PB97-963143
EPA/541/R-97/150
January 1998
EPA Superfund
Explanation of Significant Difference
for the Record of Decision:
Brodhead Creek
Stroudsburg, PA
9/30/1997
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EXPLANATION OF SIGNIFICANT DIFFERENCES
BRODHEAD CREEK SUPERFUND SITE
I. INTRODUCTION
Site Name: Brodhead Creek Superfund Site
Site Location: Borough of Stroudsburg, Monroe County,
Pennsylvania
Lead Agency: U.S. Environmental Protection Agency, Region
III ("EPA" or the "Agency")
Support Agency: PA Department of Environmental Protection
("PADEP")
Statement of Purpose
This Explanation of Significant Differences ("ESD") is
issued in accordance with Section 117 of the Comprehensive
Environmental Response, Compensation and Liability Act, as
amended ("CERCLA"), and is now a part of the Administrative
Record for the Brodhead Creek Superfund Site ("Site"). This
document explains significant differences to the remedy selected
in the Record of Decision for Operable Unit 1 ("ROD") for the
Site signed by the EPA Regional Administrator on March 29, 1991,
as amended by the first ESD to the ROD issued on July 19, 1994.
The ROD for Operable Unit 1 and the first ESD are attached hereto
as Exhibit 1. This is the second ESD which EPA has issued for
Operable Unit 1.
II. SUMMARY OF THE SITE HISTORY, SITE CONDITIONS, AND SELECTED
REMEDY
The Site occupies approximately 12 acres in the Borough of
Stroudsburg in Monroe County, Pennsylvania. The Site is the
location of a former coal gasification plant which operated along
the west bank of Brodhead Creek in Stroudsburg from approximately
1888 to 1944. A waste product from these operations was a black
tar-like liquid ("coal tar") with a density greater than water
and principally composed of polynuclear aromatic hydrocarbons
("PAHs"). The coal tar was placed in an open pit located on the
Site. This practice continued to the mid-1940's when the plant
was abandoned.
The geology underlying the Brodhead Creek Site consists of;.
the following stratigraphic units in ascending order: bedrock,*,
silty sands, stream gravels ("gravel unit"), floodplain deposits,
and surficial fill. The lithology of the gravel unit can be
characterized as loosely consolidated, stratified, well rounded,
coarse gravels. The gravel unit thickness averages about 10 to
15 feet, but ranges from absent in some parts of the Site to a
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maximum of over 25 feec in a stracigraphic depression near che
center of che Site.
The principal contaminants of concern at the Site are PAHs,
benzene, and arsenic. Federal Maximum Contaminant Levels
("MCLs") for drinking water established pursuant to the Safe
Drinking Water Act, 42 U.S.C. Section 300f et seq.. are exceeded
for arsenic, benzene, and benzo(a)pyrene in the subsurface gravel
unit. Proposed MCLs are exceeded in the ground water in the
gravel unit for the following PAHs: benzo(a)anthracene;
benzo(b)fluoranthene; benzo(k)fluoranthene; chrysene,
dibenz(a,h)anthracene; and indenopyrene. These PAHs, as well as
arsenic and benzene, are "hazardous substances" as defined in
Section 101(14) of CERCLA.
The March 29, 1991 ROD for Operable Unit One ("OU-1")
addressed remediation of the releases and the threatened releases
of these hazardous substances to the subsurface soils at the
Site. A complete description of the selected remedy for OU-1, as
well as EPA's rationale for the decision, is presented in the ROD
which is attached hereto as Exhibit 1. The major components of
the selected remedy are:
(1) Installation of extraction wells and injection wells in the
free coal tar areas of, .the subsurface soils;
(2) Recovery of coal tar and process water from the extraction
wells by using the innovative technology of enhanced
recovery;
(3) Separation of the coal tar from the process water followed
by treatment of the process water;
(4) Discharge of a portion of the treated process water to
Brodhead Creek and che reinjection of the remaining process
water into the subsurface soils Co enhance coal tar
recovery;
(5) Disposal of Che recovered coal tar at an off-site permitted
incineration facility;
(6) Installation of a fence to prevent public access during
remedial activities;
(7) Imposition of deed restrictions to limit future use of the
Site; and
(8) Monitoring of ground water and biota in Brodhead Creek to .:•
ensure protection to human health and the environment.
The enhanced recovery process which has been employed at the
Site is the Contained Recovery of Oily Waste ("CROW") process.
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The ROD for Operable Unit Two ("OU-2"), issued on June 30,
1995, addressed ground water contamination and residual coal tar
contamination in the subsurface soils and established a technical
impracticability ("TI") zone within which EPA determined it would
be impracticable to remediate ground water and residual coal tar
contamination. Consequently, the ROD for OU-2 selected No
Further Action for ground water and residual subsurface soil
contamination.
III. DESCRIPTION OF SIGNIFICANT DIFFERENCES TO THE ROD FOR OU-1
Following the issuance of the ROD for OU-1 and during
remedial design/remedial action ("RD/RA"), EPA determined that
several changes should be made to the remedy set forth in the
ROD. These changes were identified as Significant Differences
and did not constitute an amendment, as that term is used in 40
C.F.R. §300.435 (c) (2) (ii), to the ROD.
On July 19, 1994, EPA issued an ESD to the ROD for OU-1
which, among other things, modified the method that would be used
to quantify the amount of coal tar to be removed during remedial
action. The ROD for OU-1 stated that the enhanced recovery
process would be applied to the free coal tar areas on site (the
RCC area and the MW-2 area.) , and should involve the removal and
treatment of at least 60% of the free coal tar from the
subsurface soils and, if technically feasible, more than 60%.
During RD/RA, EPA determined that the enhanced recovery process
should be operated until the increase in cumulative recovery of
coal tar dropped to 0.5% or less per pore volume of water flushed
through the formation. EPA explained the reasons for this change
in the July 19, 1994 ESD.
The Significant Differences between the remedy presented in
the ROD for OU-1, as amended by the July 1994 ESD, and the remedy
that will be implemented as a result of the ESD being issued
today, are discussed below. With the exception of these
Significant Differences, all terms of the ROD for OU-1, as
amended by the July 1994 ESD, remain in effect.
A. EPA is Modifying the Remedy for the MW-2 Area of the Site by
Substituting Intermittent Pumping for the CROW Process in
this Area.
In this ESD, EPA is further modifying the remedy for the MW-
2 Area of the Site by substituting intermittent pumping for the
CROW process in this area for the following reasons. Based upon
the assumptions made in the original feasibility study completed
in 1991, the total surface area of the coal tar accumulation
the subsurface soils in the MW-2 area was determined to be
approximately 450 square feet containing approximately 338
gallons of free coal tar. In December of 1993, a supplemental
investigation was conducted in the MW-2 area to further
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characterize che extent of free coal tar contamination in this
area. This supplemental investigation resulted in a revised
estimate of a total surface area of coal tar accumulation of
approximately 70 square feet containing approximately 60 gallons
of free coal tar. However, it is likely that neither estimate is
completely accurate because of the number of data points used in
the assessment and the complexity of accurately defining coal tar
migration in the subsurface soil. Nonetheless, the volume of
coal tar in the MW-2 Area is relatively small.
Although it would be possible to implement the CROW system
in the MW-2 Area, EPA determined that it would not be
economically practical to implement CROW for such a small volume
of coal tar. In addition, the MW-2 Area abuts the slurry wall at
the Site and is located in the bench of the flood control levee
on Site. During the predesign boring program conducted in the
MW-2 Area to further characterize the extent of free coal tar,
several times the drill bit encountered the slurry wall and/or
the rip rap associated with the levee. Thus, installation of
injection wells in the MW-2 Area would be difficult, and adequate
protection of the slurry wall would be a primary concern.
Therefore, EPA determined that the free coal tar located in
the MW-2 Area should be removed via intermittent pumping instead
of the CROW process. This -change has already been implemented.
Wells MW-2 and MW-2B were inspected for coal tar accumulations
initially at least once per week and then less often after the
first several months had passed. When coal tar was detected in
the wells, the coal tar was removed via pumping. This
intermittent pumping continued until EPA determined, in
consultation with the Pennsylvania Department of Environmental
Protection ("PADEP"), that the intermittent pumping could cease.
B. EPA is Converting the Interim Remedy for OU-1 into the Final
Remedy for OU-1 and for the Site as a Whole.
EPA originally considered the remedy selected for OU-1 only
an interim action for subsurface soil contamination. The ROD for
OU-1 stated that a final action addressing subsurface soils and
ground water would be selected in a later ROD after data
generated during the implementation of the interim action were
evaluated and further investigations were conducted on ground
water at the Site. These further investigations would address
threats at the Site presented by additional contaminated soils
and ground water.
On June 30, 1995, EPA issued a Record of Decision for
Operable Unit Two at the Brodhead Creek Site. This ROD addressed
ground water contamination and residual coal tar contamination "oin
the subsurface soils. The ROD for OU-2 selected No Further
Action as the selected remedy. EPA determined that the No
Further Action alternative, in conjunction with the OU-1 ROD, as
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amended by the July 1994 ESD, would be protective of human health
and the environment.
EPA gave the following reasons for this determination in the
ROD for OU-2. Implementation of the OU-l enhanced recovery
program for the free coal tar areas on site would reduce the
areas of highest subsurface soil contamination to residual
saturation levels. (The enhanced recovery process has already
been implemented at the Site; reduction in subsurface soil
contamination has occurred.) The OU-l monitoring program would
provide the data required to evaluate the fate of the coal tar
related constituents, the integrity of the slurry wall and the
"health" of the biological community in Brodhead Creek. This
will provide long term protection against the unlikely event that
Site conditions might change and potential exposures increase.
In addition, the slurry wall installed at the Site will continue
to prevent free coal tar from discharging to Brodhead Creek.
The OU-2 ROD further stated that there is currently no
significant potential for human health impact and no significant
risk related to ground water exposure. Ground water is not
currently used at the Site. Although hypothetical future use of
on-site ground water could result in an unacceptable risk, such
use is highly unlikely. Brodhead Creek serves as a regional
boundary to ground water flow; thus, no ground water across the
Creek from the Site would be impacted by the Site. Upward flow
gradients at the Site decrease the likelihood that the bedrock
aquifer beneath the Site will be impacted. A municipal ordinance
in the Borough of Stroudsburg requires mandatory connection to
the municipal water distribution system. EPA understands that
the Borough of East Stroudsburg has a similar ordinance.
Finally, deed restrictions to limit future use of the Site,
including ground water use, will be imposed as part of the OU-l
remedial action.
CERCLA requires EPA to conduct its remedial actions in
compliance with all environmental laws identified before the
Record of Decision, if they are applicable or relevant and
appropriate for the situation. These requirements are commonly
referred to as ARARs.
The Record of Decision for OU-l addressed all of the ARARs
related to subsurface soil contamination. See the attached ROD
for OU-l for a full discussion of these ARARs. As discussed in
the next two paragraphs, the changes to the ROD for OU-l
described in this ESD do not affect EPA's compliance with the
ARAR requirement.
w
The ROD for OU-l did not discuss ARARs relating to ground**.
water or drinking water. Since the selected remedy for OU-2 '.
required no further action for residual coal tar contamination
and ground water contamination, action specific ARARs did not
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apply. The only ARARs that applied to ground water were the Safe
Drinking Water Act MCLs promulgated at 40 C.F.R. 141 and the
Pennsylvania ARAR for ground water which required that all ground
water be remediated to "background" quality, as specified by 25
PA Code §§ 264.90-264.100, and in particular, 25 PA Code §§
264.97(1), (j), and 264.100(a)(9). In the ROD for OU-2, EPA
waived the federal MCLs and Pennsylvania's "background" ARAR on
the basis of "Technical Impracticability." Several site-specific
constraints made the implementation of engineering solutions to
the contamination impracticable. As discussed above, it is highly
unlikely that ground water at this Site will be used for drinking
water.
Since all of the risks from the Site have been addressed,
EPA has determined that a final ROD for OU-1 is not necessary.
This ESD will convert the interim remedy for OU-1 into the final
remedy for OU-1 and for the Site as a whole, with the following
changes to the remedy.
1. EPA is Adding a Requirement that the Sediments be
Sampled for Thirty Years
The ROD for OU-1 stated that a ground water and biota
monitoring program would be implemented at the Site. Among other
things, the biota monitoring included benthic community
monitoring, resident fish sampling, and sediment sampling in
Brodhead Creek. Information collected from the sediment
monitoring to date indicates that the PAH levels in the sediments
of Brodhead Creek near the vicinity of Station S-3 are elevated.
However, the abundance and diversity of the macroinvertebrate
population and the fish community appear not to have been
affected. EPA will continue to require that the sea lamprey be
sampled every five years for up to thirty years. In addition,
EPA is requiring that the sediments be sampled annually for up to
thirty years. This will ensure that the remedy selected
continues to be protective of human health and the environment.
2. EPA is Requiring that Additional Ground Water
Monitoring Wells will be Added to the Long-Term
Monitoring Network.
Several intermediate wells are currently screened in the
silty sand unit and are being used to monitor dissolved PAHs in
the ground water in that unit. The ROD for OU-2 stated that EPA
would recommend adding more intermediate wells to the long-term
monitoring network in the Proposed Remedial Action Plan ("PRAP")
for the OU-1 final remedy. Since EPA has determined that this
ESD will convert the interim remedy for OU-1 into the final c-
remedy for OU-1, a PRAP for the final remedy for OU-1 is not -*v
necessary. Therefore, this ESD, rather than a PRAP or a final
ROD for OU-1, shall require that additional intermediate ground
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water monitoring wells be added to the long-term monitoring
network.
These wells will monitor the Technical Impracticability zone
established in the ROD for OU-2 and will serve as early
indicators in the unlikely event that the dissolved PAHs in the
ground water move vertically downward toward the deeper ground
water in the bedrock. EPA, in consultation with PADEP, will
determine the number and location of these wells.
3. EPA is Requiring that Certain Wells in the Gravel Unit
be Monitored for Free Coal Tar.
Shallow wells are currently screened in the gravel unit to
monitor contaminants in that unit. EPA has determined that those
wells which have historically revealed the presence of free coal
tar shall be monitored on an annual basis for free coal tar
accumulations. If free coal tar is detected in those wells, the
coal tar shall be pumped out utilizing the same procedures as
were used for the MW-2 area wells. This intermittent pumping
shall continue until EPA determines, in consultation with PADEP,
that no free coal tar reaccumulates in the wells.
As stated in the ROD for OU-1, ground water at the site
shall be monitored on an annual basis for up to thirty years.
IV. PUBLIC PARTICIPATION
This ESD and the information upon which it is based have
been included in the Administrative Record file for this Site.
The Administrative Record also includes the RODs for OU-1 and OU-
2, the July 1994 ESD, and all documents that formed the basis for
EPA's selection of the remedies for OU-1 and OU-2. The
Administrative Record is available for public review at the
locations listed below:
U.S. EPA, Region III
841 Chestnut Building
Philadelphia, PA 19107
Hours: Mon.-Fri., 9:00 am to 4:00 pm
and
Stroudsburg Borough Building
Seventh and Sarah Streets
Stroudsburg, PA 18360
Hours: Mon.-Fri., 8:00 am to 5:00 pm
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Questions and comments on this ESD and requests to
the Administrative Record can be directed to:
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John Banks
Remedial Project Manager
Mailcode: (3KW22)
U.S. EPA, Region III
841 Chestnut Building
Philadelphia, PA 19107
(215) 566-3214
V. SUPPORT AGENCY REVIEW
The Pennsylvania Department of Environmental Protection
("PADEP") has concurred with the proposed Explanation of
Significant Differences in a letter dated September 29, 1997.
VI. AFFIRMATION OF STATUTORY DETERMINATION
Considering the new information that has been developed
since March 29, 1991, when the ROD for OU-1 was issued, and the
changes that are being made to the scope of the selected remedy
for OU-1 through this ESD, the EPA and PADEP believe that the
revised remedy remains protective of human health and the
environment, is cost effective, and complies with federal and
State requirements that were legally applicable or relevant and
appropriate to this remedial action at the time the original ROD,
as modified by the first ESD, was signed. In addition, the
revised remedy for OU-1 utilizes treatment technologies that
permanently and significantly reduce the toxicity, mobility, or
volume of the hazardous substances to the maximum extent
practicable for this Site.
Because the remedies for OU-1 and OU-2 selected in the original
RODs, as amended by the two ESDs for OU-1, will result in
hazardous substances remaining on site above health-based levels,
a review of the remedies will be conducted within five years
after the commencement of the remedy for OU-1. The review will
be conducted to ensure that the selected remedies continue to
provide adequate protection of human health and the environment.
Date Abraham Ferdas, Acting Director
Hazardous Waste Management Division
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