DSHW-2005-009501 - 0901a06880166067 (4)

Paul Hancock, Manager
Environmental Remediation
ATK Thiokol Inc. – Promontory
P.O. Box 707
Brigham City, UT 84302-0707

RE: Work Plan to Evaluate Ex-Situ Remediation of Perchlorate-Contaminated Soil
ATK Thiokol – Promontory Facility, EPA ID# 009081357

Dear Mr. Hancock:

The Division of Solid and Hazardous Waste has reviewed the Work Plan that was prepared by EarthFax Engineering, Inc. and submitted to our office on July 1, 2005. The objective of this
plan is to assess an ex situ method for the remediation of soil contaminated with perchlorate. The remediation method that will be assessed is anaerobic biodegradation of perchlorate,
promoted by the addition of an organic substrate.

The Thiokol Liquid Thermal Treatment Area (M-136 Burn Grounds) Post-Closure Permit requires that corrective measure alternatives be evaluated for SWMUs needing corrective action. It
is known that several SWMUs exist at the facility where perchlorate has been released to the soil. If this remediation method is determined to be successful, the technology could be
used to remediate perchlorate-contaminated soil at other locations at the facility.

The review of the Work Plan has raised the questions and comments that are listed below. However, the Division believes that work may commence under the Work Plan without complete resolution
of the issues identified in its comments. Therefore, the Work Plan is approved, contingent upon receiving Thiokol’s written responses to these questions and comments within 30 days
of the date of this letter.

In order to avoid confusion, the Division suggests that the project be referred to as a corrective measure pilot test instead of a “treatability study.” A treatability study, as defined
in R315-2-4(e) (which incorporates by reference 40 CFR 260.10), applies to the treatment of hazardous wastes in quantities not to exceed 22,000 pounds. It is stated in the Work Plan
that the contaminated soil is not a hazardous waste, and the quantity of soil to be treated far exceeds the limit for a treatability study.

3.1 Treatability Study Goals

The preliminary remediation goal proposed (55 mg/kg) is appropriate for soil ingestion by a child under a residential land-use scenario. However, the potential for migration of perchlorate
to groundwater needs to be addressed. If remediated soil containing perchlorate is placed into the on-site landfill and the perchlorate migrates to groundwater, other exposure pathways
may exist.

Please determine what the potential is for perchlorate to migrate from soil disposed of in the on-site landfill to groundwater and adjust the preliminary remediation goal if appropriate.

Treatability Study Design

In the second paragraph of this section, it is stated that the perchlorate-impacted soil that will be used in the study was previously excavated. Please give a brief description of
the areas where the soil was excavated, the cause of the release, and the associated SWMU number.

Sampling and Analysis

In the first paragraph of this section, it is stated that selected samples collected during the study (pilot test) will be analyzed for nitrate and sulfate, as well as iron, manganese
and selenium. The Division requests that Thiokol evaluate how the remediation process affects the mobility of metals. If the mobility of metals (e.g. selenium) is significantly increased,
due to changes in pH and, or redox potential of the soil, the potential for degradation of groundwater quality may need to be assessed. This information may be useful if this treatment
technology is used at other sites in the future. It is recommended that the list of metals that will be initially analyzed be expanded to include the metals covered by the method proposed
in Table 1 (6010B). Please give an explanation on how this issue will be addressed.

Residuals Management

In the last paragraph of this section, it is stated that soil that meets the remediation goal will be removed and disposed of at the on-site landfill. Please provide more detail on
how it will be determined that the remediation goal has been met. Will this be determined based on the results of one composite sample consisting of four sub-samples (collected from
two locations) for each biopile?

In addition, it is stated in this paragraph that soil that does not meet the remediation goal will be re-treated as necessary until the goal is met. If additional manure is added to
the biopiles, especially the biopile that will be 60% manure by volume, please keep in mind that dilution is not an acceptable form of treatment. After the remediation goal is met,
it should be clear, based on the concentration of perchlorate remaining in the soil and the amount of manure added, that the perchlorate has been degraded – not just reduced in concentration

due to dilution.

If you have any questions, please contact Jeff Vandel of my staff at [phone].

Sincerely,

ORIGINAL DOCUMENT SIGNED BY DENNIS R. DOWNS ON 8/26/05

Dennis R. Downs, Executive Secretary
Utah Solid and Hazardous Waste Control Board

DRD\JV\ts

c: Lloyd C. Berentzen, M.B.A., Health Officer/Director, Bear River Health Dept.
Nancy Morlock, USEPA Region VIII

File to: ATK Thiokol Inc. - Promontory

August 26, 2005
Page 2

August 26, 2005

TN200501127.doc
288 North 1460 West • PO Box 144880 • Salt Lake City, UT 84114-4880 • phone [phone] • fax [phone]
T.D.D. [phone] • www.deq.utah.gov

State of Utah

Department of Environmental Quality

Dianne R. Nielson, Ph.D.
Executive Director

DIVISION OF SOLID AND HAZARDOUS WASTE
Dennis R. Downs
Director

JON M. HUNTSMAN, JR.
Governor

GARY HERBERT
Lieutenant Governor