DSHW-2006-003308 - 0901a0688013fec9

ATK
ALLIANT TECHSYSTEMS
ATK Thiokol Inc.
P.O. Box 707
Brigham City, UT 84302-0707
Tel [phone]
Fax [phone]
5 June 2006
8200-FY07-021
Mr. Dennis R. Downs, Executive Secretary
State of Ulah
Department of Environmental Quality
Division of Solid and Hazardous Waste
288 N. 1460 W.
P.O.Box 144880
Salt Lake City, Utah 84114-4880
^ UT/ttfDIt^rf'oF
SOLID & HAZARDOUS WASTE
Dear Mr. Downs
ATTENTION: Jeff Vandel
Subject: June 2006 Revision to Report: Results of Post-Excavation Sampling at M-39 and
M-636, incorporating comments froiTi UDSHW dated April 12, 2006. ATK
Thiokol - Promontoi-y Facility, EPA ID #009081357
In a April 12, 2006 letter, your office sent comments regarding the ATK Promontory report
entitled '^Results of Post-Excavation Sampling at M-39 and M636". These comments have been
incorporated in the attached revised version of the report. Please find a copy of the report as well
as a list of the Division's specific comments and responses from ATK.
If you have any questions regarding these responses, please direct them to myself at (435) 863-
3344.
Sincerely
:;vuev/ CCsot
Paul V Hancock, Manager
Environmental Remediation
RESPONSE TO UDSHW COMMENTS
(Letter dated April 12, 2006 from
Dennis R. Downs to Paul Hancock)
UDSWH Comment: Section 2.3. Ecological Risk. The methodology deviates from the
Ecological Risk Assessment Guidance for Superfund (USEPA, 1997) (ERAGS) and UAC
R315-101. No information is provided on the potential receptors and habitats at the site. No
discussion of assessment endpoints, measures of exposure, or measures of effects were
provided. The evaluation of cadmium is acceptable because the USEPA has integrated most of
these factors into the development ofthe soil screening levels. ATK should duplicate the
ecological soil screening levels methodology for silver or evaluate silver consistent with
ERAGS. Some toxicity values for silver are available in the literature (e.g., Los Alamos
National Laboratory Ecorisk Database). ATK should evaluate chemicals without toxicity values
as uncertainties. The uncertainty evaluation should focus on determining if site management
decisions would be affected if toxicity values were available. If adequate toxicity values are
unavailable, a risk assessment to determine appropriate site management may not be possible.
An altemative is to clean the site to background levels.
ATK Response: The ecological risk assessment for cadmium has been revised
accordingly. Additional information is provided concerning site ecological conditions,
toxicity of silver, etc. An uncertainty analysis has also been provided.
UDSHW Comment: Please explain why perchlorate was selected as a chemical of potential
concem for the risk assessment. As shovra in Table 3-1 and 3-2, perchlorate was not detected in
soil and would not be a chemical of potential concem unless the analytical reporting limits
exceed risk-based concentrations.
ATK Response: Perchlorate was included as a contaminant of potential concern based
on comments made by the Division in a letter dated July 25, 2003. The report has been
reorganized to present the sampling results prior to discussing the risks. As a result,
perchlorate was dropped from the list of contaminant of potential concern prior to
presenting the risk assessment.
UDSHW Comment: While the Division does not understand why perchlorate was selected as a
chemical of potential concem, we also fmd the provided rationale for not evaluating perchlorate
in the risk assessment unacceptable. ATK states that perchlorate was not evaluated because the
USEPA has not formally released its evaluation. An uncertainty evaluation may be adequate if
the absence of toxicity values is unlikely to impact site management decisions.
ATK Response: Perchlorate has been dropped as a contaminant of potential concern.
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