U.S. EPA Superfund Program
Proposed Plan for Record of Decision Amendment
AIW Frank/Mid-County Mustang Site Operable Unit 1 (OU-1)
Exton, Pennsylvania
June 2016
INTRODUCTION TO Till SITE AND
STATEMENT OF PURPOSE
The U.S. Environmental Protection Agency
(EPA) is issuing this Proposed Plan to present
a modification to the groundwater cleanup
remedy at Operable Unit One (OU-1) of the
AIW Frank/Mid-County Mustang Superfund
Site in West Whiteland, Chester County,
Pennsylvania (the Site). The OU-1
groundwater remedy selected in EPA's
September 29, 1995 Record of Decision
(ROD) included groundwater extraction and
treatment, as well as institutional controls.1
The modifications to the groundwater remedy presented in this proposed plan include:
1. The use of in situ chemical oxidation (ISCO) and bioremediation as cleanup
technologies at the Site;
2. The addition of 1,4-dioxane to the list of Site contaminants of concern (COCs);
3. The removal of arsenic and manganese from the list of Site COCs;
4. An update to the preliminary remediation goals (PRG) for 1,1-dichloroethane and
chloroform; and,
5. The addition of Safe Drinking Water Act (SDWA) Underground Injection Control
(UIC) regulations, Pennsylvania Act 2 cleanup standards, and EPA's May 2014
Guidance for Evaluating Completion of Groundwater Restoration Remedial
Action to the list of Applicable or Relevant and Appropriate Requirements
(ARARs) and other advisories, criteria, or guidance to be considered (TBCs) in
the development and implementation of the selected remedy.
The Site is located approximately one mile east of Exton on Lincoln Highway, U.S.
Business Route 30, in West Whiteland Township, Chester County, Pennsylvania. The
location of the Site is shown in Figure 1 and the Site layout is depicted on Figure 2. The
National Superfund Database Identification Number is PAD004351003. EPA is the lead
1 The 1995 ROD for the Site did not refer to OUs. Since then, EPA has divided the remedial design and
remedial action of the selected remedy into three individual OUs (OU-1, OU-2, and OU-3). The OUs are
explained in greater detail within this Proposed Plan.
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Dates to Remember
June 1, 2016 to
June 30, 2016
Public Comment Period on
EPA's Proposed Plan
Public Meeting
June 14,2016
6:30 to 8:30 pm
West Whiteland Township Building
101 Commerce Drive
Exton, Pennsylvania
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AIWFrank/Mid-County Mustang Site Operable Unit 1 (OU-1)
agency for the Site, and the Pennsylvania Department of Environmental Protection
(PADEP) is the support agency. Since PADEP is currently responsible for operation and
maintenance activities at the Site, PADEP will fund and implement the Preferred
Alternative described in this Proposed Plan.
This Proposed Plan summarizes information that can be found in greater detail in the
June 2015 Focused Feasibility Study (FFS) Report for OU-1 and other documents
contained in the Administrative Record for the Site. EPA and PADEP encourage the
public to review the June 2015 FFS Report for OU-1 to gain a more comprehensive
understanding of the Site and the Superfund activities that have been conducted. The
Administrative Record for the Site can be accessed at www.epa.gov/arweb. or at the
following locations:
West Whiteland Township Building
101 Commerce Drive
Exton, PA 19341
Hours: Call (610) 363-9525
EPA Administrative Records Room
Administrative Coordinator
1650 Arch Street
Philadelphia, PA 19103
Telephone: 215-814-3157
Hours: Monday-Friday 8:30 am to 4:30 pm
By appointment only
EPA proposes the Preferred Alternative presented in this document, in conjunction with
the relevant components of the 1995 ROD, as the final OU-1 remedy for the Site. EPA
has determined that the modified remedy will be more effective than the current remedy
in addressing groundwater contamination at the Site.
EPA is issuing this Proposed Plan to solicit public comments on the proposed remedy
modifications for OU-1. This Proposed Plan is being issued as part of EPA's public
participation requirements under Section 117 of the Comprehensive Environmental
Response, Compensation, and Liability Act (CERCLA) of 1980, as amended, 42 U.S.C.
§ 9617, commonly known as Superfund, and Section 300.430(f)(ii) of the National Oil
and Hazardous Substances Pollution Contingency Plan (NCP), 40 C.F.R. § 300.430(f)(ii).
After the close of the public comment period and consideration of comments, EPA will
announce its selection of the remedy modifications in an Amendment to the ROD (ROD
Amendment). The public's comments and EPA's responses will be documented in the
Responsiveness Summary of the ROD Amendment. Comments should be submitted in
writing or emailed to either of the following EPA representatives:
Gregory Voigt (3HS21)
Remedial Project Manager
USEPA Region III
1650 Arch Street
Philadelphia, PA 19103
(215) 814-5737
voigt.gregory@epa.gov
Carrie Deitzel
Community Involvement Coordinator
USEPA Region III
1650 Arch Street
Philadelphia, PA 19103
(215)814-5525
deitzel. carrie@epa. gov
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The Proposed Plan includes the following sections:
I. Site History, Contamination, and Selected Remedy - Describes the nature and
extent of contamination at the Site.
II. Basis for the Document - Summarizes the results of investigations and other
activities completed since the initial ROD that form the basis for modifying the
remedy.
III. Description of New Alternatives - Describes the options for attaining the
identified remedial action objectives.
IV. Evaluation of Alternatives - Explains the rationale for selecting the Preferred
Alternative.
V. Statutory Determinations - Describes the Preferred Alternative and affirms that
it is expected to fulfill statutory and regulatory requirements.
VI. Public Participation - Provides information on how the public can provide input
to the remedy selection process.
I. SITE HISTORY, CONTAMINATION, AND SELECTED REMEDY
Site Location and Description
The AIW Frank/Mid-County Mustang Superfund Site is located approximately one mile
east of Exton on Lincoln Highway, U.S. Business Route 30 in West Whiteland
Township, Chester County, Pennsylvania (Figure 1).
The Site consists of two adjoining properties: the AIW Frank portion occupies over 15
acres, and the Mid-County Mustang covers less than one acre. The Site also includes the
areal extent of the contaminated groundwater plume, the municipal waterline, and the
groundwater treatment facility that have been constructed as part of the remedial action
for OU-1.
All the buildings on the AIW Frank portion of the Site have been demolished. The
property is currently an open area overgrown with vegetation and a large pile of crushed
stone/concrete remaining from the building demolition. The Mid-County Mustang
portion of the Site (currently Corbo Automotive Services) consists of an auto garage, a
parking lot, and a small lawn area and adjoins the AIW Frank property to the east. EPA's
extraction and treatment system building is north of the Mid-County Mustang property
(Figure 2).
Surrounding the Site is a private rental residence to west; the Stauffer Landscaping
building to the north; and a small open field, the old Meridian Bank building, and Route
30 to the south.
West Valley Creek flows east to west through the northernmost portion of the Site, just
south of the Chester Valley Trail walking path. Before EPA's involvement at the Site, the
creek was impounded on the property to form a pond measuring approximately 310 feet
by 60 feet (0.4 acres). The EPA groundwater treatment plant discharged all treated
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groundwater into this pond, where it then flowed into West Valley Creek or, as deemed
necessary by the Township, was used for spray irrigation of an adjacent township park.
Hydrogeologic Setting
The Site geology consists of unconsolidated silty clay-rich soils, also called Conestoga
silty loams, overlying the bluish-gray limestone and dolomite of the Conestoga
Limestone, the Ledger Dolomite, and the Elbrook Formation. The soils are derived from
the weathering (erosion) of the Conestoga Limestone and the Ledger Dolomite and are
well drained. Based on borehole logs from the remedial investigation (RI), the thickness
of the soil layer (called overburden) ranges from 6 feet (ft) to 75 ft throughout the Site.
The surface of the bedrock beneath the soil layer sometimes changes abruptly; this may
be the result of faulting, erosion that occurred before the soil (overburden) layer was
deposited, or when groundwater dissolves the limestone and forms cavities called
solution channels.
The Conestoga Limestone and Ledger Dolomite formations are the major source of
groundwater in the Chester Valley. Studies by the U.S. Geological Survey indicate that
the two formations, plus the Elbrook (where present) act as a single hydrologic unit as
static water levels do not significantly change where the overburden and bedrock meet, or
when groundwater flows through faults. Groundwater migrates through these formations
through fractures and solution channels within the rock mass.
There are several groundwater monitoring wells to monitor the groundwater
contamination at the Site. These wells are defined as shallow, intermediate, or deep.
Shallow wells are generally less than 75 ft deep, intermediate wells are between 75 ft and
150 ft deep, and deep wells are more than 150 ft deep. Most of the wells at the Site are
installed within the Ledger Dolomite. Some wells on the eastern portion of the site are
installed within the Conestoga Limestone. Groundwater is generally encountered from 3
ft below ground surface (bgs) to 25 ft bgs. The general direction of groundwater flow at
the Site is to the west/northwest.
History of Contamination
The AIW Frank Corporation manufactured Styrofoam products at the Site from 1962 to
1981 and the Continental Refrigeration Corporation manufactured commercial
refrigeration units at the Site from 1983 to 1988. EPA suspects that solvents used to
degrease the equipment were at times poured into an open floor drain in the front
building. This floor drain is thought to be a potential source of groundwater
contamination because it was located in the area of highest groundwater contamination.
Two large storage tanks, one for clean solvents and one for used solvents, were located
on the Site. EPA suspects that mishandling of the solvents in this storage tank area led to
the soil contamination found in this area and also contributed to the groundwater plume.
EPA suspects that previous operators of the auto garage on the Mid-County Mustang
property steamed and utilized solvents to clean auto engines and disposed of used
solvents in a floor drain. A 1984 environmental study commissioned by former owner
CDS Investment Company revealed the presence of trichloroethene (TCE) in a floor
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drain in the garage building. This drain lead to an on-Site tile field, which consisted of a
stone filter bed. It is believed that the solvents in the tile field area led to additional soil
contamination and contributed to the groundwater plume.
Previous Environmental Investigations and Removal Actions
EPA conducted a multimedia investigation of the AIW Frank/Mid-County Mustang
property and surrounding industrial sites in 1985 and found elevated levels of TCE,
tetrachloroethene, and 1,1,1-trichloroethane in the soil and groundwater. In 1987, EPA
prepared a Hazard Ranking System (HRS) score for the Site. The HRS is part of the
CERCLA process for determining if a site poses enough risk to be listed on the National
Priorities List (NPL) and prioritized for cleanup. Based on the HRS score, the Site was
listed on the NPL on October 24, 1989.
Private wells at risk of being contaminated were fitted with carbon filters to temporarily
remove VOCs from drinking water sources, and were connected to public water in 2000,
as required by the ROD.
Remedial Investigation and Feasibility Study
EPA conducted a Remedial Investigation and Feasibility Study (RI/FS) from January
1991 to January 1993. The RI/FS identified in greater detail the types, quantities, and
location of contaminants, as well as to develop ways of addressing the contamination. On
August 15, 1991, a fire destroyed the front building on the AIW Frank property and the
building was subsequently demolished.
The RI field investigation at the Site included the following tasks:
• Aerial photography analysis;
• Tank, drum, and building sampling;
• Asbestos survey and associated testing;
• Geophysical survey;
• Soil gas survey;
• Monitoring well installation;
• Groundwater sampling;
• Monitoring well location and evaluation survey;
• Aquifer testing;
• Test pit excavation and soil sampling;
• Surface water and sediment sampling; and
• Ecological assessment.
The RI investigations identified three types of significant contamination at the Site:
1. Groundwater contamination by VOCs;
2. Subsurface soil contamination by VOCs, semivolatile organic compounds
(SVOCs), pesticide/PCB compounds, and heavy metals;
3. Wastes contained in abandoned debris, underground tanks, drums, and a sump.
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Summary of Site Risks
During the RI/FS, a Human Health Risk Assessment (HHRA) was conducted to
determine the current and potential future effects of contaminants in Site media on human
health in the absence of any cleanup actions at the Site. The only risk remaining at the
site is associated with groundwater. There is no risk from site soils as they have been
addressed by the implementation and completion of the soil remedy selected in the 1995
ROD.
Human Health Risk Assessment
The HHRA was conducted during the RI/FS to characterize and quantify the current and
potential future human health risks that would occur if no remedial action was conducted
to address contaminated media at the Site. The HHRA identifies the potential exposure
pathways in which people may be exposed to Site contaminants, the toxicity of the
contaminants present, and the potential for carcinogenic and non-carcinogenic effects to
occur from exposure to the contaminants. Chemical contaminants that are ingested
(eaten), inhaled (breathed), or dermally absorbed (skin contact) may present carcinogenic
or non-carcinogenic risk to different organs of the human body.
EPA has established acceptable levels of carcinogenic risk ranging from 1 additional
cancer case per 10,000 people exposed to 1 additional cancer case per 1 million people
exposed, if no actions are taken at a site. Expressed in scientific notation, this translates to
an acceptable risk range of lxlO"4 to lxlO"6 for a lifetime excess carcinogenic risk. In
addition, EPA has established acceptable levels of non-carcinogenic risk, which is
expressed as a Hazard Index (HI). A HI exceeding 1 is considered an unacceptable non-
carcinogenic risk.
The Risk Assessment performed during the RI/FS for the Site evaluated the potential risk
associated with current land use and potential future use regarding exposure to on-site
residents and employees. Consumption of the groundwater posed a maximum lifetime
carcinogenic risk of 8.1xl0"4 (8.1 additional cancer incidents per 10,000) for a future on-
site adult resident and 1.2xl0"4 for a future on site child resident. Under a scenario where
a future on-site resident would utilize this groundwater for a potable water supply, it
would represent an unacceptable carcinogenic risk. The HI of 37 for the on-site adult
resident and the HI of 82 for the on-site child resident indicates that these scenarios
would also represent an unacceptable non-carcinogenic risk. The lifetime carcinogenic
risk and HI values for the on-site employees were at levels that do not represent an
unacceptable risk.
Ecological Risk Assessment
An ecological risk assessment was completed in 1996 to comply with the 1995 ROD.
The results of the ecological risk assessment were presented in the 2000 Remedial Action
Completion Report (RACR). The groundwater addressed under OU-1 does not occur in
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the biologically active zone. For these reasons, no additional ecological risk assessment is
needed for implementation of the Preferred Alternative selected for OU-1.
Risk Assessment Summary
In summary, the HHRA for the Site demonstrated the presence of unacceptable risks to
human health due to elevated VOC and metal concentrations in Site soil and
groundwater. EPA determined that remedial actions were necessary to reduce the risks to
within or below EPA's acceptable risk range. Therefore, it is EPA's determination that
implementation of the Preferred Alternative identified in this Proposed Plan is necessary
to protect human health from actual or threatened releases of hazardous substances and
pollutants or contaminants.
Description of 1995 Remedy
The RI/FS and HHRA assessment formed the basis for the September 29, 1995 ROD.
The Selected Remedy in the 1995 ROD consists of the following components:
1. Provision of Point-of-Use Carbon Filtration Units (for residents at risk until the
waterline is extended);
2. Installation of a waterline and service connections;
3. Performance of a Phase I archeological survey prior to any intrusive remedial
activities;
4. Excavation and off-site disposal of contaminated soils, following pre-remedial
design soil investigations;
5. Removal, decontamination, and off-site disposal of drums and sump;
6. Structure Demolition/Restoration;
7. Institutional controls (to prevent the consumption of contaminated groundwater
and creation of any hydraulically adverse influence on the extraction system
operation, including deed restrictions until cleanup levels are met);
8. Performance of an additional Ecological Assessment;
9. Extraction and treatment via air stripping of groundwater until SDWA Maximum
Contaminant Levels (MCLs) are met with vapor phase carbon adsorption and
subsequent discharge to either: (i) West Valley Creek, (ii) the on-site pond, or (iii)
the West Whiteland spray irrigation publicly owned treatment works (POTW),
following a pre-design hydrogeologic investigation;
10. Long-Term Groundwater Monitoring.
The 1995 ROD identified the following Remedial Action Objectives (RAOs):
1. Prevent current or future human exposure to contaminants in the groundwater,
soils, and sub-surface soils;
2. Minimize migration of contaminated groundwater;
3. Restore groundwater to MCLs;
4. Protect uncontaminated groundwater and surface water for current and future use;
and
5. Protect environmental receptors.
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The major COCs in groundwater identified in the 1995 ROD included:
• Trichloroethene
• 1,1,1-Trichloroethane
• 1,1 -Di chl oroethene
• 1,1 -Di chl oroethane
• 1,1,2-Tri chl oroethane
• cis-l,2-Dichloroethene
• 1,2-Dichloropropane
• T etrachl oroethene
• Vinyl Chloride
• Toluene
• Chloroform
• Arsenic
• Manganese
Additional risk evaluations were conducted for arsenic and manganese concentrations in
groundwater from samples collected in 2011. This risk evaluation was presented in the
2015 FFS. Based on the updated risk evaluation, arsenic and manganese do not pose a
threat to human health, and therefore will be removed from the original 1995 ROD COC
list.
Remedy Implementation
The 1995 ROD for the Site did not refer to OUs. In the years since, for administrative
purposes, EPA has identified OUs for the Site as follows:
OU-1:
• Groundwater Extraction and Treatment System (GETS)
• Long-Term Monitoring (LTM)
OU-2:
• Installation of the public waterline
OU-3:
• Soil excavation and disposal
• Drum and sump removal and off-site disposal
• Structure demolition/restoration
• Carbon filters
• Ecological assessment
• Archeological assessment and institutional controls
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Operable Unit 1
Construction of the GETS was completed in November 2000. The system consists of a
tray aerator designed for 90 percent VOC removal with vapor phase carbon treatment of
the off-gas followed by liquid phase carbon polishing prior to discharge. The GETS
began operation on November 1, 2000, and is capable of treating up to 200 gallons of
water per minute. EPA conducted a site visit on November 3, 2000 and verified that the
system was treating contaminated groundwater as designed. Completion of the
construction was documented in the Preliminary Close-out Report (PCOR) for the Site
dated November 10, 2000. The system was designed to operate 24 hours a day, 7 days
per week unattended with autodialing capabilities to notify maintenance personnel if
system alarms occur or system components shut down. The ROD also required
construction of a spray irrigation discharge system for the adjoining Township and
County park property, which was designed and built as an option for utilizing the water
discharged from the treatment system into the on-site pond. West Whiteland Township
assumed all responsibility for the operation and maintenance (O&M) of the spray
irrigation system.
Operable Unit 2
The design and construction of the waterline was completed in two stages. The first stage
consisted of the water main extension while the second stage dealt with the service
connections. Philadelphia Suburban Water Company (PSWC), through a contract with
U.S. Army Corps of Engineers, designed and installed the water main extension. The
water main extension included 5,483 feet of ductile iron water pipeline, 13 service taps
and 4 fire hydrants. It also included either the disconnection of the old supply wells or the
conversion of the wells to strictly non-consumptive outside use in compliance with
Chester County Health Department regulations. In all cases, the well supply was
disconnected from the in-home distribution system.
The water main extension work was completed in June 2000. Completion of the
construction was documented in the PCOR for the Site dated November 10, 2000.
Ownership of the extended water supply pipelines was assumed by PSWC. PSWC also
accepted responsibility for all future O&M of the water main extension. The OU-2
remedy has been completed per the 1995 ROD and therefore no additional changes to this
remedy are proposed within this Proposed Plan.
Operable Unit 3
On December 12, 1997, EPA and Lewis and Ruth Frame, owners of the AIW Frank
portion of the Site, signed an Administrative Order on Consent (AOC) whereby the
Frames agreed to prepare a Remedial Design/Remedial Action work plan for OU-3. On
August 5, 1998, the U.S. District Court for the Eastern District of Pennsylvania entered a
Consent Decree between EPA and the Frames requiring the Frames to perform the
remedial action selected in the ROD for OU-3 and to pay the United States $1.1 million
as reimbursement for the government's response costs at the Site. On September 4, 1998,
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EPA in consultation with PADEP, approved the Remedial Design/Remedial Action work
plan.
The Frame's contractor began work on site on October 31, 1998. The work included soil
excavation in the former above ground storage tank area of the AIW Frank portion of the
Site. The contaminated soils were placed in lined rolloff containers and disposed off-site
in accordance with the ROD. Drums that remained in the rear building were over-packed
and sent off-site for disposal. Contaminated sediments were removed from the sump
adjacent to the foundation of the front building, and the sump was then cleaned. The OU-
3 work also included an ecological assessment and an archeological assessment before
the soil excavation. No ecological risk or archeological artifacts were identified at the
Site as a result of these assessments. Completion of this work allowed for unrestricted use
of the AIW Frank portion of the Site, except for the institutional controls related to the
groundwater portion of the remedy.
The OU-3 remedy has been completed per the 1995 ROD, as documented in the 2000
PCOR, and therefore no additional changes to this remedy are proposed within this
Proposed Plan.
II. BASIS FOR DOCUMENT
Groundwater sampling was conducted semiannually at the Site since the GETS began
operation. As a result of several years of monitoring and operation, EPA has determined
that a remedy modification is necessary. Use of the tray aerator system was discontinued
in August 2005 because the groundwater concentrations were at levels that only
warranted treatment with the liquid phase carbon. After evaluation of the February/March
2008 semiannual groundwater sampling results, EPA determined that operation of only
one extraction well by itself was not generating a hydraulic capture zone and was having
minimal impact on the dissolved plume. In addition, the influent groundwater
concentrations were less than the required discharge levels. The GETS was therefore
turned off by EPA on April 24, 2008, but has been maintained in operational condition.
In order to optimize the groundwater remedy, EPA conducted three pilot studies between
2005 and 2009 to determine if the groundwater contamination could be cleaned up using
ISCO. EPA tested potassium permanganate and sodium permanganate oxidants by
injecting them through existing site wells (EW-4, EW-5, OB-II, MW-108A, and MW-
111) into the groundwater. The injections were completed in the areas of highest VOC
contamination to the south of the AIW Frank Portion of the Site. Post-injection sampling
confirmed that both oxidants were able to reduce VOC groundwater contamination and
could be used as a viable option for future treatment.
EPA conducted two additional pilot studies in 2010 and 2011 to determine if the
groundwater could be treated using in situ enhanced bioremediation. In situ enhanced
bioremediation is a process in which Site conditions are modified to enhance the desired
microbial activity. EPA tested two amendments: ABC® (a patented mixture of lactates,
fatty acids, and a phosphate buffer) and LactOil® (a self-emulsifying vegetable oil) by
injecting them into the groundwater. The amendments stimulate the growth of
microorganisms that are capable of degrading the VOC contaminants in groundwater and
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converting them to less toxic end products. The ABC® was injected into MW-112B,
which is located to the west of the Site outside the main source area. The LactOil® was
injected into EW-4 and MW-117 (installed for the pilot study) located within the area of
highest VOC contamination to the south of the AIW Frank Portion of the Site. Both
amendments were able to reduce VOC groundwater contamination and could be used as a
viable option for future treatment.
Figures 3 and 4 show TCE concentrations observed in the shallow wells and
intermediate/deep wells, respectively, from data collected in November 2013. The
highest levels of contamination are to the south/southwest of the Former AIW Frank rear
building. The highest TCE concentrations were detected in the shallow bedrock wells
MW-114 and OB-3S at concentrations of 43 |ig/L and 34 |ig/L, respectively. The
contamination plume has migrated downgradient in a west/northwest direction, which is
consistent with groundwater flow at the Site. TCE has been detected on the west side of
West Valley Creek, but at lower concentrations than what are seen closer to the Site.
November 2013 TCE concentrations are also illustrated on a hydrogeologic cross section
on Figure 5. Figure 6 illustrates TCE concentrations from October 2005, prior to the
implementation of the pilot studies discussed above. In October 2005 the highest TCE
concentrations were in wells OBI-I and EW-4, at concentrations of 470 |ig/L and 340
|ig/L, respectively. Since the pilot studies have been completed the TCE concentrations
have been significantly reduced. The TCE concentrations in November 2013 were 28.5
|ig/L and 13 |ig/L in wells OB1-I and EW-4, respectively.
Given the positive results of the ISCO and bioremediation pilot studies, a Focused
Feasibility Study (FFS) was completed in 2015 by EPA to determine whether it would be
beneficial to amend the OU-1 groundwater remedy specified in the 1995 ROD. Based on
the information presented in the FFS, EPA concluded that compared to the existing
extraction and treatment remedy, a remedy which includes ISCO and bioremediation
technologies would require less time and less funding to achieve cleanup goals. EPA
therefore has decided to propose modifications to the OU-1 remedy as explained in
Section III, below.
In addition to changing treatment technologies, this Proposed Plan also seeks to modify
the Site COCs and PRGs. 1,4-dioxane has been detected in the groundwater at
concentrations that exceeded the tap water regional screening level (RSL) and will
therefore be added as a COC that requires remediation. Because there is no MCL for 1,4-
dioxane under the SDWA, EPA proposes to use the groundwater medium specific
concentration (MSC) for 1,4-dioxane set forth in Pennsylvania's Land Recycling and
Remediation Standards Act - also known as 'Act 2' - as the PRG for this COC. The Act
2 MSC for 1,4-dioxane is 6.4 micrograms per liter (|ig/L), and has an associated risk
level of approximately 1.39 x 10"5.
Finally, the MCLs for 1,1-dichloroethane and chloroform have changed since the 1995
ROD was issued. The MCL for 1,1-dichloroethane has changed from 81|ig/L to 2.7|ig/L,
and the MCL for chloroform has changed from 100|ig/L to 80|ig/L. The PRG's for 1,1-
dichloroethane and chloroform will be updated to reflect these changes.
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An updated list of COCs and associated PRGs for groundwater is presented in Table 1.
Table 1
Proposed Groundwater Contaminants of Concern
(iron nil w ntcr I'RfJs
(hemicitl
PRC
(Utt/IJ
liiisis
Trichloroethene
5
Current COC, Drinking Water MCL
1,1,1 -Trichloroethane
200
Current COC, Drinking Water MCL
1,1-Dichloroethene
7
Current COC, Drinking Water MCL
1,1-Dichloroethane
2.7(1)
Current COC, Tap Water RSL
1,1,2-Trichloroethane
5
Current COC, Drinking Water MCL
cis-1,2-Dichloroethene
70
Current COC, Drinking Water MCL
1,2-Dichloropropane
5
Current COC, Drinking Water MCL
Tetrachloroethene
5
Current COC, Drinking Water MCL
Vinyl Chloride
2
Current COC, Drinking Water MCL
Toluene
1000
Current COC, Drinking Water MCL
Chloroform
80(1)
Current COC, Drinking Water MCL
1,4-dioxane
6.4
Proposed COC, PA Act 2 Groundwater MSC
Notes:
ju.g/L - micrograms per liter
PRG - Preliminary Remediation Goal
MCL - Maximum Contaminant Level
COC - Contaminant of Concern
RSL - Regional Screening Level (June 2015)
(1) - PRG different from 1995 ROD due to updated MCLs/RSLs
Consistent with EPA's May 2014 Guidance for Evaluating Completion of Groundwater
Restoration Remedial Action, when PRGs have been attained, EPA will evaluate all
groundwater monitoring data and develop a trend analysis and risk assessment. The risk
assessment will be based on an assessment of the cumulative risk across all applicable
exposure routes for all COCs remaining in groundwater following achievement of the
PRGs. The remediation of groundwater at the Site will continue until the risk-based
cleanup standards (cumulative risk <1.0 x 10"4 and HI less than or equal to 1 based on
target organs) are achieved.
III. DESCRIPTION OF NEW ALTERNATIVES
With this Proposed Plan, EPA is proposing to modify the portions of the 1995 ROD
addressing contaminated groundwater (OU-1). No modifications to the remedies for OU-
2 or OU-3 are presented in this Proposed Plan since the remedial actions for these two
operable units have been completed and remain protective of human health and the
environment.
The Preferred Alternative proposed herein will achieve RAOs in a more effective manner
than the remedy selected by the 1995 ROD through the use of treatment technologies
12
AR201751
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Proposed Plan
AIWFrank/Mid-County Mustang Site Operable Unit 1 (OU-1)
which will permanently reduce the toxicity, mobility, and volume of contaminants in
groundwater. The Preferred Alternative will also ensure the continued protection of
human health by eliminating current and potential future exposure to contaminated
groundwater.
Summary of Remedial Alternatives
Because the remedial alternative, the GETS, implemented for OU-1 was having minimal
impact on the dissolved phase plume after eight years of operation, EPA believed a
remedy optimization was necessary and reevaluated remedial alternatives in the June
2015 FFS Report for OU-1. EPA identified and screened a range of technologies with the
potential to address the OU-1 contamination. EPA assembled the technologies that passed
the screening into a series of cleanup alternatives and subjected them to a more detailed
evaluation. The three alternatives selected for detailed evaluation were:
Alternative 1 No Action
Alternative 4: Groundwater Extraction Treatment with Ultraviolet (UV)
Oxidation, Monitored Natural Attenuation (MNA), and
Institutional Controls (ICs)
Alternative 7: ISCO, Enhanced Bioremediation, Long-Term Monitoring and ICs
EPA's preferred remedy for OU-1 is Alternative 7. Each of the alternatives is presented
in more detail below.
Alternative 1: No Action - The No Action alternative is included as a baseline for
comparison of other alternatives. No remedial activities or additional ICs would be
implemented under this alternative. The GETS would remain offline. Some level of
natural attenuation of contaminants might occur in groundwater that would reduce the
contaminant mass over time due to naturally occurring processes, such as;
biodegradation, dispersion, dilution, adsorption, and volatilization.
Alternative 4: Groundwater Extraction Treatment with UV Oxidation, MNA, and
ICs - The GETS would be brought back online to treat the remaining contaminants in the
groundwater. Additional extraction wells may be needed to effectively treat remaining
groundwater contamination. It is anticipated that the GETS could accommodate a total
flow rate of 200 gallons per minute. A UV Oxidation system would be installed and
connected to the existing extraction system to treat 1,4-dioxane. It is estimated that the
average influent 1,4-dioxane concentration would be 50 |ig/L and the effluent
concentration would be less than 1 |ig/L. Groundwater monitoring would be required
until PRGs are achieved across the Site. MNA would be used for portions of the plume
that are beyond the capture area of the GETS. ICs include groundwater use limitations
that have been implemented per the 1995 ROD through a local ordinance restricting
groundwater use for consumption. Five-Year Reviews (FYRs) of the Site remedy also
would be required under CERCLA until the contamination is remediated to PRGs.
13
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Proposed Plan
AIWFrank/Mid-County Mustang Site Operable Unit 1 (OU-1)
Alternative 7: ISCO, Enhanced Bioremediation, Long-Term Monitoring and ICs -
Given the success of both ISCO and in situ enhanced bioremediation in their respective
pilot studies, both treatment technologies would be utilized in this alternative to
maximize flexibility during implementation and increase the likelihood of a successful
outcome. ISCO would be utilized initially at the Site by injecting an oxidant, such as
potassium permanganate, throughout the groundwater plume to treat VOC and 1,4-
dioxane contamination. In situ enhanced bioremediation of the groundwater
contamination would be completed after chemical oxidation, by injecting nutrients and/or
other amendments into the groundwater plume to stimulate biological degradation of Site
contaminants. The oxidants and amendments injected under this alternative will naturally
break down into chemicals and compounds that do not pose a threat to human health.
Additional injection and/or monitoring wells will be needed to adequately distribute the
oxidants/amendments and monitor their effectiveness. Groundwater monitoring would be
required on an annual basis for all COCs until PRGs are achieved. ICs include
groundwater use limitations that have been implemented per the 1995 ROD through a
local ordinance restricting groundwater use for consumption. FYRs of the Site would also
be required under CERCLA until the contamination is remediated to PRGs. The existing
GETS would remain shut down, but would continue to be maintained in operable
condition in the event that it is needed for future remedial action at the site. EPA would
re-evaluate the need for the GETS during future FYRs, and any change in its operational
status would be documented by in a decision document.
Remedial Action Objectives
This Proposed Plan does not alter the RAOs in the 1995 ROD, presented in Section I of
this document.
IV. EVAUATION OF ALTERNATIVES
Nine criteria are used to evaluate the different Remedial Alternatives individually and
against each other in order to select a remedy. This section of the Proposed Plan profiles
the relative performance of each alternative against the evaluation criteria. Each of the
alternatives are compared to the other options under consideration. The evaluation criteria
are summarized below.
The nine criteria fall into three groups: threshold criteria, primary balancing criteria, and
modifying criteria. A description of the three groups follows:
• Threshold criteria, which are requirements that each alternative must meet in
order to be eligible for selection.
• Primary balancing criteria, which are used to weigh major trade-offs among
alternatives.
• Modifying criteria, which may be considered to the extent that information is
available during the FS, but will be fully considered only if public comments are
received on this Proposed Plan. In the final balancing of tradeoffs between
alternatives upon which the final remedy selection is based, modifying criteria are
of equal importance to the balancing criteria.
14
AR201753
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Proposed Plan
AIWFrank/Mid-County Mustang Site Operable Unit 1 (OU-1)
K\iiluiiiion Criteria lor Supcrl'und Remedial Alternalhes
Threshold Criteria
1. Overall Protection of Human Health and the Environment determines whether an
alternative eliminates, reduces, or controls threats to public health and the environment through
institutional controls, engineering controls, or treatment.
2. Compliance with ARARs evaluates whether the alternative meets Federal and State
environmental statutes, regulations, and other requirements that pertain to the site, or whether a
waiver is justified.
Primary Balancing Criteria
3. Long-term Effectiveness and Permanence considers the ability of an alternative to
maintain protection of human health and the environment over time.
4. Reduction of Toxicity, Mobility, or Volume of Contaminants through Treatment
evaluates an alternative's use of treatment to reduce the harmful effects of principal
contaminants, their ability to move in the environment, and the amount of contamination
present.
5. Short-term Effectiveness considers the length of time needed to implement an alternative
and the risks the alternative poses to workers, residents, and the environment during
implementation.
6. Implementability considers the technical and administrative feasibility of implementing the
alternative, including factors such as the relative availability of goods and services.
7. Cost includes estimated capital and annual O&M costs, as well as present worth cost.
Present worth cost is the total of an alternative over time in today's dollar value. Cost estimates
are expected to be accurate within a range of +50 to -30 percent.
Modifying Criteria
8. State/ Support Agency Acceptance considers whether the State agrees with EPA's
analyses and recommendations, as described in the RI/FS and Proposed Plan.
9. Community Acceptance considers whether the local community agrees with EPA's
analyses and preferred alternative. Comments received on the Proposed Plan are an important
indicator of community acceptance.
The major findings of the detailed evaluation of the three alternatives based on the nine
evaluation criteria are summarized below: The "Detailed Analysis of Alternatives" can
be found in the FFS Study Report.
1. Overall Protection of Human Health and the Environment
A local ordinance restricting groundwater use is currently in place at the Site, and
therefore included as part of Alternatives 4 and 7. The ordinance provides short-term
protection of human health, provided that it remains in effect and is enforced. Alternative
1 does not provide long-term protection of human health and the environment because it
would not eliminate the groundwater contamination. Alternatives 4 and 7 are both
protective of human health and the environment because they would reduce the
groundwater contamination to safe levels. Alternative 7 would achieve PRGs and restore
the groundwater to beneficial use in the shortest period of time (Alternative 7 would
achieve PRGs in approximately 20 years, whereas Alternative 4 would take more than 30
years to achieve PRGs).
15
AR201754
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Proposed Plan
AIWFrank/Mid-County Mustang Site Operable Unit 1 (OU-1)
2. Compliance with ARARs
Alternative 1 does not comply with the Applicable or Relevant and Appropriate
Requirements (ARARs), because groundwater would not be addressed by any active
remediation to reduce contaminant concentrations and associated risks. Alternative 4
would comply with ARARs, but it is questionable whether it can be used to achieve the
PRGs in a reasonable timeframe. Alternative 7 is expected to achieve compliance with all
identified ARARs in a reasonable timeframe.
ARARs and other advisories, criteria, or guidance to be considered (TBCs) are shown in
Table 2 included at the end of this document. Note that Table 2 includes EPA's May
2014 Guidance for Evaluating Completion of Groundwater Restoration Remedial Action
as a new TBC. Pennsylvania's Act 2 cleanup standard for 1,4 dioxane has also been
added as a TBC. All ARARs and TBCs from the 1995 ROD remain the same, and are
included in this Proposed Plan.
3. Long-Term Effectiveness and Permanence
Alternatives 4 and 7 would reduce the concentrations of contaminants over time. Based
on historical operation of the GETS, Alternative 4 would be able to permanently reduce
COC concentrations, but reconfiguration of the system is needed to optimize treatment,
with additional extraction wells required to capture all of the contaminated groundwater.
MNA will be performed to complete the remediation. If the GETS cannot be optimized to
capture all of the contamination in groundwater, MNA will be required and it will take
longer to achieve PRGs. Pilot study results indicated that Alternative 7 would be effective
in reducing Site-related contaminant concentrations to levels below the PRGs in a shorter
period of time than Alternative 4. Alternative 7 will provide the most effective and
permanent remedy for the Site in the long-term.
4. Reduction of Toxicity, Mobility, or Volume through Treatment
Alternatives 4 and 7 would reduce the toxicity and volume of Site-related contaminants
through treatment technologies. Alternative 4 may also have a greater effect on reducing
the mobility of the plume if the area of influence of the extraction wells changes
groundwater flow direction.
5. Short-term Effectiveness
Alternative 4 would increase the potential for remedial workers and area residents to be
exposed to Site-related contamination through dermal contact and inhalation of vapors
during construction of extraction wells, operation of the treatment plant, and groundwater
sampling. The timeframe to bring the treatment system back online and complete the
construction of the extractions wells is estimated to be completed within 3 to 6 months.
Alternative 7 would have the greatest potential to expose remedial workers and local
residents to hazardous materials through dermal contact and inhalation of vapors during
construction of injection wells, groundwater sampling, and exposure to oxidant
16
AR201755
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Proposed Plan
AIWFrank/Mid-County Mustang Site Operable Unit 1 (OU-1)
amendments. Construction of injection wells is estimated to be completed within a
month and each injection event would only span one to two weeks.
All of the potential exposures resulting from the implementation of Alternatives 4 and 7
can be minimized or eliminated through the use of proper personal protective equipment
(PPE), safe work procedures, and site controls.
6. Implementability
Alternative 7 would be difficult to implement but could be implemented using standard
injection equipment and commercially available amendments. The fractured nature of the
bedrock at the Site could make it difficult to distribute the oxidant and bioremediation
amendments evenly to all points of the contaminant plume; however, this constraint
could be managed by using additional injection and/or monitoring wells. Periodic O&M
of the injection and monitoring wells would also increase costs.
Alternative 4 would be the most difficult to implement of the two alternatives, as it would
require installation of a UV oxidation system and operation of the GETS. This would
require extensive O&M over the course of the remedy and would incur additional costs as
GETS components begin to fail and require replacement.
7. Cost
The order-of-magnitude level estimates for total project costs (shown as present value
estimates taken over 30 years at a discount rate of 7%) for the three alternatives are
presented in tabular form below along with anticipated capital expenditures (including
design, project management, and related expenses).
Alternate
Capital Cost
30 Year I'resenl Yalue
Alternative 1
$0
$0
Alternative 4
$529,000
$4,732,000
Alternative 7
$794,000
$1,629,000
8. State Acceptance
The Commonwealth of Pennsylvania supports the Preferred Alternative, pending public
comments.
9. Community Acceptance
EPA will evaluate community acceptance of the Preferred Alternative based on
comments received during the public comment. Community comments and EPA's
response will be available in the Responsiveness Summary of the ROD Amendment.
17
AR201756
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Proposed Plan
AIWFrank/Mid-County Mustang Site Operable Unit 1 (OU-1)
V. STATUTORY DETERMINATIONS
EPA's Preferred Alternative for OU-1 is Alternative 7 (ISCO, Enhanced Bioremediation,
Long-Term Monitoring and ICs). Based on an evaluation of the three retained
alternatives using the evaluation criteria, Alternative 7 presents the best balance of the
criteria in addressing the risks in OU-1. This alternative complies with ARARs, addresses
all of the Site-related groundwater contamination, and can be implemented for about one-
third the cost of Alternative 4. Alternative 7 is also easier to implement and is expected to
achieve PRGs in a shorter timeframe than Alternative 4.
The modifications to the 1995 ROD that are presented in this Proposed Plan satisfy the
requirements of CERCLA § 121. The Preferred Alternative is protective of human health
and the environment; complies with federal and state requirements that are legally
applicable or relevant and appropriate requirements to the remedial action; is cost
effective; and utilizes permanent solutions to the maximum extent practicable. The
Preferred Alternative also satisfies EPA's statutory preference for treatment as a principal
element of the remedy.
VI. PUBLIC PARTICIPATION
EPA relies on public input so that the remedy selected for each Superfund site meets the
needs and concerns of the local community.
Public Comment Period - To ensure that the community's concerns are being addressed,
a public comment period will open June 1, 2016 and close June 30, 2016. During this
time, the public is encouraged to submit to EPA any comments on the Proposed Plan.
Public Meeting - A public meeting will be held to discuss the Proposed Plan on June 14,
2016 from 6:30 p.m. to 8:30 p.m. The public meeting will be held at the West Whiteland
Township Building, 101 Commerce Dr., Exton, PA.
It is important to note that although EPA has proposed a Preferred Alternative, EPA has
not yet selected the final remedy for the Site. All relevant comments received will be
considered and addressed by EPA before the final remedy is selected for the Site.
Detailed information on the material discussed herein may be found in the Administrative
Record for the Site. EPA encourages the public to review the Administrative Record in
order to gain a more comprehensive understanding of the Site and the Superfund
activities that have taken place there. Copies of the Administrative Record are available
for review at www.epa.gov/arweb. or at the following locations:
West Whiteland Township Building
101 Commerce Drive
Exton, PA 19341
Hours: Call (610) 363-9525
18
AR201757
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Proposed Plan
AIWFrank/Mid-County Mustang Site Operable Unit 1 (OU-1)
EPA Administrative Records Room, Attention: Administrative Coordinator
1650 Arch Street
Philadelphia, PA
(215) 814-3157
Hours: Monday through Friday, 8:30am to 4:30pm; by appointment only.
Written comments, questions about the Proposed Plan or public meeting, and requests for
information can be sent to either of the following EPA representatives:
Gregory Voigt (3HS21)
Remedial Project Manager
USEPA Region III
1650 Arch Street
Philadelphia, PA 19103
(215) 814-5737
voigt.gregory@epa.gov
Carrie Deitzel
Community Involvement Coordinator
USEPA Region III
1650 Arch Street
Philadelphia, PA 19103
(215)814-5525
deitzel.carrie@epa.gov
Following the close of the public comment period on this Proposed Plan, EPA will
prepare a Responsiveness Summary. The Responsiveness Summary will summarize and
respond to comments on EPA's Preferred Alternative. EPA will then prepare a formal
decision document, the ROD Amendment, which summarizes the decision process and
the remedy modification for the Site. The ROD Amendment will include the
Responsiveness Summary. Copies of the ROD Amendment will be available for public
review in the designated repositories described above.
19
AR201758
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Table 2
Applicable or Relevant and Appropriate Requirements and Standards To Be Considered
ARAR
l.ciiiil ('iliilion
ARAR ( hiss/1 li(
RcmiimiH'iil S\ nopsis
Ai)i)liciil)ilil\ lo Proposed Remedies
( hciniciil Specific ARARs
A. Water
Safe Drinking Water
Act (SDWA)
Maximum
Contaminant Levels
(MCLs)
40 CFR §§ 141.11,
141.61 and 141.62
Relevant and
Appropriate
MCLs are enforceable standards for
public drinking water supply systems
which have at least 15 service
connections or are used by at least 25
persons.
These requirements are not directly
applicable since groundwater in the
vicinity of the site is not used as private
drinking water supply. However, since
groundwater at the site is located within
a Class II aquifer, which is a potential
source of drinking water, the MCLs
have been incorporated into the
Preliminary Remedial Goals that were
developed for the site groundwater.
Clean Water Act
(CWA): National
Pollutant Discharge
Elimination System
(NPDES) Requirements
Clean Water Act,
Section 402: 33 U.S.C.
§1342, 40 CFR Parts
122-125
Applicable
NPDES Permit Equivalence will need
to be established for any surface water
discharges from any groundwater
extraction and treatment or stormwater
outfalls.
The substantive provisions of these
requirements are applicable to any
portion of the remedy that may affect
the water quality in the nearby West
Valley Creek. Sediment and erosion
control features will need to be
implemented before start of intrusive
construction activities.
Pennsylvania Water
Quality Standards
25 Pa. Code § 93
Relevant and
Appropriate
These are specific water quality criteria
established pursuant to Section 304 of
the CWA. These provisions set the
concentrations of pollutants that are
allowable to levels that preserve
human health based on water and fish
ingestion and to preserve aquatic life.
Ambient water quality criteria may be
relevant and appropriate to the
Comprehensive Environmental
Response, Compensation, and Liability
Act (CERCLA) cleanups based on uses
of a water body.
The discharge of treated groundwater
would be required to meet the guidelines
established for protection of aquatic life.
Page 1 of 5
AR201759
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Table 2 (continued)
Applicable or Relevant and Appropriate Requirements and Standards To Be Considered
ARAR
l.ciiiil ('iliilion
ARAR ( hiss/1 li(
Rcmiircmcnl S\nopsis
Appliciil)ilil\ (o Proposed Remedies
1 .oc;Mion-Specific A RA Rs/TIK s
Preservation of
Historical and
Archeological Data Act
(or Archeological and
Historic Preservation Act
of 1974)
16 U.S.C.§ 469
Applicable
Requires that Federal agencies take
action to recover, protect, and preserve
any significant scientific, prehistorical,
historical, or archeological data that
may be irreparably lost or destroyed as
a result of the alteration of terrain
caused by Federal activities.
U.S. Environmental Protection Agency
(EPA) does not currently have any
information that there are any significant
scientific, prehistorical, historical, or
archeological data at the site. If EPA
discovers that such data are present at
the site, actions will be taken to comply
with the substantive requirements of this
act.
The National Historical
Preservation Act and
regulations
16 U.S.C. §470;
36 CFR Part 800
Applicable
Requires that Federal agency actions
avoid adverse effects in historic
properties.
EPA does not currently have any
information that there are historic
properties at the site. If a determination
is made that there are historic properties
on or near the site, action will be taken
to mitigate any adverse effects on those
properties resulting from the remedial
activities.
Ac( ion-Specific ARARs/TB( s
A. Water
Pennsylvania Clean
Streams Law
25 Pa. Code §§ 16.1,
16.24, 16.31 - 16.33,
16.41, 16.51 and
16.101-102
Applicable
The objective of this statute is to
reclaim and restore polluted streams.
The law provides for the protection of
streams and water quality control. This
statute may be applicable to remedial
alternatives that require the discharge
of water/waste, and/or the cleanup of
contaminated streams.
The groundwater treatment alternative
that involve the discharge of treated
water will be required to comply with
the substantive requirements of these
discharge standards.
Page 2 of 5
AR201760
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Table 2 (continued)
Applicable or Relevant and Appropriate Requirements and Standards To Be Considered
ARAR
l.ciiiil ('iliilion
ARAR ( hiss/1 li(
Rc(|iiimiH'iil S\ nopsis
A|)|)liciihilil> lo Proposed Remedies
CAVA
4u o r §§ i::.:,
122.4, 122.5, 122.21,
122.26, 122.29,
122.41, 122.43 -
122.45,
122.47,122.48
(All of these sections,
except for 122.47, are
incorporated by
reference into
Pennsylvania's
regulation by 25 Pa.
Code § 92.2.)
Relax anl and
Appropriate
Lilabliilici effluent limiiauoiis for
discharges to waters of Pennsylvania
and the United States.
The groundwater treatment alternative
that involve the discharge of treated
water will be required to comply with
the substantive requirements of these
discharge standards.
Pennsylvania
National Pollutant
Discharge
Elimination System
Requirements
25 Pa. Code
§§ 92.3, 92.7, 92.31,
92.41,92.51,92.55,
92.57, 92.73, 93.6,
93.7 and 95.2
SDWA
Underground Injection
Control (UIC)
Regulations
40 CFR §§ 144.1-
144.55; 144.79-144.84;
146.1-1.6.10; 146.51-
146.73; 5, 147.1951,
147.1952.
Relevant and
Appropriate
Provides requirements for underground
injection control permitting based on
the federal program promulgated under
Part C of the Safe Drinking Water Act.
The substantive requirements of these
regulations will be followed for any
remedy that involves the injection of
materials into the subsurface.
Water Well Driller
License Act
32P.S. §645.1 et. seq.;
17 Pa. Code §§47.1-
47.8
Applicable
Sets forth requirements for the
licensing of water well drillers,
prevention of pollution of underground
waters, submittal of well construction
records, and well abandonment
notification.
The substantive requirements of these
regulations will be followed for any
remedy that involves the installation or
abandonment of a well, or the injection
of materials into an existing well.
Storm Water
Management Act
33 U.S.C. § 402; 40 §
CFR 122.21
Applicable
Requires implementation of storm
water control measures to prevent
injury to health, safety, or property.
Storm water controls will be
implemented and maintained during
construction of the remedy
Page 3 of 5
AR201761
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Table 2 (continued)
Applicable or Relevant and Appropriate Requirements and Standards To Be Considered
ARAR
l.ciiiil ('iliilion
ARAR ( hiss/1 li(
Rc(|iiimiH'iil S\ nopsis
A|)|)liciihilil> lo Proposed Remedies
32 P.S. § 680.1 et seq.;
25 Pa. Code Chapters
111, 102, and 92
USEPA Guidance for
Evaluating Completion
of Groundwater
Restoration Remedial
Action
USEPA OSWER
Directive 9355,0-1129.
Nov, 2013
To Be Considered
Presents EPA's recommendations for
evaluating Superfund groundwater
remedy performance and making
decisions to help facilitate achievement
of RAOs and associated cleanup levels.
This guidance will be used to evaluate
remedy performance and achievement
of RAOs.
B. Soil
Erosion and Sediment
Control
25 Pa. Code
§§102.4(b)(1), 102.11,
102.22
Applicable
Identifies erosion and sediment control
requirements and criteria for activities
involving land clearing, grading and
other earth disturbances and establishes
erosion and sediment control criteria.
These regulations apply to construction
activities at the site that disturb the
ground surface and would be applicable
if capping, excavation, or well
installation is required.
C. Wastes
Resource
Conservation and
Recovery Act
(RCRA)
Pennsylvania
Hazardous Waste
Management
Regulations
25 Pa. Code
§§ 262a.34 (which
incorporates by
reference 40 CFR §
262.34), 264a. 173
40 CFR § 262.34
(accumulation time
and requirements)
40 CFR §§ 264.171-
175 (containers)
Relevant and
Appropriate
These provisions govern the
accumulation time for hazardous
wastes and management of containers.
These requirements must be followed
for any groundwater treatment remedy
that generates hazardous sludge.
Municipal Waste
Handling
25 Pa. Code, Article
VIII
Applicable
These provisions govern the handling
and disposal of municipal wastes.
These provisions are applicable to any
remedy that will result in the generation
of municipal waste upon
implementation.
Residual Waste Handling
25 Pa. Code, Article IX
Applicable
These provisions govern the handling
and disposal of residual wastes.
These provisions are applicable to any
remedy that will result in the generation
of residual wastes upon implementation.
D. Air
Fugitive Air
Emissions
25 Pa Code §§ 123.1-
123.2
Applicable
Establishes the fugitive dust regulation
for particulate matter.
Any construction and/or excavation
activities will comply with the
Page 4 of 5
AR201762
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Table 2 (continued)
Applicable or Relevant and Appropriate Requirements and Standards To Be Considered
ARAR
l.ciiiil ('iliilion
ARAR ( hiss/1 li(
Rc(|iiimiH'iil S\ nopsis
A|)|)liciihilil> lo Proposed Remedies
40 CFR § 50.6 - 50.7
substantive requirements of these
regulations.
National Emissions
Standards for Hazardous
Air Pollutants
25 Pa Code §§ 124.1-
124.3
40 CFR Part 61
Applicable
Establishes the hazardous air pollutant
discharge regulation.
Any construction and/or excavation
activities as well as any treatment
alternative that would result in the
emission of Site contaminants to the air
will comply with the substantive
requirements of these regulations.
Construction,
Modification,
Reactivation, and
Operation of Sources
25 Pa Code §§ 127.1 et
seq.
Applicable
Establishes the requirements for the
use of best available technology on
new air pollutant emissions sources.
Any construction and/or excavation
activities as well as any treatment
alternative that would result in the
emission of site contaminants to the air
will comply with the substantive
requirements of these regulations.
Visible Emissions
25 Pa Code § 123.41
Applicable
Establishes opacity limits for visible
air emissions.
Emissions from any excavation/
construction will comply with the
substantive requirements of these
requirements.
Page 5 of 5
AR201763
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AIW Frank/
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AR201764
-------
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(2)Site_Lqyout. mxd
2/11/2016 CNL
Source: HGL, EPA
Legend
Former Sump
Former Pipe Outfall
Trail
Drainage Ditch
Creek
Site Boundary
Existing Structure
Former Structure
Surface Water
West Valley Creek
Chester Valley Trail
\ Former Earthem Drainage Ditch
\ Former Underground
Drainage Pipe Outfall
Former Underground
Drainage Pipe
Former
AIW Frank Building
FormeuWater Tower
AIW Frank/Mid-County Mustang
Site Boundary
Former USTs
Private Duplex
Residence
Former,Mid-County
Mustang Building
Former Meridian Bank^j^\
AR201765
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-MW-105B
HW-13B
100 200
Feet
400
o
D
HW-06 -
\G ro u n d water-T reatjne n tj3u i|d i ng^
MW-104 B
MW-104A
MW-115
./I
MW-113 A
MW-113B
jGroundwaterv
{Flow Direction-
MW-112A
-former-
Mid-'CpuntyP
Mustang'Buildirig,
EW-3
MW-107A (2)
(ndV
MW-107 B
Former
-AlWiFrank Building
Rear
Building
OB-2S (2) \ EW.2
ND'
¦MW-112B
"1»
MW-117 (1) iA A
EW-5
30
MW-114
s43
MW-110 (3)
4.8 V
M0»
"0B~5 \ _.MW-11 £.
•7fT VOB-4\
OB-3S^
r34 ^,30.
— OB-2I 1?
\ ^-ob-ii-
.( "—¦
MW-108 A EW-'<
-MW-111
MW-116 (2)
2.84\
\ Front \
\ \ w ,
\ Building \
w '•x N
MW-103A (2) MW_-| 03B
^\1.09"
EW-6
"FoYmerC
AIW Frank Building
^'-Va«ey_e,ee((;
U.S. J
Notes:
TCE=trichloroethene
^ig/L=micrograms per liter
\ \gst-srv-01 \HGLGIS\AIW_Frank\_MSIW\PP \
(3)TCE Shallow Bedrock Nov2013.mxd
Legend
Existing Structure
Figure 3
3/23/2016 CNL
Source: HGL, EPA
&
Shallow Well
—1—
TCE Concentration Contour (|ig/L)
Former Structure
TCE Concentrations
Intermediate Well
- 10 -
Estimated TCE Concentration Contour (|ig/L)
Surface Water
for Shallow Bedrock Wells
&
Deep Well
1.7
TCE Concentration (|ig/L)
(1)
Data from Dec 2011
November 2013
&
Extraction Well
ND
Not Detected
(2)
Data from April 2012
AIW Frank/Mid-County Mustang Site
&
Residential Well
L
Analyte Present (reported value may be biased low)
(3)
Data from Oct 2011
Chester County, Pennsylvania
AR201766
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MW-105A"
,3.9
HW-02
HW-13B
% I—
: HW-13A
Feet
Groundwater Treatment Building
' \\\J "—' '
¦10.
MW-104B (1)
0\5Z~
MW-104A (1)
Tnd?"
M
HW-06 -
MW-113BN MW-113A (1)5
v2.7\lV "0.34v
- MW-115(1),
'2.42,
Former
lid^Gpunt
'Mustang^Buildirig-
MW-107A (1)
'~TNDIJ "
MW-107 B (1)
,nd'\\
Rear
Building
Former
'AlWjFrank Building
MW-112A I
7.8'
'EW-2
^EW-3 (1)
kO.72
OB-21 (1) \J
[O.f
MW-112B
0.6
-MW-114
10^
MO,'
OB-5-
;EW5j
=1r2?
OB-2S
'MW-108A OB-1S
V;LT*\
MW-111^,
MW-106 (1),.
-ND
OB-6
'ND
MW-117-
- MW-11S
O
-MW-110
D
•^'-Va«ey_e,ee((;
,\f Front \
\ Building \ ^
\
V
FormeY\\N
AIW Frank Building
)):
Notes:
At locations where the intermediate and deep wells are co-located,
the higher concentration of TCE was used to estimate the plume.
TCE concentrations have been historically higher in the axis of the
plume, but the recent data shows lower concentration due to the
in situ injections.
T C E=trichloroethene
|_ig/L=micrograms per liter
\\gst-sn'-01\HGLGISAIW_Frank\_MSIW\PP\
(4)TCE_Intermediate_Bedrock_Nov2013. mxd
3/23/2016 CNL
Source: HGL, EPA
Legend
Shallow Well
—1—
TCE Concentration Contour (|ig/L)
Intermediate Well
- 10 -
Estimated TCE Concentration Contour (|ig/L)
Deep Well
1.7
TCE Concentration (|ig/L)
ND
Not Detected
Extraction Well
(1)
Data from April 2012
(2)
Residential Well
J
Analyte Present (reported value may not be accurate or precise)
Existing Structure
Former Structure
Surface Water
Data from Dec 2011
Figure 4
TCE Concentrations for
Intermediate and Deep Bedrock Wells
November 2013
AIW Frank/Mid-County Mustang Site
Chester County, Pennsylvania
AR201767
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MW-108A
CD
>
0
CC
0
W
c
CC
0
0
>
o
_Q
03
-*—>
0
0
4—
c
o
03
>
0
LU
Former Mid-County Mustang
Former AIW Frank
i— 400
— 350
— 300
— 250
— 200
— 150
¦— 100
0 37.5 75
150
Horizontal Scale in Feet
Notes:
(1) Data from December 2011.
(2) Data from April 2012.
TCE=trichloroethene
^ig/L=micrograms per liter
\ \gst-srv-01 \HGLGIS\AIW_Frank\_MSIW\PP \
(5) Vert_Distr_TCE_Nov2013. mxd
2/11/2016 CNL
Source: HGL
Typical Borehole:
— Cased Interval
— Open or Screened Interval
A-
FX-
Lpproximate Depth
of Identified Fracture
in Open Borehole
Legend
nd Not Detected
(16) TCE Concentration (|ig/L)
TCE Concentration Contour (|ig/L)
Estimated TCE Concentration Contour (|ig/L)
j Analyte Present (reported value may not be
accurate or precise)
l Analyte Present (reported value may be biased low)
TCE Concentration (f^g/L):
1
10
30
Figure 5
Vertical Distribution
of TCE Contamination
November 2013
AIW Frank/Mid-County Mustang Site
Chester County, Pennsylvania
AR201768
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MW-108A
CD
>
0
CC
0
W
c
CC
0
0
>
o
_Q
03
-*—>
0
0
4—
c
o
03
>
0
LU
Former Mid-County Mustang
Former AIW Frank
100 —
i— 400
— 350
— 300
— 250
— 200
— 150
¦— 100
0 37.5 75 150
Horizontal Scale in Feet
Notes:
(1) Data from May 2005.
TCE=trichloroethene
^ig/L=micrograms per liter
\ \gst-srv-01 \HGLGIS\AIW_Frank\_MSIW\PP \
(6) Vert_Distr_TCE_Oct2005. mxd
2/11/2016 CNL
Source: HGL
Typical Borehole:
Cased Interval
Open or Screened Interval
Approximate Depth
of Identified Fracture
Legend
nd Not Detected
(37) TCE Concentration (|ig/L)
TCE Concentration Contour (|ig/L)
TCE Concentration (f^g/L):
1
10
FX-
in Open Borehole
Estimated TCE Concentration Contour (|ig/L)
Analyte Present (reported value may not be
accurate or precise)
30
300
Figure 6
Vertical Distribution
of TCE Contamination
October 2005
AIW Frank/Mid-County Mustang Site
Chester County, Pennsylvania
AR201769
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