United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R03-93/166
June 1993
PB94-963910
&EPA Superfund
Record of Decision:
Occidental Chemical/
Firestone, PA
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50272-101
REPORT DOCUMENTATION 1. REPORT NO. 2
PAGE EPA/ROD/R03-93/166
4. Tide and Subtitle
SUPERFUND RECORD OF DECISION
Occidental Chemical/Firestone, PA
First Remedial Action
7. Authors)
9. Performing Organization Name and Address
12. Sponsoring Organization Name and Address
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
3. Radpionfe Accession No.
5. Report D«t»
06/30/93
&
10 Project Task/Work Ur* No.
11. CentractfC) or Orant(G) No.
«
(G)
13. Type of Report* Period Covered
800/800
•M.
15. Supplementary Notes
PB94-963910
1& Abatract (Limit: 200 words)
The 250-acre Occidental Chemical/Firestone site is an active polyvinyl chloride (PVC)
manufacturing facility located one-half mile southeast of the Borough of Pottstown,
Montgomery County, Pennsylvania. Land use in the area is mixed agricultural,
residential, and commercial, with some natural habitat and wetlands. The site is
surrounded by the Schuylkill River on its western, southern, and eastern sides and is
bordered by wooded and agricultural land to the northwest and northeast, respectively.
In addition, the eastern portion of the site is located within the 100-year floodplain
of the Schuylkill River. Several nearby communities use the Schuylkill River as a
source of drinking water; however, the nearest public intake is located approximately
3.5 miles downgradient of the site. The site consists of a closed 17-acre solid waste
landfill, "7 -acre active industrial waste landfill four inactive unlined earthen
lagoons, two active lined lagoons, and a TCE Handling Area. The 17-acre solid waste
landfill was operated from 1942 until its closure in 1985. The State issued two
permits to Firestone allowing continued operation of this landfill. The second permit,
which was issued in 1977, required continuous pumping of the onsite production wells to
act as a leachate collection system for the landfill . This requirement is still in
operation today and causes bedrock ground water to flow toward the center of the site;
(See Attached Page)
17. Decuman! Analysis a. Descriptors
Record of Decision - Occidental Chemical/Firestone, PA
First Remedial Action
Contaminated Media: soil, sediment, gw
Key Contaminants: VOCs (benzene, PCE, TCE, toluene, xylenes)
c COSATIFMoVGroup
ia A vmtabBity Statement 1ft Security Oaas(This Report) 21. MaotPag**
None 110
30. Security Oass (This Page) 22, Price
None
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EPA/ROD/R03-93/166
Occidental Chemical/Firestone, PA
Final Remedial Action
Abstract (Continued)
thereby, containing the contaminant plumes at the site and preventing offsite releases to
the adjacent river or ground water. The 7-acre active industrial landfill is operating
under a State permit issued in 1977. The four inactive, unlined earthen lagoons were used
for storage of PVC sludge until 1974, when the State ordered Firestone to stop using the
lagoons. Although these lagoons have received no waste since 1974, the PVC contents were
left in place. The two active lined lagoons currently hold PVC sludge. The PVC sludge
was not a listed hazardous substance until September 25, 1990; however, because of this
change in regulation, Occidental Chemical Corporation (OCC) is in the process of closing.
TCE was used in the manufacturing process from the late 1940s until 1987. The chemical was
transported to the site in railroad tank cars and was unloaded via pumping to an
above-ground holding tank, located in a bermed retention basin (the TCE Handling Area) .
Spills occurred in this area during the transfer of TCE from the tank cars to the holding
tank. PVC manufacturing began at the site in the late 1940s when Firestone Tire and
Rubber leased the site. Firestone purchased the site in 1950 and continued to manufacture
tires and PVC resins until 1980, when the site was purchased by the OCC, which currently
manufactures PVC at this site. Previous manufacturing activities conducted at this site
have resulted in the release of hazardous substances to the environment, and EPA studies
cited the presence of several VOCs in the ground water as the primary concern at this
site. As a result, OCC conducted a remedial investigation from 1990 to 1993 to
characterize the nature and extent of contamination at the site, which indicated that
exposure to contaminated ground water, from the bedrock aquifer, and to the contaminated
soil and sediment, from the earthen lagoons, presented unacceptable health risks to
potential future residents living onsite. This ROD addresses a final remedy for the
bedrock ground water contamination, and inactive earthen lagoons. A future ROD will
address the Sedimentation Pond and the drainage swale associated with the active
industrial landfill. The primary contaminants of concern affecting the soil, sediment,
and ground water are VOCs, including benzene, PCE, TCE, toluene, and xylenes.
The selected remedial action for this site includes constructing an access road to the
earthen lagoons; excavating the lagoon contents (PVC material, coal fine layers, and
contaminated soil) ; onsite drying and bagging of the PVC material for recycling;
implementing air pollution controls; sampling and analyzing the coal fines layer and
recycling residues to determine appropriate transportation and offsite disposal
requirements; sampling and analyzing the underlying soil to ensure removal of all lagoon
contents; backfilling the excavation to the original grade and revegetating the area;
sampling the Sedimentation Pond and drainage swale to define the extent of cleanup
required for contaminated sediment; mitigating any affected wetlands; sampling the
floodplain south of the landfill and the drainage swale to determine whether contaminants
migrated during flood events; collecting ground water using recovery wells, with onsite
treatment using air stripping and vapor phase carbon adsorption; discharging the treated
water either offsite to a POTW or to the Schuylkill River; monitoring the ground water
periodically; and implementing institutional controls, including deed restrictions. The
estimated present worth cost for this remedial action is $11,119,000, which includes an
annual O&M cost of $403,000 for years 0-3, and $340,000 for each of the following
estimated 97 years until completion of the ground water remediation.
PERFORMANCE STANDARDS OR GOALS:
Chemical-specific cleanup goals for the excavation of the earthen lagoons are not
provided; however excavation will be based on reducing contaminant levels to background
levels. Chemical-specific goals for ground water are also based on the State's requirement
for reducing contaminant levels to background concentrations, and include vinyl chloride
0.18 ug/1; ethylbenzene 0.06 ug/1; styrene 0.04 ug/1; TCE 0.12 ug/1 and trans-1,2-
dichloroethene 0.06 ug/1;. If EPA and the State determine that it is not technically
practicable to achieve these levels, the cleanup levels will be based on SDWA MCLs, and
include ethylbenzene 700 ug/1; styrene 100 ug/1; TCE 5 ug/1; trans-l,2-DCE 100 ug/1; and
vinyl chloride 2 ug/1.
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RECORD OF DECISION
OCCIDENTAL CHEMICAL CORPORATION SITE
DECLARATION
SITE NAME AND LOCATION
Occidental Chemical Corporation Site
Lower Pottsgrove Township, Montgomery County, Pennsylvania
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for
the Occidental Chemical Corporation Site, in Pottsgrove Township,
Montgomery County, Pennsylvania, which was chosen in accordance
with the requirements of the Comprehensive Environmental.
Response, Compensation, and Liability Act of 1980 (CERCLA), as
amended by the Superfund Amendments and Reauthorization Act of
1986 (SARA) and, to the extent practicable, the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP). This ;
decision document explains the factual and legal basis for
selecting the remedy for this Site.
- - -*••
The Commonwealth of Pennsylvania concurs with the selected
remedy. The information supporting this remedial action decision
is contained in the Administrative Record for this site.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this
Site, if not addressed by implementing the response action
selected in"this Record of Decision (ROD), may present an
imminent and substantial threat to public health, welfare, or the
environment.
DESCRIPTION OF THE SELECTED REMEDY
The Occidental Chemical Corporation Site includes an active
manufacturing facility approximately 250 acres in size. The
remedial action selected for the Site is a final remedy which
will address ground water contamination in the bedrock aquifer
and contamination at the earthen lagoons. The selected remedial
action includes the following components:
* Extraction and treatment of contaminated ground water
combined with air stripping and carbon vapor adsorption
throughout the entire plume of contamination and
• Long-term ground water monitoring throughout the
entire plume
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*' Excavation of PVC material, coal fines layer and
contaminated soil at the earthen lagoons
* Onsite Drying of PVC material and landfilling of the
coal fines layer at the earthen lagoons
* Restoration of the earthen lagoon area to original
grade .
• Additional sampling of sediment pond and drainage
swale
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the
environment, complies with Federal and State requirements that
are legally applicable or relevant and appropriate to the
remedial action, and is cost-effective. This remedy utilizes
permanent solutions and alternative treatment (or resource
recovery) technologies to the maximum extent practicable, and it -
satisfies the statutory preference for remedies that employ
treatment that reduce toxicity, mobility, or volume as their
principal element.
Because this remedy will result in hazardous substances remaining
at the Site, a review by EPA will be conducted within five years
after the initiation of the remedial action, and every five years
thereafter, as required by Section 121 (c) of CERCLA, 42 U.S.C.
§ 962 l(c), to ensure that the remedial action continues to
provide adequate protection of human health and the environment.
/
Stanley L. Laskowski Date
Acting Regional Administrator
Region III
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RECORD OF DECISION
OCCIDENTAL CHEMCIAL CORPORATION SUPERFUND SITE
DECISION SUMMARY
TABLE OF CONTENTS
Page
I. SITE NAME, LOCATION AND DESCRIPTION. 1
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES 1
A. Background 1
B. Inclusion on the NPL 7
C. Enforcement Activities 7
III. HIGHLIGHTS OF COMMUNITY PARTICIPATION 8
IV. SCOPE AND ROLE OF RESPONSE ACTION 8
V. SUMMARY OF SITE CHARACTERISTICS 9
A. Regional Setting, Soils, Geology 9,
1. Regional Setting .9
2. Soils. .......... 10
3. Geology 10
Bedrock Aquifer Geology . 10
Overburden Aquifer Geology. ....... .11
B. Nature and Extent of Contamination . 11
Data Evaluation ..... 11
Bedrock Ground Water 12
Overburden Ground Water 13
Schuylkill River. .16
Storm Water Sever Outfalls 19
Sediment Pond and Drainage Swale 22
Borrow Area Sediment. . 25
Plant Area Soils 25
Lined Lagoon Soils. 27
Earthen Lagoon Soils 30
VI. SUMMARY OF SITE RISKS 32
A. Human Health Risks 32
1. Identification of Contaminants of Concern. . . 32
2. Exposure Assessment Summary. .... 33
Potentially Exposed Human Populations 33
Chemical Exposure Pathways 56
\ Toxicity Assessment Summary 57
Risk Characterization Summary 59
Noncarcinogenic Risk 59
Carcinogenic Risk 60
B. Environmental Risks. ..... 60
C. Significant Sources of Uncertainty 62
D. Risk Assessment Conclusions 62
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VII. SUMMARY OF REMEDIAL ALTERNATIVES. 63
A. Remedial Alternatives for Bedrock Ground Water. . 64
B. Remedial Alternatives for Earthen Lagoons 72
VIII. SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES. . 75
A. Comparative Analysis of Alternatives
Bedrock Ground Water . 76
B. Comparative Analysis of Alternatives
for Earthen Lagoons. . 80
IX. THE SELECTED REMEDIES AND PERFORMANCE STANDARDS. ... 81
A. Selected Remedy for the Ground Water. 82<-
B. Selected Remedy for the Earthen Lagoons. . . . . . 87
C. Selected Remedy for the Drainage Swale and
Sedimentation Pond 90
X. STATUTORY DETERMINATIONS 90
- A. Protection of Human Health and the Environment. . .91
B. Compliance with ARARs 92
C. Cost-Effectiveness .94
D. Utilization of Permanent Solutions and
Alternative Treatment Technologies
to the Maximum Extent Practicable. . . . . . . . .95"
E. Preference for Treatment as a Principal Element. . 95
XI. EXPLANATION OF SIGNIFICANT CHANGES . .95
FIGURES AND TABLES
"Figure 1: Site Location. . . . 2
*Figure 2: Site Layout Map 4
*Figure 3: Bedrock Aquifer Potentiometric Surface ... 5
*Figure 4: Well Locations. .14
*Figure 5: Aerial Extent of TCE Plume 15
"Figure 6: Alluvial Aquifer Water Table .17
*Figure 7: Schuylkill River Sediment and Surface Water
Sampling Locations IS
*Figure 8: Stormwater Sewer and Sediment Sampling
Locations . . 20
*Figure 9: Sediment Pond and Drainage Swale
V Sampling Locations 23
*Figure 10: Borrow Area Sampling Locations 26
'Figure 11: Plant Area Soil Sampling Locations .... .28
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FIGURES AND TABLES (cont'd)
*Figure 12: Lined Lagoons Sampling Locations. ..... 29
'Figure 13: Earthen Lagoons Sampling Locations ..... 31
TABLES*
Table 1: Chemicals j€if Potential Concern (COPC)
Bedrock Aquifer ...... ...... . .34-35
Table 2: COPC - Overburden Aquifer. ... ...... 36
Table 3: COPC - Earthen Lagoon Sediment. ..... 37-38
Table 4: COPC - Lined Lagoon Soil ...... . . .39-40
Table 5: COPC - Borrow Area Soil/Sediment ..... 41-42
Table 6: COPC - Drainage Swale Sediment ...... 43-44
Table 7: COPC - Storm Drain Sediment ....... 45-46-
Table 8: COPC - UST Area #4 .......... ... 47
Table 9: COPC - Plant Area Soils. . ......... 48
Table 10: COPC - Drainage Swale and Storm Drain
Surface Water Runoff. .......... 49-50
Table 11: Toxicity Assessment Summary Table
Carcinogens. . ................ 51
Table 12: Toxicity Assessment Summary Table
Non-Carcinogens ..... .......... 52
Table 13: Inhalation Slope Factors .......... 53
Table 14: Derivation of Inhalation Reference Doses. . 54
Table 15: Exposure Assessment Summary Table ...... 55
Table 16: Summary of Human Risk ...... ...... 61
Table 17: Residual Risks at 25 Year Intervals ..... 79
Table 18: Contaminants of Concern in Ground Water. . .85
\
* Tables From Occidental RI/FS
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THE DECISION SUMMARY
I. SITE NAME, LOCATION, AND DESCRIPTION
The occidental Chemical Corporation (OCC) Site (Site) is 1/2 mile
southeast of the Borough of Pottstown, Montgomery County,
Pennsylvania. The Schuylkill River surrounds the site on three
sides forming the western, southern, and eastern boundaries. (See
Figure l). The Site contains an active polyvinyl chloride
manufacturing plant. It consists of approximately 250 acres,
which includes manufacturing, office, outdoor storage areas, and
inactive manufacturing/storage building space. Paved parking
areas, roadways, and open land comprise the remaining acreage.
The surrounding land use is agricultural, residential, areas of
natural habitat, and commercial. The land use across the
Schuylkill River is low density single family residential to the
southeast and a township park lies to the southwest. Small
commercial/industrial zones are also present across the river.
Wooded lands adjoin the northwestern boundary of the Site and
agricultural lands adjoin the northeastern portion at the Site.
Commercial office buildings, a hotel, and restaurant lie north of
the Site across Route 422. The Site is zoned for industrial land"
use in accordance with a Lower Pottsgrove Zoning Ordinance.
The location of the Site within a meander loop of the Schuylkill
River provides a unique hydro logic setting. Because the Site is
bounded by the river on three sides, surface drainage is
generally outward to the river. The eastern portion of the Site
is located within the 100 year f loodplain of the Schuylkill
River.
The Site consists of a closed seventeen acre solid waste
landfill, a seven acre active industrial waste landfill, four
inactive unlined earthen lagoons, two active lined lagoons, and
the TCE Handling Area.
II. SITE BISTORT AMD ENFORCEMENT ACTIVITIES
A. BACKGROUND
Prior to the second World War this Site was owned by Jacobs
Aircraft Engine Company (JAEC), which manufactured aircraft
engines. The Defense Plant Corporation (DPC) purchased the Site
from JAEC in 1942, JAEC continued to operate and manufacture
aircraft engines for DPC until late 1944. In 1945, DPC leased
the Site to Firestone Tire and Rubber (FTR), which subsequently
purchased t&e Site in 1950. FTR manufactured tires
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FIGURE i
OCCIDENTAL
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and polyvinyl chloride (PVC) resins at the Site. In 1980, FTR
sold the Site to Hooker Chemicals and Plastics Corporation, which
later became the Occidental Chemical Corporation (OCC) . OCC
continues to manufacture PVC at the Site today.
Past manufacturing operations at the Site have led to the release
of hazardous substances into the environment. The Site includes
the following: (See Figure 2)
A 17 acre solid waste landfill was in operation from
approximately 1942 through 1985. The landfill is approximately
1,700 feet long and ranges in width from 360 to 650 feet. Fly
ash, carbon black, tire plant wastes, wood pallets, paper,
cardboard, PVC sludge, and PVC scraps were reportedly disposed in
the landfill during its operation. In 1973, the Pennsylvania
Department of Environmental Resources (PADER) issued a permit to
FTR allowing then to continue to operate the solid waste
landfill. The landfill is located in the plant manufacturing
area of the Site. In 1977, FTR applied for a permit to expand
the landfill. One important technical feature required by PADER
when the permit was revised was to insist that the existing plant
production wells be pumped continuously to act as a contingent
leachate collection system. In this system, the process wells •>
continuously pump the bedrock groundwater to the surface for. use "
in the production process. This leachate control system, still in
operation today, controls the direction of the bedrock
groundwater flow towards the center of the site which acts to
contain the contaminant plumes preventing a release to the
adjacent river or groundwater. (See Figure 3)
In 1985, the landfill was closed and capped with a impermeable
synthetic liner system in accordance with a Closure Plan approved
by PADER. A monitoring well network was also installed to comply
with quarterly groundwater monitoring requirements for the closed
landfill.
In addition to the closed landfill, a 7 acre active
yasta landfilj is present at the Site. This landfill is
currently operated by OCC under a permit issued by PADER in 1977
(Permit No. 300001) . The active landfill is permitted and
operated as an industrial solid waste disposal facility. It is
located east of the 17 acre closed landfill. An active
sedimentation basin is located northeast of the active landfill
face. This landfill is approximately 1,000 feet long, 300 feet
wide, and rises approximately 30 feet above the floodplain. It
has a drainage swale which parallels the base of the landfill and
carries surface water runoff from the landfill to a sediment
settling basin. The active landfill and sediment settling basin'
are unlined. •
a unliood e^ffh^P Jacroonff are also present on the
Site. These lagoons were used for the storage of PVC sludge
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OCCIDENTAL CHEMICAL CORPORATION
SUPERFUND SITE LAYOUT MAP
APPROXIMATE BOUNDARY
OF FLOOD PLAIN
NONCONTACT
COOLINQ WATER
CLARIFIER
BORROW AREA
CONTAINING TCE
TREATMENT
BASINS
SEDIMENTATION
APPROXIMATE BOUNDARY
I | 17-ACRE
j | CLOSED LANDFILL
8 C H
FIGURE 2
Nui lu Sulu
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until 1974-when PADER ordered Firestone to discontinue the use of
these lagoons. The lagoons have not been formally decommissioned
but no further disposal of material in the earthen lagoons has
occurred since 1974.
Throughout the operation of the now inactive earthen lagoons,
sludge was first allowed to settle in the concrete holding basins
located at the rear of the wastewater treatment plant prior to
being sent to the lagoons. Unpolymerized PVC solids settled to
the bottom of the basins. The supernatant water was skimmed off
and sent directly to the Pottstown publicly owned treatment works
(POTW). When a basin neared capacity the PVC sludge was diverted
to the northern most lagoon (Lagoon #1). Sludge from the earthen
lagoons was periodically removed and placed in the closed
landfill when a lagoon reached capacity (approximately 15 feet
deep) ._ Firestone discontinued the use of the lagoons in 1974
when two lined lagoons were constructed to handle the waste. The
earthen lagoons and their PVC contents were left in place.
The two active lined lagoons currently hold polyvinyl chloride
(PVC) sludge which is recycled into the manufacturing process and
resold as low grade PVC product. The lagoons are lined with a
synthetic liner to prevent migration of chemicals into the i •*-.
subsurface. The liner is constructed of ethylene propylene diene*
monomer (EPDM). Until about 1937, PVC sludge was sent to these
lagoons in the same manner as the sludge sent to the earthen
lagoons. By September 1987, PVC sludge from the plant and that
stored in the lined lagoons was being reclaimed. The spent PVC
solids and liquid mixture is currently centrifuged to separate as
much solid material as possible for recycling. The liquid is
sent directly to the Pottstown POTW. The solids are mixed with
chemicals to slurry the mixture for transport to a spray dryer
for drying and subsequent packaging for resale.
Until 1990, the PVC sludge held in the lagoons was not a listed
hazardous substance. On September 25, 1990, EPA expanded its
list of hazardous waste to include some organic compounds. This
list included vinyl Chloride Monomer. Therefore, due to the
change in waste classification, the active lined lagoons became
subject to stricter regulatory requirements. Therefore, these
lagoons must either be upgraded or closed. OCC has submitted a
plan to close the lagoons. OCC is required to begin closure by
March 1994. The plan is currently under review and must be
approved by the U.S. EPA and PADER.
In addition to the above disposal areas, trichloroethylene (TCE)
was used in the manufacturing process from the late 1940's until
1987. TCE was brought to the Site in railroad tank cars and was
unloaded via pumping to a holding tank. The holding tank was
located above ground and situated in a bermed retention basin
where TCE was stored before its use in the PVC manufacturing
process. TCE was added to the plant process water used in the
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PVC reactors. The bulk of TCE combined with the PVC resin. The
spent reactor waste waters were then sent to an on-site
industrial pretreatment system before being pumped to the
Pottstown POTW. Over the years the TCE transfer process from
tank car to holding tank resulted in releases of TCE into the
soils, (i.e. spills)
From 1979 through 1983, Firestone and OCC sampled and analyzed
process water wells to determine if TCE had migrated from the
unloading area through the overburden soils and into the
groundwater via fractures in the underlying bedrock. Analytical
results revealed the presence of TCE in these wells at
concentrations which exceeded the maximum level allowed (5 ppb
TCE) by the Safe Drinking Water Act. The highest concentrations
were detected in the TCE handling area of the site where
concentrations ranged from 10 to 295 ppb. In early 1984,
approximately 898 tons of soil contaminated with TCE was removed
from the TCE handling area and disposed of off-site. The removal
of the contaminated soil reduced the movement of TCE from the
soil to the groundwater.
B. INCLUSION ON THE NATIONAL PRIORITIES LIST
In 1985, The United States Environmental Protection Agency,
Region III investigated the Site to characterize existing Site
conditions. Groundwater' and sediment samples were collected and
analyzed. The Site was evaluated by EPA in 1988 using the Hazard
Ranking System. The score was 45.91 and the OCC Site was placed
on the National Priorities List (NPL) of Superfund Sites. .EPA's
evaluation identified the primary concern at the Site as the
presence of several volatile organic coapounds (•VOCs*) in the
grounaVater. The EPA investigation identified TCE, trans-1,2-
dichloroethene (1,2-DCE), and vinyl chloride monomer (VCM) as
primary chemicals of concern.
C. HISTORY OF CERCLA ENFORCEMENT ACTIVITIES
In December of 1989, EPA negotiated and the Regional
Administrator signed an Administrative Order on Consent ("Consent
Order") with the active owner and operator, OCC (Docket No. III-
89-20-DC). Under the terms of the Consent Order, OCC conducted a
site-wide Remedial Investigation /Feasibility Study (RI/FS) for
the Site. The RI/FS, conducted between 1990 and 1993 has recently
been completed and approved by EPA.
Since December 1989, EPA has continued to investigate and gather
information on additional potentially responsible parties and has
sent general notice of potential liability to the following
parties: Bridgestone/Firestone Incorporated and General Services
Administration (GSA).
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III. HIGHLIGHTS OP COMMUNITY PARTICIPATION
The public participation requirements of Sections 113(k) (2) (B)
(i-v) and 117 of CERCLA have been met in this remedy selection
process. A newspaper advertisement was published in The Mercury.
Pottstown, PA, on Wednesday, April 20, 1993. It specified the
availability of the Proposed Remedial Action Plan (PRAP), the
duration of the public comment period, and the location of the
administrative record file which contains the Final RI/FS.
The public comment period began on April 20, 1993 and ended on
May 19, 1993. A public meeting was conducted on May 4, 1993, at
the Pottstown Senior Center. Approximately 25 people attended,
including Occidental Chemical employees, residents of the area,
and staff from EPA Region III and PADER.
IV. SCOPE AND ROLE OF RESPONSE ACTION
This final remedy selects a Remedial Action to address the
threats posed by the release of hazardous substances at the Site*.
The principal threat posed by the Site is the groundwater
contamination which resulted from the former TCE handling •*
operation. The concentrations of chemicals in the five
contaminant plumes exceed the Maximum Contaminant Levels (MCLs)
allowed by the Public Health Services Act, 42 U.S.C
SS 300 (f) to 300 (j-26). In addition, EPA plans to remediate the
inactive earthen lagoons. This remedial action will address the
bedrock groundhrater contamination and .the inactive earthen
lagoons.
Specific objectives for the site cleanup are to:
1. Restore groundwater in the bedrock aquifer to Federal and
State Applicable, Relevant, and Appropriate Requirements (ARARs),
including drinking water standards, and to a level that is
protective of human health and the environment.
2. Protect non-impacted groundwater and surface water for current
.and future use.
3. To prevent migration of chemicals from the earthen lagoons to
groundwater or to surface water, and to prevent direct contact
with lagoon material.
The active lined lagoons are being addressed by RCRA under its
closure regulations and the 7 acre active industrial solid waste
landfill is*currently operating in accordance with a permit
issued by PADER. These two areas will n&£ be addressed by this
action.
8
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V. SUMMARY -OF SITE CHARACTERISTICS
The Remedial Investigation/Feasibility Study (RI/FS) for the
Occidental Chemical Site was conducted by Occidental Chemical
Corporation between 1990 - 1993. The data obtained have been
used to evaluate chemical migration routes and risks to public
health or the environment. The primary focus of the RI/FS was to
determine the extent and fate of chemicals at the Site,
particularly TCE in the bedrock aquifer. The RI has also
involved site characterization sampling of the alluvial soils and
groundwater; Schuylkill River surface water and sediment, storm
water sewer outfalls surface water and sediment, surface water
and sediment from the sediment pond drainage swale, soil and
sediment from the earthen and lined lagoons, and background soil
samples. The ecological investigation included wetlands
delineation, plant community delineation, wildlife and habitat
surveys, and a receptor evaluation.
A. REGIONAL SETTING. SOILS. GEOLOGY .
1. Regional Setting 7
The Site lies within the Triassic Lowland Section of the Piedmont
Upland Physiographic Province. The Triassic Lowlands are
characterized by gently rolling hills formed by the erosion of
sandstone and shale. These hills have a topographic relief of
approximately 100 to 200 feet and gently slope to low lying
floodplain areas along the Schuylkill River which are at an
elevation of approximately 120 feet above mean sea level along
the Site boundary. The Site is located within the meander loop
of the Schuylkill River. Several communities utilize the river
for public water supplies. The nearest downstream public
withdrawal is owned by the Citizens Utilities Home Water Company
which serves sections of East Pikeland and East Vincent in
Chester County and the' Borough of Spring City in Montgomery
County. Citizen Utilities is allocated 5 million gallons per day
from the river and the intake for water supply is located .
approximately 3.5 miles downstream of the Site.
The results of an inventory of existing wells within a 2-mile
radius identified 26 veils. None of these wells are within 1/2
mile, 22 of the wells are residential and are at a distance of
1/2 to l mile of the Site. The other 4 wells are non-residential
wells located 1 to 2 miles from the Site. None of the wells
identified {.n the survey have been affected by the Site. The
plant production well network maintains a radially inward
gradient to the center of the Site which prevents off-site
migration of contaminants.
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2. Soils
The surface soils beneath the developed portion of the Site have
been substantially altered by construction activity since the
early 1940's. Both cut and fill activities have occurred in the
active plant area; therefore characterization of soil depths and
nature of the materials is difficult.
The Soil Conservation Service identified two types of "Made Land"
at the Site and one naturally occurring soil, the Rowland silt
loan. This soil type is found in the floodplain of the
Schuylkill River. The soil has a dark gray to black layer of
silt loam 1 to 3 feet thick. It is the result of the deposition
of coal fines transported via the river from the anthracite
region farther to the north (upstream).
3. Geology
Bedrock Aquifer Geology
The geology underlying the Site consists of two formations of *;
Triassic age: the Brunswick Formation and the Lockatong
Formation. A portion of the Site is mantled by river alluvium. "
According to the "Groundwater Resources of the Brunswick
Formation in Montgomery and Berks Counties, Pennsylvania"
(Longwill and Wood, 1965), the Brunswick Formation consists of
thin to medium bedded, reddish-brown shale, mudstone, and
siltstone. The Lockatong Formation consists of predominantly
massively bedded, medium to dark gray argillite, interbedded with
thin beds of gray to black shale, siltsone, and mar1stone. Plate
1 of the 1965 Longwill and Wood publication shows two
intertongues of Lockatong Argillite in the Brunswick Formation at
the site, which are approximately 300 feet wide in outcrop and
are separated by approximately 400 feet. The Longwill and Wood
map also indicate that formations strike 80° east, with the
bedding planes dipping from about 13° to 18° toward the north.
Jointing is abundant and nearly vertical in the bedrock. The
Lockatong Formation is more massive, with fewer joint sets than
the Brunswick Formation. One well-developed joint set and two
less abundant sets exist in the Brunswick, with orientations
measured at north 30° east, north 75° east, and north 45° west,
respectively (Longwill and Wood, 1965)
A fracture trace analysis in the immediate vicinity of the Site
reveals somewhat different local orientations than that
characterized in the regional hydrogeologic appraisal. Fractures
that may exist beneath the physical plant and the floodplain
were not apparent because bedrock fractures dp not normally show
through disturbed land or under sediment veneers. The majority
of the mapped fractures were approximately perpendicular to
bedding; orientations ranged from north-south to north 20° west.
A few fractures were sub-parallel to bedding strike including two
10
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which were•observed on the northern part of the property in an
undeveloped area as of 1959. The topography to the north and
northwest of the plant shows surface drainage generally parallel
to bedrock strike into either the Schuylkill River or Sprogles
Run, a clearly joint-controlled stream bed east of Pottstown and
oriented nearly north-south.
A hydrogeologic study at the Site in 1976 investigated the
properties of river alluvium. The alluvium ranges in thickness
from 9 to 20 feet thick and overlies a river cut terrace in the
bedrock on the southeastern half of the Site. A sand and gravel
zone ranging from 0.5 to 15 feet thick, with a 5.5. foot average
thickness, occurs directly above the weathered, silty shale
fragmented bedrock. The remainder of the Site is covered with
weathered siltstone and shale regolith which is 6 to 10 feet
thick.
Overburden Aquifer Geology
The overburden soils at the Site consist of alluvium, fill, and.
weathered bedrock. The results of the RI indicate that the
alluvium is not continuous beneath the plant area and that an
overburden of mainly fill material overlies the bedrock in the
developed areas of the site. -, "
Boring logs in the vicinity of the lined lagoons indicate that
the alluvium in this area is 4 to 10 feet thick, largely
unsaturated, and, consists of black topsoil or coal fines, orange-
brown, silt, and a sandy gravel overlying weathered bedrock
layer. The alluvial deposits extend to the approximate boundary
of the floodplain, but the alluvium is dry over much of this
area.
The overburden in the vicinity of the plant area is 8 to 11 feet
thick and consists of silty sand fill with some gravel and
cobbles. The overburden beneath the plant area is also largely
unsaturated with the exception of a perched water zone in the
vicinity of the concrete basins of the vastewater treatment
plant.
B. NATURE AND EXTENT OP CONTAMINATION
The Remedial Investigation into the nature and extent of
contamination occurred from late 1990 through 1991. A summary of
results of the physical and chemical characterization of the Site
is shown below:
Data Evaluation: The chemical data was validated to
identify cases where reported concentrations may be
inaccurate (estimated concentration) or where chemicals
may not have been present in the sample when it was
11
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collected (suspect data). Data validation also
identifies chemical concentrations which are. below the
level which can be measured accurately. These data are
referred to as "estimated" concentrations and are
qualified as such when the concentration of chemical is
below a level which can be measured accurately
(quantification limit) but above a level that can be
detected (detection limit).
Blank samples prepared in the field or laboratory were
also analyzed. Chemicals detected in the field blank
indicate that contamination was introduced into the
sample during sampling procedures in the field while
chemicals detected in the laboratory blanks indicate
that contamination was introduced into the sample at
the laboratory. Detection of chemicals in either type
of sample is therefore considered suspect. However,
this data is still reviewed during data validation and
flagged for its useability. Data were considered
suspect when sample concentrations were within a factor
of 10 of the blank concentration for the following
laboratory chemicals: methylene chloride, toluene,
acetone, phthalate ester, and methanol. For any other -w
compounds detected in a related blank, a factor of 5
was used to define suspect data.
EPA Region III, Central Regional Laboratory (CRL)
provides a data validation oversight process to ensure
that the validation of the analytical results was
properly performed. CRL examined the technical adequacy
of the review (i.e. were proper protocols used and
correctly applied), application of data qualifiers, and
accuracy of data transcription. CRL's review indicates
that the validation was done correctly for this site.
Bedrock G
• Groundwater flow in the bedrock is controlled
primarily by fractures in the rock and the types of
rock comprising the aquifer; the sandstone units in the
bedrock are more permeable than the shale and
siltstone.
• The gradient in the bedrock aquifer is from the
Schuylkill River radially inward to the center of the
Site; this is an induced gradient resulting from the
cbntinual pumping of plant production wells near the
center of the Site.
• There are no off-site wells hydraulically
downgradient of the Site as a result of the induced
12
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gradient. A well inventory indicates that are no
residential wells -within a 1/2 mile radius of the Site.
* In the production area of the Site, unsaturated
conditions predominate in the overburden. East of the
production area, an overburden (alluvial) aquifer is
present under portions of the floodplain.
• As a result of groundwater sampling, five volatile
organic compounds are the identified chemicals of
concern in the groundwater, and the extent of each
(both in area and depth) varies. (See Figure 4 for well
locations) Concentrations of these five VOCs in ground
water at the Site exceed the EPA maximum contaminant
levels (MCLs) for those compounds in drinking water.
These compounds are trichloroethylene (TCE) , trans-1,2-
dichloroethene (trans-l,2-DCE) , vinyl chloride monomer
(VCM)-, styrene, and ethylbenzene. The RI/FS estimates
the TCE plume to have a volume of 258 million cubic
feet. The ethylbenzene plume is estimated at 38
million cubic feet, the VCM plume is estimated 22
million cubic feet, the trans-l,2-DCE plume is
estimated at 20 million cubic feet, and the styrene ,
plume is estimated at 13 million cubic feet. Figure 5
depicts the aerial extent of the TCE contaminant plume
which is the largest of the five plumes. Groundwater
is contaminated to depths as great as 582 feet,
although concentrations of TCE and other VOCs are
generally the greatest within 200 feet of the land
surface near the former TCE handling area. In earlier
investigations, the soil and shallow bedrock had been
shown to be contaminated by TCE (monitoring wells were
drilled to depths of 125 feet or less) , but TCE was
present in production wells that are as deep as 440
feet. In the RI, discrete zones to depths as great as
582 feet were sampled using packer tests in 10
additional deep bedrock monitoring wells drilled for
the RI. Concentrations of TCE in ground water as great
as 91 mg/L were measured from producing zones near 77
feet below land surface of one reconnaissance bedrock
well (TB-3) . Although greatest ground water
concentrations of TCE were from zones in the upper 200
feet of the aquifer, TCE concentrations of 3 mg/L were
measured in water from a zone 500 feet below land
surface in a well (TB-1) .
\ .-....-
• Groundwater flow in the alluvial aquifer appears to
discharge to the Schuylkill River under natural
conditions. Under pumping conditions, the groundwater
flow appears also to discharge to the Schuylkill River
13
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. «*U.
Xfll COMF1 fllOM IfCfffD
• )(-• MCOMWSSMlCf KOMOCII
• *>-i MMOCK HOMIOMIC
0 M-l 0«CMU«D(H UOMIOMHC
O M-M lr.
-------
LEGEND
0TB-4 Recoonai**ono«
Locotion
MDL/WCL (0.005 mg/l)
Concentration Contour (mg/t)
4001
Rgure 5
Occidental Chemical
TCE
Isoconcentrc
Contour R
-------
for the majority of the Site. (See Figure 6) Water
level measurements located in the vicinity of the lined
lagoons are often dry. This may indicate that the
alluvial aquifer in this area recharges the shallow
bedrock aquifer due to imposed pumping stresses. .This
is supported by the presence of more permeable
sandstone units intercepting the alluvial aquifer at
this portion of the Site.
* The original sampling program included 11 wells, but
3 were dry. The sampling results include analyses from
6 overburden and 2 shallow bedrock monitoring wells.
The overburden groundwater was analyzed for volatiles,
semivolatiles, PCBs, pesticides, and metals. Volatile
compounds were not detected at concentrations above
their respective MCLs. Ethylbenzene, styrene, and
toluene were detected in a few samples but their
presence is suspect due to their presence in laboratory
blanks.
Semi-volatile compounds were detected in the overburden
aquifer. Benzoic acid was detected in OW-19 at an - •>•
estimated concentration of 2 ug/1. Bis(2-ethylhexyl) *
phthalate was detected in the same well at an estimated
concentration of 310 ug/1. Butylbenzyl phthalate and
di-n-octyl phthalate were also detected in OW-19 at
estimated concentrations of 3 ug/1 and 4 ug/1.
No PCBs or pesticides were detected in the samples.
Six overburden wells were analyzed for metals.
Detected concentrations were below background except
for iron (OWl-2) and manganese (OW-12 and OW-24A).
Schuvlklll River
• Twelve surface water samples and one duplicate were
collected from the river. (See Figure 7) No volatiles
were detected which could be positively attributed to
the field samples. Five compounds, including common
laboratory chemicals were reported in a few samples and
also in associated blanks; therefore, their presence in
the field samples is considered suspect. Acid
extractable compounds were not detected in any of the
samples. Bis(2-ethylhexyl) phthalate was detected in
all samples, but was considered suspect due to the
presence of this compound in the associated blanks.
The results of the metals analyses indicate that most
metals were either not detected or were present at
concentrations below background surface -water levels.
16
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113(4 "*" '"" "" 'M
fttlci Ufeto ttaw
mlowiCI
HKiixU »«M« «ll*fi
SG-3 -,tic«ln 0*40* ICK4II
A I 12.00 ...Kl H...4 H.,,,,00
t*! HOW Ow«CU
FIGURE G
Alluvial Aquiler Water Table Map
(Pumping Conditions ; 9/15/89
-------
ML
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SR-3-SEO
SR3ASEO
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Schuyfcl River Sediment and Surface Water Samptog
-------
"» Sediment sampling revealed that volatiles were
present but were also detected in the associated
blanks. Acid extractable compounds were not detected
in any of the samples. Base neutral compounds were
not detected in any of the samples above background
with the exception of one sample. Butylbenzylphthalate
was not detected in the background sediment but was
detected in 2 samples at estimated concentrations of
300 ppb and 160 ppb. The majority of the samples
contained low levels of polycyclic aromatic
hydrocarbons (PAHs).
Metals were generally not detected above background
sediment concentrations with the exception of SR-4-SED.
This sample contained 7 metals above background
sediment levels: chromium (140 mg/kg), cobalt (68
mg/kg), copper (230 mg/kg), lead (260 mg/kg), manganese
(2,400 mg/kg), nickel (110 mg/kg), and zinc (500
mg/kg). :
Storm Water Sever Outfalls "*
» Outfall Surface Water
No VOCs were detected in the southern storm water
outfall sample. (See Figure 8) Four volatiles (1,2-
DCE, acetone, total xylenes, and TCE) were detected in
either the field sample or field duplicate sample
collected from the northern storm sewer outfall.
Acetone was the only compound that was common to both
the sample and the field duplicate. Acetone was
detected at a concentration of 1,000 ug/1 in the sample
(NSO-1) and at a concentration of 52 ug/1 in the
duplicate sample (NSO-1A). TCE and 1,2-DCE were
detected in the northern outfall sample at
concentrations of 7 ug/1 and 2 ug/1, respectively, but
were not detected in the field duplicate sample. Total
xylenes were detected in the northern storm sewer field
duplicate sample (NSO-lA) at an estimated concentration
of 2 ug/1, but were not detected in the sample (NSO-1).
No SVOCs were detected at concentrations which could be
positively attributed to the field samples. Bis(2-
ethylhexyl) phthalate was detected in all samples at
concentrations ranging from 2 ug/1 to 3 ug/1.
V
Most metals were either not detected or present at
concentrations below background surface water levels.
19
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Storm Sewer Sediment
-------
.» Outfall Sediment
Two sediment samples and 1 field duplicate were
collected below the storm sewer outfalls.
The field duplicate contained an estimated 8 ug/kg of
1,2-DCE, but 1,2-DCE was not detected in the field
Sample. VCM was detected in Sample NSO-1-SED at an
estimated concentration of 5 ug/kg. Acetone and 1,1,1-
TCA were also detected in the sediment samples.
One acid extractable compound, 4-methylphenol (p-
Cresol), was detected in the northern storm water
outfall sediment sample at an estimated concentration
of 170 ug/kg, but was not detected in the field
duplicate sample from this location. Polyeyelie
Aromatic Hydrocarbons (PAHs) and phthalates were
detected in the sediment samples. A total of 13 PAHs
were detected in the northern storm sewer samples with
a total PAH concentration of 5,800 ug/kg. A total of -
10 PAHs were detected in the field duplicate from this
location with a total PAH concentration of 5,500 ug/kg..
The sample from the southern storm sever contained 5
PAHs and had a total PAH concentration of 1,700 ug/kg.
The PAHs common to both the NSO-1-SED and SSO-1-SEO
samples and their range of corresponding of
concentration are: benzo( a) anthracene (180-530 ug/kg),
chrysene (270-600 ug/kg), fluoranthene (500-860 ug/kg),
phenanthrene (350-820 ug/kg), and pyrene (440-870
The 2 phthalates detected in the samples were bis (2-
ethylhexyl) phthalate and di-n-octyl-phthalate. Bis (2-
ethyhexyl) phthalate was detected in samples SSO-l-SEO
and NSO-1-SED at concentrations of 11,000 ug/kg and
6,200 ug/kg, respectively. Di-n-octyl phthalate was
detected in the northern storm sewer outfall (NSO-1-
SED) sample at a concentration of 250 ug/kg, but was
not detected in the field duplicate from this location
or in the southern storm sever outfall sample.
Most metals were either not detected or were present at
concentrations below background sediment levels.
The metals above background levels were detected in the
NSA-l sample at the following concentrations: cadmium
(15 mg/kg), calcium (3800 mg/kg) , chromium (120 Kg/kg) ,
mercury (0.54 mg/kg), copper 83 mg/kg) and zinc (290
mg/kg).
21
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Sediment Pond and.Drainage Swale
* Drainage Swale Surface Water
Three samples and 1 duplicate samples were collected
from the sediment pond discharge swale. (See Figure 9)
The following 7 volatiles were detected in the surface
water samples: 2-butanone (MEK), 4-methyl-2-pentanone
(MIBK), carbon disulfide. Vinyl Chloride Monomer (VCM),
acetone/ methylene chloride, and toluene. In general,
the surface water sample (SW-i) collected below the
sediment pond discharge pipe contained the highest
concentrations and the large number of volatiles.
VCM and MEK were detected in SW-1-SW at concentrations
of 6 ug/1 and 20 ug/1, respectively. MIBK was detected
at a concentration of 110 ug/1 in SW-l-SW. Carbon
disulfide was detected in the field duplicate SW-2A at
an estimated concentration of 4 ug/1, but was not
detected in the corresponding field Sample SW-2.
Two acid extractable compounds and 2 phthalate esters -v
were detected in the surface water samples. Benzoic
acid and phenols were detected in sample SW-i at
estimated concentrations of 43 ug/1 and 4 ug/1,
respectively. Di-n-octyl phthalate was detected in the
SW-l sample at an estimated concentration of 4 ug/1.
All of the samples contained bis-(2-ethylhexyl)
phthalate; however, the presence of this, compound was
considered suspect due to its presence in the blank.
Most metals were either not detected or were not
present at concentrations above background surface
water levels. Metals detected in SW-l above background
levels and the corresponding concentrations are as
follows: calcium (33 mg/1), manganese (1.1 mg/1)
potassium (5.4 mg/1), selenium (1.001 mg/1) and zinc
(0.29 mg/1). Aluminum (2.9 mg/1), and iron 2.8 mg/1)
were detected at concentrations above background in
sample SW-3.
• Drainage Swale Sediment
Nine VOCs were detected in the samples. Two VOCs (VCM
and ethylbenzene) were detected in the sediment pond
sample at estimated concentrations of 93 ug/kg an 8
ug/kg, respectively. TCE was detected in 4 of 10 of
the sample, 2 of which were collected in the low lying
area at the base of the sediment pond and the other 2
22
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.
NO, C4064900
SCALE: r-150
FIGURE 9
SEDIMENT POND AND DRAINAGE SWALE
SAMPLING LOCATIONS
-------
were collected in .the drainage swale within 400 feet of
the sediment pond discharge pipe. The maximum TCE
concentration was estimated at 19 ug/kg detected in
sample SW-4-SED. The results indicate that the VOCs
are mainly associated with the sediment pond sample
(SW-l) and the SW-5) immediately below the sediment
pond discharge pipe.
One acid extractable compound (benzoic acid) was
detected in 5 of 11 samples at concentrations ranging
from 490 ug/kg to a maximum of 16,000 ug/kg at SW-l.
The samples containing benzoic acid were confined to
the sediment pond and the soils at the base of the
sediment pond. Dibenzofuran was detected in 2 samples,
at estimated concentrations of 61 ug/kg and 1,300
ug/kg, respectively. Other SVOCs detected in the
sediments and soils include phthalates and PAHs. The
greatest variety and highest concentrations of
phthalates and PAHs were associated with the sediment
pond sample (SW-l) and the swale sample (SW-5)
immediately below the sediment pond discharge pipe.
Fewer compounds and generally lover concentrations were
detected in the sediment samples collected downstream •<-..
of the SW-5 sample location.
The four phthalates detected in the sediments and soils
were bis(2-ethylhexyl) phthalate, butyl benzyl
phthalate, di-n-butyl phthalate, and di-n-octyl
phthalate. Bis(2-ethylhexyl) phthalate was detected in
all samples at estimated concentrations ranging from
690 ug/kg to 55,000 ug/kg. The 2 highest
concentrations were detected in samples Sw-l SED and
SW-5-SED at 22,000 ug/kg and 55,000 ug/kg,
respectively. Butyl benzyl phthalate was detected at
concentrations ranging from 100 ug/kg to 3,000 ug/kg
with the concentrations over 500 ug/kg detected at SW-l
(510 ug/kg) SW-3 (3,000 ug/kg), SW-5 (860 ug/kg) and
SW-7 (560 ug/kg). Di-n-butyl phthalate was detected in
3 of 11 samples at concentrations ranging from 56 ug/kg
to a »«vi«»i«« concentration of 290 ug/kg, detected at
SW-l. Di-n-octyl phthalate was detected in 30 of 10
samples which ranged in concentration from 130 ug/kg to
5,200 ug/kg.
PAHs were detected in all samples except SW-6, although
several PAHs were detected at low concentrations in the
field duplicate from this location. The greatest
number of PAHs were detected in samples SW-2 through
SW-5 at concentrations of total PAHs ranging from 3300
ug/kg to 99,000 ug/kg. The main PAHs detected in the
samples included chrysene, fluoranthene, phenanthrene,
and pyrene. The highest concentrations of total PAHs
24
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were detected in samples SW-5 (99,000 ug/kg), SW-3
(7,500 ug/kg), sw-4 (5,000 ug/kg), and sw-7 (5,020
ug/kg).
PCB-1254 was detected at an estimated concentration of
740 ug/kg at SW-10. Pesticides and herbicides were not
detected.
Various metals were detected at concentrations in
excess of background concentrations for sediment.
Arsenic was above background at the following
locations: SW-1 (22 ug/kg), SW-3 (55 ug/kg), and SW-7
(250 ug/kg). Chromium was detected at concentrations
above background in 2 samples (SW-5 and SW-7) at
concentrations of 110 mg/kg and 130 ing/kg,
respectively. Concentrations of cobalt above
background were detected in 2 samples SW-8: (40 mg/kg),
and SW-10 (69 mg/kg). Nickel was also detected at
these locations at concentrations of 62 mg/kg (SW-8) -
and 86 mg/kg (SW-10). Zinc was detected at
concentrations in excess of the background soils in SW-
5 (490 mg/kg) and SW-7 (530 mg/kg).
Borrow Area Sediment
Two VOCs (TCA and 1,2-DCE) were present at trace
concentrations in two sediment samples. (See Figure 10)
Total xylenes, methylene chloride, acetone, and toluene
were also detected in the sediments.
Acid extractable compounds were not detected in the
samples. Fluoranthene and pyrene were detected in
Sample B-2 at estimated concentrations of 210 ug/kg and
190 ug/kg, respectively. These concentrations are
below those detected in background soil samples.
Polynuclear aromatic hydrocarbons were not detected in
any of the other samples.
No PCBs and pesticides were detected in any of the
sediment samples.
Most of the metals were either not detected in the
sample or were present at concentrations below
background soil levels.
Plant Area Soils
The 5 VOCs detected above background soil
concentrations were: 1,1,1-TCA, TCE, 1,2-DCE, toluene,
and 2-butanone (MEK). 1,1,1-TCA was detected in 1
25
-------
)FT
-------
sample from the 8- to 10-foot interval of boring SB-2
at a concentration'of 6 u/kg. TCE was detected in all
12 samples. The TCE concentrations ranged from 1 ug/kg
to 3,900 ug/kg with the maximum concentrations detected
at the 0- to 2-foot interval of boring SB-7. (See
Figure 11) In general, the TCE concentrations were
higher in the lowest sample interval of each test
boring. The analyses detected 1,2-bCE in 11 samples.
The range of 1,2-DCE concentration detected was 3 ug/1
to a maximum of 200 ug/1 detected in the sample from
the 6- to 8-foot interval of boring SB-6. In general,
the higher concentration of 1,2-DCE ranging from 100 to
200 ug/1 were also detected in the samples from the
lower depth intervals of each boring.
MEK was detected in 3 samples at concentration of 77
ug/kg in the 8-10 foot interval of boring B-7, 820
ug/kg in the 8-10 foot interval of SB-6, and 860 ug/kg
in the 8-10 foot interval of SB-4. Toluene was
reported in all 12 field samples but the presence of
toluene is suspect due to its presence in the
associated blanks.
Lined Lagoon Soils
• Soil samples were collected from five test borings
around the lined lagoons. The total volatile
concentration of samples ranged from below the
detection limit to a maximum of 150 ppb. (See Figure
12) The 9 volatile compounds detected above background
concentrations are: TCE, 1,2-DCE, 1,1-DCE, l,2,l-TCA,
carbon disulfide, ethylbenzene, toluene, xylene, and
MIBK. TCE was detected in 5 of 9 samples at
concentrations ranging from 2 ug/kg to a maximum of 88
mg/kg.
• Semi-volatiles: Benzole acid was detected in 6 of 9
samples. The concentrations ranged from 61 ug/kg to
2300 ug/kg. The base neutral analysis detected 3
phthalates and 8 polynuclear aromatic hydrocarbons
(PAHs). The phthalates detected include bis(2-
ethylhexyl) phthalate, butyl benzyl phthalate, and di-
n-butyl phthalate. The concentrations of bis(2-
ethylnexyl) phthalate ranged froa 75 ug/kg to a maximum
of 4200 ug/kg. Butyl benzyl phthalate was detected in
1 sample at a concentration of 470 ug/kg. Di-n-butyl
phthalate was detected in 4 of 9 samples with estimated
cbncentrations between 40 ug/kg and 190 ug/kg.
• No PCBs or pesticides were detected in the samples.
• Three metals, arsenic, cadmium, and mercury were
27
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Leqeqj
• **«• I SVS Sompl. Point
•^ So* Barlng/Sompitao. Location
I SVS Sompilng Point
DWG. NO.C4064SVS
PLANT AREA SOIL CAMPLING LOCATIONS
'.*
Occidental Chtriiiu.iil i.oipoiuiion
Phase II '"Oil \,i|..)f fxjivry
And (.onlin.|fi,i '..Hi MIIIIII.J
I III .|l |. II / I.IJy
-------
8fT
FIGURE 12
Lined Lagoons Sampling Location:; j
-------
•detected above background soil concentrations.
Inactive Earthen Lagoons
» The earthen lagoons are located in the 100-year
floodplain of the Schuylkill River. Each lagoon is
generally composed of three layers; a white, wet
material, a gray to black wet material, and a coal
fines layer. The white and gray materials are products
of the PVC manufacturing process and will be referred
to in this document as PVC material. The total volume
of material in the four lagoons is approximately 38,000
cubic yards. The RI also revealed that the coal fine
material is not present at the bottom of Lagoon 1. At
Lagoons 2,3, and 4, it appears that the coal fine
material has served as a collection/adsorption layer
for the chemicals. It is believed that the soil
beneath the coal fine layer of Lagoons 2, 3, and 4 has
not been affected.
• In the area of Lagoon #1 which lacks the bottom coal
fine layer, soil sampling reveals contaminants are
present in the soils directly beneath the lagoons. The*-
contaminants present in the soils are those that are
present in the lagoon material.
• Soil sampling conducted during the RI detected the
presence of volatile and semi-volatile organic
compounds in the material contained in the four
inactive earthen lagoons. (See Figure 13) The
chemicals present are the result of the PVC _
manufacturing process. In general, the total volatile
organic concentration'(TVO) is less than 1,000 ppb.
Lagoon #1 is the noted exception, where the PVC sludge
material at a depth of 6 feet has a TVO concentrations
of approximately 24,000 ppb, and the underlying soil
has a TVO concentration of approximately 720 ppb.
• The semi-volatile organic compounds detected .are
those associated with the process of making PVC.
Benzole acid and bis(2-ethylhexyl) phthalate are the
compounds present. The concentration of benzoic acid
detected in the samples ranged from 1,600 ppb to a
maximum of 31,000 ppb. The concentration of bis(2-
ethylhexyl) phthalate ranges from 1,100 ppb to a
maximum of 280,000 ppb. The semi-volatiles appear to
be more concentrated in the upper 4 feet of material in
each lagoon.
• There were ho PCBs detected in any of the samples.
Pesticides were not detected in 3 of the 4 lagoons.
Three pesticides were detected in Lagoon #1 samples at
30
-------
-c
EARTHEN LAGOONS SAMPLING LOCATIONS
NO.: C4064900
SCALE: 1" = 100'
FIGURE 13
-------
- j
j
concentrations less than 1 ppm.
» The metal concentrations are not notably different in
the lagoon material than they are in the underlying
soils. The concentrations in both materials vary
widely.
VI. SUMMARY OF SITE RISKS
The Baseline Risk Assessment (BRA) provides the basis for taking
action and indicates the exposure pathways that need to be
addressed by the remedial action. It serves as a baseline
indicating what risks would exist if no action were taken at the
Site. This section of the ROD reports the results of the
baseline risk assessment which was completed by Occidental
Chemical Corporation" in March 1992 for the Site. In accordance
with OSWER Directive No. 9835.15 (8/28/90), EPA has determined
that the final human health risk assessment has been reviewed
independently by the Agency and has found that the human health
risk assessment is fully acceptable. The OSWER policy and EPA -
Certification of the BRA can be found in the Administrative
Record for the Site. ^
A. Human Health R^.ska
(1) Identification of Contaminants of Concern
Analytical data collected during the RI sampling were reviewed to
develop initial lists of Chemicals of Potential Concern (COPC) in
each of the following environmental media: bedrock groundwater,
overburden groundwater, earthen lagoon soil/sediments, lined
lagoon soil, borrow area soil/sediment, drainage swale sediment,
storm drain sediment, UST area 4 soils, plant area soils,
drainage swale and storm sewer surface water runoff. Each area
was considered separately. Chemicals were eliminated from further
consideration as COPCs when one or more of the following applied:
1. The chemical was not detected in any sample.
2. The chemical was detected at .concentrations below
five times the amount detected in* an associated blank
(data validation qualifier "b") in each sample.
3. The maximum value of the chemical was less than the
maximum detected background value.
4. The maximum levels of the chemical in groundwater
and surface water runoff was less than or equal to the
MCL.
32
-------
5. EPA-verified toxicity values (e.g. RfDs, RfCs,
slope factors, unit risks) were not available for the
chemical. Most chemicals eliminated by this criterion
are believed to exhibit minimal human health toxicity
(e.g. calcium, magnesium). The shaded chemicals
outlined on Tables 1 through 11 list the identified
COPC for each area investigated. All chemicals
detected in site samples were initially considered to
be chemicals of potential concern. Compounds were then
screened by comparison of on-site concentrations to
background and Maximum Contaminant Levels (MCLs). Some
chemicals for which there were no EPA verified toxicity
values were included using data verified by EPA
Environmental Criteria Office (ECAO). other toxicity
values were developed using adjusted oral data. (See
Tables 11-14 for toxicity dat£)
Despite these criteria, the EPA Risk Assessor takes into account
that there may be exceptions to the above criteria and in those
instances would retain the chemicals for further consideration.
(2) Exposure Assessment Summary
^
The exposure assessment identifies actual or potential pathways *
for human exposure to the contaminants of concern present in the
impacted media at the Site. Exposure pathways are assessed based
on two scenarios: current land use and future land use. The
property comprising the site is currently zoned for industrial
land use.
a. Potentially Expose^ fflflgan Populations
Based on the current and potential future land use of the Site,
the following subpopulations were identified:
Current Land Use - On-site Workers
- Swimmers (Schuylkill River)
Future Land Use - On-site Residents
- On-site Workers
- Swimmers (Schuylkill River)
A summary of migration pathways and receptors is provided on
Table 15.
33
-------
TABLE 1
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN
BEDROCK AQUIFER GROUNDWATER
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN. PENNSYLVANIA
Detected
Compounds
VOLATILE ORGANICS (ug/L)
1,1,1-TricWoroetnane
1,1-OfcnJofoethene
1.2-uichiofoetnane
1^-Oichloroethene (total)
2-Butanone
Bonxono
Carbon TetrachJoride
ClROlimWIM
Etnyfbenzene
Mettiytone Chloride
Styrene
Toluene
Total Xytenes*
Trin HI nrn rrfkAMA.
TnCfVOf CMAnttf 10
Vinyl Chloride
SEMIVOLAT1LE ORGANICS (u
*hencJ
Benzyl Alcohol
B^2-etnythexyf)phthalate*
Butytoenzylpnthaiate
Dkvbutyl phthalate
Dkvoctyl phthatete
INORGANICS (mg/L)
Aluminum* v
Antimony "I 7
Anwnte '
Barium
Cadum*
Chromkjra
COD*** ~"
Risk-Based
Concentrations
(Tap Water)
130
0.058
0.16
5.5
180
n .4A
0.49
0.22
M M4
0.21
130
5.4
0.47
75'.-' .,''-
1200
2.1
0.025
)A)
2200 •'•'.
11 no **&"
1 1UW:':;....- •;•;•
&1
730
370
m;mm«
n
ooot«
' O000040
028
NA
OJ)18
0.001
MCL
200
7
5
70
NA
5'
5
44WV
100
700
5
'--' "100C" "•••
1000
10000
.'../•- i-.v .^vS-:;-:.' --v-:
l:'.-'-'^L:' '-C
':. :':-: •xNAy'C ••"•
'•'•" ' : NA ';;
.- • I^A • . .
6
100
NA
.'^y-7Jr:- V
NA
^' 0008
<
"^ *'"'' •• OjQS
2
NA
O.t
NA
Maximum i
Background j Well
Concentration i Location
NO !
NO
NO
NO
NO
•vm
ND
NO
klf%
NO
ND
NO
2jb
NO
NO
NO
.:-:•!. NO ':"
NO
NO
20 b
ND
**
.... -NO-' .. .
0038 b]
- NO"1-
NO
OJ7
42
NO
0.053 b
:
TB9
TB9
TBS
TBO
," - " '
' ' '- ^ -
PW1R
PW1R
- * '
TBO
Maximum j
Sample ( Well
Concentration i Location
1
1
2| 1 TB7A
19
4|
8500
2700 1
4 J ]
140
130 -
20000
4Jjb
noooa
13006
2000
•.':';:21000.-;:";:::'-
•2000'.. v".''
. ' ':t60;::V '.. .
2J|
19B6
3)
IJBJb
, ,^-*f€^;:^
082 1
~^?OJMrj|t4*K
V/^V^tf-1 ' ^*?^^">*Aa(*tf
O24
47
- 7 ajtf^;"^
O057b
TB2A ;
TB2A
TB1B
TB3 ,
>-TB5
•r-TB5 'j
• •TBS
BRB '
TB7D :
BRB |
BRB '
TB1II ;
TBt3
TB2A .j
.:TB2^'. •)
"BRE I
TB2H '•}
TBi '
BR13
TB )
i
pwr ;
^IBTC
^;TB2A;':'-
BRB
SR8/TB2
™ TBt
^ BRB
-------
TABLE. 1 (continued)
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN
BEDROCK AQUIFER GROUNDWATER
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN, PENNSYLVANIA
Detected
Compounds
INORGANICS (mg/L)(continuc
Copper
Iron*
Lead
Magnesium*
Manganese
Mercury
Nickel
Potassium*
Selenium
Sodium*
ZJnc
Risk-Based
Concentrations
(Tap Water)
ri)
0.14
NA
NA
NA
0.37
0.0011
0.073
NA
0.018
NA
1.1
MCL
1.3 (action level)
NA
0.015 (action level)
NA
NA
0.002
0.1
NA
0.05
NA
r- -vNAt"
Maximum i
Background j Weil
Concentration j Location
:
:
0.0094 b] 1 PW1R
0.89 J
0.012 b
13
0.11)
0.0001 fl
NO
161
NO
24
0.038J
TBS
TB9O
TB9
TB9
TB9
PW1R
PW1R
TB90
Maximum
Sample
Concentration i
Weil
Location
{
l
•
0.025 b
5i
0.02k
25
1.9 k
0.0001
00)49
270| «
0.0023 fl
330]
0.061 J
TB1
BR1
PW7
TB2
BRB
. PW7
" TB1B
, TB1
PW7
TB2A
BRB i
RnuM m founded 10 two signMcant
MdMtontf OMmieal o» PrtwrtW Conown If Rhfc Btt*d GonewiMlem
m ua^ to OMcribc COPOl.
«dtQ3dolty«^^
NO « Not
8 -Found In
J
b m
of poMWeenem)
din to
UmR.
• VMM btaMd high.
]-VMMl
Umft.
-------
TABLE 2
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN
OVERBURDEN AQUIFER GROUNDWATER
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN. PENNSYLVANIA
Detected
Compounds
VOLATILE ORGANICS (ug/L)
Ethylbenzene
Methylene Chloride
Styrene*
Toluene
TnciuofOdinone
Risk-Based
Concentrations
(Tap Water)
130
5.4
0.47
75
2*
.1
SEMIVOLATILE ORGANICS (ug/L)
BenzoicAcid ~
Bis(2-etrryihexyOphthalate
Butylbenzytphthalate
DMvbutyl pnthaJate
DHVoctyi pntnatate
INORGANICS (mg/g
Aluminum*
Antimony
Arsenic*
Barium
Caidum
Cobatt**
Copper
Iron*
Lead
Magnesium
Manganese
Nickel
Potassium*
Sodium
Zinc- ••- ••••- •"•;:•:
. 15000
6.1
730
370
73
11
0.0015
0.000049
0.26
NA
0.001
0.14
NA
NA
NA
O37
0.073
NA
NA
v : 'Vtrvr.'
MCL
700
5
100
1000
NA
6
100
NA
NA
NA
0.006
0.05
2
NA
NA
1.3 (action level)
NA
0.015 (action toveO
NA
NA
ai
NA
NA
••••Wi"x'-'-'--
Maximum {
Background j Well
Concentration i Locatio
NO !
NO j
2jb j TB9
NO i
tm :
ND :
|
NO
20 b
NO
2jb
NO
0.038 b]
NO
ND
0.37
42
0.053 b
0.0094 b]
0.89 J
0.012 b
13
0.111
ND
1.8J
24
0.0381
TB9
TB9
TB9
PW1R
PW1R
TB9
PW1R
TB9
TB9D
TB9
TB»
PW1R
PW1R
TB90
Maximum i
Sample Well
Concentration Location
2Jjb OW19
UJb 1 OW8A
7jb
Ujb
2J|
2JJI
310 B
3J
SJBjb
4jj -
0.17 b]
0.031 Jj
0.0025 fl
0.181
261
0.056 b
0.016 b)
27
QJ0032 b •-
13
"'.. .' O6I.:;-V'C.
0.022 fl
2.2)
18k
•" .'-"aiaF^y1
OW19
OW19
OW24A
OW19
OW19
OW19
OW19
OW19
.
OW12
OW12
(5W8A
OW8A
OW11
OW21
OW12
OW12
OW21
OW12
OW12
OW12
OW21
OW21
OW12
ODAOMII m
ft dwnlotl of poiMMl
UML
Ooniriel Mqutad OuMMton IMt
-------
TABLE 3
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN: EARTHEN LAGOON SEDIMENT
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN. PENNSYLVANIA
Detected
Compounds
Risk-Based
Concentrations
(Industrial)
Maximum I
Background I
Concentration!
Sample
Location
Maximum i
Sample {
Concentration!
Sample
Location
VOLATILE ORGANICS (ug/kg)
1.2-Otehloroethane 31000
1,2-Otehtoroethene (total) 920000
2-Butanohe ~ . 5100000
Acetone 10000000
Benzene 99000
Carbon Otsuffide 10000000
Methytene Chloride 380000
Slyrene 95000
Tetrachkxoethene 55000
Toluene 1600000
Total Xytenes 20000000
Trtehkxoethene 260000
Vinyl Chloride 1500
SEMIVOLAT1LE ORGANICS (ug/kg)
Benzole Add
2-Methylnapntnalene
Acenapntnytene
Benzo[a]anthracene
Benzo(a]pyrene
Benzo[b]fluoranthene
Benzo(k)fluorenthene
Bls<2-*hythexy9phthatate
DWvbutytphthatete
Xetnyf uHfitttate?-
Ruoranthene
Phenanthrane
PyiBne *
PESnOOES/PCBs (ug/kg)
Attii
410000000
NA
6100000
2700
3200'
7400
10000000
82000000
4100000
4100000
3000000'
3100000
8400
fTO*
450
NO
NO
NO
ND
NO
NO
NO
NO
NO
21
NO
NO
ND
100J
NO
2001
220}
230]
630 b
2801
3H
NO
450J
2201
440|
NO
NO
OS-3S
PBQ-1A
OS-2-S
OS-1-S
OS-1-S
OS-1-S
OS-1-S
OS-t-S
OS-T-S
0848
OS-1-S
% '^-/t
OS-1-S
OS-1-S
3200
4800 OE |
27]
12000)
2000)
23000
11000
2100 DJ
8500
1600DJ
7000 OE |
940 Dj
17000
310000]
88|
100]
2701
220]
230 f
IX]
280000 OE]
380)
180001
2301
* 38000}
700 Of
330]
TB1-8
TB1-6
TB8-10
TB1-6
TB1-6
TB1-6
TB1-8 :
TB1-8
TB1-6
TBM
TB6-W
TB8-*
TB84S
TB7-40L
TB8A5
TB7-«OL
TB7-IOL
TB1*
-------
TABLE 3 (continued)
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN: EARTHEN LAGOON SEDIMENT
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN. PENNSYLVANIA
Detected
Compounds
INORGANICS (mg/kg)
Aluminum*
Antimony
Arsenic
Barium
Beryllium* . .
Cadmium
Calcium*
^ciTDmtum
Cobalt
2OOO8T
^^ff**"
Iron*
Lead
Magnesium
Manganese
Mercury
Nickel
'otasskjm
Selenium
SIV9T
Sodium
Vanadium
Zinc
Concentrations
(Industrial)
300000
41
1.6
7200
0.67
51
NA
510
NA
3800
NA
NA
NA
10000
31
2000
NA
510
510 ,
NA
720
31000
Maximum j
Background | Sample
Concentration 1 Location
30000 1 OS-1-S
NO
9.3
230 1
3.4
111
5500)
77
80J
iaoj
48000 j
270)
4800
2900J
•='• 03*
95)
3800
1.51
NO-.'"1
420
50J
4701
i
FBG-1-S
OS-2-S
OS-3-S
OS-1-S
OS-2-S
OS-1-S
OS-2-S
OS-3-S
OS4-S
OS-3-S
OS-1-S
OS-2-S
OS-1-S
OS-1-S
OS-1-S
OS-3-S
FBG-1-S
OS-3-S
OS-2-S
Maximum
Sample
Concentration
34000
301
27
430|
Z2
3.3
23000
130]
36)
61
49000
120
3900k
2800)
o.»
39
3200
0.95 1]
"y :t.iii:;*:;:-
4000
49
170
1
j Sample
Location
I TB6-13A
TB6-13
TB6-13.TB84.TB8-10
TB6-13A
TB8-10
TB8-8
TBW
TB1-8
TB6-13A "
TB6*5
TB7-12 *•'
IBM
TB7-10 - »
TB6-13A
TB6-9.5
TB8-10
TBM4
TB645
TB6-13A
TBW
TB6-13
TBS45.TB8-10
• - MdWoml Crwmtetf of PotantW OonoHn I
# - NoteoraUcradachMnlorief polMM
NA-Not
NO-Not
B-Found to
0 - Compound*Idwitttodduring ramly*of*
du»«o
COPCft.
MMO(Mwch19B2.
•M amount to tw i
i b •» net
I-
mid/ar
UrriL
IML
>VWu»btaMdNgh.
-------
TABLE 4
1DENT1HCATION OF CHEMICALS OF POTENTIAL CONCERN: LINED LAGOON SOIL
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN. PENNSYLVANIA
Maximum
Sample
Concentration
Maximum
Background
Concentration |
Risk-Based
Concentrations
ndustrial)
Sample
Location
Sample
Location
Detected
Comouns
VOLATILE ORGANICS (ug/kg)
1.1,1-Trichloroethane
1,1-Otenkxoethene
1,2-Ofchkxoethene (total)
4-Methyl-2-pentanone
Acetone
Carbon Ofsuffide
Chloroform
Ethylbenzene
9200000
4800
920000
5100000
10000000
10000000
470000
10000000
380000
Methytene Chloride
oiuene
otalXytones
rlchtoroethene
20000000
260000
SEMtVOLATlLE ORGANICS (ug/kg)
2300 '
940|
110 Jj
90J|
110 J|
4200 B )
470}
170 J |
Benzole Add
OS-1-S
OS-1-S
OS-1-S
OS-1-S
2700
3200
7400
200000
20000000
NA
iiboopoo,^
4100000
gOQfljBPP
3100000
Benzo[a]anthracene
Benzo[blfluorantnene •
Benzo[k]fluoranthene
Bte(2-ethyftiexy()phthalate
Sutytoenzylphthatate
Chrysene
DtwfeutylpMtalat* :
Ptuotanthene
OS-1-S
OS-2-S
OS-1-S
OS-1-S
OS-1-S
120 J I
110J
210 J
Phemu
-------
TABLE 4 (continued)
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN: LINED LAGOON SOIL
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN. PENNSYLVANIA
Detected
Compounds
Risk-Based
Concentrations
(Industrial)
INORGANICS (mg/kg) (continued)
Chromium
Cobalt
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Potassium
Sodium
Vanadium
Zinc
510
NA
NA
NA
NA
10000
31
2000
NA
NA
720
31000
Maximum j
Background j Sample
Concentration j Location
:
:
•
77 ! OS-1-S
80J
48000)
270 j
4800
2900)
O54
95j
3800
420
50)
470 1
OS-2-S
OS-3-S
OS-3-S
OS-1-S
OS-2-S
OS-1-S
OS-1-S
OS-1-S
FBG-1-S
OS*S
OS-2-S
Maximum
Sample
Concentration
Sample
Location
:
:
:
:
47j | LL5-«
21 | (±5-4
42000
86 j
3400]
850
0.71
28
2600
330
461
180
LL3-4
LL5-4
LL5-10
LL3-4A -
LL5-4-
LLS4 ±
LL2-4 -
LL3-10^ .
LL1-6
LL5-4
m raundod to two tiQnMnnt flQmBb
MdMoral ChwniGal o» Pamntt* Conewn If RWc BMd
Not eoraUOTd • ehwntart of potwMW eonown du* to
«• uMd to OMerib* OOPCl.
^wMtod tnddty MhiM«oMi»intt^tlmMtt>««mounllnih«
(WuM QuflM^d wHh bflN nottiQMiMVM onvnovv of polwdW oonown)
J'
i Urn*
k • \MM fatoMd Ngh.
Un*.-
-------
TABLE 5
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN: BORROW AREA SOIL/SEDIMENT
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN, PENNSYLVANIA
Detected
Compounds
VOLATILE ORGANICS (ug/kg)
1.1,1-Trichloroethane
1.2-DicMoroefhene (total)
Acetone
Methylene Chloride
Toluene
Total Xylenes
SEMIVOLAT1LE ORGANICS (ug/kg)
Bb(2-etrrylhexyQpnthalate
Ruoranthene
Pyrene
INORGANICS (mgAg)
Aluminum*
Barium
Beryfiium*
Cadmium*
Calcium
Cnromium
CobeJt
Connor
•p**P*r****
Iron
Lead
Risk-Based
Concentrations
yp - r * J ' _n.t' l\
(Residential)
700000
70000
780000
230000
1600000
16000000
120000
310000
230000
23000
550
0.4
3.9
NA
39
NA
290
NA
NA
Maximum
Background
^fin**t\**t***tt****
uoncenucuion
•
NO
NO
9JB]b
NO
6JBjb
NO
1400 JBjb
880 J)
820 Jj
22000
150
2.41
12
2600]
82
39k
70k
24000
190|
Sample
1 •-••rttl»» "
Location
'
SR-1 -3
SR-1
SR-1
SR-1
SR-1
SR-1
SR-1
SR-1
SR-1
SR-1
SR-1
SR-1-3
SR-1
SR-1
SR-1
Maximum
Sample
Concentration
3 JBjb
3JJ
12 JBjb
13 JBjb
8b
2 JBjb
450 JBjb
210 Jj
190JJ
28000
140k
1.2k]
9-1 1
14000
35k
23k
28]
22000 1
53k
Sample
Location
•
B-1.B-3A
B-2.B-3
B-1.B-2
B-2
B-3A
"B-3A
i, •
M
- 6-2
B-2
B4
B<3
B-1
B-3
B-1.B^
B-3
B-1
B-1
&3A
B-1
-------
TABLE 5 (continued)
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN: BORROW AREA SOIL/SEDIMENT
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN. PENNSYLVANIA
Detected
Compounds
INORGANICS (mg/kg) (continued)
Magnesium
L^iiimnf* i*«*j»^
wanganese
Mercury
Nickel
Potassium*
Thallium
Vanadium
ZJnc
Risk-8ased
Concentrations
(Residential)
MA
780
2.3
160
NA
0.63
55
2300
Maximum j
Background I Sample
Concentration ! Location
4100
15001
0.371
56 j
1700]
1-21]
100 1
SR-1
SR-1 -3
SR-1
SR-1
SR-1
SR-1
Sfl-1-2
250 k j SR-1
Maximum
Sample
Concentration
3900
13001
0.29|
33k
3500
0^5 j]
34J
1501
Sample
B-3
B-3
B-1
B-1.B-3
B*
B-2
*H,
B-U
m reunited to two tigniflcant figure.
• • AddHtofMl ChMrtcal at PotwitW Cenewn V Rtt 8M«d
« • Nat eantfdOTd • efMtnieal al pottntW eanam due to
btenk.
i «• und to OMerte COPOk.
NO-NMOMKttd
B • Found hi
0 - Compound* idwitttod
c •
b • VWUM quitted dw* to prnm* of aratyt* to t» Mnpto « to
(VUuot QUMnwQ wnn o MV notoomioMo tfiHRBHsof podnui oonoonii
twnnountlnflMi
lUn*.
It • VHm blMirt Mgh.
I« VMu* I
-------
TABLES
o
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN: DRAINAGE SWALE SEDIMENT
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN, PENNSYLVANIA
Detected
Compounds
Risk-Based
Concentrations
(Industrial)
Maximum
Background
Concentration
Sample
Location
Maximum j
Sample j
Concentration j
Sample
Location
VOLATILE ORGANICS (ug/kg)
1.1,1-Trichioroethane
1,2-Oichloroethene (total)
4-M«thyl-2-pentanone
Acetone
Bhyfbenzene
Methylene Chkxide
Toluene
Trichkxoethene
VtoytcNoride
SEMIVOLATILE ORGANICS
BenzofcAdd
Acenaphthene
Anthracene
Benzo[a]anthracene
Benzo[a]pyrene
Benzotbjfluoranthene
9enzo[k]fluaranthene
B1s<2-e^hexyf)phthaiate
Butyfeenzylphtftalate
9200000
920000
5100000
10000000
10000000
380000
20000000
260000
1500
W-rvtoutyphthatate
DkHxaytphthatate
Dbenzofuran*
Ruorarthene
Ruorones ; ; w~fc
Indeno{i23cdlpyrene
Naphthatene ^-^
(ug/kg)
410000000
6100000:
31000000
2700
390
7500
7400 .
200000
20000000
. NA
10000000
'^QQQQOQ:
NA
, •• 4100000
4100000
PESnaOES/PC8S (ug/kg)
;:-.. 4100000
ND
NO
NO
9JB]b
NO
NO
6JB)b
NO
ND
NO
ND
51JJ
430 J |
460 J)
480 J |
43011
1400 JBfb
6XJJ
NO
N0-»^i
li?:^%
:..:-.-:-•••:; :'
M-*( -^.Kffh»v^
ND
SR-1-3
SR-1
3jb
7|
12 |b
82 jb
8|
16 jb
7b
SR-1-2
SR-1
931
16000
2400 JJ
2800 JJ
8400 J
7600 JJ
7800 JJ
79001
55000 Bb
3000 .
5200fv
1300 J|
»**:;l
;3700| ,;/
1100 J |
•• f, fj?f
••' '•••y'y--- -..-.v _^—^
'•"*•••'•'••.'•:. 22000^
SW-1
SW-5
SW-1
SW-1
SW-1
SW-5
SW-6A
SW-*
S\V-1
SW6
SW-6
SW-6
SW-6
SW4
SW-3
SW4
SW-1
SW-1
SW-5
SW-6
sw*
SW-6
-> SW*
SW-6
SW-10
-------
TABLE 6 (continued)
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN: DRAINAGE SWALE SEDIMENT
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN. PENNSYLVANIA
Detected
Compounds
INORGANICS (mg/kg)
Aluminum*
Arsenic
Barium*
Beryllium*
Cadmium
Calcium*
Chromium
Cobalt*
CODOOf
^^**?*frw"
Iron*
Lead
Magnesium
Mercury
Nickel
aota8slum*
Gdonhjm
Slvar
Sodium*
Vanadium
ZJnc
Risk-Based
Concentrations
(Industrial)
300000
1.6
7200
0.67
51
NA
510
NA
3800
NA
NA
NA
31
2000
NA
510
• .."siov.".
NA
720
•••"•'SUm**' -:
Maximum
Background
Concentration
22000
11
150
2.4 J
12
2600]
82
39k
70k
24000
190 j
4100
0371
58|
1700]
10
L.. W-ND--,: ' '••
4001
100J
"':--:-.250k-"--"
Sample
Location
SR-1
SR-1 -3
SR-1
SR-1
SR-1
SR-1
SR-1
SR-1-3
SR-1
SR-1
SR-1
SR-1
SR-1
SH-1
SR-1
SR-1
SR-1-3
SR-1-3
SR-1-2
SR-l
Maximum
Sample
Concentration
26000
250 1
. 200]
2.2
12
10000
130
69
110
33000
170]
4000
3.1
88|
3500
0.811]
331
430]
58k
- • 530k •"••.•>::.
Sample
! SW-*
SW-7
SW-3
SW-2
SW-4
SW-1
SW-7
SW10
SW10
SW-4
SW-2
SW-4~ SW-10
sw^t
SW.TO "
SW-4
swV
SW*
SW-1
SW-4
SW-7
aVaV IQUnOBQ CD WO lIQninCaVm n0WL
CnaVMCaVS Of pOHnHl OOn0*VTL
• GiMfniori of poiaVHtal oowoawn duo to
to Dnorte COPCfc.
kodkiQ S almM tho avnount
IWM •AfTatoattBd M ACnOfntoaal Of pOlMaM OOOOaVTI QIN tD OOfflpOrtMn vMl NQlOMI DOClCQfOUflO MM <
iU$0>om«MemMi>lorte«num • aOmgAB (PucMiBi md BoMngtn. 19H. U8QS PruliidunH Piptr 1270).
NA-Not/
ND-Notl
8-Found hi
J*M
0« Compounds•
ti YMtMi>MnftrilmntiiinTTnr11nt-Ti
iota
aVB flOt
J
lUn*.
i Urn*.
Uma,
-------
TABLE 7
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN: STORM DRAIN SEDIMENT
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN, PENNSYLVANIA
Detected
Compounds
Risk-Based
Concentrations
(Industrial)
Maximum j
Background j Sample
Concentration I Location
Maximum j
Sample j
Concentration j
Sample
Location
VOLATILE ORGANICS (ug/kg)
1.1.1-Trichtoroethane
1.2-Dichloroethene (total)
Acetone
Vinyl chloride
SEMIVOLATJLE ORGANICS
4-Metfiytphenoi
2-Methylnaphthalene
Acenaphthene
9200000
920000
10000000
1500
Anthracene
Benzo[a]anthracene
B«nzo{a]pyrane
Benzo(b]fluoranthene
Benzo[k]fluoranthene
Bb&-ethyftiexyl)pnthalate
Chrysene
Okvoctylphmaiate
Ruorarthene
Ruorene
Naphthalene
Phenanttifene
Pyrene -,-. ; - -.-
INORGANICS (mg/ko)
Aluminum
Arsenic*
Barium
BeryHum*
(ug/kg)
510000
NA
6100000
31000000
2700
390
7500
7400
200000.:
:,. ..NA -,:•:•::
2000000
4100000
4100000
4100000
3000000
3100000
3QQOOQ
14
7200
0*7
Ctfdum*
lion
NO
NO
9JBjb
NO
ND
NO
NO
51J|
430 Jj
460 J j
480 J |
430 J |
1400 JBg)
600 Jf
'^:.'ND
880 Jj
NA
«
NA
NA
NA
22000
11
150
2.4J
%-V
2600|
- 82r:
39k
70k
24000
1901
SR-1-3
SR-1-2
Sfl-t
SR-1
SR-1
SR-1
SR-1
SR-1
SR-1
SR-1
SR-1
SR-1
SR-1-3
SR-1
SR-1
Sff-t
SR-1
SR-t"-
SR-1-3
SR-t
SR-1
SR-1
7JBjb I
8| !
150J8jb
SJ
170JJ
450 J)
280 JI
270 Jj
530 JJ
460 Jf
440 Jj
390 JJ
11000 Bb
600 Jj
250 Jj
860 Jj
260 Jj
500 Jj
820 J |
870 JJ
14000
as
120k
1-SkJ
4300)
27k
19000 1
96k
NSO-1A
NSO-1A
NSO-1A
NSO-1
NSO-t
NSO-1A
NSO-1A
NSO-1A
NSO-f
NSO-1
NSO-1
NSO-1
SSO-1
NSO-1. NSO-1 A
NSO-1
NSO-1
NSO-1A
NSO-1 A
NSO-1 A
NSO-1
NSO-1. NSO-1A
NSO-1A
NSO-1
NSO-1A
SSO-1 *"
NSO-1 A
NSO-1A
NSO-1A
NSO-1A
-------
TABLE /(continued)
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN: STORM DRAIN SEDIMENT
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN. PENNSYLVANIA
Detected
Compounds
Risk-Based
Concentrations
(Industrial)
INORGANICS (mg/kg) (continued)
Magnesium
Manganese
Mercury
Nickel
Potassium
Selenium
Sodium
Thallium
Vanadium
ana-,- •;"..'
NA
10000
31
2000
NA
510
NA
7.2
720
31000
Maximum }
Background j Sample
Concentration: Location
j
4100 I SR-1
15001
0.371
56]
1700]
in
400]
1.21]
100]
250 k
SR-1-3
SR-1
SR-1
SR-1
SR-1
SR-1-3
SR-1
Sfl-1-2
SR-1
Maximum 1
Sample j Sample
Concentration | Location
I
3200 1 NSO-1
7901 ! NSO-1
Z5
45k
1600]
0.72fl
230]
0.31]
19]
420]
NSO-1A
NSO-1A
NSO-1A
NSO-1A -
SSO-1
NSO-1 -'
NSO-1
NSO-1A .-';.
M fQUnoOQ tB tMO Vpnificmt npJunM*
I Mfc*w clMnftato of potartW
• AddMonat QMndal of Potontltf Conewn K Rbk
• Not eoraUMd a chwnial of poMMW eonewn du» to
M ut«d to DMcrite COPCt.
of &A««Ntod ttxtetty
UrrtL
i Umt «d Contact ftoqidrad QuwttMton or
UhriL
-------
• TABLES
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN
SOILS OF THE UNDERGROUND STORAGE TANK FARM #4
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN. PENNSYLVANIA
Detected
Compounds
SEMIVOLAT1LE ORGANICS (u
Bb(2-ethyinexyi)pnthalate
Butyfbenzylpnthalate
DMvoctyl pnthatate
Risk-Based
Concentrations
(Industrial)
3/kQ)
200000
20000000
2000000
Maximum i
Background j Sample
Concentration I Location
•
1
I
I
630 b ! OS-1-S
160] 1 OS-1-S
NO |
Maximum i
Sample ] Sample
Concentration i Location
'
2000
2500
820000
SS-3
670A
SS-1
M reunoodto MO cJonincBnt IIQUPBC.
AntM chtcnicftb of potentW conoonx
AoQnionH Cnofnicw of PotMitwl conoocn if Hvc BAMQ Com
tratfons m uMd to OMorto COPOk
b • VUuMqualHtoddu*iopraMno*of wialytilnlhcMmptoatte
quaflflcd with b «• not eoraidwvd dMtnieal* of poiMMM oenown)
-------
'TABLE 9
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN: PLANT AREA SOILS
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN. PENNSYLVANIA
Detected
Compounds
VOLATILE ORGANICS (ug/kg)
Methytene Chloride
Toluene
1 .1 .1 -Trichloroethane
Trichtoroethene (TCE)
2-Butanone
l£Otchloroethene(totaO
Risk-Based
Concentrations
(Residential)
230000
1600000
700000
47000
390000
70000
Maximum
Background
Concentration
-
NO
2)
NO
NO
NO
NO
Sample
Location
-
OS-3-S
Maximum
Sample
Concentration
6
69
6
3900
860
3300
Sample
Location
SB-2
SB7
SB-2
SB7
SB4
SB7:
.Note
]
of potvnoii concern
-------
TABLE 10
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN
DRAINAGE SWALE AND STORM DRAIN SURFACE WATER (RUN OFF)
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN. PENNSYLVANIA
Detected
Compounds
VOLATILE ORGANICS (ug/L)
1 ,2-Otehloroethene (total)
2-Butanone
4-Methyf-2-Pentanone
Acetone
Carbon Disuffide
Metnylene Chloride
Toluene
TotaJXytenes
ncnhxownene
Vfnyt Chloride
SEMIVOLAT1LE ORGANICS (ug
BenzoteAcW
Phenol
Bb(2-etnyihexyl)phthalate
Oi-n-octyl phthalate
i
INORGANICS (mg/L)
Aluminum*
Arsenic*
Barium
Calcium*
Chromium
Copper
Iron*
Lead
Risk-Based
Concentrations
(Tap Water)
5.5
180
NA
370
2.1 -
5.4
75
1200
2.1
0.025
/U
15000
2200
6.1
- : 73 ..•;'"
11
04)00049
026
NA
0.018
au
NA
NA
MCL
70
NA
NA
NA
NA
5
1000
10000
5
' "'. 2
;•:::•' ; :"NA-- ••••>*-
'• .NA-?:..'.: . -
6
NA
NA
0.05
2
NA
0.1
1.3 (action level)
NA
04)15 (action level)
Maximum \
Background { Sample
Concentration i Location
•
NO
NO
NO
6]b
NO
NO
U|b
4Jjb
NO
NO
»;^ND-. ,-:•:
NO -.";'
SJBjb
NO
1.8J
NO
0.046]
28
NO
04)21 Q
2.1J
04)11
SR-1 -2/3
SR-1
SR-1
SR-1
SR-1
SR-1
SR-1
SR-1-2
SR-1
SR-1
Maximum i
Sample | Sample
Concentration i Location
}
2JJ I NSO-1
20
110
1000d
4JJ.
5|bn
3JB]b
2J
7
6JJ
43 J|
4J|
SOBb
*JJ
23 \
0.0074]
04)59]
33
0.0074]
04)13 1]
2411
0.0098k
SW-1
SW-1
'NSO-1
,SW-2A
;sw-i
SW-2
NSO-1A
NSO-1
SW-1
SW-1
SW-1
SW-3
SW-1
SW-3
SW-1
SW-1
SW-1
NSO-1A
SW-3
SW-3
SW-3
-------
TABLE-10 (continued)
IDENTIFICATION OF CHEMICALS OF POTENTIAL CONCERN
DRAINAGE SWALE AND STORM DRAIN SURFACE WATER (RUN OFF)
OCCIDENTAL CHEMICAL CORPORATION SITE REMEDIAL INVESTIGATION
POTTSTOWN. PENNSYLVANIA
Detected
Compounds
INORGANICS (mg/L) (continue
Magnesium*
Manganese
Nickel
Potassium*
Selenium
Thallium
ane
Risk-Based
Concentrations
(Tap Water)
i)
NA
0.37
0.073
NA
0.018
0.26
1.1
MCL
NA
NA
0.1
NA
O.OS
0.002
NA
Maximum i
Background I Sample
Concentration i Location
10
0.35
NO
3.1]
NO
NO
0.089
SR-1
SR-1
SR-1
SR-1
Maximum I
Sample I Sample
Concentrationi Location
!
12
1.1 J
0.018]
5.4
0.001 1
0.002 b]
0.29J
NSO-1
SW-t
SW-1
.SW-1
SW-1
.SW-1
6W-1.
RaaUtaaf»reundadtotwoaignMcartfl0UML
SnBohQ nttCfltcs Gnhwnidis of potvrtiM conohVix
• • MdMonal Chamtaal of PMamtt Ceneatn > PUk
* - ^eonsttOTda ctamicalofpotontw concern dM to
«• uMd to Owerib* COPCk
of &/U«^^
NO-NotOMMttd
B
J
b
and/or
ilML
RMutt quwittMad from
Un*.
I -\MiMbiaaadlov.
-------
TABLE 11
TOXK3TY ASSESSMENT SUMMARY TABLE • CARCINOGENS
CHEMICAL
WEIGHT OF
EVIDENCE
SLOPE
FACTOR (SF)
SFBASIS
(tp«ci««; «xpotura)
TYPE OF
CANCER
ORAL EXPOSURE.
AWrtn
Baiytlium
B*nso(k)fluoranth«n»
CMocoloim
4.4'^OE
ijit'OicMofortmK
i,w
Mathytana cMorida
S*yww
Triohtojoattana
VlnylCMoiWa
INHALATION EXPOSURE
Cartoon TatiacMorMa
Chlofolonn
TiicMofoathana
iflnj^^^hioooa^^
82
A
82
A
82
82
82
82
82
82
82
82
82
82
82
82
82
C
82
82
(D
0)
0)
0)
0)
0)
(1)
d)
(1)
d)
W
(t)
(D
(D
(D
(D
W
«
«
(i)
(D
(D
«
1.76+01
1.7E+00
•MTMM&3
1.15E+01
1.4&02
6.1&03
3.4&01
9.1&OB
6UJ&01
3.1602
1.1E-02
1.1&Q2
146*00
(D
(3)
(D
(2)
(D
(D
itypa)
NA
NA
NA
NA
NA
ctaaulaiofytyitwn
war
IIMQ and bcoocw
hmo
NA
lung
WHEAST
(3)AfaMieilopa
(4)VlnylcMe>k>a
tramptapoaadunttitakof 9648
(remunMiWclnHEASr
-------
TABLE 12
TQXJCITV ASS6SSM6NT SUr-Mtav »j9Lg . NONCAPC1NQGENS
CHBONIC RtO
CHEMICAL
RfO BASIS
•soeaes. eiaosurei
CONFiCENCE
LSVEi.
u.c ANC MP •
1.2 DkMoioainanaftotal)
Dlwvtoutyl phtnalata
Oietnyl phthaJata
r>n-octyi phthalat*
ORAL EXPOSURE
Acetone
Aldnn
Anthracene
Antimony
A/Mn«
9eniotc Acid
Beniyi Aiconoi
BaryiHum
Bis (2-etnythexyt) phthalata
2-Butanona (M6K)
Butyl banzyl phttialata
Cadmium
Carbon Oiaurfide
Carbon Tatfaehtorida
Chloroform
Copoar
Fhjorana
Maroury
Matftytana Chtortda
< Ma»yl 2-pantanon
«Ma»»l I
Sfcw
Tatraohtoroathana
IhaHum
Totuana
l.l.1.Tflchtoroa»am
Xylanaa
INHMAnON
1.1
tToluana
60E-02
1 OE-Oi
3.0E-05
6.0E-02
4.0E-04
1.0E-03
406*00
3.06-01
5.06-03
ZOE-02
5.06-02
2.06-01
1.06-03
1.06-01
7.06-04
1.0642
5.06-03
4.36-02
9.06-03
8.06-01
2.06-02
106-01
4.06-02
4.06-02
1.06-01
3.06-04
5.06-02
4.06-03
2-06-02
&06O1
iOE-02
1.0602
TOM
aa*TaM*3.4
in
(i)
(D
(i)
(2)
(1)
(2)
(1)
(D
(2)
(1)
(1)
(D
(1)
(D
(3)
(4)
(1)
(5)
(1)
0)
(1)
(1)
(D
(D
0)
(2)
(D
(2)
(D
(t)
(D
(2)
(1)
(9
(D
(t)
mousa: gavaga
rat: gavaga
rat: diat
mouta: gavaga
rat: drinking watar
human: d watar
human; diat
rat: gavaga
rat drinking watar
guinea pig; diat
rat inhalation
rat diat
human: NA*
rabbit inhalation
ratgavag*
dog; diat (capaukw)
rat drinking watar
human; NA
rat drinking watar
rat gavaga
rat diat
rat did
rat diat
ratgavag*
mouaa: gavaga
mouargavaga
human: diat
rat oral
rat drinking watar
rat oral
•cgiMQi
ratdtot
human: oral
ratoral
NA
NA
NA
NA
NA
ncpatotoxicity
ncpmotox. >
livar toxioty
no affacts oOsarvad
< lifaspan. blood alt.
akin cnangas
no affacts obaarvad
g.i. tract toxioty
no affacts obaarvad
incraaaad livar weight
'atotoucity
arttrad organ/body w
kidnay toxioty
fatal toxicity/malform
livar toxicrty
livar fatty cyst formati
no affacts obaarvad
gj. tract irritation
livar kniona
tow hamatocrit/name
incraasad mortality
enaaad growtt/wt
Dvar/Mdnaywt enang
liver and kidnay toxici
Mrnaiotogical cnang
SNS effects
kidnay toncriry
Uvartojdcity
Dvar and kidney toxici
tow body wt neuroto
lew body •tight gain
tow body/organ wt
>aOOTAD
NA
NA
NA
NA
NA
NA
NA
low,UF»3.000: MF.i
lOw/UF. 1.000: MF.1
mad/UF. 1.00ft MF.i
low/UF.3.000: MF.l
UF. 1.000
UF-100
madium/UF. 1; MF.l
UF> 1.000
low/UF. 10ft MF> 1
mad/UF. 1.00ft MF.i
UF.100
tew/UF. 1.00ft MF.1
hign/UF-10: MF«1
madium/UF. lOftMF. 1
mad/UF. 1.00ft MF.t
mad/UF. 1.00ft MF.l
tow/UF*50ft MF.l
NA
mad/UF-1.00ft MF.1
tow/UF. 1.00ft MF.1
tow/UF-1,00ft MF.1
UF-1.000 ?-
low/UF-1.000: MF-1
tow/UF.3,OOftMF.1
tow/UF-3.000: MF-Y
madium/UF. 1; MF.1
UF-1.000
madlum/UF-10ft MF.1
UF-1,000
UF-1.009
UF-lftOOO
UF-300
tow/UF-10ft MF-1
UF.3000.MF-1
mad/UF-IJOftMF-1
mad/UF. 1,000: MF-1
mad/UF. 1«0:MF.1
madhjm/UF-iOOiMF.l
UF-10
NA
NA
NA
NA
NA
NA
NA
•UF.Uno>rtBln»yrac*or.MF.
(DM
vQHEAIT
(3) OM WD kr HKMriant On
NA-not
W H» Oral IVb tar Coppar to
01I» Oral MFDoHad to tha
ftomac
a(l J mg/1) augui Hi rt m HBAtT
K«rnna.l.1
&1 J4)Ce«aoima/ka/dav. HEASn.
-------
TABLE 13
Inhalation Slope Factors
Adjustment of Route-to-Route Extrapolation
Compound
carbon tetrachloride
chloroform
1,1-dichloroethene
styrene
trichloroethene
vinyl chloride
Oral Slope
(IRIS/HEAST)
1/fmf/kf/datf
0.13 J
0.0061 l
0.6 »
0.03 2
0.011 2
1.9
Inhal Slope AAF
(IRIS/HEAST)
I/fag/ kf/davt
0.13 l 0.40<
0.0081 »
1.2 1 —
0.0022
0.0172 —
0^93
Inhal Slope
(Provisional)
1/fmf/Vf/dav)
0.052*
— •-
—
— . .
—
—
l IRIS
2 HEAST
3 Vinyl Chloride inhalation slope factor was obtained from conversion of inhalation unit
risk reported in HEAST.
4 ATSDR Toxicological Profiles.
5 Provisional toxirity value (see Attachment 2).
-------
TABLE 14
Derivation of Inhalation Reference Doses (RfDs)
Adjustment of Route-to-Route Extrapolation
Compound OralRfD InhalRfC AAF Inhal RfD
carbon tetrachloride
chloroform
1,1-dichloroethene .
c/t-dichloroethene
ethylbenzene
styrene
toluene
0.0007 » 0.002s
0.01 l — 0.77 3
0.009 » — 0.8 3
0.01 » 0.8s
0.1 > 1.02
0.2 l 1.0*
0^» 2.0* —
5.7X104
0.013 •
0.011 6
0.025 •
OJ
OJ
0.6
i nus
2HEAST
3 ATSDRToxicological Profiles.
4 Gerde, Pn and DahU AJl^ 1991, A model for the uptake of inhaled vapors in the nose of
the dog during cyclic breathing. ToricoL AppL PharmaooL 109,276-288.
5 Provisional toxicity vahie from ECAO.
6 Provisional toxicity value (see Attachment 2).
-------
TABLE 15
Exposure Aasasanwii Summery
OparattNMl
On*
A
Bedrock Aquifer
b
C
Earihan Lagoon
0
Unad Lagoon
Sol
E
wHflMnl
F
MOfRi OMMf
ftAdSlft^a^MaA
MVHfiVill
0
xtaffQW tVM
fi^dALMkAa^
pvukmvfii
M
USTAreaSorla
1
ptotAraa soita
A
SrtwyMNMww
8uitoo*\NMM
MtflraUon
Pathway
•undw SchuytkM
niMftoiMidwMlal
«M
•tfMtwgtto
oonuyiKiU fvv9f
•OMCnaigtlo
8ohuy(UII(«wM
NA
NA
SehuyftM Rkm
toMJI
••urfMcnmoHlo
SdMiyftMMvw
(M*JI
NA
NA
NA
NA
Potential
• Rt<«(iiorii
-future raiktontt - cdultt
•ndcMMiwt
(*MJ)
(M«J)
-on«H* woiton
-hikiraraslttonta
•OfultM WOftMCB
•wMtowofhws
— ""
•onttewortiwi
•futurararttofrt*
•oiult* woihw*
•omltowoilwra
•lutMramidMM
••whnrran.aduN*
•ndcMkfcm
. Expotui*
Point
•houMhoM UM ol
Oioundw«t«f M
chinking watm
(Indudn (howti Ing)
•'
with Mdlmvnt
-dlivct contact
wHIi Mdknant
-ctUvct contact
whli tadlmant
-dh «ct contact
with aadfcnanl
-dliact contact
with MH
•dkact contact with aott
-SchuylliWNvw
surfaca wataf
Exposure Roula
•drbthlna water Ingastion
•dwmal contact (showaiing)
-vapm Inhalation (ahowaring)
•Ingaatlon
-Ingastion
•ingastton
-bigaMkin
Ingattion
•Ingastion
inhalation
•tngasllon
•ingastlon
-daimal contact
-------
b. Chemical Exposure Pathways
In order for one of the subpopulations identified above to be
exposed to the chemicals of concern at the site a chemical
exposure pathway must be present. A pathway is the route taken
by a chemical from its source in the environment until it
contacts a receptor. Each exposure pathway must include the
following elements:
• a source and mechanism of chemical release to the environment;
• an environmental transport medium (e.g., air, ground water) for
the released chemical;
• a point of potential human contact with the contaminated medium
(referred to as.the exposure point); and
• receptor contact (e.g., ingestion of contaminated ground
water).
Exposure may occur when contaminants migrate from the Site to an
exposure point (i.e., a location where receptors can come into •»
contact with contaminants) or when a receptor comes into direct *
contact with waste or contaminated media at the Site. An
exposure pathway is complete (i.e., exposure occurs) if there is
a way for the receptor to take in contaminants through ingestion,
inhalation, or dermal absorption of contaminated media.
(3) Exposure Point Concentrations and Routes of Exposure
Potential human exposure to the contaminants at the Site was
assessed by evaluating chemical sources and receiving media,
migration pathways (fate and transport), potential human
receptors, exposure points, and exposure routes. The areas
identified as potential sources of human exposure were
characterized with respect to potential chemical migration and
exposure pathways. Four potential exposure pathways were
identified. They were:
• Residential exposure to bedrock groundwater as drinking water
The current pumping of groundwater at the Site prevents off-site
migration and any current residential exposure. Consequently,
there are no receptors under the current pumping conditions.
To assess the risk associated with residential use of the bedrock
aquifer in the future, a hypothetical scenario was developed
which assumed that the groundwater plumes as currently exist on-
site migrated unchanged to a residential veil.
Although two aquifers are present under the Site, residential
exposure with respect to drinking water is to the bedrock
56
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groundwater. only since the overburden discharges directly into
the river. .
» Swimmer exposure to Schuylkill River surface water
The swimmer exposure scenario considered discharge to the river
from both the bedrock and overburden aquifers, and from surface
water runoff from the Site.
»
• Worker exposure to on-site soils or sediments
The Site is fenced and a full-time guard is present, therefore
the site access is limited to on-site workers, trespassing is
unlikely. Access to the Site from the Schuylkill River boundary.
is also considered unlikely due to thick vegetation and steep
river banks along the property boundary. The exposure pathway is
•assumed to be incidental ingestion since most' of the site is
either vegetated or paved, which prevents fugitive dust emissions
and subsequent dust inhalation. The areas of concern with regard
to worker exposure are the soil/sediments contained in the
earthen lagoons, soils surrounding the lined lagoons, the borrow'
area soils/sediments, the drainage swale soil/sediments, the
sediments of the storm drain, and the plant area soils. In the ->
plant area where subsurface soils were found to have the highest *
volatile levels, worker exposure to the subsurface soils were
evaluated as if these buried soils were actually surface soils.
In reality, the majority of the plant area is asphalted thereby
limiting exposure.
• Residential exposure to on-site soils or sediments
Although the Site is currently an industrial facility, a future
residential exposure scenario was considered in the event that
plant ceases operation as a manufacturing facility, and the site
is re-zoned. Residential exposures were limited to the plant
area, earthen lagoons and borrow area, though the borrow area is
in the floodplain where residential exposure would be extremely
limited. The lined lagoons are undergoing closure and therefore,
will not present a future residential exposure. The storm drains
and the swale area would be inconsistent with future residential
development and would likely be relocated in a new stormwater
management plan.
(4) Toxicity Assessment Summary
The Baseline Risk Assessment addresses two general types of
toxicities which may result from chemical exposure: carcinogenic
and noncarcinogenic effects.
Noncarcinogenic effects of chemicals are assumed to display a
threshold phenomenon; i.e., effects are not observed below a
given chemical concentration (threshold dose). Therefore, a
57
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health risk is thought to exist only if established threshold
doses are exceeded. Noncarcinogenic health effects include a
variety of toxic effects on body systems, such as renal toxicity
(toxicity to the kidneys), teratogenicity (damage to the
developing fetus), and central nervous system disorders.
Reference doses ("RfDs") have been developed by EFA for
"indicating the potential for adverse health effects from exposure
to contaminant(s) of concern exhibiting noncarcinogenic effects.•
RfDs, which are expressed in units of mg/kg-day, are estimates of
lifetime daily exposure levels for humans, including sensitive
individuals. Estimates of intakes of contaminant(s) from
environmental media (e.g., the amount of a contaminant(s) of
concern ingested from contaminated drinking water, etc.) can be
compared to the RfD. RfDs are derived from human epidemiological
studies or animal studies to which uncertainty factors have been
applied (e.g., to account for the use of animal data to predict
effects on humans).
Carcinogenic effects are considered to have a dose-response
relationship with no threshold. Thus, the BRA considers that any
exposure to a carcinogen is associated with some degree of risk.
U.S. EPA has developed the scheme for the review of information v
and the classification of chemicals as to their likelihood of
causing cancer. This classification scheme distinguishes between
chemicals which are known human carcinogens (Group A) and
chemicals which are probable human carcinogens (Group B), based
on their cancer-causing properties in animal studies. The dose-
response relationship for an established or potential carcinogen
is incorporated into the slope factor ("SF"), a value expressed
in (mg/kg-day)'1, which is directly proportional to the cancer
potency of the chemical.
SF's have been developed by EPA's Carcinogenic Assessment Group
as a means of estimating excess lifetime cancer risks associated
with exposure to potentially carcinogenic contaminant(s) of
concern. SFs are multiplied by the estimated intake of a
potential carcinogen, in mg/kg-day, to provide an upper-bound
estimate of the excess lifetime cancer risk associated with
exposure at that intake level. The term "upper bound" reflects
the conservative estimate of the risks calculated from the SF.
Use of this approach makes underestimation of the actual cancer
risk highly unlikely. SF's are derived from the results of human
epidemiological studies or chronic animal bioassays to which
animal-to-human extrapolation and uncertainty factors have been
applied (e.g., to account for the use of animal data to predict
effects on humans).
The critical toxicity values (RfDs and Sfs) used- in the present
risk assessment are shown in Tables 12 through 15. EPA verified
toxicity values developed from the dose-response relationships
for carcinogens and noncarcinogens are available for use in risk
58
-------
assessment.from the EPA Integrated Risk Information System
Database (IRIS) or the EPA Health Effects Assessment Summary
Tables (HEAST). Toxicity values are most often derived from oral
dosage studies in laboratory animals. Under these circumstances
EPA generally evaluated the risk associated with the inhalation
exposure route by extrapolation from oral toxicity information
(oral RFDs and supporting studies) to predict inhalation
toxicity. Oral RFDs and SFs are available from either IRIS or
HEAST for use in risk assessment of oral and dermal exposure
routes, inhalation reference concentrations (RFCs) are not
available for all compounds of potential concern on the site.
(5) Risk Characterization Summary
A. Human Health Risks
The National Contingency Plan ("NCP") establishes acceptable
levels of carcinogenic risk for Superfund sites at between one in
ten thousand and one in one million additional cancer cases if no
cleanup actions are taken at a site. Expressed in scientific
notation, this translates to an acceptable risk range of between
1 x 10~4 and l x 10~6 over a defined period of exposure to •<-.
contaminants at a site. This means that one additional person in*
ten thousand or one additional person in a million, respectively,
could develop cancer over a defined period of exposure to
contaminants at the Site.
The baseline Risk Assessment calculates risk to humans of
contracting other, non-carcinogenic health effects from exposure
to substances associated with the Site by dividing the reasonable
maximum exposure associated with the Site by doses that are
determined by EPA to be without harmful health effects. The
ratios are added to represent exposure to multiple contaminants.
Any result of this calculation (known as the Hazard Index) which
is greater than one (1.0) is considered to present an
unacceptable risk.
When reviewing the quantitative information presented in this
section, values greater than 1 x 10"4 to l x 10"6 for
carcinogenic risk, and chronic Hazard Index values greater than
1.0 for non-carcinogenic risk, indicate the potential for adverse
health impacts.
1. Noncarcinoaenic Risk
The Hazard Index ("HI") Method is used for assessing the overall
potential f&r noncarcinogenic effects posed by the indicator
compounds. Potential concern, for noncarcinogenic effects of a
single contaminant in a single medium is expressed as the hazard
quotient ("HQ") (or the ratio of the estimated intake derived
from the contaminant concentration in a given medium to the
59
-------
contaminant's reference dose). By adding the HQs for all
contaminants within a medium or across all media to which a given
population may reasonably be exposed, the HI can be generated.
The HI provides a useful reference point for gauging the
potential significance of multiple contaminant exposures within a
single medium or across media.
Table 16 presents the .calculated Hazard Indices for the
potentially exposed populations identified. The table summarizes
the risk estimates by type of land use, area, environmental media
and routes of exposure.
An HI of 15 for adults and 35 for children were calculated for
the ingestion, inhalation, and dermal adsorption of bedrock
groundwater by an on-site resident under the future site use
scenario. An HI of 1.1 was calculated for the ingestion of
earthen lagoon soil/sediments by an on-site resident under the
future site use scenario.
2. Carcinogenic Risk
For potential carcinogens, risks are estimated as probabilities.
Excess lifetime cancer risks are determined by multiplying the -
intake level with the cancer potency slope and expressing the
result in scientific notation. An excess lifetime cancer risk of
1 x 10~6 indicates that, as a plausible upper bound, an
individual has a one in a million chance of developing cancer as
a result of site-related exposure to a carcinogen over a 70-year
lifetime under the specific exposure conditions at a site. There
are currently no significant cancer risks associated with
exposure to any areas of concern at the Site.
Under the future use scenario, an excess cancer risk of
6.2 x 10~3 was calculated for the ingestion, inhalation, and
dermal adsorption of bedrock groundwater by a potential on-site
resident.
Table 16 summarizes the calculated potential carcinogenic risk to
the potentially exposed populations for each area of the Site.
B. Environmental Risks
An Ecological Assessment was performed for the Site. It involved
wetlands delineation, plant community delineation, wildlife and
habitat surveys, and a receptor evaluation. These involved field
investigations and review of published data. However, the
ecological risk assessment did not assess the effects on
environmental receptors, especially avian receptors, from
exposure tc contaminants in the sediment basin and drainage
swale. The RI reports numerous avian species observed or
reported to potentially occur in habitats associated with the
basin and swale.
60
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TABLE 16
SUMMARY OF HUMAN RISK
Carcinogenic
2.5x10*
4.9 xUT7
NA
1.5 xW5
2.0x10*
5.1 xlO*12
9.9xlOT«
1 .Ox I(T9
6.2 xW3
2.7 xW5
1.4 xlO4
NA
HI (Adult)
1.6 XIO'3
. <*•
1.9 xlO*3
1.7x10*
1.2 KMT2
UxlO'2
1.4 XIO*2
3.9x10*
3.2x10*
15
1.2 x 10-'
1.0 xlO"4
S.4 x ID"7
HI (Child) Area
Earthen Lagoons
Borrow Area
Drainage Swale
Slorm Drain
USTArca
Plant Area
5.5x10* SchuylkiU River
35 Bedrock
Oroundwaler
1 1 Earthen 1 Jttoraii
9.6x10* Plant Area
S.OxHT* Borrow Area
Media
Soil/Sediment
Soil/Sediment
Soil/Sediment
Soils
Soils
Bedrock. Overburden
Oroundwaler Surface
Runoff
Bedrock Ground water
Soil /Sediment
Soils
Soils «
.,
Chemical Classes
(COPCsl '
dnrganics
VOCs
SVOCs
Pesticides
uwrganics
voc
dtorganics
SVOCs
VOCs
PCBs
Inorganics
SVOCs
VOCs
SVOCs
VOCs
Innrganics
VOCs
SVOCs
UMrganics
VOCs
SVOCs
bwrganica
VOCs
SVOCs
Pesticides
VOCs
i
' V VOC
=====
Population
Onsile Workers .
Onsile Workers
Onsile Workers
Onsile Workers
Onsile Workers
Onsile Workers 1
Onsile Workers
Swimmers
Residential
Residential
Residential
Residential
•
Route
digestion
digestion
digestion
digestion
digestion
Inaedi tnhalali
digestion
digestion
Dermal
digestion
Inhalation
Dermal
digestion
digestion
digestion
=====
t'uiieul/tuluic
('uiicnt/Fuliuc
Cuiiciit/Fuluic
Current/Future
Cunenl/Futuie
i Cuiicnl/Fuluic
Cuirail/Fuliue
Current/Future
I'UlUIC
I'lllUIC
llltUIC
1 HllIIC
-------
The United- States Department of Interior has reviewed this
information and has found that the sediments in the drainage
swale leading from the sedimentation basin contains high levels
of the following contaminants with the noted maximum detected
level: PAHs - 99 ppm, dibenzofurans - 1.3 ppm, mercury - 3.1 ppm,
and PCBs - .74 ppm. Though there are no sediment criteria, the
results exceed the median sediment level from bioassessment
studies for each contaminant reported in Long and Morgan (1990)
as capable of causing adverse biological effects. These
compounds (i.e. PAHs, dibenzofurans, mercury, and PCBs) when at
high environmental levels are now also implicated with adversely
affecting avian embryonic and phenotype development.
C. Significant Sources of Uncertainty
The BRA makes certain assumptions in calculating risk for the
Site.' However, as is the case with any risk assessment,
assumptions are necessary to make the best probable estimate of
risk. For example, many sources of uncertainty are inherent in
the development of EPA verified toxicity values. The uncertainty
results from the extrapolation of high-dose, short-term, animal
studies to estimate risk to chronic, low-dose exposure in humans.
Current and future exposure scenarios were assumed to be - *
applicable to potentially exposed populations. No allowance was
made for antagonistic, potentiative, or synergistic chemical
interactions in calculating the toxicity of chemicals. Each of
these assumptions have their own range of uncertainty which must
be recognized and weighed in the interpretation of the results.
D. Risk Assessment Conclusions
Current groundwater pumping at the Site is preventing the
contaminated groundwater from migrating off the site. Because
there is no current use of the groundwater as a drinking water
source the focus of the risk assessment regarding the groundwater
was to evaluate potential risks associated with future conditions
at the Site in the absence of groundwater pumping. The following
potential exposure scenarios were identified for this risk
assessment: future residential exposure to bedrock groundwater
and site soils/sediments (adult and children), future and current
worker exposure to site soil and sediments, and future and
current swimmer exposure to Schuylkill River surface water.
An unacceptable level of carcinogenic risk is presented by the
bedrock groundwater in a future land use scenario involving an
on-site resident's ingestion, inhalation and dermal contact.with
the ground water contaminants. Actual or threatened releases of
hazardous substances from this portion of the Site, if not
addressed by implementing the response action selected in this
ROD, may present a substantial endangerment to public health,
welfare, or the environment.
62
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In addition, the concentrations of the five principal chemicals
found in the groundwater during the RI exceed the allowable
levels under the Safe Drinking Water Act.
An unacceptable level of non-carcinogenic risk is presented by
the earthen lagoon soil/sediments in a future land use scenario
involving an on-site child's ingestion of soil/sediment
contaminants. Actual or threatened releases of hazardous
substances from this portion of the Site, if not addressed by
implementing the response action selected in this ROD, may
present a substantial endangerment to public health, welfare, or
the environment.
An unacceptable level of risk is presented by the Sediment Pond
and Drainage Swale sediments involving the avian species'
ingestion of contaminated sediments. Actual or threatened
releases of hazardous substances from this portion of the Site,
if not addressed by implementing the response action selected in
this ROD, may present a substantial endangerment to the
environment.
VII. SUMMARY OF REMEDIAL ALTERNATIVES
«
In accordance with Section 300.430 of the National Oil and
Hazardous Substances Pollution Contingency Plan ("NCP"), 4O
C.F.R. S 3OO.43O, a list "of remedial response actions and
representative technologies were identified and screened to
determine whether they would meet the remedial action objectives
at the Site. Those that would meet the remedial action
objectives are discussed below as Remedial Alternatives.
Section 121(d) of CERCLA requires that remedial actions at CERCLA
Sites at least attain legally applicable or relevant and
appropriate federal and State standards, requirements, criteria
and limitations which are collectively referred to as "ARARs,11
unless such ARARs are waived under CERCLA Section 121(d)(4).
Applicable requirements are those substantive environmental
protection requirements, criteria, or limitations promulgated
under federal or State law that specifically address hazardous
substances found at the Site, the remedial action to be
implemented at the Site, the location of the Site or other
circumstances present at the Site. Relevant and appropriate
requirements are those substantive environmental protection
requirements, criteria or limitations promulgated under federal
or State law which, while not applicable to the hazardous
materials found at the Site, the remedial action itself, the Site
location or other circumstances at the Site, nevertheless address
problems or ^situation sufficiently similar to those encountered
at the Site that their use is• well-suited to the Site. ARARs may
relate to the substances addressed by the remedial action
(chemical-specific), to the location of the Site (location-
63
-------
specific),. or to the manner-in which the remedial action is
implemented (action-specific).
It should be noted that all costs, time frames and
waste/treatment volumes indicated below are estimates based on
the RI/FS and the Administrative Record for this Site. This
information will be further refined for the selected remedial
alternatives during the remedial design.
SUMMARY OF REMEDIAL ALTERNATIVES FOR THE OCCIDENTAL CHEMICAL SITE
GROONDWATER
Alternative 1A - No Action/Institutional Controls
Alternative IB - Groundwater Collection Using Production Wells
and Treatment by Air Stripping
Alternative 2A - Groundwater Collection Using Recovery Wells and
Treatment by Air Stripping After the Process
Alternative 2B - Groundwater Collection Using Recovery Wells and
Treatment by Air Stripping Before the Process •*.
Alternative 3A - Groundwater Collection Using Recovery Wells and
Treatment by Steam Stripping Before the Process
Alternative 3B - Groundwater Collection Using Recovery Wells and
Treatment by Steam Stripping After the Process
EARTHEN IAQOON8
Alternative i - No Action with Deed/Land Use Restriction
Alternative 2 - On-Site Drying of PVC Layers and Landfilling of
Coal Fine Layer
Alternative 3 - Off-Site Drying of PVC Layers and Landfilling of
Coal Fine Layer
Alternative 4 - Landfilling of the Lagoon Materials
A. Remedial Alternatives for BfldxfrcK Groundwater
1. Alternative 1A - No Action/Institutional Controls
^
Major Coapcneatff of the Jaoaodial Action
The NCP requires that EPA consider a "No Action" alternative for
every site to establish a baseline for comparison to alternatives
64
-------
that do require action. Under this alternative, plant production
wells would be shut down and no groundwater would be collected
and treated. Deed/Land Use Restrictions would be placed on the
property to prevent use of groundwater. This alternative would
require OCC to collect its process water from the Schuylkill
River which would allow the contaminated groundwater to migrate
off-site to residential wells and the Schuylkill River.
Estimated capital Costs: $0
Estimated Annual OEM Costs: $0
Estimated Present-Worth Costs: $ 600
Estimated Implementation Time: Immediate
Compliance trith ARARs
There are no ARARs associated with a No Action Alternative.
2. Alternative IB - Groundvater Collection Using: Existing
Production Wells and Treatment by Air Stripping
Major Components of* the Remedied. Action
This alternative allows the present pumping scenario to continue ^.
without alteration. It is in place at the Site and would not be'
modified. Contaminated ground water is contained by using the
existing collection and treatment system at the plant to provide
process water from the existing production wells. The process
water is used for product washing and as a cooling water.
Additional chemicals from the process are introduced into the
process water and pretreatment is required before discharge. The
groundwater is treated in the existing air stripper to reduce TCE
and vinyl chloride monomer before discharge to the Pottstown
POTW. The vent gases leave the air stripping column and are
discharged directly to the atmosphere.
Estimated capital Costs: $000
Estimated Annual O&M costs: $8,380
Estimated Present-Worth costs: $ 69,000
Estimated, Implementation Time: 100 Years
Compliance vith ARARs
Contamination in the ground water is required to be reduced to
background levels by 25 PA Code SS 264.90 - 264.100, specifically
25 PA Code SS 264.90(1) and (j) and 264.100(a)(9). PADER's
February, 1992, policy document, "Ground water Quality Protection
Strategy," is to be considered in the implementation of this
remedy but Us not a ARAR. This policy document defines the
framework for ground water remediation programs in Pennsylvania.
In it, Pennsylvania-Department of Environmental Resources (PADER)
states that its goal is "nondegradation of ground water quality"
(p.l), which has been interpreted to mean that the ultimate goal
65
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of all remediation projects is to restore levels to background
quality. •
However, PADER recognizes that "there are technical and economic
limitations to immediately achieving the goal of nondegradation
for all ground waters" (pp. 1-2), and that levels above
background may not present unacceptable risk to human health and
the environment. If EPA and PADER determine that it is not
technically practicable based on performance monitoring to
achieve the background concentration for any contaminant
throughout the entire area of the ground water contamination,
then the Safe Drinking Water Act (42 U.S.C SS 300f-300j-26)
MCL for that contaminant shall be the level of contamination
which this alternative shall achieve.
The existing system in place does not comply with the ARARs
described above. The system is designed to contain the
contaminant plumes and provide process water for plant
production. It is not designed to restore groundwater to
background levels as required by 25 PA Code SS 264.90 - 264.100 .
Action-specific ARARs apply to the discharge of treated ground
water. The effluent is discharged to the Publicly Owned
Treatment Works (POTW), therefore the pretreatment regulations
are applicable under this alternative. Any surface water
discharge would comply with the substantive requirements of the
Clean Water Act National Pollution Discharge Elimination System
(NPOES) discharge regulations (40 C.F.R. SS 122.41 - 122.50 and
40 C.F.R. S 131), the Pennsylvania NPOES Regulations (25 PA Code
SS 91 and 92.31), the Pennsylvania Water Treatment Regulations
(25 PA Code SS 95.1 - 95.3 and 97) and the Pennsylvania Water
Quality Standards (25 PA Code SS 93.1 - 93.9).
As discussed above, this alternative is a description of the
existing pump and treat system. The current air stripper
discharges the vent stream to the air without emission controls.
Therefore, it does not comply with the ARARs described below.
Action-specific ARARs would also apply to the VOC emissions from
any air stripping tower. VOC emissions from an air stripping
tower would be governed by the PADER air pollution regulations.
Air Emissions would, also comply with 40 C.F.R. Part 264, Subpart
AA, and 25 PA Code Chapter 264, Subchapter AA (Standards for
Process Vents), and with 40 C.F.R. Part 264, Subpart BB, and 25
PA Code Chapter 264, Subchapter BB (Air Emissions Standards for
Equipment Leaks). Air emissions of Vinyl Chloride would comply
with 40 C.F.R. Part 61, National Emission Standards for Hazardous
Air Pollutants (NESHAPS).
Air permitting and emissions ARARs are outlined in 25 PA Code
Chapters 123, 127, 131, 135 and 139. 25 PA Code S 127.12
requires all new air emission sources to achieve minimum
attainable emissions using the best available control technology
66
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(BAT). In -addition, the PADER air permitting guidelines for
remediation projects require all air stripping and vapor
extraction units to include emission control equipment.
OSWER Directive 9355.0-28 - Control of Air Emissions from
Superfund Air Strippers at Superfund Ground water Sites although
not an action-specific ARAR, is to be considered for any air
stripper used in this remedy.
3. Alternative 2A - Groundwater Collection Using Recovery Walls
and Treatment by Air Stripping (vith Vapor Phase Carbon
Adsorption) Before the Process
Major Components of the Remedial Action
This groundwater pumping and treatment alternative is designed to
optimize well locations and recovery rates. It prevents migration
of the five contaminant plumes and removes the contaminants from
the saturated zone. Groundwater would be extracted by controlled
pumping to prevent mixing of the plumes. Occidental used a mode'l
to estimate that ground water would be extracted at a pumping ;
rate of approximately 335 gallons per minute and treated above ^
ground by Air Stripping. However, exact pumping rates and *-
configurations will be determined during remedial design subject
to approval by EPA in consultation with PADER and the Delaware
River Basin Commission (DRBC). Air stripping would remove the
volatile organics (TCE, trans-l,2,DCE, VCM, styrene,
ethylbenzene) from the groundwater and the vapor-phase carbon
adsorption unit would remove the volatiles from the air stream.
The carbon unit when "saturated" by the contaminants shall be
regenerated on-site. In carbon regeneration, the carbon is
heated in a kiln-like apparatus to "release" the contaminants
from the carbon, the "regenerated" carbon is then available for
re-use. The majority of the contaminants that adsorb onto the
carbon are destroyed in the regeneration. However, any residual
contaminants trapped in the kiln pollution control device must be
further treated/disposed and shall be handled as a RCRA hazardous
waste.
The treated groundwater would be used in Occidental's current PVC
production process. Once the volatile organics are removed by
the air stripper, the ground water would undergo additional
treatment before discharge either to the Pottstown Publicly owned
Treatment Works (POTW) or the SchuylXill River.
Estimated Capital Costs: $1,400,000
Estimated Annual O&M Costs: $ 340,000
Estimated Preseat-Wortn costs* $ 7,100,000
Estimated Implementation Time: 100 Years
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Compliance.with ARARs
Contamination in the ground water is required to be reduced to
background levels by 25 PA Code §5 264.90 - 264.100, specifically
25 PA Code SS 264.90(i) and (j) and 264.100(a)(9). PADER's
February, 1992, policy document, "Ground water Quality Protection
Strategy," although not an ARAR, would be considered in the
implementation of this remedy. This policy document defines the
framework for ground water remediation programs in Pennsylvania.
In it, Pennsylvania Department of Environmental Resources (PADER)
states that its goal is "nondegradation of ground water quality"
(p.l), which has been interpreted to mean that the ultimate goal
of all remediation projects is to restore levels to background
quality.
However, PADER recognizes that "there are technical and economic
limitations to immediately achieving the goal of nondegradation
for all ground waters" (pp. 1-2), and that levels above
background may not present unacceptable risk to human health and
the environment. If EPA and PADER determine that it is not
technically practicable based on performance monitoring to
achieve the background concentration for any contaminant
throughout the entire area of the ground water contamination, • •«-.
then the Safe Drinking Water Act (42 O.S.C SS 300f-300j-26) the '
less restrictive MCL for that contaminant shall be the level of
contamination which this alternative shall achieve.
Action-specific ARARs would apply to the discharge of treated
ground water. Depending on the method of.effluent discharge from
the ground water treatment system, applicable NPOES or Publicly
Owned Treatment Works ("POTW") pretreatment regulations would
apply. Any surface water discharge would comply with the
substantive requirements of the Clean Water Act NPDES discharge
regulations (40 C.F.R. SS 122.41 - 122.50 and 40 C.F.R. S 131),
the Pennsylvania NPDES Regulations (25 PA Code SS 91 and 92.31),
the Pennsylvania Water Treatment Regulations (25 PA Code SS
95.1 - 95.3 and 97) and the Pennsylvania Water Quality Standards
(25 PA Code SS 93.1 - 93.9).
Action-specific ARARs would apply to the treatment of a hazardous
waste. The ground water collection and treatment operations will
constitute treatment of hazardous waste. The ground water
contains listed hazardous wastes. Treatment may result in the
generation of contaminated treatment residuals. The remedy to be
implemented will comply with the applicable requirements of 25 PA
Code Part 262 Subparts A (relating to hazardous waste
determination and identification numbers), B (relating to
manifesting* requirements for Off-site shipments of spent carbon
or other hazardous wastes), C (relating to transporters of
hazardous waste), and with respect to operations at the site
generally, with the substantive requirements of 25 PA Code 264
Subparts B-D, I (in the event that hazardous waste generated as
68
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part of the remedy is manage'd in containers), j (in the event
that hazardous waste is managed, treated or stored in tanks).
The Site ground water is above the TCE level (500 ppb) that
qualifies for handling groundwater as a hazardous waste as
specified in 25 PA Code Chapter 261 Subchapter C and 40 C.F.R. $
261.24.
Action-specific ARARs would also apply to the VOC emissions from
any air stripping tower. VOC emissions from an air stripping
tower would be governed by the FADER air pollution.regulations.
Air Emissions would also comply with 40 C.F.R. Part 264, Subpart
AA, and 25 PA Code Chapter 264, Subchapter AA (Standards for
Process Vents), and with 40 C.F.R. Part 264, Subpart BB, and 25
PA Code Chapter 264, Subchapter BB (Air Emissions Standards for
Equipment Leaks). Air emissions of Vinyl Chloride would comply
with 40 C.F.R. Part 61, National Emission Standards for Hazardous
Air Pollutants (NESHAPS).
Air permitting and emissions ARARs are outlined in 25 PA Code
Chapters 123, 127, 131, 135 and 139. 25 PA Code S 127.12
requires all new air emission sources to achieve minimum
attainable emissions using the best available control technology "
(BAT). In addition, the PADER air permitting guidelines for
remediation projects require all air stripping and vapor
extraction units to include emission control equipment.
OSWER Directive 9355.0-28 - Control of Air Emissions from
Superfund Air Strippers at Superfund Ground water Sites although
not an action-specific ARAR, is to be considered for any air
stripper used in this remedy.
The on-site carbon regeneration is subject to the substantive
requirements of a Hazardous Waste Permit in Pennsylvania (23 PB
422) under 25 PA Code S 265.431.
Fugitive dust emissions generated during remedial activities
would be controlled in order to comply with fugitive dust
regulations in the federally-approved State Implementation Plan
for the Commonwealth of Pennsylvania, 40 C.F.R. Part 52, Subpart
NM, SS 52.2020 - 52.2023, and 25 PA Code S 123.2, and the
National Ambient Air Quality Standards for particulate matter in
40 C.F.R. S 50.6 and 25 PA Code SS 131.2 and 131.3.
This Alternative will comply with 25 PA Code Chapter 264,
Subchapter F, S 264.97, regarding ground water monitoring.
This Alternative will comply with regulations concerning well
drilling as set forth in 25 PA Code Chapter 107. These
regulations are established pursuant to the Water Well Drillers
License Act, 32 P.S. S 645.1 e£ seq.
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This Alternative would comply with the Delaware River Basin
Commission Ground Water Protected Area Regulations regarding
construction of water extraction wells (No. (6) (f); Water Code
of the Basin, Section 2.50.2), metering of surface water intakes
(No. 9; Water Code of the Basin, Section 2.50.2), non-
interference with domestic or other existing wells (No. 10) and
non-impact on ground water levels, ground water storage capacity,
or low flows of perennial streams (No. 4; Water Code of the
Basin, Section 2.20.4).
The substantive requirements of the Delaware River Basin
Commission (18 C.F.R. Part 430) are applicable. These
regulations establish requirements for the extraction of
groundwater within the Delaware River Basin.
4. Alternative 2B - Qroundwater Collection Using Recovery Walls
and Treatment by Air Stripping (with Vapor-Phase carbon
Adsorption! After the Process
Major Components of the Remedial Action
This alternative is identical to that described in Alternative 2A
with the exception that Occidental's estimate of ground water -.
pumping to be at a rate of approximately 620 gallons per minute -
(gpm) to an Air Stripper located after the PVC Production
Process. The 620 gpm is a combination flow from the remediation
recovery wells and additional production wells which would be
providing water to Occidental's process operations. However,
exact pumping rates and configurations would be determined during
remedial design subject to approval by EPA in consultation with
PADER and the DRBC. The air stripper unit for this alternative
is designed to handle a larger flow than alternative 2A. Once
the volatile organics are removed by the air stripper, the ground
water would undergo additional treatment before discharge either
to the Pottstown POTW or the Schuylkill River.
Estimated Capital Costsi $ 1,600,000
Estimated Annual OUI Costs: $ 430,000
Estimated Present-Worth Costst $ 8,700,000
Estimated Implementation Tim*: 100 Years
Compliance with ARARa
The ARARs discussed above under Alternative 2A will be complied
with under Alternative 2B.
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5. Alternative 3A - flroundvatfti- collection Pa ing Recovery w«ii«
and Treatment by Steam Stripping Before the Process
Major Components of the Remedial Action
This groundwater pumping and treatment alternative is similar to
Alternative 2A with the exception that the volatile organics
would be removed using Steam Stripping. As described in
Alternative 2A, this option also optimizes well locations and
recovery rates. It prevents migration of the five contaminant
plumes and removes the contaminants from the saturated zone.
Groundwater would be extracted by controlled pumping to prevent
mixing of the individual contaminant plumes. The groundwater
would be extracted at a pumping rate of approximately 335 gallons
per minute and treated above ground by Steam Stripping. However,
exact_pumping rates and configurations will be determined during
remedial design, subject to approval by EPA in consultation with
PADER and the Delaware River Basin Commission (DRBC). Steam
Stripping would remove the volatile organics from the
groundwater. The volatile organics that are removed during steam
stripping would enter a condenser which would require off-site "
disposal. The Steam Stripper would be located before any
production process, including Occidental's current PVC production*-.
process. Once the volatile organics are removed, the ground
water would undergo additional treatment before discharge to
either the Pottstown POTW or the Schuylkill River. Schuylkill
River.
Estimated capital Coats: $ 1,400,000
Estimated Annual OUC Costs* $ 560,000
Estimated Present-Worth Costst $ 11,000,000
Estimated Implementation Time: 100 Years
Compliance with ARARs
The ARARs discussed above under Alternative 2A will be complied
with under Alternative 3A.
6. Alternative 3B ••• Qro^Tidirater Collection Using Recovery Wells
and Treatment bv 8tessi Stripping After the Process
Major Components of the Somttdinl Action
This alternative is identical to that described in Alternative 3A
with the exception that the groundwater would be pumped at a rate
of approximately 620 gpm to the Steaa Stripper which is located
after the PVC Production Process. However, exact pumping rates
and configurations will be determined during remedial design
subject to approval by EPA in consultation with PADER and the
DRBC. steam Stripping would remove the volatile organics from
the groundwater. The volatile organics that are removed during
steam stripping would enter a condenser which would require of f-
71
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site disposal. Once the volatile organics are removed, the
groundwater would undergo additional treatment before discharge
either to the Pottstown POTW or the Schuylkill River.
Estimated Capital Costs: $ 1,800,000
Estimated Annual O&M Costs: $ 715,000
Estimated Present-Worth Costs: 9 13,470,000
Estimated Implementation Time: 100 Years
»_.
Compliance with ARARs
The ARARs discussed above under Alternative 3A would also apply-
to Alternative 3B.
B. Remedial Alternatives for the Earthen Lagoons
1. Alternative 1 - No Action/Institutional Controls
Major Components of the Remedial Action
The NCP requires that EPA consider a "No Action" alternative for*
every site to establish a baseline for comparison to alternatives
that do require action, tinder this alternative the lagoons would*..
be left in place and deed restrictions would be placed on the
area to prevent use of the soils.
Estimated Capital Costss $0
Estimated Annual out Costs: $0
Estimated Present-Worth Costs: $ 600
Estimated Implementation Time: Immediate
Compliance with ARARa
There are no ARARs associated with a No Action Alternative.
2* Alternative 2 — on-site Drying of PVC Layers and Landfillina
ot the Coal Fines Tiaver
Major Components of the Remedial Action
This alternative provides for on-site drying of the white and
gray PVC layers of the earthen lagoons and landfilling of the
coal fines layer. This alternative requires that an access road
be constructed to the lagoons. The layers will be dried in an
on-site dryer and the vapors from the dryer will be treated to
reduce VOC emissions prior to discharge. Appropriate portions,
of the PVC layers of reclaimed material will be marketed as
reclaimed product, and the coal fines layer, contaminated soil,
or residuals-will be transported off-site to an appropriate
disposal facility. *>
This alternative includes a post-excavation sampling program to
72
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document complete removal of the chemicals of concern outlined in
Table 3 to background concentrations.
Estimated Capital Costs: $3,847,000
Estimated Annual O & M Costs: $63,000
Estimated Present worth costs: $4,019,000
Estimated Implementation Time: 3 Years
Compliance with ARARs
This alternative would comply with the following ARARs:
Pennsylvania Clean Streams Law establishes an enforceable law
intended to reclaim and restore polluted streams through water
quality control. Flooding of the earthen lagoons may be
considered discharge of industrial materials into a receiving
water body under this law.
On-site treatment (recycling), storage will comply with RCRA
regulations 40 C.F.R. Part 264 and standards for owners and
operators of hazardous waste treatment, storage and disposal
facilities. It will also comply with 25 PA Code Chapter 264.
* ^
Determinations about the effectiveness of any soil remediation at
the Site shall be compared with EPA document no. 230/02-89-042,
Methods for Evaluating Cleanup Standards. Vol. I; Soils and
Solid Media, although not an ARAR for the Site, this document
shall be considered.
Regulations of activities affecting waters of the U.S. require
that activities being conducted on waters of the United States,
including wetlands, should first avoid impacts to Waters of the
U.S., and then minimize impacts. All unavoidable impacts to such
areas will require restoration and mitigation to compensate for
all function and values lost by implementing the remedial action,
including the time for the mitigation to become fully effective.
Pennsylvania Air Pollution Control Regulations PA Code Title 25,
Chapter 212 through 293 govern air emissions from remedial
actions and provide for the control of air pollutants and
guidance for the design and operations of air pollution sources.
Air emissions may occur during excavation and drying of earthen
lagoon materials.
Pennsylvania Erosion Control Regulations PA Code Title 25,
Chapter 102 apply to excavation and activities to control
erosion. ^
Pennsylvania Stormwater Management Act of-October 4, 1978
regulates migration of stormwater from industrial sites either as
point or non-point sources, which may be applicable during
excavation of the earthen lagoons.
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3. Alternative 3 - Off-Site Prvino of PVC Layara and Landfillinq
of Coal Fines Laver
Major Components of the Remedial Action
This alternative provides for off-site drying of the white and
gray PVC layers and the landfilling of the coal fines layer. The
alternative requires building an access road to the lagoons,
excavating each of the layers of material, transporting the PVC
layers to an off-site dryer, where it is dried, bagged, packaged
and transported back to OCC for marketing as reclaimed product.
The coal fines layer and any contaminated soil will be
transported to an appropriate off-site disposal facility.
This alternative includes a post-excavation sampling program to
document complete removal of the chemicals of concern outlined in
Table 3 to background concentrations.
Estimated Capital Coats: $5,900,000
Estimated Mutual O & M Costa: $8,640
Estimated Prasaat worth costs: $5,915,000
Estimated Implementation Time: 2 Years .-: „
Compliance vith JUUUts
The ARARs discussed above under Alternative 2 would also be
complied with under Alternative 3.
4. Alternative 4 - Landfillino of the Lagoon Materials
Major Components of the Remedial Action
This alternative provides for landfilling of all material in the
earthen lagoons. This alternative requires that an'access road
be built to the earthen lagoons area, and that all of the
material is excavated from the lagoons and is transported for
disposal off-site at an appropriate landfill. This estimate is
based on disposal in a non-hazardous landfill. However, disposal
in a hazardous landfill would still be a possibility.
This alternative includes a post-excavation sampling program to
document complete removal of the chemicals of concern outlined in
Table 3 to background concentrations.
Estimated Capital Costs* $S,3«»,»32
Estimated Annual o i M Costss $2,«tO
Estimated Present Worth Costs: $5,3*4,000
Estimated Implementation Times 2 Tears
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Compliance with ARARs
The ARARs discussed above under Alternative 2 would also be
complied with under Alternative 4.
VIII. SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES
The remedial action Alternatives described above for each area of
the Site were evaluated under the nine evaluation criteria set
forth in the NCP at 40 C.F.R. § 300.430(e)(9). These nine
criteria are organized according to the following categories
listed in 40 C.F.R. § 300.430(f)(1):
Threshold Criteria
• Overall protection of human health and the environment
• Compliance with applicable or relevant and appropriate
requirements (ARARs)
Primary Balancing Criteria
Long-term effectiveness and permanence
Reduction of toxicity, mobility, or volume through
treatment
Short-term effectiveness
Implementability
Cost
Modifying Criteria
• Community acceptance
• State acceptance
Threshold criteria must be satisfied in order for an Alternative
to be eligible for selection. Primary balancing criteria are
used to weigh the strengths and weaknesses of the Alternatives
and to identify the Alternative which provides the best balance
of the criteria. State and community acceptance are modifying
criteria which are taken into account after public comment is
received on the Proposed Plan. Descriptions of the individual
criteria follow:
overall Protection of Human Health and the Environment. Overall
protection of human health and the environment addresses whether
each alternative provides adequate protection of human health and
environment and describes how risks posed through each exposure
pathway are eliminated, reduced, or controlled, though treatment,
engineering controls and/or institutional controls.
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Compliance with Applicable or Relevant and Appropriate
Requirements. Compliance with ARARs addresses whether, a remedy
will meet all of the applicable or relevant and appropriate
requirements of other federal and state environmental statutes
for any hazardous substances left on-site or whether it provides
a basis for invoking a waiver.
Long-Term Effectiveness and Permanence. Long-term effectiveness
and permanence refers to expected residual risk and the ability
of a remedy to maintain its effectiveness over time. It includes
the consideration of residual risk and the adequacy and
reliability of controls.
Reduction of Toxicity, Mobility, ana Volume. Reduction of
toxicity, mobility, or volume through treatment refers to the
anticipated performance of the treatment technologies a remedy
may employ.
Short-Term Effectiveness. Short-term effectiveness refers to the
period of time needed to complete the remedy and any adverse
impacts on human health and the environment that may be posed
during the construction and implementation of the remedy until
cleanup levels are achieved. ' ^.
Impleaentability. Implementability refers to the technical and
administrative feasibility of a remedy, including the
availability of materials and services needed to implement that
remedy.
Cost. Cost includes estimated capital, operation and
maintenance, and net present worth costs.
Coaaunity Acceptance. Community acceptance addresses whether or
not the public agrees with the Preferred Remedial Alternative.
This is assessed in the Record of Decision following a review of
the public comments received on the Administrative Record and the
Proposed Plan.
State Acceptance. State acceptance addresses whether the State
concurs with, opposes, or has no comment on the Preferred
Remedial Alternative.
A.
&mr.vaTfl of iT.Tiram'i'
overall Protections Since Alternative 1A (Mo Action) would
neither eliminate nor reduce to acceptable levels the threats to
human health or the environment presented by contamination at the
Site, it is unacceptable and therefore, it will not: be^discussed
in the remainder of this analysis.
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Alternative IB - (Production ,Wells & Treatment by Air Stripping
with Carbon Adsorption) prevents direct contact with the
contaminated ground water by collecting groundwater and treating
volatile organics and it prevents groundwater impact on surface
water. However, it does not optimize collection of chemicals
from the bedrock aquifer because the pumping system was designed
to provide process water, not remediate the groundwater. It also
does not minimize the discharge of volatile organics to the air
because the air stripper is designed to operate without VOC
controls. Therefore, this alternative is not considered
protective of human health and the environment and will not be
discussed in the remainder of this analysis.
Alternative 2A (Recovery Wells & Treatment by Air Stripping (with
Carbon Absorption) Before Process) - adequately protects human
health and the environment by collecting groundwater and treating
it to background concentrations and eliminates air discharges of
VOCs. It protects the environment because it minimizes waste
streams to be disposed during remediation and prevents
contaminated groundwater from migrating off-site.
Alternative 2B (Recovery Wells with Air Stripper After Process) -
adequately protects human health and the environment by •*
collecting groundwater and treating volatile organics to
background concentrations and eliminates air discharges of VOCs.
It protects the environment because it minimizes waste streams to
be disposed during remediation and prevents contaminated
groundwater from migrating off-site.
Alternative 3A (Recovery Wells with Steam Stripper Before
Process) - adequately protects human health and the environment
by collecting groundwater and treating volatile organics to
background concentrations and eliminates air discharges of VOCs.
It protects the environment because it minimizes waste streams to
be disposed during remediation and prevents contaminated
groundwater from migrating off-site.
Alternative 3B (Recovery Wells with Steam Stripper After Process)
- adequately protects human health and the environment by
collecting groundwater and treating volatile organics to
background concentrations and eliminates air discharges of VOCs.
It protects the environment because it minimizes waste streams to
be disposed during remediation and prevents contaminated
groundwater from migrating off-site.
Compliance vito ARARss Levels of volatile organics in the
groundwater are in excess of Safe Drinking Water Act Maximum
Contaminant* Levels (MCLs). The goal of the groundwater remedy
for the Site-is to restore the- quality of groundwater to comply
with Pennsylvania ARARs of background quality. EPA believes that
Alternatives 2A through 3B can meet the Pennsylvania ARARs as
well as all other ARARs associated with Alternatives 2A through
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3B. . .
Long Term Effectiveness and Permanence: Alternatives 2A through
3B would likely reduce risk to acceptable levels under the future
use scenario. Alternatives 2A through 3B are effective in the
long-term because of the conservative design of the treatment
system, which can handle fluctuations of concentrations of
chemicals in groundwater and dynamic discharge regulations.
Groundwater monitoring is to be conducted to document the
progress of remediation. Table 17 displays the results of
groundwater modeling performed at the OCC Site. It shows that
the five volatile plumes will be significantly reduced within the
first 25 years. It predicts that after 50 years of pump and
treat the only detectable chemical remaining is TCE. At the end
of remediation, the concentration of TCE remaining in the
groundwater is expected to be below MCLs.
However, Occidental developed Alternatives 2A and 3A to take
place before the production process while Alternatives 2B and 3B
take place after the process. The production process at the Site
is irrelevant to the selected remedy. The remedial action at the
Site should be implemented irrespective of whether Occidental's
current process, continues, is modified, or ceases. Therefore,
EPA prefers Alternative 2A and 3A over 2B and 3B because they are
independent of the production process.
Reduction of Toxicity, Mobility/ or Volume through Treatment:,
Alternatives 2A and 2B also reduce the VOCs in the groundwater at
the OCC Site. However, Alternatives 2A and 2B provide an
efficient remediation program that does not cause cross-migration
of the individual chemical plumes or vertical migration of.the
plumes. Once the groundwater is processed through the air
stripper, the VOCs are removed and sent to a vapor-phase carbon
unit for absorption of volatile organics. The volatile organics
adsorb onto the carbon bed. An on-site carbon regeneration
system employs activated carbon to destroy the majority of the
volatile organics.
Alternatives 3A and 3B also reduce the VOCs in the groundwater at
the OCC Site. Alternatives 3A and 3B provide an efficient
remediation program that does not cause cross-migration of the
individual chemical plumes. Once the groundwater is processed
through the steam stripper and the VOCs are removed from the
groundwater, the steam and organic vapors enter a condenser which
separates out the organics for off-site disposal. Although off-
site disposal is required for the organics there is a reduction
in the volume of the organics.
V
short Term Effectiveness:. The risk associated with the current
groundwater use scenario was not calculated during the
Feasibility Study since there is no migration of the
contamination or current use of the contaminated groundwater.
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TABLE 17 : RESIDUAL RISKS AT 25 YEAR INTERVALS
TCE (ug/l)
trans-1,2-DCE
VCM
Ethyibenzene
Styrene
Residual rtsK
25 Years
148
ND
ND
ND
17
7.26-5
50 Years
43
ND
ND
ND
ND
1.86-5
75 Years
13
ND
ND
ND
ND
5.56-6
100 Years
4.1
ND
ND
ND
ND
1.76-6
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Drinking water wells in the area are not affected by the
groundwater contamination from the OCC Site. Remedial
construction workers would be exposed to volatile emissions
during any well and pipe installation activities associated with
OCC Alternatives 2A through 3B.
Implementability: Alternatives 2A through 3B are proven
technologies that have been implemented in numerous CERCLA RODS.
Costs: Of the Alternatives containing remedial action, OCC
Alternative 2A - Groundwater Collection Using Recovery Wells and
Treatment by Air Stripping Before the Process, the preferred
alternative, has the lowest net present worth and complies with
the ARARs.
Community Acceptance: The April 1993 Proposed Plan and the May 4,
1993 public meeting produced comments from the general public,
local officials, and potentially responsible parties (PRPs) for
the Site. Responses to these comments appear in the
Responsiveness Summary section of this ROD.
State Acceptance: The Commonwealth of Pennsylvania has concurred
with the selection of Alternative 2A as the remedy for this
portion of the Site.
B. COMPARATIVE ANALYSIS FOR EARTHEN LAGOONS
Overall Protection: Alternative 1 - No Action would not eliminate
or reduce the threats to human health and the environment
presented by the contamination at the earthen lagoons. It is riot
protective of human health and the environment and therefore,
will not be discussed in the remainder of this analysis.
Alternative 2 and 3 is considered to be more protective than
Alternative 4 because recycling of the majority of the lagoon
materials occurs under these alternatives.
Compliance with ARARS: Alternatives 2, 3, and 4 will comply with
applicable or both relevant and appropriate Federal and State
environmental regulations.
Long Term Effectiveness and Permanence: Alternatives 2, 3, and 4
provide long term effectiveness and permanence. Additional long
term effectiveness and permanence is provided by Alternatives 2
and 3 as compared with Alternative 4 because Alternatives 2 and 3
minimize the amount of material that is landfilled.
Reduction of Toxicity, Mobility or Volume through Treatment:
Alternative^ 2 and 3 reduce mobility and volume by recycling the
majority of lagoon materials. Alternative 4 reduces mobility of
the lagoon materials by placement into a secure landfill but does
not reduce volume.
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Short Term Effectiveness: Alternative 4 provides more short term
effectiveness than Alternatives 2 and 3 because it is proposed to
take less time than either alternative. Alternatives 3 and 4
require less time for design and installation of remediation
equipment than Alternative 2. Worker health and safety will be
protected under all alternatives by use of engineering controls
and, if necessary, personal protective equipment.
Implementability: Each of the alternatives is implementable.
Alternative 2 is anticipated to be more complicated to implement
because equipment has to be designed and installed for operation.
Alternatives 3 and 4 require material loading, transport off-
site, and backfilling activities. Disposal and reclamation
activities occur off-site with Alternatives 3 and 4.
Costs: The lowest cost is associated with Alternative 2, followed
by Alternative 4. Alternative 3 is the most costly. However,
costs estimated for Alternative 4 were based on disposal as a
non-hazardous waste. Additional sampling would be required to
evaluate appropriate disposal options.
Community Acceptance: The April 1993 Proposed Plan and the May 4,
1993 public meeting produced comments from the general public,
local officials, and potentially responsible parties (PRPs) for
the Site. Responses to these comments appear in the
Responsiveness Summary section of this ROD.
State Acceptance: The Commonwealth of Pennsylvania has concurred
with the selection of Alternative 2 as the remedy for this
portion of the Site.
IX. THE SELECTED REMEDY AMD PERFORMANCE STANDARDS
A. General Description of the Selected Groundvater Remedy
Following review and consideration of the information in the
Administrative Record file, the requirements of CERCLA and the
NCP, and public comment, EPA has selected Alternative 2A
(Groundwater Collection Using Recovery Wells and Treatment by Air
Stripping (with Vapor Phase Carbon Adsorption) Before the
Process) for the treatment of the bedrock groundwater.
Alternative 2A meets the threshold criteria of overall protection
of human health and the environment and compliance with ARARs,
and provides the best balance of long term effectiveness,
reductions of toxicity, mobility and volume of contaminants
through treatment, short term effectiveness, implementability and
cost.
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The selected remedy consist^ of the following components:
* Installation, operation and maintenance of groundwater
extraction wells to remove contaminated groundwater from beneath
the Site and to prevent contaminants from migrating further;
* Installation, operation, and maintenance of air stripper
to treat groundwater to the required levels;
• Installation, operation, and maintenance of vapor phase
carbon unit on air stripper;
• Periodic sampling of groundwater and treated water to ensure
that treatment components are effective and that groundwater
remediation is progressing towards the cleanup goals; and
• Each component of the selected remedy and its performance
standard(s) is described in detail in Section C, below.
PERFORMANCE STANDARDS "
(1) Groundvater Extraction and Treatment system
(a) Ground water Extraction System
Contaminated ground water shall be extracted using multiple
wells, the exact location, pumping rate, and number of which
shall be determined during the remedial design, and shall be
approved by EPA in consultation with PADER and DRBC. The system
shall be designed to capture contaminated groundwater throughout
the plume. The plume is defined as the ground water which
contains contaminants of concern above their background
concentrations. (See Table 19) The effectiveness of the system
to capture contaminated ground water shall be carefully
monitored,'and modifications that may be required during its
operation may include, but are not limited to, any or all of the
following:
• alternating pumping at wells to eliminate stagnation
points, i.e., those areas between extraction wells where the
ground water may not be captured effectively;
• pulse pumping to allow equilibration of the ground water
system and to encourage adsorbed contaminants to partition into
ground water; and
• installation of additional extraction wells as necessary
to capture the contaminated ground water and/or to facilitate or
accelerate the removal of contaminants from the ground water.
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(b) tsroundwater Cleanup Levels
The well system for extracting groundwater shall be operated
until the Performance Standard for each contaminant of concern is
met and maintained throughout the entire plume of contamination
for a period of 12 consecutive quarters. The plume is defined as
the ground water which contains contaminants of concern above
their background concentrations. (See Table 18) The Performance
Standard for each contaminant of concern in the groundwater shall
be the MCL for that contaminant (the federal ARAR for public
drinking water supplies under the Safe Drinking Water Act) or the
background concentration of that contaminant (the Pennsylvania
ARAR under 25 Pa. Code §§264.90-264.100), whichever is lower.
The background concentration for each contaminant of concern
shall be determined by EPA in consultation with PAOER during the
Remedial Design in accordance with the procedures for groundwater
monitoring outlined in 25 Pa. Code §264.97. Determination of
background concentrations shall not delay implementation of the
remedy. In the event that a contaminant of concern is not
detected in samples taken for the determination of background
concentrations, the method detection limits of drinking water
analytical methods with respect to that contaminant of concern
shall constitute the "background" concentration of the
contaminant.
The MCLs for all of the contaminants of concern are set forth at
40 C.F.R. § 141.61 (July 1, 1992 ed. including amendments set
forth therein). The MCLs, the detection limits and the
appropriate analytical methods for testing for the contaminants
of concern are listed in Table 18.
(c) Air Stripper and Vapor Phase Carbon Units
The recovered groundwater shall be treated using packed or tray
column air stripping units and vapor phase carbon units. The
Performance Standard for the air emissions from the air
stripping units shall be the requirements of the RCRA regulations
set forth at 40 C.F.R. Part 264, Subpart AA - Air Emission
Standards for Process Vents.
The total organic emissions from all affected process vents at
the Site shall be below 1.4 kg/hr (3 Ibs/hr) and 2800 kg/yr (3.1
tons/yr) under this regulation. Any vinyl chloride air emissions
from the groundwater treatment units will comply with Section 112
of the Clean Air Act, 42 U.S.C. §7412, National Emission Standard
For Hazardous Air Pollutants (NESHAPs). The relevant and
appropriate NESHAP for vinyl chloride is set forth at 40 C.F.R.
Part 61, Subpart F. The air emissions will also comply with the
Commonwealth* of Pennsylvania regulations set forth at 25 Pa.
Code, Chapter 127, Subchapter A. Those regulations require that
emissions be reduced to the minimum obtainable levels through the
use of best available technology, as defined in 25 Pa. Code
§121.1.
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The on-site regeneration is subject to the substantive
requirements of a Hazardous Waste Permit in Pennsylvania under 25
PA Code § 265.431.
,(d) Discharge of Treated Water
Two discharge options are considered implementable, they are POTW
discharge or surface water discharge.
POTW Discharge:
If the treated well water is utilized in the production process,
any volatile materials introduced into the remediated well water
as it passes through the productions process shall require
pretreatment to meet the indirect discharge limits of the POTW.
Surface Water Discharge:
As an alternative, the effluent may be directly discharged to the
Schuylkill River. The treated effluent discharged to the
Schuylkill River shall meet the substantive discharge
requirements of the NPDES program under the Clean Water Act, and
shall comply with discharge rates established by EPA in
consultation with PADER and DRBC. •
(e) Periodic Monitoring and System shutdown
A long-term groundwater monitoring program shall be .
implemented to evaluate the effectiveness of the groundwater
pumping and treatment system throughout the entire plume.
Numbers and locations of these monitoring wells shall be approved
by EPA during the remedial design, in consultation with the
PADER. The wells shall be sampled quarterly for the first three
years and semi-annually thereafter until the levels of
contaminants of concern in these wells have reached background
levels as established by EPA, in consultation with PADER during
the Remedial Design, or MCLs whichever is lower. Once these
required levels have been reached, the wells shall be sampled for
twelve consecutive quarters throughout the entire plume and if
contaminants remain at or below these required levels, the
operation of the extraction system may be shut down.
Semi-annual monitoring of the groundwater shall continue for
five years after the system is shut down. If subsequent to an
extraction system shutdown, monitoring shows that groundwater
concentrations of any contaminant of concern are above background
levels or MCLs, whichever is lower, the system shall be restarted
and continued until the required levels have once more been
attained for twelve consecutive quarters. Semi-annual monitoring
shall continue until EPA determines, in consultation with the
PADER, that contaminants have met previously specified
performance standards. An operation and maintenance plan for the
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TABLE 18
Contaminants of Concern in Ground Water
Contaminant
vinyl chloride
ethylbenzene
styrene
1 ,2-dichloroethene
(trans)
trichloroethene
MCL (ug/l)
2
700
100
100
5
Detection Limit
(ug/l)
.18
.06
.04
.06
.12
Method
601
524.2
524.2
524.2
601
Method 601 is found in 40 C.F.R. Part 136 ^
Method 524.2 is found in 40 C.F.R. Part 141
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groundwater' monitoring system shall be required, and must be
approved by EPA in consultation with the PADER.
(f) Operation and Maintenance of Extraction and Treatment
System
Operation and maintenance of the groundwater extraction and
treatment system shall be required in order to assure that it
performs according to the EPA-approved design. The performance of
the groundwater extraction and treatment system shall be
carefully monitored on a regular basis and the system may be
modified, as warranted by the performance data collected during
operation. Samples of treated groundwater shall be collected
periodically to ensure that the treatment technologies employed
are reducing contaminant levels to required standards. These
modifications may include, for example, alternate pumping of
extraction wells or the addition or elimination of certain
extraction wells. A plan shall be developed to accomplish the
above specified operation and maintenance requirements.
(2) Institutional Controls
Institutional controls, in the form of deed restrictions will be '
placed on the deeds to the properties that comprise the on-site
ground water where contaminants remain above Performance Standard
levels. The institutional controls are needed to prevent the use
of on-site ground water for a drinking water source. Additional
deed restrictions will be implemented to limit the use of .the
Site to industrial use only. In addition, continued monitoring
of specified wells and periodic reevaluation of remedial
technologies for ground water restoration are also required.
(3) Worker Safety
During all Site work, Occupational Safety and Health
Administration ("OSHA") standards set forth at 29 C.F.R.
Parts 1910, 1926 and 1904 governing worker safety during
hazardous waste operations, shall be complied with as required by
the MCP.
(4) F±V9-To*r Ruviotrs
Five-year reviews shall be conducted after the start of the
remedial action to assure that the remedy continues to protect
human health and the environment. A 5-Year Review Work Plan
shall be required and shall be approved by EPA in consultation
with the PADER.
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STRATEGY IF. THE SELECTED REMEDY TS NOT ACHIEVED
Based on the information obtained during the RI, and the
analysis of the remedial alternatives, EPA and the Commonwealth
of Pennsylvania believe that it is possible to achieve the
required groundvater cleanup levels. However, the ability to
achieve required cleanup levels at all points throughout the area
of attainment or plume of contamination cannot be determined
until the extraction system has been implemented, operated,
modified as necessary, and plume response monitored over time.
If it is determined by EPA, in consultation with PADER, that
on the basis of the system performance data, that certain
portions of the aquifer cannot be restored to background levels,
or MCLs, whichever is lower, and/or if EPA determines that it is
technically impracticable to restore the aquifer, EPA may amend
the ROD or issue an Explanation of Significant Differences in
accordance with the KCP. In such event, the likely alternative
actions will attempt to remediate the groundwater to its
beneficial use, i.e. a drinking water source. If, however the
aquifer cannot be restored to its beneficial use, some or all of
the following measures involving long-term management could
occur, as determined by EPA in consultation with PADER, for an
indefinite period of time, as a modification of the existing - S
system:
• long term gradient control may be provided by low level
pumping, as a containment measure;
• chemical-specific ARARs may be waived for those portions of
the aquifer for which EPA and PADER determine that it is
technically impracticable to achieve further contaminant
reduction;
• institutional controls may be provided/maintained to restrict
access to those portions of the aquifer where contaminants remain
above Performance Standards;
• remedial technologies for groundwater restoration may be
reevaluated; and
• further sampling and/or monitoring of existing and/or new
wells may be ordered.
Following review and consideration of the information in the
Administrative Record file, the requirements of CERCLA and the
NCP, and public comment, EPA has selected Alternative 2, (Onsite
Drying of PVC Layers and Landfilling of the Coal Fines Layer),
for the removal of the earthen lagoons at the OCC Site.
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Alternative 2 meets the threshold criteria of overall protection
of human health and the environment and compliance with ARARs,
and provides the best balance of long term effectiveness and
permanence, reduction of toxicity, mobility or volume of
contaminants through treatment, short term effectiveness,
implementability and cost.
The selected remedy for the earthen lagoons consists of the
following components:
• Construction of an access road to the earthen lagoons
» Excavation of PVC material (which includes all PVC sludge),
coal fine layers and contaminated soil
• Storage hopper for excavated materials
» On-site drying PVC material with air pollution controls
• Dried PVC material shall be bagged, stored, and recycled
• Sampling and analysis as approved by EPA for transportation and.
disposal of bottom coal fines layer of lagoons, including :
residuals
• Sampling and analysis of underlying soils as approved by EPA to
document removal of chemicals of concern to background
concentrations
• Restoration of the area to original grade which includes
backfilling excavations with clean fill
• Institutional Controls
PERFORMANCE STANDARDS
(1) All PVC Material (white and gray layers) contained in the
earthen lagoons shall be dried on-site and recycled in accordance
with the following:
(a) The PVC Materials which comprise approximately 31,000
cubic yards of lagoon materials shall be excavated and
transported out of the floodplain for onsite drying. Prior
to the start of the removal of the material, an access road
shall be built which supports the weight of loaded dump
trucks and excavation equipment. Vegetation which has grown
on the lagoon surface shall be removed prior to excavation
of the white layer. Any possible impacts on^wetlands shall
be identified, and impacts on wetlands shall*be minimized
and mitigated, pursuant to a plan approved by EPA. All
material identified as white and gray layers, coal fines,
and contaminated soil shall be excavated. Once excavated,
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the PVC material shall be dried on-site and bagged. The
bagged material shall be stored out of the floodplain until
the reclaimed materials are marketed for sale to be reused
in applications such as electrical conduit, or sewer pipe.
(b) Recycling of the PVC Material shall ensure that
hazardous substances, pollutants, and contaminants within
the final recycled product ("Final Product") are inseparable
from the Final Product. The PVC Material and any residuals
shall be tested in accordance with procedures authorized
under RCRA to determine whether such materials exhibit RCRA
hazardous characteristics.
(2) The PVC material shall be dried so that the material is
appropriate for recycling and does not exhibit RCRA
characteristics. The dryer shall be operated so that air
emissions from the dryer meet the appropriate requirements as set
forth at 40 C.F.R. Part 264, Subpart AA - Air Emission Standards
for Process Vents. In addition, the dryer shall be operated to
comply with the Commonwealth of Pennsylvania regulations set
forth at 25 PA Code, Chapter 127, Subchapter A.
(3) Dried material shall be bagged and stored in a manner that
does not contribute to any further site contamination, and does
not cause any release or threat of release of hazardous
substances.
(4) Residuals from the recycling process, and PVC material from
the lagoon perimeter that EPA determines cannot be recycled,
shall be tested to determine whether such residuals exhibit RCRA
hazardous characteristics. Recycling residuals that do not
exhibit RCRA hazardous characteristics shall be disposed of in an
appropriate off-site landfill.
(5) Residuals that do exhibit RCRA hazardous characteristics
shall undergo treatability tests so that EPA can determine the
most appropriate method of treatment prior to land disposal.
These materials shall then be treated so that such materials no
longer exhibit RCRA hazardous characteristics and shall then be
disposed of in an appropriate off-site landfill.
(6) Coal fines underlying the PVC sludge shall be excavated,
analyzed for RCRA Characteristics and transported off-site for
appropriate disposal. Sampling and disposal requirements shall
be approved by EPA in consultation with PADER.
(7) Following removal of the PVC sludge and coal fines, sampling
and analysis of the underlying soils shall be performed to
document complete removal of the lagoon contents.
(8) The restoration shall include removal of the constructed
access road and revegetation of all restored areas with native
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grasses and- herbs, if wetlands are impacted, they shall be fully
restored, according to a restoration plan approved by EPA in
consultation with PADER.
(9) Institutional Controls in the form of deed restrictions shall
be placed on the deeds to the properties to limit the use of the
Site to industrial use only.
C. General Description of the Selected Drainage avale and
Sedimentation Pond Remedy
Following review and consideration of information in the Remedial
Investigation, EPA shall require additional sampling to define
the extent of cleanup required for the contaminated sediment
found in the Sediment Pond and Drainage Swale during remedial
design. The sediment shall be remediated to levels equivalent to
the maximum Schuylkill River sediment background concentration
detected during the Remedial Investigation: PAHs - 5 ppm,
dibenzofurans - 0 ppm, PCBs - 0 ppm, and mercury - .4 ppm. In
addition, further sampling of the floodplain to the south of the'
17 acre landfill and sediment pond/drainage swale is required to
determine whether migration of contaminants has occurred during '
flooding events.
The sediment pond and drainage swale are downgradient of the
active 7-acre industrial waste landfill permitted by the State of
Pennsylvania. Review of the report and photographs from the EPA
June 1991 Site Analysis (TS-PIC-90960) shows the potential for
contaminants associated with other site activities (e.g., the
closed landfill and areas of standing liquid and mounded
material) to have been transported by storm water runoff to the
pond and swale area.
Upon completion of the further sampling, a full assessment of
environmental risk and development of remedial objectives shall
be completed.
X. STATUTORY DBTERMIHATIONS
Section 121 of CERCLA requires that a selected remedy:
. be protective of human health and the environment;
. comply with ARARs;
. be cost-effective; •
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. utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the
maximum extent practicable; and
. address whether the preference for treatment as a
principal element is satisfied.
A description of how the selected remedies satisfy each of the
above statutory requirements is provided below.
The selected remedies for the Site will be protective of human
health and the environment by reducing the principal threat posed
at the Site, by addressing the ground water contamination beneath
the OCC Site and at the earthen lagoons: sludge and soil
contamination. Potential health threats posed by the Site
through exposure-pathways (i.e. direct contact, ingestion of
sludge, contaminated soils, sediments and contaminated ground
water, and inhalation of ambient air) will be eliminated by the
remedies selected in this ROD. -
Contaminants in the ground water beneath the OCC Site will be
remediated to background levels. PVC Material at the earthen
lagoons will be excavated and recycled while the contaminated
soil/coal fines at earthen lagoons will be excavated and
transported off-site for disposal. Contaminated sediments at the
Sediment Pond and Drainage Swale will be remediated to background
levels found in the Schuylkill River.
B. Compliance vith ARARs
All applicable or relevant and appropriate requirements (ARARs)
pertaining to the selected remedies for the OCC Site will be
attained. The ARARs are discussed in Sections VII, X and below.
Pumping and Treatment of Groundvater with Air stripping and
Carbon Vapor Phase Adsorption.
Contamination in the ground water beneath the OCC Site is
required to be reduced to background levels by 25 PA Code §S
264.90 - 264.100, specifically 25 PA Code SS 264.97(1) and (j)
and 264.100(a)(9). PADER's February, 1992, policy document,
"Ground water Quality Protection Strategy," although not an ARAR
is to be considered in the implementation of this remedy. This
policy document defines the framework for ground water
remediation programs. In the document, PADER states that its
goal is "noiydegradation of ground water quality" (p. 1), which
means that the ultimate goal of all remediation projects is to
restore levels to background quality. However, PADER recognizes
that "there are technical and economic limitations to immediately
achieving the goal of nondegradation for all ground waters" (pp.
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1-2), and that levels above background may not present an
unacceptable risk to human health and the environment. The
background concentration for each contaminant of concern shall be
established in accordance with the procedures for ground water
monitoring in 25 PA Code § 264.97, which shall be an ARAR for
this remedy. The SDWA MCLs listed in Table 19 are also ARARs
with which this remedy will comply.
Action-specific ARARs for the discharge of treated ground water
will be met. Depending on the method of effluent discharge from
the production treatment system, applicable NPDES or POTW
pretreatment regulations will apply. If the effluent is
discharged to the Schuylkill River, this remedy will comply with
the substantive requirements of the Clean Water Act NPDES
discharge regulations (40 C.F.R. SS 122.41 - 122.50 and 40 C.F.R.
Part 13J.), the Pennsylvania NPDES Regulations (25 PA Code SS 91
and 92.31), the Pennsylvania Water Treatment Regulations (25 PA
Code SS 95.1 - 95.3 and 97), the Pennsylvania Water Quality
Standards (25 PA Code SS 93.1 - 93.9). If the effluent is
discharged to a Publicly owned Treatment Works (POTW), this
remedy will comply with 40 C.F.R. Part 403. "
voc emissions from any air stripping tower will be governed by • ""'
the PADER air pollution regulations. Air Emissions will also
comply with 40 C.F.R. Part 264, Subpart AA, Subchapter AA
(Standards for Process Vents), and with 40 C.F.R. Part 264,
Subpart BB, Subchapter BB (Air Emissions Standards for Equipment
Leaks) and 25 PA Code Chapter 264. Air emissions of Vinyl
Chloride will comply with 40 C.F.R. Part 61, Subpart F, National
Emission Standards for Hazardous Air Pollutants (NESHAPS).
Air permitting and emissions ARARs are outlined in 25 PA Code
Chapters 121, 123, 124, 127, 131, 135, and 139. 25 PA Code S
127.12 requires all new air emission sources to achieve minimum
attainable emissions using the best available technology ("BAT").
In addition, the PADER air permitting guidelines for remediation
projects require all air stripping and vapor extraction units to
include emission control equipment. However, the permitting
regulations allow for exemptions if a source is considered to be
of "minor significance,1* or if emission controls are not
economically or technically feasible. Also to be considered at
the Site are the PA Bureau of Air Quality Memorandum permitting
Criteria for remediation projects involving air strippers and
soil decontamination units. During design of the air stripping
unit, PADER shall calculate from actual design flow rates and VOC
loading rates whether emission controls need to be installed.
A vapor phase carbon adsorption shall be installed to ensure
compliance with S 112 of the Clean Air Act, 42 U.S.C. S 7412,
National Emission Standards for Hazardous Air Pollutants
(NESHAPs). The relevant and appropriate NBSHAP for vinyl
chloride is set forth at 40 C.F.R. Part 61, Subpart F. OSWER
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Directive 9355.0-28 - Control of Air Emissions from Suoerfund &JT-
shippers at Superfund Ground water Sites although not an ARAR is
to be considered for any air stripper used in this remedy.
Fugitive dust emissions generated during remedial activities will
be controlled in order to comply with fugitive dust regulations
in the federally-approved State Implementation Plan for the
Commonwealth of Pennsylvania, 25 PA Code §§ 123.1 - 123.2, and
will not violate the National Ambient Air Quality Standards for
fugitive dust generated during construction activities, 40 C.F.R.
§§ 50.6 and 52.21(j) and 25 PA Code §5 131.2, 131.3, and 131.4.
This remedy will comply with the ground water monitoring
requirements in 25 PA Code Chapter 264, Subchapter F.
Earthen Lagoon Excavation.
The remedy for the earthen lagoons will comply with the
applicable portions of the PADER Ground Water Quality Protection
Strategy, which prohibits continued ground water quality
degradation, since all contaminated sludge and soil which could'
potentially impact the ground water will be excavated for either
onsite recycling or off-site disposal. „
Onsite treatment (recycling), storage will comply with RCRA
regulations 40 C.F.R. Part 264 and standards for owners and
operators of hazardous waste treatment, storage and disposal
facilities. It will also comply with 25 PA Code Chapter 264.
Determinations about the effectiveness of any soil remediation at
the Site shall be compared with EPA document no. 230/02-89-042,
Methods for Evaluating Cleanup Standards. Vol. I; Soils and
Solid Media, although not an ARAR for the Site, this document
shall be considered.
Excavation of the earthen lagoon materials may impact the
adjacent wetland area. This Alternative will consider the
provisions for protection of wetlands and flood plain management
in 40 C.F.R. Parts 6 (Executive Order 11988 "Floodplain
Management 230, Guidelines for Specification of Disposal Sites
for Dredged Material1* and 230 and 25 PA Code SS 105.17-105.20(a).
In addition, it will comply with erosion control requirements
related to excavation activities in 25 PA Code Chapter 102.
Fugitive dust emissions generated during remedial activities will
be controlled in order to comply with fugitive dust regulations
in the federally-approved State Implementation Plan for the
Commonwealth of Pennsylvania, 25 PA Code SS 123.1 - 123.2, and
will not violate the National Ambient Air Quality Standards
(NAAQS) for particulate matter, 40 C.F.R. SS 50.6 and 25 PA Code
SS 131.2, 131.3, and 131.4.
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This remedy will comply with the ground water monitoring
requirements in 25 PA Code Chapter 264, Subchapter F.
Compliance With Other Laws
Any off-site disposal or treatment as a result of this remedy
will comply with regulations for the generation and
transportation of hazardous wastes, 25 PA Code Chapter 262,
Subchapters A and C, and Chapter 263. It shall also comply with
the RCRA regulations and standards for owners and operators of
hazardous waste treatment, storage and disposal facilities, 25 PA
Code Chapter 264.
Pennsylvania Solid Waste Management Act, Act 97 which is
applicable to remedial actions involving storage, collection,
transportation, processing, treatment, and disposal of solid
waste.
This remedy would comply with CERCLA S 121(d)(3) and with EPA
OSWER Directive #9834.11, both of which prohibit the disposal of.
Superfund site waste at a facility which is not in compliance :--
with SS 3004 and 3005 of RCRA and all applicable State :
requirements. .:
Occupational Safety and Health Act (OSHA) Regulations (29 CFR
Parts 1904, 1910, and 1926) provide occupational safety and
health requirements applicable to workers engaged in onsite field
activities. The regulations are applicable to onsite work
performed during the implementation of a remedial action.
Department Of Transportation (DOT) Rules for Hazardous Materials
Transport (49 CFR Parts 107 and 171-179) regulate the transport
of hazardous materials, including packaging, shipper equipment,
and placarding. These rules are applicable to wastes such as
those shipped off-site for treatment or disposal. Potential
applications of the DOT rules apply to the Site if off-site
drying occurs or off-site disposal of lagoon materials occurs.
C. Cost-Effectiveness
The estimated present worth cost of the selected remedy for the
ground water contamination beneath the OCC Site (ground water
pumping and treatment combined with air stripping and carbon
vapor adsorption) is $7,100,000.
The estimated present worth cost of the selected remedy for the
earthen lagoons (Onsite drying of PVC layers and Lahdfilling of
Coal Fines Layer) is $4,019,000. If the coal fines material
require hazardous waste disposal, the estimated present worth
cost of the selected remedy is $5,300,000.
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D.
EPA has determined that the selected remedies represent the
maximum extent to which permanent solutions and treatment
technologies can be utilized while providing the best balance
among the other evaluation criteria. Of the alternatives
evaluated that are protective of human health and the environment
and meet ARARs, the selected remedies provide the best balance of
tradeoffs in terms of long-term and short-term effectiveness and
permanence, cost, implementability, reduction in toxicity,
mobility, or volume through treatment, State and community
acceptance, and preference for treatment as a principal element.
The selected remedy for the contaminated ground water beneath the
OCC Site, pumping and treatment with air stripping and carbon
vapor adsorption is a proven technology.
The selected remedy for the earthen lagoon materials will provide
a higher degree of treatment and a lower residual contamination.
than the other Alternatives evaluated.
B. Preference for Treatment as a Principal Element "]"•
Ground water pumping and treatment combined with air stripping
and carbon vapor phase adsorption of the contaminated ground
water at OCC Site fulfills the statutory preference for remedies
that employ treatment as a principal element.
Onsite drying of the earthen lagoon materials fulfills the
statutory preference for remedies that employ treatment as a
principal element.
XX. EXPLANATION OF SIGNIFICANT CHANGES
The Proposed Plan for the Occidental Chemical Site was released
for public comment on April 20, 1993. The Proposed Plan
identified Groundwater Alternative 2A (Groundwater Pump 6 Treat
Before the Production Process with Air Stripping and Vapor Phase
Carbon Adsorption) and Earthen Lagoon Alternative 2 (Onsite
Drying of Lagoon Materials and Landfilling of Coal Fines Layer)
as EPA's preferred Alternatives for ground water and earthen
lagoon remediation. The selected remedy described in this ROD
differ from the remedy in the Proposed Plan with regard to the
following:
1) Upon receipt of comments by the Department of Interior during
the public comment period, EPA has determined that the Sediment
Pond and Drainage Swale require sediment cleanup. In order to
remediate the Sediment Pond and Drainage Swale, further sampling
is required to characterize the extent of contamination. In
addition, sampling is required in the floodplain area to the
south of the seventeen acre landfill to determine if migration of
contaminants has occurred during flooding events. Upon
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completion of sampling, an environmental risk assessment with
remedial standard may be developed, if appropriate, which would
then be set forth in a future ROD for this Site.
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Responsiveness Summary
Occidental Chemical Corporation Superfund Site
Lower Pottsgrove, Montgomery County, Pennsylvania
This Responsiveness Summary documents public comments received by EPA during the
public comment period on the Proposed Plan for the Occidental Chemical Corporation Site
("the Site"). It also provides EPA's responses to those comments. The Responsiveness
Summary is organized as follows:
SECTION I
SECTION H
SECTION
SECTION IV
Overview
This section summarizes recent actions at the Site and the public's
response to the remedial alternatives listed in the Proposed Remedial
Action Plan (Proposed Plan). The Proposed Plan outlines various
cleanup alternatives available to address Site contamination and
highlights EPA's preferred alternative.
Background on Community Involvement
This section reviews the history of community interest and involvement
in the Occidental Chemical Corporation Superfund Site.
Summary of Major Comments and Questions Received During the
Public Meeting and EPA's Responses
This section documents comments and questions from the public
regarding the Site and EPA's responses to them.
Summary of Written Comments and Questions Received During the
During the Comment Period and EPA's Responses
This section documents written comments and questions from the
public regarding the Site and EPA's responses to them.
L . Overview
The public comment period on the Proposed Plan for the Site began on April 20,1993, and
ended on May 19,1993. EPA held a public meeting at the Pottstown Senior Center on May
4, 1993.
At the meeting, EPA representatives summarized the results of the Remedial Investigation
("RT), Feasibility Study ("FS"), and the Baseline Risk Assessment ("BRA") performed for
the Site. EPA presented the preferred alternative to address Site contamination.
The Proposed Plan addressed twa areas of contamination: bedrock ground water and
earthen lagoons. The preferred cleanup alternative for the contaminated bedrock ground
water would involve extraction of the water using recovery wells and treatment through an
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air stripper with vapor phase carbon adsorption. The preferred cleanup alternative for the
earthen lagoons would involve constructing an access road, drying the white and gray layers
of polyvinyl chloride (PVC) material onsite for recycling and transporting coal fines and
contaminated soil to an appropriate disposal facility.
The public was given an opportunity to ask questions or submit written comments on the
cleanup alternatives outlined in the Proposed Plan and the results of the Remedial
^Investigation for the Site. The comments and EPA's responses are documented in Section
III and IV of this document. The transcript of the public meeting is contained in the
Administrative Record for the Site. In general, the public which expressed opinions
supported EPA's Preferred Alternative to cleanup the Occidental Chemical Site.
IL Background on Community Involvement
The Occidental Chemical Corporation Superfund Site is located 1/2 mile southeast of the
Borough of Pottstowri, Montgomery County, Pennsylvania. In February 1991, EPA
conducted community interviews with local residents and officials to determine public
awareness and concerns about the Occidental Chemical Corporation Site. EPA used these
community interviews to develop a Community Relations Plan. The Community Relations.
Plan addresses community concerns about the Site and guides two-way communication
between EPA and the Site community. Residents and local officials expressed concern about
the impact of Site contamination on the community. The major concerns included: ground
water contamination spreading off-site, health hazards associated with contamination,
hazardous waste disposal procedures, and reduced real estate values in the area. The
interviews revealed that community members were generally unfamiliar with the Site and the
Superfund process.
In August 1991, EPA held a public meeting to discuss the Superfund process and future
activities planned at the Site. Attendance at this meeting was low and consisted of mostly
local officials. EPA distributed informational fact sheets in February 1991, and in April 1993
to update the community on cleanup work at the Site.
HL Summary of Major Comments and Questions Received During the Public Meeting
and EPA's Responses
PROPOSED REMEDIAL ACTION PLAN
1. When wfll the clean up be started ?
EPA Response: *It is estimated that actual construction will begin in 1995. Upon the close
of the public comment period, EPA will review all Site-related comments and questions
submitted during the comment period and voiced at the May 4, 1993 public meeting and
issue a Record of Decision. EPA then intends to give the parties responsible for the
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contamination an opportunity to conduct the cleanup, and engineers will prepare plans and
technical specifications to implement the cleanup.
GROUND WATER CONTAMINATION
1. Will there be an incinerator on site ?
EPA RESPONSE: No. During the public meeting an EPA representative described the
regeneration of the carbon adsorption units as a form of incineration. In actuality, when
carbon is regenerated it is heated in a kiln-like apparatus to release the contaminants from
the carbon. The contaminants may be completely destroyed; however those that are not are
then trapped in a pollution control device on the kiln. The residuals which may be trapped
in the pollution control device are handled as a RCRA hazardous waste and disposed of
appropriately.
2. Is the trichloroethylene (TCE) found in the ground water a cancer risk ?
EPA RESPONSE: Yes. According to the Site Risk Assessment, there is a cancer risk
associated with drinking the ground water. However, there is no current use of the ground'
water as drinking water. The risk exists from the potential migration of the water to
residential wells north of the Site, to the Schuylkill River or under the river to residential
wells south of the Site or to future use of the ground water at the Site. Also, EPA believes
that the contaminated ground water would migrate to the residential wells if the Occidental
Chemical Corporation shut down their wells.
3. Why is vinyl chloride present in any measureable amount when it is so volatile ? Is it
bound up in the solids ?
EPA RESPONSE: Vinyl chloride is dissolved in the ground water. EPA believes that it is
a result of the break down of trichloroethylene (TCE) that occurred beneath the ground in
the water. Recently, the concrete settling basins located in the wastewater treatment plant
on the Site have been identified as a potential source of vinyl chloride contamination.
Occidental is currently upgrading these basins to prevent leakage.
4. Is Occidental Chemical Corporation monitoring the ground water wells ?
EPA RESPONSE: Yes, Occidental Chemical Corporation is monitoring the wells. EPA
oversees this monitoring process.
5. How is the contaminated ground water is being processed now and where the discharge
is going? .
EPA RESPONSE: Occidental Chemical Corporation is pumping the ground water from the
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wells and using.it in its production process. After the production process, the ground water
passes through the waste water treatment system which settles out the PVG solids. The
ground water then passes through an air stripper to remove the volatile organic compounds
and is discharged to the Pottstown Publicly Owned Treatment Works (POTW).
6. Is there a contingency plan in case the carbon unit doesn't adsorb the compound ?
EPA RESPONSE: Yes, two carbon units will be on site for that particular reason. When
the first carbon unit becomes saturated with volatile organic compounds it will be
regenerated onsite. While the first unit is regenerated, a second unit will be utilized. Also,
the equipment will have routine maintenance to ensure proper operation.
7. Will the vapor phase carbon adsorption unit be installed into the air stripper that is
already present ?
EPA RESPONSE: No, the air stripper that is currently operating on-site receives the ground
water after it has been utilized in Occidental's production process. EPA has determined that
the ground water should be treated before the production process with a new air stripper:
Once treated, the water could enter the production process and go through the existing
wastewater treatment which includes an air stripper before discharge to the POTW or the •
Schuylkill River.
8. Is EPA going to operate this system even if Occidental closes ?
EPA RESPONSE: EPA intends to ensure that either one or more of the responsible parties
will operate the systems, no matter what happens to Occidental's production. If no
responsible party can conduct the cleanup, it is possible that EPA or the State could take
over the clean up.
9. How many years will it take to clean up the grbundwater ?
EPA RESPONSE: A current ground water model developed by Occidental shows'that to
restore this water supply to drinking water quality it could take 100 years. However, this
system will be monitored to determine if the plumes respond to the treatment A long term
ground water monitoring program will be implemented. The wells will be sampled quarterly
for the first three years and semi-annually thereafter until the levels reach background. If
the performance data indicate that the portions of the aquifer cannot be restored, and EPA
determines that it is technically impracticable to restore the aquifer, EPA may amend the
ROD or issue an Explanation of Significant Differences in accordance with the NCP. This
is further discussed in Section DC #4, of the ROD.
10. What will be done with the extra water that is pumped from the additional wells ?
EPA RESPONSE: The remedy selected does not pump additional volume. The wells will
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continue to supply Occidental with process water but they will be pumped at lower rates to
optimize the collection of contaminated water.
11. Has EPA considered new technologies in dealing with TCE contamination ? For
example, using microbes to remediate the TCE in the groundwater.
EPA RESPONSE: Yes, EPA has considered various technologies in the remediation of the
groundwater. One of the technologies that was considered was insitu bioremediation. This
involves altering the subsurface environment to accomodate a colony of microbes which then
metabolize the organic waste. Specific nutrients must be present as well as suitable
hydrogeology. This use of this technology is typically applied to soils and its use in fractured
bedrock, which exists at this site, is unproven.
EARTTffiN LAGOON CONTAMINATION
12. Where will the earthen lagoon material be landfilled ? Will it be disposed on site ?
EPA RESPONSE: EPA does not know the exact location of the off site landfill. This
location will be determined during remedial design. The material will not be landfilled on'
the Occidental Site. The only material that is proposed for landfilling is the coal fines layer
at the bottom of the lagoons and any contaminated soil. Depending on the classification of
the coal fines and soils, the material will be landfilled in either a hazardous waste, residual
waste or solid waste landfill.
13. What will be done with the old landfill on site ?
EPA RESPONSE: No additional work will be performed at the old landfill (17 acre closed
landfill). It was closed in 1985 under a Pennsylvania Department of Environmental
Resources (PADER) closure plan. The landfill is covered with an impermeable liner and
surrounded by monitoring wells. Samples taken from those wells have shown that the
groundwater has not been impacted by the closed landfill
IV. Summary of Written Comments and Questions Received During the Pubfic Meeting
and EPA's Responses
GROUND WATER CONCERNS
Comments submitted by the Borough of Pottstown and the Township of Lower Pottsgrove
expressed the following concerns:
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14. The pump & treat requirement will unnecessarily burden the current property owners
and certainly those who might consider an investment in this property in the future.
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EPA RESPONSE: EPA disagrees that the cleanup will unnecessarily burden, the current
property owner. The properly remediated site will be a far better investment than an
unaddressed contaminated site.
15. This burden of operating the pump and treat system will eventually result in the public
agency assuming responsibility for its continuance. It is likely that it will result in the
responsibility of the local government
EPA RESPONSE: Operation and Maintenance at this Site will remain the responsibility
of the reponsible parties. See Response #8.
16. What happens if there is a change in ownership ? Would anyone desire to purchase this
site within the next 100 years if this pumping requirement goes along with ownership ? Or
what happens is a future owner fails to continue the pumping ? Will it become the
responsibUty of the Township ?
EPA RESPONSE: A change in ownership would not affect the operation and maintenance.
of the pump and treat system. The responsible parties would still be required to continue
the O & M. If all of the responsible parties were financially incapable of contining the
O & M, the Commonwealth of Pennsylvania would be asked to assume the responsibility.
17. The performance standard that Occidental is required to meet is higher than the
standard that is required for human consumption drinking water.
EPA RESPONSE: The performance standard for each contaminant of concern is the
Maximum Contaminant Level (MCL) which is the federal standard for drinking water
supplies, or the background concentration, whichever is lower. In the event that the
contaminants of concern are not detected in the background samples, the method detection
limits of EPA-approved low level drinking water analytical methods will constitute
background for each specific contaminant Therefore, it is possible that the background
levels established are more stringent than MCLs. However, this is a requirement of the
Commonwealth State of Pennsylvania's Ground Water Quality Protection Strategy which wfll
be followed in the implementation of this remedy.
18. If EPA is concerned that this water eventually may be used for human consumption, an
alternative that is less expensive and readily available would be to extend water lines to any
resident or land use impacted by the contaminated plume.
EPA RESPONSE: The Site currently does not impact the water supply. However, the
potential threat from the Site to impact human health and the environment requires
remedial action. The mandate of the Snperfund program is to protect human health and
the environment from the current and potential threats posed by uncontrolled hazardous
waste sites and to restore groundwater to its beneficial use. Thus, the currently existing
contamination has impacted an important ground water resource, which local residents may
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need to use for drinking water in the future. Remedies that protect human health and the
environment can be fulfilled through a variety or combination of means. These means
include the recycling or the destruction, detoxification, or immobilization of contaminants
through the application of treatment technologies. Protection can also be provided in some
cases by controlling exposure to contaminants through engineering controls (such as
containment) and/or institutional controls which prevent access to contaminated areas.
However, treatment is the preferred method of attaining protectiveness, wherever
practicable.
The following comments were submitted by the Occidental Chemical Corporation:
19. The Proposed Plan should be modified to show landfilling of the earthen lagoon material
(Alternative 4) as the preferred option. This is based on a review of recent market
conditions which showed that the demand for the reclaimed product from the earthen
lagoons is low, and therefore likely that the dried material would need to be stored for an
extended period of time. Current market conditions create the situation wherein direct
landfilling will be less costly and more time-efficient to complete, thus, direct landfilling
becomes the preferred alternative. -
EPA RESPONSE: EPA disagrees that landfilling of the lagoon material should be
preferred alternative. Occidental has not provided any supporting information which
substantiates the recent market conditions or, which market they are concerned about It
is possible that alternative markets could be developed for this material. In addition, EPA
believes that further characterization of the P VC material is required to ensure that it is not
a RCRA characteristic waste. If landfilling were to be considered additional sampling would
be warranted to meet disposal requirements.
20. The Site is said to be "3 miles" southwest of the Pottstown Borough on page 1 of the
Proposed Plan, and "1/2 mile" on page 2. The Site is 1/2 mile from the borough boundary
and approximately 3 miles from downtown Pottstown.
EPA RESPONSE: EPA acknowledges this discrepancy and will clarify this in the Record of
Decision.
21. Page 4, Earthen Lagoons: The last sentence states that the underlying soils and coal
fines layer have been classified as non-hazardous. It should also be stated that the gray and
white material layers have been tested and the material is not classified as hazardous.
EPA RESPONSE: The Proposed Plan states that as a result of the RI Sampling the
underlying soils and coal fines layer have been classified as non-hazardous. It also states that
the lagoon material is not a hazardous waste as defined by RCRA.
However, it must be clear that the lagoon material is to be recycled. If recycling were not
the remedy, additional sampling would be warranted to characterize the material for disposal
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to make sure that it is not a characteristic hazardous waste. The coal fines and soil will
require additional sampling in the remedial design prior to disposal. The results of that
sampling will determine the appropriate disposal method.
22. Page 5, Ground Water Alternatives: First, the presentation of Alternatives 2A and 3A
indicate that groundwater would be pumped at approximately 410 gpm when either the air
or steam stripper is placed before the plant's production process. The groundwater
modeling for the FS showed that 410 gpm is the expected maximum pumping rate from the
wells within the remediation capture zone; a design start-up pumping rate of 335 gpm was
recommended, with the potential to adjust rates based on performance of the system.
Secondly, the presentation of alternative 2B and 3B indicate that the ground water would
be pumped at rate of 620 gpm if either stripper is placed after the process. The 620 gpm
was a combination of flow from the remediation recovery wells and additional production
wells required to meet peak demands in the process operations. As presented in the
modeling report, the 620 gpm included groundwater pumped from wells outside the
remediation zone which were distant enough from the remediation recovery wells. Within.
Alternatives 2B and 3B, the groundwater obtained from within the remediation capture zone
would be supplemented by water from wells outside the zone. The stripper units for.
Alternatives 2B and 3B were thus designed to handle a larger flow (620 gpm) than 2A and
2B designs (410 gpm) because of the combined groundwater sources at the point of
treatment.
EPA RESPONSE: EPA acknowledges this clarification, however, operation of Occidental's
process is irrelevant to the operation of the remedy. These pumping rates are presented as
estimates only. Actual pumping rates and configurations will be determined when the
selected remedy is designed.
23. Page 5, Ground Water Alternatives: The proposed plan states that the preferred
groundwater remediation alternative has an approximate 100-year duration. It should be
noted that the modeling performed by Occidental shows the 5 VOC plumes will be so
significantly reduced within the first 25 years such that the risk associated with the
concentration of 2 chemicals which will still be detectable at that time will be in an
acceptable range (i.e. 1 X 10-4 to 1 x 10-6).
EPA RESPONSE: EPA has expanded its explanation of the Ground Water Alternatives
in the Record of Decision. However, the cleanup is required to meet the PADER
Groundwater Quality Protection Strategy. The purpose of the cleanup is to restore the
impacted ground water, so that it can be used as a safe drinking water source in the future.
See Response #17.
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