DSHW-2004-008251 - 0901a068801613ce (4)

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

RE: Groundwater Flow and Contaminant Transport Model Work Plan for the ATK Thiokol Inc. – Promontory Facility, EPA I.D. #UTD009081357

Dear Mr. Hancock:

The Division of Solid and Hazardous Waste has reviewed the revised Groundwater Flow and Contaminant Transport Model Work Plan that was submitted to our office on August 25, 2004. Comments
on the original Work Plan were generated by the Division and e-mailed to John Holladay on July 28, 2004.

The Division’s comments are appropriately addressed in the revised Work Plan; therefore, the Work Plan is hereby approved. There are however, a few issues that were not included with
the e-mailed comments, regarding the geology and hydrogeology of the site as described in the Work Plan. These issues are briefly discussed below since they may impact the conceptual
site model for the site. It is not necessary, however, to revise the Work Plan.

( In Chapter Two, page 2-1, it is stated that the Great Blue Limestone Formation is exposed at the ATK site and is found in several of the facility borings. In addition, it is stated
that the Manning Canyon Shale conformably overlies the Great Blue Limestone. This interpretation of the site geology is at odds with the USGS Geologic Map of the Lampo Junction Quadrangle,
Box Elder County, Utah (Map 136, Utah Geological Survey, 1991).

According to the USGS map, the limestone unit exposed at the site is the Oquirrh Formation. Its estimated thickness in the area of the M-136 Burn Grounds is 600 feet, although the
formation thickness diminishes toward the east. This may be significant since the USGS interpretation puts the Manning Canyon Shale (a possible confining layer or aquitard) below the
limestone unit at the site instead of above it as described in the Work Plan.

( In Chapter Three, page 3-1, it is stated that at the northern part of the facility, the potentiometric surface is approximately 100 feet below the elevation of Blue Creek, implying
that it is a losing stream. Please note that at well H-5 (south of the rocket display) it appears that the potentiometric surface is only approximately 20 feet below the elevation of
Blue Creek. This raises the question of whether Blue Creek continues to be a losing stream as it flows south.

The Division requests that Thiokol or EarthFax notify Helge Gabert once the model is set up and convergence of it is achieved so that run simulations may be observed. Please call Jeff
Vandel at 538-9413 if you have any questions. Thank you for your cooperation.

Sincerely,

ORIGINAL DOCUMENT SIGNED BY DENNIS R. DOWNS ON 10/14/04

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

DRD\JV\ts

c: Linda Bowling, USEPA Region VIII

TN200401143
File to: ATK Thiokol Inc. – Promontory

October 14, 2004
Page 2

State of Utah

Department of Environmental Quality

Dianne R. Nielson, Ph.D.
Executive Director

DIVISION OF SOLID & HAZARDOUS WASTE
Dennis R. Downs
Director
OLENE S. WALKER
Governor

GAYLE F. McKEACHNIE
Lieutenant Governor

October 14, 2004

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