PB96-963103
EPA/ESD/R08-96/117
June 1996
EPA Superfund
Explanation of Significant Difference
for the Record of Decision:
Wasatch Chemical Company,
(Lot 6) Salt Lake City, UT
11/30/1995
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PB96-963103
EPA/ESD/R08-96/117
June 1996
EPA Superfund
Explanation of Significant Difference
for the Record of Decision:
Wasatch Chemical Company,
(Lot 6) Salt Lake City, UT
11/30/1995
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EXPLANATION OF SIGNIFICANT DIFFERENCES
WASATCH CHEMICAL SUPERFUND SITE - SALT LAKE CITY, UTAH
NOVEMBER 1995
DECLARATION
Considering the new information that has developed and the changes that have been made to the
selected remedy chosen in the record of decision dated March 29, 1991, EPA and UDEQ believe that
the remedy remains protective of human health and the environment, complies with Federal and State
requirements that are applicable or relevant and appropriate for this remedial action, and is cost
effective. In addition, the revised remedy utilizes permanent solutions and alternative treatment
technologies to the maximum extent practicable for this site.
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/so/ 7^
Max H. Dodson Date
Assistant Regional Administrator
Office of Ecosystems Protection and Remediation
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EXPLANATION OF SIGNIFICANT DIFFERENCES
WASATCH CHEMICAL SUPERFUND SITE - SALT LAKE CITY, UTAH
NOVEMBER 1995
INTRODUCTION
The U.S. Environmental Protection Agency (EPA) has prepared this Explanation of Significant
Differences (ESD) to document the differences between the remedy selected in the Wasatch Chemical
Superfund Site Record of Decision (ROD), issued by EPA on March 29, 1991, and the remedy
described herein, which will be implemented at the site.
The changes to the ROD have been made as a result of new information that EPA received
subsequent to the issuance of the ROD. These changes do not fundamentally alter the sitewide
remedy presented in the ROD. The sitewide remedy for the site remains protective of human health
and the environment. EPA is the lead agency at the site, with support provided by the Utah
Department of Environmental Quality (UDEQ) under a site-specific enforcement agreement.
This ESD is prepared in fulfillment of EPA's public participation responsibilities under Section 117(c)
of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, 42 U.S.C.
Section 9601, et seq. (CERCLA), as amended by the Superfund Amendments and Reauthorization Act
of 1986 (SARA), and Section 300.435(c)(2)(i) of the National Oil and Hazardous Substances
Contingency Plan (NCP), 40 Code of Federal Regulations (CFR) Part 300. These laws and
regulations require EPA to publish an ESD when the remedy to be implemented differs significantly
from the remedy described in the ROD.
This ESD will address two changes in the remedial action, modification of the site boundary and
deletion of the requirement that all unpaved areas of the site be paved. Results of additional
investigations conducted after the ROD was signed have further defined the extent of groundwater
contamination, necessitating a change in the site boundaries. As an extra precautionary measure, the
ROD required that all unpaved areas of the site be paved to prevent future occupants from direct
exposure to and ingestion of residual contaminants that may remain on site. This component of the
remedy is unnecessary. Both of these modifications will be explained in detail in other sections of
this ESD.
This ESD provides a brief history of the site, describes the remedy selected in the ROD, and explains
the ways in which the remedy described herein differs from the remedy selected in the ROD. It also
summarizes the support agency's comments on the changes to the remedy and discusses compliance
with all legal requirements.
The administrative record which contains this ESD and the documentation supporting it is available
for.public review at the following locations:
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EPA Superfund Records Center
999 18th Street, Fifth Floor
Denver, Colorado 80202
Hours: Monday-Friday 8:00am - 4:30pm
Telephone: (303)312-6473
Utah Department of Environmental Quality
Division of Environmental Response and Remediation
168 North 1950 West, First Floor
Salt Lake City, Utah 84116
Hours: Monday-Friday 8:00am - 5:00pm
Telephone: (801)536-4479
Salt Lake City Public Library
Chapman Branch
577 South 900 West
Salt Lake City, Utah 84104
Hours: Monday-Thursday 10:00am - 8:00pm
Saturday 10:00am - 6:00pm
Telephone: (801) 524-8285
SUMMARY OF SITE HISTORY, CONTAMINATION PROBLEMS, AND SELECTED
REMEDY
The Wasatch Chemical site is located in an industrial area of Salt Lake City, Utah, near the
intersection of 700 West and 2100 South Streets (Figure 1). The Wasatch Chemical property is
currently owned by Entrada Industries, Inc. (Entrada). The site comprises approximately 18 acres
and is in an area of light and heavy industries, including an automobile dealership, a steel fabrication
facility, a former food distribution facility, and a railroad yard. The site encompasses three areas.
The first area is Lot 6, which is a largely undeveloped section on the northern portion of the
property. The second area consists of portions of Lots 2 and 3 and all of Lots 4 and 5. The third
area consists of adjoining parcels surrounding the site, including the Steelco property owned by Alta
Industries, Inc. to the north of Lot 6, and the property owned and operated by the Denver and Rio
Grande Western Railroad Company (DRGWR) to the east of the site.
Between 1957 and 1971, the site was used for warehousing, producing, and packaging industrial
chemical products. Between April 1970 and April 1971, operations at the site were expanded to
include the manufacture of fertilizers. In April 1973, Wasatch Chemical Company (Wasatch
Chemical) constructed a liquid and dry pesticide formulation building. From approximately 1973
until June 1978, Wasatch Chemical formulated, blended, and packaged various chemical products at
the site, including pesticides, herbicides, fertilizers, industrial chemicals, and cleaners.
In June 1978, Entrada sold its agricultural chemical and industrial chemical and cleaner businesses.
The agricultural business was moved off-site; the industrial chemical business, purchased by Great
Western Chemical Company, continued to operate to a limited extent on-site through August 1992.
EPA placed the Lot 6 portion of the site on the National Priorities List (NPL) on February 11, 1991.
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Contamination at the site has been divided into three categories: source areas, soils, and groundwater.
The source areas include the process drain system (including the former evaporation pond), yard drain
system, and septic system on Lot 6. Dioxin waste consolidated during the removal action conducted
by EPA in 1986 constitutes the remainder of the source material. Soil contamination at the site is
widespread and consists of herbicides, pesticides, dioxins, volatile organic compounds (VOCs) and
semivolatile organic compounds (SVOCs). Soil contamination is the result of numerous spills, run-off
accumulation in topographic low points, and transport of contamination from source areas. .
Groundwater contamination is also widespread at the site and consists of VOCs, SVOCs, herbicides,
and pesticides. The source of groundwater contamination is believed to be due to the transport of
contaminants from the sources areas, particularly the process drain lines and evaporation pond.
The major components of the selected remedy, as presented in the ROD, include the following:
• Excavation of all soils containing indicator chemicals above action levels, sludges from the
yard and process drain systems, the septic system, and consolidation of these contaminated
materials and dioxin removal wastes (approximately 3,587 cubic yards of soils and sludges
and 650 gallons of liquid waste) in the former evaporation pond;
• Treatment of staged soils, sludges, and dioxin removal wastes by thermal destruction of
contaminants through in-situ vitrification;
• Excavation and landfarming of approximately 1,111 cubic yards of hydrocarbon-contaminated
soils;
• Surface sealing by asphalt paving;
• Extraction of on-site contaminated groundwater until maximum contaminant levels (MCLs)
and proposed MCLs are met, and treatment, to the extent necessary, of extracted groundwater
by air stripping to meet publicly owned treatment works or Utah pollution discharge
elimination system standards;
• Disposal of any residuals remaining from the treatment of groundwater at an off-site
hazardous material disposal facility; and,
• Implementation of institutional controls such as deed restrictions, denial of well permits, or
acquisition of water rights, as practicable and to the extent allowable by law.
DESCRIPTION OF THE SIGNIFICANT DIFFERENCES AND THE BASIS FOR THOSE
DIFFERENCES
The changes memorialized in this ESD are based on new information that EPA received subsequent to
the issuance of the ROD. EPA determined that the information supports the need to correct and/or
clarify certain aspects of the remedy described in the ROD. These changes do not fundamentally alter
the overall approach of the sitewide remedy or any individual component of the sitewide remedy.
Site Boundary. The site is described in Section 1.0 of the ROD as those areas where contaminants
from site activities may have been placed or may have migrated. On this basis, the boundaries at the
time die ROD was signed were delineated as follows: to the east, the tracks of DRGWR; to the
south, 2100 South Street; to the west, 700 West Street; and to the north, a line of demarcation
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extending across the Steelco property at a distance of 80 feet from the northern edge of Lot 6 (Figure
1). The ROD also states that the boundaries of the site may be adjusted if contaminants from site
activities are found to have been placed or to have migrated to areas outside these boundaries.
Entrada performed a groundwater investigation for remedial design/remedial action (RD/RA)
consistent with the EPA and UDEQ statement of work dated November 5, 1991. This investigation
was performed to obtain information to supplement the technical data collected during the remedial
investigation. The objective of the investigation was to characterize the sources, nature, and extent of
groundwater contamination underlying the Steelco property and groundwater contamination underlying
the Wasatch Chemical site.
The results of that additional investigation indicated that groundwater contamination extended past the
site boundaries described in the ROD. Based on the results of the investigation, the eastern and
western boundaries of the site remain unchanged, but the northern boundary has been extended to
coincide with the DRGWR rail spur in the south-central portion of the Steelco property.
Additionally, it has been determined that contaminants from site activities have not been placed on or
migrated to the Mega Foods property on the southern boundary of the site. Therefore, the southern
site boundary now excludes the Mega Foods property. In summary, the site boundaries, which .
include the areal extent of contamination, are as follows: to the east, the tracks of the DRGWR; to the
south, 2100 South Street excluding the Mega Foods property; to the west, 700 West Street; and to the
north, the DRGWR rail spur in the south-central portion of the Steelco property (Figure 2). The
remedial action for the site will treat groundwater across the areal extent of contamination.
Asphalt Paving. The selected remedy for soils, sludges, and dioxin waste presented in the ROD
included, in part, excavating soils containing indicator chemicals above soil action levels, and paving
all unpaved areas of the site to prevent direct exposure to and ingestion of residual contaminants that
may remain in soils on-site by future occupants.
Surface soil containing indicator chemicals above soil action levels have been excavated and
consolidated for treatment. The paving component of the selected remedy is unnecessary based on the
following:
• The ROD already requires unpaved areas to be cleaned up to risk-based levels selected to
protect future occupants from unacceptable health risks; paving is thus unnecessary to meet
the remedial action goal for soils presented in the ROD.
• Surface soils above soil action levels have been removed from the existing unpaved areas of
the site.
• Asphalt paving will significantly increase the amount of stormwater discharged to the 700
West Ditch and given the size of the site, may require enlargement of the municipal
stormwater control system, and increase the potential for flooding, in the area.
SUPPORT AGENCY COMMENTS
UDEQ concurs with the remedy changes presented in this ESD.
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AFFIRMATION OF THE STATUTORY DETERMINATIONS
Considering the new information that has been developed and the changes that have been made to the
selected remedy, EPA and UDEQ believe the remedy: remains protective of human health and the
environment; complies with applicable or relevant federal and state requirements appropriate to this
remedial action at the time the original ROD was signed; and, is cost effective.
PUBLIC PARTICIPATION ACTTVTnES
Notice is hereby made that this ESD and its supporting documentation is available for review through
the administrative record file located at the above listed locations.
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EXPLANATION OF SIGNIFICANT DIFFERENCES
WASATCH CHEMICAL SUPERFUND SITE - SALT LAKE CITY, UTAH
NOVEMBER 1995
DECLARATION
Considering the new information that has developed and the changes that have been made to the
selected remedy chosen in the record of decision dated March 29, 1991, EPA and UDEQ believe that
the remedy remains protective of human health and the environment, complies with Federal and State
requirements that are applicable or relevant and appropriate for this remedial action, and is cost
effective. In addition, the revised remedy utilizes permanent solutions and alternative treatment
technologies to the maximum extent practicable for this site.
Max H. Dodson Date
Assistant Regional Administrator
Office of Ecosystems Protection and Remediation
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