DSHW-2004-008274 - 0901a06880160759

INTRODUCTION

This document is an addendum to the M136 Liquid Thermal Treatment Area Post-Closure Permit Application. It supplements or replaces information submitted in Section E of that report.

Ground water monitoring activities have been conducted in accordance and pursuant to stipulations of a Consent Order between Thiokol and the State of Utah, No.s 8502162 and 8606402.

E. GROUNDWATER MONITORING

E-1 Exemption from Ground Water Protection Requirements

Not Applicable.

E-2 The Ground Water Monitoring System

Well Location

A topographic map showing well location and identification is located in Figure E-2.1.

Background and Point-of-Compliance Monitoring Wells

The background monitoring wells are C-6, C-8, and A-10. Wells C-6 and C-8 are upgradient wells. Well A-10 also serves as a background well and may also be upgradient. All other wells
are downgradient. Wells A-2, A-3, A-4, A-5, A-6, A-7, C-1, C-2, B-9 are the point-of-compliance monitoring wells for the M-136 Burning Grounds. Wells A-10, A-2, A-3, and B-9 are completed
in a perched aquifer on the east end of the M-136 burning grounds. The other wells are completed within the "regional" aquifer.

Well Installation

In the fall of 1985, the six original ground water monitoring wells, D-1 through D-6 were installed. The report entitled Ground Water Detection Program M-136 contains all the information
as to the drilling construction of the six monitoring wells. In 1987, ten additional ground water monitoring wells (designated A-1 through A-10) were installed. Nine additional monitoring
wells, C-1 through C-9, were installed on and adjacent to M-136 Burning Area in 1988. Design detail for the D-, A-, and C-series wells may be found in Appendices E-1.6, E-1.7 of the
M-136 Post-Closure Permit Application. In 1989, ten monitor wells, B-1 through B-10, were installed to assess the extent of contamination of ground water south and south-southwest of
the M-136 facility. Ten additional monitor wells, E-1 through E-10 were installed in 1990. Details of these wells are found in Appendix 2.1. This information includes depths of screen
and casing, depth to ground water, filter pack, annular sealing materials, dates of construction, boring logs, and other pertinent data.

Additional wells that have been added to the groundwater monitoring system include: LF-1, LF-2, LF-3, and LF-4, completed in 1993; G-1, G-2, G-3, G-4, G-5, G-6, G-7, and
G-8, constructed in 1996; and H-1, H-2, H-3, H-4, H-5, H-6, H-7, H-8, H-9, and H-10, completed in 2003.

Design and Construction of Wells

D-Series Wells (D-1 through D-6)

These six original ground water monitoring wells were installed in the fall of 1985. The report entitled Ground Water Detection Program M-136 contains all the information as to the
drilling construction of the six monitoring wells. The D-series wells are no longer actively sampled (see Appendix E-2.7 - Sampling Plan).

A-Series Wells (A-1 - A-10)

These ten monitoring wells were drilled using a Chicago Pneumatic (CP) 7000 air rotary rig equipped with an overhead casing hammer and a Chicago Pneumatic RT 1800 table-driven air rotary
rig. The CP 7000 advanced 8-inch-inside diameter (I.D.) steel casing as 7-7/8-inch holes were drilled through the alluvium. The casing was driven to bedrock or until the casing refused
to be driven to the point of driveshoe collapse. The RT 1800 was also used to retrieve the 8-inch steel casing when subsurface conditions were favorable. When the steel casing was
unretrievable the casing was left in place and extra caution was taken to ensure the well was sealed properly to avoid contamination transport. When drilling wells A-4 and A-7, unexpected
problems arose. Well A-4 had a zone in which the bedrock was faulted and the rubble caved in on the drill bit. Well A-4 was stabilized with Portland cement from 40 to 140 feet in depth.
Below 140 feet, ground conditions were stable and the well was completed with the specified hole diameter. Boring logs for each of these wells can be found in Appendix E-1.6 of the
Post-Closure Permit Application.

In well A-7 the eight-inch casing could not be driven past 119 feet. The decision was made to reduce the hole size and case past the problem zone. A seven-inch diameter