Superfund Record of Decision: Lindane Dump, PA


          United States        Office of
          Environmental Protection   Emergency and
          Agency           Remedial Response
EPA/ROD/R03-92/147
March 1992
SEPA    Superfund
          Record of Decision;
          Lindane Dump, 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 administrative record   j
for this site.

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50272-101^.^_____^_
REPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA/ROD/R03-92/147
3. Recipient* Accession No.
4. THte and Subtitle
SUPERFUND RECORD OF DECISION
Lindane Dump. PA
First Remedial Action - Final
5. Report Date
03/31/92
6.
7. Authors)
PflTRMininfl OrQ«wilZBDon RflpL No.
Performing Organization Name and Address
ia ProjecVTask/Work Untt No.
11. Contract(C)orGrant
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EPA/ROD/R03-92/147
Lindane Dump, PA
First Remedial Action - Final
i
Abstract (Continued)

was discontinued prior to 1920 and resultant cinder and slag, along with cryolite ore
tailings, BHC {Lindane) filter cake residuals containing pesticides, and waste sulfuric
acid containing DDT were disposed of onsite. In 1965, after the property was sold to
Allegheny Ludlum Corporation, other wastes—including construction wastes, industrial
waste treatment plant sludge, coke, rubber tires, and slag—were disposed of onsite.
During 1976 and 1977, the Alsco Commur.ity Park was constructed by the Harrison Township
on a 14.3-acre tract of the upper site area that had been previously used as a waste
disposal site. In addition, fill material from an unknown source was placed and graded
into the park. This ROD addresses contaminated soils and controlling ground water and
surface water contamination. The primary contaminants of concern affecting the soil and
ground water are VOCs, including benzene, and the pesticide Lindane.

The selected remedial action for this site includes installing a multi-layer cap where
side slopes are stabilized; construction of a combination clay and soil cap where site
slopes are unstable; vegetating the capped areas; upgrading the existing leachate/shallow
ground water collection and air stripping treatment with discharge to the Allegheny
River; sludge disposal at an approved facility; constructing and maintaining a perimeter
fence; ground water and surface water monitoring; restoration of the Alsco Community
park; and implementing institutional controls, including deed and access restrictions.
The estimated present worth cost for this remedial action is $14,122,500, which includes
an annual O&M cost of $634,000 for 30 years.

PERFORMANCE STANDARDS OR GOALS: Chemical-specific goals for leachate and shallow ground
water clean-up goals are based on the more stringent Pennsylvania state water quality
criteria standards or SDWA MCLs, and include gamma BHC (Lindane) 0.2 ug/1 and benzene 5
ug/1.
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RECORD OF DECISION
LINDANE DUMP SITE

DECLARATION
SITE NAME AND LOCATION

Lindane Dump Site
Harrison Township, Allegheny County, Pennsylvania

STATEMENT OF BASIS AND PURPOSE

This decision document presents the selected remedial action plan
for the Lindane Dump Superfund Site (the Site) in Allegheny
County, Pennsylvania, which was chosen in accordance with the
Comprehensive Environmental Response, Compensation and Liability
Act of 1980, as amended by the Superfund Amendments and
Reauthorization Act of 1986, (CERCLA), 42 U.S.C. §§ 9601 et sea..
and to the extent practicable, the National Oil and Hazardous
Substances Pollution Contingency Plan, 40 C.F.R. Part 300. This
decision is based upon and documented in the contents of the
Administrative .Record. The attached index identifies the items
which comprise the Administrative Record.

The Commonwealth of Pennsylvania concurs with the selected
remedy.

ASSESSMENT OF THE SITE

Pursuant to duly delegated authority, I hereby determine,
pursuant to Section 106 of CERCLA, 42 U.S.C. § 9606, that actual
or threatened releases of hazardous substances from this Site, as
specified in Section VI, smrnnaipy of site Risks, if not addressed
by implementing the response action selected in this Record of
Decision (ROD), may present an imminent and substantial
endangerment to the public health, welfare, or the environment.

DESCRIPTION OF THE SELECTED REMEDY

The remedial action plan in this document is presented as the
permanent remedy for controlling the ground water contamination
at the Site. This remedy comprises the following components:

1. Implementation of a combination clay and soil cap and
multilayer cap on approximately 14 acres of the upper
portion of the Site and approximately 4 acres of the
lower portion of the Site to reduce the infiltration of
water into the fill area, which in turn will reduce the
migration of contaminants from the fill into the
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aquifer of concern.

2. Upgrading the existing leachate collection and
treatment system to provide better treatment of
contaminated leachate and shallow ground water with the
long-term goal of returning the ground water to its
most beneficial use.

3. Providing additional protection by implementing
institutional controls and installing a security fence
around the lower portion of the Site in conjunction
with the new cap to restrict the use of the Site, to
prevent any possible direct human contact with
contaminants at the Site, and to protect the integrity
of the cap by preventing any intrusion which could
compromise the cap.

4. Monitoring ground water and implementing a Site
maintenance program.

STATUTORY DETERMINATIONS

Pursuant to duly delegated authority, I hereby determine that the
selected remedy is protective of human health and the
environment, complies with Federal and State requirements that
legally are applicable or relevant and appropriate to the
remedial action, and is cost-effective as required under Section
121(d) of CERCLA, 42 U.S.C. § 9621(d). With respect to the
principal threat at the Site, the contaminated ground water and
leachate, the remedy satisfies the statutory preference, as set
forth in Section 121(b) of CERCLA, 42 U.S.C. § 9621(b), for
remedial actions in which treatment that reduces toxicity,
mobility,or volume is a principal element. Finally it is
determined that this remedy utilizes permanent solutions and
alternative technologies to the maximum extent practicable.

Because this remedy will result in hazardous substances remaining
onsite above health-based levels, a review will be conducted
within five years after commencement of the remedial action to
ensure that human health and the environment continue to be
adequately protected by the remedy.
0 jj^t^-uc ( . /i
A^
Edwin B. Erickson ' Date
Regional Administrator
Region III
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RECORD OP DECISION
LINDANB DUMP SITE
DECISION SUMMARY

I. SITE NAME, LOCATION AMD DESCRIPTION
The Lindane Dump Site is located in Harrison Township near
Natrona, Pennsylvania, in the Allegheny River Valley (see Figure
1). Both Harrison Township and Natrona are located in Allegheny
County on the northwestern side of the Allegheny River. The Site
is located approximately at river mile 25, some 20 road miles
northeast of downtown Pittsburgh. Land surfaces in this area are
generally steeply sloping toward the Allegheny River.

The total Site area is approximately ±61.8 acres. The Site
can be described in terms of the upper project area and the lower
project area. These areas are delineated on Figure 2. Alsco
Community Park (designated as the upper project area) is a 14.3
acre recreational site owned and maintained by Harrison Township,
Pennsylvania. This park is situated upon an area which, was
formerly an industrial waste disposal site. Park facilities
include a tennis court, baseball fields, picnicking and parking
facilities. Residential areas are just north and east of the
park. Population for Harrison Township was 13,252 in 1980, with
a slight growth projected for 1990 (Allegheny County Department
of Planning). The property immediately to the south of the Park
(the lower project area) consists of approximately 47.5 acres,
and is owned by the Allegheny Ludlum Corporation. Between the
Site and the river is an industrialized area involving recycling
and steel manufacturing. From the 1850 until the mid-1980s,
portions of the 47.5 acre parcel of land (the lower project area)
were also used for waste disposal. The land use zoning in the
project area is a mix of residential, business, recreational,
manufacturing and special use. Figure 3 shows the area zoning
designations.

The majority of both the upper and lower areas have been
graded and form terraces in the hillside extending from the
residential areas, located north and northeast of the project
Site, down to Karns Road. However, steeply sloping areas exist
between the upper and lower project areas and along Karns Road in
the lower project area.

The Site stratigraphy from top to bottom consists of an
upper fill area made up of fill and waste materials mixed with
terrace gravel deposits, an upper alluvium deposit which is
intermixed with a series of thin coal seams, a layer of
sandstones, shale and clay which are underlain by more coal
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JPHOJECT SITE! .
LINDANE DUMP SITE
SOUMCSt »*n«*yi»••!• »*f ••« •! Tep»frc^nlc
»»« d»«i»t'» Survey, Itt7
PROJECT sire BOUNDARIES
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tilt lOPOOHA^MC MAP
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Sit*
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LINDANE DUMP SITE
Fiaum 3
ZONING IN VICINITY
OF PROJECT SITE
So
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deposits which were extensively mined during the 19th century and
finally, a semi-confined bedrock zone which contains a number
of discrete water bearing zones.

Ground water on the Site moves downward from the pop of the
fill area into the alluvium zone and further into the coal mine
and bedrock zones, while at the same time proceeding downgradient
toward the Allegheny River. The coal mine intercepts a portion
of the ground water flow and discharges at the base of the coal
outcrop near Karns Road in the alluvium. A cross-section of the
Site stratigraphy and ground water flow direction is shown on
Figure 4.

II. SITE HISTORY AND ENFORCEMENT ACTIVITIES

The history of waste disposal at the Site is summarized
below:

In 1850, Pennsylvania Salt Manufacturing Company (the name
was later changed to Pennsalt, then to Pennwalt and currently is
known as Elf Atochem), began to manufacture chemicals in Natrona.
The area beneath the Site was extensively mined for coal during
the latter part of the nineteenth century and the first half of
the twentieth century. Early topographic maps indicate that the
land surface at the Site was originally comprised of a steeply
sloping ravine which drained toward the Allegheny River.
Tailings from the mining operations and cinders (bottom ash) from
steam and electrical power generation at the plant were placed at
the Site from the mid-1800s through the early 1900s. Sulfuric
acid was one of the first chemicals to be produced at the
Pennsalt plant. This operation was discontinued prior to 1920.
The resultant cinder and slag from this operation were disposed
at the Site. Cryolite ore was also refined at the plant and ore
tailings were disposed at the Site.

Alumina from bauxite was also produced at the plant until
1940. The resultant red mud residual, a very fine-grained
material with a high iron content (30 to 60 percent Fe203), is
contained in the Site.

Between 1947 and 1959, various organic and inorganic
products were produced at the Pennwalt plant, including
hexachlorocyclohexane (technical BHC) which was produced at the
plant between 1947 and 1955. Also, for a one-year period during
this time interval, p,p'-dichloro-dipheny1-trichloroethane (DDT)
was produced at the plant (production ceased in the early 1950s).
BHC filter cake residuals containing lindane and waste sulfuric
acid containing DDT were disposed on the Site.

From 1959 to 1965, the Lindane Dump Site was not utilized.
No known filling operations occurred during this time period. In
1965, Pennwalt sold the property to Allegheny Ludlum. From the
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PROJKCT LIMITS
U
o
oo
D n
LOWER
UPPER PROJECT AREA
PROJECT

AREA
.|NI)AW. DUMP SITU

CHOI! HCIIO.
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mid-1960s to the mid-1980s, Allegheny Ludlum continued to use the
Site for disposal of wastes including construction wastes,
industrial waste treatment plant sludge, coke, rubber tires, and
slag.

During 1976 and 1977, the Alsco Community Park was
constructed on the 14.3 acre tract, by Harrison Township on the
upper Site area, which was donated to Harrison Township by
Allegheny Ludlum in 1972. Park construction included grading the
entire upper project area and placement of slag over portions of
the graded area. In addition, fill material (from an unknown
source) was placed and graded onto the areas of the present-day
tennis courts and ball diamond areas. The Park facilities also
include a sheltered picnic area and parking lot.

RESPONSE ACTIONS

In October 1981, the EPA proposed the Site on the National
Priorities List (NPL) under the provisions of the Comprehensive
Environmental Response, Compensation, and Liability Act (CERCLA).
The NPL listing was promulgated in September 1983. Between 1980
and 1985, several investigations, monitoring events, and interim
remedial measures were completed at the Site by the Pennwalt
Corporation.

In 1985, EPA and the Pennsylvania Department of
Environmental Resources (PADER) requested that further site
investigations be conducted. Pennwalt was invited and agreed to
implement the investigatory work. Specifically, EPA and PADER
requested that a Supplemental Remedial Investigation and
Feasibility Study (RI/FS) to supplement the previous remedial
investigations, which were done by Pennwalt independently, be
conducted for the Site, and that the results of all previous
studies and remediation efforts be combined with this new project
work in an RI/FS report.

In 1987, Pennwalt entered into a Consent Order (CO) with
PADER to conduct a Supplemental RI/FS for the project Site. The
CO also called for Pennwalt to comply with specified effluent
limits for the interim leachate collection/ treatment system,
which was installed in 1984. The Supplemental RI was completed
in January 1990. The FS Report was completed in March, 1992.

During the course of the RI/FS, EPA undertook an exhaustive
Potentially Responsible Parties ("PRP") investigation to
determine those parties which would be responsible under CERCLA
for undertaking the Remedial Design/Remedial Action ("RD/RA").
This investigation included reviewing documents in EPA, State and
local governmental agency files, interviewing former and current
employees of Pennsalt, Allegheny Ludlum and Harrison Township
Water Authority, sending and reviewing CERCLA 104(e) information
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request letters, reviewing title search documents and researching
corporate history and status. As of the issuance -date of this
ROD, EPA has identified several parties whom it believes to be
PRPs for the Lindane Dump Site. After issuance of this ROD, EPA
intends to issue Special Notice Letters to the parties currently
identified as PRPs to invite them to enter into negotiations with
EPA to conduct the RD/RA.
' o
III COMMUNITY RELATIONS SUMMARY

In accordance with Sections 113 and 117 (k) (2) (B) (i-v) of
CERCLA, 42 U.S.C. §§ 9613 and 9617, EPA, in conjunction with the
PADER, issued a Proposed Plan to present the preferred remedial
alternative. The Proposed Plan and the Supplemental RI and Draft
FS reports were made available to the public in the copies of the
administrative record maintained at the EPA Region III offices
and at the information repository listed below:

Harrison Township Municipal Building
Municipal Drive
Natrona Heights, Pennsylvania 15065

EPA held a public comment period from December 17, 1991 to
January 16, 1992 for the purpose of soliciting public
participation in the decision process. As part of the public
comment period, a public meeting was held on January 8, 1992 to
present information and to accept oral and written comments and
to answer questions from the public regarding the Site and
remedial alternatives. A transcript of the meeting was
maintained in accordance with Section 117(a)(2) of CERCLA, 42
U.S.C. § 9617(a)(2). Responses to the oral and written comments
received during the public comment period are included in the
attached Responsiveness Summary. This decision document presents
the selected remedial action for the Lindane Dump Site, in
Natrona, 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 upon the
Administrative Record

An announcement of the public meeting, the comment period,
and the availability of the RI/FS was published in the Valley
News Dispatch, on December 17, 1991.

All documents considered or relied upon in reaching the
remedy selection decisions contained in this Record of Decision
are included in the Administrative Record for the Site and can be
reviewed at the information repositories.

IV. SCOPE AND ROLE OF THIS REMEDIAL ACTION

There were no principal threats identified at this Site
based on the EPA criteria (Principal Threats are those source
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materials considered to be highly toxic or highly mobile that
generally cannot be contained or would present a significant risk
to human health or the environment should exposure occur). The
scope and role of this final remedial action is to address the
MCL exceedences and the threat at the Site, which is the
contaminated ground water and leachate.' The source materials
contained within the fill area are only considered to pose a low
level threat due to their low concentration. The purpose of the
cap is to further reduce the risk posed from incidental contact
with any contaminants contained within the soil and to also
reduce the migration of contaminants from the fill area into the
ground water which in turn will reduce or eliminate the MCL
violations in the ground water which now occur. A more detailed
discussion is contained at Section IX. The upgraded treatment
plant will result in the effluent meeting the new discharge
requirements of the Commonwealth of Pennsylvania.

V. SUMMARY OP SITE CHARACTERISTICS

A. Regional Climate

Data collected from the weather stations in Pittsburgh
provide the most complete data available for the Natrona Heights
area. The climate in this area is humid continental modified
slightly by the close proximity of the Atlantic Seaboard and the
Great Lakes. Precipitation is well distributed throughout the
year; during the winter months about one-fourth occurs as snow.
The first snowfall usually occurs in late November and the last
occurrence of snowfall is generally in early April. The annual
rainfall amount is approximately 36.30 inches per year. The
annual normal temperature for Pittsburgh region is 50.3 F.
Rainfall intensity is projected to be 0.97 inches for a one hour,
one year rainfall event and 5.13 inches for a 24 hour, 100 year
event.

B. surface Water Hvdrolocrv

Surface water bodies in the vicinity of the Site include the
Allegheny River and two tributaries, Bull Creek and Little Bull
Creek (See figure 5). The Allegheny River is the major surface
water stream in the Natrona, Pennsylvania area. The river
drainage basin upstream of Natrona (River Mile 24) encompasses
11,410 square miles River flow at Natrona is regulated by the
Allegheny Reservoir, Chautaugua and Tionista Lakes, Union City
Reservoir, Woodcock Creek, east branch Clarion River, Mahoning
Creek, Crooked Creek, Yellow Creek, Conemaugh River, Loyalhanna
Lakes, and fifteen smaller reservoirs. The average flow of the
Allegheny river at Natrona for 47 years of record is 19,580 cubic
feet per second (cfs). A maximum flow of 238,000 cfs was
recorded on december 30, 1942. A minimum flow on record is 895
cfs on October 22, 1963.
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r
HARRISON TOWNSHIP

SITE

JACKS ISLAND
LOCK A OAM NO. 4
(CUtrvUw W«t«r

NATRONA
-N-
FIOURE 5

SURFACE WATER MAP

ALLEGHENY COUNTY.
PENNSYLVANIA
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The Allegheny River provides the public drinking water
supply for Harrison Township as well as recreation and
transportation for the area. Harrison Township Water Authority
intakes an average of 1.8 million gallons of water per day from
the Allegheny River immediately upstream from Lock and Dam No. 4,
which approximately is 4000 feet downstream from the Site. Water
treatment consists of prechlorination, sedimentation with alum
and lime addition, filtration, fluoridation, and post
chlorination. An estimated population of 13,000 is served with
average water sales of 1.6 million gallons of water per day.

On Site Surface Water Drainage

The project Site can be divided into two areas: the Alsco
Community Park (upper portion) and the lower portion (owned by
Allegheny Ludlum). The majority of both areas have been leveled
to form terraces in the hillside extending from the residential
areas north and northeast of the project Site down to Karns Road.

In the upper portion of the Site, stormwater flows along
natural drainage swales and manmade ditches from the residential
areas to the north. The majority of the stormwater flow is
diverted around the terraced portion of the park and eventually
reaches a ditch along Spring Hill Road. The surface water runoff
from a portion of Spring Hill road is conveyed through a former
mine air shaft which transverses through a portion of the lower
project area and discharges into a man-made channel at Karns
Road. There is some runon over the flat areas of the park, part
of which probably infiltrates while the remainder runs off. In
the lower portion of the site, the majority of the stormwater
flows through natural drainage ditches and down the steep slopes
to Karns Road. Some stormwater may also run onto the terraced
portion of the lower project area and quickly infiltrates.

C. Geology

The project site is situated in the Freeport Quadrangle in
western Pennsylvania. Regionally, the geologic setting consists
entirely of sedimentary rocks of Devonian to Pennsylvanian age,
with unconsolidated alluvial deposits of Quaternary age bordering
the Allegheny River and its tributaries. The prevalent lithology
consists of shale and sandstone, with minor amounts of limestone,
clay, coal, and impure iron ore. General stratigraphic horizons
are fairly constant, but variability of the beds can be extreme
in localized instances.

The individual units in the quadrangle include, in ascending
order, the Portage group, the Chemung Group, and the Venango-
Catskill group, all of Devonian age; the Pocono Series of
Mississippian age; and the Pottsvilie Series, the Allegheny
Group, the Conemaugh Group, and limited outcrops of the
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Monongahela Group , all of Pennsylvania!) age. The Conemaugh
Group outcrops extensively. Quaternary alluvial deposits,
including fluvial and glaciofluvial terrace deposits and
unconsolidated alluvium, outline the major rivers and streams
that drain the area. The generalized geologic column for the
area is shown on figure 6.

The unconsolidated Quaternary deposits in the area are
identified either as recent alluvial deposits or as terrace
deposits of glacial or non-glacial origin. It consists mainly of
interbedded layers of sand, gravel, and clay in the stream beds
and silty loam in the flood plains and river flats. Igneous
pebbles can be found in the alluvium bordering the Allegheny
River; these were transported from reworked glacial deposits.
Terraces of fluvial origin can be found throughout the area, but
are not clearly differentiated from the present alluvium. Gravel
and sand are predominant in the terraces with local deposits of
silt and sand.

Terraces of glaciofluvial origin lie approximately 200 to
250 feet above the alluvia flats. These terraces originated
through the overloading of rivers and streams with glacial debris
and subsequent deposition during the Pleistocene Era of
glaciation. The glaciation covered the upper reaches of
Pennsylvania but did not reach the Freeport Quadrangle area.

Underlying these unconsolidated sediments is Paleozoic
bedrock ranging in age from Devonian to Pennsylvanian. The
uppermost Pennsylvanian age units are the outcrops of the
Monongahela group which are exposed only in the southeastern
corner of the quadrangle. This group is made up entirely of
sandstones and shales. The Conemaugh Group, the most extensively
outcropping unit throughout the quadrangle is composed almost
entirely of shales with numerous sandstone beds and limited coal
and clay layers. The rock in this unit underlies the project
site. The Allegheny Group, underlying the Conemaugh Group,
consists of shale, sandstone, limestone, and limited coal and
clay. This unit outcrops in the precipitous cliffs found along
major stream channels. The lowermost Pennsylvanian age unit is
the Pottsville series, represented by sandstones with shale and
conglometric interlayers. Each of the previous units is
differentiated regionally by marker beds of coal.

D. Hydrogeo1ooy

The two ground water aquifers in the vicinity of the project
Site are the stream channel alluvial deposits and the
consolidated bedrock units. These aquifers are both class 2
aquifers, suitable for drinking water supply. Ground water
occurs in the intergranular spaces in the alluvial deposits and
is generally under water table conditions. In the consolidated
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AGE
SERIES
GROUP
LOCAL NAMES

EHAUOH
AN
NNSYLV
CNY
ALLC
S
DEVONI
II
1
CONSISTS OF SANOSTONC
OTAOINO TO SHALE
CONSISTS Of SHALE AND
THIN SANDSTONE
OS
CONSISTS PRINCIPALLY
or SHALE
ALLUVIUM
BCNWOOO LIMESTONE
SCVMCKLEY SANOSTONC

REDSTONE COAL
PITTSBURGH SANDSTONE

PtTTSBURGH COAI
PITTSBURGH LIMESTONE

CONNELLSVILLE SANOSTON!
aAcxsauRo COAL AND
LIMESTONE
MORGANTOWN SANDSTONE
DUOUESNC COAL
AMES LIMESTONE
PITTSBURGH RED BEOS

r.sir-
STONE
BRUSH CREEK LIMESTONE
BRUSH CREEK COAL
MAHONINO COAL

MAHONINO SANDSTONE

UPPER FREEPORT COAL

BUTLER SANDSTONE
LOWER FREEPORT COAL
FREEPORT SANOSTONC
UPPER KITTANINO COAL

MOOLE KITTANINO COAL

LOWER KITTANINO COAL
KITTANINO SANDSTONE
VANPORT LIMESTONE
CLARION COAL
CLARION SANDSTONE
8ROOKVILLE COAL
PROM HUSHES, 1933 AND WAflNER H ol., I9TS
QINIRAUZtD RIOIONAL
QIOLOaC COLUMN PON
TNI NATNONA ANIA
20
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bedrock, the ground water is generally found in bedding planes,
joints, fractures and interstitial openings and nay be under
either water table or confined conditions. The majority of the
monitoring wells for this Site are contained within this unit.

The consolidated bedrock units are generally sandstones and
shales but there are thin limestone beds, clay beds, and coal
seams. The water-bearing properties of the consolidated bedrock
vary with lithology and structure. The Conemaugh Group, directly
overlying the Upper Freeport Coal is generally composed of
shales, sandy shales and sandstones and have low permeabilities
and yield little or no water at wells. Such ground water as
occurs within this group is contained within bedding planes,
joints, and interstitial openings. The Allegheny Group directly
underlying the Upper Freeport coal, has lithologic and
hydrogeologic characteristics similar to the Conemaugh Group.
There are no known wells in Harrison Township screened within
this unit. The observed low permeability and the expected
increase in salinity with depth of the Allegheny Group bedrock at
the Site indicates the poor aquifer characteristics of the
bedrock interval for water supply usage.

Bedrock in the Natrona area is affected by the Amity
Anticline which strikes northeast-southwest and dips to the
southeast. The Natrona area is located on the eastern limb of
this anticline. Faulting in the region is minimal. Numerous
evidences of fracturing and crushing of the lithology without
displacement have been discovered.

E. NATURE AND EXTENT OF CONTAMINATION

Site Characterization

The nature and extent of chemical contamination at the
Lindane Dump Site was characterized through extensive sampling of
surface and subsurface soils, ground water monitoring wells,
surface water, including leachate seeps, sediments, and air
monitoring on-site. In addition, sample data from residential
wells and the water intake for the Harrison Township water
Authority were also reviewed. Samples taken were analyzed for
U.S. EPA Target Compound List (TCL) and Target Analyte List (TAL)
constituents initially. For the organic analyses, this also
included searches for non-target compounds. In later sampling
rounds, the list of constituents tested for were reduced to those
which were previously detected or were suspected to be present.
The data, with required sampling and analysis procedures,
underwent a rigorous quality assurance review to ensure
compliance, validity, and usability of the results.

All analytical data obtained in the course of the remedial
investigation were compiled, sorted by environmental medium,
evaluated with respect to analytical qualifiers (including sample

8
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specific minimum quantification limits), analyzed statistically
to generate upper 95 percent confidence limits of 'the average
concentration of each chemical in each medium; and examined in
comparison to naturally occurring background levels in accordance
with U.S. EPA guidelines. Environmental media evaluated
individually include surface water, sediments, surface and
subsurface soils, water from seeps, and ground water. The
following summarizes the results of the investigation and lists
the various chemicals of concern which were identified during the
investigation of the various media.

Surficial Soil Contamination

o Exploratory trenching was conducted at several
locations in the lower project area to obtain
information on the horizontal and vertical variability
of fill. Compounds detected were BHC isomers,
including the isomer Gamma-BBC (Lindane), DDT, DDE,
DDD, and the inorganics; arsenic, cadmium, chromium,
copper, lead, mercury, nickel, selenium, silver, and
zinc.

o Exploratory borings drilled in the upper project area
detected isomers of BHC and 4,4'-DDT at varying depths
in each of the borings through the fill along with the
same inorganics that were identified in the lower
project area exploratory borings.

o Surficial soil samples were taken in the lower project
area. Samples were analyzed for phenols; benzene;
chlorobenzene; dichlorobenzene; 4,4'-DDT and its
metabolites; the BHC isomers and the inorganic
parameters arsenic, cadmium, chromium, copper, lead,
mercury, nickel, silver, and zinc. Each of these
constituents were discovered in one or more samples
with the exception of chlorobenzene, dichlorobenzene,
and gamma-BBC, which were not detected in any of the
surficial soil samples.

o Surficial soil samples were taken in the upper project
area including several locations along the perimeter of
the Park which defines the legal property boundary
between the Park and adjacent residential properties.
The following compounds were detected in one or more
samples taken during several sampling events; alpha
BHC, beta-BHC, delta-BHC, gamma-BHC, 4,4'-DDT, 4,4'-
DDE, 4,4'-ODD along with the inorganics; arsenic,
chromium, copper, lead, nickel, zinc, mercury, silver
and phenol.

A summary of contaminants detected in the soil samples and
their range of concentrations is shown in Tables 1 thru 8.
22
-------
A summary of contaminants detected in the soil samples and
their range of concentrations is shown in Tables 1 thru 8.

TABLE 1
SUMMARY OF 8URFICIAL SOIL AREAL COMPOSITES SAMPLE ANALYSES
UPPER PROJECT AREA FEBRUARY 1988
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Constituent
Frequency of
Detection
Range of Concentrations
Detected
(ug/kg)
Alpha BHC
Gamma BHC
Delta BHC
4,4'- DDT
6/15
3/15
3/15
7/15
5.86
8.45
6.33
24.4
- 342
- 52.8
- 46.3
- 73,800
TABLE 2
SUMMARY OF SURFICIAL SOIL ZONE COMPOSITES SAMPLE ANALYSES
UPPER PROJECT AREA FEBRUARY 1988
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Constituent
Frequency of
Detection
Range of Concentrations
Detected
(ug/kg)
Aldrin
Alpha BHC
Beta BHC
Delta BHC
Gamma BHC
4,4'- DDT
4,4'- DDE
4,4'- ODD
Phenol
Arsenic
Chromium
Copper
Lead
Mercury
Nickel
Silver
Zinc
1/6
4/6
6/6
1/6
0/6
5/6
4/6
1/6
1/6
6/6
6/6
6/-6
6/6
1/6
6/6
1/6
6/6
46.1
15.6 - 57.4
64.2 - 1,200
11.1

72 - 24,200
21.8 - 335
423

(mg/kg)

6.1
22.4 - 32.7
9.4 - 173
31.2 - 114
92.3 - 558
.4
15.1 - 434
1.1
121 - 490
10
23
-------
TABLE 3
SUMMARY OF CONSTITUENTS DETECTED IN EXPLORATORY TRENCH COMPOSITES
MARCH 1988
AL8CO COMMUNITY PARK SITE
KATROKA, PENNSYLVANIA
Constituent*
Volatile Organic Compounds
Acrolein
Benzene
ChJorobenzene
Chloroform
Ethyibenzene
Methylene Chloride
1 ,2-Dichlorobenzene
1 ,4-Dichlorobenzene
Pesticide/PCB Compounds
Aldrin
Arodor-1242 (PCB)
Aroclor-1254 (PCB)
Alpha-BHC
Beta-BHC
Delta-BHC
Gamma-BHC
4,4'-DDT '
4,4'-DDE
4,4'-DDD
Endrin
Base Neutral Compounds
Anthracene
Benzo (a) anthracene
Benzo(a)pyrene
Benzo (ghi)perylene
Benzo (k)fluoranthene
Bis(2-ethylhexyl)phthalate
Chrysene
2,4-Dinitrotoluene
Fluoranthene
' Fluorene
Indeno(l,2,3-cd)pyrene
Napthalene
Phenanthrene
Pyrene
Frequency of
Detection

8/10
1/10
2/10
1/10
2/10
8/10
2/10
2/10

3/10
1/10
1/10
8/10
6/10
5/10
6/10
10/10
9/10
5/10
1/10

2/10
1/10
1/10
1/10
1/10
5/10
1/10
2/10
1/10
1/10
1/10
1/10
1/10
2/10
Range of Concentrations
Detected
(mg/kg)

10.1 - 23.2
0.2
0.3 - 2.4
0.4
2.8 - 5.5
0.1 - 0.3
0.3 - 0.4
0.4 - 0.8

0.6 - 2.4
11.8
4.2
1.3-409
0.2 - 82.7
0.1 - 33.3
0.2 - 165
0.1 • 8,520
0.2-680
1.4 - 82.5
5.6

16.0 - 66.6
33.3
76.7
17.2
66.6
10.4 - 30.5
22.4
10.7 - 66.7
63.3
11.3
66.7
10
17.2
10.7 - 50
24
11
-------
TABLES (Continued)
SUMMARY OF CONSTITUENTS DETECTED IN EXPLORATORY TRENCH COMPOSITES
ALSO) COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Constituent5
Frequency of
Detection
Range of
Concentrations
Detected (mg/kg)
Wet Chemistry and
Inorganics
Cyanide 2/10
Phenol 3/10
As 10/10
Cd 8/10
Cr 10/10
Cu 10/10
Pb 10/10
Hg 10/10
Ni 10/10
Se 6/10
Ag 8/10
Zn 10/10
1.9- 3.7
4.3 - 31.2
17.4 - 32.1
1.1 - 9.9
242.0 - 4,960
108.0 - 826
147.0 - 4,880
0.3 - 5.8
264.0 - 4,220
0.7 - 3.2
1.3 - 28.8
313.0 - 3,230
"Composites are representative of the proportions of each of various materials encountered in the
trenches.

bA complete propriety pollutant scan was conducted; only
constituents detected are reported.

TABLE 4
SUMMARY OF EXPLORATORY TRENCH SAMPLE ANALYSES
FIVE-FOOT INTERVAL COMPOSITES
MARCH 1988
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Constituent
Frequency of
Detection
Range of Concentrations
Detected
(ug/kg)
Alpha BHC
Gamma BHC
Delta BHC
4,4'- DDT
26/36
24/36
16/36
36/36
18.0
6.8
12.2
37.9
- 2,240,000
- 291,000
- 108,000
- 5,820,000
12
25
-------
TABLE 5
SUMMARY OF SURFICIAL SOIL SUPPLEMENTAL DISCRETE SAMPLE ANALYSES
UPPER PROJECT AREA
MAY 1988
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Frequency of Range of Concentrations
Constituent Detection Detected
(ug/kg)

Alpha BHC 8/9 9.6 - 4,240
Gamma BHC 9/9 6.0 - 39.7
Delta BHC 6/9 10.2 - 127
4,4'- DDT 9/9 61.3 - 5,680
TABLE 6
SUMMARY OF EXPLORATORY BORING SAMPLE ANALYSES*
DECEMBER 1988
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Frequency of Range of Concentrations
Constituent Detection Detected
(ug/kg)
Alpha BHC
Gamma BHC
Delta BHC
4,4'- DDT
Arsenic
Lead
Chromium
30/37
23/37
24/37
24/37
36/37
32/37
36/37
8.0 - 517,000
10.2 - 206,000
20.4 - 296,000
12.2 - 236,000
1.2 - 145
15.3 - 7,600
4.8 - 2,730
Zinc 37/37 5.9 - 11,900

a Exploratory borings were also analyzed for volatile organic
compounds; none were detected.
13
26
-------
TABLE 7
SUMMARY OF ADDITIONAL DISCRETE 8URFICIAL SOIL SAMPLE ANALYSES
UPPER PROJECT AREA DECEMBER 1989
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Constituent
Frequency of
Detection
Range of Concentrations
Detected
(ug/kg)
Alpha
Beta
Delta
Gamma
4,4'-
4,4'-
4,4'-
BHC
BHC
BHC
BHC
DDT
DDD
DDE
4/11
9/11
3/11
3/11
7/11
2/11
5/11
15.4
10.1
8.4
17.7
22.9
474
23.6
-
-
-
-
-
-
^*
466
1,320
106
149
13,500
3,620
1,930
TABLE 8
SUMMARY OF SURFICIAL SOIL SAMPLE ANALYSES
LOWER PROJECT AREA JULY 1990
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Constituent
Frequency of
Detection
Phenolics

Arsenic
Cadmium
Chromium
Copper

Lead
Mercury
Nickel
Silver
Zinc
2/16

14/16
16/16
16/16
16/16

16/16
9/16
16/16
16/16
16/16
Range of Concentrations
Detected
(ug/kg)
Benzene
Chlorobenzene
1 , 2-Dichlorobenzene
l, 3-Dichlorobenzene
1 , 4-Dichlorobenzene
4,4'- DDD
4,4'- DDE
4,4'- DDT
Alpha BHC
Beta BHC
Delta BHC
Gamma BHC
10/16
0/16
0/16
0/16
0/16
9/16
16/16
15/16
3/16
7/16
1/16
0/16
249

117
34.2
103
16.6
49.4
81

- 623
-
-
-
-
- 2,260
- 4,580
- 17,400
- 25.4
- 227
'.1
-
(mg/kg)
2.84 - 3.95
1.22
0.46
182
166

128
0.28
171
0.70
244
36.7
26.2
1,380
707

1220
1.51
11,800
4.73
3,680
14
27
-------
Surface Water and Sediment Contamination
o Sediment samples, collected from drainage ditches in
the upper project area, during the RI detected alpha-
BHC, .delta-BHC, gamma-BHC and 4,4'-DDT in one or more
of the ditch samples.

o River and sediment samples were taken from the
Allegheny River. None of the constituents of concern
were found in the water samples except delta-BHC which
was found in one sample taken from just downstream of
the interim leachate collection/treatment plant
discharge. Sediment samples taken from the river
detected alpha-BHC, beta-BHC, delta-BHC, gamma-BHC,
4,4'-DDT, 4,4'-ODD and 4,4'-DDE. In addition, the
inorganics; arsenic, cadmium, chromium, copper, lead,
mercury, nickel, silver and zinc were detected .

o Storm runoff samples were collected from six locations
in the upper project area and analyzed. Only alpha-BHC
and gamma-BHC were present above detection limits.

o Water intake sample data from the Harrison Township
Water Authority was reviewed as a part of the
investigation. The samples taken from a water intake
downstream of the Site were analyzed for both organic
and inorganic parameters. None of the samples exceeded
the corresponding Safe Drinking Water Maximum
Contaminant Level (MCL) with the exception of mercury
on one occasion.

A summary of contaminants detected in the surface water,
sediments and stormwater runoff and their range of concentrations
is shown in Tables 9 thru 12.

TABLE 9
SUMMARY OF STORMWATER RUNOFF SAMPLE ANALYSES
SEPTEMBER 1982
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA

Frequency ofRange of Concentrations
Constituent Detection Detected
(ug/kg)

Alpha BHC 5/6 0.15 - 124
Beta BHC 0/6
Delta BHC 0/6 -
Gamma BHC 5/6 0.14 - 11.4
DDT 0/6
Benzene 0/6
Chlorobenzene 0/6
Dichlorobenzene 0/6 -
Trichlorobenzene 0/6
15
28
-------
TABLE 10
SUMMARY OF DRAINAGE DITCH SEDIMENT SAMPLE ANALYSES
FEBRUARY 1988
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Constituent
Frequency of
Detection
Range of Concentrations
Detected
(ug/kg)
Alpha
Gamma
Delta
4.4'-
BHC
BHC
BHC
DDT
1/5
1/5
2/5
2/5
307
361
110 - 627
1420 - 1680
TABLE 11
SUMMARY OF ALLEGHENY RIVER SEDIMENT SAMPLE ANALYSES
MAY 1988
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Constituent
Frequency of
Detection
Inorganics
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Silver
Zinc
6/6
1/6
6/6
6/6
4/6
1/6
6/6
2/6
6/6
Range of Concentrations
Detected
(ug/kg)
Organics
Alpha BHC
Gamma BHC
Delta BHC
4,4'- DDT
4,4'- ODD
4,4'- DDE
Benzene
Chlorobenzene
l , 2 -Dichlorobenzene
1,3 -Dichlorobenzene
l , 4 -Dichlorobenzene
Trichlorobenzene
Te t r ach 1 or oben z ene
Pent ach lor ocyc lohexane
Tr i ch 1 or opheno 1
Phenolics

3/6
3/6
2/6
2/6
1/6
1/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6
0/6

5.3 - 15.6
4.1 - 13.6
9.6 - 10.0
8.0 - 241
8.3
82.0
—
-
-
-
-
-
-
-
-
-
mg/kg
4.4 - 11.3
1.6
15.7 - 49.1
22.2 - 206
15.5 - 710
.54
18.7 - 69.8
.72 - 2.4
94 - 398
16
29
-------
TABLE 12
SUMMARY OF ALLEGHENY RIVER WATER SAMPLE ANALYSES
MAY 1988
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Constituent
Frequency of
Detection
Range of Concentrations
Detected
(ug/1)
Alpha BHC
Gamma BHC
Delta BHC
Benzene
Chlorobenzene
1,2-Dichlorobenzene
1,3-Dichlorobenzene
1,4-Dichlorobenzene
0/3
0/3
1/3
0/3
0/3
0/3
0/3
0/3
.14
Ground Water Contamination

o Ground water samples were taken from selected shallow
water table, and upper bedrock wells and seeps located
downgradient of the Site. The samples contained alpha-
BHC, beta-BHC, delta-BHC, gamma-BBC, 4,4'-DDT, benzene,
Chlorobenzene and dichlorobenzene. In addition, low
levels of chromium, nickel, zinc and phenol were also
detected.

A summary of contaminants detected and their range of
concentrations found in the ground water and seep samples is
shown in Tables 13 - 18. Figure 7 shows the locations of the
monitoring wells sampled during the Remedial Investigation.
30
17
-------
I i
o o
,-;> -i
•*••=•
r 1
UJ
S^r£tfSEE&>-
v%*x ^^te%,.
^^?^SSK^
~\..>.,-:* .--•» v***'-»M?*jSLy>'**
•v lA . ».VV>»*3*3^.*.-
«-o^;^i^ffi^bji:^^._^ . -

ite^J5-'^^y^ip3^^'i;-"
rf^l:- ;fii ;:. -::''>. KM!
--- • /:•*•.,'. ^••-^ 'W-M
.* « •- • «. "l - * J — -
LEGEND
MNDANE DUMP SITK
Mt-f
FIGURE 7

MOMTOMNO WEU. AMD

SttP LOCATIONS
-------
TABLE 13
SEEP CONFLUENCE 1982 PRIORITY POLLUTANT ANALYSIS
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Detection
Limit
Confluence
Concentrat ionsa
Zinc
Nickel
Chromium
Phenol
10
50
20
50
ug/1
ug/1
ug/1
ug/1
140
90
48
220
ug/1
ug/1
ug/1
ug/1
Cyanide
Copper
Thallium
Beryllium
Cadmium
Antimony
Lead
Mercury
Selenium
Silver
Arsenic

Volatile Orcranics

Benzene
Chlorobenzene
Methylene Chloride
All others
0.02 mg/1
0.02 mg/1
0.06 mg/1
0.01 mg/1
0.01 mg/1
0.10 mg/1
0.06 mg/1
0.001 mg/1
0.01 mg/1
0.01 mg/1
0.03 mg/1
100 ug/1
100 ug/1
100 ug/1
Acid Extractables

Base-Neutral Extractables

1,2-Dichlorobenzene
l,4-Dichlorobenzene
1,2,4-Trichlorobenzene
All Others

Pesticides

BHC-Alpha
BHC-Beta
BHC-Gamma
BHC-Delta
All Others
10 ug/1
10 ug/1
10 ug/1
10 ug/1
10 ug/1
10 ug/1
10 ug/1
BDLD
20 ug/1
BOL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
BDL
800 ug/1
410 ug/1
200 ug/1
BDL

All BDL
46 ug/1
60 ug/1
120 ug/l
BDL
150 ug/1
23 ug/1
390 ug/1
350 ug/i
BDL
aAnalysis of samples taken 4/7/82.
Confluence included all seeps except #1.

bBDL: Below Detection Limit.
32
18
-------
TABLE 14
SUMMARY OF SEEP CONFLUENCE, AND SEEP SAMPLE ANALYSES
APRIL 1982 TO MAT 1982
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Frequency of Range of Concentrations
Constituent Detection Detected
(ug/1)

Metals

Chromium 0/6 % -
Nickel 2/6 116 - 422
Zinc 6/6 14 - 863

Organics

Alpha BHC 8/13 0.33 - 378
Beta BHC 0/13
Gamma BHC 7/13 0.87 - 781
Delta BHC 7/13 0.064 - 942
DDT 0/13
Benzene 2/14 270 - 1,320
Chlorobenzene 2/14 400 - 429
Dichlorobenzene 2/14 143-148
Trichlorobenzene 0/13
Methylene Chloride 0/6
19
33
-------
TABLE 15
SUMMARY OF GROUND WATER SAMPLE ANALYSES FOR MONITORING WELLS
PN-7 AND PN-8
APRIL 1982 TO MAY 1982
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Constituent
Frequency of
Detection
Range of Concentrations
Detected
(ug/1)
Metals

Chromium
Nickel
Zinc

Organics

Alpha BHC
Beta BHC
Gamma BHC
Delta BHC
DDT
Benzene
Chlorobenzene
Dichlorobenzene
Trichlorobenzene
Methylene Chloride
0/6
1/6
6/6
5/6
0/6
5/6
5/6
0/6
0/6
2/6
0/6
0/6
0/2
70
47 - 185
0.062 -2.26

0.048 - 1.6
0.100 - 2.4
18 - 19
34
20
-------
TABLE 16
SUMMARY OF GROUND WATER SAMPLE ANALYSES FOR MONITORING WELLS
PN-1, PN-2, PN-3, PN-4, PN-5, AND PN-6
APRIL 1982 TO MAY 1982
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Constituent
Frequency of
Detection
Range of Concentrations
Detected
(ug/1)
Metals

Chromium
Nickel
Zinc

Organics

Alpha BHC
Beta BHC
Gamma BHC
Delta BHC
DDT
Benzene
Chlorobenzene
Dichlorobenzene
Trichlorobenzene
Methylene Chloride
2/17
5/17
15/17
9/17
0/17
8/17
11/17
0/17
7/16
8/17
1/17
3/17
0/4
20
81 - 230
16 - 11,600
0.028 - 338

1.6 - 373
0.044 - 1,545

980 - 17,100
2.6 - 3,630
723
196 - 515
21
35
-------
TABLE 17
SUMMARY OF GROUND WATER SAMPLE ANALYSES FOR MONITORING WELLS
PN-1, PN-2, PN-3, PN-7, PN-8, AND SEEP CONFLUENCE
1984-1985
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA
Range of Concentrations
Constituent Detected
(ug/1)
Alpha BHC 0.034 - 343
Beta BHC BDLa - 0.6
Gamma BHC 0.064 - 873
Delta BHC 0.078 - 1,690
Benzene BDL - 1,780
Chlorobenzene BDL - 420
Dichlorobenzene BDL - 515
a Below Detection Limit

TABLE 18
SUMMARY OF MONITORING WELL AND SEEP SAMPLE ANALYSES
FEBRUARY 1988 TO FEBRUARY 1989
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA

Frequency ofRange of Concentrations
Constituent Detection Detected
(ug/1)
Alpha BHC
Gamma BHC
Delta BHC
4,4'- DDT
Benzene
Chlorobenzene
1 , 2-Dichlorobenzene
1 , 3 -Dichlorobenzene
1 , 4 -Dichlorobenzene
15/28
14/28
16/28
1/21
9/29
8/29
1/29
0/29
2/29
0.08 - 1,240
0.05 - 1,150
0.06 - 4,220
2.02
1.1 - 10,800
3.9 - 1,920
331
-
4.2 - 763
Air Contamination

o Air quality monitoring in the upper project area was
undertaken and only alpha-BHC was detected above
detection limits in one sample.

Contamination Migration Paths

Based on the information developed during the Remedial
Investigation, it can be stated that the only significant pathway
for the movement of the contaminants is the migration of the

22
36
-------
contaminants from subsurface soils and the fill area into the
shallow ground water in the alluvial layer below the site. In
addition, a small portion of the contaminants are migrating below
the shallow aquifer and reaching the deeper aquifer, located in
the bedrock zone.

Estimated Contaminant Quantity

Based on an analysis of historical photographs of the site,
it was estimated that approximately 1.2 million cubic yards of
fill material were placed at the Site over the period of record.
Based on the analysis, it is estimated that of the 1.2 million
cubic yards of fill, approximately 40 percent of the fill
is composed of red mud and/or red cinder from the cryolite ore
processing. The remaining 60 percent is believed to be made up
of unoxidized ore tailings, slag, construction debris, gravel and
terrace deposits from the hillside north of the lower project
area. There was insufficient information available from the
historical records to determine the actual quantities of other
wastes such as Lindane or DDT that have been deposited at the
Site and mixed in with the other fill materials.
VI. SUMMARY OP SITE RISKS

A. Human Health Effects of Site Contamination

As part of the Remedial Investigation performed for the
Lindane Dump Site, a risk assessment was conducted to evaluate
the potential impacts of the Site on human health and the
environment. In the risk assessment, a set of chemicals of
potential concern were selected for detailed evaluation based on
the RI sampling results. Contaminants of concern were selected
separately for four environmental media; ground water, surface
water, sediments and soil.

The risk assessment then evaluated the potential human
health risks associated with exposure to these chemicals of
concern for each media.

Exposure Analysis

Exposure pathways considered for the purpose of evaluating
site risks include: (1) incidental ingestion and dermal
absorption from direct contact with contaminated surface soils,
surface waters and sediments; (2) future consumption of
contaminated ground water which may be utilized as a potable
supply; and (3) incidental ingestion of seep waters emanating at
the base of the Site. Other potential pathways of exposure such
as inhalation of dust and .uptake of contaminants into garden
vegetables were judged to be insignificant relative to exposure
resulting from direct contact with contaminated soils or not
applicable as soils tested in residential yards were found to
only have low levels of contaminants which would not pose a
threat to human health at any time period.

The next step in the exposure analysis process involved
quantification of the magnitude, frequency and duration of

23
37
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exposure for the populations, and exposure pathways selected for
evaluation. Generally, exposure point concentrations of
chemicals of concern were based upon the 95 percent upper
confidence limit of the average, so as to produce an estimate of
reasonable maximum exposure. A summary of the upper 95 percent
confidence limit average for the various contaminants is shown in
Tables 19A and 19B. Intake factors (e.g., amount of soil
ingestion, rate of dermal contact, exposure frequency, and
duration) were selected in accordance with EPA risk assessment
guidance so that the combination of all variables conservatively
results in the maximum exposure that can reasonably expected to
occur at the site.
38
24
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TABLE 19A
SUMMARY OF WATER CONCENTRATIONS
OF CONSTITUENTS OF INTEREST
(UPPER 95TH PERCENT VALUES)
TO WHICH CURRENT AND FUTURE POPULATIONS
MAY BE EXPOSED VTA INCIDENTAL INGBSTION
Recreational, Recreational,
Lower Project Area Seeps Allegheny River
Constituent (Current and Future)* (Current and Future)'
Benzene
alpha-BHC
beta-BHC
delta-BHC
gamma-BHC
Chloro benzene
4,4'-DDD
4,4'-DDE
4,4'-DDT
1 ,2-Dichloro benzene
1 ,4-Dichlorobenzene
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Phenol
Silver
Zinc
0.002
0.005
NAd
0.024
0.012
0.005
NA
NA
ND
ND
0.001
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
ND<
ND
NA
0.00014
ND
ND
NA
NA
NA
ND
ND
ND
ND
ND
NA
ND
0.0001
NA
NA
ND
NA
'All values in mg/1.
bAssumed contract with seep water in lower project area by children only.

'Assumed contact with River water while swimming.
Organic results from May 1988 sampling. Inorganic results from 1989 sampling of finished water at HTWA.
'ND = Analyzed, but not detected. NA =»= Not analyzed in most recent sampling programs.
25
39
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TABLE 19B
SUMMARY OP SOD. AND SEDIMENT CONCENTRATIONS
Of CONSTITUENTS OF INTEREST
(UPPER 95TH FE8OEHT VALUES)
TO WHICH CURRENT AND FUTURE POPUIAnONS
MAY BE EXPOSED VIA INCIDENTAL FNGESTOW
Constituent
Benzene
alpha-BHC
beta-BHC
deita-BHC
gamma-BHC
Chloro benzene
4,4'-DDD
4,4'-DDE
4,4'-DDT
1 ,2-Dichlorobenzene
1 ,4-Dichlorobenzene
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
Nickel
Phenol
Silver
Zinc
Recreational/
Residential,
Upper Area
(Current and
Future1"
Ntf
0.281
0.313
0.025
0.021
ND
0.452
0.378
7.25
ND
ND
29.9
ND
105
87.4
330
0.30
240
4.31
0.65
392
Occupational,
Upper Area
(Current and '•
Future)*
ND
0.281
0.313
0.025
0.021
ND
0.452
0.378
7.25
ND
ND
29.9
ND
105
87.4
330
0.30
240
4.31
0.65
392
Occupational,
Upper Area
(Future only)'
ND*
1.08
0.313f
0.103
0.066
ND*
0.4521
0.378*
19.9
ND»
ND<
44.5
ND<
984
87.4'
1,713
0.30*
240*
4.31'
0.65f
1,949
Recreations!,
Lower Area
(Current and
Future)6
0.339
0.013
0.084
0.030
ND
ND
0592
1.13
4.06
ND
ND
20.3
8.67
771
390
512
0.77
3,597
3.17
2.64
1,465
Occupational,
Allegheny
River Sediment
(Current and
Future)d
ND
0.007
NA«
0.009
0.010
ND
0.005
0.043
0.10S
ND
ND
13.6
0.67
58.6
146
397
0.37
138
ND
0.57
346
aAlf values in mg/kg. All concentrations and exposure scenarios were assumed to be the same for current and future populations, except as noted.

bAssumed contact with surficial soils only.

cAssumed contact with surficial and subsoils up to 6 ft (collectively) only.
Constituents found common to both surficial and subsoils reported, except as noted.

dAssumed contact with River Sediments.

'ND = Analyzed for but not detected. NA = Not analyzed in most recent sampling programs.

'Constituent not measured in borings, therefore, surficial soil concentrations only were Mmmxi
Toxicitv and Risk Characterization

Projected intakes for each risk scenario and each chemical
were then compared to acceptable intake levels for carcinogenic
and non-carcinogenic effects. With respect to projected intake
levels for non-carcinogenic compounds a comparison was made to
risk reference doses (RfDs). RfDs have been developed by EPA for
chronic (e.g. lifetime) and/or subchronic (less than lifetime)
exposure to chemicals based on an estimate that is likely to be
without an appreciable risk of deleterious effects. The chronic
RfD for a chemical is an estimate of an acceptable lifetime daily

26
40
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exposure level for the human population, including sensitive
subpopulations, without an appreciable risk of deleterious
effects. The potential for non-cancer health effects is
evaluated by comparing an exposure level over a specified time
period with the RfD derived by the EPA for a similar exposure
period. This ratio of exposure is called the hazard quotient.

The non-cancer hazard quotient assumes that there is a
threshold level of exposure (i.e. RfD) below which it is unlikely
for even the most sensitive populations to experience adverse
health effects. If the exposure level exceeds the threshold,
(i.e., the hazard quotient exceeds a value greater than 1.0)
there may be concern for potential non-cancer health effects.
The more the value of the hazard quotient or hazard index exceeds
one, the greater the level of concern for potential health
impacts.

To assess the overall potential for non-cancer effects posed
by multiple chemicals, a hazard index (HI) is derived by summing
the individual hazard quotients. This approach assumes
additivity of critical effects of multiple chemicals. This is
appropriate for compounds that induce the same effect by the same
mechanism of action. EPA considers any Hazard Index exceeding
one to be an unacceptable risk to human health.

For carcinogens, risks are estimated as the incremental
probability of an individual developing cancer over a lifetime as
a result of exposure to a potential human carcinogen. The EPA's
Carcinogen Assessment Group has developed carcinogen potency
factors (CPFs) for suspected and known human carcinogens which
are used to convert daily intake averaged over a lifetime of
exposure directly to incremental risk. The CPF is generally
expressed in units of risk per milligram chemical per kilogram
body weight per day of exposure (i.e., risk units per mg/kg/day).
The CPF or slope factor is the upper 95th percentile confidence
limit of the extrapolation (slope) from high-dosed animal data to
very much lower doses in humans. The use of the upper limit
produces a risk estimate that has a 95 percent probability of
exceeding the actual risk, which may actually be zero. For
exposure to multiple carcinogens the upper limits of cancer risk
are summed to derive a total cancer risk. Cancer risks beyond
the generally acceptable risk range of 1 X 10~4 to 1 X 10~* (i.e.
a l.o X 10"6 level indicates one additional chance in 1,000,000
that an individual will develop cancer) are considered an
unacceptable risk to human health.

The following summarizes the risk evaluation for the
ingestion pathways that were done. It was determined that the
ingestion pathway was the only pathway where significant exposure
could occur. Dermal contact and inhalation are not considered
significant pathways for exposure given the Site conditions.
These tables show, for each media, population targeted, and land
use, the chemicals of concern (chemicals which posed a increased
cancer risk of 10~6 or greater or an individual hazard index
greater than 1), their upper 95th percentile confidence limit of
their average concentration, the base risk posed by the chemicals
of concern, a clean-up level (based on a health-based standard)
and the residual risk level remaining after attaining that clean-

27
41
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up level.

Media/Population/Land Use: Upper Area Surficial Soils/ Adults/
Future Recreational-Residential

Concentration in Base Risk/ Clean-up Clean-up Risk/
Chemical Units/Basis* HZ Level HZ
mg/kg

Arsenic RME/29.9 3.9 X 10'6 N/A1 N/A2

a/ RME = 95% CI of the mean unknown.
I/ No clean level exists for this contaminant in soils.
2/ No clean-up level residual risk determined as no clean-up
level designated.
Media/Population/Land Use: Upper Area Surficial Soils
Adults/Future Occupational

concentration in Base Risk/ Clean-up Clean-up Risk/
Chemical Units/Basis* HZ Level HZ
mg/kg

Arsenic RME/44.5 2.1 X 10"6 N/A1 N/A2
a/ RME = 95% CI of the mean unknown.
I/ No clean level exists for this contaminant in soils.
2/ No clean-up level residual risk determined as no clean-up
level designated.
Media/Population/Land Use: Lower Area Surficial Soils
Adults/Future Recreational

Concentration in Base Risk/ Clean-up Clean-up Risk/
Chemical Units/Basis* HZ Level HZ
mg/kg mg/kg

Arsenic RME/20.3 1.9 X 10~6 N/A1 N/A2
Lead RME/390 1.1 X 10'6 500 N/A3

a/ RME = 95% CI of the mean unknown.
I/ No clean level exists for this contaminant in soils.
21 No clean-up level residual risk determined as no clean-up
level designated.
3/ No clean-up residual risk determined as the RME is less than
the clean-up level.
28
42
-------
Media/Population/Land Use: Allegheny River Sediments/
Adults/Future Occupational
Concentration in Base Risk/ Clean-up • Clean-up Risk/
Chemical Units/Basis' HZ Level HZ
mg/kg

Arsenic RME/13.6 8.0 X 10"6 N/A1 N/A2
Lead RME/397 5.2 X 10"6 N/A1 N/A2

a/ RME = 95% CI of the mean unknown.
l/ No clean level exists for this contaminant in sediments.
2/ No clean-up level residual risk determined as no clean-up
level designated.
Media/Population/Land Use: Allegheny River Water/
Adult/Future Recreational

Concentration in Base Risk/ Clean-up Clean-up Risk/
Chemical Units/Basis* HZ Level HZ
mg/1
I/ No chemicals of concern exceeded a cancer risk of 10~° or a
hazard index greater than 1.
Media/Population/Land Use: Upper Area Surficial-Subsoils/
Adults/Future Occupational
Concentration in Base Risk/ Clean-up Clean-up Risk/
Chemical Units/Basis* HZ Level HZ
mg/kg
I/ No chemicals of concern exceeded a cancer risk of 10~6 or a
hazard index greater than 1.
29
43
-------
Media/Population/Land Use: Upper Area Surficial Soils/
Children/Future Recreational-Residential
Concentration in Base Risk/ Clean-up • Clean-up Risk/
Chemical Units/Basis' HZ Level HZ
mg/kg
Alpha BHC
Arsenic
RME/.281
RME/29.9
,-6
1.08 X 10
3.20 X 10'5
N/A1
N/A1
N/A2
N/A2
a/ RME = 95% CI of the mean unknown.
I/ No clean level exists for this contaminant in soils.
21 No clean-up level residual risk determined as no clean-up
level designated.
Media/Population/Land Use: Lower Area Seep Water/
Children/Future Recreational
Concentration in Base Risk/ Clean-up Clean-up Risk/
Chemical Units/Basis' HZ Level HZ
mg/1 ug/1

Gamma-BHC RME/. 012 2.41 X 10'5 .21 N/A2
Alpha-BHC RME/. 005 4.86 x 10"5 - N/A2

a/ RME = 95% CI of the mean unknown.
I/ MCL
2/ No clean-up level designated as the cancer risk does not
exceed 10~4.

Media/Population/Land Use: Allegheny River Water/
Children/Future Recreational

Concentration in Base Risk/ Clean-up Clean-up Risk/
Chemical Units/Basis* HZ Level HZ
mg/1

I/ No chemicals of concern exceeded a cancer risk of 10~6.
44
30
-------
Media/Population/Land Use: Ground Water/
Adults/Future Occupational
Concentration in Basa Risk/ Clean-up • clean-up Risk/
Chemical Units/Basis" HI Leval HZ
mg/1
Alpha-BHC
Gamma-BHC
RME/. 00151 5.3 X 10'6 N,
RME/. 00195 8.8 X 10'6 .1
fA1 N/A2
23 N/A2
a/ RME = 95% CI of the mean unknown.
I/ No clean-up level exists for this contaminant in water.
2/ No clean-up level designated as the cancer risk does not
exceed 10~4.
3/ MCL

The risks posed by the Lindane Dump come from potential
exposure to contaminated soils, ground water, and leachate from
the seeps via ingestion. The total risks from each media are
discussed in the following paragraphs. All risks numbers
discussed below include the cumulative risk from all
contaminants, (even those with an associated increased cancer
risk less than 10~6 or hazard index less than 1), which were
found in each media

Surficial Soil Risks

The increased risk for cancer for an adult exposed to
surficial soils or subsoils by ingestion under current and future
conditions, ranged from 6 X 10~7 to 4 X 10~6. For a child, under
the same exposure scenarios the increased risk ranged from 2 X
10"5 to 4 X 10~5. For adults, the hazard index ranged from 0.008
to 0.1. For children, the hazard index was 0.2.

Surface Water and Sediment Risks

The increased risk for cancer for an adult exposed to river
sediments by ingestion under current and future conditions is 8 X
10~6. The hazard index is 0.03, the same for both the current
and future exposure scenarios.

For adults and children ingesting Allegheny River water
adjacent to the Site under current and future conditions, there
is no increased risk for cancer and the hazard index ranged from
0.000009 for adults to 0.00005 for a child.

Ground Water and Seep Water Risks

The increased risk for cancer for a child ingesting seep
water under current and future conditions is 7 X 10"5. The hazard
index is 0.3 for this exposure scenario.

For an adult in the future using ground water as drinking
water from a well on or downgradient of the Site during working
periods, the increased risk of cancer is 4.2 X 10~5 and the
hazard index is 0.077 for this exposure scenario.
31
45
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A summary of all exposure scenarios and risks posed by the
Site for adults is shown in Table 20. The cumulative increased
risk for cancer for adults for the upper portion of the Site is
4.6 X 10~6, with the cumulative increased risk of cancer for
adults for the lower portion of the Site being 1.48 X 10~5.
TABLE 20
POTENTIAL CARCINOGENIC RISKS AND NONCARCINOGENIC HAZARD INDICES
VIA SOIL/SEDIMENT/WATER INGESTION ROUTES
FUTURE POPULATIONS (ADULTS)
Upper Area Surficial Soils
Recreational/Residential
Upper Area Surficial Soils
Occupational
Cancer
Risk
4 X 10
-6
6 X 10
-7
Hazard
Index
0.01
0.008
Lower Area Surficial Soils
Recreational
Allegheny River Sediments
Occupational
Cancer
Risk

Hazard
Index
2 X 10
0.05
-6
8 X 10"6
0.03
Allegheny River Water
Recreational
Upper Area Surficial/Subsoils
Occupational
Cancer
Risk

Hazard
Index
6 X 10
0.1
-7
0.000009
Bedrock/Alluvial Ground Water
Occupat i ona1
Cancer
Risk
4.2 X 10
-6
Hazard
Index
0.077
Total Cancer Risk 4.6 X 10*6 Total Cancer Risk
Upper Area Lower Area
1.48 X 10'5
46
32
-------
A summary of all risk scenarios and risks posed by the Site
for children is shown in Table 21. The cumulative increased risk
for cancer risk for children for the upper portion of the site is
5 X 10~5, with the cumulative increased risk of cancer for
children for the lower portion of the Site being 7 X 10~5.
TABLE 21
POTENTIAL CARCINOGENIC RISKS AND NONCARCINOGENIC HAZARD INDICES
VIA SOIL AND WATER INGESTION ROUTES
FUTURE POPULATIONS (CHILDREN)
.••^•••••^•••••••••...^••••••••^••^•••••••••^•^••••••^••^^••••••^••^•••••^•••••B*

Upper Area Surficial Soils Lower Area Seep Hater
Recreational/Residential Recreational

Cancer
Risk 4 X 10'5 7 X 1CT5
Hazard
Index 0.2 0.3
Allegheny River Water
Recreat iona1

Cancer
Risk
Hazard
Index 0.00005
Total cancer Risk 5 X 10'5 Total Cancer Risk 7 X 10'5
Upper Area Lower Area

Based on the risk assessment analysis for increased risk for
cancer and the hazard index, there is no current risk scenario
which would warrant EPA to trigger a remedial action at the
Lindane Site. Under the worst case scenario, the greatest
increased risk for cancer at the Site is for a child who ingests
water from the seep flows at the Site, which has a corresponding
risk of 7 X 10~5. This risk scenario does not exceed the lowest
acceptable risk level which is l X 10~4 which EPA generally uses
when determining if a remedial action should be undertaken.

However, if at any Superfund Site, it is determined that
there is increased risk of cancer which falls between 1 X 10
and l X 10~4 and human health could be threatened by any
contaminants which exceed other health based criteria, then I
may determine that a remedial action is warranted at a Site. ^r

33
47
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the Lindane Site, potential health based threats to humans could
occur as a result of the Maximum Contaminant Levels (MCLs)
exceedences that were found in the ground water. MCLs are
promulgated standards for drinking water under the Safe Drinking
Water Act. During the Remedial Investigation, MCL exceedences
were observed in the ground water for benzene and lindane (gamma-
BHC). Table 22 contains a summary of the ground water data
which was used in the risk assessment. The MCL for lindane is
0.2 parts per billion (ppb) and the MCL for benzene is 5 ppb.
Based on these thresholds there were a total of nine exceedences
of MCLs for the two contaminants observed during these sampling
events. Based on these MCL exceedences, which EPA believes could
pose a threat to human health sometime in the future, a remedial
action at the Lindane Site is considered warranted by EPA to
remediate the threat.
34
48
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TABLE 22
6ROUNDWATER DATA SUMMARY (1988 - 1989)*
ALSCO COMMUNITY PARK SITE
NATRONA, PENNSYLVANIA

Well

No.b Sample Date
PN-7
PN-8
PN-7
PN-7S
PN-8S
PN-lOwt
PN-10S
PN-7S
PN8
PN-8S
PN-10wt
PN-10S
Average
Standard Deviation
2/88
2/88
1/89
1/89
1/89
1/89
1/89
2/89
2/89
2/89
2/89
2/89

Upper 95 Percent Limit
Number of Samples
Maximum

Concentration (ppb)
Alpha-BHC

0.01
1.83
0.13
0.09
0.80*
0.05
2.36
0.01
2.48
0.52
0.05
2.29
0.97
1.05
1.51
12
2.48
Gamma-BHC

0.01
2.18
0.10
0.08
0.63d
0.05
2.98
0.05
3.74
2.24
0.16
2.53
1.23
1.39
1.95
12
3.74
Delta BHC

0.01
3.07
2.00
1.71
2.16d
0.05
3.74
0.01
4.53
2.99
0.11
4.04
2.03
1.68
2.90
12
4.53
M'-DDT*

0.02
0.02
0.02
0.02
0.02d
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.00
0.02
12
0.02
Benzene

0.2
0.2
9.4
0.2
1.01*
0.2
12.S
0.2
2.2
1.1
0.2
10.2
3.1
4.7
5.5
12
12.5
Chloro-
benzene
0.2
41
3.9
0.2
17.0"
0.2
24.9
0.2
51.6
31.0
0.2
41.8
17.7
19.6
27.9
12
51.6
1,2-DCBC

0.2
0.2
0.2
0.2
0.2*
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.0
0.2
12
0.2
1,4-008*

0.2
0.2
02
0.2
0.2-
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.0
0.2
12
0.2
* For purposes of averaging, data reported as BMDL were assumed to be equal to method detection limit; ND
data were assumed to be equal to 1/5 of the detection limit.
b Wells were determined to be representative of alluvial/shallow bedrock groundwater discharge from the Site.
e All data were ND.
d Average of duplicate sample results.
35
-------
It is important to note that a public water line exists at
the Site. The public water supply line supplies water to the
residential areas north and west of the Site, to three homes
along Karn's Road, and to Allegheny Ludlum's manufacturing plant.
However, no public water exists at the Alsco Community Park.
There are no currently known receptors using the contaminated
ground water as a source of drinking water; however, there still
exists a threat for possible human health risks if at sometime in
the future, development occurs downgradient of the Site or a
change in the use of the park occurs which could lead to the
potential use of the ground water as a drinking water source.

B. Environmental Impact of Site Contamination

An ecological assessment of the Site was done in conjunction
with the Remedial Investigation. During the assessment, there
was no observed impact on the terrestrial or aquatic life at the
Site. It was determined that, because the Site is surrounded by
highly developed residential, commercial and industrial areas, it
is unlikely that habitats are present that would be suitable for
significant numbers and varieties of terrestrial or avian
wildlife. There are no known wetlands near or influenced by the
Site. No known populations of rare or endangered plant or animal
species or significant biological communities are present within,
or in close proximity to the Site boundaries. Environmental
exposure points of concern at the Site include surface soils,
stream sediments, and stream water. The seeps are potential
sources of chemicals of concern to the streams; however, the
existing interim leachate collection and treatment system is
currently collecting an estimated 97 percent of all leachate
produced as a result of the Site and the treatment system is
removing an estimated 99 percent of the contaminants prior to the
effluent being discharged to the Allegheny River.
C. Uncertainty in the Risk Characterization

In order to quantitatively estimate the potential risks to
human health which may occur as a result of exposure to
contaminants in ground water at the Site, numerous assumptions
regarding exposure parameters were required. Within each
exposure parameter there is an inherent uncertainty. For
example, although 71.8 kilograms was used as a mean weight for
the entire population, actual body weights vary over a wide
range. Other uncertainties include ground water ingestion rates,
exposure frequencies, analytic results and toxicity numbers.

Actual or threatened releases of hazardous substances from
this Site, if not addressed by implementing the response action
selected in the ROD, may present an imminent and substantial
endangerment to public health, welfare or the environment.
36
50
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VII. DESCRIPTION OP ALTERMATIVE8

The Superfund process requires that the alternative chosen
to clean up a hazardous waste site meet several criteria. The
alternative must protect human health and the environment, be
cost-effective, and meet the requirements of environmental
regulations. Permanent solutions to contamination problems
should be developed whenever possible. The solutions should
reduce the volume, toxicity, or mobility of the contaminants.
Emphasis is also placed on treating the wastes at the site,
whenever this is possible, and on applying innovative
technologies to clean up the contaminants.

The FS studied a variety of technologies to see if they were
applicable for addressing the contamination at the Site. The
technologies determined to be most applicable to these materials
were developed into remedial alternatives. These alternatives
are presented and discussed below.

other alternatives not listed below but examined during the
FS included both on-site and off-site encapsulation of the fill
material and also on-site and off-site treatment and disposal of
residuals left after treatment in an approved disposal facility.
Capital costs for these alternatives ranged from $ 360,000,000
for on-site encapsulation to $ 575,000,000 for off -site
encapsulation and $ 1,500,000,000 for excavation, on-site
incineration and on-site disposal to $ 2,000,000,000 for
excavation, off-site incineration and disposal at an off-site
disposal facility. These alternatives were not analyzed in
greater detail as were the other alternatives due to their
associated high costs, the large volume of material
(approximately 1,200,000 cubic yards) that would have to be
handled and treated, the lack of discernable hot spots at the
Site, and the marginal risk reduction which results if they were
to be implemented.

All costs and implementation timeframes specified below are
estimates based on best available information. All operation and
maintenance costs shown are for an annual basis.
COMMON gLgMmrogs All of the alternatives with the exception
of "No Further Action1* would include common components. Each of
them include (1) a restrictive covenant to be put in place that
would prohibit any further development of the Site for uses other
then those currently in use and prevent the use or development of
surface water or ground water on or beneath the property; (2) the
leachate/shallow ground water collection and treatment system
will be upgraded to replace the existing interim system; (3)
security fencing will be built to limit access to the lower
portion of the project Site; (4) implementation of a long term
ground water monitoring program to assess effectiveness of the
remedy on the ground water in the alluvial and bedrock and to
measure site-related contaminants over time; (5) an EPA review of
the Site every five years will be done to ensure continued
protection to human health and the environment (the 5 year review
would also be applicable to the "No Further Action Alternative1') .
37
51
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ALTERNATIVE 1; NO ACTION

Capital Cost: $ 0
Operation and Maintenance: $ 240,000
Present Worth: $ 2,262,500
Months to Implement: 0

The National Contingency Plan (NCP), EPA's regulations
governing the Superfund program, requires that the "no-action"
alternative be evaluated at every site to establish a baseline
for comparison with the other alternatives. Under this
alternative, no remedial action would be taken at the Site.

However, at the Lindane Dump Site, remedial actions have
already been taken. Thus a true "no action" is not possible.
The best approximation of a no-action is ceasing current actions,
that is shutting off the current interim leachate collection and
treatment system. However, since these remedial actions will not
cease, as the existing leachate collection and treatment system
must continue to be operated and maintained under the existing
State of Pennsylvania Order, this alternative has been termed "no
action". Under this alternative the interim leachate collection
and treatment system will remain in service and the Site would be
left in its current condition.

Under this alternative EPA would still review the Site
within five years in accordance with CERCLA to assure that
changes have not occurred which would pose a risk to human health
or the environment.

As this is the "No Action" Alternative, No ARARs would be
applicable for this alternative as there is no Remedial Action
being implemented.

ALTERNATIVE 2 CLAY AND SOIL CAP. UPGRADED LEACHATB COLLECTION AND
TREATMENT SYSTEM. DEED AND ACCESS RESTRICTIONS AMD GROUND WATER
MONITORING

Capital Cost: $ 8,162,700
Operation and Maintenance: $ 634,700
Present Worth: $ 14,146,000
Months to Implement: 24 months

This alternative essentially consists of two remedial
elements: engineering controls which include a clay soil cap
(along with appurtenant alternative components, i.e. storm
drainage culverts) and optimization of the existing interim
leachate collection and treatment system (ILCTS). Institutional
controls will include deed and access restrictions.

The proposed cap would cover approximately 18 acres of the
Site. Most of the upper area of the Site now occupied by the
Natrona Alsco Community Park and approximately 7.3 acres of the
lower area of the Site would be capped. The cap would be placed
over those areas where waste was previously disposed of. Based
on currently available information, the cap would not extend onto
any residential properties. Figure 8 shows the approximate
boundaries of the proposed cap. The cap would consist of a 2

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i ' V /
v ---->< A/
LINDANE DUMP SITE

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foot clay layer, a drainage layer, 2 feet of fill material and 1
foot of topsoil, the cap would then be revegetated. Figure 9
shows a typical cross-section of the cap layer. The cap will
have a slope of approximately 3.5 percent in the lower area and 4
percent in the upper area. Because of the new cap, the park
facilities would have to be reconstructed with the exception of
any trees within the capped area which could not be replaced as
their root systems would compromise the integrity of the new cap.

The optimization of the ILCTS will include construction of a
new treatment facility which would meet or exceed the required
effluent discharge limits that would be established for this
Site. The treatment components for the leachate to be
implemented will include water conditioning, neutralization, air
stripping, solids filtration, granular activated carbon
absorption, backwash, solids thickening and dewatering.
The sludge created by the treatment process which will be
considered hazardous will be disposed in an approved disposal
facility.

The new leachate/shallow ground water collection and
treatment system will handle approximately an estimated 35,700
gallons of leachate per day and will remove approximately 97
percent of all contaminants contained in the leachate. The
capping will also reduce the amount of contaminants which are
currently released from the soil as a result of erosion and
stormwater runoff by 96 to 99 percent.

In addition to the above components, monitoring wells would
be installed to monitor the alluvial and shallow bedrock aquifer
downgradient of the Site to ensure that human health and the
environment are adequately protected.

ALTERNATIVE 3 CLAY AND SOIL CAP. UPGRADED LEACSATE COLLECTION AND
TREATMENT SYSTEM. GROUND WATER EXTRACTION AMD DISCHARGE. DEED AND
ACCESS RESTRICTIONS• AND GROUND WATER MONITORING

Capital Cost: $ 8,745,900
Operation and Maintenance: $ 677,900
Present Worth: $ 15,136,500
Months to Implement: 24 months
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FINSIHED GRADE
WITH VEQETATION
V
TOPSOIL
EARTHEN
BACKFILL MATERIAL
FILTER FABRIC-v
GEONET \
DRAINAGE—*S
LAYER
FILTER FABRIC
XXXXX
XXXXXX
XXXXX
CH or CL CLAY

K.< !X1(F7cm/8ec

XXXXXX
XXXXXX
XXXXXX
WASTE MATERIAL
TYPICAL CAP SECTION
1' - 0' TYP.
2'-0' TYP.
."LESS THAN f
MINIMUM 2'-0'
NOT TO SCALE
LINDANE DUMP SITE
FIGURE 9

TYPICAL CAP SECTION
CLAY AND SOIL CAP
-------
This Alternative is the same as Alternative 2 except for the
addition of an additional engineering control consisting of
implementing a ground water extraction component from the
alluvial/shallow bedrock zone at the base of the Site and the
direct discharge of the extracted ground water to.the Allegheny
River.

The ground water would be extracted through the use of
pumping wells at the Site. Approximately 24 wells would be
needed to effectively meet the required pumping rate.

It was assumed during the FS that the extracted ground water
would then be discharged directly to the Allegheny River without
treatment as the ground water now meets the current FADER water
quality effluent limits for the Site. All quantities of waste
treated in this alternative would be the same as in alternative
2.

TREATMENT SYSTEM. DEED AND ACCESS RESTRICTIONS. AND GROUND WATER
MONITORING

Capital Cost: $ 8,131,300
Operation and Maintenance: $ 634,700
Present Worth: $ 14,114,600
Months to Implement: 24 months

This Alternative is the same as Alternative 2 with the
exception of the cap design. The layout of the cap is the same
as Alternative 2, but the cap construction would consist of a l
to 2 foot thick impervious clay layer overlain by a 50 mil
(minimum thickness) impervious geomembrane, a drainage layer with
filter fabric, 2 feet of earthen backfill material and a 1 foot
layer of topsoil with vegetation.

The difference between the cap design (clay and soil) in
Alternative 2 and this alternative is the additional reduction of
infiltration which the multi-layer cap would provide. It is

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estimated that the additional reduction in infiltration provided
by the multi-layer cap would be approximately 14 percent greater
than the clay and soil cap.

All other components contained in Alternative 2 would be
implemented in conjunction with this Alternative.

ALTERNATIVE 5 MULTI-LAYER CAP, UPGRADED LEACHATE COLLECTION AND
TREATMENT SYSTEM* GROUND WATER EXTRACTION AND DISCHARGE* DEED AND
ACCESS RESTRICTIONS AMD GROUND WATER MONITORING

Capital Cost: $ 8,714,500
Operation and Maintenance $ 677,900
Present Worth: $ 15,105,100
Months to Implement: 24 months

This Alternative is the same as Alternative 4 (Multi-layer
Cap) except for the addition of the ground water extraction and
discharge to the Allegheny River which is the same as the ground
water extraction component described in Alternative 3.

The following ARARs have been identified for this
alternative; for the airstripping operation at the leachate
collection and treatment system, Section 7401 of the Clean Air
Act, 42 U.S.C. S 7401; Chapter 127, S 127.1 of the Pennsylvania
Air Pollution Control Act; For the effluent discharge form the
treatment plant, 35 P.S. SS 691.1 et. sea. of the Pennsylvania
Clean Stream Law; For the cap, and its operation and maintenance,
Title 25, Article VT, Chapters 260 thru 270 and Chapter 75.38 of
the Pennsylvania Hazardous Waste Management Regulations; For
clean-up of the contaminated leachate and shallow ground water,
§§ 300f to 300J-26 of the Safe Drinking Water Act, 42 U.S.C. and
for the cap; its operation and maintenance; for any leachate
treated and any residual waste which is created as the result of
the treatment process, 40 C.F.R. § 264 of the Resource
Conservation and Recovery Act; for the ground water extraction
and discharge, 35 P.S. §§ 691.1 et. sea. of the Pennsylvania
Clean Stream Law.
41 57
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_cc
)ED LEACHATB COLLECTION AMD TREATMENT SYi
ACCESS RESTRICTIONS AND GROUND WATER MONITORING
Capital Costs:
Operation and Maintenance:
Present Worth:
Months to Implement:
$ 8,139,200
$ 634,700
$ 14,122,500
24 months
This Alternative, though not discussed in the Feasibility
Study was developed by EPA, upon review of the alternatives
proposed in the FS. Because of concerns about construction of a
multi-layer cap over portions of the Site which have steep side
slopes, a combination of alternatives 2 and 4 was developed which
would provide for a multi-layer cap over those portions of the
Site where side slopes are not considered a problem and a clay
and soil cap over those portions where slope stability may make
it infeasible for the multi-layer cap to be placed. It is
currently estimated that a multi-layer cap could be utilized on
over 75 percent of the capped area. The determination of the
final areas to be covered by either type of cap will be
determined during project design. The rest of this alternative
would incorporate all other components as previously described in
alternatives 2 and 4.

VIII. COMPARATIVE ANALYSIS OP ALTERNATIVES

Each of the seven remedial alternatives has been evaluated
with respect to the nine evaluation criteria set forth in the
NCP, 40 C.F.R. S 300.430(e)(9). These nine criteria can be
categorized into three groups: threshold criteria, primary
balancing criteria, and modifying criteria.

Threshold Criteria

1. Overall Protection of Human Health and the Environment
2. Compliance with Applicable or Relevant and Appropriate
Requirements (ARARS)
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Primary Balancing Criteria

3. Reduction of Toxicity, Mobility, or Volume through
Treatment
4. Implementability
5. Short-term Effectiveness
6. Long-term Effectiveness
7. Cost

Modifying Criteria

8. Community Acceptance
9. State Acceptance

These evaluation criteria are in accordance with the
requirements of Section 121 of CERCLA, 42 U.S.C. § 9621 which
measure the overall feasibility and acceptability of the
alternatives. Threshold criteria must be satisfied in order for
an alternative to be eligible for selection. Primary balancing
criteria are used to evaluate the performance of each of the
alternatives relative to the others. State and community
acceptance are the modifying criteria formally taken into account
after public comment is received on the Proposed Plan. The
evaluations are as follows:

THRESHOLD CRITERIA

1. Overall Protection o
All of the alternatives would provide varying degrees of
protection to human health and the environment by eliminating,
reducing or controlling risk through treatment, engineering
controls, or institutional controls. Alternatives 2, 3, 4, 5,
and 6 would reduce the risk to human health from exposure to
contaminated ground water and seeps through the implementation of
the leachate/shallow ground water collection and treatment
system. The implementation of a cap in all of the alternatives
would reduce the risk of potential exposure to any receptor from
direct contact with any contaminants on the surface or within the
near surface of the Site. Transportation of contaminants by
erosion will also be reduced or eliminated by the installation of
the cap. The amount of leachate produced will also decrease as a
result of the reduced infiltration which will result from
implementation of the cap.

2. COMPLIANCE WITH ARAR8

The following applicable or relevant and appropriate
requirements (ARARs) have been currently identified: Section 7401
of the Clean Air Act, 42 U.S.C. S 7401; Chapter 127, S 127.1 of
the Pennsylvania Air Pollution Control Act; 35 P.S. SS 691.1 e£
sea, of the Pennsylvania Clean Stream Law; Title 25, Article VI,
Chapters 260 thru 270 and Chapter 75.38 of the Pennsylvania
Hazardous Waste Management Regulations; §S 300f to 300J-26 of the
Safe Drinking Water Act, 42 U.S.C. and 40 C.F.R. S 264 of the
Resource Conservation and Recovery Act.

Alternatives 2, 3, 4, 5, and 6 will attain compliance with

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NPDES requirements for the effluent discharge, under 25 Pa. Code
Chapters 16, 93, and 97 of the Pennsylvania Water Quality
regulations, from the leachate/shallow ground water collection
and treatment system. The cap design, construction and
subsequent maintenance will meet the appropriate and relevant
requirements of landfill closure and maintenance under 25 Pa.
Code §S 271.0 - 273.0. The air emissions from the leachate
treatment system will attain the ARAR under the National
Emissions Standards for Hazardous Air Pollutants (NESHAPS) set
forth at 40 C.F.R. S61.64 and Chapter 127, $ 127.1 et sea.of the
Pennsylvania Air Quality regulations for such operations. In
alternatives 3 and 5, the ground water discharge to the Allegheny
River will attain the required effluent discharge parameters as
established by the Commonwealth regulations and laws as specified
under Chapters 93, 16 and 97 of the Pennsylvania Water Quality
regulations. It is believed that none of the alternatives can
attain the Commonwealth of Pennsylvania ARAR as specified by 25
Pa. Code §§ 264.90 - .100., Pa. Code 264.97(i)(j) and
264.100(a)(9) for remediating ground water to background levels.
It is believed that this cleanup level may be unattainable at
this Site due to potential stability problems created by the
previous mining operations which took place at the Site.
Extraction and treatment of ground water in the vicinity of Karns
Road may be impracticable due to the close proximity of the
mining area. Subsidence problems could result if such a
technique were undertaken. Additionally, the downgradient
portion of the plume has only low levels of contaminants. It is
highly unlikely that implementing a pump and treat system at a
substantial financial cost would substantially reduce these
levels. In addition, it is anticipated that with the
implementation of the cap over the Site, the level of
contaminants reaching the lower aquifer will be substantially
reduced.

PRIMARY BALANCING CRITERIA

3. LONG TERM EFFECTIVENESS AMD PERMANENCE

While none of the alternatives provides a permanent remedy,
Alternatives 3 and 5 provide the highest level of long-term
effectiveness practicable at the Lindane Dump Site. Both
alternatives extract the ground water and prevent potential
migration of contaminants, while preventing further contamination
of the aquifer with the use of the cap. Alternatives 2, 4, and 6
would provide long-term effectiveness by reducing or eliminating
further contamination through the implementation of the cap. The
implementation of the optimized leachate/shallow ground water
collection and treatment system in all of the alternatives will
provide a long-term and effective means of controlling and
eliminating contamination contained in the seeps and shallow
ground water. Under all of the alternatives there would remain a
residual of risk as the source material would continue to exist
underneath the cap. If the cap should prove to be ineffective or
fail sometime in the future or the leachate collection and
treatment system fail, the long-term monitoring of the Site would
identify any changes in the risks posed by the Site prior to any
receptors being adversely affected.

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4. REDUCTION OF TOXICITY, MOBILITY OR VOLUME THROUGH TREATMBMT

All of the alternatives would collect and treat the
contaminants in the leachate and shallow ground water, through a
leachate/shallow ground water collection and treatment system.
Alternative 1 would also collect and treat the contaminants;
however, the resulting effluent discharges would not meet the new
effluent discharge standards that have been established by PADER
for the new system under Chapters 16, 93, and 97, 25 Pa. Code 25
Chapters 16, 93, and 97 of the Pennsylvania Water quality
regulations due to the continued use of the existing leachate
collection system. All of the alternatives will reduce the
toxicity, volume and mobility of contaminants contained in the
ground water and leachate through the treatment process. Through
the implementation of the cap in alternatives 2, 3, 4, 5, and 6,
the mobility of the contaminants in the fill layer would be
reduced due to the reduction of infiltration of water through the
fill layer. The use of ground water extraction in alternatives 3
and 5 would reduce the mobility of the contaminants in the deeper
aquifer, but would not reduce the volume or toxicity of the
contaminants as the ground water would not be treated. None of
the alternatives would permanently reduce the toxicity, mobility
and volume of hazardous wastes which is the preferred remedial
action pursuant to Section 9621 of CERCLA, 42 U.S.C. § 9621.
However, it has been shown during the FS screening process that
for the alternatives considered, permanent reduction of toxicity,
mobility and volume of hazardous substances would be technically
impracticable from an engineering and economic perspective.

5. SHORT-TERM EFFECTIVENESS

Alternatives 2, 3, 4, 5 and 6 could present short-term
risks to workers and the community due to increased truck and
construction traffic during the installation of the additional
soil cover or construction of a multi-layer cap. Fugitive dust
emissions from the Site may occur during construction activities.
Risks to onsite workers could be minimized by the use of proper
operating procedures, personal protective gear and the continual
monitoring for on-site emissions during construction.
Precautions would also be taken to ensure that these emissions
would not impact the community.

Alternatives 2, 3, 4, 5 and 6 could also present short-term
risks to workers who might come in contact with contaminated
ground water resulting from maintenance activities on the
leachate treatment and ground water extraction systems, recovery
wells, or associated piping. The health risks associated with
such short-term exposures is considered minimal. Risks to onsite
workers could be minimized by the use of proper operating
procedures and personal protective gear and monitoring.

The various components of the Preferred Alternative could be
constructed within 24 months following issuance of the ROD. The
leachate collection and treatment system would be fully
operational at that time and would be collecting approximately 97
percent and treating 99 percent of all contaminants in the ground
water and leachate at the Site. The site cap would also be
completed but residual contaminants remaining in the ground water

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would not be remediated until such time that the contaminants
migrate downgradient and are captured and treated by the leachate
collection and treatment system.

6. IMPLEMENTABILITY

Each of the alternatives under consideration would be
implemented at the Site using conventional construction
practices. Alternatives 2, 3, 4, 5, and 6 may pose some
implementation problems during construction due to the Site
restrictions which limit construction Site access and would
affect sizing of the plant for the construction of the new
leachate/ shallow ground water collection and treatment system.
If any of the Alternatives should ever fail or if additional Site
risks are ever identified, additional response actions could
easily be implemented to address any new risks which may be posed
by the Site. Any of the capping components can be easily
implemented. Capping is a proven and reliable technology with
needed materials and contractors readily available. The leachate
collection and treatment component has already been proven at the
Site and the components to rebuild the system to its new
operating standard again is readily available. Approvals from
other governmental agencies to construct and operate any of the
alternatives is not expected to be difficult to obtain.
Monitoring wells for the long-term monitoring program can be
easily installed downgradient of the Site to monitor the ground
water in the shallow bedrock and alluvium areas.

7. COST

CERCLA requires selection of a cost-effective remedy that
protects human health and the environment and meets the other
requirements of the Statute. The capital and the annual
operation and maintenance (O&H) costs for these alternatives, as
calculated on a present worth basis are similar in cost range.
Costs have been developed for direct and indirect capital costs
and O&M costs. The present worth of each alternative has been
calculated for comparative purposes.

Direct capital costs include the following:

o Remedial action construction

o Equipment

o Building and services

o Waste disposal, costs

Indirect capital costs include:

o Engineering expenses

o Environmental permit compliance

o Startup and shakedown

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o Contingency allowances
Annual O&M costs include the following:
o Operating labor and material cost
o Maintenance materials and labor costs
o Chemical, energy and fuel costs
o Administrative costs and purchased services
o Monitoring costs
o Costs for periodic site review (every five years)
o Insurance, taxes, and license costs
The remedial action alternative cost estimates have an
accuracy of +50 percent to -30 percent. For the purpose of the
present worth calculations, all Alternatives have a performance
period of 30 years. Costs for the alternatives considered are
shown in Table 23.
TABLE 23
DETAILED COST ESTIMATE ANALYSIS
PRESENT WORTH ANNUAL TOTAL PROJECT
ALTERNATIVE CAPITAL COST O&M COST COST
1 $ 0 $ 240,000 $ 2,262,500
2 $ 8,162,700 $ 634,700 $ 14,146,000
3 $ 8,745,900 $ 677,900 $ 15,136,500
4 $ 8,131,300 $ 634,700 $ 14,114,600
5 $ 8,714,500 $ 677,900 $ 15,105,100
6 $ 8,139,200 $ 634,700 $ 14,122,400
I/ Total Project Costs Based On Present Worth at 10
percent interest for 30 years
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MODIFYING CRITERIA

8. STATE ACCEPTANCE
The Commonwealth of Pennsylvania has concurred with
selection of Remedial Alternative 6 for implementation at the
Site.
9. COMMUNITY ACCEPTANCE

A public meeting on the Proposed Plan was held on January 8,
1992 in Natrona Heights, Pennsylvania. Comments received at that
meeting and during the comment period are discussed in the
Responsiveness Summary to this Record of Decision
IX. SELECTED REMEDIAL ALTERNATIVE

The remedial alternative selected for implementation
("Selected Remedy") at the Lindane Dump Site is Alternative 6,
Combination Multi-Layer and clay and Soil Cap, vith an optimized
Leachate/Shallov Ground water collection System, Deed and Access
Restrictions, and Long-Term Monitoring.

While the use of a multi-layer cap, with a synthetic liner
over the entire 18 acre area of the Site to be capped would be
preferred, the use of a combination cap would address possible
construction and stability problems on portions of the Site where
the steep side slopes may pose problems for placement of the
synthetic liner which could act as a slippage plane for the
overlying layers of soil.

The implementation of the combination cap will reduce or
eliminate the infiltration of water through the fill area in the
upper portion of the Site and a part of the lower portion of the
Site. This in turn will reduce or eliminate the movement of the
contaminants from the fill area to the aquifer below the Site,
which will help to eliminate the current MCL violations in the
ground water and the seeps. The addition of the cap will also
eliminate any potential exposure to Site contaminants which may
be present in the surface or near-surface soils of the Site. As
a part of the capping operation the existing park facilities
would be reconstructed.

The new optimized leachate/shallow ground water collection
and treatment system will eliminate any exposure to contaminants
contained in the leachate from the seeps. The effluent from the
treatment process will meet or exceed the new Commonwealth of
Pennsylvania water quality criteria standards.

The use of deed and access restrictions will prevent any
intrusion or activity which may compromise the integrity of the
new cap and limit access to any area which is not capped.

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Long-term monitoring of the surface and ground water in the
alluvial and shallow bedrock will also be implemented to ensure
the effectiveness of the cap and the leachate/shallow ground
water collection and treatment system and to monitor for MCL
exceedences. If during the course of the monitoring, it is
determined that MCL exceedences are continuing to occur or begin
to reoccur, additional action will be implemented to remediate
the threat.

Five year reviews of the Site will also be conducted to
insure that the remedy selected was being protective of human
health and the environment.

Performance Standards

(1) Construction of Clay and soil and Multi-layer Cap

The surface area to be capped shall include those areas
where there is historical evidence of waste materials. In
addition, an analysis shall be done to determine the upper 95
percent confidence limit (UCL), the coefficient of variation,
along with a statement of statistical confidence and power, for
any contaminants in the remaining soils outside the area proposed
to be capped. For those areas where the 95% UCL for any
contaminant exceeds a health-based standard which was used in the
Site risk assessment, the cap shall be extended to cover those
areas.

The clay and soil cap portion of the overall cap shall
consist of a 2-foot clay layer, a drainage layer, 2-foot of clean
earthen backfill material and a 1-foot layer of topsoil. The 3
feet of cover material shall be sufficient to protect against
freezing in the area. The depth of the layers required to
protect against freezing shall be confirmed during the design
phase of the cap. The maximum slope for the cap shall be between
3 to 5 percent with a minimum slope which will provide for
adequate site drainage without causing potential erosion
problems. Adequate measures shall also be taken to insure the
slope stability.

The clay selected for the clay and soil cap construction
shall meet the classification of CH or CL under the criteria for
the Unified Soil Classification as determined by the provisions
of the American Society for Testing and Materials (ASTM) D2487,
Latest Edition. The clay shall have an overall permeability
coefficient of 1.0 x 10~7 cm/sec or less following placement and
compaction.

The drainage layer shall consist of a minimum l-foot thick
layer of well draining soil having a minimum hydraulic
conductivity value of 1 x 10~3 cm/sec or an alternate drainage
method with an equivalent flow capacity. A geonet material may
be substituted for the well-draining soil if during the design
phase, cost studies show it to be more economical and that design
studies show it will meet or exceed the comparable performance
criteria of the soil drainage layer. If the geonet material is
selected, a filter fabric shall be installed above and below the
geonet material to prevent fines from entering and blocking the

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void spaces.

The multi-layer cap portion of the overall cap shall consist
of a l to 2 foot impervious clay layer, overlain by minimum 50
mil impervious geomembrane, a drainage layer with-filter fabric,
2 foot of clean earthen backfill material, a 1 foot layer of
topsoil. The 3 feet of cover material will be sufficient to
protect against freezing in the area. This depth of the layers
required to protect against freezing shall be confirmed during
the design phase of the cap.

The clay selected for the multi-layer cap construction shall
meet the classification of CH or CL under the criteria for the
Unified Soil Classification as determined by the provisions of
the American Society for Testing and Materials (ASTM) D2487,
Latest Edition. The clay shall have an overall permeability
coefficient of 1.0 x 10~7 cm/sec or less following placement and
compaction.

The geomembrane shall be placed directly on top of the clay
layer to act as an additional seal to further minimize
infiltration by incidental precipitation. The geomembrane shall
have a coefficient of permeability that is equal to or less than
that of the underlying clay material used in the cap as described
above.

The drainage layer shall consist of a minimum 1-foot thick
layer of well draining soil having a minimum hydraulic
conductivity value of 1 x 10~3 cm/sec or an alternate drainage
method with an equivalent flow capacity. A geonet material may
be substituted for the well-draining soil if during the design
phase, cost studies show it to be more economical and that design
studies show it will meet or exceed the comparable performance
criteria of the drainage soil layer. If the geonet material is
selected, a filter fabric shall be installed above and below the
geonet material to prevent fines from entering and blocking the
void spaces.

The cap construction shall be conducted in such a manner
that will minimize all potential risks and hazards associated
with the Site and constituents of concern. Dust suppression and
control shall be implemented as part of the construction plan.
An air monitoring plan to ensure the safety of on-site workers
and nearby residents levels shall also be developed and
implemented during construction.

A surface water control plan shall be developed and
implemented during the cap construction to prevent the off site
migration of any contaminated water, soil, or sediments.

The cap shall be maintained to ensure the permeability
coefficient of 1 x 10~7 cm/sec. Routine inspection and
maintenance shall be performed on a regular basis for a period
of 30 years. Maintenance shall include, but shall no be limited
to repairs to the cap as necessary to correct the effects of
settling, subsidence, erosion, animal intrusion, etc., and the
cultivation of natural vegetation (grasses and weeds) on the clay
and topsoil portion of the cap to prevent erosion. As this is a

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containment only remedy, it may be required that cap maintenance
be continued beyond the 30 years period to insure the cap
integrity until no hazardous substances remain on site which may
pose a threat. Because the selected remedy will result in
contaminants remaining on-site, 5-year site reviews under Section
121(c) of CERCLA, 42 U.S.C. § 9621 (c) shall be required.

The areas where the multi-layer cap or clay and soil cap
will be placed will be determined by EPA based a slope stability
analysis to be done as a part of the Remedial Design phase and on
the design specifications of the synthetic liner and the
manufacturers recommended maximum allowable slope for its
placement. Based on this analysis, the multi-layer cap will be
used over the maximum portion, of the area to be capped, shown
feasible.

The final cap design and construction shall meet the
relevant and appropriate requirements of Commonwealth of
Pennsylvania Municipal Landfill Closure Standards as contained in
25 Pa. Code 264 §§ 301-310.

(2) Installation of Surface Drainage

Surface drainage for the entire Site shall be designed and
constructed in such a manner so as to control and minimize the
amount of overland drainage which will occur in order to minimize
any surface erosion and to lessen potential infiltration through
the cap. The drainage system for the entire Site shall also be
designed in such a manner so as to avoid impacting upon the
existing surface drainage from any adjacent land owner. The
drainage system shall be able to carry a discharge based on the
24 hour, 25 year, rainfall event.

(3) Vegetation of Cap Area

Vegetation shall be established on the newly capped area
upon its completion. Revegetation shall provide for an effective
and permanent vegetative cover of the same seasonal variety as
vegetation native to the Site and capable of self regeneration.
Revegetation shall provide a quick germinating, fast growing
vegetative cover capable of stabilizing the soil surface from
erosion. Mulch shall be applied to newly vegetated areas to
control erosion and promote germination of seeds and increase
moisture retention of the soil.

(4) Leachate/Shallow Ground Water collection and Treatment
System

The selected remedy includes the continued collection and
treatment of shallow ground water and leachate emanating at the
base of the Site along Karns Road. The existing treatment system
shall be modified so that the resulting discharge will meet or be
lower than the PAOER proposed final effluent discharge limits
under NPDES. The treated effluent will then be discharged to the
Allegheny River. The appropriate treatment system to meet the
effluent discharge standards shall be designed and submitted to
EPA for review. EPA in conjunction with PADER will have final

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approval authority on the final treatment system. The sludge
generated by the treatment system which will be considered to be
hazardous will be disposed of at an approved disposal facility.

The collection and treatment system shall be .maintained for
a 30 year period or longer if hazardous substances which pose a
threat remain on site.

(5) Construction of a Perimeter Fence

A perimeter fence shall be constructed around the lower
portion of the Site to prevent public access to this portion of
the Site. The fence shall be maintained for 30 years or longer
if hazardous substances remain on site.

(6) Ground Water and surface water Monitoring

Surface water (storm runoff and seeps) and ground water
(monitoring wells) monitoring shall be conducted for 30 years.
During the first five years, sampling shall be conducted
quarterly. This data will be evaluated by EPA, in consultation
with PADER, to determine the monitoring needs for the next 25
years. Parameters to be monitored include but are not limited to
the following: volatile organic compounds, semi-volatile organic
compounds, TAL inorganics (metals), pesticides, particle size,
and leachate parameters. The number and placement of monitoring
wells will be determined by EPA during the design phase to
maximize the monitoring of the ground water migration from the
Site.

(7) Restoration of Park Facilities

The park facilities located on the upper portion of the Site
known as Alsco Community Park shall be reconstructed after
completion of the Site cap so as to provide the same recreational
facilities and supporting structures as existed prior to
construction of the cap. The new park facilities, however shall
be constructed in such a manner, so as to not compromise the
integrity of the cap. In addition, no trees which are removed as
a result of the capping will be replaced within the new cap area.
This is to prevent the tree root systems from invading and
compromising the integrity of the cap.
X STATUTORY DETERMINATIONS

Under its legal authorities, EPA's primary responsibility at
a CERCLA site is to undertake remedial actions that achieve
adequate protection of human health and the environment. In
addition, Section 121 of CERCLA, 42 U.S.C. § 9621, establishes
several additional statutory requirements and preferences. One
such requirement is that when complete, the Selected Remedy
implemented at the Site must comply with applicable or relevant
and appropriate environmental standards established under federal
and state environmental laws unless a statutory waiver is
justified. The Selected Remedy also must be cost-effective and
utilize permanent solutions and alternative treatment

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The Selected Remedial Alternative protects human health and
the environment in the long term through the implementation of a
cap which will reduce the infiltration of water through the fill
area, which in turn will reduce the migration of contaminants
from the fill into the ground water. In conjunction with the
cap, the upgrading of the existing leachate/shallow ground water
collection and treatment system 'will assure that any contaminants
which are contained in the leachate or ground water will be
removed prior to its discharge to the Allegheny River. In
addition to the reduction in infiltration of water through the
fill area, the cap will also prevent exposure to any contaminants
which may exist in the surficial or near surface soils. Long-
term maintenance of both the cap and leachate/shallow ground
water collection and treatment system will ensure the continual
protection provided by both elements.

The implementation of deed restrictions for the entire Site
along with security fencing in the lower portion of the Site will
further provide protection by preventing any intrusive activity
which could compromise the cap's integrity.

There are no short-term risks associated with the Selected
Remedy that cannot be readily be controlled. In addition, no
adverse cross media impacts are expected from implementation of
the selected remedy.

Compliance with Applicable or Relevant and Appropriate
Requirements

The Selected Remedy will comply with all applicable or
relevant and appropriate chemical-, location-, and action-
specific ARARs except for the noted waiver. Those ARARS are as
follows:

1. Chemical-Specific ARARs

a. Relevant and appropriate Maximum Contaminant
Levels (MCLS) promulgated under the Safe Drinking
Water Act, 42 U.S.C. §§ 300f to 300J-26, and set
forth at 40 C.F.R. S 141.61(a) and 55 Fed. Reg.
30370 (July 25, 1990) are:

Contaminant Concentration (ua/liter)

Gamma-BHC (Lindane) .2
Benzene 5
b. The Pennsylvania ARAR for ground water for
hazardous substances is that all ground water must
be remediated to "background" quality as specified
by 25 Pa. Code SS 264.90 - .100. Such background
levels shall be attained as part of the Selected
Remedy, unless it is demonstrated that attaining
such levels is infeasible or otherwise waivable
under CERCLA § 121(d), 42 U.S.C. S 9621(d).

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b. The Pennsylvania ARAR for ground water for
hazardous substances is that all ground water must
be remediated to "background11 quality as specified
by 25 Pa. Code §§ 264.90 - .100. Such background
levels shall be attained as part of the Selected
Remedy, unless it is demonstrated that attaining
such levels is infeasible or otherwise waivable
under CERCLA § 121(d), 42 U.S.C. § 9621(d).

c. The National Emissions Standards for Hazardous Air
pollutants (NESHAPs) set forth at 40 C.F.R. §
61.110 - .112 and promulgated under the Clean Air
Act, 42 U.S.C. § 7401 contains an emission
standard for benzene for equipment leaks which is
relevant and appropriate, to the air stripping if
the airstripping produces 1000 megagrams of
benzene per year or more.

d. Applicable discharge limits for the final effluent
discharge from the leachate treatment system have
been established under 25 PA Code §§ 93.1 - 93.9.
They are as follows;

Monthly Daily
Parameter Ave fmo/1) Max (ma/1)

Flow (MGD) 0.0304
Suspended Solid 20 40
Alpha-BHC 0.01 0.02
Beta-BHC 0.01 0.02
Delta-BHC 0.01 0.02
Gamma-BHC 0.01 0.02
Benzene 0.01 0.02
4,4-DDT 0.0003 0.0005
pH between 6.0 and 9.0 S.U.
at all times

EPA is waiving the requirement in the Pennsylvania Hazardous
Regulations [ 25 PA Code §§ 264.90 - 264.100 specifically 25 PA
Code §§ 264.97 (i) and (j) and § 264.100(a) (9), which contain
a requirement to remediate all ground water to background levels.
EPA is waiving the requirement to remediate to background levels
based on the technical impractibility of being able to extract
all contaminated ground water from beneath the Site to treat it
so as to meet background levels. It should be noted that the
contaminated ground water in the deep aquifer already meets the
Federal Drinking Water Standard and that shallow ground water
will meet the Federal Standard once it has been treated. The
authority to waive ARARS is found in CERCLA § 121(d)(4), 42
U.S.C. §9621 (d)(4) and the NCP §300.430(f)(1)(ii)(C). This ARAR
is being waived for the technical impractibility of extracting
all contaminated groundwater associated with the Site. The major
reasons include; 1) Potential subsidence problems which could
occur within the Site as a result of the pumping the deep
aquifer. Subsidence could occur during pumping as the imcreased
movement of the groundwater could contribute to potential

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instability of the waste material which makes up the majority of
the fill area and the mineshafts which exist below the Site below
the Site; and 2) The potential for additional migration of
contaminants from within the fill area into the deep aquifer
could be caused by the ground water extraction process. If this
occurs, combined with the uncertainty of the ability to capture
all contaminated ground water from the deeper aquifer due to the
complex hydrogeologic conditions at the Site would work against
the purpose of the selected remedy. The new cap and upgraded
shallow ground water/leachate collection and treatment system,
are being implemented to further reduce and/or prevent the
migration of contaminants from the fill area into the ground
water and to maximize the capture and treatment of those
contaminants which have already reached the shallow ground water.
The additional pumping action could compromise those goals.

2. Location-Specific ARARs

No location specific ARARs with respect to this Site,
have been identified.

3. Action-Specific ARARs

a. 25 Pa. Code §§ 123.1 and 123.2 are applicable to
the Selected Remedy, and require that dusts
generated by earthmoving activities be controlled
with water or other appropriate dust suppressants.

b. To the extent that new point source air emissions
result from the implementation of the remedial
alternative, 25 Pa. Code § 127.l2(a)(5) is
applicable, requiring that emissions be reduced to
the minimum obtainable levels through the use of
best available technology (BAT), as defined in 25
Pa. Code § 121.1.

c. Treatment and discharge of contaminated leachate
and ground water to the Allegheny River will need
to comply with the requirements of Pennsylvania's
NPDES program. Those requirements as set forth in
25 PA. Code §§ 93.1 through 93.9, include design,
discharge, and monitoring requirements which will
be met in implementing the Selected Remedy and
will be examined during the Remedial Design phase.

d. 25 Pa. Code §§ 102.1 through 102.24 contain
relevant and appropriate standards requiring the
development, implementation, and maintenance of
erosion and sedimentation control measures which
effectively minimize accelerated erosion and
sedimentation.

e. Relevant and appropriate design requirements for
the cap are contained in 25 Pa. Code § 264.301.

f. 25 PA. Code § 264.310 contains standards for
closure and post closure for landfills including
final soil cover, grading, vegetation, maintenance

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and monitoring requirements, which are relevant
and appropriate for the Selected Remedy.

g. 25 Pa. Code §§ 105.291 through 105.314,
promulgated in part under the Pennsylvania Dam
Safety and Encroachments Acts of 1978, set forth
applicable design requirements relating to the
leachate/ground water treatment discharge
pipe/headwall construction.

h. The leachate and ground water collection and
treatment operations at the Site will constitute
treatment of hazardous waste (i.e., the leachate
contains hazardous waste), and will result in the
generation of hazardous wastes derived from the
treatment of the contaminated leachate ^i.e..
spent carbon filters from the air stripping
operation). The remedy to be implemented will
comply with the applicable requirements of 25 Pa.
Code Part 262 Subparts A (relating to hazardous
waste determination and identification numbers), B
(relating to manifesting requirements for off-site
shipments of spent carbon or other hazardous
wastes), C (relating to pretransport requirements;
25 Pa. Code Part 263 (relating to transporters of
hazardous waste); and with respect to operations
at the Site generally, with the substantive
requirements of 25 Pa. code 264 Subparts B-E, F
(in the event that hazardous waste generated as
part of the Selected Remedy is managed in
containers), J (in the event hazardous waste is
treated or stored in tanks), and K (in the event
hazardous waste generated as part of the Selected
Remedy is treated or stored in surface
impoundments).

i. The land disposal restrictions set forth at 40
C.F.R. Part 268 are applicable to the management
of hazardous wastes (including spent carbon
filters from the air stripping operation)
generated as part of the Selected Remedy.

j. 29 C.F.R. § 1910.170 sets forth applicable
requirements regarding worker safety in the
handling of hazardous waste.

k. 49 C.F.R. § 171.1-171.16 sets forth applicable
requirements regarding off-site transportation of
hazardous wastes.
•

1. The requirements of Subpart AA (Air Emission
Standards for Process vents) and BB (Air Emission
Standards for Equipment leaks) of the federal RCRA
regulations, 40 C.F.R. §S 264.1032 and 264.1052,
are relevant and appropriate for the air stripping
operations under the Selected Remedy. These
regulations require that total organic emissions
from the air stripping process vents must be less

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than 1.4 kg/hr (3 Ib/hr) and 2800 kg/yr (3.1
tons/yr).

m. Revised Procedures for Planning and Implementing
Off-Site response Actions (OSWER No. 9834.11
November 13, 1987), although not an ARAR is a
guidance developed by EPA which is to be
considered (TBC) in implementing the remedy.

Cost Effectiveness

Alternative 6 is cost effective in remediating the Site,
when compared to all other Alternatives. A detailed breakdown of
costs for all components of the Alternative is shown in Table 24.

TABLE 24
DETAILED COST SUMMARY - PREFERRED ALTERNATIVE
Item Cost

Cap/Drainage Structures $ 3,979,600
Leachate/Shallow Ground Water
Treatment System 842,700
Fence/Gate 90,900
Deed Restrictions 15.000

Subtotal-Capital Costs $ 4,928,200

Geotechnical Studies 300,000
Treatability Study 200,000
Contingency (20%) 985,600
Engineering (20%) 985,600
Construction Management (10%) 492,800
Administration/Legal (5%) 247.000

Total Capital Costs $ 8,139,200

Operation and Maintenance

Mowing $ 61,000
Ground Water Monitoring 49,300
Cap Inspections 6,400
Cap Repairs 3,000
O&M of Leachate/Shallow
Ground Water Treatment
System 409.100

Subtotal $ 528,900
Contingency (20 %) 105.800
Total O&M Costs 634,700

30 Year Present Worth O&M1 $ 5,983,300

Total Present Worth Project Costs $ 14,122,500
1/Thirty-year present worth at 10 percent interest.
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Preference for Treatment as a Principal Element

The Selected Remedy satisfies the statutory preference for
remedies that employ treatment as a principal element to
permanently reduce the toxicity, mobility, or volume of hazardous
substances. The Selected Remedy addresses the risks posed by the
leachate and shallow ground water associated with the Site
through the use of treatment technologies.

Utilization of Permanent Solutions and Alternative Treatment
technologies to the Maximum Extent Practicable

EPA has determined that the Selected Remedy represents the
maximum extent to which permanent solutions and treatment
technologies can be utilized while providing the best balance
among the other evaluation criteria. Of the alternatives that
are protective of human health and the environment, the selected
remedy provides the best balance in terms of long-term and short-
term effectiveness and permanence; cost; implementability;
reduction in toxicity, mobility, or volume of hazardous
substances through treatment; state and community acceptance; and
the statutory preference for treatment as a principal element.

XI. DOCUMENTATION OF SIGNIFICANT CHANGES FROM THE PROPOSED PLAN

The Proposed Plan for the Site was released for comment in
December 1991. The Proposed Plan described in detail the
alternatives studied in the Feasibility Study and identified
Alternative 6 as the Preferred Alternative. EPA reviewed all
written and verbal comments submitted during the comment period
and at the public meeting. Upon review of these comments, it was
determined that no significant changes to the remedy presented in
the Proposed Plan were necessary.
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RESPONSIVENESS SUMMARY

This community relations responsiveness summary is divided
into the following sections:

Section I Overview. A discussion of EPA's Preferred
Alternative and the public response to this
Alternative.

Section II Background of Community Involvement and Concerns.
A discussion of the history of community interest
and concerns raised during remedial planning
activities at the Lindane Dump Superfund Site.

Section III Summary of Major Comments Received During the
Public Comment Period and Agency Responses. A
summary of comments and responses categorized by
topic.

I. OVERVIEW

EPA's Preferred Alternative, Alternative 6, outlined in the
Proposed Plan, involves construction of a combination multi-layer
and clay and soil cap over approximately 18 acres of the Site,
upgrading the existing leachate/shallow ground water collection
and treatment system with discharge of the treated water to the
Allegheny River, deed restrictions on the whole Site and access
restrictions on part of the lower portion of the site, long-term
monitoring of the ground and surface water, and operation and
maintenance of the new cap and leachate/shallow ground water
collection and treatment system.

During the public comment period, the community supported
the remediation of the Site.

II. BACKGROUND OF COMMUNITY INVOLVEMENT AND CONCERNS

Public interest in the Lindane Superfund Site began in 1987
during the initiation of the Remedial Investigation under the
Consent Order between PADER and Pennwalt (now Elf Atochem). An
initial public workshop was held in November 1987 to discuss the
purpose of the Remedial Investigation and Feasibility Study and
to solicit public questions and concerns. The majority of the
public was concerned with potential impact to their drinking
water supply and the potential exposure to any contaminants which
were buried beneath the park area. After the public workshop,
public interest remained at a low level until the Proposed Plan
was released for public review in December 1991. A public
hearing was held on January 8, 1992 at the Harrison Township
Municipal Building. Approximately 50 residents along with
representatives of the Harrison Township Government, Allegheny
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Department PADER, EPA and Elf Atochem attended the hearing. The
concerns raised at the hearing are summarized in the following
section.

III. SUMMARY OF MAJOR COMMENTS RECEIVED DURING THE
PUBLIC COMMENT PERIOD AND AGENCY RESPONSES

1. The Pennsylvania Department of Environmental Resources has
concurred with the selection of Alternative 6 as the recommended
remedy.

EPA Response: No response required.

2. One resident asked what were the chances that their children
may develop cancer as the result of direct exposure to site
contaminants prior to them being covered up during the park
construction?

EPA Response: The current investigation did not examine previous
potential exposure cases. Without specific information as to
what substances were on the site prior to the park construction,
their concentrations, and times of potential exposure, it would
only be conjecture as to what probably exposure could have
occurred. Therefore, for EPA to place an estimate on any
potential chances of an increased risk of cancer or other health
effects without reliable information would not be reasonable. In
conjunction with this question, EPA has referred it to the Agency
for Toxic Substances and Disease Registry (ATSDR) for their
evaluation and possible response.

3. One resident questioned whether the EPA investigation
determined if DDT tailings were disposed of throughout the
Township?

EPA Response: The RI/FS done by Atochem under Pader and EPA's
oversight only centered on the Lindane Dump Site itself and did
not look beyond the known site. Our review of historical past
disposal information did not indicate that any DDT tailings were
taken to any other location.

4. One resident raised the question; if the RI/FS investigated
the white sand-like substances at the park and other places?

EPA Response: The investigation did not look at the white sand-
like substances as these were covered-up by the park construction
prior to the undertaking of the RI/FS investigation. We were not
aware of other locations during the RI/FS where these substances
were alleged to be placed.

5. One resident asked what is the timetable for remediating the
site?
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EPA Response: Once the Record of Decision ("ROD") has been
issued for the Site, EPA will issue Special Notice Letters to
those parties EPA believes are liable for remediating the Site.
These letters will ask the parties noticed to enter into
negotiations to reach an agreement with EPA to undertake the
Remedial Design/Remedial Action ("RD/RA") necessary as indicated
in the ROD to remediate the Site. The issuance of the Special
Notice letters will trigger a 60 day moratorium during which time
EPA can take no action at the Site. If at the end of the 60 day
moratorium no parties indicate their willingness to negotiate
with EPA to do the RD/RA, EPA has the option of then issuing an
administrative order to the parties to order them to peform the
RD/RA or EPA can use Superfund money to do the work ourselves and
then later seek reimbursement through a court action. If one or
more viable partiws agrees to enter into negotiations, EPA will
allow an additional 120 days for negotiations. If at the end of
that time period no agreement has been reached, EPA will have the
same options as above as if no negotiations had occurred.
Following either a negotiated settlement, administrative order,
or EPA using Superfund money, a design study will be done
followed by preparation of plans and specifications and bid
documents with appropriate EPA and PADER reviews during the
process. The project would then be bid and construction started.
Based on a best case scenario, the project construction could
begin as early as late 1993 or early 1994 with about a 2-year
period to complete all necessary construction phases.

6. One local citizen asked what will Pennwalt's (Elf Atochem)
liability be once the cap is in place?

EPA Response: Pennwalt or any other responsible party that
enters into an agreement with EPA or is ordered by EPA to
remediate the Site will be responsible for maintaining the cap,
operating and maintaining the new leachate collection and
treatment system and monitoring the ground water for a time
period of no less than 30 years after site construction is
completed.

7. One resident's, question was; what actions will be taken to
ensure that the liable parties maintain the Site after the cap is
in place?

EPA Response: Under any settlement agreement reached or EPA
administrative order issued, the liable parties will be legally
bound to undertake whatever maintenance and operation activities
are determined to be necessary at the Site to ensure continued
protection of human health and the environment.

8. One resident asked if there would be a risk of soil
contamination to the private residents after the cap is in place?
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EPA Response: The results of the soil samples taken from the
perimeter of the site during the remedial investigation did not
indicate levels' of contamination that would pose a health threat.
Capping the site will greatly reduce the infiltration of
precipitation which will prevent the migration of contaminants
from wastes landfilled at the site. Therefore, properties
bordering the site are not considered at risk for soil
contamination.

9. One resident asked whether soil samples were taken from the
residential area that borders the site, to what depth were
samples taken, and what contaminants were found in these areas?

EPA Response: The soil sampling conducted at the Lindane Dump
Site extended out to the site boundaries. Some of the bordering
residential properties were sampled during the sampling
activities. Generally only soil samples were collected but some
samples were collected at depths up to three feet. No
significant contamination was detected at the site boundary so
there was no need to sample further into the residential areas.

10. One resident questioned what the project boundaries in
relation to the surrounding neighborhood would be?

EPA Response: The project boundaries as currently defined would
include the Alsco Community Park property defined as the upper
portion of the site and the lower area belonging to Allegheny
Ludlum below the park down to Karns Road. The project boundaries
may extend further if additional contamination were to be found
beyond the existing area currently identified. However, based on
current information, this is unlikely.

11. A worker at the interim leachate collection and treatment
plant asked whether air samples were taken at the plant area and
did the air and surface soil samples results indicate that there
is a risk of airborne contamination at the site?

EPA Response: Air samples were collected at the site to
determine the presence and concentration of site-related organic
compounds in the ambient air. No significant concentrations
which could pose a threat to human health were detected. Soil
samples taken at and near the treatment plant were analyzed and
there were no significant concentrations of contaminants in the
soils which could pose a threat to human health if they became
airborne.

12. One resident raised the concern on what was the risk of
exposure to contaminants during construction .activities?

EPA Response: The construction activities will consist of
implementation of the cap on the site which is the remedial
alternative selected -by EPA. The capping alternative will
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require a minimum amount of excavation and therefore would pose a
minimal health risk to the residents. On-site air monitoring
will be done throughout the construction phases to ensure the
safety of local residents. In addition, contingency plans will
be prepared to address minimize any potential situations which
may pose health risks. Workers constructing the cap would also
incur a minimal health risk because Federal regulations which
will require them to have appropriate safety training, wear
protective clothing, use appropriate air monitoring equipment and
follow approved health and safety plans for all phases of the
construction.

13. One resident asked what is the risk of ground water
contamination in the area's residential wells?

EPA Response: Because the ground water from the Site flows out
toward the Allegheny River, only wells between the Site and river
would be at risk for ground water contamination. The Remedial
Investigation indicated that there are no current wells within
this area used for drinking water purposes. In 1990, the
Allegheny County Health Department tested residential wells
located upstream from the Site and the results indicated that no
Site contaminants were occurring in any of the residential wells.

14. One adjoining resident asked that since EPA only sampled to a
depth of three feet, is there a risk to residents whose homes
were built lower than three feet from the ground surface?

EPA Response: Both EPA and PAOER reviewed Site records and
historical photographs of the Site area. There was no indication
of any disposal in the areas now occupied by residential
structures.

15. One concerned citizen asked if the placement of the cap would
divert the ground water flow beneath the Site such that it would
bypass the leachate collection and treatment system?

EPA Response: The placement of the cap on the Site will not
change the direction of the ground water flow. Ground water will
continue to flow in the same direction towards the river. The
cap will only divert the precipitation from infiltrating the fill
areas.

16. One resident asked if there was a method to determine if all
the contaminated ground water is actually collected by the
leachate collection system?

EPA Response: Leachate is currently and will continue to be
collected by the existing subsurface drainage system that is
channeled directly to the leachate collection/treatment system.
Any contaminated ground water that is not collected by the
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drainage system and treatment plant is considered to be minimal.

17. One resident asked what is the fate of the water collected
from the leachate collection system?

EPA Response: The water that enters the leachate
collection/treatment is currently treated in the adjacent
granular activated carbon treatment system. The carbon treatment
system removes the contaminants from the leachate and then
disposes of the cleaned water by pumping it to the Allegheny
River. When the treatment process is upgraded as part of the
implementation of the entire remedial alternative, the effluent
released will meet the more stringent treatment standards which
will be imposed by the Commonwealth of Pennsylvania.

18. One resident questioned whether the river sampling conducted
by Harrison Township downstream of the Site at their water supply
intake indicated any contamination?

EPA Response: EPA reviewed the Harrison Township sampling data as
part of the Remedial Investigation and found that there were no
Site related contaminants in any of the samples taken.

19. One resident asked if contaminants leak down into the
underlying mineshafts and migrate to the river?

EPA Response: Based on the available information, it is possible
for some of the contaminants to leak into the underlying
mineshafts; however the majority of the contaminated ground water
goes directly to the leachate collection system and is therefore
treated prior to its release to the Allegheny River. Those
contaminants which do reach the river do not pose a threat to
anyone using the river either recreationally or as a drinking
water source. This was confirmed during the risk assessment
which took into account the contaminants that were found in both
the river water and sediments.

20. One resident asked what is involved with the natural
processes that will clean up the Site after the cap is in place?

EPA Response: The natural processes that will cleanup the ground
water are basically a combination of dispersion, dilution and
biodegradation.

As contaminant constituents move through the ground water, they
will tend to spread out from the path they are expected to
follow. This phenomenon is known as dispersion which dilutes the
contaminants. Once dispersed, microorganisms in the ground water
can then easily break down the diluted constituents via the
process of biodegradation. with the cap in place, the ability of
the contaminants to migrate into the ground water will be greatly
lessened and therefore will allow the microorganisms to more
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readily biodegradate the existing contaminants in the ground
water. This process will only address those contaminants which
migrate from the fill into the ground water. Those contaminants
which remain immobilized within the fill area will remain in
place with no definite timeframe for them to degrade.

21. One resident raised the question; will the Site monitoring
be continuous and will it include additional soil and water
samples?

EPA Response: EPA will require that monitoring of the ground
water downgradient of the Site be done on a regular basis to
ensure that the selected remedy continues to be protective
of human health and the environment. The monitoring program for
the ground water will be developed during the Remedial Design
Phase. However, no additional soil or surface water samples will
be taken as these media pose no unacceptable threat to any
receptors.

22. One resident asked how long will it take for the Site to be
safe for building houses?

EPA Response: It is EPA's intent to not allow any new
construction such as homes to be built on the Site. The purpose
of the cap is reduce and eliminate infiltration of water into the
fill area which will reduce or prevent migration of contaminants
into the aquifer below the fill area. Construction of homes or
similar structures over the cap would defeat the purpose of the
cap by potentially compromising the integrity of the cap layer.
As a part of the Remedial Action, EPA will require that deed
restrictions be placed on the Site which would prohibit any type
of construction or structures which would compromise the
integrity of the cap once it is in place or any other type of
activity such as excavation of other areas of the Site not capped
which could potentially expose hazardous waste.

23. One resident asked if the subdivision contractor who built
the homes could be contacted to determine where the fill material
originated from that was placed as fill material in conjunction
with the construction of the homes?

EPA Response: EPA and PAOER could not locate the former
contractor. Soils were tested in residential yards adjacent to
the Site during the RI and the results indicated that the soils
did not contain any contamination of any concern.

24. Atochem, previous Site owner and PRP for the Site, raised
the question of why the Preferred Alternative is identified as
only addressing ground water and leachate contamination and not
other media?

EPA Response: EPA has determined, that based on the results of

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the RI and Risk Assessment, that the only health-based threat
posed by the Site to potential future receptors is from ingestion
of the ground water which contains the contaminants benzene and
lindane which exceed their respective MCLs. The Preferred
Alternative will address this threat through the implementation
of the cap which in turn will reduce infiltration into the fill
layer which should reduce or eliminate the MCL exceedences. The
upgraded collection and treatment plant will treat the ground
water and leachate which is already contaminated and this in turn
will prevent the further migration of the contamination beyond
the current Site.

25. Atochem questioned the description of the Site stratigraphy
and ground water flow in the proposed plan as being insufficient.

EPA Response: EPA believes that the geological and
hydrogeological descriptions contained therein were sufficient
for describing the general conditions of the Site to the general
public. The public was further directed in the Proposed Plan to
review the Administrative Record at the Site repository if they
needed additional information. The Administrative Record
contains all documents which were prepared during the Site
investigation and relied upon by EPA in making it's
recommendation.

26. Atochem questioned the need for installation of additional
wells installed downgradient of the Site as part of the long-term
monitoring plan.

EPA Response: EPA believes the six wells already selected in the
FS may not provide sufficient monitoring data on the deep aquifer
to adequately address whether the selected remedy is completely
protective of human health and the environment. Therefore, EPA
believes that additional wells located further downgradient from
the Site may be necessary to provide adequate monitoring. A
final determination of well placement will be made during the
design phase.

27. Atochem feels that the EPA rationale for the Preferred
Alternative of the Combination Clay-Soil and Multi-layer Cap is
not warranted and that a Multi-layer Cap for the entire area to
be capped be constructed instead.

EPA Response: EPA believes that given the steep existing slope,
that only a clay-soil cap will be stable enough to construct on
the steeply sloped areas'due to potential slippage planes which
may occur as the result of the synthetic liner within the cap
layer. However, EPA will consider Atochem's position on the use
of the Multi-layer Cap for the whole area to be capped, if during
design studies, it can be proven that the potential slope
stability problems which could arise during and after the cap
construction will not threaten the integrity of the cap structure

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after its implementation and that the multi-layer cap if
implemented over the entire area to be capped will meet all
required performance standards.

28. Atochem disagreed with the language in the Proposed Plan
which indicated that the new treatment facility "would meet or
exceed the required effluent discharge limits that would be
established for this Site" Atochem contents that final proposed
effluent limits have already been established by PADER in a
letter to Atochem dated March 22, 1991.

EPA Response: EPA has conferred with PADER on this matter and
has included the proposed effluent limits per the March 22, 1992
letter from PADER to Atochem as final in the ROD.
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