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Superfund Program Region 3
Proposed Plan
North Penn Area Five Superfund Site (Operable Unit 2)
Colmar and Hatfield Township, Pennsylvania
September 2008
EPA ANNOUNCES NEW PROPOSED
PLAN FOR OPERABLE UNIT 2
The United States Environmental
Protection Agency (EPA) is issuing this
Proposed Plan to present the preferred
alternative for an interim source control
remedy to address contamination in the area
identified as Operable Unit Two (OU2) at
the North Penn Area 5 Superfund Site
(Site). EPA completed a Remedial
Investigation and Feasibility Study (RI/FS)
for the Site in July 2002. The RI identified
three primary areas of contaminated
groundwater associated with the Site. In
each of these areas, groundwater was found
to be contaminated with trichloroethene
(TCE) and related volatile organic
compounds (VOCs). Historically these
areas have been referred to by the facility or
location where contaminated groundwater
was found. The primary areas of concern
are identified as the OU1 BAE Plume; the
OU2 Stabilus Plume; and the OU3 Advance
Lane Plume.
This is the second Proposed Plan issued
by EPA for the Site. The first plan, which
was issued on July 26, 2002,-recommended
the use of chemical oxidation combined with
groundwater extraction and treatment at
each of the three OUs for the Site, including
OU2, to address contamination identified
during the RI. The 2002 Proposed Plan also
recommended use restrictions to ensure that
contaminated groundwater is not used for
drinking water purposes. EPA received
extensive comments on the 2002 Proposed
Plan. Based on these comments, EPA
conducted additional field investigations and
issued a supplemental RI. On June 25,
2004, EPA issued a Record of Decision
(ROD) selecting a cleanup plan for the OU1
and OU3 portions of the Site.
PUBLIC COMMENT PERIOD:
September 16, 2008 - October 16; 2008
ijgfwill accept written comments on the '
;d Plan'during the comment period;
IPUBL1C MEETING:
September 23,2008
£PA|will hold,a public-meeting,to explain
ttheiPfoposediPlahrf©ral and written^
[comments will also be accepted at the
^meeting. The meeting will be held at the
'Montgomery Township MuriicipakBuilding
at 7:00 p.m..
For more information, see the
Administrative Record at these locations:
iLansdale Public fcibrary « n
|301 Vine Street . . ¦
Lansdale, PA 19446; v -m
(215) 855-3228
lMontgomery:Township;MunlClpa^ Building.
I'i OO h Stump Road
iMontgomeryville, PA 18963 >
(215)393 6900
EPA-Records Center
jl650 ArcluStreet .
[Philadelphia. PA 1,9103
1(2*15), 814-315 7 for'.appointment
http ://l oggerhead .epafgov&rweb
-------
Based on review of comments received
during the public comment period on the
2002 Proposed Plan and upon further review
of the existing data, EPA has determined
that additional investigations are necessary
before a final cleanup plan can be selected
for the OU2 portion of the Site. However,
EPA is proposing an interim source control
remedy to address high levels of TCE in
groundwater found in the overburden (i.e.,
the soil and unconsolidated material
overlying the bedrock, aquifer).
This Proposed Plan summarizes the
findings of earlier investigations, provides
details on EPA's preferred remedy and
explains the reasons for this preference. In
addition, the Proposed Plan explains how
the public can participate in the decision-
making process and provides names,
addresses and telephone numbers of the
EPA contacts. Terms highlighted in this
Proposed Plan in bold italic print are defined
in a glossary of relevant technical and
regulatory terms provided at the end of this
Proposed Plan.
EPA is the lead agency for Superfund
activities at the Site. EPA, in consultation
with the Pennsylvania Department of
Environmental Protection (PADEP), will
select the interim remedy for OU2 after
reviewing and considering all written and
oral comments submitted during a 30-day
public comment period. The selected
remedy will be documented in a Record of
Decision (ROD) for OU2. The OU2 ROD
will be placed in the administrative record
for the Site.
PUBLIC PARTICIPATION
This Proposed Plan for the North Penn
Area 5 Superfund Site has been prepared by
EPA to facilitate public participation in the
decision-making process regarding
remediation of the Site. The Proposed Plan:
(1) fulfills the public notification
requirements of Section 113(k)(2)(B),
117(a), and 121(f)(1)(G) of the
Comprehensive Environmental Response,
Compensation and Liability Act of 1980, as
amended, (CERCLA), and of Section
300.430(f)(2) of the National Oil and
Hazardous Substances Pollution
Contingency Plan (NCP), 40 CFR
§ 300.430(f)(2); (2) describes the remedial
alternatives evaluated and solicits comments
on these alternatives; (3) identifies EPA's
preferred alternative and explains why EPA
prefers it; . (4) solicits community
involvement in selection of the remedy; and
(5) refers interested parties to the RI/FS,
Supplemental RI, and other Site-related
n documents in the administrative record file.
Copies of the administrative record file are
located in the information repository at the
EPA Region III offices in Philadelphia,
Pennsylvania, and online at
http: //I o ggerhead. epa. gov/arweb. The file
can also be reviewed at either of the
following locations:
Lansdale Public Library
301 Vine Street
Lansdale, PA 19446
(215) 855-3228
Montgomery Township Municipal Building
1001 Stump Road
Montgomeryville, PA 18963
(215)393-6900
EPA and PADEP recommend that the
public review these documents to gain a
more comprehensive understanding of the
Site and the Superfund activities that have
been conducted there. EPA and PADEP
also encourage the public to review and
comment on this revised Proposed Plan for
the Site. Interested parties may comment
during the public-comment period, which
begins on .September 16, 2008, and closes
on October 16, 2008. On September 23,
2008, EPA will hold a public meeting to
discuss the remedial alternatives. It will be
held at , the Montgomery Township
Municipal Building at 7:00 pm.
AR304824
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EPA, in consultation with PADEP, may
modify the preferred alternative, or develop
another alternative, if public comment
warrants such an action, or if new
information is presented.
SITE DESCRIPTION AND HISTORY
The North Penn Area 5 Superfund Site
(Site) is located in the vicinity of Colmar
and Hatfield Township, Pennsylvania in the
eastern part of Montgomery County, with a
portion of the Site extending into Bucks
County. The Site encompasses an
approximately five square-mile area
generally bounded by Richardson Road to
the southeast, Bethlehem Pike (Route 309)
to the west, Trewigtown Road to the
northwest and Schoolhouse Road to the east
(Figure 1).
\
The area is comprised of commercial
and industrial businesses, residences,
undeveloped woodland properties, parkland
and farmland. During'the 2002 RI it was
estimated that 2,900 people lived within a
one mile radius of the Site. Some area
residents utilize private wells as a source of
drinking water. In addition, two municipal
water suppliers, North Penn Water Authority
(NPWA) and North Wales Water Authority
(NWWA) have water supply wells in the
vicinity of the Site.
The Site is one of five National
Priorities List (NPL) listings made final in
March 1989 within the NPWA service
district in Montgomery and Bucks Counties.
The NPL includes sites where uncontrolled
hazardous substance releases present the
•most significant potential threat to human
health and the environment. The basis for
the listing originated in 1979 with the
detection of VOCs in the groundwater from
NPWA supply well NP-21, which was later
taken out of service. Investigations by
NPWA, PADEP (formerly known as the
Pennsylvania Department of Environmental
Resources or PADER) and EPA identified
several potential sources in the Colmar area.
The North Penn Area 5 study area initially
included eight facilities, identified as
potential sources of contamination, based on
previous activities and their proximity to
contaminated groundwater. A detailed
discussion of the investigation of these
properties is included in the RI Report.
The RI identified three separate plumes
of groundwater contamination at the Site.
The Site has been divided into OUs
according to geographical areas where
groundwater contamination was found
during the RI. The general location of each
OU is identified on Figure 2. As mentioned
above, the contamination at OU1 and OU3
is being addressed pursuant to the 2004
ROD. This Proposed Plan pertains only to
the OU2 portion of the Site, however, a brief
description of each OU is provided below.
QUI BAE Plume
The apparent source of the OU1
groundwater contamination is the facility
located on the property at 305 Richardson
Road in Colmar. Until recently, the facility
was owned by BAE Systems Information
and Electronic Systems Integration, Inc.
(BAE), formerly known as Marconi, Tracor
Aerospace .Systems, Inc. and American
Electronics Laboratory (AEL). In February
2008, the facility and the property on which
it is located, was purchased by Sensor and
Antenna Systems, Lansdale, Inc. The 67-
acre property consists of an electronics
manufacturing and testing facility which
includes several buildings. Operations at
this location, which began in 1953, included
the manufacturing of communications
equipment.
Beginning in 1979, under the
supervision of PADER, AEL conducted an
investigation which found that soils and
groundwater at the facility were
contaminated with TCE. As a result, AEL
removed an underground solvent tank and
AR304825
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excavated and treated the surrounding soils source, to create a reaction that transforms
to reduce the TCE concentrations. The the contamination into the harmless
treated soils were placed back into the byproducts of carbon dioxide and water,
excavations. AEL also ^excavated and The pre-design activities include conducting
removed six 55-gallon drums and two 1- sampling and analyses to characterize the
gallon containers from the property. groundwater geochemistry at OU1. In/
addition, BAE is conducting a pilot test to
The groundwater contamination evaluate the possible use of soil vapor
identified during the RI as the OU1 BAE extraction (SVE) and/or dual-phase
Plume appears to originate from the former extraction which combines SVE and
BAE underground solvent tank area and groundwater extraction and : treatment
extends towards the west (Figure 2). In technologies. The results of these
1986, in an effort to address this investigations-are expected to aid in the
contamination, AEL began operation of a design of the final cleanup plan for OU1.
groundwater extraction and treatment
system, which consisted of one extraction OU2 Stabilus Plume >
well located in the vicinity of the former
solvent tank. The extracted groundwater is The apparent source of the OU2
( pumped to an air stripper to remove VOC groundwater contamination is the facility
. contamination, and the treated water is located on the property at 92 County Line
discharged to an on-site tributary of the Road in Colmar. The 11-acre property
West Branch Neshaminy Creek. In 2004, includes a building, a covered storage pad
BAE expanded the extraction system by and a large paved parking lot. H & N
converting two existing monitoring wells to Packaging, Inc. (H&N), now part of the
extraction wells. The system is operated Colmar Constantia Group, has owned the
under the oversight of PADEP and the property since 1999. H&N uses the facility
Delaware River Basin Commission. to manufacture packaging materials. From
1979 to 1998 the property was owned by
In December 2006, in accordance with a Stabilus, Inc. (formerly Stabilus/Gas Spring
settlement agreement and administrative Company). Operations included the.
order on consent with EPA, BAE initiated manufacturing of gas springs used in hinged
additional investigations to better define the doors and windows. TCE was used for
extent of the QUI contaminated cleaning parts at the former Stabilus facility,
groundwater plume. These investigations
included the installation and sampling of In 1979, TCE was found in samples
new monitoring wells installed at ten collected from a sanitary sewer line
locations on the former BAE property, and originating at the facility. A video survey
geophysical and hydraulic testing to refine and pressure test, conducted in 1980,
the understanding of the hydrogeologic indicated the sewer was intact. However, a
conditions and contaminant transport later survey conducted in 1990 identified
mechanisms at OU1. BAE is also several areas where the sewer showed signs
conducting pre-design activities to better of sagging and root infiltration. In 1980,
evaluate chemical, physical and biological NPWA" representatives reported observing
treatment alternatives, including enhanced liquid leaking from a truck that was
in-situ chemical oxidation, which was pumping TCE into a tank in the loading
selected as part of the remedy for OU1 in dock area of the facility. Although much of
the 2004 ROD. In-situ chemical oxidation . the TCE was recovered, it was noted that
involves adding chemicals, such as some leaked onto the parking lot.
permanganate or hydrogen peroxide to the
4
AR304826
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Sampling conducted as part of the RI
and Supplemental RI, confirmed TCE and
related VOCs are present in the groundwater
at the former Stabilus, facility. The
groundwater contamination identified during
the RI as the OU2 Stabilus Plume appears to
originate from the loading dock area of the
former Stabilus facility and extends both to
the north onto the KEMA Powertest facility
(Powertest) and to the southwest onto the
former BAE facility (Figure 2).
The Powertest facility consists of two
buildings on an 11 -acre parcel located on the
property at 4379 County Line . Road.
Historically, Powertest conducted electrical
equipment testing at the facility. The RI
concluded that groundwater in the vicinity
of the facility may be impacted by the TCE
contamination originating at the Stabilus
facility. However, the RI also indicated that
the high levels of 1,1,1-trichloroethane
(1,1,1-TCA) detected in Powertest
monitoring well MW-2 seems to be an
anomaly and may not be related to the
Stabilus facility.
OU3 Advance Lane Plume
The source of the groundwater
contamination identified during the RI as the
OU3 Advance Lane Plume has not been
identified, but appears to originate in the
vicinity of Advance Lane and Enterprise
Lane in Colmar (Figure 2). In 1998, as part
of the RI, EPA conducted sampling of water
supply wells in the area east of Bethlehem
1 Pike (Route 309). The sampling results
indicated that TCE and related VOCs were
present in water supply wells and.
monitoring wells at several commercial
facilities located on Advance Lane,
Enterprise Lane and Bethlehem Pike. In
2000, EPA connected four commercial
facilities with TCE-contaminated water
supply wells to public water. In 2002, EPA
conducted sampling of water supply wells in
the area west of Bethlehem Pike. No
contaminants related to the Site were
detected in the water supply wells located
west of Bethlehem .Pike during the 2002-
sampling event.
In April 2007, EPA conducted'
additional sampling of residential and
commercial supply wells in the area.
Although trace levels of organic and
inorganic compounds were detected in
certain water samples, none of the
constituents were reported at levels that
exceeded risk-based concentrations for
residential tap water. EPA also installed
four new monitoring wells in an attempt to
identify 1 the source of contaminated
groundwater and to aid in defining the
extent of groundwater contamination
associated with OU3. The recent sampling
results from new and existing monitoring
wells indicate that TCE levels have
decreased. EPA plans to conduct a pilot test
to better evaluate the use of enhanced in-situ
chemical oxidation selected in the 2004
ROD. The results of the activities discussed
above are expected to aid in the design of
the final cleanup remedy for OU3.
SITE CHARACTERISTICS
In 1997, EPA initiated a Remedial
Investigation (RI) and Feasibility Study (FS)
at the Site. Initial field activities began in
April 1998 and were completed in June
2002. . EPA conducted additional field
investigations and issued a supplemental RI
in September 2003. Activities included
identification of existing groundwater wells
and installation of new groundwater
monitoring wells at 31 locations across the
Site. The approximate well locations are
identified on Figure 3. EPA collected
groundwater samples and conducted aquifer
pump tests to better understand the regional
groundwater flow patterns and their
influence on the movement of the
contamination. Investigations also included
sampling soil in suspected source areas and
sampling of surface water and sediments in
nearby streams.
AR304827
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The objective of the investigations was
to characterize Site conditions, determine
nature and extent of contamination, and
assess risks to human health and the
environment. As discussed earlier, the RI
identified three primary areas of
contaminated groundwater identified as
OU1, OU2, and OU3 (Figure 2). The
investigations are discussed in detail in. the
RI reports. The RI and Supplemental RI
findings regarding Site geology,
hydrogeology, and extent of contamination
are briefly summarized below:
• The soils investigation included eight
facilities which had been identified as
potential sources of contamination.
Although the majority of the facilities
had isolated detections of low level soil
contamination, the investigation did not
identify any contaminated soil source
areas that appeared to be responsible for
the groundwater contamination.
• Surface water bodies in the vicinity of
the Site include the West Branch of the
Neshaminy Creek, its Western and
Eastern tributaries and an unnamed
tributary to the Neshaminy Creek.
Sampling results indicated that low
levels of volatile and semi-volatile
organic compounds were present in
surface water at the Site. However,
neither TCE nor any of its degradation
products were detected. There were
widespread detections of various
inorganic compounds, although there
was generally no statistical difference
between upstream location data and
downstream locations. The RI
concluded that the presence of
inorganics, including metals, in the
surface water is influenced primarily by
natural or anthropogenic sources (e.g.,
atmosphere deposition or urban runoff).
• Sediments in area streams and
tributaries were found to contain a wide
variety of low concentration metals,
pesticides and polycyclic aromatic
hydrocarbons. However, the frequency
and distribution of these contaminants
appeared to be random. An evaluation
of the sediment sampling data indicated
that there was generally no statistical
difference between the sampling data
collected upstream of the Site and the
downstream sample data. As with the
surface water sampling, the results
indicated -that for the most part, the
sediment contamination appears to be
influenced primarily by anthropogenic
sources (e.g., highway, parking lot and x
residential runoff). Notable exceptions
included elevated levels of copper and
cadmium detected in the tributary
channel downstream from the BAE
Systems facility.
• The Site is underlain by sedimentary
rocks of the Brunswick Formation and
the Lockatong Formation. The
overburden layer - consists of soil and
highly weathered unconsolidated
bedrock. The underlying aquifer is
predominantly fractured bedrock.
• The overburden layer at the Site is
typically between 10 to 40 feet thick.
The overburden is comprised of soil and
unconsolidated weathered bedrock
(shale) and consists of silt, clay, and
some sand. It becomes progressively
harder with depth. The overburden is
generally thin and discontinuous
throughout the Site (usually less than 20
feet thick), although in some areas
located near drainage features, it can be
20 to 40 feet thick. Much of the
overburden is dry, but may be
seasonally wet. Thicker sections of
overburden may contain a year round
water-saturated layer.
• Groundwater underlying the Site is
found in both the shallow
unconsolidated overburden and the
underlying _ fractured bedrock.
AR304828
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Groundwater flow in the overburden
generally follows the local topography,
while flow in the bedrock aquifer varies
across the Site. The overburden and •
bedrock groundwater systems appear to
be hydrogeologically connected with
groundwater levels and flow patterns
fluctuating with local pumping and
seasonal variation in recharge.
• TCE and related VOCs are present in
the groundwater underlying the former
BAE property. Groundwater samples
collected from shallow monitoring
wells installed in the overburden
showed TCE concentrations up to 1,000
micrograms per liter (ug/1) with median
concentrations ranging between 20 - 50
ug/1. TCE groundwater concentrations
up to 320 ug/1 were detected in shallow
monitoring wells installed in the
bedrock aquifer. TCE concentrations in
samples collected from a limited
number of deeper bedrock monitoring
wells ranged from 1 ug/1 to 6 ug/1. •
• Groundwater quality at the former BAE
facility appears to be impacted by two
separate TCE plumes. The southern
plume appears to originate from the
former BAE underground solvent tank
area and extends towards the west. A
second TCE plume, located on the
northwestern portion of the property,
may originate from a source on the
former Stabilus facility. However, it is
possible the contamination may be
associated with an unknown source in
the northwestern corner of the former
BAE property. TCE concentrations in
shallow monitoring wells installed in •
the overburden and in the bedrock
aquifer in the vicinity of the former tank
location are decreasing, most likely" a
result of the ongoing operation of the
groundwater, pump and treat system.
TCE concentrations in shallow
monitoring wells installed in the
bedrock aquifer on the northwestern
portion of the property remain high.
TCE and related VOCs are present in
the groundwater underlying the former
Stabilus facility. TCE contaminated
groundwater is present in the vicinity of
the loading dock area of the former
Stabilus facility and extends both to the
north onto the Powertest facility and to
the southwest onto the former BAE
facility. Samples collected from
shallow monitoring wells installed in
the overburden showed TCE
groundwater concentrations levels up to
3,600 ug/1. TCE groundwater
concentrations up to 3,800 ug/1 were
detected in shallow wells installed in
the bedrock aquifer. TCE
concentrations in samples collected
from a limited number of deeper
bedrock wells installed on the property
ranged from non-detect to 7 ug/1.
TCE was found in the water samples
collected from several commercial
supply wells in the Advance Lane area
at concentrations up to 300 ug/1. TCE
was also detected in a monitoring well
installed in the bedrock aquifer at
concentrations up to 360 ug/1. The
source or sources of the groundwater
contamination have not been
identified. Although VOCs were
detected in surrounding supply wells, the
concentrations did not exceed
Maximum Contaminant Levels (MCLs)
established under the Safe Drinking
Water Act.
The 2003 Supplemental RI provided
additional information regarding the
nature and extent of contamination in
the area between the former Stabilus
and former BAE facilities. Consistent
with the findings of the original RI, the
supplemental investigation found that
high concentrations of TCE are present
AR304829
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in the groundwater in the vicinity of the
loading dock area of the former Stabilus
facility. Although groundwater found
in the overburden appears to be
intermittent, the supplemental
investigation identified a continuously
saturated section of overburden that
extends from the former Stabilus
facility to the northwestern portion of
the former BAE property. Water level
data from the wells installed in the
overburden indicates both westerly and
southwesterly flow components,
demonstrating flow from the parking lot
area of the former Stabilus facility
towards the former BAE property. In
addition, sampling results indicate the
overburden contains TCE throughout
the length of this saturated zone
extending from the vicinity of
monitoring well RI-25, located near the
loading dock at the former Stabilus
facility, to monitoring well RI-31,
located in the northwestern corner of
the former BAE property (Figure 4).
Although, it is noted that ¦ TCE
concentrations varied across the area.
The highest TCE concentration
observed during the 2003. direct push
sampling of the overburden was found
at sample location DP4, located on the
former Stabilus facility, at a
concentration of 7,600 ug/1. The results
of the supplemental investigation
; indicate that the TCE detected in the.
northwestern corner of the former BAE
facility in the vicinity of RI-31 could be
the result of migration of contaminated
groundwater from a source located on
the former Stabilus facility, although
there could be another source:
SUMMARY OF SITE RISKS
The RI included a risk assessment to
identify the potential risks to human health
and the environment due to exposure to
chemicals identified in surface and
subsurface soils, sediment, surface water
and groundwater associated with the Site.
The risk assessment evaluated the potential
risks from exposure to contamination found
in these media both site-wide and at each of
the eight facilities included in the initial
investigation. The assessment evaluated
human health risks and ecological risks.
Human Health Risks
The results of three rounds of sampling,
conducted from 1998 to 2000, were
evaluated to determine the potential
chemicals and media of concern, and
populations potentially at risk. Based on the
initial screening step, the risk assessment
identified several VOCs and metals as
chemicals of potential concern (COPC).
The concentrations of the COPC were
compared to background levels and various
risk or hazard thresholds to identify the final
chemicals of concern (COC). Based on the
concentrations present at the Site, four
VOCs were identified as final COC. Table
1, on the following page lists the COPC and
the final COC identified at the Site.
The risk assessment evaluated the
potential risks from exposure to the
chemicals found in site media (soil,
sediment, surface water and groundwater)
both site-wide and at each individual
facility. An exposure assessment was then
conducted to estimate the actual (current)
and potential (future) human exposure to the
various site media, the frequency and
duration of these exposures, and the
pathways that result in human exposure.
The exposure assessment included
conservative estimates of exposure for both
current and future land-use assumptions
across the Site. The potentially exposed
populations evaluated as part of the initial
site-wide exposure assessment included the
following groups:
• Employees of on-site and nearby
commercial and industrial facilities
(current and future)
AR304830
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• Visitors who may use groundwater for
water supply (future)
• Construction workers who may be
working at various facilities (current'
and future)
Residents (adults and child) who live on
or adjacent to the Site and may use
nearby streams for recreational
purposes (current and future)
Adult and child residents (future)
• Commercial businesses or residents
using groundwater for water supply
purposes (future)
TABLE 1: LISTING OF CHEMICALS OF POTENTIAL CONCERN
Initial Chemicals? of Potential ;^
Reason for Selection or Deletion -
« Final Chemicals
MC L*
Concern -Groundwater
of Concern
TM)
Arsenic
Background
Antimony
Background
Barium
Background
Cadmium
Below risk or hazard thresholds
Iron
Background
/
Lead
Background
Manganese
Background
Nickel
Background
Thallium
Background
Trichloroethene
X
5
1,2 Dichloroethene (total)
Below risk or hazard thresholds
1,1 Dichloroethene
X
7
Tetrachloroethene
X
5
Chloroform
Below risk or hazard thresholds
1,1 Dichloroethane
Below risk or hazard thresholds
N-Nitroso di n propylamine
Below risk or hazard thresholds
Deldrin ^
Below risk or hazard thresholds
1,1,1 Trichloroethane
Below risk or hazard thresholds
1,2 Dichloroethane
X
5
1,1,2 Trichloroethane
Below risk or hazard thresholds
Carbon Tetrachloride
Below risk or hazard thresholds
Heptachlor epoxide '
Below risk or hazard thresholds
*MCL = Maximum Contaminant Level
The routes of exposure evaluated
included dermal absorption, ingestion and
inhalation. All of the 2002 RI sampling data
were included in the evaluation. Daily
chemical intakes were calculated for each
exposure route for each , of the populations
identified above, as appropriate.
Risk assessments typically rely on
existing information developed for specific
chemicals to help determine the types of
adverse effects from exposure. The risk
assessment studied both the carcinogenic
(cancer) and non-carcinogenic risks to
humans based on the levels of the
contaminants found at the Site. The NCP
establishes a range of acceptable levels of
carcinogenic risk for Superfund sites that
range between one in 10,000 and one in one
AR304831
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million additional cancer cases if cleanup
action is not taken at a site. Expressed in
scientific notation, this translates to an
acceptable risk range of between 1E-04 and
1E-06 over a defined period of exposure to
site related contaminants. In addition to
carcinogenic risk, chemicals that are
ingested, inhaled or dermally absorbed may
present non-carcinogenic risks to different-
organs of the human body. The non-
carcinogenic risks or toxic effect are
expressed as a Hazard Index (HI). If a HI
is less than one (1.0), it is interpreted to
mean that the risk of a non-carcinogenic
injury /is low. EPA considers a HI
exceeding one (1.0) to be an unacceptable
non-carcinogenic risk.
As discussed above, the risk assessment.
evaluated the potential risks from exposure
to contamination found in site media (soil,
sediment, surface water and groundwater)
both site-wide and at each individual
facility. The assessment identified an
unacceptable human health risk associated
with the areas identified as OU1, OU2 and
OU3. Groundwater was identified as the
primary media of concern. Although the
"driving" pathway for human risk was
contaminated groundwater, the calculations
for populations at risk included all site
media and potential pathways. A more
detailed discussion of the human health risk
assessment can be found in Appendix M of
the RI Report. The potential human health
risks associated with exposure to
contaminated media found at OU2 are
summarized below.
The current groundwater-use scenario
was not evaluated since groundwater is not a
current source of drinking water at OU2.
However, the future groundwater-use
scenario was evaluated, since groundwater
could be used in the future. The future
groundwater-use scenario assumed that
workers and residents could use the
groundwater underlying the OU2 portion of
the Site as a future drinking water supply.
The calculations included in the residential
use scenario also included dermal and
inhalation exposure from bathing activities.
The cumulative carcinogenic or cancer
risk to future workers due to exposure to all
contaminated media (soil, sediment, surface
water and groundwater) was identified at
2.7E-03 which translates to about 27
additional cancer cases for every 10,000
people exposed. The Risk Assessment also
identified a HI for non-carcinogenic risk for
future workers at 6.0E+01 or 60 due to
exposure to all contaminated media. The
cumulative carcinogenic risk to future adult
residents due to exposure to all
contaminated media was identified at 4E-02
which translates to 4 additional cancer cases
per every 100 people exposed. The
cumulative, carcinogenic risk to a future
child resident was not included because the
calculated risk shown for future adult
residents is based on a total lifetime risk
which includes the child and adult. The
Risk Assessment also identified a HI for
future adult and child residents at 3.2E+02
or 320 and 7.7E+02 or 770, respectively.
Each exposure scenario discussed above
exceeds EPA's acceptable EPA's acceptable
range of 1E-04 to 1E-06 for carcinogenic
risks and EPA's HI for non-carcinogenic
risk of 1.0.
Ecological Risks
An ecological risk assessment was
performed to identify the potentially
affected natural environment, distribution of V
contamination, fate and transport of
contaminants, exposure pathways, and to
develop a list of contaminants of potential
ecological concern. The Risk Assessment
did not identify any ecological risks at OU2
due to the lack of complete exposure
pathways to the contaminated groundwater.
A complete discussion of the ecological risk
assessment can be found in Appendix M of
the 2002 RI Report.
AR304832
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SCOPE AND ROLE OF THIS ACTION
As discussed earlier, this is the second
Proposed Plan issued by EPA for the Site.
The first plan, issued on July 26, 2002,
recommended the use of chemical oxidation
combined with groundwater extraction and
treatment at each of the three OUs for the
Site, , including OU2, to address
contamination identified during the RI. The
2002 Proposed Plan also recommended use
restrictions to ensure that contaminated
groundwater is not used for drinking water
purposes. On August 7, 2002, EPA held a
public meeting to present the findings of the
RI/FS and to discuss the proposed cleanup
plan for the Site. EPA received extensive
comments on the 2002 Proposed Plan.
Based on these comments, EPA conducted
additional field investigations and issued a
supplemental RI. - On June 25, 2004, EPA
issued a ROD, hereinafter, 2004 ROD,
selecting a cleanup plan for the OU1 and
OU3 portions of the Site. In accordance
with the 2002 Proposed Plan, the 2004 ROD
called for employing in-situ chemical
oxidation to address contamination in the
OU1 and OU3 source areas while
controlling migration of contamination
through groundwater extraction and
treatment. The components of the remedy
selected for OU1 and OU3 are described in
detail in the 2004 ROD. The response
actions selected for OU1 and OU3 in the
2004 ROD remain unchanged.
Based on review of comments received
during the public comment period on the
original Proposed Plan and upon further
review of the existing data, EPA has
determined that additional investigations are
necessary before a final cleanup plan can be
selected for OU2. However, EPA is
proposing an interim source control remedy
to address the high levels of TCE in the
groundwater in the overburden that appears
to originate from the loading doclc of the
former Stabilus facility and may be a source
of the contamination found in the
overburden on the northwestern portion of
the former BAE facility and in the
underlying bedrock aquifer.
¦i
Stabilus Inc. and Honeywell
International, Inc., two of the potentially
responsible parties at the Site, have
proposed the use of enhanced in-situ
bioremediation to address contamination at
OU2. The proposed treatment area is
identified on Figure 5. EPA evaluated the
proposal and found enhanced in-situ
bioremediation to be a viable treatment
technology to address contamination in the
OU2 overburden. Furthermore, given the
size of the area requiring treatment,
enhanced in-situ bioremediation is expected
to be more cost effective than in-situ
chemical oxidation in addressing the VOC
contamination in the OU2 overburden.
Therefore, EPA is proposing to employ
enhanced in-situ bioremediation as part of
the interim source control remedy to address
contamination in the OU2 overburden where
the highest concentrations of TCE have been
observed. As discussed above, EPA has
determined that further investigations must
be conducted as part of the interim remedy.
Groundwater investigations including
sampling of the overburden groundwater,
installation of new bedrock monitoring wells
and hydrogeological and chemical testing
will be conducted to delineate the extent of
contamination associated with the Stabilus
loading dock area and the contamination in
the northwestern corner of the former BAE
property. In addition, an evaluation of the
potential for vapor intrusion into structures
on the former Stabilus property will be
conducted. If, based on this evaluation,
vapor intrusion is found to be a problem
additional response activities will likely be
required. The interim remedy also includes
use restrictions to prevent exposure to
contaminated groundwater.
These actions are anticipated to be
neither inconsistent with, nor preclude
AR304833
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implementation of, a final cleanup remedy.
EPA, in consultation with the
Commonwealth of Pennsylvania, will select
a final comprehensive remedy for OU2,
based on the additional site characterization
data and the results of the implementation of
the interim source control remedy.
REMEDIAL ACTION OBJECTIVES
The Remedial Action Objectives
(RAOs) for the OU2 interim source control
remedy are to:
• Restore groundwater quality in the
overburden impacted by contamination
originating from the former Stabilus
loading dock source area to meet MCLs;
• Prevent or minimize further migration of
contaminants from yhe former Stabilus
loading dock source area;
• Prevent future exposure to contaminated
groundwater at concentrations in excess
of MCLs; and
• Determine the extent of groundwater
contamination associated with the
former Stabilus loading dock area and
the northwestern corner of the former
BAE property.
• Determine whether vapor intrusion is a
potential source of contamination.
Based on the results of the RI, the OU2
overburden groundwater appears to be
hydrogeologically connected to the bedrock
aquifer. Therefore, cleanup of the OU2
overburden impacted by contamination from
the former Stabilus loading dock area shall
continue until MCLs for the chemicals
identified below are attained in groundwater
found in the overburden. Table 2 below
presents the performance standards for the
remediation portion of the OU2 interim
source control remedy. These objectives are
consistent with the RAOs identified in the
2004 ROD for OU1 and OU3 which are to
restore " groundwater quality in the
overburden and the bedrock aquifer and to
reduce concentrations of contamination in
the groundwater to MCLs or below.
)
TABLE 2: PERFORMANCE STANDRARDS FOR OU2 GROUNDWATER
; . " Chemical ' . , _ „
- -V;'Units s
MCL
Tetrachloroetnene
Hg/L
5
Trichloroethene
Hg/L
5
1,1,1-Trichloroethane
Hg/L
200
1,1-Dichloroethene
Hg/L
7
Cis-l,2-Dicloroethene
Hg/L
70
Trans 1,2 -Dichloroethene
Mg/L
100
1,2-Dichloroethane
H&/L
5
Vinyl Chloride
Hg/L
2
The chemicals listed above have been detected at the Site or may be a breakdown product of chemicals
which are present at the Site. While the performance standards may provide a safe exposure level for each
individual chemical, as determined by the Safe Drinking Water Act (SDWA), they may not necessarily
indicate an acceptable health risk if all the compounds are present at the MCL as listed. Thus, EPA
reserves the right to modify the specific performance standards if it is determined that the cumulative risk
associated with exposure to contaminants remaining in the groundwater exceeds acceptable levels.
AR304834
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SUMMARY OF REMEDIAL
ALTERNATIVES
The proposed interim remedial
alternatives for the OU2 portion of the Site
are presented below.
Common Elements
As discussed, EPA has determined that
farther investigation is required before a
final remedy can be selected for OU2.
Therefore, with the exception of the "No
Action" alternative (Alternative 1), each
alternative includes additional investigations
necessary to determine the extent of
contamination associated with OU2.
Groundwater investigations, including
sampling of the overburden and the
installation of new bedrock monitoring wells
and hydrogeological and chemical testing,
would be conducted as part of a pre-design
investigation. These investigations are
expected to delineate the VOC
contamination in the former Stabilus loading
dock source area and the VOC
contamination in the northwest corner of the
former BAE facility. In addition, an
evaluation of the potential for vapor
intrusion into structures located on the
former Stabilus property will be conducted.
If, based on the initial evaluation, vapor
intrusion is found to be a problem additional
response activities will likely be required.
Both Alternatives 2 and 3 would require
Institutional Controls (ICs) (e.g.,
ordinances, easements, covenants, title
notices, or land use restrictions through
orders or agreements with EPA) be
established to protect the integrity of the
interim remedy and ensure that the
contaminated groundwater associated with
OU2 is not used for drinking water
purposes. EPA expects to restrict
installation of drinking water supply wells
on parcels impacted by contamination
associated with OU2 through orders or
agreements with the property owners. EPA
will coordinate these efforts with PADEP
and the Montgomery County Health
Department (MCHD). An Institutional
Control Implementation and Assurance Plan
(ICIAP) will be developed for OU2 during
the pre-design investigation to ensure
appropriate controls are drafted,
implemented and monitored. Final ICs will
be developed for OU2, based on the results
of the interim source control remedy.
ALTERNATIVE 1: No Action
Estimated Capital Cost: SO
Estimated Annual O&M Cost: $0
Estimated Total Present Worth Cost: $0
The No Action alternative is included for
consideration as a potential response action,
as required by the NCP, in order to compare
it to the other remedial alternatives. The No
Action alternative does not utilize treatment
technologies to reduce contaminant
mobility, toxicity, or volume. Furthermore,
the No Action alternative does not prevent
future exposure to contaminated
groundwater.
ALTERNATIVE 2:
In-situ Chemical Oxidation
Estimated Cost of Investigations: $911,000
Estimated Capital Cost: $3,223,253
\
Estimated Annual O&M Cost: $40,000
Estimated Total Present Worth Cost: $4,415,196
' This alternative includes the common
elements summarized earlier. Sampling
would be conducted to delineate the extent
of VOCs in the overburden groundwater in
the former Stabilus loading dock source area
AR304835
-------
and in the northwest corner of the former
BAE facility. For costing purposes, it is
assumed that 30 groundwater samples would
be collected in each of the two areas from
temporary monitoring wells installed in the
overburden via direct push technology. In
addition, new bedrock monitoring wells
would be installed in each area to help
determine the extent of groundwater
contamination in the bedrock aquifer. For
costing purposes, it is assumed that
approximately 6 bedrock wells would be
installed at each of the two locations.
Geophysical fogging, packer and chemical
testing would be conducted on individual
boreholes before the wells are completed.
These tests should provide detailed
information regarding groundwater flow and
contaminant distribution in the bedrock
aquifer. The final number, location and
design of the overburden and bedrock
monitoring wells, would be determined in
the pre-design investigation.
Soil gas, sub-slab and/or indoor air
sampling would be conducted to determine
if the VOC groundwater contamination
associated with OU2 is contributing to vapor
intrusion in buildings overlying the
groundwater contamination. Sampling
locations and methods would be determined
during the pre-design investigation.
In addition to the above investigations,
this alternative would employ enhanced in-
situ chemical oxidation to address highc
levels of TCE in the overburden in the
loading dock source area on the former
Stabilus facility. The proposed overburden
treatment area is identified on Figure 5. The
proposed treatment area is approximately
'y
56,000 square feet (ft ) or just under one and
one half acres. • The final treatment area,
where TCE concentrations in the overburden
are equal to'or greater than 100 ug/1, would
be delineated during the pre-design
investigation.
In-situ chemical oxidation involves the
injection of an oxidant (permanganate,
persulfate, peroxide and/or ozone) into the
contaminated areas to provide chemical
destruction of the organic contaminants. At
OU2, the chemical oxidation process would
be expected to convert TCE and the related
VOCs to carbon dioxide and water. The
number of injections and timeframe for
• treatment varies depending on site
conditions. For costing purposes, it is
assumed that the oxidant would be injected
via a- direct push technology at
approximately 500 locations to a depth of
approximately 20 feet. It is further assumed
that treatment would involve two rounds of
injection of an oxidant during an 18 month
timeframe. The first round would provide
the primary treatment, and the second
injection would act as a polishing step.
Monitoring would be conducted to evaluate
the effectiveness of chemical oxidation in'
N achieving the groundwater cleanup goals
identified in Table 2, in the overburden, as
well as to evaluate any impact to the
groundwater quality in the underlying i
bedrock aquifer. After a period of two years
following the first round of injections, EPA
would evaluate the results of the in-situ
remediation to determine whether chemical
oxidation is effectively reducing the
concentrations of VOCs in the overburden
source area. For costing purposes, it is
assumed that monitoring would be
conducted for up to ten years.
ALTERNATIVE 3:
Enhanced In-situ Bioremediation
Estimated Cost of Investigations: $911,000
Estimated Capital Cost: $1,334,294
Estimated Annual O&M Cost: $40,000
Estimated Total Present Worth Cost: $2,526,237
1.4
AR304836.
-------
This alternative would include the
additional groundwater investigation
activities, the vapor intrusion assessment
and the institutional controls discussed
under the common elements and described
in greater detail under Alternative , 2.
However, instead of in-situ chemical
oxidation, this alternative would employ
enhanced in-situ bioremediation to address
the high levels of TCE in the overburden
in the loading dock source area on the
former Stabilus facility. The proposed
overburden treatment area is the same area
identified in Alternative 2 (Figure 5). The
final treatment area, where TCE
concentrations in the overburden are equal
to or greater than 100 ug/1, would be
delineated during the pre-design
investigation. '
Enhanced in-situ bioremediation
systems designed to remediate VOCs in
groundwater typically involve input ofJan
organic source, nutrients, and/or microbial
cultures to stimulate degradation. As with
in-situ chemical oxidation, the number of
injections and timeframe for treatment
varies depending on site conditions. For
costing purposes, it is assumed that the
material will be injected via a direct push
technology at approximately 250 locations
to a depth of approximately 20 feet. It is
anticipated that treatment would involve
three injections. The first two injections
would involve the addition of an organic
substrate such, as such soybean oil, which
should help support the growth of
microorganisms that have the ability to
break down the TCE and related chlorinated
compounds. Once the soybean oil is
dispersed throughout the contaminated
portion of the overburden, selected nutrients
and microbial cultures would be injected to
further enhance biodegradation. It is
assumed that three rounds of injection would
occur during a 24 month timeframe.
Monitoring would be conducted to
evaluate the effectiveness of the alternative
in achieving the groundwater cleanup goals
identified in Table 2 in the overburden, as
well as monitoring to evaluate any impact to
the groundwater quality in the underlying
bedrock aquifer. After a period of two years
following the first round of injection, EPA
will evaluate the results of the in-situ
remediation to determine whether
bioremediation is effectively reducing the
concentrations of VOCs in the overburden
source area. For costing purposes, it is
assumed that the monitoring would be
conducted for up to ten years.
EVALUATION OF THE INTERIM
SOURCE CONTROL REMEDIAL
ALTERNATIVES FOR OU2
This section of the Proposed Plan
profiles the relative performance of each
alternative against the evaluation criteria,
noting how it compares to the other options
under consideration. The alternatives
described in this proposed plan were
evaluated using the criteria set forth in 40
C.F.R. 300.430 (e)(9)(iii). The criteria fall
into three groups described as follows:
1 Threshold criteria are requirements
that each alternative must meet in
order to be eligible for selection.
2 Primary balancing criteria are used
to weigh major trade-offs among
alternatives.
3 Modifying criteria are formally
considered after public comment on
the Proposed Plan. In the final
balancing of trade-offs between
alternatives upon which the final
remedy selection is abased, modifying
criteria are of equal importance to
the balancing criteria.
15
AR304837
-------
The evaluation criteria are summarized as follows:
EVALUATION CRITERIA FOR SUPERFUND REMEDIAL ALTERNATIVES
Threshold Criteria
Overall Protectiveness of Human Health and the Environment addresses whether an alternative
eliminates, reduces, or controls threats to public health and the environment through institutional controls,
engineering controls, or treatment.
Compliance with Applicable or Relevant and Appropriate Requirements (ARARs) addresses whether
the alternative will meet the requirements of Federal and State environmental statutes, regulations, and
other requirements that pertain to the site, or whether a waiver is justified.
Primary Balancing Criteria
Long-term Effectiveness and Permanence addresses the ability of an alternative to maintain protection
of human health and the environment over time, once cleanup goals have been met.
Reduction of Toxicity, Mobility, or Volume of Contaminants through Treatment addresses 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.
Short-term Effectiveness addresses the period of time needed to implement an alternative and the risks
the alternative poses to workers, residents, and the environment during implementation, until cleanup
goals are achieved.
Implementability addresses the technical and administrative feasibility of implementing the alternatives,
including factors such as the relative availability of goods and services.
Cost includes estimated capital and annual operations and maintenance costs, as well as present worth
cost. Present worth cost is the total cost of an alternative over time in terms of today's dollar value. Cost
estimates are expected to be accurate within a range of +50% to -30%.
Modifying Criteria
State/ Support Agency Acceptance considers whether the State agrees with the EPA's analyses and
recommendations, as described in the RI/FS and Proposed Plan.
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. EPA's responses to public comments are addressed in the Responsiveness Summary section
of the Record of Decision.
1. Overall Protection of Human Health
and the Environment
Alternative 1 (No Action) would do
nothing to reduce the risks associated with
16
exposure to contaminated groundwater.
Since the alternative would not be protective
of human health and, therefore, does not
satisfy this threshold criterion, it will not be
considered further in this analysis.
AR304838
-------
Both Alternative 2 (In-situ Chemical
- Oxidation) and Alternative 3 (In-situ
Bioremediation) would address VOCs in the
OU2 overburden impacted by the former
Stabilus loading dock source area via in-situ
treatment technologies. Each attempts to
control any release of contaminants from the
overburden. Both alternatives are expected
to reduce contamination in the overburden;
however, there is some uncertainty
associated with both alternatives since the
technologies are still developing and site
specific conditions will govern their
1 effectiveness.
Each alternative includes groundwater
monitoring to evaluate its effectiveness in
achieving performance standards in the
overburden as well as its effect on
groundwater quality in the underlying
bedrock aquifer. Each alternative also
includes additional investigations necessary
to determine the extent of\ contamination
associated with OU2. Each alternative
requires ICs to protect the integrity of the
interim remedy and prevent exposure to
contaminated groundwater and, as such, is
expected to be protective of human health
and the environment in the short term, and
the ICs should provide adequate protection
until the additional site investigations are
completed and a final ROD is Issued.
2. Compliance with ARARs
This criterion evaluates whether the
alternatives would meet all of the Applicable
or Relevant and Appropriate Requirements
(ARARs) of other environmental statutes
and/or provide grounds for invoking a
waiver. CERCLA requires that remedial
actions at least attain legally applicable or
relevant and appropriate cleanup standards,
standards of control, and other substantive
environmental protection requirements,
criteria or limitations promulgated under
Federal or State law, which are collectively
referred to as "ARARs", unless such
ARARs are waived under CERCLA Section
121(d)(4), 42 U.S.C. § 9621(d)(4), and the
NCP at 40 C.F.R. § 300.430(f)(l)(ii)c)).
"Applicable" requirements are those
cleanup standards, standards of control, and
other substantive environmental protection
requirements, criteria or limitations
promulgated under Federal or State law that
specifically address a hazardous substance,
pollutant, contaminant, remedial action,
location, or other circumstance at a
CERCLA site. "Relevant and appropriate"
requirements are those requirements that,
while not legally "applicable," address
problems or situations sufficiently similar to
those encountered at the site that their use is
well suited to the particular site. Only those
State standards that are promulgated, are
identified by the State in a timely manner,
and are more stringent than federal
requirements, may be applicable or relevant
and appropriate. ARARs may relate to the
substances addressed by the remedial action
(chemical-specific), to the location of the
site (location-specific), or the manner in
which the remedial action is implemented
(action-specific).
In addition to applicable or relevant and
appropriate requirements, the lead agency
may, as appropriate, identify other
advisories, criteria, or guidance to be
considered for a particular release. The "to
be considered" (TBC) category consists of
advisories, criteria, or guidance that were
developed by EPA, other federal agencies or
states that may be useful in developing
CERCLA remedies.
Both Alternative 2 (In-situ Chemical
Oxidation) and Alternative 3 (In-situ
Bioremediation) are expected to comply
with all state and federal ARARs. The
following discussion identifies the ARARs
relating to the alternatives discussed herein.
On-site actions (i.e., within the areal extent
of contamination and all suitable areas in
very close proximity to the contamination
necessary for implementation of the
AR304839
-------
response action) need comply only with the
substantive aspects of ARARs, not with the
corresponding administrative requirements
(e.g., consultation, issuance of permits,
' documentation, record keeping and
enforcement).
Chemical Specific ARARs
The Maximum Contaminant Levels (MCLs)
for public drinking water supplies
established under the Safe Drinking Water
Act (SDWA), 42 U.S.C. §§ 300f-300j, and
set forth, at 40 CFR §§ 141.50, 141.51,
141.61, and 141.62, are considered to be
, relevant and appropriate standards for
groundwater cleanups under the Superfund
program. Groundwater at the OU2 portion
of the Site exceeds the MCLs for various
contaminants. Each of the treatment
alternatives (2 and 3) would be expected to
achieve MCLs in the overburden
groundwater. Table 2 presents the
performance standards for the remediation
portion of the OU2 interim source control
remedy.
PADEP has identified the Pennsylvania
Land Recycling and Environmental
Remediation Standards Act (Act 2), 35 P.S.
§ 6026.101, et seq., as an ARAR. Act 2
provides for the promulgation of
remediation standards for cleanup of
contaminated sites in the Commonwealth of
Pennsylvania. However, EPA has
determined that Act 2's Statewide Health
Standards for groundwater do not, on the
facts and circumstances of the proposed
remedy, impose any requirements more
stringent than the federal standard.
Location Specific
No location specific ARARs were identified
for either alternative.
Action Specific ARARs
The Pennsylvania Fugitive Emissions
Regulations, 25 Pa. Code §§ 123.1-.2,
establish opacity limits for visible air
emissions and are applicable to the dust
control measures to be employed during all
on-site construction work. Each treatment
alternative (2 and 3) is expected to comply
with this requirement.
The regulations of the Underground
Injection Control (UIC) Program, 40 C.F.R.
§§ 144.1(g), 144.11, 144.12(a), 144.82,
146.6, 146.7, 146.8, 146.10(c), are
applicable to the installation of injection
wells and to the in-situ alternatives proposed
for the source area. The UIC regulations
define and establish five classes of
introduction wells. Generally, Class V wells
are shallow discharge or disposal wells,
storm water or agricultural drainage
systems, or other devices that are used to
release fluids into or above an underground
source of drinking water. In Pennsylvania,
EPA Region III has primacy in matters
involving UIC and the PADEP defers to
EPA in implementing the UIC program.
Each alternative is expected to comply with
these requirements.
The Pennsylvania Stormwater Management
Act, 32 P.S. § 680.13, requires the
implementation of measures to control
stormwater runoff during construction and
remediation activities. Each alternative is
expected to comply with this requirement.
The Pennsylvania Erosion and Sediment
Control Regulations, 25 Pa. Code §§
102.4(b), 102.11, 102.22, set forth measures
to limit soil erosion during any earth
disturbance activities. Each alternative is
expected to comply with this requirement.
18
AR304840
-------
(
Long-term
Permanence
Effectiveness
and
Although this Proposed Plan sets forth
an interim remedy, both treatment
alternatives (2 and 3) provide some long-
term protection of human health and the
environment because they would provide for
treatment of VOCs in the overburden,
thereby, eliminating these compounds as
potential contaminants. In addition,
monitoring will be conducted to ensure the
components of each perform effectively in
the future. The overall time frame to restore
the groundwater in the overburden is not
expected to be significantly different for
each alternative. However, the alternatives
are not expected to provide adequate long-
term effectiveness and treatment of
contamination in the bedrock aquifer. Each
alternative would include" Institutional
Controls to prevent exposure to
contaminated groundwater. As such, each
alternative provides for long-term
effectiveness equally with respect to
exposure to contaminated groundwater.
4. Reduction of Contaminants Toxicity,
Mobility, or Volume through
Treatment
The proposed remedial action is an
interim action and, as such, is not intended
to address fully the statutory mandate for
treatment. Nonetheless, Alternatives 2 and 3
each satisfy the CERCLA statutory
preference for treatment. The treatment of
VOCs via each in-situ technology is
expected to provide a significant reduction
of the toxicity, mobility and volume of
contaminants within the overburden.
Neither alternative would prevent further
migration of contaminants within the
bedrock aquifer.
5. Short-term Effectiveness
Both Alternatives 2 and. 3 are expected
to be effective in the short-term in reducing
contamination in the overburden and
preventing migration of contamination to the
underlying bedrock aquifer. Each would
have a relatively short construction period
because both alternatives only require the
installation of new monitoring wells. There
would be minimal short-term impacts to
remedial construction workers, the
community,, or the environment.
6. Implementability
The implementation of each alternative
is straightforward. Conventional
construction techniques and equipment
would be used for the installation of new
monitoring wells and/or for modification, if
necessary, of existing wells. The in-situ
treatment technologies are fairly well-
established and the services and materials to
construct these processes are readily
available. Overall, no technical problems
are envisioned which would adversely affect
the construction of or the schedule for
implementation of either alternative.
Similarly, long-term operation and
maintenance requirements can be easily
performed.
7. Cost
Estimated investigation, capital, annual
operation and maintenance (O&M), and
present worth costs were compared for each
alternative. Investigation costs include the
estimated cost of delineating the overburden
and bedrock contamination originating from
the loading dock source area on the former
Stabilus facility and the contamination on
the northwestern portion of the former BAE
facility. Investigation costs also include the
vapor intrusion assessment of the structures
on the former Stabilus facility. Capital
costs include construction, engineering
design, construction management,
administration, and contingency. Annual
O&M costs include the estimated annual
operation and maintenance costs of the
remedy throughout the life of the project.
19
AR304841
-------
In order to best compare the varying
costs of the alternatives, a present worth
analysis was performed. This analysis
includes the present worth of annual O&M
costs with a discount rate of 7% over the
project life (estimated to be 10 years for
comparison purposes) and the one-time
capital costs and one-time cost of the
additional investigations.
Refer to Table 3 below for a summary
of the estimated costs of each alternative .
8. State/Support Agency Acceptance
State acceptance of the preferred alternative
will be evaluated at the conclusion of the
public comment period and will be
addressed in the OU2 ROD.
9. Community Acceptance
This criterion will be addressed in the
OU2 ROD following EPA's review of
comments on the revised Proposed Plan and
supporting , documents included the
administrative record.
TABLE 3: ESTIMATED COST OF ALTERNATIVES
Alternative
-Investigation
Costs,
Capital Costs
Cost of
Annual O&M
.Total Present"
Worth 1 J
Alternative 1
No Action
$0
$0
$0
$0
Alternative 2
In-situ Chemical
Oxidation
$911,000
$3,223,253
$40,000
$4,415,196
Alternative 3
In-situ
Bioremediation
J
$911,000
$1,334,294
$40,000 '
$2,526,237
SUMMARY OF THE PREFERRED
INTERIM SOURCE CONTROL
REMEDIAL ALTERNATIVE FOR OU2
EPA is proposing an interim source
control remedy to address the TCE
overburden plume that appears to originate
from the loading dock area of the former
Stabilus facility, while conducting further
investigations to determine the full extent of
the OU2 contamination. Given the size of
the area requiring treatment, in-situ
bioremediation is expected to be more cost
effective than in-situ chemical oxidation in
addressing the VOC contamination.
The preferred alternative for the interim
remedy meets the overall remedial action
objectives for the Site, provides short-term
protection of human health and the
environment and is expected to provide
adequate protection until a final remedy is
selected. Although the preferred alternative
for the interim action is not intended to
address fully the statutory mandate for
permanence and treatment to the maximum
extent practicable, this action does utilize
treatment and thus supports the statutory
mandate. 1
20
AR304842
-------
A review will be conducted at least
every five years pursuant to CERCLA
Section 121 (c) and th'e NCP Part
300.430(f)(5)(iii)(C), until ,the groundwater
performance standards are achieved, to
ensure that the remedy continues to provide
adequate protection of human health and the
environment. EPA, in consultation with the
Commonwealth of Pennsylvania, will select
a final remedy for OU2, based on the
additional site characterization data and the
results of the implementation of the interim
source control remedy. The preferred
alternative for the interim source control
remedy at OU2 includes:
A. Delineation of VOCs in the
Overburden
Sampling will be conducted to delineate
the groundwater contamination in the
overburden in the former Stabilus
loading dock source area and in the
northwestern corner of the former BAE
facility. The sampling shall delineate
the overburden areas where TCE
concentrations in groundwater are equal
or greater than 100 ug/1. For costing
purposes, it is assumed that
approximately 30 groundwater samples
will be collected in each of the two
areas from temporary monitoring wells
installed in the overburden via direct
push technology. The final sampling
locations and methods will be identified
in a work plan for the pre-design
investigation.
B. Investigation of Bedrock Aquifer
New bedrock' monitoring wells will be
installed to help determine the extent of
groundwater contamination in the
bedrock aquifer in the former Stabilus
loading dock source area and in the
northwestern corner of the former BAE
facility. For costing purposes, it is
assumed that approximately 6 bedrock
wells will be installed at each of the two
locations. 1 Geophysical logging,
packer and chemical testing will be
conducted on individual boreholes
before the wells are completed. These
tests should provide detailed
information regarding groundwater flow
and contaminant distribution in the
bedrock aquifer. In addition, the tests
will identify water bearing zones and
zones of contamination so that the wells
can be appropriately constructed. The
final number, location and design of
monitoring wells will be determined in
the pre-design investigation work plan.
Wells determined by EPA to no longer
be necessary will be abandoned in
accordance with State, requirements for
well abandonment. The results of these
investigations will be used in
determining a final remedy for OU2.
C. Evaluation of the Potential for
Vapor Intrusion
EPA will evaluate the potential for
vapors emanating from the VOC
contaminated overburden to migrate
into overlying buildings through
crawlspaces, cracks or other openings in
the foundation. This process is known
as vapor intrusion. Depending on the
concentration of VOCs present, vapor
intrusion may cause unhealthy indoor
air quality. An evaluation will be
conducted to determine whether vapor
intrusion presents a potential risk at any
structure located in the vicinity of the
OU2 groundwater contamination. Soil
gas, sub-slab, indoor and ambient air
sampling will be conducted, as
necessary, to determine whether VOC
contamination associated with OU2 is
contributing to vapor intrusion in
buildings located on the former Stabilus
property. Sampling locations and
methods will be determined in the pre-
design investigation work plan.
AR304843
-------
D. Enhanced In-situ Bioremediation
Enhanced in-situ bioremediation
systems designed to remediate VOCs in
groundwater typically involve input of
an organic source, nutrients, and/or
microbial cultures to stimulate
degradation or break down the
chemicals of concern in groundwater.
Final degradation products of these
processes include carbon dioxide,
water, chloride ion, and ethane. The
number of injections and timeframe for
treatment varies depending on site
conditions.
The interim source control remedy
employs enhanced in-situ
bioremediation to address the
. overburden contamination associated
with the loading dock source area on the
former Stabilus property where TCE
has been detected at concentrations of
100 ug/1 or greater. For costing
purposes, it is assumed that the
bioremediation enhancements will be
injected via a direct push technology at
approximately 250 locations within the
proposed treatment area to a depth of
approximately 20 feet (i.e., within the
overburden).
The treatment conducted as part of this
alternative is expected to involve a
series of three injections. Since natural
degradation appears to be limited, the
first two injections will involve the
addition of an organic substrate, such as
soybean oil, which should help support
the growth of microorganisms which
have the ability to break down the TCE
and related chlorinated compounds.
Once the soybean oil is dispersed
throughout the contaminated portion of
the overburden, selected nutrients and
microbial cultures will be injected to
further enhance biodegradation. It is
anticipated that the three injections will
occur during a 24 month timeframe.
Studies will be conducted as part of the
pre-design investigation, as necessary,
to determine the best mix of nutrients
and microbial cultures required to
optimize biodegradation processes in
the OU2 overburden. The addition of
substances to enhance biodegradation
processes at the Site shall be delivered
to the overburden in a manner that
sustains increases in the rates of
biodegradation of the groundwater
contaminants throughout the proposed
treatment area, until MCLs are achieved
in the overburden groundwater.
The addition of substances to enhance
biodegradation processes at the Site
shall be conducted in a manner that will
not result in the accumulation of toxic
intermediate products of biodegradation
(e.g., vinyl chloride) within the
overburden or underlying groundwater
aquifer. Monitoring of select
biogeochemical indicator parameters
will be conducted through the collection
of -field data and the analysis of
groundwater to monitor progress and
determine whether sufficient carbon is
being introduced to support the
necessary reducing conditions.
Controls will be implemented, as
necessary, to assure that possible
incomplete degradation of VOCs in the
overburden does not result in an
increase in vinyl chloride
concentrations in the overburden or
underlying bedrock aquifer. The final
treatment area, bioremediation
enhancements, schedule for the
injections, and monitoring program will
be determined during the Remedial
Design.
E. Performance Monitoring
The cleanup of the OU2 overburden
impacted by contamination from the
Stabilus loading dock area shall
22
AR304844
-------
continue until MCLs for the chemicals
identified in Table 2 are attained in
groundwater found in the overburden.
Monitoring wells will be installed in the
overburden and in the bedrock aquifer
in sufficient numbers and locations to
evaluate the performance of the
enhanced bioremediation interim source
control remedy. Sampling and analysis .
of the monitoring well network will be
conducted, as necessary, to document
contaminant levels before and after the
various injections of biostimulant
(soybean oil) and microbial cultures.
Monitoring shall be conducted to
evaluate the bioremediation processes
and achievement of performance
standards. EPA will evaluate the
monitoring results to determine the
effectiveness of the bioremediation in
reducing VOCs in the overburden and
to evaluate any impact to the underlying
groundwater aquifer. The benchmarks
for determining the effectiveness of the
bioremediation treatment will be
determined during the Remedial
Design. After a period of two years
following the first round of injection of
biostimulant, EPA will evaluate the
overall results of the in-situ remediation
to determine whether bioremediation is
effectively reducing the concentrations
of VOCs in the overburden. The final
monitoring program shall be determined <
during the Remedial Design. For
costing purposes, it is assumed that the
monitoring would be conducted for up
to ten ,years. Monitoring wells
determined by EPA to no longer be
necessary will be abandoned in
accordance with State requirements for
well abandonment.
used for drinking water purposes. EPA
expects to restrict installation of
drinking water supply wells on parcels
impacted by contamination associated
with OU2 through orders or agreements
with the property owners. EPA will
coordinate these efforts with PADEP
and MCHD. An ICIAP will be
developed for OU2 during the remedial
design to ensure appropriate
institutional controls are drafted,
implemented and monitored. Final ICs
will be developed for OU2, based on
the results of the interim source control
remedy.
COMMUNITY PARTICIPATION
EPA is soliciting comments from the
community on the proposed interim remedy
for OU2, as set forth in this Proposed Plan
and supporting documents. The public
comment period is from September 16, 2008
through October 16, 2008. A public
meeting will be held during the comment
period at which EPA will discuss this
Proposed Plan and supporting documents,
answer questions, and accept oral and
written comments from the public. The
public meeting is scheduled for Sepember
23, 2008 at 7:00 p.m. and will be held at the
Montgomery Township Municipal Building.
The front page of this Proposed Plan
provides the dates for the public comment
period; the date, location, and time of the
public meeting; and the locations of the
Administrative Record files.
Written comments on this Proposed
Plan should be postmarked no later than
October 16, 2008' and sent to:
F. Institutional Controls
Kelley A. Chase
ICs shall be established , to protect the U.S. Environmental Protection Agency
integrity of the interim remedy and 1650 Arch Street (3HS21)
ensure that the contaminated Philadelphia, Pennsylvania 19103-2029
groundwater associated with OU2 is not
23
AR304845
-------
Following the conclusion of the thirty summarize comments from the public and
(30) day public comment period on this , EPA's responses to these comments. Copies
Proposed Plan, a Responsiveness Summary of the OU2 ROD will be made available for
will be prepared and included in the OU2 public review in the information repository.
ROD. The Responsiveness Summary will
EPA Contacts for the Site:
; i.i'A =• i r -• . ;••• i.T""-,;, * •. - •
Kelley A. Chase, Remedial Project Manager
U.S. Environmental Protection.Agency , ' •: '
V '1650 Arch Street (3HS21)
Philadelphia, PA 19103-2029
'MlU- .(215) 814-3124
*? chase.kelley@epa.gov :
^David; Polish,.Community I^Yol^jement^^idihato^ W"-
U.S. Environmental Protection Agency
1650 Arch Street(3HS52) .
Philadelphia, PA 19103-2029 - ^ /
(215) 814-3327
rr.;r, polish.david@,epa.gov - . V w. ¦¦¦
i,
24
AR304846
-------
List of Acronyms
ARAR
' Applicable or Relevant and Appropriate Requirements ,
CERCLA
Comprehensive Environmental Response, Compensation, and Liability Act
COC
Contaminant of Concern
COPC
Contaminant of Potential Concern
EPA
U.S. Environmental Protection Agency >
HI
Hazard Index
ICIAP
Institutional Control Implementation and Assurance Plan
MCHD
Montgomery County Health Department
MCL
Maximum Contaminant Level
NCP
National Oil and Hazardous Substances Pollution Contingency Plan
O&M
Operations and Maintenance
OSWER
Office of Solid Waste and Emergency Response
OU
Operable Unit
PADEP
Pennsylvania Department of Environmental Protection
PADER
Pennsylvania Department of Environmental Resources
RAO
Remedial Action Objective
RI/FS
Remedial Investigation/Feasibility Study
ROD
Record of Decision
SDWA
Safe Drinking Water Act
TCE
Trichloroethene
Mg/1
microgram/liter
VOCs
Volatile Organic Compounds
i
/
25
-------
Glossary of Terms
Administrative Record - An official compilation of site-related documents, data, reports, and other
information that is considered important to the status of and decisions made relative to a
Superfund site. The public.has access to this material.
Applicable or Relevant and Appropriate Requirements (ARARs) - The federal and state
environmental requirements that a selected remedy must attain, unless they are waived. These
requirements may vary among sites and remedial alternatives.
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) - A
federal law passed in 1980 and modified in 1986 by the Superfund Amendments and
Reauthorization Act (SARA). The Act created a trust fund, known as Superfund, to investigate
and clean up abandoned or uncontrolled hazardous substance facilities.
Groundwater - Water found beneath the earth's surface in geologic formations that are fully
saturated. When it occurs in sufficient quantity, groundwater may be used as a water supply.
Hazard Index (HI) - Non-carcinogenic risks or toxic effect are expressed as HI. If a HI is less
than one (1.0), it is interpreted to mean that the risk of a non-carcinogenic injury is low. EPA
considers a HI exceeding one (1.0) to be an unacceptable non-carciriogenic risk.
Institutional Controls (ICs) - Ordinances, easements, covenants, title notices or land use
restrictions through orders or agreements with EPA to protect the remedy and limit the use of
land and/or groundwater to protect human health and the environment.
National Oil and Hazardous Substances Pollution Contingency Plan (NCP) - Federal
regulations which provide the organizational structure and procedures for preparing for and
responding to discharges of oil and releases of hazardous substances, pollutants, and
contaminants.
National Priorities List (NPL) - EPA's list of the nation's top-priority hazardous substance
facilities that may be eligible to receive federal money for response under CERCLA.
Operable Unit (OU) - A discrete portion of a site or a discrete action representing an
incremental step in the investigation and remediation of hazardous substances at a facility.
Present Worth - A term used to indicate the discounting of sums to be received in the future to
their present value equivalent or the amount that will accumulate to that sum if invested at
prevailing interest rates.
Record of Decision (ROD) - A legal document that describes the remedy selected for a
Superfund facility, why the remedial actions were chosen and others not, how much they cost,
and how the public responded.
26
'AR304848
-------
Remedial Investigation and Feasibility Study (RI/FS) - An RI is a study performed to identify
the nature and extent of contamination at a hazardous substance facility. An FS identifies and
evaluates alternatives for addressing the contamination. The RI is used in conjunction with the
FS to support the selection of a remedy for the site.
Scientific Notation - Method used to express numerical values. For example, one million
(1,000,000) is expressed as l.OE+06. One, one-millionth (or one in one million) (0.000001) is
expressed as 1.0E-06.
Superfund - See CERCLA.
Vapor Intrusion - When certain chemicals are released into soils and/or groundwater they can
give off gases, or vapors, that can seep inside buildings. The vapors move through the soil and
seep through cracks in basements, foundations, sewer lines and other openings. Vapor intrusion
is a concern because vapors can build up to a point where the health of residents or workers in
those buildings could be at risk.
Volatile Organic Compounds (VOCs) - Organic liquids [e.g., trichloroethene (TCE)] that
readily evaporate under atmospheric conditions.
27
I
-------
AR304850
-------
AR304851
-------
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-------
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TCE Concentration Map
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North Penn Area 5
APPROX. SCALE M MET
AR304853
-------
Figure 5
Proposed Treatment Area
North Penn Area 5
Colmar, Pennsylvania
Proposed
Treatment
Area
o
Fromer Stabilus
Building
(Currently H&N
Packaging)
'Covered
Storage
Area
APPROX. SCALE IN FEI
EPA R3 GIS Team 9/2/2008 Bob Walker VIS 111 Map 3466
AR304854
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