DSHW-2016-004463 - 0901a068805fb625

DSHW-2016-004463 195 North 1950 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
Printed on 100% recycled paper
State of Utah

GARY R. HERBERT
Governor

SPENCER J. COX
Lieutenant Governor
Department of
Environmental Quality

Alan Matheson
Executive Director

DIVISION OF WASTE MANAGEMENT
AND RADIATION CONTROL
Scott T. Anderson
Director

February 16, 2016

George Gooch, Manager
Environmental Services
ATK Launch Systems – Promontory
P.O. Box 707
Brigham City, UT 84302-0707

RE: Storm Water Management Plan for M-136 and M-225
ATK Launch Systems – Promontory Facility
UTD009081357

Dear Mr. Gooch:

The Division of Waste Management and Radiation Control has completed its review of ATK’s response
to comments and revised Storm Water Management Plan for the M-136 and M-225 Treatment Facilities.
The response to comments and revised Storm Water Management Plan was submitted after the Division
reviewed the original Plan that ATK submitted in accordance with Permit Condition IV.H.4. in
April, 2011.

Significant work, including re-grading of drainage ditches, revision of storm drainage calculations,
vadose zone modeling and refined groundwater modeling was completed by ATK in an effort to address
the Division’s concerns regarding the increasing trend in perchlorate concentrations that were identified
in wells C-1 and D-4. The Division considers the proper management of storm water to be an important
aspect of ensuring that continued operations at the burn grounds do not contribute to the existing
groundwater contamination at the facility.

The Division is generally in agreement with ATK’s responses to its comments on the original Plan with
the exception of the response to our concern regarding the use of the HYDRUS model when the
unsaturated zone consists of fractured bedrock. The Division agrees that fractured bedrock can act as a
barrier to water movement in the vadose zone, but this barrier is dependent on fracture size, orientation
and other factors. Dissolution cavities and fault zones have been observed in the local carbonate rocks
at the facility. Due to the presence of these features, the Division is not convinced that flow barriers will
obstruct percolation of water through the vadose zone and still questions the results of the HYDRUS
modeling.
(Over)

Therefore, it appears that the answer to the question of whether precipitation can percolate through the
vadose zone to groundwater at the site is unknown.

Based on groundwater monitoring results for wells C-1 and D-4, perchlorate concentrations have been
decreasing since the fall of 2012 sampling event. The Division therefore believes that the best course of
action at this point is to continue monitoring these and other wells in the vicinity and continue
implementing the best management practices at the burn grounds to prevent the potential for
contaminating soil or groundwater.

Thank you for your staff’s efforts on this issue. If you have any questions, please call Jeff Vandel at
[phone].

Sincerely,

Scott T. Anderson, Director
Division of Waste Management and Radiation Control

STA/JV/jr

c: Lloyd C. Berentzen, MBA, Health Officer, Bear River Health Department
Grant Koford, EHS, Environmental Health Director, Bear River Health Department
Paul Hancock, ATK Launch Systems
Moye Lin, USEPA Region 8