PB96-963122
EPA/ESD/R02-96/287
March 1997
EPA Superfund
Explanation of Significant Difference
for the Record of Decision:
A.O. Polymer,
Sparta Township, NJ
9/17/1996
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REGIONAL ADMINISTRATOR'S APPROVAL OF
CERCLA SECTION 117(c)
EXPLANATION OF THE SIGNIFICANT DIFFERENCE
INVOLVING THE
A. O. POLYMER SUPERFUND SITE
Section 1 17(c) of the Comprehensive Environmental Response, Compensation and Liability Act
(CERCLA), 42 U.S.C. §9617(c), requires that the Environmental Protection Agency (EPA) publish an
Explanation of Significant Difference (ESD) whenever it takes any remedial action that differs in any
significant respect from the final remedial action selected by EPA. The ESD must describe the
significant difference(s) between the selected remedial action and the modified remedial action,
including an explanation of why such changes were made. Section 1 17(d) of CERCLA, 42 U.S.C.
§9617(D), requires public notification of the ESD in a newspaper of general circulation. The attached
notice will be published in the New Jersey Herald.
The Record of Decision (ROD) for the A.O. Polymer Superfund Site (the Site), signed on June 28, 199 K
called for the use of a soil vapor extraction system to remove contaminants from the soils that act as the
source of groundwater contamination. The soil vapor extraction system has been operating since
December 1994 and has removed 1400 gallons of contaminants from soils. The groundwater component
of the ROD called for extraction of the contaminated groundwater, treatment with a powdered activated
carbon treatment (PACT) system,. and discharge of the treated water back into the groundwater aquifer.
Results from a treatability study performed on the PACT system with groundwater taken from the Site
indicate that the effluent from the PACT system exceeds the surface water discharge limitations. In
addition, information gathered since the issuance of the ROD has shown that the aquifer does not have
sufficient capacity to accept the treatment system effluent without adversely affecting the groundwater
plume and surrounding properties. Therefore, the treated groundwater will be discharged to the Wallkill
River located 500 feet southeast of the Site. Further, air stripping will be used instead of PACT to
remove contaminants from the groundwater. This technology is capable of meeting the surface water
discharge limits.
This ESD calls for modifying the ROD to allow the use of an air stripper to remove contaminants from
groundwater. The contingency surface water discharge point for treated groundwater contained in the
ROD will be utilized. The groundwater pumping regime will also be modified in a manner consistent
with the ROD. This remedy will be protective of human health and the environment.
William J.MuszynsW^y 33P
JEANNE M. FOX DATE
REGIONAL ADMINISTRATOR
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A.O. POLYMER SUPERFUND SITE
Sparta Township, New Jersey
Exolanation of Sianificant Difference
USEPA - Region 2
Introduction
The United States Environmental Protection
Agency (EPA) prepared this Explanation of
SignificantDifference(ESD) to explain
modifications to the remedy selected in the
Record of Decision (ROD) dated June 28,
1991 for the A.O. Polymer Site (the Site).
This ESD explains changes to the remedy
relating to the capture and treatment of
contaminated groundwater. As explained
in further detail belowr under this ESD, the
groundwater treatment process will be
changed from Powdered Activated Carbon
Treatment (PACT) to air stripping. Also, the
groundwater capture zone will be smaller,
but strategically located to clean up the
aquifer in the same amount of time
contemplated in the ROD.
The remedy is being implemented by the
potentially responsible party (PRP). Under
the Superfund Law (the Comprehensive
Environmental Response, Compensation,
and Liability Act (CERCLA)), owners and
operators of facilities and transporters and
generators of hazardous chemicals can be
held responsible for cleanup activities.
EPA is issuing this ESD in accordance with
Section 117(c) of CERCLA, as amended,
42 U.S.C. § 9617(c), and Section
300.435(c)(2)(i) of the National Oil and
Hazardous Substances Pollution
Contingency Plan (NCP), 40 C.F.R.
§300.435(c)(2)(i) (the NCP contains the
EPA regulations for implementing the
Superfund program). This ESD and those
documents that form the basis for the
decision to modify the remedy will be
incorporated into the Administrative Record
maintained for the Site in accordance with
Section 300.835(a)(2) of the NCP. The
Administrative Record is available for
review during business hours at EPA
Region II, 290 Broadway, New York, New
York 10007, (212) 637-4308, and at an
information repository at the Sparta
Township Library, 22 Woodport Road,
Sparta, New Jersey 07871, (201)729-3101.
Site Location, History, and
Contamination Problems
The Site, located at 44 Station Road in the
Township of Sparta, New Jersey, occupies
approximately four acres near Sparta
Station along the New York, Susquehanna
and Western (NYS&W) Railway. It is
bounded to the north and east by Station
Park, a municipal recreation area, to the
southeast by Station Road, and to the south
and west by the NYS&W Railway. Several
small businesses and three homes are
located on Station Road near the Site. The
Wallkill River flows 500 feet to the
southeast. The Site was operated as a
specialty polymer and resin manufacturing
facility for approximately 30 years. Mohawk
Industries began operation at the Site in the
early 1960s and was involved in the
production of various resins using
polymerization processes. Mohawk also
engaged in the reclamation of electronic
component cleaning fluids containing
various freon compounds in alcohol.
The Site has been divided into two areas:
the facility area, and the disposal pit area.
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The facility area consists of office and
laboratory facilities, a main reactor building,
assorted storage buildings and tanks, and a
non-contact cooling water pond. The office,
reactor building, lab, and tanks were used
by A.O. Polymer from 1978 until the Site
was abandoned in 1994. The disposal pit
area is located in the northern area of the
Site property and consisted of unlined pits
into which chemical wastes, primarily
solvents containing volatile and semi-
volatile organic compounds (VOCs), were
discarded.
In 1980 and 1981, a surface cleanup of the
disposal pit area was initiated by the New
Jersey Department of Environmental
Protection (NJDEP). The cleanup included
the removal of surface drums and the
excavation and removal of contaminated
soil in the disposal pit area to a depth of
approximately 10 feet. After excavation of
the disposal pits, the area was backfilled
with clean soil.
Detection of VOC contamination in the
groundwater in the surrounding area
resulted in additional investigations by
NJDEP. The Site was placed on the
National Priorities List on September 1,
1983. In December 1986, NJDEP initiated
a Remedial Investigation at the Site to
determine the nature and extent of
contamination. A ROD signed in June 1991
selected the remedial action for the
remaining soil contamination in the disposal
pit area and the resulting groundwater
contamination.
Selected Remedies in the ROD
The selected remedy called for a soil vapor
extraction system to remove organic
compounds in soils. This system works by
vacuuming air through a system of
perforated pipes placed in the contaminated
soil. A vacuum is applied to the pipes and
volatile compounds are drawn from the soil.
The selected remedy also called for
extracting contaminated groundwater
through a system of pumping wells and
treatment utilizing a powdered activated
carbon filtration system.
The soil vapor extraction system has been
operating since December 1994 and has
removed over 1400 gallons of contaminants
from approximately 7,500 cubic yards of
contaminated soil. The groundwater pump
and treatment system is currently being
designed.
Description of Significant Difference
In the ROD, EPA selected a Powdered
Activated Carbon Treatment (PACT)
system to treat the contaminated water.
The treated groundwater would then be
discharged to the aquifer by use of
reinjection wells or recharge basins.
During the remedial design, extensive field
activities were conducted to further define
aquifer characteristics and determine the
aquifer's capacity to accept the discharge
from the treatment plant. Based on the
results of these field studies (as
documented in the Pre-Design Report,
December 1995), it was found that
discharge to the aquifer could have
unacceptable consequences. Specifically,
to accommodate discharge to the aquifer,
recharge basins or numerous reinjection
wells would have to be installed in areas of
Station Park currently used as athletic
fields. Due to the shallow water table in the
area, such a discharge system has the
potential to flood other areas of the park.
Also, it has been determined that the
contaminant plume is in a steady state
condition since its size and boundaries have
not changed over the last ten years.
Discharge to the aquifer could destabilize
the steady state condition of the
contaminant plume, resulting in the
expansion of the plume into areas not
presently impacted.
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Due to the consequences of discharge to
the aquifer, discharge to the Wallkill River,
which was described in the ROD as a
contingency, will now be selected as the
point of discharge. Direct discharge to
surface water will avoid distrupting
groundwater flow and therefore allow for the
efficient capture of highest concentrations
of contaminants by extraction wells, and
further, will also cause minimum
disturbance to adjoining properties.
During the remedial design, a treatability
study was conducted to determine the level
of effectiveness that could be provided by
the PACT system. The treatability study
results showed concentrations of VOGs
including, trichloroethene, 1,1,1-
trichloroethane, and tetrachloroethene, in
the treated groundwater exceeded the New
Jersey Pollutant Discharge Elimination
System/Discharge to Surface Water permit
equivalent effluent limitations. Since the
treatability study of the PACT system
indicated that system did not meet
acceptable levels, the remedy will be
modified. An air stripper will replace PACT
to treat the contaminated groundwater.
Air stripping has been used for the
treatment of VOCs in dilute aqueous waste
streams such as those that exist in the
groundwater underlying the Site.
Performance data for similar systems
indicate that this technology will meet the
discharge standards for the Site.
Modified Remedy
Under the modified remedy, an air stripper
will be utilized to remove VOCs from
contaminated groundwater and the treated
groundwater will be discharged to the
Wallkill River. An air stripping system runs
groundwater through a tray, column, or tank
and forces air in the opposite direction to
the water flow. During this process, VOCs
are transferred from the groundwater to the
air stream. Contaminants in the air stream
are then removed by air treatment
equipment. This arrangement allows for.
use of a less complex treatment system that
will meet discharge criteria. Construction of
the groundwater capture and treatment
system is scheduled to begin in the fall of
1996.
The groundwater extraction system would
consist of wells located in the most
contaminated part of the plume. This
arrangement will avoid drawing clean river
water into the capture zone, minimize
construction and operations impacts on
park property, and increase the efficiency of
the pump and treatment system. The
groundwater remedy will remove the most
contaminated part of the plume allowing the
remaining contaminants to naturally
attenuate. A large portion of the plume will
be allowed to naturally attenuate and will
have no environmental impacts. Consistent
with the ROD, it is estimated that the
groundwater remedy will attain cleanup
standards within a period of thirteen years
once extraction of contaminated
groundwater is started. The modified
remedy will be protective of human health
and the environment and comply with
groundwater and discharge requirements.
Analysis of the Modified Remedy
In the ROD, EPA stated that the remedy
would comply with the requirements of
Section 121 of CERCLA, 42 U.S.C. § 9621.
Section 121 requires that the remedy must
at least satisfy the following two threshold
criteria:
1. Overall Protection of Human Health and
the Environment. This criterion addresses
whether or not a remedy provides adequate
protection and describes how risks posed
by the contaminated material are
eliminated, reduced or controlled through
treatment, engineering controls or
Institutional controls.
2. Compliance with ARARs. This criterion
addresses whether or not a remedy meets
all of the federal and state environmental
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standards which are applicable or relevant
and appropriate requirements (ARARs).
As described below, the modified
groundwater remedy fully meets these
criteria.
1. Overall Protection of Human Health and
the Environment:
The modified remedy remains protective of
human health and the environment. The
removal of VOCs from groundwater by air
stripping will achieve protective discharge
levels established for the stream and
reduce Site risks to an acceptable level.
The amount of time required to reach the
desired cleanup level in the groundwater
remains the same.
2. Compliance with ARARs:
The modified remedy will comply with all
ARARs identified in the ROD including the
groundwater protection and discharge
standards. The groundwater restoration
ARARs are the Federal and State Safe
Drinking Water Act Maximum Contaminant
Levels (MCLs) and the discharge ARARs
are New Jersey Pollutant Discharge
Elimination System/Discharge to Surface
Water Effluent Limitations (N.J.A.C. 7:14A),
as specified in the 1991 ROD. All off-site
disposal activities will be conducted in
compliance with all local, state and federal
regulations.
Support Agency Comments
NJDEP concurs with the modified remedy
as described in this ESD.
Affirmation of Statutory Determinations
The modified remedy is protective of human
health and the environment, complies with
federal and state requirements identified in
the ROD, and is cost effective.
In accordance with the requirements of
CERCLA, EPA will publish a notice of this
ESD in the local newspaper, The New
Jersey Herald. This ESD will be included in
the Site Administrative Record, which is
available at the repositories for public
review.
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