United-States1
Environmental Proteciton
Agency.
Office of
Emergency and
Remedial Response
EPA/ROD/R 03-86/031
S«pl«mb«r 1986
4>EPA Superfund
Record of Decision:
Delaware City PVC, DE
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TECHNICAL REPORT DATA
iPleat read Instructions on iht rtvtnt before completing)
1. REPORT NO.
EPA/ROD/R03-86/031
3. RECIPIENT'S ACCESSION NO.
4. TITLE ANO
SUPERFUND RECORD OF DECISION
Delaware City PVC, DE
5. REPORT DATE
September 30, 1986
I. PERFORMING ORGANIZATION CODE
7. AUTMORIS)
I. PERFORMING ORGANISATION REPORT %c
9. PERFORMING ORGANIZATION NAM6 ANO ADDRESS
10. PROGRAM ELEMENT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
J13. TYPE OF REPORT AND PERIOD COv£ae;
Final ROD Report
14. SPONSORING AGENCY CODE
800/00
19. SUPPLEMENTARY NOTES
16. ABSTRACT " ~~~~~~~' ' " ~ ~~
The Delaware City PVC site is located two miles northwest of Delaware City, New
Castle County, Delaware. In 1966 stauffer Chemical Company (SCO of Westport,
Connecticut, founded the Delaware City PVC Plant, which is used for the manufacturing o
polyvinylchloride resin (PVC), polyvinyl acetate and other polymers. From 1971 to 19~4
off-grade PVC resin, sludge from the wastewater treatment system and residue fror? the
stripping process were disposed of in two onsite pits. These "buried sludge pits" were
closed and covered in 1979. Off-grade PVC resin was disposed of in a third pit. This
material was removed and the pits backfilled in 1974. In May 1981 Formosa acquired the
PVC manufacturing and processing facility and has continued operations to present. The
two buried sludge pits and the third disposal pit were retained by SCC as part of its
Carbon Disulfide Plant, located adjacent to the PVC Plant property. An EPA conducted
inspection in May 1982 indicated serious contamination of the shallow ground water.
Currently, ground water, surface water, and soils are contaminated with ?vc, benzyl
chloride monomer (VCM), TCE, and 1,2-dichloroethane (EDO.
The description of the selected remedial action for each area of this site is
provided below. Off-Grade Batch Pits: excavate and remove existing PVC sludge and
contaminated soils; install a double synthetic liner; install monitoring wells and
perform quarterly sample analysis for TCE, EDC, VCM. The excavated material will ne
(See attached sheet)
KEY WORDS ANO DOCUMENT ANALYSIS
DESCRIPTORS
b.iOENTIBiERS.OPEN £N06O TERMS
COSATi F;eid.Croup
Superfund Record of Decision
Delaware City PVC, DE
Contaminated Media: gw, sw, soil
Key contaminants:TCE, PVC, EDC, VCM
18. DISTRIBUTION STATEMENT
19 SECURITY CLASS / Tint Kfponi
None
21 NO. Of PAGES
57
20. SECURITY CLASS . Tins page I
22. PRICE
EPA t*m 2220-1 (*•». 4-77) PREVIOUS eOi TION . i O»§OHTC
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EPA/ROD/R03-86/031
Delaware City PVC, DE
16. ABSTRACT (continued)
processed and recovered (estimated at 80-85%) as a saleable finished
product to the maximum extent possible. Non-recoverable material will be
disposed of offsite at an approved RCRA facility. Stormwater Reservoir:
The sane remedy as described for the above off-grade batch pits. Unlined
Ditches: excavate and remove PVC sludge and dispose of at an approved RCRA
facility; install a single synthetic liner. Aerated Lagoons: excavate and
remove PVC sludge; clean and repair lagoons as necessary; install a double
synthetic liner; install monitoring wells and perform quarterly sampling
analysis for TCE, EDC and VCM. The excavated material will be recovered to
the maximum extent possible (estimated to be 80-85%) and non-recoverable
material will be disposed of offsite at an approved RCRA facility. Closed
Buried Sludge Pits: place a drainage layer on top of the existing synthetic
cap; cover with a second synthetic cap and topsoil and revegetate. Former
PVC Storage Area: cover and cap the entire area with a double synthetic
cap. Ground Water: install a line of six ground water recovery wells at
the northern edge of the contaminant plume, and another six wells at the
southern edge. Reuse the collected ground water in Formosa's plant
operations. During periods of low water demand in the plant, treat the
ground water in the existing waste water treatment plant. Install two
monitoring wells at the southern edge of the plume. Provide an alternate
water supply for existing contaminated wells. Operation and Maintenance:
as a minimum, regular inspections and, as necessary, repairs to the liners
and caps. The ground water recovery system will be routinely monitored to
assure that it is capturing the contaminated plume. The estimated capital
cost for the remedy is $1,904,000 with annual O&M costs of $43,000.
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RECORD OF DECISION
REMEDIAL ALTERNATIVE SELECTION
Site; Delaware City PVC Site, New Castle County, Delaware
Documents Reviewed:
I am basing my decision principally on the following documents describing
the analysis of cost effectiveness and feasibility of remedial alternatives for
the Delaware City PVC Site:
v - "Remedial Action Feasibility Study": Delaware City PVC Site, New Castle
County (Malcolm Pirnie, Roux Associates, June 1986).
- "Hydrogeology and Groundwater Conditions": Delaware City PVC Site,
New Castle County (Roux Associates, February 4, 1983).
- "Interim Report, Groundwater Conditions": Delaware City PVC Site,
New Castle County (Roux Associates, June 1982).
_ "A Site Inspection Report": Delaware City PVC Site, New Castle County
(Ecology & Environment, Inc., June 28, 1982).
- "Hydrogeologic Review": Delaware City PVC Site, New Castle County
(Ecology and Environment, Inc., June 3, 1982).
- Staff summaries and Recommendations.
- Recommendation by the Delaware Department of Natural Resources and
Environmental Control.
Description of the Selected Remedy;
1. Off-grade Batch Pits - Excavate and remove existing polyvinyl chloride (PVC)
sludge and contaminated soils Co the levels to be determined at the design
stage; install a double synthetic liner, install monitoring wells and perform
quarterly sample analysis for trichloroethylene (TCE), 1,2, dichloroethane
(EDC) and vinyl chloride monomer (VCM), the contaminants of concern at the
site. The excavated material will be directly processed and recovered (estimated
by the companies to be 80-85%) as a saleable finished product to the maximum
extent possible. Non-recoverable material will be disposed of off-site at an
approved RCRA facility (est. I year).
2. Stormwater Reservoir (RV Pond) - The same remedy as described for the above
off-grade batch pits (est. 1 year).
3. Unlined Ditches - Excavate and remove PVC sludge, install a single synthetic
liner. The excavated material will be disposed of off-site at an approved
RCRA facility (est. 8 months).
4. Aerated Lagoons - Excavate and remove PVC sludge, clean and repair lagoons
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as necessary, Install a double synthetic liner, install monitoring wells and
perform quarterly sampling analysis for TCE, EDC and VCM. The excavated material
will be recovered to the maximum extent possible (estimated by the companies Co be
80-85%) and non-recoverable material will be disposed of off-site at an approved
RCRA facility (est. 18 months).
5. Closed Buried Sludge Pits - Place a drainage layer on top of the existing
synthetic cap, and cover with a second synthetic cap (or comparable substitute in
compliance with the requirements of RCRA) and topsoil and then revegetate
(est. 1 year).
6. Former PVC Storage Area - Cover and cap the entire area with a double syn-
thetic cap (or comparable substitute in compliance with the requirements of RCRA)
and then revegetate (est. 6 months).
7. Groundwater - Install a line of six groundwater recovery wells at the
northern edge of the contaminant plume, and another six wells at the southern
edge. Reuse the collected groundwater in Formosa's plant operations. During
periods of low water demand in the plant, treat the groundwater in the existing
waste water treatment plant. Install two monitoring wells at the southern edge of
the plume. Provide an alternate water supply for existing contaminated wells.
8. Operation and maintenance (O&M) for the remedy will include as a minimum
regular inspections and as necessary repairs to the liners and caps. The
groundwater recovery system will be routinely monitored to assure that it is
capturing the contaminated plurae.
Declarations •
Consistent with the Comprehensive Environmental Response, Compensation,
and Liability Act of 1980 (CERCLA) (42 U.S.C. § 9601-9657) and the National
Contingency-Plan (40 CF R Part 300), I have determined that the remedial
action described above, together with proper operation and maintenance consti-
tutes a cost-effective remedy which mitigates and minimizes damage to public
health, welfare, and the environment. The remedial action does not affect
or violate any floodplain or wetland area. The State of Delaware has been con-
sulted and agrees with the approved remedy. In addition, the action will require
future operation and maintenance activities to ensure the continued effectivenes?;
of the remedies. These activities will be considered part of the approved
action and eligible for Trust Fund monies for a period of six months following
completion of construction.
In addition, the off-site disposal of contaminated soil to a secure hazardous
waste facility is necessary to protect public health, welfare and the environment
I have determined that the action being taken is appropriate when balanced
against the availability of Trust Fund monies for use at other sites.
r\
.._
"*• f. • ij'" . *• *~*i
// James M. -Self •)
REGIONAL ADMINISTRATOR
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SUMMARY OF REMEDIAL ALTERNATIVE SELECTION
DELAWARE CITY PVC SUPERFUND SITE
SITE DESCRIPTION
The Delaware City PVC Site is located approximately 2 miles northwest of
Delaware City at latitude 39°35'16"N and longitude 75°38'50"W in New Castle
County, Delaware. The site is situated on State Route 13 just west of the
Getty Refining and Marketing Company between Red Lion Creek to the north, and
Dragon Creek to the south. The area of the study site is approximately 260
acres. (See Figure #1)
-f The Delaware City PVC Site consists of a Polyvinyl Chloride (PVC) manu-
facturing facility owned and operated by Formosa Plastics Corporation (Formosa).
From 1966 until May, 1981, Stauffer Chemical Company (Stauffer) manufactured
PVC resin and processed vinyl chloride monomer at the facility. In May 1981,
Formosa acquired the PVC manufacturing and processing facility and has continued
operations to present. Stauffer has retained ownership of an existing carbon
disulfide plant adjacent to Formosa's property. In April, 1982, one of the
domestic supply wells on Stauffer's property became contaminated with 1,2
dichloroethane (EDC), vinylchloride monomer (VCM) and trichloroethylene (TCE).
This occurence prompted Formosa and Stauffer to perform a hydrogeologic
investigation, conducted by Roux Associates, which identified the sources of
ground water contamination (See Figure #2). The following sources were identified
at the site:
1. Off-grade Batch Pits - unlined earthen lagoons which receive waste-
water from the S-l and S-2 production areas, when the wastewater
sumps in these areas overflow. These lagoons also serve as surge
reservoirs during periods when the wastewater effluent cannot be
discharged to the Delaware River. PVC solids contaminated with EDC,
VCM and TCE are also deposited in these lagoons. This sludge-like
material must be periodically excavated and disposed of off-site.
2. Stormwater Reservoir (RV Pond) - an unlined earthern basin used pri-
marily for storm water collection. This pond occasionally receives
process wastewater and PVC solids from the production area (E-2) when
the wastewater sump overflows.
3. Unlined Ditches - these ditches conduct stormwater runoff from the
plant site to the off-grade batch pits and the RV pond. Process
wastewater is also discharged to these ditches when the production
area sumps overflow. PVC solids have been deposited at several
locations in the ditches.
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4. Aerated lagoons - concrete lined lagoons which receive wastewater
and PVC solids for treatment. The potential for leakage from the
aerated lagoons exists through cracks in the concrete liner.
5. Closed Buried Sludge Pits (Burial Pits) - unlined pits which were
used to dispose of PVC solids and sludge from the aeration lagoon.
In 1979, Stauffer closed out the pits with a synthetic cap made from
PVC and designed to prevent percolation. The cap was then covered
with soil and revegetated.
6. Former PVC Resin Storage Area - A former PVC resin storage area was
excavated and regraded in 1974 by Stauffer. Recent sampling has
-f indicated the presence of resin residue with EDC, VCM and TCE
concentrations at levels of concern.
The Closed Buried Sludge Pits and the Former PVC Resin Storage Area are
located on the Carbon Bisulfide Plant property owned by Stauffer Chemical
Company and are no longer in use. The remaining sources are part of the active
manufacturing process at the Formosa Plastics Plant.
The hydrogeologic investigation identified a plume of contamination consisting
of EDC, VCM and TCE in the lower portion of Columbia aquifer. High concentrations
of EDC, VCM and TCE arc present in the ground water in an area adjacent to,
and west of the PVC plant. The Roux report recommended evaluating remedial
actions to eliminate the major sources of EDC, VCM and TCE on the property and
eliminating the ground water pollution.
SITE GEOLOGY
The site is located within the Atlantic Coastal Plan Geologic Province
and is underlain by southeasterly dipping, unconsolidated sedimentary strata
of Cretaceous age.
The Cretaceous deposits mantle the irregular surface of the crystalline
bedrock and have been locally divided into three formations. The oldest or
deepest deposits are called the Potomac Formation. The Potomac consists of
silt and clay beds with sandy layers or lenses that serve locally as aquifers.
'The sand lenses encountered between clay layers are generally thinner than the
clays. The sand layers divide the Potomac Formation into three zones, the
Upper, Middle, and Lower. The Potomac Formation is an important municipal
and industrial water supply source in the area. (See Figure #3)
Stratigraphically overlying the Potomac Formation within a portion of the
area of investigation, is a layer of white, "sugery", fine-grained sand known
as the Magothy formation.
Above the Potomac and Magothy formations in the study area, is the
Merchantville Formation which belongs to the Matawan Group of Upper Cretaceous
Age.
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The Merchantville Formation consists of greenish-grey clayey silt with
clay, which is locally abundant as the in filling of burrows of benthic organisms.
The Merchantville Formation has a low permeability and thus serves as an
aquitard which hydraulically seoarates the sand of the Magothy and Potomac
Formations from the overlying Columbia aquifer. Where the Merchantville is
absent, clays of the Upper Potomac are present directly below the Columbia and
serve the same purpose. All evidence from this investigation indicates that
the Columbia is continuously underlain by an aquitard.
Overlying the irregular topography of the Merchantville is the Columbia
Formation which is Pleistocene in age. The Columbia Formation in Northern
Delaware consists of quart & sand with minor interbeds and lenses of gravel,
sj.lt and clay. The Columbia aquifer is a water supply source for many residents
o'f this area.
HYDROGEOLOGY OF COLUMBIA AQUIFER
The drilling and sampling program performed during the RI has concentrated
on the Columbia Formation, because this is the aquifer that was found to contain
EDC, VCM and TCE. The resistivity survey that was also performed during the
investigation has helped to confirm the continuity of the Merchantville and/or
Potomac clay under the entire study area. It has also demonstrated that the
Potomac clay layer is continuous under the Magothy sand layer which is present
in the western portion of the site. Due to the presence of the Potomac clay
present in the area it can be concluded that the Potomac formation is not
threatened by contamination at the present time.
•
Water table maps prepared during the RI report show indications of a
"mound" in the water table under the western portion of the PVC plant property.
The highest water level in this mound was recorded at Observation Well
OW-11, east of the identified sources. This mound is probably caused by
water losses at the plant (fire water ponds, cooling water towers) upgradient
of the identified source area. Ground water flows from the area of this
mound under the sources to the northwest, west and southwest toward U.S.
Route 13. Ground water to the west of Route 13 flows east to converge with
the flow from the plant. Thus, ground water flowing to the northwest, toward
OW-5, turns in a northerly direction (roughly parallel to Route 13) and
flows toward Red Lion Creek. Ground water flowing from the PVC plant toward
OW-16 turns in a southerly direction and flows to Dragon Run. (See Fig. 4)
Within the Columbia aquifer on the Stauffer property, there is a downward
component of groundwater flow typical of a recharge area. The underlying
Merchantville formation will restrict further movement of ground water into
the deeper aquifer. This explains why EDC, VCM and TCE can be found in only
the lower portions of the Columbia Aquifer.
Site History
In 1966 Stauffer Chemical Company of Westport, Connecticut, founded the
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Delaware City PVC Plant, which is used for the manufacturing of polyvinyl-
chloride resin (PVC), polyvinyl acetate and other polymers. From 1971 to
1974 off-grade PVC resin, sludge from the wastewater treatment system and
residue from the stripping process were disposed of in two on-site pits.
These "buried sludge pits" were closed and covered in 1979. Off-grade PVC
resin was disposed of in a third pit. This material was removed and the
pits backfilled in 1974. These three pits constitute the areas onsite
where disposal of waste occurred.
In May 1981, Stauffer Chemical Company sold the PVC Plant to Formosa
Plastics Corporation, who currently operates the facility. The sale did
not include the property on which the two buried sludge pits are located and
on which the third disposal pit, now backfilled, was also located. This property
was retained as part of the Stauffer Chemical Company Carbon Disulfide Plant,
which is located adjacent to the PVC Plant property.
On March 9 and 10, 1982, EPA conducted an inspection and sampling of the
Delaware City PVC Plant. A total of 20 samples were obtained, including 8
surface water, 9 monitoring well, 2 industrial well, 2 residential well, 3
soil, and 1 waste sample. Sample results from this inspection have indicated
that serious contamination of the shallow groundwater in the Columbia Formation
exists under the site. In particular, high levels of VCM, TCE, and EDC were
found in ground water samples from monitoring wells located in the vicinity of
the lagoons and buried sludge pits.
Subsequent to this inspection, Stauffer Chemical Company and EPA conducted
sampling of the residential wells located northwest of the sources in the
shallow (Columbia) aquifer. The results showed significant contamination of
the wells with EDC and VCM. The impacted domestic wells (3 wells) were immediately
replaced with an alternative water supply (tank truck and bottled water).
The residential well contamination prompted Stauffer to conduct a hydrogeologic
investigation. This detailed hydrogeologic investigation included: the installation
of 32 monitoring wells, a sensitivity survey, and well sampling. The results
are described in the Roux Associates, Inc. report dated February 4, 1983.
The findings and conclusions from the Roux report are outlined below:
1. "The shallow geology in the area of investigation, from the land
surface downward, includes: layers of sand (Columbia Formation); a
clayey silt aquitard (Merchantville Formation); a sand layer (Magothy
Formation); and a thick clay layer of the Potomac Formation.
2. The Merchantville Formation and upper clay layer of the Potomac Formation
are apparently continuous beneath the site and hydraulically separate
the Columbia aquifer from deeper Potomac aquifers.
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3T~ High concentrations of EDC and VCM are present in ground water in the
Columbia aquifer in the area adjacent to, and west of, the PVC plant.
4. The extent of EDC and VCM in the Columbia aquifer has been deter-
mined to be limited to an area of the Stauffer and Formosa properties
west of the PVC plant and possibly a small portion of Getty property
west of Route 13. Also, EDC and VCM is limited to the lower portion
of this aquifer.
5. Ground water flow in the Columbia aquifer from the western portion of
the PVC plant property is apparently in all directions. Observation
wells in the Columbia aquifer to the north, south, and east of the
plant do-.-not contain detectable concentrations of EDC or VCM. Observation
wells to the west of the plant do contain these compounds. Therefore,
based on the distribution of EDC and VCM in the Columbia, the flow of
ground water containing these compounds is to the west.
6. Based on the observed ground water flow directions and the concen-
trations of EDC and VCM in ground water samples from observation
wells, it appears that the source(s) of EDC and VCM are the surface
impoundments in the western portion of the PVC plant property. Based
on the construction of these impoundments, it is logical to assume
that the off-grade batch pits, which are unlined, are the principal
source.
7. Flow of ground water in Che Columbia aquifer to the west of the PVC
plant is apparently controlled by the slope of the upper surface of
the Merchantville, the presence of more permeable sediment in the
deeper portion of the Columbia, and a ground water mound in the western
portion of the PVC plant property.
8. The rate of ground water flow in the Columbia aquifer is estimated to
range between 0.3 and 1 foot per day (approximately 100 to 300 feet
per year).
9. The total volume of ground water flowing past the boundary of Stauffer's
property to the west (beneath Route 13) is estimated to be 100,000
gallons per day (70 gallons per minute). Only the deeper portion of
this flow contains EDC and VCM.
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10., -The Columbia aquifer is used locally for individual domestic supplv.
The deep Potomac aquifer is used locally by Getty for industrial
water supply.
11. No water supply well within the area of investigation, domestic or
industrial, (except for one on-site Stauffer residence) contains
detectable concentrations of EDC or VCM. The one exception (in addition
to the Stauffer domestic well) is a single finding in 1982 of 6.1 ppb
EDC in a supply well for an Stapleford Chevrolet Dealer on Route 13,
south of Wrangle Hill Road. However, this value was questioned in
the Roux Report since the concentration was near the detection limit.
12. Discharge from the Columbia aquifer appears to be to local streams, '
primarily Dragon Run.
13. None of the stream samples collected in the study area contained
detectable concentrations of EDC or VCM."
In May 1984, EPA and the Department of Natural Resources and Environmental
Control (DNREC) entered into a Consent Order with Stauffer and Formosa to per-
form a Feasibility Study (FS) for the site and to implement an approved remed-
ial action. The final FS was submitted to EPA in June 1986 and was released for
public comment on July 25, 1986.
CURRENT SITE STATUS
After the submittal of the Roux Associates report, Stauffer and Formosa
continued ground water monitoring in order to track the migration of the ground
water plume. During one of these sampling efforts in 1983, EDC and VCM were de-
tected in the Foraker Getty Service Station and Stapleford Chevrolet dealer
wells south of the previously mapped plume area. Stauffer provided an alternate
water supply (tank truck and bottled water) to the owners of these two wells.
This sampling confirmed the contamination of the auto dealer's well questioned
by Roux in 1983.
In August 1985, Stauffer provided city water from their plant to the three
residences on their property. In 1986, the telephone company relay station
well located south of the Foraker Getty and Stapleford Chevrolet wells, also
became contaminated with EDC, VCM and TCE. The owner of the well was also
provided with a temporary water supply by Stauffer and Formosa.
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A permanent solution for the Foraker Getty, Stapleford Chevrolet and
telephone company relay station wells will be specifically addressed during
the recommended remedial action.
ADDITIONAL REMEDIAL INVESTIGATION ACTIVITIES
In accordance with the Consent Agreement, Stauffer and Formosa performed an
additional remedial investigation (RI) at the site. This additional RI work in-
cluded the installation of monitoring wells , pump testing, and soil testing.
With regard to monitoring, four (4) additional monitoring wells were installed to
identify the extent of the plume migration. Two monitoring wells OW-30 and OW-31
were installed to define the southern limit of the plume and two monitoring wells
-OW-32 and OW-33 were installed to determine the northern limit of the plume. These
monitoring wells, including other selected wells, were sampled during the August
and December 1984 sampling efforts (see Tables 1 and 2).
The results of the August and December 1984 sampling were compared with the
limits of the plume identified in the Roux Associates report dated February 4,
1983. A comparison of the previous sampling results and the later results indi-
cated:
1. The ground-water sample collected in August 1984 from OW-30 shows
levels of 1,100 ppb EDC and 50 ppb VCM (Table 1). This finding is
consistent with the ground-water flow directions mapped for the area
and more significantly, this well showed no EDC or VCM the first time
it was sampled.
2. It appears that the plume has stabilized in the northerly direction.
Despite findings of EDC and VCM in OW-5 from the inception of the
project, OW-33, and OW-32 have never shown EDC or VCM. This situation
is the result of this area of the Columbia aquifer being significantly
less permeable with a lower gradient than those to the south.
3. Neither EDC or VCM were detected in the wells west of Route 13 (OW-33,
OW-29, OW-28).
A pump test program was conducted to determine the aquifer hydraulic para-
meters necessary for the design of a potential groundwater intercept system. It
was determined that recovery wells could be pumped between 10 and 15 gallons
per minute (gpm) over an extended period of time.
A total of ten test pits in the former PVC resin storage area
(TP 9-18) were excavated on October 23, 1984 under the supervision of a
geologist .from Roux Associates. The purpose of excavating these pits was to
investigate this potential source area and to determine its significance with
regard to local groundwater contamination. Samples were collected, logged,
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and delivered to Stauffer's Eastern Research Center for VCM, EDC, and
TCE analysis. A minimum of two samples were collected from each test
pit, with at least one sample normally being collected from natural
sediments underlying any fill or resin. The locations of the test
pits are shown on Figure 5 and analysis results are given in Tables 3 & 4.
Four additional test pits (TP19-22) were excavated on November 29, 1984.
The purpose of these pits was to further define the extent of the PVC
resin. Analytical results for these resin/soil samples are given in
Table 2. Overall the concentrations of EDC in the soil ranged from
non-detectable (ND) to 120 parts per million (ppm) and the concentrations
of TCE ranged from ND-210 ppm. Note: the detection limit in soil is 4
ppm.
EflDANGERMENT ASSESSMENT
The Feasibility Study performed by Malcolm Pirnie provided an analysis
of the potential environmental and health-related impacts represented by the
contaminants VCM, EDC, and TCE. The analysis used available physiochemical,
toxicological and fate assessment data, relative to the above contaminants, in
order to screen and evaluate potential pathways of exposure, receptors and
associated health and environmental risks.
For any of the above mentioned compounds to represent a potential threat
to environmental or human receptors, an exposure pathway from these source
areas to the receptors must exist. The significance of air, surface water,
soil and ground water as potential exposure pathways was considered and
evaluated:
Air - The small amount of volatilization of EDC, VCM and TCE from the
unlined ditches, batch pits, RV pond and aeration lagoons is the primary
release mechanism to air from the identified sources. It is estimated that
total VCM emissions from the unlined ditches, batch pits, RV pond and aera-
tion lagoons amount to 0.33 Ib/day. Relative to releases controlled under
the Clean Air Act from the active operation ,the release of VCM, EDC, and TCE
represents an insignificant exposure pathway.
Soil - Two types of exposure pathways, direct and indirect dermal con-
tact, are considered in the evaluation of on-site soils. The most signifi-
cant pathway is direct dermal contact with PVC sludges containing VCM,
EDC or TCE, during their removal or by unauthorized persons entering the
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site. Direct dermal contact is highly unlikely. During periods of exca-
vation and removal, specific worker protective controls will be employed
and, in addition, plant security measures are more than sufficient to
ensure that unauthorized site access will not occur.
The second pathway is indirect contact and involves the contamina-
tion of ground water through leaching of the VCM, EDC and TCE from overlying
PVC sludges. The Remedial Investigation Study concluded that ground water
contamination by indirect contact with on-site PVC sludges constitutes the
greatest environmental and human health threat. The proposed remedial
alternative measures will eliminate contaminated PVC sludges as an indirect
exposure pathway to environmental and human receptors.
Surface Water - Ground water containing VCM, EDC and TCE is migrating
northerly toward Red Lion Creek and southerly toward Dragon Run. Serving
as a discharge point for the contaminated ground water plume, these surface
waters represent a potential exposure pathway for aquatic biota and humans.
Available data from the literature, however, indicates that the rapid
volatilization rates for VCM, EDC and TCE under the turbulent stream
conditions found in typical surface waters will significantly reduce
these contaminant levels. Red Lion Creek and Dragon Run may not be
turbulent to the point of producing volatilzation rates comparable to
the literature. Nevertheless, the potential impacts of the contaminants
reaching the surface water must be addressed.
Ground Water- A detailed hydrogeologic investigation has confirmed the
presence of the contaminants VCM, EDC and TCE In the Columbia aquifer. This
aquifer serves as a drinking water supply for residents in the surrounding
area and, therefore, represents a significant potential threat for direct human
exposure via ingestion, inhalation and dermal contact. Consumption of con-
taminated ground water by local residents represents the most significant
site-related exposure pathway and health risk threat.
Potential human and environmental receptors at this site are described
below:
Human Receptors - As discussed earlier, the most significant potential
exposure pathway is via the ground water. A concern exists that residents
could potentially be exposed to the contaminants via ingestion of the ground
water or via inhalation of vapors or dermal contact during cooking, bathing,
and other domestic uses. Samples collected from monitoring wells as part
of the Remedial Investigation Study indicate the presence of VCM, EDC, and
TCE. The use of the three wells on Stauffer property serving residences has
been discontinued due to contamination in one well by VCM and EDC.
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Rydrogeologic investigations indicate that the ground water plume is
moving away from the site in a northerly direction, towards Red Lion Creek,
and in a southerly direction towards Dragon Run. An estimated 25-30 resi-
dences that utilize ground water are located downgradient of the northerly
and southerly paths of the plume. These residences are located along Route 13
north of its intersection with Route 7, in the vicinity of the intersection
of Route 13 and Wrangle Hill Road, and further to the south along Route 13.
Only one of these residential wells may be tapping deeper, protected aquifers.
A hydraulic connection, between the ground water and Red Lion Creek
and Dragon Run, represents a potential exposure pathway via surface
water, since these creeks are used for recreational or drinking water
purposes.
Off-site exposure of humans to VCM, EDC, and TCE via air or soil is
not likely since the release of contaminants from source areas to air is
insignificant and soil dermal contact is virtually non-existent.
Environmental Receptors - Future potential environmental receptors of
the contaminants VCM, EDC and TCE include the aquatic and terrestrial biota
of the surrounding area, however, there is very little information on the actual
biotic communities present. The area is largely rural with some commercial/
industrial development. The primary pathway for exposure of biota is through
surface waters potentially contaminated by groundwater. The persistence
of these contaminants in surface waters would be limited, as discussed
previously. In addition, data on VCM, EDC and TCE in the literature indicates
that none of these three substances has a high potential for bioaccumulation
or biomagnification in aquatic or terrestrial biota.
ALTERNATIVE EVALUATION
The major objectives for the remedial action to be taken at the
Delaware City PVC site are to abate the sources of contamination and to
mitigate the existing plume of contaminated ground water. This would
involve preventing and/or reducing: a) infiltration through the sources;
b) further migration of the existing contaminated shallow ground water;
c) direct contact of the soil with the PVC resin; d) future contamination
of the Potomac Formation, and e) the degradation of surface waters. The
requirements of CERCLA Section 104, EPA's mandate to protect the public
health and welfare and the environment, determine the goals and level
of response for the site.
In an effort to determine remedial alternatives for the subject site,
feasible technologies were identified. These technologies were then
screened to eliminate all but the most practicable and implementable ones.
This screening considered: technical, public health, environmental,
institutional, and cost considerations. Those technologies that passed
the technology screening process were used to form remedial alternatives.
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The remedial alternatives were developed using best engineering judgement
to select a technology or group of technologies that best addresses the
problems existing at the site to protect public health, welfare, and the
environment. In an effort to provide a degree of flexibility in the final
selection of a remedial action, alternatives covering a range of remedial
action categories have been developed.
These categories are described below:
a) No action
b) Alternatives for treatment or disposal in an off-site facility.
c) Alternatives which attain public health and environmental standards
as defined by CERCLA.
d) Alternatives which exceed public health and environmental standards
as defined by CERCLA .
e) Alternatives which do not attain public health or environmental
standards but will reduce the likelihood of present or future
threat.
In order to establish a means of evaluating the developed remedial
alternatives, Section 300.68(h) of the National Contingency Plan (NCP) was
reviewed. In accordance with the NCP, criteria were selected by Malcolm Pirnie
to evaluate the developed alternatives. With the exception of public acceptance,
the selected criteria presented below are consistent with the EPA Final Draft
Guidance Document for the preparation of Remedial Action Feasibility Studies
under CERCLA dated October 18, 1984 (Draft Guidance Document) and are defined
as follows:
Criterion Definition
Environmental Environmental effectiveness is defined as the ability
Effectiveness of a particular remedial alternative to provide miti-
gation of future ground water and surface water contami-
nation.
o
Reliability Reliability is defined as the level and difficulty of
operation and maintenance (O&M) requirements for a demon-
strated technology to reach and maintain the desired per-
formance.
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Public
Acceptance
Constructlbility
Time Frame
Safety
Public acceptance is defined as the reaction most likely
to be expressed by the neighboring communities to the
potential health effects of a particular remedial alter-
native. Community opposition can prevent viable plans
from being implemented.
Constructibility is defined as the labor effort and degree
of construction difficulty necessary to implement a parti-
cular remedial alternative considering the physical charac-
teristics of the site and external factors such as construc-
tion equipment and materials availability.
Time frame is defined as the length of time it takes to
complete the construction of a particular remedial alter-
native.
Safety is defined as the amount of precaution necessary to
prevent accidental exposure from occurring to either on-site
workers or nearby residents during the actual implementation
of a particular remedial alternative or for disposal off site,
The developed remedial alternatives were ranked (using the matrix approach as
described in Chapter 3 of the Draft Guidance Document) with the six criteria defined
above. Weighing factors for each criterion, which vary from 0.5 to 1.2, were also
developed and used in the evaluation process. The weighing factors used by Malcolm
Pirnie were based on prior Remedial Investigation/Feasibility Study (RI/FS) documents
and attempt to reflect the relative importance of the individual criteria.
A rank ordering technique was used as an effective method to eliminate inappro-
priate alternatives from further detailed consideration.
ANALYSIS OF REMEDIAL ALTERNATIVES
Note:. Tables 5 & 6 contain costs for all alternatives.
Elements common to alternatives below:
o Offsite Disposal - The FS prepared by Malcolm Pirnie discusses three
options for the excavation and disposal of the PVC sludge from the
impoundments. These options are: excavation and disposal of the PVC
sludge in a municipal landfill, excavation and disposal of the PVC sludge
in a RCRA Hazardous Waste Management Facility (HWMF) and the recovery of
the PVC sludge to the maximum extent possible as a saleable finished
~ product and disposal of the non-recoverable soil/PVC mixture in a RCRA
HWMF.
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fhe disposal of the PVC sludges in the municipal landfill does not comply
with the Agency's policy regarding the off-site disposal of Superfund
waste. The Off-Site Disposal Policy requires all of the waste from a
Superfund site to be taken to a RCRA HWMF. Therefore, this alternative
was determined to be unacceptable by EPA.
The disposal of the PVC sludge at a RCRA HWMF while complying with
the Agency's Off-Site Policy is an expensive alternative (approximately
2-3 times cost of disposal at a municipal facility) and does not
necessarily provide a .permanent remedy. The recovery of the sludge and
disposal of the excess waste in a RCRA facility is cost effective and
environmentally effective, because it reduces the amount of waste to be
taken off-site, provides a permanent remedy for a significant percentage
of the existing PVC sludge, is less expensive than disposal of all the
PVC sludge in a RCRA facility and is comparable in cost to the disposal
of all the PVC sludge in the municipal landfill. It also attains all
environmental and public health standards under CERCLA.
The recovery of the PVC sludges to the maximum extent possible
(estimated by the companies to be 80-85%) as a saleable finished product
and disposal of the non-recoverable soil/PVC mixture in a RCRA Hazardous
Waste Management Facility (HWMF) will be -used in the source control
alternatives.
Use of RCRA controls - Most of the alternatives listed below include the
installation of some type of liner or cap to prevent or minimize the
continuing leaching of contaminants into the groundwater at the site. The
Malcolm Pirnie study discusses the use of clay, single synthetic and double
synthetic liners, concrete lining for the trenches and single and double
synthetic caps.
The National Contingency Plan ( Section 300.68(j), 47 Fed. Reg., 31180
[July 16, 1982]) states that the remedial alternative selected will be the
one the Agency determines is cost effective (i.e. the lowest cost alternative
that is technically feasible, reliable, and which will effectively mitigate
or minimize damage to human health, welfare and the environment.) In
addition, in selecting a remedial action for this site, the EPA must also
consider all other applicable environmental laws including RCRA.
Vinyl chloride is a RCRA listed waste in pure form, but when mixed with
byproducts of manufacturing, the waste mixture is exempt. EPA examined
the technical alternatives presented and available to minimize migration
of contaminants. The relevant standards for caps and liners, outlined in
RCRA for control of migration of hazardous wastes, were seen to provide
the control that is required. Therefore, the alternatives were evaluated
in this light to insure that they meet the requirements of CERCLA and the
NCP and are essentially those that would be required under RCRA.
The design requirements for multi-media or multiple caps and liners
outlined in RCRA are suitable for storage areas and treatment units because
they allow better environmental protection than single liners and enable
monitoring of the upper cap or liner to identify failures before
serious leakage results.
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ANALYSIS OF REMEDIAL ALTERNATIVES (cont)
A. Off-grade Batch Pits and RV Pond Remedial Alternatives
These two sources have been considered together since the same remedial
actions apply to both. In developing remedial alternatives, it was determined
that Formosa would continue to keep both the offgrade batch pits and the RV
Pond in service due to their importance in the continued operation of the
Plant. Hence, any alternatives in which these impoundments are taken out of
service were initially screened out.
Alternative No. 1 - No Action
This alternative involves no remedial action and leaves the sources
in their existing state. Both off-grade batch pits and RV pond are of
earthen construction which is not suitable for retaining wastewater. At the
present time, the PVC sludges placed in these basins are in direct contact
with the soil and cause groundwater contamination through leaching of the
VCM, EDO, and TCE. The groundwater contamination through direct contact
with on-site PVC sludges constitutes the greatest environmental and human
health threat. A no action alternative would provide no additional protection
to the public health or environment and the contamination of soil and
groundwater would continue.
Alternative No. 2 - Recovery of the PVC Sludges and Installation of a
Clay Liner
This alternative includes excavation of the PVC sludges and co'ntaminated
soil to levels to be determined at the design stage and recovery of PVC to
the maximum extent possible. Disposal of non-recoverable material will be at
an off-site RCRA HWMF. This alternative also includes installation of a
three foot clay liner compacted to a permeability of 10-^ cm/sec.
Since this alternative involves excavation and recovery of contaminated
sludges, the risk of further groundwater contamination from these sludges
will be eliminated. The clay liner will prevent the leaching of VCM, EDC,
and TCE into the groundwater. The clay liner, however, may not be completely
reliable due to the potential for cracking, thus jeopardizing the integrity
of the liner. This alternative does not attain public health and environmental
standards as defined by CERCLA.
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Alternative No. 3 - Recovery of the PVC Sludges and Installation of
a Single Synthetic Liner
This alternative includes excavation of the PVC sludges and
contaminated soil to levels to be determined at the design stage, and
recovery of PVC to the maximum extent possible. Disposal of non-recoverable
material will be at an off-site RCRA HWMF. This alternative also includes
installation of a single synthetic liner. .Prior to installation of a
synthetic liner, the site will be carefully graded to remove rocks and
other materials that may puncture the liner and a layer of clay or geotextile
material may be placed as a sub-base. A one foot thick layer of clay will
be placed on top of the synthetic liner to protect against weathering.
Three downgradient monitoring wells will be installed to monitor any
potential contaminant migration from the pits and the pond. The wells
will be initially sampled on a quarterly basis for PH, TOC, TOX, conductivity,
VCM, TCE and EDC. If sampling results from two consecutive quarters are
found to be consistent and acceptable, further sampling may be extended to
semi-annually. In addition, a Hazardous Substance List (HSL) analysis
will be conducted once a year.
Since this alternative involves recovery of contaminated sludges, the
risk of ground water contamination from these sludges will be eliminated.
The single synthetic liner is more environmentally effective than a clay
liner, but single liners do not attain public health and environmental
standards as defined by CERCLA.
«
Alternative No. 4 - Recovery of the PVC Sludges and Installation of
a Double Synthetic Liner
Under this alternative, the contaminated sludges and soil will be
excavated to levels to be determined at the design stage and will be
recovered to the maximum extent possible. Non-recoverable material will
be disposed of off-site in a RCRA HWMF. The risk of groundwater
contamination from direct contact of these sludges with the soil will be
eliminated. This alternative also includes installation of a double
synthetic liner. Prior to installation of the lower (secondary) liner,
the site will be carefully graded to remove rocks and other materials that
may puncture the liner. Then a layer of clay will be placed as a sub-base
on the graded site. After the secondary liner is placed, a loose fill
material (sand/gravel) will be installed on top. This fill material will
provide drainage to a leak detection system which will also be installed
at that time. The leak detection system is generally a slotted pipe that
is pitched to a sump located outside of the impoundment. Due to the slope
of the pits and the RV pond, a loose fill would not remain on the side
slopes. A geotextile fabric will, therefore, be placed between the
synthetic liners along the side slopes. Above the drainage layer an upper
synthetic liner will be installed and a one-foot thick clay layer will be
placed on top of the upper synthetic liner to protect it against weathering
and erosion. The liner and geotextile fabric will be tied into the berm
around the impoundment with the top clay cover extended to cover the tie-in.
The monitoring requirements for this alternative would be the same as for
the single liner alternative described earlier.
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Th e double liner alternative will provide the most protection against
groundVate'r contamination. Any wastewater that possibly penetrates through
the first liner should be retained by the second and detected by the detection
system. Hence, the environmental effectiveness of the double liner is considered
to be excellent.
Reliability of the double liner is judged to be excellent due to low
operation and maintenance requirements once the system is installed. In addition,
double synthetic liner systems with leak detection systems have demonstrated
their reliability and applicability at similar sites. In particular, the
double liner is more reliable in preventing leakage than the clay or single
synthetic liner over time and represents a small increase in cost.
The double liner alternative meets all public health and environmental
standards as defined by CERCLA.
B. Unlined Ditches Remedial Alternatives
In developing remedial alternatives for the unlined ditches it was deter-
mined that Formosa would continue to operate the ditches as part of their
wastewater treatment plant. It was also determined that the PVC sludges with-
in the unlined ditches cannot be recovered due to contamination with soil in
the ditches and, therefore, approximately 100 cubic yards (cy) of solids will
be removed and disposed of in a RCRA HWMF. The amount of solid material to be
removed is based on a one foot deep excavation along an estimated twenty five
percent of the total length of the unlined ditches. The actual areas which
require excavation were visually noted during a 1985 site visit, based on
the presence of the white PVC residue.
Alternative No. 1 - No Action
This alternative involves no remedial action and leavas the source in
its existing state. The unlined ditches are of earthen construction and do
not prevent leaching of VCM, TCE, and EDC from the PVC solids into the
groundwater. The groundwater contamination through contact with on-site
PVC sludges constitutes the greatest environmental and human health threat.
A no action alternative would provide no additional protection to the public
health and the environment and the contamination of soil and groundwater. would
be expected to continue.
Alternative No. 2 - Installation of Concrete Trench
In this alternative no contamination would be removed and a pre-cast 4-inch
thick concrete liner would be placed in the ditches (see Fig. 7). The concrete
trench would be susceptible to erosion and cracking during its operation. If
cracking does occur, it could cause further ground water contamination due to
leaching of the VCM, EDC, and TCE from the PVC sludges that are left in the
ditches. Thi.s alternative does not attain public health and environmental
standards as defined by CERCLA.
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Alt'ernative No. 3 - PVC Sludge Excavation and Installation of Single
Synthetic Liner
In this alternative, contaminated sludges will be removed and disposed of
off-site in a RCRA HWMF. The risk of groundwater contamination due to direct
contact of the sludges with the soil will be eliminated. This alternative
also involves installation of a single synthetic liner (see Fig. 7). These
ditches convey waste to storage areas and are not storage areas themselves.
Single liners are believed to provide an adequate barrier and effective protection
of the groundwater. Prior to installation of the synthetic liner, the site
will be carefully graded to remove rocks and other materials that may puncture
the liner. A geotextile fabric will be used as the sub-base material to protect
the liner from puncturing. The geotextile fabric will also help to
keep the side slopes from eroding.
The PVC sludge excavation and lining of the ditches with an impermeable
synthetic liner will significantly reduce the potential for leakage into the
groundwater. The environmental effectiveness of the synthetic liner was judged
to be excellent compared to that of a concrete trench. There are concerns
regarding the stability of the synthetic liner with the eroding side slopes,
however, the geotextile fabric will be helpful in controlling this factor.
This alternative attains public health and environmental standards as
defined by CERCLA.
Alternative No. A - PVC Sludge Excavation and Installation of Concrete Trench
In this alternative, contaminated sludges will be removed and disposed of
off-site in a RCRA HWMF. The risk of groundwater contamination due to direct
contact of sludges with the soil will be eliminated. This alternative also
includes installation of a pre-cast 4-inch thick concrete liner. The concrete
trench will be susceptible to erosion and cracking during its operation. If
cracking does occur, it could cause further groundwater contamination due to
leaching of the VCM, EDC, and TCE from the PVC sludges that are contained in
the ditches due to the active operations. This alternative does not attain
public health and environmental standards as defined by CERCLA.
C. Aerated Lagoons - Remedial Alternatives
In developing remedial actions/alternatives for the aerated lagoons it was
determined that Formosa would continue to operate the lagoons as part of their
wastewater treatment plant. Therefore, any alternatives in which these impound-
ments are taken out of service have not been considered. Additionally, the
recovery of the PVC sludges to the maximum extent possible as a saleable finished
product and disposal of the non-recoverable soil/PVC mixture in a RCRA HWMF will
be used in all of the source control alternatives.
Alternative No. 1 - No Action
This alternative involves no remedial action and leaves the source in its
existing state. The lagoons are constructed with a reinforced concrete liner,
which has eroded in different areas. At the present time, these lagoons are
not effective in retaining wastewater. The VCM, TCE and EDC found in the PVC
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sludges, move through cracks in the concrete liner and cause groundwater
contamination. The groundwater contamination at the site constitutes a
great environmental and human health threat. A no action alternative would
provide no additional protection to the public health or environment and the
contamination of soil and groundwater could be expected to continue.
Alternative No. 2 - PVC Sludge Recovery and Repair of a Concrete Liner
This alternative includes excavation of the PVC sludges and recovery of
PVC to the maximum extent possible. Disposal of non-recoverable material will
be in an off-site RCRA HWMF. The risk of groundwater contamination due to
leaching of the VCM, EDC and TCE through cracks in the existing concrete
liner will be eliminated. This alternative also includes the repair of the
existing concrete liner. After the liner is repaired, it will still be sensitive
to'erosion and cracking during its operation. If cracking does occur, it
could cause further groundwater contamination due to leaching of the VCM, EDC
and TCE from the PVC sludges. This alternative does not attain all public
health and environmental standards as defined by CERCLA.
Alternative No. 3 - PVC Sludge Recovery and Installation of a Single
Synthetic Liner
This alternative includes excavation of the PVC sludges and recovery of
PVC to the maximum extent possible. Disposal of non-recoverable material would
be in an off-site RCRA HWMF.
This alternative also includes repair of the existing concrete liner and
installation of a single synthetic liner over the existing liner. The risk of
groundwater contamination due to leaching of the VCM, EDC and TCE through the
cracks in the existing concrete liner would be eliminated.
After excavation of the accumulated PVC solids and crack repair,
geotextile fabric will be placed over the existing concrete to protect the
synthetic liner from wear and puncture. Monitoring wells will be installed
and sampled to verify the containment (as described for the offgrade batch pits
and RV pond). The single liner system placed over the cleaned and repaired
existing liner would provide more protection against leakage of the contaminants
to groundwater than the repaired concrete liner. However, a single synthetic
liner system does not attain all public health and environmental standards as
defined by CERCLA.
Alternative No. 4 - PVC Recovery and Installation of a Double Synthetic Liner
Under this alternative, the contaminated sludges will be recovered to the
maximum extent possible and non-recoverable material will be disposed of off-site
in a RCRA HWMF. The risk of groundwater contamination due to leaching of the
VCM, EDC and TCE through the cracks in the existing concrete liner will be
eliminated.
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This -alternative also includes repair of the existing concrete liner and
installation of a double synthetic liner over the existing liner. The double
liner system has been described previously: clay sub-base, secondary synthetic
liner, leak detection system, geotextile fabric, primary synthetic liner, and
clay cover. Monitoring wells will be installed and sampled to verify
containment (as described for offgrade batch pits and RV pond).
The double liner alternative will provide the greatest protection against
groundwater contamination. Any wastewater that could possibly penetrate through
the first liner should be retained by the second and detected by the leak
detection system. Hence, the environmental effectiveness of the double liner
is considered to be excellent.
Reliability of the double liner is judged to be excellent due to low
operation and maintenance requirements once the system is installed. In
addition, double synthetic liner systems with leak detection systems have
demonstrated their availability and applicability at similar sites.
The double liner is more reliable in preventing leakage than the concrete
or single synthetic liner over time and represents a small increase in cost.
The double liner alternative meets all public health and environmental
standards as defined by CERCLA.
D. Closed Buried Sludge Pits - Remedial Alternatives
The unlined closed buried sludge pits (approximately 30,000 ft^ in
area) were used to dispose of PVC solids and sludge from aeration lagoons. In
1979, these pits were closed out with a single 20 mil PVC cap, covered with
topsoil and revegetated. The capped area was graded to promote stormwater
runoff to a collection ditch which runs along the perimeter of the area. The
synthetic cap is tied into the ground beyond the extent of the contaminated
sludges and soils. It should be noted that direct contact of the buried sludges
with the underlying groundwater is not anticipated to be a problem, since the
water table lies below the deepest area of contamination.
Alternative No. 1 - No Action
In this alternative the existing cap would be periodically inspected for
signs of erosion, puncture, infiltration and repaired as necessary. An inspection
of the PVC liner conducted in July 1985 by Stauffer, indicated minimal to no
reduction of integrity of the cap system. The topsoil was uncovered at two
locations to sample the integrity of the PVC cap. These samples exhibited no
cracks, tears or perforations caused during six years of service.
The existing synthetic cap appears to prevent percolation of stormwater
since it promotes stormwater runoff to a collection ditch running along
the perimeter of the pits. However, if the cap is not maintained properly,
there is a potential for cracks, tears or perforations to occur which would
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contrib.ute-.to groundwater contamination through leaching of the VCM, EDC and
TCE. This alternative does not attain public health and environmental standards
as defined by CERCLA.
Alternative No. 2 - Recapping
This alternative involves placing 18" - 24" of loose material (sand/gravel)
to serve as a drainage layer on top of the existing synthetic liner and providing
an additional synthetic cap over the drainage layer. This new liner would
then be covered with topsoil and revegetated. The new liner would extend 10
feet beyond existing liner.
This double cap alternative will provide more protection against groundwater
contamination than a single synthetic cap. Any percolation that could possibly
penetrate through the first liner should be retained by the drainage system
and the second liner. The double cap is more reliable in preventing leakage than
the single cap over time and represents a small increase in cost. This alternative
meets all public health and environmental standards as defined by CERCLA.
Alternative No. 3 - Excavation and Removal
This alternative involves excavation and removal of all contaminated
material and disposal in a RCRA HWMF. Removing the contaminated soil and
sludges would entail excavating approximately 25,000 cubic yards. The area
would be regraded upon the removal of the contaminated material.
This alternative would eliminate the source of contamination and therefore
protect the groundwater from further contamination.
This alternative meets all public health and environmental standards as
defined by CERCLA.
E. Former PVC Resin Storage Area - Remedial Alternatives
The former PVC storage area (approximately 12,000 ft^ in area) had been
excavated and regraded in 1974 by Stauffer. During the performance of the FS,
fourteen test pits were excavated under the supervision of a geologist from
Roux Associates in order to determine the extent of contamination in this
source area. The concentrations of EDC in the soil ranged from ND to 120 ppm
and the concentrations of TCE ranged .from ND to 210 ppm. ND indicated con-
centrations less than the 4 ppm detection limit.
The remedial actions for the former PVC resin storage area involve preventing
the stormwater from contacting the PVC resin and contaminated soil that are
present on-site. The remedial alternatives, therefore, involve either removal
of all the contaminated material or capping to prevent storrawater percolation.
Direct contact of the contaminated material with the underlying groundwater is
not anticipated to be a problem since the water table lies below the area of
contamination.
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Alternative No. I - No Action
This alternative involves no remedial action and leaves the source in its
existing state. At the present time, the stormwater percolates through the
PVC resin and the contaminated soils and contaminates the groundwater through
leaching of the VCM, EDC and TCE. The groundwater contamination through storm-
water percolation constitutes an environmental and human health threat. The
no action alternative would provide no additional protection to the public
health and environment and the contamination of groundwater would be expected
to continue.
Alternative No. 2 - Excavation and Removal i
Under this alternative, the areas of highest contamination will be excavated
arid disposed of in a RCRA HWMF. Based on the analytical results from test pit
excavation and sampling, it was determined by Malcolm Pirnie, that test pit (TP)
12 and TP-14 should he excavated. TP-12 contained 210 ppm of TCE at a depth of 24'
and TP-14 contained 120 ppm of EDC and 50 ppm of TCE at a depth of 42". The
total amount of material removed will be 615 cubic yards. The highest
concentration of any contaminant to remain in the soil would be 27 ppra of EDC
located at a depth of 5"5" in TP-9.
This alternative would not provide protection against groundwater contami-
nation, because the leachate generated from the soil left on-site would cause
concentrations of contaminants in groundwater greater than the 10~6 Unit Cancer
Risk (UCR). This alternative does not meet all public health and environmental
standards as defined by CERCLA.
•
Alternative No. 3 - CappingtheAreas of Highest Contamination with Single
Synthetic Liner
Under this alternative the material would be left in place and the areas
of highest contamination will be capped with a synthetic cap. The cap would
be installed over a 2,700 square foot area around both TP-12 and TP-14. Prior
to cap installation, additional tests would be performed around TP-12 and TP-14
to confirm that significant levels of PVC sludges exist and warrant capping.
This alternative would not provide protection against ground water contami-
nation, because the leachate generated from the soil left uncovered would cause
concentrations of contaminants in the groundwater greater than the 10~6 UCR.
Also, the areas that will be capped may develop cracks, tears or perforations
if they are not properly maintained. This could contribute to groundwater
contamination through leaching of the VCM, EDC and TCE.
This alternative does not attain public health and environmental standards
as defined -by CERCLA.
Alternative No. 4 - Capping the Entire Area with a Single Synthetic Cap
This alternative involves installation of a synthetic cap over the entire
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area. The installation of the synthetic membrane would involve sub-base grading,
placement of a sand layer, installation of a membrane, topsoil placement and
vegetation of topsoil. The synthetic liner would also extend approximately 10
feet beyond the area of contamination.
This alternative does not attain public health and environmental standards as
defined by CERCLA.
Alternative No. 5 - Capping the Entire Area with a Double Synthetic Cap
This alternative involves installation of a double synthetic cap over the
entire area. The installation of a double synthetic liner would involve grading
the site, placement of a sand layer, installation of a lower membrane, installa-
tion of a drainage layer, placement of an upper membrane, topsoil placement
and vegetation of topsoil.
The double cap alternative will provide more protection against groundwater
contamination than a single synthetic cap. Any percolation that could possibly
penetrate through the first cap would be retained by the drainage layer and
the second cap.
The double cap alternative is more reliable in preventing leakage than a
single cap and represents a small increase in cost.
The double cap alternative meets all public health and environmental
standards as defined by CERCLA.
F. Groundwater - Remedial Alternatives
At the present time, groundwater containing EDC, VCM nd TCE is flowing
west from the area of the identified sources. Groundwater flowing to the
northwest toward OW-5 turns in a northerly direction (roughly parallel to Route
13) and flows towards Red Lion Creek. Groundwater flowing toward OW-16 turns
in a southerly direction and flows towards Dragon Run. The alternatives to be
discussed below involve either plume remediation or plume management. For the
alternatives that involve plume remediation, the recovered water will be used
in Formosa's PVC plant operations. During any low water demand period at the
plant, the recovered water will be discharged to Formosa's wastewater treatment
plant. The discharge of the treated groundwater will be in compliance with NPDES
standards.
Alternative technologies considered for groundwater remediation included
biological-; physical and chemical treatment. Due to low concentrations of
contaminants in the groundwater, most alternatives were eliminated on both a
technical and cost basis. Air stripping remained after initial screening but
was not chosen because reuse of the water in the plant was more cost-effective..
-------
-23-
Alternative No. 1 - No Action
This alternative involves no remedial action and leaves the site in its
existing state. A detailed hydrogeologic .investigation has confirmed the
presence of the contaminants VCM, EDC and TCE in the Columbia aquifer. The
aquifer serves as a drinking water supply to residents in the surrounding
area. Without groundwater controls, the contaminant plume will continue to
migrate in the northerly and southerly directions and will impact the residential
wells located downgradient. At the present, an estimated 25-30 residences
are located downgradient of the northerly and southerly paths of plume. The
migration of the contaminated plume represents a significant potential threat to
those citizens who are currently using the aquifer through direct exposure via
ingestion, inhalation and dermal contact.
The contaminated groundwater, if not recovered, will eventually discharge
into Red Lion Creek and Dragon Run. Additionally, is has been calculated that
EDC and VCM will be present in the groundwater at the discharge point in
concentrations greater than allowed by EPA Water Quality Criteria. Aquatic
and terrestrial biota may be impacted due to the presence of these contaminants
in the surface waters. Also, there is a potential threat to the population
utilizing these creeks for recreational or drinking purposes.
A no action alternative would provide no additional protection to the public
health or environment and the contamination of the groundwater and surface
waters would be expected to continue.
Alternative No. 2 - Downgradient Pumping to Collect Groundwater at the
Edge of the Existing Plume in the Buried Valley
This alternative involves installation of two lines of pumping wells, one
across the buried" valley at the northern edge of the plume and one across the
valley at the southern edge in order to collect the EDC, VCM and TCE contaminated
groundwater. (see Fig. 8)
EDC and VCM have been detected in monitoring well OW-5 (at 1,6000 and 310
parts per billion(ppb), respectively during August 1984 sampling). Well OW-32,
300 feet downgradient of OW-5, has not shown these compounds. Likewise, OW-22,
further downgradient, has never shown EDC or VCM. Therefore, the edge of the
plume is somewhere between OW-5 and OW-32.
Through August 1984, OW-3 had consistently shown traces of EDC
(less than 5ppb) but no VCM. In the December 1984 sampling, EDC and VCM were
detected. The northern line would consist of six wells each pumping 1015gpm.
OW-5 could be incorporated into this line of pumping wells. Any EDC/VCM/TCE
that may have migrated past OW-5 towards OW-2, will be drawn back toward and
.withdrawn by the northern line of pumping wells.
Six piezometers would be installed both upgradient and downgradient of
this line of wells. Water levels will be taken on a quarterly basis for the
duration ol the pumping to demonstrate that the system is effectively inter-
cepting all EDC, VCM, and TCE contamination in the identified plume area.
-------
The southern line of punning wells would trend northeast from Route 13
through OW-16. Through the action of these wells, all EDC, VCM and TCE flowing
to the south from the existing plume area can be intercepted. OW-30 showed
EDC (1,100 ppb) and VCM (50 ppb) for the first time during August 1984 sampling.
EDC/VCM/TCE in the vicinity of OW-30 will be drawn back .to the proposed line
of pumping wells. Six piezometers would be installed both upgradient and
downgradient of this line of wells, so that accurate water level data can be
collected. In this way it can be shown that all EDC/VCM/TCE from the identified
plume is being intercepted. Similar to the northern line, six pumping wells
would be required. Existing monitoring well OW-16 could be incorporated as
one of the pumping wells. Each pumping well in the northern and southern
lines would consist of six-inch diameter casing and ten feet of screen. Well
depths would range from 50 to 70 feet below the surface and each well would be
pulped at 10 to 15 gpm. The piezometers would consist of two-inch diameter
casing and screen and be screened at the same hydrogeologic setting as the
pumping wells. The lower portion of the Columbia aquifer has been shown to be
contaminated with EDC, VCM and TCE in the February 4, 1983, hydrogeology report.
These two lines of wells are designed to intercept and collect water from
the deeper portion of the aquifer that contains the EDC, VCM and TCE. The
exact number, location and pumping rates will be adjusted, if necessary, during
the final design phase of the remedial program to ensure complete capture of
the groundwater plume.
The recovery wells will be operated until the concentrations of VCM, EDC
and TCE in these wells reach 1 ppb, 0.94 ppb, and 2.7 ppb respectively for. two
consecutive sample analysis.
This alternative also includes replacement of the Getty Gas Station,
Stapleford Chevrolet and Telephone Company Relay station wells. A pilot hole
to 300 feet below land surface will be drilled and sediment cores will be
logged at regular intervals. A suitable water-bearing unit in either the
Magothy or Upper Potomac aquifers will then be selected as an alternative source
of water to these businesses.
Two monitoring wells will be installed at the southern edge of the plume to
monitor the movement of the contaminated plume. These wells will be sampled
semi-annually for VCM, EDC and TCE. Downgradient residents using well water
will be provided a permanent potable water supply, if EPA/DNREC determine at
any time, that contamination of the residential wells is imminent.
This alternative provides for plume control, groundwater remediation and
alternate water supplies.
-------
-25-
Alternative No. 3 - Downgradient and Within Plume Pumpage to Collect All
Contaminated Groundvater
This alternative involves the two lines of pumping wells described in
Alternative No. 2. In addition, a third line of wells would be set up within
the existing plume area. Use of the three lines of wells would speed up the
clean-up time, because more water would be collected, (see Fig. 8)
The third line of wells would consist of eight new pumping wells spaced
approximately 125 feet apart. The line would extend from the vicinity of
existing monitoring well OW-17 towards monitoring Well OW-1. Both four-inch
diameter monitoring Wells OW-17 and OW-1 could be used as part of this system.
The total of ten wells in this line would be pumped at 10 gpra each which would
adds an extra lOOgpm of pumpage to this alternative.
The third line of new wells within the existing plume area would effectively
intercept contaminated groundwater flowing from the identified sources. The
two lines in the buried valley would effectively intercept groundwater containing
EDC, VCM and TCE from the edge of the existing plume.
Each well in the third line of wells would consist of a six-inch diameter
casing with five feet of screen. These wells would be shallower than their
buried valley equivalents due to the higher elevation of the underlying aquitard.
It is estimated that these wells will be 50 feet deep. The exact number,
location and pumping rates will be adjusted, if necessary, during the final
design phase of the remedial program to ensure complete capture of the groundwater
plume.
It is recommended that ten 2-inch diameter piezometers be installed both
upgradient and downgradient of this third line to effectively measure the
extent of the radius of influence of this line to the west.
This system of three lines of pumping wells has one major advantage. One
volume (from the sources to the intercept wells) of the identified plume can
be removed in half the time that an equal volume of contaminated water would
be captured through implementation of Alternative I. The third line is located
downgradient of a lower permeability area where groundwater flow rates are
significantly slower than in the buried valley. Thus the cleanup of the
plume could be completed in less time. A potential disadvantage of this expanded
system is that the larger volume of water removed (280 gpm total) may limit
choices for disposition of water.
The recovery wells would be shut off when the concentrations of VCM,
EDC and TCE in the recovery wells reach 1 ppb, 0.04 ppb, and 2.7 ppb respectively
for two consecutive sample analyses.
This alternative includes replacement of the Getty Gas Station,
Stapleford Chevrolet and Telephone Company Relay Station Wells as described
-------
-26-
in Alternative No. 2.
^..
Two monitoring wells will be installed at the southern edge of the plume
to monitor movement of the contaminated plume. These wells will be sampled
semi-annually for VCM, EDC and TCE. The three lines of wells are designed to
intercept and collect water from the deeper portion of the aquifer that contains
the EDC, VCM and TCE. The exact number, location and pumping rates of these
wells will be adjusted, if necessary, during the final design phase of the
remedial program to ensure complete capture of the groundwater plume.
Alternative No. 4 - Plume Management
The fourth alternative is plume management. Plume management involves
implementation of a monitoring network to track the movement of the plume to
re-Ceptors. Under natural conditions, groundwater in the buried valley flows
either to the north or south to discharge into Red Lion Creek or Dragon Run
respectively (Figure 8). The rate of movement of the existing plume to the north
appears to be slower than movement to the south because sediments to the north
are significantly less permeable than those to the south (based on pump test
results). (see Fig. 9)
A number of items must be addressed in implementing any plume management
alternative. These are:
1. The projected path(s) of the plume must be verified.
2. The identified sources must be abated so the plume is allowed to
flush itself naturally.
3. An adequate monitoring system must be set up over the lifetime of the
existing plume.
4. Domestic wells in the path of the plume, particularly at the same
horizon in the aquifer, must be identified so alternative supplies of
water can be provided, if necessary.
5. The future use of lands above the plume must be determined so as to
prevent supply wells from inadvertently being installed into the
plume.
6. The effects (if any) of plume discharge into receptors must be determined,
This alternative allows continuing contamination of the aquifer and demands
extensive monitoring and institutional controls. EPA has determined that this
does not meet all public health and environmental standards as defined by CERCLA.
Alternative No. 5 - Delaware DNREC - Remedial Alternative
w
The State of Delaware proposed an additional alternative to the four
described above. In the State's proposal an industrial water supply wellfield
would be developed along either the east or west side of Route 13. The resulting
water supply could be used by Stauffer/Formosa for one or more purposes in
ongoing operations. The State assumed that the groundwater would have a maximum
-------
-27-
concentjation of EDC and/or VCM of 1000 ppb. The actual detections provide an
average concentration of 7,000 ppb EDC, 400 ppb VCM, and lOppb TCE for groundwater
collected by the recovery wells. Groundwater flow paths were projected from
the identified sources to each of the potential recovery wells. The highest
levels of VCM, EDC and TCE recorded at each monitoring well within a flow path
were averaged. Each of these numbers was then averaged. These calculations
take into account 25% dilution by uncontaminated water withdrawn along with
the plume water.
Such a wellfield would accomplish the major goals described in the State's
proposal. The major goals of the State's proposed alternative are to provide
water from a wellfield while ensuring protection of the deeper aquifer system.
An ancillary benefit is the removal of water containing EDC, VCM and TCE.
The State also proposed to construct a waterline for the residences along
the' discharge path as part of the cleanup. However, Malcolm Pirnie determined
that this alternative would not effectively remove all .EDC, VCM and TCE from
the identified plume. In particular, the DNREC's alternative would be unable
to capture all of the plume unless wells are installed along the entire width
of the plume, parallel to the buried valley and in poor waterbearing areas.
CONSISTENCY WITH OTHER ENVIRONMENTAL LAWS
Alternatives were examined in light of applicable Federal, State and local
environmental program requirements and in light of all CERCLA requirements.
The remedial actions proposed will be coordinated with the State to insure
that the water and air quality will meet all applicable standards.
•
RECOMMENDED ALTERNATIVE (see Table 6)
Section 300.68(j) of the National Contingency Plan (NCP) states that the
appropriate extent of remedy shall be determined by the lead agency's selection
of a remedial alternative which the agency determines is cost-effective (i.e.,
the lowest cost alternative that is technically feasible and reliable and
which effectively mitigates and minimizes damage to and provides adequate
protection of public health, welfare and the environment). In selecting a
remedial alternative, EPA must consider all environmental laws that are applicable
Based on the evaluation of the cost effectiveness of each proposed alternative,
,the analysis contained above and the comments received from the public and
information from the Delaware Department of Natural Resources and Environmental
Control (DNREC), we recommend the following remedial alternative for the
six-identified sources and the groundwater:
1. Off-grade Batch Pits - Excavate and Remove PVC sludges and contaminated
soils to the levels to be determined at the design stage; install a double
synthetic (or RCRA conforming equivalent) liner, install monitoring wells and
perform quarterly sample analysis for TCE, EDC and VCM. The excavated material
-------
-28-
will be directly processed and recovered (estimated by the companies to be 80-85%)
as a saleable finished product to the maximum extent possible. Non-recoverable
material will be disposed of off-site at an approved RCRA facility. Since
this alternative involves recovery of contaminated sludges, the risk of groundwater
contamination from these sludges will be eliminated.
The double liner will provide the most protection against leakage of the
contaminants.
2. RV Pond - The same remedy as described above for the off-grade batch
pits.
3. Unlined Ditches - Excavate and remove PVC sludge, intall a single
synthetic liner. The excavated material will be disposed of off-site at an
approved RCRA facility. Excavation and removal of PVC sludges will eliminate
the risk of groundwater contamination from these sludges. The single synthetic
liner will provide protection against leakage of the contaminants into the
groundwater.
4. Aerated Lagoons - Excavate and remove PVC sludge, clean and repair
lagoons, install a double synthetic (or RCRA conforming equivalent) liner and
monitoring wells. The excavated material will be recovered (estimated by the
companies to be 80-85%) and the non-recoverable material will be disposed of
off-site at an approved RCRA facility. The recovery of contaminated sludges
will eliminate the risk of groundwater contamination from these sludges.
Cleaning and repair of the concrete liner and installation of a double liner
on top will provide the most protection against leakage of the contaminants
into the groundwater.
5. Closed Buried Sludge Pits - Place a drainage layer on top of the
original liner. Then cover with a second synthetic liner (or comparable sub-
stitute in compliance with the requirements of RCRA), topsoil and revegetate.
The double synthetic cover will provide protection against stormwater percolation
and groundwater contamination.
6. Former PVC Storage Area - Cover and cap the entire area with a double
synthetic (or comparable substitute in compliance with the requirements of RCRA)
cap and revegetate. The cap will protect the groundwater from the leaching of
.the contaminants.
7. Groundwater - Install one line of six groundwater recovery wells at
the northern edge of the plume, and another six wells at the southern edge.
Reuse the collected groundwater in Formosa's plant and during the low water
demand at the plant dispose of the groundwater at the wastewater treatment
plant. Install two monitoring wells at the southern edge of the plume. The
. recommended-recovery system will collect the contaminants and prevent the plume
from'migrating further.
-------
-29-
OPERATION AND MAINTENANCE
Periodic inspection and maintenance will be required for all the liners
and the caps to assure that they are functioning properly. Periodic inspection
and maintenance will also be necessary during operation of the recovery system.
The operator of the recovery system should have experience with a municipal
wellfield or contaminated groundwater pumping system or have demonstrated
experience in a groundwater related field.
Proper maintenance of the groundwater treatment system will be required to
ensure compliance with the NPDES and the Clean Air Act.
The groundwater monitoring program for the sources and recovery well
system will commence after installation of the liners, caps and the recovery
wells (est. 12 months). Periodic analysis will evaluate the effectiveness of
the selected remedy.
EVALUATION OF ALTERNATIVES NOT SELECTED
OFF-GRADE BATCH PITS AND RV POND
The alternative that involved installation of a clay liner was not chosen,
because it may not be completely reliable due to the potential for cracking.
The alternative that involved installation of a single synthetic liner
was not chosen, because it was less reliable than the double synthetic liner.
If the wastewater penetrates the single synthetic liner it would cause ground-
water contamination. Overall, both the clay and single synthetic liners are
less reliable and environmentally effective than the double synthetic liner.
The double liner is more reliable in preventing leakage than the clay or
single liner over time and represents a small increase in cost ($500,000 vs.
$460,000 and $450,000 for off-grade batch pits and $250,000 vs. $232,000 and
$227,000 for RV Pond).
Both clay and single synthetic liners do not meet all public
health and environmental standards as defined by CERCLA.
UNLINED DITCHES
The single synthetic liner was chosen over the concrete liner alternative.
The concrete liner was less environmentally effective than synthetic liner due
to the possibility of cracking. The concrete liner was also more expensive than
the synthetic liner (5115,000 vs. $65,000).
The single synthetic liner meets all public health and environmental standards
as defined by CERCLA.
-------
AERAtEI)^ LAGOONS
The alternative that involved cleaning and repair of the existing concrete
liner was not chosen, because it would still be sensitive to cracking and
erosion during its operation. If the cracking occurs, it could cause further
groundwater contamination.
The alternative that considered installation of a single synthetic liner
was not chosen because it was less reliable and environmentally less affective
than the double synthetic liner.
The double synthetic liner is more reliable in preventing leakage than
single synthetic liner or concrete liner over time and represents a small
increase in cost ($425,000 vs. $343,000 and $278,000).
Both the concrete and single synthetic liners do not meet all public
health and environmental standards as defined by CERCLA.
CLOSED BURIED SLUDGE PITS
The alternative that involved keeping the existing cap was not chosen
because it was less environmentally effective than the double synthetic cap.
It did not meet all public health and environmental standards as defined by
CERCLA.
Total excavation and removal of contaminated sludges was rejected, because
it offered comparable protection to the double synthetic cap, but was considerably
more expensive ($5,946,000 vs. $155,000).
FORMER PVC RESIN STORAGE AREA
The alternative that involved excavation and removal of highest contamination
areas was not chosen, because the concentrations of contaminants left on-site
would cause- further degradation of the groundwater through leaching of the
contaminants.
The alternative that involved capping the highest contamination areas
with synthetic liner was not chosen because the uncovered areas would also
cause further degradation of the groundwater.
Capping the entire area with single synthetic liner was rejected because
it was less environmentally effective than the double synthetic cap.
The double cap is more reliable than the single cap over time and represents
a small increase in cost ($295,000 vs. $180,000).
t.
Furthermore, all three of the alternatives described above do not meet
-------
-31-
all public-.health and environmental standards as defined by CERCLA.
GROUNDWATER
Alternative No. 3 (i.e., 3 lines of recovery wells) was rejected, because
the only advantage it had over Alternative No. 2 (i.e., 2 lines of wells) was
that it would take a shorter time to clean-up the groundwater. However, it was
more expensive while offering the same level of protection as Alternative No.
2 ($839,000 vs. $599,000).
Both the plume management alternative and Alternative No. 5 were more
expensive and offered less protection than Alternative No. 2 ($1,720,000 and
$2,285,000 vs. $599,000).
Plume management was also rejected because it allows for contamination
of the aquifer and natural "finishing" of the contaminants rather than "cleanup"
of the groundwater.
Alternative No. 5 was rejected because it was determined that it would
not collect all of the contamination in the groundwater.
-------
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-------
120 —
ISO
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-------
LEGEND
OBSERVATION WELL
TEST BORING
• DOMESTIC WELLS
0 GETTY WELL
A»—
-------
.TABLE 1
ANALYSIS OF DELAWARE CITY OBSERVATION WELLS FOR
VCM, EDC, AND TCE
SAMPLES COLLECTED AUGUST 21 - AUGUST 23, 1984
SAMPLES ANALYZED AUGUST 24 - AUGUST 31, 1984
Sample
OW-3
OW-5
OW-10
OW-11
OW-13
OW-14
OW-16
OW-17
OW-17A2)
ow-ia
OW-19
OW-22
OW-28
(2)
(2)
(2)
Concentration (ppb)
VCM
ND(3)
310
Det
250
EDC
Det(4)
1,600
230
40
TCE
ND
13
4
4
Other O
ND
ND
One at
Three a
OW-29
OW-30
OW-31
.OW-32* '
OW-3 3
Lower Limit of
Detection
O.A spikes at 10 ppb
(Average percentage
recovery from duplicate
analysis)
ND
ND
ND
210
ND
ND
ND
ND
ND
ND
50
ND
ND
ND
1
105%
ND
ND
ND
3,400
Det
ND
ND
ND
ND
ND
1,100
ND
ND
ND
1
4
9
Det
15
Det
ND
ND
ND
15
.ND
Det
7
ND
ND
1
93%
94%
50, and 25 ppb
ND
ND
ND
One at 3,400 ppb
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
LO
Notes:
1.
2.
3.
4.
Modified version of EPA Method 624 (Purge and trap gas
ch.omatography with flame ionization detection).
Saaple split with EPA's contractor, NUS.
Nil - Not detected.
Det - Detected below the lower limit of cjuantitation, 3 ppb.
14
-------
_TABLE Z
ANALYSIS OF DELAWARE CITY OBSERVATION WELLS FOR
VCM, EDC AND TCE U
SAMPLES COLLECTED DECEMBER 19 - DECEMBER 20, 1984
SAMPLES ANALYZED DECEMBER 27- DECEMBER 31, 1984
Concentration (ppb)
Sample
OW-3
^7-3 (duplicate)
OW-5
OW-11 (Top)
(Middle)
(Bottom)
OW-12
CW-15
OW-16
OW-20
OW-21
OW-30
OW-31
OW-3 2
Detection Limit
Q.A. Spikes at 10 ppb and 100 ppb
(Average % Recovery)
VCM
200
210
1,500
2,600
2,600
2,500
1,400
6°(2)
no1 '
ND
ND
100
ND
ND
1
115%
EDC
2,000
2,100
'14,000
31
36
31
27,000
2S,ooo(3,
ND
ND
2,600
ND
ND
1
106%
TCS
5.7
5.9
21
22
22
21
25
14
Det
ND
8.3
4.7
4.1
ND
1
115%
Notes:
1. Modified version of EPA Method 624 (Purge and trap gas
chromatography with flame ionization detection).
2. ND - Not Detected.
3. Det - Detected below the lower limit of quantitation, 3 ppb.
15
-------
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Location of Test Pft
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LOCATIONS OF
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4
FIG. 5
-------
DELAWARE CITY SOIL ANALYSIS
SAMPLES COLLECTED 10/23/84
SAMPLES ANALYZED 10/29/84 - 11/02/84
Depth
( inches )
12
54
36
36
84
12
24
12
24
12
12
30
52
42
32
16
74
53
10
32
7
49
4
48
12
36
Concentration (ppm)
Description
/ •
Soil and white powder
Blackish residue
Soil and white powder
Brown virgin soil
Brown virgin soil
Soil and white powder
Brown virgin soil
Soil and white powder
Brown virgin soil
Brown soil
Soil and white powder
Brown virgin soil
Brown virgin soil
Fine white powder
White slimy clay
White powder
Brown virgin soil
Red soil, strong odor
Soil and white powder
Brown virgin soil
Soil and white powder
Red soil/sand
White powder
Red soil/sand
Red soil
Red soil
VCM
-J »ro(3)
Det
ND
ND
ND
ND
. ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND.
ND:
ND
ND
ND
' KD
ND
ND
ND
EDC
. ND
' 27
14
ND
ND
18
ND
22
ND
ND
14
ND
ND
120
63
24
ND
ND
ND
ND
ND
ND
. D_et
ND
ND
ND
TCE
ND
Det
Det
ND
ND
20
ND
ND
210
ND
Det
Det
ND
150
Det
. ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Sample
No.
1
2
TP-10 1
TP-10 2
TP-10 3
TP-11 1
TP-11 2
./
TP-12 1
TP-12 2
TP-12 3
TP-13 1
TP-13 2
TP-13 3
TP-14 1
TP-14 2
TP-14 3
TP-14 4
TP-15 1 '
TP-15 2
TP-15 3
•TP-16 1
TP-16 2
TP-17 1
TP-17 2
TP-18 1
"TP-18 2
Notes: ,
1. Modified version of EPA Method 624 (Dispersion of soil in
tetraglyme followed by purge and trap gas chromatography with
flame ionization detection).
2. .White powder and white slimy clay have been identified as PVC
resin. As shown in Appendix C, this material is typically present
as a thin layer approximately 6 to 12 inches thick within the top
2 feet of the surface.
3. ND indicates less than 4 ppm (detection limit).
4. .Det indicates less than 12 ppm (lower limit of quantitation).
23
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TABLE
DELAWARE CITY; SOIL ANALYSIS
SAMPLES COLLECTED 11/29/84
SAMPLES ANALYZED 12/17/84 - 12/26/84
Test
Pit No.
TP-19
TP-19
TP-19
TP-19
TP-20
TB-20
TP-20
TP-20
TP-21
TP-21
TP-21
TP-21
TP-22
TP-22
TP-22
TP-22
Sample
No.
1
2
3
4
-x^_
1
2
3
4
1
2
3
4
1
2
3
4
Depth
(inches) Description
18
Brown virgin soil
48
48
36
Brown soil with
traces of white
soil
Brown soil, no
visible powder
Brown virgin soil
Concentration (ppm)
VCM
ND
ND
ND
ND
ND(2)
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
£DC
ND
ND
ND
ND
ND
ND
Det
ND
ND
ND
ND
ND
ND
ND
ND
ND
TCS
ND
ND
ND
ND
ND
.. ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Notes:
2.
3.
Modified version of EPA Method 624 (Disperson of soil in
tetraglyme followed by purge and trap gas chromatography with
flame ionization detection).
ND indicates less than 2 ppm (detection limit)
Dec indicates less than 6 ppm (lower limit of quantitation)
24
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|'-0" CLAY
CO
>
r
•n
O
> •
r r
h
O OH
r- * »
i :J
C9 * A
? h
CA 2
z 5
LINER
6EOTEXTILE
l'-0" SAND/GRAVEL
LEAK DETECTION
-------
•n
0
LINER
ui
SYNTHETIC LINED DITCH
(TYPICAL)
8
df
- "
H2 -4 R «
•"» • — •«
O
>
cich
z z : :
ni m • «
o D ? °
S °
H
O
X
SITf
ITT STUDY
TCH
CONCRETE LINED DITCH
(TYPICAL)
COVER
— GEOTEXTILE
GRATING
-------
>
•fHtOIAL
I *«0 It l^« •••«•!
lOfMTtrtCP »LJi«B
FIG. 3
-------
LEGEND
> — EXISTING
WATER LINK
DOMESTIC
SUPPLY WELL
EXISTING
MONITORING WELL
PROJECTED
' PATH OP PLUME
•- EXISTING PLUME
(8/84 DATA)
PROPOSED
MONITORING WELL
EXPECTED
GROUNOWATER
DISCHARGE LOCATIONS
112
OCLAWANI CITY PVC SITt
MIUIOIAk ACTION 'LASIIIUTY STUOT
ALTERNATIVE Hi
PLUME MANAGEMENT
CIR
-------
Tnhlo r>
DELAWARE CITY PVC SITE
Source Alternative
Area Description
j Off-grade A) Excavate, remove sludges,
Pits Batch provide double synthetic
liner
B) Excavate, remove sludges,
provide single synthetic
liner
C) Excavate, remove sludges
i
>\ RV Pond A) Excavate, remove sludges,
provide double synthetic
liner
B) Excavate, remove sludges,
provide single synthetic
liner
C) Excavate, remove sludges,
provide clay liner
l\ Unlined. A) Excavate PVC sludge, pro-
Ditches vide synthetic liner
B) Excavate PVC sludge, pro-
vide concrete trench
C) Install concrete trench
(no contamination removed)
Remedial Action
Present Worth Costs
(Recovery of the
sludge and dis-
posal at RCRA
facility) (I)
$ 500,000
450,000*
460,000*
250,000
227,000*
232,000*
87,000
Alternatives
Present Worth Costs Present Worth Costs
(Disposal at municl- (Disposal at RCRA
pal landfill) (II) landfill) (III)
$ 455,000 $1,440,000
405,000 1,310,000
415,000 1,320,000
208,000 578,000
185,000 570,000
190,000 575,000
45,000 65,000
90,000 115,000
87,000 87,000
| ..
* Afl r":. .nfnd hv KPA
-------
DF.L
Table 5 (rout i nno
-------
Tnhlf *j (ronl iniii-il)
DELAWARE CITY I'VC S1TK
Remedial Action Alternative
Source
Area
Alternative
Description
C) Cap (double synthetic mem-
brane) entire area, cover,
revegetate entire area
(no contamination removed)
D) Excavate, remove contami-
nated materials, regrade
cover, revegetate entire
area
Present Worth Costs
(Recovery of the
sludge and dis-
posal at RCRA
facility) (I)
295,000
Present Worth Costs
(Disposal at munici-
pal landfill) (II)
295,000
Present Worth Costs
(Disposal at RCRA
landfill) (III)
295,000
65,000
143,000
Groundwater A)
B)
C)
D)
Description
Downgradient pumpage to
collect ground water at the
edge of the existing plume
in the buried Valley
(includes monitoring)
Downgradient and within
plume pumpage to collect
all contaminated ground-
water (includes monitor-
ing)
Plume management
Delaware DNREC Remedial
Alternative
Present Worth Costs
$ 590,000
830,000
1,720,000
2,285,000
* As est
>d by EPA
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Table 6
DELAWARE CITY PVC SITE
1)
2)
3)
4)
5)
6)
7)
. -• RECOMMENDED
Source/Alternative
Off-grade Batch Pits
(Alternative 01-A-I)
RV Pond
(Alternative //2-A-I)
Unlined Ditches
(Alternative 03-A-III)
Aerated Lagoons
(Alternative //4-C-I)
Closed Buried Sludge Pits
(Alternative #5-C-I)
Former PVC Storage Area
(Alternative #6-C-I)
Groundwater
(Alternative #7-A)
REMEDIAL ALTERNATIVES
Capital
Cost($)* 0/M.($/Yr.)*
$450,000 $5,300
$237,000 $1,400
S 55,000 $1,100
$407,000 $2,000
$139,000 $1,700
$281,000 . $1,500
$335,000 $30,000
Present
Worth(S)
$500,000
$250,000
S 65,000
$425, Of*
$155,00.
$295,000
$590,000
TOTAL $1,904,000 $43,000 $2,280,000
*as estimated by EPA
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RESPONSIVENESS SUMMARY
DELAWARE CITY PVC SITE
NEW CASTLE COUNTY, DELAWARE
SEPTEMBER 1986
This community relations responsiveness summary is divided into
the following sections:
Section I: Overview - A discussion of EPA involvement at the site
and a description of the EPA's preferred remedial
action alternative.
Section II:
Summary of Public Ccnroents Received During the Public
Comment Period and Agency Responses - A summary of comments
categorized by topic and followed by EPA responses.
Section III: Remaining Concerns - A description of remaining community
concerns that EPA and the Delaware Department of Natural
Resources and Environmental Control should consider in
conducting the remedial design and remedial actions at the
site.
In addition to the above sections, a list of EPA community relations
activities conducted at the Delaware City PVC site is included as Attachment
A of this responsiveness summary.
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- 2'-
I. Overview
In 1983, the Delaware City PVC site was included on the National
Priorities List (NPL).
In May, 1984, EPA and the Delaware Department of Natural Resources and
Environmental Control (DNREC) entered into a Consent Order with
Stauffer and Formosa to perform a Feasibility Study (FS) for the site
and to implement the Approved Remedial Action. The FS evaluated 18
alternatives for remediating the six identified sources of contamination
and four alternatives for groundwater remediation.
Comrtunity interest and involvement during the time between the signing
•^ of the consent order and the opening of the conment period on the
preferred alternative were very limited.
The FS was released to the public for review and comment on July 27,
1986. This marked the opening of the comment period, which extended
until September 3, 1986. During the comment period, the EPA and the
DNREC recommended preferred remedial alternatives for the six
contamination sources as well as for groundwater remediation.
The alternatives are described in detail in Section 5.0 of the FS
Report. In summary, the EPA's and DNREC's recommended alternatives
for the six contamination sources and groundwater are as follows:
Description of the Selected Remedy;
1. Off-grade Batch Pits - Excavate and remove existing polyvinyl
chloride (P\*3) sludge and contaminated soils to the levels to be
determined at the design stage; install a double synthetic liner,
install monitoring "wells and perform quarterly sample analysis
for•trichloroethylene (TCE), 1,2, dichloroethane (EDC) and vinyl
chloride monomer (\£M), the contaminants of concern at the site.
The excavated material will be directly processed and recovered
as a saleable finished product to the maximum extent possible.
Non-recoverable material will be disposed of off-site at an
approved RCRA facility (est. 1 year).
2. Stormwater Reservoir (RV Pond) - The same remedy as described for
the above off-grade batch pits (est. 1 year).
3. Unlined Ditches - Excavate and remove P\C sludge, install a single
synthetic liner. The excavated material will be disposed of off-
site at an approved RCRA facility (est. 8 months).
4. Aerated Lagoons - Excavate and remove PVC sludge, clean and repair
lagoons as necessary, install a double synthetic liner, install
monitoring wells and perform quarterly sampling analysis for TCE,
EDC and VCM. The excavated material will be recovered to the
maximum extent possible and non-recoverable material will be
disposed of off-site at an approved RCRA facility (est 18 months).
-------
- 3'-
S.^Closed Buried Sludge Pits - Place a drainage layer on top of the
existing synthetic cap, and cover with a second synthetic cap
(or conparable substitute in compliance with the requirements of
RCRA) and topsoil and then revegetate (est. 1 year).
6. Former PVC Storage Area - Cover and cap the entire area with a
double synthetic cap (or comparable substitute in compliance with
the requirements of RCRA) and then revegetate (est. 6 months).
7. Groundwater - Install a line of six groundwater recovery wells at
the northern edge of the contaminant plume, and- another six wells
at the southern edge. Reuse the collected groundwater in Formosa's
plant operations. During periods of low water demand in the plant,
treat the groundwater in the existing waste water treatment plant.
Install two monitoring wells at the southern edge of the plume.
Provide an alternate water supply for existing contaminated wells.
8. Operation and maintenance (O&M) for the remedy will include as a
minimum, regular inspections and, as necessary, repairs to the
liners and caps. The groundwater recovery system will be routinely
monitored to assure that it is capturing the contaminated plume.
II. Summary of Public Comments Received During the Public Comment Period
and Agency Responses
Comments raised during the Delaware City P\C site public comment
period are summarized briefly below. The comments received during
the comment period, July 27 to September 3, 1986, are categorized by
relevant topics.
Remedial Alternative Preferences
1. One ccmmentor suggested that EPA and DNREC should consider an
alternative which would completely remove all of the contaminants
and dispose of them in a separate landfill or appropriate facility.
This same ccmmentor was concerned about the preferred alternative
leaving contaminants in place for future generations.
EPA Response - High cost and dwindling landfill space makes land-
filling of all contaminated material undesireable when similar
environmental results can be achieved by the techniques described.
However, EPA will consider total removal before signing the ROD.
2. A suggestion was made to create a common hazardous waste treatment
plant or disposal facility for all of the sites in the Delaware
City. area.
EPA Response - DNREC answered that at this time, private industry
has not indicated an interest in building such a plant.
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- 4 --
Technical Questions/Concerns Regarding Remedial Alternatives
1. One conmentor questioned whether there is an existing market for
refined PVt: sludge.
EPA Response - Formosa Plastics Corporation is currently recovering
PVC sludge from the lagoons on site, rather than disposing the
sludge as a waste.
2. Vtao has the final selection authority?
EPA Response - After considering all relevant comments, EPA will
decide which option is most environmentally sound and economically
feasible.
3. A question was raised regarding the time frame for cleanup at the
site.
EPA Response - Following the close of the public ccnment period, EPA
will prepare a formal Record of Decision (ROD) identifying the
recommended alternative. Subject to the conditions in the Consent
Order, the responsible parties will have 30 days to begin implemen-
tation of the preferred alternative.
4. One ccmmentor asked what would be left behind after the remedial
cleanup is completed.
EPA Response - Under the preferred alternative, all PVC sludge
will be excavated and removed from four of the six contamination
sources, including the off-grade batch pits, RV pond, unlined
ditches and aerated lagoons. The excavated material will be
directly processed and recovered as a saleable finished product
to the maximum extent possible. Non-recoverable material will be
disposed of off-site at an approved RCRA facility. Synthetic
liners will also be installed. The closed buried sludge pits will
be covered with a RCRA type cap, and revegetated. The former P^
storage area will be capped with a RCRA type cap and revegetated.
5. Another conmentor questioned what would be done to alleviate
groundwater contamination.
EPA Response - Under the preferred alternative, the remedial action
would include installing one line of six wells at the northern
edge of the contaninant plume, and another six wells at the southern
edge. The collected groundwater would be reused in Formosa's
plant operations. During periods of low water demand in the plant,
the groundwater would be treated in the existing waste water
treatment plant. TWo monitoring wells would be installed at the
southern edge of the plume and an alternate water supply would be
provided for existing contaminated wells.
-------
6. One. ccmmentor asked how much PVC sludge was estijTiated to be in
'the lagoons.
EPA Response - According to the Feasibility Study, there are
approximately 84 tons of PVC sludge contained in the lagoons on
site.
7. Formosa Plastics Company conmented that it was in agreement with
EPA's and DNREC's concept of excavation of sludges and engineering
controls to eliminate future contamination, however, it disagreed
with EPA's and DNREC's requirement for disposal of excavated
material as a hazardous waste.
EPA Response - It is EPA's policy that all CERCLA-designated
hazardous substances be disposed of at a facility in compliance
with all requirements of RCPA. In fact, the agency interprets
CERCLA as requiring their disposal at a RCRA facility.
8. Stauffer Chemical Company commented that it agreed with EPA's and
DNREC's preferred alternative for remediation of the groundwater,
however it disagreed with EPA's and DNREC's requirement that the
closed buried sludge pits and the former PVC storage areas be
capped with a double synthetic nenbrane cover because it is not
cost effective. In the alternative, Stauffer commented that
consideration should be given to the use of a soil member having
equivilent permeability characteristics as one of the two synthetic
membrane members proposed.
•
EPA Response - EPA believes that the double synthetic membrane cover
is far more environmentally effective and reliable than a single
synthetic cap. Given this additional protection and the fact that
EPA does not believe that the cost for this alternative far exceeds
the cost of a single synthetic cover, EPA believes that the preferred
alternative represents a cost-effective remedy for these sources.
EPA will consider the use of a soil membrane having equivalent
permeability characteristics as the synthetic membrane proposed.
Public Health/Environmental Concerns
1. A question was raised concerning how the EPA and the DNREC can
justify leaving carcinogenic materials at the site.
EPA Response - EPA explained that the major threat to the public
exists from migration of the groundwater plume toward receptors.
The recovery wells will interest and collect the contaminated
groundwater before it reaches the downgradient users. The RCRA
caps and liners proposed will prevent further contamination of
the groundwater by stopping leaching of these contaninants into
the groundwater.
-------
- 6 -
Other Issues
1. One corunentor asked if the Stauffer Chemical Company had commented
on the preferred remedial alternative.
EPA Response - Yes, the comments received fron the StaufEer Chemical
Company are described in this document.
2. A question was raised concerning the Consent Order - is there any
clause in the order that prevents Formosa from selling its land
holdings, which in turn may ccnprcmise the cap and recovery wells?
EPA Response - Deed restrictions would prevent this.
III. Remaining Concerns
Issues and concerns expressed during the comment period that the EPA
was unable to address during remedial planning activities include:
1. Concern was raised about the financial security of Formosa Plastics
Corporation and their ability to make assurances that the remedial
actions will be carried out to completion and repaired as necessary.
2. Concern remained over how much of the PVC sludge could be recoverable.
(It is estimated by Formosa to be 80-85%)
3. The liability of both ccnpanies (Formosa and Stauffer) was raised
as a point of concern. One ccmmentpr recommended that the companies
should post bonds to ensure their liability.
-------
Attachment A
Community Relations Activities Conducted
at tin«» Delaware City PVC Site
0 A press release announced that public conrnents would be accepted on
the administrative consent order, May 1984.
0 A press release announced the extension of the comment period on the
consent order, July 1984.
0 The completion of the Feasibility Study, its availability at local
repositories and the opening of the public comment period on the
proposed cleanup alternatives were announced in a press release,
July 1986.
0 A fact sheet identifying the preferred remedial alternatives was
prepared, August 1986.
0 An informal meeting was held on August 27, 1986 to answer questions
and accept comments on the proposed cleanup.
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