PB95-963130
EPA/ESD/R10-94/102
March 1995
EPA Superfund
Explanation of Significant Difference
for the Record of Decision:
Northwest Transformer/Mission
Pole Superfund Site, Everson, WA
12/22/1993
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EXPLANATION OF SIGNIFICANT DIFFERENCES
Site Name and Location:
Northwest Transformer/Mission Pole Super fund Site
Whatcom County, Washington
Lead and Support Agencies:
Lead Agency - U.S. Environmental Protection Agency (EPA)
Support Agency - Washington State Department of Ecology (Ecology)
Statute that recniires Explanation of Sicmificant Differences
(ESP):
Comprehensive Environmental Response, Compensation, and Liability
Act (CERCLA), Section 117(c) and National Oil and Hazardous
Substances Contingency Plan (NCP), Section 300.435(c)(2)(i).
A '
Introduction
The remedial action at the Northwest Transformer
Mission/Pole site in Whatcom County, Washington, is nearly
complete. The work is being performed in accordance with the
Amended Record Of Decision (ROD) dated September 30, 1991, and
the Consent Decree (CD) for Remedial Design/Remedial Action
(RD/RA) entered January 15, 1992, with one significant
difference. Since Section 117(c) of CERCLA requires that an
Explanation of Differences be published when any remedial action
is taken which differs in any significant respect from the Record
of Decision for the site, the purpose of this document is to
inform the public that the final two piles of excavated soil
containing 53 and 70 parts per million Polychlorinated Biphenyls
(PCBs), respectively, will be disposed of at a hazardous waste
landfill rather than by incineration.
This document also discusses the results of the
Environmental Protection Agency's (EPA) reassessment of the
selected remedy for groundwater (which was and remains no further
action) in light of sampling results and the apparent removal of
the source of groundwater contamination during remediation.
Summary of Site History, Contaminants, and Selected Remedy
The site consists of approximately 1.6 acres in Whatcom
County, Washington, which was used from'1958 to 1985 by Northwest
Transformer, Inc. for a transformer repair and salvage operation.
In the course of these activities, soils and a barn on-site were
contaminated with polychlorinated biphenyls (PCBs) . EPA
conducted a removal in May 1985 during which transformers, drums,
containers and soils were removed for off—site disposal. The
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most significant contamination was found in the southeast portion
of the site in the vicinity of an old dry well or seepage pit.
The site was listed-on the National Priorities List in 1985,
after which EPA conducted a Remedial Investigation/Feasibility
study (RI/FS) to determine the nature and extent of contamination
and evaluate cleanup alternatives. The RIfFS demonstrated that
PCBs remained on site in soils at levels which, if left
unaddressed, posed an unacceptable risk to public health and the
environment. On September 15, 1989, EPA selected in situ
vitrification (ISV) as the remedy for soils at the site and
required additional study of groundwater and the barn at the
site. However, since ISV was an innovative technology and not
yet commercially available, the ROD required that a treatability
study (TS) be done to test the remedy before attempting full-
scale implementation.
At the time the ROD was signed, the NW Transformer Company
was out of business and could not perform the necessary work.
Their customers, who are also Potentially Responsible Parties
(PRPs) under the law ~$ generators of hazardous wastes, agreed to
conduct the treatability study under an Administrative Order on
Consent signed in February 1990. .
,
The TS was formally completed in April of 1991, after
successfully demonstrating that ISV would be effective. for the
contaminantS and conditions at the site. However, the TS also
revealed that the unit cost of ISV was several times higher than
the ROD estimate had been, due to hiqh mobilization costs, an .
increase in the vendor's price for ISV, and other factors. The
availability of a full-scale ISV unit Was also identified as a
problem, since the. vendor had yet to perform a successful full-
scale test of ISV due to scale-up problems.
In response to those concerns and PRP requests, EPA agreed
to allow the PRPs to conduct a Remedial Design Soil Sampling
Program in February, 1991, to better characterize the soil
contamination. Based on the samplinq, the PRPs determined that
the extent and level of soil contamination was less than the RI
had shown. Based on that information, the treatability study and
the problems with ISV, the PRPs argued in favor of a change to
the selected remedy for soils. The PRPs also proposed to forgo
detailed characterization of the barn in favor of removal and
disposal at an approved hazardous waste disposal facility in.
conjunction with soil remediation.
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On September 30, 1991, after consideration of public comment
and with Ecology concurrence, EPA amended the 1989 ROD to change
the remedy for soils and select final remedies for the barn and
ground water. The amended remedy for soils and the barn.
consisted of excavation, removal and disposal of soils containing
1 or more ppm PCBs. Soils with 50 or more ppm were to be
disposed of by incineration, while soils with less than 50 ppm
PCBs were to be landfilled at an approved hazardous waste
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facility. The final outcome of the selected remedy was
condition~l: if all soils with ~ 1 ppm down to 15 feet and all
soils ~ 10 ppm below 15 feet are shown to be removed, no further
site restrictions will be required; if some soils between 1 and
10 ppm are shown to remain near the surface, a fence and long-
term maintenance and monitoring program will be required.
For Groundwater, the original 1989 ROD selected only
monitoring since the RIfFS had not fully characterized the
groundwater. Three rounds of sampling were conducted in off-site
and on-site perimeter wells and no PCB contamination was detected
through August 1991. The amended ROD called for continued.
monitoring during RDfRA, after which, if no PCBs were detected,
no further action would be reqUired for groundwater.
Remedial Design was completed in early March, 1993, and on-
site preparations for Remedial.Action began March ~5, 1993. By
the end of April tl).e barn had been removed and excavation of
contaminated soil was proceeding as planned and thought to be
mostly complete. However, the extent of contaminated soil in the
deeper area of the se~page pit turned out to be much greater than
RD sampling had revealed. Instead of'15 feet below the surface,
the excavations eventually extended 42 feet below the surface
before all contamination above cleanup levels was removed.
. As of December 17, 1993, all contaminated material above
cleanup levels had been excavated and was in theflnal stages of
off-loading and disposal. Over 4,000 tons of soil contaminated.
with 50 or less ppm PCBs has been landfilled at an approved
hazardous waste facility. Using the average concentration of 20
ppm, approximately 166 lbs of PCBs have been landfilled (the
basis for this value and other calculations are given fully in
the administrative record and summarized on Attachment A).
Approximately 265 tons of soil contaminated with 50 or more ppm
PCBs have been sent to an off-site incinerator for disposal.
About one-third of the soils conta~ned in excess of 250 ppmPCBs
with .hot spots as high as.5,000ppm. Based on the average
concentration of 156 ppm, approximately 137.5 lbs of PCBs from
soils have been incinerated. In ad~ition to the treated soils,
550 gallons of highly PCB-contaminated water and "scum" (with
concentrations up to 39,000 ppm) captured during the excavations
have also been treated by incineration in accordance with PCB.
disposal regulations.
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The last two stockpiles of contaminated soil on site. are
addressed iri this ESD. They include about 70 tons of soil at an
average concentration of 62 ppm PCBs which are scheduled for off-
loading and disposal at a approved hazardous waste landfill
between Decmber 22nd and 28th, 1993. These soils represent
approximately 8.6 lbs of PCBs.
Following final disposal of stockpiled soils, site grading
is scheduled for early January 1994 and planting of grass-seed in
the spring.
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Description of Siqnificant Differences and Basis for those
Differences
&..
SOILS
Impl~mentation'of the soils remedial action occurred under
different conditions than anticipated. The depth of
contamination was determined to extend much deeper than
originally anticipated (42 feet below ground rather than 12.5
feet) and the levels of PCB were much higher than anticipated.
The hot spot contained PCB-contaminated soil with concentrations
well over 500 ppm and in one place as high as 5,000 ppm. As a
result of these conditions and actions, much more PCB-
contaminated soil has been removed and 'incinerated than was
originally anticipated as, described below ,(see attachment A for
calculations) and an unconditional soil cleanup has been
accomplished.
The volume of soil from the seepage pit contaminated with 50
or more ppm PCBs incr~ased from an original estimate of less than
100 tons to over 530 tons~ This ESD covers 70 tons of that
material containing an average of 62 ppm PCBs which will be
transported to an approved hazardous waste landfill for disposal.
The remaining 460 tons of material was screened to segregate
relatively clean (based on confirmation sampling) cobbles'and
gravel from more contaminated soils. After screening the
segregated material was tested and disposed of in accordance with
the amended ROD. Over 265 tons of soil containing concentrations
ranging from 50 to over 5,000 ppm PCBs have been shipped for
incineration. The remaining so~l, cobbles, and rocks have been
disposed of at an approved hazardous waste landfill. Even with
this ESD, the cost of the remedial action increaseq.more than
$1,000,00,0 (from about $3,000,000 to over $4,000,0(0) due to the
additional excavations and incineration.
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The subject of this ESD is the last two stockpiles ,
(approximately 70 tons) of soil on site which were awaiting -
disposal as of 12/21/93. One pile contained soil with an average---
concentration of 53 ppm PCBs and the other 70 ppmPCBs. These
two piles contain approximately 3% of the total weight of PCBs
which met the ROD threshold for incineration (> 50 ppm), or
approximately 8.6 lbs of PCBs out of a total of 257.6 lbs. The
stockpiled soils therefor~ represent a substantially different
threat to the environment because of the lower average
concentration (62ppm vs several hundred ppm) and maximum
concentration (70 ppm vs over 5,000 ppm).
One of the factors which EPA considers when evaluating
alternative remedies is the cost effectiveness reiative to any
incremental increase in protectiveness. In this case, the unit
cost of incineration is ten times the cost of landfilling
($1,600/ton for incineration versus $160/ton for landfilling).
This tenfold increase is warranted for highly contaminated
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material, but becomes less compelling for lower concentrations of
PCB-contaminated soils.
EPA is allowing the two remaining piles of soil to be
disposed of at a hazardous waste landfill rather than by
incineration because of the following factors:
the extensive excavation and disposal of over 4,000
tons of contaminated soil to date;
the incineration of 265 tons of contaminated soil
including PCB concentrations up to 5,000 ppm;
confirmation that the remaining 70 tons of soil contain
70 or less parts per million PCBs;
the ability to protectively dispose of stockpiled soils
in a Toxies Substances Control Act permitted facility
the substantial increase in soil requiring disposal;
and, .
the disproportionate cost of
stockpiled soils relative to
by incinerating soil at such
incineration of the
the limited benefit gained
low concentrations.
As described in the previous section, the Amended ROD
provided for unconditional and unrestricted site use if the soil
performance standards were met. The Amended ROD also provided
for a more limited removal of soils in conjunction with certain
institutional controls. During site remediation the PRPs chose
to continue to excavate despite the considerable increase in soil
volume in an effort to completely attain the performance
standards, which they accomplished. Confirmation sampling has
shown that once the final. contaminated soil stockpiles are
removed from the site and disposed of, the site will meet all CD
and ROD performance standards for soils. No further restrictions
to prevent contact with site soils will be required.
B.
Groundwater
During Remedial Design, an additional pair of deep and
shallow groundwater wells was placed in the middle of the site.
(adjacept to and downgradient of the seepage pit). Those wells
were sampled along with off-site and perimeter wells 3 times
during remedial design. During those sampling rounds no
contamination was detected in the off-site or perimeter wells,
however, the new shallow well (screened at about 30') was found
to contain PCBs at 1-2 parts per billion (ppb), which exceeded
both the Maximum. Contaminant Level of 0.1 ppb and the practical
quantitation limit established for this site at 0.5 ppb.
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According to the Amended ROD, sinc~ contaminants above the
PQL were detected in two rounds of sampiing, EPA was required to
determine what, if any, further action was necessary for
groundwater. As a result, in December 1992, EPA determined it
would be necessary to con~inue groundwater monitoring until
completion of the remedial action.
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After evaluation of the sample results from the groundwater
monitoring program as required by the Amended ROD, EPA has
determined that no further action is still the appropriate remedy
for groundwater. Since the contaminated soil-excavated from the
seepage pit was found immediately upgradient from and at the same
depth as the one on-site well in which PCB contamination;has been
found, the Remedial Action for soils is believed to have
addressed the source of the groundwater contamination. Periodic
groundwater monitoring will be for as long as is necessary to
determine with confidence that the source of groundwater
contamination has been removed. Once EPA makes that
determination, the site will be.delisted and no further reviews
will be conducted, since the site will be deemed to meet all
requirements of the consent decree for a non-conditional cleanup
and the NCP requirements for delisting.
Summary of SUPPort Aqencv Comments
The Department of Ecology for the State of Washington was
consulted on this matter. They confirmed that disposal at an
approved hazardous waste facility was compatible with the state
Dangerous Waste Regulations, Chapter 173-303 WAC, specifically
Section 071 which provides for this type of material. A copy of
the letter encouraging EPA to approve the PRPs request to dispose
of the remaining soils by landfilling is attached. Ecology .
concurred with the decision to allow landfillinq of the final two
piles of soil because of the extensive and successful remedial
action taken so far, the increased scope of the project and the
protectiveness offered by landfilling soils with 70 or less ppm
PCBs relative to the substantial cost and limited additional
protectiveness offered by incineration in this situation.
Public Participation Activities
A public notice is being published in the Bellingham Herald
and the Lynden Tribune. . This document and the supporting.
documents have been added to the Administrative Record.
Affirmation of the Statutory Determinations
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The amended ROD and Remedial Action for the Northwest
Transformer/Mission Pole Superfu,nd site remains protective of
human health and the environment, .complies with Federal and State
requirements that are applicable or relevant and appropriate-to
this remedial action, and is cost effective.
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Date
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NWT M/P ESD Attachment A
page 1. of 2
NORTHWEST TRANSFORMER (MISSION/POLE) SITE
ESD BACKGROUND DATA
1.
Stockpiled Soils Addressed in this ESD
A) Approximate weight of 2 uncommingled stockpiles: 70 tons
B) Average PCB concentration in subject stockpiles P0920-5 (70
ppm) and P0920-6 (53 ppm): 62 ppm
C) Estimated weight of PCBs in subject stockpiles: 8.6 lb
-Based on 70 tons at 62 ppm and 2 X.10-3Ib PCB/ton soil
2.
Soils Contaminated with 50 or more ppm PCBs
a) Approximate total weight of excavated (unscreened) soil with
~50 ppm PCBs: . 530 tons
-Based on: ... .
o 93 tons sent to APTUS inc1nerator last June
o 70 tons in uncommingled stockpiles P0926-5 AND -6 .
o 367 Tons of commingled soil in stockpi~e and rolioffs
prior to screening
b) Approximate weight of rocks and cobbles screened out of
excavated soil: 265 tons
(this material has been tested after screening and
shown to contain an average of .30 ppm PCBs. It is
being disposed of at a TSCA-approved la~dfill]
c) Approximate weight of soil with ~50 ppm PCBs sent to APTUS
incinerator: 265 tons
-Based on:
o 93 tons sept to APTUS last June;
o 172 Tons of commingled soil remaining in stockpile
and rolloffs after screening out rocks and .//
cobbles.
d) Estimated average
soil with ~50 ppm
-Based on data in
October 13, 1993
PCB concentration of excavated, .commingled
PCBs prior to screening: 156 ppm
Table A-4 of Perkins coie letter dated
e} Estimated weight of PCBs in excavated, commingled soil with
~50 ppm PCBs: 165 lb
-Based on 530 tons at 156 ppm and 2X10-31b PCBs/ton soil
f} Estimated weight of ~CBs in soil sent to APTUS: 137.5 lb
-Based on 265 tons at 156 ppm and 265 tons at 30ppm
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NWT HIP ESD Attachment A
page 2 of 2
.h.
soils Contaminated with less than 50 ppm PCBs
a) Approximate weight
-Based on:
o 2,100
o 1,200
o 390
o 66
of soil landfilled: .,150 tons
o
o
tons sent to Arlington (6/93)
tons sent to Arlington (7/93)
tons sent to Arlington (10/93
Tons >1/4-inch gravel screened
commingled soil stockpile and
rolloffs
324 Tons surficial scrape and final
70 Tons in uncommingled stockpiles
(based on this ESD)
out of
site cleanup
P0926-5 and -6
b) Estimated average PCB concentration in landfilled soil
landfilled: 20ppm
c) Estimated weight"of PCBs in landtilled soil: 166lb
-Based on 4,150 tons at 20 ppm and 2x10-3lb PCB/ton-
soil -
4.
Costs
a} Approximate average cost for soil transportation/disposal at
APTUS incinerator: $1600/ton
b) Approximate cost for soil transportation/disposal at
Arlington-landfill: $160/ton
c) Incremental cost per ton for incineration versus landfilling
= $1600-160 = $14401ton-
d) Incremental cost of incinerating versuslandfilling 265 tons
of <1/4-inch soil with ~50 ppm PCBs = 265 x $1,440 =
$382,000
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