PB98-963111
EPA 541-R98-043
September 1998
EPA Superfund
Explanation of Significant Difference
for the Record of Decision:
Osborne Landfill (ROD #2)
Grove City, PA
8/24/1998
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EXPLANATION OF SIGNIFICANT DIFFERENCES
OSBORNE LANDFILL SUPERFUND SITE
I. INTRODUCTION
SITE NAME: Osborne Landfill Superfund Site
SITE LOCATION; Pine Township, Mercer County Pennsylvania
LEAD AGENCY; U.S. Environmental Protection Agency,
Region III ("EPA" or the "Agency")
SUPPORT AGENCY: Pennsylvania Department of Environmental Protection
("PADEP")
Statement of Purpose
This explanation of Significant Differences ("ESD") is issued in accordance with Section
117(c) of the Comprehensive Environmental Response, Compensation and Liability Act, as
amended ("CERCLA"), and is now a part of the Administrative Record for the Osborne Landfill
Superfund Site ("Site"). This document explains significant differences to the remedy selected in
the Record of Decision ("ROD") for the Site signed by the Director of Superfund on December
30, 1997. This ESD makes changes to the ROD previously issued, which is attached as Exhibit
1.
II. SUMMARY OF THE SITE HISTORY, SITE CONDITIONS, AND SELECTED
REMEDY
The Osborne Landfill Site is located in Pine Township, Mercer County, Pennsylvania.
Located less than one mile east of Grove City, Pennsylvania, the Site encompasses
approximately 15 acres along the East Pine Street extension. Strip mining was conducted at the
Site during the 1940s prior to disposal of wastes in the strip mine pit. To the north of the Site are
woodlands. Farmland is present to the east and southeast across the East Pine Street Extension.
A large shallow pond is located just west of the Site and considered to be a federally protected
wetland. Another wetland is situated south of the Site on both sides of the East Pine Street
Extension. The immediate Site area is sparsely populated. Most of the residential homes near the
Site, are located along Enterprise Road, which is approximately 1/4 mile north of the Site, and to
the east on Diamond Road. Homes along Enterprise Avenue and Diamond Road previously used
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ground water, but Cooper Industries extended the municipal water line around the eastern
perimeter of the Site and connected any resident along the extension who was willing to accept
the connection.
Fill material was deposited into the strip mine pool at the base of the highwall from the
late 1950s to 1978, when the Site was closed by PADEP for not having a permit to accept
wastes. A wide array of wastes were disposed which contained metals, volatile organic
hydrocarbons, semi-volatiles and PCBs. The primary waste by volume was foundry sand.
Several Remedial Investigations have been conducted at the Site. These investigations
have focused on the fill area, the wetlands to the southwest of the Site, the Clarion Aquifer/Mine
Void system, the Homewood Aquifer System and the deeper Connoquennesing and Burgoon
Aquifers. These investigations documented contamination in the fill above EPA's action levels.
These investigations also documented contamination of ground water in the Clarion Formation
(primarily in the mine voids) with vinyl chloride above Maximum Contaminant Levels (MCLs)
allowed by the Safe Drinking Water Act. The wetlands to the southwest did not contain
contaminants at levels of concern.
The ROD #1 selected installation of a slurry wall around the perimeter of the Site, and a
clay cap to prevent infiltration into the fill. To prevent leachate from leaving the fill, extraction
wells were installed in the fill to remove leachate and to produce an inward hydraulic
containment. The collected leachate is treated by an iron and manganese removal system, air
stripping and carbon adsorption. The treated leachate is injected into the mine pool to the east of
the Site. ROD#l also selected pump and treatment as the remedy for contaminated ground water
in the Clarion Aquifer.
During the design phase, field work showed that it was not possible to remediate the
Clarion Aquifer as described in ROD#l. Aquifer response tests performed during the Remedial
Design indicated that reasonable ground water capture zones could not be created by extraction
wells placed in the Clarion Aquifer. Instead, very narrow columns of water would be drawn from
the more contaminated mine pool into the Clarion sandstone aquifer. EPA was also conducting
an investigation of the deeper aquifers at the Site, which are in communication with the shallow
aquifer. EPA decided to wait until the investigations were completed, so that an implementable
ROD for all Site ground water could be issued. A second Record of Decision(ROD#2) issued on
December 30, 1997, addressed all site ground water and the wetlands to the southwest of the
Site. The wetlands had not been impacted by Site contaminants and EPA selected "No Action"
for the southwest wetlands. EPA selected "Natural Attenuation with Monitoring" for the
contaminated Clarion aquifer and three years of ground water monitoring for the deeper
uncontaminated aquifers at the Site. In ROD#2, EPA specifically listed the wells that would be
monitored.
At the time that the Feasibility Study was completed for the Natural Attenuation with
monitoring ground water alternative, the slurry wall and clay cap had not been constructed. The
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construction of the slurry wall and cap necessitated the closure of some wells that would be
destroyed by the construction. After ROD#2 was issued, EPA was informed by Cooper
Industries that two of the wells on the list specified in the ROD had been abandoned because
their location interfered with the slurry wall and clay cap construction. The two wells which were
abandoned were MWV-2(mine void well adjacent to original east fence line) and MWC-3 (also
adjacent to the original east fence line). The slurry wall containment performance wells installed
as well nests C-2 and C-3 in the Clarion Aquifer are very close to the locations of the closed
wells in Clarion/Mine Void formation. These wells perform the same function as the wells that
were closed and are sampled periodically for Site contaminants. Therefore the removal of these
wells from the monitoring network does not significantly reduce the scope of the selected
monitoring program.
III. DESCRIPTION OF SIGNIFICANT DIFFERENCES
Subsequent to the issuance of ROD#2, EPA determined that minor corrections should be
made describing the remedies set forth in ROD#2. These changes are identified as Significant
Differences and do not constitute ROD amendments, as that term is used in 40 C.F.R. Section
300.435(c)(2)(H), to ROD#2. The Significant Difference between the remedies presented in the
ROD#2 and the change to ROD#2 that will be implemented is explained below. Except to the
extent changed by the section below, all of the terms of ROD#2 remain in effect.
RECORD OF DECISION ISSUED QN DECEMBER 1997
In ROD#2, EPA specifically listed the wells that would be monitored as part of the
selected remedy CM-2 (Natural Attenuation With Monitoring). At the time that the Feasibility
Study was developed for alternative CM-2, the slurry wall and clay cap had not been constructed.
The construction of the slurry wall and cap necessitated the closure of some wells that would be
destroyed by the construction. After the ROD#2 was issued, EPA was informed by Cooper
Industries that two of the wells on the list specified in ROD#2 had been abandoned because their
location interfered with construction. The two wells which were abandoned were MW-V2 (mine
void well adjacent to original fence line) and MWC-3 also adjacent to the original fence line. The
performance wells installed as well nests C-2 and C-3 are very close to the locations of these
closed wells and collect water from the Clarion Formation. Therefore the removal of wells MW-
V2 and MW-C3 from the monitoring network does not significantly reduce the scope of the
selected monitoring program. This ESD corrects the list of wells that will be monitored. As the
result of this change and a calculation mistake in the original cost estimate, the cost of the
remedial action has changed, and Cooper Industries has revised the cost sheet for CM-2 which is
attached. EPA has added the additional cost of the increased well testing required by the
ROD#2 for a total cost of $252,725. The detailed breakdown of the costs is attached.
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IV. PUBLIC PARTICIPATION
This ESD and and the information upon which it is based have been included in the
Administrative Record file for this Site. The Administrative Record also includes both RODs and
all documents that formed the basis for EPA's selection of the Remedial Actions for the Site. The
Administrative Record is available for public review at the locations listed below;
U.S. EPA, Region III
841 Chestnut Building
Philadelphia, PA 19107
and
Grove City Community Library
125 West Main Street
Grove City, PA 16127
Questions and comments on EPA's action and requests to review the Administrative
Record can be directed to:
Frank Vavra
Remedial Project Manager
Mail Code: 3HS22
U.S. EPA, Region III
841 Chestnut Building
Philadelphia, PA 19107
(215) 814-3221
VI. SUPPORT AGENCY REVIEW
The Pennsylvania Department of Environmental Protection has concurred with the
proposed changes to the remedial action in the proposed Explanation of Significant Differences
in a letter dated July 29, 1998.
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VII. affirmation of statutory determination
Considering the new information that has been developed and the changes that have been
made to the scope of the selected remedies, the EPA and PADEP believe that the revised remedy
remains protective of human health and the environment, complies with the Federal and State
requirements that are applicable or relevant and appropriate to this remedial action, and are cost
effective. In addition, the revised remedy utilizes treatment technologies that permanently and
significantly reduce the toxicity, mobility, or volume of the hazardous substances to the
maximum extent practicable for this Site.
Abraham Ferdas, Director
Hazardous Sites Cleanup Division
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A v A LMm" v IXV'^^ . J
4d uai
TABLE 4-1
ALTERNATIVE CM2 - NATURAL ATTENUATION WITH MONITORING
CLARION AQUIFER AND MINI VOID SYSTEM
OSBORN1 LANDFILL SITE
OPERABLE UNIT 2
FOCUSED FEASIBILITY STUDY
ITEM
QUANTITT
CAJPITAI. OOSTS
ANNUAL 0 * M
COSTS
PRESENT
WORTH
CO.V3TSUCTION
Well Inrtallaboo
1 Mooitonoe W«H
17,800
ENGimmm
Monitor Wall Tnir»ll»>»nn
1 Mooitorinc WtU
11,429
Mmutohac Co«u
9 W«Ua S»mi Aflnu*ily (1)
$19,840
*100,916
6 W«U» Quarterly (2)
9 W»Di Annually (S)
Annual lUpoct
tr>,43*
$43,990
Momiann« Wall Maiattnanca
is w«m
n ,m
I10.S44
Annul 0 * M. total
ns.m
Km Yaa* Ra*i«* (Pnaaat WoxtH)
114,976
CONSTRUCTION SUBTOTAL
*24,204
Htaltliiail Safety
ON
SO
Bid Cmtfi&ea&qr
ION
$J,420
Scap« coatmctacy
ISN
M.M1
construction total
~30,260
Penaimof * Lotml
6%
IL613
Stivicii Diuriflf Co&*troc£tt&
1%
ta.ua
TOTAL IMPLEMENTATION COST
WS.M8
Eafiaaano* k Daaira
ION
I3.IN
TOTAL CAPITAL COOTS
131174
TOTAL PRSSSNT WORTH
IXiZ.7fS
<1> MWV-1. MWV-3. HMV4, WN*. tl/SIM, MWC-4, MWM,
(2) MMM. MWV-4, HWtf-7. MWV-», K»W0. PlIW
(3) UpttaiwidemMwciiwiatwaamiMwinuatty. TlwMlutinuinbartobatampMmayafy tasadona
; and approval
Osborne fe costs.wk4
02X5/98, 02:38:42 PM
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