DSHW-2010-053465 - 0901a068801e3257 (5)

July 27, 2010

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

RE: Spring 2010 Groundwater Monitoring
Human Health Risk Assessment for Groundwater
ATK Launch Systems - Promontory Facility
UTD009081357

Dear Mr. Gosen:

Earlier this year, the Division of Solid and Hazardous Waste evaluated ATK’s Spring 2010 Groundwater Monitoring Plan. The Division informally agreed to the plan and ATK initiated the
sampling effort. The Division has also been working with ATK on a Human Health Risk Assessment (HHRA) for groundwater. The HHRA was reviewed and a document containing comments and
questions was sent to ATK on December 1, 2009. Based on this review and more recent communications regarding exposure units, the Division has compiled the groundwater data that exists
that would be beneficial for use in the HHRA. Enclosed with this letter is a table that summarizes this existing data. Also enclosed is the list of wells the Division recommended that
ATK sample as part of the Spring 2010 sampling effort to provide additional data for areas where it is needed. The Division recommended the listed wells in order to move the HHRA forward.

In addition, ATK and the Division have had discussions on the historic detections of total chromium at the facility. On June 30, 2010, ATK submitted the document “Lines of Evidence
for Sources of Chromium and Risks at ATK Promontory Monitoring Wells.” The Division has completed its review of this document. In general, we are in agreement that the total chromium
widely detected at the facility is likely from corrosion of stainless steel well screens and parts and most likely exists as the trivalent species. In a telephone conversation with
Paul Hancock on July 15, 2010, it was agreed that ATK would sample three or four of the wells that historically have shown high values of total chromium for hexavalent chromium. These
tests would be conducted in order to confirm ATK’s findings as described in the document submitted and to resolve the chromium issue for the HHRA.

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

Sincerely,

ORIGINAL DOCUMENT SIGNED BY SCOTT T. ANDERSON ON 7/26/2010

Scott T. Anderson, Director

STA\JV\tjm

Enclosure

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

Evaluation of Available Groundwater Data for the HHRA by Exposure Unit

Exposure Unit Center of Plume or Source Wells for TCE # of sample results since Spring 2004 Center of Plume or Source Wells for ClO4 # of sample results since Spring 2004 1. E519
Lab Sump
(Northern Plume) M508-3
M508-4
M508-B1 7
7
6 J-1
J-7
LF-1 13
17
2 2. E585 Lab Sump P-6
P-7 2
2 P-7 2 3. Perched Zone East of Regional Aquifer A-3
B-9
D-1 4
4
1 A-3
B-10
M39B1 4
1
8 4. M-136 Burn Grounds (Regional Plume) A-4
A-8
B-2D
B-3
C-3
E-9 0
2
0
1
1
4 D-4
D-5
D-6 2
2
2 5. M-153 Drain Field (near facility boundary) B-6
G-2 1
2 B-6
G-2 1
2 6. Plant 3 Plume TCC3
X-4 8
6 TCC3
X-4 8
6 7. Off-site Plume EW-6 10 EW-6 10 8. Shotgun Spring Shotgun Spring 9 Shotgun Spring 9 9. Pipe Spring Pipe Spring 9 Pipe Spring 9 10. Fish Spring Fish Spring 9 Fish Spring 9 11.
Horse Spring Horse Spring 9 Horse Spring 9 12. Fork Spring Fork Spring 1 Fork Spring 1 13. Connor Spring Connor Spring 1 Connor Spring 1
Suggested wells and springs to sample for VOCs and perchlorate Spring, 2010 for inclusion in the risk assessment:
A-4 7. C-3 13. LF-1
A-8 8. D-1 14. P-6
B-2D 9. D-4 15. P-7
B-3* 10. D-5 16. Fork Spring
B-6 11. D-6 17. Connor Spring
B-10 12. G-2

* could sample well B-3 for RDX as well for data to add to Fall, 2008 result

July 27, 2010
Page 2
TN201000584

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
TN201000584 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
Scott T. Anderson
Director