potomac aquifer. The hydraulic barrier would
,prevent migration of contaminated Potomac ground water from the
waste management area and would remediate the ground water in the
area of attainment (see Fiqure 35 for the approximate recovery
well locations). The recovered ground water would be treated 'as"
discussed in the "North Landfill" section and discharged to the
south wetlands to prevent any dewatering of the wetlands that
might tend to occur due to the withdrawal of the Columbia ground
water. The present worth cost of this alternative is
$13,500,000.
COMPARATIVE ANALYSIS OF ALTERNATIVES: Each of the
alternatives provides for the overall protection of human health
except Alternative #1 (under the "no action" alternative, nothing
would preclude someone, in the future, from drilling a drinking
. water well in the contaminated area). Alt,ernative #2 does not
meet ARARs 'since the 'ground water is not returned to' its
beneficial use by reducing contaminant levels to HCLs or non-zero
HCLGs (except perhaps by natural attenuation which, even if it
does occur, could take a very long time).
. ,
Alternative #3 would meet ground-water ARARs in the Potomac
aquifer. However, the ground water upgradient of the hydraulic
barrier will become more contaminated since the pumping will
cause a reversal of the natural upward flow of the groundwater
into ~he Columbia aquifer and will pull more highly ~ontaminated
'ground"water. down into 'the Potomac, aquifer. Also' in.. the Potomac'
aquifer, the lorig~term effectiveness and permanence is greatest
with Alternative #2 because the plume should eventually attenuate
naturally to levels safe to drink since the sources of
29For the Columbia aquifer, the monitoring would include
sampling MW-21A, MW-23A, MW-24A, MW-25A, and MW-26A for metals.
For the Potomac aquifer, the monitoring would include sampling
MW-6B, MW-18B, MW-21B, and MW-26BS. If the monitoring shows that
any of the Site-related contaminants have migrated t~ anyone of
these wells at a level sufficient to produce a risk (cumulative
risk caused by all Site-related contaminants) of either 1X10-6
for carcinogenic risks or 1 for non-carcinogenic risks, further
remedial action separate from this ROD (such as restoration or
containment of the ground water) will be considered at that time.
46
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contamination are being controlled. Active remediation in the
Potomac aquifer would create a slug of contamination underneath
the waste management area that would require pumping for a longer
period of time than would be required to let the existing
contamination in the Potomac aquifer to attenuate naturally to
currently acceptable levels.
Alternative #3 also has the potential of meeting ground-
water ARARs in the Columbia aquifer by remediating the
contaminated portion of the Columbia aquifer in. .the area of
attainment. However, the Columbia aquifer may become more
contaminated because pumping the Columbia aquifer may cause the
wetland area to become a recharge area for ground water instead
of a discharge area for ground water. If the Co!umbia aquifer,
ground water is recharged from the surface water in the wetlands;
higher levels of contamination may be introduced into the ground
water by the washing of contaminants from the sediments. The
active remediation of Alternative #3 does offer the greatest
degree of long-term effectiveness and permanence for the Columbia
aquifer. However, contaminant levels in the Columbia aquifer
should'decrease in Alternative #2 since the sources of .
contamination (releases from north ,and south landfills and the
contaminated plant areas) are ,being controlled.
Alternative #3 offers some reduction in mobility or vol~e
" throughtrea~ment. However, eviden~e to date indicates that the,
plume has not migrated very much in the last 15 years.
Alternative #2 rates .the best in the area of short-term
effectiveness because in Alternative #3 wells will be placed in
wetlands. This will cause temporary and possibly permanent loss
of these wetlands because access roads will have to built. Each
of the alternatives isimplementable, although Alternative #2 is
the easiest to implement. Alternative #2 costs significantly
less (approximately 10 times less) than Alternative #3.
EPA has determined that Alternative #2 (monitoring and
installation of a public water supply 'line) is the preferred
remedy' for this area of the Site because it would provide the
best overall ,protection of human health and the environment.
Once this alternative is implemented, there would be no
possibility of human exposure to contaminated ground water. The
selected remedies for the other areas of the Site would minimize
to the maximum extent practicable the release of contaminated
ground water into the environment. EPA does not expect the
contaminant plume in the Potomac aquifer to expand. To date, the
plume has exhibited limited migration potential due most likely
to anions in the natural ground water combining with the heaVy
metals and precipitating the metals out of solution so they are
no longer mobile. Also, the selected remedy for the other areas
of the Site will greatly decrease, if not eliminate, contaminant
migration from the Columbia aquifer to the Potomac aquifer (i.e.,
the source of c~ntamination to the Potomac will be greatly
. 47
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reduced and perhaps eliminated).'
shows that the plume is becoming
remedial measures in additi~n to
in this ROD may be called for at
However, if the monitoring
unacceptable in area of extent,
the public water line selected
that time.
In order to select Alternative #2, EPA must invoke the
greater risk to human health and the environment waiver (NCP
Section 300.430(f) (ii) (c) (2» in recognition of the fact that to
meet MCL or non-zero MCLG ARARs would create more harm than
good. 30 Althougp ARARs would not be met with Alternative #2,
t~e alternative would provide overall protection of human health
and the environment. EPA has determined that Alternative #2 has
. advantages over Alternative #3 in that pumping the Potom~c
aquifer (as outlined in Alternative #3)'would cause an increase
in contaminant lev~ls in a portion 'of.the Potomac aquifer and
pumping.the Coiumbia aquifer (as outlined in Alternative #3)
would potentially harm the south wetlands and cause greater
contaminant levels in the Columbia aquifer. Further,
implementation of Alternative #2 will be protective of human
health since installation of a public water supply line to nearby
, residents and businesses along Old Airport Road and use of
institutional controls to limit new wells from being drilled,
would prevent human exposure to ground water contaminated by
harmful levels of Site-related contaminants.
. The 'State supports the selection of A~ternative #2 'except
that'the state wants' the ROD, to . state that if the long-term'"
monitoring wells begin to exhibit levels of contaminants
considered unsafe to drink, further remedial action would be
taken rather than just considered (see Attachment A for details
on the State's position). Written comments received from the
public, including Du Pont, were generally supportive of
Alternative #2.
SELECTED REMEDY:
DBSCRIPTION AND PERFORMANCE STANDARDS
. Based ,on the findings of the RI/F'S; the nine . criteria
identified in Section'300.430(e) (9) (iii) of the NCP (see
Table 11); and written comments received from the public,
including Du Pont; EPA has'selected a remedy for this Site. The
selected remedy addresses the human health and environmental
risks presented by this grossly contaminated Site. Below is a
summary and a detailed description with performance standards of
30The "greater. harm to human health and the. ~nvi~onment" .
ARAR waiver also applies to the State of Delaware RegUlations
Governing Public Drinking Water (revised 3/11/91) sections 22.2,
22.3, 22.4, 22.6, and 22.10 and the Delaware Regulations
Governing Hazardous Substance Cleanup (1/93), Section 9 for the
Columbia and Potomac aquifers.
48
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the selected remedy. It should be noted that some changes may be
made to the implementation of the remedy as a result of the
remedial design and construction processes. Such changes, in
general, reflect modifications resulting from the engineering
design process. Any changes to the remedy will be done in
accordance with the NCP.
SUMMARY OF EPA'S SELECTED REMEDY
1.
Ballpark
. Selected Remedv: Excavation of soils above 500 ppm
lead with disposal in the north landfill (Alternative
, #2) .
. ~ose:
,lead.
Prevent human exposure to'elevated levels of
. Cost:
$10,000
2.
North landfill
. Selected Remedv: capping; wetland remediation,
restoration and monitoring; vertical barrier wall
, to'base of the Columbi.a aquifer;' and ground-water
recovery and treatment (Alternative #5). .
down
. PurDose: Prevent continued releases of contaminants to
the ground water which discharges to the river and the
north wetlands, clean up areas of unacceptable
environmental impact in the north wetlands, prevent.
exposure of plant and terrestrial,life to contaminated
soils. . ,
. Cost:
$12,100,000
3.
South landfill
. Selected Remedy: Excavation and consolidation of
contaminated.soil underneath and to the east of Basin
Road or South James Street onto the south landfill; in-
situ soil stabilization of the combined soil; capping
(RCRA Subtitle D) of the south landfill
(Alternative #5)..
. PurDose: Prevent continued .releases of contamiriants to
the ground water which discharges to the river and the'
south wetlands, prevent unacceptable human exposure to
contaminated soils from the landfill.
.~:
$14,300,000
49
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.
4.
South wetlands
. Selected Remedv:
(Alternative #2).
Excavation, restoration, monitoring
. Puroose: Prevent unacceptable impacts to environmental
receptors.
. Cost:
$4,200,000
5.
Christina River
. Selected Remedv:
#2).
Dredging, monitoring (Alternative
.
PurDose: Prevent unacceptable impacts to. environmental
receptors.
. Cost: $4,700,000 (based on disposal of the dredged
sediments in the north landfill)
6.
CIBA-GEIGY and Du Pont HQlly Run plants
. Selected Remedv: Vertical barrier wall along the
Christina River at the eIBA-GEIGY plant, pave the rest
. of thegro~nd within the contami~ated' piant areas, "
recover the ground water" up~gradient of the barrier'
wall, institute special health and safety plans for
intrusive work (Alternative #5).
. PurDose: Prevent continued releases of contaminants to
the ground water which discharges to the river, prevent
unacceptable human exposure to contaminated soils~
. Cost:
$11,000,000
7.
Ground water
. Selected Remedy: Monitoring, provide public water
supply along Old Airport Road, establish a ground water
management zone, invoke the "greater risk to human
health and the environment" ARAR waiver (Alternative
#2) .
.
PurDose: Prevent human exposure to Site-related
contaminated ground water, prevent further
. contamination of the Columbia and the Potomac aquifers,
protect the south wetlands. .
. Cost:
$1,400,000
50.
-------
,The total present worth cost of the proposed remedy is
approximately $47,700,000. See Table 13 for a cost summary of
the overall remedy and Tables 14 to 20 for a detailed cost of
each portion of the remedy.
DETAILED DESCRIPTION AND PERFORMANCE STANDARDS
1.
BALLPARK
1.1
80il Removal and Disposal
DESCRIPTION: A small area, where Ayre Street dead ends at
the ballpark (see Figures 1 and 24), with lead levels above
500 ppm shall be excavated.Sa~ples shall be taken to delineate
the 'waste material and to. deterinine'if the soil to be excavated
should be classified as a RCRA-hazardous waste. Soil shall be
excavated to a depth and extent such that remaining lead levels
are below SOO ppm. Confirmatory samples shall be taken before
the area is backfilled with clean fill from an EPA-approved off-
site source and reseeded.. The estimated amount of soil requiring
excavation is one cubic yard. The excavated material shall be
disposed of in the north landfill. Tests shall be performed to
determined if the soil to be excavated is a RCRA-hazardous waste
(i.e.,' exceeds the Toxicity Characteristic Leac~ing Procedure,.
':(TGLP) criteria). If the soil fails, the, TCLP. test, the excavated
soil 'shall, in compliance with RCRA land disposal regulations, be .
treated until it is no longer a RCRA-hazardous waste (through
stabilization) and then disposed of in the north landfill. If
testing reveals that the soil is not a RCRA-hazardous waste, it
shall be disposed of in the north landfill without treatment. .
The present worth cost for this alternative is $10,000. See
Table 14 for details of the cost including the capital cost and
annual operations and maintenance costs.
PERFORMANCE STANDARDS: Below are the performance standards
for the ba~lpark portion of ,the selected remedy:'
1.1.1. A statistically significant number of surface soil
samples (0-6" depth) to determine the areal extent of lead
contamination above SOO ppm shall be collected in the ballpark in
the' vicinity of the end of Ayre, Street. These samples shall be
analyzed, at a minimum, for lead using standard EPA Contract
Laboratory Program (CLP) protocols for metals.
1.1.2. All soils above the'SOO ppm lead level$ shall be
excavated to a ,depth where the. lead levels are below 500 ppm.
1.1.3. Confirmatory soil samples shall be collected from'
the excavated area (of sufficient number to statistically
determine that the lead levels remaining in the excavation pit
are below SOO ppm).
Sl
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1.1.4. TCLP tests for metals (complete list of TCLP metals)
shall be performed on soils which have been determined by the
above testing (see paragraph 1.1.1) to be.above 500 ppm total
lead (eit~er before or ~fter excavating).
1.1.5. If the soil samples from the area requiring
excavation fail the TCLP test for metals, the exc~vated soil
shall b~ stabilized. Stabilization shall involve thoroughly
mixing the excavated soils with' a cementitious or pozzolanic .
reagent mixture developed specifically to bind the metal
constituents within the stabilized matrix. The actual'
stabilization agent shall be selected during the remedial design
and. is subject to EPA approval. Due to the expected small volume
of excavated soil (approximateiy one cubic yard) and to the use
.of the north iandfill for disposal (which is not being. .
stabilized), design. optimization tests do not have to be
performed to determine the stabilization agent. Instead, a
literature review shall be performed to determine the nature and
quantity of stabilizing agent to be used. .The performance
standard for the stabilized soil is that it shall pass the TCLP
test for metals prior to disposal in the north landfill(RCRA
land disposal regulations are ARARs).
1.1.6. The excavated soil shall. be disposed' of in the north
landfill prior to capping.
1.2
Ballpark Cost.
DESCRIPTION: The estimated present worth cost of
Alternative #2 is $10,000.
2.
NORTH LANDFILL
2.1.
Landfill. Cover
DESCRIPTION: A low-permeability cover system (cap) shall be
installed to reduce infiltration in order to minimize continued
ground-water contamination ,from this area. For example, the
cover could be a geosynthetic c~ay liner. Figure 25 shows the
approximate area to be covered and a potential cross section of
the cover system. The thorium bearing drums shall be ~ocated.
PERFORMANCE STANDARDS:
2.1.1. Prior to capping, the exact location of the thorium
drums shall be determined.
52
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2.1.2. A landfill cap shall be installed that completely
covers the north landfill (see Figure 25 for the approximate area
of this cap).
2.1.3. The landfill cap shall sufficiently overlap or tie-
in to the pavement at the CIBA-GEIGY and Du Pont Holly Run plants
to prevent infiltration of water between the area that is paved
and the area that is capped and shall sufficiently overlap or
tie-in to the physical ground-water barrier wall to prevent
infiltration of water between the area that is ,capped and the
hydraulic barrier wall.
2.1.4. The landfill cap shall have a permeability of 1X10-7
em/see or less.
, . ,
2.1.5.' The'la~dfill cap' shall have at least two layers of
low-permeability material, one of which shall be a geosynthetic
membrane.
2 . 1. 6 . The
to function with
minimize erosion
settling so ,that
provide adequate
landfill cap shall be designed and constructed:
minimum maintenance; to promote drainage and
or abrasion of the cover; to accommodate
the cover's integrity is maintained; and ,to
freeze protection for the liner.
2 . 1. 7 . . 'The 'landfill cap' shall be, re~vegeta:ted in. suc,h 'a way',
as to provide a high quality habitat for wildlife to the maximum
extent practicable (without endangering the liner). The types of
vegetation shall be identified in the remedial design. Th~ .
remedial design is subject to EPA approval.
2.1.8. All material disposed of in the north landfill shall
be of such structural strenqth as to adequately support the cap.
2.1.9., All material that is to be disposed of in the north
. landfill (see paragraphs,1.L6, 2.2.1, 2.3.1, 'and 5.3.2) 'shall be'
disposed of prior to capping. '.
2.2.
stabilization and Disposal of Upland Waste Piles
DESCRIPTION: Several small (less than one cubic yard) piles
of Lithopone waste in the upland area to the west of the north
landfill shall be stabilized, if necessary, and then consolidated
to the north landfill prior to the capping set forth in section
2.1.
PERFORMANCE STANDARDS:
2.2.1. The several small piles of Lithopone waste in the
uplands adjacent to the north wetlands and to the west of the
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north landfill shall be excavated and disposed of in the north
landf i 11.
2.2.2. Samples from the material excavated per paragraph
2.2.1 shall undergo a TCLP test for metals. Any of the material"
that fails the TCLP test shall be stabilized prior to disposal in
the north landfill.
2.2.3. Stabilization shall involve thoroughly mixing the
excavated soils with a cementitious or pozzolanic reagent mixture
developed specifically to bind the metal constituents within the
stabilized matrix. The actual stabilization agent shall ~
identified in "the remedial design and approved by EPA. Due to
the expected small volume of excavated soil (approximately one
cubic yard) and to the use of the north land(ill for disposal
(which. is not being" stabilized), design" optimization tests do not.
have to be performed to determine the stabilization agent.
Instead, a literature review shall be performed to determine the
nature and quantity of stabilizing agent to be used. The
performance standard for the stabil~zed soil is that it shall
pass the TCLP test for metals prior to disposal in the north
landf ill.
2.3.
North Drainage way and North Wetlands
. . . .
DESCRIPTION: The upper and parts of the mid~"and "lower
north drainage way will be covered by the cap called for in
section 2.1. The wetlands associated with the lower part of the
north drainage way (i.e., those not covered by the cap described
in paragraph 2.1 above) and the rest of the north wetlands that
contain sediments in excess of the Site-specific sediment clean-
up criteria shall be remediated by removing the top one foot of
sediments. The exact area requiring remediation shall be
determined during remedial design by sampling sediments
throughout the north wetlands. The excavated sediments, if
"necessary, "shall. be. stabilized to make a: more structurally sound.
. material and put underneath the cap. The excavated wetland area
shall be restored.
PERFORMANCE STANDARDS:
2.3.1. The following shall be the site-specific clean-up
criteria for the sediments in the north wetlands (these are
absolute chemistrY values normalized to grain size): .
. Lead.
Cadmium .
Zinc
1200
60
5600
ppm
ppm
ppm
Areas that exceed anyone of the above Site-specific clean-up
criteria for the north wetlands, as revised if necessary pursuant
54
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to paragraph 2.3.3, shall be excavated to a depth of one foot.
The designation of areas which exceed the Site-specific clean-up
criteria and require excavation is subject to EPA.approval.
2.3.2. A statistically significant number (and a number
sufficient to direct remedial activities) of samples shall be
collected from the top 6" of the sediments in the north wetlands
(see area in Fiqure.36) to delineate areas containing sediments
. above the site-specific sediment clean-up criteria. The samples
shall be analyzed for the complete Target Analyte List (TAL) of
metals and grain size. The samples shall be collected. from areas
estimated to have a minimum of 50% fines (percentage of sediments
that can pass through a 64 micron sieve).
. .
. 2.3.3. A mi~imum.of four solid phase sediment toxicity.
tests (involving four. toxicity. test replicates and total organic
carbon (TOC), grain size, and TAL metals analyses) measuring the
survival rate of Hyallela azteca shall be performed in the north
wetlands in areas where the cadmium, lead, and zinc levels are
below the Site-specific clean-up criteria and above their AET
values (9.6 ppm, 660 ppm, and 1600 ppm, respectively, on an
absolute basis). A 30% reduction in survival compared to the
control sample shall be considered a significant impact. If
significant impacts are seen in any of the toxicity tests
performed for the north wetlands, EPA may modify ~e Site-
. specif~c clean-up. crite~ia as described in Paragraph 2.3..1 .
(however, not below their respective AETvalues) for the north
wetlands, if appropriate, to protect the environment.
2.3.4~ Prior to excavating 32 work-hours shall be spent
collecting and moving to an appropriate habitat any wildlife that
is residing in areas to be affected by the remediation.
2.3.5. The excavated area shall be backfilled with clean
fill from an EPA-approved source and returned to original grade.
. .
.2.3 ..6.. The wetlands that will be directly" affected .by the.
cap construction and the north drainage way excavation shall be
delineated to determine wetland type prior to remedial action.
using the "Federal Manual for the Delineation of Jurisdictional
Wetlands" (Federal Interagency Committee for Wetland Delineation,
1989).
2.3.7. The excavation of the sediments shall be designed
and performed in such a way as to minimize environmental damage
and to utilize, to the maximum extent practicable, excavation
methods such as vacuum.dredging or other alternative excavation
methods.
2.3.8. A portion of uplands (formerly farmland) adjacent to
the north wetlands equal in size (unless EPA determines during
the remedial design that the type of wetlands requires more than
'55
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L..__~_.
one-to-one replacement) to any wetlands destroyed by the north
landfill cap construction (this includes, for example, a small
area on top of the landfill and the upper part of the drainage
way) shall be graded to establish we~land hydrology. The exact
location and size shall be identified in the remedial design.
The remedial design shall be subject to EPA's approval prior to
implementation.
2.3.9. The wetlands ~hall be successfully re-established.
A complete restoratiop program shall be developed during remedial
design to address the excavated area and the' newly created .
wetland area. This program shall, at a minimum identify factors
which are key to a successful restoration program including, but
not limited to, replacing and regrading soils and re-
establishment of vegetation. The program shall be'implemented.
Other appropriate measures, includ,ing but' not limited .to, .
periodic maintenance (i.e., planting) may also be necessary to
ensure long-term restoration.
2.3.10. A variety of grasses and hydrophytic species common
to the area ,shall be used to revegetate the we~land. '
2.3.11. The newly constructed wetland shall be located and
constructed in such a manner as to prevent the runoff from the.
north landfill cap from destroying or de-stabilizing the new
wetland" . . ' , .
2.3.12. The excavated sediments shall be, if necessary,
stabilized (or otherwise processed just for the purpose of
removing or binding the water to make a sufficiently structurally
sound material to adequately support the cap) and shall be
.disposed of in the north landfill (RCRA land disposal regulations
would be triggered only if the sediments fail the TCLP test and
are stabilized "ex-situ"). The remedial'design shall describe
tests and procedures for determining' if stabilization or other
. physical processing is necessary to prior to putting the
'excavated sediments underneath the cap. These tests and
. procedures shall also include specifications for the final
stabilized or otherwise processed material.
2.4.
Borth Wetlands. Long-term Monitoring
DESCRIPTION: The lower section of the north drainage way
and the north wetlands shall undergo long-term monitoring to
ensure that the remedy is protective.
PERFORMANCE STANDARDS:
2.4.1. A long-term monitoring plan shall be developed and
implemented to monitor the effectiveness of the remedial action
in the north wetlands/drainage way and to make sure that the
56
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Site-specific clean-up criteria remain protective of the
environment.
2.4.2. The monitoring plan shall include sediment
monitoring stations located in both remediated and unremediated
areas (also include a site backgrourid location); TAL metals
analysis and acute and chronic toxicity tests shall be performed
(preferably using Hyallela azteca) at these locations.
2.4.3." The monitoring plan shall include appropriate field
observations of plant growth and of the general conditions of the
wetlands in sufficient detail to provide sufficient information
to determine the successful establishment of the wetlands.
2.4.4. The monitorihg plan shall identify the frequency "of ,
,monitoring and reporting requirements. The"reporting
requirements shall include a discussion of the results in
addition to data presentation.
2.4.5. ~he monitoring plan for the north wetlands shall
include the determination of a reference station to be approved
by EPA~ The reference station shall be representative of natural
background conditions in a tidal wetland and is, preferably, near
the site (EPA does not consider RS15 to be representative of
natural background conditions)~ Also since there is probably no
pristine 'ar~a nea'r the Site,; ,a list of, conditions ,tha~ would be '
expected in a pristine tidal wetland shall be developed "through
examination of aquatic conditions at areas in northern Delaware
or other appropriate areas.
2.4.6. Performance standards 2.4.1 to 2.4.5 above are the
minimum requirements of the monitoring plan. The monitoring plan
is subject to EPA approval. The discussion of the monitoring
results is also subject to EPA approval. If at some time EPA
determines that this monitoring data indicates that the Site-
specific clean-up criteria are no 19nger protective (for example,
"the metals'remaining in the sediments become ~orebioavailable, "
due to ,changing c,onditions and cause a greater impact),
additional remedial measures beyond those described in this ROD
may be required incl~~ing further dredging.
2.5.
8or~h Landfill Physical Barrier Wall
DES~PTION: A physical barrier wall (an actual wall that
limits migration of ground water to the maximum extent
practicable) shall be constructed to extend'from the ground'
surface to the base of the Columbia aquifer keying into the
aquitard which separates the Columbia aquifer and the Potomac
aquifer (see Figure 27 for the approximate wall location). This
wall shall connect to the physical barrier wall to be installed
alonq the river' bank at the CIBA-GEIGY plant as discussed under
57
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the "CIBA-GEIGY and Du Pont Holly Run Plants" section below (see
section 6.4). Because the wall may cause mounding of the ground
water to occur in the landfill, ground-water extraction wells
shall be installed to control any mounding effect. The recovered.
ground water shall be treated. '
PERFORMANCE STANDARDS:
.2.5.1. A physical barrier shall be constructed to extend
from the surface to the base of the Columbia aquifer. The.design
shall be such as to minimize to the maximum. extent practicable
the flow of Columbia ground water underneath the barrier wall
into the Christina River. The approximate barrier location is
shown in Figure 27. The exact location of the physical barrier
wall shall be identi~ied. in'the remedial design and. subject. to
EPA approval. The east end shall connect to the barrier wall in .
the CIBA-GEIGY plant. The west end shall extend far enough
around the north landfill to capture all of the Columbia and fill
zone ground water that has come into contact with contaminated
soil. .
2.5.2., The barrier shall have a permeability of 1X10-7
em/sec or less.
~.5.3. Different barrier wall technologies including deep
soil mixing, sheet.piles, geosynthetic membranes, and slurry.
.walls shall' be evaluated in the remedial design. Of.the '
technologies that are implementable, the remedial design shall
identify the technology considered to have the longest life.
More than one technology may be necessary depending on the wall
location.. EPA wil~ make the final decision as to the type of
barrier wall technology to be used.
2.5.4. Any unused piping found to cross the path of the
barrier wall shall be plugged or removed to a distance to. be
identified in the remedial design, subject to EPA approval, tha~
will.keep.a reservoir of potentially co~taminated.ground water
from being formed adjacent to the barrier wall. Any used piping
shall be inspected to make sure it is in proper working condition
so that a seal can be formed between the pipe and the barrier
wall that is of sufficient quality as to prevent a preferential
flow path of ground water from forming.
2.5.5. Ground-water recovery wells shall be installed in
sufficient number to control any mounding effect created by the
barrier wall. The wells shall draw the water table down to the
maximum extent practicable without affecting the water table
underneath the chemical plants in such a way as to cause
structural problems to buildings or pavement. The wells shall be
installed in accordance with appropriate state regulations (see
Table 12).
58
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2.5.6. All extracted ground water shall be treated and
discharged to the Christina River (or if determined by EPA during
the remedial design to be acceptable, the treated ground water
maYq be discharged to a publicly owned treatment works-POTW)".
This treatment shall include removing all contaminants (including
metals, organics, and, if necessary, radionucleides) necessary to
meet all discharge requirements (especially compliance with the
substantive requirements of a National Pollution Discharge
Elimination System [NPDES] permit if discharging to the Christina
River). If an air stripper or other vented sys~em is used to
treat the ground water, secondary controls will be necessary in
order to comply with Federal and State air ARARs (see Table 12)
"if the" emissions exceed the specified amounts in these ARARs.
Secondary c9ntrols will also be installed if nec~ssary to ensure
protectiveness of human health and the environment (for" "" ""
protection of human' health, secondary emission controls shall.be
installed if the emissions from the air stripper cause a greater
than 1X10-6 excess cancer risk). It is anticipated that the
treatment sludges will be hazardous waste. Any treatment
residues containing tetrachloroethylene shall be considered to be
F002 waste. Disposal of any treatment sludges or other wastes
shall be in accordance with appropriate Federal and State
regulations (see Table 12).
2.6.
.~orth Landfill Institutional Controls
DESCRIPTION: Institutional controls shall be put in place
in order to ensure the protectiveness of the remedy.
PERFORMANCE STANDARDS:
2.6.1. No excavation or construction, except as necessary
to maintain the integrity and the level of protectiveness of the
north landfill cap, shall be allowed once the cap is installed.
2.6.2~. No uses of the. north landfill shall be
may impair the cap's integrity. Any change in land
completion of the remedial action shall require the
approval of EPA, and/or its succe$sors.
made which
use following
prior written
2.6.3. As long as the buried thorium is present, the
property owner(s), and its successors-in-interest, shall
continuously maintain a metal monument placed on the north
landfill, said monument to be approved by ~PA to warn of the
presence of buried radioactive thorium-bearing material and to
mark the specific location(s) of. the thorium~bearing material in .
the north landfill. )
2.6.4. The property owner(s), and its suc;:cessors., shall
notify EPA, and/or its successors, of its intent to convey any
interest in' the, property described herein; Such conveyance shall
. 59
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not be made without the prior written approval of EPA, and/or its
successors. No conveyance of title, easement, or other interest
in the property shall be con~ummated by the property owner(s),
and its successors, without adequate and complete provision for
continued maintenance and protection of the north landfill cap.
2.6.5. The property owner(s), its successors and assigns,
shall not at any time institute legal proceedings, by way of
quiet title or otherwise, to remove or amend these institutional
controls unless ~PA, and/or its successors, has given ~e .
pr~perty owner(s), and/or its successors, advance written
approval. 31 .
2.6.6. No drinking water wells shall be installed at the
north landfill.. No. industrial: water production wells shall be
installed in the Potomac aquifer at the north landfill.
2.6.7.
purposes.
The north landfill shall not be used for residential
2.6.8. The north landfill shall not be used for
recreational purposes as long as thorium remains present in the
landfill.
2.6.9. Once remediation at the north landfill is completed
and the vegetation is restored, the.vegetation shall not" be .
removed except for maintenance activities. .. .
2.6.10. The restrictions on the use of the property shall
be included in the deeds to the Site property. The deeds to the
affected property shall also be modified to give notice to the
public of past land disposal and of the fact that releases and
threats of releases of hazardous substances have affected their
respective parcels.
2.6.11. Additional measures may be required to implement
the institutional controls outlined in. paragraphs 2.6. 1 to .
2.6.10. . .. .. .
31paraqraphs 2.6.2 to 2.6.5 are necessary for EPA to ensure
adequate protection of human health and the environment from .any
potential risks posed by the buried thorium. The U.S. Nuclear
Regulatory Commission (NRC) has" commented to EPA. that the ...
possibility exists for NRC itself to exempt this Site from NRC's
decommis~ioning regulations in 10 CFR Part 40.4. NRC would
require a strong set of institutional controls to be in place
before it would consider allowing the drums to remain at the
Site.
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2.7.
Borth Landfill Cost
DESCRIPTION: The estimated present worth cost of
Alternative #2 is $12,100,000. See Tabl~ 15. for details of this
cost estimate including the capital cost and annual operations.
and maintenance costs.
3.
SOUTH LANDFILL
3.1.
Bxcavation of the Basin Road Area
DESCRIPTION: The portion of the landfill underneath and to
the ~ast .of B~sin Roaq . (Le. ,all of the land.fill currently on .
Delaware property) . shall be excavated and backfilled with clean
fill, and the excavated soil shall be consolidated in the rest of
the south landfill.
PERFORMANCE STANDARDS:
3.1.1. A statistically significant number of samples (to be
analyzed for TAL metals) shall be collected to determine the
extent (lateral and vertical) of the contamination at the south
landfill on Delaware property underneath and. to the east of Basi~
. :Rqad (or. South .James Street). See Figure .4. .. .
3.1.2. The contaminant levels allowed to remain in soils at
the Basin Road excavation area shall 1) not contribute to ground-
water contamination; determined as follows: for soil left at the
Basin Road area (above or below the water table), a TCLP-like
leach test using clean ground water from near the Site, instead
of acetic acid, shall meet MCLsi and 2) shall protect human
health, determined as follows: the .levels set shall produce a
carcinogenic risk of no greater than lX10-s and a non-
carcinogenic risk below 1 for a utility repair/construction
.scenario. These so,ilclean-up criteria are subject to.EPA
approval. ..
3.1.3. Soils above the clean-up criteria on Delaware.
property, and on whatever Du Pont property necessary to allow
construction of the cap and to provide unlimited access to the
boat ramp at the west side of the James Street bridge, shall be
excavated and consolidated to the remaining portion of the south
landfill. .
. . 3. 1.4. . The excavation acti v,i. ti~s (and potentially other. .
remedial action tasks at the south landfill and south wetlands)
will require temporary restrictions or ie-routing of traffic.
Nearby residents and business shall be notified in a timely
manner of these activities. The scheduling of work shall be done
in such a way as to allow limited road access through this area
61
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during normal daily business hours for vehicles which do not have
an alternate route.
3.1.'5. A statistically significant number of confirmation
samples 'shall be collected to determine whether or not the soil
remaining in the excavation is below the clean-up criteria.
3.1.6. Once the excavation passes the
sampling, it shall be backfilled with'clean
approved source. Backfilling shall be done
minimize settlement and provide an adequate
confirmatory
fill from an EPA-
in such a way as to
base for"Basin Road.
'3.1.7.' After the excavation is backfilled, Basin Road shall
be reconstructed in accordance with DelDOT road construction
reqUirements. . , , ' ,
3.2.
In-situ stabilization
DESCRIPTION: The waste in the south landfill shall be
stabilized in-situ prior to capping. By stabilizing the waste, .
the ability of the metals to be leached. by the ground water will
be reduced to acceptable levels. A design optimization study
shall be performed to determine the appropriate stabilization
~gent to ,be used.
PERFORMANCE' STANDARDS:
3.2.1. Prior to stabilization, corings ~hall ,be collected
to adequately determine the depth of the waste material (TAL '
metals analysis'may be necessary).
3.2.2. After excavation and consolidation of the
soils/waste from the east portion of the south landfill (see
section 3.1) and the sediments from the south wetlands (see
section 4.1) into the remaining part ,of the south landfill, al~
of th~ soil, wa$te, and sedimen~ in the south landfill shall, be
stabilized in-situ as necessary to pass the TCLP test. '
Stabilization shall involve thoroughly mixing a cementitious or
pozzolanic reagent mixture without removing the soil from the
landfill.
3.2.3. Prior to stabilization, design optimization tests
shall be done in order to determine the proper nature and
quantity of the stabilization agent. A task of the remedial
design shall be to develop a work plan (subject to EPA approval)
,for the design optimization tests. Tbe choice of stabilization
agents is subject to EPA approval.
3.2.4. Stabilization shall continue until the soil, waste,
and sediment material passes the TCLP test and passes a TCLP-like
62
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test using background Site ground water instead of acetic acid.
MCLs shall be used as the criteria for the second test.
3.3.
8ou~h Landfill cap
DESCRIPTION: A cap with a minimum of 1a" of 1xlo-scm/s
permeability soil (or its ~quivalent>. shall be installed over the
portion of the landfill on Du Pont property (see Figure 28).
PERFORMANCE STANDARDS:
3.3.1. . Prior to excCt.vating 32 work-hours shall be spent
collecti~g and moving to a new environment any wildlife that is
residing in areas ..to be affected bt the remediation..
3.3.2. A landfill cap shall be installed that completely.
covers the portion of the south landfill that is on Du Pont
property.
3.3.3. The landfill cap shall be designed and constructed
in such a way as to limit to the maximum extent practicable any
encroachment on the south wetlands, the south pond, and the
Christina River. The wetlands constructed in place of the berm,
as described in paragraphs 3.4.1 and 3.4.2, shall be used to
. replace. the .loss of any wetland~caused by the construction of
the south landfill cap. . ...
3.3.4. The landfill cap shall have or be equivalent to
having a permeability of' lxlO-S em/sec or less with a minimum of
1811 of soil.
3.3.5. The landfill cap shall have a drainage layer
adequate thickness and appropriate permeability to ensure
any surface.water infiltration at the south landfill is
effectively .distributed.
of
that
3 . 3 . 6 . The
to function with
minimize erosion
settling so that
provide adequate
. .
.. .
landfill cap shall be designed and constructed:
minimum maintenance; to promote drainage and
or abrasion of the cover; to accommodate
the cover's integrity is maintained; and to
freeze protection for the cap.
3.3.7. The landfill cap shall bere-vegetated in such a way
as to provide a high quality wildlife habitat to the maximum
extent practicable (without endangering the liner). The types of .
vegetation shall be identified in the. remedial design and are
subject to EPA approval.
63
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,~
3.4.
site security and Berm Removal
DESCRIPTION: The berm shall be removed to the maximum
extent practicable without adversely affecting the south pond.
Also, in order to provide better site security to control
trespassing, additional fencing and a barrier of thorny plants
shall be installed around the entire south landfill area
including the landfill and the adjacent wetland area.
. PERFORMANCE STANDARDS:
3.4.1. The berm shall be removed to. the maximum e~ent
practicable without adversely affecting the south pond. As much
area as possible shall be graded to allow wetland hydrology to
develop. . "The south wetland 'restoration program," outlined in .
paragraphs 4.1. 10 and. 4 ~ 1.11 below; shall be performed in this
area as well.
3.4.2. Human access to the Site shall be limited to the
maximum extent practicable, without severely limiting the
migration of terrestrial animals into this area. This shall be
accomplished by using a combination of fencing and thorny plants.
The locations of the fences and the thorny plants (see Figure 28
for the approximate location of the fences and bushes) and the
choice of plants is subject to EPA approval.
3.5.
South Landfill Institutional Controls
DESCRIPTION: Institutional controls shall be placed on the
Du Pont property south of the Christina River to restrict future
land use, to notify the public of past land use, and to ensure
the protectiveness of the remedy.
PERFORMANCE STANDARDS:
. 3..5.1.. No excavation or constru~ti"on, except as neces.sary
to maintain the "integrity and the level of protectiveness of the
south landfill cap, shall occur once the cap is installed.
3.5.2.
purposes.
The south landfill shall not be used for residential
3.5.3. Once remediation at the south landfill is completed
and the vegetation is restored, the vegetation shall not be .
removed except for maintenance activities.
3.5.4. No drinking water" wells shall be installed at the
south landfill. No industrial water production wells shall be
installed in the Potomac aquifer at the south landfill.
64.
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3.5.5. The restrictions on the use of the property shall be
included in the deeds to the site property. The deeds to the
affected property shall also be modified to give notice to the
pUblic of past land disposal and,ot the fact that ,releases and
threats of releases of hazardous substances have affected their
respective parcels.
3.5.6. Additional measures may be required to implement the
institutional controls outlined in paragraphs 3.5.1 to 3.5.5.
3.5.
South Landfill Cost
DESCRIPTION: The estimated present worth cost of ,
'Alternative #5 is $14,~00,000. See Table 16 for details of the,
, cost estimate including the capital' cost and annual operations
and maintenance costs.
4.
SOUTH WETLANDS
4.1. South Wetlands Sediment Excavation
DESCRIPTION: The exact areal extent of unacceptable '
enviro~ental imp~ct (based on the clean~up crit~ria for ca~ium,
'lead, and zinc) shall be identified in 'the remedial ,design' ,
(Figure 29 shows the approxi~ate area requiring remediation),
subject to EPA approval. Sediments above these criteria shall be
excavated to a depth of one foot. The excavated sediments'shall
be stabilized and then disposed of in the south landfill prior to
placement of the south landfill cap as described in paragraphs
3.3.1 to 3.3.7 above. The area of excavation shall be backfilled
to return the area to original grade and re~vegetated to restore
the wetlands. '
PERFORMANCI;: STANDARDS:'
4.1.1. The f~llowing shall be the site-specific clean-up
criteria for the sediments in the south wetlands (these are
abSolute chemistry values normalized to grain size):
Lead
Cadmium
Zinc
1200
60
5600
ppm
ppm
ppm
Areas that 'exceed anyone of the above Site-specific clean-up
criteria in the south wetlands shall be excavated to a depth of
one foot. Other areas may require excavation to a depth of one
foot pursuant to paragraphs 4.1.2 to 4.1.6.
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4.1.2. A statistically significant. number (and a number
sufficient to direct remedial activities) of samples shall be
collected from the top 6" of the sediments in the south wetlands
(see area in Figure 38) to delineate areas containing sediments
above the site-specific sediment clean-up criteria. The'samples
shall be analyzed for the complete Target Analyte List (TAL) of
metals and grain size. The samples shall be collected from areas
estimated to have a minimum of 50% fines (percentage of sediments
that can pass through a 64 micron sieve).
4.1.3. A minimum of four solid phase sediment toxicity
tests (involving four toxicity test replicates and total organic
carbon (TOC), . grain size, and TAL metals analyses) measuring the
survival rate of Hyallela a~teca shall be performed in the south
wetlands in c;treas. ~here the cadmium,. lead, and zinc levels are
below the Site-specificclean~up criteria and above their AET
values (9.6 ppm, 660 ppm, and 1600 ppm, respectively, on an
absolute basis). A 30% reduction in survival compared to the
control sample shall be considered a significant impact. If
significant impacts are seen in any of the toxicity tests
performed for the south wetlands, EPA may modify the site-
specific clean-up criteria as described in Paragraph 4.1.1
(however, not below their respective AET values) for the south
wetlands, if appropriate, to protect the environment.
. : 4 .1." 4. . A minimum of four" solid phase sediment toxicity' .
tests (involving four toxicity test replicates and total organic
carbon (TOC), grain size,and TAL metals analyses) measuring the
survival rate of Hyallela azteca shall be performed in the south
pond. A 30% reduction in survival compared to the control sample
shall be considered a significant impact. If significant impacts
are seen in any of the toxicity tests performed for the south
pond, the south pond shall be -included in the area of the south
wetlands to be remediated if EPA determines that it is
appropriate to adequately protect the environment.
. .4.1.5. At.20%" of the chemistry sampling locations called
" for in paragraph 4.1.2 above that are outside of the expected
area of remediation (see Figure 29), surface water chemistry
samples shall be collected and analyzed for' total and dissolved
TAL metals. Areas where the dissolved concentration of anyone
Site~related contaminant, 'present also in the sediments at that
location, exceeds its respective Delaware acute SWQS shall be
included in the area of the south wetlands to be remediated. EPA
does not consider the "greater risk to human.health and
environment" ARAR waiver to be protective in these areas (i.e.,
in areas where the dissolved.concentration of a site-related
contaminant exceeds its respective acute SWQS, EPA no longer
considers the site-specific sediment clean-up criteria to be
protective) .
66
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4.1.6. Areas of the south wetlands that exceed anyone of
the Site-specific clean-up criteria for the south wetlands, as
revised if necessary, or where the dissolved metal concentration
of any , one 'Site-related contaminant (present in the sediments in
that particular area) exceeds its respective Delaware acute SWQS
shall be excavated to a depth of one foot. The excavation of the
sediments shall be designed and performed in such a way as to
minimize environmen~al damage and utilize, to the maximum extent
,practicable, excavation methods' such as vacuum dredging or other
alternative excavation'methods. The determination of 'whIch ar~as
exceed the Site-specific clean-up criteria and require ,excavation
is subject to EPA approval.
, 4.1.7. Prior to excavating 32 work-hours shall, be spent.
collecting and mov~ngto a new environment any 'wildlife that is
residing in areas to be affected by the remediation.
4.1.8. The excavated area shall be backfilled with clean
fill from an EPA-approved source and returned to original grade.
4.1.9. The excavated sediments shall be consolidated to the
south landfill prior to stabilization and capping in accordance'
with the performance standards under the "South Landfill" section
above. ' ,
, '4~1~10. The,wetlan~s,shall be s~ccessfully re-established.,
A complete restoration program 'shall be developed during remedial
design to address the excavated area and the newly created
wetland area. This program shall, at a minimum identify factors
whic~ are ~ey to a successful restoration program including, but
not limited to, replacing and regrading soils and re-
establishment of vegetation. The program shall be implemented.
other appropriate measures, including but not limited to,
periodic maintenance (i.e., planting) may also be necessary to
ensure long-term restoration. .
,4.1.11. ,A variety of grasses and hydrop'hyt'ic species common'
to the area shall be used to revegetate the wetland.
4.1.12.' Only if EPA decides to include the south pond in
the area of the south wetlands to be remediated, shall paragraphs
, 4.1.13 to 4.1.15 be complied with.
4.1.13. The south pond shall be excavated to a depth of one
foot. The excavation of the sediments shall be designed and
performed in such a way as to minimize environmental damage and
utilize, ,to, the maximum' extent practicable, excavation methods
such as vacuum dredging or other alternative excavation methods.
4.1.14. Paragraphs 4.1.6, 4.1.7, 4.1.8, 4.1.9"and 4.1.10
apply to the south pond also.
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4.1.15. Vegetation of similar type and quantity that
existed in the south pond prior to remediation shall be
successfully re-established.
4.2.
South Wetlands Long-term Monitoring
DESCRIPTION: Long-term monitoring of the entire south
wetland area shall be conducted to ensure that the remedy remains
protecti ve. '
PERFORMANCE STANDARDS:
4.2.1. A long-term monitoring plan shall be developed and
implemented to monitor ~e effectiveness of the remedial action
in the'south wetlands,to'make sure, that 'the Site-specific clean- '
up criteria remain protective of the environment and to make sure
the restoration is successful.
4.2.2. The monitoring plan shall include sediment
monitoring stations located in both remediated ,and unremediated
'areas (also include a 'site background location). TAL metals
analysis, TOC, grain size, acute and chronic toxicity tests
(prefera~ly using Hyallela azteca), and benthic density and
diversity measuremen~s shall be performed at these locations.
, 4.2.3. 'The monitoring plan shall !ncludemuskrat monitoring'
at the south pond and a background station every other year' ,
during the first five years after the remedy is implemented. The
monitoring shall include whole body tissue analyses for TAL
metals and organ histeopaths of the liver and kidney or blood and
hair analyses for TAL metals.
4.2.4. ' The monitoring plan shall 'include appropriate field
observations of plant growth and of the general conditions of the
,wet+ands of 'sufficient, detail to provide sufficien~ information
'to determine the successful establishment of the wetland. '
4.2.5. The monitoring plan shall determine the frequency of
monitoring arid reporting requirements. The reporting
requirements shall include a discussion of the results in
addition to data presentation. ,
4.2.6. The monitoring plan for the south wetlands shall
include the determination of a reference station to be'approved
by EPA. The reference station shall be representative of natural
background conditions in a non-tidal wetland and" preferably,
near the site (EPA does not consider RSl5 to be representative of
natural background conditions). Also since there is probably no
pristine area near the Site, a list of conditions that would be
expected in a pristine non-tidal wetland shall be developed
68
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through examination of aquatic conditions at areas in northern
Delaware or other appropriate areas.
, ,4.2.7. Performance standards 4.2.1 to 4.2.6 above are the
minimum requirements of the monitoring plan. The monitoring plan
is subject to EPA's approval. The discussion of the monitoring
results is also subject to EPA's approval. If at some time EPA
determines that this monitoring data indicates that the Site-
specific' clean-up criteria are no longer protective (for example,
the metals remaining in the sediments become morebioavailable
due to changing conditions and cause a greater impact), ,
additional remedial measures beyond those described in this ROD
may be required including further dredging.
4'.3.
Tide Ga1;e
DESCRIPTION: The tide gate shall be maintained as part of
the operations and maintenance of this area to prevent the
Christina River from entering the wetlands.
PERFORMANCE STANDARDS:
4.3.1. The tide gate shall, be maintained in such a way as
to allow,water to, discharge ,from, the sout~ wetlands,to the
Christina River but not allow water, and therefore' aquatic life,
from the Christina River'to enter the south wetlands. '
4.4.
Sou1;h We1;land 7nsti1;u1;ional Con1;rols
DESCRIPTION: Institutional controls shall be put in pla~e
in order to ensure the protectiveness of the remedy.
PERFORMANCE STANDARDS:
4'.,4.'1~ No drinking water wells shall be, installed' in the,'
south wetlands area. No industrial water production wells shall
be installed in the Potomac aquifer in the so~th wetlands area.
4.4.2. Paragraph 4.4.1 applies to all of the land between
the south landfill and Old Airport Road that is currently owned
by Du Pont and not just those areas classified as wetlands.
These restrictions shall be included in the deeds to the site
property. Deeds to the affected property shall be modified to
give notice to the public. of past land disposal and,of the fact
that releases and threats of releases of hazardous' substances
have affected the property.
4.4.3. Additional measures may be requir~d to implement the
institutional controls outlined in paragraphs 4.4.1 to 4.4.2.
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4.5.
South Wetlands Cost
DESCRIPTION: The estimated present
Alternative #2 .is $4,200,000. See Table
cost estimate including the capital cost
and maintenance costs.
worth cost of
17 .for details of the
and annual operations
5.
CHRISTINA RIVER
5.1.
Delineation of Area to ~ Dredged
DESCRIPTION: The exact areal extent of unacceptable
environmental impac~ (based on the clean-up criteria for'cadmium;
lead, and zinc) shall be determineq. .
PERFORMANCE STANDARDS:
5.1.1. The following shall be the Site-specific clean-up
criteria for the sediments in the Christina River (these are
absolute chemistry values normalized to grain size):
Lead
. Cadmium
.' Zinc
1200
60
5600
ppm
ppm
ppm
Areas that exceed anyone of the Site-specific clean-up criteria
in the Christina River, at sample depths described in paragraph
.5.1.4 below, shall be dredged until the river bottom in the
dredged area is b~low each Site-specific clean~up criteria
described above (revised as necessary pursuant to paragraph 5.1.3
below) .
5.1.2. A statistically significant number (and a number
sufficient. to direct remedial activities) of samples shall be
. coll'ec.ted from the"Christina River (see area in Fi~e 39) to. .
delineate areas' containing sediments above the Site-specific
sediment clean-up criteria. The samples shall be analyzed for
the complete Target Analyte List (TAL) of metals and grain size.
The samples shall be collected from areas estimated to have a
minimum of 50% fines (percentage of sediments that can pass
through a 64 micron sieve).
5.1.3. A minimum of four solid phase sediment toxicity
tests (involving four toxicity test replicates and total organic
carbon (TOC), grain size, and TAL metals analyses) measuring the
survival rate of Hyallela azteca.shall be performed in the
Christina River in areas where the cadmium, lead, and zinc levels
are below the Site-specific clean-up criteria and above their AET
values (9.6 ppm, 660 ppm, and 1600 ppm, respectively, on an
absolute basis). A 30% reduction in survival compared to the
70
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control sample shall be considered a significant impact. If
significant impacts are seen in any of the toxicity tests
performed .for the Christina River, EPA may modify the site-
specific clean-up criteria as described in paragraph 5.1.1 .
(however, not below their respective AET values) for the
Christina River, if appropriate, to protect the environment..
5.1.4. Each sampling station in Paragraph 5.1.2 shall have
four samples collected and analyzed for TAL metals~ The samples
shall be taken at depths of 0-6", 6-12", 12-18", and 18-24".
Exceedance of anyone site-specific clean-up crlteria, as revised
if necessary, at any depth sampled shall cause the area.
.represented by that sample to be included in the area(s) to be
dredged. The area of dredging is subject to EPA approva~.
Small, localized hotspots located away from the CIBA- .. .
GEIGY/Du Pont. facility may be excluded. from the dredging if EPA
determines that dredging the hotspot(s) is not cost effective and
leaving them in the river is protective of the environment.
5~2.
Christina River Dredging
DESCRIPTION: Hydraulic dredging of the river shall take
place in this area(s) of unacceptable environmental impact. The
dredged ~rea shall then. be covered with clean fill.
PERFORMANCE STANDARDS:
5.2.1. The area of unacceptable environmental. impact as
established pursuant to 5.1.4 above shall be dredged until the
river bottom in this area(s) is below the site-specific clean-up
criteria. .
5.2.2. Dredging shall only be carried'out when the river
current velocity is 1.5 feet per second (ips) or below
(approximately one. hour befQre and after slack. tide).
5~2.3. Dredging shall only take place during. the period of
November to March (inclusive) to avoid anadromous fish runs and
the time of greatest benthic activity.
5.2.4. All available engineering controls shall be used to
minimize, to the maximum extent practicable, transport of
sediments away from the dredging area. Exa~ples of the types of
controls to consider include increasing the percentage water
intake at the cutter head, using silt curtains, and/or using
hydraulic dredging equipment. .
5.2.5. Monitoring shall be performed downgradient from the
dredging area to monitor sediment transport. The remedial design
shall specify unacceptable levels of sediment transport that
. 71
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require dredging to be temporary halted or be modified. These
levels shall be submitted to EPA for approval prior to dredging.
5.2.6. Dredged sediments shall be pumped to a treatment
plant at the plant areas.
5.2.7. A statistically significant number of samples shall
be taken after dredging to ensure that the sediments remaining on
the river bottom are below the Site-specific clean-up criteria.
5.2.8. Clean fill from an EPA-approved source which meets
specifications to be determined during the remedial design shall
be placed in the dredged areas to return the river botto~ to its
original grade.
5.3.
Dewatering of Dredged Material
DESCRIPTION: The dredged sediments shall be dewatered and
properly disposed of either on-site or off-site.
PERFORMANCE STANDARDS:
5.3.1. The remedial design shall identify, subject to EPA
approval, the best method for properly handling the dredged
sediments and appropriately preparing them,for disposal~ " ,
Dewatering and/or stabilization 'may be used to provide adequate,
structural strength for disposal. If stabilization is required
and the sediments fail the TCLP test, the sediments shall be
stabilized in such a way as to pass the TCLP test.
5.3.2. The dredged sediments shall be properly prepared for'
disposal. The properly-prepared dredged sediments shall be
disposed. The order of preference for the disposal location of
the processed sediments shall be on-site in either the north or
the south landfills, and then off-site in an EPA-approved
disposal facility.
5.3.3.' If off-s1 te disposal will take place, TCLP tests
shall be performed on t~e sediments to determine if they are a
RCRA-hazardous waste prior-to any processing other than physical
dewatering. If they fail the TCLP test, RCRA land disposal
regulations shall be complied with, and the sediments shall be
stabilized so that they pass the TCLP test.-
5.3.4. Any stabilization required to meet RCRA land
disposal regulations shall involve thoroughly mj.xing the '"
excavated soils with a cementitious or pozzolanic reagent mixture
developed specifically to bind the metal constituents within the'
stabilized matrix. The actual stabilization agent shall be
identified in the remedial design and subject to EPA approval.
72
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The performance standard for the stabilized soil is that it shall
pass the TCLP test for metals prior to disposal.
5.3.5. Disposal, whe~her on-site or. off-site, shall occur
in a timely manner.
5.3.6. Wastewater generated from the treatment of
sediments shall be discharged to the Christina River in
compliance with the substantive requirements of a NPDES
for such activity or discharged toa POTW in compliance
necessary pre-treatment requirements.
dredged
permit
with any
5.4.
Cbris~ina Ri~er ,Long-termxonitoring
DESCRIPTION: . Long-term monitoring shall be conducted in the
Christina River to determine if the unremediated areas develop
unacceptable impacts and to confirm the long-term effectiveness
of the remedy.
PERFORMANCE STANDARDS:
5.4.1. A long-term monitoring plan shall be developed and
implemented to monitor the effectiveness of the remedial action
in the cqristina River and to make sure that the Site~specific
,'clean-up criteria remain protective of. the environment. ' '
5.4.2. The long-term monitoring plan shall include sediment
monitoring stations in the Christina River in both remediated and
unremediated areas (and include a site background station). TAL
metals analysis, TOC and grain size tests, acute and chronic
toxicity tests (preferably using Hyallela azteca), and benthic
density and diversity measurements shal'l be performed at these
locations. '
. 5.4.3. ' The, long-term monitoring plan shall. determine'
,frequency ofmonitorinq and reporting requirements~ The
reporting requirements shall include a discussion of the results
in addition 'to data presentation.
, .
5.4.4. The monitoring plan for the Christina River shall
include the determination of a reference station to be approved
by EPA. The reference station shall be representative of natural
background conditions in a tidal river environment and; ,
preferably, shall be near the Site (EPA does not consider RS15 to
b~ representative of natural background conditions). Also since
there is probably no pristine area near the Site, a list 'of
conditions that would be expected in a pristine tidal river'
environment shall be developed through examination of aquatic
conditions at areas in northern Delaware or other appropriate
areas.
73
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5.4.5. Performance standards 5.4.1.to 5.4.4 above are the
minimum requirements of the monitoring plan. The monitoring plan
shall be submi~ted to EPA for approval. The discu~sion of the
monitoring results shall also be submitted to EPA for approval. .
If at some time EPA determines that this monitoring data
indicates that the Site-specific clean-up criteria are no longer
protective (for example, the metals remaining in the sediments
become more bioavailable due to changing conditions and cause a
greater impact), additional remedial measures beyond those
described in this ROD may be required including furt~er dredging.
5.5.
'Christina River Cost
DESCRIPTION: The estimated present
'Alternative #5 is .$4,700,000. See Table
cost estimate including the capital cost
and maintenance costs.
worth cost of .
18 for details of the
and annual operations.
6.
CIBA-GEIGY AND DU PONT HOLLY RUN PLANTS
6.1. DESCRIPTION: The remedies in Section 6 address the
area shown in Figure 30. This area includes the complete CIBA-
GEIGY plant and a portion of the Du Pont Holly Run plant that has
contaminated SQils '(called "contaminated plant areas" .below).
Only about 3% ot the Holly Run plant area is included~ ."
6.2.
CISA-GBIGY an4 Du Pont Bolly Run Plants Institutional
Controls
DESCRIPTION:
contaminated plant
the protectiveness
past land use.
Institutional controls shall be placed on the
areas to restrict future land use,. to ensure
of the remedy, and to notify the public of
PERFORMANCE STANDARDS:
6.2.1.. The contaminated plant areas shall not be used for
residential purposes.
6.2.2. No drinking water wells shall be installed at the
contaminated plant areas. No.water production wells s~all be
installed in the Potomac aquifer at the CIBA-GE!GY corporation
Newport and Du Pont Holly Run plants.
. .'
6.2.3. The pavement and/or building structures located at
the Site property shall be maintained in a manner which limits,
to the maximum extent practicable, the infiltration of water.
74.
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6.2.4. The property owners, and/or their successors, shall
notify EPA, and/or its successors, of their intent to convey any
interest in the Site property. Such.conveyance shall not be made
without the prior written approval of EPA, and/or its successors.
No conveyance of title, easement, or other interest in the Site
property shall be consummated by the property owners, and/or
their successors, without adequate and compl~te provision for
continued maintenance of the propert~.
6.2.5. The property owners, and/or their successors, shall
notify EPA, and/or its successors, of any substantial' change to
their present operations at the Site at least six' months prior' to
the proposed change. .
6.2"6. Any change iil land' use following compl~tion of the
remedial action shall require the prior written approval of EPA,
and/or its successors.32
6.2.7. The respective Site owners shall modify the deeds to
the affected Site property to give notice to the public of the
past land disposal practices and of the fact that releases and
threats of releases of hazardous substances have affected the
property.
6.2.8. Additi~nal measures may be required to implement the
irist~tutiona'l. controls outlined. in'paragraphs 6.2.1 to 6.2.7. .
6.3.
Paving of contaminated Plant 'Areas
DESCRIPTION: The remaining unpaved portions of the
contaminated plant areas shall be paved.
PERFORMANCE STANDARDS:'
. 6. 3.1. '. The remaining unpaved. portions o~. the. contaminateci
plant areas shall be paved. .Pavingshall be done in such a way
as to minimize the need for mairitenance and to limit to the
maximum' extent practicable infiltration of water into the ground.
32paragraphs 6.2.4 to 6.2.6 are necessary for EPAto ensure
adequate protection of humap health and the environment from any
potential risks posed by the buried thorium. The u.S. Nuclear
Regulatory Commission (NRC) has commented to EPA that the
possibility exists for NRC itself to exempt this site from NRC's .
decommissioning regulations in 10 CFR Part 40.4. NRC would
require a strong set of institutional controls to be in place
before it would consider allowing the drums to remain at the
Site.
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6.4.
Plant Areas Ground Water Physical Barrier .al1
DESCRIPTION: A physical barrier wall (an actual wa11 that
limits migration of ground water to the maxi~um extent
practicable) shall be constructed to extend from the ground
surface to the base of the Columbia aquifer keying into the
aquitard which separates the Columbia aquifer and the Potomac
aquifer (see Figure 37 for the approximate wall location).
Ground water shall be recovered on ~he chemical plant side of the
wall to control any ground-water mound~ng that could affect
building foundations and that could force contaminated ground
water downward into the Potomac aquifer., Recovered gr9und water
, shall be treated prior to discharge.
PERFORMANCE' STANDARDS:'
, ,
6.4.1. A physical barrier wall (an actual wall that limits
migration of ground water to the maximum extent practicable)
shall be constructed to extend from the ground surface to the
base of the Columbia aquifer keying into the aquitard which
separates the Columbia aquifer and the Potomac aquifer (see
Figure 37 for the approximate wall location). The design shall
be such as to minimize the flow of Columbia ground water
underneath the barrier wall. The approximate barrier location is
shown in Figure 37. The exact location of the physical barrier
wall shall be 1dentified in the remedial design and subject to .
EPA approval.. The west end shall connect 'to' the barrier wall in
the north landfilL The east end shall extend 'far enough around
the CIBA-GEIGY plant to capture all of the Columbia and fill zone
ground water that has come into contact with contaminated soil.
6.4.2. The barrier shall have a permeability of 1X10-7
em/see or less.
6.4.3. Different barrier wall technologies including deep
soil mixing, sheet piles, geosynthetic membranes, an~ slurry
walls, s~all be evaluated in the reme~iial desi,qn. Of the ,
technologies that are implementable, the remedial design shall
identify the technology considered to have the longest life. .
More than one technology may be necessary depending on the wa11
location. EPA will make the final decision about what barrier
wall technology will be used.
6.4.4. Any unused piping found to cross the path ,of the
barrier wall shall be plugged or removed to a distance to be'
identified in the remedial design, subject to EPA approval, that
will keep a reservoir of'potentially.con~aminated ground water
from being formed adjacent to the barrier wall. Any used piping
shall be inspected to make sure it is in proper working condition
so that a seal can be formed between the pipe and the barrier
wall that is of sufficient quality as to prevent a preferential
flow path for the ground water from forming.
7(5
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'6.4.5. Ground-water recovery wells shall be installed in
sufficient number to control any mounding effect created by the
barrier wall. The wells shall draw the water table down to the
maximum eXtent practicable without affectinqthe water table
underneath the chemical plants in such a way as to cause
structural problems to buildings or pavement. The wells shall be
installed in accordance with appropriate State regulations.
6.4.6. All extracted ground water shall be treated and
discharged to the Christina River (or if determined by EPA during
the remedial design to be acceptable, the treated ground water
may be discharged to a publicly owned treatment works-POTW).
This treatment' shall include removing all contaminants (including
metals, organics, and, if necessary, radionucleides) necessary ~o
meet all. discharge requirements {especially compl~ance with. the
substantive requirements of a National Pollution Discharge
Elimination System [NPDES] permit if discharging to the Christina
River). If an air stripper or other vented system is used to
treat the ground water, secondary controls may be necessary'in
order to comply with Federal and State air ARARs (see Table 12)
and to ensure protectiveness of human health and the environment
(for protection of human health, secondary emission controls
shall be installed if the emissions from the air stripper cause a
greater than 1X10-6 excess cancer risk). It is anticipated that
.the treatment. sludges w.ill be haz.ardous waste. Any treatment.' '.
residues contalning tetrachloroethyl$ne Shall. be cQnsidered F002
waste. Disposal of any treatment sludges or other wastes shall
be in accordance with appropriate Federal and State regulations
(see Table 12).
6.5. . Health and Sarety Plan for Subsurrace Work
DESCRIPTION: A special health and safety plan shall be used
during any future subsurface work in the contaminated plant
areas. .
PERFORMANCE STANDARDS:
. 6.5.1. . A health and safety plan to protect workers against
exposure to contaminated soils shall be developed and complied
with for all future subsurface work.
6.5.2. The health and safety plan shall include a waste
management section. This section. shall discuss procedures for
testing any soil excavated post-remedial action to determine of .
it 'is 'a RCRA~hazardous waste. 'If so determined, the soil shall
be handled and disposed of as such.
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6.6.
contaminated Plant Areas Cost
DESCRIPTION: The estimated present worth cost of
Alternative #5 is $11,000,000. See Table 19 for .details of the
cost including the capital cost and annual operations and
maintenance costs.
7.
GROUND WATER
7.1.
Public Water supply Line
DESCRIPTION: To mitigate potential future risks from
qround water,.. the residences and businesses near the Si~e along
Old Airport Road. shall be placed on public water supply.
PERFORMANCE STANDARDS:
7.1.1. A public water supply line shall be installed along
.Old Airport Road as far as, and including, private well #16 of .
the RI, located at Cress Collision Service, Inc. (see Fiqure 40).
7.1.2. Residences and
private well #16, including
desiret~havepublic water
supply line.
7.1.3. Costs of public water usage shall be the
responsibility of the appropriate residence or business.
businesses between the Site and
well #16 (approximately 7 wells) that
shall ~connected to a public. water
7.1.4. Coordination shall take place with a local water
supply company that services this area (that is in compliance
with the Safe Drinking Water Act and its implementing
requlations) to ensure that the public water supply line is
proper.ly install~d.
7.1.5. The existing private we.lls at businesses or.
residences. that are connected to the public water supply line
shall be abandoned in accordance with State requlations.
7.2
Ground-water Management Zone
DESCRIPTION: Institutional controls including deed
restrictions and a qround-vater.management zone in the area of
the site (see Figure.33 for the approximate area) shall be .
established to limit the future installation of drinking water
wells.
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P~ORMANCE STANDARDS:
7.2.1. The State shall e~tablish and maintain a ground-
water management zone in the area of the site for'as long as
levels of contaminants remain that make the ground water unsafe
to drink. No drinking water wells shall be permitted to be
drilled in areas where the contaminant levels make ,the ground
water unsafe to drink or where the pumping of the well threatens
to spread the contamination.
7.3.
LODg-~erm M~Di~oring of ~he Ground .a~er
DESCRIPTION: Long-term monitoring of the Columbia and the
'Potomac aquifers shall take place 'to monitor the rate of "
, contaminant'migration and attenuation in the Columbia aquifer and
the rate of contaminant migration and attenuation in the Potomac
aquifer to the south.
PERFORMANCE STANDARDS:
7.3.1. A long-term monitoring plan ror the Columbia and the
Potomac aquifers shall be developed, submitted toEPA for,
approval, arid implemented to monitor the rate of contaminant
migration and attenuation in the Columbia aquifer (for the area
outside ,of the waste management area as shown in, Figure 32), 'and'
'to monitor the rate'of migration and attenuation of 'contaminants
to the south in the Potomac aquifer.
7.3.2. This plan shall outline which wells are to be'
sampled (new wells may be necessary if the current ones are not
in the right locations), type and frequency of analyses, and
frequency of reporting. The reports shall include a discussion
of the monitoring results. At a minimum, for the Columbia
aquifer, th~ monitoring shall include sampling MW-21A, MW-23A,
MW-24A,MW-25A, and MW-2~A for metals twice per year. For the
Potomac aquifer, the monitoring shall ~nclude sampling ~-6B,' MW-
18B, MW-21B" and MW-26BS for metals twice per year. If any 'of,
the Site-related contaminants migrates to anyone of these wells
at a level sufficient to produce ,a risk of either 1X10-6 for.
carcinogenic risks or 1 for non-carcinogenic risks, EPA, in
consultation with DNREC, may require active remedial measures
(such as restoration or containment of the ground water) beyond
those described in this ROD at that time. The monitoring
reports, including all of the appropriate information, shall be
submitted to EPA for approval. '
7.3.3. The monitoring plan shall also provide for wells in
each aquifer in the waste management area to help monitor the
effectiveness of the remedy in these areas.
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7.3.4. Monitoring for thorium shall take place every six
months by sampling monitoring wells MW-33, .SM-l, SM-3, and SM-4
for t~orium-232 and its daughter products and gross alpha and
beta radiation. The detection limits shall be low enough to
provide adequate data to determine if a release is occurring.
Monitoring for thorium will stop if all of the thorium is ever
removed from the north landfill.
7.4.
Ground-water Cost
DESCRIPTION: The estimated present
Alternative #2 is.$1,400,000~ See Table
cost estimate including the capital cost
and maintenance costs.
worth cost of .
20 for details of the
and annual operations
8.
OTHER MISCELLANEOUS PERFORMANCE STANDARDS
8.1. DESCRIPTION: Below are other performance standards
that apply to several areas. of the site or the Site as a whole.
8.2.
~erations and Maintenance Plan
D~SCRIPTION: An operati~ns and' maintenance plan .shali be
~eveloped and implemented for each portion of the remedy.
PERFORMANCE STANDARDS:,
8.2.1. The plan shall include a list of all vendor-required
maintenance activities.
. 8.2.2.' The plan shall include a list of potential
operations. and maintenance.problems and their proposed solution.
8.2.' 3 . Th~ plan shall include a 'list' 'of all required
inspections and general guideline~ for the inspections.
8.2.4. The plan shall include operating instructions for
the qround-water recoverY and treatment system.
8.2.5.
forms.
The plan shall include reporting requirements and
8.2..6.. .The .plan shall include health and. safety
requirements.
8.2.7. The plan shall include .tasks to inspect, document,
and repair any erosion problems along either the north or the
south river bank.
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8.2.8. The'plan shall include tasks to inspect, document,
and repair any pavement or other problems that contribute to the
infiltration of water in the contaminated plant areas.
8.2.9. Performance standards 8.2.1 to 8.2.8 are the minimum
requirements of the operation and maintenance plan. The plan,
including all of the appropriate information shall be submitted
to EPA for approval. '
8.2.10.
carried out.
All requirements of the approved plan shall be
8.3.
Brosion Control Plan
DESCRIPTION:
implemented.
An erosion control plan shall be developed and
PERFORMANCE STANDARDS:
8:3.1. An erosion ,control plan shall be developed and
implemented which outlines procedures to be used to control
transport of soil and sediment due to erosion, to the maximum
extent practicable and in accordance with the ARARs in Table 12,
for, all activities which present the potential for transporting
soils or'sediments. This plan shall also include'pr~cedures to '
'be used to properly discharge stormwater from the construction
areas.
8.3.2. This plan shall be developed in accordance with any
State and local regulations and shall be submitted to EPA for,
approval.
8.4.
Particulate Air Emissions
, DESCRIPTION: ,All remedial work shall b~' done in such ,a
manner,as to minimize transport of airborne particulate
emissions. '
PERFORMANCE STANDARDS:
8.4.1. As part of the remedial action health and safety
plan, levels of particulate considered to pose an unacceptable
health risk shall be developed along with monitoring requirements
to measure particulate counts.
8.4.2. Air monitoring shall be done at appropriate times to
ensure protectiveness of human health.
8.4.3. If the air monitoring results indicate that
p~rticulate counts are high enough that EPA concludes that
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unacceptable health risks are posed to people on-site or off-
site, appropriate measures shall be taken to reduce the
particulate count to safe levels off-site, and either to reduce
the particulate, count to safe levels on-site or to prot~ct the
workers through personal protective equipment.
8.5.
Was~e Kanaqemen~ Plan
DESCRIPTION: A waste management plan shall be developed to
handle any other wastes generated during remedial design or
remedial action for which waste management performance standards
have not previously been set.
PERFORMANCE ST~ARDS: .
8.5.1. A waste management plan shall be developed,
submitted to EPA for approval, and implemented to handle any
other wastes generated during remedial desiqn or remedial action
that have not previously had waste management performance
standards set. The plan shall outline how all Federal, State,
and local regulations will be complied with.
8.6.
ARMs
. " DESCRIPTION: The selected remedy shall meet all chemica'l,
location, and action specific ARARs that apply to the remedy
unless waived formally by EPA. .
PERFORMANCE S~ANDARDS:
8.6.1. The selected remedy shall attain, at a minimum, all
chemical, location, and action specific ARARs listed in Table 12
unless waived formally by EPA. .
8.7.
Babita't Value Balance Sheet
DESCRIPTION: A balance sheet shall be developed during
remedial design to keep track of and compare current and future
land use values.
PERFORMANCE STANDARDS:
8.7.1. A balance sheet shall be developed during remedial
design which accounts for all current habitat land use values at
the Site and accounts 'for all habitat land use values post-
remedial action. This balance sheet may be used by EPA to help
review the remedial design. The balance sheet shall a180
describe any temporary habitat losses caused by construction.
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STATtJ'l'ORY DB'l'ERKINATIONS
. EPA's. primary responsibility at Superfund sites is to
und~rtake remedial actions that are protective of human health
and the environment. In addition, Section 121 of CERCLA, 42
U.S.C. S 9621, establishes several other statutory requirements
and preferences. These requirements specify that when complete,
the selected remedial action for.each site must comply with
applicable or relevant and appropriate (ARARs) environmental
standards established under federal and state eQvironmental laws
unless a statutory waiver is invoked. The selected remedy also
must be cost effective and utilize treatment technologies or
resource recovery technoloqies to the maximum extent practicable.
Finally, th~ statute includes. a preference for remedies that
permanently and siqnificantly reduce the volume~ toxicitYi'or .
mobility of hazardous substances. The following sections discuss
how the selected remedy for this site meets these statutory
requirements.
PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
The selected remedy provides overall protection of human
health and the environment. +t protects human health by:
. 1. . Removing all soil from the ballpark containing qreat~r
than 500 ppm lead will eliminate the possibility of children..
being exPosed to unacceptable levels of lead during recreational
activities. .
2. Capping the north landfill to prevent exposure to
maintenance workers cutting grass from contaminated soils.
capping will eliminate. risks posed by this pathway. .
3.. Instituting health and safety plans for 'all subsurface
work in areas of contaminated soil at the Du Pont Holly Run/CIBA- .
GEIGY plants and at the south landfill. This will prevent
unacceptable levels of exposure for work activities to .
contaminated soils in these areas. .
4. capping the south landfill and providing improved Site-
security by modifications to the fencing and installation of
thorny plants around the south landfill and south wetlands will
prevent exposure to adolescent trespassers from contaminated
soils. capping and improving site security will address risks
posed by this pathway.
5. Paving the remaining areas of the CIBA-GEIGY plant and
contaminated area of the Du Pont Holly Run plant to prevent
exposure of maintenance workers cutting qrass to contaminated
soils. Paving will eliminate risks posed by this pathway.
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6. Installing a public water supply line to residents and
businesses along Old Airport Road to prevent any potential' future
exposure to contaminated grqund water caused by plume migration
to existing wells. Installing a water supply' line will eliminate
any potential risks posed by this pathway.
7. Establishing a ground water management zone to prevent
any new wells from being drilled into the plume. Preventing
installation of new drinking water wells will eliminate risks to
potential future userS posed by this pathway.
8. Excavating contaminated soils underneath and to the east
of Basin Road or South James Street to prevent future exposure by
construction workers to contaminated soils. Following excavation
and backfilling with clean fill, this, pathway will no longer pose
unacceptable rlsksto off-site workers. ' , .
9. Capping the north landfill, paving the contaminated
plant areas, installing a physical barrier wall along the river
in the area of the CIBA-GEIGY plant and the north landfill,
controlling the hydraulic head of the Columbia aquifer upgradient
of the barrier wall, capping and in-situ stabilization of the
,south landfill, excavating the s01l underneath and to the east of
Basin Road will limit to the maximum extent practicable any'
continued release of contamination. to the Columbia and Potomac
aquifers' and therefore minimize; to the extent practicable and
possibly prevent, the spread. of' contaminants in these two' ",' ,
aquifers. These parts of the selected remedy will help prevent
the potential for exposure of humans to contaminated ground
water. '
The selected remedy will protect the. environment by:
1. Removing sediments in the north wetlands (including the
north drainage way), the south wetlands, and the Christina River
that are above the Site-specific clean-up criteria and then
backfilling the wetland areas with clean sediments to prevent
exposure of aquatic life to levels ofcontamination:that EPA has
determined 'at this Site produce unacceptable risks to
environmental receptors~ There will be some residual risk to
environmental receptors in the remediated areas because, for
example, it will be impossible to prevent some contamination from
the unremediated portions of the wetlands and river to migrate to
the remediated areas. However, the risks will be greatly
reduced. '
2. Capping the north landfill, paving the. contaminated, "
plant areas, installing a physical barrier wall along 'the river
in the area of the plants and the north landfill, controlling the
hydraulic head of the Columbia aquifer upgradient of the barrier
wall (through ground-water pumping and treating), capping and in-
situ stabilization the south landfill, and excavating the soil
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underneath and to the east of Basin Road. This will greatly
decrease the loading of contaminants (mainly heavy metals) to the
river and the wetlands thus limiting to the maximum extent
practicable any continued build-up of contaminant levels in
sediments in the river and wetlands, and should significantly
improve (especially in the river) the surface water quality which
currently exceeds AWQC or SWQSs.
3. Removing the berm in the south wetlands will help
. mitigate adverse impacts to the floodplain caused by the volume
increase at the south landfill due to stabilization. This will
also eliminate any erosion of surface soils to the south wetlands
that are creating or could create an adverse impact to the
wetlands. Using this area to create wetlands in compensation for
wetlands 'lost.due to' other' construction actiyities at the south.
'landfill will greatly increase the habitat value of this section
of the Site.
4. Installing thorny plants around the south landfill/south
wetland area to decrease Site access by humans and yet allow
migration of terrestrial animals which are known to inhabit to
Site.
5. Invoking the "greater harm to human health and the
environment" ARAR waiver for the ground water. In the .Columbia .
. ' aquifer, . this will prevent potentia],. adverse affects. on . the south
wetlands caused by pumping the aquifer and. removing the naturai
source of recharge to the south wetlands and potentially
introducing contamination from the wetland sediments into the
Columbia aquifer. In the Potomac aquifer, invoking the ARAR
waiver will prevent more contamination from being introduced to
the portion of the Potomac aquifer underneath the waste
management area. It is believed that most of the contamination
in the Potomac aquifer is due to the use of process water wells
at the pigment plant drawing contamination down from the Columbia
aquifer to the Potomac aquifer. .Recovery wells.screened in the
. Potomac 'aquiferto.re~ediatethe portion.of.the plume .outside .the. .
. waste management area would have the same impact as the process
water wells' on the portion of the plume in the Potomac aquifer
underneath the waste management area. . .
6. Instituting long-term monitoring of both remediated and
unremediated portions of the wetlands and the river and long-term
monitoring of the muskrat population at the south pond. . The
monitoring of the wetlands and the river will ensure the selected
remedy remains protective. The muskrat monitoring will help
ensure that.the decision not to r~mediate the south pond.
continues to be protective of the environment.
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COMPLIANCE WITH APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENTS
The selected remedy shall attain all action, iocation, and
chemical specific applicable or relevant and appropriate
requirements for the Site which are listed in Table 12. Also
included in the table are criteria, advisories or guidance to be
considered (TBCs) for implementation of this remedy.
Several of the ARARs in Table i2 merit fUrther discussion.
First, RCRASubtitle C landfill closure regulations are not
considered ARARs for the north or the south landfill. Since the
south landfill wa~ closed prior to the enactment of RCRA, RCRA
landfill closure regulations are not applicable. Also, once the
st~bilization process is complete at ' the south landfill, tne",.
landfill, will no longer contain material similar to a RCRA-
hazardous waste and RCRA subtitle Cclosure regulations would not'
be considered relevant. Similarly, the north landfill was closed
prior to the enactment of RCRA, so RCRA landfill closure
regulations are not applicable. The closure regulations are
relevant since some of the waste in this landfill may fail the '
TCLP test. However, the closure regulations are not appropriate.
The main technical parts of the closure'regulations are that the
cap must be less permeable than the bottom liner to prevent a
bathtub effect and that the ground wa~er must be 'monitored to ,
'determina if, any contamination' is migrating froIQ the landfill.
Since the north landfill has no bottom liner, meeting the closure
regulations would only require a slightly impermeable cap~ EPA
has determined that only a slightly impermeable cap would not be
protective, and that the requirements of this 'ROD (a low
permeability cap) are required to be protective of human health
and the environment. As for the ground-water monitoring, since
the north landfill is adjacent to a river, since the Columbia
aquifer is already contaminated, and since active ground-water
remediation will not take place in this area, the monitoring
requirements as descri~ed in 40 CFR 264.98 are 'not" '
appropriate,33 a~d therefore, th~ closure regulations are not'
appropriate. '
Second, EPA has determined that for the overall protection
of human health and the environment at this site, compliance with
the MCL and non-zero MCLG ground water ARARs must be waived.34 ,
33Ground water monitoring at the north landfill will take
place to monitor for releases of thorium. Metals analyses will
, ,also be performed to monitor the levels of contamination but this,
will not be in accordance with 40 CFR'264.98. '
34The "greater harm to human health and the environment"
ARAR waiver also applies to the State of Delaware Regulations
Governing Public Drinking Water (revised 3/11/~1) sections 22.2,
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The ground water at the site is a Class IIA aquifer (i.e., the
aquifer system, both the Columbia and the Potomac, is a current
source of drinking water). Therefore, the NCP states that EPA's
obje~tive would be to return the ground water to, its beneficial
use by considering MCLs or non-zero MCLGs as ARARs. However, the
NCP does provide certain instances where ARARs may be waived.
Sections 300.430(f) (1)(ii) (C) (1-6) of the NCp outline six
different ARAR waivers, including the interim measure waiver, the
equivalent standard of per'formance. waiver, the greater risk t.O
human health and the environment waiver, the technical'
impracticability waiver, the inconsistent application' of stat~
standards waiver, and the Fund-balancing waiver.' The greater
risk to human health and the environment waiver may be invoked
when compliance with an ARAR will cause greater risk to human
heaith arid the environment than non-compliance. "
EPAhas concluded that the "greater risk to human health and
the environment" waiver should be invoked in this case. Active
remediation in the Potomac aquifer will cause the ground water
upgradient of the hydraulic barrier (underneath the waste
management area) to become more contaminated since the pumping
will cause a reversal of the natural upward flow of the ground
water into the Columbia aquifer and will pull more highly
contaminated ground water down into the Potomac aquifer (which is
how the Potomac aquifer originally became contaminated). EPA
, does,not'expectthe contaminant,plume in the Potomac aquifer to
expand. To date, the plume has exhibited limited migration'
potential due most likely to anions in the natural ground water
combining with the heavy metals and precipitating them out of
solution. Also, the seYected remedy for the other areas of the
Site will greatly decrease, if not eliminate, contaminant
migration from the Columbia aquifer to the Potomac aquifer (i.e.,
the source of contamination to the Potomac ,will be greatly
reduced, if not actually eliminated).
, ' Acti ve ',remediation i,n the Columbia aquif!!!r may cause the. ,
Columbia aquifer to become more contaminated because pumping'may"
cause the wetland area to become a recharge area for ground water
instead'of a discharge area for ground water. If the Columbia
ground water is recharged from the surface water in the wetlands,
higher levels of contamination may be introduced into the ground
water by the washing of contaminants from the sediments.35 As
22.3, 22.4, 22.6, and 22.1Q and the Delaware Regulations
Governing Hazardous Substance Cleanup (1/93), Section 9 for the
Columbia and Potomac aquifers.' ' ,
35The clean-up criteria for the sediments were set to
protect aquatic life only since there was not expected to be any
human exposure by direct contact to the sediments. However,
sediment contaminant levels that are protective of aquatic life
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with the Potomac aquifer, EPA does not expect the plume in the
Columbia aquifer to spread since the sources will be controlled.
Also, in the Columbia aquifer, ground water generally flows
toward the Christina River, thus keeping the ,plume from
expanding. .
As a result, EPA has determined that compliance with MCL and
non-zero MCLG ground water ARARs will cause a greater harm to
human health and the environment than non-compliance and invokes
the "greater harm to human health or the environment" ARAR
waiver. If, however, EPA determines through monitoring that the
migration rate in either the Columbia aquifer or the PQtomac
aquifer is larger or different than expected and that, if left
uncontrolled, the plume would pose a greater threat to human.
health or. the'envi~onment., appropriate remedial measUres beyond,
those called for in this ROD may be called for at that time. '.
Third, state SWQSs have been waived in the north wetlands,
the south wetlands, and the Christina River. In the river,
Federal AWQC were also waived. For both the north wetlands and
river, background sources of contaminants prevent ,site remedial
measures from attaining these ARARs requiring that EPA invoke the
"technical impractlcability" ARAR waiver. For the south
wetlands, substantially more sediments would have to be dredged'
than appears necessary to protect the wetlands. Stripping the
complete'south wetland just to attain sWQSs would cause more. harm
than good, thus EPA is invoking the i'greater'r~sk to human health
and the environment" ARAR waiver.
COST-EFFECTIVENESS
Of the alternatives that offer adequate protection of human
health and the environment, the selected remedy is the least
costly. It also meets all other requirements of CERCLA and
affords overall effectiveness proportionate to the cost. Also,
the net ,presentworth.of.$47.7 million is much. less ~xpensive
than the estimated cost, of $750 million for complete remov~l of
the contamination. For several areas of the site, cost had
little to do with the selection of the remedy for that area of
the Site because only one alternative passed the threshold
criteria of overall protection of human health and the '
environmerit and compliance .of ARARs. However, there are several
issues relating to the cost-effectiveness of the selected
alternative which do merit further discussion.
In the north landfill area, two alternatives met the
threshold criteria. The alternative that. provided the greatest
degree of overall protection to human' health and the environment
may, as potentially in this circumstance, not be protective of
human health through ingestion of ground water.
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also. happened to be the less costly of the two alternatives by
$400,000.
In the south landfill area, the stabilization and cap
alternative is $7 million more expensive than the cap only
alternative. However, since the waste material is in the water
table (and will continue to be even after the localized ground-
water mounding dissipates after capping), EPA determined the cost
was worth the extra degree of protection of the environment
because stabilization will limit to the maximum extent'
practicable the migration of heavy metals to the river and the
south wetlands. Also, stabilization and capping meet.the
statutory preference for treatment as a principal element. EPA
has selected the stabi~ization alternative that does not includ~
the most costly cap.
In the Du Pont Holly Run and CIBA-GEIGY plant areas, the
alternative involving the physical barrier wall along the river
was selected over the circumscribing physical barrier wall'
because it will provide the same degree of protection of the
environment and yet will cost $5 million less. In the Christina
River, dredging was selected over capping. EPA has determined
that since capping of the river sediments would permanently
destroy an area of habitat (even though it would protect aquatic
life from the contaminated sediments), the dredging alternative-
'woqld still be the preferred alternative' even if the additional
costs to dredging associated with off-site disposal of-the
sediments (estimated at $8.5 million) is considered.
UTILIZATION OF PERMANENT SOLUTIONS AND ALTERNATIVE TREATMENT
TECHNOLOGIES TO THE MAXIMUM EXTENT PRACTICABLE
Of those alternatives that are protective of human health
and the environment, EPA has determined that the selected remedy
provides the best tradeoff in terms of long-term effectiveness
and permanence, reduction in toxicity, mobility, or volume
achieved ~ough treatment, _short~term-_effectiveness,
implementability, and cost, also considering the statutory -
preference for treatment as a principal element and considering
State and community acceptance.
For the ballpark, the north landfill, the south wetlands,
the Christina River, and the ground water, the threshold criteria
of overall protection of human health and the environment
dictated the choice of the selected remedy. For the south
landfill, a greater degr~e of overall protection of. the
environment and reduction of mobility through treatment played a
major role in the selection of stabilization and capping. For
the Du Pont Holly Run and CIBA-GEIGY plant areas, short-term
effectiveness, implementability, and cost dictated the decision
to select the alternative with the physical barrier wall along
the river instead of around the complete area of contamination.
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Also, the local community had expressed concern about an
alternative that would raise the water table in the town of
Newpor.t as would the alternative involving a circumscribing
barrier ~all.
As discussed in detail in the "Scope and Role of Remedial
Action" section, the only permanent solution to the principal
threats at the Site is complete removal of the north landfill,
the south landfill, and the CIBA-GEIGY plant (including its
destruction). This is not practicai for several reasons. The
major reason is the cost. An estimated $750 million (includes
the cost of plant reconstruction) would be needed to 'perform a
complete removal, of the principal threats. The need ,to incur
costs of this magnitude is not warranted based on the risks to
human health and the'environment since for both current and'
'potential future 'conditions, 'engineering and institutional
controls can provide the necessary protection of human health and
the environment. Also, although the contamination could be
removed it can not be destroyed.
The only portion of the Site where a permanent solution was
employed that allows unlimited and unrestricted access is the
ballpark. EPA has determined that this is the only portion of
the Site for which a permanent solution is practical. EPA has
also determined that there ,are ,not alternative treatment
technoloq,ie~ or resource recovery options sui table for, '
implementation at 'this Site. Therefore, the selected remedy
utilizes permanent solutions and treatment technologies to the
maximum extent practicable. ' ,
PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT
From the results of the RIfFS, EPA has determined that
several areas of the Site are principal threats~ These include
the soil beneath,the CIBA-GEIGY plant, the north and south
landfi11s,'and the sediments in tne north drainag~ way (adjacent
to, the north 'landfill). The major contaminants of concern iri "
these areas are meta'ls. Stabilization is the best demonstrated
available technology (and the only available technology for a
site of this size) for the treatment of metals. In-situ and ex-
situ stabilization are not ,practicable in the north landfill
area36 because of 'the debris th~t was buried there. For
example, trash (glass, wood, paper, and cardboard), steel drums,
concrete rubble, steel work, and artificial marble have been
buried in the north landfill. There is little value in tearing
down the CIBA-GEIGY plant in order to stabilize the soil
36The remediation of the north drainage way is included with
the remediation of the north landfill since the north drainage
way cuts through the landfill and then runs along the base of it.
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underneath the plant since the north landfill and the CIBA-GEIGY
plant are one large contiguous area of contamination.
After giving careful consideration to available technologies
and Site characteristics, EPA has determined that treatment of
the south landfill is practicable. However, for the ClBA-GEIGY
plant, the north landfill, and the north drainage w~y sediments,
EPA has determined that treatment is not practicable. Therefore,
the statutory preference for treatment as a principal element has
been satisfied with the selection of stabilization as part of the.'
remedy at the south landfill. '
DOCUMENTATION OF SIGNIFICANT CHANGES
The selected remedy described in this ROD 6ontain~ a n~er
of significant changes from EPA's preferred alternative in the'
Proposed Plan. The changes were made in response to comments on
the Proposed Plan and consultations with the state of Delaware
and other federal agencies including the Nuclear Regulatory
Commission (NRC), US Fish and Wildlife Service (FWS) and the
National Oceanic and Atmospheric Administration (NOAA). The
changes are ,described below. ' .
L The cost of the dredging alternative for the Christina
River WaS reduced by approximately $8,000,000. The cost estimate'
'in the Proposed Plan was based on off-site disposal 'of the' ,
dredged material. The cost estimate in the ROD more accurately
reflects the cost of the preferred alternative in, the Proposed
Plan and the selected remedy for the Christina River which'calls
for the preference of on-site disposal.
2. In response to a resident's concern that contaminants
are transported during heavy rainfall from the south wetlands to
the south s~de of Old Airport Road, an area south of Old Airport
Road has been added to the ar~a of the south ,w.etlands from which
sediment sampling will take place. Th~ssampling may d~lineate
areas requiring 'remediation (see Figure 38). EPA verified the
resident's cQncern by observing evidence' that surface water had
flowed from the South wetlands over Old Airport Road after a
period of heavy rainfall. '
3. The public water supply along Old Airport Road will be
installed only to Cress Collision Service, Inc. and not to the
end of the road as originally intended. This change was the
result a Du Pont comment that due to the extent of the source
,control at the south landfill, ,it is not necessary 'at this time
to install the water line to the end of the road. (See comment
G.2 in the Responsiveness Summary.) .
4. The selected remedy does not include the river bank
cover along the north river bank at the north landfill and the
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CISA-GEIGY plant. This is in response
Interior comment which raised concerns
vegetation along the river bank. (See
Responsiveness Summary.)
5. In order to allow continued use of a boat ramp on the
south bank of the Christina River between South James Street and
the current South landfill fence, the boat ramp area shall be
excavated and backfilled with clean fill along with the rest of
the south landfill that is located on the state of Delaware's
property.
to a Department of the
about stripping the
comment H.ll in the
6. In response to comments by Du Pont 'and the Town of
Newport regarding the circumscribing physical barrier wall, EPA's
selected remedy now specifies that the physical barrier wall be
installed along the Christina River" only. (See comment 'F.l ,in'
the Responsiveness Summary.)
7. The sediment clean-up criteria in the ROD reflect slight
revisions from those presented in the Proposed Plan, mainly
because DNREC raised concerns ,that the criteria in the Proposed
Plan were not based on a large enough data base. EPA, NOAA,
DNREC, and the FWS have had numerous discussions in an attempt to
develop mutually agreeable sediment clean-up criteria.
-:The'ROp contains cleart-up.criteria developed,by' EPA after,
thoroughly considering the concerns of DNREC, NOAA~ FWS, .and the
comments of Du Pont. These criteria include sediment chemistry
values (on a normalized to grain size basis) which are slightly
below the values presented in the Proposed Plan. Sediments
containing normalized contaminant levels above the criteria will
be dredged. The criteria-also include performing a small number
of Hyallela azteca solid phase toxicity ~ests in each of,the
north wetlands, the south wetlands, the Christina River, and the
south pond to make that sure the sediment chemistry values are
protective. The values may. be lowered, if necessary to protect
. the environment,based on the results of the added toxicity.
: tests. The sediment clean~up criteria in the ROD have the
support of EPA, FWS, and NOAA. The complete details of the
development of the sediment clean-up criteria are contained in
the Administrative Record for the Site. The "Third and Final
Edition" of the "Memo To 'File: River & Wetland Remediation Goals
(Sediment Clean-up Criteria), Du Pont-Newport site, Third and
Final Edition" (dated,7/9/93) is attached to this ROD.,
8. The ROD contains specific language describing where the
long-t-ermground-water monitoring ts to take place and how the
results are to be used in evaluating whether the ground-water
ARAR waiver remains protective of human health and the
environment.
92
-------
9. Several ARAR waivers are included in the ROD that were
not discussed in the Proposed Plan. These include waiving
Delaware's SWQSs for the north and south wetlands and the
Christ'ina River for either "technical impracticability" (as in
the case of the north wetlands and the river) or for "greater
risk to human health and the environment" (as in the case of the
south wetlands). Federal AWQC are also being waived for the
Christina River by invoking the "technical impracticability" ARAR
,waiver. The waivers do not affect the remedy itself. The
selected remedy for the north and south wetlands and the'
Christina River is essentially the same as EPA's preferred
alternative in the Proposed Plan. ' ,
10. After discussions with the u.s. Nuclear Regulatory
Commission and review of its regulations, the selected remedy now
includes a task to' locate and mark the location of the thorium '
drums buried in the north landfill.
11. After further review of the sediment clean-up criteria
outlined in the Proposed Plan, mercury and copper have been
removed from the Site-specific clean-up criteria for the
sediments that is part of the ROD. EPA determined that the use,
of lead, cadmium, and zinc was enough to adequately delineate the
areas of sediments in the wetlands and the river that require
remediation. '
12. In response to' comments received from'Du Pont and'
concerns of the State of Delaware, the cap on the south landfill
in the ROD only has to meet RCRA Subtitie D requirements instead
of being a low-permeability cap identical to that called for at
the north randfill~ '
13. EPA's preferred alternative in the Proposed Plan for
the south landfill called for access road improvements and
erosion controls to be installed at the south berm. ,The selected
remedy calls for the berm to be removed to mitigate impacts to
'the 'floodplain' 'caused by the volume increase 'of ..the south' ,
landfill due to the consolidation~ stabilization, and capping.
Restoring this area to a wetland will help compensate for lost
wetlands due to the capping of the south landfill.
,93
-------
TABLE 1
, TYPICAL BACKGROUND
METAL CONCENTRATIONS
(RANGES IN MGIKG (PPM))
Shacklette & Shacklette &
Dragun; 1988 Boergner, 1984 Boergner, 1984
Metal (Typical) (Eastern, US Range) (North Delaware)
Antimony 0.6 - 10 < 1 - 8.8 < 1
Arse1?ic 0.1- 40 < 0.1 - 73 0.1 - 2.6
Barium 100 - 3,500 10 - 1,500 500
Beryllium 0.1 - 40 < 1 - 7 < 1
Cadmium 0.1 - 7.0
Chromium 5.0 - 3,000 1 - 1,000 50
CObB/t 1.0 - 4.0 < 3.'0 - 70 < 3 -. 5
Copper 2.0 - 100 < 10 - 700 < 1 - 10
Lead 2.0 - 200 < 10 - 300 20
Manganese 100 - 4,000 < 2 - 7,000 < 2 - 150
Mercury 0.01 - 0.8 0.01 - 3.4 0.051
Nickel 5.0 - 1,000 < 5 - 700 7 - 10
Selenium' 0.1 - 2.0 . < 1.0 - 3:9 0.5,
Silver O. 1 - 5.0
Thallium
Vanadium 20 - 500 < 7-300 30 - 500
Zinc 10 - 300 < 5 - 2,900 28
-------
MA TERIAL
. Garbage
. Trash (glass, wood, paper, cardboard)
. Steel Drums
. Lever Packs
., Sand and din
. Concrete
. Steel work
. Asbestos
. Ught ballasts - PCS's/PSS's
. Rubber - gasket material, tires from garage
. Nylon shutters
. Artificial marble - "Corian"
. Aerylates and latex emulsions
. Quinacridone tars
. Off-grade quality copper phthaJocyanine pigment
. Off-grade quality quinacridone pigment
. . . Off-grade quality "AftISir" pigment
'. Off-grade qU8lity Chromium Dioxide
"Mylar" recording tape
. "Aftlair" fines (30% mica) plus (70% TiqJ
. Off-grade quality Chro~ium Dio~de
floor sweeping and bags
. Thoriated nickel
. Dirt contaminated with zinc are
. Raw materials left in bag liners and drums
and leaks from drums
. .
Quinacridone . . .
Copper phtha/ocyanine
- "Aftlair"
- Magnetic products
TABLE 2
NORTH DISPOSAL SITE
WASTE DISPOSAL INVENTORY
DU PONT-NEWPORT SITE
ESTIMATED QUANTI7Y
Several tons
100 tons
Several hundred tons
Several hundred tons
Several thousand tons
5 tons
2 tons
A few tons
2 tons
4 tons
Several hundred Ibs.
1,000 tons
100 tons
Estimate 10,000-15,000 Ibs.
6 tdns .
Estimated 100,000 Ibs.
2 tons
20 tons of combined waste
Several hundred tons
Several hundred tons
A few tons
A few tons
A few tons
A few tons
-------
TABLE 3
EPA THRESHOW VALUE GUIDELINES (TVGs).
FOR SEDIMENT
ARSENIC 33 ppm
CADMIUM 31 ppm
CHROMIUM 25 ppm
COPPER 136 ppm
LEAD 132 Pprn
MERCURY 0.8 ppm
NICKEL 20 ppm
ZINC 760 ppm
OTHERS: BARIUM <20 (GREAT LAKES HARBOR SEDIMENT GUIDELINE)
ppm"=parts per million.
.EPA Threshold Value Guidelines, National Perspective on Sediment Quality (1985)
-------
TABLE 4
GROUNDWATER SAMPUNG SUMMARY
PHASE I REMEDIAL INVESTIGATION
DUPONT-NEWPORT SITE'
WeI' Number
Auauat. 1987
~1
SM-2
SM-3
SM-4
SM-5
DM-4
DM-6
PMU.7
DML-7
DM-6
WW-11
WW-13
MW-1A '
MW-1B
MW-1C
MW-2A
MW-2B
MW-2C
MW-3A
MW-3B
MW-3C
MW~
MW-4B
" MW-4C
Mw-sA
MW-SB
MW-SC
MW-6A '
MW~B
MW~ .
MW-7A
MW-7B
MW-7C
MW-8
MW-9
MW-11
MW-13
MW-14 .
MW-15
Necatro A 8
Nec88tro B8
x
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X '
X
X
X
X
8Reaic1entIaJ weD located on Old Airport Road proximal to Du Pont property.
December. 1987
x
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X'
X
X
X
X
X
Note: The Augu8t 1987 groundwater samples were analyzed for the complete Hazardous Substance List (HSL.)
parameters. The December 1987 groundwater samples were analyzed for HSL volatile organi~; HSL base/neutral semi-volatile
organics; barium, C8dmlum, chromium, copper, lead, nickel, zinc, arsenic, 8Odium, beryllium, silver and sulfate.
-------
TABLE 5
GROUNDWATERSAMPUNGSUMMARY: DUPONT.NBNPORTSITE
REMEDIAL INVESTIGATION: PHASE II & III
~
PHASE II ANALYSES
ROUND1-NOVEMBER1~
MW-SA
MW-SB
MW-SC
MW-11
MW-13
Upgradient Well
MW-16A
MW-17A
MW-17B
MW-18A
MW-19A
. MW-19B
Total Zn, Dissolved Zn
Total Zn, Dissolv8et Zn
Total Zn, Dissolved Zn
Total Zn, Dissolved Zn
Total Zn, Dissolved Zn .
TCL Organics, TAL Metals, Dissolved Metal, Cyanide.
TCL Volatiles, Total Metals: Dissolved Metals
TCL Volatiles, Total Metals, Dissolved Metals
TCL Volatiles, Total Metals, Dissolved Metals
. TCL Volatiles, Total Metals, Dissolved Metals
TCL Volatiles, Total Metals, Dissolved Metals
TCL Volatiles, Total Metals, Dissolved Metals
ROUND 2 - DECEMBER 1~
DMoS
DMoS
DML-7
DMU-7
MW-iA
MW-1B
MW-1C
MW-2A .
MW-2B
MW-2C
MW-3A
MW-3B
MW-3C
MW-4A
MW-4B
MW-4C
MW-SA
MW-SB
MW-SC
MW-6A
MW~B
MW'{sc
. MW-7A
MW-7B
MW-7C
MW~
MW-9
MW-11
MW-13
MW-14
MW.15
MW-16A
MN-17A
MN-17B
MN-18A
MN-18B
MN-19A
MN.19B
Necas1ro A
SM-4
SM-5
WW-13
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba,.Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
. Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
. Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba.
. Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn,. Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba.
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zri, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
TCL Volatiles, TAL Total Dissolved Metals
TCl Volatiles, TAL Total Dissolved Metals
TCl Volatiles, TAL Total Dissolved Metals
Tel Volatiles, TAL Total Dissolved Metals
TCl Volatiles, TAL Total Dissolved Metals
TCl Volatiles, TAL Total Dissolved Metals
TCl Volatiles, TAL Total Dissolved Metals
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
Total Zn, Cd, Ba, Dissol'.(ed Zn, Cd, Ba
Total Zn, Cd, Ba, Dissolved Zn, Cd, Ba
-------
TABLE 5 (Continued)
PHASE III Analyses
Drilled prior to Phase III
Drilled as part of Phase III
MW.188
MW.18A
MW.14
MW.7C
MW.7B
MW.7A
MW.13
MW.7C
MW~(F)
MW~
MW.11
MW-5C
MW-S8
MN-5A .
MW.198
MW4C
MW-3C
MW-38
DtM)
MW-8
MW.9
DM-U7
DM-l7
MW-48
MW-4A
MW~ (A) .
MW-298
MW.28B
MW-2BA
MW.21 B
t.fN-Z3A
t.fN.24A
t.fN-25A
MW-26BS
t.fN:26BD
t.fN.21A
MW.2A(A)
MW.1A(A)
MW-36A
MW-29A(A)
t.fN-29A(F)
t.fN-37A
DM-8
SM-S
MW-32B
t.fN-32A
MW-32F
MW-33C
MW-33A
t.fN-31 A
MW.15
MW.16A
MW.19A
MW.178
MW.17A
MW.2C
MW-28
MW-2A(F)
SM-3
MW.1C
MW.18 .
MW.1A(F)
MW-3A
St.4-4
SM-2'
MW-31.F
M'N-38F
MW-39F
MW-30B
MW-3OA
MW-30F
MW.28C
MW.27A
MW.26A
MW.20A .
MW.20B
MW-33B
MW-31 B
. MW-34B
. MW-35C
MW-35B
~-35A
Note: PrH'hMe III (drilled prior to Phase II~ well$ analyzed for TCl VOA; TAL Metals (Total/Dissolved) as part of
Phase III; Phase III (drilled as part of Phase II~ well$ analyzed for TCl VOA, SVOA Pest/PCBs; TAL Metals (TotaIIDissoIved)
-------
TABLE 6
MAXIMUM CONTAMINANT LEVELS (MCLs) &
MAXIMUM CONTAMINANT LEVELS GOALS (MCLGs)
FOR SITE-RELATED GROUND WATER CONTAMINANTS
INORGANICS
MCLG (ppb\ MCL (ppb\
6 6,
N/A 50
2000 2000
4, ' " 4
5 5
100 100
o N/A*
2 2
100 100
ANTIMONY
ARSENIC
BARIUM
'BERYLLIUM
CADMIUM
CHROMIUM (total)
LEAD (at tap)
MERCURY (inorganic)
, -NICKEL
ORGANICS
CARBON TETRACHLORIDE
o 5
o 5
100 ioo
600 600
75 75
o 5
o 5
o 2
BENZENE
CHLOROBEN Z ENE
1,2-DICHLOROBENZENE
1,4-DICHLOROBENZENE
TETRACHLOROETHENE
'TRICHLOROE'l'HENE
VINYL CHLOlUDE
RADIONUCI;oEIDES,
GROSS ALPHA ACTIVITY
o
15 picu/l
5 piCU/l
RADIUM-228
o
*EPA currently uses 15 ppb as an "action level" that provides
adequate protection to human health.
-------
TABLE 7
DNREC SURFACE WATER QAULITY STANDARDS
FOR SITE-RELATED CONTAMINANTS
CHRON.IC (DDb) ACUTE (DDb)
CADMIUM* 1.1 3.9 .
CHROMIUM (VI) ** 11 16
COPPER* 12 18
LEAD * 3.2 82
MERCURY 0.012 2.4
NI CKEL * 160 1400
ZINC* '110 120
ALUMINUM 87 750
IRON 1000 Nl~
BARIUM: No water quality criteria are available according to the
Hazardous Substance Data Bas~, 1992, the average background
concentration is 43 ppb with a range of 2 to 340ppb
*Values are hardness dependent; value listed is based on 100 ppm
as CaC03; measured valures in wetlands near the. north and south
landfills range from 104 to 183 ppm caC03
**US EPA
-------
TABLE 8
CHEMICALS POTENTIALLY CONTRIBUTING TO RISK BY MEDIA OF CONCERN
DU PONT-NEWPORT SITE
Parameter SOS CG HRP NDS CRSW BP CR *CFGW *PFGW
Seeps
Antimony X X X X X
Barium X X X X X X X X X
Benzo(a)anthracene X
Beryllium X X X X X X
bis(2-ethylhexyl)phthalate X
Cadmium 'X 'X X X X X X X
Carbon Tetrachloride X X
4-Chloroani/ine X
Cfl/orobenzene X.
Ch;omium X X X X X X X X
Cobalt X X X X X X X X
Copper. X. X X
1, 1-Dichloroethene X
Manganese X. X X X X X X X X
Mercury X
Nickel X X X. X X
Trichloroethene X X X X
Thalium X
'rrichloroethene X X'
Vanadium X" X X X
Vinyl Chloride X
Zinc X X X X X X X X
Notes: SOS - South Disposal Area 50ils NDS - North Disposal Area Soils . CR Seeps - Christina River Seepage
CG - CIBA-GEIGY Plant Soils CRSW - Christina River Surface Water CFGW - Columbia Formation Groundwater
HRP - Holly Run Plant Soils ". . . BP - Ballpark Soils PFGW - Potomac Formation Groundwater
* Only four Columbia Formation wells were screened by the concentration-toxicity screen. No other screening was done for
the Columbia Formation wells. All the Potomac Formation wellls were screened by the concentration-toxicity screen.
-------
~
(YEARS)
Ballpark
North Landfill
South Landfill
Christina River
CIBA-GEIGY Plant
Holly Run Plant
Ground Water
: RECEPTOR
'Children (Ages 6-14)
Maintenance Worker
Maintenance Worker
'Construction Worker
Trespasser (Adult)
Trespasser (Adolescent)
, (Ages 14-23)
Swimmer (Adult)
Swimmer (Children)
Non-swimmer (Adult)
Non-swimmer (Children)
Maintenance Worker
Construction Worker
Maintenance Worker
Resident (Adult),'
TABLE 9
EXPOSURE
TIME (HOUJ~S/DAY)
4 Hrs/Days
8
8
8
4
4
3
3
3
3
8
8
8
2 liters/Day
EXPOSURE
FREQUENCY (DAY/YEAR)
39
2
80
48
48
39
39
39
39
6
80
56
365
EXPOSURE
DURATION
9Years
45
45
2
30
9
30
9
30
9
45
2
45
30
-------
CARClNO-
AREA OF INTEREST POTENTlAL RECEPTOR* GENIC RISK
Ballpark Recre~tlonaJ (Chlld)-- 7.2X1U7
North Landfill Maintenance Worker 4.1X10-6
& Holly Run
South Landfill Maintenance Worker 9.0x10-6
Construction Worker*** 2.Bx1U7
Trespasser (Adult) 7.0x10'7
Trespasser (Adolescent) 4.9x10.7
Christina Recreational (Child)** 9. 1x 1 0-6
River Recreational (Adult) 6. 6x 1 0-6
CIBA-GEIGY' Maintenance Worker 1.4x10.5
Plant Construction Worker 1.1x10.5
Ground water Residential (Adult)**-
Columbia Aquifer 3.0X10-4
Potomac Aquifer 4.6X10-6
* Exposure routes for these receptors included
Inhalation, ingestion, and dermal contact. a~
appropriate for each scenario. .
** The total risk associated with the Site to a Child
partaking in recreational activities is the sum of the
risks associated with the ballpark and the river. For
non-carcinogenic riskS, the total Hazard Index is 0.42.
*** Potential future use only. .
TABLE 10
HAZARD If:lDEX
WITHOUT LEAD .
0.16
0..075
0.0027
0.70
0.032
0.074
0.039
0.016
0.068
6.0
170
3.6
HAZARD INDEX
WITH LEAD
0.38
4.0
0.93
3.0
0.96
1.9
20
26
190
5.9
-------
TABLE 11
BVALOATXON CRXTERXA
OVerall Protection of Human Health and the Environment:
Addresses whether the remedy provides adequate protection and
describes how risks posed through each pathway are eliminated,
reduced or controlled through treatment, engineering controls, or
institutional controls.
Compliance witb ARARs: Refers to whether a remedy will meet all
Applicable or Relevant and.Appropriate Requirements (ARARs) of
Federal and State environmental. statutes and/or provides grounds
for' invoking a waiver.. .Italso addresse~ whether Or not the
remedy complies' with' advisories, criteria, and guidance that EPA
and DNREC have agreed to follow.
Long-Term Effectiveness and Permanence: Refers to the magnitude
of residual risk and the ability of a remedy to. maintain reliable
protection of human health and the environment. over time once
clean-up standards have been met.
Reduction of Toxicity, Ko~ility, or Volume Through Treatment: .
Relates ~o the anticipated performance of the treatment
tecpnoloqies with respe9t to these criteriq. .
Short-Term Effectiveness: Refers to the period of time needed to
achieve protection, and any adverse impacts on human health and
the environment that may be posed during the construction and'
implementation, until clean-up standards are achieved.
Xmplementability: The technical and administrative feasibility
of a remedy, including the availability of materials and services
needed to implement a particular option.
Cost: The'following costs are evaluated:. . estimated capita~~
operation and maintenance, and present worth.
State Acceptance: Indicates whether, based on its review of the
feasibility study and the Proposed Plan, the support agency
concurs with or opposes the selected remedy.
community Acceptance: Relates to the comments received. from the
public, including the Potentially Responsible Parties, during the
. public. comment. period for the Proposed Plan.
-------
TABLE 12
APPLICABLE
OR. RELEVANT AND APPROPRIATB RBQUIRBMBHTS
AND TO BE CONSIDERED MATERIAL. (TBCe) .
DU PONT-NEWPORT SITE
(ABARe)
ARAR Applicability 10 Area of
ARAR or TBC LepI alation (]aa RequiraDeDt SyJIOIIIia SeIectat Remedy Cooocm
L CHBMICAL SPBCIFIC
A. Water
1. Safe Drinking Water 42 U.S.C. 6 JOOf ~!!;9.
Act
. a. Maximum 40 C.F.R 6 141.50-51 Relevant. Non-enforceable health goals for public water supplies. The The "greater harm to human health and the GW
Contaminant Level and NCP requires that non-zero MCLGs shall be allained by environment" ARAR waiver has been invoked for
Goals (MCLGs) Appropriate remedial actions for ground water that is a current or both the Potomac and Columbia aquifers.
potential source of drinking water, where the MCLGs are
relevant and appropriate under ihe circumstances o[ the
release.
b. Maximum 40 C.F.R 6141.11-12 Relevant Enforceable standards [or public drinking water supply The "greater harm to human health and the GW
Contaminant Levels and systems (with at least fifteen service connections or used by environment" ARAR waiver has been invoked [or
(MCLs) Appropriate. at least 25 persons). The NCP requires that MCLs, for Ihose both the POlomac and Columbia aquifers.
contaminants whose MCLG is zero, shall be allained by
remedial actions for ground water that is a currenl or
potential source o[ drinking water, where the MCLs are
relevant and appropriate under the. circumstances of the
release.
c. Maximum 40 C.F.R 6141.11-12 Applicable Enforceable standards [or public drinking water supply Installation of public water supply line shall be done GW
Contaminant Levels systems (with at least fifteen seivice connections If used by at in such a way as to provide drinking water in
(MCLs) least 2S persons). MCLs apply to public water systems that compliance with these standards.
provide piped water for human consumption.
2. Health Effects To be Non-enfdrceable toxicity data for specific chemicals for use in To be considered where remedial action addresses NL,SL,
Assessment Considered public health 8ssessmenls. Also ;'10 be considered" are risk-based criteria or when selling clean-up standards CGIHR,
Carcinogenic Potency Factors an4 Reference Doses provided for the protection o[ human health. GW
in the Superfund Public Health Ev.alualion Manual.
1
-------
ARAR . AppIicabiUtylo Ala of
ARM or 11IC ..... CiIaIioa a.. . Requiralaat 8YIICJIIIII Sda:ted RaDcdy a-.
3. Interim Guidance on EPA OSWER To Be To be considered when remedbtl action addresses IOIIa that To be colllidered when lead Ia pre8eIIt aDd remedial BP,NL,
Eaaabilahlni Soli Lead Directive #9355."~ Coniidered cause a threat to human health throup direct contact, action addreaes lOll, that cause a threat to human SL.
Ceanup LeYeIa at dated 1218189 ingestion, or inhalation of lead. health through direct contact, ingestion, or Inhalation. COIHR
Superfund Sites
4. State of Delaware Sections 222, 223, 22.4, Relevant. Sets criteria for public drinking water supplies. These The "greater harm to human health and the OW
Regulations Governing. 22.6,22.10 and requirements are nol directly applicable since ground water environment" ARAR waiver has been Invoked for
Public Drinking Water Appropriate at the Site is used as a private.dirnking water supply. both .the Potomac and Columbia aquifers.
Revised March 11, 1991 However, under the circuOl8tancea of this Site, these
requirements are relevant and appropritate.
6. State of Delaware Sections 22.2, 22.3, 22.4, Applicable Sets criteria ror public drinking water supplies. Installation of public water supply line shall be done OW
Regulations Governing 22.6,22.10 in such a way as to provide drinking water in
Public Drinking Water compliance with these standards.
Revised March 11, 1991
7. Delaware ToRe The reports were adopted as policy by the DNREC To be considered for ground.water monitoring. OW
Comprehenaive Water Considered Secretary. Among these reports is the Groundwater Quality
Resources Management Management Report, July 1983, which provided Delaware
CommlUee Reports, with a number of tools for dealing with ground~water
December 13, 1983 contamination.
8. Clean Water Act Clean Water Act, Section Relevant Water quality criteria set at levels to protect human health These standards have been waived for the surface CR
303 and for water and fish ingestion and. protection of aquatic life in waier in the Christina River by invoking the
Appropriate streams, lakes, and rivers. "technical impracticaliility" ARAR waiver due to non-
Site related upstream soul'Oeli of contamination.
9. Delaware Surface Sections 3, 4, 5, 6, 8,9, Applicable Criteria are provided to maintain surface water for streams, 1. Any surface water discharge must meet these NL,SW,
Waler Quality 10, 11.1, 11.2, 11.3, 11.4, lakes, rivers, and standing water in wetlands of satisfactory levels if more stringent than Cederal regulations. CR,
Standards aJ amended, 11.6, 12 quality consistent with public health and recreational COIIIR
Feb. 26, 1993 purposes, the propagation and protection oC fISh and aquatic 2. These standards have been waived for the surface
: life, and other beneficial uses of water. water in the north wetlands and the Christina .River
by invoking the "technical impracticability" ARAR
waiver due to non-Site related upstream sources of
contamination. These standards have been waived Cor
the surface water in the lOuth wetlands by invoking
. the "greater harm to human heatlh and the
environment" ARAR waiver.
2
-------
ARAR Applicability to Ala 01
ARAR Cll'11JC LcpI (]IIIIoD a.. RequiraDeDt,~ Sc:Ia:taI Raacdy ~
B.AIr
1. Clean Air Act 42 U.S.C t 7401
a. Nallonal Emissions 40 C.F.R Part 61 Relevant Standards promulgated for air emissions from specific source Relevant and appropriate for potential releases of NL,
Standards (or and categories. Not applicable but may be relevant and vinyl chloride and radionucleides resuiling from CGIHR
Hazardous Air Appropriate appropriate for emissions from air strippers at Superfund gl'9ulid-water treatment.
Pollutants sites.
2. Delaware Ambient Air Tille 7, Delaware Code, Applicable EstablisheS ambient air quality stan!iards. Applicable for potential releases from air stripping of ALL
Quality Standards Ch 60, Regulation 3, ground water, excavation work, or other remedial
Section 6003 actions.
C. y.........--
1. Standards for Protection 10 C.F.R. Part 20 Relevant These standards are designed to limit radiation hazards Remediation must take place in such a way as to NL,
Against Radiation ' and caused by Nuclear Regulatory Commission-licensed activities. prevent over-aposure of radiation to workers or CGIHR
Appropriate The general requirement is that every reasonable effort to public. Discharges to air or water must meet specific
maintain radiation exposures "as low as is reasonably concentration limits for radionuc1eides. Waste
achievable" be made. This regulation also describes specific disposal must also meet any pertinent requirements.
radiation dose limits for the protection of workers and
memebers of the public, radioactivity concentration limits for
efl1uents, precautionary procedures, and waste diposal
requirements.
2. Delaware Radiation Title 16, Delaware Code, Applicable Establishes regulations for registration of facilities, licensing May 1M: applicable for work at the north landfill and NL,
Conlrol Regulations' 7405 ,oC malerlals, slandards of protection, safety requirements, the ground water pump and treat system at, thiS area. CGIHR
and nolificalion requirements.
IL LOCATION
SPECIFIC "
1. Coastal Zone 16 U.S.C. 1451 ~ gg. Appli~ble Requires that Federal agencies conducting or supporting On-sile remedial actions are required to be NL,SL,
Management Act of 15 C.I".R. Part 930 activities directly affecting the coastal zone, conduct or consistent, to the maximum extent practicable, with SW,CR,
1972; support those activities In a manner'lhat is consls,tent with Delaware's coastal zone management program. EPA CGIHR
Coastal Zone Act the approved appropriate Statc coastal zonc managcmcnt must notify Dclaware of its determination that the
Reauthorization program. (See Delaware's Comprehensive Updatc'and actions are consistcnt to the maximum extent
Amendments of 1990 Routine Program Implementation"Msreh 1993) pracllcablc.
3,
-------
ARAR AppIlclbility 10 Ala 0(
ARAR CJI' 11IC LepI aIaIioD ea.. Requinma1t SyaiJpIiI SeIa:8aI RaDaIy Cooam
2. The Archaeological 16 U.S.C' 469 Applicable Requirements relating to potential 1081 or destruction of ArCheoloaical and historical reIOU1'Ct8 have not been NL,
and Historical significant scientific, historical, or archaeological data identified to elate. HCJWeYeI', the Installatloa of the CGIHR
Preservation Act of physical barrier wall along the Christina RlYer has the
1974 potehtlal for disturbing archeological resources.
Further action will be .taken to Identify resources and,
if identified, action will be taken to mitigate any
allvei1c effeclS on thOlie resources that would result
from construction. If resources happen to be
identified in other arc88 (although no specific actions
will be taken to find), action will be taken to mitigate
any adverse effects on thOlie resources that would
resulf from Imptementation of the remedial action.
3. Protection of 40 C.F.R. Part 6, Applicable Sets forth EP A policy for carrying out provisions of Applicable since much of the remedial action Will ALL
Aoodplalns Appendix A Executive Order 11988 (Aoodplain Management) which take place within the SOO-ycar floodplain. Due to the
requires actions to avoid adve~ crfectS, minimize potential volume Incn:asc of the south landfill, the berm In the
harm, and restore and preserve mitural and beneficial values. south wetlands will be removed to mitigate the loss of
. . volume inside a floodplain.
4. Protection of Wetlands 40 C.F.R. Pan 6, Applicable Sets fonh EP A policy for canYing out .provisions of Applicable since the construction of the nonh and NL,SL,
Appendix A Executive Order 11990 (Protection of Wetlands) which south landfill caps will affect wetlands. SW
requires actions to avoid adverse effects, minimize potential
harm, and restorc and preserve natural and beneficial values.
S. Delaware Coastal Zone 7 Delaware Code To Be Controls the location, extent, aniltype of industrial Will be considered for consistency since the remedial ALL
Act, 7 Delaware Code Sections 7003, 7004 Considered development in Delaware's coastal areas. action involves substantial aquatic habitat and is
Chapler 70; Coastal. localed in Delaware's coastal area although not In the
Zone Act Regulations, defined coastal zone of this statute.
619193
6. Delaware Wetlands Sections 1,2,7 Applica~le Requires activilies that may adversely affect wetlands in Any substative requirements shall be mel since NL,SL,
Regulations Revised Delaware to be permitted. Permits must be approved by the wetlands will be destroyed and replaced in the north SW
June 29,1984 county or municipality having jurisdiction. drainage way; and dredged (or excavated) and
restored in the nonh and south wetlands. Since all of
the wetland. or remediation Is oonsldered 'on-slte", no
permit will be obtained.
4
-------
ARAR AppIicabilil)'lo An:a of
ARAR 01' 'l1IC LcpI atatioo a- RequiraDc:at SyoopIiI SdcdaI RaDedy o-u
7. Delaware Rqulationa Sectlona 1,3," Applicable Requires activities that affect public or private subaqueous Any substantive requirements shall be met since tbe Ni..,
Governing the Use of lands in the State be permiUed. remediation involves dredging of the Ouiltina River. Si..,SW,
Subaqueous Lands, However;no permit shall be obtained. CR
amended September 2,
1992
8. Delaware Executive ToRe General policy to minimize the adverse effects to rreshwater To be Considered ror weiland remediation and NL,SL,
Order 56 on Considered well.ands. restoration. SW
Freshwater Wetlands
(1988)
9. Governor's Roundtable ToRe General policy to minimize the adverse errects to rreshwater To be considered ror weiland remediation and NL,SL,
~eport on Freshwater Considered wellands. restoration. SW
. Wellands .(1989)
10. Ground Water BPA 440/6-84-002 To be Identifies ground water quality to be achieved during The BP A aquirer classification will be taken into GW
Protection Considered remedial actions based on aquirer characteristics and use. consideration during design and implementation or
Strategy or 1984 the treatment remedy.
Ill. ACI10N SPBCIFIC
A Ml8cellineoua
1. Council on 40 C.F.R. 1500.2(1) Relevant Requires use or all practicable mC!ins, consistent with the Institutional controls shall be added to the north and NL,SL
Environmental Quality and requirements of NEPA to restore and enhance the quality of south .Iandfill properties to make sure they remain
Appropriate the human environment and avoid or minimize any pOssibe wildlife habitat.
adverse errects upon the quality of the human environment.
2. Delaware Regulations Section 9 . Relevanl Establishes clean-up criteria ror hazardous waste sites. Only 1. Waived for ground water using the "greater haml SL,GW
Governing Hazardous and criteria considered relevant and ilPpropriate are for ground to human heallh and the environment" waiver.
Substance Cleanup, 1193 Appropriate water and soil (lxl0.Sj Hazard Index of Ij or natural 2. Applies to Ihe determination or soil clean-up
background if higher). criteria at the Basin Road ponion of the south'
landfill.
B. Wata'
1. Clean Water Act 40 C.F.R. Part 122-12S APplicable Enforceable standards for all discharges to waters of the Discharge limits shall be met ror all on-site discharges NL,
(CWA)j National United States. to surface water including treated ground water and CGIHR,
Pollutant Discharge wastewater rrom dewatering dredge material. Only CR
Elimination System substantive requirements shall be met and no permit
Requirements shall.be obtained.
5
-------
ARAR Applicability 10 An:a 01
ARAR or 11IC LepI CIIdoa a- R£quin:mmt SJaopIiI Sdccted Raacdy o-a
2. Genenl Pretreatment 40 C.P.R Part 403 Applicable Standards for dlacharge to POTW. Applicable ,hould the c:ltnded pound water, treated NI..,'
Relulationa ground water, or W81tcwater from dredge material be CGIHR,
discharged to a POTW. CR
3. Section 10 of the River 33 V.S.C. Section 403 Applicable PenniUing requirements for dredging. The rivn dredging will eomply to any subslantive CR
and Harbors Act 33 C.F.R. Part 320-330 ~uirements, but no pennit will be obtained.
4. State of Dela\Wre SccIiona 3, 4, 5, 6, 7, 8, 9, Applicable Contain requirements governing the location, design, Installation of any monitoring and recovery wells and NL,SL,
Regulations Governing 10 installation, use, disinfection, modification, repair, and the abandonment of wells shall meet all substantive SW,
Ihe Construction of abandonment of all wells and aisociated pumping equipment. requirements. CGIHR,
Water Wells, GW
January 20, 1987
5. Delaware Water Sectiona 3-6, 8-10, 11.1, Applicable Standards are established in order to regulate the discharge Applicable should the ground-water treatment system NL,
. Quality Standards, as 11.2,11.3,11.4, Jl.6, 12 into state waters in order to maintain the integrity of the involve discharge to surface water. CGIHR
amended, February 26, water.
1993
6. Delaware River Buin DRBC Ground Water Applicable Regulate restoration, enhancement, and preservation of ,Applicable If remedial action involves discharge of NL,
Commission (DRBC) Protected Area waters in the Delaware River basin. >50,000 gallonS/day average over any month or a CG/HR
Water Quality Regulation. No.4, 6(f), withdrawal of ground water'of 100,000 gallons/day or
9, 10; Water Code of the more average over any month.
Basin, Sections 2.20.4,
2.50.2
7. Delaware Regulations Sections I, 3, 5.05 Applicable Contain infonnation pertaining to water allocation pennits May be applicable for the ground-water reeovery NL,
Governing the - and criteria for their 'approval. system or the public water supply line. CGIHR,
AItocation of Water No pennlt required. GW
March I, 1987
8. State of Delaware To Be ' Policy for ground-water management. To be eonsidered In sening Ihe ground water GW
Groundwater' Considered management zone.
Management Plan
November 1,1987
Section 7, 8, 9, 10, II, 12, "
9. Delaware Regulations Applicable Contain water quality regulations for the dlacharging Into Applicable for potential discharge of treated ground NL,
Governing Control ,of 13 surface and, ground water. . . water into surface water. Also applicable for SL,
Water Pollution, stonnwater runoff into the Christina River. CGIHR
amended 6/23/83
6'
-------
ARM Apptic:abilitylo Area 0(
ARAR ell'11IC .LePI CIIadoIt aa. RcquiraDeot SyDOpIiI SeIrdaI RaDaIy c.-n
10. State of Delaware Sections 22.2, 22.3, 22.4, ~pliC8ble Establishes requirements for public drinking water supplies. Applicable for the establishment of public drinking GW
RegulatioDl 22.6, 22.10 water. service to reaidenll along Old Airport Road.
Governing Public
DrinkiDg Water
March 31, 1991
C. AIr
1. Control of Air EPA OSWER Directive To be: Policy to guide the selection of controls for air strippers at To be: considered in determining if air emissions NL,
Emissions from Air 9355.0-28 cOnsidered groundwater sitea aecording to the air quality status of the control$ are necessary for an air stripper because CGIHR
Strippera at Superfund site's location (i.e., ozone attainment or non-attainment area). N.ew Castle is In an ozone non-attainment area.
Ground Water Sources most in need of controls are those with
Sites, June 15, 1989 emissions rates in excess of 3 Ibs./hour or 15 Ibs./day
or a potential rate of 10 tons,year of total YOCs.
2. Delaware Regulations Regulations Number 2, Applicable Sets forth the requirement that a permit is necessary-to If emissions exceed 2.5 IbsJday then the substantive NL,
Governing the Control 19,24 operate an air stripper if emissions will exceed 2.5 IbsJday. requirements of the regulation must be: met. In CGIHR
of Air Pollution Section 2 describes general conditions. Section 19 deals with addition, the emissions from the air stripper must
odor. Section 24 deals with volatile organic compounds. meet the Ambient Air Quality Standards set forth in
Regulation 3 of 7 Delaware Code, Chapter 60,
Section 6003.
E. Sedimen~olids
l. Delaware Sediment and Seclion 3, 6, 9, 10, II, 15 Applicable Establishes a statewide sediment and stormwater A stormwater and sediment management plan NL,SL,
Stormwater Regulations management program. consistent with Delaware requirements must be SW,CR,
January 23, 1991 approved by EPA only before construction disturbing CGIHR
over 5,000 square (eet o( land can begin.
F. Waste Handling and
Disposal :
1. RCRA Sublille D 40 C.F.R. 258.6O(a) Relevant Closure requirements (or RCM subtille D landfills. Provides some technical. requirements (or the cap 8t SL
Landfill Regulations and the south landfill.
- Appropriate
2. Delaware Rcqulalions Sections 2, 5, 6 Relevant Establishes regulations to impleinent an improved solid waste Relevant and appropriate for the south landfill. SL
Governing Solid Waste and mal\agement program.
Appropriaie
7'
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ARAR AppIiI:ability 10 An:a 01
ARAR or TBC LC:pa CIadIm a.. Requin:mca'"8yD.opIiI ScIccIaI R.cmaIy ec-u
3. Delaware Rqulatloaa SEE BELOW SEE Delaware Regulations GOU'Cf1lII1J HazardoUi Wate Pan 261 SEE BELOW SEE
GoverniDg HazardOIll F.S, F.7, F.9, F.lI, F.l3, BELOW define "hazardous waste". The regulations listed below apply BELOW
Wate F.1S,F.17 to Ihe handling of such hazardous waste.
4. Resource Conservation SEE BELOW SEE .. Regulates the management of hazard~us was Ie, 10 ensure Ihe SEE BELOW SEE
and Rccovcl)' Acl of F.6, f7.8, F.IO, F.l2, F.14, BELOW safe disposal of wasles, and 10 provide Cor resource reoovel)' BELOW
1976j . Hazardous and F.16, F.18 from the envlronmenl by controlling hazardous wastes "from
Solid Wasle cradle to grave."
Amendments of 1984 Federal regulations
would not apply for those
regulalions which
Delaware has the
authority from EPA to
administer. .
S. Standards Applicable Qelaware Regulations Applicable' Establishes slandards for genera~ors of hazardous wastes Applicable to operator(s) of the wastewater treatment NL,
10 Genentors of Governing Hazardous including wasle detenninalion manifests and pre-transport plant if the wastes generated by the groundwater COIHR
Hazardous Wate Wasle, Part 262.10-58 requirements. treatment system Is a RCRA-hazardous waste.
6. Standards Applicable EP A Regulations, Applicable Eslablishes slandards for generalors of hazardous wasles Applicable 10 operalor(s) of Ihe waslewaler lrealmenl NL,
10 Generalors of 40 C.F.R Part 262.10-S8 including wasle delenninalion manifests and pre-lransport planl if Ihe wasles generated by the groundwater CO/HR
Hazardous Waste requirements. lreatment system is a RCRA-hazardous wasle. .
7: Standards Delaware Regulations Applicable Regulalions for owners and operalors of TSDFs which define Applies 10 onsile recovery and treatment systems NL,
for Owners and Governing Hazardous acceplable managemenl of hazar~ous wastes. which handle hazardous wasle COIHR
Operators of Waste, Pan 264
Hazardous Wasle (40 C.F.R Pan 264)
Trealmenl, Siorage,
and Disposal
Facililies (TSDF)
8. Standards EPA Regulalions, Applicable Regulations for owners and operators of TSDFs which define Applies 10 onsite recovery and lrealmenl syslems NL,
for Owners and 40 C.F.R Part 264 acceptable management of hazardous wasles. which handle hazardous wasle CO/HR
Operators of
Hazardous Waste
Treatment, Storage,
and Disposal
Facllilies (TSDF)
8
-------
ARAR AppIic:abilitylo Area 0(
AltAR 01' TBC LcpI CtaIioo a- Requin:mr:ot SyJIOII8iI Sda:IaI Raoedy a-n
9. RCRA Requirements Delawlre Replatloaa Applicable Requirements for storage of hazardous wlllte In storage Applicable for temporary .torage containeR and on- NL,SL,
for Use and Governln, Hu.ardoua containers. site treatment syatellll. SW,
Management of Waste, Part 264.170-178 CGIHR,
Containers CR
10. RCRA Requirements EPA Regulations, Applicable Requirements for storage of haZardous waste in storage Applicable for temporary storage containers and on- NL,SL,
for Use and 40 C.F.R Part 264.170- containers. site .treatment systems. SW,
Management of 178 CGIHR,
Containers CR
11. RCRA Requirements Delaware Regulations Applicable Requirements for storage or treatment of hazardous waste in Only applicable for onsite treatment systems and NL,SL,
for Tanks Systems Governing Hazardous tank systems. temporary storage tanks containing hazardous wastes. SW,
Waste, Part 264.190-199 CGIHR,
CR
12. RCRA Requirements EP A Regulations, Applicable Requirements for storage or treatment of hazardous waste in Only applicable for onsite treatment systems and NL,SL,
for Tanks Systems 40 C.F.R Part 264.190- tank systems. temporary storage tanks containing hazardous wastes. SW,
199 CGIHR,
CR
13. The Hazardous Waste Delaware Regulations Applicable Requires a pennit for the treatment, storage, or disposal of Any substative requirements will be met. NL,SL,
Permit Program Governing Hazardous any hazardous waste as identified or listed in Pan 261. But no permit will be obtained SW,
Waste, Part 122 CGIHR,
CR
14. The Hazardous Waste EPA ~egulations, Applicable Requires a permil for the Ireatmenl, storage, or disposal of Any substative requirements will be met. NL,SL,
Permil Program 40 C.F.R. Part 122 any hazardous wasle as identifi~ or listed in Part 261. But no permit will be obtained SW,
CG/l-II~,
CR
15. Identification and Delaware Regulations Applicable Identifies solid wastes which are regulated as hazardous Use to determine which materials to be disposed of ALL
Llsling of Hazardous Governing Hazardous wastes. are hazardous wastes.
Wastes Wastes, Pan 261 -
16. Identification and EPA Regulations, Applicable Identifies solid wastes which are regulatcil as hazardous Use to determine which materials to be disposed of ALL
Listing of Hazardous 40 C.F.R. Pan 261 wastes. are hazardous wastes. .
Wastes
9
-------
,
ARAR. Applicability to Area 0(
ARAR or me .... (]I8doa a.. RcquiraDmt.SyIqIIiI SdetcaI Rc:medy 00aIx:m
17. RCRA land Dlapoul Delaware RqullUoD Applicable Restrictions on land dispoeal of hazardous wastes. Appliea to remedial IdlOlllln the south landfill, the BP ,Nt.,
ReatrictlOlll Oovemln. Hu.anIou8 south wetlands, Ind the Cuutlna River only If Iny St.,SW,
Waste, Part 268 stabilization 18 done CI-8ltu and waste Ia hazardous. CR
.. Applies to dirt from the ballpark if it is hazardous.
18. RCRA land Dispoeal EP A Regulations, Applicable Restrictions on land disposal of h~rdous wastes. Applies to remedial actions in the south landfill, the BP,NL,
Restrictions 40 C.F.R. Part 268 south wetlands, and the Christina River only if any SL,SW,
.. stabilization is done CI-8ltu and waste Is hazardous. CR
Applies to dirt from the ballpark If It Is hazardous.
10
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TABLE 13
COST SUMMARY FOR
SELECTED REMEDY.
. E./. DU PONT, NEWPORT SUPERFUND SITE
(BASED ON 1992 DOLLARS)
CAPITAL COSTS O&M COSTS<') TOTAL
Ballpark 10,000 ..().. 10,000
North Landfill 3,947,000 8,153,000 12,100,000
South Landfill 14,007,000 266,000 . 14,300,000
South Wetlands 3, 111~ 000 1,046,000 4,200,000
Christina River 4,012,000 677,000 4,700,000
CIBA-GEIGY & 3,555,000 7,445,000 11,000,000
Du Pont Holly Run Plant
Ground Water 378,000 1,020,000 1,400,000
. Operation. & Maimen;pJce Costs, net presem wort/1 ~ 5~ discount rate for 30 years.
. .
-------
TABLE 14
REMEDIAL COSTS FOR THE BALLPARK
(Based on 1992 dollars)
TOTAL DIRECT COSTS
(including sampling,
excavation, site restoration)
5,200
MObilization & Demobilization
Health and Safety
Engineering Costs
, 60% of DC
~,100
Contingency
(20%)
8,300
1,700
,O&M
o '
TOTAL PRESENT WORTH ,COSTS
$10,000
-------
TABLE 15
REMEDIAL COSTS FOR THE NORTH LANDFILL
(based on 1992 dollars)
DIRECT COSTS:
La~dfill cover
Barrier wall.
Ground-water pump
and treat system
Wetlands remediation &
restoration
913,000
622,000
444,000
354,000
()ther
134,000
TOTAL DIRECT COSTS
$2,467,000
Mobilization .& Demobilization
Health & Safety .
Engineering Costs
Wetlands Mitigation Plan
30% of .DC :
740,000
$3,207,000
Wetlands Contaminant Delineation
71,000
$3,278,000
Contingency
(20%)
656,000
O&M (5% Discount Rate, 30 Years):
Wells/Pumps-, Cover, Misc.,
Treatment System
Long-Term Monitoring
93,000/Event, 12 Events
7 , 580 , 000'
573,000
TOTAL PRESENT WORTH COSTS
$12,100,000
-------
TABLE 16
REMEDIAL COSTS FOR THE SOUTH LANDFILL
(~ased on 1992 dollars)
DIRECT COSTS:
Cover
Berm removal/site security
Excavation, backfill, pavement"'
Stabilization '
800,000
92,000
1,342,000
6,748,000
TOTAL DIRECT COSTS
$8,982,000
Mobilization & demobilization
Health & safety, '
Engineering costs
30% OF DC
2,695,000
11,677,000
CONTENGINECY
(20%)
2,335,000
14,012,000,
O&M (5% DISCOUNT RATE, 30 YEARS):
COVER, ACCESS ROAD, FENCING
18,000/YEAR '
266,000
TOTAL PRESENT WORTH COSTS
$14,300,,000
-------
TABLE 17
REMEDIAL COSTS FOR THE SOUTH WETLANDS
(based 00 1992 dollars) .
DIRECT COSTS:
Site clearing & sediment
removal .
Stabilization & consolidation
Confirmatory testing
Restoration
Other
128,000
947,000
88,000
464,000
51,000
TOTAL DIRECT COS~S
.$1,678,000
Mobilization .& demobilfzation
Health & safety
Engineering costs
Wetlands mitigation plan
~O% OF DC
672,000 -
Wetland contaminant delineation
2,349,000
244,000
2,593,000
518,000
Contingency
(20%)
3,111,000
O&M (5% DISCOUNT RATE, 30 YEARS):
. Maintenance
298,000
50,000 for five years.
17,000.for.next- five years.
3,000 for-last twenty_years
Long-term monitoring
748,000
$103,000/event, 12 events
46,000/event, 3 events
TOTAL PRESENT WORTH COSTS
$4,200,000
-------
TABLE 18
REMEDIAL COSTS FOR THE CHRISTINA RIVER
(based'on 1992 dollars)
DIRECT COSTS:
Dredging
Sediment dewatering
Disposal at north landfill
Water treatment
TOTAL DIRECT COSTS:
Mobiiization & demobilization
Health & safety
Engineering costs
40% OF DC
River contaminant delineation
CONTINGENCY
(20%>,
O&M (5% DISCOUNT RATE, 30 YEARS):
Long-term monitoring
$110,OOO/event, 12 events
TOTAL PRESENT WORTH COSTS
192,000
892,000
375,000
10 ',000
$1,469,000
588,000
2,057,000
1,287,000
3,344,000,
699,00
4,012,000
677,000
$~,700,000
-------
TABLE 19
REMEDIAL COSTS FOR THE CIBA-GEIGY AND.
DU PONT HOLLY RUN PLANT AREA
. (based on 1992 dollars)
DIRECT COSTS:
Paving
Barrier wall
Ground water pump
and treat
26,000
347,000
443,000
TOTAL DIRECT COSTS:
$816,000
. .
.. .
. Mobilization .& d~~obilization
Heal th & safety.
Engineering costs
40% OF DC
326,000
1,142,000
CONTINGENCY
(20%)
229,000
. CIBA-GEIGY plant modifications
2;200.000.
3,571,000
O&M (5% DISCOUNT RATE, 30 YEARS):
Paving
$1300/year
20,000
Riverbank cover
141,000
$9, 140lyear
Well maintenance
$22,000/year
336,000
Water treatment
$452,OOO/year
TOTAL PRESENT WORTH COSTS
6.948.000
$11,000,000
-------
TABLE 20
REMEDIAL COSTS FOR THE GROUN~ WATER
(based of 1992 dollars) "
DIRECT COSTS:
Potable water supplies
225,000
TOTAL. DIRECT COSTS
$225,000
Mobilization & demobilization
Health & safety'
Engineering costs
40%"OF DC
90,000
315,000
CONTINGENCY
(20%)
63,000
378,000
O&M (5% DISCOUNT RATE, 30 YEARS) .
Long-te~ monitoring
1,020,000
TOTAL PRESENT WORTH COSTS:
$1,400,000
-------
FIGURE 1
Site Location Map
E.I. Du Pont, Newport Super-fund Site
BANNING PARK
A •
Campgrounds
Newport
Approximate distance to nearest public water
supply well is 1.5 miles southeast of the Site
• Appro, tato
1.00 in.
art* m Mn*d to Unr «• gmnl Sit toeakn noi n» «Kflc Sk
-------
FIGURE 2
Site Layout Map
DUPONT
HOLLY RUN
PLANT
CIBA-GEIGY
NEWPORT PLANT
-------
B-10
PHASE III.OATA.
FIGURE 3*
Site Characteristics: Soil Contamination
APPROXIMATE LOCATION
OF CONTAMINATION
B-16
PHASE IIMTA.
*.v
NORTH<«'.
WETLANDS
TB-33
....PHASE UI.CATA
KEY
Soil Boring Locations
•*> Test Boring Locations
+ Hoty Run Borings
• Surfac* Grab Simple Location
B Phase I Test Pit (or SOS
Waste Characterization
B-1
PHASE III DATA
TOTAL METALS
tap*
Barium
gs
ManganiM
Mmiry
Off
Zinc
CONCENTRATION
(Ht/kg)
tO,200
4,480,000
Iro
19.600
33,700
6,400
T?;»O
NO
14,600
41/80
445,000
Simple depth. «M
July25,1»90
...PHA5EJII.J0ATA..
TOTAL METALS
Araenia • .: ...
Barium
•MM
Cjdmium
Chromium
ManoimM
Zinc
CONCENTRATION
(WAS)
«,-1-;-
20.900
-------
~
FIGURE 4
Relocated South James Street/Basin Road
Through Newport
Philadelphia Baltimore Railroad
CIBA-GEIGY
NEWPORT PLANT
SOUTH
DISPOSAL
SITE
: SOUTH WETLANDS>
^ Extended Area
of Original Landfill
Original Location
', ; of South James Street/
r Baskl Rood
REFERBKEMAftOdDOT
Contract No. 71 -02-007
Sheer No. 150 of 198
Page 500047f of The Administrative Record
NOTE: Boring locations are approximate.
'
-------
REFERENCE MAP: MOOT
Contract No. 71-02-007
StiMtNo. 156 of 198
Pbg> 203825 of TU AdminiHrotiv. R«cord
— 20
— 10
— o
3.5 16=
1 =
Boring R-12
A-1-b
Chemical Fill
11 =
5.5
4.5
W.OH=
20 12.0
40
13 =
23 =
13 =
13 =
14.0 24=
50
6.0
24 =
13 =
-40 5.0
1.0 19=
A-8
Organic
A-7-5
Organic
A-1-b
r2-7I21
FIGURE 5
Configuration of Borings R-9 and R-12
LocaHon of Borings R-l 2 and R-9
. 37
A-6
A-1-b
A-2-4
Sample No. 38
=
z
A-2-4
A-2-4
70.0 Sample No. 39
Decamp. Gneiss
s
s
=
=
ia Baltimore Haiiroad
IIIIIUIIIIIIIlUlllllllllllllllllllllUlimilHIIIIIIillllllllllllllHIIIIIillllHillllliiill
CIBA-GEK3Y
NEWPORT PLANT
^--70
=
=
REFERENCE MAT: MOOT
Conlrod No. 71-02-007
SUrtNo. 153 of 198
Pag* 203822 of The Administrative Record
20—1
Boring R-9
12=
4.5 1 =
2 =
12.5
1 =
23=
18=
18.5 2Q=
25 =
4.5 8=
24 =
10.5
17=
4.0 24 =
4.0
10=
8.0 23=
00 =
II II
A- A *
A A
A A
A A
A *
A A
A A
A A
A A
A A
A A
A A
A A
V*~l*
%
%
"v
k \ \ •>
x y x
k \ \ ^
I'A"
]
Topsoil
A-1-b (Fill)
Chemical Fill
A-8
Organic
A-1-b
A-2-4
Sample No. 9
A-1-b
A-2-4
A-4
A-1-b
10—\
o —
-10 —
-20 —
-30 —
-40 —
-50—
70.0
-70—
-------
FIGURE 6
Ballpark Soil Sampling Locations
(•^Approximate Properly
M I I I I I III I II II I M I M I M I I I I I I I I I I I I M
Railroad Tracks
M I I M I I I I I I I II I M M I I I I I I I I I I M M I I I I
Du Pont Holly Run Plant
CIBA-GEIGY Newport Plant
-------
FIGURE 7
Site Characteristics: Wetlands Sediment Contamination
PhilatUlfhU Baltimore Raibwui
DUPONT
HOLY RUN
WANT
AS:11
".*. NORTH*As-i
-------
FIGURE 8
Distribution of Sediment Contamination Enrichment Factors
for Metals in the Christina River
s
CO
2 3.
Miles Down Stream From RS15
NOTE. The Enrichment Factor Is the ratio of a normalized contaminant concentration to a normalized contaminant concentration at a reference station (in this case RS-15)
-------
FIGURE 8
(Continued)
100
§
ec
o
UJ
O
CC
5
S
-------
FIGURE 9
Simplified Geological Cross-Section of Site
ARE A Of
CROSS-SECTION
(Viewed from
from watt to east)
CIBA-GEIGY
PLANT
I.,.,....!.,,'!?..'!'.',' '.„>.»'...,.....
COLUMBIA FORMATION
LOWER POTOMAC FORMATl ON
-------
MW-3QF
ITA. L_
FIGURE 10*
Fill Zone Well Locations
Chromium
uST
Mramt*
VOCs"
t^-OtNawMw
MncMoKMUww
DUPONT
HOILYRUN
PLANT
CIBAGEK3Y
NEWPORT PIANT
SOUTH
LANDFILL
'SOL/rHWETLANDS
HI
TOTAL METALS
*_ ;_
WMnR
&&.
Chmjnium
StT
Bfer-
VinMtwrn
One
fl^ATA
CONCENTS
(M4»)
NO
3650
1
13.7
i
40.«
WION
•Chmtal ronwrlration. « reported tor Nowmb* 1NO umpire «tnt. CompM*dab on Iw bund inIhi Admirntntivi Rxwd
• WOC* • VoMto Organic Compound*
-------
FIGURE IT
Columbia Aquifer & Shallow Well Locations
Philadelphia Baltimore Ratlroad
tlllUIIIHIIilllllllHIIUIIlllllllliiuiiiiiiiii...
mar
DUPONT
HOU.YRUN
RIANT
•MW29A
•MW-37A
CIBAGEK3Y
NEWPORT
CONCENTRATION \
\
SOUTH
LANDFILL
'MW-U
'SOUTH WETLANDS.
NORTH*.
> WETLANDS >;
KEY
• Columbia Aoult.r Will Locrtoni
(wtto iciMMd In ColumUi Aquifer only)
Q StUlow Well Locaflons
(wills tcnmd In CahmHa Aqutlti and W ion*)
ConpMi «• on ta bwri to IN MuMMivi tognl
-------
FIGURE 12*
Upper Potomac Well Locations
Philadtlphia Baltimon Rat
IMIIIH11U11IUI0 H11MI Htf ItHIIIM Ml • mi iV
Comf W« dill on M Iwnd n IIM AdrnnMntiw Rmnl.
-------
FIGURE 13*
Lower Potomac Well Locations
\a Baltimore Railroad
IIIIHUIIIHIIIIIIHIMIIIIHIIIUIIIHIIIIIIIIIIIII
DUPONT
HOLLY RUN
PLANT
CIBA-GEIGY
NEWPORT PLANT
SOUTH WETLANDS
NORTH1
WETLANDS
PMO.PATA...
••VOCl.WDMIIi
n*n»wtadlo(ll(Winitw1tM
-------
FIGURE 14
Ground Water Contamination
in Columbia and Potomac Aquifers
BAUPARK
„„„„„„ ,,ll,,|,||HMMMIIMIIM«»'«l'"nm!MII'l"'"""«"»1""1'1""1 mWHINNIIIliljiil Mllllll
CIBA-GEIGY
CXJPONT NEWPORTPLANT
HCXiYRUN
PLANT
——~{ Extent of ground water contamination in the
_.„__; Potomac aquifer that exceeds MCLs and non-zero MCLGs
ITTH
Extent of ground water contamination in the
Columbia aquifer that exceeds MCLs and non-zero MCLGs
-------
FIGURE 15
Direction of Vertical Ground Water Flow
Columbia vs. Upper Potomac Zones
(Low Tide-December 13,1990)
BALLPARK
PhilatUlphia Baltimore Railroad
ii!H'H«iii|Aiiiiiii}iimiiiMiiwmiyMiiiMiijimiiiii,iiuiiiii
CIBA-GEIGY /•/ /
IEWPORT PLANT __/
Area of Discharge
(Upward Vertical
Gradient)
Area of Recharge
(Downward Vertical
Gradient)
-------
FIGURE 16
Direction of Vertical Ground Water Flow
Upper Potomac vs. Lower Potomac
(HlGHTide-December 13,1990)
'a Baltimore Railroad
iiMjjniimHUMiiHmuiuiimiiMHiimHH
CIBA-GEK3Y
NEWPORT
DUPONT
HOUYRUN
PLANT
Area of Discharge
(Upward Vertical
Gradient)
Area of Recharge
(Downward Vertical
Gradient)
-------
RW1-12
TOTAL METALS
Aluminum
MM
Cadmium
Chromium
•p*
Iron
e
ip*i
2.060.0
11
I
1
6
1
2,MO
I
FIGURE 17*
Characteristics: Surface Water Contamination
and Ground Water Seepage
DUPONT
HOU.YRUN
PIANT
COMPOSITE 3
G.WS.9..U
VOCs"
440.0
Cirtxm tWKhtoiide 310.0
MontarawM 3400
TUncnorofthm 3.200.0
WATER QUALITY CRITERIA
Pwmiiir
+ Haidness Dependent: value listed is based on 100 ppm as CaCOi; measured values in wetlands near the North and South Disposal sites
range from 104 to 163 com CaCPi
'Only contaminants «Nh data Dial noiedi »ie AmMml Water Quality Cituria in listed.
"VOCi. VolatUi Otganlc Compounds
ttOn* of the leaps consulting lie conposUt.
•
-------
FIGURE 18
Lead Data for Surficial Soil Samples
at the CIBA-GEIGY Newport Plant
BALLPARK
Philadelphia Baltimore Railroad
,l,,MM.HMIM,.UIMIHIMIl.IIM,HWMHl|,M,,HIM»,HMMM,,M,HMMMHIHM,MMWMH,|,11,,,,|1|milH ^
CIBA-GEIGY A0.JF'
Newport Plant
NORTH
LANDFILL
SOUTH
LANDFILL
SAMPLE
LOCATION
SS-69
SS-70
S5-71
SS-72
SS-73
SS-74
SS-75
SS-76
B-1
B-8
B-1Q
B-11
B-12
B-25
EA-1
EA-2
EA-3
EA-4
EA-5
EA-6
EA-7
EA-8
EA-9
TOTAL LEAD
(ppm)
100
30
ISO
1,400
150
1200
20
830
39
127,000
67,700
414
414
19.800
143
322
43
71
No Data
528
21
17
679
KEY
Buildings
• Non-validated Soil Sample
Location! and Data
• Samplu taken by Du P*MT
and ihown in Fig. 64 oi (he Rl
O Non-validated Soil Sample
location* and Data
(Fig. 64AinlheRI)
ppm = parts per million
-------
FIGURE 19
Sediment Characteristics
'fhiladtbhia MM
CIBA-GEK3Y
NEWPORT PLANT
AS-08
TOTAL METALS
MB
Chromium
Iron
HI
MmgantM
SET
INVERTEBRATES
Chronomu*. Ttrtin*
HyiMteAztKt
INVERTEBRATES
ChKonomUMt
ENRICHMENT
FACTOR*
147
5.1
10
1483
U
45
% SURVIVAL"
17.5%
25%
% DOMINANCE*
27.0%
300%
TAXA RICHNESS—
SET 3
Famillw 3.0
Toul TuWSMion s'o
Berthic Otmilyt . 433 indiv Mi'
AS-09
TOTAL METALS
IHM
Catouum
Ctvonilun
m
Imi
ttsr
E
INVERTEBRATES
QwtxnnuTMUo*
^•MiAiHa
INVERTEBRATES
CHranomkliw
ENRICHMENT
FACTOR'
41
4.7
a
105*
17
y
166
% SURVIVAL"
42.5%
tarn
% DOMINANCE*
20.0%
TAXA RICHNESS'"
ClMM* 3.0
Ord« 20
FnlM 10
Wi(Ti«j/SMion 40
BMNc 0«n«ty » . 71 ndiv An1
-------
FIGURE 19 (Continued)
Sediment Characteristics
BALIPARK,
~ Philadelphia Baltimort Railroad
IIIIIIIUIIMIIINMIHIINIUHIUNIIHIIINIIIHIIUIIIIIIIUIINHltllllHIIIHtlllllllHHWNUIIHniUIIUIHHI
2^
CIBA-GEK3Y
NEWPORT PLANT
NORTH
WETLANDS
Tm RUmu and BtnMc 0»nilty for
AS-06 M Mmd on two nptato inb
umplM. wlMfiM at ofwr Tm
RttlntM and Banftlc Oanilly Hall tor
VMM flguras It btMd on HUM
rtpNcilignbuniplu.
AS-02 J_
TOTAL METALS
Barium
Cadmium
ar
sr
ENRICHMENT
FACTOR'
Ml
10.5
(2
26.6
1.0
113
AS-03
TOTAL METALS
Barium
Cadmium
Coppar
Iron
UK)
Manganeae
Mercury
EM
m
INVERTEBRATES
Cenodapnnia
fSSSS
Chiroromua Tartan*
HfaMaAitaca
INVERTEBRATES
CJirorjomjdjfj
ENRICHMENT
FACTOR-
165.1
15.1
s
M.3
18
1.6
12
31.1
% SURVIVAL"
n.o%t
B.fii 1
K5%
ISOJt 1
% DOMINANCE*
35D%t
S7.0%|
TAXA RICHNESS-"
Cluaaa -.;:•:":• 4.0
Orten 3.0
Fwiita . $.0
Total Tau/Station 1 J Q
BaotNc Danairyt « 1,791 Indhr.An'
fPtuMllDaU
NOTES
•Enrichnurt Factor Ihtrattool
norm«Nz«d contai
ctntntkm
mate lo oommnlion* at • nbranot
location ItahouWbinolKflhalHS 15
Mt mad a* MM ralcranoi Hadon
• % Survival: btaad onII* number ol
MMdmb lhal iurviwd contimal
•ipowra to CtKWna Rhw and North
ind South D»po«il «t wdand
MdirMnU. Bawd on lour rapfcal* grab
' * Tua RichnM: total numbar ol apacn
toundinthaumpl*
• % Oomlnanoa: percent contribution ol
indrvidualt ol ttn moat numaraua
•pecwInttMumpla.
t Pollution tolaeirt organama.
t Banthk Oanaity: total numbar ol
individuali colktcted pet umpling
ittlkm band on a maan numbv ol 3
raDtcataorabaamptaa.
-------
FIGURE 20
River Sampling Data
NOTES
Refer to Figure 19 page 2
5gfl APPROXIMATE SITE AREA I
TAXA RICHNESS"*
4.0
IS
«S 10.0
BMhfc Dmtyi. 4,331 indiv /ro»
RS-15
RS-15 Located 1.3 miles Upstream
1 from RS-04
-------
FIGURE 20
River Sampling Data
I APPROXIMATE SITE AREA I
NOTES
Refer to Figure 19 page 2
RS-06
Approx Umilmlrom
N.I>iinagtW»y(HS-13l
ENRICHMENT
FACTOR'
Appro* 2501* from
ENRICHMENT
FACTOR'
2.1
0.6
1.S
if
1.3
32
ENRICHMENT
FACTOR-
CHURCHMAN'S
MARSH
Cwiodaphnw
Pisnaphate.
INVERTEBRATES
aMMiM
Chtronomidjt
RS-14
AtN.DraingiWiy
RS-11
Awran 0.4 mite torn
N.Dnun»g«Wiy(HS-13)
ENRICHMENT
MCTOR-
ENRICHMENT
FACTOR'
•- M ..
68.0
BwlHc OimXyt - 4,
-------
FIGURE 21
Ecological Habitats
BALLPARK
DUPONT
HOLLY RUN
PLANT
CIBA-GEIGY
NEWPORT PLANT
I NON-TIDAL WETLANDS I
-------
FIGURE 22
Estimated Wetland and River Areas Requiring Remediation
BAllPARK
HHIHIIIUIIIIIIHIHIIHIIIIII
DUPONT
HOLLY RUN
PLANT
Philatttbhia Baltimore Railrotd
IIIIIIIIIIIIMIIIII
CIBA-GEK3Y
NEWPORT PLANT
r^
'y//
Estimated Areas
Requiring Remediation
-------
FIGURE 23
Site Area Requiring Sediment Sampling
to Delineate Exact Areas for Remediation
BALLPARK
PhilaJtlfhi* Baltimore Rattro»J
IIHIHIIIIIIlfimilllllimmillllllllllllimillllllll
IIIIIIHIIIIHIINNIIIUIIHHIIINIUUI
DUPONT
HOLLY RUN
PLANT
CIBA-GEK3Y
NEWPORT PLANT
NORTH
LANDFILL
SOUTH
LANDFILL
Area Requiring Sampling to Delineate
To 1 mile upstream
Exact Areas (or Remediation
m
-------
FIGURE 24
Ballpark
r
"1
Winsor
Avenue
roximate Property
Estimated Area of
Remediation
Foot Path
Backstop
I I I I I I I M I II M I II I I > I U I M > II | M I M II I II I < M'M II I II
Railroad Tracks
I I I M i I I I I I M M I > I > I I M I I I > M M «• M I I < «••! I I I « I I I I I I M
Du Pont Holly Run Plant
CIBA-GEIGY Newport Plant
-------
FIGURE 25
North Landfill Cap
BALLPARK
it BMman RailnaJ
jiiiiiiiiiiHiiimiiiftiiiiiiiiiiiHiiimiiiiiiimii mmm „
DUPONT
HOUYRUN
PLANT
OM-GEIGY
NEWPORT PLANT
NORTH
LANDFILLl
AREATOBECAPPE
Potential Profile of Low-Permeability Cap for North Landfill
NORTH • • • v
• i^v^i\in . * */
-WETLANDS:.:
Vegetative Cover Soil
^^VVV^^^^
Sand Drainage Layer
-------
FIGURE 26
Potential Cross-Section of River Bank Cover System
North Landfill
Cap
rete Revetment Mattress
Concrete Filled
/Fabric Bags
Average Water
CChristinaRiver
* The average water level is based on a high tide elevation of 4.5 ft. and a low tide elevation of -1 ft.
-------
FIGURE 27
North Landfill Physical Barrier Wall
(Approximate Location)
Philadelphia Baltimore Railroad
IIIIIIHUIIIHIIIIIIllllllUIIIIIIIMIIIHIIIIIIIUIlllliniMiiiiiiiiiiuiMiiii
IHHIWflNllllllllllllllllltlllMllHINIIIIIIIIIIIIIlllllui
DUPONT
HOLLY RUN
PLANT
CIBA-GEIGY
NEWPORT PLANT
NORTH
LANDFILL
ical Barrier Wall
to Base of Columbia Formation
NORTH
DRAINAGE
WAY
SOUTH
LANDFILL
:-:•: NORTH
:•: WETLANDS:-:
: SOUTH WETLANDS
• r»i into Physical Barrier Wall at CIBA-GEIGY Plant
-------
FIGURE 28
South Landfill Cap and Excavation Area
Philadelphia Baltimore Railroad
u||||IIIIHH|NM|HIHNIIHHIIWHIMHIIIHIHUIHUIHIHIHHIIIIIIIUHIIHIMIl(lMIUIIIIIIUIIIHIII mil HIIIIIINIIIUIHI
DUPONT
HOLLY RUN
PLANT
CIBA-GEIGY
NEWPORT PLANT
NORTH
LANDFILL
SOUTH WETLANDS
| See Figure 25 for Cap Cross-Section!
Aooroximote Ar
To Be Copped
A fence and (homy plants will be added
for increased Site security
SOUTH WETLANDS
-------
FIGURE 29
Estimated Sediment Removal in South Wetlands
BALLPARK
PhiUutelfhi* Ralumort Railroad
IIIIIIIIIIHHMIIIIIllllll
DUPONT
HOLLY RUN
WANT
CIBA-GEIGY
NEWPORT PLANT
NORTH
LANDFILL
SOUTH
LANDFILL
NORTH-
WETLANDS .'
SOUTH WETLANDS
QJHWETUN
Estimated Area
of Sediment Removal
-------
FIGURE 30
CIBA-GEIGY Newport Plant and Du Pont Holly Run Plant
PhilaJtlphit Bali,mar, failreai
MMMMMMNMi M|«,M,HMH^ MM1.HHM.HItIIH1l.llll|HIMMIMt..IIM ,H,IMI.
Contaminated Plant Area
DUPONT
HCXLYRUN
PLANT
NORTH •„*.%"
-WETLANDS:
-------
FIGURE31
Estimated Area Requiring Ground Water Recovery
(due to Circumscribing Wall)
BANNING PARK
*
Campgrounds
Estimated Ground Water
Recovery Area
-------
FIGURE 32
Points of Compliance
Waste Management Area
Extent of ground water contamination in me
Columbia aquifer that exceeds MCLs
Area of Columbia aquifer requiring
remediation
_.._. Extent of ground water contamination in the
Potomac aquifer that exceeds MCLs
Area of Potomac aquifer requiring remediation
Waste Management Area
uummlimMMiiiniiiiM"""1""""1"""
QBA-GeiGY
NEWPORT PIANT
Area of Columbia Requiring Remediation
Area of Potomac Requiring Remediation
-------
FIGURE 33
Approximate Area of Ground-Water Management Zone
BANNING PARK
A
Campgrounds
Newport
imate Ground-Water
Management Zone Area
-------
FIGURE 34
Estimated Well Locations
for Remediating the Columbia Aquifer
BALLPARK
llHMMIMHMMMMMIIIIHMIIIHMIIIIMtlllllll
Philadelphia Baltimore Railroad
iiimmiiiiiiiiiiiiHiiiiiHuiiiiimiiiiuiiiii
DUPONT
HOLLY RUN
PIAKT
CIBA-GEIGY
NEWPORT PLANT
NORTH
LANDFILL
Approximate Area
of Cleanup
. NORTH-'.
.WETLANDS'.
SOUTH WETLANDS:
Well Locations
-------
FIGURE 35
Estimated Well Locations: Potomac Hydraulic Barrier
BALLPARK
IWNIIHIIINNIIIIIMIIIMIIIIIHIIIIN
DUPONT
HCXLYRUN
PIANT
Philadelphia Baltimore Railroad
IIIIIIINHNIHHIIHIIINIIINIIHMUHHHtMMHHIIIMII
CIBA-GEIGY
NEWPORT PLANT
r
NOHHX-X
»MK WETLANDS.
-------
FIGURE 36
North Wetlands Area Requiring Sediment Sampling
rt
to Delineate Exact Areas for Remediation
BALLPARK
Philadelphia Baltimore Railroad
DUPONT
HOLLY RUN
PLANT
CIBA-GEIGY
NEWPORT PLANT
NORTH
LANDFILL
SOUTH
LANDFILL
SOUTH WETLANDS-
. « «
Requiring Sampling to Delineate
Exact Areas for Remediation
-------
FIGURE 37
CIBA-GEIGY Newport Plant and Du Pont Holly Run Plant
a Baltimore Railroad
HIIIIIUIIIIIIIIIIII
~j Contaminated Plant Areas
DUPONT
HOUYRUN
WANT
NORTH
LANDFILL
Approximate Location of
Physical Barrier Wall*
SOUTH
LANDFILL
NORTH
WETLANDS:
'SOUTH WETLANDS-
• Ties into Physical Barrier Wall at North Landfill
-------
FIGURE 38
South Wetlands Area Requiring Sediment Sampling
to Delineate Exact Areas for Remediation
Baltimore Railroad
DUPONT
HOU.YRUN
PLANT
CIBA-GEIGY
NEWPORT PLANT
NORTH
LANDflLL
SOUTH
LANDFILL
NORTH .%v
WETLANDS:
Areo Requiring Sampling to Delineate
Exact Areas for Remediation
-------
FIGURE 39
Christina River Area Requiring Sediment Sampling
to Delineate Exact Areas for Remediation
BALLPARK
PhilaAlfhu Salomon Railroad
HI FOOT
HOLLY RUN
PLANT
CIBA-GEK3Y
NEWPORT PLANT
SOUTH
LANDFILL
v. NORTH *
-WETLANDS:
SOUTH WETLAN
Area Requiring Sampling to Deli
Exact Areas for Remediation
2 miles"clownstream
To 1 mile upstream
-------
FIGURE 40
Location of Public Water Supply Line
Public Water Supply Lines
will Extend to This Point
1-95 & 1-495
INTERCHANGE
Indicates approximate areas which contain
residential dwellings.
Approximate distance to nearest public water supply
well is currently 1.5 miles southeast of the Site.
-------
-- -- -- ----
--'-"'"-"'---;:0: _.;; "'"
..4
:.., -~' ,:~.
ATTACHMENT A
C""C~ 01' TIC
Q,NCTQIt
STAn 0,. C&,4W"ltC
CIPARTMKNT O~ NATU.."I. Rucu,.ca
It E.~V'''CN'''INTAI. C:ONTftCI.
OIVlS/ON OF AI" & WASTE MANAGEMENT
.t 1CINQ8 HrO"'WA...
~.o. 8Ca lAC'
COVIlt. =e1.A...AItC I ~J
TIu-..c: (303) 7" . ~.,...
Auausc 17, 1993
Mr. S~an18Y t. La8kowaki. (3DAOO)
Accinl a-S1onal A~ini.cracor
~.S. EPA, Re,10n II!
841 Ch..cnuc !ullcH.ng
Philadelphia. PA 19107-4431
\
,
St."BJECT :
DuPQnc-~.vpor; R8corc of De~1aion, July 1993
Dear MZ. La.kow.k1:
. . .
Tha. Del&v&r8 D.pa:~enc of Natural aesourca. and Env1ror.:encalCencro1
("Deparc=enc8) ha. completed 11:. review of the July, 1993 Kaco:~ of Deel.1on
(ROD) ~ocWllefte £0-: the DuPont-Newpo:'C S~pe:ft.md .ite. !hi. c:orra81londence
repre.senu chI D.para.nt'. podtion regarding eM b8~8 c!escribed in thb iCD.
'1118 Departmenc b..
deccrib.d in the ROD. The
ROD which l:he Depucmene
posicion.
dtc t.d nOI: ~ concur Oft porc1aM of the ruedy
attachment (Attachment A) cUscu.... tha ana. ~f the
dG.. no~ concur a10n& vi th the rational. for 1 ta
'thank you for che oppor~i r:y to C:~1IIIII.nt on th1. cSocWll8nt.
. .
-
Sincerely,
//}~~~~~r:.
Mary L. KcKenaie
AC1:ina J)1~tcto~
KFK: dw
K1K2'o4.wp
.\c1:achlllent:
pc:
Chr1nophe A.C.
N.V. Raman
!Cad Ka1bachn
Alma HU1.~
D&V8 CArtel'
Bob K\oWhl
Tulou
. t)tt.t"~"'4 i)MIC fIAIt-r,q ~~,,,,u M ,.w
-------
-- -. . .
"''''''''''''-. _::_~'_r.,;-
. ...-~~~~-~=o~;~ -
ACt~chm.n~ A
UCOIJ) 'or DXCISIOJ '01. DUPOST-nvPOB.'1' SIT!
CO!lHD'rS 0' TU J:W..\i'AU J)!PAR'1'D!rr or NA'1'CLU. USOUiCZS
AND uvnoD!l'U1. COl!fftOt
l"!
South !...anc1fill: The Deput=enc hu elace.d noe co concur wi t:h ~1s
ponton of tbe :sudy. The DepuCllen: .uppor:. dle instal1adoft of & low
peme&D111cy cap over t~e 'out.~ landfill. ~e cio no~. however, s~pon ~he
stabilizae10n component of eh. ramedy which 1.5 not coat effective, becau.se
1: provides hardly any benefit: to :he environment at an expenaa ot
approxi:acely $10-12 million. In DN1U:C's oJl1.n1.on t."\e 'scabilizacion .
component of t..~. ruedy. is nd.unwc. El'A'. rat10nale for the' ciou.bl. .
. remedy ~rov~d.d in :he ~a.pont~v.ne.a 5~~ is no: very c~ncing.
the Deparement qu..tions c~i. double remedy to: the following :"'0118:
a.
Likely reducdancy of the se&bili:ation.
The vue. cONci::'.1enc. in ::he .ou:h lauc:it111 have a lov mobility,
. and therefore, aloni:ori=s of Iroundwater qualicy by DuPon: should
provide enough pro~.~~lon to the enviro~.nc.
b.
c.
In its comments on :he Propo.ed PLAn (January 28. 1993).DuPoa~ ~
,raised :e..onable ~o~.~ &bo~~ ~he po..ib111ty ot .t&btlizacicn
incr8a8tns ~~e leachability of aome metal. 1a ~. wa.ca =acer1al.
Th8 D8I'u=ent18 concemad chat little or no beCllfit to che
environm8at will be obtainad by stabilizing :be V&lCe material it
the atabil1zadon proce.. i.nc::..... tb.. mobU1ty of .0118
~ont_in&nt. . .
d.
In the re,poM1v8ntl. '\UIIII&ry grcundwatarflov 11 u"A AI the b.I1,
to d1spu:e DuPont', ~oneenT:1on chat "~ere is currently little Or no
flow of contm1n&ncs from !:he .outh landfill". Gro\mtvat:er flow
alot\. u1 not caWl. conUJa1nan~ flow. The ccmtua1M:U: mue: aha b. ;
aIOb:£.b to' Cau.l8 1C8 =:£'I1'&::£'on. In ehe seconci draf~ of eM aoD. the
impre".1.on b liven ~ut UA .81"" wi en. the concept thac cho I118cal.
conc.m.1nation in :~e iro\U1OwUer 40.. no: alove very quickly. Thi.s
Lmpr...ion 1. .uppo~:.ci by EPA's selection of mou1torins a. the
ready for groundwacer on .che sOUoth dei. of the Christ1na lUver. If
the IIIOni:orlni of :he groundwater 11 considered protective enoush :0
addr... che concec of lIetala concazUna:101\ 1n the JroUNN&Cer, the
nec...1ty to .~&bUize che wa8~' ,.eu 'U}'8rnUOUl. The low
pe1'lll.abiUcy eap '..rUl considerably reduce :he 1ntllcr&c10n of
s..r£ac:e ..,a1:.~.
-
2.
South IJetlanc.: The. Deparc.nc do.. not: ~onc:\:t' w1,c;h chi.. po~:ioft ot the
uJII8dy. !'h. Oepartmene ~&. provU.d to EPA on ftUlllereus ocea81oM 1:.
polieion regarding the IoLse of sediment cleanup criteria to deeermine ana.
of the tOuch weclandl r.qui~inS r.medl~Cion. The n8parCal.nc', conC8rna
. wich :he use of sedial.nt c4.anup crit.ria for remedial decision makin, are
b...d upon:
Pas. 1
-------
. ci.
a.
The limi:ed number of sampling stacio.ns used to cie:armine ehe
sediment ch8lDbtry. based cleanup val~e8. . especially. for the
wetlanci.s. It; .pP"%'8 tha.t the data is not suffic1tnt to be uaed for
sec':1ng quantitative cle4r1up levels. As :his dOCWII8ftt SCats. (i....
Page 3 of ~. River and ~eClar1d Remediation Goals =emo). "there i.
not One single biological Ce8t performed at the aite ~t corralat..
statistically well to. the sediment c:helDhC:ry (either & single
contaminant or suite of cont~inant.)..
b.
!he D.paraenc is concerned by ~"1. ob.ervaeion t."t4c e1'1e sampling.
stAtions in the south wetlands where both biological t;esting and
metals c:hemiacry analysis were performed (AS01. M03, and ASOS). the
results indicate !:hac Vtry limited toxicity occurred. .to the ca..:
organiJmseven chough elevated hveb of dce related coriCam1%1a\ts
.wer. fo~ in the sediments. . Statistically dlf1i£ic:anc sampl1q
should ba conducted in the area to beete: a8se.. :he relatio~h1p
beeween tne .ediment enemisery value. and the biological e.st1ng
n.ults. Seeeing sediment cleanup criteriA \U1nl the da:a c~r8ntly
available would not be appropriate.
c.
The Department Clue.tion. d'1e approach of combining the Chrbtina
River and wetl.ncU . sediment. toxici:y and c:hem18t1')' ciata co cieearmina
on. .ec of sedJ.ment chemistry basad cleanup levels that ue
applicable to both ~Co.y.tema I the river and the wetlands. In .eh8
nf,renced memo (1..., River and tJedaDd lauc1iat10ft Goals lIamQ) cha
.outh . pond 1.8 dhcu..ed a... a .pedal lrea Where differancu in
envirOnzD8ntal cond1tioM be~"8en the pond ~ the vedand.8 1II&Y
account for .edimen: toxicity difference. (paS. 5). If d1fferanc..
in b1oavaUabil1.ty exilt becveen the. .outh .pond and the wecland8. it
would be reasonable co &..um. tM-t differenc.. in bioavallabUicy
anc1 illl'pacu would exist becw..n the w.tlAncU and the Chri8t1na
liver. The ..d1ment cham!nry may ba cU.fferent and thi 18n.itivity
of c11ffermt orlan1lU that inhabie ~a tWO ecoly.tem.a 111&1 a1.0
differ. Concerns exi.e that tha limited data. de.. not Ad.~U&:.ly
reflect ehe naeural variability at ehe 11t,.
It 1s ehe nepar:ment's ~er.ean~1ng that two ba.1c :ithocia. exist ~
for nor.aalizing .ediment cia:a: normaliz1na to grain dze. (Foreener I
1990; Horowiez. 1991) And nomal1%iZ!1 data to "conaerYativ.
element"- in the sample, 5w:h .. alum1nula (Horowitz. 198.5; ~Uado11,
at al, 1989. Foreener. 1990) and iron (Smith. at &1. 1987). The
procedures u.ed in analyzing s1ce se41manc -ample. for chemi.ery
valua8 and grain size have rai..d ..r10Wl concerna. Std.c:1y
apeaktni. normalizing to &rain .1z. may noc be valid if I'parate
.ed1=8IU: aliquot. were analyzad for grain sb, and mec.l8 CMlli.a-,.
Although it b po..ible eo aetallpe co Cho:ouslUY hoao,'nize .
.ediment. hefore p1:'.~.rinl ..p.r&~e aliquot.. the r..ulca. of field:
duplicaee. typically reveal consid8rable variability. Such
variation tncroducC8 &n unaccepcable amount of error when
interpreting daca ba.ed on chemical analy.e. from one aliquot and
grain .ize to . different aliquot. The procedur.. to cieeeain. the
.ecitmenc chamisery basad cle.~p level, have not been explained in
the ~D. .
Page 2
-------
---- -.----
------- --_..- -
The Depart:enc's cQnce:ns.~ich ~he UAe of ~e .ediment cleanup criCer1a
have b.en ciocwancad on .averal COrr881)Onl18ncu to EPA. AA a nau1t of
the Dep.r:menc'. conce~~ w1th the ua. 'of the s.ci1manc cleaaup criteria.
EPA raqU8lca4 thee ~e D.~&r~nt ~re~&r.. a sediment cle&~~ Icaema for
the DuPont-N'wpor~ sitt. On June 21. 1993. ~e Dep.r~nt .ubmit~.d to
EPA ies sediment cleanup scheme for the Dulont-Newport lice. The Icheme
described a prcceu for :euins ..d.imenu for cham1at~ thro~h \U8 of ~~
.c1d-vcl.t~le sul!148/;t:ultantou.ly tx:racead. mecals (AVS/SEM) analysis
and. castins sedimenes for toxici cy co organisu (1.,.. solici phase
toxicity :eac1ng). The schame c&11,4 for t..tlna to be conduct.d in .
a:ici nec¥ork .uch chat & .tatbtically d,mfic&nt nWllb.r of aamplu woulci
be collected, anet c."'enforll, a valid aueasant could b. III&de mcb te.peet
to .che ar~al of the weclana.:requiring.ramedlacion.
Tha Depar~ent's sediment cleanup schema was not incorporatad into th1.
ROD.
3.
,
Chrhd1".& River; Th. De1'a:=.ru: cioe. noc CeMUI' wim ::h1. por~ion ot thl
remeciy. !he ra~ioa&18 for noc suppor~inl th15 por1:1on of t:ba r8llaciy i.
COu.1st8nc with :he co==.n~s incl~c.d for ~ sou~~ w8clanda reme4y ~1th
reapect ~o ~~e u.e of sed1:enc cl.an~p c:1teria to c!.ttermine are.1 of tb.
river r.q~1rin8 remediation. .
The I)epercent cio.. not ~el1.V8 ."the:r.. i. .utt1c1tnc daea &Vail~la from.
=h. 18med1al I~..:isaeion of che.Chr1.c1na Riverte ..eab11.b ..d1m8n:.
c:i.e&ZNJI criteria for the dVer. The lim1c8ci "ca wh1ch 1\&1 b..n collecc.d
in 1:.."- Chr1sc1na atw!: cioe. incU.cace ~ac an aciveraa 1mp&Ct hu occurred.
in eh. river -=.. of ~. C1ba G811Y por1:1on of che 81:a. Thi8
c!.tcena1nacion wa. baaed Uit0n b1elolical t..cs which 1NS1eacad . 10"
s~1vor.h1.p percanc&se. !h. De'Par=enc 'U1',or~s 1:h8 us. of AVS/SiK &n4
solid pha.. coxic1ty t8.tinl in & atatistically v.lid approach eo ..a...
impaccs and arl.. rlqu1rinl rlmediacion in th8 Chriatina Riv8r.
I..
GroUIUiwa~er: The I).percenc concurs with DlOIC ot the :-1"41 delcrib.d in
;h1.s lec 1:10n ot the 101). However, the Daputmenc doas noc IUppOZ'C EPA I .
. position. nl81'CUnl lonS term monitorinl.. El'A hu noc. provic!aci lnthe 10]).
& 4ec1don poine from which corrective acdcm8 would be taken vit:b ra.~ect
to concwnatld irounclvuar m1srat10n. Quoeina from P.58 1.7 of che IOJ);
"If any f)f che .1~a.ralatad con~amf.nanca m1i1'atad to any one
of cha.e vell. ae a laval sufficiene to produce a ri.k of
tither 10.' fOI: cueinolaftic :bka or 1 fer non.cU'c1nosen1e
rhka. furthar nmad1al aceion (such ... raltoradon or
conea11D8nt of sroundwuu) w111 bl ccm8iciarad u chae t1a."
'-
Th. Departmenc had r.quescad chat & ciaci.10n-m&k1nl procell for rema41&1 .
. aedon. b..ad on eh. &ro~civ.te: IIIOnicor1n, r8.~lea, b. 1nclud8ci in eM .
~D. .
3.
Co..cal Zone Maftagement.A't: The D.par~.nt hal be.n coord1~t1ns with
EPA r.sardins the conlis:ency deeerm1nation for the Federal Co..eal Zone
Mana&amen~ Ace (CZMA). !o dace. ehe Dep.:~.nt baa luppl1ad EPA with
Pale 3
-------
SENT EY:~NREC Air&Was~e M9~
; 8-17-93
l:::::~5?M ;
13e2739586eH
cOlllllants on their draft COMls1:8ncy determination;
cona1,cency aeterminacion has not been finalized.
1~el2~3":'5o.l;= ~
however,
the
Cona1ac8ncy wi:." che Federal CZMA is performed by the D.p~tII.nt' s
Delaware Co..eal Management Program (DCMP). Since the remeciiation 1. &
direct federal &c~ivity. it must comply with the policies of en. DCMP"as
required by the CZHA. Since EPA ha. not fina1!z8d. 1.t. COnain8t1cy
cieterminadon for the proj act. the DCMP cannol: d8t:8rmine if the iOD is
consistent with it. pollci... ..pec1ally thaI. resardlng w8clanda.
" .
,
,
-------
ATTACHMENT B
UNITED STATES ENVIRONMENTAl.. PROTECTlON AGENCY
REGION m
841 C~ BuikIng
Philadelphia, Pennsylvania 19107'
SUBJECT:
River & Wetland Remediation Goals
(Sediment Clean-up Criteria)
Du Pont-Newport site ~
Third and Final Edition,
Randy ~t~eon, RPM iO~-#~ - 't-tif.<:r-A .
OE/MD Sect>on (3HW4,j'£4- [7' /' / \
File ,
DATE: 7/9/93
FROM:
TO:
Introduction
This memo describes the determination of the ,wetland and
riv~r sediment clean~up criteria at the ~u Pont-Newport Superfund
, site.' ,This. is the third edition 9f this memo. . Previous editions
were issued 10/27/92 and 4/29/93. Discussions over the past ten
months with the Biological Technical Assistance Group of EPA
Region 3 (STAG), the US Fish and Wildlife Service (FWS), the
State of Delaware, the National Oceanic and Atmospheric
Administration (NOAA), and EPA's Environmental Response Team
(ERT) have led to the development of these criteria. In general,
because the state of Delaware has had serious reservations with
the original derivation of these criteria (mainly that they are
based on what it considers an insufficient amount of data)
, discussions have continued in aneffort.to determine criteria,
,with'whichevery one could agree. 'Delaware's Department of "
Natural Resources and Environmental Control (DNREC) proposed to
EPA.sediment criteria dated 6/21/93. DNREC's criteria centered
around using acid-volatile sulfide (AVS) and the three toxicity
tests described in the second edition to determine areas of
unacceptable impact. Decisions about which areas to be
remediated would be made once' then new sampling data was
collected. EPA did not agree with relying heavily on an approach
(the AVS) which is largely still in the research stage and has
not been used at the Site and in essence issuing a ROD which did
,not make a decisi~fI. about the remediation. A meeting with DNREC'
on 6/22/93 did not bring resolution to these issus. EPA also had
serious reservations about the criteria as outlined in the second
edition. EPA did not believe that'the overall cost of the extra
1
-------
toxicity tests (around two million dollars) was warranted for the
amount of benefit to gained. .
. , .
'At this time EPA is issuing the final sediment clean-up
criteria to be used in the ROD. These criteria have been
accepted (through verbal discussions although this document has
not been formally reviewed) by the Biological Technical
Assistance Group of EPA Region 3 (BTAG), the US Fish and Wildlife
Service (FWS) , the State of Delaware, t~e National Oceanic and
Atmospheric Administration (NOAA), and EPA's Environmental
Response Team (ERT). with the. condition th~t the contaminated, yet
unremediated areas, undergo long-term monitoring. '
The' criteria. are, the. chemistry criteria that were.. developed .
in the first edition .and revised in the second edition. All".
areas of wetlands and the river which exceed these values will be
remediated. Since these values are high compared to other
published sediment guidelines, areas of the Site where the
sediment chemistry is below the chemistry criteria outlined below
but above "apparent effects threshold" (AET) values, a limited
number of toxicity tests (solid phase Hyallela azteca) will be
done to make sure that the criteria are protective. Results of
the testing may lower the chemistry criteria. xt ia t.aperativ.
to recognize that these cleaD-ap Ievela are based OD Du PoDt-
.ewport sit.-sp.ci~ic cOD4itions and are absolutely not ~o ~
us.a'at other sit...
Backqroun4
The determination of sediment clean-up criteria has 'been a
difficult process. Results of the biological testing during the
RI (sediment toxicity testing and benthos studies) indicate that
large portions of the site have heavy metals that, while'
exceeding published guidelines,l are apparently not producing
unacceptable biological ~mpacts.
". .
. 'Numerous reviews of DU Pont documents by and discussions
with the BTAG, (which has NOAA, FWS, ERT, and EPA Environmental
Services Division (404 enforcement) representation), NOAA-
Seattle, and others have concluded (DNREC has been heavily'
lTo date, there are no promulgated regulations for sediment
clean-up criteria. Several organizations have published levels
that can be used as guidelines to help indicate when toxic
effects ~y be expected. These include Threshold Value
Guidelines or TVGs by EPA (set. at levels which are expected to'
produce interstitial water contaminant levels at Water Quality
Criteria), the biological ~ffects guidelines or ER-Ls and ER-Ms
by Long & Morgan (1991), and the Great Lakes Harbor Sediment
Guidelines by the u.S. Army Corps of Engineers.
2
-------
involved in these discussions as well) that certain areas of the
site exhibit unacceptable env~ronmental impacts and warrant
remediation (see Figures 1 and 2 for various test 'results and
Table 1 for the determination of which stations exhibit impacts
that warrant remediation). The conclusions took into account
current conditions and possible future conditions. At this Site
a process of building a "weight-of-evidence" was \lsed to draw th~
conclusions. Many aspects were considered:
A.
Levels of toxicity as indicated by foUr different
toxicity tests (two elutriate and two solid phase)
measuring mortality, reproductivity and groWth (not
necessarily 'each for every test)
Density~ 'diversity,. and richness of benthic organisms
B.
c.
contaminant levels in sediment and surface water
D.
Field observations
E.
Aerial Photographs
F.
Fish tissue analysis
Plant.tissue analysis
G.
H.
. .
. .
Modeling of potential future conditions
Sediment consumption by terrestrial animals
1.
J.
Type and value of wetland habitat
The factors which were most relied upon where the benthos studies
and the toxicity test. It should be noted that EPA considers any
area containing elevated levels of site-related contaminants to
be impacted by the site. However, not all impacts warrant
remediation. At this Site, stripping all areas of the river ~nd
the wetlan~s that exhibit elevated levels of Site-related
contaminants could cause more harm to tQe environment than
leaving all or some of the contamination in place. Since there
a~e not any promulgated clean-up criteria for sediments, the
determination of when impacts are acceptable or unacceptable and,
therefore, when remediation is warranted, becomes one of
professional jUdgement.
. As discussed above, data from the RI was used to determine
the general az:eas requiring remediation. Howeyer, due to the
broad spacing of samples taken durinq the RIfFS, the exact areal
extent of remediation is currently unknown but will be determined
during the remedial design (RD) phase. In order to define the
exact areal extent of remediation, clean-up criteria must be set.
3
-------
Discussion
Clean-up criteria are set to provide the remedial designer
with a relatively simple and practical way to delineate of areas
which require remediation. The simplest, most practical test to
use would be a sediment chemistry test only. . Using a triad.
approach (the combination of sediment chemistry, benthic studies,
and toxicity tests done at each particular station which was
heavily relied upon to determine the general' areas requiring'
remediation) at numerous nodes on a grid becomes expensive and
impracticable to implement duringRD/RA (for example, Du Pont and
EPA had a very hard time agreeing to: what areas demonstrated
unacceptable impacts during the writing 'of the Environmental
Evaluation). However, efforts to date by Du Pont during the
RI/FS and by NOAA (personal communication with Don McDonald,
4/23/93 and 4/26/93) show that there is not one single biological'
test performed at the site that correlates well statistically to
the sediment' chemistry (either. a single contaminant or suite of'
contaminants) thus providing an easy way of determining sediment
chemistry criteria that are predictive of biological stress.
Therefore,. EPA reviewed the triad data to see if patterns,
.whi~h although not. correlating .statistically to one single. .
contaminant, existed between elevated' levels of. Site-related.
sediment contaminants and the most sensitive indicators of
Unacceptable impact (at this Site, benthos studies and toxicity
tests). Chemistry data was.reviewed on a normalized basis.2
Trends w~re seen for cadmium, lead, and zinc. When these
metals were high (not necessarily all at once3), unacceptable
2Extreme variability can occur in sediment contaminant
levels due to naturally occUrring physical/chemical conditions
such as deposition rates, sediment types, grain-size ahd organic
matter content. Therefore, comparing sediment chemistry from
different sampling stations. and sampling events to determine
'where anthropogenic loading has occurred becomes difficult.
Normalizing the data allows a more direct comparison of sediment
chemistry between different stations to take place. In this case
it was determined that the grain size of the sediments was the
greatest cause of natural variability (see Environmental
Evaluation, 8/7/92, page 4-6). By normalizing the data to qrain
size (dividing the actual contaminant. levels by the perce~tage of
sediments from that. sample that pass through a 64 micron sieve)
the affect of qrain size on the sediment chemistry is removed.
3NOAA also attempted to correlate sediment contaminant
levels with each other and arrived at the conclusion that only
lead and copper levels were related to each other (there was a
4
-------
impacts. were observed. Barium did not appear to be causing
measurable impacts to aquatic life (i.e., at some' stations, AS05
for instance, very high level's of barium did not cause toxicity
that warranted remediation). Other Site-related contaminants
such as copper, mercury, nickel, arsenic, chromium, and manganese
either did not exhibit trends or exhibited trends of increasing
levels associated with increasing impacts but were determined not
to add to the usefulness of the' criteria set for cadmium, lead,
and zinc. . . . .
Figures 3 to 5 are bar charts containing the normalized
concentrations of cadmium, lead, and zinc for the sediment
stations where biological testing was conducted. On ~he right
side of the chart. are those stations where EPA has determined'
that the results of the biological testing indicates that.
remediation is warranted. On the left side are those stations
where the results did not indicate that remediation was
warranted. The charts also show the "lowest possible criteria"
or "LPC" and the "maximum possible criteria" or "MPC" for each of
these three contaminants.4 The LPC for a particular contaminant
is at. the highest level of any station where the biological test
results indicated that remediation was not warranted. The MPC
for each particular contaminant is the maximum level of that.
contaminant for those stations where the biological tests
indicated that remediation was warranted. The LPC and the MPC
dictate.the range of available. contaminant levels from which the'
actual clean-up criteria may be set. Setting a clean-up criteria
. below the LPC would trigger remediation at stations where
remediation is not warranted, and setting a criteria above the
MPC'would'serve no purpose in directing remediation since
remediation would not be triggered at any of the sampling
locations where EPA has determined remediation is warranted.
The criteria ranges from Figures 3 to 5 are (on a normalized
basis):
.cadmium 67 to. 1121 ppm
Lead 1443 to 51~60 ppm
Zinc 6853 to 32558 ppm
correlation coefficient of approximately 0.7). This means that,
overall, high levels of one contaminant are independent of other
contaminants and means that measured toxicity could be caused by
different ,contaminants at different stations perhaps singularly
or in varying combinations with other site-related contaainants.
~e "lowest possible criteria" and the "maxim~ possible
criteria" are terms relative only to the data. presented in
Figures J to 5.
5
-------
The above lowest possible criteria came from station AS01 in
the south wetlands pond. However, this. station also had the best
biological test results of any station at the site indi~ating
that the contaminants are potentially less bioavailable in the
pond. The test results and field observations (muskrat lodges,
turtles, and the best stand of vegetation in the south we~lands)
indicate that there may not be a need to remediate this. area in
spite of the high concentrations of metals that generally have
caused unacceptable toxicity at other stations at the site. The
difference in the environmental conditions between the pond and'
the marshy wetlands may be causing a difference in the
bioavailability of the contaminants, thereby causing unacceptable
environmental impacts in the marshy wetlands to occur at lower
contaminant levels' than in the south pond. Limitinq the LPC to
the levels found. at Asoi'istherfo~e not. protective because these
levels have generally been found to cause toxicity at other
sampling stations. Therefore, station AS01 will not be used to
develop sediment chemistry clean-up criteria for the rest of the
Site, and the sediment clean-up criteria will not apply to the.
south pond.' .
The criteria ranges from Figures 3 to 5 without AS01 are:
LPC MPC
Cadmium 52 to 1121. ppm
Lead 1060 to 51860 ppm
Zinc 5350 to 32558 ppm
The absolute values for the above LPCs (the pre-normalized'
value for the station from which the LPC was derived) are:
Cadmium
Lead
Zinc
648
509
2520
ppm
ppm'
ppm
. These 'values are 'generaliy high compared ,to other sediment
guidelines that nave'been developed such asEPA's Threshold Value,
Guidelines (TVGs), ER-Ls/ER-Ms (Long , Morgan~ 1991), and, .
, apparent effects threshold (AET) levelss which are listed below:
AET
TVG
ER-L
ER-M
Cadmium
Lead
Zinc
9.6
660
1600
31
132
760
5
35
120
9
110
270
ppm
ppm
ppm
S"Briefing Report to the EPA Science Advisory Board: The
Apparent Effects Threshold Approach." US EPA Region 10 (prepared
by PTI Environmental services, EPA Contract ~o. 68-03-3534/PTI
Contract No. C714-01) September 1988.
6
-------
The fact that the LPCs .are generally higher than other guidelines
may mean that the bioavailibilty of the metals is lower than what
. could. generally be expected. Although, it should be noted that
the LPCs above are not levels below'which toxicity is not
present, but are levels at which remediation is definitely
warranted at the Du Pont-Newport Site based on biological
testing. As such, the actual clean-up criteria shall be set only
slightly above the lowest possible criteria. Sediment chemistry
clean-up criteria are (on a normalized basis):
Cadmium
Lead
Zinc.
60'
1200.
'56QO
ppm
ppm
ppm
Areas where the normalized surficial sediment' chemistry in the
wetlands and the river is above these criteria shall be
remediated.6
Since tbe LPCs are relatively high and the number of samples
taken compared to the area of sediments is relatively small,
furth$r biological testing shall be performed to make sure that
the Site-specific clean-up .criteria are protective. Solid phase
sediment toxicity tests using Hyallela az~eca and measuring
survivability shall be used to make sure that the sediment
criteria described above. are pro~ective. . A minimal'n~r of .
sampling stations shall' be performed in each of four di~ferent
areas: the north wetlands, the south wetlands, the south pond,
and the Christina River (four sampling stations in each of four
areas with four replicates per station for a total of 64 tests
will be used in the cost estimate for the ROD). These stations
shall be located in areas where the chemistry levels fall between
the Site-specific clean-up criteria and the AET values for zinc,
cadmium, or lead. A 30% drop in survival compared the
appropriate reference and/or control sample will be considered
unacceptable (reference attached Dynamac letter). EPA may lower
. the sed,iment clean-up criteria depending on the results. of the '
toxicity testing." The toxicity test results. wj;ll be reviewed. .
60ne concern, 'especially in the river, is that if an area is
sampled and 'the % fines is very low, then the normalized values
. will be very high even if there is only minor contamination
present. Therefore, samples are to be,collected from
depositional areas.. If a node of the grid fall in -a area that is
predominately gravel the location of the node should be adjusted
to an area expected to have at least 50% fines. For the purposes
of these' criteria, all samples should have 'atleast. 50\ fines.
'Since the criteria do not apply to the' south pond and since
it is small, ei ther the whole pond would be or would n~ be.. .
remediated depending on the results of the toxicity tests in the
south pond along with the other data collected during the RI.
7
-------
independently for each area. This may lead to different clean-up
criteria for the north. wetlands, the south wetlands, and the'
Christina River. . .
Since the contaminant levels that potentially will remain in
the wetland and river sediments are relatively high, long-term
monitoring will be required to make ,sure the contaminants do not
become excessively bioavai~able in the future. The requirements
of the long-term monitoring program shall take into account'the
results of the delineation activities. See the attached'
suggestions from NOAA regarding the monitoring. Also, due to
possible tapacts to terrestrial receptors at the south pond
caused by plant uptake of contaainants,8 muskrats should be
moni tored. ,,'
Application
Use the criteria in the following manner:
1. Set up a sampling grid of the north and south wetlands
and .the river for the initial chemistry analyses. See Figure 6
for the area in whi9h sediment chemistry tests must be taken in
order to delineate the exact areas requiring remediation.9 The
chemistry criteria'do not apply to the south pond as discussed
, above. ' " ..','
2. Due to the possibility of river sediments becoming
mobile during a major $torm event (such as a hurricane), sampling
at each river sta~ion shall be done to a depth of two feet with
discrete samples taken every six inches.
3. Sample the top 6" of sediment for TAL metals.
determine the percent fines.
, . ~..' Di vide the chemistry analyses of each of ,th~, above
contaminants at. each sampling location by ~e percent fines
(expressed on a decimal basis) from that sampling station (i.e.,
normalize to grain size).
Also
8Risk assessment calculation similar to that for determining
the Hazard Index for humans show there is a potential impact to
,animals who consume plants from this area.
, '
9The n~~ of n~es should be statistically significant and
small enough to be able to quide the remedial, equipllent. The
cost estimate for the ROD used a 100' x 100' grid in the wetlands
and the river with the spacing becoming 500' x SQO' in the river
one-half mile up and down stream of the facilities~'
8
-------
5. .Compare the normalized results' to th~ following
chemistry criteria: .
Cadmium
Lead
Zinc
60
1200
5600
ppm
ppm
ppm
If anyone is exceeded, the area represerited by that sample shall
be remediated.
.6.
resample
area due
h
-------
c.
histeopaths on kidneys and/or livers
samples collected at the 1, 3, and 5 year interval
startinq durinq RD.
A formal review and report of this data would be ,prepared as part
of the 5 year review process unless deemed necessary at an
earlier date by ,EPA. '
, d.
Conclusion
,EPA, ,in consultation ,with" NOAA, and the USFWS, has developed
site-specific sediment clean-up criteria for the ~ Pont-Newport
Superfund Site. The determination of the criteria 'was based
mainly on the results of the toxicity tests and the benthic
studies which were performed durinq the Remedial Investiqation.
The criteria involve delineatinq areas of unacceptable toxicity
usinq sediment chemistry levels for cadmium, lead, and zinc (with
a minimal number of toxicity tests to ensure that the criteria
are protective). It ia iaperative, to recoqni.. that the.e clean-
up level. are ba.ed on Du Pont-BeYport 8it--ap.ci~ic condition.,
and are absolutely not to be used at other sit... These tests
shall be performed 'early in the remedial desiqn process to
'determine areas ,of the wetlands ~n~ the Christina River ,whiCh
reqUire 'remediation. ' .. . . .
10
-------
TABLE 1
MAJOR REASONS WHY STATIONS REQUIRE REMEDIATION
L
AS07: Extremely low benthic density, low Chironomus tentans
survival, no vegetation present
Extremely low benthic density, extremely low Chironomus
ten tans survival, low taxa richness
2. AS08:
3. AS09:
4. AS03:
Extremely low benthic density, low taxa richness, low
Chiro:(1omus tentans survival . .
. .
Low benthic diversity,expected low Hyallela azteca
survival (very low survival occurred in the RI but
problems with the laboratory control of this test has
decreased the validity of the data), hiqh percent
dominance of pollution tolerant benthos
RS11: Lo~ taxa richness, extremely high percent dominance of
pollution tolerant benthos
5.
6.
RS12: Low taxa richness, extremely high percent dominance of
pollution tolerant benthos,. low.Chironomus ten tans
survival
NOTE: The 0% survival of fathead minnows at RS07 is considered
an outlier in light of the. relatively low levels of contaminati~n
present. This area will under further toxicity testing as part
of the delineation for the dredging.
RS01 was previously included on this list but further review
of the data indicated that it should be removed. In Phases II
anq III, RS01 was sampled on a mid-channel bar. In Phases II
. there washighievels.of contaminants but no toxicity tests. were
. . performed... In Phase .111,. the contaminant levels were 'low and the
toxicity test results were good but the percent fines was too low
(8.3%) such that the normalized values were abnormally hiqh and
should not be used. For Supplemental Phase III, the Hyallela
azteca test results were not. good but the contaminant levels were
so. low that the toxicity may have been caused by other problems.
Also not the high variability of the replicate results (0, 10,
50, and 70% survival).
11
-------
CADMIUM
10D1100 .0I , II fib C~
.1
10000
~
"
I
B
i
;.
.;,'
,;
/,
%
'.
%
pp.
'.
'.
.',
~
"
./
;;
%
;;
~
1
~
ASIO MUS 1tS04 a506 RS07 RS07 RSOI' IlSO\! ItSIO
as!) IISI~ liS.. A.'I.I\ ASI2 IIsm ASOI ASIII> AStl1 /lS01 /lSOI /Ism /lSIlI 1\" II \I'd I
SCallon
STATIONS NOT. REQUIRING REMEDIATION" ..STATIONS REQUIRING REMEDIATION
11"1.1
...,.,.., "... r:' .,
-------
lEAD
100000
801
flfIb
Da.
t'I ft! ~ ? I~O
10
STATIONS NOT REQUIRING REMEDIATION
STATIONS REQUIRINO REMEDIATION
~
...
f4
a . LPt!." 14'13......
e :JDhf'cxX)"
8
9
a
N
j
~
10000
ppm
100
.1
FIGURE 4
-------
100000
.01
fSPb
ZINC
o~
ft\f~c.!b~
~ 10000
... t.k . ,,53
i s 53So
ti 1000
U
8
u
:If
...
N
(i
N
I
ppm
100
10
.1
STATIONS NOT REQUIRING REMEDIATION
'r-I". I~r- ~
STATIONS REQUIRINO REMEDlAT10N
-------
CYNAMAC
CORPORATION
Environmental.Services
80 W. Lancaster Avenue
Devon, PA 19333
Telephone: 215-989-9400
Fax: 215-989-9414
Mr. Randy Sturqeon
U.S. EPA Reqion III
841 Chestnut Buildinq'
. ,Philadelphia,' PA . 19107
Reference:
Contract No. 68-W9-0005
Work Assignment No. C03034
DuPont Newport,' Newport, Delaware
Subject:
Revised Performance Schedule
Dear Mr~ StUrqeon:
. "
. .
As per your request and discussions of the teleconference held on
May 7, 1993, Dynamac has revised the document submitted to you on
April 29, 1993.
Attachment 1 provides an Explanation of Procedures used to develop
the Performance Standards as well as proposed the Samplinq Plan.
Attachment 2 provides a Cost Estimate for the implementation of. the "
proposed Samplinq Plan. .
If you h~ve any questions, .pJ,.ease callme at (215) 989-9400.
~'
'ca';;il1e Costa, P.E...
Manaqer, Engineerinq
.cc: . .Ms, Donna McGowan, US EPA Reqion III, CERCLA RPO .
Mr. Robert Stecik,' Vice President, Northeast operations
Corporate Headquarters: The Dynamac Building. 2275 Research Boulevard. Rockville. MD 20850-3268 .
-------
SAMPLING PLAN AND PERFORMANCE STANDARDS
FOR THE DUPONT-NEWPORT SITE
A systematic .sampling plan has been developed for the SDS wetlands, NDS wetlands, and
Christina River at the DuPont-Newport site. The sampling pIan has been designed to provide
a statistically sound basis for testing the following hypothesis:
T1u! growth of Chironomus te1UQ1lS. survival of Chironomus temans, and survival ofByalella
azteca are reduced in site sediments rellJtive to the same endpoints for these organisms in
sedUnerus from an area 'unaffected I1y the DuPont-Newpon site bur otherwise the same.
. StratBICation of Site
To increase precision, the'SDS wetlands, SDS pond, NDS wetlands, the .Christina River
upstream from the North Drainageway, and the Christina River downstream from the North
Drainageway are considered to be different statistical stra~ or domains at the site, and
systematic sampling has been designed for each stratum. The north drainageway, the northern
half of the SDS wetlands and the north bank of the river along the NDS and CIBA-GEIGY were.
not included because it is anticipated that these areas will be remediated due to very high
~iment contamination levels.
The' statistical design developed for this repOrt is based in part on ~ careful evaluation of the
results of prelimInary sediment toxicity testing conducted during the RI. The WithiIi-station
variance and the coefficients of variation for sets of samples in each stratum were used in
selecting the appropriate number of samples for each stratum and the' necessary number of
replicates at each station, as described below. .
Replicates
In the RI sediment toxicity tests, four (4) replicate samples were collected at each sampling
station. There was relatively little dispersion in the observed survival rates for Chironomus
tentans and Hyalella azieca. Given that the average standard deviation across the site was 19%
or . lower in the Ri tests,. and assuming that the same: standard deviation Wiil be seen in future
tests, it can be ~er assumed that six (6) replicates at each station will be sufficient to discern
. impacts related to contamination from other impacts. The choice of six (6) replicates is based
on a statistical power analysis, given that the specified significant difference in survival rates is
32.5 % relative to reference for OaironOTnUS tenrans, and 30% relative to reference for Hyalella
tmeca, as desCIibed below. That is, six (6)" replicates will be sufficient to discern between
significant differences and variation caused by background causes, given a standard deviation
of less than 19 ~.
EP A guie:tance on petfonnance standards for toxicity tests. for these two organisms to" be
published this autumn will be recommending use of eight (8) replicates per station when the
tighmess of the variance is unlcnown; therefore the decision to use only ~ replicates is based
largely on the small standard deviations in the preliminary data (Ankley, 1993; Norberg-King,
1993).
-------
Number of Samples to be CoUected from Each Stratum
The number of samples required to obtain a given precision with a specific confidence level can
be obtained from the following equation:
n =
( CV) 2 (t; )
p2
n = nUD:1ber of stations
CV = coefficient of variation
p = allowable margin of enor expressed as a percent
t = the two tailed t value obtained from standard statistical tables at the a level
of significance and at (n-l) degrees of freedom. (Mason, B.I., 1983).
For this sampling plan, a confidence level of 95% has been chosen. The selected allowable
margin of errur is +/- 10%; this meanS that a +/- 10% precision is cOnsidered r~nable in
making a determination for each stratum of the need for remediation based on the results of
sediment toxicity tests. The coefficien~ of variation was devel~ from the preli~ary .
Chironomus teMans and. Hyalellil Q2JeCQ sediment toxicity tests .presented In the RI (see Tables. .
A, B,and C, which provide statistical summaries of the RI sediment toxicity data); Based on
the RI data, the average coefficient of variation for each stratum is 39% or less (when 0%
survival values are ignored). While the average coefficients of variation are different for each
stratum, the average coefficient of variation across the site for survival for both organisms is
27.1 %. To be conservative a coefficient of variation of 29% was used in the above equation
to calculate the required number of samples in each stratum. Ignoring the 0% ~urvival results
in calculating the coefficient of variation for each stratum is assumed to be a reasonable step,
because. the sediments with extremely high mortality will clearly have to be rem~ted.
.where
Using these values for the variables in the abOve equation (95% confidence, 10% error, and
29% site-wide coefficient of variation) yields 35 stations for each stratum. However, since the
SDS pond is small and the whole pond will either be-cleaned up or not, 35 stations will not be
necessary there. Therefore, . five (5) stations (locations based on professional judgement) will
. be placed in the SDS pond. The 35 stations in each of the other strata besides the SDS pond
should be pJaced in a rectangular grid. The grids will be expanded or contraeted to fit the size
and approximate shape of. the stratum. Based on maps provid«f in the RI, the approximate
dimensions between nodes of the grids will be: SDS wetlands, ISO' X 250'; NDS wetlands, 300'
X 120'; ChriStina River upstream, 480' X 175'; Christina River doWnstream, 960' X 175'.
Total Number of Samples
As described above, six (6) replicates will be collected from each station for each organism (six
(6) for Chironomus leMons and six (6) for Hyalella Q2JeCQ). An additional sample will be
collected from each station to be analyzed for physical and chemical characteristics (grain size,
Ph, and the suite of TAL metals). At approximately 10" of the stations in each stratum, (four
-------
(4) stations), duplicates for sediment physical and chemical characteristics will be collected to
incr~ precision. - -
In addition, sediment toxicity tests, benthic community analyses, physical and chemical analyses
will be conducted at two appropriate reference locations that will be as similar as possible to site
sampling stations, particularly with respect to sediment physical characteristics, except for the
absence of site influence. -
Performance Standards for Conducting -the H~ azuca sUrvival, Chironomus -tentans
survival, and Chironomus UnIiI1JS growth tests are as follows:
BacIcgfound Station Surviv3I Chironomus te1Utl1lS: 70% (ASTM, 1992).
Background Station Survival HyaJel14 azteca: 80% (ASTM, 1992).
These background station survival rates are published in the American Society for Testing and
Materials Standard Guide for Conducting Sediment Toxicity Tests with Freshwater Invertebrates
(Standard E 1383-92). If the average ~rvival rates fall below either of these percentages, the
test is considered unacceptable.
-Note:. If th~ control survival rates are not achieved, the test will have to_be repeated. Results -
from any tests with less than the above-specified survival - rates for the controls will be
considered invalid.
The need for remediation at different stations has been established based on the results of
sediment toxicity tests and the performance standards set for this site. The performance
standards for sediment toxicity tests at the DuPont-Newport site are based on a thorough review
of the data presented in the RI (especially Tables C-I0, C-12, C-13, and C-14; Woodward
Ciyde, 1992) and a statistical analysis. These standards are wholly consistent with the .
- recommendations of EPA ~ent toxicity experts (Norberg-King, 1993; Ankley, 1993), and.
provide a statistically Sound indication of the need to remediate different portions of the site.
These performance standards, when applied to the sediment toxicity tests conducted during the
- RI, support existing decisions to remediate the stations described in Table 1.
The sediment toxicity test performance standards are:
32.5~ drop (difference-of 32.5~) in relative Chironomus te7ltans survival (Figure 1),.
30~ drop (difference of 30~) in relative Hy~ll4 amca survival (F"IgUre 2), and
35% reducQon (factQr of 3~") in ~tive Chironomus tentIJnS growth (Figure 3).
Detailed statistical analyses of the sediment toxicity tests from the RI showed that an observed
decrease is probably related to contamination, and not to other souloes of variation, when there
is a 32.5 ~ or more drop in ChiT01IOfIUIS tentmlS survival relative to the reference station (see
Attachment A for an iIHfepth discussion of the statistical analysis of variance performed), a 30%
drop in- HyaJelkl survival, and a 35~ reduction in Chironomus growth. It should be noted that
while the analysis of variance indicates that an 18.7" drop in ByaJell/J azJeCtl survival is the
.
.
.
-------
, 2.
TABLE 1
MAJOR REASONS WHY STATIONS REQUIRE REMEDIATION
1.
AS03: Low benthic diversity, expected low HyaJelkl QZJeca survival (very low survival
occurred in the RI but problems with the laboratory control of this test has
decreased the validity of the data), high percent dominance of pollution tolerant
benthos. "
AS07.: Ex~mely low benthic density, low ChiroMmus tenums survival, no vege~tion
, present. ' , .
3.
AS08: Extremely low benthic density, low taxa richness, extremely low Chironomus
te7llans survival.
4.
AS09: Extremely low benthic density, low taxa richness, low Chironornus te7llans
survival. '
s.
RS01: . Low benthic diversity, expected low HyaJelkl QZJeco survi~ (very low survival
occurred'in the RI but. 'problems with ,the 'laboratory contro~ of this' ~ ,has' '
decreased the validity of the data), high percent dominance of pollution tolerant
benthos.
6.
RS 11: Low taxa richness, extremely high percent dominance of pollution tolerant
benthos.
7.
RS12: Low taxa richness, extremely high percent dominance of pollution tolerant
benthos, low ChiroMmu.f te7llll1lS survival.
. This table,Was'prepared by u.s. EPA Region m..
-------
minimum that could be detected with four replicates, a 30% drop has ~een set as the
performance standard' to be conservative , because the Hyalella azJeca survival test in the RI 'was .
flawed by low survival of the control (Woodward Clyde, 1992).
The values chosen for the performance standards are the result of careful examination of the
prepo.ndel'3Jlce of evidence for the need to remediate particular stations at the site, as well as of
the variation in the RI sediment toxicity teSt results. The following factors limited the choice
of the selected performance standard values. .
If the performance standard were set too low, then the result would be that, for example,
stations AS09 and AS07 might not appear to. need remediation, when ecological evidence
indicates that they do require'remediaI:action (see Figure 1). That is, stations AS09 and ASO?
exhibit low benthic density and low benthic taD richness, and high levels of chemical
contamination (see Table 1). If a very large drop in relative survival was set as the standard,
some stations might not be remediated where real ecological effects were being observed.
If the performance standard were set too high, then the result would be that some areas, which
do not require 'remedial action, would appear to require such action. For example, if the
performance standard for Chironomus tentallS survival was set ata 10% decrease relative to the .
reference, then stations RS13 and AS12 would appear to neeci"remediation (see Figure 1);
. however, the rest of the ~logical evidence presented in the RI is not consistent with this ~lt.
. That"is, the. RI indicateS there is no need for remediation at tliese two stations.
The statistical analysis behind setting the minimum difference for the performance standards can
be sum~ as foijows (see Attachment A for a detailed explanation). Four (4) replicates
were collected from each'station (or sediment toxicity tests in the RI. The variation between
replicates at each station was measured. The average standard deviation for Chironomus tenlans
survival rates was approximately 19~, (the standard deviations for replicates for Hyalella
survival and Chironomus growth were even lower; see Tables A, B, and C, which ~ummarize
. data presented in the RI). Using this standard deviation, we conducted an analysis of variance
(ANOV A) test to deci~e what amount of-a difference could be attributed to cornamination alone, ; .
given that there were four replicates from each station. This test was evaluated at a 95 %
confidence level, that is, with 95'1 confidence that when a pollutant effect is indicated by the
results of the sediment toxicity tests, it is highly probable that there is a pollution effect at the
'site. (See calculations in Attachment A). As a result of the ANOV A tests, a 32.5 % difference
in relative Chironomus te1Ilans survival was calculated as the minimum detectable difference. .
Similarly, we calculated an 18.7" difference in relative HyalelltJ azJeca survival, and a 35%
reduction in relative ChironomllS growth, as the minimum detectable differences. based on the
RI data.
Again, while the analysis of variance indicates that an 18.7% drop in HyalelltJ OZleca survival
is the minimum that could be detected with four replicates, a 30~ drop has been set as the
performance standard to be conservative, because the HyalelltJ OZIeca survival test in the RI was
flawed by low survival of the control (Woodward Clyde, 1992).
It is important to note that these performance standards have been approved by EP A sediment
-------
toxicity experts as discernable differences between reference and . site stations (Norberg-King,
1993; Ankley, 1993), when an adequate number of replicates are used. .
The use of six (6) replicates per station is recommended to ensure a powerful statistical test of
the hypo$esis that site sediments are adversely impacted. The more replicates are used, the
more certain it will be that areas that appear to be unimpaired based on the results of the toxicity
tests are, in fact, unimpaired at the site.
-------
100
0/0 60
i.
-_.-_u__o-..
. Figure 1 .
Survival (0/0) of Chironomus tentans
Relative .to RS15
(From Table C-10, DuPont/Newport RI, 1992)
80
R.'.ruOl 8tallon 8urvlval Rat.
t
40
,
,iii,
'~.: ..:~.,
.~: t
:\Ji ~.
:)'1 \:'
r~ . 1(
~ ::;,~"
,I:.!I\
..
20
,I;'
o
...
RS16 RS11 - AS03 AS08 RS14 AS06 RS13 AS12 RS01 RS12 AS09 AS07 ASOB
Site Sample Locations
(1) Performance Standard Calculation:
. 86%(Reference Station RS16) ~ 32.6% . 62.5%
---
--------."- --
--~--_...._--- ...
-------
0/0 50
40
--"---_.._--
80
70
. Figure 2
Survival (0/0) of Hyalella aztec a
Relative ..to RS15
(From .Table C-14, DuPont/Newport RI., .1992)
30
Referenoe Station SurvIval Rate
60
t
30'" Drop
!
Re.u.ltlng Perlormanoe
Standard Survlva' Ral. (1)
20
10
o
~-"'I-.
RS16 AS06 AS09 RS13 AS06 ~S11 RS14 . AS12 RS01 AS03 AS08 AS07 RS12
. Site. Sample Locations
(1) Performance Standard Calculation:
ee.6"(Ref~rence Station RS16) - 30111. . .36.6111.
------"---.. ----.
-------
-------.---.. . 0 .
__.___0_.
, Figure 3 . .
Summary of Weight Data for Chironomus. ten tans
. Relative to RS15
. .
(From Table C-11, DuPont/Newport RI, 1992)
Mean Dry Weight (mg)
. 6
5
Reference Station Mean Dry Weight (mg)
,4
t
, 311.. Drop
! '
Resulting Performance
Standard Mean Dry
Weight (mg) (1)
3
2
1
" '
:\I'~'i~" ",
:' , (; { : fl';'
-l,tf, , ""1/,'
;frllii ',:; ~f)
o
RS01 RS14 AS12 AS06 AS03 RS13 AS09 AS07 . RS12 AS08
Site Sample Locations
(1) Performance Standard Calculation: .
, 4.592(Reference Station RS15) - 1;600(35%) . 2.992
R816 AS06 RS11
---_...
_0_--0_00
-------
TABLE A - COEFFICIENT OF VARlA110N AMONG THE SlItVlVAL RATES OF CHIIONOMUS iENTANS
FROM THE NORTH AN> SOUJH DISPOSAL SITES, AN> Ct.USl1M' RIVEn'
. -~aon' H.... ~ ,,-.... P!CIp .":'!'
. .;""N-'''''' SUIVNW'
. ::""111 ...;." 70 III
RWeleil/:t B 00
?;~:!!I!fI?:: 'I
I~ 'I
~11~~i ~ ~
[=--E
~
8&n1i181 R.t.. amana 8tallana'
""'age ~!8ftI
82.11
4U
17.8
4ii:.11
lU
II) CV .lIlatlOn Hep. SI.WVIvaI Av..g. I urClp n ~ :;u
1!1 .J!);ii J;;{i1~ -r= ~~~~ SurvMoJ..tt~ SurvfvJ 13
R"",nca B 00
Station C 100
. .. . D 80
11 "'U~~11 ~ 1~
:: .... C 70
:.... D 100
A. 50
B 40
C 70
D 50
" 11
B 50
C 70
D 80
A DU
B 70
C 00
I) 50
40 v, I:..~' IE
-lIIIaDlOP In.
~I ar .
AVef.!
slftIIii.l Ratal amond 818110118
Avaraga
3811 rt
i<.
411
18 L:::.!itt(.
20 11.~
~'i
52.11
12.:1
77.11
IIU
3z.5 13
110
ZII D.1
1.
~~" ;;rallOfi. ".. IliurvMII A-~'!J!=b~'" =so=;=c'; 'I
r"'l...!.b~!Iit. 1'It). Survlv.'- ~) SI.WVIvaI' r")
15~R-':~~~.'.: '~6. 8' 13 '151
. Slatlon. C 100
, .: D 80
;'Ij.~j: t ~.~ ,,' "I" -"
"I~' i! " 'T<7 --.
87.8
4ii:.11
III
:14.11
25.8
12.4
1.11
111.4
11
11
...:".'.:
: '.::: .',:
>.:...
'.13.D
"':'.
IOLV::~:._I'::I: ..
IAVlrllll1 .VllllOn Of
Swvlval Rat.. amcna S18110118
~varag~.~iIn1
20 101 V.,IIUOIT
2\
":3
111.0
(I) TlblaC-10, Woodward Clyde. 1082. RllkA.._m.NOlI"oN-NIIWpOlt SI.. Volumd. ErM-onmenlal Evaluation. Auguat7, 1002.
(2) Slandud D8Ylltioft .
(3) Co8ftIclenlolv.rllllon .
(4) RS07 II -'dared an odIler and _I not e-Idared In Ute coeficieN of vallatlon eqLBtlon a. leq....ted bV U.S. EPA.
(5) Indlcat.. drop In" Iwvn' b8IwHn r8f.- llallon (R9111)and ....IaIlon8. . .
(8) Indlcat... 20.0811. a.age reduction kllwv1u81 rat. betwe", ,...,anol llatlon (RSt5) and IMa Il8l1ona ((34.5%+ 111.4%+6.31/.)/3).
(7) IndIcatnan 1'.78 averallulandard d8vtallon of NVIwa"at- amol'Q llallona ((211.0+13.8+10.0)/3).
(8) Co8IIIoI8nkIfvarlation a"'18" _.~ wtIholA llallona where 011. .wvlval wel 'DeCIded In Hyalliia azt~ or Ch~onomul tenlan. (.).
Baql18 ClJeIMIion: 81. StaiionASOO
Standard OlVllltion 'CIIIII'*:
jj (X,-~I
J.a
n-l
. .
\\tIar.: Xa .60, X;t .90, Xa . 100~' X. . 80, Jr. 82.5. n . ..
~
. lion ASOO
C08fIcI8rtafV.latlonfclnnlM: CV. ~ e 100
%
Whar.: .. 17, .K . 82.!I
CoefIcIenl of v.rlatlon {eM . 20
-------
. TABLE B - COEfFICIENT OF VARlA110N AMONG ltlE SURVIVAL RATES OF HrALEUA AZTECA
FROM THE NORTH AN) SOUTH DISPOSAL SITES. AN) CtfUSl1tM RIVER'
:::::Rii . 08111 Site
.~. ft.. ~ ,,-.e urap "":' 50' ~"!, ,S.-non Rep. s~~ """"!J! I urap In" SO ~. ~laU!ln Rep.lli~ Avwage urap in ~
. . no. SurvIwoI no,- lOc8llon"," ...... Survival ~ Surv",aI' """. l~" r.. SurvIvaI- "'I. Survival'
,')'-~11.!,\" 113 GUll 2.:1 U :'..RSII1..<: " II~ 118.211 2-D:n ~S111 A II~' 1I1I.}!5
Rji(~ 85 R.,.el1lle B 6~. Rtf.""", B 85
,:.I'~!l!Mf ~ ':.~!!on{ C. 70.SIaI!O!'l 0 70
Ii ~ 1 " n. ,,"' l.~ '" ,..~. "; ;' 10
20 -85
45 40
HI
~
'2.!iI__~.a
.n -, 1'1
11.11 11.0 "I
~I
I
5'.11
:I~,
"".,. ,;
':.:
31.11
28.8
22
17.0
:, i'
':'" .
""lIIIe [ ,ap In
U~IAale.
.1Av8fiiiji1I8ncl8foUeVlellOn Gr-
Bwvnl R.I.. ....- Slallon.'
II ""'lIIIe CoellC18,. .
383
au. 1
...,
AVWlllle D ap n
" SurVM.1 Ral'"
"VWlllle
Swvatal R.le. .mana Slallona'
'" =~=......
28.8
,..... ap In
,""".
8....R....-- 818-'
JAVW.
CIa.:!
11.11
2?
(1) Tabla C-14, Woodw8rd Clyd.. 1882. RIlkA.....m.nlDII'onl-NewpOlt S... VoIum.2, Envlronmenlal Evaluallon. AugUll7, 10112.
~1e.~dDw8I1on' .
(31 CoefIIoleni of V..lallon
(4) ftS01 Ie _Idtfed." odIIIr and _s not conaldw8d In \he coe1l1clenl of va,latlon eqUation .. reque'led by U.S. EPA.
(5) IndIc8l. drop In" swWalbelwMn ,tf._. ..110" (RS15) and s.. slatlol\l.
(8) IndIc&t8aa S1.",._..,8dIdIcIft1l\ ~r."'b.lwftnret..nc..l8t1on (RS1151.nd .Ke sla\lons ((53.a,c.+aO.'%+28.8%)/3I.
(7) Indlcat... 10.1 ~-.. llInderd...1Ion of 111M! ,.1. .mo,.. .lallona ((11.6+17.0+11.81/3). .
(I) CoIIIIaIeNof\l8llltlafta-.. _.CaICWQd wlhcMAatatione where 0% sI8VNaI-. ,ecorded 11\ Hy.llila utsce 01 Ch_~m\18 tenia.. ('I.
118,... C81C1811On: BII -\Ion ASOII
--
'ji (K,-J)'
I"
n-1
slandard D8VIaUDn fann"-:
WhIr.: Xa .65, Xa .80; X. .55, X, . 80. J. 70, n . .
Co8IIcI8nI ofV..lallon'OInIuIa: CV. j . 100
WhIr.: - . 12.2, x. 70
Co8IIclent of V..lallon /
-------
TABLE C - SUMMIIRY OF WEIGHT DATA FOR CHmONOMUS TENTANS EJCPOSm FORt2 DAYS
TO CHRIS~ RIVER. NORTH AN) SOUTH DISPOSAi. SITE WET\AN) Sm.MENTS'
>: ~ 43~:3 a.f1l1 . 0.1111 0.4011 13.1;
B $.381 B 11.188 B 3.23
C :1.81171 -C 3.788 .::, .:., C 3.853
o . D 5.012 '.(, "",,': 0 4.431
A . 1.7;1" 1.0". 01.010111 11'.l1li A 1.7~4 1.aza a.zo'l U.4411 A n 0.0011 ==r.ii7! ~f.2li
8 0.888 8 1.258 O'. B 3.513
3.48111 C . 1.807:., C 11.24'
.. 8.11771 D 0.722pP..;': D 5.58
01 0.7211 ...- 0,11011 na " 0.114 4.444 U.1411 0.7011
'.1181 B 4.21~'" ".
10 ~ 4~2~:'
. II.NI 1.001 01.." 0..04 "a.olili "...UII 1.aa.. 1.1a2 ao.au i,
. 8 4.18
. C 3.1128 ,.: 'c.,
o D US7
8.l1li41 8.1" 0.818 0.- 7.1181 A 4.1177
3.88 B 3.1182
..28111 C 4.773
:t07! D 3.1133
;;~, Ul4iID I~~~I ~"
~ 1.24 rAverag.
W.bhtAmana Stallona' . Meanbrv WebhlAmMn Stallone'
lAver. ~G.4r"ver. -.-
;=Wh"
~~\a~~! .
iimi!'~1;~
4."41
o.za. 0.8.40
1.ZD17D
U.1I11
0:'1881~
17,~2
81/11118 CIJNItIon: SIIIIIaIIonAIItII
..
i IXJ-~'
J.,
n-l .
Slandald Devlallon fOil"''':
Wher.: x,," 4.89. x." 3.38. X," 3.657. x." ..383,~.. '.078. n...
~
mp : ASOI
Co8fIcIent of VarIaUon form"': CV".!!.. 100
~
Where: 8.0.687. K" '.078
CoeIIc..", 01 Variation (C'JI . ".14
-------
REFERENCES
American Society for Testing and Materials. 1992. Standard Guide for Conducting Sediment
Toxicity Tests with Freshwater Invertebrates. ASTM Standard E 1383-92. Philadelphia,
Pennsylvania. .
Anldey, G. 1993. Personal communication with Gary Ankley, research sediment toxicologist,
U. S. EP A Environmental Research Laboratory, Duluth, Minnesota. .'
Green, R.H. 1979. Sampling Design and Statistical Methods for Environmental.Biologists. New
York: John Wiley & Sons. 257.pp. .
Mason, B.1. 1983.. Preparation of Soil Sampling Protocol Techniques and Strategies. EPA-
600/4-83-020. August, 1983. .
Norberg-King, T. 1993. Personal communication with Teresa Norberg-King, research aquatic
biologist, U.S. EPA Environmental Research Laboratory, Duluth, Minnesota, .
~oodward-Clyde. 1992. Risk Assessment DuPont-Newport Site. Volume 2, Env~'onmental
Evaluation. August 7, 1992. .
-------
Attachment A
A factorial analysis of variance (ANOV A) was utilized to determine the minimum detectable
change in growth and survivability of Chironomus teNons and the surv~vability of Hyalella
azJeca in sediments collected from the allegedly impaired areas due to contamination, when
compared to data obtained for the reference location when four (4) replicates per station are
collected. Ho asserts that the test area is not impaired when compared to the reference location.
The equation used to compute the changes in averages is based on a 1 X 2 (1 sampling event
by 2 areas: reference location and allegedly impaired area) factorial analysis of variance and
is presented below (Green, 1979).
) f) SScalc+ 1 dE
FO.95 (1, 2 (r-l d = 55 + 2 (X-I) df
. err
Where:
. FO.95 (1, 2 (r-I) dE) = F-value for CI = 0.95 at I dE (numerator);
2 (i-I) dE (denominator) .
5Scalc + I dE = (AX r) 2 + 2r
SSer.r+ 2 (r-I) dE = S2
df =
r =
S2 =
Ho =
. degrees of freedom,
. number of replicates, and . .
variance among stations in all three strata per organism per test.
The area is not impaired when compared to the reference location. .
This equation simplifies to: .
F(1,2(r-1)df) = (AX r)2
2r . S2 .
Since the change in the average is the only unknown variable, the equation is rearranged to:
Ax = ~ FO.95 (1, 2 (X-I; df) . 2 . 82
-------
Table A-I
Parameters and Results Cor the Factorial ANOV A
Resulting
Test Fus(1,2(r-l)dO r i- !!aX
Chironomus survival 5.99 4 352 > 32.5 % ..
Chironomus growth 5.99 .$ 0.815 > 1.6 mg (35%)
Hyalella survival 5.99 4 117 > 18.7%
Results
A change greater than the minimal detectable change will result in the rejection of the null
hypothesis, therefore asSerting that the ~ in question is impaired when 'compared to the
reference location and requires clean-up. The minimal detectable change in ChironD11J!IS survival .
i~ a difference of 32.5%, in Hyalella survival is a difference of 18.7%, and in Chironomus
growth is a factor of 35 %. These values can be used as performance standards for the RI. In
summary, because of the observed differences (variances, or standard deviations) in the four
replicates per stations used in the RI sediment toxicity tests, a statistical analysis as described
above shows the miilimum differences that can be discerned from background variation at the
site. These performance standards are consistent with the advice from EP A sediment toxicity
experts. .
-------
ATIACHMENT 2
Cost Estimates for Sediment Tests at DuPont, Newport
Toxicity Tests ---
Physical Tests. Chemical Test Benthic
.10-day Toxi.clty Test Macrolnvertebrate
Laboratorv DH Grain Size TAL Metals Chiroriomus Ii) I Hvalella II} Communi!Y S!!UC~ur~J!TI)..
ENSR Inc. NA NA NA $1 300.00 $1,000.00 NA
A TI Corp. $15.00 $27.50 (h) $493.75 NA NA m
NA
Analytlkem, Inc. $5.00 $150.00 $345.00 $1,600.00 0) $1,800.000) NA
$400.00 Ik) $400.00 (k) ..
RMC $8.00 NA $390.00 $900.00 $900.00 NA
IT Corp. NA $159.00 NA 'NA NA ----
NA
Dvnamac NA NA NA . NA NA -.
$2,500.00
"'1'"
!'veraae Cosl/Test $9.33 $112.17 $409.58 $878.10 $780.00 $2,500.00
Cosl/Area la) $326.67 $3,925.83 $14,335.42 $30,733.33 $27,300.00 NR ..
Cost of Dups or Reps/Area (b) $37.33 $448.67 $1,638.33 $153,666.67 $136,500.00 NR
Total Cosl/Area Ie) $364.00 $4.374.50 $15973.75 $184400.00 $163.800.00 NR ...
_. --
South Disposal Sile (SDS) Pond Cost (d) $46.67 $560.83 $2,047.92 $4,733.33 $4,300.00 NR
SDS Pond DUDS or ReDs Cost Ie) $9.33 $112.17 $409.58 $23 666.67 $21.500.00 NR ..
Total SDS Pond. Cost .$56.00 $673.00 $2.457.50 $26;400.00 $25,600.00 NR -
CosUReference location In $16.67 $224.33 $819.17 $6 400.00 $6.000.00 $15,000.00 -
Total Cost (a) . $1 549.33 $18,619.67 $67,990.63 $778 800.00 $693,000.00 $30,000.00
0) EIUIIudIr4I"'a louhdllpo881t1a (B081 pond. Will. AWl8Qa CoIIII'al' and al"""" 35 IIIUOIIII,om ..ell a,... 0081 noIlndud8 d~UC8laIIOl Itdlmanl cll8mltl'y Ind phYllo8lp,opartlH o"epIlCII.llorltdlm." lolilcly Ind
8nlh1o~ eludy. .
.1 EIIGI...,.."'a 11)8 pond. Aee- 4 d~"""/"" (oppllllllm8lely 1M. vllllrflial ooUod8d/llal"OI Itdlm8nl cll8mltl'y Ind phyllcal p,op.rtieo end II 'epilctlH 101"'" ledlml..lollcly Ind benlhlo oommlrolly ItUlly.
>I EIIDkId8t II)lponII.
Q UlIIII:. AVllIII8 CoeI/TIII and ..e_lIe18Io18. 00II nallnclude d~lI08t.. 10'ledlme" cll8mll'ry end phyeal p'opertlH or,epllcatll'or Itdlm8nl tOllclty end benlNo oommlrolly tludy.
.1 Atl- I ~lIo8to (opplOldnlll8ly 1M. oil"""" ooI8ded In "'0 B08 pondl 'o,e8dlme" cll8mlltry end phylal propert181 end II 1lpilealH '0'''''' Itdlm8nlloklclty Ind b8nlhlo oommunly ItUlly.
I Atl- I -Ikq''''- IooIIlonend I ~1081""'1on 'Of l8dlme.. cll8mlltry and phyllcal plop8rtl8t and 1I/lp1108l.. '01"'" Itdlmenl lokIcIty and bonlhlo oommunly ItUlly.
II Ale- 4 -, 1110108 pond, end 1I,--IoOIIIonI.
11 P,a equeII 1110 OVIIIIII 011118 "'01ll8lhod (83OIond 1118 ¥,omeIlI method (8251.
I Till ..... bGIh QIOIIth end ouMweldala.
I FOIIII8 "'" I""'. (888td on lpp/OIdrnI8e1y 11I1IIrfI18t.1
"For"'" 8ddUon8Ia8Jl1'1a. (888td OIIlppl1llllmllely III 1"""".1
I Till ylllduuNlvll d8t8 0IiW. .
nlBer&I*I MIaoI_IIK8Io CommunIIw 8IfUCllureliudy yI8Idt PlIO"" (~I dominance. cUndence, 8nd.dlY8l1nv.
IA - Nol AppIIoebI8. No quale IoIlhIt e8Moe wu oblalnld 1lOIII INe OOII'4Iony.
ill - No! R8IIu8tled. CcImrIi
-------
10/21/92
Oi:Z5
'a'
B.~n
I€J 00 2
;'i-~~
I ~
. .
\ > /
'--
u.s. DEPARTMENT OF COMMERCE
N.&iona' Oceania and ACInOSllh8Pic Administr.l~ian
Nattonal Ocean Service
Office Of.Ocean Fraources ConurvatiOn and Assessment
Hazardous Maler1818 FrRPOn58 and Asa8s8ment Division
Co8tll ResoUJQ:I Coordination Branch
1600 Sand Point Way NE. BIN C15700
Seattle. WA 98115
. October 20, 1992
Mr. John R. Sturgeon (3HW42>
. Office of Superfund ProgramS
EPA-Regionm .
. 841 Chestnut Street .
~plUa,PA 19107
RE:
DuPont-Newport
. Wetlands Remediation Goals
Dear Mr. Sturgeon:
~-~g~~~~~~~oo~moo~~~
memorandum to the .filesregarding the DuPont-Newport Superfund Site in
N~New Castle ~nty, Delaware. The foDowing amunent$ are made on .
behalf of the National Oceanic and Atmospheric AdminiStration (NOAA). . .
NOAA wiJlsupport the sediment clUn-up criteria desaibed in this document if
the comments described In this memo are inme mobile
. during a major ngioNl stmm ~ Core sediment samples will be taken which
wiJ1 be separated into" - 6 Inch sediment sectkms. Each of these sectioN will be
aNlyzed to determine the extent of contamination In river sedbnents. U the
clean-up criteria are exceeded, sediments will be removed down8to a level where
amtamination is below the criteria set for this site. The placement of dean liD in
remediated areas will not be required. Applf-tion of these dean-up criteria to
river sedimems should remove the major portion of site-related contaminati~
.AR317571"
.....~
tn~\
, ...' ,
. .
. >'
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10/21192
07:26
tt
BAZMAT
~003
. and because the river is a dynamic environment, natural recovery will be
enhanced. .
Additional language needs to be inducted regarding the site-specific nature of
these sediment deanup criteria. These aiteria have been established based on
the available information pertaining to the DuPont-Newport Superfund site.
These criteria are site-spedfic: and are not intended to be applied at any other
siteL These aiteria were derived usin& si~ chemisby as well as bioassay
data. In adcii~ remediation activities are expected to prevent further
cxm~tion via groundwater and. leachate. In same areas, the south disposal
site pond far example, removal is !lOt wurantecL With the source of ". .
cxmtamination reD1Dved-lsolated, or stabWzed, CIOI\ditfons are expec:ted to
improve over time. Because cleanup aiteria for sediments will be normalized to
grain size, cleanup levels Oft a dry-weJght basis are expeded to be lower than the
established sediment contaminant criteria.
Tluoughout the document, the words "unacceptable tmpac:r' are used relative to
footnote 2 on pap 1. Given site-spedfic amditiol1S, the remedy described here is
acceptable to NOAA. Perhaps the footnote should be modified to include the
river and to clarify that -at ~ sfte~ st:rip~g the ~ wetland (l)uld cause .
rncire harm to the environment". . .." ."
The-monitoring suggestion provided by NOAA should be sUJNl\U'ized in this
document. The foUowing could be included: "
Although the detai]s woulci be detennined during nanedial design, a 1I\01\i~g
progt.un might include: "
1. Sediment chemistry and toxidty testing C1i~ survival and c:hinmomid .
". . survival and growtb) at a total of 18 stations. . " ..
2. 1 stations In the river (1 station adjacent to DOrth 1aI\dfD1; 2 stations adjacent to
the south landfi11; 2 stations downstreim of remediat2d area; 1 station upstzeam
of r-1Mdiated area; and llef.erence station) .
3. 61tatkms in die south wetland (AS.03, AS-OS,2 stations In the lower wetland
that wtU DOt be remed.iated; 1 station in the pond; 1 station between the fiB area
and the benn)
4. 5 stations in the north wetland and draiMp d.itda area (ASoCli near ASC9 in
the ditdl; AS-IO; AS-11i 1 station in the MwIy c:reaEd wetland>.
.
- s. A baseUne sampIiI1g round shauld aJso be cxmdw:ted before remediation
bepIs. Long term monitoring should be amducted at a deaeasIng frequency:
for example, years 1, 2,3,5, 7,9, 11, 15, 20, 25, and 30.
Aft.317572
-------
10/21/92
oi:'!;
-a-
B.~-\T
~uu. L
.-
6. Sediment grain size and rota) organic carbon content showd be measured for
all samples. 3 field replicate 5aD\p1es should be c.'Ollected for chemical analysis
and. toxicity testing. . No more than the top 5 centimeters of sediment should be
cnllected for chemical analysis and toxicity testing. Toxidty tests should be
conducted on subsets of dte same sediment analyzed for trace element
concentrations. .
&ktitionaJ Specific Comments:
Page 3, Foomote 3: Grain size should be nonnali%ed to the fraction of sediment
that will pass through a 64 miaon steve. .
Page 4, item 3: Concentrations should be divided by percent fines (expressed on
a ded~al basis).
Page 4, lir.st full paragraph: "the blologica1 tests indicated no sipift~nt
environmental bripacts" should be changed to "severe".
. Page S: 11Us muskrat study is probably excessive. Taking 16-20 muskrats from
the pond in three different years will remove up to 60 muskrats frOD\ the
. wetland. Two stations. are not needed at the pond, .it is wilikely that tw~ separate
. muskrat populations exist In such. small- area. This study should be sca1ed bade
to one station (in addition to the reference station) and only 3-S muskrats per
year. If it is not known how UW\y muskrats are in the wetland, only adult males
should be taken. .
If you have any questions, please a:mtact me at (215) 597-3636.
Sincerely,
~CA. b: Y ~ --->.1 ~
P~. KNght ~ -
NOAA- Coastal ResoU1'Cll! ~
.
.
4R317573
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