United States Office of
Environmental Protection Emergency and
Agency Remedial Response
EPA/ROD/R03-92/143
March 1992
&EPA Super-fund
Record of Decision:
Strasburg Landfill, PA
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NOTICE
The appendices listed in the index that are not found in this document have been removed at the request of
the issuing agency. They contain material which supplement but adds no further applicable information to
the content of the document All supplemental material is, however, contained in the aU»*iisualfre record
for this site.
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50272-101
REPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA/ROD/R03-92/143
3. Recipients AceeMlon No.
4. Tide and Subtitle
SUPERFUND RECORD OF DECISION
Strasburg Landfill, PA
Third Remedial Action - Subsequent to follow
S. Report Date
03/31/92
7. Author).)
8. Performing Organization Rept No.
9. Performing Organization Name and Address
10. ProjecVTask/Work Urtt No.
11. Contnct(C) or Gr«nt(G) No.
(C)
(G)
12. Sponsoring Organization Name and Address
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report & Period Covered
800/000 .
14.
15. Supplementary Note*
PB93-963916
16. Abstract (Limit 200 words)
The 22-acre Strasburg Landfill site is an inactive landfill located within a 220-acre
tract of land in Newlin and West Bradford Townships, Chester County, Pennsylvania. The
site is characterized by hills draining toward Brandywine Creek and its floodplain,
which form the southern and western site boundaries. The nearest wetland is the Briar
Run watershed, located 600 feet east/southeast of the site. Land use in the area is
primarily suburban residential, with some residual agricultural areas. The 201
~single-family residences that surround the site use ground water as a drinking water
source. Prior to 1973, the site was used as farmland. Subsequently, landfilling
permits were granted, and from 1979 to 1983, the landfill accepted more than 3 million
cubic yards of industrial and heavy metals waste and sewage treatment plant sludge,
including over 1,000 cubic yards of polyvinyl chloride (PVC). In 1979, state
investigations determined that landfill operations had resulted in excessive siltation
of Briar Run, and in 1980, the state permanently prohibited the landfill from receiving
additional industrial waste. -In 1983, after the owners were cited for failure to
correct onsite violations, the state ordered the landfill closed. As a result of
improper landfill closure efforts, over 15 leachate seeps have increased cap erosion'
(See Attached Page)
17. Document Analysis a. Descriptors
Record of Decision - Strasburg Landfill, PA
Third Remedial Action - Subsequent to follow
Contaminated Media: soil, debris, leachate
Key Contaminants: VOCs (TCE, toluen, xylene)
b. Identifiera/Open-Ended Terms
e. COSATI Held/Group
18. Availability Statement
18. Security Class (This Report)
None
20. Security Class (This Page)
None
21. No. of Pages
64
22. Price
(See ANSI-Z39.18)
See Instructions on Reverse
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-35)
Department of Commerce
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RECORD OF DECISION
8TRASBORG LANDFILL SITE
DECLARATION
SITE NAME AND LOCATION
Strasburg Landfill Site
Newlin Township, Chester County, Pennsylvania
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for
Operable Unit 3 for the Strasburg Landfill Site, in Newlin
Township, Pennsylvania, which was chosen in accordance with the
requirements of the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA), as amended by
the Superfund Amendments and Reauthorization Act of 1986 (SARA)
and, to the extent practicable,. the National Oil and Hazardous
Substances Pollution Contingency Plan (NCP). This decision
document explains the factual and legal basis for selecting the
remedy for this Site.
The Pennsylvania Department of Environmental Resources (FADER)
concurs with the selected remedy. The information supporting
this remedial action.decision is contained in the Administrative
Record for this site.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from this
site, if not addressed by implementing the response action
selected in this Record of Decision (ROD), may present an
imminent and substantial threat to public health, welfare, or the
environment.
DESCRIPTION OF TEE SELECTED REMEDY
This Operable Unit is the third of four operable units for the
site. Operable Unit 1 involves the collection and treatment of
leachate from the eastern portion of the landfill. Operable Unit
2, which is currently at the design stage, will involve the
construction of a security fence around the perimeter of the
landfill portion of the Site. This third operable unit will
address all principal threats posed by contamination from the
Site in all media except groundwater. Within this remedial action
the landfill will be recapped, a landfill gas venting system will
be installed, and the leachate discharging from the landfill will
be collected and treated. These actions, combined with those
contemplated within Operable Unit 4, which will address the
groundwater contamination, will address all of the principal
threats posed by conditions at this Site.
This Remedial Action (for Operable Unit 3) will need long-term
operation and maintenance, which includes management, to remain
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effective. Operation and maintenance will be needed to ensure
that the new landfill cap is maintained and that the leachate
continues to be collected and treated in compliance with
applicable regulations.
The selected remedy includes the following major components:
o Removal of the existing (damaged) landfill cover
o Installation of a landfill cap over the existing 22 acre
landfill
o Installation of a landfill gas venting system
o Revegetation of the landfill cap
o Installation of a sub-surface leachate collection system
o Construction of a leachate treatment system -
o Operation and Maintenance
DECLARATION OF STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the
environment, complies with Federal and State requirements that
are legally applicable or relevant and appropriate to the
remedial action, and is cost-effective. This remedy utilizes
permanent solutions and alternative treatment (or resource
recovery) technologies to the maximum extent practicable, and it
satisfies the statutory preference for remedies that employ
treatment that reduce toxicity, mobility, or volume as their
principal element.
Because this remedy will result in hazardous substances remaining
on-site above health-based levels, a review will be conducted
within five years after commencement of remedial action to ensure
that the remedy continues to provide adequate protection of human
health and the environment.
Edwin B. EricJcson v Date
Regional Administrator
Region III
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Decision Summary for the Record of Decision for operable Unit 3
/ *
1. site Name. Location, and Description
The Strasburg Landfill Site is a portion of land, including
a 22-acre inactive facility, located within a 220-acre tract of
land south and slightly east of Strasburg Road in both Newlin and
West Bradford Townships, Chester County, Pennsylvania. The
coordinates of the Site are North 39° 56' 35" latitude and West
75° 46'18" longitude. The entrance to the landfill is on
Strasburg Road and is controlled by a locked gate. The gate,
however, is across the road entrance only and access, at this
time, to the Site is essentially unrestricted (Fig 1). A
previous Record of Decision (ROD), designated "Operable Unit 2"
or "OU2," was signed on June 28, 1991. That ROD calls for the
installation of a perimeter fence around the landfill portion of
the Site.
The topography of the area is characterized by a combination
of steep and gentle hills. All the land in the area is sloped
towards, and drains to, the Brandywine Creek that forms the
southern and western boundaries of the Site area.
The highest elevation of hills south of the Site area in
Newlin Township approaches 550 feet above mean sea level (MSL).
The landfill itself resembles a steep hill. The peak elevation
of the landfill, from ground control survey, is 474 feet above
MSL. The south and east sides of the landfill have a much
steeper slope than the north and western sides. The slope along
the eastern side is approximately 60 degrees in some locations.
Surface drainage from the Site flows to the south and southwest
toward the Brandywine Creek and to the east and southeast toward
Briar Run that flows into the Brandywine.
The elevation of the Brandywine Creek floodplain to the
south is approximately 250 feet above MSL. There are no wetlands
either on the landfill, or within 300 feet of the landfill in any
direction (Fig 2). The nearest wetland is the Briar Run
watershed which is approximately 600 feet east and southeast of
the landfill.
Land use in the area is primarily suburban residential, with
some residual agricultural areas. There are 201 single family
residences within a one mile radius of the Site. All the
drinking water to these residences is supplied from groundwater.
Most of the homes are served by private home wells. There is a
private water company, approximately one mile east and slightly
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i art LOCATION MAP
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of LAMBTILL MMf AOI
Wl«r. 2 SCHEMATIC SITE MAP OF STIIASBURG LANDFILL
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north of the landfill, that provides drinking water from deep
wells to several residences radiating away from the site area.
According to the State closure plan, the landfill was
supposed to be closed by covering the fill material with two feet
of soil, a polyvinyl chloride (PVC) cover, and an additional two
feet of soil and vegetation. Later discussion in this decision
document will show that this type of landfill closure did not
occur. Grasses and various wild vegetation are growing on
approximately 60 - 70% of the landfill cap. The remaining areas
are barren because of one or more of the following reasons: poor
quality of the soils, the steepness of the slopes, no maintenance
of the existing cover, exposure of the PVC cover, and leachate
seeps. Typically, leachate seeps form and stain the vegetation;
as the leachate persists, the vegetation dies off, leaving barren
strips on the landfill. Next, erosion sets in, and strips off
all but the largest rocks in these areas. Leachate seeps will
not be contained by the implementation of the access restrictions
imposed by OU2; these seeps may freely flow through the fence on
the surface as well as into the groundwater.
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2. 5jte History and Enforcement Activities
According to EPA's records, prior to 1973, some of the
property was used for farming and a large portion of the property
was undeveloped.
A partnership, Strasburg Associates Inc. (SAX), was formed
in September 1973 and purchased the property in December 1973.
In August 1975, Strasburg Associates received a Pennsylvania
Department of Environmental Resources (FADER) permit to accept
municipal wastes at the 22-acre facility. The opening was
delayed until February 1979 because of local concerns over the
use of residentially zoned roads, the proposed sale of the
landfill to Strasburg Landfill Associates (SLA) and permitting of
a proposed 200 acre expansion.
In May 1978, SLA was formed through a joint vsntur©
agreement. In August 1978, SLA acquired the landfill. In
October 1978, SLA applied to PADER for a proposed 200-acre
landfill expansion. On October 11, 1978, SLA entered into a
lease agreement with SA, a joint venture composed of SAI and
Strasburg Associates II, (another limited partnership), to
operate the landfill.
In February 1979, the 22-acre landfill was opened. In the
spring of 1979, new PADER permits-were granted to SLA to receive
certain industrial and heavy metal wastes. By July 1979, the
landfill was accepting sewage treatment plant sludge and
manufacturing wastes, including "off-spec" and scrap PVC. By
December 1979, more than 1,000 cubic yards of PVC wastes, 2,052
cubic yards of industrial wastes and sludges, and 35,000 gallons
of heavy metal sludge had been accepted at the landfill.
In December 1979, PADER charged the landfill operators with
excessive siltation of Briar Run. At that time PADER prohibited
the disposal of certain industrial wastes because the waste
characteristics did not match those on the approved waste
disposal application module. Also, PADER prohibited SA from
accepting additional PVC waste for disposal. In August 1980,
PADER permanently prohibited the landfill from receiving
industrial wastes. Between January and June 1981, PADER cited SA
for operational problems (dust control, daily cover, and litter
control) at the landfill.
PADER conducted periodic inspections, both announced and
unannounced, during the landfill operation. During an
unannounced inspection in April 1983, PADER found four major
operating violations: improper run-off control; slopes in excess
of allowed limits; failure to cover compacted waste; and
inadequate sedimentation and erosion control. PADER issued SA a
notice of violation and required that the violations be corrected
within 30 days. The violations were not corrected within the
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specified time. In May 1983, PADER suspended the landfill
operating permit and ordered the landfill closed. '. SLA closed the
landfill in May 1983, by providing a final soil cover, a PVC
cover, and stabilized the site with an additional layer of soil,
The operators also planted vegetation, and installed a leachate
storage tank system. PADER also issued an order requiring the
removal of collected leachate for off-site treatment and
disposal.
As part of the closure plan, the landfill was supposed to be
regraded, covered with 2 feet of soil, and topped with a PVC
cover. Another 2 feet of soil was supposed to be placed on the
PVC cover and vegetation planted. After the vegetation took
root, the cap was to be maintained by mowing. This did not
occur. The landfill PVC liner is not covered with two feet of
soil; and, in numerous locations, the liner is exposed to the
surface. The leachate collection and storage system was also
installed as part of the closure plan. It is not clear how well
this system was installed. EPA has had to perform additional
work to channel some of the landfill leachate into the treatment
system constructed as part of OU1, as discussed below.
In August 1983, volatile organic contaminants (see Tables 1
and 2) were detected in an on-site monitoring well, M-2, and in
the landfill witness system drain pipe. In September 1983,
volatile organic contaminants (see Table 1) were detected in
Briar Run east of the landfill. PADER required SA and SLA to
conduct a periodic monitoring program and a hydrogeologic study.
In October 1983, volatile organic contaminants, in excess of
drinking water standards, (see Table 3) were detected in an off-
site residential drinking water well southwest of the landfill.
In February 1984, SLA installed four monitoring wells (M-2A,
M-2B, M-2C, and M-5) and began a sampling and analysis program
(see Table 2). SLA submitted the hydrogeologic investigation to
PADER in July 1984.
In July 1984, the hydrogeologic/engineering report
evaluating the extent of groundwater contamination was completed.
The six corrective measures delineated in the report included:
o Extending the PVC liner;
o Installing new leachate collector drains;
o Installing a 15 mil PVC membrane cap;
o Regrading soil to attain 2-1/2:1 or 3:1 final outslopes;
o Revegetating the sides and the top of the landfill; and
o Regrading soil to divert surface water away from the fill.
Implementation of these measures was never completed.
Additionally, the eastern side of the landfill is very steep
(estimated 60% slope) in areas, and erosion is occurring such
that the original PVC liner is exposed and torn in numerous
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locations. Vegetation is non-existent or extremely sparse over
approximately 1/3 of the landfill. Approximately-eight distinct
leachate seeps were evident in 1989 on the eastern and southern
portions of the landfill. Over the next two year period, the
number of distinct surficial leachate seeps has increased to
approximately 20 seeps, including a number of seeps on the
western slopes of the landfill. Because of the lack of cap
maintenance and the toxic effect of the leachate seeps on the
present vegetation, erosion has begun to rapidly accelerate the
demise of the already poor landfill cap.
PADER has conducted periodic monitoring of residential
drinking water wells, on-site monitoring wells, sediment pond
outfall, leachate seeps, and Briar Run from September 1983 to the
present (see Appendix A of the Remedial Investigation [RI]):
Summary of PADER Residential Well Sampling). The monitoring
program results showed two residential wells southwest of the
landfill contaminated with volatile organics. In August 1983,
PADER analyses of water from well M2 and of leachate from the
witness drain revealed organic and inorganic contamination (see
Table 1). In September 1983, analyses of water samples collected
from well M2, the witness drain, and Briar Run (see Table 2)
revealed significant levels of organic chemicals.
A Hazard Ranking System (HRS) scoring package was prepared
by EPA for the Strasburg Landfill site in April 1987, receiving a
score of 30.71. The site was proposed for inclusion on the
National Priorities List (NPL) in Update Number 7, released in
June 1988. The Strasburg Landfill was added to the NPL in March
1989.
As a result of the leachate running off of the landfill, and
flowing directly into Briar Run, and the failure of the operator
to take any corrective actions, PADER initiated an action to
collect this leachate and haul it, for treatment, to a nearby
municipal sewage treatment plant. Prior to the installation of
the leachate collection system and treatment system, surface
water runoff and leachate from the landfill were directed into
the unlined sediment ponds located southwest and east of the
landfill.
Since the installation of the leachate collection and
treatment system, flow through the system has increased slightly
and (fall 1991 flow meter gauge) averages approximately 5 gallons
per minute.
Despite the warning signs of the hazardous nature of this
Site and the clear evidence that this Site was a landfill, EPA
has seen direct evidence of many different groups of people
utilizing the property, and specifically the landfill for various
recreational activities. These include the following:
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o people using horses whose tracks are seen adjacent to, and
on the lover slopes of the landfill. Local residents
indicate that there is both random horseback riding and
organized fox hunts involving large numbers of riders
and accompanying hounds;
o hikers, who occasionally build campfires on the slopes and
top of the landfill;
o vandals, who have attempted to dismantle parts of the
leachate treatment system;
o joggers; and most particularly;
o riders of motorcycles and "all terrain vehicles" (ATVs)
whose tire tracks are wearing grooves into the sides of
the landfill.
It is expected that some of the contact between the site
users and the surficial landfill seeps will be eliminated by the
construction of the (OU2) security fence. EPA has also spoken to
people who recreate on the site and they have indicated that, on
occasion, leachate seep material has splashed up on their
clothing and, furthermore, that the leachate has splashed into
their mouths. EPA's concern for both the health of local people
and the continuing deteriorating condition of the existing cap
and emergence of new,leachate seeps leads EPA to propose the
series of actions outlined in this ROD to minimize or eliminate
the potential exposures to contaminants on the site. Also, EPA
is aware that the security fence will not totally eliminate
people coming into contact with the surficial leachate streams,
as these streams could flow, virtually unrestricted, though the
fence.
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Table l
SUMMARY OF ANALYTICAL RESULTS FOR SAMPLES
COLLECTED FROM WELL M2 AND
WITNESS DRAIN PIPE,
PADER, AUGUST 1, 1983
Compound
Chloroethane
Chlcrc@then@
1 , 2-Dichloroethene
1 , 1-Dichloroethene
1 , 2-Dichloroethene
1 , 1-Dichloroethene
1,1, 1-Trichloroethane
Trichloroethene
Tetrachloroethane
Chlpromethane
Dichloromethane
Dichlorofluoromethane
Trichlorof luoromethane
Benzene
Toluene
Ethyl benzene :
Chlorobenzene
witness Drain
Pipe
27
126
11
109
140
-
6
9
-
2
86
-
Trace
34
76
12
4
Well
M2
7
S
-
16
3
10
47
3
14
2
3
Trace
9
2
Trace
-
_
-9-
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Table 2
SUMMARY OF ANALYTICAL RESULTS FOR SAMPLES
COLLECTED FROM WELL M2, THE WITNESS DRAIN PIPE,
AND BRIAR RUN,
PADER, SEPTEMBER 6, 1983
Compound
Chloroethane
Chloroethene
1,2-Dichloroethene
1,1-Dichloroethene
1,2-Dichloroethene
1,1-Dichloroethene
1,1, l-Trichloroethane
Trichloroethene
Tetrachloroethane
Chloromethane
Dichloromethane
Dichlorofluoromethane
Trichlorofluoromethane
Benzene
Toluene
Ethyl benzene
Chlor obenz ene
Well
M2
8.7
18
1.2
22
9
8.4
65
4.1
18
'
4.6
Trace
3.7
6.2
1.0
-
_
Witness Drain
Pipe
6.7
Estimate 180
13
Estimate 150
100
2.1
16
2.4
5.8
-
34
- •
-
47
97
19
3.8
Briar
Run
' -
2.2
-
1.5
1-7
-
1.5
Trace
Trace
-
-
-
-
1.0
1.0
-
_
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Table 3
ANALYTICAL RESULTS OP THE SAMPLES
COLLECTED FROM AN OFF-SITE
RESIDENTIAL WELL
FADER, OCTOBER 14, 1983
Compound
Residential
Well
Chloroethane
Chloroethene
1,2-Dichloroethene
1,1-Dichloroethene
l,2-Dichloroethene
l,1-Dichloroethene
1,1,1-Trichloroethane
Trichloroethene
Tetrach1oroethane
Chloromethane
Dichloromethane
Dichlorofluoromethane
Trichlorofluoromethane
Benzene
Toluene
Ethyl benzene
Chlorobenzene
0.9
7.8
3.4
3.3
5.8
9
8.5
Trace
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A number of Potentially Responsible Parties (PRPs) have been
notified with regard to remedial actions undertaken at the Site.
A Unilateral Administrative Order was issued to three PRPs for
the implementation of OU 1, discussed below.
3 . Highlights of CpOTlfflrcupitv Participation
The current Proposed Plan for Operable Unit Three (OU3) for
the Strasburg Landfill site was released for public comment on
December 24, 1991. A Remedial Investigation (RI) and Feasibility
Study (FS) , summarized in the Proposed Plan, were also made
available for public comment. These two documents and the
Proposed Plan, along with other site related documents, were made
available to the public in both the administrative record and an
information repository maintained at the EPA Docket Room in
Region III and at the Bayard Taylor Memorial Library located in
Kennett Square, PA. The notice of availability for these two
documents was published in the Daily Local News on December 24,
1991.
In accordance with CERCLA Sections 113 (k) (2) (B) (i-v) and
117, a public comment period was held from December 24, 1991 to
January 23, 1992; at the request of one of the commenters, this
period was extended to February 6, 1992. In addition, a public
meeting was held on January 8, 1992 at the West Bradford Township
Building. At this meeting, representatives from EPA and PADER
answered questions about problems at the Site and the remedial
alternatives under consideration. A response to the comments
received during the public comment period is included in the
Responsiveness Summary, which is part of this ROD.
This decision document presents the selected remedial action
for OU3 for the Strasburg Landfill Site, in Newlin and West
Bradford Townships, Pennsylvania, chosen in accordance with
CERCLA, as amended by SARA, and to the extent practicable, the
National Contingency Plan. The decision for this Site is based
on the administrative record.
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4. Scope and Role of Operable Unit (OU 31 or Response Action
Within Site Strategy .
As with many Superfund sites, the problems at the Strasburg
Landfill Site are complex. As a result, EPA has organized the
remedial work into four separate planned actions.
This ROD which is the third planned remedial action (OU 3)
at the site, addresses the following contaminated media: the
surface of the landfill; nearby surface streams; air in and
around the landfill; the surficial aquifer; and to a limited
extent, the groundwater. The first ROD (OU 1) addressed
contaminated residential wells and leachate releases into surface
water ways and groundwater near the landfill. Under this first
action, leachate is now collected, treated, and discharged on
site. OU 1 has been fully implemented. The second ROD (OU 2)
addresses sits access and security. Under this subsequent
action, the landfill portion of the site is to be enclosed with a
security fence and additional warning signs will be placed in the
area. A future ROD (OU 4) will specifically address groundwater
in the area of the site. The scope of this future remedial
action (OU 4) will be based on the success of the remedy selected
for this (OU3) operable unit.
This remedial action addresses low level wastes emanating
from the landfill both onto the surface, and into the groundwater
and surface streams near the Strasburg landfill, The principal
threat is the leachate emanating from this landfill. This remedy
will look to minimize or eliminate the exposure pathways of
people coming into contact with these substances, for example,
inhaling the hazardous vapors either on the landfill or by
showering using contaminated groundwater; by ingesting the
contaminated groundwater, or by having these leachate materials
splashed up on them. It should be noted that this action may not
fully address all of the contamination evidenced in the
groundwater. Monitoring and modelling will be used in developing
the scope of Operable Unit 4, which is planned to address
groundwater contamination.
A Remedial Investigation (RI) and Feasibility Study (FS)
which were performed for this OU are contained in the public
record as support for this Record of Decision. The RI/FS for
this third planned action were finalized in September, 1991.
Since the fourth operable unit will be based on (partly)
groundwater modelling, based on several years of data collected
after OU 3 is completed, the ROD for this future unit (OU 4) is
not expected for a minimum period of two years after the
completion of this (OU 3) operable unit. Naturally, unforeseen
situations may arise which would modify this comment.
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5. ?\UnnflrY °^ Site Characteristics
During sampling by FADER in October 1983, volatile organic
compounds were, detected in off-site residential drinking water
wells. Based on their findings, FADER implemented a periodic
monitoring program of the residential drinking water wells.
In August 1986, EFA prepared an HRS package to determine the
Strasburg Landfill Site's eligibility for proposal to the NFL.
The Strasburg Landfill was proposed to the NFL on Update #7, in
May 1988. Since that time and continuing through to the time of
this decision summary, EPA continues to conduct a FRP search.
From the evidence gathered to date, it is clear that the
Strasburg landfill received massive quantities of both municipal
and industrial wastes. The industrial wastes disposed of at this
Site came from both direct deposits and also indirectly, through
the actions of municipalities that brought sludges, containing
wastes from industrial contributors, to the Site. Because of the
lack of records regarding the operation of the landfill, the
specific ratio,,or volume from any one source is impossible to
determine, but measurements show that the total volume of the
landfill is more than 3 million cubic yards. Specific
contaminants, which have been determined as leaving the landfill
site, and placing the nearby residents and visitors to the site
at risk, are listed in Tables 1 through 7 in this decision
document.
Nature and Extent of Contamination
This sub-section focuses on the contaminants that may pose
hazards, through ingestion, inhalation and direct contact, to the
public due to the release of hazardous substances from the
landfill. The Strasburg Landfill received both municipal and
industrial wastes during its operation. The landfill served as a
significant disposal site for municipalities in southeastern
Pennsylvania as well as a disposal site, for industrial
contributors from this same area as well as from Delaware. It is
estimated that the total volume of the landfill is at least
3,000,000 cubic yards of combined wastes and fill. The
proportion of industrial waste to municipal waste has not been
determined. Responses from industrial contributors to inquiries
from EPA as to the substances deposited in the landfill
characterize, at least a portion of the waste, as hazardous, as
defined in 40 CFR S 261 Subpart C and 25 PA Code Part 261,
Subpart C. These wastes, defined as "characteristic" under the
Resource Conservation and Recovery Act (RCRA), were disposed of
at the landfill after the effective date of RCRA. In addition
some of the wastes deposited at the landfill contained
constituents of hazardous wastes as contained in 40 CFR S 261
Subpart D and 25 PA Code Part 261, Subpart D.
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During several planned inspections of the landfill cap, it
was observed that the plastic liner, which was supposed to be
buried under two feet of soil, was exposed to the surface. The
number of locations where the liner was exposed exceeded 25
locations and, based on further examination, it is estimated that
a significant portion of the landfill has only a few inches of
soil cover. In addition, leachate streams flow from a number of
areas on the landfill which have been improperly capped or where
the landfill cap has been somehow compromised. Initial over-
flights of the Site showed approximately 15 leachate seeps on the
eastern and southern slopes of the landfill. In the last twelve
months, EPA has identified at least six additional seeps on the
southern and western portions of the landfill. It is not clear
if these are new seeps or if they had been overlooked during the
over-flight investigation. Leachate, as used in this document,
refers to the liquid and semi-liquid substances, particularly
hazardous chemicals, that seep from the contents of the landfill,
either onto other ground surface areas, ground (called "discharge
to groundwater") or surface waters.
In order to minimize cap erosion and stabilize landfill
deposits, side slopes for a landfill should be not less than 2%
and not greater than 15%. This is specified in 25 PA Code
264.301(5). The eastern slopes of the Strasburg Landfill have
grades of approximately 50 - 60%. Because of the steepness of
these slopes, soil cover has slid away from the liner exposing
large amounts of the liner to the surface.
As part of the landfill closure (according to the closure
plan), the cell structure of the landfill was to be vented to
allow for the escape of built-up landfill gases (so they do not
rupture the sides or top of the landfill). Vent pipes were to be
placed at reasonable distances to allow the gases to escape, and
the landfill liner was supposed to be covered with clean soil.
Soil depth on top of the liner was specified to be a depth of two
feet, and, as a final measure, the surface soils were to be
seeded to promote the growth of vegetation to prevent soil
erosion. In the situation at the Strasburg Landfill, as
described above, the depth of soil cap is totally inadequate,
with much of the liner exposed and torn. In addition, the type
of soil used for final cover was inappropriate. Much of the
liner cover material is best described as weathered bedrock,
which is a poor soil base for subsequent vegetation. More
importantly, this weathered bedrock contains numerous medium
sized jagged rocks, many over 8 inches in diameter, which, when
dropped from the tailgate of a dump truck, can puncture the
fragile plastic liner. The effect is that the liner more closely
resembles (in effect) an inverted colander, allowing rain water
to flow freely into the landfill and leachate to flow freely out
of it.
-15-
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There is much evidence that the existing cap.of the landfill
has been compromised. There are large areas on the. eastern slope
of the landfill where all of the soils have eroded exposing large
areas of the liner. Furthermore, EPA now finds over twenty
distinct leachate seeps covering the eastern, southern, and
western slopes of the landfill. Most leachate seep material that
rises to the landfill surface, flows to the eastern and southern
direction toward a small trout stream called Briar Run. From
roughly the area where the seeps would enter Briar Run, this
stream flows approximately one quarter mile before it joins the
Brandywine Creek, which is classified as a scenic stream and is
also used as a drinking water intake less than two miles farther
downstream. The neighborhood around the landfill is relatively
stable in terms of development; however, similar areas, in
locales as close as four miles away are experiencing a
considerable amount of development of single family housing. It
is expected that this type of development will, in a reasonably
short time, occur in this area. At the time the site was first
visited by EPA, private surveyors, apparently contracted by the
owners, were on the property working on a plan to develop part of
the property for executive homes. While this action immediately
ceased, additional development in the area may bring more people,
particularly children, into contact with the landfill.
Leachate Seeps
There are a number of leachate seeps evident on all but the
small northern slope of the landfill. The largest and most
notable leachate streams are located on the eastern and
southeastern portions of the landfill. Data are available on
landfill leachate collected from a manhole near the sediment pond
and a seep located between the sediment pond and Briar Run Creek.
Recent analytical results for samples of these materials are
given in Table 4. These materials are presumably derived from
the same general source as the liquid from the other seeps at the
southeast corner of the landfill and may exhibit similar
contamination patterns.
The liquid discharging from some of the southeast seeps flow
overland and eventually discharge directly to Briar Run or flow
in a northeasterly direction to be collected and treated in the
leachate collection system (OU 1), or to a drainage ditch that
empties into the sedimentation pond immediately east of the
landfill. During heavy rains, the sedimentation pond (prior to
the implementation of OU 1) would overflow and discharge, via a
riser and a conduit, running eastward from the pond, through the
woods and into Briar Run, which in turn flows into Brandywine
Creek. Liquid discharged from some of the southeast seeps may
migrate to groundwater via infiltration at various points along
the overland flow pathway. Groundwater movement in the area is
mainly via fractures in the Peters Creek Schist Formation.
-16-
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Potential pathways of exposure to the leachate seep material
include the following:
o Ingestion of domestic well water which could be
contaminated with leachate flowing through fractures in
the bedrock.
o Direct contact (including dermal and- oral exposure)
with the seep material by members of the general
population (adults and children) who might enter the
site for miscellaneous recreational purposes; for
example, children playing in the area;
o Inhalation of volatile organics, emitted from the
leachate and soils along the overland flow pathway, by
representatives of the general population that may come
into close proximity to the seeps or their overland
flow pathways; and
o Dermal, oral, and inhalation exposure to contaminants
that might reach Briar Run or the Brandywine Creek.
This is a concern for members of the general population
using the Brandywine for recreational purposes such as
canoeing, tubing, swimming, bathing, wading, fishing,
or as a drinking water source.
The leachate has also infiltrated the ground and reached
(discharged into) the groundwater that is used as a water supply
source by 203 residences in the vicinity of the landfill.
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Table 4
SUMMARY OF ANALYTICAL RESULTS FOR
SEEP AND LANDFILL LEACHATE SAMPLES
(ug/L)
*
Seep East of
Compound Sediment Pond
Vinyl Chloride
1 , 1-Dichloroethane
trans- 1 , 2-Dichloroethylene
1 , 2 -Dichloroe thane
1 , 2-Dichloropropane
Trichloroethylene
Benzene
Toluene
Chlorobenzene
Xylenes
cis-l , 2-Dichloroethylene
1 , 4 -Dichlorobenzene
1, 2-Dichlorobenzene
Chloroethane
Ethylbenzene
Source: PADER, March 9f 1988.
10
30
1.0
4.3
2.9
3.4
2.2
8.4
26
2.0
35.0
7.8
1.0
— •
Landfill
Leachate
20
• —
•
•
~ "
..
10
280
15
Est. 950
13
Est. 50
--•
12
130
-18-
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Table 5
LIST OF CONTAMINANTS FOUND IN
RESIDENTIAL DRINKING WATER WELLS
(ug/L)
Compound
Maximum Detected
Contaminant
Concentration
Levels
Maximum
Allowable
Contaminant
Levels (MCLs)
Benzene
Chlorobenzene
chloroform
1 , 1-Dichloroethane
1 , 2-Dichloroethane
cis-l , 2-Dichloroethylene
1,2-Dichloropropane
1,1, l-Trichloroethane
Trichloroethylene
1,1,2,2 -Tetrachloroethy lene
Vinyl chloride
3.4
1.4
1.7
16.0
1.3
413.9
1.2
2.5
35.8
3.5
2.5
5
100
-
-
5
7
5
200
5
• 5
2
Source: FADER 1987-1988.
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6. SVHBMrY of Sjl^e Risks
The contaminants in the landfill leachate and seeps (Table
4) and in the residential water supplies of the affected homes
(Table 5) consist of a variety of hazardous volatile organic
compounds. This section provides a summary of the potential
risks to human health from these contaminants in the absence of
any remedial action.
It should again be noted, that, although EPA has evaluated
the risks posed by the site contaminants, the stability and
integrity of the existing cap is a significant concern to be
addressed by this remedial action. Further degradation of the
cap may lead to increased leachate production, greater number of
seeps and more potential exposure risks. Additionally, the
security of the existing collection and treatment system is
impacted by trespassers and vandals. Failure of this system
could cause large releases of contaminated water directly to
Briar Run and then to the Brandywine Creek. Large bushes have
also taken root on the cap and the penetration of their roots can
be expected to further compromise the landfill's PVC liner.
HUMAN HEALTH RISKS
The Strasburg Landfill is a former 22-acre landfill located
on an open 220 acre tract of land. The only access restriction
is a locked gate across the main access road. When Operable Unit
2 is installed, the 22 acre landfill will be enclosed in a
security fence. This access restriction will minimize exposure
to the landfill leachate seeps; however, the fence will not serve
as a barrier and seep material will (can) flow freely through it.
Nor will the fence restrict access of Site visitors beyond the
landfill area.
The exposure pathways that appear to have the greatest
potential to produce adverse human health effects at Strasburg
Landfill are:
o Zngestion of contaminated drinking water from the
surficial aquifer (all of the 200+ residents in the
vicinity of the landfill rely on groundwater for the
source of their drinking and bathing water)
o Inhalation of hazardous vapors by bathing or showering
with contaminated groundwater. Migration of volatile
contaminants via soil gas to the air in the vicinity of
the landfill, where they could be inhaled by site
visitors;(it is estimated that on a daily basis,
approximately 40 people visit the site area for
recreational purposes).
-20-
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o Migration of contaminants within landfill leachate to
the ground surface in seep, areas and the sediment pond,
where site visitors could be accidentally exposed to the
contaminants through direct dermal contact, incidental
ingestion, or inhalation of volatiles emanating from the
leachate. Note: the security fence to be implemented as
part of OU 2 for this site will minimize dermal contact.
The fence will not restrict migration of the leachate
from the landfill area.
The pathways were quantitatively evaluated in the Risk
Assessment section of the Strasburg Landfill Remedial
Investigation report. The groundwater pathway was found to pose
the greatest potential risk of the three pathways, (see Tables 5
and 8 for summary of Site risks) The impact of groundwater on
people most directly impacted by the observed contamination has
been partially addressed in past actions at the Site. The final
RI/FS for this Operable Unit also considered and addressed, to a
limited extent, remedial alternatives for groundwater. Control
of site access does not affect this pathway. Using site
contaminant concentrations presented in the tables above, a
reasonable maximum exposure (RME) estimate was developed based on
estimated frequency and exposure duration that the receptor
population (Site visitor) is likely to experience. Various
physiological parameters (e.g., breathing rate, ingestion rate,
body weight, etc.) were incorporated to obtain an estimate of
the lifetime average daily dose of a contaminant. For the
inhalation pathway, site visitors come in contact with volatile
contaminants on site by inhalation only. For the accidental
contact pathway, site visitors could be exposed to contaminants
by direct dermal contact, incidental ingestion, and by inhalation
of vapors from leachate.
A brief review of the key parameters for the three pathways
follows:
For the inhalation pathway: Since site visitors walk, jog,
and ride horses, motorcycles or ATV's on site, an inhalation rate
corresponding to light to moderate activity was used. The
exposure time, the expected duration of a site visit, was assumed
to be one hour per day. The exposure frequency, the number of
days per year during which site visits might occur, was assumed
to be 100 days/year. Averaging time, the period over which the
estimated exposure is averaged, was taken as 30 years for
noncarcinogens (90 percentile for time spent at one residence)
and 70 years for carcinogens, corresponding to the carcinogenic
potency slope factors which are based on lifetime exposures.
For the accidental contact pathway, two exposure scenarios
were evaluated in the risk assessment. The first exposure
scenario involved a site visitor and accidental contact with the
seep material by partial or total emersion. The second exposure
-21-
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scenario involved accidental contact with the seep material by
having the seep material splashed 'on a site visitor after riding
a motorcycle, ATV, or horse through a leachate seep. Dermal
absorption of contaminants depends on the dermal permeability
constant of the specific chemical compound. Since specific data
for this constant were not available for most chemicals found in
the seep areas, constants for organic compounds vere assumed and
chosen to reflect an inverse relationship to the octanol/vater
partitioning coefficient for that compound.
For the ingest ion pathway, exposure is based on the
consumption of 2 liters per day of the groundwater (see Table 5).
For the first exposure scenario, skin surface area was taken
as equivalent to the area of the arms, legs, hands, and feet that
would likely come into contact with seep water or sediment. The
exposure frequency for the first accidental contact exposure
scenario was assumed to be four times per year.
For the second exposure scenario, skin surface area was
taken as equivalent to the area of the hands, and one half the
area of the arms and legs. The exposure frequency was assumed to
be 50 times per year.
Exposure time for each accidental exposure scenario was
assumed to be one hour, the estimated time for a site visitor to
return home and remove wet clothing. Incidental ingestion by
hand-to-mouth contact was included in each accidental contact
exposure scenario and was taken as 100 mg/day based on EPA
guidance. Inhalation rates for the accidental contact exposure
scenarios were the same as used for the inhalation pathway, other
values were also the same.
Using the estimates of a lifetime average daily dose of a
particular chemical under the RME scenario and assumed values for
key parameters, risks posed by the chemical contaminants are then
evaluated. Noncarcinogenic risks are assessed by calculating a
hazard index, the ratio of estimated average daily dose to the
reference dose, which is considered an allowable daily intake. A
hazard index greater than 1.0 indicates that adverse effects may
be possible. A hazard index value less than 1.0 indicates that
adverse effects would not be expected. For carcinogenic
compounds, a linearized multistage model is used to estimate the
carcinogenic potency slope factor. The lifetime average daily
dose is multiplied by the low-dose slope factor for each route of
exposure to a particular compound; carcinogenic risk is then
estimated by adding the risks due to oral, dermal, and inhalation
routes.
The remedial investigation was designed to characterize the
nature, extent, and limits of contamination originating at the
strasburg Landfill. The possible source areas were identified
-22-
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based on a review of past activities at the site and previous
sampling activities. All of the potential source.areas and
migration pathways were investigated using various field
techniques and by collection and laboratory analysis of samples.
In this way, the nature of the contamination was characterized
and its extent defined. Given the information available about
the site, it seems unlikely that any significant source areas or
migration pathways were overlooked. Since samples were collected
from a variety of media encompassing all of the likely source
areas and migration pathways, and samples from most of the media
except soil gas were analyzed for the full Target Compound List
(TCL) plus any non-TCL organics that were found, it is also
unlikely that any significant contaminants would have been
missed. ' .
For the purposes of risk assessments, EPA uses the notation
of 1Q"4 which means an incremental risk of 1 additional cancer in
an population of 10,000 people exposed for 30 years. These
numbers are incremental over the normal risk of approximately one
cancer in every four individuals that occurs naturally. 1CT6
represents a risk of 1 additional cancers in an exposed
population of one million people.
EPA has recently adopted a policy that acceptable exposures
to known or suspected carcinogens are generally those that
represent an excess upper bound lifetime cancer risk to an
individual of between 10"4 and 10~6. In addition, EPA will use
the 10~6 risk level as the point of departure for determining
remediation goals for NPL sites. For systemic toxicants
(noncarcinogens), EPA defines acceptable exposure levels as those
to which the human population, including sensitive subgroups, may
be exposed without adverse effects during a lifetime or part of a
lifetime, incorporating an adequate margin of safety (EPA 1990).
This acceptable exposure level corresponds to hazard index of l.
If the hazard index is less than 1, no adverse effects would be
expected. If the hazard index is greater than 1, adverse effects
could be possible.
Based on the human health risk assessment presented in the
Strasburg Landfill Remedial Investigation Report, estimate hazard
indices for systemic toxicants did not exceed 1 (the largest was
0.15) for any the pathways. Therefore, the remainder of this
discussion focuses on the sources of the potential cancer risks.
The magnitude of the potential cancer risks posed by site
contaminants are summarized in Table 8. Estimates of reasonable
maximum exposure and risks potential residential receptors are
based on 30-year exposures, since that is the 90th percentile
amount of time an individual lives at a single residence (EPA
1989b).
-23-
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Table 6 . .
CONTAMINANT CONCENTRATIONS IN WATER AND
SEDIMENT IN SEEP AREAS USED FOR EVALUATING
ACCIDENTAL CONTACT WITH THESE AREAS
UCL* Concentration - Upper 95th % Confidence Limit on
Arithmetic Mean
Chemical (/jg/kg-soil Mg/L-vater)
OROAHXCS
Benzene 6.1
bis(2-Ethylhexyl)phthalate 280
Chlorobenzene . 20.8
Chloroethane 4.85
1,2-Dichlorobenzene 3.98
1,4-Dichlorobenzene 16
1 , 1-Dichloroethane 24.8
l,2-Dichloroethane 2.94
1,2-Dichloroethene 22.2
1,2 -Dichloropropane 4.43
Ethylbenzene 39.5
Naphthalene 38.9
Toluene 1.4
Trichloroethene 4.97
Vinyl chloride 19.1
Xylenes 104
INORGANICS
-------
STRASBURG LANDFILL
SUMMARY OF CONTAMINANTS FOUND IN SOIL GAS AND AMBIENT AIR
COMPOUND AMBIENT AIR SOIL GAS FLUX BOXES
Concentration Concentration Concentration
Range/Detection Range/Detection Range/Detection
Frequency(ppb) Frequency(ppb) Frequency(ppb)
Benzene
Dibromomethane
1,1-Dichloroethene
1,2-Dichloroethene 0/91
Dichlorotetrafluoroethane N/A
Ethylbenzene N/A
Tetrachloroethene 17/91
Toluene N/A
Trichloroethene 30/91
Trichlorofluoromethane N/A
24/91 2 - 10,000
0/91
40/91 17 - 1,700
10 - 4,400
80 - 5,400
1,3,5-TrimethyIbenzene N/A
Vinyl Chloride 44/91 60 - 11,000
m/p-Xylene N/A
9/10
6/10
5/10
3 - 150
4 - 224
2 - 840
o-Xylene
N/A
N/A: Not analyzed.
7/10 2 - 11,000
N/A
N/A
7/10 1 - 567
N/A
3/10 3-84
N/A
N/A
6/10 1 - 129
N/A
N/A
0/10
0/10
0/10
2/10
3/10
1/10
1/10
1/10
1/10
3/10
1/10
1/10
3/10
2/10
0.08 - 0.64
0.03 - 0.06
0.29
0.09
1.53
0.14
0.46 - 1.65
0.04
0.48
0.23 - 0.57
0.10 - 0.18
-25-
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Table 8
SUMMARY OF ESTIMATED EXCESS LIFETIME CANCER RISKS
TO BTRABBURQ LANDFILL SITE RECEPTORS
Pathway Csss
Inhalation RNE to
Ot Airborne Site
Contasilnonts Visitors
Accidental RNE
'ontect with
;,*p Areas
n
fatal Risks RNE
to Site
laceptors
Adults
30-Veer
Exposure
5.6 x 10*
OX)
5.4 x 10*
8X
6.0 x 10*
Receptor*
Children
Child/Adult
1-6 6-12 12-18 1-31
Yssrs Vesrs Vesrs Veers
2.5x10* 1.3x10* 6.4 x 10*
OX)
2.0 x 10* 1.2 x 10* 6.5 x 10*
8X
2.3 x 10* 1.3 x 10* 7.1 x 10*
Composite
Contributions
by Exposure
Route
Inhalation - 100X
Denial - SOX
Ingest ion - 7X
Inhalation - 44X
Risk
Risk
Contributions
by Chesitcsl
VC - SIX
1.1-DCE - MX
•enzene - 4X
ICE - 3X
Arsenic - SOX
VC - 9X
•erylliua) •
1.1-DCA - 2X
•EHP - IX
Key:
RNE • Reasonable Max in* Exposure RENP •Bts(2-ethylhexyl )phthaUte
PCE • Tetrachloroethene 1,1-OCA • 1.1-Dlchloroethane
TCE • Trlchloroethene
VC • Vinyl chloride
1,2-DCA • 1,2-Dtchloroethane
1,1-OCE • 1.1-Dlchloroethens
1.2-OCP « 1,2-Dlchloropropan*
o
© fD
-26-
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Among 30-year residents, the greatest exposure and risks
would accrue to an individual living at a residence from birth
through early adulthood, since children tend to experience
greater exposure than adults in the same setting. This occurs
for two main reasons: children engage in more exploratory
behavior than adults, thereby increasing their potential contact
with contaminants, and children have greater ingestion-rate-,
inhalation-rate-, and skin-area- to body-weight ratios than
adults, thus increasing the intensity of their exposure in a
given situation. For these reasons, potential risks to a
composite child/adult receptor, age 1 to 31 years, were estimated
by summing risks for age groups explicitly evaluated.
•* -
For on-site air exposure and accidental contact with seep
areas, the risk for children 6 to 12 years old and 12 to 18 years
old, were combined with adult risks representing 18 years of
exposure to complete the 30-year exposure period. Children 1 to
6 years old would be unlikely to wander onto the landfill
unaccompanied by an adult; thus, omission of the age group from
these pathways would be unlikely to affect the estimated
composite risks. Using the risk estimates for the composite
child/adult population, the most sensitive population, as shown
in Table 8, the magnitude of potential cancer risks to site
visitors posed by site contaminants was estimated to be 6.5 x
10~6 for accidental contact with seep areas and 6.4 x 10"7 for
inhalation of airborne contaminants. The excess lifetime cancer
risk for a site visitor exposed for 30 years to the site
contaminants in the air and seep areas is 7.1 x 10~6.
This means that an individual visiting the Site for the
recreational purposes described (walking, jogging riding horses,
ATVs or motorcycles) has a little more than one chance in a
million of developing a cancer that otherwise would not have
developed.
Also shown in Table 8 are the risk contributions
attributable to the different chemical contaminants and to the
different routes of exposure. For the inhalation pathway, all of
the exposure is attributed to inhalation with the greatest risk
posed by vinyl chloride (51%) followed by 1, l-dichloroethene.
For the accidental contact pathway, half of the exposure is
attributed to dermal route, 44% to inhalation, and the remainder
to ingestion; most of the risk (80%) is attributed to arsenic
exposure.
Cancer potency factors (CPFs) have been developed by EPA's
Carcinogenic Assessment Group for estimating excess lifetime
cancer risks associated with exposure to potentially carcinogenic
chemicals. CPFs, which are expressed in units of (mg/kg-day)"1,
are multiplied by the estimated intake of a potential carcinogen,
in mg/kg-day, to provide ah upper-bound estimate of the excess
lifetime cancer risk associated with exposure at that intake
-27-
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level. The term "upper bound" reflects the conservative estimate
of the risks calculated from the CPP. Use of this approach makes
underestimation of the actual cancer risk highly unlikely.
Cancer potency factors are derived from the results of human
epidemiological studies or chronic animal bioassays to which
animal-to-human extrapolation and uncertainty factors have been
applied.
Reference doses (RfOs) have been developed by EPA for
indicating the potential for adverse health effects from exposure
to chemicals exhibiting noncarcinogenic effects. RfDs, which are
expressed in units of mg/kg-day, are estimates of lifetime daily
exposure levels for humans, including sensitive individuals, that
is not likely to be without an appreciable risk of adverse health
effects. Estimated intakes of chemicals from environmental media
(e.g., the amount of a chemical ingested from contaminated
drinking water) can be compared to the RfD. RfDs are derived
from human epidemiological studies or animal studies to which
uncertainty factors have been applied (e.g., to account for the
use of animal data to predict effects on humans). These
uncertainty factors help ensure that the RfDs will not
underestimate the potential for adverse noncarcinogenic effects
to occur.
Excess lifetime cancer risks are determined by multiplying
the intake level with the cancer potency factor. These risks are
probabilities that are generally expressed in scientific notation
(e.g., IxlO"6 ). An excess lifetime cancer risk of 1x10~6
indicates that, as a plausible upper bound, an individual has a
one in one million chance of developing cancer as a result of
site-related exposure to a carcinogen over a 70-year lifetime
under the specific exposure conditions at a site.
Potential concern for noncarcinogenic effects of a single
contaminant in a single medium is expressed as the hazard
quotient (HQ) (or the ratio of the estimated intake derived from
the contaminant concentration in a given medium to the
contaminant's reference dose). By adding the HQs for all
contaminants within a medium or across all media to which a given
population may reasonably be exposed, the Hazard Index (HI) can
be generated. The HI provides a useful reference point for
gauging the potential significance of multiple contaminant
exposures within a single medium or across media.
As discussed above, the incremental cancer risk, using all
these conservative assumption factors is 7.1 X 10". While this
[risk] is within the 10'6 to 10~4 risk range that EPA uses to
initiate remedial action, it is above the 10~6 "starting point"
the EPA uses as a baseline for decisions.
Actual or threatened releases of hazardous substances from
this site, if not addressed by implementing the response action
-28-
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selected in this ROD, may present an Imminent and substantial
endangerment to public health, welfare, or the environment.
ECOLOGICAL RISKS
Ecological field investigations and risk assessments were
conducted in the 400-acre study area surrounding the Strasburg
Landfill site to characterize the biological communities and
determine if significant ecological resources are potentially
affected by site contamination. The ecological site survey and
contacts with natural resource trustee personnel indicated the
presence of high-quality habitat in the study area. The landfill
is surrounded by apparently healthy, diverse terrestrial and
aquatic communities, including river, wetland, forest, and open-
field ecosystems harboring abundant wildlife populations. Stream
surveys of benthic invertebrates indicated no alteration of
community structure directly downstream from the site, and there
was no other obvious evidence of adverse effects of chemical
contamination on the existing populations, communities, or
ecosystems. Other than the identified wetlands, no significant
sensitive or protected biological resources (such as endangered
species) are known to occur in the study area. Several species
with special status in the Commonwealth of Pennsylvania have been
reported in the vicinity, however, and these or other protected
species could conceivably come in contact with the site or
establish populations there. The Brandywine Conservancy
Management Center manages two nature preserve properties within
one mile of the landfill, providing potential source populations
of special-status species.
The ecological risk assessment for the Strasburg Landfill
site identified elevated levels of contaminants relative to
background concentrations and environmental concern levels in
seep areas, surface water, sediments, and soil gas. Potential
low-level, chronic exposure of aquatic biota to site-related
contaminants is considered likely from uncontrolled releases at
seep areas and from runoff into surrounding wetlands and streams.
No single contaminant appears to be occurring in surface water at
levels toxic to aquatic life, but bioassay results demonstrate
that seep water is toxic to indicator organisms tested under
laboratory conditions. Shannon Diversity Indices were calculated
for the benthic invertebrate samples collected at upstream and
downstream locations in Briar Run and Brandywine Creek. For both
streams, the diversity indices were higher downstream of the
landfill than upstream. Thus, there is no evidence of a decrease
in diversity of benthic invertebrates downstream of the landfill
in either Briar Run or Brandywine Creek.
Although sediment contamination is not sufficient to alter
benthic community composition in Briar Run, there is evidence of
elevated levels of metals in wetland sediments with the potential
-29-
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to migrate downstream. This migration may have toxic effects on
some aquatic organisms. •
Terrestrial organisms may also be exposed to site-related
contaminants, particularly landfill air emissions of volatile
organic compounds (VOCs). For example, small mammals such as
field mice inhaling air on the landfill perimeter may be exposed
to toxic levels of VOCs migrating from soil gas to the near-
ground ambient air. Elevated and potentially toxic levels of
vinyl chloride occurred in soil gas plume areas on the east and
vest sides of the landfill, and benzene, PCE, and 1,1-DCE were
present at elevated and potentially toxic levels on both sides of
the landfill. Small mammals could also be at risk from elevated
levels of barium in drinking water at the seeps.' The potential
risks to small mammals decrease rapidly with distance from the
landfill and are likely to be negligible for all populations
except those residing on the landfill and its perimeter or in
wetlands adjacent to the landfill. Because of the limited
spatial distribution of chemical contamination, predators and
scavengers that utilize small mammals as prey probably face
negligible risks from feeding on a contaminated food source or
from reduced abundance of prey populations.
In summary, it can be clearly seen that the Site poses risk
to the human health and the environment. Leachate seeps pose
risk to site visitors and trespassers. Leachate also enters the
local natural environment through run-off into Briar Run and
surrounding soils. We also know that leachate continues to
discharge to the groundwater from the poorly capped landfill.
Alternatives to address reduction of these risks were developed
and evaluated.
7. Description of Alternatives
The Superfund statute and regulations require that the
alternative chosen to clean up a hazardous waste site meet
several criteria. The alternative must protect human health and
the environment, meet the requirements of environmental
regulations, and be cost effective. Permanent solutions to
contamination problems should be developed wherever possible.
The solutions should reduce the volume, toxicity, or mobility of
the contaminants.
The intent of this action is to reduce the health risk to
people through; elimination of present routes of exposure. In
accordance with 40 CFR $300.430 a list of remedial response
actions and representative technologies were identified and
screened to meet the remedial action objectives at this site. The
FS studied a variety of technologies to determine if they were
applicable for addressing the contamination at the Site. The
technologies determined to be most applicable were developed into
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remedial alternatives. In addition, EPA has evaluated the No
Action Alternative (Alternative iy as required by-.the National
Contingency Plan (NCP). These alternatives are presented and
discussed below. All costs and implementation time frames
provided for the alternatives below are estimates.
This action is planned to be the final action for all media
except groundwater. As stated above, groundwater will be finally
addressed in OU 4 and will be based on the data collected and
modelling after this action is fully implemented. The intent of
the OU 4 action will be to address any risk to human health and
the environment caused by exposure to the groundwater.
The current routes of exposure include ingestion of
contaminated groundwater, inhalation of landfill vapors and
direct contact with leachate seeps both in and around the
landfill surface. The population to be protected are those
people who reside in the area who use the groundwater for
ingestion and bathing purposes and also those persons who utilize
the Site for recreational activities such as motorcycle or all
terrain vehicle riding, walking, jogging, or hunting. The health
risk will be reduced by replacing the existing, improperly
installed cap and by capturing and treating the•subsurface
leachate flow before it reaches the aquifers used for domestic
purposes.
The following alternatives which were identified and
evaluated in the FS, will be developed and discussed using the
following sequence: identification of remedial action objectives;
identification, effectiveness, implementability, costs.
Note: The cost and time factors listed in this plan are estimated
values based on best engineering judgment by EPA.
Alternative 1 - No Action
Capital Cost: $ 50O
Operation and Maintenance (O&M) Costs: $l97,996/yr
Present Worth: $3,044,700
Implementation Time: 2 months
Pursuant to the NCP, this alternative was developed to
provide a baseline to which the other remedial alternatives can
be compared. For the purposes of this alternative, no action is
considered to be "no further action" and includes, as part of
the costs, maintenance of the landfill cap. This on-going cost
is also included in the other alternatives described below. This
alternative, which involves no remediation, is considered in the
detailed analysis to provide a baseline to which the other
remedial alternatives can be compared. This alternative,
however, would include some baseline items that are considered to
be appropriate based on present circumstances at the site:
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o Quarterly monitoring of the 11 existing monitoring wells,
and EPA-designated residential wells in the surrounding
community.
o Periodic ambient air monitoring;
o Operation and Maintenance of the existing landfill cap
(such as mowing and repairs) and the remedies being
implemented under on 1 and OU 2.
Alternative 1A - Limited Action
Capital Cost: $ 1,000
O & M Costs: same as above
Implementation Time: 1 month
Alternative 1A would include all of actions listed above in
the "no action" alternative, with the addition of deed
restrictions on the immediate landfill property (at no additional
cost or time). Deed restrictions, which are considered
"institutional controls," are sometimes implemented at locations
to restrict actions such as the development of new drinking water
wells. Under this alternative, EPA would seek to restrict usage
of the site for usages, such as human habitation, until such time
as the risk levels in the various exposure media were reduced to
acceptable levels.
Alternative 2 ~ Source Containment (capping} and Landfill Gas
Em.issji.ons Collection (venting)
Capital Cost: $6,162,497
O & M Costs: $277,011 / yr
Present Worth: $10,420,850
Implementation Time: 24 months
Alternative 2 involves containment of the landfill by
capping, in addition to the provisions made under the no-action
alternative (excluding the environmental monitoring). Con-
tainment technology, such as capping, is intended to reduce
landfill emissions, infiltration of precipitation, and the amount
of leachate produced would be reduced. The capping technology
selected is a multilayered cap, due to the existing slopes and
intended land use. From among the various types of multilayered
caps, the type whose performance is specified in 25 PA Code
Chapter 264, Subchapter 6 is selected for containment of the
landfill.
This technology involves clearing and grubbing, grading, and
covering site soils with approximately 24 inches of compacted
clay and an impermeable synthetic membrane that is covered by
approximately 24 inches of compacted sand. The compacted clay
and synthetic membrane act as barriers to the infiltration of
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water, while the top sand layer provides a drainage way for
percolating water. Overlying these materials is 12 inches of
loam (topsoil) to allow for revegetation. This sequence of
materials meets the requirements of 25 PA Code, Chapter 264,
Subchapter 6 for capping at a new facility. This technology
takes advantage of the self-repairing properties of clay, along
with the impermeable nature of a synthetic membrane. Six
operations are required to complete the construction of this cap,
and seams in the membrane require careful installation and
sealing.
The existing cap would be removed (excavated) prior tc the
installation of a new cap (specified for hazardous material
landfills). Capping would be performed over the entire 22-acre
area (including the sides) of the Strasburg Landf-ill.
In addition to capping, the gas generated within the
landfill would be vented to the atmosphere by installing a
passive type of gas collection system. This collection system
would be installed at the time the landfill cap was being
installed. The collection system would be flexible enough to
allow the addition of a gas treatment unit in the future, if
determined essential. A passive gas collection system has
advantages over active gas collection. If the landfill gas is
collected actively, it would draw air into the landfill, which
will increase the volume of the gas and shift the solid-to-gas
equilibrium, increasing volatile organic compound (VOC)
concentration in the gas. It may also interfere with the
anaerobic biological decomposition process and therefore reduce
the quantity of methane gas being generated. Calculations
performed during the feasibility study showed that introduction
of excessive amounts of oxygen into the landfill could cause a
fire to start due to spontaneous combustion.
Operation and maintenance (O&M) of the landfill cap consists
of maintaining the vegetative cover (including mowing and
grubbing); making repairs in the cap as they are needed; and
removing debris from the leachate witness system.
/
Alternative 3 — Source Containment? Landfill Gas Eirijg?iong
Discharge
Capital Cost: $6,502,997.
O&M Costs: $312,471./yr
Present Worth:.$11,306,460.
Implementation Time: 30 months
In addition to all aspects of Alternative 2, Alternative 3
includes a secondary leachate collection system on the southwest,
south, and southeast sides of the landfill. A trench around the
southern boundaries of the landfill will be used for collecting
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the leachate flowing by gravitational force. Currently, the
leachate is being collected by the existing leachate collection
system below the landfill and treated in an air stripper
constructed and maintained by Clean Harbors, Inc. Additional
leachate collected by the secondary leachate collection system
would be treated by UV-ozone oxidation and discharged to the
surface water. For an innovative technology such as UV-ozone
oxidation, pilot tests would be conducted prior to full-scale
operation. This alternative would not only reduce the vertical .
infiltration of water but also would collect and treat the
leachate rather than allowing it to migrate off site.
O & M of the cap would be the same as with Alternative 2.0 &
M of the leachate collection and treatment system would entail
keeping the collection system free of sedimentation and
maintaining the UV/ozone treatment in working order so that NPDES
compliance can be maintained.
Alternative 4 •» ?ource Contain.ff?n.1r r Landfill *??j? ^missions
Collection and Treatment
Capital Cost: $6,232,497.
o & M costs: $310,Oil./yr
Present Worth: $10,998,140.
Implementation Timet 26 months
Alternative 4 consists of the actions described for
Alternative 2, in addition to the treatment. of landfill gas
emissions. Even after installing the landfill cap, as per
Alternative 2, the need for treating landfill gas emissions
containing VOCs and methane might exist.
Landfill gas emissions would be collected actively and
treated for VOCs by a Vapor Phase Activated Carbon (VPAC) column
followed by flaring to destroy methane. If the moisture content
of the landfill gas emissions is high enough to warrant moisture
removal before treatment, then demoisturizing columns containing
silica gel, self-indicating molecular sieves, or desiccants would
be utilized. Landfill gas emissions would be dried before
entering the VPAC column for treatment of VOCs, which would help
to prolong the life of the column.
For the purpose of this proposal, an active collection and
treatment system for landfill gas emissions is designed based on
several assumptions. The concentration of VOCs in the landfill
gas was estimated using air emissions data from the risk
assessment section of the RI report. The gas-generation rate was
estimated using factors in the Solid Haste Handbook (Robinson
1986). The volume and weight of the landfill contents were
estimated using approximate area and depth calculations. The
spent carbon filter units would also have to be disposed of in a
manner consistent with appropriate RCRA regulations.
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0 & M costs for the cap maintenance will be the same as for
Alternative 2. O & M costs incurred for the gas venting system
will involve periodic replacement of the gas filter system units,
including filter media, and appropriate disposal costs.
Alteimative 5 — Source Containment? Landfill Gas Emissions
Treatment, and Discharge
Capital Cost: $6,572,997
O & M Costs: $345,471./yr
Present Worth: $11,883,750.
Implementation Time: 30 months
Alternative 5 is a combination of alternatives 3 and 4.
This alternative would include the multilayered type landfill cap
(as containment); active landfill gas collection, filtration, and
flaring of landfill gases; expanded leachat® collection and
treatment via an extended trench around the southern and
southwestern boundaries of the landfill; and the basic actions
planned under the no-action alternative. A detailed description
of this alternative is a summation of alternatives 1, 3, and 4.
O & M costs associated with Alternative 5 would be a
combination of the 0 & M elements associated with Alternatives 3
and 4.
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8. *?1TffTlflT'V of Comparative Analysis of Alternatives,
An analysis was performed on all of the alternatives using
the nine criteria specified in the NCP in order to select a
remedy for OU 3 . An explanation of the nine criteria is attached
as Exhibit A. These nine criteria are organized according to the
groups below:
CTERIA
Overall protection of human health and the environment
Compliance with applicable or relevant and appropriate
requirements (ARARs)
PRIMARY BALANCING CRITERIA
Long-term effectiveness
Reduction of toxicity, mobility, or volume through treatment
Short-term effectiveness
Implementability
Cost
MODIFYING CRITERIA
Community acceptance
State acceptance
These evaluation criteria relate directly to the
requirements in Section 121 of CERCLA, 42 U.S.C. Section 9621,
which determine the overall feasibility and acceptability of the
remedy.
Threshold criteria must be satisfied in order for a remedy
to be eligible for selection. Primary balancing criteria are
used to weigh major trade-offs between remedies. State and
community acceptance are modifying criteria formally taken into
account after public comment is received on the Proposed Plan.
The following is a summary of the comparison of each of the
alternatives' strengths and weaknesses with respect to the nine
criteria.
Overall Protection of Health and Environment
All of the alternatives evaluated for this remedy are
considered to prevent contact with contaminated surface soil and
leachate, thereby limiting human exposure and reducing future
risks. The no-action and limited action alternatives would not
reduce the health risks associated with the site more than the
two interim actions, i.e., point-of-use carbon treatment for the
two affected residential drinking water wells (implemented March
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EXHIBIT A. filSClXPfXOV Of ITlLOlf XOM C&IT111A
Ovarall Protection of Human ffaalth and tha tnvironaanfcal •
addreeaes whether or net a remedy will: cleanup a site to within
the risk range* result in any unacceptable impacts; control the
inherent hazard (e.g., texicity and mobility) associated with a
site; and minimise tha short-term impacts associated with
cleaning up -tha a it a.
JL«AJt»a • addraaaaa vhathar or not a raaady will
•aat all tha applicable or relevant and appropriate retirements
of other environmental atatuaa and/or provide grounds for
invoking a waiver.
q»fcar» tf fecttvanasa and PeMt
nea • refers to the ability of
a remedy to maintain reliable protection of human health and the
environment over time, once cleanup goals have been met.
of Tax Jetty. Mobility, or Volume through Tg —
refers to the anticipated performance of the treatment
technologies that may be employed in a remedy.
iff«etiv«M«e • refers to the period of time needed
to achieve protection* and any adverse impacts on human health
and the environment that may be) posed during the construction and
implementation period until cleanup goals are achieved.
TaBiMMtabiiitv . describes the technical and administrative
feasibility of a remedy, including the availability of materials
and services) needed to implement the chosen solution.
£&•£ - includes the capital for materials, eg*tipmeat, ete. and
the operation and maintenance cost.
gu«»ag» a^May ftflgtBtif^* • indicates vhether, based on its
review of, the XX, Ft and £he Proposed Man, the State concurs
with, opposes, or has no comment on tha preferred alternative.
M . vill be assessed in the Record of Decision
following a review of the public comments received en the XX, PS,
and tha Proposed tten. ,
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1990) and fencing the Immediate landfill area to-restrict site
access (implementation pending). •
The no-action and limited action alternatives would not
provide any protection of the environment. They would continue
to allow landfill-generated leachate to migrate into groundwater
and contaminated groundwater to migrate off site. The interim .
action, point-of-use carbon treatment, implemented earlier as
part of OU 1, is effectively reducing the human health risks in
the groundwater pathway at the two affected residential drinking
water wells southwest of the landfill.
Alternative 2 (source containment by capping-and gas
venting) would reduce the human health risks and environmental
receptor exposure by reducing or eliminating the direct-contact
pathway with leachate seep material. These actions in
conjunction with the interim action to restrict site access will
reduce the site-specific identified health risks to acceptable
levels. This alternative would notf however, reduce the human
health risk or environmental receptor exposure to the inhalation
exposure pathway, since only gas venting, and not gas collection
and treatment, is included in Alternative 5.
Alternative 3 (source containment by capping, gas venting,
leachate collection, treatment, and discharge) would reduce the
amount of leachate that may contaminate the groundwater and
migrate off site in addition to the protection provided by
implementation of Alternative 2. This alternative provides
source containment by capping, which would reduce the vertical
infiltration of rainwater, therefore reducing the volume of
leachate to be treated. Because less leachate would enter the
groundwater, the groundwater contamination process would be
slowed down. This action would supplement the interim action
point-of-use carbon treatment implemented earlier as part of OU
l, which treats the contaminated groundwater that is used as
drinking water at the two residences southwest of the landfill.
Alternative 4 (source containment by capping, and gas
collection and treatment) would reduce the human health risks and
environmental receptor exposure by reducing or eliminating the
direct contact pathway with leachate seep material and the
inhalation pathway of landfill gas emissions. These actions, in
conjunction with the interim action to restrict site access, will
provide a reduction of the site-specific identified health risks
to acceptable levels. The items in this alternative will not
eliminate groundwater contamination because landfill-generated
leachate will continue to contaminate groundwater and migrate off
site.
Alternative 5 (source containment by capping; leachate
collection, treatment and discharge; and gas collection and
treatment) would reduce the human health and environmental
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receptor exposure by reducing or eliminating the direct contact
pathway with leachate seep material and the inhalation pathway of
landfill gas emissions. These actions in conjunction .with the
previously implemented interim action to restrict site access
will provide a reduction of the site-specific identified health
risks to an acceptable level. Leachate collection, treatment,
and discharge would reduce the amount of leachate available to
contaminate groundwater and migrate off site. The landfill cap
will reduce or eliminate water, particularly rainwater, from
peculating through the landfill and into the groundwater. This
action would supplement the interim action, which was part of OU
1 which is point-of-use carbon treatment, implemented earlier, to
treat contaminated groundwater used as drinking water at the two
residences southwest of the landfill.
Alternatives 2 and 4 are less protective since they do not
address the leachate which has been evidenced as entering the
water table. Alternatives 3 and 5 both provide additional
protection in that both propose to add additional collection and
treatment for leachate in the upper portion of the aquifer.
Alternative 5 is most protective in that it also seeks to treat
the vented air emissions from the landfill.
Compliance with ARARs
CERCLA requires that remedial actions meet applicable or
relevant and appropriate requirements (ARARs) of other federal
and state environmental laws and/or provide grounds for invoking
a waiver. These laws may include, but are not limited to : the
Toxic .Substances Control Act, the Clean Water Act, the Safe
Drinking Water Act, and RCRA.
A "legally applicable" requirement is one which would
legally apply to the response action if that action were not
taken pursuant to Sections 104, 106, or 122 of CERCLA. A
"relevant and appropriate" requirement is one that, while not
"applicable," is designed to address problems sufficiently
similar to those encountered at the Site, and is appropriate to
the circumstances of the release, or threatened release, such
that its use is veil-suited to the particular site.
There are a number of specific requirements which will need
to be met for this action. The Federal and State ARARs include:
o The landfill caot The Pennsylvania Municipal Landfill
Regulations, as contained in 25 PA Code S 273.322 (a) and
(b), are applicable for this landfill cap. However, because
the landfill accepted wastes which were hazardous as
specified in 40 CFR $261 Subpart C (or constituents as
contained in Subpart D), and 25 PA Code Part 261 Subpart C
(or constituents as contained in Subpart D), the following
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PA Hazardous Waste Regulations would be relevant and
appropriate to this action, as specified in Title 25 PA
Code, Chapter 264, Subchapter 6 sections:
264.111 Closure Performance
264.117 Postclosure care and;
264.118 Postclosure Plan, Amendment of Plan
Specifically subsections a, a(l), a (2) (i) and
(ii), a(3)
and Subchapter N sections:
264.301 Design Requirement General: specifically
subsections: 264.301(5) , (6) , and (12)-(15)
264.303 Leachate Management
264.310 Closure, Postclosure Care
To the extent that portions of the old cap or other
materials may have to be disposed of off -site, the Land
Disposal Restrictions as contained in 40 CFR Part 268
EBigsjons from the landfill: 40 CFR Part 264 subpart AA
for VOCs and the National Emissions Standards for Hazardous
Air Pollutants (NESHAPs) , as contained in 40 CFR Part 61, as
well as the National Ambient Air Quality Standards (NAAQg) ,
as specified in 40 CFR Part 50, and the PA Air Pollution
Control Act and Air Discharge Regulations, as specified in
25 PA Code Sections 123 and 127.1 (not exempted by Section
127.14).
o Discharges of the treated leachate from the landfill:
National Pollutant Discharge Elimination System (NPDES) as
specified in 40 CFR Part 122, Subpart C, and PA Clean
Streams Law, as specified in 25 PA Code Chapters 92, 93, 94
and 96.
EPA and PADER have agreed to model the groundwater
contamination levels after this alternative is implemented for a
minimum period of two years. Therefore, Groundwater Protection,
as specified in the PA Hazardous Waste Management Regulations, as
contained in 25 PA SS 264.97(i)(j) and 264.100 (a) (9) , are not
ARARs for this operable unit. Sampling will be conducted on a
quarterly basis. A determination will be made at that time as to
the type of further treatment to be considered in OU 4 for this
site.
In reviewing the ARARs for this operable unit the following
is a discussion as to how each of the alternatives would comply:
The no-action and limited action alternatives would not meet
any identified ARARs. In addition, these alternatives would not
reduce the site-specific identified health risks associated with
the site.
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The leachate treatment system as contemplated as parts of
Alternatives 3 and 5 would meet the requirements of a PADER NPDES
discharge permit to Briar Run or Brandyvine Creek.
Under Alternatives 2, 3, 4, & 5, capping the landfill with a
designed impermeable cap would meet the PADER closure ARARs.
Groundwater would continue to be contaminated by leachate from
the landfill. The amount of leachate generated by precipitation
infiltrating through the cap would be significantly reduced and
perhaps totally eliminated. Capping would reduce the site-
specific identified health risk to human and environmental
receptors by reducing or eliminating leachate seeps that exist on
the landfill and by reducing or eliminating the direct-contact
exposure pathway associated with the leachate seeps. Collection
and treatment of landfill-generated leachate would tend to reduce
the amount of leachate contributing to groundwater contamination.
Under Alternatives 3 & 5, installation of a cap would meet
the PA Municipal Landfill regulations, as well as the PA
Hazardous Waste Regulations. Collection and treatment of
landfill-generated leachate would tend to reduce the amount of
leachate contributing to groundwater contamination. The
treatment system would provide adequate treatment of the
collected leachate to meet the requirements of a PADER (NPDES)
discharge permit to Briar Run or Brandyvine Creek.
Alternative 4, installation of a cap, would meet the PA
Municipal Landfill Regulations and the PA Hazardous Waste
Regulations. Capping and gas collection and treatment would
reduce the site-specific identified human health risks and
environmental receptor exposure by reducing or eliminating the
direct contact pathway for the leachate seeps and the inhalation
pathway. The gas treatment plant would meet applicable design
and treatment standards.
r
Alternative 5 would require installation of a cap which
would meet the PA Municipal Landfill Regulations and the PA
Hazardous Waste Regulations regarding landfill capping require-
ments. Collection and treatment of landfill-generated leachate
would tend to reduce the amount of leachate contributing to
groundwater contamination. The treatment system would provide
adequate treatment of the collected leachate to meet the
requirements of a PADER (NPDES) discharge permit to Briar Run or
Brandywine Creek.
Alternatives 2/3, 4, & 5 would satisfy the requirements
for the landfill cap. Testing performed to date would indicate
that air emissions are in compliance with the cited ARARs,
however, vent gas treatment as proposed under Alternatives 4 and
5 would provide extra assurance that no violation of the NESHAPS
would occur.
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Long-Term Effectiveness and Permanence
As no remedial action is planned under the no-action and
limited action alternatives, the magnitude of risks identified in
the Risk Assessment portion of the RI report will remain;
however, some of the risks may gradually reduce due to natural
attenuation. The landfill, as a source of contamination
(hazardous wastes), would continue to be a major source for
continual leachate migration to groundwater.
Long-term periodic monitoring of groundwater and air would
help to track contaminant activities in these media, and future
remedial action would depend upon these monitoring results. Deed
restrictions on the property and warning signs for surface water
would mitigate exposure possibilities, which would protect human
health but not the environment. The no-action and limited action
alternatives do not include any actions to repair the extensively
deteriorated existing cap, including the synthetic membrane
cover. If the existing cap is not repaired, there is a potential
for significant failure due to the existing steep slopes.
However, even maintenance of the existing cap may not prevent
further deterioration of it and the synthetic membrane cover.
These provisions, under the no-action and limited action
alternatives, are routine and established techniques. Therefore,
except for certain fluctuations in cost due to technical part
replacement, there would not be unforeseen difficulties.
Landfill leachate would continue to migrate into the
groundwater, and landfill gas emissions would continue through
the existing, compromised cover. Groundwater, surface water,
soil, and sediment would remain contaminated under Alternatives l
and 1A. Therefore, these alternatives are not considered a
permanent solutions.
Capping the landfill as anticipated under Alternative 2
would reduce the site-specific health risks further than the
access-restriction interim-action would, by reducing the leachate
and subsequent seep generation. Capping would also include
proper venting of the landfill, but this would not reduce the
health risk attributed to inhalation of air emissions, as no gas-
treatment system is included in this alternative. This
alternative would not directly reduce groundwater contamination,
as capping does not include measures to collect and treat
landfill-generated leachate in addition to the existing leachate
collection system. However, a secondary effect of capping the
landfill would be a reduction of leachate generated by the
infiltration of precipitation through the cap. This would reduce
the amount of leachate available to contaminate the groundwater.
The groundwater may begin to attenuate naturally. This
alternative would directly reduce the exposure to environmental
receptors, e.g., small animals inhabiting the landfill property,
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by reducing the direct contact pathway with leachate seep
material.
Under Alternative 3, the long-term effectiveness of capping
technology will be similar to that described in Alternative 2.
Alternative 3 also involves collection and treatment of leachate
generated within the landfill, which would prevent further
contamination of the groundwater by infiltrating leachate. The
leachate collection and treatment system would be expected to
have a long life, similar to capping with routine maintenance.
Collection trenches are routinely installed and have been shown
to be effective in capturing groundwater and leachate. Although
this alternative does not cover actual groundwater restoration/
it will help to reduce the risks by allowing natural attenuation.
Also under Alternative 3, to ensure long-term effectiveness,
annual O&M would be required on the secondary ieaehate collection
system and the UV-ozone treatment system.
Alternative 4 is a combination of capping and collection and
treatment of landfill gas emissions. While capping alone would
provide containment of the landfill, this alternative would also
mitigate the risks posed by the air exposure route by treating
the vented gas. As discussed previously, landfill caps are
effective, assuming proper maintenance is performed. Landfill
gas emissions would be treated for VOCs and methane. Collection
and treatment of landfill gas will also help to prevent pressure
buildup within the landfill.
Gas treatment is effective if designed properly. Carbon
adsorption and flaring are well-documented and effective
technologies for treating landfill gas. System maintenance and
replacement make gas treatment possible for an indefinite period
of time. Waste remaining on site somewhat limit the permanence
of Alternative 4. The gas treatment is a permanent solution, as
contaminants are destroyed.
Alternative 5 would have good long-term effectiveness. All
systems as discussed previously would operate effectively for a
long period of time with appropriate maintenance. The permanence
of this alternative is fair at best as. it only provides
containment of wastes; no destruction or removal of the source of
contamination is included. Because it includes containment of
the landfill and treatment of both emissions and leachate,
Alternative 5 would reduce risks from air exposure and
groundwater contamination. The techniques used to achieve these
treatments are described in previous alternatives.
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The no-action alternative would provide for no reduction in
toxicity, mobility, or volume. Even though some institutional
measures are planned under the limited action alternative, none
of the contaminated medium of concern will be treated and,
consequently, this alternative would not provide any reduction in
the toxicity, mobility, or volume of the contaminated media
either.
Alternative 2 involves the containment technology of capping
the landfill using a design under the performance specifications
of PA Municipal Landfill Regulation and the PA Hazardous Waste
Regulations. No treatment of any kind is planned- under this
alternative. The contaminated contents of the landfill would be
confined and sealed from the top, which would reduce leachate
generation (and thus reduce groundwater contamination) and
landfill emissions and would restrict mobility of the contami-
nants. Capping would not reduce the toxicity or volume of the
landfill contents.
A passive gas collection system would vent the landfill gas
to the atmosphere. Even though it will not reduce toxicity,
mobility, or volume through treatment, venting would help to
alleviate a possible pressure buildup of toxic gases within the
landfill.
Alternative 3 would reduce mobility, toxicity, and volume of
leachate, to a substantial extent, through treatment. Leachate
would not be allowed to migrate into the soil and groundwater,
and will be discharged to the surface water after treatment,
thereby reducing volume and toxicity of contaminated (untreated)
leachate. Capping would restrict mobility of the contaminants
similar to Alternative 2. Contaminants in leachate would be
treated. Since leachate would be collected, treated and
discharged, there would be less leachate entering and
contaminating groundwater. Groundwater contamination would be
allowed to attenuate naturally.
For alternative 4, as with alternatives 2 & 3 above, the
landfill cap will somewhat reduce the mobility of the con-
taminants leaving the landfill in the form of leachate. The cap
will reduce the amount of leachate generated and thus the amount
of contaminants entering the groundwater. Over time, it is
anticipated that the reduced contaminant loading to groundwater
and subsequent media (soil/sediment and surface water) would
attenuate naturally. The collection and treatment of landfill
emissions will eliminate the volume of gas migrating off site,
thereby reducing the mobility of contaminants. The volume and
toxicity of contaminants are completely reduced during the
treatment of the gas.
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Alternative 5 would reduce toxicity, mobility, and volume of
contaminants in air emissions as well as groundwater. .Due to
capping, the mobility of contaminants in the landfill would also
be restricted, which would have a positive impact on other media
of concern, such as groundwater, surface water, and
soil/sediment.
Capping the landfill would reduce infiltration of
precipitation into the landfill, which would decrease the
quantity of leachate generated within the landfill. As the
amount of leachate carrying contaminants and entering the
groundwater aquifer decreases, the rate at which the groundwater
is contaminated would also decrease, thereby reducing the
toxicity due to contaminants in groundwater. Also, the leachate
generated, even after capping, due to infiltration of rainwater
from the sides of the landfill, would be collected, treated, and
discharged to the surface water of Briar Run. This would also
reduce the toxicity in groundwater due to reduced loading of the
leachate.
Landfill gas emissions would be collected and treated before
being released into the atmosphere. Treatment would reduce vocs
and methane, which would mitigate the toxicity of landfill
emissions.
Short-Term Effectiveness
Under the no-action and limited action alternatives,
institutional measures and access control rather than remedial
actions are planned. These activities would not pose any risk to
the community. Monitoring and access restrictions would be
carried out by workers using the proper levels of personal
protection as specified in OSHA. There would, not be any
environmental impacts from these non-construction activities.
Except for warning signs at the perimeter of the Site area and
deed restrictions, other activities are long-term but periodic.
Installation of signs may take approximately three to four weeks.
Deed restriction is a one-time event.
Under Alternative 2, the capping contemplated would involve
constructing a multilayered cap over the landfill after removing
the existing one. During construction, short-term environmental
impacts would include noise, dust, and increased traffic through
neighborhoods. These activities would not pose any significant
risk to the community. Workers involved in the construction task
would follow OSHA specified health and safety practices. Exposed
surfaces of landfill contents would be kept to a minimum to
reduce potential on- and off-site exposures. Monitoring of
ambient air will be carried out along the perimeter and at the
work sites to identify potential exposure to workers and
residents. Operational procedures during field activities will
be modified to reduce emissions. Smoking will not be allowed in
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the area of potential emissions. Construction of. the landfill
cap may take several months.
Under Alternative 3, short-term environmental impacts due to
construction of the cap and passive leachate collection/treatment
system would be similar to those discussed for Alternative 2.
Workers engaged in construction, operation, and maintenance of
the cap and leachate collection/treatment system would have to
follow health and safety procedures. Construction may take
several months, and operation and maintenance would be long term.
For Alternative 4, during construction of the multi-layered
cap and landfill gas emissions collection/treatment system,
short-term environmental impacts, as mentioned for Alternatives 2
& 3, would occur. Standard health and safety practices would be
adhered to by construction workers. No smoking would be allowed
around gas collection and treatment activities, to prevent any
fire due to methane content of landfill gas. Special drilling
techniques and increased air monitoring for methane would be
carried out to avoid an explosion. Construction activities
would take a few months and operation and maintenance would be
long term.
Short-term environmental impacts for Alternative 5 during
construction, safety procedures, and duration of activities would
be analogous to those for alternatives 3 and 4.
Capping involves constructing a multi layered cap over the
landfill upon removing the existing one. During construction,
short-term environmental impacts would include noise, dust, and
increased traffic through neighborhoods. These activities would
not pose any significant risk to the community. Workers involved
in the construction task would follow proper required health and
safety practices. Construction of the landfill cap may take
several months. Exposed surfaces of landfill contents would be
kept to a minimum to reduce potential off-site exposures.
Monitoring of ambient air will be carried out along the perimeter
and at the work sites to identify potential exposure to workers
and residents. Operational procedures during field activities
will be modified to reduce emissions. Smoking will not be
allowed in the area of potential emissions. Appropriate drilling
techniques would be used to prevent explosions when installing
gas recovery wells.
Imolementability
Four institutional responses included under the no-action
and limited action alternatives are well established and reliable
techniques to achieve respective goals. Decisions regarding
monitoring frequency and the number of signs will be made by
consulting with the lead agency, local authorities, and any other
concerned party. Future remedial actions will be based upon the
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monitoring results. This alternative would not inhibit future
remedial action if determined to be necessary.
All of the other four alternatives evaluated for this
Decision have been proven reliable and are readily available.
Landfill caps are routinely specified for various types of fills.
There is some aimplementability" concern over the placement of a
cap which would comply with the requirements of PA Municipal
Landfill Regulations and the PA Hazardous Waste Regulations,
especially on the steep slope areas of the landfill. This will be
further evaluated during the design phase of this project. If
necessary, the top portions of the landfill, especially the
eastern slopes may have to be regraded. Adequate equipment and
personnel are available to construct any of the remedies from a
number of sources located within a few miles of the site.
Containment technology such as capping is routinely
performed when subsurface contamination at a site precludes
excavation and removal of wastes because of potential hazards
and/or unrealistic costs. It is a reliable and established
technique at landfill sites. The main disadvantages of capping
are uncertain design life and the need for long-term maintenance.
Several contractors are available to construct the landfill
cap, who would also provide heavy equipment and skilled workers.
Necessary permits and approval would have to be obtained from
regulatory agencies before actual construction began. For
venting landfill gas emissions to the atmosphere, air permits may
be required. Other additional remedial actions could be
undertaken after installation of the cap, if determined
appropriate and essential. Long-term monitoring and maintenance
plans would also be designed and implemented.
The implementability of the portion of alternatives 2, 3, 4,
& 5 involving capping of the landfill is dependent upon the
stability, design, and condition of the Strasburg Landfill. Some
concerns include:
o That the slopes of the landfill sides are too steep;
o That the stability of the landfill is not studied; and
o That part of the landfill is sitting in the groundwater.
Information on the existing design and construction details
of the Strasburg Landfill, as well as stability information, will
need to be collected during cap design. The cap included in
these alternatives is based on assumptions about the integrity
and stability of the landfill.
Special design features will be needed to cover the steep
slopes of the landfill as well as for tie-in of the cap to the
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base. There is a potential need for a retaining vail around part
of the landfill.
Venting of the landfill will be accomplished through a
passive gas collection system installed with the cap. This
system would involve installations of highly permeable (relative
to surrounding soil) veils that vould provide paths for gas to
flow to points of controlled release. The installation of these
wells vould require specialized drilling techniques to prevent
methane explosions. These types of precautions are routinely
performed. The design of the gas collection system vould require
a test veil to determine the final system parameters (veil size
and numbers of wells). Other limited data should also be
collected during design, such as gas generation rate, moisture
contents, and composition to assist in system design. This
information vould also be collected during a long-term monitoring
program during operation, and the system vould be modified
accordingly.
Capping implementability vas discussed for Alternative 2. A
secondary leachate collection/treatment system vhich is a
reliable and established technique for gravity collection, would
also be installed. Design and installation of collection
trenches are standard techniques and could be readily
accomplished. Potential problems with installation include
slopes around landfill, installation in rock-outcropping and
standard trench requirements (shoring). Contractors are
available to install the collection and treatment system, vho
vould also provide necessary equipment and skilled workers.
Approval from regulatory agencies vould be obtained before
construction of any system.
With regard to permits, no additional permits for the cap
are anticipated to be required to implement any of the
alternatives.
Implementation of Alternative 4 needs several
considerations. Implementation of a cap was discussed in
Alternative 2. For design and implementation of a
collection/treatment system for landfill gas emissions, modeling
and field pilot studies vould be necessary during the remedial
design.
A passive collection and treatment system for landfill gas
emissions for this remedial action is estimated based on several
assumptions. The concentration of VOCs in the landfill gas vas
estimated using air emissions data from the risk assessment
section of the RI report. The gas-generation rate vas estimated
using factors contained in the solid Waste Handbook (Robinson
1986). The volume and veight of the landfill contents were
estimated using approximate area and depth calculations.
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Data such as gas generation rate, composition, and moisture
content would be obtained during the RD phase of the project as
discussed under Alternative 2. Several contractors are available
to install the collection and treatment system for landfill gas
emissions. Equipment would include carbon adsorption columns,
flaring units, and possibly silica gel columns. These could be
obtained readily from vendors. All required permits for
installation and air emissions would be obtained from respective
authorities.
Implementation of alternative 5 involves the techniques and
factors discussed in alternatives 3 and 4. Containment technology
such as capping is routinely performed when subsurface
contamination at a site precludes excavation and removal of
wastes because of potential hazards and/or unrealistic costs, it
is a reliable and established technique at the landfill sites;
The main disadvantages of capping are uncertain design life and
the need for long-term maintenance.
Several contractors are available to construct the landfill
cap and gas treatment system, who would also provide heavy
equipment and skilled workers. Necessary permits and approval
would be obtained from regulatory agencies before actual
construction begins. For collection and treatment of landfill
gas emissions to the atmosphere, air permits may be required.
Other additional Remedial Actions could be undertaken after
installation of the cap, if determined appropriate and essential.
Long-term monitoring and maintenance plans would also be
designed and implemented. The design information for the various
media as discussed under alternatives 2, 3, and 4 will need to be
collected for final determination of overall implementability and
construction.
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Cost
Estimated Costs for the various alternatives are presented in the
table below:
Estimated Remedial Action Costs
(in Dollars)
Alternative Capital O & M Present Worth
1. No Action $1,000. $197,996 $3,177,500
2. Cap,Vent Gas Collection $6,162,497 $277,011 $9,614,665
3. Cap,Vent Gas Collection $6,502,997 $312,471 $10,397,070
Leachate Collection & Treatment
4. Cap, Gas Collection & $6,232,497 $310,011 $10,095,920
Treatment
5. Cap,Vent Gas Collection $6,572,997 $345,471 $10,878,330.
& Treatment,Leachate Collection
& Treatment
Capital, operation and maintenance (O&M), and present-worth
costs as applicable for the four institutional response
activities for the no-action alternative are contained in the
above Table. These activities include:
o Groundwater monitoring;
o Ambient air monitoring;
o Signs; and
o Deed restrictions (1-A Limited Action).
Total capital cost for Alternative 1 is $1,000. Annual O&M
cost for this alternative is $197,996. Thirty-year present-worth
costs for this no-action alternative is $3,044,700. Cost for
deed restrictions (Alternative 1-A) is estimated as a one time
$500 item.
The cost for alternative 2 includes both the cost for the
no-action alternative, capping, and gas collection. The Table
above gives the capital, O&M, and present-worth costs for the
four activities contained in the No-Action Alternative and those
for capping and gas collection. The cost for a retention wall
was also developed. If necessary, the wall would be added to all
options involving capping. As all alternatives except the
no-action alternative include capping, the cost of this potential
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retention wall should not affect the overall cost comparison of
alternatives. :
Total capital cost for Alternative 2, as listed above, is
$6,162,497. Annual O&M cost for this alternative is $277,011.
Thirty-year present-worth costs for this alternative is
$10,420,850.
For Alternative 3, the cost for a passive leachate
collection and treatment system is added to the cost of
Alternative 2. Total capital cost for Alternative 3 is
$6,502,997. Annual O&M cost for this alternative is $312,471.
The 30-year present-worth costs for this alternative is
$11,306,460.
Cost for Alternative 4 is obtained by adding the cost for
treatment of landfill gas emissions to the cost of Alternative 2.
There is no present risk basis for imposing the cost for vented
gas treatment. However, after the cap is in place the vent gases
will be continued to be monitored. This cost may be justified in
the future if the risk measured warrants further treatment.
Total capital cost for Alternative 4 is $6,232,497. Annual O&M
cost for this alternative is $310,011. Thirty-year present-worth
cost for this alternative is $10,998,140.
The cost for Alternative 5 is developed by adding the cost
for leachate collection/treatment to that of Alternative 4. This
alternative is the most costly one as it includes more treatment
schemes than any other alternative.
Total capital cost for Alternative 5 is $6,572,997. Annual
O&M cost for this alternative is $345,471. Thirty-year present-
worth cost for this alternative is $11,883,750.
Based on the above cost comparison, the present worth cost
of alternatives 2 through 5 are all within 10% of each other.
Based on the considerations discussed under the other criteria,
EPA concludes that the landfill cap, vent gas collection system,
and leachate collection and treatment system identified in
Alternative 3 is cost effective and reasonable for the work under
consideration. The additional costs associated with gas
treatment as contemplated with alternatives 4 and 5 are not
justifiable based on the Air ARARs.
State Acceptance
The FADER has visited the site on a number of occasions and
has observed the continuing deterioration of the existing cap.
Since neither the no action or the limited action alternatives
address this continuing source of local contamination, the
Commonwealth would not accept these alternatives.
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The Commonwealth feels that the issue of leachate, as it
impacts the area groundvater needs to be addressed. Alternative
2 does not involve any action, other than capping the landfill
which will address that groundvater contamination. As such, the
Commonwealth will not concur with this selection.
Alternative 4 will comply with the ARARs for the landfill
cap, however, it does not address the issues associated with
groundwater protection which are more fully addressed by the
proposed leachate collection system discussed in Alternative 3
above. The Commonwealth will not concur in this selection.
Alternatives 3 & 5 both address the issues of the
deteriorated cap and the treatment of the leachate flows.
Alternative 5 also includes treatment for the vented landfill
gases. In terms of reduction of risk to the environment both
alternatives 3 & 5 would be acceptable to the Commonwealth.
C.Q]flfflu.nitv Acceptance
Community Acceptance is assessed in the attached
Responsiveness Summary. In general, the resident community
continues to be concerned over the continued, and increasing
recreational use of this abandoned property and would be opposed
to the no action and limited action alternatives. The community
also agrees that the present cap is not effective and is
concerned about the continued emergence of new leachate streams
on the landfill. At the time of the public meeting the public
agreed that something needed to be done to address the leachate
flows from the landfill. This action is not addressed by
alternative 2. Therefore the community would not accept this
alternative.
Furthermore, there is general community agreement that
Alternative 3 is both practical and will address their concerns
over the risks posed by the landfill as long as a diligent
monitoring program is continued.
With regard to Alternative 4, at the public meeting there
was strong support for vent gas treatment, but not without the
leachate collection system. As a stand-alone alternative this
alternative would not be acceptable to the community. The
concern was not so much for the actual risk for the air emissions
but rather for elimination of the offensive odor.
Alternative 5 was the preferred alternative by the
community, as it provides the most treatment of any of the
alternatives.
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9. Selected Remftfly Afld Performance Standard^
\
Based on the comparison of the nine evaluation factors for
each of the five alternatives, Alternative 3 is the selected
alternative. The components of this selected alternative are as
follows:
- source containment by capping;
- passive gas collection;
- leachate collection;
- leachate treatment and discharge; and
- operation and maintenance of the above systems
Capping the landfill with a cap that meets the PA Municipal
Landfill Regulations, 25 PA Code $273.322 (a) and (b) and the PA
Hazardous Haste Regulations, 25 PA Code Chapter 264, Subchapter G
would reduce the amount of leachate generated by precipitation
infiltrating through the existing landfill cap and through the
refuse. A leachate collection system around the southeast,
south, and southwest sides would collect leachate that migrates
from the toe of the landfill. The leachate will be treated by
UV/ozone oxidation and discharged to Briar Run.
In conjunction with the two previous interim actions, i.e.,
point-of-use carbon treatment for the two affected residential
wells southwest of the landfill, which was implemented in March
1990; and restricting access to the immediate landfill area by
fencing, which is pending implementation, the actions recommended
in this report will reduce human and environmental receptor
exposure to acceptable levels.
If implementation of the selected remedy demonstrates, in
corroboration with physical and chemical evidence, that it will
not be possible to meet the remediation goals for this action,
and it is thus technically impracticable (either technically
infeasible or unreliable) to achieve and maintain the capping,
venting, and leachate treatment system goals at this Site, the
EPA, in consultation with the Commonwealth of Pennsylvania, would
intend to amend this ROD or issue an Explanation of Significant
Differences to inform the public of alternative access controls.
The five-year review required by Section 121 of CERCLA is
applicable to the selected remedy. This review will be conducted
in conjunction with the other remedial actions developed and
specified for this site.
Performance standards
(1) Removal of the Existing Landfill Cover
The existing landfill cover, including the perforated liner, will
be removed from the surface of the landfill. Soils removed from
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this cover may be tested and, if shown to be acceptable to EPA,
may be reused in the recapping of the landfill. Removed
substances from the existing cover, which cannot be. reused, will
be disposed of in a manner approved by EPA.
(2) Installation of Landfill Cap
A landfill cap will be constructed on the top and the sides of
the landfill. This cap will be constructed to meet the
performance specifications applicable under 25 PA Code 273.322(a)
and (b) and the relevant and appropriate specifications as
contained in the PA Hazardous Waste Regulations, 25 PA Code
Chapter 264, Subchapter G Sections:
264.111 Closure Performance
264.117 Postclosure care and use of property
264.118 Postclosure Plan, Amendment of Plan, specifically
subsections a, a(l),a(2)(i) and (ii), a(3) and;
Chapter 264, Subchapter N sections:
264.301 Design requirement general: specifically subsections
264.301(5), (6), and 264.301(12))-(15)
264.303 Leachate Management
264.310 Closure, Postclosure Care
The cap shall be constructed as follows (subject to EPA approval
at the design phase of this remedy):
a) a top soil layer two feet thick, or more, to provide freeze
thaw protection;
b) a soil drainage layer 12 inches thick with a hydraulic
conductivity of 10"2 cm/sec or greater, or a geosynthetic
drainage layer; and
c) a two-component low-permeability layer comprised of a 30-mil
(minimum thickness) geomembrane and two feet of clay with a
hydraulic conductivity of not more than 10~7 cm/sec.
(3) Revegetation of the Landfill Cap
Vegetation shall be established on the new soil cover (i.e. the
entire extent of the cap). Revegetation shall provide for an
effective and permanent vegetative cover of the same seasonal
variety native to the site and capable of self regeneration and
plant succession. Revegetation shall provide a quick
germinating, fast-growing vegetative cover capable of stabilizing
the soil surface from erosion.
(4) Installation of Landfill Gas Venting and Monitoring Systems
A landfill gas venting system shall be installed on the surface
of the new landfill cap to minimize the potential for landfill
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gas migration off of the site. To prevent future complications
regarding Active/Passive gas ventilation, the landfill cap will
be constructed to comply with the Active gas treatment system.
The system, however, need only be operated and maintained as a
passive system as long as human health and the environment safe
levels are maintained. The number of landfill gas vents shall be
determined during the remedial design. The landfill gas venting
system shall meet the requirements for new air emission sources
as specified in 25 PA Code SS 123 and 127.1 (not exempted by
S127.14).
Periodic ambient air monitoring shall be conducted to
evaluate the landfill gas emissions. If the monitoring shows
that landfill gas emissions would cause increased health risks
when vented, a gas treatment system shall be installed to address
this problem. At this time, the health effects estimated from
current data do not warrant gas treatment.
To monitor the potential occurrence of landfill gas
migration off of the landfill perimeter, gas monitoring stations
shall be installed at the same time the landfill cap is
installed. The number and placement of these monitoring stations
will be developed during the design phase of this remedial
action. The number and locations of these stations will be
approved by EPA. These gas monitoring stations shall be
monitored quarterly for a period of 30 years or until EPA
determines that no gas monitoring is necessary.
(5) Installation of the Leachate Trench Collection System
A leachate collection system, to collect leachate in the
surficial aquifer, shall be installed around the landfill cap.
This collection system will extend around the circumference of
the landfill starting at the existing leachate collection system
and extending in a south and then westerly direction encompassing
approximately 240* of the landfill cap boundary. The specific
distance from the landfill cap of this collection system will be
determined by EPA during the design phase of this project.
(6) Installation of the "Collected Leachate" Treatment System
A leachate collection and treatment system will be
constructed in the vicinity of the existing treatment system
building. The collection and treatment system will be
constructed and installed to handle the leachate from the
leachate collection trench. The capacity of the collection
system will be determined by EPA during the design phase of this
project. The treatment system- shall operate to insure compliance
with both air emissions and compliance with the NPDES as
specified in 40 CFR Part 122 subpart C and PA Clean Streams Law,
as specified in 25 PA code Chapters 92, 93, 94, and 96.
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specified in 40 CFR Part 122 subpart C and PA Clean Streams Lav,
as specified in 25 PA Code Chapters 92, 93, 94, and 96.
(7) Operation and Maintenance
Operation and maintenance (O & M) of the remedy shall be
conducted for thirty years. This will include O & M of the
landfill cap, the landfill gas venting system, and the leachate
collection and treatment systems. Monitoring of the groundwater,
will be conducted quarterly for a period of two years with the
sample locations determined by EPA and PADER. The results of
this monitoring will be used to model the contaminants fate in
the groundwater for the purposes of operable unit 4.
(8) Remedy Review
The five-year review required by Section 121 of CERCLA is
applicable to the selected remedy. This review will be conducted
in conjunction with the other remedial actions developed and
specified for this site.
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10. statutory Determinations
Section 121 of CERCLA requires that the selected remedy:
be protective of human health and the environment;
comply with ARARs;
be cost effective;
utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the
maximum extent practicable; and
address whether the preference for treatment as a principal
element is satisfied.
A description of how the selected remedy satisfies each of
the above statutory requirements is provided below.
In summary, the selected remedy is protective of human
health and the environment as required by Section 121 of CERCLA.
Potential risks from exposure to contaminated surface soil and
leachate are prevented by the installation of the landfill cap/
the vent gas system, and the leachate collection and treatment
system.
The selected remedy is the most cost-effective action
approach available to protect human health and the environment.
The selected remedy uses capping and treatment to eliminate the
potential for direct (ingestion,inhalation and immediate contact)
human exposure to contaminated surface soil and landfill
leachate.
Protection of Human Health and the Enviro,Tnn?'nt T
The selected remedy (Alternative 3) will be protective of
human health and the environment by reducing the principal
threats posed at the Site which are addressed by this operable
unit.
Landfill caps have been demonstrated as being very effective
in protecting people from the risks associated with hazardous
substances found present in landfills such as this one. Vent Gas
systems have also been shown to be need to allow the landfill to
maximize its- effectiveness.
The leachate collection system is protective of human health
in two ways: it reduces the immediate contact threat by readily
collecting the leachate streams and not allowing them to collect
on the landfill surface; and it is also protective in that it
physically and chemically reduces the hazardous substances into
inert substances and thereby reduces the threat to both humans
and environment.
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No unacceptable short term risks or cross media impacts will
be caused by implementation of this selected remedy. .
Compliance with Applicable or Relevant and Appropriate
Requirements.
All applicable or relevant and appropriate requirements
(ARARs) pertaining to the selected remedy and this operable unit
will be attained.
As stated above, this is considered a final remedy for all
media except groundwater. As such, it will comply with all
federal and Commonwealth ARARs with the exception of the
Commonwealth's "Clean-up to Background" groundwater ARAR.
Groundwater and the related PADER groundwater ARARs will be
addressed by operable unit 4.
The selected remedy will comply with the following ARARs:
o The landfill cap will comply with the performance
standards as contained in the Municipal Landfill Regulations
as contained in 25 PA Code 273.322 (a) and (b) and PA
Hazardous Waste Regulations as contained in 25 PA Code
Chapter 264, Subchapter G Sections:
264.111 Closure Performance
264.117 Postclosure care and use of property
264.118 Postclosure Plan, Amendment of Plan, specifically
subsections a, a(l),a(2)(i) and (ii), a(3) and;
Chapter 264, Subchapter N sections:
264.301 Design requirement general: specifically subsections
264.301(5), (6), and 264.301(12))-(15)
264.303 Leachate Management
264.310 Closure, Postclosure Care
o Air Emissions from the landfill will comply with 40 CFR
Section 264, subpart AA for VOCs and the National Emissions
Standards for Hazardous Air Pollutants (NESHAPs), as
contained in 40 CFR Part 61, as well as the National Ambient
Air Quality Standards (NAAQS), as specified in 40 CFR Part
50, and the PA Air Pollution Control Act and Air Discharge
Regulations, as specified in 25 PA Code Sections 123 and
127.1 (not exempted by Section 127.14).
o Discharges of the treated leachate will comply with the
NPDES, as specified in 40 CFR Part 122 subpart C and the PA
Clean Streams Law, as specified in 25 PA Code Chapters 92,
93, 94 and 96.
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EPA and FADER have agreed to model the groundvater
contamination levels after this alternative is Implemented for a
minimum period of two years. Therefore, Groundvater Protection,
as specified in the PA Hazardous Waste Management Regulations, as
contained in 25 PA Code SS 264.97(1) (j) and 264.100 (a) (9), are
not ARARs for this operable unit. Sampling will be conducted on
a quarterly basis. A determination will be made at that time as
to the type of further treatment to be considered in OU 4 for
this site.
Another issue which is a "to be considered" is that care
will be taken in obtaining the soils for the landfill cap so as
not to disturb any local ecosystems or habitats.
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Cost-Effectiveness. .
The selected remedy affords overall protectivenesa
proportionate to its costs. Landfill caps have shown, if only
through their frequent application, that they are an economical
and effective means to close landfill operations. Leachate
collection systems, as specified in this document, are reasonably
cost effective and provide an additional, necessary treatment
system to the landfill remediation.
utilization of Permanent Solutions and Alternative Treatment for
resource recovery) Technologies to the Maximum Extent Practicable
(MEPl.
The selected remedy utilizes a permanent solution to the
maximum extent practicable. EPA has used treatment for past
remedies at this site and intends to implement further treatment
technologies (again, as practicable and as needed) for future
actions at this site.
The remedy selected provides the best balance of trade-offs
among the alternatives evaluated with respect to the evaluation
criteria. It is protective of the near-by community in that the
risks of contact with the leachate streams will be eliminated.
Furthermore, impacts on the groundvater will be effectively
reduced, perhaps eliminated, by the implementation of the
leachate collection and treatment system. Although this operable
unit addresses groundvater to a limited extent, groundwater will
be finally addressed by operable unit 4.. The other alternatives
(not selected) do not meet all of the remedial objectives for the
Site. Cost and protectiveness were the reasons for not selecting
alternatives 4 and 5. It was felt that the incremental increase
in protectiveness was not warranted by the increased cost,
however it is also noted that, if the air emissions change with
the imposition of the new landfill cap, this extra (gas)
treatment may be necessary based on monitoring.
Both the State and the community played a significant role
in the development. of this decision. Treatment technologies and
continued monitoring will be implemented based on their concerns.
Preference for Treatment as a Principal Element.
~~The selected remedy satisfies the preference for treatment
in Chat it employs treatment to address the principal threat
posed by conditions at the site. The landfill cap provides
passive treatment in that it eliminates weathering elements from
coming into contact with the hazardous materials in the landfill.
This action will further reduce the amount of hazardous
substances (leachate) being released into the nearby environment.
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The leachate collection system and treatment system provides
direct, active treatment for the leachate will be.collected,
treated on-site and discharged to an acceptable receiving stream.
The principal treats of ingestion of leachate and direct contact
exposure, especially to children trespassing on the site, will be
eliminated. In addition the toxic burden to the groundvater will
be significantly reduced.
Based on the additional monitoring to be performed at the
Site, it may be shown that groundvater contamination may persist
above acceptable levels. If this is shown to be evident then the
preference for treatment as a principal element will be addressed
by EPA in the final decision document (OU 4) for the site.
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11. Documentation of Significant Changes
The proposed plan cited RCRA as the applicable. Federal lav
governing the placement of the landfill cap. The proposed plan
also cited, as an ARAR for the landfill cap, the PA Municipal
Landfill closure Regulations as contained in 25 PA Code, Section
273.322 (a) and (b). PADER has subsequently commented that the
25 PA Code, Chapter 264, Subchapter G, Hazardous Waste
Regulations are relevant and appropriate for the landfill cap.
These Pennsylvania Hazardous Waste Regulations are relevant and
appropriate because the landfill accepted RCRA characteristic
waste and constituents of listed hazardous wastes as contained in
40 CFR Part 261, Subparts C and D, and 25 PA Code Part 261,
Subparts C and D. The ROD has incorporated these comments and
reflects the PADER Hazardous Waste Regulations as an ARAR.
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Strasburg Landfill - Operable Unit 3
Responsiveness Summary
There were basically three groups of Comments received in
response to this Proposed Plan:
o comments raised during the public meeting held on January 8,
1992
o written responses from nearby residents
o written responses from persons identified as potentially
responsible parties
Comments Raised At The Public Meeting:
Comment: Alternative 5 should be selected instead of Alternative
3 since it only costs an additional $70,000 and would further
reduce risks in the neighborhood.
Response: Measurements of air contaminants in and around the
landfill do not indicate a need for the installation of vented
gas treatment. Therefore EPA would not have sufficient basis to
obligate funds to address this concern. EPA understands that
conditions may change, especially with the installation of an
effective landfill cap with an operable venting system. Among the
conditions which may change is the type of contaminants measured
in the air at the Site. Installation of a treatment system at the
time of the cap and leachate collection systems may result in a
vent gas treatment system which would be inappropriate for the
gases measured under the new cap. Therefore, as stated above, EPA
will continue to monitor the vent gases from the landfill. In the
event that the contaminant concentration levels are measured at
actionable risk levels, EPA will evaluate taking action to
install an appropriate treatment system.
Comment: Why doesn't EPA look to treat, not just vent the
landfill gases as part of this Operable Unit?
Response: There are two reasons why EPA has chosen not to include
treatment of the vented gases at this time. First, the levels and
types of substances measured at the vent pipes, and in other gas
studies on this landfill, indicate that no treatment is
necessary. The air contaminant levels are in compliance with
existing regulatory levels. Secondly, conditions, such as type
and/or size of landfill caps, may alter the air contaminants
measured at the Site. So that, if EPA designed and installed a
treatment system now, based on data from the ineffective landfill
cap, we may be looking to treat the wrong substances.
EPA's selected remedy includes monitoring the air and vent
gases after the new cap and leachate collection system is in
place and will evaluate the new data to determine if further
action is required.
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Comment: Has EPA considered interdicting surficial aquifer flows
before they come into contact with discharges from the landfill.
Response: EPA has looked into the possibility of taking measures
to intercept groundwater prior to the landfill area, however,
because of the hydrogeology of the area this idea was discounted
as potentially causing more problems than it may solve.
Comment: Has EPA investigated the landfill manifests to determine
what substances were taken to the landfill?
Response: EPA has not been able to obtain the complete manifest
log for the landfill. EPA has conducted a thorough investigation
of existing sources of information, such as shipment logs from
companies and municipalities, to determine what had been sent to
this site.
Comment: If we go with Alternative 3 there will be no monitoring
or sampling of the gaseous emissions from the landfill. A
landfill cell could rupture and generate additional gaseous
compounds into the atmosphere.
Response: While not clearly spelled out-in the Proposed Plan,
monitoring of the Landfill gases is considered part of this
alternative. The air monitoring is specified in the performance
standards section of this ROD. In addition, since this comment
has been raised, EPA will specify the air monitoring program to
be incorporated as part of this remedial-action, in the remedial
design phase.
Comment: The cost ($70,000) to add a gas filtration system is
small in comparison to the other costs of Alternative 3.
Therefore EPA should look to add this component on at this time.
Response: While it is true that the incremental costs are small
for the addition of an air filtration system, the risks measured
in the air monitoring do not warrant this additional expenditure.
Comment: How close is the nearest public water supply?
Response: According to the information contained in this file,
the nearest Water Supply is the B & E Water Company. They have a
well field approximately 1.5 miles due east of the landfill.
Comment: Will the proposed Remedial Alternative create any
contamination problems in the future?
Response: The proposed Alternative incorporates technologies
which have been shown to be implementable. Based on the past
knowledge EPA has regarding these systems and the information we
have reviewed regarding this site, we feel that there will not be
any long term environmental problems in implementing this remedy.
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Care will be taken during the actual remedial action phase of the
cap reconstruction to minimize or eliminate any short term
contamination problems.
Comment: What will be done with the old cap soil & debris as part
of this remediation?
Response: Specifics on actual disposal actions to be included as
part of this alternative will be developed as part of the
remedial design. In reviewing all of materials used as part of
the existing cap it may be determined that part or parts of this
cap may be able to re-incorporated into the new cap.
Comment: What is the plan for monitoring the home wells in and
around the Site?
Response: EPA is working in cooperation with the Pennsylvania DER
to develop a sampling matrix which includes the nearby home
wells. According to the most recent information, the next round
of home well samples is scheduled for March 1992 and will be
conducted by the FADER.
Comment: West Bradford Township requested that they be kept
updated as to the progress of the work on a somewhat periodic
basis (approximately monthly).
Response: EPA recognizes the on-going concern of West Bradford
Township regarding this site. As design and construction actions
begin, EPA will make a strong effort to keep West Bradford and
Newlin Townships apprised of site actions.
Comment: What are the sampling methodologies to be used in
sampling the home wells for hazardous constituents?
Response: The sampling will use two separate methodologies to
qualify and quantify the sampling results. These are identified
as EPA Method 524 and EPA Method 502.2.
Comment: With regard to the surface discharge of the treated
leachate, under what conditions would the discharge be moved from
Briar Run to Brandywine Creek?
Response: Discharge of the treated leachate will have to be in
compliance with PA Clean Streams Law and Federal Discharge
limitations. Because of the limitations of treatment technology
and the relatively small flow in Briar Run, it may be
technologically impossible to treat the waste stream down to
levels permissible in Briar Run, whereas the Brandywine has a
much larger flow and therefore a higher assimilative capacity.
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Comments Were there any alternatives considered other than
stream discharge for the treated leachate, such as land
application?
Response: EPA did review some other alternatives, including land
application, for disposal of the treated leachate flow. Land
disposal was discarded as a potential alternative because the
weather conditions in Chester County would not allow for this
technology to be implemented 12 months in a year. Cost and
operation and maintenance concerns were also factors in
discarding this as a possible treatment alternative.
Comment: Will the entire 22 acre landfill be covered with the
protective cap?
Response: The exact extent of the cap will be determined at the
design phase of the selected alternative. At present, it is
expected that the entire 22 acre landfill will be covered with
the new cap.
Written comments From Nearby Residents:
There were two written responses received from nearby residents,
both were in favor of the proposed cap and leachate system, one
resident requested that EPA select Alternative 5 instead of
Alternative 3, as this Alternative would require the additional
installation of a treatment system for the vented landfill gas.
Response: This is the same issue that was raised during the
public meeting - see Response to first comment above.
•!*-.
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written Comments From Potentially Responsible Parties:
The first set of written comments received were from the Clean
Harbors Company, the company that currently maintains and
operates the leachate collection system. Their comments (with
responses) are as follows:
comment: The risks associated with the air emissions from the
landfill are in the range of 10~6 and therefore collection and
treatment are not warranted and therefore only Alternative 1 (no
action) is warranted.
Response: EPA concurs that the risks presently measured
(associated) with regard to air contaminants do not warrant
treatment of the landfill gases at this time, however, as also
determined during this investigation, the landfill cap is
extensively compromised in numerous locations and landfill
contaminants appear to exchange freely into the atmosphere and
the groundwater. EPA concurs with the recommendation that the
landfill gases be monitored on a routine basis. EPA disagrees
that Alternative 1 is the only action warranted since the air
pathway is only one of several exposure pathways under which
nearby residents are exposed. Alternative 3 already provides for
monitoring of landfill gases with the proviso-that further action
(i.e. treatment) will be implemented if the contaminant levels or
constituent changes (to actionable levels) with respect to time
or remediation.
comment: The security fence and warning signs as specified in the
OU2 ROD will deter residents from traversing the Site.
Response: EPA concurs that the security fence and warning signs
will be effective in deterring most residents and recreational
visitors from contact with most landfill seeps. The fence will
not serve as a barrier to keep seep material on the landfill,
and, furthermore, residents have already inquired of EPA as to
when the fence will be erected as they have indicated that they
recreate right outside of the proposed fence area.
Comment: The risks associated with residential use of groundwater
is stated as too high and does not take into account the fact
that the residences with the highest levels of measured
contaminants are now on filter systems..
Response: EPA and PADER have continued to monitor the residential
drinking water in the area around this landfill. It is true, as
asserted, that the measured levels of contaminants in groundwater
have gone down in recent sampling events. There are three reasons
why EPA feels that the risk levels as stated are reasonable for
this action:
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1) Rainfall in the area has been below average for the past few
years, this may cause the actual concentration levels to
artificially lower.
2) Since the time of the initial residential well sampling at
least one additional residence has shown evidence that the plume
is spreading. This home is not on a filter system.
3) There have been continued problems with the residential filter.
systems which have remained unresolved for extended periods of
time.
Comments Removal and reconstruction of the landfill cap may
release large quantities of landfill gases and thereby increase
the inhalation risk to site workers and nearby residents.
Replacement of the cap is not warranted given the fact that 98%
of the existing cap is intact.
Response: EPA is very concerned about issues relating to exposure
risks associated with landfill cap reconstruction. EPA has
already shown that landfill cap reconstruction is implementable
and the issue of site safety will be addressed during the design
phase of this operable unit. EPA disagrees with the statement
that because 98% of the existing cap is intact, replacement is
not warranted; EPA's investigations have observed that the cap
has been compromised in numerous locations to the point that
replacement, of the cap is warranted. ~
Comment: The proposed secondary leachate collection and treatment
system assumes the leachate is entirely in the vadose zone and
the proposed design will be impracticable.
Response: The commenter raises some of the same technical issues
that EPA sees as needing to be addressed during the design phase
of this remedial action. EPA agrees that the geological
conditions will need to be further assessed and studied during
the design phase of this project. EPA disagrees that this system
is impractical and feels that the system is practical and will
show to be an effective treatment system for the surficial
leachate discharge to groundwater.
A large set of comments regarding this proposed plan were
submitted by the Maxus Corporation on behalf of the Occidental
Chemical Corporation (OCC) (a potentially responsible party). The
comments regarding this proposal are addressed below. It should
be noted that interspersed with these comments are other
assertions by the Commenter as to EPA's official positions,
policies, and statements. EPA does not accept any of these
assertions as true. Furthermore, this commenter goes to
considerable effort to assert non-liability on the part of OCC at
this site. The purpose of this responsiveness summary is to
address comments raised as they pertain to the proposed
remediation. Issues regarding liability, and the administrative
protocols associated with past operations at the landfill not
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associated with this remedy are not discussed in this response
summary.
Comments submitted by MAXUS by letter dated February 5, 1992:
Cover Letter:
1. Comment: Strasburg Landfill functioned as a normal sanitary
landfill for municipal household wastes and sewage sludge.
Response: It is clear in all of the records relating to the
operation of the Strasburg Landfill that it was permitted
and operated to accept both industrial and municipal wastes.
This permit was revoked by FADER when it was determined that
the industrial wastes were not being handled correctly.
There is also information that the landfill continued to
accept industrial wastes after this approval was rescinded.
Therefore, based on the information that EPA has received to
date, it would be incorrect to categorize this landfill as a
"normal" municipal type landfill.
2. Comment: EPA's selection of Alternative 3 is based on a
flawed risk assessment which grossly overstates possible
human risks. Strasburg should be removed from the National
Priorities List and closed as a non-hazardous sanitary
landfill.
Response: As stated in 1. above, and as has been established
through monitoring, documented in the site investigation
(SI) and the remedial investigation (RI), the Strasburg
Landfill is not a non-hazardous sanitary landfill. The risk
assessment developed for this site is not "flawed" but
rather based on established data. The actions taken by EPA
through the Records of Decisions (RODs) for operable units 1
and 2 are, or will be, effective in reducing immediate risk
to the surrounding community (long term and some immediate
risk still remain). EPA feels that, if these actions had not
been decided previously, the data would call for them to
have been specified as part of this action.
The data collected during the RI only verifies the data
collected during the SI which was used as a basis to place
this site on the NPL. Nothing uncovered to date at this Site
would warrant its removal from the NPL.
Furthermore, neither the remedial investigation nor PADER's
quarterly.monitoring of residential wells provides any
, evidence to support the assertion that the site is
recovering on its own. Given the highly fractured bedrock
geology in the area, it is very difficult to identify
contaminant sources with certainty. However, identification
of fault traces leading from the landfill area toward the
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Wheatland Drive area suggests that the landfill is a
possible source of the contamination.
3. Comment: FADER failed to properly oversee and manage
operations and closure of this Site and this is a non-
hazardous landfill.
Response: This comment does not address any of the actions
proposed in this plan but rather goes to allegations of
liability. As stated previously, EPA does not consider this
Site as a non-hazardous landfill.
4. Comment: There is no basis for the inclusion of .UV/ozone
technology. Expensive pretreatment would be required for
this type of treatment. UV/ozone technology will enormously
increase the amount of waste generated during the treatment
process and will transfer significant contaminants to the
air through volatilization.
Responses The feasibility study report recommended pilot
studies to develop the necessary data to evaluate if
UV/ozone treatment is a practical or reliable treatment
method for Strasburg Landfill leachate. The recommended
pilot studies will also provide information to develop site
specific costs, including operational, maintenance and
disposal costs associated with the UV/ozone treatment system
for Strasburg Landfill leachate.
o Scaling was an anticipated problem as noted in the FS
text. According to the vendor, scale can be cleaned by
routine maintenance and should not require a signifi-
cant amount of time (See FS page 4-34).
o Pretreatment efforts were not described in the FS as
they will be determined as a result o the treatability
tests. However,. EPA does agree that if extensive
pretreatment is required costs could be prohibitive.
The Ultrox SITE report indicates a treatment (i.e. O &
M costs) cost range of $.25 to $17 per 1000 gallons.
At the 10 gpm rate O & M costs (exclusive of testing;
apparently Maxus only considered the operation costs
and not the maintenance and insurance costs) were
estimated at $1.2 per 1000 gallons for 200 ppb influent
or $1.4 per 1000 gallons for 400 ppb influent. These
costs would appear consistent with those presented in
the Feasibility Study. As noted in Maxus' evaluation,
if extensive pretreatment residues are generated, this
could significantly increase the cost. At this point
in time, it is not clear whether air stripping or
UV/ozone will generate more residue. To assist in this
evaluation, EPA will review the operational data on the
existing air stripping system. Once the treatability
8
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test is completed, pretreatment needs of both systems
can be compared and a more detailed benefit analysis
can be performed.
o Also note that in the FS both UV/ozone and air
stripping were costed without significant pretreatment
for comparison, since reliable pretreatment information
was unavailable and will be generated during design.
The costs presented in the FS for O & M may be
underestimated if extensive pretreatment is required.
5. Comment: The RI/FS and supporting documents contain
numerous misstatements and flaws which are addressed in
Attachment I.
Response: EPA denies this allegation and each of the
specific assertions are discussed below (as raised) in
responses to Attachment I comments.
6. Comment: EPA has essentially concealed the significance of
the 1,000,000+ cubic yards of municipal waste disposed
of at the site. EPA's contractor is confused over the
difference between polyvinyl chloride and vinyl
chloride. Furthermore EPA disregards the fact that
vinyl chloride is typically detected in municipal
solid waste vent gases and product. Under the right
conditions, Vinyl Chloride monomer may be formed in the
landfill itself.
Response: At no time has EPA attempted to hide the fact that
this facility was also used for the disposal of municipal
wastes, nor the estimated size of the landfill. Furthermore,
a number of municipalities have admitted that they sent both
domestic trash and sewage sludges to this landfill while it
was in operation.
The issues of: who brought vinyl chloride monomer to the
site; how PVC degrades in a landfill; and how various
chemicals which may be present in a landfill may, under the
right conditions produce additional vinyl chloride (VC)
monomer do not impact the selection of remedy at this Site
and go instead to the issue of liability. It is not the
purpose of a proposed plan to address issues of liability.
Rather, the issue is that VC monomer, along with a host of
other organic and inorganic hazardous substances, have been
determined to be present on the Site and to be migrating off
of the site; and, it is because of these determinations that
EPA seeks, through this decision document to take remedial
action to correct this contamination.
7. Comment: .The Commenter asserts that the RI is incorrect in
stating that OCC was prohibited from disposing of its PVC
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wastes at this landfill because it inconsistent with the
wastes described in its PAOER Module No. 1 Form.
Responses EPA fails to see the connection between this
comment and the selection of the proposed remedy. EPA has
not failed to consider the significance of the municipal
waste contributions in the selection of this remedy. The
documentation in EPA's file indicates that OCC has sent
large quantities of scrap poly vinyl chloride and hazardous
waste sludges containing vinyl chloride monomer, to the
landfill and that these scrap quantities contained vinyl
chloride monomer, a contaminant often measured as emanating
from the landfill. Additional documentation in EPA's file
indicate that PADER recommended to the Strasburg Landfill
that they discontinue accepting these wastes. The commenter
has misinterpreted that EPA asserts this comment was
contained in the McCaffery report.
8. Comment: Maxus requests that the proposed remedial action
plan be suspended pending notification of the PRPs
consistent with $113 (fc)(2)(D) of CERCLA.
Response: This request is denied in this action since it
does not address the proposed plan remedy. It is also
denied for the following reasons:
1) Maxus does not assert that they represent any other PRP
other than themselves or OCC and they did receive timely
notification of this action as evidenced by their response.
2) As stated in the subject ROD, notification of this
proposed plan was published in the local daily newspaper on
December 24, 1991 to satisfy the requirement of
S113(k)(2)(D) and, in addition;
3) A copy of the proposed plan was individually mailed to
each of the PRPs at the addresses contained in the EPA
Region III listings at the time of the issuance of the
proposed plan.
10
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ATTACHMENT I
GENERAL COMMENTS
1. Comment: EPA needs to correct the Administrative Record to
show that DSCC PVC wastes are not vinyl chloride or ethylene
dichloride wastes.
Response: This comment does not address the remedy proposed
in this plan but rather goes to the issue of liability.
However, since part of the risk analysis for this action is
based on the determined presence of vinyl chloride both in
the groundwater and in the soils, OSCC stated, in
correspondence to EPA that the waste PVC which they sent to
the Strasburg Landfill contained vinyl chloride monomer.
2, comment? Wheatland Drive groundwater contamination appears
to be from the residents. EPA should say that these
residents are not threatened by the landfill.
Response: This allegation is incorrect. The RI stated that
sampling conducted a few years ago showed low levels of TCE
in several home well samples from Wheatland Drive
residences. These results were not duplicated in the
subsequent sampling event. One possible cause of these
results may have been one of the residents putting a
degreaser into their septic system; however, EPA is aware
that these type chemicals move quickly in certain hydro-
geological structures and has not ruled out contamination
from the landfill as a source. EPA remains concerned that
the Wheatland Drive residents are threatened by the
landfill.
3. Comment: Why hasn't EPA investigated the possibility that
Zarzycki and other residents to the southwest contaminated
their own groundwater?
Response: There is no evidence to support the assertion
that local residences contaminated their own groundwater
through the use of individual septic systems.
4. Comment: Where residents have already contaminated their
groundwater, risks should only be considered as increased
risks.
Response: There is no evidence to support the assertion that
local residences contaminated their own groundwater through
the use of individual septic systems.
5. Comment: EPA should inform the public that Wheatland Drive
residents are protected from site groundwater, and that
these residents contaminated their own groundwater. EPA
11
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should retract the statement that no contaminants were found
in the Wheatland Drive wells. .
Response: Maxus misunderstood EPA's statement in the public
meeting. There were no appreciable levels of contaminants
found in the most recent round of domestic well sampling on
Wheatland Drive samples. TCE was found in Wheatland Drive
home well sampling conducted a few years ago; however, it
could not be determined or ruled out that the contamination .
was from the landfill. EPA does not agree that all of the
subsurface contamination from the landfill is screened by
Briar Run.
6. Comment: EPA should remove the Strasburg Landfill from the
National Priorities List.
Response: See response to Cover letter comment #1; in
addition, the risk levels currently measured in and around
this site remain high enough to warrant inclusion on the
NPL.
7. Comment: The vinyl chloride levels found at the Strasburg
Landfill are consistent with levels found at landfills
receiving only non-industrial wastes.
Response: EPA does not necessarily agree with this comment.
Whether this is true or not has no bearing on the
remedy selected for this operable unit.
8. Comment: Risk assessments should report the "reasonably"
calculated cancer risks, not just maximal estimates.
Response: The risk assessment was prepared according to EPA
guidelines. The risk assessment presents the estimated
excess cancer risks associated with the "reasonable maximum
exposure" that might occur to chemicals of potential concern
at the site. EPA's Risk Assessment Guidance for Superfund
Volume I HumarR Health Evaluation Manual (December 1989)
(HHEM) mandates the use of risk estimates based on the
reasonable maximum exposure case as the basis for regulatory
decisions. Exposure assumptions to be used in estimating
the reasonable maximum exposure are provided in other EPA
guidance including the Exposure Factors Handbook (July 1989)
and OSWER directive 9285.6-03 entitled "Human Health
Evaluation Manual, supplemental Guidance: Standard Default
Exposure Factors" (March 1991). These assumptions were used
in developing the exposure estimates for the risk
assessment. The HHEM does not recommend comparing site
risks to general population risks.
9. Comment: Risk assessments should use the most current and
accurate data not historical data.
12
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Responses Risk of exposure is cumulative and may have
occurred when concentration were higher. Although the data
shows a decreasing trend, there is no evidence to support
the assertion that concentrations will continue to decrease.
Due to the cell construction technique used at the landfill,
there may be a delay when contaminants are released.
Furthermore, EPA has demonstrated that a release to
groundwater has occurred and an exposure route exists. EPA
used the best available data for the risk assessment.
This comment is internally contradictory. On the one hand
it states that only the most current data should be used in
the risk assessment then it wants historical data to be used
to predict future contaminant concentration for use in the
RA.
The KKEM in Section 5.1 provides for combining results from
different investigations, provided the analytical methods
and data quality are comparable. The risk assessor
contacted the PADER laboratory that analyzed the samples for
the PADER residential well monitoring program for the
Strasburg Landfill area and was satisfied that the methods
used and the overall quality of this data were comparable to
groundwater data generated by the RI. The PADER data showed
that the groundwater contaminant concentrations fluctuate
considerably from quarter to quarter. In light of this
variability, the limited data available from the remedial
investigation (only one round of sampling from most wells)
did not appear to be sufficient to adequately characterize
the groundwater contamination in the area. Since the PADER
data provided a broader data base than the RI data and also
provided an historical record of the groundwater
contamination in the area, it was included in the risk
assessment. The PADER data does show that the greatest
groundwater contaminant concentrations in the residential
area southwest of the landfill occurred during the 1986 to
1988 time period. It also* shows that the level of
contamination is highly variable from quarter to quarter and
does not provide adequate information to confidently predict
the rate at which contaminant concentrations might decline
in the future. Risk estimates corresponding to both the
historical average and the 1990 average concentrations, a
period during which contaminant concentrations had declined
from their 1986-88 highs, were included in the risk
assessment. The possibility of further decreases in
groundwater contaminant concentrations and the possible
overestimation of the risks that could result were included
in discussions of the uncertainties associated with the risk
estimates.
13
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10. Comment: The following reasons justify a no cancer increase
risk determination from groundwater: •
lOa. Comment: Wheatland Drive residents are separated from the
landfill by Briar Run which is a groundwater discharge
point.
Response: EPA acknowledges that Briar Run is a groundwater
discharge for the local shallow groundwater system.
However, rock fractures in the deep groundwater system may
exist and provide a route for contamination to migrate
southeast toward the Wheatland Drive area. Many of the
Wheatland Drive wells extend to depths well below the Briar
Run creek bed, therefore it is entirely possible that
contaminants could migrate from the landfill, under Briar
Run via bedrock fractures and reach the wells in the
Wheatland Drive area.
lOb. Comment: All contamination in the southwest residential
wells are below Federal MCLs.
Response: The most recent residential well results showed
contamination above MCLs. Also, the Commonwealth of
Pennsylvania has an ARAR to require groundwater clean-up to
"background" levels. Any exposure to a carcinogen is assumed
to marginally increase an individual's risk of cancer. The
MCLs are based on technical feasibility as well as human
health risks and are sometimes set at levels corresponding
to estimated cancer risks of 10"4 or higher (e.g., vinyl
chloride and arsenic). The maximum contaminant level goals
(MCLGs), which are based solely on potential health risks,
are set at zero for carcinogens as a matter of public
policy. The statement that residential groundwater to the
southwest is below MCLs is incorrect. The concentrations of
tetrachloroethene, trichloroethene and vinyl chloride
exceeded their MCLs during 1990.
lOc. Comment: Groundwater concentrations of hazardous substances
are decreasing.
Response: See response to Comment 9 on page 12 (above) .
lOd. Comment: All cancer risks should be reported in their range
of ZERO up to the calculated risks.
Response: This comment is unclear; however, the risk
assessment was prepared according to EPA guidelines.
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lOe. Comment: EPSrshould not use historical data to-calculate
£ " Reasonable Maximum Exposures for future" rislct exposure
•*?;.•• — ResponsesBased on the-responses ta comment 9>; j.vv«rr-v«; r
Bsfe^:'. -i v; - ----- ~;(cj^-andi^d^abpve], that-assertion JL&-- incorrect* Groundwater
":-^ is regarded-asi" a potential; drinking- watlfe?source throughout
:'.;•.•";'--*": the area not.,just at the locations ofe existing^ water supply
;^s&r~- ,-.: wells. Groundwater contaminant ^concentrations-have been
:".-.-•'-- •_ • shbwn-to fluctuate substantially from quarter-to quarter, ,.,
£r,. •'--""' : ",i". therefore, it is incalifect to conclude that risks at,
1 :- : . existing wells, have been eliminated based orfra single
i:. : ; sampling event during which no MCLs were exceeded^ Further,
^|t 1 .^Ji as discussed in the risk assessment* (RA) *> vinyl chloride can
p^ •., pose potentially significant cancer risks- at concentrations
I!;™'V.. v below the detection limitsf used-in the available analyses.
r^s For^ alir of these reasons^ it is incorrect to-, conclude that"
^tiS potential cancer risks from groundwater contamination, from
"•--••• the Strasburg Landfill have-been- elimiri^ed.- -.' ^ ..- A;- >
Thire aE» not,- comments from Maxus- EneEgy^numbered^'"! I andj 12 .
"^^fer-- 13; Comment::Contact risk should be recalculated due the
i^-s ,^i - implementation of tfie- fenced Overalls risk should
recalculated as per comments iri Attachment V.,
•'•'-:- 1 Response: The^^ security-; fence is;designed to-Jje porous, and "
^^KS^ -? will not prevent leachate from migrating off-site.
:||ipife--:--- - "- Furthermore^: leachate has been observedyin the past ^
"dft^.,...-• .•""•"'-• migrating off ofr the landfill.-^(Also see responses to- "
_.^^^....T__T Attachment__vy.-^_ -^ ^ V_;.'/"'' ^": -"".:- :/,''' ".••"-.;
14._; Commeitt: ^The^commenter asserts that the UV/ozone treatment
^ system ia not practical or^feasible because pretreatment
-, V; requirementjpwere not adequately:, assessed.^ .Operational: -.-:
Li..-•-•='• "costs, incliidiii^disposalvwere^xinder estimated ^ f .. ,,-^--
r -••:"'"" Responses Th(e^^o€studiea£recommended^in^^^^
;^;:i study/report-wtilSxidentify if pretreatment isJ necessary".
"^': 7 -: r Likewise, thet-pilote studiea will provide information to
^J:T -^;: ^^ evaluate- site specific, costs r such as: disposal *-.-.;-,,. Also>: the-
=-€!f"" ~* _- ;pilot-studies^-recommended wiKfe provide the. necessary data- to
^fe'£,:^ :£;1 ;dletermine_:i£-UV/;ozone treatment is:a practical or reliable
gjk-::^"-""^"^--treatment metfeod^for Strasburg Landfill^ leachate..- ^ - •=•
ig?~-7^-.-..-.;. :%, Pretreatment requirements- to remove iron, suspended' solids
g^J:•_•":. . ,;: and^ manganese should be similar tQ that required for air
jjttzfj.^.,'"-^";stripping^-. Therefore, in keeping with the overall goal for
T- ' * ' treatment and-complete destruction of waste ,-UV/pzone was
fj~" -.>••'' selected 'as the recommended method pending results of the
:i- treatability tests. Should the treatability tests indicate
an overall higher cost of operation relative to air^
stripping with vapor phase carbon adsorption, then a change
15
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could potentially be made at that time to the most cost
effective method. -'
15. comment: The commenter asserts that air stripping should be
selected as the leachate treatment method because it has
been demonstrated to be effective.
Response: Air stripping was installed at the Strasburg
Landfill by PRPs to replace the need for daily leachate
removal by tank trucks to an off-site disposal facility.
This reduced the daily cost of leachate hauling and'disposal
and eliminate the risk of transportation related accidents.
Air stripping is a mass transfer of volatiles from water to
air, whereas, UV/ozone is an innovative treatment technology
that destroys volatiles. The pilot studies recommended in
the feasibility study report will provide information on the
pretreatment and overall operational costs for the system.
Pending this cost information and the potential for PADER to
require Vapor Phase carbon adsorption, the initial method
selected to be included in the selected alternative was
UV/ozone. This is in keeping with EPA's overall policy of
preference for methods which destroy contaminants. Should
the treatability study indicate an overall high cost of
operation (primarily from pretreatment requirements)
relative to air stripping with vapor phase carbon
adsorption, then a change could possibly be made at that
time to the most cost effective method.
B. SPECIFIC COMMENTS ON REMEDIAL INVESTIGATION
1. Comment: PADER may have been incorrect in stating that low
rainfall amounts in recent years may have caused reduced
contaminant concentrations in groundwater. Less rainfall
should yield higher concentrations.
Response: This comment has no effect on the remedy selected.
EPA agrees, however, with the potentiality presented by
PADER. The production of leachate in the Strasburg Landfill
is somewhat dependant upon rainfall production. As the
rainwater seeps through the compromised cap and combines
with the hazardous wastes buried inside creating leachate.
The leachate, at least a portion of it, is then carried off
site in the groundwater. If the quantity produced is smaller
and the receiving stream (groundwater) is constant, the
resultant concentration should be lower.
2. comment: The field soil gas and flux box data should have
been validated by a second independent reviewer.
Response: The soil gas and flux box data were qualified by
the field chemist using standard EPA procedures, by
16
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analyzing QC samples such as duplicates, blanks and
standards. The use of an a second in-field reviewer was not
thought to be cost effective.
3. Commentj Vinyl chloride concentrations in the Zarzycki well
were always lower than the concentrations of 1,2-
dichloroethane and trichloroethane. This confirms that the
vinyl chloride is due to degradation of other chemicals.
Response: The commenter attempted to show that the vinyl
chloride measured is due to degradation of other chemicals.
EPA asserts that vinyl chloride measured may be from a
number of sources within the landfill, including potential
degradation of chemical products and also deposition of
vinyl chloride monomer.
EPA does not agree that vinyl chloride, found down gradient
of MW-3I, is due to degradation of other chemicals. Due to
a number of reasons, including but limited to: the
fractured nature of substrate bedrock and the methodologies
used at various times for analyzing for vinyl chloride in
the groundwater.
Lastly, EPA denies the assertion that vinyl chloride
concentrations outside the landfill are solely due to
chemical degradation.
4. Comment: EPA's contractor may have significantly
underestimated the cost to provide electrical power to the
site to run the UV/Ozone equipment etc.
Response: The cost estimates included in the FS are in fact
only estimates based on (potential) motor usages. More
definitive costs will be developed at the time of Remedial
Design. However, the changes in cost due to electrical
power are not significant to the point that would alter the
remedy selection.
5. Comment: EPA does not identify the specific location of the
asphaltic spray liners. EPA needs to document the existence
of these liners and the fact that they may have not been
compatible with the substances deposited there.
Response: The assertion that EPA needs to document the
existence and compatibility of the linear material is
denied. EPA has already demonstrated that contaminants from
the landfill are entering the groundwater. Further
demonstration of this assertion was not felt necessary as it
did not go to the selection of a remedy.
6. comment: The commenter asserts that site specific wind speed
data was not used for the risk assessment. Also, the
17
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commenter asserts that Philadelphia Airport weather data
should not be used for air modeling or risk assessment at
the Strasburg Landfill.
Responses The risk assessment required information on both
the annual average wind speed as well as its directional
frequency and velocity frequent distribution (stability
array or STAR data). This information was readily available
for the Philadelphia Airport weather station but not for
Chester County. It was determined that the airport data
would be reasonably representative, so it was used. It is
also important to note that minor differences in the wind
patterns would result in only minor differences in the
exposure and risk estimates. Uncertainties in the wind data
are probably very small in comparison to other uncertainties
in the risk assessment process.
Wind speed and direction data were collected by a portable
meteorological station deployed on site while the ambient
air samples were being collected. This information was used
to establish the wind direction and speed that prevailed
when the air samples were collected which allowed the soil
gas sampling locations that were upwind of the ambient air
sampling points during actual sample collection to be
determined. This allowed EPA to determine which areas of
the landfill had contributed emissions detected in the
ambient air samples and made it possible to calibrate and
validate the vapor emission model selected.
The mean wind speed used in the air dispersion modeling is
given in the RI in Table D-2 as 4.35 meters/second which is
equal to 9.73 mph.
7. Comment: EPA failed to consider whether the homes were
equipped with shower stalls or showers in tubs and should
perform the risk calculation based on the specific size of
the shower enclosure.
Response: Standard EPA assumptions concerning the size of
shower stalls were used in completing the risk assessment.
[see Figure 3-8 in the RI]. The risk estimates presented
are not intended to represent risks to specific individuals
or in specific residences, but rather the risks associated
with using groundwater, with the contaminant concentrations
observed in the residential areas, as a source of potable
water used for general domestic purposes. It is reasonable
to assume that most people shower or bathe. Showering
results in a somewhat greater potential exposure to volatile
contaminants and therefore is the appropriate assumption to
use in estimating the reasonable maximum exposure that might
occur. The assumed shower stall dimensions were 2.5 feet x
5 feet x 7 feet (Table D-5) which corresponds to the air
18
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volume above a typical residential bath tub. Assuming a
shower stall, with dimensions of, perhaps, 2t5 feet x 2.5
feet x 6 feet, would have resulted in a smaller air volume
and hence higher estimated air concentrations and exposures.
In regard to the comment regarding Zarzycki's deep well
(ref.Figure 4-4 in the RI), it can not be guaranteed that
Zarzycki's deep well is the only well southwest of the
landfill that will ever be used as a drinking water source
and that vinyl chloride and other contaminants, found
repeatedly in other wells in that area, will never appear in
these wells. However, since the intent of the risk
assessment is to estimate the risks that use of groundwater
as a drinking water source anywhere in the vicinity of the
landfill could pose, the approach used in the risk
assessment for this operable unit is appropriate.
8. Comment: EPA should use the data obtained from the shallow
Zarzycki well for risk assessment purposes.
Response: The commenter asserts that the data gathered from
the Zarzycki shallow well should not be used for assessment
purposes. However, EPA disagrees, since the shallow well is
a sample point in an aquifer used for domestic water
purposes.
9. Comment: Page 4-70 of the RI states that the Strasburg
Landfill is the only known contaminant source for Wheatland
Drive. The residents may have contaminated their own wells.
Response: There is no statement on Page 7.70 in the RI
report regarding the contaminant source for Wheatland Drive
residents.
10. Comment: The commenter asserts that Table 4-19 (vinyl
chloride data) should be rejected based on the qualifiers.
Response: EPA rejects this assertion and believes that the
data was used appropriately in making this determination.
The field results reported in Table 4-19 were not used in
the quantitative risk assessment. The laboratory results
reported in Table 4-20 were used.
11. Comment: The commenter asserts that improper data was used
in calculating the risk associated with ambient air portion
of the risk assessment. The commenter also asserts that
there can be no off-site inhalation hazard determined from
the air.
Response: Vinyl chloride was detected in ambient air sample
EE012 at 0.48 ppb. The wind direction and velocity at the
19
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site were monitored by a portable met station while the air
samples were being collected. The on site wind direction
data indicated that the wind was blowing from the southeast
to southwest sector during the time sample EE012 was being
collected. Thus it was downwind from the high soil gas area
along the southwestern edge of the landfill.
It is often possible to detect and estimate the
concentrations of chemicals when they are present in samples,
at concentrations below their formal detection limits. HHEM
Exhibit 5-4 indicates that it is acceptable to use such data
(J-gualified data) in a risk assessment, and estimated
values typically are used since they provide the best
available estimates of the concentrations actually present.
The ambient air data was not used directly in the risk
assessment because it is only representative for the weather
conditions (wind direction and velocity) that existed at the
time it was collected. The risk assessment requires
estimates of the annual average concentrations at potential
exposure points. These values were estimated by starting
with the measured soil gas concentrations, which do not vary
significantly for hour to hour or day to day, then using
mathematical models to predict the average ambient air
concentrations. The modeling approach was verified by
comparing the modeled concentrations for the wind conditions
observed on site the day the air samples were collected to
the air concentrations actually measured on site that day.
Very good agreement, about ±20%-which is well within
experimental error, was obtained.
The values of 1,516 and 2,428 ppb for vinyl chloride listed
in Table 5-14 are the average soil gas concentrations used
as a starting point to estimate the annual average ambient
air concentrations by the modeling process just described.
The modeled concentrations for on site air used in the
exposure and risk estimation calculations are given in Table
5-41. The estimated exposure point air concentration for
vinyl chloride is 3.83 x 10*4 mg/m3 which is equivalent to
0.18 ppb* and is consistent with the concentration of 0.48
ppb measured on site. When performed correctly this
"reality check" appears to be quite satisfactory.
(*Note that the 0.18 ppb concentration is an estimate of the
average vinyl chloride concentration in the breathing zone
along the; perimeter road at the toe of the landfill where a
site visitor might walk or ride an ATV. It is not the
modeled concentration predicted for the EE012 sample
location on the day sampling occurred.)
20
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12. Comment: The commenter asserts that an informant listed the
PVC waste in the south side of the landfill. .-
Responset This is a misquote from the RI report. The
location of the PVC deposited waste is consistent with the
location of the high vinyl chloride soil gas measurements.
13. Comment: The commenter asserts that the underdrain system
was built in the groundwater table.
Response: EPA has no documentation to support or deny this
allegation. EPA understands that the purpose of the
underdrain system was to collect groundwater before coming
in contact with landfilled material.
14. Comment: The commenter asserts that various organic
compounds with densities greater than 1 are likely sources
of deep groundwater contamination.
Response: This assertion is only true if the contaminant is
present at a concentration above its water solubility limit
so that it forms a separate non-aqueous phase liquid (NAPL)
layer. If the density of the separate liquid layer is
greater than that, of water, it will sink. However, at lower
concentrations at which a contaminant is completely
dissolved (like in the groundwater at the landfill), the
contaminant distributes more or less uniformly in the water
and does not sink independent of the water in which it is
dissolved. The comment is incorrect.
15. Comment: The commenter asserts that only validated and
reliable data should be used in risk assessments.
Response: The HHEM in Section 5.1 provides for combining
results from different investigations provided the
analytical methods and data quality are comparable. The
risk assessor contacted the PADER laboratory that analyzed
the samples for the PADER residential well monitoring
program for the Strasburg Landfill area and was satisfied
that the methods used and the overall quality of this data
were comparable to groundwater data.generated by the RI.
The PADER data showed that the groundwater contaminant
concentrations fluctuate considerably from quarter to quar-
ter. In light of this variability, the limited data
available from the remedial investigation (only one round of
sampling from most wells) did not appear to be sufficient to
adequately characterize the groundwater contamination in the
area. Since the PADER data provided a broader data base
than the RI data, and also provided a historical record of
the groundwater contamination in the area, it was included
in the risk assessment. The PADER data does show that the
greatest groundwater contaminant concentrations in the
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residential area southwest of the landfill occurred during
the 1986 to 1988 time period. It also shows-that the level
of contamination is highly variable from quarter to quarter
and does not provide adequate information to confidently
predict the rate at which contaminant concentrations might
decline in the future. Risk estimates corresponding to both
the historical average and the 1990 average concentrations,
a period during which contaminant concentrations had
declined from their 1986-88 highs, were included in the risk
assessment. The possibility of further decreases in
groundwater contaminant concentrations and the possible
overestimation of the risks that could result were included
in discussions of the uncertainties associated with the risk
estimates.
As stated in the Remedial Investigation Risk Assessment
Section 5.2.2.1 (p. 5-12), no CLP methods have been
established for air or gas samples. A standard (non-
CLP) EPA method was used to evaluate ambient air;
however, this method is not suitable for analyzing soil
gas samples. As discussed in Response B-ll, ambient
air data collected on a single occasion is not suitable
for use in the risk assessment. The soil gas data was
judged to be the best data available to use in
estimating the annual average ambient air concentra-
tions needed in the risk assessment. The general
practice of using the best available data to estimate
exposure point concentrations was used throughout the
risk assessment.
16. Comment: The commenter asserts that EPA cannot make
arbitrary assumptions that chemicals are present in
performing risk assessment calculations.
Response: The criteria used to determine if there was reason
to believe a chemical might be present in a sample were
clearly stated in the risk assessment. It should be noted
that this approach results in lower, more realistic
estimates of contaminant concentrations than the uniform use
of 1/2 the DL recommended in the HHEM.
17. Comment: The commenter asserts that only air results from
Table 5-10 for vinyl chloride and other contaminants should
be used for calculating the contaminant concentrations for
air pathway exposure assessments. Also, the commenter
asserts that the risk assessment should not use calculated
exposures that exceed measured ambient air values.
Response: The soil gas results were not simply averaged. A
weighting factor was used to account for the size of the
area represented by each sampling point. Thus when more
points were added in an area the area represented by each
22
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point decreased and the weighting factor was reduced accord-
ingly. The average soil gas concentrations obtained in this
way are reasonably representative of the high soil gas
concentration area along the edge of the southern half of
the landfill. This area can be regarded as a hot spot
within the overall Superfund site and was assessed as such
in accordance with guidance in the HHEM Section 6.5.3.
There is also a perimeter road that runs along the edge of
the landfill in the high soil gas area which is known to be
used by site visitors. Since potential exposure to site
Visitors was being assessed, it was appropriate to use the
soil gas concentrations in the hot spot to model the ambient
air concentrations in this area.
The issue of the estimated exposure point air concentrations
was discussed in-the response to comment B-ll.
18. Comment: The commenter asserts that all water and sediment
data should be used in the risk assessment calculations, not
a limited selection that results in a biased risk estimate.
Responses The contaminant concentrations in Table 5-15 were
used to assess potential direct contact exposures to
contaminants in the seep areas and settling ponds on site.
Data from Tables 4-41 and 4-43, which report results for
water and sediment samples from seep areas and settling
ponds on site, were included in this calculations of the UCL
concentrations given in Table 5-15. Data for methylene
chloride and acetone from these tables were not used because
they had "B" qualifiers indicating that these compounds were
also present in the associated blanks at concentrations that
rendered these data unusable for risk assessment purposes
(HHEM, Section 5.5). Data from Tables 4-40 and 4-42, which
report results for water and sediment samples from off-site
locations along Briar Run and Brandywine Creek, were not
included in the calculations of the UCL concentrations in
Table 5-15 because they were not collected from the
potential exposure points under consideration.
19. Comment: The commenter asserts that all PADER and other
unvalidated data should be removed due to the age of the
data and uncertainties as to its validity. Also, the
commenter asserts that data from the Zarzycki shallow well
should not be considered because that well water zone is no
longer used for residential consumption.
Responses The reasons for using the PADER data were
discussed in the response to comment A-9 and the reasons for
using the ambient air and soil gas data were discussed in
the response to comment B-ll. The responses to comments A-
lOe and B-7 discuss the reasons for using all of the
available groundwater data in assessing groundwater risks.
23
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20. Comment: The commenter asserts that vinyl chloride does not
exceed MCLs and should not be used for risk assessment
purposes.
Responses EPA's policy for conducting risk assessment is to
develop values based on cumulative effects of substances
determine present. (See response to comment A-lOb).
21. Comment: The commenter asserts that Table 5-17 should be
revised to show no detectable vinyl chloride in the
historical or current RME case for the risk assessment.
/
Response: See responses to comments A-lOe and B-7.
22. comment: The commenter asserts that the exposure duration
should be nonexistent after the installation of the remedy
in OU2.
Response: As stated above, the fence is not intended to
prevent leachate from leaving the landfill. Values based on
EPA guidance or information in the scientific literature
were used in the exposure estimation calculations for all
parameters for which they were available. Some factors such
as the exposure frequency and exposure time depend on site
specific factors such as the proximity of residential areas
to the site, ease of site access, the physical
characteristics of the site and climatic conditions. The
values used for exposure time and frequency were based on
estimates of the level of site visitor activity which were
based on observations made during numerous site visits. If
ATV riders only rode through contaminated leachate and
sediment once during a site visit, the volatiles might well
evaporate from the skin making a dermal exposure time of 10
minutes reasonable. However, if someone is "off reading" on
site it is probably more likely that they would ride around
the site and through seep areas repeatedly, re-exposing
themselves on each occasion. This would, certainly be an
appropriate reasonable maximum exposure assumption. For
these reasons EPA believes that the exposure time and
frequency assumptions used were appropriate.
A
The baseline risk, assessment estimates the risks the site
could pose assuming no remedial actions are taken (the no-
action alternative). Separate risk estimates were prepared
for the various potential exposure pathways, exposure points
and receptors to facilitate evaluation of the potential risk
reductions that could be obtained by implementing remedial
measures affecting specific exposure pathways or exposure
points.
24
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be a groundwater discharge point, preventing groundwater
contamination on the other side.
Response: The reasons for using data from monitoring wells
28 and 51 to evaluate potential future groundwater risks in
the Wheatland Drive area are discussed on page 5-54 of the
RA. The highly featured bedrock geology in the area makes
it difficult to predict groundwater flow patterns with
confidence. The fracture trace study done by EPA identified
fracture traces leading from the landfill to the residential
area along Wheatland Drive, therefore a possible groundwater
migration pathway linking the landfill and the Wheatland
Drive area may exist. Many of the Wheatland Drive wells
extend to depths well below the Briar Run creek bed, there-
fore, groundwater might well pass under Briar Run on its way
to the Wheatland Drive area. Contaminants were found in
monitoring wells MW-2S and 51, located about midway between
the landfill and the closest Wheatland Drive homes. Given
the uncertainties in the groundwater flow patterns and the
possible existence of a migration pathway linking the
landfill and Wheatland Drive, it is possible that these
contaminants could reach Wheatland Drive in the future.
Since these contaminants have not been found at Wheatland
Drive in the past, the contaminant concentrations found in
monitoring wells MW 2S and 51 were used to assess the
possible future groundwater risks that might occur if this
contamination were to reach the Wheatland Drive wells in the
future.
26. Comment: The commenter asserts that the most recent 1990
well results are representative of the upper confidence
level. The commenter also asserts that EPA should use only
the most recent active residential well data for assessing
risk to Laurel Road residents.
Response: See responses to comments A-9, A-lOc, and B-7.
27. comment: The commenter asserts that Tables 5-50 and 5-51
need to be recalculated using only recent data.
Response: This assertion is denied. See other responses to
comments A-9,A-10c, and B-7.
28. Comment: The commenter asserts that the modeling of surface
air exposures to,small animals based on subsurface (soil
gas) measurements is inappropriate. Soil gas measurements
should only apply to animals burrowing to the depth where
the measurements were made, and surface field mice are not
at risk from subsurface contaminants. Surface air
measurements should be used to estimate small animal
exposure.
26
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Response: The use of soil gas measurements for air pathway
estimates, rather than ambient air measurements, is
justified in response to comment B-ll. In addition, an
estimate of air concentrations near the ground surface was
needed to determine the exposure to small animals. Ambient
air samples were taken several feet above the ground,.and
therefore could not be used for this purpose.
The burrowing activities of small animals were not
considered in the risk assessment, because evaluation of
exposure in the near-ground breathing zone is considered to
be more generally applicable to burrowing and non-burrowing
animals alike.
The statement that surface field mice are not at risk from
soil gas contaminants is unjustified. Upward,
pressure-driven: movement of gases is expected to be a
dominant vapor release mechanism for this landfill. Still
air at the soil-air interface is likely to contain high
levels of contaminants,...relative to the overlying.turbulent
air layer* Therefore, small animals could have significant
exposure to soil gas contaminants.
29. Comment: Commenter asserts that EPA has not properly
informed the.public with risk associated with the landfill.
Response s EPA. disagrees. The commenter's conclusion about
the source of groundwater contamination is not supported by
the available information. The probability of the true
groundwater risks southwest of the landfill exceeding the
estimated risks is unknown. The 1 in 10,000 figure was used
for illustrative purposes only as discussed in the response
to comment B-24. _.:... : ; , ...<
30. Comment:. The commenter asserts that vinyl chloride may have
been brought to the site from household and other municipal
waste., •••••- -s-.^-^r .
Response: EPA does not disagree with the assertion; however,
this comment does- not concern the selection of remedy for
this operable unit.
Comment: The commenter also asserts that EPA should not rely
on ^invalidated and qualified field data for risk
assessments. -~
Response: Risk assessments performed for this investigation
are consistent with EPA guidelines. See response to A-9 & B-
10.
27
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ATTACHMENT C
SPECIFIC COMMENTS ON FEASIBILITY STUDY
1. Comment: The commenter asserts that the risks associated
with the site with the implementation of OU2 is less than 1
x 10~6 for all people.
Responses The risk assessment developed for the operable
unit was based on the assumption of OU2 being in place and
is calculated as 1 x 10~4, which in accordance with the
National Contingency Plan (NCP), is just cause for the
action envisioned for this operable unit.
2. Comment: The commenter asserts that the Strasburg landfill
should be characterized as a typical municipal landfill.
Response: EPA disagrees because the landfill was permitted
and did accept industrial waste.
3. Comment: The commenter asserts that chromium and nickel
discharge limits should not be required below natural
levels.
Response: EPA states that water discharge limits are not
related to natural soil sampling conditions and are
established to attain stream water quality criteria.
4. Comment: The commenter asserts that vinyl chloride data
should not be used.
Response: See responses to Comment B-15.
5. Comment: The commenter asserts that since vinyl chloride is
not present in MW-3I, downgradient users should not be
affected by any vinyl chloride release from the landfill.
Response: EPA denies this assertion. See response to
comment B-3.
6. Comment: The commenter asserts that the risk assessment for
air exposure should be recalculated.
Response: EPA denies this assertion. See response to
Comment B-ll.
7. Comment: The commenter asserts that health risks have been
reduced to acceptable levels through the implementation of
OU1 and OU2.
28
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Responses EPA denies this assertion. See response to
Comment C-l.
8. Comments The commenter asserts that homeowners have
contaminated their own groundwater, particularly in the
Wheatland Drive area.
Response: EPA denies this assertion. There is no evidence
to support the assertion that contamination has been caused
by any other source than the Strasburg Landfill.
9. Comments The commenter asserts that OV/ozone should not be
considered practical or reliable for treating leachate
generated at the Strasburg landfill.
Response: See response to Comment A-14 of Attachment 1. In
addition, the contaminant loading for leachate collection
from other areas of the site may increase. The pretreatment
requirements for UV/ozone have not been determined;
therefore; the commenter's claim that significantly more
waste will be generated for UV/ozone is unsubstantiated
(information will be generated during treatability test).
10. Comments The commenter "concurs11 that waste removal,
groundwater barriers and groundwater- extraction are not
practical or effective.
Responses Since this comment is taken out of context, EPA
cannot agree or disagree. , _
11. Comment: The commenter asserts that supplied water should
not be considered as more protective of human health than
the current water supply.
Responses EPA is not considering incorporation of a public
water supply as part of the operable unit.
12. Comments The commenter asserts that the carbon treatment
units will be re-engineered for point-of-use treatment.
Responses The carbon treatment units are already installed.
Re-engineering of the carbon treatment units is not being
considered.
13. Comments The commenter asserts that all of the factors
associated with operations, maintenance and disposal have
not been considered.
Responses The commenter is confusing groundwater data with
leachate data. There is no evidence to show the
concentration of VOCs in the leachate are decreasing. Due
to cell construction techniques used at the landfill, there
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may be a delay when contaminants are released. The
treatment schemes discussed in the feasibility study report
are inclusive and comprehensive to address possible
scenarios at the site.
14. Comment: The commenter asserts that risk level as of
November 1990 are considered safe and the situation
continues to improve.
Responset Based on the information gathered to date, EPA
disagrees with this assertion.
15. Comment: The commenter asserts that the secondary leachate
collection system must remain above seasonal high water
table level.
Response: This issue will be resolved during the design
stage for this operable unit.
16. Comment: The commenter asserts that the existing cap need
only to be repaired and not replaced.
Response: Based on observations performed by landfill
experts, the existing cap has been extensively compromised.
This is evidenced by numerous leachate seeps - which
continue to flow and emerge at new locations across the
surface of the landfill. Therefore, EPA feels it is more
cost and risk based effective to replace rather than repair
the existing landfill cap.
17. Comment: The commenter asserts that the no action
alternative must consider current risk reduction activities
and that 98% of the existing cap is intact.
Response: The no action alternative did consider the
current risk reduction activities. Furthermore, EPA has not
asserted that 98% of the cap is intact but rather that
observations have shown that at least 2% of the cap was
observable and was severely deteriorated.
18. Comment: The commenter asserts that replacing the cap would
be dangerous to workers and local residents and repairing
the existing cap would be as effective as replacement.
Response: EPA is aware of the dangers associated with
replacing.landfill caps and will ensure that appropriate
safeguards, including extensive on-site air monitoring, will
be implemented. As stated above, EPA has stated it is not
feasible to repair the existing cap. Replacement of the cap
is necessary.
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ATTACHMENT II
DSCC'S PVC WASTE
1. Comment: The commenter asserts that DSCC only disposed
physically oversized polymer resins.
Response: According to information provided by DSCC to EPA,
the material from their operation contained vinyl chloride
monomer.
2. Consent: The commenter asserts that there was no
misrepresentation of the waste contents by DSCC.
Response: Based upon available information, EPA does not
assert that there was a misrepresentation of the waste
contents.
3. Comment: The commenter asserts that no evidence has been
presented to show that unreacted vinyl chloride could
somehow dissociate from the PVC under landfill condition [as
in U.S. vs. New-Castle County, et al.].
Response: This comment is not concerned with the remedial
action proposed by the decision but rather goes to the issue
of potential responsibility (and the subject of potential
future enforcement actions). Although EPA disagrees with
this statement and comparison, EPA will not respond further,
at this time to this assertion.
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ATTACHMENT III
SOURCES OF VINYL CHLORIDE AT THE SITE
Comment: The commenter asserts apparently contradictory
statements regarding the production of vinyl chloride from
PVC. On the one hand, the commenter asserts that PVC resin
cannot degrade to vinyl chloride monomer and, on the other
hand, cites documented sources where levels of vinyl
chloride have been measured as a result of PVC products.
Response: EPA has not attempted to quantify the vinyl
chloride present at the landfill because to date we have not
be able to review complete disposal records of material
taken to the site. As stated above, in response to comment
on Attachment II-3, the issue of vinyl chloride production
does not concern the issue of remediation as proposed for
this operable unit.
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ATTACHMENT IV
CAUSES OF LEACHATE RELEASE AT THE SITE
1. Comment: The comnenter asserts that there are no unusual
volumes of hazardous substances concentrations at the site
that would require a Superfund response. Furthermore, the
commenter asserts there were numerous technical problems
documented that were associated with development, operation :
and maintenance of the landfill.
Responses EPA neither agrees or disagrees will the
assertion regarding the history of the site. Since this
site poses a threat to the human health and the environment,
as defined in the NCP, EPA is tasked with effecting remedial
actions to correct these problems as they exist today. EPA
agrees that it must consider the development, operation and
maintenance of the landfill to the extent those actions
directly affect current remedial strategy.
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ATTACHMENT V .
Flaws in the Risk Assessment
The comments listed in this attachment regarding the risk
assessment have been addressed in the specific comments listed
above.
Paragraph l
Comment: EPA has ignored the site risk reductions resulting
from the installation of the fence on Operable Unit 2.
Response: The baseline risk assessment estimates the risks
the site could pose assuming no remedial actions are taken
(the no-action alternative). Separate risk estimates were
prepared for the various potential exposure pathways,
exposure points and receptors to facilitate evaluation of
' the potential risk reductions that could be obtained by
implementing remedial measures affecting specific exposure
pathways or exposure points. Furthermore, as pointed out
previously, the fence will not serve as an effective barrier
in keeping the leachate on the landfill.
Paragraph 2
Comment: EPA needs to recalculate risks using the expected
exposure concentration for each year. Using this approach no
risk from the site exists.
Response: The data used in the risk assessment acknowledges
that groundwater contaminant concentrations southwest of the
landfill appear to be decreasing. The reasons for this
observed decrease is not clear, however, PADER has indicated
that it may be due to the recent years' low total rainfall.
The available data show an overall decrease in groundwater
contaminant concentrations from the 1986-88 time period to
1990; however, they also show that the concentrations vary
substantially from quarter to quarter. Given this
variability and the absence of consistent and predictable
trends in the data, a reliable estimate of the rate of
pqtential future decreases in contaminant concentrations
could not be obtained from the available data.
It might be theoretically possible to model the future
groundwater contaminant concentrations; however, there are
at least half a dozen environmental processes, each with its
own substantial uncertainties, that would have a bearing on
the concentrations. These processes include the rate at
which contaminants are released from the landfill, the rate
at which contaminant concentrations within the landfill are
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depleted over time as a result of migration and degradation,
the velocity and direction of groundwater flow, retardation
of contaminant movement in the groundwater as a result of
interactions with organic carbon and soil minerals, possible
biodegradation and biogeneration of contaminants in the
groundwater, and changes in contaminant concentrations due
to other chemical reactions and volatilization. The
complexity of the problem and the magnitude of the
uncertainties involved in estimating the combined effects of
all of these processes effectively preclude obtaining
reliable estimates of future groundwater contaminant
concentrations through modeling.
With all of the difficulties and uncertainties inherent in
trying to predict future groundwater contaminant
concentrations, it would be very difficult to know whether
any estimates obtained would be adequately health
protective. Use of the steady-state assumption is likely to
overestimate long-term exposure concentrations, as acknowl-
edged in the risk assessment; however, it can be confidently
assumed to be health protective. HHEM acknowledges in
Section 6.5.1 that it is frequently necessary to assume
steady-state conditions because the information required ta
estimate non-steady-state conditions is not readily
available.
Paragraph 3
Comments Based on the commenter's interpretation of the
data, there should be no excess cancer risk due to vinyl
chloride or other contaminants, because the measured levels
will go to below the MCL.
Responset The role of the baseline risk: assessment is to
provide EPA's risk managers with estimates of the aggregate
risks posed by a site, taking into account all of the
contaminants present and all of the environmental media and
pathways by which exposures could occur. This is usually
done by combining site specific exposure estimates with
quantitative- toxicity estimates for each chemical of
potential concern, as in the present risk assessment.
Occasionally^ for very simple sites having only a small
number of contaminants and exposure pathways, a compilation
of MCLs and. other ARARs can be used in place of a site
specific risk assessment provided ARARs have been
established for all of the contaminants and environmental
media involved. This was not the case for the Strasburg
Landfill. For more complex sites a list of ARARs is
compiled separately then both the aggregate health and
environmental risks, estimated by the risk assessment, and
the available ARARs are taken into account by the risk
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manager(s) in selecting an appropriate remedial response for
the site.
Any exposure to a carcinogen is assumed to marginally
increase an individual's risk of cancer. The MCLs are based
on technical feasibility as well as human health risks and
are sometimes set at levels corresponding to estimated
cancer risks of 10~4 or higher (e.g., vinyl chloride and
arsenic). The maximum contaminant level goals (MCLGs),
which are based solely on potential health risks are set at
zero for carcinogens as a matter of public policy. The
statement that residential groundwater is below MCLs is
incorrect. The concentration of vinyl chloride exceeded its
MCL in Zarzycki's shallow well as recently as July of 1990.
Paragraph 4
Comment: The commenter asserts that the Feasibility Study
states that the residents on Wheatland Drive are protected
from contaminants in the groundwater because Briar Run
serves as a discharge point. Also, that since Operable Unit
2 has been approved only non-contact, site risks should be
used.
Response: Many of the Wheatland Drive wells extend to depths
well below the Briar Run creek bed, therefore, groundwater
might well pass under Briar Run on its way to the Wheatland
Drive area. Contaminants were found in monitoring wells MW-
2S and 51, located about midway between the landfill and the
closest Wheatland Drive homes. Given the uncertainties in
the groundwater flow patterns and the possible existence of
a migration pathway linking the landfill and Wheatland
Drive, it is possible that these contaminants could reach
Wheatland Drive in the future. Since these contaminants
have not been found at Wheatland Drive in the past, the
contaminant concentrations found in monitoring wells MW-2S
and 51 were used to assess the possible future groundwater
risks that might occur if this contamination were to reach
the Wheatland Drive wells in the future. It is a
misinterpretation of the data to state that all of the
eastern flowing contaminated groundwater is intercepted by
Briar Run.
The baseline risk assessment estimates the risks the site
could pose assuming no remedial actions are taken (the no-
action alternative). Separate risk estimates were prepared
for the various potential exposure pathways, exposure points
and receptors to facilitate evaluation of the potential risk
reductions that could be obtained by implementing remedial
measures affecting specific exposure pathways or exposure
points.
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EPA is not convinced that there are no area residents among
the individuals jogging or riding horses or ATVs on the
site. In fact, it seems unlikely that individuals would
come to a Superfund site from some distance away, bringing
their horses and ATVs with them, to engage in these
activities. Furthermore, EPA has obtained several statements
from nearby residents that they have used the site area,
including the landfill for recreation purposes. As stated
previously, the fence is not intended to be a barrier for
the leachate seeps. Since the leachate can flow though the
fence, the risk of contact exposure exists.
Paragraph 5
Comments EPA should use 10~4 as an acceptable risk for this
site considering, among other factors, the low population
densities, actual site conditions, and Operable Units 1 and
2.
Response: The acceptability of a particular risk level is a
risk management, not a risk assessment issue.
The risk assessment does not state that there is only a 1 in
10,000 chance of the actual risks being as high as the
estimated risks. The probability of the true groundwater
risks southwest of the landfill exceeding the estimated
risks is unknown. The 1 in 10,000 figure was used for
illustrative purposes only as discussed in the response to
comment B-24.
Paragraphs 6 and 7
Comments The increased risk presented by this site to the
community has no real basis in reality and is merely a paper
calculation.
Responses The cancer risk estimates were prepared and
reported in accordance with. EPA guidance (HHEM 1989 and
"Guidelines for Carcinogen Risk Assessment:, Federal
Register 51:33992-34012. 19861.
The methods used for estimating and reporting. potential
cancers risks are based on prudent public health policy as
discussed in Section 5.4.3.3 of the risk; assessment. The
'methodology was adopted in 1986 through a formal rule making
process that took public comments into consideration. The
cancer risks in the general population were well known when
EPA's guidelines for carcinogen risk assessment were
adopted. However, EPA elected to discuss cancer risks posed
by Superfund sites in terms of the additional, excess or
incremental risks posed by a site, apart from the baseline
cancer risks experienced by the general population.
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Comparison of estimated site risks to general population
risks is not part of the baseline risk assessment process or
report format recommended in the HHEM.
ATTACHMENT VI
UV/Ozone Treatment
Comment: The commenter asserts that the UV/ozone treatment
system for the leachate is not practical or reasonable for
the Strasburg Landfill site. The cost and implementability
has been underestimated in particular pretreatment and
associated residual disposal.
Response: The feasibility study report recommended pilot
studies to. develop the necessary data to evaluate if
UV/ozone treatment is practical or reliable treatment method
for Strasburg Landfill leachate. The recommended pilot
studies will also provide information to develop site
specific costs, including operational, maintenance and
disposal costs associated with the UV/ozone treatment system
for Strasburg Landfill leachate.
o Scaling was an anticipated problem as noted in the FS
text. According to the vendor, scale can be cleaned by
routine maintenance and should not require a signifi-
cant amount of time (See FS page 4-34).
o Pretreatment efforts were not described in the FS as
they will be determined as a result of the treatability
tests. However, EPA does agree that, if extensive
pretreatment is required, costs could be prohibitive;
however, experience with similar pretreatment efforts
has shown that this has not been the situation. The
Ultrox SITE report indicates a treatment (i.e. O & M
costs) cost range of $.25 to $17 per 1000 gallons. At
the 10 gpm rate 0 & M costs (exclusive of testing;
apparently Maxus only considered the operation costs
and not the maintenance and insurance costs) were
estimated at $1.2 per 1000 gallons for 200 ppb influent
or $1.4 per 1000 gallons for 400 ppb influent. These
costs would appear consistent with the Feasibility •
Study. As noted in Maxus' evaluation if extensive
pretreatment residues are generated this could
significantly increase the cost. At this point in
time, it is not clear whether air stripping or UV/ozone
will generate more residue. To assist in this
evaluation, EPA will review the operational data on the
existing air stripping system. Once the treatability
test is completed, pretreatment needs of both systems
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can be compared and a more detailed benefit analysis
can be performed. ,
o Also note that in the FS both UV/ozone and air
stripping were costed without significant pretreatment
for comparison, since reliable pretreatment information
was unavailable and will be generated during design.
The costs presented in the FS for 0 & M may be
underestimated if extensive pretreatment is required. .
In addition to the above comments, the PAOER has commented, after
the Public Comment period, in two separate letters, regarding the
draft Record of Decision. Most of their comments addressed
grammatical errors in the document and points of clarification.
These have been corrected. In addition, the following substantive
comments have been raised:
Commentt The PADER requested the addition of the PA Hazardous
Waste Regulations to the Site ARARs.
Response: EPA concurs with this comment and the Decision Document
was corrected to reflect the appropriate PADER citations.
Comment: PADER commented that Alternatives 3 and 5 were
essentially the same with the exception of landfill gas emissions
and do not justify requiring separate alternatives.
Response: EPA agrees that the sole distinction between the
Alternatives is the type of treatment for the landfill gas
emissions. The alternatives are presented separately because,
under the evaluation criteria, the risks currently measured from
the landfill gases do not warrant the incremental increase in
costs associated, with active landfill gas treatment as presented
in Alternative 5.
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