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The selected remedy includes the following major components:
1) Water Supply: Installation of a waterline to prevent contact with groundwater contamination
at residences affected or potentially affected by the Site.
2) Main Plant Area Soils: Installation of a cap to prevent direct contact with contaminated soils
at the Main Plant and to reduce the potential for continued migration of these contaminants to the
groundwater.
3) Main Plant Area Groundwater Plume: Extraction and treatment of groundwater via air
stripping followed by carbon adsorption or U/V oxidation and subsequent reinjection of treated
water to the aquifer to restore the Site groundwater to beneficial use.
4) Former Disposal Area/Mounded Area Soils: Excavation, off-Site treatment and disposal of
contaminated soils to reduce the potential for continued migration of contaminants in these soils
to the groundwater.
5) Former Disposal Area/Mounded Area Groundwater Plume: Implementation of a Natural
Attenuation program to monitor reduction of contaminant concentrations in groundwater to
Maximum Contaminant Levels.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the environment and is cost effective
EPA believes that the selected remedy will comply with all Federal and State requirements that
are legally applicable or relevant and appropriate to the remedial action. The selected remedy
utilizes a permanent solution to the maximum extent practicable and satisfies the statutory
preference for a remedy that employs treatment that reduces toxicity, mobility, or volume.
Because this remedy will result in hazardous substances remaining on-Site above health-based
levels, a review by EPA will be conducted within five years after initiation of the remedial action
to ensure that the remedy continues to provide adequate protection of human health and the
environment.
Abraham Ferdas, Acting Director Date
Hazardous Waste Management Division
Region HI
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TABLE OF CONTENTS
PART II - DECISION SUMMARY
I SITE NAME, LOCATION, AND DESCRIPTION 1
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES 2
III. HIGHLIGHTS OF COMMUNITY PARTICIPATION 3
IV SCOPE AND ROLE OF THE RESPONSE ACTION 3
V SUMMARY OF SITE CHARACTERISTICS 4
A. Topography 4
B. Climate 4
C. Hydrology 5
D. Land Use 5
VI. NATURE AND EXTENT OF CONTAMINATION 5
A. Main Plant Area 6
B. Former Disposal Area/Mounded Area 12
C. Domestic Wells 16
D. Potential Disposal Area 17
E. Previous Investigation Data 19
VII. SUMMARY OF SITE RISKS 20
A. Human Health Risks 20
1. Identification of Chemicals of Potential Concern 21
2. Exposure Assessment 23
3. Toxicity Assessment 25
4. Human Health Effects 26
5. Risk Characterization 26
B. Ecological Risk Assessment ' . 27
VIII DESCRIPTION OF ALTERNATIVES 29
IX COMPARATIVE EVALUATION OF ALTERNATIVES 40
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MAL yERN TCE SUPERFUND SITE
• Water Supply 42
- Main Plant Area Soils 44
- Main Plant Area Groundwater 46
- Former Disposal Area/Mounded Area Soils 47
- Former Disposal Area/Mounded Area Groundwater 50
X. SELECTED REMEDY AND PERFORMANCE STANDARDS 52
A. Water Supply 52
B. Main Plant Area Soils 54
C. Main Plant Area Groundwater 56
D. Former Disposal Area/Mounded Area Soils 60
E Former Disposal Area/Mounded Area Groundwater 62
XI. STATUTORY DETERMINATIONS 64
A. Overall Protection of Human Health and the Environment 64
B. Compliance with Applicable or Relevant and Appropriate Requirements 65
C. Cost Effectiveness 66
D. Utilization of Permanent Solutions and Alternative Treatment (or Resource
Recovery) Technologies to the Maximum Extent Practicable 66
E. Preference for Treatment as a Principal Element 67
XII. DOCUMENTATION OF SIGNIFICANT CHANGES 67
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PART HI - RESPONSIVENESS SUMMARY
OVERVIEW
I RESPONSES TO PUBLIC MEETING COMMENTS
II RESPONSES TO WRITTEN COMMENTS
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Appendix B - Figures
FIGURES
Figure 1 - Site Location
Figure 2 - Site Location with Hillbrook Circle
Figure 3 - Main Plant Area
Figure 4 - Generalized Groundwater Flow directions in the vicinity of the Malvern TCE Site
Figure 5 - Distribution of VOCs in Surface Soils, Main Plant Area 1996
Figure 6 - Distribution of S VOCs in Surface Soils, Main Plant Area 1996
Figure 7 - Soil Boring Locations, Main Plant Area
Figure 8 - Monitor Well Locations, Main Plant Area
Figure 9 - Distribution of VOCs and S VOCs in Groundwater, Main Plant Area
Figure 10 - Isopleth Concentration Map of Total VOCs, Main Plant Area
Figure 11 - Distribution of VOCs in Surface Soils, FDA
Figure 12-Distribution of S VOCs in Surface Soils, FDA
Figure 13- Soil Boring Locations, FDA
Figure 14- Distribution of VOCs and SVOCs in Groundwater, FDA
Figure 15- Isopleth Concentration Map of Total VOCs for Domestic Wells and FDA
Figure 16- Geophysical Survey Grid and Soil Boring Locations, PDA
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Appendix C - Tables
Table 1 - Maximum Concentrations in Surface Soil, Main Plant Area 1996
Table 2 - Maximum Concentrations in Subsurface Soils, Main Plant Area 1996
Table 3 - Monitor Well Sampling Organic Analytical Results, Main Plant Area 1996
Table 4 - Monitor Well Sampling Inorganic Analytical Results, Main Plant Area 1996
Table 5 - Comparison of Prefiltration Domestic Well Analytical Data Aug 1995 and June 1996
Table 6 - TCE Related Compounds for Soil Gas Samples
Table 7 - Chemicals of Potential Concern for Human Health Evaluation
Table 8 - Toxicity Information
Table 9 - Summary of Maximum Future Groundwater Risks to Residential Well Users
Table 10 - Summary of Risks by Receptor and Pathway
Table 11 - Summary of Risks Across Pathways
Table 12 - Summary of Alternatives
Table 13 - Summary of ARARs for the Selected Remedy
Table 14 - Residents to be Connected to the Public Water Supply
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RECORD OF DECISION
MAL VERN TCE SITE
PART II - DECISION SUMMARY
I. SITE NAME, LOCATION, AND DESCRIPTION
The Malvem TCE Supertund Site (Site) is located in East Whiteland Township, Chester County,
Pennsylvania (Figure 1). The Site is owned and operated by Chemclene Corporation
(Chemclene), which presently sells hydraulic oil and industrial cleaning solvents from the 258
North Phoenixvilie Pike location. The Site encompasses approximately 5 acres along the
southeast side of Bacton Hill, and includes a Main Plant Area connected to a Former Disposal
Area by a narrow meadow corridor. A Transcontinental natural gas pipeline right-of-way extends
along the southern boundary of the Site, with residential areas and areas with natural forestation
and vegetation bordering the property to the west, north and east (Figure 2).
Existing facilities at the main plant include a former distillation building, a storage building
which has collapsed, a concrete pad area, an open garage, and seven above-ground storage tanks
(Figure 3). One 8,000-gallon tank contains hydrogen peroxide and the other six above-ground
storage tanks are currently empty. From 1952 until 1992, Chemclene Corporation sold and
reclaimed industrial cleaning solvents including trichloroethene (TCE); 1,1,1-trichloroethane
(1,1,1-TCA); perchloroethylene (PCE, also called tetrachloroethene); and methylene chloride
(MEC). These solvents were used by local industries for degreasing metal parts and other
cleaning purposes. Chemclene used a distillation process to remove impurities from the
chlorinated solvents. The distilled solvents were then returned to customers for reuse.
The end products of processing waste solvents are the reclaimed solvents and chlorinated still
bottoms. The chlorinated waste solvents are listed hazardous wastes pursuant to the Resource
Conservation and Recovery Act (RCRA) and therefore, the resulting still bottoms are listed
hazardous waste. Prior to 1976, Chemclene reportedly buried drums containing the still bottom
sludges from the distillation process in the Former Disposal Area and Mounded Area,
approximately 1,900 feet southwest of the main plant. The Former Disposal Area consists of two
unlined earthen pits, each approximately 30 feet by 50 feet by 15 feet deep. This area is
currently secured by an 8-foot high chain link fence. The Mounded Area, located on the western
edge of the Former Disposal Area, is approximately 8 feet wide by 150 feet long.
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II. SITE HISTORY AND ENFORCEMENT ACTIVITIES
In the spring of 1980, TCE was detected in groundwater from several wells in the vicinity of the
Chemclene facility. At this time, Chemclene Corporation began sampling domestic wells in the
immediate vicinity of the property. Private domestic wells and on-Site monitoring wells were
sampled by Pennsylvania's Department of Environmental Resources (PADER) and Chemclene in
June 1980 and July 1981. Analytical results revealed contamination of the underlying aquifer
with chlorinated ethenes and related compounds. TCE was detected in wells at concentrations up
'to 12,600 micrograms per liter (ug/1), far exceeding the Maximum Contaminant Level (MCL) of
50 ug/1. The Site was listed on the National Priorities List (NPL) in September 1983 The
contaminated home wells were located south of the Former Disposal Area, with several located
in the Hillbrook Circle residential development. Chemclene furnished activated carbon filter
units to 20 residential wells within the Hillbrook Circle Development and conducted periodic
sampling of home wells in accordance with its Domestic Well Management Plan until November
1994. In February 1995, EPA assumed control of maintenance activities of the carbon filter units
and periodic sampling of the home wells, after it was determined that Chemclene was not
following the procedures outlined in its Domestic Well Management Plan. In August 1995,
several of the filter systems were upgraded by EPA in response to analytical results from
residential well samples that showed contamination was passing through the existing filters into
the homes.
In addition to the installation of carbon filters, Chemclene conducted removal actions following
the detection of soil and groundwater contamination in 1980. Debris and approximately 300
drums were removed from the Former Disposal Area excavations in a prolonged remedial effort
from 1981 to 1984. Soils underlying the Former Disposal Area were excavated to a depth of 15
feet and transported for disposal at a RCRA permitted disposal facility. Additional drums were
removed from the Mounded Area in late 1990; however, contaminated soil was left in place.
Four underground storage tanks (USTs) were removed from the main plant in 1986. Soil
samples collected from below the excavation grade of the tanks exhibited elevated concentrations
of TCE, PCE, and 1,1,1-TCA. In addition, elevated levels of volatile organic contaminants
(VOCs) were detected in soil gas samples collected outside the distillation building in the Main
Plant Area. These contaminant levels are believed to be related to Chemclene's past practices of
discharging contaminated condensate from the recycling distillation process directly onto the
ground surface.
As an operating facility, Chemclene Corporation entered into a Corrective Action Order with
EPA in 1987. A RCRA Facilities Investigation (RFI) Work Plan was approved for the Site in
1989. In July 1992, Chemclene withdrew its RCRA Part B Application as a treatment and
storage facility, and stopped accepting waste solvents for reclamation. Chemclene continues to
operate a hauling operation and sells hydraulic fluid, raw TCE, and hydrogen peroxide from the
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Site. This operation is regulated by the East Whiteland Township Fire Marshal's office
Chemclene failed to complete the RCRA RFI and implement interim corrective measures. As a
result, EPA began considering the Site under the Superfund remedial program in November
1993 All existing data was compiled and a report was developed entitled Data Summary
Report, April 1995. Based on EPA's review of the existing information, data gaps were
identified and EPA conducted a Remedial Investigation (RI) to complete the necessary data
gathering at the Site. The RI was completed in January 1997 and the Feasibility Study (FS) in
June 1997 The Proposed Plan for a comprehensive Site clean up was issued in June 1997
m. HIGHLIGHTS OF COMMUNITY PARTICIPATION
The documents which EPA used to develop, evaluate, and select a remedy for the Site have been
maintained at the Chester County Library, 400 Exton Square Parkway, Exton, PA and at the EPA
Region 3 Office, Philadelphia, PA.
The Proposed Plan was released to the public on June 23, 1997. The notice of availability for the
RI/FS and Proposed Plan was published in the Daily Local News on June 23, 1997. A 30-day
public comment period began on June 23, 1997 and was initially scheduled to conclude on July
23, 1997. By request, the public comment period was extended until September 2, 1997.
A briefing for the East Whiteland Township Board of Supervisors and a public meeting were
held during the public comment period on July 14, 1997. At the meeting, representatives from
EPA answered questions about the Site and the remedial alternatives under consideration.
Approximately 50 people attended the meeting, including residents from the impacted area,
potentially responsible parties, and news media representatives. A summary of comments
received during the comment period and EPA's responses are contained in Part III of this
document.
IV. SCOPE AND ROLE OF RESPONSE ACTIONS
This final selected remedy addresses the threats posed by the release of hazardous substances
at the Site. The primary objective of the remedy described in this ROD is to reduce or
eliminate the potential for human or ecological exposure to contaminated soil and groundwater
at the Site. The selected remedy outlined on pages 52 to 64 of this ROD will comprehensively
address the risks posed by the release or threat of release of hazardous substances from the
Site. The concentrations of chemicals in the two groundwater plumes exceed the MCLs set
under the Safe Drinking Water Act, 42 U.S.C. §§ 300(0 to 300 0-26). In addition, this
remedial action addresses soils at the Former Disposal Area.
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V. SUMMARY OF SITE CHARACTERISTICS
A. Topography
The Site is located in eastern Chester County, Pennsylvania, in the Piedmont Physiographic
Province of the Appalachian Highlands. Topography in the county is characterized by uplands
composed of Precambrian igneous and metamorphic crystalline rocks that have weathered into
rolling hills. These uplands are bisected by the Chester Valley, the county's most prominent
topographic feature, which is underlain by deeply eroded carbonate rocks. The Chester Valley
trends east/northeast across the county.
The Site is situated in the northern edge of the Chester Valley adjacent to Bacton Hill. The
valley floor has gentle relief with elevations ranging from 350 to 400 feet above mean sea level
(MSL). Topography at the Site ranges from 395 feet MSL in the north portion of the Former
Disposal Area to 360 feet MSL in the area around the main plant. Bacton Hill defines the north
edge of the valley around the Site and is underlain by the Cambrian age Chickies Quartzite, a
formation that is comparatively resistant to weathering and forms ridges.
B. Climate
The climate in Chester County is humid, temperate and continental with-fairly mild winters.
Average monthly temperatures range from 32°F in January to 77°F in July (National Oceanic
and Atmospheric Administration, Climatological Data from Conshohocken Station). The
average annual temperature, based on a 100-year record through 1955 is 52.2°F. The absolute
minimum and maximum temperatures for the same time period are -15°F and 105°F
respectively.
Precipitation in Chester County is evenly distributed throughout the year, with a difference of
about 1.2 inches between the wettest month (July) and the driest month (October). Most of the
rainfall in the warm seasons occurs as showers and thunderstorms. An average of thirty storms
occur each year, producing considerable erosion and local flooding when infiltration capacity is
exceeded and surface drainage systems are near maximum capacity. Flooding problems are
exacerbated by the increase in impermeable surfaces associated with commercial development of
the area. The average annual groundwater recharge to underlying carbonate rocks in the Chester
Valley is 21 inches, approximately 45 percent of the total precipitation.
The average amount of snow falling on Chester County ranges from 20 to 30 inches per year, but
usually remains as ground cover only for several days per year. During winter months,
precipitation events are usually more prolonged and less intense than in the summer. Runoff is
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MAL VERN TCE SUPERFUND SITE
reduced in the winter and groundwater recharge is enhanced, unless the ground surface is frozen
Lower winter temperatures reduce evaporation and plants become dormant, greatly reducing
water losses through transpiration.
C. Hydrology
The Site is located in the Chester Valley, underlain by carbonate and clastic rocks of Cambrian
and Ordovician age. The immediate area of the Site is underlain by the Ledger Dolomite and
Elbrook Limestone Formations. Recent overburden deposits across the Site consist of fine-
grained soils overlying bedrock. Overburden deposits range in thickness from 30 to 120 feet.
The bedrock aquifer underlying the Site is generally unconfmed and is recharged by local
precipitation. Groundwater flows through a network of interconnected secondary openings that
include joints, faults, bedding planes, and fractures. In May 1996, the mean depth to
groundwater at the Main Plant Area was 70 feet.
Groundwater at the Main Plant Area flows to the northeast toward the Catanach Quarry at a
gradient of 0.02 ft/ft. The regional potentiometric surface shows that there is a groundwater
divide located between the Main Plant Area and the Former Disposal Area near monitoring well
CC-11. Water level data suggests that the divide may move as a function of quarry activity and
hydrogeologic conditions. Based on the hydraulic gradient and coefficients of hydraulic
conductivity derived from the results of aquifer tests at monitoring wells CC-19 and CC-21,
groundwater flows at a relatively rapid velocity of 0.66 ft/day.
Groundwater beneath the Former Disposal Area/Mounded Area flows to the southwest toward
the Hillbrook Circle development under a relatively flat gradient (0.001 ft/ft). Groundwater
velocities range up to 5 ft/day. (See Figure 4)
This aquifer is a current drinking water source. As recently as 1992, the Philadelphia Suburban
Water Company withdrew water from this aquifer at a production well on Phoenixville Pike to
supply local residents on public water. In addition, Great Valley High School operated a well in
the Ledger Aquifer to provide water for drinking and irrigation.
D. Land Use
The predominant land uses in East Whiteland Township are open space, encompassing 32
percent of total township acreage, and single-family residences and agriculture, each making up
approximately 14 percent. Much of the open area consists of forested uplands and meadows.
Open space and agricultural lands have been decreasing since 1950, as the percentage of
commercial and residential land increases.
VI. NATURE AND EXTENT OF CONTAMINATION
This section discusses the nature and extent of contamination in the soils (surface and
subsurface), groundwater, and surface water and sediment at the Site. This discussion is
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MAL VERN TCE SUPERFUND SITE
presented by area: Main Plant Area, Former Disposal Area/Mounded Area, and Potential
Disposal Area. Within each of these areas, the media (soil-surface and subsurface, groundwater,
surface water and sediment) is then discussed. Domestic well data are presented in the
subsection discussing groundwater contamination at the Former Disposal Area/Mounded Area.
A. Main Plant Area (MPA)
SURFACE SOIL
Twenty-five surface soil samples were collected at the Main Plant Area in the spring of 1996.
Samples were collected from 0 to 6 inches. Samples were collected from background locations
(SS-1, SS-2, and SS-41 through SS-44) and in areas of suspected contamination based on the
results of previous investigations. These areas include the loading dock area (SS-4 through SS-
6); the former UST area (SS-3, SS-7 through SS-9); the existing above-ground storage tank area
(SS-10 through SS-16); and the fill area west of the storage building (SS-17 through SS-20).
Volatile Organic Compounds YVOCs^
VOCs detected in the surface soils were comprised mostly of chlorinated aliphatic hydrocarbons
(CAHs) including: l,2-dichloroethane( 1,2-DCA), total 1,2-dichloroethene (total 1,2-DCE),
MEC, PCE, 1,1,1-TCA, and TCE. Figure 5 shows the contaminant distribution of VOCs for the
surface soil samples collected at the Main Plant Area and indicates where Soil Screening Levels
(SSLs) were exceeded. Acetone and MEC were detected in some samples at concentrations not
substantially above levels detected in laboratory quality control blanks. Excluding these data,
VOCs were detected in 13 of the 25 surface soil samples collected at the Main Plant Area.
Total VOC concentrations range from 2 ug/kg to 235 ug/kg (SS-07). TCE was detected in 7
samples with concentrations ranging from 2 ug/kg (SS-08) to 81 ug/kg (SS-07). PCE was
detected in 12 samples with concentrations ranging from 2 ug/kg to 56 ug/kg (SS-12). MEC
was detected in all 25 surface soil samples collected at the Main Plant Area. Of the 25 samples,
only one, SS-07 (80 ug/kg), was detected at a concentration substantially above the level detected
in the laboratory quality control blank. Table 1 lists the maximum concentrations of
contaminants detected in the surface soil at the Main Plant Area. See Figure 5 for distribution of
VOCs in surface soil.
VOC screening levels were exceeded in the surface soil for 1,2-DCA, MEC, PCE and TCE at
concentrations of 24 ug/kg, 80 ug/kg and 81 ug/kg, respectively.
Semivolatile Organic Compounds fSVQCs')
Eighteen SVOCs were detected in the surface soils at the Main Plant Area. SVOCs were
detected in 15 of the 25 surface soil samples collected at the Main Plant Area at concentrations
substantially above the laboratory quality control blanks. Total SVOCs concentrations range
from 11 ug/kg (SS-10) to 11,103 ug/kg (SS-11) (Figure 6). The total SVOC concentration of
11,103 ug/kg detected at SS-11 is comprised mainly of bis(2-ethylhexyl) phthalate at 11,000
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MAL VERN TCE SUPERFUND SITE
ug/kg. Fifteen SVOCs were detected in the sample SS-15, collected adjacent to the aboveground
storage tank area. Total SVOC concentrations for SS-15 were 8,660 ug/kg. Excluding bis"(2-
ethylhexyl)phthalate, no SVOC was detected in more than 7 of the 25 samples collected. Figure
6 also shows the distribution of the SVOCs in the surface soil at the Main Plant Area, and
indicates samples where criteria have been exceeded.
Inorganics
Twenty-two inorganics (total metals and cyanide) were detected in the surface soils in the Main
Plant Area. Eighteen metals were detected in 19 or more of the surface samples collected at the
Main Plant Area. The highest concentrations of nine metals were detected at SS-17, in the fill
area adjacent to the rear storage building. Table 1 presents the maximum concentrations detected
in the surface soil at the Main Plant Area.
Concentrations of metals in the background samples (SS-1, SS-2, SS-41, SS-42, SS-43, and SS-
44) were comparable to Main Plant Area samples SS-3 through SS-20. SSLs were exceeded for
barium, chromium, nickel and thallium in the surface soils. Twenty-three surface soil samples
with concentrations up to 140 mg/kg, exceeded the SSL (32 mg/kg) for barium. Nineteen
samples with concentrations up to 113 mg/kg exceeded the SSL (19 mg/kg) for chromium. SSLs
were exceeded in 10 samples for nickel and in one sample for thallium.
The pervasive appearance of barium and chromium in all the samples, including background
samples, indicates these metals may occur naturally in the surface soil at the Main Plant Area.
Elevated iron and manganese concentrations in soil are not considered to originate from the .
waste disposal activities at the Main Plant Area. Most of the subsurface soil at the Site is stained
brick-red to red-brown, indicating that the soil contains percentage amounts (of the bulk mineral
matrix) of ferric hydrous oxide minerals. This type of soil is common world-wide in mature
carbonate terrains and is not related to contamination by synthetic organic compounds.
Concentrations of iron and manganese in soil will decline in the presence of significant amounts
(greater than 1.0 mg/1) of Site-related contamination. Anaerobic bacteria utilize iron and
manganese as electron acceptors in the degradation of CAHs and aromatic hydrocarbons. Often,
in soil extensively contaminated with VOCs and SVOCs, iron and manganese hydrous oxides
have been completely leached away leaving a reduced mineral assemblage. Soil color is usually
altered from red-brown to dark-gray.
SUBSURFACE SOILS
Twelve soil borings were installed in the spring of 1996 at the Main Plant Area (Figure 7). The
total depth of the soil borings ranged from 42 feet to 102 feet. Overburden deposits range in
thickness from approximately 30 feet (CC-6) to greater than 100 feet (MPA-8, MPA-9).
Overburden deposits consists of reddish brown and whitish-gray silts and sands interbedded with
clays, silty clays and clayey silts. Gravel and pebble size limestone/dolomite clasts are found
throughout the overburden deposits. Silt and sand lenses beneath the Main Plant Area range in
thickness from less than 1 foot up to 40 feet (MPA-8 and MPA-9).
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Forty subsurface soil samples were collected for laboratory analysis from 12 borings at the Main
Plant Area. Samples were collected from 2-foot intervals in each boring.
Volatile Organic Compounds
VOCs detected in the soil samples collected at the Main Plant Area included: 1,1-dichloroethene
(1,1-DCE), l,l-dichloroethane(l,l-DCA), Total 1,2-DCE, 1,2-DCA, 1,1,1-TCA, TCE, 1,1,2-
TCA, 1,1,2,2-tetrachloroethane (1,1,2,2-PCE), PCE, total xylene, toluene, ethylbenzene,
benzene, 2-butanone, 4-methyl-2-pentanone. VOCs1 considered as possible laboratory
contaminants included MEC, acetone, and chloroform. TCE was detected in 22 of the samples
ranging in concentrations from 1 to 420,000 ug/kg (MPA-8, at 25-27 foot depth). Total 1,2-DCE
was detected in 13 of the samples ranging in concentrations from 1 to 4,000 ug/kg (MPA-6 at 10-
12 foot depth). PCE was detected in 12 samples from 2 to 270,000 ug/kg MPA-6, 10-12 feet
depth). Table 2 outlines the maximum concentrations detected in the subsurface soil at the Main
Plant Area, and the location of the highest detection by parameter.
In borings MPA-1, MPA-11 and MPA-12, designated as background borings, TCE was only
detected (3 ug/kg) in the 10-12 foot sample at MPA-1. Borings MPA-2 and MPA-3 are located
in the loading dock area where distillate condensate was reportedly disposed onto the ground
surface. Low levels of TCE, PCE and 1,1,2-TCA were detected in MPA-3. Generally, VOC
concentrations increased (by 1 to 2 orders of magnitude) with depth at MPA-2. Total VOCs were
detected at 1277 ug/kg in the MPA-2 at the 50-52 foot depth interval. MEC data were flagged as
possibly resulting from laboratory contamination in each of the samples were detected, at
concentrations up to the maximum of 480 mg/kg in MPA-2 at the 50-52 foot depth.
Borings MPA-4, MPA-5, MPA-6, and MPA-7 are adjacent to the former UST area. Low levels
of VOCs (<20 ug/kg) were detected in MPA-5. Moderate levels of VOCs were detected in
samples from MPA-4 and MPA-7. Total VOCs at MPA-7 were detected at less than 100 ug/kg in
both samples. Total VOCs in MPA-4 at the 12-14 foot depth were detected at 260 ug/kg, and at
lower concentrations in the other samples. VOCs were detected in MPA-6 in the 10-12 foot
sample at 497,316 ug/kg, including total benzene, toluene, ethylbenzene, and xylene (BTEX)
concentrations of 152,052 ug/kg, and PCE at 270,000 ug/kg. The highest concentrations for nine
VOCs at the Main Plant Area were detected in MPA-6 at the 10-12 foot interval, which
corresponds to the base of the former USTs excavations. Seven VOCs from this sample
exceeded screening levels.
Borings MPA-8 and MPA-9 are adjacent to the above ground storage tank area. Moderate to
high levels of VOCs were detected in MPA-8 at the 25-27 foot depth and MPA-9 at the 100-102
foot depth. Total VOCs detected in MPA-9 at the 100-102 foot depth were at concentrations of
869 ug/kg, with TCE as the main component at 780 ug/kg. MEC was also detected in MPA-9
samples at concentrations up to 140 ug/kg. Total VOCs were detected in MPA-8 at the 25-27
foot interval at concentrations of 625,214 ug/kg, with TCE as the main component at 420,000
8
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MAL VERN TCE SUPERFUND SITE
ug/kg.
Boring MPA-10 is adjacent to the storage shed. Moderate levels of VOCs were detected in the
MPA-10, 6-8 ft. sample at concentrations of 871 ug/kg, with total xylene as the main component
.at 780 ug/kg. MEC was also detected in MPA-10 at the 6-8 foot interval at 160 ug/kg
Semivolatile Organic Compounds
Twenty-one SVOCs were detected in the subsurface soil samples at the Main Plant Area. The
distribution of SVOCs varied significantly with most SVOCs being present in five or fewer
samples. Of the maximum detected concentrations for the SVOCs in the Main Plant Area,
eighteen were detected in the MPA-6 at the 10-12 foot interval. The total SVOC concentration
in this sample is 18,070 ug/kg. Only the bis(2-ethylhexyl) phthalate concentration exceeded the
soil screening level. The SVOCs detected are constituents of petroleum hydrocarbons and
probably originated from one of the USTs. Table 2 outlines the maximum concentration
detected and the number of times each analyte was detected.
Inorganics
Twenty-one inorganics (total metals and cyanide) were detected in the subsurface at the Main
Plant Area. Sixteen metals were detected in 34 or more samples. Table 2 outlines the maximum
concentration detected and the number of times each analyte was detected.
SSLs were exceeded for arsenic, barium, chromium, and nickel in subsurface samples at the
Main Plant Area. The SSL for barium (32 mg/kg) was exceeded in eleven samples with
concentrations up to 287 mg/kg Seven subsurface samples exceed the SSL for nickel (21
mg/kg) with concentrations up to 62.3 mg/kg. The SSL for chromium was exceeded in four
samples and the SSL for arsenic was exceeded in one sample.
GROUNDWATER
A groundwater sampling program was conducted in the spring and winter of 1996 to determine
the nature and extent of contamination in the groundwater at the Main Plant Area (See Figure 8
for monitoring well locations). This subsection describes the known horizontal and vertical
extent of contamination in the groundwater beneath the Main Plant Area. Groundwater
contamination is defined by analytical results from a monitoring well sampling event in May
1996, and a time-related sampling during 24-hour aquifer tests at CC-19 and CC-21.
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Five existing and four newly-installed monitor wells and one commercial well (CC-JO) were
sampled in the spring and winter of 1996. Eleven samples were collected and analyzed for
organics, metals (total and dissolved), cyanide, and water quality parameters from CC-2, CC-3,
CC-6, CC-7, CO 13, CC-19, CC-20, CC-21, CC-22 and CC-JO. Table 3 and 4 highlight
parameters where MCLs have been exceeded in the groundwater for organics, and total and
dissolved inorganics.
Volatile Organic Compounds
Twenty-three VOCs were detected in the groundwater monitoring wells at the Main Plant Area
with the number of VOCs detected in each well ranging from six to seventeen. VOCs were not
detected in the Led-Jo commercial well (CC-JO). Sixteen VOCs were detected in the
groundwater at CC-06 and CC-07. The primary contaminants disposed at the Main Plant Area,
1,1,1-TCA, TCE and PCE, were detected in all monitoring wells. The maximum detected
concentrations for nine VOCs were detected at CC-06, and maximum detected concentrations for
ten VOCs were detected at CC-07. Total VOCs detected at the Main Plant Area range in
concentration from 20 ug/1 (CC-20) up to 88,732 ug/1 (CC-6). Total VOCs detected at CC-07
were 59,881 ug/1. Figure 8 shows the distribution of VOCs and SVOCs in groundwater at the
Main Plant Area, including compounds that exceeded MCLs.
Primary MCLs were exceeded for eleven VOCS including: 1,1,1-TCA, 1,1,2-TCA, 1,1-DCE,
1,2-DCA, carbon tetrachloride, chloroform, cis-l,2-DCE, MEC, PCE, TCE and vinyl chloride.
The MCL for TCE was exceeded in groundwater at all nine wells at the Main Plant Area with'
concentrations ranging from 8.5 ug/1 to 53,900 ug/1. The MCL for PCE was exceeded in seven
wells with concentrations ranging from 5.9 ug/1 to 7110 ug/1.
Monitoring wells on the eastern (CC-02) and western (CC-20 and CC-22) edge of the Main Plant
Area contain low levels of VOC contamination. Hydraulically, CC-2 is the most upgradient well
at the Main Plant Area, but displays up to 65 ug/1 total VOCs, including TCE above the MCL
(Figure 10). The four most contaminated wells are within the Main Plant Area in the former
UST area and the condensate distillate disposal area. VOC concentrations appear to decrease
radially outward from wells CC-03, CC-06, CC-07, and CC-13 as shown in Figure 9. VOC
concentrations in CC-13 are an order of magnitude less than the adjacent wells CC-06 and CC-
07 CC-13 monitors a deeper interval (124 to 178 ft below ground surface) than adjacent wells
CC-06 and CC-07. The vertical extent of contamination decreases with depth and with
horizontal distance from the main contaminant source area. The monitoring wells that are in or
adjacent to the main contaminant source area (CC-03, CC-06, CC-07 and CC-13) have two to
three orders of magnitude higher concentrations than the monitoring wells that are located
outside the Main Plant Area (CC-19 through CC-22) or at a greater distance from the source area
(CC-02).
The contaminant plume at the Main Plant Area extends approximately 120 feet from the highly
contaminated core defined by wells CC-6 and CC-7 to a projected isopleth of 10 ug/1 (Figure 10).
Monitor wells at the Main Plant Area are not well situated to characterize the longitudinal
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boundary of the plume. The contaminant plume is approximately 200 feet wide. The total
length of the plume is not known at this time.
Semivolatile Organic Compounds
Low levels of SVOCs (less than 3 ug/kg) were detected in the groundwater at the Main Plant
Area and at CC-JO. SVOCs detected in three separate wells at the Main Plant Area include 1,2-
dichlorobenzene, phenanthrene, and di-n-butyl phthalate. Bis(2-ethylhexyl) phthalate was
detected in CC-JO. SVOCs in the groundwater did not exceed MCLs.
Inorganics
Twenty-four inorganics (total metals and cyanide) were detected in the groundwater at the Main
Plant Area and CC-JO.
Primary MCLs were exceeded at CC-06 for total concentrations of antimony, barium, beryllium,
cadmium, chromium, nickel and thallium. Secondary MCLs and action levels were exceeded for
aluminum (total), iron (total and dissolved), lead (total) and manganese (total and olved) for a
number of wells. Table 4 shows which metals exceeded MCLs in the groundwate. ;he Main
Plant Area.
DNAPL Investigation
The RI contained an integrated approach to assess the Main Plant Area for the potential
distribution of DNAPLs using existing analytical and field observation data. Both groundwater
and soil quality data were evaluated to determine the presence of DNAPLs using various
screening methods. These techniques included EPA guidance procedures for evaluating
groundwater quality data, a method for evaluating analytical data from soils following Feenstra,
et. al. (1991), head space screening results from soil samples, and visual observations of
groundwater samples using a nonvolatile, hydrophobia dye.
As DNAPLs often accumulate in small pools in the vadose and saturated zones, the likelihood of
encountering DNAPLs in a soil sample from a vertical boring or groundwater from a
conventional monitor well is remote, unless the boring is drilled directly through the DNAPL
pool. Consequently, screening methods that evaluate contaminant concentrations in several
different media with several techniques must be employed to determine the potential occurrence
of DNAPLs. The database consisted of groundwater and soil analytical data, headspace
screening results and a dye survey from the latest round of groundwater sampling.
Results of the screening analysis indicated that DNAPLs may occur in, or upgradient of monitor
wells CC-6, CC-7, and CC-13. All three wells are located directly below the former UST area.
Soil quality data indicated DNAPLs may occur in the vadose zone at 10-12 feet below grade in
MPA-6, and 25-27 feet below grade in MPA-8. Headspace correlation based on a headspace-
threshold measurement of 150 ppm identified potential DNAPLs in borings MPA-2, 3, 4, 6, and
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B. Former Disposal Area/Mounded Area (FDA/MA)
The source of soil contamination detected at the Former Disposal Area/Mounded Area were
buried drums containing still bottoms from Chemclene's solvent recycling process
Approximately 300 drums and adjacent soils were excavated and removed from the area for
disposal at an approved facility between 1981 and 1984. Chemclene removed a second cache of
drums from the Mounded Area in 1990; however, contaminated soil was left in place
SURFACE SOIL SAMPLES
In April 1996, a total of 21 surface soil samples (including QA/QC samples) were collected from
the Former Disposal Area/Mounded Area at depths between 0 and 6 inches below ground
surface. Surface soil samples were submitted for VOC and SVOC, metal, and cyanide analyses.
Of the surface soil sample locations in the Former Disposal Area/Mounded Area (designated SS-
21 through SS-40), nine locations were within the fenced area, four were within the Mounded
Area, and the remaining seven were northwest and southeast of the fenced excavation area
(Figure 11).
Volatile Organic Compounds
PCE was the most commonly detected Site-related contaminant in the surface soil samples. PCE
was detected in ten samples, with a highest concentration of 130 ugVkg in SS-28, and
concentrations of less than 10 ug/kg in the remaining nine samples. PCE was the only Site-
related VOC detected in excess of the SSL of 40.0 ug/kg (Figure 11). Other organic
contaminants detected at low levels in surface soils were 1,1,1-TCA, 1,2-DCE, and TCE.
Distribution of VOCs in surface soils and the VOCs that exceed SSLs are shown in Figure 10.
Semivolatile Organic Compounds
Of the surface soil sampling locations at the Former Disposal Area/Mounded Area, bis(2-
ethylhexyl)phthalate was detected in all but SS-21 and SS-33, at levels ranging from 55 (SS-35)
to 2400 ug/kg (SS-25). Bis(2-ethylhexyl)phthalate was the only SVOC detected in 15 of the 20
samples, and was also detected in field blanks submitted with the surface soil samples. The
distribution of SVOCs in the surface soil at the Former Disposal Area/Mounded Area is shown in
Figure 12.
The highest total concentration of SVOCs was detected in sample SS-27 (1,747 ug/kg) in the
Mounded Area. SVOCs were not detected in excess of the SSLs.
Inorganics
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The inorganic composition of the Former Disposal Area/Mounded Area surface soils is
considered to be generally representative of background conditions, although several metals were
detected at levels exceeding SSLs. These metals were: barium, cadmium, chromium, nickel,
selenium, and thallium. Barium was detected above the SSL of 32 mg/kg in all 21 of the surface
soil samples, at levels ranging from 36.3 (SS-32) to 157 mg/kg (SS-40). Cadmium was detected
above the SSL of 6 0 mg/kg in three samples: SS-23 at 8.6 mg/kg; SS-26 at 36 4 mg/kg; and SS-
37 at 10 mg/kg. Chromium was detected above the SSL of 19.0 mg/kg in 16 samples, with a
maximum concentration of 40.9 mg/kg detected in SS-28. Nickel was detected above the SSL of
21 mg/kg in three samples: SS-26 at 25 mg/kg; SS-28 at 21.9 mg/kg, and SS-31 at 23.5 mg/kg
Selenium was detected above the SSL of 3.0 mg/kg in one sample, SS-40, at 3.9 mg/kg.
Thallium was detected above the SSL of 0.4 mg/kg in three samples: SS-25 at 1.6 mg/kg; SS-26
at 3.1 mg/kg; and SS-27 mg/kg. Cyanide was detected in two of the surface soil samples: SS-
24, at 0.68 mg/kg; and SS-36, at 21.5 mg/kg. There are no applicable SSLs for cyanide in soils
SUBSURFACE SOIL SAMPLES
The subsurface at the Former Disposal Area/Mounded Area is defined by a total of six soil
borings (designated FDA-1 through FDA-6), drilled in March 1996 to depths ranging from 27 to
62 feet below ground surface (Figure 13). The subsurface consists of recent unconsolidated
overburden deposits overlying the Cambrian Ledger Dolomite. The Ledger Formation was
encountered only in boring FDA-4, at a depth of approximately 60 feet below ground surface.
Overburden deposits generally consist of silts and sands interbedded with clays, silty clays, and
clayey silts. Subangular limestone/dolomite clasts are found throughout the overburden deposits.
Volatile Organic Compounds
Eighteen VOCs were detected in 19 subsurface soil samples at the Former Disposal
Area/Mounded Area. Most VOCs were detected in nine or fewer samples. PCE, MEC, and
acetone were detected more frequently. PCE was detected in 16 of the 19 subsurface samples
although concentrations in nine samples may have resulted from laboratory blank contamination.
Concentrations of total VOCs (excluding those detected in laboratory quality control blanks)
range from 3 ug/kg (FDA-2 at 25-27 foot) to 505,000 ug/kg (FDA-5 at 8-10 foot). VOCs that
may be present from laboratory contamination include 1,2-DCE, MEC, acetone, PCE, and
xylenes. Soil samples collected between 2 and 10 ft below ground surface at FDA-3 and FDA-5
and between 3 and 22 ft below ground surface at FDA-4 exhibited total VOC concentrations in
excess of 1,000 ug/kg.
The highest concentration of an individual VOC was PCE at 410,000 ug/kg in FDA-5 at 8-10
feet. This maximum concentration exceeded the SSL (40 ug/kg) for PCE by several orders of
magnitude. Maximum detected concentrations for ethylbenzene, MEC, PCE, TCE, and xylenes
were also detected in this sample. VOCs that were commonly detected at concentrations above
SSLs included PCE, TCE, 1,1,1-TCA, 1,1,2,2-TCA, 1,1-DCA, 1,2-DCE, 1,2-DCA, and xylenes
Borings FDA-4 and FDA-5 are located in or adjacent to the Mounded Area. VOC
contamination at the Mounded Area generally decreases with depth. Total VOCs in samples
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MAL VERN fC£ SUPERFUND SITE
deeper than 20 feet below grade at the Former Disposal Area/Mounded Area are less than 100
ug/kg.
Low le'vels of VOC contamination were detected at soil borings FDA-1, FDA-2, and FDA-6,
however, these contaminants were also detected in laboratory quality control blanks and appear
to result from laboratory rather than Site-related contamination.
Semivolatile Organic Compounds
SVOCs were detected in 11 of the 19 subsurface soil samples collected from the Former
Disposal Area/Mounded Area. These samples were from borings FDA-3, FDA-4, and FDA-5
The most commonly detected SVOCs, including 2-methylnaphthalene, bis(2-
ethylhexyl)phthalate, di-n-butyl phthalate, naphthalene, and phenanthrene were detected in 8 to
11 samples. The remaining SVOCs were detected in fewer than 4 samples each. Total SVOC
concentrations exceeding 1,000 ug/kg were detected in samples from depths of 2-22 feet at FDA-
3, FDA-4, and FDA-5.
Inorganics
Thirteen metals were detected in the 19 subsurface soil samples collected at the Former Disposal
Area/Mounded Area. The list of metals in the subsurface soils is generally similar to that of the
surface soils. SSLs for barium, chromium, and thallium were exceeded for one or more of the
subsurface soil samples. Barium was detected above the SSL of 32 mg/kg in FDA-2 at 20-22
feet (33.2 mg/kg); and in FDA-4 at 8-10 feet (60.4 mg/kg). Chromium was detected above the
SSL of 19.0 mg/kg in FDA-1 at 25-27 feet (19.9 mg/kg); FDA-2 at 20-22 feet (20.1 mg/kg);
FDA-3 at 12-14 feet (22.6 mg/kg); FDA-3 at 8-10 feet (21.3 mg/kg); and FDA-4 at 8-10 feet
(20.7 mg/kg). Thallium was detected above the SSL of 0.4 mg/kg in four samples. FDA-1 at
10-12 feet (0.8 mg/kg); FDA-3 at 12-14 feet (0.73 mg/kg); FDA-4 at 20-22 feet (1.3 mg/kg); and
FDA-4 at 3-5 feet (2.2 mg/kg). However, all thallium levels, except that of FDA-3 were detected
at similar levels in the field quality control blanks.
GROUNDWATER
This subsection describes the known horizontal and vertical extent of contamination detected in
groundwater underlying the Former Disposal Area/Mounded Area. Groundwater contamination
in this area is defined by analytical results for groundwater samples collected from a total of nine
monitoring wells. Concentrations of detected compounds are compared with the corresponding
MCLs.
Groundwater samples were collected from existing Former Disposal Area/Mounded Area
monitor wells (CC-5, -9,-10,-l 1, and -14) and newly installed wells (CC-15 through CC-18) in
April and May 1996. Unfiltered groundwater samples were analyzed for VOCs, SVOCs, total
metals, and cyanide, and for alkalinity, chloride, low concentration metals, nitrate, nitrite, silica,
sulfate, total dissolved solids (TDS), and total organic carbon. Filtered groundwater samples
were analyzed for dissolved metals. Conventional water quality parameters (alkalinity, nitrate,
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silica, sulfate, TDS) were used to characterize background groundwater chemistry.
Volatile Organic Compounds
Twenty VOCs were detected in the groundwater at the Former Disposal Area/Mounded Area.
Total VOC concentrations ranged from a low of 8.1 ug/1 in CC-11 to a high of 3,298 ug/1 in CC-
5. Figure 14 presents the distribution of VOCs in the monitoring wells at the Former Disposal
Area/Mounded Area. VOCs that exceeded groundwater MCLs are underlined.
The following VOCs were detected at levels exceeding the MCLs: 1,1-DCE at wells CC-5, CC-
15, and CC-16; 1,2-DCA at wells CC-5 and CC-16; cis-l,2-DCE at wells CC-5, CC-16, and CC-
17; PCE at wells CC-5, CC-9, CC-15, CC-16; and TCE at wells CC-5, CC-9, CC-14, CC-15,
CC-17, and CC-18.
An isopleth map presenting total VOC concentrations was created with analytical data from the
May 1996 monitor well sampling event and June 1996 domestic well sampling event. The
domestic well data are discussed in the next section. The monitoring wells exhibiting the highest
concentration of VOCs (CC-5, CC-15, CC-16, and CC-17) are configured in a line extending
along the south and southwest portion of the Former Disposal Area/Mounded Area. VOC
contamination in CC-5 is 1 to 2 orders of magnitude higher than the surrounding wells CC-9,
CC-10, CC-15, CC-16, CC-17, and CC-18, all of which are within a distance of 50 to 250 feet
from CC-5. The VOC contaminant plume, centered at CC-5, extends from the Former Disposal
Area/Mounded Area to the residences along Hillbrook Circle as shown in Figure 15. Due to the
relatively flat potentiometric surface in the area encompassing the Former Disposal
Area/Mounded Area, contamination appears to spread laterally upgradient as well as migrating
downgradient. In this mode of migration, contamination has moved toward CC-14, before
migrating downgradient. The plume is elliptical and appears discontinuous in Hillbrook Circle.
Total VOC concentrations within the Hillbrook Circle Development are up to 180 ug/1 at a
distance of 2,100 feet from the Former Disposal Area/Mounded Area.
Semivojatile Organic Compounds
SVOCs were not detected in concentrations above the detection limit in groundwater from the
Former Disposal Area/Mounded Area monitor wells.
Inorganics
Total metals that were detected in Former Disposal Area/Mounded Area wells in concentrations
in excess of the corresponding MCLs were aluminum at CC-10 and CC-14, beryllium at CC-14,
cadmium at CC-11; iron at CC-5, -10, -11, and -14; and manganese at CC-10, -11, and -14.
Elevated metal concentrations at CC-11 are the result of low pH (6.42) at this well and represent
local background conditions, rather than Site-related contamination.
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Of the dissolved metals, iron and manganese levels, both in CC-11, exceeded associated MCLs.
Cyanide was not detected in the Former Disposal Area/Mounded Area groundwater samples
C. Domestic Wells
Groundwater samples were collected from domestic wells in the vicinity of Chemclene during
sampling events conducted in June, August, and December of 1995, and of June 1996. Samples
were analyzed for VOCs and SVOCs. This subsection presents analytical results from the June
1996 sampling event, and compares total VOC concentrations of unfiltered samples with results
of corresponding unfiltered samples from the August 1995 sampling event. Only 15 unfiltered
samples (including a duplicate) were collected in August 1995. Only unfiltered data are
presented because filtered samples represent the filter efficiency; and in general, only trace or
nondetectable levels of VOCs have been detected in domestic wells that have filter systems.
Samples were collected from a total of 49 domestic wells in June 1996. Both unfiltered and
filtered samples were collected from 18 of the 49 domestic wells, for a total of 67 samples.
Volatile Organic Compounds
VOCs were detected at concentrations above the detection limits in samples from 20 of the 49
domestic wells during the June 1996. VOCs were detected in both filtered and unfiltered
samples from five of the domestic wells. Total VOC concentrations were greater than or equal to
10 ug/1 in eight of the 49 domestic wells: DW-6B, 9B, 16B, 36A, 36B, 41B, 57B, and 58B. A
maximum total VOC concentration of 289 ug/1 was detected in the sample from DW-41B.
Three organic contaminants (1,1-DCE, PCE, and TCE) were detected at levels exceeding
corresponding MCLs. A concentration of 18 ug/1 of 1-1 DCE was detected in DW-41B,
exceeding the MCL of 7.0 ug/1. PCE was detected at or above the MCL of 5.0 ug/1 in DW-41B
(38 ug/1), DW-58B (14 ug/1), and DW-65B (5.0 ug/1). TCE was detected in excess of the MCL
of 5.0 ug/1 in the following wells: DW-36B (36 ug/1); DW-41 (140 ug/1); DW-6B (34 ug/1); DW-
9B (7.0 ug/1); DW-57B (23 ug/1); DW-58B (110 ug/1); and DW-67B (7.0 ug/1).
As shown in Figure 14, the distribution of VOCs detected in groundwater at the Site is defined
by a major plume extending to the southeast from the Former Disposal Area/Mounded Area, and
a second area of groundwater contamination to the southeast. These areas of contamination do
not form a continuous plume, but are separated by several wells in which VOCs have not been
detected. This distribution pattern may be a result of differences in domestic well depth and
construction
Based on June 1996 analytical data, selected wells were compared to results from August 1995,
total VOC concentrations had increased in 5 samples, decreased in 8 samples, and remained the
same (nondetect) in 2 samples. The highest total VOC concentration in August 1995 was 121
ug/1 in well DW-36B, compared with 55 ug/1 in the same well in June 1996. Well DW-36B
exhibited the greatest change in VOC concentrations between the 2 sampling intervals, with the
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MALVERN TCE SUPERFUND SITE
other wells showing differences of only a few ug/l from August 1995 to June 1996. Table 5
presents the total VOC concentration of selected domestic wells for August 1995 and June 1996
Semivolatile Organic Compounds
SVOCs were detected at concentrations above the detection limit in samples from four of the 49
domestic wells. Bis(2-ethylhexyl)phthalate was detected in DW-36B (8 ug/l); in DW-52B (16
ug/l); and in DW-55B (23 ug/l). Di-n-butyl-phthalate was detected in DW-61 at concentrations
of 39 and 22 ug/l (duplicate sample).
D. Potential Disposal Area
The Potential Disposal Area was identified during an examination of aerial photographs from the
1950's and 1960's. This area exhibited signs of excavation activities, stressed vegetation, and
discarded debris. The Potential Disposal Area lies in a wooded area approximately 200 feet west
of the Main Plant Area. Based on the aerial photographs, the Potential Disposal Area is
approximately 100 feet by 100 feet in size. The Potential Disposal Area lies between a
residential development to the north and the gas pipeline right-of-way to the south. A small
stream, which flows from the residential properties, bounds the Potential Disposal Area to the
west. Small mounds of soil and concrete blocks were scattered throughout the area. Debris in
the Potential Disposal Area included auto parts, an empty crushed drum, a barbed wire fence
along the northern boundary, and miscellaneous trash. To determine the extent of the Potential
Disposal Area, a geophysical grid for a magnetic survey was configured so that the boundaries of
the grid extended past the obvious boundaries of the Potential Disposal Area. The geophysical
grid in the Potential Disposal Area encompassed an area 160 feet wide (east-west) by 120 feet
long (north-south). (See Figure 16)
A geophysical survey, soil gas survey, and subsurface boring program were conducted in the
winter of 1995 through spring of 1996 to determine the nature and extent of contamination at the
Potential Disposal Area.
The application of a magnetometer/gradiometer survey at the Potential Disposal Area indicates
that a small amount of metal is strewn about the ground surface. Magnetic field and gradient
anomalies were generally small in area and less than 100 gammas. Anomalies associated with a
number of buried drums are usually greater than 200 gammas in strength. Nearly all significant
magnetic field and gradient anomalies above 50 gammas and 5 gammas per foot respectively,
were associated with some form of metal lying at the ground surface. These results suggest that
drums were probably not buried at the Potential Disposal Area. Results of the
magnetometer/gradiometer survey were consistent with results of the soil gas survey and soil
boring program at the Potential Disposal Area.
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Soil Gas Survey
Fourteen soil gas samples were collected in March 1996 at the Potential Disposal Area. Soil-gas
collectors were placed in areas identified as suspect following the geophysical survey and several
Site walk-overs. Additional devices were installed to provide adequate areal coverage. Soil gas
samples were analyzed for eight TCE-related VOCs listed in Table 6. VOCs were not detected
in the soil gas samples collected at the Potential Disposal Area.
Subsurface Soil
The subsurface at the Potential Disposal Area is defined by six soil borings (Figure 16). Soil
borings were drilled to a maximum depth of 27 feet below ground surface. Bedrock was not
encountered at the Potential Disposal Area in any of the soil borings. Overburden deposits at the
Potential Disposal Area consist of reddish brown and whitish-gray silts and sands interbedded
with clays, and clayey silts and sands. Gravel and pebble size limestone/dolomite clasts are
found throughout the overburden deposits but occur in greater density in the 2 to 6 foot interval.
Silt units beneath the Potential Disposal Area range in thickness from 1 foot (PDA-3) to 19 feet
(PDA-5). Sand units range in thickness from 2 feet (PDA-4) to 25 feet (PDA-3) at the Potential
Disposal Area.
Sixteen subsurface soil samples were collected for laboratory analysis from the 5 borings at the
Potential Disposal Area. Samples were collected from three 2-foot intervals in each boring.
Since organic vapors were not detected in the borings, the intervals sampled for laboratory
analysis were chosen based on lithologic changes to achieve horizontal and vertical coverage,
and to determine vertical extent of contamination, if any exists.
Volatile Organic Compounds
A low level of toluene was detected in one sample at the PDA-2 at 25-27 foot depth. VOCs
detected but at concentrations not substantially above levels detected in laboratory blanks)
include acetone, MEC, and total xylene. MEC was detected in all sixteen soil samples collected
at the Potential Disposal Area ranging in concentrations from 7 to 21 ug/kg (all B flagged).
SSLs were exceeded for MEC (10 ug/kg) in 15 subsurface soil samples, all of which were B
flagged and associated with possible blank contamination.
Semivolatile Organic Compounds
A low concentration of diethyl phthalate was detected in one sample at the PDA-5, 25-27 feet.
(42 ug/1). Other SVOCs detected in the samples but flagged with a B qualifier (concentrations
not substantially above levels detected in laboratory blanks) included bis(2-ethylhexyl) phthalate
(Figures 4-26 and 4-27). SSLs were not exceeded for SVOCs in the subsurface at the Potential
Disposal Area.
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Inorganics
Twenty metals and cyanide were detected in the subsurface at the Potential Disposal Area.
Seventeen metals were detected in 10 or more of the samples collected in the subsurface at the
Potential Disposal Area.
SSLs were exceeded for arsenic, barium, chromium, and selenium in the subsurface at the
Potential Disposal Area. SSLs were exceeded for arsenic and barium in two samples with
maximum concentrations of 16.2 mg/kg (PDA-1 at 6-8 feet) and 53.2 mg/kg (PDA-5 at 8-10
feet), respectively. SSLs were exceeded for chromium and selenium in one sample at
concentrations of 22. 1 mg/kg and 23.6 mg/kg (PDA-4 at 25-27 ft.) respectively. These metals
were present at elevated levels in the background soil sample (FDA-2), and may therefore
represent ambient soil conditions. With the exception of selenium, concentrations of all the
metals lie within average range for background locations in the eastern United States.
E. Previous Investigation Data
Several soil gas surveys, soil sampling programs, and groundwater sampling events have been
conducted at the Site. Two soil gas surveys were performed at the Site between 1989 and 1993.
Soil gas surveys were performed at the Main Plant Area and Former Disposal Area/Mounded
Area in December 1989, and a second soil gas survey was conducted in the mounded area of the
Former Disposal Area/Mounded Area in October 1992.
Total VOC soil gas concentrations ranged from undetected to 530 ppm in the Former Disposal
Area/Mounded Area. VOC concentrations were slightly lower farther from the Mounded Area,
but most samples still showed discernible levels of contamination. Total VOC soil gas
concentrations at the Main Plant Area ranged from 1.73 ppm to 1,035 ppm. The area southeast
of the distillation building had the highest readings.
The soil gas surveys indicated the presence of VOC contamination of the soil. This data was not
used quantitatively in the risk assessment due to the nature of the data, but was used to indicate
areas of potential concern for inhalation exposure.
Several soil sampling programs have been conducted at the Main Plant Area and Former
Disposal Area/Mounded Area since 1990. Soil borings were installed at the main plant to
investigate contamination in soils below the former USTs, at the condensate disposal area (area
southeast of the distillation building), and at the garage loading dock. Borings have also been
installed around the excavations at the Former Disposal Area/Mounded Area created by the
removal of drums and debris, and the Mounded Area. Surface soil samples have been collected
from the Main Plant Area and the Former Disposal Area/Mounded Area.
Soil borings installed in the excavation area of the Former Disposal Area/Mounded Area in 1990
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indicated the presence of VOCs (6 - 96 ug/kg total VOC). Soil borings installed in the Mounded
Area in 1992 showed much higher levels of VOCs (up to 224,400 ug/kg total VOC).
Constituents detected included 1,1,1-TCA, PCE, TCE, 1,1,2-TCA, 1,1-DCE, 1,2-DCA, and
bromoform. Similar compounds and concentrations were detected in the soil borings sampled in
1996 from the Mounded Area. Additionally, low levels of PAHs were detected in the samples
collected in 1996. Soil borings were not sampled from the Former Disposal Area excavation
area in 1996. Surface soil samples were collected at the mounded area of the Former Disposal
Area/Mounded Area in February 1991 and March 1996. VOCs were detected during both
sampling events, and the concentrations in 1996 were lower than the 1991 concentrations.
Soil boring samples collected from the Main Plant Area in January 1990 and March 1996
indicated that the highest contamination was present in the area from which the USTs were
removed. Surface soil samples were collected from the Main Plant Area in March 1996. VOCs
were detected in many of the samples.
VD. SUMMARY OF SITE RISKS
Following the Remedial Investigation, analyses were conducted to estimate the human health and
environmental hazards that could result if contamination at the Site is not cleaned up. These
analyses are commonly referred to as risk assessments and identify existing and future risks that
could occur if conditions at the Site do not change. The Baseline Human Health Risk
Assessment (BLRA) evaluated human health risks and the Ecological Risk Assessment (ERA)
evaluated environmental impacts from the Site.
A. Human Health Risks
The BLRA assesses the toxicity, or degree of hazard, posed by contaminants related to the Site,
and involves describing the routes by which humans could come into contact with these
substances. Separate calculations are made for those substances that are carcinogenic (cancer
causing) and for those that are non-carcinogenic, but can cause other adverse health effects.
The primary objective of the risk assessment conducted was to assess the health risks to
individuals who may have current and future exposure to contamination present at and migrating
from the Site under existing site conditions. The risk assessment is comprised of the following
components:
• Identification of Chemicals of Potential Concern (COPCs) - identify and
characterize the distribution of COPCs found on-Site.
• Exposure Assessment - identify potential pathways of human exposure, and
estimate the magnitude, frequency, and duration of these exposures.
• Toxicity Assessment • assess the potential adverse effects of the COPCs.
• Risk Characterization - characterize the potential health risks associated with
exposure to site related contamination.
Each of these steps is explained further below.
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I. Identification o/COPCs
The identification of COPC includes data collection, data evaluation, and data screening steps
The data collection and evaluation steps involve gathering and reviewing the available site data
and developing a set of data that is of acceptable quality for risk assessment. This data set is then
further screened to reduce the data set to those chemicals and media of potential concern. The
data used for the quantitative risk analysis were all validated prior to use in the risk assessment.
Sail
The only soil data that have been validated are the data collected during the RI conducted by
EPA. Therefore, the 1996 soil sampling data were used for the quantitative risk assessment. Soil
boring data collected from between 0-12 feet were used to evaluate subsurface exposure. Surface
soil samples collected from 0-0.5 feet were used to evaluate surface soil exposure. Soil samples
were analyzed for VOCs, SVOCs, metals, and cyanide.
The 1996 soil data were grouped into the six exposure areas previously discussed for the risk
assessment. The areas include the soils at the Former Disposal Area/Mounded Area, the UST
area, the aboveground storage tank area, the area southeast of the distillation building, and the
area south of the garage at the main plant.
Groundwater
Groundwater data from August 1994 and May 1996 were used for the risk analyses. These were
the only data collected at the Site that have been validated. In general, VOC concentrations
appear to have remained the same or have slightly decreased over time. Therefore, use of the
1994 and 1996 groundwater data are representative of current Site conditions.
The three most contaminated wells within each plume were selected for the quantitative risk
assessment. Wells CC-6, CC-7, and CC-13 were used to represent worst-case groundwater at the
Main Plant Area, and wells CC-5, CC-15, and CC-16 were used to represent worst-case
groundwater at the Former Disposal Area/Mounded Area.
Risks associated with use of the domestic wells were also evaluated. Data from wells without
carbon filters were used to evaluate current residential risks and data collected prior to the filter
(or after the filter if breakthrough was detected) for the wells equipped with carbon filters were
used to evaluate potential future residential risks.
Background Samples
Five background surface soil samples and four background soil borings have been collected at
the Site. Only two samples from the background soil borings are useable for the risk assessment
due to the depth of the samples used to represent subsurface soil exposure.
Data from the Philadelphia Suburban Water Company (PSWC) Great Valley well was
representative of background conditions in the aquifer beneath the Site. The inorganic data
collected from the Great Valley well in October 1992, prior to the well becoming contaminated,
was used as the background groundwater for the risk assessment.
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Selection of Chemicals of Potential Concern
The COPC selection process was conservative, to ensure selection of the most constituents.
Selection of COPCs was based on the criteria presented in EPA Region III guidelines The
maximum concentration of each detected constituent in each media was compared to the
following criteria to select the COPCs per area. If the maximum concentration of a constituent
exceeded each of the criteria, the constituent was selected as a COPC.
• Comparison with Health-based Criteria. The maximum detected chemical
concentrations in groundwater and soil were compared with risk-based
concentrations (RBCs) that were developed using current toxicity factors in the
exposure formulas provided by EPA Region III. These screening level RBCs
were based on a target hazard index of 0.1 and a target cancer risk of 1 x 10-6 For
soils, the cross-media protection criteria (for air) were developed using the EPA
Soil Screening Guidance. Soil saturation concentrations were calculated and used
as the screening value if they were less than the soil RBC. Constituents with
maximum detected concentrations below the RBC or soil saturation values were
eliminated from the COPC list.
• Comparison with Background Samples. The 95 percent upper tolerance limit
(95% UTL) was calculated for each inorganic constituent detected in the set of
background soil samples. For potential source areas where the maximum detected
concentration was greater than the background 95% UTL (or the maximum
background concentration if the 95% UTL is greater than the maximum), the
inorganic constituent was retained as a COPC.
• Comparison with Recommended Dietary Allowances (EDAs): Chemicals which
are human nutrients, present at low concentrations (i.e., only slightly elevated
above naturally occurring levels), and toxic only at very high doses were
eliminated from the quantitative risk analysis. These constituents are calcium,
magnesium, potassium, and sodium. All of the human nutrients detected in
groundwater and soil, except for manganese in the Main Plant Area plume, result
in intakes below RDAs. Ingestion of groundwater from the Main Plant Area
plume by future adult residents would result in an intake of 300 mg/day, which
slightly exceeds the RDA of 280 mg/day. This is not a significant exceedence,
and manganese is not a significant contributor to the intake and resulting potential
health effects.
Iron, which is also considered a human nutrient, was evaluated quantitatively in the risk
assessment because there is a provisional toxicity value for iron. Ingestion of soil at the Former
Disposal Area excavated area would result in an intake of 11.5 mg/day by a child which slightly
exceeds the RDA for a child of 10 mg/day. Ingestion of groundwater from the Main Plant Area
plume would result in an adult intake of 640 mg/day for an adult resident and an intake of 320
mg/day for a child resident, which both exceed the RDA of 15 mg/day and 10 mg/day for an
adult and child, respectively.
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Chemicals of Potential Concern
Table 7 identifies the chemicals that were selected as COPC based on the above screening
methodology for each of the six potential source areas (soil) and the two groundwater plumes
There were no COPC present at the area south of the garage, therefore this area was not
considered a potential source area and a quantitative risk evaluation was not carried out
The domestic wells located off the Chemclene property were also screened using the above
screening and data evaluation methods. The data were separated into two separate sets, domestic
wells with filters and domestic wells without filters. All of the domestic wells that were sampled
in 1995 and had at least one VOC detected were screened for COPC.
Although the ROD focuses on the chemical risk-drivers at the Site, other contaminants not
specifically discussed in the ROD were also observed in environmental samples at noteworthy
concentrations and are a concern to EPA. (A detailed evaluation of all chemicals exceeding risk
screening criteria, i.e. - CoPCs, is presented in the Baseline Risk Assessment of the Remedial
Investigation Report.)
2. Exposure Assessment
An exposure assessment involves three basic steps: 1) identifying the potentially exposed
populations, both current and future; 2) determining the pathways by which these populations
could be exposed; and 3) quantifying the exposure. Under current Site conditions, the BLRA
identified potential populations as having the potential for exposure to Site-related contaminants,
either currently and/or in the future. The migration pathways for the contamination from the
source areas include: volatilization of the chlorinated solvents from soil, subsurface soil and
groundwater, downward migration of the VOCs from soil to the groundwater, and lateral
down gradient transport of VOCs in the groundwater.
Current Land
Chemclene currently sells hydraulic oil, industrial cleaning solvents, hydraulic fluid, and
hydrogen peroxide, and operates a hauling operation from the Main Plant Area of the Site.
Therefore, current populations which could be exposed include the employees and visitors of
Chemclene Corporation. Chemclene uses a local on-Site well for process and wash water at the
plant. This water is not used as a potable water supply. Chemclene uses water from domestic
well DW-010 or bottled water as a potable water supply for site workers. The Main Plant Area
and pan of the Former Disposal Area/Mounded Area are not physically separated from the
surrounding land and are accessible to the off-Site public under current conditions. Therefore,
potentially exposed populations to the Main Plant and unfenced portions (mounded area) of the
Former Disposal Area/Mounded Area include trespassers. Individuals currently using the
Chemclene property may be exposed to contaminants in the surface soil.
Another population which currently could be exposed to Site contaminants is the residents that
live hydraulically downgradient of the Chemclene property. Residents near the Chemclene
property obtain their potable water from private groundwater wells. Twenty of the 51 residential
wells in the vicinity of the plant have carbon filters to treat organic contamination. Data obtained
from domestic well sampling indicate elevated levels of several organic constituents in
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groundwater that are Site-related. These persons may be exposed to constituents in groundwater
during potable use.
In summary, the populations potentially exposed and the possible pathways under current land
use include:
1 Chemclene employees working outdoors potentially exposed through incidental
ingestion, dermal contact, and inhalation of volatiles and fugitive dust from
surface soils.
2. Trespassers playing on or walking across the Chemclene property potentially
exposed through incidental ingestion, dermal contact, and inhalation of volatiles
and fugitive dust from surface soils.
3. Residential groundwater users downgradient of Chemclene property potentially
exposed through ingestion of and dermal contact with groundwater, and inhalation
of volatiles from groundwater while showering or bathing.
Potential Future Uses
The predominant land use in East Whiteland Township is agriculture, rural residential, and open
space. However, agriculture and open space areas are decreasing as the area is being converted
to residential and commercial properties. The future land use for the Site and surrounding area is
expected to be similar to the current land use, either commercial or residential. The Chemclene
property is currently commercial, but could possibly be converted to a residential area in the
future. This property could also be used by a different owner for commercial operations. This
may entail expanding the number of workers, and may include using the groundwater as a
potable water supply. Also, construction activities may take place at the Site.
In summary, the populations potentially exposed and the possible exposure pathways under
future land use include:
]. Construction workers potentially exposed through incidental ingestion, dermal
contact, and inhalation of volatiles and fugitive dust from surface and subsurface
soils.
2. Trespassers playing on or walking across the Chemclene property potentially
exposed through incidental ingestion, dermal contact, and inhalation of volatiles
and fugitive dust from surface soils.
3. Residents living on the Chemclene property potentially exposed through
incidental ingestion, dermal contact, and inhalation of volatiles and fugitive dust
from surface soils, and ingestion of and dermal contact with groundwater, and
inhalation of volatiles from groundwater while showering and bathing.
4. Residential groundwater users living downgradient of the Chemclene property
potentially exposed through ingestion of and dermal contact with groundwater,
and inhalation of volatiles from groundwater while showering and bathing.
5. Commercial and construction workers potentially exposed through ingestion of
groundwater from beneath the Chemclene property.
In order to quantify the potential exposure associated with each pathway, assumptions must be
made for various factors used in the calculations. Table 8 summarizes the values used in this
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BLRA
3. Toxicity Assessment
The purpose of the toxicity assessment is to weigh available evidence regarding the potential for
particular contaminants to cause adverse effects in exposed individuals. Where possible, the
assessment provides a quantitative estimate of the relationship between the extent of exposure to
a contaminant and the increased likelihood and/or severity of adverse effects.
A toxicity assessment for contaminants found at a Superfund site is generally accomplished in
two steps: 1) hazard identification; and 2) dose-response assessment. Hazard identification is
the process of determining whether exposure to an agent can cause an increase in the incidence
of a particular adverse health effect (e.g., cancer or birth defects) and whether the adverse health
effect is likely to occur in humans. It involves characterizing the nature and strength of the
evidence of causation.
Dose-response evaluation is the process of quantitatively evaluating the toxicity information and
characterizing the relationship between the dose of the contaminant administered or received and
the incidence of adverse health effects in the administered population. From this quantitative
dose-response relationship, toxicity values (e.g., reference doses and slope factors) are derived
that can be used to estimate the incidence or potential for adverse effects as a function of human
exposure to the agent. These toxicity values are used in the risk characterization step to estimate
the likelihood of adverse effects occurring in humans at different exposure levels.
For the purpose of the risk assessment, contaminants were classified into two groups, potential
carcinogens and noncarcinogens. The risks posed by these two types of compounds are assessed
differently because noncarcinogens generally exhibit a threshold dose below which no adverse
effects occur, while no such threshold can be proven to exist for carcinogens. As used here, the
term carcinogen means any chemical for which there is sufficient evidence that exposure may
result in continuing uncontrolled cell division (cancer) in humans and/or animals. Conversely,
the term noncarcinogen means any chemical for which the carcinogenic evidence is negative or
insufficient.
Slope factors have been developed by EPA's Carcinogenic Assessment Group for estimating
excess lifetime cancer risks associated with exposure to potentially carcinogenic contaminants of
concern. Slope factors, which are expressed in units of (mg/kg/day)-1 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 slope factor. Use of
this approach makes underestimation of the actual cancer risk highly unlikely. Slope factors 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 to account for the use
of animal data to predict effects on humans. Slope factors used in the baseline risk assessment
are presented in Table 10.
Reference doses (RfDs) have been developed by EPA for indicating the potential for adverse
health effects from exposure to contaminants of concern exhibiting noncarcinogenic effects.
RfDs, which are expressed in units of mg/kg/day, are estimates of acceptable lifetime daily
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exposure levels for humans, including sensitive individuals. Estimated intakes of chemicals
from environmental media (e.g. the amount of a chemical ingested from contaminated drinking
water) can be compared to the RfD. RfDs are derived from human epidemiological studies or
animal studies to which uncertainty factors help ensure that the RfDs will not underestimate the
potential for adverse noncarcinogenic effects to occur. Reference doses used in the baseline risk
assessment are presented in Table 9.
4. Human Health Effects
lexicological profiles of selected constituents, including carbon tetrachloride, 1,1-DCE, cis-1,2-
DCE, PCE, 1,1,2-TCA, and TCE which are primary contaminants contributing to Site risks, can
be found in Appendix A. In addition, a toxicity profile is provided for lead which does not have
published toxicity values.
5. Risk Characterization
The risk characterization process integrates the toxicity and exposure assessments into a
quantitative expression of risk. For carcinogens, the exposure point concentrations and exposure
factors discussed earlier are mathematically combined to generate a chronic daily intake value
that is averaged over a lifetime (i.e., 70 years). This intake value is then multiplied by the
toxicity value for the contaminant (i.e., the slope factor) to generate the incremental probability
of an individual developing cancer over a lifetime as a result of exposure to the contaminant.
The National Oil and Hazardous Substances Pollution Contingency Plan (NCP) established
acceptable levels of carcinogenic risk for Superfund sites ranging from one excess cancer case
per 10,000 people exposed to one excess cancer case per one million people exposed. This
translates to a risk range of between one in 10,000 and one in one million additional cancer
cases. Expressed as scientific notation, this risk range is between 1. OE-04 and l.OE-06.
Remedial action is warranted at a site when the calculated cancer risk level exceeds 1 .OE-04.
However, since EPA's clean up goal is generally to reduce the risk to 1 .OE-06 or less, EPA also
may take action where the risk is within the range between 1 .OE-04 and l.OE-06.
The potential for noncarcinogenic effects is evaluated by comparing an exposure level over a
specified time period (i.e., the chronic daily intake) with the toxicity of the contaminant for a
similar time period (i.e., the reference dose). The ratio of exposure to toxicity is called a hazard
quotient. A Hazard Index (HI) is generated by adding the appropriate hazard quotients for
contaminants to which a given population may reasonably be exposed. The NCP also states that
sites should not pose a health threat due to a non-carcinogenic, but otherwise hazardous,
chemical. If the HI exceeds one (1.0), there may be concern for the potential non-carcinogenic
health effects associated with exposure to the chemicals. The HI identifies the potential for the
most sensitive individuals to be adversely affected by the noncarcinogenic effects of chemicals.
As a rule, the greater the value of the HI above 1.0, the greater the level of concern.
Table 9 summarizes the total risk levels for current and future Residential Well Users.
Table 10 summarizes the total risk levels from all appropriate exposure routes calculated for each
group of individuals. Table 11 summarizes the total risk levels by each area (i.e. Former
Disposal Area, Main Plant Area).
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B. Ecological Risk Assessment
The ecological risk assessment was designed to evaluate the potential threats to ecological
organisms from exposure to Site contaminants and to establish potential Site-specific clean-up
level(s) for the contaminants of concern. Both acute (short-term) and chronic (long-term) studies
were conducted for a variety of organisms, representing several different trophic levels. Direct
toxicity usually results from direct exposure to certain metals and volatile compounds, and is best
evaluated from laboratory or on-Site bioassays. Both chronic and acute bioassays were used to
assess direct toxicity at this Site. Indirect or secondary toxicity usually results when birds and
mammals accumulate contaminants (some metals, PCBs, and pesticides) in their bodies from
eating contaminated prey. Therefore, chronic threats (long-term survival, growth and
reproduction) to birds and mammals were assessed by conservatively estimating the amount of
contaminated prey that may be consumed on-Site and comparing that dose to a known effect
level. The following summarizes the various tools that were used to assess ecological risk at the
Site:
• surface water bioassays with invertebrates and fish
• sediment bioassays with amphipods and midges
• soil bioassays with earthworms
• food chain modeling with birds and mammals.
The results indicate the following:
• Three potential wetland areas were identified between the Main Plant Area and the
Former Disposal Area/Mounded Area.
• With the exception of one sampling location (W1), the results of a 7-day aqueous phase
toxicity evaluation using the cladoceran Ceriodaphnia dubia suggest that there is no
toxicity associated with surface water to freshwater invertebrates at the Site.
• The results of a 7-day aqueous-phase toxicity evaluation using the fish Pimephales
promelas suggest that there is no toxicity associated with surface water to freshwater
invertebrates at the Site.
• The results of a 10-day solid-phase toxicity evaluation using the crustacean (Hyallela
azteca) and midge (Chironnomus tentans) suggest that there is no acute or chronic
toxicity associated with surface sediment to freshwater invertebrates at the Site.
The results of the 14-day and 28-day solid-phase toxicity evaluation using Eiseniafoetida
suggest that there is no toxicity (acute or chronic) associated with the surface soil to soil-
dwelling invertebrates at the Site.
• The results of the hazard quotient calculations for omnivorous and carnivorous mammals
suggest that the levels of PCBs, aluminum, chromium, lead, manganese, and selenium in
the surface soil, surface water, and soil invertebrate community at the Site are sufficient
to pose a risk to the survival, growth, and/or reproduction of omnivorous and carnivorous
mammals, all long-term effects anticipated if these organisms feed constantly onsite.
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• The results of the risk characterization for omnivorous and carnivorous birds suggest that
there is also a potential chronic risk associated with PCBs, aluminum, cadmium, lead, and
zinc at the Site.
These results suggest that the levels of PCBs, aluminum, cadmium, lead, and zinc in the surface
soil, surface water, and soil invertebrate community at the Site are sufficient to pose a risk to the
survival, growth, and/or reproduction of omnivorous and carnivorous birds.
RECOMMENDATIONS
The weight of evidence approach was used to evaluate the results of the ecological risk
assessment. Compounds were evaluated based on the mechanism of toxicity and the
measurement endpoint which supported the evaluation related to the mechanism. Two
approaches were evaluated, direct toxicity which include metals and volatiles, and food chain
accumulation which include PCB, pesticides, and some metals.
The direct toxicity evaluations indicate that metals or volatiles do not pose a risk through direct
toxicity.
PCBs were detected in surface soils at several locations within the Former Disposal
Area/Mounded Area. Based on food chain evaluations, the levels observed in those areas pose a
potential chronic ecological risk. Although metals pose a potential ecological risk, these .are not
Site-related and are representative of background conditions. However, the selected alternative
will eliminate any potential ecological risk associated with exposure to soils contaminated with
PCBs.
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VTH. DESCRIPTION OF REMEDIAL ALTERNATIVES CONSIDERED FOR THE
SITE
•
The Feasibility Study (FS) discusses a series of alternatives to address the subsurface soil and
groundwater at the Main Plant Area and Former Disposal Area and groundwater contamination
south of the Chemclene property. The FS and Addendum (May 29, 1997) also provide
supporting information relating to the alternatives in this ROD.
Four to eight alternatives for each of the media at the two locations were identified as possible
response actions. These are numbered to correspond with alternatives found in the FS. The
alternatives will be discussed in the following sections: water supply alternatives for both areas,
Main Plant Area soil and groundwater alternatives, and Former Disposal Area soil and
groundwater alternatives. For a summary of alternatives, see Table 12.
WATER SUPPLY
Alternative WS-G-3a: Public Water Supply
Alternative WS-G-3b: Well Head Treatment
Alternative WS-G-3-a: Public Water Supply
Capital Cost: $ 408,600
Operation and Maintenance: $ 97,371
Total: $ 505,971
The objective of this alternative is to prevent contact with contaminated groundwater at the
residences affected or potentially affected by the Site. This objective can be accomplished by
connecting residences affected and potentially affected by the Site to a public drinking water
supply. Establishment of a permanent connection to a public water supply would eliminate the
use of contaminated groundwater. Affected residential wells would be abandoned upon
connection to a public water supply or convened to monitoring wells. By the end of 1997,
Philadelphia Suburban Water Company plans to install water mains in Phoenixville Pike from
Aston Road to Conestoga Road, and to extend the existing main in Conestoga Road north to
Bacton Hill Road.
Because contaminated media would be left on the Site, a review of the Site conditions would be
required every five years, as specified in the NCP.
Alternative WS-G-3b: Well Head Treatment
Capital Cost: $ 113,676
Annual Operation and Maintenance: $ 42,000
Operation and Maintenance Period: 30 Years
Total Cost: $ 979,647
The objective of well head treatment would be to reduce the concentrations of VOC
contaminants in residential drinking water to meet drinking water standards. Well head
treatment would include the purchase, installation, maintenance, and monitoring of carbon filters
at each of the affected residences.
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Residences hydraulically downgradient of the Former Disposal Area/Mounded Area include
homes in the Hillbrook Circle development and nearly all residences along Conestoga Road and
Phoenixville Pike. Only one residence is hydraulically downgradient of the Main Plant Area
(DW-10). Presently, 19 residences in Hillbrook Circle and on Phoenixville Pike are equipped
with either single or double canister unit filters.
Under this alternative, contaminated media would be left on the Site and a review of the Site
conditions would be required every 5 years.
MAIN PLANT AREA
Soil Alternatives
MPAS-1: No Action
MPA S-2: Institutional Controls
MPAS-3: Capping
MPA S-4: InSitu Soil Vapor Extraction
Alternative MPA-S-1: No Action
Capital Cost: SO
Annual Operation and Maintenance: $0
Total Cost: $0
The NCP requires that EPA consider a "No Action" alternative for every Superfund site to
establish a baseline or reference point against which each of the remedial action alternatives are
compared. In the event that the other identified alternatives do not offer substantial benefits over
this alternative, the No Action alternative may be considered a feasible approach.
Alternative MPA-S-2: Institutional Controls
Capital Cost: $ 89,000
Annual Operation and Maintenance: $ 56,000
Operation and Maintenance Period: 30 Years
Total Cost: $1,145,000
The purpose of the institutional controls is to prohibit temporarily or permanently certain
activities on parts of the Site that pose unacceptable risk. Institutional controls protect human
health to some degree by diminishing the potential for exposure. Institutional controls would
include deed restrictions to limit future use of the Site, fencing to restrict access, and Site reviews
every five years.
Alternative MPA-S-3: Capping
Capital Cost: $ 343,000
Operation and Maintenance: $ 30,000
Operation and Maintenance Period: 30 Years
Total Cost: $ 940,441
This alternative consists of installation of a cap over the Main Plant Area soils which have
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concentrations of contaminants which are above the clean up standards established for the
protection of groundwater. For purposes of the cost evaluation, the cap is assumed to be concrete
and to extend around the existing buildings. This would reduce infiltration through contaminated
soil and allow the facility to remain available for commercial use. This is practicable because the
building floors provide a cap. In the event of disuse of the existing buildings, further evaluations
of the soils beneath the buildings would be required to determine the need for extension of the
cap. In addition, any existing equipment or tanks shall be removed in order to allow for the
extension of the cap over affected areas. The actual size and locations of the capped areas would
be determined during the remedial design phase of the project. Key elements of this alternative
include Site grading, installation of a cap in the Main Plant Area, including stormwater controls,
vapor monitoring points, and long-term monitoring.
Alternative MPA-S-4: In-Situ Soil Vapor Extraction (SVE)
Capital Cost: $ 827,000
Annual Operation and Maintenance. S 352,000
Operation and Maintenance Period: 5 Years
Total Cost: $2,351,000
The purpose of In-Situ SVE is to reduce the mass and concentration of VOC contaminants in the
soil which are acting as a source of contamination to groundwater. The VOC contaminants
would be removed from the Main Plant Area soils. Key elements of this alternative include
installation of extraction wells (the depth and number of wells to be determined during remedial
design), construction of a manifold, air treatment, disposal of the treatment wastes, and quarterly
VOC monitoring. These factors, and the effectiveness of the technology for the area of concern
would be evaluated by a pilot study. For purposes of the remedy at the Site, SVE would be
combined with capping to enhance recovery efficiency.
Groundwater Alternatives
MPA-G-1: No Action
MPA-G-2: Institutional Controls
MPA-G-4: Natural Attenuation
MPA-G-5: Groundwater Collection, Treatment & Discharge
MPA-G-6: Groundwater Collection, Treatment of Source Area & Discharge
Alternative MPA-G-1: No Action
Capital Cost: $0
Annual Operation and Maintenance: $0
Total Cost: $0
Under this alternative, no further effort or resources would be expended. Consideration of this
alternative is required, as stated previously. A review of Site conditions would be required every
five years, since under this alternative, waste would be left in place.
Alternative MPA-G-2: Institutional Controls
Capital Cost: $ 59,000
Annual Operation and Maintenance: $ 28,000
Operation and Maintenance Period: 30 Years
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Total Cost: $ 684,000
The purpose of institutional controls is to prevent the use of contaminated water-bearing units as
a source of drinking water and/or to prevent the spread of contamination caused by groundwater
pumping. Institutional controls protect human health to some degree by diminishing the
potential for exposure. Key elements of this alternative include the legal requirements of the
deed restrictions for groundwater use.
Alternative MPA-G-4: Natural Attenuation
Capital Cost: $ 223,000
Annual Operation and Maintenance: $ 41,000
Operation and Maintenance Period: 30 Years
Total Cost: $ 986,116
Natural attenuation relies upon naturally occurring processes, particularly bioremediation,
dilution, and dispersion to reduce concentrations of contaminants in the subsurface to below
levels that pose little or no potential risk to human health and the environment. Under this
alternative, groundwater samples are collected and analyzed for biological and chemical
indicators to confirm contaminant biodegradation is reducing contaminant mass, mobility, and
risk at an acceptable rate. Key elements of this alternative include construction of additional
monitoring wells, monitoring for natural attenuation indicator parameters, preparation of trend
analyses, and annual monitoring report preparation.
Alternative MPA-G-5: Groundwater Collection, Treatment and Discharge
Capital Cost: $1,167,000
Annual Operation and Maintenance: $ 316,000
Operation and Maintenance Period: 30 Years
Total Cost: $ 6,213,637
This alternative reduces the mass and concentration of contaminants in groundwater to MCLs by
pumping and treating of groundwater at selected wells. A principal effect will be to reduce the
extent of the existing plumes. The overall pumping rate, and the number, depth, and location of
wells were selected to minimize the overall costs of treatment. The objective of this
groundwater extraction system would be to contain the contaminant plume by pumping the
extraction wells to keep the contaminant plume from migrating further from the Main Plant Area.
To achieve discharge limits, extracted groundwater would be treated on-Site using air stripping
followed by either vapor phase activated carbon or U/V oxidation. After treatment of
groundwater, the effluent would be discharged by one or a combination of the methods below.
direct discharge to Valley Creek
on-Site spray irrigation of forested areas
re-injection to subsurface
trucking to a Publicly Owned Treatment Works (POTW)
discharge to a water purveyor (including the costs of a main extension by the
purveyor).
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Groundwater reinjection and spray irrigation are the most likely discharge alternatives due to the
Exceptional Quality designation of Valley Creek, the cost effectiveness of trucking discharge to a
POTW, and the potential infeasibility of discharge to a water purveyor.
Alternative MPA-G-6: Groundwater Collection, Treatment of Source Area, and
Discharge
Capital Cost: $ 1,233,000
Annual Operation and Maintenance: $ 316,000
Operation and Maintenance Period: 30 Years
Total Cost: $ 6,280,000
This alternative reduces mass and concentration of contaminants, similar to Alternative MPA-G-
5; MPA-G-6 differs in the location of selected wells for groundwater withdrawal. This
alternative requires pumping at the locations where Dense Non-Aqueous Phase Liquids
(DNAPLs) are suspected. The strategy would be to collect contaminants in the dissolved phase
along with any DNAPLs that are encountered. This pumping configuration would restore the
groundwater to beneficial use. Groundwater treatment and discharge alternatives are the same as
MPA-G-5 above.
FORMER DISPOSAL AREA/MOUNDED AREA
Soil Alternatives
FDA-S-1: No Action
FDA-S-2: Institutional Controls
FDA-S-3: Capping
FDA-S-4: Excavation, Off-Site Thermal Treatment, Disposal at a Subtitle C Landfill
FDA-S-5: Excavation, ExSitu Volatilization, & Reuse as Backfill
FDA-Sr6: Excavation, On-Site Thermal Treatment, and Reuse as Backfill
FDA-S-7: InSitu Soil Vapor Extraction
FDA-S-8: Excavation, Consolidation of Soils at the Main Plant
Alternative FDA-S-1: No Action
Capital Cost: $0
Annual Operation and Maintenance: $0
Total Cost: $0
Under this alternative, as stated previously, no further effort or resources would be expended.
Alternative FDA-S-2: Institutional Controls
Capital Cost: $ 94,000
Annual Operation and Maintenance. $ 56,000
Operation and Maintenance Period: 30 Years
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Total Cost: $1,150,000
The purpose of institutional controls is to prohibit temporarily or permanently certain activities
on pans of the Site that contam hazardous materials. Institutional controls protect human health
to some degree by diminishing the potential for exposure. Institutional Controls would include
deed restrictions to limit future use of the Former Disposal Area and fencing to restrict access.
Key elements of this alternative include the location and costs of the fencing and the legal
requirements of the deed restrictions.
Alternative FDA-S-3: Capping
Capital Cost: $ 434,000
Annual Operation and Maintenance: $ 30,000
Operation and Maintenance Period: 30 Years
Total Cost: $ 974,285
The purpose of capping is to reduce potential leaching of contaminants in the unsaturated soil.
This objective is accomplished by minimizing infiltration of rainfall and associated leaching of
contaminants which are localized in the unsaturated soil zone. A gradual reduction in mass and
concentration of contaminants in soil may occur as a result of natural attenuation processes. A
cap can also be used to prevent exposure via direct contact with contaminated soils Key
elements of this alternative include grading, import of off-Site borrow material, installation of a
clay, linear low density polyethylene membrane or bituminous concrete cap in the Former
Disposal Area/Mounded Area, stormwater controls, soil vapor monitoring points and long-term
monitoring.
Common Components for Alternatives FDA-S-4. FDA-S-5. FDA-S-6. and FDA-S-8
A common component for the excavation alternatives includes geoprobe exploration to more
closely delineate volumes of soil which exceed clean up requirements, followed by excavation.
Excavations will be above the water table and clean fill will be used to regrade the area. The
principal factor for this alternative is the volume of material to be excavated. The volume of the
excavated material was determined by the area! extent and depth of soils with contaminant
concentrations which exceeded the clean up standards established for soil.
Alternative FDA-S-4: Excavation, Off-Site Thermal Treatment, Disposal at
Hazardous Waste Landfill
Capital Cost: $7,016,000
Annual Operation & Maintenance: $0
Total Cost: $7,016,000
The objective of excavation is to remove the mass of VOC contaminants in the vadose zone.
Key elements of this alternative include geoprobe exploration, excavation and off-Site disposal
to a hazardous waste landfill, backfilling, regrading, and land stabilization.
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Alternative FDA-S-5: Excavation, Ex-Situ Volatilization, and Re-Use as
Backfill
Capital Cost: $2,351,000
Annual Operation and Maintenance: $ 390,000
Operation and Maintenance Period: 1 Year
Total Cost: $ 2,787,000
The objective of excavation is to remove the mass of VOC contaminants in the vadose zone.
Key elements of this alternative include geoprobe exploration, excavation, ex-situ volatilization,
re-use of treated soils as backfill, regrading, and land stabilization. Because the soils contain
RCRA listed hazardous waste, once treated, soils must meet certain levels in order to place the
soil back onto the ground. EPA has a "Contained-In Policy" which allows that soils
contaminated with RCRA hazardous waste can be treated to certain site-specific levels that
would allow such soils to be placed back onto the ground. A future pilot study would be
required to determine if ex-situ volatilization can treat soils to these site-specific levels that
render the soil non-hazardous and allow backfilling.
Alternative FDA-S-6: Excavation, On-Site Thermal Treatment, and Re-Use as
Backfill
Capital Cost: $ 3,858,000
Annual Operation and Maintenance: SO
Operation and Maintenance Period: < 1 Year
Jotal Cost: $ 3,858,000
The objective of excavation is to remove the mass of VOC contaminants in the vadose zone.
Key elements of this alternative include geoprobe exploration, excavation, on-Site thermal
desorption, re-use of treated soils as backfill, regrading, and land stabilization. Because the soils
contain RCRA listed hazardous waste, once treated, soils must meet certain levels in order to
place the soil back onto the ground. EPA has a "Contained-In Policy" which allows that soils
contaminated with RCRA hazardous waste can be treated to certain site-specific levels that
would allow such soils to be placed back onto the ground. A future pilot study would be
required to determine if on-Site thermal treatment can treat soils to these site-specific levels that
render the soil non-hazardous and allow backfilling
Alternative FDA-S-7: In-Situ Soil Vapor Extraction
Capital Cost: $ 1,308,000
Annual Operation and Maintenance: $ 581,560
Operation and Maintenance Period: 5 Years
Total Cost: $ 3,873,503
The objective of in-situ SVE is to reduce the mass and concentration of VOC contaminants in the
vadose zone. SVE will greatly accelerate the rate at which the clean up levels can be attained
VOC contaminants will be removed from the subsurface soils. Key elements of this alternative
include installation of extraction wells (the depth and number of wells will be determined during
remedial design), air treatment, disposal of the treatment wastes, and quarterly VOC monitoring
The factors considered in sizing the treatment unit are the air conductivity of soil, mass of
contaminants, and the concentration of VOCs recoverable in air. These factors were estimated
for the FS. These factors would be evaluated by a future pilot study.
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Alternative FDA-S-8: Excavation with Consolidation at the Main Plant Area
Corrective Action Management Unit (CAMTJ)
Option 1 Option 2
Capita] Cost: $ 684,319 Capital Cost: $ 777,762
Annual O&M: $ 30,000 Annual O&M: $ 30,000
O&M Period: 30 Years O&M Period: 30 Years
Total Cost: $1,242,924 Total Cost: $1,336,367
The objective of this alternative is to remove contaminated soils from the Former Disposal
Area/Mounded Area. The estimated 5,700 cubic yards of soil would be transported to the Main
Plant Area and covered with a RCRA cap. Key elements of this alternative include geoprobe
exploration, excavation and removal of contaminated soil to the Main Plant Area, removal of the
collapsed quonset hut storage building, relocation of the office trailer, consolidation of soil and
capping. In-situ treatment of contaminated soils by vapor extraction at the Main Plant Area was
evaluated under Alternative MPA-S4 (In-Situ SVE). If Alternatives MPA-S-4 and FDA S-8 are
both selected and pre-design pilot studies are favorable, the design of the In-Situ SVE system
would be configured to treat soils transferred from the Former Disposal Area/Mounded Area to
the Main Plant Area in addition to contaminated subsurface soils beneath source areas at the
Main Plant Area.
Two options were evaluated for constructing a fill containing 5,700 cubic yards of contaminated
soil. Option 1 involves razing and/or relocating several auxiliary structures at the Main Plant
Area which are believed not to impact the current operation at the facility, including a former
storage building which has collapsed in place, miscellaneous tanks and an office trailer. The
completed fill would occupy approximately 0.43 acres and would have a maximum height of 20
feet with maximum side slopes of 2.5 to 1. This area would be capped separately from the
proposed area in MPA-S3. Option 2 would require the razing of all existing structures at the
Main Plant Area. Because Option 2 provides more surface area, the completed fill would occupy
0.8 acres and would rise a maximum of 7 feet above existing grade. The maximum side slopes
for Option 2 would be 4:1. If Option 2 were selected, the surface area of the cap would include
the majority of the Main Plant Area and therefore the cap included under MPA-S3 would not be
required and would result in a significant cost savings.
For both Options 1 and 2, the northern boundary of the capped fill lies over 30 feet inside the
northern property line. Locating the fill in this manner will accommodate keeping the easement
open between the Former Disposal Area/Mounded Area and Main Plant Area, and should
prevent problems regarding access and easements if the property is ultimately sold. However,
the exact area of the cap would be finalized during remedial design.
The concept of the RCRA Corrective Action Management Unit (CAMU) is a critical element to
this alternative. The federal CAMU regulation, which was effective in April 1993, can be
applicable to CERCLA sites. A CAMU is an area within a facility that is designated by the EPA
Regional Administrator under 40 C.F.R. Part 264 subpart S, for the purposes of implementing
corrective action. A CAMU shall only be used for the management of remediation waste.
In this alternative, a CAMU would be used to consolidate contaminated soil from the Former
Disposal Area into a single area at the Main Plant Area. This action would enlarge the surface
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area affected by contaminated soil at the Main Plant Area but would have no impact on the
groundwater clean up at the Main Plant Area. However, contaminated soil and remediation
wastes would be effectively removed from the Former Disposal Area/Mounded Area which
would reduce the timeframe for groundwater clean up at the Former Disposal Area. To comply
with closure requirements, the relocated material would be covered with a RCRA cap
Groundwater Alternatives
FDA-G-1: No Action
FDA-G-2. Institutional Controls
FDA-G-4: Natural Attenuation
FDA-G-5: Groundwater Collection, Treatment, and Discharge
FDA-G-6: Groundwater Collection, Treatment (Single Well), and Discharge
Alternative FDA-G-1: No Action
Capital Cost: $0
Annual Operation and Maintenance: $0
Total Cost: $0
Under this alternative, as stated previously, no further effort or resources would be expended on
the groundwater at the Former Disposal Area.
Alternative FDA-G-2: Institutional Controls
Capital Cost: $ 59,000
Annual Operation and Maintenance: $ 28,000
Operation and Maintenance Period: 30 Years
Total Cost: $ 684,000
The purpose of institutional controls is to prevent the use of contaminated water-bearing units as
a source of drinking water or to prevent the spread of contamination caused by groundwater
pumping through administrative means. Institutional controls protect human health to some
degree by diminishing the potential for exposure. Key elements of this alternative include the
legal requirements of the deed restrictions for groundwater.
Alternative FDA-G-4: Natural Attenuation
Capital Cost: $ 227,000
Annual Operation and Maintenance: $ 42,000
Operation and Maintenance Period: 30 Years
Total Cost: $ 979,647
Contaminants are presently migrating within a groundwater plume toward Hillbrook Circle,
located southwest of the Former Disposal Area/Mounded Area. A review of historical data
indicates the area occupied by this plume has been at a steady-state or receding since drummed
waste and contaminated soil were removed in the early 1980s (See Section II. Site History).
Groundwater sampling and analysis has suggested that the contaminant plume was receding over
this time period due to the drum and soil removal activities.
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A receding contaminant plume occurs, in the absence of active remediation, when the rate of
natural attenuation of contamination exceeds the rate at which contaminants enter the
groundwater from a source. Typically, under receding conditions, the contaminant plume has
expanded to a maximum extent and then the leading edge recedes as natural attenuation occurs
along the periphery of the plume. The conditions at the Former Disposal Area/Mounded Area
would suggest that the contaminant plume is approaching equilibrium with residual
contamination which remains in the soil. The RI determined that there is significant evidence of
biological and abiotic attenuation. Abiotic attenuation includes volatilization, sorption,
hydrolysis, and dehalogenation. The solvents disposed at the Former Disposal Area/Mounded
Area were primarily TCE, TCA, PCE, and MEC. However, other chlorinated species, including
(cis)l,2-DCE, 1,1-DCE, and 1,1-DCA are present in approximately equal concentrations. These
de-halogenated compounds are known to be degradation by-products of the more highly
halogenated solvents which were disposed. Their presence in high concentrations indicates that
the process of chemical degradation is advanced at the Former Disposal Area/Mounded Area
Under this alternative, groundwater samples are collected and analyzed for biological and
chemical indicators to confirm contaminant biodegradation is reducing contaminant mass,
mobility, and risk at an acceptable rate. Key elements of this alternative include construction of
additional monitoring wells, quarterly monitoring for natural attenuation indicator parameters,
preparation of trend analyses, and annual monitoring report preparation.
Alternative FDA-G-5: Groundwater Collection, Treatment and Discharge
Capital Cost: $2,869,000
Operation and Maintenance: $ 2,898,000
Operation and Maintenance Period: 2 years
Total Cost: $8,258,000
This alternative includes the collection, on-Site treatment, and discharge of contaminated
groundwater at the Former Disposal Area/Mounded Area. Because of the large area of the plume
(extending from the Former Disposal Area to the residential area), and the high transmissivity of
the aquifer, selecting a well configuration to capture the complete plume would be difficult.
Different scenarios were modeled, but recovery well locations that would de-water the residential
wells were rejected. Modeling indicated that a pumping rate of 2,000 gallons per minute from
the four extraction wells along the property boundary would prevent migration of the majority
(approximately 80%) of the plume. Though some of the plume on the property and in the
Hillbrook Circle would not be captured, the outlying plume area would be reduced by natural
attenuation, especially when isolated from the source of higher levels of contamination. The
existing wells are not capable of this yield and actual implementation of this alternative would
require installation of larger diameter extraction wells.
Several methods of disposal of treated water, as discussed in Alternative MPA-G-5, were
considered. Re-injection was considered most plausible, however, reinjection down gradient of
the property could cause contamination to migrate to previously uncontaminated areas and
residences in Hillbrook Circle. Injection into eight wells upgradient of the extraction wells was
determined to be more effective. This disposal method would help flush contaminants around
monitoring well CC-14 toward the extraction wells. Extracted groundwater would be treated
using air stripping combined with either activated carbon or U/V oxidation before re-injection.
Clean up to MCLs is estimated to require two years.
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Alternative FDA-G-6: Groundwater Collection (Single Well), Treatment, and
Discharge
Capital Cost: $ 1,599,000
Annual Operation and Maintenance: $ 846,000
Operation and Maintenance Period: 7 Years
Total Cost: $ 3,269,802
This alternative includes the collection, on-Site treatment, and discharge of contaminated
groundwater at the Former Disposal Area/Mounded Area. Alternative FDA-G-6 also relies on
natural attenuation mechanisms to ultimately reduce groundwater contaminant concentrations
below MCLs (5 ug/1 for TCE). The intention of this alternative is to significantly reduce
concentrations within the most highly contaminated portion of the plume. The pumping well
would be shut off after two years and the plume would degrade to the MCL through natural
attenuation.
In this alternative, contaminated groundwater would be intercepted at a single extraction well
located downgradient of the Former Disposal Area/Mounded Area pumping at 500 gallons per
minute. The exact location for the extraction well would be determined during design. Two
wells could potentially be used if deemed necessary. Treated groundwater would be disposed by
injecting groundwater in two injection wells located hydraulically upgradient of the Former
Disposal Area/Mounded Area.
Results of the modeling indicated that concentrations in the central portion of the contaminant
plume would decrease from greater than 1,000 ug/1 to around 100 ug/1 after two years of
pumping. Concentrations in the central portion of the plume are estimated to reach the clean up
level of 5 ug/1 (MCL for TCE) in seven years.
Extracted groundwater would be treated at the plant with identical treatment and discharge
processes as discussed for the Main Plant Area. The volume requiring treatment is estimated at
720,000 gallons/day.
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IX. COMPARATIVE EVALUATION OF ALTERNATIVES
Each of the remedial alternatives summarized in this ROD has been evaluated against the nine
(9) evaluation criteria set forth in the NCP, 40 C.F.R. Section 300 430(e)(9). These nine criteria
can be categorized into three groups: threshold criteria, primary balancing criteria, and modifying
criteria. A description of the evaluation criteria is presented below:
Threshold Criteria:
1. Overall Protection of Human Health and the Environment addresses whether a remedy
provides adequate protection and describes how risks are eliminated, reduced, or
controlled.
2. Compliance with ARARs addresses whether a remedy will meet all of the applicable, or
relevant and appropriate requirements of environmental statutes. Preliminary ARARs
each alternative are referenced in Appendix A1-A3 of the FS. ARARs for the Selected
Remedy are summarized in Table 14.
Primary Balancing Criteria:
3. Long-term Effectiveness refers to the ability of a remedy to maintain reliable protection of
human health and the environment over time once clean up goals are achieved.
4. Reduction of Toxicity, Mobility, or Volume through Treatment addresses the degree to
which alternatives employ recycling or treatment that reduces toxicity, mobility, or
volume of contaminants.
5. Short-term Effectiveness addresses the period of time needed to achieve protection and
any adverse impacts on human health and environment that may be posed during the
construction and implementation period until clean up requirements are achieved.
6. Implementability addresses the technical and administrative feasibility of a remedy,
including the availability of materials and services needed to implement a particular
option.
7. Cost includes estimated capital, operation and maintenance costs, and present worth
costs.
Modifying Criteria:
8. State Acceptance indicates whether, based on its review of backup documents and the
Proposed Plan, the State concurs with, opposes, or has no comment on the preferred
alternative.
9. Community Acceptance includes assessments of issues and concerns the public may have
regarding each alternative based on a review of public comments received on the
Administrative Record and the Proposed Plan.
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Below is a summary of alternatives for reference during the comparative analysis:
Water Supply
WS-G-3a: Public Water Supply
WS-G-3b: Well Head Treatment
Main Plant Area Soils
MPAS-1: No Action
MPA S-2: Institutional Controls
MPAS-3: Capping
MPA S-4: InSitu Soil Vapor Extraction
Main Plant Area Groundwater
MPA-G-1: No Action
MPA-G-2: Institutional Controls
MPA-G-4: Natural Attenuation
MPA-G-5: Groundwater Collection, Treatment & Discharge
MPA-G-6: Groundwater Collection, Treatment of Source Area & Discharge
Former Disposal Area Soils
FDA-S-1: No Action
FDA-S-2: Institutional Controls
FDA-S-3 Capping
FDA-S-4: Excavation, Off-Site Thermal Treatment, Disposal at a Subtitle C Landfill
FDA-S-5: Excavation, ExSitu Volatilization, & Reuse as Backfill
FDA-S-6: Excavation, On-Site Thermal Treatment, and Reuse as Backfill
FDA-S-7: InSitu Soil Vapor Extraction
FDA-S-8: Excavation, Consolidation of Soils at the Main Plant
Former Disposal Area Groundwater
FDA-G-1: No Action
FDA-G-2: Institutional Controls
FDA-G-4: Natural Attenuation
FDA-G-5: Groundwater Collection, Treatment, and Discharge
FDA-G-6: Groundwater Collection, Treatment (Single Well), and Discharge
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Water Supply Alternatives
1 Overall Protection of Human Health and the Environment
Implementation of Alternatives WS-G-3a or WS-G-3b identified above would not protect human
health or the environment at the Main Plant Area or the Former Disposal Area/Mounded Area
(i.e., the source areas) because they do not address groundwater contamination on the property
The risk posed from contaminated soil and potential exposure to contaminated groundwater on
these areas would not be reduced. Migration of contamination would continue through soil-
contaminant leaching, groundwater migration, surface water migration, and infiltration. Residual
risks for these areas are identical to those identified in the baseline risk assessment.
Implementation of WS-G-3a or WS-G-3b would protect human health at the residences by
eliminating the potential for direct contact with contaminated groundwater by ingestion.
Residential water would be treated to drinking water standards under WS-G-3b or supplied from
a public water supply under WS-G-3a.
2. Compliance witfi ARARs
Requirements for the use of groundwater as a residential water supply, include meeting Safe
Drinking Water Act MCLs. For carcinogens, these requirements include treating groundwater at
least to concentrations that do not cause a lifetime cancer risk greater than 1 in 10,000. For
systemic toxicants, these requirements include treating groundwater to media specific levels
where people could be exposed by direct ingestion or inhalation on a daily basis with no
appreciable risk of deleterious effects.
Chemical-specific ARARs for this WS-G-3a or WS-G-3b would be met at the residences, but
would not be met at the source areas.
The location-specific ARAR which applies to WS-G-3a or WS-G-3b is the Delaware River
Basin Commission requirement which prohibits adverse impacts to the groundwater resources in
the Delaware River Basin. This ARAR would be met at the residences, but not at the source
areas.
There are no action-specific ARARS which apply to WS-G-3a or WS-G-3b.
3. Long-Term Effectiveness and Permanence
Neither WS-G-3a or WS-G-3b provides long-term effectiveness and permanence within the
source areas. The risk currently associated with the source areas would not be decreased and
might be increased through migration of contaminants. Long-term risks posed by the source
areas are described in the baseline risk assessment. Because of contaminants left at the Site, a
review of Site conditions would be required every 5 years.
Alternative WS-G-3a and WS-G-3b would be effective in the long-term at protecting public
health at the point of exposure. For well head treatment, maintenance and monitoring of carbon
units would be necessary for the duration of well head treatment. However, connecting local
residences to a water supply would provide long-term protection to public health at the point of
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exposure and would require the O&M to ensure long term effectiveness.
4. Reduction of Toxicity. Mobility, and Volume through Treatment
Neither WS-G-3a or WS-G-3b would provide any reduction of toxicity, mobility, and volume of
contaminants at the source areas and would not meet the statutory preference for treatment. WS-
G-3a and WS-G-3b would provide a reduction of toxicity and volume of contaminants at the
residential water supplies. WS-G-3b would meet the statutory preference for treatment at the
residences.
5. Short-Term Effectiveness
No increased risk to the surrounding community would be realized by implementation of either
WS-G-3a or WS-G-3B at the source areas. This alternative would be effective immediately at
the residences upon installation of the carbon units or water supply.
6. Implementability
WS-G-3a and WS-G-3b are both easily implementable. Equipment and services to install,
monitor, and maintain the carbon units are available from local sources. Installation of a water
main is already planned by the Philadelphia Suburban Water Company and is a standard
construction activity. However, the implementability of these alternatives that require
Institutional Controls may be affected due to legal considerations.
7. Cost
Evaluation of costs of each alternative generally includes the calculation of direct and indirect
capital costs and the annual O&M costs, both calculated on a present worth basis.
Direct capital costs include costs of construction, equipment, building and services, and waste
disposal. Indirect capital costs include engineering expenses, start-up and shutdown, and
contingency allowances. Annual O&M costs include labor and material; chemicals, energy, and
fuel; administrative costs and purchased services; monitoring costs; cost for periodic Site review
(every five years); and insurance, taxes, and license costs.
The total present worth costs of WS-G-3a is estimated at $586,249 which is less expensive than
WS-G-3b which is estimated at $979,647.
8. State Acceptance
The Commonwealth of Pennsylvania has had the opportunity to review and comment on all the
documents in the Administrative Record and has participated in selecting the remedy for this
Site. The Commonwealth has had the opportunity to comment on the draft ROD and, to the
extent possible, the Commonwealth's comments have been incorporated into the ROD.
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9. Community Acceptanqg
A public meeting on the Proposed Plan was held on July 16, 1997 at the Great Valley High
School, East Whiteland Township, Pennsylvania. Comments received orally at the public
meeting and in writing during the comment period were in favor of the provision of a public
water supply for affected residents. Oral and written comments on the remedial alternatives
evaluated by EPA for the implementation at the Site are included in Part III of this ROD
Main Plant Area - Soil Alternatives
1. Overall Protection of Human Health and the Environment
Alternative MPA-S-3, Capping, and Alternative MPA-S-4, In-Situ Soil Vapor Extraction (SVE)
in combination, potentially achieve overall protection of human health and the environment. In
the case of In-Situ SVE, effectiveness needs to be demonstrated through a treatability study.
Alternative MPA-S-1, No Action, and Alternative MPA-S-2, Institutional Controls, would not be
protective since clean up standards would not be met. Therefore, MPA-S-1 and MPA-S-2 will
not be discussed further in this analysis since they do not meet this threshold criterion.
Alternative MPA-S-3, Capping, is the only alternative which would provide an immediate
benefit by minimizing the release of contamination to groundwater from the contaminated soils
in the unsaturated zone and protecting construction workers from direct contact with
contaminated soils. The capping alternative also benefits In-Situ SVE, and several groundwater
alternatives such as natural attenuation, conventional groundwater extraction, and DNAPL
collection/groundwater extraction.
Alternative MPA-S-4, In-Situ SVE in combination with MPA-S-3, Capping, provides the largest
reduction in soil migration and health-based risk on the Site through treatment of contamination
above the clean up standards. The mass of contaminants in the soils would be reduced thereby
and eliminate an ongoing source of contamination to groundwater.
2. Compliance with Applicable or Relevant and Appropriate Requirements (ARARS1
Alternative MPA-S-3, Capping, and Alternative MPA-S-4, In-Situ SVE, would comply with
chemical-, location-, and action-specific ARARs. A treatability study would be required for SVE
to ensure that it can adequately achieve target clean up levels.
3. Long Term Effectiveness and Permanence
Alternative MPA-S-4, In-Situ SVE in combination with MPA-S-3, Capping, would be the most
effective in the long-term since it incorporates treatment of the soil, which is not a reversible
process and does not require long-term maintenance. A treatability study would be required.
Alternative MPA-S-3, Capping, would be effective in the long-term providing the O&M
program and Institutional Controls are carried out. If the integrity of the cap is compromised, the
contaminants in the underlying soil would be reactivated as a source of groundwater
contamination and could lead to future exposures above the health-based risk standards.
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4. Reduction of Toxicity. Mobility, or Volume through Treatment
Alternative MPA-S-4, In-Situ SVE in combination with MPA-S-3, Capping, provides the most
significant reduction in toxicity, mobility, and volume in the source areas. Alternative MPA-S-3,
Capping, provides a reduction in mobility, but does not provide a reduction in toxicity and
volume on-Site.
5 Implementability
This evaluation criterion addresses the difficulties and unknowns associated with implementing
the clean up technologies associated with each alternative, including the availability of services
and materials, and the reliability and effectiveness of monitoring. However, the
implementability of any alternative that requires Institutional Controls may be affected due to
legal considerations
Alternatives MPA-S-3 and MPA-S-4 are technically implementable. Alternative MPA-S-3,
Capping, incorporates standard construction practices, including grading and paving for the
concrete cap. An O&M program required for the cap incorporates standard construction
practices. Alternative MPA-S-4, In-Situ SVE, incorporates standard construction practices.
Routine O&M would include monthly sampling of extracted vapor and periodic changing of
granular activated carbon for off-gas treatment.
Five year reviews would be required for Alternative MPA-S-3, Capping, since contaminated
soils will remain on the Site. Five year reviews would be required for Alternative MPA-S-4, In-
Situ SVE, during operation of the system.
6. Short-Term Effectiveness
t
A temporary increase in fugitive dust and construction traffic on nearby roads would occur
during installation of the cap under Alternative MPA-S-3, Capping. Construction workers would
be required to use personal protective equipment.
Alternative MPA-S-4, In-Situ SVE, would result in a temporary increase in fugitive emissions
during construction and from treatment system operation. Off-gas from the treatment system
would possibly require treatment. Construction workers would be required to use personal
protective equipment.
7. Cost
MPA-S-3 Capping, costs $940,441 and is less expensive than MPA-S-4, In-Situ SVE, at
$2,351,189,
8. State Acceptance
The Commonwealth of Pennsylvania has had the opportunity to review and comment on all the
documents in the Administrative Record and has participated in selecting the remedy for this
Site. The Commonwealth has had the opportunity to comment on the draft ROD and, to the
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extent possible, the Commonwealth's comments have been incorporated into the ROD.
9. Community Acceptance
A public meeting on the Proposed Plan was held on July 16, 1997 at the Great Valley High
School, East Whiteland Township, Pennsylvania. Comments received orally at the public
meeting and in writing during the comment period were generally in favor of installation of a
cap over the Main Plant Area. Comments were varied with respect to the implementation of SVE
at the Main Plant Area. See Part III of this ROD for oral and written comments on the remedial
alternatives evaluated by EPA for the implementation at the Site.
Main Plant Area - Groundwater Alternatives
1. Protection of Human Health and Environment
Neither Alternative MPA-G-1, No Action, nor Alternative MPA-G-2, Institutional Controls,
alone would provide overall protection of human health and the environment and will, therefore,
not be discussed further in this analysis. Alternative MPA-G-2, Institutional Controls, may be a
viable method to enhance the effectiveness of other alternatives. Alternative MPA-G-4, Natural
Attenuation, may be effective in preventing the downgradient extension of the plume of
contaminated groundwater. However, the data also indicates that the release of contaminants to
groundwater is an on-going process at the Main Plant Area. Without other measures to control
the sources of contamination, the plume is expected to persist for an extended period of time.
Due to the apparent strength of the contaminant sources at the Main Plant Area, Alternative
MPA-G-4, Natural Attenuation, cannot be relied upon to achieve MCLs and will, therefore, not
be discussed further in this analysis.
Alternatives MPA-G-5 and G-6 are expected to achieve overall protection of human health and
the environment.
2. Compliance with ARARs
Alternative MPA-G-5, Groundwater Collection, Treatment, and Discharge, and Alternative
MPA-G-6, Groundwater Collection, Treatment of Source Area, & Discharge, would comply with
chemical-, location-, and action-specific ARARs.
3. Long-Term Effectiveness and Permanence
Both Alternatives MPA-G-5 and MPA-G-6 would be the most effective in the long-term since
they incorporate treatment of the groundwater, which is not a reversible process.
4. Reduction of Toxicity, Mobility, and Volume through Treatment
Both alternative MPA-G-5 and MPA-G-6 provide the most significant reduction in toxicity,
mobility, and volume at the source areas on the Chemclene property.
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5. Short-Term Effectiveness
A temporary increase in fugitive dust and construction traffic on nearby roads would occur
during installation of the grouhdwater treatment system under Alternatives MPA-G-5 and MPA-
G-6. Construction workers would be required to use personal protective equipment. A
temporary increase in fugitive emissions during treatment system operation would occur. Off-
gas from the treatment system may require treatment.
6. Impiementability
Alternatives MPA-G-5 and MPA-G-6 incorporate standard construction practices and equipment
is readily available. However, the implementability of any alternative that requires Institutional
Controls may be affected due to legal considerations.
Five year reviews would be required for Alternatives MPA-G-5 and MPA-G-6 during operation
of the systems.
7.
Of MPA-G-5 and MPA-G-6, G-5 is slightly less costly ($ 6,213,515) than G-6 ($6,279,515).
8. State Acceptance
The Commonwealth of Pennsylvania has had the opportunity to review and comment on all the
documents in the Administrative Record and has participated in selecting the remedy for this
Site. The Commonwealth has had the opportunity to comment on the draft ROD and, to the
extent possible, the Commonwealth's comments have been incorporated into the ROD
9. Community Acceptance
A'public meeting on the Proposed Plan was held on July 16, 1997 at the Great Valley High
School, East Whiteland Township, Pennsylvania. Comments received orally at the public
meeting and in writing during the comment period were varied with respect to the installation of
a Pump and Treat System at the Main Plant. See Pan III, Section II of the Responsiveness
Summary for detailed written comments and EPA responses.
Former Disposal Area Soil Alternatives
1. Overall Protection of Human Health and the Environment
Alternative FDA-S-1, No Action, and Alternative FDA-S-2, Institutional Controls, alone would
not be protective since remedial action objectives would not be met. These alternatives will not
be discussed further in this comparative analysis; they have been screened out on this basis
Alternatives FDA-S-3 through FDA-S-7 would provide overall protection of human health and
the environment. In the case of ex-situ volatilization, on-Site thermal desorption, and In-Situ
SVE, effectiveness needs to be demonstrated through a treatability study. FDA-S-8 would be
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protective'of human health and the environment by removal of contaminated soils
Alternatives FDA-S-3 through FDA-S-8 would provide an immediate benefit by minimizing the
release of contamination to groundwater from the contaminated soils in the unsaturated zone and
protecting humans from direct contact with contaminated soils.
Alternatives FDA-S-4 through FDA-S-8 provide the largest reduction in soil contamination and
health-based risk on the Site through treatment of contamination above the clean up standards
The mass of contaminants in the soils would be reduced and the source of contamination to
groundwater would be removed.
2. Compliance with ARARs
Alternatives FDA-S-3 through FDA-S-8 comply with chemical-, location-, and action-specific
ARARs. A treatability study would be required for ex-situ volatilization, on-Site thermal
desorption.and In-Situ SVE (Alternatives FDA-S-5, FDA-S-6, and FDA-S-7) to ensure that the
treatment systems can adequately comply with the clean up levels.
3. Long-Term Effectiveness and Permanence
Alternatives FDA-S-3 through FDA-S-8 would be the most effective in the long-term since they
incorporate treatment or removal of the soil, which is not a reversible process and does not
require long-term maintenance. A treatability study would be required for ex-situ volatilization,
on-Site thermal desorption, and In-Situ SVE.
Alternative FDA-S-3, Capping, would be effective in the long-term if a cap O&M program is
maintained. If the integrity of the cap is compromised, the contaminants in the underlying soil
could be reactivated as a source of groundwater contamination, and lead to future exposures
above the health-based risk standard.
4. Reduction of Toxicity. Mobility, and Volume through Treatment
Alternatives FDA-S-4 through FDA-S-8, provide the most significant reduction in toxicity,
mobility, and volume through treatment at the Former Disposal Area. Alternative FDA-S-3,
Capping, does not employ treatment. The cap does provide a reduction in mobility, but does not
provide a reduction in toxicity and contaminant volume.
5. Short-Term Effectiveness
A temporary increase in air emissions and construction traffic on nearby roads would occur
during installation of the bituminous concrete cap under Alternative FDA-S-3, Capping.
Construction workers would be required to use personal protective equipment.
Alternatives FDA-S-4 through FDA-S-8 would result in a temporary increase in fugitive
emissions during construction. Construction workers would be required to use personal
protective equipment.
For Alternative FDA-S-5, Excavation, Ex-Situ Volatilization, Re-Use as Backfill, Alternative
FDA-S-6, Excavation, On-Site Thermal Desorption, Re-Use as Backfill, and Alternative FDA-S-
7, In-Situ SVE, off-gas from the treatment system would possibly require treatment.
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6 Implementability
All alternatives are technically implementable However, implementability of any alternative
that requires Institutional Controls may affected due to legal considerations. Alternative FDA-S-
3, Capping, incorporates standard construction practices, including grading and paving for the
cap. An O&M program required for the cap incorporates standard construction practices.
Alternative FDA-S-4, Excavation, Off-Site Thermal Desorption, & Disposal at a Subtitle C
Landfill, Alternative FDA-S-5, Excavation, Ex-Situ Volatilization, Re-Use as backfill, and
Alternative FDA-S-6, Excavation, On-Site Thermal Desorption, Re-Use as backfill, and FDA-S-
8, incorporate standard construction for excavation and backfill. A specialty contractor would be
required for Alternative FDA-S-6, Excavation, On-Site Thermal Desorption, Re-Use as Backfill
Alternative FDA-S-7, In-Situ SVE, incorporates standard construction practices. Routine O&M
would include monthly sampling of extracted vapor and periodic changing of granular activated
carbon for off-gas treatment.
Five year reviews would be required for FDA-S-3, Capping, since contaminated soils will remain
on the Site. Five year reviews would be required for Alternative FDA-S-4, In-Situ SVE, during
operation of the system.
7 Cost
Alternative Total Cost
FDA-S-3 $ 993,000
FDA-S-8 $ 1,242,924
FDA S-5 $ 2,787,000
FDAS-7 $3,117,000
FDA S-6 $ 3,858,000
FDA S-4 $ 7,016,000
8. State Acceptance
The Commonwealth of Pennsylvania has had the opportunity to review and comment on all the
documents in the Administrative Record and has participated in selecting the remedy for this
Site. The Commonwealth has had the opportunity to comment on the draft ROD and, to the
extent possible, the Commonwealth's comments have been incorporated into the ROD.
9. Community Acceptance
A public meeting on the Proposed Plan was held on July 16, 1997 at the Great Valley High
School, East Whiteland Township, Pennsylvania. Comments received orally at the public
meeting and in writing during the comment period were generally not in favor of EPA's
proposed alternative FDA-S-8 for the Former Disposal Area soils. See Pan HI, Responsiveness
Summary of this ROD for detailed comments and responses.
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Former Disposal Area Groundwater Alternatives
1 Overall Protection of Human Health and Environment
Neither Alternative FDA-G-1, No Action, nor Alternative FDA-G-2, Institutional Controls,
would provide long-term protection of human health and the environment. These will not be
considered further.
Alternative FDA-G-5, Groundwater Collection, Treatment, and Discharge, would achieve overall
protection of human health and the environment by interception, removal and treatment of
contaminated groundwater. Alternative FDA-G-6, Groundwater Collection (Single Well),
Treatment, and Discharge, would achieve overall protection of human health and the
environment by capturing the most contaminated part of the plume. The remaining plume would
be reduced by natural attenuation.
2. Compliance with ARARs
Alternative MPA-G-4, Natural Attenuation will comply with chemical-specific ARARs at the
conclusion of the remedial action. Location-, and action-specific ARARs are not directly
applicable for this alternative.
Alternative FDA-G-4, Natural Attenuation, has been shown to be effective in preventing the
downgradient extension of the plume of contaminated groundwater. This alternative is a viable
and effective solution which would satisfy the ARARs in the long-term.
Alternative FDA-G-5, Groundwater Collection, Treatment, and Discharge, and Alternative FDA-
G-6, Groundwater Collection (Single Well), Treatment, and Discharge, would comply with
chemical-, location-, and action-specific ARARs.
3. Long-Term Effectiveness and Permanence
Alternative FDA-G-5, Groundwater Collection, Treatment, and Discharge, and Alternative FDA-
G-6, Groundwater Collection (Single Well), Treatment, and Discharge, would be the most
effective in the long-term since they incorporate removal and treatment of the groundwater,
which is not a reversible process.
Alternative FDA-G-4, Natural Attenuation, may be effective in the long-term. Contamination
would be remediated by natural attenuation mechanisms over time and the progress would be
tracked by groundwater monitoring.
4. Reduction of Toxicity. Mobility, and Volume through Treatment
Alternative FDA-G-5, Groundwater Collection, Treatment, and Discharge, and Alternative FDA-
G-6, Groundwater Collection (Single Well), Treatment, and Discharge, provide the most
significant reduction in toxicity, mobility, and volume at the source area of the Former Disposal
Area. FDA-G-6 ultimately relies on natural attenuation mechanisms to degrade the contaminant
plume below MCLs.
Reduction of toxicity, mobility, and volume for Alternative FDA-G-4, Natural Attenuation, is
dependant on natural attenuation mechanisms such as biological and abiotic attenuation. Abiotic
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attenuation includes volatilization, sorption, hydrolysis, and dehalogenation.
5 Short-Term Effectiveness
Alternative FDA-G-4, Natural Attenuation, involves no construction or Site activities and would
therefore produce no disturbance to the surrounding community and environment.
A temporary increase in air emissions and construction traffic on nearby roads would occur
during installation of the groundwater treatment system under Alternative FDA-G-5,
Groundwater Collection, Treatment, and Discharge, and Alternative FDA-G-6, Groundwater
Collection (Single Well), Treatment, and Discharge. Construction workers would be required to
use personal protective equipment. A temporary increase in fugitive emissions during treatment
system operation would occur. Off-gas from the treatment system may require treatment.
6. Implementability
All alternatives are technically implementable However, the implementability of any alternative
requiring Institutional Controls may be affected due to legal considerations. Alternative FDA-G-
4, Natural Attenuation, is readily implemented. Alternative FDA-G-5, Groundwater Collection,
Treatment, and Discharge, and Alternative FDA-G-6, Groundwater Collection (Single Well),
Treatment, and Discharge, incorporate standard construction practices and equipment is readily
available.
Five year reviews would be required for Alternative FDA-G-4, Natural Attenuation since.
contaminated groundwater would remain on the Site. Five year reviews would be required for
Alternative FDA-G-5, Groundwater Collection, Treatment, and Discharge, and Alternative FDA-
G-6, Groundwater Collection (Single Well), Treatment, and Disposal, during operation of the
systems or allowing the residual plume to degrade below MCLs.
7. Cost
FDA-G-4 is the least expensive at $979,647 followed by FDA-G-6 at $3,272,000 and FDA-G-5
at $8,258,000.
8. State Acceptance
The Commonwealth of Pennsylvania has had the opportunity to review and comment on all the
documents in the Administrative Record and has participated in selecting the remedy for this
Site. The Commonwealth has had the opportunity to comment on the draft ROD and, to the
extent possible, the Commonwealth's comments have been incorporated into the ROD.
9. Communit
A public meeting on the Proposed Plan was held on July 16, 1997 at the Great Valley High
School, East.Whiteland Township, Pennsylvania. Comments received were varied with respect
to installation of a pump and treat system at the Former Disposal Area. Oral and written
comments on the remedial alternatives evaluated by EPA for the implementation at the Site are
included in Part III of this ROD.
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X. SELECTED REMEDY AND PERFORMANCE STANDARDS
Based upon considerations of the requirements of CERCLA, the detailed analysis of the
alternatives using the nine criteria, and public comments, EPA has determined the following to
be the most appropriate remedy for the Site:
A. Water Supply: To prevent contact with groundwater contamination at residences affected
or potentially affected by the Site, EPA has selected Alternative WS-G-3a, Public
Water Supply.
B. Main Plant Area Soils: To prevent direct contact with contaminated soils in the Main
Plant Area and to reduce the potential for continued migration of these contaminants to
the groundwater, EPA has selected Alternative MPA-S-3, Capping.
C. Main Plant Area Groundwater: To restore the Site groundwater to beneficial use through
removal and treatment of contaminated groundwater. EPA has selected Alternative
MPA-G-6, Groundwater Collection, Treatment of Source Area, and Discharge.
D. Former Disposal Area/Mounded Area Soils: To reduce the potential for continued
migration of contaminants in these soils to the groundwater, EPA has selected
Alternative FDA-S-4, Excavation, Off-Site Thermal Treatment, Disposal at a
Hazardous Waste Landfill.
E. Former Disposal Area/Mounded Area Groundwater: To reduce concentrations of
contaminants in groundwater to MCLs, EPA has selected Alternative FDA-G-4,
Natural Attenuation.
The detailed requirements and performance standards associated with the selected remedy are
presented below.
A. Water Supply Remedy and Performance Standards
1. A source of potable water shall be provided year round to the residents listed in Table 14
by extending the existing waterline to the area of concern in the vicinity of the Site. The
Philadelphia Suburban Water Company (PWSC) currently supplies water to East
Whiteland Township, and has sufficient capacity at this time to provide water. PWSC
plans to install water mains in Phoenixviile Pike from Aston Road to Conestoga Road,
and to extend the existing main in Conestoga Road north to Bacton Hill Road by the end
of 1997. Therefore, this portion of the remedy addresses connections to the water mains
that will be in place prior to the implementation of the remedy. To provide the water
supply to the affected residents in Hillbrook Circle, a secondary main will be required
along with connections.
2. The water supply provided shall be in compliance with the Safe Drinking Water Act, 42
U.S.C. §§ 300(f)-300(j), and 40 C.F.R. § 141. The residences listed on Table 14 are
those which EPA believes to have been impacted or have the potential to be impacted by
the groundwater contamination from the Site. Approximately 52 residences are expected
to be connected to the public water supply.
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3. The water supply.system shall be constructed in compliance with PSWC, State and local
requirements. At a minimum, the water line shall be installed in a trench below the freeze
line and independent connections shall be brought from the main into each residence. All
areas impacted by construction activities shall be graded, restored, and revegetated, as
necessary.
4. Independent connections shall be brought from the main into each residence affected or
potentially affected by the contaminated groundwater.
5. Fire hydrants shall be installed in accordance with existing East Whiteland Township
requirements along the main into Hillbrook Circle and along Phoenixville Pike.
6. Following hook up, .costs of public water usage shall be the responsibility of the
residence.
7. The installation of the water line shall avoid, minimize, and mitigate impacts on
floodplains and wetlands. The performance standard will be in compliance with
Executive Order No. 11988 and 40 C.F.R. Part 6, Appendix A (regarding avoidance,
minimization, and mitigation of impacts on floodplains) and Executive Order No. 11990
and 40 C.F.R. Part 6, Appendix A (regarding avoidance, minimization, and mitigation of
impacts on wetlands).
8. The existing residential wells shall be abandoned in accordance with the requirements of
the Pennsylvania Safe Drinking Water Act 25 Pa. Code Section 109.62 and consistent
with PADEP's Public Water Supply Manual, Part II, Section 3.3.5.11 and Chester
County Health Department Rules and Regulations Chapter 500 unless selected by EPA
for long-term monitoring. Existing carbon filters installed and/or maintained by EPA
shall be removed from the residences.
9. RCRA listed constituents are present in the groundwater. Therefore, management of the
spent filters shall be in accordance with the substantive requirements of 25 Pa. Code
Chapter 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); and C (relating to pretransport requirements; 25 Pa. Code
Chapter 263 (relating to transporters of hazardous wastes); and with respect to the
operations at the Site generally, with the substantive requirements of 25 Pa. Code Chapter
264, Subparts B-D, I (in the event that hazardous waste generated as part of the remedy is
managed in containers); 25 Pa. Code Chapter 264, Subpart J (in the event that hazardous
waste is managed, treated, or stored in tanks), and 40 C.F.R. 268 Subpart C, Section
268.30, and Subpart E (regarding prohibitions on land disposal and prohibitions on
storage of hazardous waste).
10. All areas impacted by the construction activities during remedy implementation shall be
graded, restored and revegetated to the extent practicable.
11. The use of groundwater impacted by the Site shall be restricted through the
implementation of Institutional Controls, as set forth in Section X.C.7 and E.7-12.
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B. Main Plant Area Soils Remedy and Performance Standards
1. • Cap: The Main Plant Area shall be capped with a final cover designed and constructed to
provide long-term minimization of migration of liquids into the Main Plant Area soils.
The cap shall function with minimum maintenance and include a drainage layer to
promote drainage and minimize erosion. The cap shall shall accommodate settling and
subsidence and consist of a Flexible Membrane Liner (FML) or equivalent that achieves
a permeability less than or equal to 1 x 10 "7 cm/sec. The cap shall also be designed to
facilitate other components of the remedy including the groundwater extraction and
treatment system. The design of the cap should consider the existing use of the property.
The cap shall be installed over all areas of the Main Plant Area with surface or subsurface
soil contaminated above any of the following levels:
Contaminant Soil Clean-up Standard fmg/kg)
Trichloroethene (TCE) 0.70
l,l-Dichloroethene(l,l-DCE) 0.05
1,1 -Dichloroethane (1,1 -DCA) 0.39
Tetrachloroethene (PCE) 1.22
Vinyl Chloride 0.01
Methylene Chloride 0.50
Benzene 0.38
Ethylbenzene 74.00
Toluene 9.47
Xylene 8,790.00
These levels are based on an amount of residual contamination that if left in the soil,
would not cause the groundwater to be contaminated above Maximum Contaminant
Levels. See FS, Appendix B. The exact location and extent of the capped area shall be
determined during remedial design. Any existing equipment or aboveground storage
tanks in the area where the cap shall be placed shall be removed to complete the cap
construction in accordance with the requirements above.
2. An O&M program shall be implemented to maintain the integrity of the cap for a period
of 30 years. Maintenance shall include repairs to the cap as necessary to maintain the
permeability standard, correct any breaches, or any effects of settling, subsidence or
erosion. An operation and maintenance plan for the cap will be required, and is subject to
approval by EPA in consultation with the Commonwealth of Pennsylvania.
3. Structure Removal: The existing quonset hut structure (former container storage area) has
collapsed and is no longer acting as a cap to the soils beneath it. Therefore, the
collapsed quonset hut shall be decontaminated and removed. Once the structure is
removed, a representative sample shall be collected to determine if the quonset hut debris
is hazardous under RCRA. If hazardous, the quonset hut debris shall be decontaminated
in accordance with the Hazardous Debris Rule and properly disposed of or reused.
Soil sampling shall be conducted beneath the quonset hut to determine if soils are
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impacted above any of the clean up levels listed in B. 1 above. The cap shall be extended
to include this area, if soils are so impacted, and/or, in order to achieve the requirements
set forth in (1) above.
4. Tank Removal:
Underground Storage Tanks
The former USTs previously excavated, and currently located on property adjacent to
Chemclene, shall be decontaminated and properly disposed of or reused in accordance
with RCRA. Representative samples shall be collected and analyzed to confirm
decontamination. If the tanks continue to contain hazardous substances, they shall be
shipped to a proper off-Site disposal facility in accordance with RCRA. If it is
determined subsequent to decontamination that the tanks do not contain hazardous
substances, the tanks may be reused or disposed offSite.
5. Main Building: The area occupied by the Main Building shall serve as a cap consistent
with the Standards in (1) above. Presently, the building acts as a cap over an area of soils
at the Main Plant. The building shall be inspected and maintained so as to reduce
potential infiltration of precipitation to the extent possible and provide an effective cap
over the soils at this area of die Site. If and when the building no longer reduces potential
infiltration of precipitation and serves as an effective cap over the soils at the Main Plant
Area, the building shall be removed, in accordance with the provisions set forth in this
part.
In the event the building is removed, for any reason, soils beneath the removed building
shall then be analyzed to determine if contamination is present above any of the clean up
standards listed in B. 1 above. If contamination is above clean up standards, the cap as set
forth in (1), above shall be extended to cover this area.
6. Closure of the Main Building (including Loading Dock and Chemical Laboratory) .The
Main Building shall be closed in accordance with 25 Pa. Code 25 § 265.110 through
265.119, 265.442(7); 40 C.F.R §§ 264.110 through 264.120, 264.178, 270.14(b)(13).
Closure will consist of removal and proper disposal of all hazardous wastes;
decontamination of the floor, related distillation equipment, contaminated structures (i.e.
walls), and associated processing equipment. Contents of the building (i.e. process
equipment, lab chemicals, etc.) shall be sampled to determine if hazardous substances are
present. If hazardous substances are present, the material shall be shipped to a proper off-
Site disposal facility in accordance with RCRA.
7. Wastewater generated during decontamination activities shall be properly managed in
accordance with Pennsylvania Hazardous Waste Management regulations and/or the
Clean Water Act.
8 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 (SIP) for the Commonwealth of Pennsylvania, 25 Pa. Code §§ 123.1 - 123.2 and the
National Ambient Air Quality Standards for Paniculate Matter in 40 C.F.R. §§ 50.6 and
Pa. Code §§ 131.2 and 131.3.
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8. The Main Plant Area perimeter fence shall be maintained to prevent trespassing and
access to the Site during construction. The fence shall be maintained for 30 years to
prevent unauthorized access to the capped area.
9. The cap shall not be breached or adversely affected. The capped area may continue to be
used for commercial operations or other activities as long as the cap is not adversely
affected Institutional Controls shall be implemented to accomplish this.
C. Main Plant Area Groundwater Remedy and Performance Standards
1. Groundwater Remediation
The groundwater affected by contamination originating at the Main Plant Area shall be
remediated through extraction and treatment. Extraction well(s) shall be designed to
remediate the dissolved contaminant plume to MCLs listed in C.2 below. The exact
number and location of extraction well(s) shall be determined during the remedial design
phase. The degree to which natural attenuation can be incorporated into the pump and
treat system will be determined during remedial design A portion of the extraction
system shall be positioned to collect potential DNAPLs in the area of existing monitoring
wells CC-6 and CC-7. DNAPLs shall be contained if present, extracted to the degree
practicable, and disposed of off-Site.
2. Groundwater Treatment
a) The groundwater plume at the Main Plant Area shall be remediated until the MCL or
the non zero MCLG (whichever is more stringent) for all the contaminants of concern [40
C.F.R. part 141 ] is achieved. Since most CoPCs at the Site are members of the same
general class of chemicals and possess similar physical and chemical properties, the
selected treatment remedy at the Site will likely reduce or eliminate all contaminants
posing potential risks. The performance standards for the contaminants in the
groundwater at the Main Plant Area are listed below:
Contaminant MCL ft/y/A MCLG (ug/f)
Chloroform 100 0
Trichloroethene (TCE) 5 0
l,l-Dichloroethene(l,l-DCE) 7 7
l,2-Dichloroethane(l,2-DCA) 50
Tetrachloroethene (PCE) 5 0
Vinyl Chloride 2 0
b) Recovered groundwater shall be treated and reduced to MCLs via air stripping
followed by vapor phase granular activated carbon or U/V oxidation prior to reinjection.
The treatment system shall reduce the contaminants in the extracted groundwater,
unattended, on a continuous, 24-hour-per-day performance basis. A treatment plant shall
be capable of handling high contaminant concentrations because of the potential presence
of DNAPLs. A pilot study shall be conducted to determine the appropriate treatment
method to conform with drinking water standards. The final pumping rate and the exact
location, size, and number of extraction wells shall be determined during remedial design.
Final design criteria for the air stripper treatment system will be determined by EPA in
consultation with P ADEP. The design, construction and operation of the treatment
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system shall consider and reduce the possible visual and noise impacts to the surrounding
residences. The design, construction and operation of the treatment system shall be in
harmony with the surrounding community to the extent practicable.
c) The treated groundwater effluent shall be discharged to reinjection wells located to
maximize the performance of the remedy in 2.a above. The treated groundwater effluent
shall be reinjected in accordance with "Applicability of Land Disposal Restrictions to
RCRA and CERCLA Groundwater Treatment Reinjection", OSWER Directive #9234 1 -
06. The final number of injection wells, and their locations and configurations, shall be
determined in a pre-design study.
d) Any VOC emissions from the air stripper tower will be in accordance with the
Pennsylvania Department of Environmental Protection air pollution regulations outlined
in 25 Pa. Code §§ 121.1 -121.3, 121.7, 123.1, 123.2, 123.31, 123.41, 127.1, 127.11,
127.12, and 131.1-131.4. 25 Pa. Code § 127.12 requires all new air emission sources to
achieve minimum attainable emissions using the best available technology (BAT). In
addition, the PADEP air permitting guidelines for remediation projects require all air
stripping and vapor extraction units to include emission control equipment. Federal
Clean Air Act requirements, 42 U.S.C. §§ 7401 ej seq.T are applicable and must be met
for the discharge of contaminants to the air. Air permitting and emissions ARARs are
outlined in 40 C.F.R. §§ 264.1030 - 264.1034 (Air Emissions Standards for Process
Vents), and 40 C.F.R. §§ 264.1050 - 264.1063 (Air Emissions Standards for Equipment
Leaks). Air emissions of vinyl chloride will comply with 40 C.F.R. Parts 61.60 - 61.69,
National Emission Standards for Hazardous Air Pollutants (NESHAPS). OWSER
Directive #9355.0-28, Control of Air Emissions from Superfund Air Strippers at
Superfiind Ground Water Sites, is a "to be considered" (TBC) requirement.
e) Management of waste from the operation of the treatment system (i.e. spent carbon
units, DNAPLs) shall comply with the requirements of: 25 Pa. Code Chapter 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); and C (relating to pretransport requirements); 25 Pa. Code Chapter
263 (relating to transporters of hazardous wastes); and with respect to the operations at
the Site generally, with the substantive requirements of 25 Pa. Code Chapter 264,
Subparts B-D, I (in the event that hazardous waste generated as part of the remedy is
managed in containers); 25 Pa. Code Chapter 264, Subpart J (in the event that hazardous
waste is managed, treated or stored in tanks); and 40 C.F.R. 268 Subpart C, Section
268.30, and Subpart E (regarding prohibitions on land disposal and prohibitions on
storage of hazardous waste).
3. The extraction and treatment system shall avoid, minimize, and mitigate impacts on
floodplains and wetlands. The performance standard will be in compliance with
Executive Order No. 11988 and 40 C.F.R. Part 6, Appendix A (regarding avoidance,
minimization and mitigation of impacts on floodplains) and Executive Order No. 11990
and 40 C.F.R. Part 6, Appendix A (regarding avoidance, minimization, and mitigation of
impacts on wetlands).
4. Fugitive dust emissions generated during remedial activities will be controlled in order to
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comply with fugitive dust regulations in the federally-approved State Implementation
Plan (SIP) for the Commonwealth of Pennsylvania, 25 Pa. Code §§ 123.1 - 123.2. and
the National Ambient Air Quality Standards for Paniculate Matter in 40 C.F R §§ 50 6
and Pa. Code §§ 131.2 and 131.3
5. The extraction and reinjection systems shall achieve the substantive requirements of the
Delaware River Basin Commission (DRBC) (18 C.F.R. Part 430). These regulations
establish requirements for the extraction and discharge of groundwater within the
Delaware River Basin. However, modifications to the Selected Remedy as a result of the
DRBC requirements are not anticipated.
6. Monitoring
a) The performance of the extraction and treatment system shall be monitored
through the use of monitoring wells. EPA, in consultation with PADEP, will determine if
additional monitoring wells are necessary to determine the extent of the groundwater
plume or performance of the system.
b) At least one round of samples shall be collected from existing Site monitoring wells as
well as any additional monitoring wells installed, during the predesign phase, and
analyzed for VOCs, in order to determine the extent of groundwater contaminant plume
at that time. Any new wells installed must be drilled in accordance with 25 Pa. Code
Chapter 107. These regulations are established pursuant to the Water Well Drillers
License Act 32 PS § 645.1 et seq
c) An operation and maintenance plan shall be developed for the groundwater
extraction system during the remedial design phase. The operation and maintenance plan
shall be developed and implemented to determine the operation and performance of the
system within design criteria and achievement of performance standards. At a minimum,
the influent and effluent from the treatment facility shall be sampled twice per month for
VOCs. Operation and maintenance of the groundwater extraction system shall continue
for an estimated 30 years or such other time period as EPA, in consultation with PADEP,
determines to be necessary, based on the statutory reviews of the remedial action
conducted every five years from the initiation of the remedial action. The performance of
the groundwater extraction and treatment system shall be carefully monitored on a regular
basis, as described below in the Section 6.g of this Selected Remedy. The system may be
modified, as warranted by performance data during operation to achieve Performance
Standards. These modifications may include for example, alternate pumping of
extraction well(s), the addition or elimination of certain extraction wells and, changes in
reinjection location.
d) The operation and maintenance plan shall be revised after construction of the
treatment system has been completed if it is determined to be necessary by EPA.
e) Five year statutory reviews under Section 121(c) of CERCLA shall be required, as
long as hazardous substances remain on-Site and prevent unlimited use and unrestricted
access to the Site. Five year reviews shall be conducted at the initiation of the remedial
action in accordance with EPA guidance document, Structure and Components ofFive-
Year Reviews (OSWER Directive 9355.7-02, May 23, 1991).
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0 Existing pumping and/or monitoring wells which serve no useful purpose shall be
properly plugged and abandoned consistent with PADEP's Public Water Supply
Manual, Part II, Section 3.3.5.11 and Chester County Health Department Rules and
Regulations Chapter 500, in order to eliminate the possibility of these wells acting as a
" conduit for future groundwater contamination. Wells which EPA determines are
necessary for use during the long term monitoring program will not be plugged.
g) A long-term groundwater monitoring program shall be implemented to evaluate the
effectiveness of the groundwater extraction and treatment system at the Main Plant Area.
i) The plan for the long-term groundwatermonitoring program shall be included in
the operation and maintenance plan for the groundwater extraction and treatment system.
The plan shall include the sampling of a sufficient number of wells to monitor the
effectiveness of the remedial action. EPA, in consultation with PADEP, will determine
the number and location of monitoring wells necessary to verify the performance of the
remedial action.
ii) The installation of additional monitoring wells will be required. Numbers and
locations of these monitoring wells shall be determined by EPA during the remedial
design, in consultation with the PADEP.
iii) The wells shall be sampled quarterly for the first three years. Based on the
findings of the first three years of sampling, the appropriate sampling frequency for
subsequent years will be determined by EPA, in consultation with the PADEP.
iv) Sampling and operation and maintenance shall continue until such time as
EPA, in consultation with PADEP, determine that the performance standard for each
contaminant of concern has been achieved throughout the entire area of groundwater
contamination.
v) If EPA, in consultation with PADEP, makes such determination, the wells
shall be sampled for twelve consecutive quarters throughout the entire plume and if
contaminants remain at or below the performance standards, the operation of the
extraction system shall be shut down.
vi) Annual monitoring of the groundwater shall continue for five years after the
system is shutdown.
vii) If subsequent to an extraction system shutdown, annual monitoring shows
that groundwater concentrations of any contaminant of concern are above the
Performance Standard set forth above, the system shall be restarted and continued until
the performance standards have once more been attained for twelve consecutive quarters
Annual monitoring shall continue until EPA determines, in consultation with the PADEP,
that the Performance Standards in 2.a above for each contaminant of concern has been
achieved on a continuing basis.
7. Institutional Controls
No newly commenced or expanded groundwater pumping in the aquifer shall be
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implemented'which will adversely affect the plume migration. The Site shall be identified
as property underlain by contaminated groundwater. Human consumption of
contaminated groundwater shall be prevented. Institutional Controls shall be
implemented to achieve these items.
D. Former Disposal Area/Mounded Area Soils Remedy and Performance Standards
1 All soils with contaminant concentrations exceeding any of the following soil clean-up
performance standards shall be excavated and removed from the Former Disposal
Area/Mounded Area:
Contaminant Soil Clean-up Standard fmg/kg^
Trichloroethylene (TCE) 0.70
U-Dichloroethene(U-DCE) 0.05
l,l-Dichloroethane(l,l-DCA) 0.39
1,1,1 Trichloroethane (1,1,1 TCA) 45.00
Tetrachloroethene (PCE) 1.22
Vinyl Chloride 0.01
Methylene Chloride 0.50
PCBs 1.00
Since most CoPCs at the Site are members of the same general class of chemicals and
possess similar physical and chemical properties, the selected remedy at the Site will
likely reduce or eliminate all contaminants posing potential risks. An estimated 5,700
cubic yards of soil with contaminant concentrations exceeding the above performance
standards is present at the Former Disposal Area/Mounded Area. Additional sampling
shall be performed during the remedial design to determine the full extent of required
excavation of the subsurface soil contamination. During the previous investigations at
the Former Disposal Area/Mounded Area, low level PCB contamination was detected in
surface samples, however, subsurface soils were not fully characterized for PCBs during
the RI. Therefore, any sampling conducted during the remedial design will require PCB
analysis. The number and location of the soil samples, the analytical parameters, and
methods will be determined by EPA, in consultation with PADEP, during the remedial
design phase.
2. Structural stability of open excavations shall be maintained with temporary shoring or
engineering measures as appropriate. Excavation will begin using a backhoe, and the
sides of the excavation area shall be cut back to a minimum 2 to 1 slope to prevent side
wall failure. Air monitoring shall be conducted during excavations to ensure safety of
Site workers and nearby residents living in the vicinity of the Site.
3. Sediment and erosion controls and temporary covers will be installed to protect exposed
soil from the effects of weather consistent with PADEP's Bureau of Soil and Water
Conservation Erosion and Sediment Pollution Control Manual. Erosion potential shall be
minimized. Further, controls in the form of Site grading to improve land grades, cover
soils, vegetation, and drainage channels to reduce erosion potential from surface runoff
may be required to minimize erosion. Contaminated soils shall be prevented from being
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washed into on-Site surface water and adjacent uncontaminated and uncontrolled wetland
areas during remedial action implementation. The extent of erosion control necessary
will be determined by EPA, in consultation with the PADEP, during the remedial design
phase.
4. Post-excavation sampling will be performed after the excavation is completed. Post-
excavation samples will be obtained from the base and the sidewalls of the excavation to
ensure that contamination is not present above the soil clean-up Performance Standards
specified in D. 1. The location of the post-excavation samples will be selected based on
visual observation of lithology and screening for VOCs using an appropriate organic
vapor detector. The samples will be analyzed for VOCs and PCBs on a quick turnaround
basis using a method approved by EPA.
5. If the post-excavation sample concentrations are below all the clean-up levels, the
excavation will be backfilled using clean soil. Clean borrow material will be brought in
to restore the excavation to original grade. Backfilling will be performed, and the
material will be compacted to minimize the potential for subsidence. The excavation area
shall be covered with a layer of cover soil and revegetated with native plant material until
a viable cover is established. Any on Site landscaping will be in accordance with Office
of the Federal Executive; Guidance for Presidential Memorandum on Environmentally
and Economically Beneficial Landscape Practices on Federal Landscaped Grounds, 60
Fed. Reg. 40837 (August 10, 1995) which is a "to be considered" (TBC) requirement.
6. If VOCs or PCBs are-detected at levels above any of the soil clean up Performance
Standards in the post-excavation samples, additional material will be removed from the
excavation area and new samples obtained for analysis as discussed in D. 1. Excavation
and sampling activities will continue until the results indicate that the soils do not contain
contaminants of concern above any of the performance standards. The excavation area
will then be restored as described in D.5.
7. RCRA listed constituents will exist in the excavated soil, therefore, the remedy will be
implemented consistent with the following substantive requirements, which are
applicable to on-Site activities, of Pa. Code §§ 262.11 - 262.13 (relating to hazardous
waste determination and identification numbers), 25 Pa. Code § 262.34 (relating to
pretransport requirements); 25 Pa. Code Chapter 263 (relating to transporters of
hazardous wastes); and with respect to the operations at the Site generally, with the
substantive requirements of 25 Pa. Code Chapter 264, Subparts B-D, I (in the event that
hazardous waste is generated as part of the remedy).
8. 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 (SIP) for the Commonwealth of Pennsylvania, 25 Pa. Code §§ 123.1 - 123.2. and the
National Ambient Air Quality Standards for Paniculate Matter in 40 C.F.R. §§ 50.6 and
Pa. Code §§ 131.2 and 131.3
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E. Former Disposal Area/Mounded Area Groundwater Remedy and Performance
Standards
1 . A Natural Attenuation groundwater monitoring program shall be implemented to
determine that natural attenuation is occurring, and that the groundwater plume will not
enlarge or migrate into areas not presently affected by the source area at the Former
Disposal Area/Mounded Area. Monitoring shall be conducted until the MCL or the non-
zero MCLG for all the the contaminants of concern [ 40 C.F.R. part 141] whichever is
more stringent is achieved. Since most CoPCs at the Site are members of the same
general class of chemicals and possess similar physical and chemical properties, the
selected remedy at the Site will likely reduce or eliminate all contaminants posing
potential risks.
The performance standard for the contaminants in the groundwater are listed below:
Contaminant MCL (uf/f) MCLG (ug/h
Chloroform 100.0 0
Trichloroethene 5.0 0
l,l-Dichloroethene(l,l-DCE) 7.0 2
l,2-Dichloroethane(l,2-DCA) 5.0 0
Tetrachloroethene (PCE) 5.0 0
2 The Natural Attenuation program shall include the sampling to monitor the effectiveness
of the Natural Attenuation program. Monitoring shall include sampling of the
groundwater discharging to Valley Creek and surface water within Valley Creek to
ensure that the groundwater plume does not impact the creek. The necessary monitoring
shall be determined during Remedial Design and shall be provided in a Natural
Attenuation Monitoring Plan. EPA, in consultation with PADEP, will determine the
number and location of monitoring wells, number and location of creek samples, and
monitoring parameters necessary to verify the performance of the remedial action.
Installation of additional wells may be necessary and must be in accordance with 25 Pa.
Code Chapter 107. These regulations are established pursuant to the Water Well Drillers
License Act, 32 P.S.§ 645.1
3. The wells and creek sampling points shall be sampled quarterly for the first three years.
The samples shall be analyzed for VOCs and natural attenuation parameters at each
sampling location. The natural attenuation parameters will be determined by EPA in
consultation with PADEP during Remedial Design. Based on the findings of the first
three years of sampling, the appropriate sampling frequency for subsequent years will be
determined by EPA in consultation with the PADEP.
4. Monitoring shall continue until such time as EPA, in consultation with PADEP,
determine that the performance standard for each contaminant of concern has been
achieved. If EPA and the Commonwealth make such a determination, the wells shall be
sampled for twelve consecutive quarters throughout the entire plume and if contaminants
remain at or below the performance standards, the monitoring program shall be
discontinued.
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5. Five year statutory reviews under Section 121 (c) of CERCLA will be required, as long as
hazardous substances remain onsite and prevent unlimited use and unrestricted access to
the Site. Five year reviews shall be conducted at the initiation of the remedial action in
accordance with EPA-guidance document, Structure and Components of Five-Year
Reviews (OSWER Directive 9355.7-02, May 23, 1991).
6. Existing monitoring wells which serve no useful purpose shall be properly plugged and
abandoned consistent with PADEP's Public Water Supply Manual, Part II, Section
3.3.5.11 and Chester County Health Department Rules and Regulations Chapter 500, in
order to eliminate the possibility of these wells acting as a conduit for future groundwater
contamination and to prevent adverse impacts to the remedy. Wells which EPA
determines are necessary for use during the long term monitoring program will not be
plugged.
7. No newly commenced or expanded groundwater pumping in the aquifer shall be
implemented which will adversely affect the plume migration. Institutional controls will
be used to identify the Site as property underlain by contaminated groundwater, and to
prevent the human consumption of contaminated ground water.
8. Drinking water supply wells shall not be installed in the area of the contaminated
groundwater plume.
10. No new development at or near the Site shall adversely affect the natural hydraulic •
containment and plume migration.
11. Title restrictions along with other appropriate means shall be used to implement the
requirements above.
12. Title restrictions will be appropriately recorded with the Chester County Recorder of
Deeds.
FUTURE POSSIBLE CHANGES IN ACCORDANCE WITH NCP
Groundwater Extraction and Treatment System
It may become apparent during implementation or operation of the groundwater extraction
system and its modifications, that contaminant levels have ceased to decline and are remaining
constant at levels higher than Performance Standards over some portion of the contaminant
plume originating from the Main Plant Area. If EPA, in consultation with PADEP, determines
that implementation of the selected remedy demonstrates, in corroboration with hydrogeological
and chemical evidence, that it will be technically impracticable to achieve and maintain the
Performance Standards throughout any part of the contaminant plume, EPA, in consultation with
PADEP, may require that any or all of the following measures be taken, for an indefinite period
of time, as further modification(s) of the existing system:
a) long-term gradient control provided by modified pumping, as a containment measure;
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b) chemical-specific ARARs may be waived for those portions of the aquifer that EPA
determines, in consultation with PADEP, are technically impracticable to achieve. Such
determinations shall be reevaluated at each subsequent five-year review;
c) institutional controls may be provided/maintained to restrict access to those portions
of the aquifer where contaminants remain above performance standards; and
d) remedial technologies for groundwater restoration may be reevaluated.
The decision to invoke any or all of these measures may be made during implementation or
operation of the remedy or during the 5-year reviews of the remedial action. If such a
decision is made, EPA shall amend the ROD or issue an Explanation of Significant
Differences.
Natural Attenuation
It may become apparent during implementation of the Natural Attenuation program that
contaminant levels have ceased to decline and are remaining constant at levels higher than
Performance Standards over some portion of the contaminant plume. EPA, in consultation with
PADEP, may require that any or all of the following measures be taken, for an indefinite period
of time, as further modification(s) of the remedial action:
a) chemical-specific ARARs may be waived for those portions of the aquifer that EPA
determines, in consultation with PADEP, are technically impracticable to achieve. Such
determinations shall be reevaluated at each subsequent five-year review;
b) institutional controls may be provided/maintained to restrict access to those portions
of the aquifer where contaminants remain above performance standards; and
c) remedial technologies for groundwater restoration may be reevaluated.
The decision to invoke any or all of these measures set forth above may be made during
implementation or operation of the remedy or during the 5-year reviews of the remedial action.
If such a decision is made, EPA shall amend the ROD or issue an Explanation of Significant
Differences.
XI. STATUTORY DETERMINATIONS
The following sections discuss how the selected remedy for the Malvern TCE Site meets these
statutory requirements.
A. Protection of Human Health god the Environment
Based on the Baseline Human Health Risk Assessment for the Site, measures should be
considered to reduce potential risk from the following sources. (1) VOCs in the groundwater and
(2) VOCs in subsurface soils. These media and contaminants were selected because potential
health hazards for some exposure scenarios exceeded the EPA target range of 1.0 x 1CT4 (or 1 in
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10,000), and 1.0 x 10* (or 1 in 1,000,000) for lifetime cancer risk or a non-cancer Hazard Index
of one (1). The results of the Ecological Risk Assessment show the potential for risk to
ecological receptors; however, the selected remedy will address this concern.
The extension of a public water supply called for in the selected remedy will provide a
permanent alternative water supply to affected and potentially affected residences and businesses
which will prevent current human exposure to groundwater contaminants. However, it will not
actively reduce the contaminants in the soil or groundwater, or prevent migration of
contaminated groundwater from the source areas of the Site.
The installation of a cap over soil at the Main Plant Area will reduce the infiltration of
precipitation, thereby eliminating the potential for contaminant migration to the groundwater and
preventing future exposure through ingestion, inhalation and dermal contact of groundwater.
The selected remedy protects human health and the environment at the Main Plant Area
of the Site by reducing levels of contaminants in the groundwater to those levels required by
ARARs through extraction and treatment. The groundwater extraction and treatment system
shall reduce the levels of contaminants of concern in the groundwater to achieve MCLs as
required by the Safe Drinking Water Act, 42 U.S.C. §§ 300(f) - 300(j), and 40 C.F.R. § 141.61.
Reinsertion of treated groundwater will not adversely affect human health or the environment,
provided that all Performance Standards and ARARs are met.
The excavation of soil at the Former Disposal Area will protect human health and the
environment by removing the contaminated soil, thereby eliminating the potential for
contaminant migration to the groundwater and preventing future exposure through ingestion,
inhalation and dermal contact.
The selected remedy protects human health and the environment at the Former Disposal
Area by reducing levels of contaminants in the groundwater to those levels required by ARARs
through Natural Attenuation. Natural Attenuation shall reduce the levels of contaminants of
concern in the groundwater to achieve MCLs as required by the Safe Drinking Water Act, 42
U.S.C. §§ 300(f) - 3000), and 40 C.F.R. § 141.61. Reinjection of treated groundwater will not
adversely affect human health or the environment, provided that all Performance Standards and
ARARs are met.
Implementation of the selected remedy will not pose any unacceptable short term risks or
cross media impacts to the Site, or the community.
B. Compliance with and Attainment of Applicable or Relevant and Appropriate
Requirements f "ARARg">
The selected remedy will comply with all applicable or relevant and appropriate chemical-
specific, location-specific and action-specific ARARs as discussed above in Section X of this
ROD and summarized on Table 13.
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C. Cost-Effectiveness
The selected remedy is cost-effective in providing overall protection in proportion to cost,
and meets all other requirements of CERCLA. Section 300.430(f) (ii) (D) of the NCP requires
EPA to evaluate cost-effectiveness by comparing all the alternatives which meet the threshold
criteria - protection of human health and the environment and compliance with ARARs - against
three additional balancing criteria: long-term effectiveness and permanence, reduction of
toxicity, mobility or volume through treatment; and short-term effectiveness. The selected
remedy meets these criteria and provides for overall effectiveness in proportion to its cost
Water Supply: Alternative WS-G-3a, Public Water Supply, $505,971.
• Main Plant Area Soils: Alternative MPA-S-3, Capping, $940,441.
• Main Plant Area Groundwater: Alternative MPA-G-6, Groundwater Collection,
Treatment of Source Area, and Discharge, $6,280,000.
• Former Disposal Area/Mounded Area Soils: Alternative, FDA-S-4, Excavation, Off-
Site Thermal Treatment, Disposal at a Hazardous Waste Landfill, $7,016,000.
• Former Disposal Area/Mounded Area Groundwater: FDA-G-4, Natural Attenuation,
$786,739.
The combined estimated present worth cost for the selected remedy presented in this Record of
decision is $15,529,151. The proposed plan estimated that the preferred alternative would cost
$14,592,000. The difference in estimated costs from the Proposed Plan to this ROD is primarily
due to the remedy changes outlined in Section XII of this ROD (page 67).
D. Utilization of Permanent Solutions and Alternative Treatment Technologies to the
Mail mum Extent Practicable
EPA has determined that the selected remedy represents the maximum extent to which
permanent solutions and treatment technologies can be utilized while providing the best balance
among the other evaluation criteria. Of those alternatives evaluated that are protective of human
health and the environment and meet ARARs, the selected remedy provides the best balance of
tradeoffs in terms of long-term and short-term effectiveness and permanence, cost effectiveness,
implementabiliry, reduction in toxicity, mobility, or volume through treatment, State and
community acceptance, and preference for treatment as a principal element.
Under the selected remedy, groundwater extraction through source and migration control
wells and treatment of groundwater using air stripping is more cost-effective than the other
alternatives evaluated. The selected remedy will reduce contaminant levels in the Class IIA
aquifer, a known source of drinking water, and reduce the risks associated with ingestion and
inhalation of the groundwater to the maximum extent practicable, as well as provide long-term
effectiveness.
The selection of excavation and off-Site disposal of contaminated soils at the FDA,
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provides the best balance of trade offs among the nine NCP selection criteria. The remedy
provides the highest degree of long-term effectiveness and permanence, reduces mobility and
reduces risk to human health and the environment.
The selected remedy for the Main Plant Area provides the highest feasible degree of long-
term effectiveness and permanence, reduces mobility and reduces risk to human health and the
environment. Cleanup of Main Plant Area soils is particularly challenging since they contain
high levels of complex contamination down to 100 feet deep (see section VI. A, pp. 6 - 9).
Accordingly, the alternatives of excavation and off-site treatment and disposal, or, several
possible in-situ treatment methods for these soils, were considered infeasible and screened out
during the Feasibility Study. Soil vapor extraction (SVE) was evaluated carefully by EPA, as
Alternative MPA-S-4. However, EPA concluded that although it may have been possible to
remediate some of these soils using this method, the selected remedy of capping provides an
equivalent level of protection and long-term effectiveness. The soil capping remedy will be
combined with long-term institutional controls and a groundwater remedy designed to achieve
and maintain MCLs. An on-going business also operates in the area of the soil contamination.
EPA therefore has attempted to utilize permanent solutions and alternative treatment
technologies to the maximum extent practicable for the unique conditions at the Main Plant Area.
E. Preference for Treatment as a Principal Element
The selected remedy satisfies, in part, the statutory preference for treatment as a principal
element. The contaminated groundwater alternative (MPA-G-6) addresses the primary threat of
future ingestion and inhalation of contaminated groundwater through treatment using air
stripping. In addition, the soils at the Former Disposal Area/Mounded Area will be treated off-
Site prior to disposal.
XH. DOCUMENTATION OF CHANGES FROM PROPOSED PLAN
The Proposed Plan identifying EPA's preferred alternative for the Site was released for comment
on June 23, 1997. During the public comment period, EPA received numerous comments from
the responsible parties and local community regarding EPA's Proposed Remedy. The changes
discussed below are detailed in Pan III of this ROD. (See Pan III of this ROD) The selected
remedy described in this ROD differs from the remedy in the Proposed Plan with regard to the
following:
1) Main Plant Area Soils: EPA has reconsidered adoption of SVE at the Main Plant Area soils.
EPA believes that although it may have been possible to remediate some of the soils at the Main
Plant, the selected remedy (S-3, Capping) provides an equivalent level of protection and long-
term effectiveness as the originally proposed remedy, while being more cost effective.
2) Former Disposal Area/Mounded Area Soils: EPA has reconsidered the movement of
contaminated soils from the Former Disposal Area/Mounded Area to the Main Plant Area for
consolidation. As a result, EPA has modified the preferred remedy and has selected FDA-S-4,
Excavation, Off-Site Thermal Treatment and Disposal at a Hazardous Waste Treatment and
Disposal Facility. Although the selected remedy for the soils is more costly than EPA's
originally preferred remedy, EPA believes this modification provides the best balance of
tradeoffs in long-term and short-term effectiveness and permanence, cost effectiveness,
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implementability, reduction in toxicity, mobility, or volume through treatment, State and
Community acceptance, and preference for treatment as a principal element.
3) Former Disposal Area/Mounded Area Groundwater: During the public comment period, EPA
received numerous comments regarding the extraction and treatment of groundwater at the
Former Disposal Area/Mounded Area. As a result, EPA again reviewed the available data
regarding the natural attenuation of groundwater at the Former Disposal Area/Mounded Area
Based upon this review, EPA has made a modification from the Proposed Remedy and has
selected FDA-G-4. EPA believes that FDA-G-4 provides an equivalent level of protection and
long-term effectiveness as the originally proposed remedy, while being more cost effective.
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APPENDIX A - TOXICOLOGICAL PROFILES OF SELECTED SITE CONTAMINANTS
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Carbon Tetrachloride (Tetrachloroethane)
Tetrachloroethane (TCA), more commonly referred to as carbon tetrachloride, is a clear, heavy
liquid with a sweet aromatic odor. It is a synthetic chemical with no natural sources. Because it
evaporates very easily, it is not usually encountered in its liquid state in the environment.
Carbon tetrachloride is readily absorbed from the gastrointestinal tract and more slowly absorbed
through the lungs and skin. Most carbon tetrachloride leaves the body by being exhaled through
the lungs within a few hours after exposure.
Acute exposures of carbon tetrachloride to humans have shown a wide range of effects. Prior
exposure to alcohol, phenobarbital, and some pesticides have been shown to increase the effects
of carbon tetrachloride. Single exposures to low concentrations may cause symptoms such as
irritation of the eyes, moderate dizziness and headache which disappear once exposure is
discontinued. Exposure to higher concentrations will cause the same symptoms as above, but
additional symptoms of nausea, loss of appetite, mental confusion, agitation and the feeling of
suffocation may be seen. Chronic exposure to carbon tetrachloride produces symptoms of
fatigue, lassitude, giddiness, anxiety, headache and muscle twitching. Organ damage is usually
restricted to the liver, although there are some reported cases of kidney damage. After chronic
exposure there is usually regeneration in these organs. Carbon tetrachloride is carcinogenic in
animals producing mainly liver tumors. The USEPA has classified carbon tetrachloride as a
group B2 carcinogen indicating that, based on animal studies, it is probably a human carcinogen,
although there are no adequate studies of cancer in humans.
Most carbon tetrachloride is released to the environment in the atmosphere. Although it is
moderately soluble in water, its high rate of volatilization results in only about 1% of the total
carbon tetrachloride in the environment being in surface waters and oceans Likewise, carbon
tetrachloride tends to volatilize from tap water used for showering, bathing and cooking inside a
hqme(ATSDR, 1989a).
1,1'Dichloroethene (1,1-DCE)
1,1 -DCE is used to make certain plastics, such as packaging materials and flexible films like
SARAN wrap, and flame -retardant coatings for fiber and carpet backing. It is a clear, colorless
liquid and has a mild, sweet smell like chloroform. 1,1-DCE is considered highly volatile and
readily migrates to the atmosphere, where it is photo-oxidized by reaction with hydroxyl radicals.
It readily volatilizes through the air-filled pores in near-surface soils. Based on a soil sorption
coefficient (K^.) value of 65, this compound is expected to be only weakly sorbed to soils. This
compound is not expected to undergo hydrolysis or microbial degradation in natural systems. In
unsaturated near-suiface soils, depending on several factors, including percent organic material,
about 60 percent of the compound is expected in the gaseous phase, with only 3 percent in the
aqueous phase and the remainder absorbed to soil. In deeper soils, 78 percent of the compound
is expected to be in the aqueous phase. That portion of the compound that does not volatilize
from soil may be expected to be mobile in groundwater.
EPA reports a chronic oral RfD of 9.0 x 10° mg/kg-day with the stipulation that the RfD is
currently under review (IRIS, 1995). This RfD has an uncertainty factor (UF) of 1000. The
confidence in the study, the database, and the RfD is medium. EPA lists the same value for the
AR302658
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MAL VERN TCE SUPERFUND SITE
interim subchronic RfD (HEAST, 1992) No inhalation RfCs are available, however a risk
assessment for this compound is under review by an EPA work group (IRIS, 1995)
The oral RfDs were derived from a chronic oral bioassay in which rats were provided drinking
water containing either 50, 100, or 200 mg/L 1,1-dichloroethene. The authors calculated intakes
to be 7, 10, and 20 mg/kg/day for male rats and 9, 14, and 30 mg/kg/day for female rats (IRIS,
1995). The female rats evidenced hepatic lesions at all exposure levels, while the males only
showed a significant effect at 200 mg/L. Therefore, the LOAEL was set at 9 mg/kg- day; a
NOAEL could not be determined.
1,1-DCE has been classified by EPA (IRIS, 1995) as a group C (possible human) carcinogen.
This classification indicates limited evidence of carcinogenicity in animals with inadequate
evidence of human carcinogenicity and is based on the results of tumors observed in one mouse
strain following an inhalation exposure to 25 ppm of 1,1-DCE for 5 days/week for 52 weeks
(IRJS, 1995). EPA has established an oral CSF of 0.6 (mg/kg/day)'1 (BUS, 1995) and an
inhalation Carcinogenic Slope Factor (CSF) of 0.18 (mg/kg/day)'1 (IRJS, 1995). The oral CSF is
only valid if the water concentration is below 600 mg/L, and the inhalation CSF is only valid if
the air concentration is less than 200 mg/m3.
EPA lists a one-day health advisory of 2 mg/L and a ten-day health advisory of 1 mg/L (Drinking
Water Standards and Health Advisories). The ambient water quality criteria for water and fish
consumption is 3.3 x 10-2 mg/L and for fish ingestion only is 1.85 mg/L.
EPA (1986) reports an acute concentration of 11,600 mg/L for the dichloroethenes as the LOEC
in aquatic systems. 1,1-DCE has a relatively low octanol/water partition coefficient (5.37) and a
BCF range from 20 to 30, which indicates that 1,1-DCE may not accumulate significantly in
animals (Lyman el at., 1982). 1,1 -DCE is not very toxic to freshwater or saltwater fish species,
with acute LC50 values ranging from 80 to 200 mg/L (EPA, 1980).
cis- 1,2-DCE and trans- 1,2-DCE
1,2-DCE exists in two isomeric forms, cis- 1,2-DCE arid trans- 1,2-DCE, that are colorless,
volatile liquids with a slightly acrid odor. 1,2-DCE is prepared commercially by either the direct
chlorination of acetylene or by the reduction of 1,1,2,2-TCA with fractional distillation used to
separate the two isomers. 1,2-DCE can also be formed as a by-product during the manufacture
of other chlorinated compounds. Commercial use is not extensive, but trans-1,2-DCE and
mixtures of cis- and trans- 1,2-DCE have been used as intermediates in the production of other
chlorinated solvents and compounds, as well as low temperature extraction solvents for dyes,
perfumes, and lacquers. Both cis- and trans- 1,2-DCE are moderately flammable and react with
alkalis to form chloracetylene gas, which spontaneously ignites in air.
Information on the toxicity of 1,2-DCE in humans and animals is limited. Workers acutely
exposed to 1,2-DCE have been reported to suffer from drowsiness, dizziness, nausea, fatigue and
eye irritation. Acute and subchronic oral and inhalation studies of trans-1,2-DCE and acute
inhalation studies of cis-1,2-DCE indicate that the liver is the primary target organ in animals;
toxicity being expressed by increased activities of liver associated enzymes, fatty degeneration
and necrosis. Secondary target organs include the central nervous system and lung.
AR302859
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MAL VERN TCE SUPERFUND SITE
Limited information exists on the absorption, distribution, and excretion of 1,2-DCE in either
humans or animals. In vitro studies have shown that the mixed function oxidizes will metabolize
1,2-DGE, the final metabolic products are dependent on the initial isomer of 1,2-DCE.
On the basis of an unpublished study describing decreased hemoglobin and hematocrits in rats
treated by gavage for 90 days, EPA (1990a, b) assigned a subchronic and chronic oral RfD for
cis-1,2-DCE of 1E-1 mg/kg/day and 1E-2 mg/kg/day, respectively. The RfDs were derived from
a NOAEL Lowest Observed Adverse Affect Level (LOAEL) of 32 mg/kg/day. An inhalation
•RfC for cis-1,2-DCE has not been derived.
Subchronic and chronic RfDs of 2E-1 mg/kg/day and 2E-2 mg/kg/day, respectively, for
trans-1,2,-DCE have been calculated. The RfDs were derived from a LOAEL of 175 mg/kg/day
based on the increase of serum alkaline phosphatase activity in mice that received trans-1,2-DCE
in their drinking water. An RfC for trans-l,2-DCE has not been derived.
No information was available concerning the chronic, developmental or reproductive toxicity of
cis-1,2-DCE or trans-1,2-DCE. No cancer bioassays or epidemiological studies were available to
assess the carcinogenicity of 1,2-DCE. EPA has placed cis-1,2-DCE in weight-of-evidence
Group D (not classifiable as to human carcinogenicity) based on the lack of human or animal
carcinogenicity data and on essentially negative mutagenicity data. Trans-1,2-DCE has not been
classified.
Because of its volatility, the primary route of 1,2-DCE exposure to humans is by inhalation,
although dermal and oral exposure can occur. Exposure to 1,2-DCE may occur as a result of
releases from production and use facilities, from contaminated waste disposal sites and
wastewater, and from the burning of polyvinyl and vinyl copolymers. 1,2-DCE contaminates
groundwater supplies by leaching from waste disposal sites. Therefore, human oral, dermal, and
inhalation exposure can occur from drinking and using water, and by breathing vapors from 1,2-
DCE-contaminated supplies and delivery systems.
Tetrachloroethene (PCE)
PCE is a halogenated aliphatic hydrocarbon. It is a colorless liquid with a molecular weight of
165.85 and a vapor pressure of 17.8 mm Hg at 25°C. PCE has a half-life of 47 days in the
atmosphere and 30 to 300 days in surface water and groundwater. PCE is used primarily as an
industrial solvent for a number of applications, and is routinely used in laundry and dry cleaning
operations. Inhalation exposure is the primary concern for workers. The general public can also
be exposed to PCE by inhalation, mainly in areas of concentrated industry and population. Some
of the highest outdoor air levels (up to 58,000 ppt) have been associated with waste disposal
sites. Exposure can also occur through contact with contaminated food and water supplies. An
estimated 7 to 25 percent of the water supply sources in the United States may be contaminated
with PCE.
The main targets of PCE toxicity are the liver and kidneys by both oral and inhalation exposure,
and the central nervous system (CNS) by inhalation exposure. Acute exposure to high
concentrations of the chemical (estimated to be greater than 1500 ppm for a 30-minute exposure)
may be fatal. Chronic exposure causes respiratory tract irritation, headache, nausea,
sleeplessness, abdominal pains, constipation, cirrhosis of the liver, hepatitis, and nephritis in
-------
MAL VERN TCE SVPERFUND SITE
humans; and microscopic changes in renal tubular cells, squamous metaplasia of the nasal
epithelium, necrosis of the liver, and congestion of the lungs in animals.
RfDs for chronic and subchronic oral exposure to PCE are 0.1 mg/kg/day and 0.01 mg/kg/day,
respectively (Buben and Flaherty, 1985; USEPA, 1990; 1991). These values are based on
hepatotoxicity observed in mice given 100 mg PCE/kg body weight for 6 weeks and a NOAEL
of20mg/kg.
Epidemiological studies of dry cleaning and laundry workers have demonstrated excesses in
mortality due to various types of cancer, including liver cancer, but the data are regarded as
inconclusive because of various confounding factors. The tenuous finding of an excess of liver
tumors in humans is strengthened by the results of carcinogenicity bioassays in which PCE,
administered either orally or by inhalation, induced hepatocellular tumors in mice. PCE was
negative for tumor initiation in a dermal study and for tumor induction in a pulmonary tumor
assay.
Based on the sufficient evidence from oral and inhalation studies for carcinogenicity in animals
and no or inadequate evidence for carcinogenicity to humans, PCE is placed in EPA's weight-of-
evidence Group B2 (probable human carcinogen). For oral exposure, the slope factor is 5.1 x 10'
2 (mg/kg/day)"1; the unit risk is 1.5 x 10"6 (mg/L)'1. For inhalation exposure, the slope factor was
calculated as 2.03 x 10'3 from the unit risk of 5.2 x 10'7 (mg/m3)'1.
Trichloroethene (TCE)
TCE is a colorless, stable liquid with a chloroform like odor. It has a molecular weight of 131.5,
a vapor pressure of 60mm Hg at 20°C, and a solubility of 1,100 mg/f at 25°C. TCE is considered
slightly soluble in water and is miscible with common organic solvents. TCE is used as a metal
degreaser, as an extraction solvent for oils, fats, and waxes, for solvent dyeing, in dry cleaning,
and for cleaning and drying electronic parts.
Inhalation exposure is the most likely route for human contact with TCE. Systemic health
effects have generally been reported only when people are exposed to TCE levels above the odor
threshold. There are a few case reports of humans exhibiting kidney and liver damage following
exposure to very large amounts of TCE.
There is no reliable information concerning the adverse systemic effects of chronic exposure to
levels of TCE below the threshold limit value of 50 ppm. Neurological effects reported in
workers exposed for less than 15 years to relatively high mean TCE levels (167 ppm) include
vertigo, fatigue, headache, and short-term memory loss. The number of symptoms increased
with cumulative exposure time.
EPA's IRIS database currently does not list a chronic oral or inhalation RfD for TCE. The
chronic systemic toxicity of TCE is currently under review by the RfD Workgroup. Pending this
review, a provisional chronic oral RfD of 6E-3 mg/kg-day was issued by ECAO (now NCEA) in
1992, based on the subchronic mouse study by Tucker, et al (1982). The critical effect seen in
this study was liver toxicity following oral administration.
Animal studies have shown increases in cancers of various types following inhalation or oral
AR30286
-------
MAL VERN TCE SUPERFUND SITE
exposure to TCE. These cancer types include cancer of the liver and forestomach in mice, and
cancer of the kidney and testes in rats. It is believed that tumor production by TCE is the result
of metabolites of TCE. There are differences between high- and low-dose metabolism of TCE,
as well as differences between species' susceptibility to cancer. Given that enormous worker
populations have been exposed to TCE, and that only a small number of persons have
experienced chronic effects, it is possible that TCE is not metabolized to the active carcinogen
level in humans at low environmental doses. The mechanisms of carcinogenicity are not known.
EPA has classified TCE as a Class B2 (adequate evidence in animals but insufficient evidence in
humans) carcinogen.
Mutagenesis studies have suggested that TCE is only very weakly genotoxic following metabolic
activation. The Health Assessment Document concludes that there is insufficient evidence to
prove that TCE is mutagenic.
1,1,2-Trichloroethane (1,1,2-TCA)
1,1,2-TCA is a colorless, sweet-smelling liquid that does not burn easily and boils at a higher
temperature than water. It is used mostly where 1,1-DCE (vinylidene chloride) is made. 1,1,2-
Trichloroethane is used as a solvent. 1,1,2-TCA can enter the body when a person inhales air
containing the compound, or when a person drinks water containing this compound. It can also
enter the body through the skin. After it enters the body, it is carried by the blood to organs and
tissues such as the liver, kidney, brain, heart, spleen, and adipose (fat) tissue. Experiments in
which animals were given 1,1,2-TCA by mouth have shown that most of the compound leaves
the body unchanged in the breath and as other metabolites in the urine in approximately one day.
Very little 1,1,2-TCA stays in the body for more than two days.
1,1,2-TCA can cause temporary stinging and burning pain on the skin. There is no other
information on the health effects of 1,1,2-TCA in humans. Short-term exposure to high levels in
the air or high doses given by mouth or applied to the skin has caused death in animals. Long-
term exposure of animals to high doses given by mouth has also shortened the lifespan.
Breathing high levels in air can affect the nervous system and cause sleepiness. 1,1,2-TCA may
also affect the liver, kidney, and digestive tract, produce skin irritation, and affect the immune
system. Mice, but not rats, that were given high doses of 1,1,2-TCA by mouth for most of their
life developed liver cancer, but we do not know whether humans exposed to this chemical would
develop cancer (ATSDR, 1989b). The U.S. EPA has classified 1,1,2-TCA as a group, possible
human carcinogen (limited evidence of carcinogenicity in animals and inadequate or lack of
human data).
In wastewater treatment plants that receive refractory volatile compounds, such as 1,1,2-TCA,
from industrial discharges or other sources, stripping will be an important mechanism for
transferring the chemical from the water into the air. 1,1,2- TCA will not adsorb appreciably to
soil, sediment, and suspended solids in the water column and would be expected to readily leach
into the subsurface soil and ground water. The bioconcentration factors for 1,1,2- TCA are low;
therefore, it would not be expected to bioconcentrate in fish to any great extent (ATSDR, 1989b).
Lead
Lead is a commonly used, naturally occurring metal which is ubiquitous in the environment.
-------
MAL yERN TCE SUPERFUND SITE
Lead is found in construction materials, leaded gasoline, radiation protection gear, paint,
ceramics, plastics, and ammunition. Lead is well absorbed from the respiratory tract, including
the nasal passages. Absorption from the gastrointestinal tract is less rapid and complete than
from the respiratory tract. Dermal absorption is a much less significant route of exposure than
inhalation or ingestion. Absorbed lead is distributed to the soft tissues of the body with the
greatest distribution to the kidneys and the liver. Lead is eventually transferred to the skeleton
where 90% of the body's long-term burden is stored. The portion of lead that is not absorbed is
excreted in the feces. Most of the absorbed lead is excreted in the urine or through biliary
clearance into the gastrointestinal tract (ATSDR, 1988)
Lead intoxication in humans can occur by ingestion and inhalation of dust or fumes. Symptoms
of lead intoxication include anorexia, malaise, headaches and intestinal spasms. The
neuromuscular disease, lead palsy, is a result of advanced subacute poisoning (lead blood levels
of 70 //g/dL and less), and is characterized by muscle weakness leading to paralysis. Lead
encephalopathy is the term used for the central nervous system manifestation which is commonly
seen in children when lead blood levels reach 90 ^g/dL. Symptoms include clumsiness,
dizziness, delirium, convulsions and coma. The mortality rate is 25% when the brain is involved,
with survivors suffering long-term neurological problems (ATSDR, 1988; HSDB, 1988; IRIS,
1994; USDHHS, 1991).
Chronic low level lead exposure (lead blood levels of 30-50 //g/dL) is associated with learning
disabilities. Lead toxicity is defined by the Centers for Disease Control as a blood level of 25
/ug/dL or greater in a child. Damage at lower levels has been reported and the blood level will be
revised to approximately 10-15 /ug/dL. Kidney damage occurs after prolonged exposure, and is
apparently reversible. In epidemiological studies, lead intoxication is also associated with
increased blood pressure which is symptomatic of kidney damage. Lead exposure is associated
with reproductive effects such as miscarriages and temporary sterility. Lead readily crosses the
placenta. Occupational exposure to airborne lead is associated with an increased incidence of
total malignant neoplasms, cancers of the digestive tract and cancers of the respiratory tract. An
increased incidence in kidney cancer was seen in lead smelter workers exposed by inhalation and
in various animal species exposed by ingestion at levels of 500 ppm and above. The USEPA has
classified lead as a group B2 carcinogen based on animal studies (probable human carcinogen
with inadequate or no evidence in humans) (ATSDR, 1988; HSDB, 1988; IRIS, 1994;
USDHHS, 1991).
The mobility of lead in soil is dependent on the chemical properties of the soil. Lead can react
with sulfates, carbonates and phosphates or combine with clays and organic matter which limits
the further migration of lead through the soil matrix. Lead in surface waters is usually present as
suspended solids. Atmospheric lead is removed by dry deposition and rainout. Lead does not
significantly bioaccumulate in fish. Lead localizes in fish skin which serves to reduce human
exposures by fish consumption. Lead is toxic to wildlife, particularly water fowl, through their
consumption of lead shot. Tetraethyl lead is biodegradable, but inorganic lead concentrations
above 5 /ug/L can be toxic to microorganisms. As water hardness increases, the acute toxicity of
lead to freshwater aquatic species decreases (ATSDR, 1988; HSDB, 1988; IRIS, 1994;
USDHHS, 1991).
-------
MAL yERN TCE SUPERFUND SITE
APPENDIX B- FIGURES
-------
75-33
75'32'
TTTJT- H"»* -Ip '/.—rr
' -. • '-.vlW •. ^ ••
•^•"T' "V-^i- '
•.•-.^\ la/?'-1
:-\^^^r^
;TV,<--\^I
fM-2531;V X/.
5f.-- -MM^ / ^
r ; j^^^r^MV-*rf
i&~ '• \~~^^ \ ^^*
Rase from u.S Geotogicai Survey Maivem 1 1A 000. 1983
Flquf« 1. location o* the Malvem TCE Site and selected wells. Chester County. Pennsvlv.-ioia
-------
CO
CD
ro
cx>
WFIL LOCATION AND
OWM IDENTIFICATION NUMBER
0 500 1.000 FEET
I I—^ *
0 100 200 300 METERS
TRANSCONTINENTAL
GASPIPEtJNE
O
OW-«7
I ocation of dome site weNs near the Malvem TCE Site. Chester County. Pennsylvania
FIGURE 2
-------
10 MAIt !')'(/
four
-------
75°35'
75°34(
7S°33'
40°04'
40°03'
Base from U.S. Geological Survey Malvem 1:24,000.1983
Generalized ground-water-flow directions In the vicinity ot the Malvem TCE Site. Chester County, Pennsylvania.
-------
is=4r«l Is&gy
MOtfR:
i. coNcrwrnAricws *m in vg/^g
t. COMPOUNDS vNOfauMD men i>
l/S»PA SSt's on I'A fCl ? SIKIS'J
fO> SOUS.
LfGfNO
IBO
,'. FIGURES
\ DISTRIBUTIONS* OF VOCS
\ , -,;&\ IN SURFACE SOILS
\ /- V MAIN PLANT AREA-1996
ire
-------
i. conctf/raATioNS APC in
i. COMPOUNDS UNOfOLINlO tXCffO
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fOR SOILS.
LEGCNO
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CAS P(Pfl«f
180
FIGURE O
DISTRIBUTION OF SVOCS
IN SURFACE SOILS
MAIN PLANT AREA-1996
MALVERN TCE
-------
m UP.
\ • •'
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SOIL BORING LOCATIONS
MAIN PLANT AREA-1996
rcc
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MONITOR WELL LOCATIONS Sff£
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MAiVfRN TC€
ro
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f. COMTOUWIS uMofn."vro r.xcirn
usi ''A MCI '» rcw WOUWMVAI i n
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FIGURE 9
DISTRIBUTION OF VOCS
AND SVOCS IN
GROUNDWATER
MAIN PLANT AREA-1996
UALVfRN IC€
-------
no-"' «CM I'
> OC-F) »»«UIO MOC'OCC" »M
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VOC 0»*te«A«A;«n XV>^\«\ M»p
POTENTIOMETRIC SURFACE MAP ._
3/26/96
MAIN PLANT AREA
UAjVltlH ICI
-------
i-,l,ttlt ,'H i lyni"' I* I I'l'lr*
NO'fS: ,
I. fXKNT Of UnjNDCO A/JFA IS
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ssi's on TA Acr ?
sons.
-•••:• ' ^< *# -'-'-I
DISTRIBUTION OP VOCS
IN SURFACE SOILS
FORMER DISPOSAL AREA/
MOUNDED AREA-1996
-------
\
i. (xifNt or MOUNOTO *WA is
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FIGURE -12
DISTRIBUTION OP 8VOCS
IN SURFACE SOILS
FORMER DISPOSAL AREA/
MOUNDED AREA-1096
c
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i IHIW n
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^ ,P,w ISOPLETH CONCENTRATION
«'i7;--^'\ MAP OF TOTAL VOCS FOR
DOMESTIC WELLS AND
FORMER DISPOSAL AREA-1996 E
MAI Vt UN I Lf
-------
i .>« > '!*:«»
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o
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SCALE I'- 60
FIGURED
GEOPHYSICAL SURVEY GRID AND
SOIL BORING LOCATIONS
POTENTIAL DISPOSAL AREA-1996
UALVERN TCE
-------
MAL VERN TCE SUPERFUND SITE
APPENDIX C- TABLES
flR30288
-------
Malvam TCE Sit*
Maximum Concentrations in Surtaca Sod
Main Plant Araa-1996
CX^A^Ir*
CotwtnindM
MttUIMI
N-^WS-^
OttMM4t
INORGANICS (MC/KO
ML'MMJM
AJISENIC
AJUUM
lOtYUJUM
lADMfUM
IALCOM
rHXOMRjV*
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IOITEI
•ON
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rtACNESOM
(ANCANESB
(BtCUBY
flOZl
OT ASSAM
EUMUM
a.vn
OOO/M
ITiALUUM
'ANADIUM
INC
20009
*t
140
32
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2040
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VOLATIU OIGAMKS (UCVKO
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• iinnuad »»!«•
3 • Sifflpl* dilund for jrul
-------
Malvem TCE Sit*
Maximum Concentrations in Subsurfac* Soil
Main Plant Area • 1996
Dtttctod Aiuljrt*
MUUIIUI
Coaccatntloa
Itfeaticwof
MttiMMT
vOOCmifMlMI
Numb«raa
MPA4/JMI
MTAS/404T
MFA7/40-0
MFA4V10-U
MTA10/4»-<7
MPAW/45-*7
MPA5/404Z
MPA«/»2r
MPA«/10>U
MPA7/4M7
MTA2/90-S
MPA4/904S
40 0*40
I4o<40
MnrUNi
CNZD(B)fLUORANTHENI
IENZO(CH)raiYUNB
CNZOtiqaUOtANTHENI .
ItSC-ETHYUaXYUmTHAlATS
mm BENZYL FHTHAUTt
XRYSENB
X-N-BUTYt PHTHALATR
HBENZOFUKAN
lUOftANTHENB
1UOUNI
NDENO(li*CO)PYR£NE
MFHTHAUNI
•ENTACHLOHOPHENCX
•HENANTHRCNE
•HENOt
>YR£NB
19001
2100 f
210|
4M|
MOf
«»|
220(
«0f
UOOOBO
JlOf
400 f
4401
J»l
1400)
630)
2SOI
4100 f
531
000 1
621
1300f
MPA4/IO-U
MPA«/tO>U
MPA4/10»U
MPA4/tO-U
MTA«/10>U
MPA*/10*U
MFAi/tO-U
MPA4/UVU
MPA«/10>U
MPA6/10»U
MPA4/10-U
MPA3/20-Z2D
MFA4/IOU
MPA«/10»U
MPA4/UXU
MFA4/10-U
MPA«/10>U
MPA5/4O42
MPA6/KVU
MPAIO/30-J2
MPA4/10-I2
10140
Iof40
Iof40
2of40
2 of 40
2 Of 40
lof40
2 of 40
24 of 40
3 of 40
2 of 40
19 of 40
Iof40
2 of 40
2 of 40
Iof40
3of40
I of 40
Sof40
lo(40
2o<40
flR302883
-------
Table 2 continued
Maiv«m TCt Site
Maximum Conctntrations in Subsurfac* Soil
Main Plant Area-1996
D«t«cttd Aaalytr
Mui«iu»
(.ofuiouuim
Loutiaaaf
MUUBO*
CoMtnmtitM
Nu«bOTo
27TODD
24000 D
420000 O .
uooooo
MPA«/tO-l2
MPA5/4H7
MfA»/IOO-ia
MTA«/10»I2
MFA2/JO.J2
MPA4/10-U
MPA4/10-U
MFAS/V-SD
MTAf/IOO-KB
V4fA»n00.102
MTM/10-U
MPA2/«M>
MPA4/I0-U
MTA2/90.A
MTA4/IO-U
MTA4/10-U
MPAC/»2T
MFA4/UVU
»0/40
lo<40
So<«)
)of40
2 o/40
9o<40
13o<40
3o«0
20*40
32 at 40
lot 40
3 of 40
4of40
40 o<40
12*40
rKITIS»
1 • no* dMKMd t^ftantttUy akowt Mtfta
• •ttSUMd vvlu^
) • Sttipte diluMd far MMiyw
AR3028BI4
-------
Table 3
Malvem i CE Site
Monitor Wefl Sampling Organic Analytical Results
Main Plant Area • 1996
STATION K>
SAMPLE DATE
USEPA
MCU
cc-02
vtnt
CC-03
cc-oe
tOHt
COOT
CC-1J
CC-13D
wane
CC-19
8/2/M
CC-20
CC-21
ma*
CO22 COJO
S/OT* ami*
SEMVOLATILE OROAMCS (UCM.)
1.2-OtCHlOROBENZENE
BIS(2-€THYLHEXVIJPMTMAUTE
Ot N-BUTYL PMTHALATE
PHENANTHRENE
VOLATUE OROAMC8 (UOM.)
.1,17-TETHACWLOOOETHANE
.1.1-TWCMLOflOETHANE
l.1>TRICHLOnOETHANE
l.l-OICHLOnOETHANE
1,1-OICHLOnOETHENE
I ^.4-TRICHLOnOBENZENE
^MOCOROETHANE
,4-DICHLOflOBUTANE
KNZENE
MRBONOISULFIOE
MIWON TETRACHLORIOE
^COROETHANE
X.OROFORM
»S-1,2-OICHLOnOETHENE
MCTHVLENE CHLORIDE
ETRACHLOROETHENE
rOLUENE
mANS-1.2-O1CHLOROETHENE
rmCHLOnOETHENE
rntCHLOIN)R.UOROMETHANE
/INVLCHLORIOE
900
6
NA
NA
NA
200
NA
5
NA
7
70
000
$
NL
5
NL
5
NA
100
70
5
5
1000
100
s
NL
2
3J
2J
a.s
2J
29.2
2.4
1180
2J
6.0
IB
X^tolM:
prtmwy USEPA Md)») i
- Moondwy USEPA MCX(«) MandMto
• USEPA acton tovri
\ - Pwanwtorlt tatadM '•• kiUSEPA MCt(«) Mndw*
.-pMnwtor to not teM ki USEPA MCL(f) MMdwdt
5 - pMnMlvr (Mvdid h WwA
C i-«
o
Mhw •XCM
-------
Table 4
»
x>
3D
o:
c:
c
oc
c:
MMFUMIf MCU MM MM) MM KM* MM MM
MM IOIM. BM»OH>1» IOIM. MMMV** IOIM MIBOIM
WUIMUM WBMM M« • mt • MM»t
IMIMUMf • M«
IMilMC" - • M • • • • »C
• NniuM 4 . . . . fit
JMUMUM M* M»C
•"*•* M» • - • • _ •__
MMMMM Ml MM. . .ft M • MM*«
ONCWH 1-1 • • • ••
•Ml MB • • . M« -
1IIMU* M • • - • 1C •
VMM MM • • - • MC
MJOUM M «*M MMI MM MM MMC MM
IIHUUt 1 • • • M«
me MM* Ma • M MWG
fim~* tOt »« MC» M MMHMi
U . I^HMB • MM •.•••• UM W> MQM MjMiMl
:SEZ!L
'
i
>
>
>
>
>
M.! M.I tiii M.! tf ^i? tut tij ttt MM* • a* "" *t» ^u ^^ ^
• IOIM MMOtM. 10IM MMMM* IOf*l MMMM» £2. gMM^M loZ MM^M. wSH MMO^I. iSTU «.*?MO WlT M*«*O
.!.''"' **** • • • M» . »••• M»J«
*• • • M» Mff t»J *J
..';;;•••*•••»• »»*
MM* MM* IMM IMM MM* tVM MM* HIM I** ' ' ^»* ***
* ™ "*' ••»••••• IMM IMM IM* I MM MM* *MMf IM»J MMJ
IMM IMMI MM MM MM MM IMM IMM IMM* MMM IIM FM*! IMM* MOOOUi Hm MNB
M» • • • M W M M . . riMMMf-
M* M IK M M - - il i, . . M . • IM »»
'
-------
Table 5
Comparison * preWlralkin Dome** W«U Analytical Data
August 1995 and June 1996
|>AMm NAME
jjAMITE UATC
1. 1. 1 TWO ILUMOC THANE
. U-1 NMTHUMCOCTHANE
,1 MCIILUHUETHANE
.lUKMUWUETHENE
,1 UBMUMtt-KMUNCUIIIUI'ANE
M»OU-ONl>tTHANE
MJIANUNE
HEKANUNE
IACE1UNE
AMUN OMN.HK
HUWUtONM
IS- I.2>UM. IILUNOCTIiCNC
p»4tl H VUNE CHUNU1K
•/»/« 4/25/m
ULUENE
MANS- 1.2 UK. HUMtUfcTHtNfi
KK.IIUJKLC11U-NC
MV-UkStO
«/»/»S
•/M/M t/k/M
.1.1 1KKIILOMOETHANE
M.2
.1 UMIU-tHtltTHANt
,2 UUHCUMlVl-CHUMttirMUI'ANC
tUTANUNE
HEIANUNE
IACE10NE
ANM1N INSULFUM)
IIIUKIIHIMM
IV l.l-WCI ILUKUCTHtNC
IMl fl irttNt CHLOHICC
11 KACMLUNUCTHENf
CXUtNE
HANS UlMCItLUKUtlHtNE
UK »IH.H«.»lOO»UJMlTHANE
Vlfc'Nl(IOTAL)
-------
Table 6
TCE-Related Compounds for Soil Gas Samples
EPA Method Modified 8240
1,2-Dichlorethane
1,1-Dichlorethane
trans* 1,2-Dichloroethene
cis-1 ^•Dichloroethene-
1,1-Dichlofoethene
Tetrachloroethene
l.U-Trichloroethaae
TrichloiDetheoe
PHUPAWortfrortlOSM IVRDt l\TM«VT«h2.1. WM
AR302888
-------
Table 7
Chemical! of Potential Concern for Human Health Evaluation
tnftVQfft fCC
Soil
Surface Soil
UST Area PDA excavated Area
Bn(2-«thyi haiyitenthalate Aluminum
Arsantc Arsenic
Beryllium BeryttMm
iron Cadmium
Manganese Chromium
iron
Theaium
SC of OlattUaiton Buikttne; Area South of Oarage
Arsenic None
BeryNium
Chromium PDA Mounded Area
Iron • Benxo(a)oyiene
Manganese ' Aluminum
Thallium BeryNium
Cedmum
AST ATM iron
Benio(bM«uoranmene Mengeneee
Banzo(a)pyrane Tnafcun*
Aluminum
Beryttium
Iron
Manganese
Subeurface Soil
UST Area
Tetraenjoroethena
Arserwe
Iron
Manganese
SB of Oieuuetton BuMdtng
Areanc
iron
Msnganaia
ASTAfee
Iron
Mangeneae
•OA Mounded Area
i .2-Ocrnofoethena <»«*>.
Anenc
iron
Minojneae
Grounowater (Offafte Residential Walla)
Current Scenario
DW-07
CntOfOfOi^l
OW^ataV
DW-tf
t.i-0iento(oevwne
rHrtureScenerte
CMorofontk
TttraMfttofOeHhsine
iJ^TftthtofMtfaana
OW44T
t
Tatfaohioioaihana
TricNorOfMhMW
OW46*
Tntt*>n#y*m
Groundwatar (Industrial • monitoring wralls)*
Former (Xtpoaal Aree Mam Plant Area
'• . U^J**1^0^*^
TetracMoraemane
I.T.I *Tncnioroatrtani
TneMoroetnane
Vinyl CMonde
\*m*^*»9 tVllSMrfHMHJBJ
1.1-Okhtoroemene
'
oa- 1 ^-Oicnloroetnene
Tatracnioroetnene
i , 1 .2.2-Tetrachioroatnane
1.1.2-TricNoroemene
Tnentoroemene
Vinyl CMonde
Nepnmaiene
Antvnofiy
Arsenc
Bervlhum
Ceummm
ChromHjm
iron
Nickel
Thafcum
vaneoxim
lrt»n«m« COPCSUM.XLS .
worksheet: COPCLIST
/1R302689
-------
• — Tible S ' 1 Of 3 1
Toxtelty Information
M»»v»m rce SH»
Chemical Nam*
Chronic
Oral MD Sourc*
(m«flig-
TdrachkHoelhena
Muene
l.2.4-TricMo(Ob*nien*
.I.l-Trichloiuelliene
1.1.2-Tnchtoroelhana
liKttoroetnon*
nchloroliuOfOrnelliBne
1 . 2. 4 • T rimflthyftwni ene
Vinyl chtoiid*
Xylene nurture
o Xytona
m Xylene
p Xylan*
3006 03 E
6 OOE 01 1
1 OOE 01 1
7 OOE 04 1
2006-02 1
4 OOE-OI E
1 OOE-02 1
MA
I OOE-02 E
3 OOE-02 E
9 OOE 03 1
9 OOE -03 H
1 OOE-02 H
2 OOE-02 1
3 OOE 04 1
1 OOE-OI 1
6 OOE 02 1
SOOE03 H
300E02 1
NA
1 OOE-02 1
2 OOE-OI 1
t OOE 02 1
3SOE-02 E
400C03 1
6 OOE 03 E
3 OOE 01 1
5 OOE-02 E
NA
2 OOE .00 1
200E»00 H
200E*00 H
NA
Uncertainty/
IwooWywiQ
Factor*
• '
3000/
3000/1
100/1
1000/1
1000/1
IOOO/I
10000/
IOOO/I
IOOW
3000/
IOOO/I
10000/1
IOOO/I
100/1
IOOO/
3000/
IOOO/I
IOOO/I
IOOO/I
1000/1
IOOO/I
100/1
IOO/
too/
Stibehronk
OrdfMD Seurc4
(mCA«r
AR30209C
17/51/98
If VI
-------
Chemical Nam*
Dftentoluran
Ji n buttfph»vjlal*
1,? DKNoroberuano
1,4 OcMofotMtuon*
>(2 e*y«ieiivQad(Ml*
>emyjphlhelele
Methyl phmalata
Fluocanlhene
Fluorene
Ind.noO.Z.acdJpVMHHi
2 Memytnafirtmatone
•Melhylpheool
« Mrthylpheiiol
4aphlhalane
'henartfhtene
'yiena
Chronic
Oral RIO Sourca
(moAfday)
400603 E
IOOEOI
900E-02
200E-01
600E01
SOOE-OI
IOOE»OI H 4
400E-02
400E-02
MA
NA
5 Out 02 1
SOOE03 H
400E-02 PI
NA
300E-Q2 1
UntwtaMy?
•ja ., ^| /_ _
mpaiiymy
Factor*
1000/1
1000/1
300/1
1000/1
10W
3000/1
3000/1
1000/1
IOOW
3000/1
OratMO Sourca
mg*»-daw
NA
lOOEtOO H
NA
NA
NA
8.00E*00 H
tOK*Ot H94
4.00E-OI H
4.00E-OI - H
NA
NA
SOOE-OI H
S.006-O3 H
NA
NA
300E-OI M
T"*1* 8 2 of 3
Toxtetty Infomurtkm
ttitom TCC SH»
Ctironle "
MMlRfD Soorc*
(m^^nl
. NA
NA
400E-02 A
229E-01 1
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA . .
UncartaMy/
^kk^iMteaVa^
•oowying
Factor*
1000
tooroa/itfc Anutytf* . i . .
Aluminum
i Aviioiiy
Arsenic
arum
tritium
;admium (carcioogetucity)
Cadmum (load)
Cadmium (water)
:«tdum
^Hocmum (hemjvalenO
Chromium (trivalent)
CobM
Cyanide
lion
lead
Magnesium
Me.cury
Nictiel
Potassium
Selenium
Stoat
Ihallrum(i) chloride
Vanadium
?mc
IOOE*00 E
400E-04 1
30DE-04 1
700E-02 1
S.OOE-03 1
NA
100603 1
S 006 -04 1
NA
S 006 43 1
1006*00 1
• OOE-02 E
400E-02 E
200E02 1
300E-OI E
NA
NA
240E-07 1
300E-04 H94
SOOEO3 1
200E02 1
NA
S ODE 03 1
SOOE03 1
NA
B DOE OS 1
700E-03 H
300COI 1
1000/1
3/1
3/1
100/1
10/1
10/1
500/1
100/10
100/1
IOOW
3WI
100/3
3/1
3/1
300/1
100
3/1
NA
400E-04 H
3006-04 H
7.00E-O2 H
S.OPE-03 H
NA
NA
NA
NA
200E-02 H
1 0OE«00 H
NA
400E-02 H
200E-02 H
NA
NA
NA
NA
3.00E-04 H94
NA
200E02 H
NA
S OOE-03 . H
500E03 H
NA
8 ODE -04 H
7QOE-03 H
300E-OI H
NA
NA
NA
143E-04 • A
NA
NA
NA
S71E-OS W
NA
.NA
5.71E-07 W
NA
NA
NA
NA
NA
NA
M3E4S 1
• 57E-09 I
NA
NA
NA
NA
NA
NA
NA
NA
NA
1000/1
3WI
S*IIV€TWWI|C
MtalRtD sourct
(maykf^toy)
NA
NA
400E-OI A
714E-OI H
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA .
NA
NA
NA
NA
NA
NA
NA
NA
NA .
NA
NA
NA
NA
NA
NA
NA
NA
BS7E-OS H
NA
NA
NA
NA
NA
NA
NA
NA
NA'
WalajM*of-
EvManca Sourci
C1a»t
0
O
D
C 1
c
D
0
0
0
B2
NA
C
C
D
0
D
Oral
CSF Source
(moAomay)'
NA
NA
NA
240E-02 H
I20E-03 1
NA
NA
NA
NA
730E-01 U
NA
NA
NA
NA
NA
NA
Mwl
CSF Source
(moAorday)1
NA
NA
NA
NA
NA
NA
NA
NA
NA
8 10E-01 E
NA
NA
NA
NA
NA
NA
NA
D DW
A 1
D DW
62 . 1
61 1
61 1
61 1
NA
A 1
0 OW
NA
0 1
0 1
NA
62 1
NA
D 1
0 1
O OW
O OW
NA
O 1
D 1
NA
0 1
O OW
0 1
NA
NA
1SOE*OO 1
NA
4.30E«OO 1
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
1 SIE-tOI 1
NA
fl.40E*00 1
6306*00 1
NA
NA
NA
« 206*01 1
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
A HciMi EMKls A»eswn*ni Summary Tab* ?. (HEASM AMinaM MHhods
OW Dnr*«g Wdei Regulations md Menti »
-------
.....
table 8 3 o£ 3
tdxlclly Information
Mtfcwm TOE Stt*
CnvffiKM NMVM
Chronic
Of •( MD SO«HC*
(m^f-dn)
Uncwlclnry/
WoolfylfVQ
F*ClW(
Subchronk
Ord MD Sourc*
(m9«9^toy)
Chronle
IntiMRfD Sourc*
(moAgMMy)
Unewtalnly/
•^bhjMflwki^ii
i^vonyiriy
F*eto»
Subchronk
MMlRfO Sowc*
(mo/hoxtoy)
Wctgnlol-
EvMcne* Sourc*
ClM«
Orrt
C3F Sowci
(moAo-d^C
Miri
CSF Source
(mo/ko^ay) '
E EPA • NCEA pumuorwl »lu». SupMftjnd Twftraetf Support Coniw
M HMM) EltocH AuMJnMrt Summer T«Mn (HEAST). FVtWS
M»4 M«««hCH*d» Aswnmeni Summary Tibl>i(HEAST). FVIW4
I • InltQrftlttf Hi ill InfoflMhon Sytfoifi (lAlS). AC
. riA • Not cvUitil* 01 not «|)p>c«M»
PI • PiovtMmM MO M*mo Horn Joan DolwtMM ID O*MM SWwn EPA O»»nn V.
O PioxMnal Gwdanc* fc» OuanMakv* IWi AisMSffMrt ol Pdycyctc Amnwkc ><
i. ECAO. OMEA. EPAWWW 9*OW. JUy IM1
CO
CT>
ro
f.X)
V.D
Nwumc •••'VIOX «IS
12/31/96
If 1
-------
Table 9
Summary of Maximum Currant Groundwatar Risks to Rasldantial Wall Usars
Malvtm TCE
Wall
Wall DW-02
Wall DW-07
Wall DW-046
Wall OW-066
Pathway
Inhalation
Ingestion
Dermal*
Total
Inhalation
Ingestion
Dermal*
Total
Inhalation
Ingestion
Dermal*
Total
Inhalation
Ingestion
Dermal*
Total
Noncancer
Child Adult
0.0077 0.0033
0.0023
0.0100 0.0033
0.0064 0.0027
0.0019
0.0083 0.0027
0.0078 . 0.0033
0.0003
0.0081 0.0033
00036. 0.0015.
0.0001
0.0037 0.0015
Cancer
Age-adjusted
2.9E-06
1.1E-07
1.2E-08
3.0E-06
2.4E-06
9.1E-08
1.0E-08
2.5E-06
6.5E-06
9.9E-06
1.3E-07
1.6E-05
2.9E-06
4.5E-06
6.1E-08
7.5E-06
TIM adult pttfnwy is
contributor.
Summary of Maximum Future Groundwatar Risks to Residential Well Users
Mitvtm TCE
Well
Well DW-036
Well DW-041
Well DW-058
Pathway
inhalation
Ingestion
Dermal'
Total
Inhalation
Ingestion
Dermal-
Total
Inhalation
Ingestion
Dermal*
Total
Noneancer
Child Adult
0.86 0.37
0.40
13 0.37
0.021 0.0083
2.2 0-95
1.1
3.3 0.98
0.95 0.41
0.43
1.4 0.4t
Cancer
Age-adjusted
55E-05
8.3E-05
5.3E-06
1.4E-04
1.5E-04
2.1E-O4
1.5E-05
3.7E-04
1.1 EOS
1.6E-05
3.7E-06
3.1E-05
* D«rm« •xpocur* ator 0M cftiW orty. Th« aduM pMrnwy • coraidmo ID M • mnor oontnbuer.
filename:SRISKS.XLS
worksheet:dw-curr
AR302893
12/26/96
11:28 AM
-------
fSbimr
Summary of flrsfcs by Receptor Md Pathway
Me/vent rce
Media
Q — aim .an
rmfiwvy
Future Onslte Resident
Noncancer
CUM
Adult
Cancer
Age-wlluslwi
TrespasMr
Noncancer
Youth
Adult
Cancer
Youth
Adult
IndutlrUI
Noncftncw
Site Worker
Construction
Worker
Cancer
Site Worker
Construction
Worker
Groundwaier
Former
Disposal
Ar«a
Main
Plant
Area
inhalation
InposUoo
Dermal
ToM
Inhatalton
rngestton
Dermal
ToM
So*
Underground
Storage
Tank*
Araa SE of
Distillation
Building
Above Ground
Storage
Area
FOA
icavated
Area
FOA
Mounded
Area
torMtaton
Ingniion
DwrnaJ
Total
|- J,— tm aii MI
IIVlMBDOTi
Inp^sMon
Owmal
Total
fnhriatton
InQSStion
Dermal
ToM
Inhatollon
Ingeslion
Dermal
ToM
InhaJafcon
Ingeston
Dermal
Total
17
35
97
62
440
930
270
1600
68
IS
NA
22
teo
400
NA
MO
0083
32
0.70
4.0
014
2.3
061 •
3.1
•cOOOOl
19
0.3B
2.3
0034
31
060
4.0
0023
2.1
042
2.5
0030
034
024
O.«1
0.051
025
0.19
0.49
<00001
020
012
0.32
0.012
034
025
0.60
0.0060
023
013
0.36
5 BE 04
1 6E03
12E-04
2.SE-03
1.6E-02
4.7E-O2
32E-03
6.6E-02
18E-08
2.7E05
26E05
S.3E-OS
59E07
26E-05
21E-06
4.SC-05
6.7E-10
1 2E05
19E-05
30C-OS
2.2E-07
29EOS
24E-05
5.3E-O5
87EO9
83E06
7 IE 06
1.5E-OS
NA
NA
NA
NA
NA
NA
0.00077
0044
0022
0.067
0.0013
0032
0017
O.OS1
<00001
0027
0011
0.037
0.00032
0044.
0022
0.066
0.00021
0029
0012
0.041
NA
NA
NA
NA
NA
NA
0.00073
0025
0.018
0.044
0.0013
0.018
0014
0.034
<0.0001
0.015
00068
0.024
0.00030
0025
0019
0.044
0.00020
0017
00097
0.027
NA
' NA
NA
NA
NA
NA
12E 10
72E-07
5.8E-07
1.3C-06
4 IE 09
47E-07
48E07
9.6E-07
006*00
2.-1C-07
ooe*oo
2.1B-07
15E-09
51E-07
55E-07
11E-06
6 IE 11
15E-07
16E-07
9.1E-O7
NA
NA
NA
NA
NA
NA
32E-10
1 1E06
1.3E-06
J.4E-06
1 IE 08
73E-07
1 1E^K
1.6C-O6
00€»00
33C47
OOE»00
3.3E-07
39E-09
60E-07
13E-06
2.1E-08
16E-10
23E-07
37E-07
6.0E-07
NA
54
NA
S.4
NA
140
NA
140
0.021
012
0096
0.24
0036
0089
0.075
0.30
0012
0.073
0047
0.13
0.0087
O.12
0099
0.23
00057
0081
0052
0.14
NA
NA
NA
NA
NA
NA
NA
4 IE 04
NA
4.1E-04
NA
1 1E-02
NA
1.1E-02
0021
12
Oil
1.3
00050
051
0049
0.57
0.010
058
0.039
0.63
NA
NA
NA
0.0059
069
0.070
0.76
7.7E-09
45E06
5 BE 06
1.0E-OS
26E07
29E 06
49E06
8.1E-06
5.7E-IO '
13E06
43E-06
S.6E-06
94E-08
32E06
56E06
8.9E-06
3 BE 09
9 3E 07
1 6E 06
2.6E-06
NA
NA
NA
NA
NA
NA
62E 07
1 BE 06
3.7E-07
2.8E-06
20E-IO
64E 07
1 4E-07
7.7E-07
NA
NA
NA
NA
NA
NA
2 7E-07
13E06
2.7E-07
t.BE-06
CD
ro
CO
NA - Not applicable
Offsite groundwater risks summarized on Table 6-7 lor the current scenario and Table 68 lor Vie Mure scenario.
IZ/7VM
II ?4 >
Mown* SRlSKSUS
totf.ndt •"
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Pathway
Future OnsNe Resident
Noncancer
CMM
AduN
Cancer
Age-
adkisted
Table J.1
Summary of Risks Acroat Pathway*
MenvmrCE
TrestM
Noncancer
Youth
AduH
FDA Area
3roundwaler • FDA
Soil - FDA Excavated
Area
Soil • FDA Mounded
Area
Total FDA Area
62
40
2.5
69
22
0.60
0.36
23
MPA Area
Groundwaler • MPA
Soil - US T Area
Soil • Distillation
Building
Soil • AST Area
Total MPA Area
1600
40'
3.1
23
1600
580
061
049
032
5*0
2 5E 03 .
5.3E-05
1.5E-OS
2.SE-03
NA
0.066
0.041
0.11
66E02
S.3E-OS
48E05
30E-05
6.6E42
NA
0067
0051
003?
0.15
NA
0044
6.027*
0.070
NA
0.044
, 0034
0024
0.10
Cancer
Youth
NA
ME 06
3.1E-07
1.4E-06
AduN
•
Industrial
Noncancer
Site
Worker
Construction
Worker
Cancer
Site Worker
Construction
Worker
NA
2.1^-06
6.0E-07
2.7E-4M
NA
1.3E-OJS
96607
216-07
2.SE-06
NA
24E06
1.8E-08
3.3E-07
4.6E-06
5.4
0.23
0.14
5.7
140
024
020
013
140
NA
NA
076
0.76
4 IE 04
89E06
26E06
4.2E-04
NA
1.3
057
063
2.5
1 1602
10605
8 IE 06
56606
1.1E-02
NA
NA
1B6 06
1.6E-06
NA
2 BE 06
7.7E-07
NA
356-06
The luture onsite residential groundwaler risks are based on monitoring wel data.
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Ittanjme SRISKS KIS
stH>*inan« Sum acioss
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TABLE 12 - SUMMARY OF ALTERNATIVES
Water Supply
WS-G-3a: Public Water Supply
WS-G-3b: Well Head Treatment
Main Plant Area Soils
MPAS-1: No Action
MPA S-2: Institutional Controls
MPA S-3: Capping
MPA S-4: InSitu Soil Vapor Extraction
Main Plant Area Groundwater
MPA-G-1: No Action
MPA-G-2: Institutional Controls
MPA-G-4: Natural Attenuation
MPA-G-5: Groundwater Collection, Treatment & Discharge
MPA-G-6: Groundwater Collection, Treatment of Source Area & Discharge
Former Disposal Area Soils
FDA-S-1: No Action
FDA-S-2: Institutional Controls
FDA-S-3: Capping
FDA-S-4: Excavation, Off-Site Thermal Treatment, Disposal at a Subtitle C Landfill
FDA-S-5: Excavation, ExSitu Volatilization, & Reuse as Backfill
FDA-S-6: Excavation, On-Site Thermal Treatment, and Reuse as Backfill
FDA-S-7: InSitu Soil Vapor Extraction
FDA-S-8: Excavation, Consolidation of Soils at the Main Plant
Former Disposal Area Groundwater
FDA-G-1: No Action
FDA-G-2: Institutional Controls
FDA-G-4: Natural Attenuation
FDA-G-5: Groundwater Collection, Treatment, and Discharge
FDA-G-6: Groundwater Collection, Treatment (Single Well), and Discharge
AR302896
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Table 13
Malvern TCE Site - Identification of ARARs
Water Supply Remedy
Requirement
The water supply provided shall achieve MCLs
The installation of the water line shall avoid,
minimize and mitigate impacts on (loodplains and
wetlands.
Existing Residential wells shall be abandoned
Management of the spent carbon filters shall be in
accordance with the substantive requirements of
hazardous waste regulations.
Type
Chemical
Location
Action
Action
Citation
The Safe Prinking Water Act 42 U.S.C. §§ 300(i>300(j),
and40CFR§!4l
Executive Order No. 11988 and 40 CFR Part 6, Appendix A
(regarding avoidance, minimization, and mitigation of
impacts on floodplains) and Executive Order No. 11990 and
40 CFR Part 6, Appendix A (regarding avoidance,
minimization, and mitigation of wetlands
Pennsylvania Safe Drinking Water Act, 25 Pa Code Section
109.62 and consistent with PADEPs Public Water Supply
Manual, part II. Section 3.3.5.11 and Chester County Health
Department Rules and Regulations Chapter 500.
25 Pa. Code Chapter 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 waste); and C (relating to
pretransport requirements); 25 Pa. Code Chapter 264,
Subparts B-D, I (in the event that hazardous waste is
managed, treated, or stored in tanks), and 40 CFR 268
Subpart C, Section 268.30, and Subpart E (regarding
prohibitions on storage of hazardous waste).
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Table 13
Malvern TCE Site - Identification of ARARs
Main Plant Area Soils Remedy
Fugitive dust emissions generated during remedial
activities will be controlled
Quonset Hut debris shall be decontaminated in accordance
with the Hazardous Debris Rule and properly disposed or
reused.
USTs shall be decontaminated in accordance with the
Hazardous Debris Rule and properly disposed or reused.
The Main Building (including Loading Dock and Chemical
Laboratory) shall be closed in accordance with Federal and '
PA Hazardous Waste Regulations.
Wastewater generated during decontamination activities
shall be properly managed.
Action
Action
Action
Action
Action
Fugitive dust regulations 1 the federally approved State
Implementation Plan (SIP) for the Commonwealth of
Pennsylvania. 25 PA Code §§ 123. 1 - 123.2, and the National
Ambient Air Quality Standards for Paniculate matter 1 40 CFR
§§ 50.6 and PA Code §§ 1 3 1 .2 and 1 3 1 .3
Hazardous Debris Rule 40 CFR 268.45
Hazardous Debris Rule 40 CFR 268.45
25 Pa Code § 265.1 10 through 265. 1 19, 265.442(7);40 C.F.R.§§
264.1 10 through 264.120, 264.178, 270.l4(bXI3)
PA Hazardous Waste Regulation
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TlM«l3
Malvtrn TCE Site Identification of ARARs
Main Plant Area Groundwatcr Remedy
Requirements
Any new wells installed must be drilled in accordance with
Pennsylvania Water Well Drillers regulations.
The treated groundwater effluent shall be reinjecled in accordance
OSWER Directive #9234 1-06.
The installation of the extraction and treatment system shall avoid.
minimize and mitigate impacts to wetlands.
Existing pumping and/or monitoring wells which serve no useful
purpose shall be properly plugged and abandoned.
Air Emissions from Superfund Site shall be controlled.
Air Emissions will also comply Slate and Federal Requirements
Type
Action
Action
Location
Action
To Be Considered •
Action
Citation
25 Pa. Code Chapter 107. These regulations are established pursuant to the
Water Well Drillers License Act, 32 P.S § 645 1 el seq.
"Applicability of Land Disposal Restrictions to RCRA and CERCLA
Groundwaler Treatment Reinjection". OSWER Directive #9234 1-06
Executive Order No. 1 1988 and 40 CFR Part 6. Appendix A {regarding
avoidance, minimization and mitigation of impacts on floodplains) and Executive
Order No. 1 1990 and 40 CFR Part 6, A (regarding avoidance, minimization and
mitigation of impacts on floodplains) and Executive Order No. 1 1 990 and 40
CFR Part 6, Appendix A (regarding avoidance, minimization, and mitigation of
wetlands
PADEP's Public Water Supply Manual. Part II, Section 3 3 5 1 1 and Chester
County Health Department Rules and Regulations Chapter 500. in order to
eliminate the possibility of these wells acting as a conduit for future groundwater
contamination.
OWSER Directive #9355 0-28, Control of Air Emissions from Superfund Air
Strippers at Superfund Ground Water Sites.
40 CFR
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TaM* tJ
Malvf r» TCK Silt Idtmifkaiioa of ARAR>
Main Plant Area Grovitdwalrr Rentdy ,
Management or the spent carbon fillers shall be in accordance with the
substantive requirements of hazardous waste regulations.
Fugitive dust emissions generated during remedial activities will be
controlled in order to comply with federal and state air regulations.
Extraction and Discharge ofgroundwaler shall be in accordance with
the substantive requirements of the Delaware River Basin
Commission
The groundwater shall be restored to MCLs.
Action
Action
Location
Chemcial
25 Pa. Code Chapter 262 Subparts A (relating to hazardous waste determination
and identification numbers). D relating to manifesting requirements Tor olTsite
shipments of spent carbon or other hazardous wastes);
25 Pa Code Chapter 263 (relating lo transporters of hazardous wastes): and wilh
respect to the operations at eh the Site generally, wilh the substantive
requirements of 25 Pa Code Chapter 264, Subparts B-D, 1 (in the event that
hazardous water generated as part of the remedy is managed in containers), 25 Pa.
Code Chapter 264, Subpart J (in the event that hazardous waste is managed in
containers). 25 Pa. Code Chapter 264. Subpart C. Section 268.30 and Subpart F.
(regarding prohibitions on storage of hazardous waste).
Fugitive dust regulations in the federally-approved Slate Implementation Plan
(SIP) for the Commonwealth of Pennsylvania. 25 PA Code j|§ 1 23 1 - 1 23 2 and
(he national Ambient Air Quality Standards for Paniculate Matter 40 Cl R 8$
50.6 and PA Code §§ 131 2 and 131 3
(18 CFR Part 430) are applicable; These regulations establish requirements for
the extraction and discharge of ground water within the Delaware River Basin.
The Safe Drinking Water Act 42 U.S.C. «S 300(0-3000). and 40 OR $ 14 1
3=3
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Fori
Table 13
Malvcrn TCE Silt Identification of ARARs
ner Disposal Area/Mounded Area (FDA/MA) Soils Remedy
Requirements
Type
Citation
Any on-sile landscaping will be in accordance with Federal
Landscaping guidance.
To Be Considered
Office of the Federal Executive: Guidance for Presidential Memorandum on
Environmentally and Economically Beneficial Landscape Practices on
Federal landscaped Grounds, 60 Fed Reg 40837 (August 10, I99S) which is a
"to be considered" (TBC) requirement
RCRA listed constituents are present in the soils, therefore, the remedy
will be implemented consistent with the following substantive
requirements, which are applicable to on-site activities.
Action
Pa. Code §§ 262.11 • 262.13 (relating to prelransport requirements); 25 Pa.
Code 5 262.34 (relating to prelransport requirements); 25 Pa. Code Chapter
263 (relating to transporters of hazardous wastes); and with respect to the
operations at the Site generally, with the substantive requirements f 25 Pa.
Code Chapter 264, Subparts B-D, I (in the event that hazardous waste
generated as part of the remedy).
Sediment and erosion controls and temporary covers will be installed to
protect exposed soil from the effects of weather consistent wilh
PADEP's Bureau of Soil and Water Conservation Erosion and Sediment
Pollution Control Manual.
To Be Considered
PADEP's Bureau of Soil and Water Conservation Erosion and Sediment
Pollution Control Manual
Fugitive dust emissions generated during remedial activities will be
controlled in order to comply wilh federal and slate air regulations.
Action
Fugitive dust regulations in the federally-approved Stale Implementation Plan
(SIP) for the Commonwealth of Pennsylvania. 25 PA Code (j(j 123 I - 123.2
and the National Ambient Air Quality Standards for Paniculate matter in 40
CFR S§ 50.6
-------
Requirements
Installation of additional wells may be necessary and must be in
accordance Water Well Drillers License Act.
The groundwater shall be restored to MCLs.
Table 13
FDA/MA Groindwaler Remedy
ARARs
Type
Action
Chemical
Citation
25 Pa. Code Chapter 107. These regulations are established pursuant !? the
Water well Drillers License Act. 32 PS $ 645. 1 clsca.
The Safe Drinking Water Act 42 U.S.C. $$ 300(0-3000), and 40 CFR $141
-------
TABLE 14
MALVERN TCE SUPERFUND SITE
RESIDENTIAL WELLS TO HOOK UP TO PUBLIC WATER
Well Number i Address
, 3
4
7
20
42
43
33
M
60
66
1
2
5
12
30
31
32
11 Hillbrook Circle
25 Hillbrook Circle
36 Hillbrook Circle
1
232 N. PhoenKville Pike
13 Hillbrook Circle
21 Hillbrook Circle
!
29 Hillbrook Circle
28 Hillbrook Circle
39 Hillbrook Circle
215 N. PhoenBviHe Pik
8 Hillbrook Circle
«
1
4 Hillbrook Circle
26 Hillbrook Circle
365 Conestaga Rd
330ConesicgaRd
405 Conettoga Rd
411ConestogaRd
45 ! 9 Hillbrook Circle
46
47
48
49
51
61
62
63
64
69
7 Hillbrook Circle
5 Hillbrook Circle
1 Hillbrook Circle
2 Hillbrook Circle
10 Hillbrook Circle
38 Hillbrook Circle
388ConestogaRd
386 Conestaga Rd
384 Conestoga Rd
3 Hillbrook Circle
70 1 211 N. Phoennville Pike
71
100
200
6
9
10
13
16
19
23
33
36
41
44
50A
32A
33A
56
57
58A
39A
65
67
409 Conedoga Rd
366 Conestaga Rd
407 Conettoga Rd
32 Hillbrook Circle
33 Hillbrook Circle
256 N. Phoeninrille Pike:
206 N. Phoenaville Pike,
212 N. Phoenaville Pike!
228 N. PnoenRville Pike!
244 N. Phoenirville Pike
15 Hillbrook Circle
17 Hillbrook Circle
19 Hillbrook Circle
23 Hillbrook Circle
6 Hillbrook Circle
27 Hillbrook Circle
30 Hillbrook Circle
31 Hillbrook Circle
34 Hillbrook Circle
35 Hillbrook Circle
37 Hillbrook Circle
248 N. Phoenerville Pike
410 Conestaga Rd
AR302903
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RESPONSIVENESS SUMMARY
FOR THE
PROPOSED REMEDIAL ACTION PLAN
FOR THE
MALVERN TCE SUPERFUND SITE
EAST WHITELAND TOWNSHIP, CHESTER COUNTY, PENNSYLVANIA
Public Comment Period
June 23,1997, through September 2,1997
AR30290I4
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Malvern TCE Superfund Site
Responsiveness Summary
for the
Proposed Remedial Action Plan
TABLE OF CONTENTS
Overview
Background
Part I: Summary of Commentors* Major Issues and Concerns During the Public Meeting
A. Operations at the Site
B. The Preferred Soil Alternatives
C. The Preferred groundwater Alternatives
D. The Preferred Water Supply Alternative
E. Bioremediation
F. Responsibilities of the PRPs
G. The Time Frame for the Remedial Action
H. The Site's Impact on the Surrounding Community
I. The Contamination
Part II: Summary of Commentors' Major Comments and Questions Received in Writing
During the Public Comment Period
A. Comments of North Industrial Chemicals, Inc
B. Comments of East Whiteland Township
C. Comments of Environmental Resources Management (ERM) on behalf of the
Malvem Site Study Group, a PRP group
D. Comments of David De Win on behalf of the Concerned Residents of East
Whiteland Township
E. Comments of Fox, Rothschild, O'Brien & Frankel, LLP and Walter B.
Satterthwaite Associates Inc. on behalf of the Malvem De Minimis PRP Group .
F. Comments of United States Department of Interior
G. Comments of Mr. & Mrs. Charles Kocher
H. Comments of Pennsylvania Environmental Defense Foundation
AR302905
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Responsiveness Summary
Malvern TCE Superfund Site
East Whiteland Township, Chester County, Pennsylvania
This Responsiveness Summary is divided into the following sections:
Overview
The overview summarizes the public's response to remedial(cleanup)
alternatives listed in the Proposed Remedial Action Plan ("Proposed
Plan"). The Proposed Plan outlined various methods of cleanup of the
Malvem TCE Site and discusses EPA's preferred method.
Background
This section provides a brief history of community relations activities
conducted during remedial planning at the Malvern TCE Superfund Site.
1. Summary of Major Comments and Questions Received During the
Public Meeting and EPA Responses
This section documents comments and questions from citizens and
potentially responsible parties during the July 16,1997 Public Meeting at
Great Valley High School in Malvern, PA. These comments and
questions and EPA's responses are categorized by topic.
II. Summary of Major Comments and Questions Received During the
Public Comment Period in Writing and EPA Responses
This section provides a comprehensive response to all significant
comments received in writing by EPA during the Public Comment period.
Overview
The Proposed Plan for the Malvern TCE Site (Site), located in East Whiteland Township,
Chester County, Pennsylvania was issued on June 23, 1997. EPA's public comment period for
the Site was originally scheduled to run from June 23,1997 through July 23,1997. This
AR302906
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comment period was extended until September 2, 1997 in response to several timely requests.
EPA conducted a public meeting on July 16,1997 to present the Proposed Plan to the public. At
this meeting, the public was given an opportunity to ask questions and to comment on the
cleanup alternatives outlined in the Proposed Plan and the results of the Remedial Investigation
(RI) for the Site. The Proposed Plan details EPA's preferred clean-up alternatives to cleanup the
Site contamination, giving consideration to the following nine evaluation criteria:
Threshold Criteria
• Overall protection of human health and the environment
• Compliance with Federal, state, and local environmental and health laws
Balancing Criteria
• Long-term effectiveness and permanence
• Reduction of mobility, toxicity, or volume of contaminants
• Short-term effectiveness
• Ability to implement
• Cost
Modifying Criteria
• State acceptance
• Community acceptance
EPA carefully considered state and community acceptance of the clean-up alternatives
before reaching the final decision regarding the clean-up plan. The Record of Decision (ROD)
details EPA's final clean-up decision.
EPA's selected remedy is outlined below. These alternatives provide the best balance
among the alternatives with respect to the nine evaluation criteria EPA used to evaluate each
alternative.
• Water Supply: To prevent contact with groundwater contamination at residences affected
or potentially affected by the Site, EPA has selected Alternative WS-G-3a, Public
Water Supply.
• Main Plant Area Soils: To prevent direct contact with contaminated soils in the Main
Plant Area and to reduce the potential for continued migration of these contaminants to
the groundwater, EPA has selected Alternative MPA-S-3, Capping.
• Main Plant Area Groundwater: To reduce the migration of contaminated groundwater
from the Main Plant Area, EPA has selected Alternative MPA-G-6, Groundwater
AR302907
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Collection, Treatment of Source Area, and Discharge by Reinjection.
• Former Disposal Area/Mounded Area Soils: To reduce the potential for continued
migration of contaminants in these soils to the groundwater, EPA has selected
Alternative, FDA-S-4, Excavation, Off-Site Thermal Treatment, Disposal at a
Hazardous Waste Facility.
• Former Disposal Area/Mounded Area Groundwater: To reduce concentrations of
contaminants in groundwater to MCLs, EPA has selected FDA-G-4, Natural
Attenuation .
Background
Historically, public concern and involvement with the Malvem TCE Superfund Site has
been moderate. In the early 1980s, residents became familiar with the Site when the
Pennsylvania Department of Environmental Protection (PADEP) discovered soil and
groundwater contamination on the property and groundwater contamination in nearby residential
water wells.
From 1982 through 1992, residents on Phoenixville Pike and in the Hillbrook Circle
development were involved with the Site while Chemclene, the Site's owner and a potentially
responsible party (PRP), periodically tested residential water wells and placed carbon filters on
wells with trichloroethene (TCE) contamination. Some residents only became aware of the Site
and its associated contamination when their wells ran dry and they were required to redrill.
According to residents, EPA's RI and community relations activities have increased the
community's awareness and understanding of the Site.
EPA began considering the Site under the Superfund remedial program in November
1993. EPA first initiated community relations activities in July 1995. During that month EPA
established an information repository at the Chester County Library, issued a fact sheet, and held
a public meeting.
EPA's fact sheet provided a brief history of the Malvern Site, an overview of EPA's
activities at the Site, and a description of the Site contamination. The fact sheet also announced
EPA's first public informational session which was held on July 31, 1995. The purpose of the
information session was to inform residents of the contamination at the Site and the status of
EPA's activities at the Site. The East Whiteland Township Environmental Advisory Board
hosted the meeting and approximately 20 people attended.
In October 1995, EPA issued a second fact sheet which provided background information
AR302908
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on the Site and the status of the groundwater and soil investigations and residential well
sampling.
In February and March 1996, EPA conducted community interviews with residents living
in the Hillbrook Circle and Aston Woods residential developments. These interviews allowed
EPA to speak with residents one-on-one about their concerns and questions regarding the
Malvem Site.
In March 1996, EPA issued another fact sheet. This fact sheet announced approval of the
sampling plan for the Site, discussed the scheduled soil sampling and its potential impact on the
community, announced the preparation of the Community Relations Plan (CRP) for the Malvem
Site, and announced the schedule of residential water sampling.
On April 25,1996, EPA held an information session at the Great Valley High School to
respond to concerns and questions residents had raised during the community interviews. EPA
officials who attended the meeting included: Linda Dietz, Remedial Project Manager; Jennifer
Hubbard, lexicologist; Barbara Rudnick, hydrogeologist; and Carolyn Szumal, Community
Involvement Coordinator. In addition, Ron Sloto, a hydrogeologist with the U.S. Geological
Survey attended. EPA sent postcards to local residents to invite them to the information session.
EPA issued the CRP for the Malvem Site in May 1996. The CRP highlighted issues,
concerns, and interests of the community located near the Site and provided background
information about the Superfund process and the Site. In addition, the CRP listed EPA's
community relations objectives and planned activities intended to encourage public participation
in Site activities.
To announce the availability of and to obtain public input on the Proposed Remedial
Action Plan (Proposed Plan), EPA held a public comment period from June 23, 1997, through
September 2,1997. During the public comment period, EPA issued a fact sheet and held a
public meeting in the Great Valley High School Auditorium on July 16,1997, to provide
residents with information about the Site and the proposed clean-up alternatives. The public
meeting also provided an opportunity for residents to ask questions about or comment on the Site
and EPA's proposed clean-up alternatives. EPA announced the public meeting, the opening of
the public comment period, and the availability of the Proposed Plan in a public notice placed in
the Daily Local News on June 23,1997.
The July 1997 fact sheet highlighted EPA's preferred alternatives to cleanup the
contamination at the Site, announced the availability of the Remedial Investigation/Feasibility
Study (RI/FS) and Proposed Plan in the information repository, provided a brief history of the
Site, invited the public to comment on the documents in the information repository, and
AR302909
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announced the public meeting.
To announce the extension of the public comment period to September 2, 1997, EPA
placed a public notice in the Daily Local News on July 28,1997.
Part I: Summary of Commentors* Major Issues and Concerns During the Public Meeting
This section provides a summary of commentors' major issues and concerns and EPA's
responses to those issues and concerns. "Commentors" may include local homeowners,
businesses, the municipality, and PRPs. The major issues and concerns about the proposed
clean-up alternatives for the Malvern Site received during the public meeting on July 16, 1997,
and during the public comment period, are grouped into the following categories:
A. Operations at the Site
B. The Preferred Soil Alternatives
C. The Preferred ground water Alternatives
D. The Preferred Water Supply Alternative
E. Bioremediation
F. Responsibilities of the PRPs
G. The Time Frame for the Remedial Action
H. The Site's Impact on the Surrounding Community
I. The Contamination
A. Operations at the Site
1. Why didn't EPA or PADEP take action against Chemclene for so many years even
though both agencies knew there were problems in 1980?
EPA Response: During the early. 1980s. Chemclene assumed responsibility for
investigating and cleaning up the contamination at the Site. Chemclene provided carbon
filters for the affected residents, performed drum removal activities at the Former
Disposal Area and removed contaminated soil at the Former Disposal Area. The
majority of this work was performed with the oversight of Pennsylvania Department of
Environmental Resources. In 1987, EPA took an administrative enforcement action
pursuant to the Resource Conservation and Recovery Act (RCRA) against Chemclene and
entered into a Corrective Action Order with Chemclene. The Corrective Action Order
required Chemclene to investigate and remediate contamination at the Site. Chemclene
failed to implement the requirements of the RCRA Corrective Action Order and began
considering the Site under the Superfund remedial program in November 1993.
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2. Several commentors expressed their disapproval that Chemclene was allowed to operate
for so many years even though Chemclene mishandled chemicals, creating a hazard for
area residents. The commentors felt that Chemclene should not be permitted to stay in
business.
EPA Response: See Response to Part I, A. #7 and Part II, E. #7.
3. A representative from one of the PRPs inquired how his company could be sure that
something like this would not happen to him again (i.e. be named a PRP at other sites).
How could he find out if the vendor to which his company currently transports waste was
doing the same things as Chemclene did?
EPA Response: EPA encourages companies to minimize their waste stream instead of
creating waste that needs to be disposed of in some manner, and to examine their
processes for opportunities to eliminate the creation of waste in the first place. If waste
is created, however, to inquire about a disposal or treatment company's environmental
record, the public can call the state environmental agency or the appropriate EPA
Region to find out what per mil (s) the company holds and if that company has been found
to be in violation of any environmental regulations. PADEP regularly inspects all .
companies permitted to accept hazardous waste in Pennsylvania. EPA information is
available to the public under the Freedom of Information Act.
4. Who currently regulates Chemclene's operations at the Site?
EPA Response: Chemclene Corporation does not have a hazardous waste treatment,
storage, or disposal permit. The current operation is regulated by the East White land
Township, Office of the Fire Marshall. Chemclene Corporation holds a Hazardous
Operations Permit with the Office of the Fire Marshall and is permitted to store
combustible liquids and oxidizers at the facility. The storage of certain amounts of
chemicals is subject to the federal Emergency Planning and Community Right to Know
Act.
5. Who sets the standards and regulations which the East Whiteland Township Fire
Marshall must enforce when regulating Chemclene - EPA, PADEP, or East Whiteland
Township?
EPA Response: The Fire Marshall regulates Chemclene Corporation in accordance with
the Fire Prevention Code of East Whiteland Township. The Fire Prevention Code is
adopted by the East Whiteland Township, Board of Supervisors. During the public
meeting a reference was made to the BOCA codes but this was incorrect.
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6. What or who occupied the Site before Chemclene started a business there?
EPA Response: According to aerial photography, prior to the beginning of Chemclene's
operation in 1952, the area was forested
1. Why was there no enforcement action taken against Chemclene for so many years and
why didn't EPA notify or warn other companies that dealt with Chemclene that there
were problems at the facility? Chemclene had all the required EPA licenses.
EPA Response: EPA generally does not warn other companies of environmental
problems. Generally, it is up to the generator to ensure the facility they choose for
disposal is in compliance. See Response #/ above and Response in Part 11, Section E. 1
on page 37.
8. When was Chemclene's hazardous waste permit revoked ?
EPA Response: Chemclene withdrew its hazardous waste permit (Part B permit) in
July 1992. This response is corrected from that given at the public meeting where it was
stated that Chemclene's hazardous waste operations ended in mid-1993.
B. The Preferred Soil Alternatives
1. If EPA excavated the soil from the Former Disposal Area and transported it to the Main
Plant Area, what would the pile look like? How high would the pile be? What kind of
vegetation would be placed over the soil?
EPA Response; Although the details for this alternative would be part of the detailed
design, the mound of soil probably would be between JO and 20 feet high, the mound
would be capped, and the final surface of the cap would be a grass cover. However, the
steepness of the mound would affect the type of vegetation that could grow. The type of
vegetation could have been specified in the Record of Decision. Before the soil is moved
to the Main Plant Area, preparation of the Main Plant Area would be required, therefore,
the collapsed quonset hut would be removed.
2. A representative of one of the PRPs and several area residents expressed formal
opposition to the preferred alternative for the Former Disposal Area soils (FDA-S-8).
Residents suggested the soil be left at the Former Disposal Area and treated or excavated
and taken offSite.
EPA Response: As a result of public comment, EPA has reconsidered the Proposed
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Remedy and has made a modification. The remedy selected for the Former Disposal
jirea soils is FDA-S-4, Excavation and OffSite Treatment and Disposal. Seepage 60 of
the Selected Remedy.
3. Will there be deed restrictions associated with the cap at the Main Plant Area and these
restrictions also apply to the Former Disposal Area if EPA chose the cap alternative at the
Former Disposal Area?
EPA Response: Yes, if a cap is placed over portions of the Site, EPA will place deed
restrictions on the property to prevent any use that -would adversely impact the capped
area.
EPA would like to clarify the response given at the public meeting with respect to the
restriction of the current business and implementation of a cap remedy. If the only
remedy available to EPA restricted the current business operation, EPA would still have
the authority to proceed. However, if an equally protective, cost effective remedy is
available that would allow a business to continue operation then EPA 's policy would be
to look favorably,on that alternative and consider it strongly for selection.
4. What will EPA do to maintain the cap and how long will EPA maintain the cap?
EPA Response: The purpose of the cap at the Main Plant Area is to reduce infiltration of
precipitation through contaminated soil Since contaminated soil will be left in place,
EPA has incorporated 30 years of cap operation and maintenance (O&M) into the
preferred clean-up alternatives at the Main Plant Area. The O&M is the responsibility of
the party undertaking the remedial action which in this case will be either the responsible
parties or EPA. If EPA were to perform the remedial action then EPA would enter into a
Super-fund State Contract with the Commonwealth of Pennsylvania to perform the
Operation and Maintenance activities at the Site. The Site would be evaluated every five
years by the responsible parties or EPA. If, after 30 years, EPA believes that the remedy
has remained and will remain protective of human health and the environment, the site
can be deleted from the National Priorities List. EPA believes there is a possibility that
the operation and maintenance at the Main Plant Area could last longer than 30 years
due to the suspected presence of dense non-aqueous phase liquids in the groundwater.
5. A resident commented that she has read articles which stated that a downside of the
alternatives under consideration is the release of hazardous vapors in the air. The resident
asked if EPA could promise that no such air pollution will occur with soil movement,
• pumps and wells.
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EPA Response: Release of vapors during soil excavation activities may occur and these
releases were considered in the evaluation of alternatives. However, air monitoring will
be performed during the remedial action to ensure that the residents and Site workers
performing the soil excavations are not exposed to unacceptable levels of contaminant
vapors. Additionally, during the RI, air monitoring -wasperformed during drilling
activities and there was no indication of unacceptable levels of contaminant vapors.
With respect to the groundwater treatment system, the air stripper exhaust will be treated
using activated carbon adsorption or U/V oxidation. If responsible parties install the
•wells, they will need to work to resolve access matters.
6. If EPA proposes to excavate the soil at the Former Disposal Area and move it to the
Main Plant Area Corrective Action Management Unit (CAMU), why not treat it once it is
moved?
EPA Response: EPA did consider the ex-situ treatment of the Former Disposal Area soils
in the vicinity of the residences. However, EPA did not believe that the onSite treatment
alternatives provided the best balance among the evaluation criteria. In addition, EPA
considered treating the soils in-situ once they were placed back onto the ground at the
Main Plant CAMU. Even with a CAAfU designation, more stringent State environmental
regulations could impact the placement of the soils after onSite treatment. The
contaminants in the soil are listed hazardous wastes, therefore, the soil must be handled
as a hazardous waste and certain stringent State and Federal regulations apply to the
treatment and land disposal of the treated soil. Therefore even after treatment the soil
may still require qffSite disposal if certain treatment levels are not achieved. EPA did
not see the benefit in treating the soil on-Site and possibly be required to still dispose off-
Site. However, EPA has reconsidered moving the Former Disposal Area soils to the
Main Plant CAMU and instead has selected Alternative FDA-S-4, Excavation, OffSite
Treatment and Disposal.
7. A resident suggested that EPA further evaluate placing a cap over the contaminated soil
at the Former Disposal Area rather than excavating it and moving it to the Main Plant
Area.
EPA Response: EPA evaluated the use of a cap at the Former Disposal Area in the FS
and believes the cap alternative does not provide the best balance of the evaluation
criteria. However, EPA has reconsidered moving the Former Disposal Area soils to the
Main Plant Area CAMU. See Response above.
C. The Preferred groundwater Alternatives
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1. If Catanach Quarry closed, would the groundwater flow change?
EPA Response: The groundwater flow at the Main Plant Area is affected by pumping at
the Catanach and Cedar Hollow quarries. If both quarries ceased pumping, the natural
flow direction would be to the south.
2. Why is EPA proposing to reinject the treated water into the ground rather than
discharging the water?
EPA, Response: EPA believes that reinfection of treated groundwater into the aquifer is
the most appropriate discharge method at this Site since it lies in the Valley Creek
watershed. The Valley Creek has been designated an Exceptional Value Stream by
Pennsylvania and EPA prefers not to discharge to Valley Creek in this case. EPA would
like to clarify the response given at the public meeting regarding discharge to Valley
Creek Although EPA has selected reinfection for the Malvern Site, if EPA determined
that other discharge options were not available or effective, EPA could opt to discharge
to Valley Creek.
3. To where will EPA reinject the water after it has been treated?
EPA Response: EPA will reinject treated water from the Main Plant Area into injection
wells located on property owned by East Whiteland Township east of the Main Plant
Area and west of Phoenixville Pike. Since EPA has selected Natural Attenuation at the
Former Disposal Area, reinfection of water will not be required.
4. Is the land on which EPA proposes to place the reinjection wells, and which EPA stated
was owned by East Whiteland Township, the same land located along Phoenixville Pike
that is deeded as recreational land for the Aston Woods Development?
EPA Response: The parcel of land where EPA proposes to place the reinjection wells
runs along the fence line of the Main Plant Area adjacent to Phoenixville Pike. The area
currently is wooded and several monitoring wells are located on the property. EPA has
been coordinating with East Whiteland Township Board of Supervisors who have
commented on the use of the land for placement of injection wells.
5. Is EPA required to obtain permission from East Whiteland Township to install the
reinjection wells on the township's property?
EPA Response: Because of overriding federal authority, strictly EPA is not required to
do this. However, EPA plans to work cooperatively with the East Whiteland Township
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Board of Supervisors to obtain their consent for access for the installation of the
reinfection wells. EPA incorrectly responded at the public meeting that permission from
the East Whiteland Township Board of Supervisors would be required, because our
policies generally encourage us to work out access issues in a cooperative spirit with
other government agencies. If responsible parties install the wells, they will need to work
to resolve access matters.
6. How will EPA get approval from the East Whiteland Township Board of Supervisors to
install the reinjection wells on the township's property?
EPA Response: As clarified above, it is EPA 's practice to coordinate such access issues
with property owners. EPA coordinated access with the Township for the installation of
monitoring wells for the RJ activities. EPA has received the Township's comments on
the Proposed Plan and use of the property. See Part II, Section B.
1. At what concentration of contaminants will EPA turn off the ground water pump-and-treat
system at the Former Disposal Area?
EPA Response: EPA has made a modification from the Proposed Remedy at the Former
Disposal Area from FDA-G-6 (Groundwater Collection and Treatment of Source Well) to
FDA-G-4 (Natural Attenuation). Therefore, although the selected remedy at the Former •
Disposal Area is not an active pump and treat system, the remediation through natural
attenuation will continue until the groundwater reaches drinking water standards (i.e.
MCLs).
8. What is the cost per ton of removing and treating the contaminants which the pump-and-
treat system will remove from the groundwater?
EPA Response: EPA does not have a estimate of cost per ton. EPA has tried to provide
an estimate of the cost per gallon using the cost estimate of Alternative MPA-G-6
provided in Appendix C of the FS. However, it is very difficult to estimate the volume of
water that will require treatment since the plume at the Main Plant Area may not be
clearly defined.
9. Once the pump-and-treat system is started, what will be done to replace the water being
removed from the aquifer? What prevents water from the surrounding areas from getting
into the pump-and-treat system?
EPA Response: I) The water being removed from the aquifer will be treated and
reinjected. 2) The objective of pump and treat is to draw contaminated groundwater
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towards a well where it is extracted for treatment. The extent of the capture zone is
related to the pumping rate within the well. This rate can be adjusted to minimize
capture ofuncontaminated water.
1 0. Did EPA consider constructing a physical barrier to prevent the contaminated water from
migrating?
EPA Response: Barrier technology is applied to shallow unconsolidated material which
is not the case at this Site. The Malvern Site is located in complex bedrock geology and
barrier technology is inappropriate.
II. A representative from the law firm of Drinker, Biddle, and Reath expressed his firm's
formal opposition to the preferred groundwater alternatives for the Former Disposal Area
and Main Plant Area.
EPA Response: EPA has considered this comment in the final remedy selection. See
Part II, Section, #2 of this Responsiveness Summary.
12. Why is EPA proposing to treat the groundwater at the Former Disposal Area if EPA also
claims the water cannot be contained? Why spend the money to pump and treat the water
to remove only a portion of the contamination?
EPA Response: EPA proposed to pump the source area in the central portion of the
groundwater plume in an effort to reduce contaminant mass remaining in the aquifer and
to expedite the cleanup. However, EPA has reconsidered the proposed cleanup of the
Former Disposal Area groundwater and has selected Natural Attenuation of the
groundwater at the Former Disposal Area. See Part II, Section C, #2 of this
Responsiveness Summary.
13. Who currently uses the water flowing from the Site and who could possibly use it in the
future?
Response: Currently, residents who live in Hillbrook Circle and residents living
along Conestoga Road and Phoenixville Pike use water that flows from the Site. Future
residents who build homes and drill wells in the affected area could be impacted.
14. Instead of installing the reinjection wells on the township's property, could EPA install
the wells on the Balderston property?
EPA Response: EPA considered installing the reinjection wells in an upgradient location
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on the Balderston property when evaluating the alternatives in the FS. However,
.groundwater modeling in the FS indicates that if reinfection wells are placed on the
downgradient end of the contaminant plume on the township property, the reinjected
water will act as a hydraulic barrier and reduce the potential of plume migration.
15. A resident expressed his formal support for EPA's preferred alternatives to cleanup the
Malvem Site. He particularly supported the collection, treatment, and discharge of the
groundwater.
EPA Response: EPA has considered the comment in the final remedy selection. EPA has
endeavored to select a remedy that is acceptable to the community.
D. The Preferred Water Supply Alternative
1. Will EPA connect all residents along Phoenixville Pike to public water?
EPA Response: The final selected remedy requires the connection of all impacted or
potentially impacted residences to the public water supply. This includes residences
along Phoenixville Pike that are currently part of the Domestic Well Management Plan.
See Table 14 of the ROD.
2. Which homes on Hillbrook Circle would EPA connect to public water?
EPA Response: The final selected remedy requires the connection of all impacted or
potentially impacted residences to the public water supply. This includes all residences
on Hillbrook Circle that are currently part of the Domestic Well Management Plan. For
a complete list of residents, see Table XX of the ROD.
3. How will EPA be able to monitor the movement of contaminants if the wells around
Hillbrook Circle are abandoned?
EPA Response: The domestic wells in Hillbrook Circle are not specifically designed or
constructed for monitoring purposes. Therefore, the abandonment of these wells will not
impact the monitoring of the groundwater plume. A monitoring system, which will
include the installation of new monitoring wells, will be installed to monitor the
groundwater.
4. . Will Philadelphia Suburban Water Company have rights to the aquifer?
EPA Response: Water use rights issues are generally beyond the scope of EPA's
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activities. With regard to the Malvern Site, however, EPA's remedy specifically prohibits
use of contaminated groundwater by anyone, in order to protect public health. EPA can
lift this restriction after the aquifer is remediated.
5. A representative from the law firm of Drinker, Biddle, and Reath expressed his firm's
formal approval of EPA's preferred water supply alternative. His firm believes that the
key clean-up issue is preventing residents from drinking the water.
EPA Response: EPA has considered this comment and has selected the provision of a
public water supply in the final remedy selection. EPA has also selected institutional
controls to prevent use of contaminated groundwater.
6. Why is EPA proposing to spend money to cleanup the groundwater if EPA also proposes
to connect residents to the public water supply?
EPA Response: EPA is continually faced with the challenge of ensuring adequate and
safe drinking water supplies, now and in the future. " Writing off" existing potential
supplies because of chemical contamination increasingly reduces the country's ability to
assure adequate, clean supplies over time. Several federal requirements therefore apply
to this important water resource. The National Contingency Plan (NCP) at 40 C.F.R.
Section 300.430 requires that groundwater be restored to its beneficial use, which at the
Malvern TCE Site is a current drinking water supply. Also, the Selected Remedy must
meet all ARARs, which require remediation of groundwater to MCLs.
7. How can residents be sure that the public water will be of better quality than the well
water they currently drink? Will the water be tested?
EPA Response: The responsibility for ensuring the quality of the drinking water rests
with the water provider, Philadelphia Suburban Water Company. The water provider is
required to monitor the public water supply to ensure that the supply is in accordance
with the federal Safe Drinking Water Act (SDWA), 42 U.S.C §§ 300fto SOOj-26. The Act
establishes enforceable, health-based drinking water standards.
8. A resident expressed his appreciation for EPA's response to the situation. This resident
also was concerned about miscommunications that occurred since EPA knew about
contamination in residential wells during the 1980s. The only reason he found out that
his well was contaminated was because his well went dry in 1991 and he had to have his
new well water tested.
EPA Response: EPA understands the resident's concern and will try to alleviate this
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problem in the future. Since EPA 's Office of Superfund Programs assumed the remedial
activities at the Site, there has been an extensive outreach to the surrounding residents.
EPA will continue this outreach through the completion of the remedial activities.
9. A representative from one of the PRPs suggested that the Malvem Site is an appropriate
site to use PADEP's new Act II Program and Site Specific Remedies.
EPA Response: EPA has considered the applicability of the Land Recycling and
Environmental Remediation Standards Act ("Act 2") to the Selected Remedy at the
Malvern Site. However, EPA does not believe Act 2 to be an ARARforthe Selected
Remedy. EPA will continue to work with PADEP in implementing an appropriate
cleanup at the Site.
10. Will EPA pay for the expense of connecting Hillbrook Circle residents to the public water
supply?
EPA Response: The cost of connecting Hillbrook Circle residences to the public water
supply will be addressed by the Selected Remedy which as required by CERCLA is the
responsibility of the Responsible Parties. The residents will be responsible for -water
usage.
11. If residences are connected to the public water supply, will EPA dispose of the
contaminated filters currently in place?
EPA Response: The disposal of the filtration units and filters is a performance standard
of the Selected Remedy, and will be conducted by either the PRPs or EPA. Seepage 53
of the ROD.
12. A resident inquired why some of the homes near the Site did not have filtration systems
installed on their wells. This resident did not have one and requested that EPA place a
filter on his well until his home is connected to the public water supply.
EPA Response: EPA monitors well data for all homes in the Domestic Well Management
Plan on an annual basis and some homes on a bi-annual basis. The only homes that are
currently on filters are those that are above MCLs, levels that have been established by
the Safe Drinking Water Act. Homes that have not been placed filters have not had an
exceedance of an MCLfor the contaminants of concern.
£. Bioremediation
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1. Why hasn't EPA considered using bioremediation and air injection to cleanup the
contaminated soil?
EPA Response: EPA did consider both bioremediation and air inject ion for remediating
soils at both the Main Plant Area and the Former Disposal Area. Various technologies
screened for the soils at the Former Disposal Area and Main Plant can be found in
Tables 3-2 and 3-4 of the FS. At both locations, bioremediation of soils was rejected as
a technology because the aerobic biodegradation of chlorinated compounds has not been
found to be effective. Air injection was considered under the description of Soil Vapor
Extraction (SVE). In this process, the volatile organic compounds are volatilized by
forcing air through the subsurface and removing the air for treatment. Although SVE at
both the Former Disposal Area and Main Plant Area was retained as a cleanup
alternative, EPA believes the FDA-S-4, Excavation, OffSlte Treatment and Disposal of
Soils andMPA-S-3, Capping Soils at the Main Plant, provide the best balance among the
nine criteria.
1 t
2. A resident noted that she had read some articles in the Philadelphia Inquirer and the New
York Times about bioremediation. She inquired if EPA had considered using that
technology to cleanup the contamination at the Site or combining it with another clean-up
method.
EPA Response: EPA considered bioremediation early in the Feasibility Study (FS) as
discussed above including consideration of technical studies, however, EPA did not
specifically evaluate the articles the resident referenced.
F. Responsibilities of the PRPs
1. Will the PRPs be responsible for providing the money for the cleanup as soon as the
ROD is issued?
EPA Response: Once EPA selects the final clean-up plan, EPA will initiate negotiations
with the PRPs to conduct the clean-up activities which consists of design of the remedy,
then implementation, followed by long-term operation and maintenance. These
negotiations typically take several months.
2. How often do PRPs cooperate with EPA?
EPA Response: PRPs often cooperate with EPA and conduct the necessary activities to
cleanup a hazardous waste site. EPA estimates that PRPs conduct the remedial activities
at approximately 70% of the Superfund Sites.
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3. If Chemclene had liability insurance to cover the costs of cleaning up the site, would the
generator PRPs also be responsible for the clean-up costs?
EPA Response: If Chemclene had liability insurance to cover the cost of the cleanup, the
owner could attempt to access this to perform the remediation at this Site. However,
under law, most PRPs are jointly and severally liable for cleanup costs.
4. Has EPA investigated Chemclene's insurance records from the year the company began
operations to determine if there is insurance coverage that could be used to pay for the
cleanup?
EPA Response: EPA is currently conducting an extensive investigation of all of
Chemclene's financial records.
G. The Time Frame for the Remedial Action
1. While the question of who will pay for or conduct the cleanup is being resolved, will
further clean-up actions stop?
EPA Response: The formal settlement process and a 120 day moratorium on further
EPA actions begin with the issuance of special notice letters to the PRPs. Special notice
letters are authorized by CERCLA when EPA determines that a period of negotiation
would facilitate an agreement with PRPs for taking a response action. Once special
notice letters are issued, a 60-day moratorium period is required. This allows the PRPs
that time to submit a good faith offer to perform the work. If such an offer is received,
the moratorium is extended an additional 60 days.
2. If the issue of funding the cleanup goes to litigation, will the cleanup wait until the court
battle is settled?
EPA Response: No. If the PRPs do not present a good faith offer to EPA within 60 days
after the issuance of the special notice letters, EPA has the enforcement option to require
the PRPs to fund the cleanup, or EPA may start the clean-up process using Superfund
money. If EPA uses money from the Superfund to fund the cleanup, EPA may recover
those costs later through litigation.
3. When will EPA make a decision about the final clean-up plan and when will the actual
cleanup be started?
EPA Response: The public was requested to submit comments and questions about the
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Proposed Plan to EPA by September 2, 1997. EPA has considered all comments and
questions in the selection of the final remedy. With issuance of the ROD, EPA will begin
negotiations with the PRPs regarding who will conduct or pay for the cleanup. The
negotiations could take several months. It is likely that the design of the remedy will
begin in late 1998 and construction may begin in late 1999.
H. The Site's Impact on the Surrounding Community
1. If the property were no longer used and institutional controls were in place, would those
facts significantly change the risk of human exposure to contaminants?
EPA Responses Yes. Although highly unlikely, if the Chemclene property no longer were
used and institutional controls were in place, there would be no exposure to
contaminants and therefore no risk. However, contaminants would remain, potentially
causing future problems. Institutional Controls would include prohibiting use of
groundwater throughout the entire area of the plume. This will be a challenge to fully
enforce.
2. Does contamination from the Site impact Valley Creek?
EPA Response: EPA has sampled surface water on the Site and in-Valley Creek and has
determined that contaminants from the Site surface water have not impacted surface
water in Valley Creek.
3. A pipe designed to collect storm water and run-off from Phoenixville Pike is being
installed in the Charlestown Oaks Townhouse Development above the Aston Woods
Development. The pipe discharges to Valley Creek. If contaminated water were picked
up in the pipe, would it be discharged into Valley Creek?
EPA Response: See Response H.2 above.
4. How much of the clean-up activities will be visible from Phoenixville Pike and the Aston
Woods Development? What will the clean-up activities look like and how long will they
last?
EPA Response: The exact details of the clean-up activities will be determined in the
remedial design. However, it is quite possible that some cleanup activities will be visible
from Phoenixville Pike and Aston Woods. EPA estimates that construction could take up
' to two years.
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5. What would the risk be to human health if EPA only connected residences to public
water, placed deed restrictions on the property, and fenced and capped the area?
EPA Response: If EPA connected residences to the public water supply, placed deed
restrictions on the property, and fenced and capped the area, there -would be no exposure
to contaminants, therefore there would be no current risk to human health. However,
contaminants would remain, potentially causing risk to people in the future.
6. In the past, did the Site contamination impact the high school? Will the site cleanup
impact the high school in the future?
EPA Response: EPA's studies indicate that soil contamination is confined to the
Chemclene property and has not impacted the High School. In addition, the High School
uses public water supplied by PWSC. Groundwater contamination flows to the northeast
from the Main Plant and the High School is located to the southeast. During the RI at
the Site, EPA conducted air monitoring which indicated that there were no unacceptable
levels of contaminants in the air.
For future impacts see Response B. 7 above.
7. Is there a record of any of the high school students coming into contact with the Site
contaminants? This inquiry was based on knowledge that the high school's cross country
team used to run across the Chemclene property during practice, biology classes studied
nearby wetlands, and children living in Aston Woods crossed the property as a shortcut.
EPA Response: EPA pointed out that the Former Disposal Area and Main Plant Area
previously were and currently are fenced. Therefore, if students crossed the property it
was most likely property next to the Site which Mrs. Balderston used to own and which
the Springridge Development Corporation currently owns. That property is not
contaminated. In addition, the surface soils on the areas of concern at the Site do not
pose an unacceptable risk. It is the subsurface soils at the Main Plant Area that pose an
unacceptable risk
8. Does EPA need the approval of the East Whiteland Township Board of Supervisors to go
ahead with the cleanup?
EPA Response: No. EPA does not need the approval of the East Whiteland Township
Board of Supervisors to proceed with the clean-up plan. However, EPA will work
cooperatively with the township in the implementation of the Selected Remedy.
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9. Will residents living near the Site be able to sell their homes without suffering a loss?
EPA Response: Residents impacted or potentially impacted by the Site have been
identified and will be provided public water. EPA often receives inquiries from real
estate agents and explains the facts about the Site to them. However, EPA has no
information about whether real estate values near this Superfund Site may have been
impacted. Existence of contamination could possibly affect real estate values. EPA plans
to ensure cleanup and control of this contamination, thus, over time, benefitting real
estate values.
10. Why didn't EPA warn people in the past about the potential risks associated with the
Site?
EPA Response: The potential risk to surrounding residents is primarily due to the use of
groundwater. The residents using groundwater that have been impacted have been
placed on carbon filters to remove contaminants. In addition, routine sampling of
potentially impacted residents that are not contaminated has been performed to ensure
the condition does not change. EPA has learned that newer residents moving to
Hillbrook Circle were not made aware of the groundwater contamination when their
homes were purchased. EPA has implemented a Community Relations Plan at the Site
and will continue this outreach through the completion of the remedial activities.
11. Has EPA considered using Brownfields as a standard for cleaning up the site?
EPA Response: "Brownfields " is EPA 's term for minimally contaminated urban sites on
which we seek to encourage redevelopment. The Chemclene property is highly
contaminated and thus, is has been listed on the NPL.
12. If EPA does not cleanup the Site, will it threaten Valley Creek?
EPA Response: Yes, it is possible that Valley Creek could be impacted if the Selected
Remedy is not implemented.
13. Instead of spending $ 14 million for the proposed alternatives, EPA should purchase all
the homes affected or potentially affected by the contamination, relocate the homeowners,
and declare the area uninhabitable.
EPA Response: The Selected Remedy provides protection of human health and the
environment and therefore, there is no need to declare the area uninhabitable.
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I. The Contamination
1. How will EPA ensure that the Site will not be contaminated further?
EPA Response: Chemclene is not permitted to accept any hazardous waste at its
property. The company has a permit with the East Whiteland Township Fire Marshall to
store hazardous materials. The Fire Marshall also periodically inspects the facility.
Chemclene is prohibited from treating, storing, or disposing of hazardous wastes on the
property. Chemclene's hazardous waste handling practices were the original cause of
the contamination.
2. How did EPA determine that a nearby septic tank cleaner was not the cause of the
contamination in the southwest comer of Hillbrook Circle?
EPA Response: EPA has responded to this comment below in Part II, Section C, #7.
3. Prior to 1980, was there an analysis conducted of Hillbrook Circle's drinking water?
EPA Response: EPA does not believe that the drinking water around Hillbrook Circle
was analyzed prior to 1980.
4. Are there hazardous contaminants in the groundwater at the Site that also are found in the
grouhdwater at the Catanach Quarry?
EPA Response: It is EPA 's understanding that TCE has been detected at the Catanach
Quarry. However, EPA has not determined that the Malvern Site is the source of this
contamination. Further investigation of the extent of the contaminant plume at the Main
Plant Area will be conducted during Remedial Design.
Part II; Summary of Commentors* Major Comments and Questions Received in Writing
During the Public Comment Period
This section provides technical detail in response to comments or questions on the
Malvem Site. EPA received these comments or questions in writing during the public comment
period. These comments or questions may have been covered in a more general fashion in Part I
of this Responsiveness Summary. The following specific comments are addressed:
A. Comments of North Industrial Chemicals, Inc.
B. Comments of East Whiteland Township
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C. Comments of Environmental Resources Management (ERM) on behalf of the
Malvern Site Study Group, a PRP group
D. Comments of David DeWitt on behalf of the Concerned Residents of East
Whiteland Township (CREW)
E. Comments of Fox, Rothschild, O'Brien & Frankel, LLP and Walter B.
Satterthwaite Associates Inc. on behalf of the Malvem De Minimis PRP Group
F. Comments of United States Department of Interior
G. Comments of Mr. & Mrs. Charles Kocher
H. Comments of Pennsylvania Environmental Defense Foundation
A. Comments of North Industrial Chemicals, Inc.
In a one-page letter dated July 16,1997, Jack Hammond, a representative of North
Industrial Chemicals Inc., submitted comments to EPA regarding the Malvem TCE Proposed
Plan.
1. Why did EPA favor Chemclene when considering methods to cleanup the Site
contamination? The proposed alternatives work around Chemclene's current operations
thereby increasing the cost of the remediation and the risk of additional contamination.
EPA Response: See Response E.6, page 39 of this Responsiveness Summary.
B. Comments of East Whiteland Township
In a one-page letter dated August 15,1997, J. Donald Reimenschneider, East Whiteland
Township Manager, submitted recommendations on behalf of East Whiteland Township
regarding EPA's proposed alternatives for the Malvern Site.
1. EPA should convey the treated groundwater to the six proposed injection wells on the
township property using underground piping.
EPA Response: EPA understands the Township's concern regarding the construction of
the injection -well system and will work with the Township during Remedial Design to
address such concerns.
2. EPA should place protective fencing around each of the proposed injection wells.
EPA Response: It is possible to construct flush mount injection wells and therefore,
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fencing would not be required. However, these details will be addressed during the
Remedial Design andEPAjvill take the Township's concern under consideration during
the design.
3. EPA should be responsible for maintaining the injection wells, including capping and
filling them upon decommissioning. Well abandonment must comply with County
Health Department regulations.
EPA Response: The Selected Remedy addresses the issues raised in this comment. Please
see page 5 7, of the ROD.
4. EPA should provide public water, at EPA's expense, to the Hillbrook Circle residences
and other residences whose wells were affected by Chemclene.
EPA Response: EPA agrees and has selected the Public Water Supply Alternative for the
provision of public water. See ROD page 52. Under CERCLA, remedy costs will
ultimately be borne by the Responsible Parties, even if the Fund pays for the remedy.
C. Comments of Environmental Resources Management (ERM) on Behalf of the
Matvern Site Study Group, a PRP Group
In a 82-page document dated August 29,1997, ERM, on behalf of the Malvern Site Study
Group, submitted comments on the Proposed Plan and RI/FS for the Malvern Site. The
comments and responses are summarized below.
1. EPA incorrectly identified the Malvern Site as the source of contamination for several
domestic wells in the southwest comer of Hillbrook Circle. The Former Disposal Area
is not the source of the volatile organic compound (VOC) contamination in the area of
DW-058. The exact source currently is undefined, but may be related to historical use of
chlorinated solvent products to unclog a septic system drain field.
EPA Response: EPA disagrees and believes the facts show otherwise. Precise
delineation of contaminant distribution in this area is difficult due to the reliance on
active residential wells of varied construction for monitoring purposes. Contaminant
levels in this area are also very low and the relatively flat potentiometric surface
compounds the difficulty of defining an exact plume outline. Acceptance of whether
Hillbrook Circle development is impacted by one dispersed low level plume or a possible
second source of contamination does not affect EPA's selection of a remedial action for
domestic wells in the development. Continued use of wells in the development represents
the potential for spreading of contamination to previously uncontaminated wells.
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Therefore, the proposed remedy of connecting all residents in the Hillbrook Circle
development, on Phoenixville Pike, and on Conestoga Road to public water supplies still
offers the best protection for residents in the area.
ERM's interpretation of the local groundwater flow in the area around the Former
Disposal Area appears flawed and incompatible with realistic interpretation of the
regional potentiometric surface map developed by USGS. This potentiometric surface
map (McManus andSloto, 1997: Plate 1) indicates that groundwater flows
south/southwest from the Former Disposal Area through the Hillbrook Circle
development, and then intercepting Valley Creek where potentiometric lines form an
acute angle (304 feet NGVDD1929) north of Conestoga Road. ERM's hypothesis that
groundwater flows from the Former Disposal Area to the northeast toward the quarry
complex under the flow regime mapped by USGS would require the groundwater flow
direction to change greater than 90 degrees after leaving the Former Disposal Area, with
flow moving from an area of lower to higher potentiometric head across a well defined
groundwater divide. A northeastward flow direction was discussed in the RJ report as a
transient occurrence coinciding with elevated pumping at the quarries, but not suggested
for the potentiometric surface developed by USGS.
2. EPA concluded that natural attenuation processes are reducing contaminant
concentrations in the Site groundwater and are inhibiting the migration of Site
contaminants. However, EPA failed to incorporate significantly natural attenuation into
the Proposed Plan.
EPA Response: EPA did incorporate natural attenuation in the Proposed Plan by
proposing FDA-G-6, groundwater extraction and treatment, at the Former Disposal
Area. This alternative focused pumping on the source area of the contaminant plume at
the Chemclene property and allowed natural attenuation of the plume off the Chemclene
property. And, as explained below, EPA has determined Natural Attenuation to be
acceptable, provided it can meet required cleanup levels in accordance with Section X. E
of the Selection Remedy.
As indicated in the RJ Report, CAH's in the contaminant plume emanating from the
Former Disposal Area exhibit significantly elevated concentrations of degradation
products of TCE, 1,1,1-TCA, andPCE. At several monitor wells, concentrations of
degradation products exceed the concentrations of more halogenated and chlorinated
CAH's. Additionally, evaluation of historical data indicates that concentrations of CAH's
in monitor wells at the Former Disposal Area, and nearby domestic wells have been
decreasing with time since the last removal of drums at the mounded area in 1990. With
time, the contaminant plume should continue to recede. Modeling of the contaminant
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plume using a series of first order equations indicated that contaminant concentrations
should decline below MCL 's within 16.5 years (CH2M HILL, 1997). Due to the inherent
uncertainty associated with modeling it was EPA's initial position that a short term
active pump and treat remedy would remove these doubts by expediting natural
attenuation process. However, EPA has re-evaluated this approach and has concluded
that the overall risk of a natural attenuation remedy at the Former Disposal Area is
acceptable if the 52 residential wells around the Site are connected to public water
supplies. In addition, these domestic wells need to be abandoned to prevent further
exposure to the residents, or converted to monitoring wells. This remedy, like all
remedies, can be reevaluated based on measurable performance.
3. EPA did not adequately account for the presence of dense non-aqueous phase liquids
(DNAPLs) in groundwater around the Main Plant Area. EPA's proposed remedial action
would be technically impractical and ineffective in the presence of DNAPLs. Due to the
presence of DNAPLs, EPA will not be able to meet groundwater applicable or relevant
and appropriate requirements (ARARs) in the long-term.
EPA Response: EPA disagrees. ERM's presumption that EPA ignored the presence of
dense non-aqueous phase liquids (DNAPL's) in selecting a remedial alternative for
groundwater at the Main Plant Area is false. Alternative MPA-G-6, Groundwater
Collection, Treatment of Source Area, and Discharge, was selected to reduce
contaminant mass in the center of the groundwater plume and control migration of
contaminants offSite. At the same time, mechanisms of natural attenuation as discussed
in the RJ Report, will help eliminate contaminants from the peripheral areas of the plume.
This approach is clearly stated in the Proposed Plan.
EPA acknowledges that achieving chemical specific A RAR's for groundwater using pump
and treat technology in the presence of DNAPL's is difficult and may be technically
impracticable. A number of technical issues were considered for the selection of
Alternative MPA-G-6. These issues were balanced against the need to protect public
health and groundwater supplies. (The NCP mandates that polluted groundwater be
restored to beneficial use regardless of whether it is used for current public drinking
water supplies.) The selected alternative was intended to reduce the contaminant mass in
the most highly contaminated plume area and decrease the extent of the contaminant
plume. If it becomes evident that the area of highest contamination can not be
remediated to MCLs, this area will be considered for a technical impracticability waiver
as discussed in the ROD, page 64. This waiver will only change the cleanup standards
for the area where the present standard cannot be met. No design changes to the
treatment system would be required. The only practicable change to the system would be
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the re-designation of some remedial wells to containment wells.
EPA has selected Alternative MPA-G-6, Groundwater Extraction and Treatment, as the
remedial alternative for ground-water at the Main Plant Area because there is no
significant design difference between this alternative and one that provides a technical
impracticability waiver for the area of highest groundwater contamination. Any future
changes to this approach can be made based on remedial action monitoring data. EPA
believes this approach recognizes the difficulty of remediating groundwater within the
facility boundaries of the Main Plant Area, as well as the benefits of natural attenuation
to any active pump and treat design.
4. EPA failed to incorporate the site-specific clean-up levels approach to the conditions at
the Site allowed under Pennsylvania's Land Recycling and Environmental Remediation
Standards Act (Act 2), despite identifying the Act as an ARAR.
EPA Response: EPA did not identify Act 2 as an ARAR for this Site. The table that ERM
is referring to in the FS is entitled preliminary. AfinalARARs determination is made as
part of the remedy selection. EPA coordinated with PADEP throughout the remedy
selection process.
5. EPA did not apply the Technical Impracticability (TI) Guidance for Groundwater for the.
likely presence of DNAPLs below the water table at the Main Plant Area.
EPA Response: EPA has considered this guidance as discussed above in response #2.
6. EPA did not consider the effects of the presence of DNAPLs on soil remediation
properly.
EPA Response: EPA did consider the effects of DNAPLs on soil remediation. The
remedial alternative for groundwater was based on a conservative approach in regard to
protection of groundwater supplies, consistent with the NCP. This conservative
approach considered that the contaminant mass in plume at the Main Plant Area could
be reduced while preventing additional downgradient migration of the plume. IfDNAPL
is present, pumping at the source area will contain its migration and recover a certain
volume. Consistent with a conservative approach to groundwater remediation, soil
alternatives were developed to prevent additional leaching of contamination to
groundwater from the unsaturated soils. As the presence ofDNAPL has not been
definitively demonstrated. EPA believes remediation of soil either through soil vapor
extraction (SVE), soil flushing, or prevention of additional leaching with capping, could
aid in the remediation of a dissolved-phase plume by removing the source in the vadose
o
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zone. However, since EPA believes implementation of the cap at the Main Plant Area
provides adequate protection of groundwater, EPA has reconsidered the adoption ofSVE
at the Main Plant Area.
6. EPA did not conduct pilot studies of soil vapor extraction (SVE) to determine if the
technology would be effective under specific site conditions.
EPA Response: EPA had planned a Pilot Study for the Fall of 1997 at the Main Plant
Area to determine the effectiveness of SVE. However, since EPA has not selected SVE at
the Main Plant Area, the Pilot Study was determined to be unnecessary. Instead, EPA
will be using MPA-S-3, Capping at the Main Plant Area.
7. EPA did not consider the cost-effectiveness of natural attenuation as a realistic permanent
solution for groundwater remediation.
EPA Response: EPA has considered the cost effectiveness of natural attenuation as
discussed in Response #2 above. Additionally, EPA has reconsidered the cost
effectiveness of natural attenuation (Alternative FDA-G-4)for implementation at the
Former Disposal Area in lieu of the pump and treat alternative (FDA-G-6) described in
(he Proposed Plan. In accordance with the NCP, cost effectiveness is part of the nine
evaluation criteria for selecting a remedial alternative. Cost effectiveness is grouped
with four other criteria that are known as primary balancing criteria for selecting an
alternative. For EPA, the balancing criteria are secondary to the two threshold criteria
in selecting an alternative:
1. Overall protection of human health and environment
2. Compliance with Applicable or Relevant and Appropriate Requirements
EPA reconsidered FDA-G-4, Natural Attenuation, because the alternative meets the two
threshold criteria at the Former Disposal Area and decided to select it.
However, this is not the case at the Main Plant Area. Cost effectiveness of a natural
attenuation alternative (MPA-G-4) over groundwater extraction alternatives (MPA-G-5
and G-6) at the Main Plant Area was not considered appropriate because natural
attenuation is not protective of human health and the environment at the Main Plant
Area.
Although a number of techniques were performed on analytical data during development
of the RI Report, a reasonable mechanism for natural attenuation (anaerobic
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degradation, dehalogenation, hydrolysis) could not be definitively identified that
explained the attenuation of Chlorinated Aliphatic Hydrocarbons (CAHs) at the Main
Plant Area. In light of this uncertainty, and estimations of an extended period for
constituents to attenuate below MCLs (35 years), natural attenuation was not considered
as a sole alternative for groundwater remediation at the Main Plant Area. Consequently,
a cost effectiveness analysis was not warranted.
8. EPA should have concluded that the proposed Main Plant Area groundwater alternatives
could violate the remedial action objectives (RAOs) by increasing the plume movement
off the property.
EPA Response: EPA disagrees with ERM's interpretation. The remedial action
objective is to restore the Site groundwater to a beneficial use through removal and
treatment of the contaminated groundwater. The Site is defined as the area impacted
groundwater contamination. To achieve this objective, contaminated groundwater will
be pumped to extraction wells both on the Chemclene property and off the Chemclene
property. This action by definition draws contamination to the extraction wells. The
placement of extraction wells on the Chemclene property will be designed to keep the
most contaminated groundwater from migrating off the Chemclene property. Off
property extraction wells will be designed and placed to as to not adversely impact the
purpose of the extraction wells on the Chemclene property.
9. EPA did not evaluate integrated Site-wide alternatives, even though various remedial
actions for specific areas or media interrelate and, in some aspects of the Proposed Plan,
are redundant for meeting the RAOs.
EPAResponse: EPA elected to address the Site in this manner because the Site contains
two areas of concern, each with at least five alternatives for soil and groundwater.
Integration of Site-wide alternatives results in a large and unruly number of
combinations of alternatives for evaluation. In addition, the groundwater and source
control alternatives at each area are relatively independent of each other. An evaluation
of Site-wide alternatives is not required by the NCP. Such an evaluation at this Site
would generate an excessive number of permutations for alternatives, there would not be
much value added, and would detract from the clarity of the FS.
The physical characteristics of the Site accommodates a thorough evaluation of
alternatives for specific media at each area of concern. The Former Disposal Area and
Main Plant Area are separated by 1,900 feet. Although the two areas of concern overlie
the same aquifer, the areas appear to be separated by a groundwater divide.
Subsequently, integrating remedial elements for both sites such as a common
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ground-water or soil vapor treatment plants would be difficult to accomplish without
significant costs for conveying media between sites for treatment.
10. EPA did not apply all elements of the Common Sense Initiative to the proposed
alternatives.
EPA Response: EPA's decision making at Superfund Sites is guided by the National
Contingency Plan. In contrast, the Common Sense Initiative focuses on ongoing
pollution reductions in agency regulated business sectors. In any event, EPA endeavors
to use common sense in all its decision making.
\ 1. ERM suggested the following remedial actions for the Main Plant Area:
• continue operation of the carbon filters until public water is available;
• connect one Phoenixville Pike residence and the Main Plant Area to public water;
• restrict the property to industrial/commercial use;
• place an asphalt cap over contaminated soils;
• place institutional controls on the site to prevent future groundwater use at the MPA;
and
• monitor groundwater to ensure that natural attenuation continues to remove
contamination and limit the extent of the plume.
EPA Response: EPA has considered ERM's suggestion and although EPA has made
modifications from the Proposed Plan, EPA does not believe ERM's suggested remedial
actions for the Main Plant Area, in its entirety, provides the best balance of the
evaluation criteria.
12. ERM suggested the following remedial actions for the Former Disposal Area:
•. continue the operation of carbon filters until public water is available;
• connect affected residents on Hillbrook Circle to public water;
• remediate Former Disposal Area soils by either in-situ treatment or excavation/on-site
treatment and replacement;
• monitor the groundwater to ensure that natural attenuation continues to remove
contamination and limit the extent of the plume.
EPA Response: EPA has considered ERM's suggestion and alt hough EPA has made
modifications from the Proposed Plan, the Agency does not believe ERM's suggested
remedial actions for the Former Disposal Area, in its entirety, provides the best balance
of the evaluation criteria.
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13. Extensive comments were received from ERM regarding the Risk Assessment contained
in Section 6 of the Remedial Investigation. ERM identified the following issues as errors
of significance:
*• Inclusion of natural background metals as chemicals of potential concern (COPCs)
» Misidentification of potential receptors and use of unrealistic exposure scenarios
> Use of historical data maximum concentrations for calculation of future off-site
groundwater risks
» Evaluation of TCE and PCE as carcinogens
» Evaluation of Class C compounds as carcinogens
These issues are addressed in detail below, referencing the specific sections in which they are
discussed in the ERM document which can be found in the Administrative Record for the Site.
EPA disagrees with ERM's conclusions regarding the Risk Assessment and has not made any
changes based on these comments. A detailed response is provided below.
EPA Response:
ERM Section 2.4. LI, Chemicals of Potential Concern
Metals
As ERM suggests, many of the inorganic COPCs detected in site soils and Main Plant Area
groundwater can be found naturally in the environment. To address this possibility, current
Environmental Protection Agency (EPA) risk assessment policy recommends comparing on-site
data to site-specific background data. (Note that when making site-specific decisions regarding
the elimination of COPCs, it is inappropriate to compare site data to background ranges from
the general literature for the entire Eastern United States, as proposed by ERM). At the Malvern
TCE Site, a statistical comparison of Site-related soil and groundwater concentrations to Site-
specific background soil and groundwater concentrations was performed, and only the
inorganics present at levels statistically above background -- and greater than respective Risk-
Based Concentrations (RBCs) — were retained as COPCs in the risk assessment.
Regarding ERM's comment that several background concentrations used for COPC screening
do not correspond to background data reported in the RI, the following point should be noted
In the risk assessment, the maximum detected concentration of each inorganic constituent on-Site
was compared to the 95% Upper Tolerance Limit (UTL)for background constituents. The 95%
UTL does not necessarily equal any single background detection; rather the 95% UTL provides
a statistical representation of the complete background data set.
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ERM questions the appropriateness of evaluating iron in the risk assessment, stating that "iron
is not even a CERCLA hazardous substance, and is therefore not regulated under Superfund."
However, iron is included on the Superfund Target Analyte List. It is current EPA risk
assessment policy to evaluate'the risks associated with all constituents which are analyzed for
and detected at a Site in excess ofRBCs. At the Malvern TCE Site, ironfalls into this category
and was, consequently, carried through the quantitative risk assessment.
In general response to ERM's false claim that naturally-occurring metals in groundwater (and
•soil) were improperly carried through the risk assessment, it should be noted that the inorganic
constituents retained as COPCs in Main Plant Area groundwater do not significantly contribute
to the risk associated with groundwater use, as compared to the gross risks posed by organic
contaminants. Manganese, the inorganic constituent that contributes the highest
noncarcinogenic hazard due to ingestion of groundwater, only contributes 9.3% of the total
hazard. Beryllium, the inorganic constituent which contributes the highest carcinogenic risk due
to ingestion of groundwater, only contributes 5.1% of the total carcinogenic risk. Therefore, the
presence of inorganic constituents in groundwater has no impact what-so-ever on remedial
decisions for the Mahern TCE Site.
Similarly, it must also be noted that there were no significant risks or hazards associated with
direct exposure to site soils that resulted in a decision to remediate soil. The decision to
remediate soil was based solely on the potential leaching of organic contamination from soil to
groundwater. The proposed soil remediation methods are intended to address the soil-to-
groundwater transport pathway, not direct contact with soil.
Specific comments related to the Former Disposal Area are addressed below:
• Contrary to ERM's claim, background metals were not evaluated on the basis of only one Rl
sample. All of the background soil samples collected at the Malvern TCE site were combined
to calculate respective 95% UTLsfor inorganic background constituents. The site-specific
95% UTL background concentration for each inorganic compound was then used to
represent the background concentration for both Former Disposal Area and Main Plant
Area soils. ERM further suggests that background metal concentrations at the Former
Disposal Area were higher than those at the Main Plant Area. This assertion is also
incorrect; background metal concentrations at the Former Disposal Area were not higher
than at the Main Plant Area for the majority of the constituents which were detected.
• ERM questions the inclusion of arsenic as a COPC, citing that "16 of the 21 sample results
were blank qualified. " Arsenic was retained as a COPC because three of the 16 Former
Disposal Area samples had detections of arsenic that were not blank qualified. EPA risk
assessment guidance (EPA, 1989) states that if all samples contain levels of a given
constituent at five times (or 10 times for common laboratory contaminants) the level of
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contamination noted in the blank, then that chemical should be completely eliminated from
the set of sample results (Page 5-17, Section 5.5). Since arsenic was not blank-qualified in
all of the analyzed samples it was rightfully retained as a COPC in the risk assessment.
• The inclusion of cadmium as a COPC is challenged by ERM since only two of 10 samples
contained cadmium in excess of the screening RBCfor residential soil. However, cadmium
was retained as a COPC because the maximum detected concentration in soil exceeded the
background 95% UTL, as well as the RBC. Additionally, contrary to ERM's allegation, the
risk assessment does not assume that chronic exposure will occur at only the most
contaminated 10% of the soils. All confident detects and nondetects for cadmium at the Main
Plant Area and Former Disposal Area are incorporated in the calculation of the exposure
concentration.
• ERM asserts that thallium should not have been identified as a COPC in soil since the
highest detected concentration (3.1 mg/kg) was "not significantly above the non-detect at the
background sample. " Per EPA risk assessment policy, thallium was retained as a COPC
because it was detected in on-site soil in excess of background, as well as in excess of its
RBC.
• ERM contends that even though aluminum was detected at noteworthy levels in soil, it should
not have been evaluated in the risk assessment, since it is "one of the most abundant
elements in the earth's crust. " As was discussed previously, it is current EPA policy to use
site-specific background data, rather than background data from the general literature for
the entire Eastern United States. Site-specific background data were collected at the
Malvern TCE site. . The concentration of aluminum detected at the site exceeded the 95%
UTL for the site-specific background, as well as its RBC.
Again, for the record, it must be noted that there were no significant carcinogenic risks or
noncarcinogenic hazards associated with direct exposure to site soils that resulted in a decision
to remediate the soil. The decision to remediate soil was based on the potential leaching of
organic constituents from soil to groundwater. The proposed soil remediation methods are
intended to address the soil-to-ground water transport pathway, not direct contact with soil.
Therefore, ERM's comments on inorganic data handling are irrelevant to the proposed
remediation.
Laboratory Artifacts
ERM asserts that detections ofbis(2-ethylhexyl)phthalate (DEHP) in VST area surface soil are
"laboratory artifacts, " citing a blank-qualified detection of 62,000 ug/kg as proof of this claim.
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However, DEHP observations that were not blank-qualified are an order of magnitude greater
than the samples that were blank-qualified. The blank-qualified detection of DEHP cited by
ERM (62,000 ug/kg) actually represents a subsurface soil sample collected during a different
sampling event than the confidently detected concentrations used in the risk assessment.
Therefore, it is appropriate to assume that DEHP positively detected in surface soil is truly
present on-Site and, therefore, eligible for risk-assessment consideration. (Note that DEHP
contributed less than one percent of the total carcinogenic risk or noncarcinogenic hazard
associated with exposure to UST area surface soil.)
ERM claims that chloroform is a "laboratory artifact" in several domestic wells and, therefore.
should not have been evaluated in the risk assessment. Risk of exposure to chloroform was
evaluated for several domestic wells because this organic contaminant was not detected in any of
the associated blank samples at similar concentrations during the RI sampling event. Similar
concentrations of chloroform were considered blank-related for different sampling events on
different sampling dates. Additionally, the wells where chloroform was the only COPC did not
pose an unacceptable noncarcinogenic hazard or carcinogenic risk to potential receptors.
ERM Section 2.4.1.2, Receptors and Exposure Scenarios
Since the remedy for this Site involves extension of the public water supply, ERM believes
evaluating groundwater risks in and around the Site, as was done in the risk assessment, is
improper. However, the purpose of a baseline risk assessment is to evaluate current conditions
at the Site, under the assumption that no remediation will be implemented, in order to determine
the need for action. Presently at the Malvern TCE Site, neighboring residents are not connected
to a public water supply and use groundwater as their sole potable source. Further, since
groundwater flow is not confined by Site boundaries, future exposure to downgradient receptors
can -- and will — occur if contaminated groundwater is not addressed. Additionally, irrespective
of current or potential future use patterns, groundwater is considered by the federal government
to be a public asset and, as such, the National Contingency Plan mandates that groundwater be
res tared to its beneficial use to the extent practicable.
Given the objective of such evaluations, EPA makes a clear distinction between risk assessment
and risk management. Using data founded in good science and conforming to EPA's mission of
protecting public health and the environment, the risk assessment provides information on the
potential threats associated with exposure to Site-related constituents. The risk manager uses
this information to determine if clean-up is necessary and, if so, to help decide the best approach
for remediation. Therefore, risks associated with potential potable groundwater use at the
Malvern TCE Site have been provided in the risk assessment for application to risk management
decisions. The technical and engineering issues related to Dense Non-Aqueous Phase Liquids
and other remediation matters that could impact clean-up decisions are addressed in the
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Feasibility Study by the risk manager, not in the risk assessment by the risk assessor (as
requested by ERM).
ERMSection 2.4J.3, Data Set Used
ERM contends that an incomplete data set for off-site groundwater is provided in the Rl report,
and that EPA apparently used the highest historical concentration for each COPC to calculate
risks from exposure. In response to this assertion, it should be noted that data from the June
1996 residential well sampling event were not available at the time the risk assessment was
conducted. Therefore, data from 1995 were used in the assessment of risk Although residential
well sampling was performed on three occasions, no single residential well was sampled more
than twice. Since a 95% Upper Confidence Limit can not be calculated from two sampling
results, the maximum detection of the two samples was used as the exposure concentration in the
risk assessment, per EPA guidance. For many of the wells, only one sample was collected
during 1995; in this case, single sample results were used for risk assessment calculations, also
in accordance with EPA guidance.
ERM disagrees with the inclusion of 1994 groundwater data for estimating Former Disposal
Area risks. However, groundwater data collected from monitoring wells at the Chemclene
property in both 1994 and 1996 were used for the assessment of risks at the Chemclene property.
Use of the 1994 data, in conjunction with the 1996 results, may have resulted in a conservative
risk estimate for the Former Disposal Area groundwater plume. However, use of the 1996 data
alone would have also resulted in an unacceptable risk, triggering the need for action.
ERM Section 2.4.1.4, Quantitative Assessment of TCE and PCE
ERM challenges the inclusion of TCE and PCE in the risk assessment for the Malvern TCE Site,
since carcinogenic slope factors for these compounds have been withdrawn from the Integrated
Risk Information System (IRIS). Note, however, that rather than ignore potential risks posed by
Site-related contaminants, it is standard risk assessment practice to use toxicity values which
have been withdrawn from IRIS when no other values are available. The EPA National Center
for Environmental Assessment (NCEA) recommends the use of the withdrawn slope factors for
TCE and PCE as provisional values for risk assessment. Further, according to a June 8, 1993
memo from Cindy Sonich-Mullin (Director, Superfund Health Risk Technical Support Center,
Chemical Mixtures Assessment Branch) to Edward Hanlon (U.S. EPA, Region V) on Toxicity
Information for Trichloroethylene and Tetrachloroethylene (Fields Brook/OH), TCE and PCE
were removed from IRIS in 1989 due to uncertainties in the cancer weight-of-evidence
classification, not uncertainties in their carcinogenic slope factors. In addition, the World
Health. Organization has recently stated that TCE is probably carcinogenic to humans (LARC
Monographs, 1995).
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For the sake of perspective, it should be noted that TCE only contributes 16.4% of the
inhalation and 12.8% of the ingestion cancer risks associated with potable use of Former
Disposal Area ground-water, while at the Main Plant Area, TCE contributes 16.3% and 13.7% of
the inhalation and ingestion cancer risks, respectively. PCE contributes an even lower
percentage to the total risk associated with Former Disposal Area and Main Plant Area
grdundwater use. The primary contributor to carcinogenic risks via these exposure routes is
1,1-DCE. In fact, this compound alone poses an unacceptable cancer risk via either route of
exposure (inhalation or ingestion), and is sufficient for triggering an action at the Site.
ERM Section 2.4.LS, Evaluation of Other "Class Cn Carcinogens
ERM erroneously interprets EPA 's position on the evaluation of potential risks posed by possible
human carcinogens, stating that such compounds "have inadequate evidence to be classified as
carcinogens. " In truth, EPA guidance indicates that slope factors are typically calculated for
potential carcinogens in classes A, Bl andB2, and that estimation of slope factors for the
chemicals in class C proceeds on a case-by-case basis. Further, EPA risk assessment guidance
(USEPA, 1989) states that "slope factors for all potential carcinogens having a weight-of-
evidence classification of A, B, or C should be sought" (Page 7-7 6, Section 7.4.3). Since slope
factors are available for the class C carcinogens selected as COPCs in the Malvern TCE risk
assessment, potential cancer threats presented by these contaminants were quantitatively
evaluated in the risk assessment, as dictated by EPA guidance.
Further, EPA 's proposed carcinogenic risk assessment guidelines (April 1996) discuss
eliminating the use ofweight-of-evidence classifications. If finalized in its current form, all class
A, B and C carcinogens will be categorized into one group. Under this scheme, these
constituents would still be evaluated for carcinogenic risks.
ERM Section 2.4.2,2, Contaminants of Potential Concern
In ERM's re-evaluation of risk at the Malvern TCE site, several "metals " were removed from
consideration by "proper comparison " of concentrations to background levels, including
"benz(a)fluoranthene and benzo(a)pyrene ". Please note that neither benzo(a)fluoranthene nor
berao(a)pyrene are metals. Rather, these chemicals are semi-volatile organic compounds.
ERM Section 2.4.2,3, Reassessment of Site Risks
Completely dismissing all other contaminants at the Site, ERM calculated carcinogenic risks
related only to vinyl chloride exposure. (Vinyl chloride is the only class A carcinogen detected
at the Malvern TCE Site.) According to EPA risk assessment policy, it is improper to eliminate
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class B2 (or C) carcinogens from the calculation of carcinogenic risk, for reasons cited above.
EPA has conducted the Risk Assessment in accordance with good science, established science
and guidance, and with the important responsibility of protection of public health.
D. Comments of David DeWitt on behalf of the Concerned Residents of East Whiteland
Township (CREW)
In a seven-page letter dated August 20,1997, David DeWitt, President of CREW,
submitted comments and questions on behalf of the group about EPA's proposed alternatives to
cleanup the MaJvem Site.
1. CREW is interested in the Community-Based Remedy Selection Process, part of the
Superfund Administrative Reforms announced by Carol Browner, EPA Administrator, on
October 2,1995. CREW would like to be involved actively in all aspects of remedy
selection and implementation. EPA proposed alternatives could make the community
worse off than it is now if they are implemented. The alternatives should not put the
interests of Chemclene before the interests and concerns of the community.
EPA Response: The Community-Based Remedy Selection Process Administrative Reform
announced by Carol Browner is a pilot reform in which EPA, Region III did not
participate. However, EPA intends to work closely with CREW in the implementation of
the remedy to ensure the community's concerns are addressed during the Remedial
Design. EPA understands the concerns that CREW may have with respect to remedy
implementation but EPA is required by the NCP to protect public health in the selection
of a remedy.
2. All structures, treatment units, etc., such as SVE wells and groundwater treatment units,
should be located as far from residences as possible. Remedial activities and equipment
should not be visible from Phoenixville Pike or Aston Road. All remedial activities
should be carried out to minimize noise, dust, air emissions, odors, etc. in the area. Large
equipment should be located inside buildings to minimize aesthetic and noise issues.
EPA Response: EPA understands the concerns of CREW and is committed to working
with the community to address these concerns during the Remedial Design phase.
3. The developers of Aston Woods deeded the property bordered by Aston Road and
Phoenixville Pike to East Whiteland Township as recreational land for the benefit of
Aston Woods. This property should not be used for long-term remedial activities.
EPA Response: EPA understands the concerns of CREW but would like to reiterate that it
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may be necessary to use this property for long-term remedial activities. However, EPA is
committed to working with the community and will consider their concerns in the
Remedial Design phase.
4. EPA should place a RCRA cap over all areas where soil contamination is above relevant
clean-up criteria. A RCRA cap is the only containment alternative that will minimize
infiltration and prevent on-Site exposure during the O&M period and it is more protective
of human health and the environment. The final remedy in the ROD should be
contingent so that the parties carrying out the remedy have the option of implementing a
RCRA cap.
EPA Response: The Selected Remedy for the cap construction at the Main Plant Area is
performance based. This requires the cap to be constructed with the permeability
equivalent to that of a RCRA cap. The performance standards for implementation of the
cap are outlined on page 54 of the ROD.
5. EPA should eliminate the option of transporting contaminated soils from the Former
Disposal Area to the Main Plant Area because the movement could create uncontrolled
air emissions of the contaminants in the soil. These soils either should be capped near the
Former Disposal Area, but remote from homes, or transported off-Site. In addition, it is
unfair and technically unwarranted to transport contaminated soil to create a containment
cell 20- to 30-feet high directly behind homes.
EPA Response: EPA agrees that the contaminated soils at the Former Disposal Area
should be transported oflSitefor treatment and disposal, and has provided for this in the
Selected Remedy.
6. The SVE unit should treat off gases if detectable concentrations of site contaminants will
be present in the off gases. There should be no injection of air or other vapors as part of
the SVE since this may disturb subsurface air vapors unpredictably.
EPA Response: EPA has reconsidered the use of SVE at the Main Plant Area and has not
selected SVE in the ROD.
1. EPA did not establish the technical feasibility of SVE. EPA should conduct pilot testing
to ensure the technology is effective and appropriate. If SVE is implemented, the SVE
well shown in the FS on or near the property line should be moved to another location.
EPA Response: EPA had planned a Pilot Study to determine the effectiveness of SVE but
since it is not part of the Selected Remedy, EPA will not conduct a Pilot Study.
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8. JEPA has not given sufficient consideration to a natural attenuation groundwater remedy
at the Main Plant Area. A groundwater pump-and-treat system will create a disturbance
for the neighborhood and potentially can create an exposure pathway. EPA's scenario of
an industrial worker at the Site drinking the water is not sufficient justification to pump
and treat the groundwater since deed restrictions would eliminate this risk.
EPA Response: EPA disagrees. This comment is further addressed in Section C, #2 of
this Responsiveness Summary. However, EPA did select Natural Attenuation at the
Former Disposal Area.
9. If EPA implements a groundwater pump-and-treat system, the air stripper and all vapor-
phase treatments must be located inside a building. The building should be noise proof
and the system must have a noise arrester.
EPA Response: EPA understands the concerns of CREW and is committed to working
with the community to address these concerns during the Remedial Design phase.
10. The groundwater treatment system should be located in the area identified as the
proposed spray irrigation location. The system should not be located in close proximity
to homes or directly across from Great Valley High School. CREW believes it
impractical to have two separate groundwater treatment systems. If there is a treatment
system for the Main Plant Area groundwater, there should be one consolidated system for
the Main Plant Area and Former Disposal Area located away from homes. The inlet from
the Former Disposal Area can be shut off after five years.
EPA Response: EPA has made a modification to the Proposed Remedy and has selected
FDA-G-4, Natural Attenuation, for the Former Disposal Area groundwater. Therefore, it
wall not be necessary to construct a treatment system for the Former Disposal Area. EPA
understands CREW's concern regarding the construction of a treatment system in the
vicinity of the Main Plant and is committed to working with the community during the
Remedial Design phase to address these concerns.
11. CREW strongly objects to the spray irrigation option for treated groundwater since it is
likely to cause nuisance conditions from water spray drifting to homes, roads, etc.,
particularly in winter months when icing is a concern.
EPA Response: EPA has not selected Spray Irrigation for the discharge of treated
groundwater.
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12. EPA guidance states that treatment of DNAPLs is presumed to be technically infeasible
and EPA is entitled to receive a technical impracticability (TI) waiver unless written
justification to the contrary is provided. The proposed treatment will subject residences
to greater pumping and extraction volumes and the extraction, handling, packaging, and
transportation of listed hazardous wastes. CREW suggests selecting Alternative MPA-G-
5 (Ground Water Collection, Treatment, and Discharge), and pumping and extraction
rates should be determined based on a containment objective.
EPA Response EPA has considered this issue in Section C, #2 of this Responsiveness
Summary.
E. Comments of Fox, Rothschild, O'Brien & Frankel, LLP and Walter B.
Sattertbwaite Associates Inc. on behalf of the Malvern De Minimis PRP Group
In a 17-page letter dated September 2,1997, Fox, Rothschild, O'Brien & Frankel, LLP
and Walter B. Satterthwaite Associates Inc., on behalf of the Malvem De Minimis PRP Group,
submitted comments to EPA regarding the Proposed Plan.
1. The Malvem Site is a former RCRA facility and should be closed in accordance with
RCRA guidelines. The Proposed Plan did not address normal RCRA closure issues
which would eliminate any possible risk to human health for on-Site employees and
future residents. Tailoring the clean-up plan to allow Chemclene to continue operating
violates RCRA regulations.
EPA Response:
The Selected Remedy addresses the closure of the regulated units (i.e. quonset hut and
main building) that were never closed by Chemclene. Closure of the regulated units will
not address the risk posed by soil and ground-water and EPA has deferred the
remediation of the soil and groundwater to the Superfund program.
The remedy as established in the ROD will achieve all of the standards for closure under
RCRA, even though the closure is done as part of a CERCLA cleanup. However, closure
of a facility under RCRA does not require sealing off all access to the facility on which
the RCRA units were located. It is not inconsistent with RCRA to allow Chemclene's
continued use of the Site for activities which do not require a RCRA permit.
The commentor in effect argues that there will be less risk of exposure to Chemclene
workers if they are barred from the entire Site. Certainly there would be less theoretical
risk at any Superfund site if a huge fence were constructed and all access to the site was
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forever forbidden. However, the purpose ofCERCLA is to cleanup contaminated sites.
not merely to reduce risk by restricting access. The cleanup of a Superfund site is to be
designed, to the maximum extent practicable, to allow the continued or future use of the
site and its resources.
2. EPA has ignored Land Use Guidance by allowing Chemclene to continue operating and
in assuming residential use in the human health risk analysis. The guidance requires
discussion with local land use authorities and other locally affected parties, review of
anticipated future land use or uses, and zoning and analysis of site activities consistent
with possible future land use.
EPA Response: EPA has not ignored the Land Use Guidance and has consulted with East
Whiteland Township. The property is currently zoned residential and Chemclene
currently operates a lawful nonconforming commercial facility from the property. This
in effect means that the facility was in operation prior to the zoning and may continue to
operate as such. It is clear from the zoning that the local land use authorities anticipate
that the future land use could be a residential property.
3. EPA's policy is to defer facilities that may be eligible for inclusion in the Superfund
program to the RCRA program if the sites are subject to RCRA corrective action. There
are exceptions to this deferral, none of which are applicable in this situation. Chemclene
is obligated to comply with RCRA.
EPA Response; EPA agrees that Chemclene should comply with RCRA generally
speaking. The commentor argues that it is EPA policy to "defer facilities that may be
eligible for inclusion in the CERCLA program to the RCRA program if they are subject to
RCRA corrective action. " However, EPA's RCRA deferral policies deal with the deferral
of listing of a site on the NPL if it can be cleaned up under RCRA corrective action.
These policies were not in effect in 1983 when the Malvern TCESite was listed on the
NPL. Notwithstanding the 1983 listing of the Site on the NPL, EPA continued to pursue
cleanup of the Site under the RCRA corrective action regulations until 1993, when it
became clear that Chemclene was neither willing nor financially able (based upon
financial analysis at the time) to cleanup the Site expeditiously under RCRA.
EPA's RCRA deferral policies are designed with two goals in mind. One goal is to
preserve Superfund resources if a willing and able owner/operator is available to
cleanup a site under RCRA. A second goal is to preserve the procedural rights of owners
and operators to the extent that the owners/operators would prefer to continue work
under RCRA in lieu of a listing on the NPL Neither goal is at issue in the Malvern TCE
Site. The owner/operator does not appear to have sufficient resources to cleanup the
Site, and was unwilling to cooperate fully with the RCRA corrective action program.
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EPA has to date undertaken only Rl/FS activities at the Site, activities which are allowed
under EPA's RCRA deferral policies even if a Site has not been listed on the NPL.
Moreover, the proposed NPL listing was published in the Federal Register and both the
owner/operator and the public have had sufficient opportunity to challenge the listing. At
this time, 14 years after the Site was listed on the NPL, there are no procedural avenues
left to address in the listing process.
Furthermore, the RCRA deferral policies simply do not address or imply a right of
generators and other PRPs to demand that EPA use RCRA instead ofCERCLA to
cleanup the Site. One can easily see why the generator PRPs would prefer the cleanup to
proceed under RCRA: under RCRA EPA can order only the owner and operator to
conduct the cleanup, whereas generators also may be liable for a cleanup under
CERCLA. However, the RCRA deferral policy is not in any way addressed to the
generators 'preferences. If the generators believe that the owner/operator should be
responsible for the cleanup, the proper channel for such a claim is in a contribution suit
against the owner /operator. Having determined that an expeditious cleanup is not likely
to occur under RCRA, EPA's decision to utilize CERCLA is not subject to second-
guessing by the generator PRPs. There are still obligations under both laws. The
Agency retains discretion to decide which tools to use to accomplish the result.
4. The Malvem De Minimis PRP Group is extremely concerned about allowing Chemclene
to continue operating on the Site. EPA appears to be assisting Chemclene in its
continued operations by adjusting the selected remedy to allow Chemclene to stay in
business. In doing so, EPA is allowing the very party EPA contends aided, and in some
instances, caused the release of hazardous substances into the environment to operate on
the same land the company contaminated.
EPA Response: The commentor argues that an owner and operator who contributed to
the contamination at a Site must necessarily be put out of business, or at least not be
allowed to use any of the Site. However, absent extreme circumstances it has been EPA's
policy to avoid putting PRPs out of business as a result ofCERCLA liability. The
commentor is misinformed; what would be unprecedented would be for EPA to require
Chemclene to cease non-RCRA business activities merely because ofChemclene's
liability for contamination at the Site. EPA has selected a remedy that is protective of
human health and the environment which also allows continued use of the Site and its
resources.
5. EPA's preferred alternatives neither meet the goals of nor are consistent with the
management principles and expectations of the clean-up plan selection process described
in the NCP.
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EPA Response: EPA disagrees, and believes that both the Proposed Remedy and the
Selected Remedy are consistent with the NCP. See Section IX and X of the Selected
Remedy.
6. EPA's preferred alternatives likely will cause further migration of Site contaminants.
The FS did not adequately consider the effects that the installation of a public water
supply would have on human health. The FS failed to consider the fact that groundwater
extraction, treatment, and reinjection is not more effective in protecting human health and
the environment than natural attenuation.
EPA Response: Although EPA has reconsidered the extraction and treatment of
groundwater at the Former Disposal Area and has selected Natural Attenuation, EPA
disagrees with the conclusion that the preferred alternatives would cause further
migration of the Site contaminants. ERMand Walter B. Satterthwaite Associates, Inc.
(WBSA) both cited increasing VOC concentrations in time-related samples collected from
pumping wells during the aquifer tests at the Former Disposal Area (CC-16 and CC-17),
and Main Plant Area (CC-I9 and CC-21) as evidence that pump and treat technology
will contribute to plume migration at the Site. The increase in VOC concentrations from
these samples provides strong evidence that pumping wells at both the Main Plant Area
and Former Disposal Area should be successful in mobilizing and capturing
contamination in groundwater at extraction wells. Using industry-accepted analytical
modeling methods, the modeled pump and treat systems (pumping and injection wells) at
both the Main Plant Area and Former Disposal Area were configured to contain the
plume within the presently contaminated areas at the Site. These configurations were
tested (using modeling methods) to ensure contamination could not migrate outside the
cumulative capture zone for the system.
An evaluation of the effect of connecting residences to public water supplies for the Main
Plant Area and Former Disposal Area in the FS indicated that alternatives MPA-G-3 and
FDA-G-3, alone, were not protective of human health and the environment. Although
residents would no longer use groundwater from beneath the area for drinking, or other
domestic uses, contaminated groundwater could continue to migrate in the subsurface
and potentially impact future residences. In the area around the Site, groundwater from
the Ledger Aquifer is a source of high quality drinking water and in accordance with the
NCP should be restored to beneficial use. As recently as 1992, Philadelphia Suburban
Water Company withdrew water from this aquifer at a production well on Phoenixville
Pike to supply local residents. In addition. Great Valley High School operated a well in
the Ledger Aquifer to provide water for drinking and irrigation. Any alternative that
allows highly contaminated groundwater to remain in an aquifer that has historically
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been utilized as a drinking water supply cannot be considered protective of human health
find the environment.
Natural Attenuation cannot be considered protective of human health and the
environment at the Main Plant Area. With a natural attenuation alternative,
groundwater contaminated with elevated VOC's is allowed to remain in an aquifer that
has been historically used for drinking water supplies. In the best scenario, geochemical
conditions (anoxic to hypoxic environment with anaerobic bacteria) are favorable for the
destruction of CAH compounds to innocuous transformation products including water,
carbon dioxide and chloride. If these conditions are not optimal as at the Main Plant
Area, contaminants can persist in the groundwater indefinitely (in excess of 30 years).
Even if geochemical conditions are favorable for the degradation ofCAH's, some of the
less halogenated, dechlorinated transformation products (vinyl chloride) that form as
part of the natural attenuation process are considered more toxic than primary
compounds (TCE, PCE). Groundwater pump and treat affords controlling migration of
the contaminant plume and accomplishes removal of contaminant mass from the aquifer.
Although ultimate aquifer restoration may not occur across the entire plume,
contaminant mass is reduced and migration is limited to the property boundaries.
8. Soils in the vadose zone are characterized by highly heterogeneous, fine-grained soils.
These soils significantly limit the effectiveness of SVE, indicating that, at a minimum,
EPA should have conducted a treatability study to gauge adequately the technology's
effectiveness at the site.
EPA Response: EPA has reconsidered the use of SVE as a remedial alternative for soil
at the Main Plant Area. At the time of this decision, EPA has determined that the
installation of the cap at the Main Plant Area will provide necessary protection of
groundwater.
9. The distribution of substances detected in on-Site soils at the Main Plant Area is
characterized by limited and isolated pockets with only trace levels of chemical outside
these isolated hot spots. Therefore, EPA should evaluate alternatives which focus on the
isolated and relatively shallow hot spots, with institutional and/or engineering controls for
the remainder of on-Site soils which pose little or no long-term threat.
EPA Response: An evaluation at the Main Plant Area indicated that soil contamination
as characterized by soil samples (contamination sorbed to soil particles) and vapor
readings (soil gas) indicated that contamination occurred in three primary areas of
concern (former underground storage tanks, aboveground storage tanks, and distillate
condensate disposal area). Seventeen of the 42 subsurface samples analyzed at the Main
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Plant Area exhibited concentrations elevated above Site specific Soil Screening Levels
(SSLs). EPA disagrees that contamination is relatively shallow, contamination in the
vadose zone in all three areas extended to depths as great as J 00 feet. Beneath each of
these areas, concentrations and PID measurements were sufficiently elevated to suggest
the presence ofDNAPL, although DNAPL was never encountered in soil samples. EPA
has, however, determined that engineering controls such as soil capping should provide
adequate protection ofgroundwater, along with pump and treat.
10. The NCP states that, when groundwater restoration is not practical, EPA should ensure
other protection to prevent the further migration of contaminants, prevent exposure to
contaminated groundwater, and evaluate the need for further risk reduction. Data for the
site indicates that this should be done. The proposed groundwater extraction alternative
is likely to create additional contaminant migration beyond that which would occur
naturally. The combination of hydrogeologic barriers and natural attenuation has
prevented the plume from migrating. Therefore, groundwater extraction and treatment
are not necessary or appropriate.
EPA Response: EPA agrees that groundwater pump and treat is not necessary at the
Former Disposal Area and has reconsidered the implementation of this technology at the
Former Disposal Area. Historical contaminant concentrations from groundwater
samples have been declining since 1990 after removal of drums and contaminated soil at
the Mounded Area. In addition, the presence of significantly elevated concentrations of
transformation products ofTCE, PCE, and 1,1,1-TCA indicates that the natural
attenuation processes are relatively advanced. In most of the monitor wells,
concentrations of degradation products is equal to of greater than concentrations of
primary CAH's.
However, EPA believes pump and treat technology is necessary and appropriate at the
Main Plant Area. EPA believes that the extent ofgroundwater contamination at the
Main Plant Area may not be fully defined. In addition, an evaluation ofCAH
concentrations indicates the process is not as advanced as it is at the Former Disposal
Area. Total VOC concentrations in individual monitor wells have been stable since
1990. In addition, at many wells concentrations of less chlorinated transformation
products are several times less than concentrations of primary CAH's. CAH
concentrations in groundwater appear to be in equilibrium with a source in the vadose
zone. Modeling simulations conducted using site-specific half-lives indicate that TCE is
the most persistent CAH at the Main Plant Area and would require greater than 35 years
to degrade below the MCL of 5 ug/l. A major assumption inherent to the degradation
model equations is that contamination is in the aqueous phase and there is no DNAPL
source replenishing degrading contaminants.
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The use of pump and treat technology in the source area at the Main Plant Area is
intended to reduce contaminant mass and prevent further migration from the Chemclene
property. Time-related groundwater samples collected during the 24-hour aquifer tests
at CC-19 and CC-2J indicate that extraction wells would be successful in mobilizing and
collecting contaminants. Although, results ofDNAPL screening utilizing several
analytical techniques indicate that DNAPL may be present in the vicinity ofCC-6, CC-7,
and CC-13, visual evidence ofDNAPL has never been encountered at the Site. The
response to the pump and treat system in the suspected DNAPL area will be evaluated
during the operation of the system. If it is determined through performance monitoring
that it is impracticable to reach the cleanup standards, these standards will be changed
in the DNAPL area.
11. During sampling conducted by EPA in May 1996, EPA found contaminant levels
increased over a 24-hour period. The data indicates that pumping to obtain the samples
caused significantly more plume migration in 24 hours than had occurred naturally in
more than 15 years. This field test data indicates that the proposed alternative may
actually be detrimental to human health and the environment.
EPA Response: EPA disagrees and believes the data shows otherwise. Many aspects of
this comment have been addressed above
12. The regional potentiometric surface map indicates that the elevation of the water surface
surrounding the discontinuous plume is at an identical or higher elevation than the water
surface at the Former Disposal Area. This area lies to the west of the flow path from the
Former Disposal Area and another off-site source of contamination likely contributes to
this condition. In addition, domestic well D-58, located in the center of the domestic well
plume, contains no 1,1,1 -trichloroethane (1,1,1 -TCA) or 1,2-dichloroethane (1,2-DC A)
two primary contaminants found in the plume at the Former Disposal Area in well CC-5.
EPA Response: This comment was already addressed in Section C, #/ above.
13. EPA calculated the rates of natural degradation at both the Main Plant Area and Former
Disposal Area using half-lives calculated from historical site data for TCE and 1,1,1-
TCA. Since the half-life values for these chemicals were based on actual site data, the
degradation rates EPA calculated assume no source treatment. EPA did not consider, in
either the FS or the Proposed Plan, the impacts of natural attenuation or marginal
improvements in time to achieve Maximum Contaminant Levels (MCLs) under the
proposed alternative.
EPA Response- The time of attenuation for TCE and 1,1,1-TCA reported in the Rl
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Report are based on the assumption that all contaminant mass is in the aqueous phase
(assumption I., page 5-39), and that there is no source (analytical equations in Table 5-
3) to replace degrading CAH's. This evaluation essentially assumes that the source of
contamination has been removed from each site. To maintain the conservativeness of the
evaluation, CAH concentrations from the most contaminated wells were modeled for both
sites (CC-5, Former Disposal Area; CC-7, Main Plant Area). In evaluating the present
conditions at the site, these analyses are more valid for the Former Disposal Area than
the Main Plant Area, where soils in the vadose zone appear to continue leaching
contaminants to the groundwater. The intention of these analyses were to illustrate CAH
degradation with time, under existing site conditions in the absence of a contaminant
source.
WBSA 's contention that remedial alternatives for groundwater (FDA-G-6, MPA-G-6) at
the Former Disposal Area and Main Plant Area provide only marginal improvements in
time to achieve MCL's is not valid. Evaluation of alternative FDA-G-6 indicates that
with a combination of pumping at a single extraction well at 500 gpmfor two years and
natural attenuation all CAH's should degrade below their respective MCL's in 7years
from the beginning of remediation. Time of remediation using FDA-G-6 is significantly
more rapid than for natural attenuation (FDA-G-4) which requires 16.5 years to achieve
MCL's. Comparison of improvements for the time of remediation at the Main Plant Area
between Alternatives MPA-G-4 and MPA-G-6 if all contamination in groundwater is in
the aqueous phase. With dissolved phase contamination, concentrations should decline
below MCL's in 19.5years using alternative MPA-G-6. Assuming the source of
contamination in the vadose zone is removed, contaminant concentrations should decline
below MCL's in 35 years. However, a comparison of true improvements between
alternatives is not valid ifDNAPL is present. With DNAPL, pumping will continue for 30
years to reduce contaminant mass and prevent offSite migration. In the presence of
DNAPL, natural attenuation will require significantly longer than 35 years to degrade
below MCLs dependent on the strength of the source concentration.
14. Assuming public water is made available, which would reduce the risk of exposure to
groundwater to zero, institutional controls preventing construction activities on the site
would eliminate current and future risks.
EPA Response: Although the current risk of exposure to groundwater can be eliminated
by connecting residents at both areas of concern to public water, this measure does not
address leaving elevated concentrations of CAH's in the Ledger Aquifer. The Ledger
Aquifer has been a historical source of high quality water supplies for residents in the
area around the Malvern TCE area.
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15. EPA rejected all technologies involving the excavation and ex-situ treatment of
contaminated soil at the Main Plant Area because, in the FS, EPA determined that the
contamination was too deep to be removed. EPA's conclusion was faulty because: (1)
only two samples contained concentrations high enough to be considered a potential
source of future groundwater degradation and (2) if the objective was to eliminate
exposure of future construction workers, the depth of the soils posing a risk to these
future workers certainly is not too deep to be excavated.
EPA Response: EPA disagrees and believes the facts show otherwise. WBSA 's comments
that only two subsurface soil samples collected at the Main Plant Area contained
concentrations sufficiently high to be considered a potential source of contamination to
groundwater is incorrect. Of the 42 subsurface soil samples (collectedfrom 12 borings)
submitted for laboratory analysis, 17 exhibited concentrations of one or more compounds
in excess of the site specific SSL's (FS Appendix B, Table B~4). Nine of the seventeen
samples were collected at depths greater than 40 feet below grade. As the objective of
excavation is to remove all contaminated soils with concentrations greater than SSL's
rather than selected easy-to-access areas, excavation of contaminated soil at the Main
Plant Area was not considered practicable.
16. A significant concern for S VE at the Main Plant Area is heterogeneity of the subsurface
soil, which could result in pockets of soil contamination that cannot be treated with S VE..
The factors that caused EPA to reject soil flushing as a possible clean-up option would be
just as detrimental to in-situ SVE. Therefore, consistent with the NCP, EPA should
conduct a pilot scale treatability study. Therefore, EPA either should have rejected SVE
or should not have rejected soil flushing during the preliminary screening process.
EPA Response: EPA has reconsidered implementation of an SVE alternative at the Main
Plant Area. EPA believes that capping alone provides an equivalent level of
protectiveness and long term effectiveness as SVE while being more cost effective. Prior
to this decision a pilot study was planned for mid September that included a vacuum
extraction well and four observation clusters. Although the alternative has been
reconsidered, remediation with SVE could be effective at the Main Plant Area even in the
presence of heterogeneous soils. The thick (around 70 feet) vadose zone at the Main
Plant Area has been characterized by 12 borings. An additional five borings with
continuous sampling would have been added for the pilot study.
Geologic interpretation of the vadose zone indicates that there are thick, partly
continuous zones of well sorted sands (RJ Figures 3-3, 3-4, 3-5, 5-1 and 5-2) interbedded
with silt and clay. Soil contamination as characterized by analytical results from soil
samples and PID measurements indicates that contaminants occur in all lithology types
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at the Main Plant Area. Typically contamination in finer grained soils is found adjacent
to a more permeable sand unit (Figures 4-3, 4-4, and 4-5). Contaminant distribution
patterns in horizontal lithologic sections (RI Figures 5-1 and 5-2) indicate that
contamination appears to have migrated through permeable units and collected at the
interfaces marked by a lithologic change. By careful spacing of vapor extraction wells,
airflow in the subsurface could be optimized to remediate contaminated soils in the
highly permeable units and contaminant accumulations in proximal fine-grained soils.
Soil flushing was not considered equivalent to SVE in its ability to remediate soils at the
Main Plant Area during the FSprocess because air is a significantly more effective
carrier in the vadose zone than water (Fam, 1996). With SVE, airflow in the vadose
could be more easily controlled than the flushing. Careful design of the SVE extraction
well placement and screen intervals could take advantage of the heterogeneity at the
Main Plant Area to develop an effective SVE system.
17. EPA should use caution when selecting gradient-control utilizing extraction wells to
minimize DNAPL migration in groundwater. This is important particularly in the
heterogeneous fractured carbonate aquifer where the direction of groundwater flow within
individual water bearing units and the consequences of artificial gradient manipulation
are impossible to predict. Using this technology likely would cause an increase in the
mobility of contaminants which currently are contained by natural conditions.
EPA Response: Alternative MPA-G-6, using pump and treat technology to remove
contaminants at the source area and downgradient areas of the plume at the Main Plant
Area was designed to collect groundwater contaminants and prevent further
downgradient migration. The mobilization of contaminants toward points of lower
potentiometric head at extraction wells is not a valid argument for rejection of pump and
treat technology. Mobilization of contaminants toward extraction wells as indicated by
time-related sampling during pumping tests at the Main Plant Area and Former Disposal
Area is the fundamental purpose of pump and treat technology. The system element of
greatest concern in regard to migrating contamination is the injection well system, which
could potentially drive contaminants away from the site. However, contaminants in the
source area should not be affected by injection in downgradient areas of the site
18. While EPA stressed that caution should be used to prevent DNAPL migration when
evaluating containment, EPA did not consider this when evaluating collection and
treatment, even though they are similar technologies in terms of the groundwater
pumping process. Collection and treatment has been shown to cause contaminant
migration within and between water bearing units in the aquifer, therefore EPA should
reject it since it violates one of the RAOs.
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EPA Response: See Response to E. 17.
9
19. EPA did not consider innovative technologies to address groundwater contamination at
the Main Plant Area, as stipulated in the NCR.
EPA Response: The hydrogeologic setting at the MPA, a fractured bedrock aquifer, is not
compatible with a number of the new insitu, innovative technologies for groundwater
remediation. As an example, WBSA recommendation for the use of an insitu reactor or
reactor wall at the Main Plant Area is not feasible because there is no practical method
for installing the reactive wall in the bedrock aquifer overlain by 40 to 100 feet of
unconsolidated overburden. Injection of granular reactive iron through injection wells
results in accumulation of this material in the bottom of the injection wells with no
dissemination into the aquifer. New semi-passive well technologies (Wilson, et.al, 1997)
utilizing reactive materials have not been implemented on actual Sites and have not been
tested in bedrock environments. Most of these technologies were rejected before
preliminary screening because they are not compatible with the hydrogeologic
environment at the Site. This approach was selected rather than developing a long list of
technologies that are quickly rejected in the screening task
20. EPA incorrectly evaluated soils at the Former Disposal Area by inadequately reviewing
gradient control and groundwater collection.
EPA Response: Comment E.20, derived from WBSA's comment 7, was somewhat
confusing in relating gradient control and groundwater collection to the evaluation of
soils remediation at the Former Disposal Area. The main intention of the comment
appears to have been that gradient control at the Former Disposal Area was retained
during the screening process (FS; Table 3-5), but considered impracticable because of
high transmissivity in the Ledger Aquifer, -while groundwater extraction was retained
without mention of limitations. WBSA's cites this relationship as an inconsistency in the
FS. Analytical flow and numerical transport modeling (FS; Appendix D) demonstrated
thai contaminants could be collected at relatively high flow rates with one to four
extraction wells. However, gradient control and drawing the downgradient portion of
the plume back toward the Former Disposal Area required even more elevated pumping
rates from additional wells. As part of the single pumping'well collection alternative (
FDA-G-6; Appendix D), modeling indicated that a large portion of the contaminant
plume would decouple from the Site and continue migrating downgradient, where it
would naturally attenuate.
21. EPA stated that the effectiveness of S VE depends on the soil matrix, grain size, and
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moisture. However, the two areas with the highest contaminant concentrations at the
Main Plant Area contain soils comprised of moist to wet silt and poorly graded sand with
silt and clay. These soils types would inhibit SVE's effectiveness.
•
EPA Response: WBSA 's comment regarding the moisture content of soils at the Main
Plant Area and SVE effectiveness is noted as a concern for SVE. At present. EPA has
reconsidered implementation of an SVE alternative (MPA-S-4) at the Main Plant Area.
Alternative MPA-S-4 was, however, rejected because of concerns with the variable
moisture content of subsurface soils. Moisture content of soils at the Main Plant Area
varied across the potential area for SVE treatment. As an example, thick beds of well
sorted sands encountered beneath the distillate condensate area were dry and friable. An
SVE pilot study was planned for the Site to help understand the effects of heterogeneities
in lithology and moisture content. However, it is no longer necessary because an
alternative remedy was chosen.
22. EPA concluded that pneumatic fracturing and thermal enhancements may increase the
effectiveness of SVE if the future pilot study indicates that SVE is not effective.
However, pneumatic fracturing will not provide significant benefits since it is best suited
to brittle clays with low plasticity, conditions not present at the Site.
EPA Response^ WBSA's comment regarding the feasibility of pneumatic fracturing at the
Main Plant Area is noted; however, SVE is not currently planned for use at the Site.
23. The preliminary design for the SVE system assumes five extraction wells averaging SO
feet deep to capture contaminants over an area approximately 60 feet by 60 feet. This
assumption is inconsistent with soil data collected during the RJ.
EPA Response At this time, EPA has reconsidered implementation of the SVE
alternative at the Main Plant Area. However, contrary to WBSA's comment that the
evaluation of soil lithology in FS Section 4.3.1.4 was incorrect, data show that thick beds
of dry, well sorted sands underlie the potential area of treatment at the Main Plant Area
(Figures 3-3, 3-4,and 3-5) as stated in the FS. This lithology was also described in the
preliminary screening (FS Section 3.3.1.4). Subsequently, it is difficult to identify
inconsistency in the FS regarding the description subsurface soils.
24. In terms of cost, EPA did not consider the possible need to alter the design of the SVE
system, nor did EPA consider, the cost of implementing another alternative if the SVE
alternative does not work. In addition, Site data do not support the general conclusion
that Site-wide treatment of soils is necessary.
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EPA Response: WBSA 's comment regarding cost analysis of alterations to SVE design or
contingencies if SVE is not successful is noted. The actual design of the SVE system was
to be based on the results of a comprehensive pilot study. Many of the design criteria for
the system were to be developed from the pilot study. Subsequently, assumptions made
for costing the FS might have changed.
25. EPA did not consider the combination of natural attenuation and public water adequately.
EPA stated that the public water alternative would not provide for any reduction in the
mobility of the groundwater plume. However, abandoning the existing wells will
eliminate pathways for contaminant migration among individual water-bearing fractures
in the residential wells. In addition, eliminating residential pumping will reduce the rate
of future contaminant migration.
EPA Response: At present, EPA has reconsidered implementation of the groundwater
pump and treat system at the Former Disposal Area (FDA-G-6). However, the
discussion of public "water supply and natural attenuation in the FS (Sections 4.3.4.3 and
4.3.4.5) was correct in stating that neither alternative was protective of human health
and the environment. Although abandonment of local residential wells will prevent
current exposure to contaminated groundwater, Alternatives FDA-G-3a and G-4, allow
elevated concentrations ofCAHs to remain in an aquifer that has been traditionally used
as a source for high quality public drinking water supplies. The NCP considers
groundwater a public asset that should be evaluated for restoration to beneficial use.
With Alternatives FDA-G-3a andFDA-G-4, groundwater cannot be used public
consumption until natural attenuation meets health-based goals ofMCLs.
26. Without any remedial measures having taken place, the contaminant plume has migrated
less than 150 feet. For dissolved-phase VOCs in a highly transmissive fractured
carbonate bedrock aquifer, this is an extremely rare occurrence. This clearly
demonstrates that natural attenuation processes are effective in controlling contaminant
migration in groundwater at the Main Plant Area. Because natural attenuation has been
proven to demobilize VOCs in groundwater and cause a reduction in the volume and
toxicity of the contaminant plume, natural attenuation satisfies several of the RAOs for
groundwater at the Main Plant Area.
EPA Response: EPA does not believe the full extent of the VOC contaminant plume in
groundwater at the Main Plant Area has been fully characterized. The RI report
documented groundwater flow from the Site to the northeast. The monitoring wells
located off the Chemclene property are located east of the Site. The evidence suggests
that the low VOC concentrations seen in these monitoring wells may be due to lateral
dispersion, not natural attenuation, and the longitudinal axis of the VOC plume may be
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oriented to the northeast. The extent of contamination in this direction will be
determined during the remedial design phase.
The mechanism and nature of CAH degradation in groundwater at the Main Plant Area
is uncertain. Groundwater beneath the Main Plant Area is oxic (dissolved oxygen > 2.0
mg/L), and subsequently not compatible "with the dechlorination and dehalogenation of
CAHs by biodegradation. Degradation of CAH's is typically associated with anaerobic
bacteria in an hypoxic to anoxic environment (Barbee, 1994). An evaluation of the
concentrations of primary CAHs (TCE, PCE, 1,1,1-TCA) in relation to dechlorinated
transformation products (cis 1,2-DCE, vinyl chloride, 1,1-DCE, etc.) suggests that the
progress of degradation is not advanced. Furthermore, the constituent ratios of
transformation products to primary products are not increasing with time as expected at
a Site where contaminant concentrations and migration is controlled by natural
attenuation. An evaluation of concentration ratios conducted along the centerline of the
plume using dot a from May 1996 indicates that ratios of transformation products to
primary CAHs remain stable with distance from the contaminant source area (Rl Figure
5-9). These concentration relationships would suggest that whole scale natural
attenuation is not occurring in groundwater at the Main Plant Area.
27. Using the proposed groundwater collection, treatment, and discharge system, EPA
estimated that, assuming source control or removal, the contaminant plume will be
remediated below MCLs in 19.5 to 32.5 years, depending on the success of the
hydrofracturing. This assumption is incorrect for three reason: (1) available data indicate
that pumping caused a significant migration of the plume; (2) hydrofracturing may cause
contaminants to migrate into new water-bearing units not previously intercepted and
could alter the hydrogeologic characteristics naturally containing the plume; and (3) the
time frame estimate for remediation is based on the unrealistic assumption that DNAPLs
are not present.
EPA Response: EPA disagrees and believes that the facts demonstrate otherwise. This
response is based on WBSA 's previous comment that contains three reasons that
assumptions for estimating time of remediation for alternative MPA-G-5 were flawed.
On the contrary, estimates of the time of remediation for the contaminant plume at the
Main Plant Area were correct based on the assumption that contaminants were in the
dissolved phase. In direct contradiction to WBSA's previous comment, the FS (Section
4.3.2.5) clearly states that additional pumping time would be required for a DNAPL
source below the water table.
As stated in earlier responses, mobilization of contaminants toward pumping wells as
demonstrated during the 24-hour pumping tests, is not a indication that implementation
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of pump and treat technology causes additional migration of the contaminant plume. As
indicated in the RJ, time-related sampling results from the pumping tests indicate thai
' contaminants can be mobilized and captured at extraction wells. Hydraulic fracturing at
the Main Plant Area is intended to increase extraction well performance (specific
capacity, yield, efficiency, etc.) by propagating fractures into the rock matrix and limit
the influence of diffusion on remediation. Increasing fracture aperture and propagating
fractures into the rock benefits the performance of an individual extraction well and
ultimately the entire extraction well system. Subsurface investigations at the Main Plant
Area to date have not indicated that the Ledger Aquifer is separated into discrete aquifer
zones whose integrity would be compromised by the propagation of fractures.
28. Public water combined with natural attenuation is the only appropriate remedy. Natural
attenuation ensures that no further migration of the contaminant plume will occur.
EPA Response: EPA disagrees and believes the NCP suggests a different answer.
Comment £26 addresses concerns about using only public water supply (WS-G-3a) and
natural attenuation (MPA-G-4) for the remediation ofgroundwater at the Main Plant
Area. EPA has reconsidered the implementation of a pump and treat alternative (FDA-
G-6) at the Former Disposal Area and will rely on public water supply and natural
attenuation for remediation of the contaminant plume at the Former Disposal Area.
Importantly, EPA has concluded that both these choices satisfy the key goal of protection
of public health.
29. EPA assumed that the cap at the Former Disposal Area will be effective in eliminating
the risk of direct contact with soils, but if the cap is damaged, a plume of contaminated
groundwater caused by leaching could be reactivated. This assumption is incorrect
because, since the early 1980s, natural attenuation has resulted in the contraction of the
contaminant plume.
EPA Response: The intent of this comment is noted. However, a break in a cap at (he
Former Disposal Area could result in a relative increase in contaminant concentrations
in groundwater. Based on evaluations of historical analytical data, increasing
concentrations due to loss of cap integrity should cause only a brief increase in
concentrations above levels at the time of the break.
30. Not only has the groundwater plume at the Former Disposal Area been contained, but it
has been contracting for several years. Therefore, natural attenuation provides a higher
degree of short-term effectiveness. Since there appear to be no DNAPLs present at the
Former Disposal Area, the length of time required to achieve MCLs in the Former
Disposal Area plume likely will be significantly shorter than at the MPA. Since the
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contaminated soil area at the Former Disposal Area has not had an adverse impact on
water quality, vadose zone source removal or control is not critical. Eliminating the risks
associated with direct contact with soils, combined with public water and natural
attenuation, could be a cost effective combination of alternatives that meet the RAOs and
ARARs for soils and groundwater at the Former Disposal Area.
EPA Response: EPA has reconsidered implementation of groundwater extraction and
treatment remedial alternative (FDA-G-6) at the Former Disposal Area and has decided
to choose natural attenuation. An evaluation of historical analytical data at the Former
Disposal Area indicates that the rate of decline in constituent concentrations has
decreased over the last two sampling events (May and December 1996). A portion of this
trend is shown in Figure 5-5 of the Rl Report, where total concentrations of 1,1,1-TCA,
TCE, andPCE were close to historical maxima in monitor wells CC-5 and CC-JO. The
decrease in the rate of CAH degradation may indicate that contaminants in groundwater
are reaching equilibrium with residual contamination in the vadose zone. If time-related
concentrations in groundwater reach steady state, the ultimate time of attenuation may
increase. Estimates of time of attenuation performed during preparation of the Rl Report
were based on Site-specific degradation rate constants calculated during a period of
plume recession. If concentrations become stable with time, rate constants will become
smaller, and the original estimates for duration of attenuation will have been
underestimated.
Remediation of soil in the vadose zone at the Former Disposal Area will help enhance the
natural attenuation process. Removal of residual contamination should result in another
episode of plume recession and ultimately the degradation of contaminant concentrations
below MCL's.
F. Comments of the National Park Service division of the United States Department of
the Interior
In an undated two-page letter, E. Scott Kalbach, Acting Superintendent of Valley Forge
National Historical Park, submitted comments on behalf of the Valley Forge National Historical
Park, part of the National Park Service division of the U.S. Department of the Interior. Mr.
Kalbach submitted comments to EPA regarding the Proposed Plan for the Malvem TCE Site.
1. Chemicals and metals from the Malvem Site have the potential to contaminate surface
water draining into Valley Creek. The Proposed Plan does not include any mitigating
actions for Valley Creek, which is an Exceptional Value waterway and a Class A Wild
Trout Stream.
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EPA Response: Based on the results of the Rl. EPA has concluded that the contaminants
of concern at the Malvern Site are generally VOCs and in one area, low levels ofPCBs.
EPA has sampled surface water closest to the source areas on the Chemclene property
and in Valley Creek and has concluded that contaminants from the surface water at the
Site have not impacted Valley Creek Additionally, VOCs are not detected by the time
groundwater from the Site discharges to Valley Creek. However, as part of the Selected
Remedy, the groundwater contaminant plume in the vicinity of the Former Disposal Area
will be monitored to ensure that Valley Creek is not impacted in the future.
2. Collection of baseline data may be necessary to develop standards for measuring changes
over time in both water chemistry and the aquatic biological community.
EPA Response: During the ecological field evaluation the benthic community directly
found on the Site, in the area of highest contamination, was not found to be impaired. In
fact, the benthic community was found to be productive and healthy. In addition, toxicity
tests conducted with benthic organisms indicated no adverse effects in any sediment
samples collected from the Site in the area of highest contamination. Therefore, there is
no indication or justification for evaluating other areas which are likely to be less
contaminated and for which we can make no causal link to the Site as the source.
3. EPA's failure to address Valley Creek in the Proposed Plan is the result of a deficient
Ecological Risk Assessment in the RI Report. EPA investigators visited the MaJvem Site
to test Valley Creek on June 20,1995, a day when there was no water in the creek.
Therefore, investigators took no samples of water, sediments, or microorganisms.
EPA Response: Valley Creek was sampled in the Ecological Risk Assessment and was
found to have TCE concentrations just above detection limits. The Ecological Risk
Assessment utilizes a gradient approach to sampling. By gradient, samples are collected
which represent a range of concentrations known (by literature review) to potentially
cause adverse effects. Since Valley Creek was just above non-detection, it did not
represent a potential issue in the Ecological Risk Assessment and other sampling
locations with elevated concentrations of Site contaminants were evaluated intensely.
The theory here, is that the concentrations which cause adverse effects are identified.
Near non-detect values did not result in adverse effects, thus Valley Creek was not at
risk.
4. A more complete biological survey would have revealed that a few years ago a bog turtle,
proposed for federal listing as a threatened species, was discovered in this wetland and
the a state-listed endangered plant, the possum haw was found on a nearby hillside.
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EPA Response: This was an oversight in the biological survey. However, this wetland is
not located at the Site and incomplete exposure pathways appear to be associated with
both of these species.
6. EPA did not consider the possibility that the cone of depression from dewatehng at
Catanach Quarry may interfere with the contamination plume from the MaJvern Site.
Although Catanach Quarry currently discharges into a sinkhole, the Quarry may request
permission from PADEP to discharge to Valley Creek after Warner Quarry closes.
EPA Response: EPA is aware of the cone of depression from the Catanach Quarry and
discusses this in the RJand the ROD.
7. Two other Superfund Sites exist in the Valley Creek watershed: Foote Mineral and Paoli
Rail Yard. In addition, Knickerbocker Landfill, now closed due to illegal hazardous
waste dumping, is located nearby. EPA did not consider the combined effects of these
Sites on Valley Creek as part of the environmental risk assessment of the Malvem Site.
EPA Response: The purpose of the Ecological Risk Assessment was to evaluate potential
ecological impacts of the Malvern TCE Site. Ecological Risk Assessments are Site
specific and are developed for all Superfund Sites. As stated above in response #1, EPA
believes that the data show that the Valley Creek has not been impacted by the Malvern
TCE Site. Therefore, the combined impacts of Malvern TCE with other sites in the area
is beyond the scope of the Superfund program.
G. Comments of a North Phoenixville Pike Couple
In a one-page letter dated August 27,1997, a couple living on North Phoenixville Pike
submitted comments regarding the Proposed Plan to cleanup the Malvern Site.
1. Although EPA stated that the connection of residences to the public water supply is, at
this stage, a proposed alternative, there are stakes on residential properties for the purpose
of installing the water lines. It seems that the decision to provide public water already
has been made. In addition, the layout of the water lines does not coincide with the
property lines.
EPA Response: The current construction activity is being conducted exclusively by the
Philadelphia Suburban Water Company and is independent of EPA's Selected Remedy.
2. Although the couple agrees with EPA's decision to provide public water to residents with
contaminated wells, the couple believes that the public water supply currently is more
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contaminated than their well. As a precaution against possible contamination, this couple
installed and has maintained a carbon filter on their well since 1980, at their own
expense. This couple does not wish to be connected to the public water supply.
EPA Response: EPA has selected the provision of a public water supply for the homes
impacted or potentially impacted by the Site. Groundwater use for human consumption
is prohibited once the public water supply is implemented. EPA beleives the public water
supply is more protective and reliable than the continued use of home wells.
3. This couple will not decommission their well. Their 19-acre property is protected by Act
319 (Clean and Green Program) and supports young Christmas trees, fruit trees, soft
fruits, asparagus, and vegetables. The couple wishes to keep their well for agricultural
purposes.
EPA Response: The remedy prohibits use of groundwater for human consumption. In
addition, any future groundwater use should not interfere with EPA's selected remedy.
From EPA 's perspective groundwater use for irrigation purposes that does not interfere
with the migration of contamination from the Former Disposal Area or the Main Plant
Area would be acceptable. However, there are state and county regulations which may
prohibit such use. This issue will be addressed during remedial design.
4. The property located at 218 Phoenixville Pike currently is vacant. Although the house
that formerly occupied the property was torn down, the well (formerly on a filter) and
electric utilities remain. If a public water main is brought down Phoenixville Pike, the
property at 218 Phoenixville Pike should be connected because the possibility for future
occupancy remains.
EPA Response: Connections to the public water supply will only be made for current
residences.
H. Comments of the Pennsylvania Environmental Defense Foundation
In a one-page letter dated August 25,1997, Chuck Marshall Chair of the Pennsylvania
Environmental Defense Foundation, submitted comments regarding the Proposed Plan to cleanup
the Malvem Site.
1. The Pennsylvania Environmental Defense Foundation supports EPA's preferred
alternative. OffSite Excavation and Treatment appears more costly while only marginally
more effective than the preferred alternative. Anything other than soil vapor extraction,
capping, and pump-and-treat does not appear to reduce the plume and the contamination.
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EPA Response: EPA has made modifications to Proposed Remedy in the final Selected
'Remedy which EPA believes provides an equivalent level ofprotectiveness and cost
effectiveness.
2. EPA does not appear to have evaluated the impact of the injection and withdrawal wells
on Valley Creek. EPA should ensure that neither surface water runoff nor groundwater
flow impact the creek.
EPA Response: The Selected Remedy for the groundwater at the Former Disposal Area is
Natural Attenuation. Therefore, there is no impact to Valley Creek from a pump and
treat system. EPA has responded above in F. 1 regarding any impact to Valley Creek
from the Site contamination.
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