DSHW-2010-052354 - 0901a068801e2c84

David P. Gosen, P.E.
Director, Environmental Services
ATK Launch Systems – Promontory
P.O. Box 707
Brigham City, UT 84302-0707

RE: Groundwater Model Recalibration
ATK Launch Systems - Promontory Facility
UTD009081357

Dear Mr. Gosen:

The Division of Solid and Hazardous Waste has completed its review of the recalibrated groundwater model that was submitted to this office in November, 2009. The updated model incorporates
the two new boundary wells X-5 and J-9, and the current contaminant concentrations that were detected in the D series wells, as requested by the Division.

Groundwater model updates are required by Post Closure Permit Condition IV.E.4 when new groundwater surface or contaminant data is obtained that would make a discernable difference from
the previous calibration. The recalibrated model is hereby approved. Please use the latest version of the model when calculating future exposure point concentrations for the ecological
and human health risk assessments.

If you have any questions, please contact Jeff Vandel at [phone]. Thank you for your cooperation.

Sincerely,

ORIGINAL DOCUMENT SIGNED BY DENNIS R. DOWNS ON 2/23/2010

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

DRD\JV\tjm

c: Paul Hancock, ATK Launch Systems
Blair Palmer, ATK Launch Systems
Lloyd C. Berentzen, MBA, Health Officer, Bear River Health Department

February 23, 2010

288 North 1460 West • Salt Lake City, UT

Mailing Address: P.O. Box 144880 • Salt Lake City, UT 84114-4880
Telephone [phone] • Fax [phone] • T.D.D. [phone]
www.deq.utah.gov
TN201000175 Printed on 100% recycled paper

State of Utah

GARY HERBERT
Governor

GREG BELL
Lieutenant Governor

Department of Environmental Quality

Amanda Smith
Executive Director

DIVISION OF SOLID AND HAZARDOUS WASTE
Dennis R. Downs
Director