PB95-963112
EPA/ESD/R08-94/090
February 1995
EPA Superfund
Record of Decision Amendment:
Sharon Steel Site
(O.U. 2), Midvale, UT
6/23/1994
-------
EXPLANATION OF SIGNIFICANT DIFFERENCES
SHARON STEEL (OU2) SUPER.PtJND SITE - HIDVALE, UTAH
June 1994
INTRODUCTION'
This document explains the significant differences between
the remedy selected in the Record of Decision (ROD), signed by
the U.S. Environmental Protection Agency (EPA) in. 1990, and the
implemented remedy at the Sharon Steel Operable Unit 2 (OU2)
Superfund Site in Midvale, Utah (Site). The Utah Department of .
Environmental Quality (UDEQ) is the lead agency for OU2 and is
conducting the Remedial Action under a ~ooperativ~ Agreement, .
. with the EPA assisting as the support agency..
Under Section 117(c) of the Comprehensive Environmental
Response, Compensation and Liability Act of 1980 (CERCLA or
Superfund), as amended by the Superfund Amendment and
Reauthorization Act of 1986 (SARA), 42 U.S.C. ~ 9617(c), EPA is
required to publish an Explanation of Significant Differences
(ESD) when significant, but not fundamental changes are proposed
. to the previously selected. site remedy. The National Contingency
Plan (NCP) sets forth the criteria for issuing an ESD and
requires that an ESD be.published if a remedial action is taken
which differs significantly in either scope, performance, or .cost
from the remedy selected in the ROD for the site.
EPA regional toxicologists conducted a review of the past
scientific rationale for the action level of 200 parts per
. million (ppm) for lead-contaminated garden soils presented in the
Baseline Risk Assessment and have determined that residential
properties with garden soils having lead concentrations between
200 ppm and 500 ppm lead do not present significantly different
. health risks. when compared to garden soils having lead
concentrations of 500 ppm:Therefore, garden soils outside the
500 ppm lead/70 ppm arsenic boundary will not be remediated to
below 200 ppm lead and will not be subject to institutional
controls.
The Site is currently in the remedial action phase of the
Superfund cleanup process. Based on new information obtained
after the signing of the ROD, the EPA and UDEQ have limited the
scope and cost of remedial action by reducing the volume of lead~
.contaminated garden soils to be excavated and/or subject to .
.institutional controls to.only those possessing lead
concentrations greater than 500 parts per million (ppm) and/or
arsenic concentrations greater than 70 ppm. This change in the
remedial action has resulted in the need for this ESD.
1
-------
This ESD provides a brief history of the Site, describes the
original remedy selected in the ROD, and explains how the
modified remedy differs from the original. It also discusses the
modified remedy's compliance with all legal requirements and
provides details on how the reader may obtain more information on
the modified remedy. .
This document also presents a brief overview of information
relating to the Site. This ESD and its supporting documentation
will be incorporated into the Administrative Record for the Site.
The Administrative Record file is available for public
review at the following locations:
~~
Ruth Vine Tyler Library .
3~5 Wood St., Midvale, UT 84047
Hours:
Monday-Thursday: 9:00 am-9:00.pm
Friday & Saturday: 9:00 am-5:30 pm
2.
Utah Department of Environmental Quality
Division of Environmental Response and Remediation
~68 North ~950 West, ~st Floor
Salt Lake City, UT 84~~6
. HQurs:
Monday~Friday: 8:00 am-5:00 pm
EPA Superfund Records Center
999 ~8th Street, Fifth Floor
Denver, CO 80202
Hours:
Monday-Friday: 8:00 am-5:00 pm
3.
SUMMARY OF SITE HISTORY. CONTAMINATION PROBLEMS AND
THE SELECTED REMEDY .
The Sharon Steel (OU2) Superfund Site is located in Midvale,
utah, encompassing part of the City of Midvale and surrounding
areas. The Site is bounded on the west by the Sharon Steel (OU~)
Site, on the north by 7200 South Street, on the east by a line
one or two blocks east of Interstate Highway ~5, and on the south
by newer residential and commercial areas. .The exact boundaries
of the Site have been defined during Remedial Design as
. properties where lead concentrations exceed 500 ppm.
The land south and west of Midvale is used primarily for
agricultural and commercial activities while land to the north
and east is mostly urban. Approximately 44,000 people live
within a 2 mile radius of the Site.
2
-------
Three main topographic and geologic features exist at the
Sharon Steel Site: the Jordan River Floodplain (draining the
entire valley area), terraces from the Great Salt Lake/Lake
Bonneville System, and artifacts from the mining industry.
Residential areas near the old Sharon Steel mill site but in the
OU2 area lie on the terraces outside of the Jordan River
Floodplain. Most public drinking water supply. wells within 3
miles of the Site use the deep aquifer to service 440,000 people,
though various shallow and deep aquifers are used for domestic,
agricultural and industrial applications.
The Site includes a former milling operation originally
owned and operated by the u.S. Smelting, Refining and Milling
Company (now known as U.V. Industries, Inc.), from 1906 to 197i.
Sharon Steel purchased the OU1 mill site in 1979. In 1982, the
..UtahDep~rtment of Health was notified that local citizens wer~
gathering wind-blown tailings for use in sandboxes and gardens.
An investigation in 1988 revealed that wind-blown tailings,
originating primarily from uncovered deposits at the OU1 mill
site, had contaminated 571 acres of residential property. These
investigations f~und soil concentrations which exceeded the
action levels for lead and arsenic {sOO ppm and 70 ppm,
respectively) over roughly 142 acres of the approximately 571-
acre residential contaminated area.
The S~aron Steel Site, including both the mil~ site (OU1)
and qff-site soils contaminat~d area (OU2), was proposed for the.
Superfund National priorities List (NPL) in 1984 and became final
on August 28, 1990. As a result of extensive public comment, EPA
decided to divide the Sharon Steel Site into two operable units
(OUs), with OU1 referring to. ground water, the mill site, and its
tailings, and OU2 referring to the residential soils contaminated
by wind-blown tailings. The Feasibility Study and Proposed Plan
for OU2 were completed and issued on June 6, 1990, and the ROD
signed on September 24, 1990.
The selected remedy presented. in the ROD for OQ2 is the
first of a two-step remedy, addressing the most immediate threat
to public health. This first phase consists of excavating
contaminated soils from the residential areas and temporarily
placing these soils at the mill site (OU1). A final remedy for
these soils, along with the existing mill site soils, will be
addressed by a future ROD for the mill site (OU1). Excavation is
triggered in residential areas by soils containing lead and
arsenic concentratipns exceeding 500 ppm and 70 ppm,
respectively. Clean soils will be placed in the excavated areas,
graded to the original ground surface contour, and properties.
relandscaped. Following outdoor cleanup, homes will be cleaned
to remove household dust potentially contaminated with lead and
arsenic. .
Institutional controls will be implemented to provide
3
-------
special provisions for future construction when removing or
replacing existing sidewalks, driveways, foundations, etc. which
may have contaminated soils beneath them. In addition, the'
original selected remedy called for removal of existing garden
soils with, lead concentrations greater than 200 ppm and arsenic
concentrations greater than 70 ppm. Institutional controls would
also have been used to regulate the installation of new gardens.
DESCRIPTION OP SIGNIPICANT DIFPERENCE
The selected remedy for OU2, as'described in section 9,
component D of the ROD, requires the removal of existing garden
soils down to 18 inches for'soils with concentrations of lead.
greater than 200 ppm and arsenic greater than 70 ppm. The remedy
also r:equires the emp~oyrnent of institutional controls to
regulate the installation of new gardens in these areas. .
The UDEQ, in conjunction with the Bureau of Reclamation,
conducted soil sampling in Midvale to determine which properties
would require soil removal and replacement based on the action
levels of 500 ppm lead and/or 70 ppm arsenic and thus, the
boundaries for complete soil removal activities in OU2. Based on
the original action levels for garden soils presented in the ROD,
many properties outside the 500 ppm lead and/or 70 ppm arsenic
boundary would be sUbj~ct to soil excavation and institutional
. controls. for garden areas only. . . .
AŁter issuance of the Rob, the EPA regional toxicologists
conducted a review of the past scientific rationale for the
action level of 200 ppm lead for lead-contaminated garden soils
presented in the Baseline Risk Assessment (BRA). This review
determined that, based on current toxicological kriowledge and
conditions at the Sharon Steel (OU2) Site, residential properties
with garden soils' having lead concentrations between 200 ppm and
500 ppm do not present significantly different health risks when
. compared to garden. soils having lead concentrations of 500 ppm~
Based on soil sampling results from properties in Midvale,
the cleanup levels required by the ROD for OU2, and the review of
BRA studies which set these levels for OU2, EPA and UDEQ have
. decided not to include properties with lead levels in gardens of
less than 500 ppm within the OU2 boundaries for remedial action.
The EPA and UDEQ do not intend to implement any soil removal or
garden restrictions for areas outside of the 500 ppm boundary as
established during Remedial Design. TheEPA and UDEQ have
therefore decided to delete component D, along with its
associated references, from the selected remedy presented in
section 9 of the ROD.
Deletion of component D will reduce the scope and cost of
the selected remedy without affecting that remedy's original goal
4
-------
of removing soils which pose significant health risks. All
soils, including gardens,' which have lead concentrations
exceeding 500 ppm, and/or arsenic concentrations exceeding 70 ppm
will be remediated in accordance with the ROD. By reducing the
scope and cost of the remedial action this modification is
'considered a significant, but non-fundamental change to the
original remedy and affords essentially the' same level of public
health protection from excessive exposure to and effects of lead
in soil. .
STATCTOR.Y Dg.~'.l!i1U(mAT:ION'S
. Based on new information provided concerning the lack of
significant health risks posed by garden soils having lead
concentrations between. 200 ppm and 500 ppm and the change mad~ to
the selected remedy regarding removal of these soils and .
institutional controls placed on new gardens in these areas, the
EPA and UDEQ believe that the revised remedy remains protective
of human health. In addition, the EPA and UDEQ believe that the
revised remedy complies with state and Federal requirements that
are applicable or relevant and appropriate to this remedial
action, is cost-effective, and utilizes per.manent solutions and
alternative treatment technologies to the max~ extent
practicable for this 'site.
NOT:ICB OF AVA:ILAB:IL:ITY.
Notice is hereby made that this ESD and its supporting
documentation is being made available through the Administrative
Record file. The Administrative Record for this ESD is available
for review at the previously listed locations. .
5
-------
EXPLANATION OP SIGNIFICANT DIPPBRENCES
RECORD OP DECISION (ROD). - SHARON STEEL (OtT2) SITE
DBCLARATIONS
Considering the new information that has been developed and
the changes that have been made to the selected remedy chosen in
the original ROD of September 24, 1~90, BPA and UDBQ 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 max~ extent practicable for this site.
Da~Ł;1y
------- |